Allen_NEBA_CommunityImpactAnalysis_2018115

Community Impact Analysis
of Ash Basin Closure Options
at the Allen Steam Station

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Community Impact Analysis of
Ash Basin Closure Options at the
Allen Steam Station

Prepared on behalf of Duke Energy Carolinas,
LLC

Prepared by

Dr. Ann Michelle Morrison
Exponent
1 Mill & Main Place, Suite 150
Maynard, MA 01754

November 15, 2018

 Exponent, Inc.

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Contents
Page
List of Figures iv
List of Tables v
Acronyms and Abbreviations vii
Limitations ix
Executive Summary x
1 Qualifications 1
2 Assignment and Retention 3
3 Reliance Materials 4
4 Introduction 5
4.1 Site Setting 6
4.2 Closure of the Ash Impoundments at Allen 9
5 Approach to Forming Conclusions 14
5.1 Net Environmental Benefit Analysis 16
5.2 Linking Stakeholder Concerns to NEBA 18
5.3 NEBA Risk Ratings 24
5.4 Risk Acceptability 25
6 Summary of Conclusions 27
7 Conclusion 1: All closure options for the Allen ash basins are protective of
human health. 29
7.1 Private water supply wells pose no meaningful risk to the community around
Allen. 29
7.2 CCR constituents from the Allen ash basins pose no meaningful risk to human
populations. 31
7.3 NEBA – Protection of Human Health from CCR Exposure 35

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8 Conclusion 2: All closure options for the Allen ash basins are protective of
ecological health. 36
8.1 No meaningful risks to ecological receptors from CCR exposure exist under
current conditions or any closure option. 36
8.2 NEBA – Protection of Environmental Health from CCR Exposure 40
9 Conclusion 3: Excavation closure to an offsite landfill creates greater
disturbance to communities. 42
9.1 There is no meaningful risk from diesel emissions to people living and working
along the transportation corridor. 44
9.2 The likelihood of noise, traffic, and accidents from transportation activities is
greater under the offsite excavation closure option. 48
9.2.1 Noise and Congestion 49
9.2.2 Traffic Accidents 49
9.3 NEBA – Minimize Human Disturbance 50
10 Conclusion 4: Both hybrid closure and excavation to an onsite landfill minimize
environmental disturbance. 54
10.1 Excavation closure to an offsite landfill and CIP closure result in a greater
net loss of environmental services than hybrid closure or closure to an onsite landfill. 56
10.2 NEBA – Minimize Environmental Disturbance 60
11 Conclusion 5: Hybrid closure maximizes environmental services. 62
12 References 65

Appendix A Curriculum vitae of Dr. Ann Michelle Morrison, Sc.D.
Appendix B Human Health and Ecological Risk Assessment Summary Update for Allen
Steam Station
Appendix C Exposure Modeling and Human Health Risk Assessment for Diesel Emissions
Appendix D Habitat Equivalency Analysis
Appendix E Net Environmental Benefit Analysis

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List of Figures
Page
Figure 4-1. Map of Allen Station. Reproduced Figure 2-1 of the 2018 CSA Supplement
(SynTerra 2018a). 7
Figure 4-2. Images of various habitat types at Allen, September 5, 2018. 8
Figure 4-3. Elemental composition of bottom ash, fly ash, shale, and volcanic ash. 10
Figure 8-1. Exposure areas evaluated in the 2018 ecological risk assessment update
(SynTerra 2018b). 39
Figure 9-1. Normalized differences between transportation activities under the closure
options. 44
Figure 10-1. Map of habitat types currently present at Allen. 55

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List of Tables
Page
Table 4-1. Ash basin closure options provided by Duke Energy (2018) 12
Table 4-2. Overview of some key logistical differences between closure options for the
Allen ash basins. 12
Table 5-1. Relationships between environmental services and concerns to the local
community associated with CCR and ash basin closure hazards 20
Table 5-2. Associations between objectives for closure and remediation of the Allen
ash basins and environmental services 21
Table 5-3. Matrix of key environmental services, attributes, and comparative metrics
applied in the NEBA 22
Table 5-4. Risk-ranking matrix for impacts and risk from remediation and closure
activities. 25
Table 7-1. Summary of human health risk assessment hazard index (HI) and excess
lifetime cancer risk (ELCR) from SynTerra (2018b) 33
Table 7-2. Summary of relative risk ratings for attributes that characterize potential
hazards to humans from CCR exposure in drinking water, surface water,
groundwater, soil, sediment, food, and through recreation 35
Table 8-1. Summary of relative risk ratings for attributes that characterize potential
hazards to ecological resources from CCR exposure in surface water, soil,
sediment, and food 41
Table 9-1. Summary of offsite transportation logistics associated with each closure
option (Duke Energy 2018) 43
Table 9-2. Hazard indices (HI) and excess lifetime cancer risk (ELCR) from exposure
to diesel exhaust emissions along transportation corridors in south-central
North Carolina. 47
Table 9-3. Comparative metrics for increased noise and congestion and traffic accidents 50
Table 9-4. Summary of relative risk ratings for attributes that characterize potential
hazards to communities during remediation activities. 53
Table 10-1. Summary of NPP DSAYs for closure options 60
Table 10-2. Percent impact of ash basin closure options. 61

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Table 10-3. Summary of relative risk ratings for habitat changes that affect provision of
environmental services. 61
Table 11-1. NEBA for closure of the ash basin at Allen. 64

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Acronyms and Abbreviations
AADT annual average daily traffic
ASOS Automated Surface Observing S ystem
AWQC Ambient Water Quality Criterion
BCF bioconcentration factor
CAMA North Carolina Coal Ash Management Act
CAP corrective action plan
CCR coal combustion residuals
CCR Rule EPA Coal Combustion Residuals Rule of 2015
CERCLA Comprehensive Environmental Response, Compensation, and Liability
Act
CIP cap in place
COI constituent of interest
COPC chemical of potential concern
CSA comprehensive site assessment
DPM diesel particulate matter
Duke Energy Duke Energy Carolinas, LLC
DSAY discounted service acre-year
ELCR excess lifetime cancer risk
EPA U.S. Environmental Protection Agency
EPC exposure point concentration
ERA ecological risk assessment
GIS geographic information system
HEA habitat equivalency analysis
HHRA human health risk assessment
HI hazard index
HQ hazard quotient
LOAEL lowest-observed-adverse-effects level
MOVES Mobile Vehicle Emissions Simulator
NEBA net environmental benefit analysis
NCDEQ North Carolina Department of Environmental Quality
NCDOT North Carolina Department of Transportation
NOAA National Oceanic and Atmospheric Administration
NOAEL no-observed-adverse-effects level
NPDES National Pollutant Discharge Elimination System
NPP net primary productivity
NRDA natural resource damage assessment
OSAT-2 Operational Science Advisory Team-2
PBTV provisional background threshold value
RAB retired ash basin
RCRA Resource Conservation and Recovery Act
REL reference exposure level
RfD reference dose

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SOC Special Order by Consent
TRV toxicity references value
TVA Tennessee Valley Authority

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Limitations
This expert report sets forth my conclusions, which are based on my education, training, and
experience; field work; established scientific methods; and information reviewed by me or
under my direction and supervision. These conclusions are expressed to a reasonable degree of
scientific certainty. The focus of this report is on local community impacts. I have, therefore, not
attempted to evaluate broader environmental impacts, such as impacts from greenhouse gas
emissions, that would be associated with each closure option.
The conclusions in this report are based on the documents made available to me by Duke
Energy Carolinas, LLC (Duke Energy) or collected as part of my investigation. I reserve the
right to supplement my conclusions if new or different information becomes available to me..

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Executive Summary1
In 2015, the U.S. Environmental Protection Agency (EPA) issued a rule called the “Hazardous
and Solid Waste Management System; Disposal of Coal Combustion Residuals [CCR] from
Electric Utilities” (CCR Rule), which, among other things, regulates closure of coal ash
impoundments in the United States. Closure of coal ash impoundments in North Carolina is
further regulated by the North Carolina Coal Ash Management Act of 2014 (CAMA) as
amended by H.B. 630, Sess. L. 2016-95. Under both the North Carolina CAMA and the federal
CCR Rule, there are two primary alternatives for closure of an ash impoundment:
 “Cap in place” (CIP) closure involves decanting the impoundment and
placing a low-permeability liner topped by appropriate cap material, soil, and
grass vegetation over the footprint of the ash to restrict vertical transport of
water through the ash, as well as a minimum of 30 years of post-closure care,
which requires the implementation of corrective action measures if and as
necessary;
 Excavation closure involves decanting the impoundment, excavating all ash
in the basin, transporting the ash to an appropriate, permitted, lined landfill,
and restoring the site.
Duke Energy’s Allen Steam Station (Allen or Allen Station) has one unlined inactive ash basin
and one unlined active ash basin. Within the footprint of the inactive ash basin are ash storage
areas, structural fill areas, and the double-lined Retired Ash Basin (RAB) Ash Landfill
(SynTerra 2018a).
Duke Energy has evaluated four representative types of closure for the ash basins at Allen: CIP;
excavation to a new onsite landfill (Excavation A); excavation to a new offsite landfill within 50
miles of Allen (Excavation B); and a hybrid closure, which involves excavating and
consolidating ash within the basin footprint to reduce the spatial area of CIP closure (Duke

1 Note that this Executive Summary does not contain all of the technical evaluations and analyses that support the
conclusions. Hence, the main body of this report is at all times the controlling document.

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Energy 2018). The administrative process for selecting an appropriate closure plan for the ash
basins is ongoing.
The purpose of my report is to examine how the local community’s environmental health and
environmental services2 are differently affected by each closure option as currently defined and
to evaluate these differences in a structured framework that can support decision-making in this
matter.
Environmental Decision-Making
Environmental decision-making involves understanding complex issues that concern multiple
stakeholders. Identifying the best management alternative often requires tradeoffs among
stakeholder values. These tradeoffs necessitate a transparent and systematic method to compare
alternative actions and support the decision-making process. My analyses in this matter have
used a net environmental benefit analysis (NEBA) framework (Efroymson et al. 2003, 2004) to
compare the relative risks and benefits from either CIP closure, excavation closures, or a hybrid
CIP and excavation closure of the ash basins at the Allen Station. The NEBA framework relies
on scientifically supported estimates of risk to compare the reduction of risk associated with
chemicals of potential concern (COPCs)3 under different remediation and closure alternatives
alongside the creation of any risk during the remediation and closure, providing an objective,
scientifically structured foundation for weighing the tradeoffs between remedial and closure
alternatives.
Despite the scientific basis of the risk characterization process used in NEBA, stakeholders in
any environmental decision-making scenario may place different values on different types of
risk (i.e., stakeholders may have different priorities for the remediation and closure). NEBA
does not, by design, elevate, or increase the value of, any specific risk or benefit in the

2 Environmental services, or ecosystem services, are ecological processes and functions that provide value to
individuals or society (Efroymson et al. 2003, 2004).
3 COPCs are “any physical, chemical, biological, or radiological substance found in air, water, soil or biological
matter that has a harmful effect on plants or animals”
(https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?de
tails=&glossaryName=Eco%20Risk%20Assessment%20Glossary).

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framework. The purpose of NEBA is to simultaneously and systematically examine all tradeoffs
that affect the services provided to humans and the ecosystem by the environment under
remediation and closure, allowing decision-makers to more fully understand all potential
benefits and risks of each alternative.
NEBA and similar frameworks have been used extensively by regulatory agencies such as the
National Oceanic and Atmospheric Administration (NOAA) and EPA to support evaluating
tradeoffs in mitigation (e.g., NOAA 1990), remediation (e.g., U.S. EPA 1988, 1994), and
restoration (e.g., NOAA 1996). The National Environmental Policy Act (40 CFR § 1502) relies
on a structured framework to conduct environmental assessments and produce environmental
impact statements; these analyses evaluate potential adverse effects from development projects
and identify alternatives to minimize environmental impacts and/or select mitigation measures.
Natural resource damage assessment (NRDA) utilizes a structured process to estimate
environmental injury and lost services and identify projects that restore the impacted
environment and compensate the public for the lost environmental services (e.g., NOAA 1996).
The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)
remedial investigation/feasibility study process uses a set of evaluation criteria to identify
remediation projects for contaminated Superfund sites that meet remediation objectives for
effectiveness, implementability, and cost (U.S. EPA 1988). Within the Superfund Program, EPA
has also recognized the importance of remediation that comprehensively evaluates cleanup
actions “to ensure protection of human health and the environment and to reduce the
environmental footprint of cleanup activities to the maximum extent possible” (U.S EPA 2010).
The Tennessee Valley Authority (TVA) recently used a structured framework to compare the
impacts and benefits of ash basin closure alternatives at ten of its facilities (TVA 2016).
Through a NEBA-like analysis, the TVA identified “issue areas,” such as air quality,
groundwater, vegetation, wildlife, transportation, and noise and created a summary table that
provided a side-by-side comparison of the impacts of “no action,” “closure-in-place,” and
“closure-by-removal” actions. As a result of this analysis, TVA identified “closure-in-place” as
“its preferred alternative” for all ten facilities stating, “[t]his alternative would achieve the
purpose and need for TVA’s proposed actions and compared to Closure-by-Removal with less

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environmental impact, shorter schedules, and less cost” (TVA 2016). Closure of the Allen ash
basins presents similar “issue areas” that can benefit from a similar, systematic analysis of net
benefits resulting from closure activities.
Linking Stakeholder Concerns to NEBA
To better understand stakeholder concerns related to closure of the ash basins at Allen, I
reviewed written communications about ash pond closure plans for the Allen Station submitted
to and summarized by the North Carolina Department of Environmental Quality (NCDEQ)
(NCDEQ 2016). From this review, I identified the following categories of stakeholder concerns:
 Drinking water quality
 Groundwater quality
 Surface water quality
 Fish and wildlife
 Maintaining property value
 Preservation of natural beauty
 Recreational value
 Swimming safety
 Failure of the ash impoundment
 Risk created by the closure option outweighing risk from contamination.
The primary concerns expressed by community stakeholders involve perceived risks from
exposure to CCR constituents that could negatively affect environmental services that benefit
the local community: provision of safe drinking water and food, safe recreational enjoyment
(hunting, fishing, swimming), and protection of natural beauty and biodiversity.4 Potential
hazards to the community associated with closure activities include physical disturbance of
existing habitats; air pollution from diesel emissions resulting from transportation activities; and
traffic, noise, and accidents that could result in property damage, injuries, and fatalities. Table

4 Biodiversity is the variety of plants and animals present at a location. Protection o f biodiversity refers to
provision of habitat and related functions capable of sustaining biological populations.

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ES-1 links concerns over CCR exposure and potential hazards created by ash basin closure to
environmental services that could be affected by closure activities.

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xv
Table ES-1. Relationships between environmental services and concerns to the local community associated with CCR
and ash basin closure hazards
Environmental Services
Safe drinking
water quality
Safe surface
water quality
Safe air
quality
Safe food
quality
Protection of
biodiversity
Recreation Natural
beauty
Safe community
environment
CCR Concerns
Drinking water
contamination
X X X
Groundwater contamination X X X
Surface water
contamination
X X X X X X X
Fish/wildlife contamination X X X X X
Contamination impacting
property value
X X X X X X X
Contamination impacting
natural beauty
X X X
Contamination impacting
recreational enjoyment
X X X X X
Contamination impacting
swimming safety
X X X X
Failure of the ash
impoundment
X X X X X X X
Closure Hazards
Habitat loss X X X X X
Contamination of air X X X X
Noise, Traffic, Accidents X X

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In recognition of the potential discrepancy between stakeholder priorities and the broad and
balanced treatment of service risks and benefits in NEBA, I organized the NEBA analysis
around the following five objectives for ash basin closure that recognize local stakeholder
concerns while being consistent with the methods and purpose of NEBA:
1. Protect human health from CCR constituent exposure
2. Protect ecological health from CCR constituent exposure
3. Minimize risk and disturbance to humans from closure
4. Minimize risk and disturbance to the local environment from closure
5. Maximize local environmental services.
In my analysis, I linked environmental services to the local community that could be potentially
impacted by ash basin closure and the identified objectives of ash basin closure, and I identified
attributes and comparative metrics5 that characterize the condition of the environmental services
(Efroymson et al. 2003, 2004).
I used human health attributes (e.g., risk to onsite construction workers, risk to offsite
swimmers) and risk quotients (hazard index [HI], excess lifetime cancer risk [ELCR]) to
evaluate whether there would be a potential impact to environmental services related to safe
water, air, and food under each ash basin closure option. I also used human health attributes to
evaluate whether there would be an impact to air quality during closure activities. I used
ecological health attributes (e.g., risk to birds, mammals) and risk quotients (hazard quotients
[HQs]) to evaluate whether there would be a potential impact to environmental services related
to safe surface water and food and protection of biodiversity and natural beauty under the ash
basin closure options. I evaluated risk and disturbance associated with traffic and accidents
using transportation metrics and trucking logistics (e.g., number of truck miles driven)
associated with each closure option to evaluate potential impacts to community safety. I used

5 For purposes of this analysis, an attribute is a feature that characterizes environmental services and may be
impacted by a closure option. Comparative metrics are features of the attribute (e.g., risk quotients, acreage of
habitat) that can be measured and compared between closure options.

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net primary productivity (NPP)6 and discounted service acre-years (DSAYs)7 to characterize
differences in the environmental services that derive from habitats (e.g., protection of
biodiversity, natural beauty) and that would be impacted by ash basin closure activities. Finally,
I assembled all attributes, services, and objectives within a full NEBA to examine which of the
closure options best maximizes environmental services for the local community. The metrics I
used are scientifically appropriate and commonly applied metrics to evaluate risk to humans and
the environment (U.S. EPA 1989, 1997, 2000; NHTSA 2016) and to quantitatively measure
differences in environmental services associated with impact and restoration (Dunford et al.
2004; Desvousges et al. 2018; Penn undated; Efroymson et al. 2003, 2004).
Of note, my analysis did not consider the risks involved with onsite construction activities. For
example, I did not attempt to evaluate occupational accidents created by onsite construction and
excavation. Nor did I attempt to evaluate emissions associated with onsite construction
activities. Finally, I did not attempt to consider the risk created by disturbing the ash basin and
exposing it to the elements during excavation activities.
Some stakeholders also expressed concern over safety of the ash impoundment dam (NCDEQ
2016). The most recent dam safety report produced by Shield Engineering, Inc. and submitted to
NCDEQ indicates “the construction, design, operation, and maintenance of the CCR surface
impoundment have been sufficiently consistent with recognized and generally accepted
engineering standards for protection of public safety and the environment” (Huggins et al.
2018).

6 NPP represents the mass of chemically fixed carbon produced by a plant community during a given time
interval. It reflects the rate at which different ecosystems are able to sequester carbon, which is related to
mitigating climate change (https://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD17A2_M_PSN).
7 DSAYs are derived from habitat equivalency analysis (HEA). HEA is an assessment method that calculates
debits based on services lost and credits for services gained from a remediation action (Dunford et al. 2004;
Desvousges et al. 2018; Penn undated). A discount rate is used to standardize the different time intervals in
which the debits and credits occur, and in doing so, present the service debits and credits at present value. The
present value of the services is usually expressed in terms of discounted service acre-years of equivalent habitat,
or DSAYs, which provide a means to compare the different service levels of affected habitat acres (Dunford et
al. 2004; Desvousges et al. 2018; Penn undated).

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Four possible options for closure of the ash basins at Allen were identified by Duke Energy and
summarized in (Table ES-2). I used these options in the NEBA to examine how different
closure possibilities impact environmental services to the local community.
Table ES-2. Allen ash basin closure options provided by Duke Energy (2018)
Closure Option Description Closure Duration
(years)a
Construction
Duration
(years)b
CIP CIP 9 6
Excavation A Excavate to new onsite landfill 22 18
Excavation B Excavate to new offsite landfill within
50 miles of Allen
20 17
Hybrid Partially excavate to consolidate ash
and CIP consolidated ash
10 7
a Includes pre-design investigation, design and permitting, site preparation, construction, and site restoration.
b Includes only site preparation, construction, and site restoration.
NEBA Risk Ratings
NEBA organizes environmental hazard and benefit information into a unitless metric that
represents the degree and the duration of impact from remediation and closure alternatives. One
approach to structure this analysis is to create a risk-ranking matrix that maps the proportional
impact of a hazard (i.e., risk) with the duration of the impact, which is directly related to the
time to recovery (Robberson 2006). The risk-ranking matrix used for this application of NEBA
is provided in Table ES-3. In this application, the matrix uses alphanumeric coding to indicate
the severity of an impact: higher numbers and higher letters (e.g., 5F) indicate a greater extent
and a longer duration of impact. Shading of cells within the matrix supports visualization of the
magnitude of the effect according to the extent and duration of impact.8 When there is no
meaningful risk, the cell is not given an alphanumeric code. Relative risk ratings for each
attribute and scenario examined were assembled into objective-specific summaries to compare
the net benefits of the closure options. All closure options in the NEBA were evaluated against
current conditions as a “baseline” for comparison.

8 Categories and shading as defined in the risk-ranking matrix are based on best professional judgment and used
for discussion of the relative differences in relative risk ratings. Alternative risk matrices and resulting NEBA
classifications are explored in Appendix E.

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Table ES-3. Risk-ranking matrix for impacts and risk from closure activities.
Darker shading and higher codes indicate greater impact.

Duration of Impact (years)
16-25
(5)
10–15
(4)
5–9
(3)
1–4
(2)
<1
(1) % Impact No meaningful risk -- -- -- --
<5% (A) 5A 4A 3A 2A 1A
5–19% (B) 5B 4B 3B 2B 1B
20–39% (C) 5C 4C 3C 2C 1C
40–59% (D) 5D 4D 3D 2D 1D
60–79% (E) 5E 4E 3E 2E 1E
>80% (F) 5F 4F 3F 2F 1F
NEBA analysis of possible closure options for the ash basin at Allen helps both Duke Energy
and other stakeholders understand the net environmental benefits from the closure option
configurations that were examined. If a closure option that is preferred for reasons not
considered in the NEBA does not rate as one of the options that best maximizes environmental
services to the local community, closure plans for that option can be re-examined, and
opportunities to better maximize environmental benefits can be identified (e.g., including an
offsite habitat mitigation project to offset environmental services lost from habitat alteration).
The NEBA can then be re-run with the updated plan to compare the revised closure plan with
other closure options.
The following is a summary of my conclusions and supporting analyses, which are structured
around the five objectives identified above.
Conclusion 1: All closure options for the Allen ash basins are
protective of human health.
The first objective for ash basin closure, to protect human health from CCR constituent
exposure, is represented by environmental services that provide safe drinking water, safe
groundwater, safe surface water, safe food consumption, and safe recreation. For purposes of the
NEBA, these safety considerations were evaluated based on the following:

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1. Provision of alternative permanent drinking water supplies to private well
water supply users within a 0.5-mile radius of the Allen ash basin compliance
boundary (Holman 2018);
2. Concentrations of CCR constituents of interest (COIs)9 in drinking water
wells that could potentially affect local residents and visitors, as characterized
by HDR (2015a) and SynTerra (2018a) in the Comprehensive Site
Assessment (CSA); and
3. Risk to various human populations from CCR exposure, as characterized in
the updated human health and ecological risk assessment conducted by
SynTerra (2018b; Appendix B).
Based on these analyses, no CCR impacts to drinking water and no meaningful risk to
humans from CCR exposure were found under current conditions10 or
under any closure option. Using the NEBA framework and relative risk
ratings, these results are summarized in

9 COIs are constituents relevant to analysis of potential exposure to CCR constituents but are not necessarily
associated with risk to human or ecological receptors.
10 SynTerra’s updated human health risk assessment (HHRA) considered only potential exposure pathways that
currently exist and could remain after ash basin closure under any closure option. Any potential risk currently
associated with seeps (or areas of wetness [AOWs]) at Allen was not evaluated in the HHRA or considered in this
analysis because any risk resulting from seeps will be eliminated, reduced, or mitigated per the court-enforceable
Special Order by Consent (SOC) that Duke Energy entered with the North Carolina Environmental Management
Commission on April 18, 2018 (EMC SOC WQ S17-009; See Section 4.24.2). The SOC requires Duke Energy to
accelerate the schedule for decanting the ash basin to “substantially reduce or eliminate” seeps that may be
affecting state or federal waters; the SOC also requires Duke Energy to take appropriate corrective actions for any
seeps remaining after decanting is complete to ensure the remaining seeps are managed “in a manner that will be
sufficient to protect public health, safety, and welfare, the environment, and natural resources” (EMC SOC WQ
S17-009).

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Table ES-4 within the objective of protecting human health from exposure to CCR constituents.

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Table ES-4. Summary of relative risk ratings for attributes that characterize potential
hazards to humans from CCR exposure in drinking water, surface water,
groundwater, food, and recreation
Objective Protect Human Health from CCR
Hazard Exposure to CCR Potentially Affected Populations Local Residents/Visitors Onsite Construction Workers Offsite Recreational Swimmers Offsite Recreational Waders Offsite Recreational Boaters Offsite Recreational Fishers Offsite Subsistence Fishers Scenario
Baseline -- -- -- -- -- -- --
CIP -- -- -- -- -- -- --
Excavation A -- -- -- -- -- -- --
Excavation B -- -- -- -- -- -- --
Hybrid -- -- -- -- -- -- --
“--” indicates “no meaningful risk.”
Current conditions and conditions under all closure options support provision of safe drinking
water, safe surface water, safe food, and safe recreation, satisfying the first objective of ash
basin closure—to protect human health from CCR constituent exposure.
Conclusion 2: All closure options for the Allen ash basins are
protective of ecological health.
The second objective for ash basin closure, to protect ecological health from CCR constituent
exposure, is represented by environmental services that provide safe surface water, safe food
consumption, and protection of biodiversity and natural beauty. For purposes of the NEBA,
these considerations were evaluated based on the following:

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1. Risk to ecological receptors from CCR exposure, as characterized by
SynTerra (2018b; Appendix B) in the updated human health and ecological
risk assessment; and
2. Aquatic community health in Lake Wylie as reported in the most recent
environmental monitoring report (Abney et al. 2014).
From my review of these analyses, no evidence of impacts to ecological receptors from CCR
exposure was identified under current conditions11 or under any closure option, and Lake Wylie
continues to support a healthy aquatic community. Using the NEBA framework and relative risk
ratings, these results are summarized in Table ES-5 within the objective of protecting ecological
health from exposure to CCR constituents.
Current conditions and conditions under all closure options support provision of safe surface
water, safe food consumption, and protection of biodiversity and natural beauty, satisfying the
second objective of ash basin closure—to protect ecological health from CCR constituent
exposure.

11 SynTerra’s updated ecological risk assessment (ERA) considered only potential exposure pathways that currently
exist and could remain after ash basin closure under any closure option. Any potential risk currently associated
with seeps (or AOWs) at Allen was not evaluated in the ERA or considered in this analysis because any risk
resulting from seeps will be eliminated, reduced, or mitigated per the court-enforceable SOC that Duke entered
with the North Carolina Environmental Management Commission on April 18, 2018 (EMC SOC WQ S17-009;
See Section 4.2). The SOC requires Duke Energy to accelerate the schedule for decanting the ash basin to
“substantially reduce or eliminate” seeps that may be affecting state or federal waters; the SOC also requires Duke
Energy to take appropriate corrective actions for any seeps remaining after decanting is complete to ensure the
remaining seeps are managed “in a manner that will be sufficient to protect public health, safety, and welfare, the
environment, and natural resources” (EMC SOC WQ S17-009).

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Table ES-5. Summary of relative risk ratings for attributes that characterize potential
hazards to ecological resources from CCR exposure in surface water, soil,
sediment, and food
Objective Protect Ecological Health from CCR
Hazard Exposure to CCR Potentially Affected Populations Fish/Shellfish Populations Aquatic Omnivore Birds (mallard) Aquatic Piscivore Birds (great blue heron) Aquatic Herbivore Mammals (muskrat) Aquatic Piscivore Mammals (river otter) Terrestrial Omnivore Birds (robin) Terrestrial Carnivore Birds (red tail hawk) Terrestrial Herbivore Mammals (meadow vole) Terrestrial Carnivore Mammals (red fox) Scenario
Baseline -- -- -- -- -- -- -- -- --
CIP -- -- -- -- -- -- -- -- --
Excavation A -- -- -- -- -- -- -- -- --
Excavation B -- -- -- -- -- -- -- -- --
Hybrid -- -- -- -- -- -- -- -- --
“--” indicates “no meaningful risk.”
Conclusion 3: Excavation closure to an offsite landfill creates
greater disturbance to communities.
The third objective for ash basin closure, to minimize risk and disturbance to humans from
closure, is represented by environmental services that provide safe air quality and a safe
community environment. For purposes of the NEBA, these considerations were evaluated based
on the following:
1. Health risks from diesel exhaust emissions to the community living and
working along transportation corridors during trucking operations to haul

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materials to and from the ash basins, as evaluated through the application of
diesel truck air emissions modeling and human health risk assessment; and
2. The relative risk for disturbance and accidents resulting from trucking
operations affecting residents living and working along transportation
corridors during construction operations, as evaluated by comparing the
relative differences in trucking operations among the closure options.
From these analyses, no meaningful health risk is expected from diesel exhaust emissions under
any closure option, but all the closure options are expected to produce different levels of
community disturbance in the form of noise and traffic congestion and risk of traffic accidents.
I used the number of trucks per day passing12 a receptor along a near-site transportation corridor
to examine the differences in noise and traffic congestion under the closure options. I compared
the increase in the average number of trucks hauling ash, earthen fill, geosynthetic material, and
other materials under the closure options13 to the current number of truck passes for the same
receptor. I specified a baseline level of truck passes14 on the transportation corridor under
current conditions of 110 passes per day. Based on the assumed 110-truck-per-day baseline
level and the number of truck trips per day from Duke Energy’s projections, the offsite
excavation closure option (Excavation B) would create significant noise and traffic congestion,
with an impact of 296%; CIP, excavation to an onsite landfill (Excavation A), and hybrid
closures have substantially lower impacts on noise and traffic congestion (CIP = 10%,
Excavation A = 4 %, hybrid = 8%). I input these percent impacts to the risk-ranking matrix
(Table ES-3) along with the total duration of trucking activities (6 years CIP; 18 years

12 Truck passes per day resulting from closure activities are calculated as the total number of loads required to
transport earthen fill, geosynthetic materials, and other materials multip lied by two to account for return trips.
The resulting total number of passes is then divided evenly among the total number of months of construction
time multiplied by 26 working days per month.
13 Truck trips to haul ash were not included in the estimate for Excavation A and hybrid closure options because
trucks hauling ash would not leave the Allen Station property and would not affect community receptors along
the transportation corridors.
14 A baseline estimate of trucking passes per day for transporta tion corridors near Allen was derived from North
Carolina Department of Transportation (NCDOT) data of annual average daily traffic (AADT) at thousands of
locations across the state and the proportion of road miles driven by large trucks in North Carolina (See
Appendix E for details).

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Excavation A; 17 years Excavation B; 7 years hybrid) to evaluate which of the closure options
best minimizes human disturbances.
I also evaluated risk from traffic accidents by comparing the average number of annual offsite
road miles driven between closure options relative to an estimate of the current road miles
driven in Gaston County, North Carolina. I specified a current, or baseline, level of annual road
miles driven along the transportation corridor near Allen of 120 million miles,15 and the road
miles driven under the closure options are from the trucking projections provided by Duke
Energy (2018). Using the 120-million-truck-miles baseline assumption, the CIP option has a
0.04% impact; excavation options A and B have 0.02 and 4% impacts, respectively; and the
hybrid closure option has a 0.03% impact. All closure options have a relative risk rating of <5%.
The relative risk ratings for CIP, excavation to an onsite landfill (Excavation A), and hybrid
options appear to be generally insensitive to lower assumed baseline annual truck miles;
however, for excavation to an offsite landfill (Excavation B), reducing the baseline assumption
(i.e., that there are fewer than 110 truck passes/day) increases the expected percent impact and
relative risk rating (see Appendix E for sensitivity analysis).
Table ES-6 summarizes the NEBA relative risk ratings based on the trucking projections and
implementation schedules provided by Duke Energy (2018) for the objective of minimizing
disturbance to humans during closure. All closure options create disturbance and risk to human
populations. Risk and disturbance created by CIP, excavation to an onsite landfill (Excavation
A), and hybrid closure options are comparable given the similar requirements for materials
(reflected in the number of miles driven and truckloads of material required). While daily and
annual trucking impacts from excavation to an onsite landfill (Excavation A) are slightly lower
than for CIP and hybrid closure, those impacts to the community last substantially longer
(approximately three times longer than CIP). Excavation closure to an offsite landfill
(Excavation B) creates considerable disturbance to the community that is substantially greater
than the disturbance created by CIP, excavation to an onsite landfill (Excavation A), and hybrid
closure options.

15 To estimate the number of baseline truck miles, I multiplied the number of total vehicle miles traveled in
Gaston County (NCDMV 2017) by the Gaston County average 5% contribution of trucks to total AADT
(NCDOT 2015).

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Table ES-6. Summary of relative risk ratings for attributes that characterize
potential hazards to communities during closure activities.
Darker shading and higher codes indicate greater impact.
Objective Minimize Human Disturbance
Hazard
Noise and
Traffic
Congestion
Traffic
Accidents
Air
Pollution Potentially Affected Populations Local Residents/Visitors Local Residents/Visitors Reasonable Maximum Exposure Scenario Baseline baseline baseline baseline
CIP 3B 3A --
Excavation A 5A 5A --
Excavation B 5F 5A --
Hybrid 3B 3A --
“--” indicates “no meaningful risk.”
All closure options support safe air quality from diesel truck emissions along the transportation
routes; however, each creates some level of disturbance and risk that could adversely impact
community safety, with a greater magnitude of impact from excavation closure option B. CIP,
excavation to an onsite landfill (Excavation A), and hybrid closure options best satisfy the third
objective of ash basin closure–to minimize risk and disturbance to humans from closure.
Conclusion 4: Both hybrid closure and excavation to an onsite
landfill minimize environmental disturbance.
The fourth objective for ash basin closure, to minimize risk and disturbance to the local
environment from closure, is represented by two environmental services: protection of
biodiversity and natural beauty. For purposes of the NEBA, these considerations were evaluated

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based on differences in the NPP of impacted habitats under the closure options, as estimated by
the number of DSAYs calculated by a habitat equivalency analysis (HEA).
The results of the HEA indicate that all closure options will result in a net loss of environmental
services due primarily to loss of forest habitat for borrow and offsite landfill areas, reduced NPP
services provided by a grass cap (cap and landfill areas),16 and the long delay for restoration of
forested habitat in the ash basins (excavation to onsite and offsite landfills, options A and B).
These factors, collectively, adversely affect environmental services provided by the impacted
habitat such that environmental services produced after closure will not compensate for the
service losses resulting from the closure. Excavation to an onsite landfill (Excavation A) and
hybrid closure of the ash basins at Allen produce the least net loss of NPP services. Differences
in net NPP services among the closure options are summarized in Table ES-7. A full description
of the methods, assumptions, results, and sensitivity analyses for the HEA are provided in
Appendix D and E.

16 An open field provides a relatively lower NPP service level than forest habitat (40% of forest NPP; Ricklefs
2008), and since a grass cap requires periodic maintenance mowing, for purposes of the HEA it was assumed
never to reach a level of NPP service equivalent to an open field. Grass cap was assigned a post-closure service
level of 8%, with full service attained in 2 years.

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Table ES-7. Summary of NPP DSAYs for closure options
CIP Excavation A Excavation B Hybrid
Ash basin losses Open field −566 −661 −702 −634

Grass Cap −74 −106 −113 −12

Open Water −139 −137 −145 −153

Wetland −611 −609 −647 −679
Broadleaf Forest −831 −238 −254 −242
Needleleaf Forest −443 −320 −342 −339
Scrub/Shrub −430 −369 −392 −296
Wetland Forest −120 −114

Total losses −3,216 −2,439 −2,594 −2,468
Ash basin post-closure gains Open field 37 245 376 82

Grass Cap 445 96 221

Open Water 126 141 67
Broadleaf Forest 311 888 1,335 891
Needleleaf Forest 256 732 1,100 733
Scrub/Shrub 36 235 361 79
Wetland Forest 2 5 7 5

Total gains 1,087 −2,327 3,321 2,078
Landfill/borrow losses Forest −1,086 −296 −2,744
Wetland −1

Total losses −1,086 −298 −2,744
Landfill/borrow post-closure gains Forest 732
Grass Cap 15 126

Total gains 732 15 126
Net Gain/Loss per Option −2,483 −395 −1,891 −391
The impact of closure on environmental services was computed as the percentage difference in
net DSAYs produced by the closure option and the baseline DSAYs (or the absolute value of
the DSAY losses). The DSAY losses represent the NPP services that would have been produced
by the ash basin, borrow areas, and landfills but for the project closure. The DSAY gains
represent the NPP services restored after project closure plus any future gains realized from
existing habitats before remediation begins. The sum of DSAY losses and gains represents the
net change of NPP services for the project resulting from closure. Dividing the closure option
net DSAYs by the absolute value of the DSAY losses provides a percentage of the impact. From
these calculations, the CIP closure will have a 58% impact on NPP services.17 Excavation

17 As discussed below, this habitat impact could be offset with an appropriate reforestation project.

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closures (A) to an onsite landfill and (B) to an offsite landfill within 50 miles of Allen will have
14 and 35% impacts to NPP services, respectively. Hybrid closure of the ash basins at Allen will
have a 16% impact to NPP services. These percent impacts were input to the risk-ranking matrix
(Table ES-3) along with the duration of the closure activities (6 years CIP; 18 years Excavation
A; 17 years Excavation B; 7 years hybrid) to visualize, within the NEBA framework, which of
the closure scenarios best minimizes environmental disturbances (Table ES-8).
Table ES-8. Summary of relative risk ratings for habitat changes that
affect protection of biodiversity and natural beauty.
Darker shading and higher codes indicate greater impact.
Objective
Minimize Environmental
Disturbance
Hazard Habitat Change
Attribute DSAYs
Scenario
Baseline baseline
CIP 3D
Excavation A 5B
Excavation B 5C
Hybrid 3B
Within the objective of minimizing environmental disturbance from closure, my analyses
indicate that all closure options adversely impact habitat-derived environmental services;
however, hybrid and excavation to an onsite landfill (Excavation A) closures minimize impacts
to the protection of biodiversity and natural beauty, best satisfying the fourth objective of ash
basin closure–to minimize risk and disturbance to the local environment from closure.
Conclusion 5: Hybrid closure maximizes environmental services.
Identifying environmental actions that maximize environmental services (the fifth objective for
ash basin closure) is a function of NEBA (Efroymson et al. 2003, 2004) and the overarching
objective that encompasses each of the other four objectives and all of the environmental
services that have been considered to this point.
I organized my analyses around the following five objectives for ash basin closure, and I found
the following:

1805956.000 - 5209 xxxi
1. Protect human health from CCR constituent exposure
All closure options for the Allen ash basins are protective of human health.
2. Protect ecological health from CCR constituent exposure
All closure options for the Allen ash basins are protective of ecological
health.
3. Minimize risk and disturbance to humans from closure
Excavation closure to an offsite landfill creates greater disturbance to
communities.
4. Minimize risk and disturbance to the local environment from closure
Both hybrid closure and excavation to an onsite landfill minimize
environmental disturbance.
5. Maximize local environmental services
Hybrid closure maximizes environmental services.
Table ES-9 summarizes the relative risk ratings for all attributes and objectives that have been
considered. From this analysis, which is based on a scientific definition of risk acceptability and
includes no value weighting, a hybrid closure of the Allen ash basins best maximizes
environmental benefits because it offers equivalent protection of human and ecological health
from CCR exposure and results in less disturbance to humans and the environment because of
the relatively low levels and duration of impacts, as compared to other options as currently
defined. Thus, hybrid closure best satisfies the fifth objective of ash basin closure—to maximize
local environmental services.
As noted previously, NEBA analysis also provides an opportunity to better understand the net
environmental benefits of possible closure options. If Duke Energy’s preferred closure option
for reasons not considered in the NEBA does not best maximize environmental services to the
local community as currently defined, the NEBA results provide insight into how environmental
services could be improved for that closure option. For instance, if Duke Energy’s preferred
closure option for Allen is CIP closure but the HEA results for the currently defined CIP closure
option estimate a net environmental service loss of 2,483 DSAYs, Duke Energy could consider
incorporating into an updated CIP closure plan for Allen a mitigation project that compensates
for the net environmental service losses projected from the currently defined CIP closure option.

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As an example, if Duke Energy started a reforestation project outside of the ash basin in 2022
(when onsite preparation of the ash basin begins), the reforestation project would gain 24.3
DSAYs/acre over the lifetime of the site (150 years in the HEA), requiring an approximate 102
acre project to compensate for the 2,483 DSAY loss projected from the HEA based on the
current CIP closure plan. Re-analysis of the HEA component of the NEBA for the updated
possible closure options would then result in no net environmental losses (as NPP services)
from habitat alteration of the basin under any closure option.
By looking at a wide variety of attributes that represent a number of different environmental
services that directly link to local stakeholder concerns for the Allen ash basins, I conclude, with
a reasonable degree of scientific certainty, that a hybrid closure of the Allen ash basins provides
greater net environmental services and less disturbance to the community and the environment
than the other closure options considered.

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xxxiii
Table ES-9. NEBA for closure of the ash basins at Allen.
Darker shading and higher alphanumeric codes indicate greater impact.
Objective Protect Human Health from CCR Protect Ecological Health from CCR Minimize Human Disturbance
Minimize
Environmental
Disturbance
Hazard Exposure to CCR Exposure to CCR
Noise and
Traffic
Congestion
Traffic
Accidents
Air
Pollution Habitat Change Potentially Affected Populations Local Residents/Visitors Onsite Trespassers Onsite Construction Workers Offsite Recreational Swimmers Offsite Recreational Waders Offsite Recreational Boaters Offsite Recreational Fishers Offsite Subsistence Fishers Fish Populations Aquatic Omnivore Birds (mallard) Aquatic Piscivore Birds (great blue heron) Aquatic Herbivore Mammals (muskrat) Aquatic Piscivore Mammals (river otter) Terrestrial Omnivore Birds (robin) Terrestrial Carnivore Birds (red tail hawk) Terrestrial Herbivore Mammals (meadow vole) Terrestrial Carnivore Mammals (red fox) Local Residents/Visitors Local Residents/Visitors Reasonable Maximum Exposure DSAYs
Scenario
Baseline -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- baseline baseline baseline baseline
CIP -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3B 3A -- 3D
Excavation A -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5A 5A -- 5B
Excavation B -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5F 5A -- 5C
Hybrid -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3B 3A -- 3B
“--” indicates “no meaningful risk.”

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1 Qualifications
I am a senior managing scientist in the Ecological and Biological Sciences Practice at Exponent,
a scientific and engineering consulting firm. I am a professional ecologist, toxicologist, and
biologist with more than 20 years of experience studying the relationship between human
activities and effects on natural resources and people. I have Doctor of Science and Master of
Science degrees in environmental health from the Harvard University School of Public Health. I
have a Bachelor of Science degree in biology from Rhodes College. My academic and
professional training includes a broad background in topics ranging from biology, ecology,
toxicology, epidemiology, pollution fate and transport, and statistical analysis. Key areas of my
practice involve the use of structured frameworks for evaluating multiple lines of evidence to
assess causation of environmental impacts and to weigh the benefits and consequences of
decisions that affect ecological and human health.
Decision support projects I have conducted include the following:
 Net environmental benefit analysis (NEBA) to facilitate the selection of a
remediation plan for a lead contaminated river and to support closure option
analysis of coal ash basins;
 Developing beach management tools to improve public advisories related to
elevated fecal bacteria from sewage contamination at recreational beaches;
 Selecting cleanup thresholds for sediment remediation that quantitatively
weigh the tradeoff between sensitivity and specificity of potential thresholds
to meet cleanup objectives;
 Natural resource damage assessment (NRDA) to support injury quantification
and restoration selection; and
 Review and testimony on the sufficiency of environmental impact analysis to
support development planning.
Projects I have been involved in have concerned coal ash basin closures, oil spills, sewage
releases, heavy metal contamination, development planning, and various industrial and

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municipal facilities that have generated complex releases to the aquatic environment. A list of
my publications, presentations, and cases for which I have written expert reports, been deposed,
and/or provided trial testimony is provided in my curriculum vitae, included as Appendix A of
this report.

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2 Assignment and Retention
I was asked to examine how local environmental health and environmental services are
differently affected under potential closure options for the coal ash basins at Duke Energy
Carolinas, LLC’s (Duke Energy’s) Allen Steam Station (Allen or Allen Station) and to evaluate
these differences in a structured framework that can support decision-making. My assignment
included review of the comprehensive site assessment (CSA) and corrective action plan (CAP)
documents for Allen, as well as documents available through the North Carolina Department of
Environmental Quality’s (NCDEQ’s) website and documents prepared as part of Duke Energy’s
National Pollutant Discharge Elimination System (NPDES) permitting. I visited Allen Station
on September 5, 2018, and I reviewed expert reports prepared for related matters involving
Allen. A list of the primary documents I relied upon is provided in Section 3 of this report.

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3 Reliance Materials
In the process of conducting my analyses, I have reviewed many documents. Of those, I have
relied most on the following reports and documents. Technical (scientific literature) references
are cited in subsequent sections of this report and listed in Section 12.
 Comprehensive Site Assessment (CSA) for the Allen Steam Station (HDR 2015a,
2016b) and SynTerra (2018a)
 Corrective Action Plan (CAP) for the Allen Steam Station (HDR 2015b, 2016a)
o Baseline Human Health and Ecological Risk Assessment for the Allen Steam
Station (HDR 2016c [Appendix F of CAP 2])
 2014 environmental monitoring report for Lake Wylie (Abney et al. 2014)
 NCDEQ Allen Meeting Officer Report (NCDEQ 2016a)
o Attachment V. Written Public Comments Received
o Attachment VIII. Public Comment Summary Spreadsheet
 Human Health and Ecological Risk Assessment Summary Update for the Allen Steam
Station (SynTerra 2018b; Appendix B)
 Closure logistics estimates (Duke Energy 2018).

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4 Introduction
In 2015, the U.S. Environmental Protection Agency (EPA) issued a rule called the “Hazardous
and Solid Waste Management System; Disposal of Coal Combustion Residuals [CCR] from
Electric Utilities” (CCR Rule), which, among other things, regulates closure of coal ash
impoundments in the United States. Closure of coal ash impoundments in North Carolina is
further regulated by the North Carolina Coal Ash Management Act of 2014 (CAMA), as
amended by H.B. 630, Sess. L. 2016-95. Under both the North Carolina CAMA and the federal
CCR Rule, there are two primary alternatives for closure of an ash impoundment:
 “Cap in place” (CIP) closure involves decanting the impoundment and
placing a low permeability liner topped by appropriate cap material, soil, and
grass vegetation over the footprint of the ash to restrict vertical transport of
water through the ash, as well as a minimum of 30 years of post-closure care,
which requires the implementation of corrective action measures if and as
necessary;
 Excavation closure involves decanting the impoundment, excavating all ash
in the basin, transporting the ash to an appropriate, permitted, lined landfill,
and restoring the site.
Duke Energy has evaluated four representative closure options for the ash basins at Allen: CIP;
excavation to a new onsite landfill (Excavation A); excavation to a new offsite landfill within 50
miles of Allen (Excavation B); and a hybrid closure, which involves excavating and
consolidating ash within the basin footprint to reduce the spatial area of CIP closure (Duke
Energy 2018). The administrative process for selecting an appropriate closure plan is ongoing.
The purpose of my report is to examine how the local community’s environmental health and
environmental services18 are differently affected by each closure option as currently defined and

18 Environmental services, or ecosystem services, are ecological processes and functions that provide value to
individuals or society (Efroymson et al. 2003, 2004).

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to evaluate these differences in a structured framework that can support decision-making in this
matter.
4.1 Site Setting
Allen is a five-unit coal-fired power plant located on the west bank of the Catawba River on
Lake Wylie near Belmont in Gaston County, North Carolina, and is approximately 1,009 acres
in area (Figure 4-1; SynTerra 2018a).
Allen began operations in 1957 with Units 1 and 2; Unit 3 was added in 1959, Unit 4 in 1960,
and Unit 5 in 1961 (SynTerra 2018a). Allen has one unlined inactive ash basin and one unlined
active ash basin. Within the footprint of the inactive ash basin are ash storage areas, structural
fill areas, and the double-lined Retired Ash Basin (RAB) Ash Landfill. The inactive ash basin
began operation in 1957 and contains approximately 3.9 million tons of ash; the active ash basin
was created in 1973 and contains approximately 7.7 million tons of ash (SynTerra 2018a).
Combined the basins cover 293 acres. The active ash basin has historically received bottom ash,
fly ash precipitated from flue gas, coal pile runoff, landfill leachate, flue gas desulfurization
(FGD) wastewater, the station yard sump, and stormwater flows (SynTerra 2018a). Allen
currently uses a dry fly ash handling system and either sends the dry fly ash offsite for beneficial
reuse or disposes of it the RAB Ash Landfill; Duke Energy is in the process of converting to dry
handling of bottom ash (SynTerra 2018a). Effluent from the ash basin discharges to Lake Wylie
through National Pollutant Discharge Elimination System (NPDES) permitted Outfall 002 (Figure
4-1).

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7

Figure 4-1. Map of Allen Station. Reproduced Figure 2-1 of the 2018 CSA Supplement (SynTerra 2018a).
The location of ash basin discharge to Lake Wylie is indicated as NPDES Outfall 002.

1805956.000 - 5209 8
Allen is located in an ecological transitional zone between the Appalachian Mountains and the
Atlantic coastal plain.19 Historically, much of the region was transformed from oak-hickory-pine
forests to farmland and more recently from farmland back to woodlands characterized by
successional pine and hardwood forest (Griffith et al. 2002). I observed forest, scrub/shrub,20
wetland, open water, and mowed grass habitat areas onsite during my September 5, 2018 visit
(Figure 4-2).

Figure 4-2. Images of various habitat types at Allen, September 5, 2018.
(a) Mowed grass, wetland, and forest looking southwest along the
western bank of Lake Wylie from the RAB Landfill. (b) A red tail hawk
and Canada goose in a wetland and mowed grass area between the
RAB Landfill and the active ash basin. (c) Shrub/scrub, mowed grass,
open water, and forest habitats looking over the active ash basin
looking south from the RAB Landfill. (d) Open water, shrub/scrub, and
forest habitat within and around the active ash basin, looking over the
middle settling cell.

19 Allen is located in the Southern Outer Piedmont based on USEPA’s ecoregion classification system.
https://www.epa.gov/eco-research/ecoregions
20 Scrub/shrub habitat is characterized by low, woody plants.

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The area surrounding Allen includes residential properties, undeveloped land, and Lake Wylie.
Created in 1904 when the Catawba Hydro Station was built near Fort Mill, South Carolina,21
Lake Wylie provides fishing, boating, and paddling recreation, and the lake is considered by
some “to be among the top bass fisheries in the southeast.”22 “The healthy food chain in this
reservoir produces quality catches of virtually all species that inhabit the lake,”23 which include
channel catfish (Ictalurus punctatus), blue catfish (Ictalurus furcatus), Black crappie (Pomoxis
nigro-maculatus), white crappie (Pomoxis annularis), largemouth bass (Micropterus salmoides),
white bass (Morone chrysops), and white perch (Morone americana).24 Duke Energy manages
six public boat ramps on Lake Wylie that facilitate access for recreation and fishing.25Rapid
development is also occurring around the Allen Station, in conjunction with a surge of
development in the larger Charlotte region.26 Directly across Lake Wylie from the Allen Station,
the River District is “slated to be the largest, mixed use community in the history of Charlotte,”
with green space, office space, retail space, residential space (4,500 homes), hotels, and trails
for biking and running.27 On the western side of Lake Wylie, numerous new residential areas are
under construction near the Allen Station, which I observed during my visit in September 2018.
4.2 Closure of the Ash Impoundments at Allen
Coal ash, or CCR, includes fly ash, bottom ash, boiler slag, and flue gas desulfurization material
(U.S. EPA 2017c). CCR are derived from the inorganic minerals in coal, which include quartz,
clays, and metal oxides (EPRI 2009). Fine-grained, amorphous particles that travel upward with
flue gas are called fly ash, while the coarser and heavier particles that fall to the bottom of the
furnace are called bottom ash (EPRI 2009). The chemical composition of coal ash is similar to
natural geologic materials found in the earth’s crust, but the physical and chemical properties of
coal ash vary depending on the coal source and the conditions of coal combustion and cooling

21 Duke Energy operates three power stations on Lake Wylie: Lake Wylie Hydroelectric Station, Allen Steam
Station, and Catawba Nuclear Station. (https://www.lakewyliemarinecommission.com/about-lake-wylie/)
22 https://www.aa-fishing.com/nc/nc-fishing-lake-wylie.html
23 https://www.aa-fishing.com/nc/nc-fishing-lake-wylie.html
24 https://www.aa-fishing.com/nc/nc-fishing-lake-wylie.html
25 https://www.takemefishing.org/blog/october-2017/destination-lake-wylie-fishing/
26 https://www.charlotteobserver.com/living/living-here-guide/article215809395.html
27 https://www.gastongazette.com/news/20180830/new-bridge-would-heighten-river-district-impact

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of the flue gas (EPRI 2009). The majority of both fly ash and bottom ash are composed of
silicon, aluminum, iron, and calcium, similar to volcanic ash and shale (Figure 4-3). Trace
elements such as arsenic, cadmium, lead, mercury, selenium, and chromium generally constitute
less than 1% of total CCR composition (EPRI 2009; USGS 2015). CCR are classified as a non-
hazardous solid waste under the Resource Conservation and Recovery Act (RCRA).28

Figure 4-3. Elemental composition of bottom ash, fly ash, shale, and volcanic ash.
Excerpt from EPRI (2009).
EPA’s 2015 CCR Rule (40 CFR §§ 257 and 261) requires groundwater monitoring29 of CCR
landfills and surface impoundments and for corrective action, including closure, of CCR sites
under certain circumstances. Owners and operators of CCR landfills and impoundments that are
required to close under the regulation must conduct an analysis of the effectiveness of potential
corrective measures (a corrective measures assessment) and select a strategy that involves either
excavation or capping the “waste-in-place.” Per § 257.97(b), the selected strategy must at a

28 https://www.epa.gov/coalash/coal-ash-rule
29 Groundwater must be evaluated for boron, calcium, fluoride, pH, sulfate, and total dissolved solids, which are
defined as the constituents for detection monitoring in Appendix III. When a statistically significant increase in
Appendix III constituents over background concentrations is detected, monitoring of assessment monitoring
constituents (Appendix IV) is required. Assessment monitoring constituents are antimony, arsenic, barium,
beryllium, cadmium, chromium, cobalt, fluoride, lead, lithium, mercury, mo lybdenum, selenium, thallium, and
radium 226 and 228, combined.

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minimum be protective of human health and the environment, attain groundwater protection
standards, control the source of releases so as to reduce or eliminate further releases of certain
CCR constituents into the environment, remove from the environment as much of the
contaminated material that was released from the CCR unit as is feasible, taking into account
factors such as avoiding inappropriate disturbance of sensitive ecosystems, and comply with the
standards for management of wastes in § 257.98(d).
The CCR Rule does not provide criteria for selecting between these closure alternatives because
they are both considered effective closure methods. The CCR Rule states both methods of
closure “can be equally protective, provided they are conducted properly.” Hence, the final CCR
Rule allows the owner or operator to determine whether excavation or closure in place is
appropriate for their particular unit (80 FR 21412).
For the last several years, Duke Energy has been evaluating all of its ash impoundments and
remains in the midst of further evaluating each one, including at Allen, under the CCR Rule and
pursuant to the administrative process set forth in CAMA. Ultimately, a final closure plan will
be approved by NCDEQ.
Four possible options for closure of the ash basins at Allen were identified by Duke Energy and
are summarized in (Table 4-1). These options were used in the NEBA to examine how different
closure possibilities impact environmental services to the local community.

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Table 4-1. Ash basin closure options provided by Duke Energy (2018)
Closure Options Description Closure Duration
(years)a
Construction
Duration (years)b
CIP CIP 9 6
Excavation A Excavate ash to a new onsite landfill 22 18
Excavation B Excavate ash to a new offsite landfill
within 50 miles of Allen
20 17
Hybrid Partially excavate to consolidate ash
and CIP consolidated ash
10 7
a Includes pre-design investigation, design and permitting, site preparation, construction, and site restoration.
b Includes only site preparation, construction, and site restoration.
Table 4-2 provides a summary of some of the logistical differences between the closure options.
Key among these are the following: (1) a substantially longer period of time is necessary to
complete excavation closures; (2) substantially more deforestation is required under excavation
to an offsite landfill; and (3) substantially more truck trips per day are required for excavation to
an offsite landfill. Considering logistics alone, however, does not provide a complete
understanding of the potential benefits and hazards associated with each closure option, and an
integrated analysis is necessary to place stakeholder concerns regarding risk from CCR in the
larger context of risks and benefits to environmental services.
Table 4-2. Overview of some key logistical differences between
closure options for the Allen ash basins.
Data provided by Duke Energy (2018).
Closure
Option
Closure Completion
Time (years)a
Deforested
Acresb
Truck
trips/dayc
CIP 9 36 6
Excavation A 22 12 2
Excavation B 20 91 163
Hybrid 10 0 4
a Includes pre-design investigations, design and permitting, site preparation,
construction, and site restoration.
b Includes areas deforested to create borrow pits and/or landfill.
c Includes the total number of round trip truck trips to haul earthen, ash, and
geosynthetic material to and from the ash basin.
Closure of the ash basins at Allen involve decanting any overlying water in the basin and
excavating or capping in place the underlying ash, as specified under CAMA and the federal
CCR Rule. Additional activities related to, but separate from, closure under CAMA and the

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CCR Rule concern constructed30 and non-constructed31 seeps associated with the ash basins.32 A
Special Order by Consent (SOC; EMC SOC WQ S17-009) was signed by the North Carolina
Environmental Management Commission and Duke Energy on April 18, 2018, to “address
issues related to the elimination of seeps” from Duke Energy’s coal ash basins. The SOC
requires Duke Energy to accelerate the schedule for decanting the ash basin to “substantially
reduce or eliminate” seeps that may be affecting state or federal waters; the SOC also requires
Duke Energy to take appropriate corrective actions for any seeps remaining after decanting is
complete to ensure the remaining seeps are managed “in a manner that will be sufficient to
protect public health, safety, and welfare, the environment, and natural resources” (EMC SOC
WQ S17-009). Given the court-enforceable requirement for Duke Energy to remediate any
seeps remaining after decanting the ash basin to meet standards for the protection of public and
environmental health, for purposes of my analyses, seeps (or areas of wetness [AOWs]) are
assumed to contribute no meaningful risk to humans or the environment following any closure
option since all closure options will entail decanting the basins and remediating any risk
associated with remaining seeps as required by the SOC (EMC SOC WQ S17-009).

30 Constructed seeps are features within the dam structure, such as toe drains or filter blankets, that collect seepage
of liquid through the dam and discharge the seepage through a discrete, identifiable point source to a receiving
water.
31 Non-constructed seeps are not on or within the dam structure and do not convey liquid through a pipe or
constructed channel; non-constructed seeps at Allen that require monitoring (and potentially action i f they are
not eliminated after ash basin decanting) are listed in the SOC (EMC SOC WQ S17-009).
32 In 2014, Duke Energy provided a comprehensive evaluation of all areas of wetness (AOWs or seeps) on Duke
Energy property and formally applied for NPDES coverage for all seeps (EMC SOC WQ S17-009).

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5 Approach to Forming Conclusions
Environmental decision-making involves understanding complex issues that concern multiple
stakeholders. Identifying the best management alternative often requires tradeoffs among
stakeholder values. For example, remediation management alternatives can decrease potential
risks to human health and the environment from contaminants, but such benefits can also have
unintended consequences, such as adverse impacts to other functions of the environment (e.g.,
destruction of habitat) or create other forms of risk (e.g., contamination of other environmental
media). These tradeoffs between existing and future environmental services necessitate a
transparent and systematic method to compare alternative actions and support the decision-
making process.
Structured frameworks or processes are commonly used to weigh evidence and support
requirements for environmental decision-making. Examples include:
 Environmental assessment (EA) and environmental impact statement (EIS)
process that supports National Environmental Policy Act requirements for
evaluating impacts from development projects and selecting mitigation
measures (40 CFR § 1502);
 Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) remedial investigation/feasibility study process that characterizes
risk from contaminants at a site and then evaluates remediation alternatives
(U.S. EPA 1988);
 RCRA corrective measures study that supports identification, development,
and evaluation of potential remedial alternatives for corrective action (U.S.
EPA 1994);
 EPA’s causal analysis/diagnosis decision information system (CADDIS) that
supports stressor identification and selection of appropriate mitigation actions
under the Clean Water Act (Cormier et al. 2000);

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 NRDA that characterizes injury and lost human services to support selection
of restoration projects under a number of environmental laws, including
CERCLA and the Oil Pollution Act of 1990 (e.g., NOAA 1996); and
 NEBA that evaluates the tradeoffs in environmental impacts and benefits
from remediation alternatives (NOAA 1990; Efroymson et al. 2003, 2004).
These frameworks have different regulatory origins and somewhat different approaches to
accomplishing their specific objectives, but they all rely on a common core of analyses,
including characterization of exposures, identification of adverse effects, definition of complete
pathways between exposures and effects, characterization of risk or impact to exposed receptors
(i.e., human and ecological populations), and weight-of-evidence analysis.
My analyses in this matter have used a NEBA framework to compare the relative risks and
benefits derived from the closure options under consideration for the ash basins at Allen. NEBA
was originally developed to examine impacts and benefits to ecological resources and habitats
excluding impacts and risk to humans (Efroymson et al. 2004); however, as noted by EPA
(2009a), remediation and closure actions can also have both direct and indirect consequences to
humans. To support a more thorough analysis of the net benefits of each closure option in this
matter, I have included comparative analyses in the NEBA that consider environmental health
more broadly, including risks and benefits to both ecological and human populations in the
vicinity. My analyses draw on the core principles of the environmental decision support
frameworks discussed above and follow a pragmatic and transparent process.
In assembling information for the NEBA and forming my conclusions, I have relied on analyses
reported in the CSA and CAP documents, as well as information provided by Duke Energy.
Because a NEBA of environmental health necessarily encompasses a variety of scientific
disciplines, I assembled a team of professionals within Exponent with expertise in ecological
risk assessment (ERA), human health risk assessment (HHRA), contaminant fate and transport,
decision support analysis, remediation, and statistics to review documents and, where indicated,
conduct analyses at my direction. The results of these efforts are included in this report and have
been reviewed by me.

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5.1 Net Environmental Benefit Analysis
Net environmental benefits are defined as “the gains in environmental services or other
ecological properties attained by remediation or ecological restoration, minus the environmental
injuries caused by those actions” (Efroymson et al. 2003, 2004). Environmental services, or
ecosystem services, are ecological processes and functions that produce value to individuals or
society. A NEBA, as discussed above, is a structured framework for comparing impacts and
benefits to environmental services and support decision-making (Efroymson et al. 2003, 2004).
NEBA can be useful in evaluating and communicating the short-term and long-term impacts of
remedial alternatives but does not make a determination of which alternative is best; that
decision must be made by stakeholders and decision-makers and may ultimately involve
weighing or prioritizing some values or objectives over others (Efroymson et al. 2003, 2004).
NEBA relies on scientifically supported estimates of risk to compare the reduction of risk
associated with chemicals of potential concern (COPCs) 33 under different remediation and
closure alternatives alongside the creation of any risk during the remediation and closure,
providing an objective, scientifically structured foundation for weighing the tradeoffs among
remedial and closure alternatives. Despite the scientific basis of the risk characterization
process, however, stakeholders in any environmental decision-making scenario may place
different values on different types of risk. In other words, stakeholders may have different
priorities for the remediation and closure. NEBA does not, by design, elevate, or increase the
value of, any specific risk or benefit in the framework. The purpose of NEBA is to
simultaneously and systematically examine all tradeoffs that affect the services (e.g., provision
of safe drinking water, protection of biodiversity34) provided to humans and the ecosystem by
the environment under remediation and closure, allowing decision-makers to more fully
understand all potential benefits and risks of each alternative.

33 COPCs are “any physical, chemical, biological, or radiological substance found in air, water, soil or biological
matter that has a harmful effect on plants or animals”
(https://ofmpub.epa.gov/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?de
tails=&glossaryName=Eco%20Risk%20Assessment%20Glossary).
34 Biodiversity is the variety of plants and animals present at a location. Protection of biodiversity refers to
provision of habitat and related functions capable of sustaining biological populations.

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EPA supports the use of NEBA (U.S. EPA 2009a) as a means to compare remediation and
redevelopment alternatives “based on their contributions to human well-being.” EPA and the
National Oceanic and Atmospheric Administration (NOAA) also use NEBA to support oil spill
response decision-making (Robberson 2006, NOAA 1990). Examples of NEBA in oil-spill
decision-making include:
 Exxon Valdez Oil Spill: NEBA was first applied to weigh the net
environmental benefits of rock-washing to remove beached oil versus leaving
the oil in place to naturally degrade (NOAA 1990).
 Deepwater Horizon Oil Spill: NEBA was used by the Operational Science
Advisory Team-2 (OSAT-2) to “compare the environmental consequences of
the defined cleanup endpoints for the oil and beach types considered, and the
consequences of cleanup beyond those endpoints,” specifically noting, “It is
at this juncture that the concept of continued remedial efforts doing ‘more
harm than good’ becomes a concern” (OSAT 2011).
I have personally applied NEBA to evaluate the net environmental benefits associated with two
alternative sediment remediation cleanup goals for lead contamination in a tidal river. At that
site, the river had been contaminated with lead from a battery manufacturing facility, and the
state required removal of contaminated sediment that could potentially pose a health risk to
people and the environment. The responsible party conducted human and ecological risk
assessments, toxicity tests, and benthic community analyses to support the selection of an
appropriate cleanup threshold for lead that would be protective of humans and the natural
environment. Uncertainty in the results, however, led to two different remediation threshold
concentrations being proposed by the state and by the responsible party. The NEBA was
conducted to examine the tradeoffs in environmental impacts associated with the two cleanup
thresholds. For one segment of the river, the footprint of remediation, including the size and
types of habitat impacted, was substantially different under the alternative cleanup goals. The
lower remediation threshold caused much greater impacts to submerged aquatic vegetation and
riparian (shoreline) habitat that had cascading consequences to animals that rely on those
environments. NEBA was able to demonstrate that remediation to the lower threshold would

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cause greater ecological harm and disturbance to the local community with little or no decrease
in risk to benthic invertebrates (the ecological receptor at issue).35 Consequently, the higher
remediation goal was applied to that segment of the river.
These examples of NEBA are particularly relevant to the issues at Allen. Remediation and
closure of coal ash basins is specifically addressed in CAMA and the CCR Rule, and both CIP
and excavation closure satisfy defined cleanup endpoints. At issue is whether removal of the
coal ash under an excavation closure crosses the “juncture,” as noted by OSAT-2, where the
action would do more harm than good (OSAT 2011).
5.2 Linking Stakeholder Concerns to NEBA
To better understand stakeholder concerns related to closure of the ash basins at Allen, I
reviewed written communications about ash basin closure plans for Allen submitted to and
summarized by NCDEQ (2016a). From this review, I identified the following categories of
stakeholder concerns:
 Drinking water quality
 Groundwater quality
 Surface water quality
 Fish and wildlife
 Maintaining property value
 Preservation of natural beauty
 Recreational value
 Swimming safety
 Failure of the ash impoundment
 Risk created by the closure option outweighing risk from contamination.
The primary concerns expressed by community stakeholders involve perceived risks from
exposure to CCR constituents that could negatively affect environmental services that benefit

35 Both remediation goals were found to be protective of human, fish, bird, and mammal health. Uncertainty in
toxicity test results and concern for protection of benthic macroinvertebrates (e.g., insect larvae and
crustaceans) led the state to propose a lower remediation threshold for lead.

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the community: provision of safe drinking water and food, safe recreational enjoyment (e.g.,
hunting, fishing, swimming), protection of natural beauty, and biodiversity. Potential hazards to
the community associated with closure activities include physical disturbance of existing
habitats; air pollution from diesel emissions; and traffic, noise, and accidents that could result in
property damage, injuries, and fatalities. Table 5-1 links concerns over CCR exposure and
potential hazards created by ash basin closure to environmental services that could be affected
by closure activities.

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20
Table 5-1. Relationships between environmental services and concerns to the local community associated with CCR
and ash basin closure hazards
Environmental Services
Safe drinking
water quality
Safe surface
water quality
Safe air
quality
Safe food
quality
Protection of
biodiversity
Recreation Natural
beauty
Safe community
environment
CCR Concerns
Drinking water
contamination
X X X
Groundwater contamination X X X
Surface water
contamination
X X X X X X X
Fish/wildlife contamination X X X X X
Contamination impacting
property value
X X X X X X X
Contamination impacting
natural beauty
X X X
Contamination impacting
recreational enjoyment
X X X X X
Contamination impacting
swimming safety
X X X X
Failure of the ash
impoundment
X X X X X X X
Closure Hazards
Habitat alteration X X X X X
Contamination of air X X X X
Noise, Traffic, Accidents X X

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In recognition of the potential discrepancy between stakeholder priorities and the broad and
balanced treatment of service risks and benefits in NEBA, I organized the NEBA in this matter
around the following five objectives for ash basin closure that recognize stakeholder concerns
while being consistent with the methods and purpose of NEBA:
1. Protect human health from CCR constituent exposure
2. Protect ecological health from CCR constituent exposure
3. Minimize risk and disturbance to humans from closure
4. Minimize risk and disturbance to the local environment from closure
5. Maximize local environmental services.
Associations between environmental services to the local community that could be potentially
impacted by ash basin closure and the identified objectives of ash basin remediation are shown
in Table 5-2.
Table 5-2. Associations between objectives for closure and remediation of the Allen
ash basins and environmental services
Ash Basin Closure Objectives
Environmental
Services
Protect
human health
from CCR
constituent
exposure
Protect
ecological health
from CCR
constituent
exposure
Minimize risk
and
disturbance
to humans
from closure
Minimize risk
and disturbance
to the local
environment
from closure
Maximize local
environmental
services
Safe drinking
water quality X X X
Safe surface
water quality X X X
Safe air quality X X
Safe food quality X X X
Recreation X X
Natural beauty X X X
Protection of
biodiversity X X X
Safe community
environment X X

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NEBA relies on comparative metrics for specific attributes of the environment to examine the
potential impacts and benefits from remediation and closure alternatives (Efroymson et al. 2003,
2004). NEBA methodology is not, however, prescriptive in defining attributes or comparative
metrics because each application of NEBA is unique to contaminant exposure, remediation and
closure alternatives, available data, and stakeholder concerns. NEBA is an extension of the risk
assessment process (Efroymson et al. 2004). As a result, receptors, exposure pathways, and risks
identified in a site risk assessment are key inputs to a NEBA. The links between key
environmental services, attributes that represent those services, and comparative metrics used in
this NEBA are summarized in Table 5-3.
Table 5-3. Matrix of key environmental services, attributes, and comparative metrics
applied in the NEBA
Attributes
Environmental Services Human Health
Risk
Ecological
Health Risk
Net Primary
Productivity
Transportation
Metrics
Safe ground water quality HI/ELCR -- --
Safe surface water quality HI/ELCR HQ
Safe soil and sediment quality HI/ELCR HQ --
Safe air quality HI/ELCR -- --
Safe food quality HI/ELCR HQ --
Protection of biodiversity HQ DSAYs
Recreation HI/ELCRa -- DSAYs
Natural beauty HQ DSAYs
Safe community environment -- Trucking
Logistics
Notes:
DSAYs – discounted service acre-years
ELCR – excess lifetime cancer risk
HI – hazard index
HQ – hazard quotient
a Estimated from health risks from consumption of fish.

I used human health attributes (e.g., risk to onsite construction workers, risk to offsite
swimmers) and risk quotients (hazard index [HI], excess lifetime cancer risk [ELCR]) to
evaluate whether there would be a potential impact to environmental services related to safe
water, air, and food under each ash basin closure option. I also used human health attributes to
evaluate whether there would be an impact to air quality during closure activities. I used

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ecological health attributes (e.g., risk to birds, mammals) and risk quotients (hazard quotient
[HQ]) to evaluate whether there would be a potential impact to environmental services related to
safe surface water and food and protection of biodiversity and natural beauty under the ash basin
closure options. I evaluated risk and disturbance associated with traffic and accidents using
transportation metrics and trucking logistics (e.g., number of truck miles driven) associated with
each closure option to evaluate impacts to community safety. I used net primary productivity
(NPP)36 and discounted service acre-years (DSAYs)37 to characterize differences in the
environmental services that derive from habitats (e.g., protection of biodiversity, natural beauty)
and that would be impacted by ash basin closure activities. Finally, I assembled all attributes,
services, and objectives within a full NEBA to examine which of the closure options best
maximizes environmental services to the local community. These metrics represent
scientifically appropriate and commonly applied metrics to evaluate risk to humans and the
environment (U.S. EPA 1989, 1997, 2000; NHTSA 2016) and to quantitatively measure
differences in environmental services associated with impact and restoration (Dunford et al.
2004; Desvousges et al. 2018; Penn undated; Efroymson et al. 2003, 2004).
Of note, my analysis did not consider the risks involved with onsite construction activities. For
example, I did not attempt to evaluate occupational accidents created by onsite construction and
excavation. Nor did I attempt to evaluate emissions associated with onsite construction
activities. Finally, I did not attempt to consider the risk created by disturbing the ash basin and
exposing it to the elements during excavation activities.
Some stakeholders also expressed concern over safety of the ash impoundment dam (NCDEQ
2016). The most recent dam safety report produced by Shield Engineering, Inc. and submitted to
NCDEQ indicates “the construction, design, operation, and maintenance of the CCR surface

36 NPP represents the mass of chemically fixed carbon produced by a plant community during a given time
interval. It reflects the rate at which different ecosystems are able to sequester carbon, which is related to
mitigating climate change (https://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD17A2_M_PSN).
37 DSAYs are derived from habitat equivalency analysis (HEA). HEA is an assessment method that calculates
debits based on services lost and credits for services gained from a remediation and closure action (Dunford et
al. 2004; Desvousges et al. 2018; Penn undated ). A discount rate is used to standardize the different time
intervals in which the debits and credits occur, and in doing so, present the service debits and credits at present
value. The present value of the services is usually expressed in terms of discounted service acre-years of
equivalent habitat, or DSAYs, which provide a means to compare the different service levels of affected habitat
acres (Dunford et al. 2004; Desvousges et al. 2018; Penn undated).

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impoundment have been sufficiently consistent with recognized and generally accepted
engineering standards for protection of public safety and the environment” (Huggins et al.
2018).
5.3 NEBA Risk Ratings
NEBA organizes environmental hazard and benefit information into a unitless metric that
represents the degree and the duration of impact from a remediation and closure alternative
(Efroymson et al. 2003, 2004). One approach to structure this analysis is to create a risk-ranking
matrix that maps the proportional impact of a hazard (i.e., risk) with the duration of the impact
(Robberson 2006). The risk-ranking matrix used for this application of NEBA is provided in
Table 5-4. The matrix uses alphanumeric coding to indicate the severity of an impact: higher
numbers and higher letters (e.g., 5F) indicate a greater extent and a longer duration of impact.
Shading of cells within the matrix supports visualization of the magnitude of the effect
according to the extent and duration of an impact.38 When there is no meaningful risk, the cell is
not given an alphanumeric code. Risk ratings generated from the risk-ranking matrix for each
attribute and closure option examined were assembled into objective-specific summaries to
compare the net benefits of the closure option. All closure options in the NEBA were evaluated
against current conditions as a “baseline” for comparison.

38 Categories and shading as defined in the risk-ranking matrix are based on best professional judgement a nd used
for discussion of the relative differences in relative risk ratings. Alternative risk matrices and resulting NEBA
classifications are explored in Appendix E.

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Table 5-4. Risk-ranking matrix for impacts and risk from
remediation and closure activities.
Darker shading/higher codes indicate greater impact

Duration of Impact (years)
16-25
(5)
10–15
(4)
5–9
(3)
1–4
(2)
<1
(1) % Impact No meaningful risk -- -- -- --
<5% (A) 5A 4A 3A 2A 1A
5–19% (B) 5B 4B 3B 2B 1B
20–39% (C) 5C 4C 3C 2C 1C
40–59% (D) 5D 4D 3D 2D 1D
60–79% (E) 5E 4E 3E 2E 1E
>80% (F) 5F 4F 3F 2F 1F
NEBA analysis of possible closure options for the ash basin at Allen helps both Duke Energy
and other stakeholders understand the net environmental benefits from the closure option
configurations that were examined. If a closure option that is preferred for reasons not
considered in the NEBA does not rate as one of the options that best maximizes environmental
services to the local community, closure plans for that option can be re-examined, and
opportunities to better maximize environmental benefits can be identified (e.g., including an
offsite habitat mitigation project to offset environmental services lost from habitat alteration).
The NEBA can then be re-run with the updated plan to compare the revised closure plan with
other closure options.
5.4 Risk Acceptability
Selecting any remediation, mitigation, restoration, or closure alternative involves considerations
of risk—risk posed by contamination in place, risk created by the action, risk remaining after the
action—and all of these risk considerations must be placed in some contextual framework if
informed decisions are to be made. Hunter and Fewtrell (2001) state, “The notion that there is
some level of risk that everyone will find acceptable is a difficult idea to reconcile and yet,
without such a baseline, how can it ever be possible to set guideline values and standards, given
that life can never be risk free?”

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EPA defines risk as “the chance of harmful effects to human health or to ecological systems
resulting from exposure to an environmental stressor” (U.S. EPA 2017a). In accordance with
EPA guidance for conducting ERAs (U.S. EPA 1997) and HHRAs (U.S. EPA 1989), risk to a
receptor (e.g., person, animal) exists when exposure to a stressor or stressors occur(s) at some
level of effect; however, because not all exposures produce adverse effects in humans or
ecological species, the exposure concentrations need to overlap with adverse effect thresholds
for there to be the potential for meaningful risk. The science supporting individual benchmarks
or levels of concern differs by the specific exposure at issue and the receptor at risk; however,
such benchmarks are considered by regulatory authorities to represent the best scientific
information available to create a baseline for risk (U.S. EPA 2017b).
The potential for risk associated with contamination is often evaluated using HQs, HIs, and
ELCRs to screen environmental media (e.g., water, soil) and identify the potential risk
associated with contamination (U.S. EPA 1989, 1997, 2000). The HQ is the ratio of an exposure
point concentration (EPC)39 divided by an appropriate toxicity benchmark for the receptor,
chemical, and exposure scenario. An HI, which is used in HHRA, is the sum of the HQs for
several chemicals that share the same target organ. If the HQ or HI is less than 1, exposure to
that chemical (HQ) or group of chemicals (HI) is expected to result in no adverse effects to even
the most sensitive receptors. Cancer risk to humans is typically evaluated using a probabilistic
approach that considers an acceptable risk benchmark range of 10-4 to 10-6, meaning that a
person’s ELCR from the exposure being assessed is less than 1 in 10,000 to 1 in 1,000,000 (U.S.
EPA 1989, 2000).
NEBA relies on scientifically supported estimates of risk; however, regardless of the scientific
acceptability of the risk characterization process, stakeholders may place different values on
different types of risk.

39 A conservative estimate of the chemical concentration available from a particular media and exposure pathway.

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6 Summary of Conclusions
Based on my review and analyses, I developed the following conclusions, which are structured
around the five objectives identified previously:
Conclusion 1: All closure options for the Allen ash basins are protective of human health.
Current conditions and conditions40 under all closure options support provision of safe drinking
water, safe surface water, safe food, and safe recreation, satisfying the first objective of ash
basin closure—to protect human health from CCR constituent exposure.
Conclusion 2: All closure options for the Allen ash basins are protective of ecological
health. Current conditions41 and conditions under all closure options support provision of safe
surface water, safe food consumption, and protection of biodiversity and natural beauty,
satisfying the second objective of ash basin closure—to protect ecological health from CCR
constituent exposure.
Conclusion 3: Excavation closure to an offsite landfill creates greater disturbance to
communities. All closure options support safe air quality from diesel truck emissions along the
transportation routes; however, each creates disturbance and risk that could adversely impact

40 SynTerra’s updated HHRA considered only potential exposure pathways that currently exist and could remain
after ash basin closure under any closure option. Any potential risk currently associated with seeps (or areas of
wetness [AOWs]) at Allen was not evaluated in the HHRA or considered in this analysis because any risk resulting
from seeps will be eliminated, reduced, or mitigated per the court-enforceable SOC that Duke entered with the
North Carolina Environmental Management Commission on April 18, 2018 (EMC SOC WQ S17-009; See
Section 4.24.2). The SOC requires Duke Energy to accelerate the schedule for decanting the ash basin to
“substantially reduce or eliminate” seeps that may be affecting state or federal waters; the SOC also requires Duke
Energy to take appropriate corrective actions for any seeps remaining after decanting is complete to ensure the
remaining seeps are managed “in a manner that will be sufficient to protect public health, safety, and welfare, the
environment, and natural resources” (EMC SOC WQ S17-009).
41 SynTerra’s updated ERA considered only potential exposure pathways that currently exist and could remain after
ash basin closure under any closure option. Any potential risk currently associated with seeps (or AOWs) at Allen
was not evaluated in the ERA or considered in this analysis because any risk resulting from seeps will be
eliminated, reduced, or mitigated per the court-enforceable SOC that Duke entered with the North Carolina
Environmental Management Commission on April 18, 2018 (EMC SOC WQ S17-009; See Section 4.24.2). The
SOC requires Duke Energy to accelerate the schedule for decanting the ash basin to “substantially reduce or
eliminate” seeps that may be affecting state or federal waters; the SOC also requires Duke Energy to take
appropriate corrective actions for any seeps remaining after decanting is complete to ensure the remaining seeps
are managed “in a manner that will be sufficient to protect public health, safety, and welfare, the environment, and
natural resources” (EMC SOC WQ S17-009).

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community safety, with a substantially greater magnitude of impact from excavation closure to
an offsite landfill.
Conclusion 4: Both hybrid closure and excavation to an onsite landfill minimize
environmental disturbance. All closure options adversely impact habitat-derived
environmental services, with a substantially greater adverse impact from CIP and excavation
closure to an offsite landfill;42 however, hybrid closure and excavation to an onsite landfill
minimize impacts to the protection of biodiversity and natural beauty, better satisfying the
fourth objective of ash basin closure—to minimize risk and disturbance to the local environment
from closure.
Conclusion 5: Hybrid closure maximizes environmental services. Hybrid closure maximizes
environmental benefits because, relative to the other closure options, it offers equivalent
protection of human and ecological health from CCR exposure and results in substantially less
disturbance to humans and the environment because of the relatively low levels and duration of
impacts, better satisfying the fifth objective of ash basin closure—to maximize local
environmental services.
Each will be discussed in detail in the following sections.

42 As noted in Section 5 and further discussed in Section 11, the loss of habitat-derived environmental services
could be offset with an appropriate reforestation project.

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7 Conclusion 1: All closure options for the Allen ash
basins are protective of human health.
The first objective for ash basin closure, to protect human health from contaminant exposure, is
represented by environmental services that provide safe drinking water, safe groundwater, safe
surface water, safe food consumption, and safe recreation. For purposes of the NEBA, these
safety considerations were evaluated based on the following:
1. Provision of alternative permanent drinking water supplies to private well
water supply users within a 0.5-mile radius of the Allen ash basin
compliance boundary (Holman 2018);
2. Concentrations of CCR constituents of interest (COIs)43 in drinking water
wells that could potentially affect local residents and visitors, as
characterized by HDR (2015a) and SynTerra (2018a) in the
Comprehensive Site Assessment (CSA); and
3. Risk to various human populations from CCR exposure, as characterized
in the updated human health and ecological risk assessment conducted by
SynTerra (2018b; Appendix B).
Through these lines of evidence, I evaluated whether CCR constituents are currently impacting
drinking water wells, whether they will impact drinking water in the future, and whether other
exposures to CCR constituents pose a risk to human populations now or with ash basin closure.
7.1 Private water supply wells pose no meaningful risk to the
community around Allen.
Per H.B. 630, Sess. L. 2016-95, all residents with drinking water supply wells within a 0.5-mile
radius of the Allen ash basin compliance boundary have been provided with permanent
alternative drinking water supplies (i.e., filter systems or connections to public water supplies;

43 COIs are constituents relevant to analysis of potential exposure to CCR constituents but are not necessarily
associated with risk to human or ecological receptors.

1805956.000 - 5209 30
Draovitch 2018),44 eliminating drinking water as a potential CCR exposure pathway for local
residents or visitors.
Additionally, available data indicate that public and private well water conditions are not
impacted by CCR constituents, and groundwater flow paths from the ash basin are away from
residential areas (SynTerra 2018a). Four public wells have been identified within 0.5 miles of
the site’s pre-2017 compliance boundary,45 which encompassed both the active and inactive ash
basins. All four of the public wells are located upgradient of the ash basin with respect to
groundwater flow and, thus, are unaffected by the ash basin (SynTerra 2018a).
Within 0.5 miles of the pre-2017 compliance boundary, 219 private wells are present (SynTerra
2018a). None of the private wells are downgradient of the ash basin; therefore, private wells are
unaffected by the ash basin (SynTerra 2018a). In 2015, 166 samples46 were collected and
analyzed for COIs and standard water parameters. The data indicated exceedances of North
Carolina Groundwater Quality Standards (2 L), interim maximum allowable concentrations
(IMACs), or provisional background threshold values (PBTVs), whichever is greater, for
antimony, cobalt, iron, pH, sulfate, strontium, thallium, total dissolved solids, and vanadium
(SynTerra 2018a). These constituents are naturally occurring but have also been associated with
CCR (SynTerra 2018a, HDR 2015a). SynTerra determined that their presence at elevated
concentrations in some wells may have been due in part to variability in natural background
conditions and/or well construction materials (SynTerra 2018a).
Although boron concentrations, one of the indicators of CCR impacts, did not exceed the 2L
standards in all private wells, seven private wells had boron concentrations greater than the
PBTV established for the site (SynTerra 2018a). These wells were geographically interspersed

44 NCDEQ determined Duke Energy had satisfactorily completed the permanent alternative water provision under
CAMA General Statute (G.S.) 130A-309.21 l(cl) on October 12, 2108 (Holman 2018).
45 The current compliance boundary has been revised inward and only encompasses the active ash basin (SynTerra
2018a).
46 In its 2016 CSA supplement, HDR (2016b) reported collection of 147 samples from private wells. However, the
data provided by HDR to SynTerra and used by SynTerra for its evaluation included 166 samples. No
explanation was provided for the discrepancy (SynTerra 2018a). More samples were collected from private
wells in 2016 and 2017, but the results were not substantively different from the older data. As such, these
newer results were only qualitatively evaluated and briefly addressed by Syn Terra (2018a).

1805956.000 - 5209 31
with others that did not contain elevated boron, and, when six of the wells were resampled, none
contained boron above the PBTV (SynTerra 2018a). The lack of consistently elevated boron
concentrations in these private water wells, combined with their location upgradient of the site,
indicates that the wells have likely not been impacted by CCR from the ash basins (SynTerra
2018a).
The most recent private well water samples included in the 2018 CSA (SynTerra 2018a) were
collected on December 20, 2017. Since then, an additional 30 samples have been collected from
10 private wells, 9 of which were previously sampled (HB630 Residential Well Data - Sept 24
2018.xlsx). 2L exceedances were detected for vanadium (in all 30 samples) and pH (in 2
samples). All samples were below both the 2L and PBTV levels for boron, and only five
samples were above the PBTV for sulfate, another potential indicator of CCR impacts. The lack
of boron exceedances and the relatively low frequency and magnitudes of exceedances for other
COIs (similar to those in previous sampling campaigns) lend further support to the conclusion
that private well water chemistry is not impacted by CCR.
7.2 CCR constituents from the Allen ash basins pose no
meaningful risk to human populations.
To assess potential risk to humans both onsite and offsite using the most recent and
comprehensive data available, SynTerra updated the HHRA (SynTerra 2018b; Appendix B) that
was originally conducted by HDR (2016c) as a component of the CAP part 2 (HDR 2016a). The
updated HHRA included updates47 to the conceptual site model, EPCs for human receptors with
complete exposure pathways, screening level risk assessments for human receptors with
complete exposure pathways, and hazard calculations (HI, ELCR) for receptors and COPCs
with plausible complete exposure pathways.

47 Updates to risk assessments are a natural part of the risk analysis process. EPA guidance for ecological risk
assessment notes, “The [risk assessment] process is more often iterative than linear, since the evaluation of new
data or information may require revisiting a part of the process or conducting a new assessment As more
information about a site is gained through site investigations, the risk assessment must be updated to reflect the
best knowledge of potential risk at a site” (U.S. EPA 1998). EPA similarly describes human health risk
characterization as an iterative process (U.S. EPA 2000).

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Consistent with the 2016 Baseline Human Health and Ecological Risk Assessment (HDR
2016c), the updated HHRA (SynTerra 2018b) examined CCR constituent exposure to a range of
human populations, including well users; construction workers; swimmers; waders; boaters; and
recreational and subsistence fishers under different pathways (i.e., exposure through seep water
or soil, sediment, surface water, groundwater, or fish tissue). HIs and ELCRs were estimated for
scenarios with plausible complete exposure pathways.
Complete CCR exposure pathways evaluated in the updated HHRA included the following
(SynTerra 2018b):
 Onsite construction workers via groundwater48
 Offsite recreational swimmers via offsite surface water and sediment
 Offsite recreational waders via offsite surface water and sediment
 Offsite recreational boaters via offsite surface water
 Offsite recreational fishers via offsite surface water and fish tissue
 Offsite subsistence fishers via fish tissue.
Since all households with drinking water supply wells within a 0.5-mile radius of the Allen ash
basin compliance boundary have received permanent alternative water supplies (Holman 2018)
and no potable water wells are located downgradient of the Allen ash basins, drinking water
risks from groundwater were not further evaluated because there is no complete exposure
pathway (HDR 2016c).
A summary of the risk assessment results from the updated HHRA (SynTerra 2018b) is
provided in

48 Groundwater exposure to onsite construction workers was evaluated in the updated HHRA, though a pathway
for exposure was considered incomplete by SynTerra (2018).

1805956.000 - 5209 33
Table 7-1.

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Table 7-1. Summary of human health risk assessment hazard index (HI) and excess
lifetime cancer risk (ELCR) from SynTerra (2018b)
Media Receptor HI ELCR
Groundwater Construction Worker 0.004 NC
Sediment Recreational Swimmer 0.001 NC
Surface Water Recreational Swimmer 0.003 1.4×10-6
Sediment Recreational Wader 0.001 NC
Surface Water Recreational Wader 0.001 3.3×10-7
Surface Water Recreational Boater 0.0005 2.8×10-8
Surface Water Recreational Fisher 0.0005 2.8×10-8
Biota (fish) Recreational Fisher 0.01 2.1×10-6
Biota (fish) Subsistence Fisher 0.4 1.5×10-4
Notes:
NC - Risk based concentration based on non-cancer HI.
The majority of exposure scenarios assessed by SynTerra (2018b) indicated that exposure to
CCR poses no meaningful risks to humans. The ELCR associated with subsistence fishers was,
however, estimated by SynTerra (2018b) to be greater than 1×10-4, above the upper end of
EPA’s target ELCR range of 10-6 to 10-4 (U.S. EPA 1989, 2000a).
Risk assessment is subject to a number of uncertainties, including the representativeness of
sample data, the degree to which exposure assumptions approximate actual exposure, estimation
of chemical toxicity, and characterization of background concentrations. Risk assessment
typically addresses these uncertainties by including conservative assumptions that tend to
overestimate exposure and risk. For example, to evaluate potential risk to subsistence fishers in
the Allen HHRA, SynTerra (2018b) used a fish consumption rate of 170 g/day, which represents
the highest level of consumption (95th percentile) in a high consuming subsistence Native
American population living in an area with plentiful fish resources that can support such high
fish consumption (Columbia River Tribes in Oregon) (U.S. EPA 2000, 2011).49 SynTerra
(2018b) further assumes this rate of fish consumption would continue for many years using only
fish from a single water body with fish tissue COPC concentrations estimated using a
conservative uptake model (bioconcentration factors [BCFs]) from the highest surface water
COPC concentrations. Each exposure pathway in the HHRA uses similarly conservative

49 In the case of Allen, SynTerra has not identified any populations of subsistence fishers in the area.

1805956.000 - 5209 35
assumptions to address uncertainty. While this serves to ensure a health protective assessment,
results that exceed target risk levels should be examined in more depth to understand the
context. Therefore, I examined the foundation for the subsistence fisher ELCR in more detail.
Risk to fishers was modeled by SynTerra (2018b) by estimating fish tissue concentrations from
surface water sample data. The cumulative ELCR of 1.5×10-4 for subsistence fishers from these
exposures was driven by concentrations of chromium (VI). This risk was not identified in the
previous HHRA (HDR 2016c), as more recent samples were included in the 2018 analysis.
For chromium (VI), the ELCR of 1.5×10-4 is less than an order of magnitude above the upper
end of the EPA’s target ELCR range of 10-6 to 10-4 (U.S. EPA 1989, 2000). This ELCR was
determined using a BCF for chromium (VI) of 200, based on a 1996 report from the National
Council on Radiation Protection and Management (NCRP 1996). However, a more recent
review by California EPA evaluated chromium uptake in fish and derived a lower BCF for
chromium based primarily on studies of chromium (VI). OEHHA (2012) states that chromium
(VI) is not well taken up into edible fish tissue and recommends a BCF of 20 (OEHHA 2012).
Had a BCF of 20 been used in the updated HHRA (SynTerra 2018b), the resulting ELCR would
be 1.5×10-5, within EPA’s range of acceptable risk. Based on the conservative uptake
assumptions and BCF used in this model and the very limited exceedance of acceptable ELCR, I
conclude there is no meaningful risk to subsistence fishers from exposure to chromium (VI) in
Lake Wylie.
Given the lack of meaningful risk under current conditions, 50 there is also no meaningful risk to
humans from CCR exposure under any of the ash basin closure options since all options reduce
or eliminate exposure pathways following closure. Thus, all closure options are protective of
public health.

50 SynTerra’s updated HHRA considered only potential exposure pathways that currently exist and could remain
after ash basin closure under any closure option. Any potential risk currently associated with seeps at CSS was not
evaluated in the HHRA or considered in this analysis because any risk resulting from seeps will be eliminated,
reduced, or mitigated per the court-enforceable SOC that Duke entered with the North Carolina Environmental
Management Commission on April 18, 2018 (EMC SOC WQ S17-009; See Section 4.2).

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7.3 NEBA – Protection of Human Health from CCR Exposure
Based on these analyses, there is no CCR risk from drinking water supplies, no evidence of
CCR impacts to drinking water wells, and no meaningful risk to humans from CCR exposure
under current conditions or under any closure option. Using the NEBA framework and relative
risk ratings, these results are summarized in Table 7-2 within the objective of protecting human
health from exposure to CCR constituents.
Table 7-2. Summary of relative risk ratings for attributes that characterize potential
hazards to humans from CCR exposure in drinking water, surface water,
groundwater, soil, sediment, food, and through recreation
Objective Protect Human Health from CCR
Hazard Exposure to CCR Potentially Affected Populations Local Residents/Visitors Onsite Construction Workers Offsite Recreational Swimmers Offsite Recreational Waders Offsite Recreational Boaters Offsite Recreational Fishers Offsite Subsistence Fishers Scenario
Baseline -- -- -- -- -- -- --
CIP -- -- -- -- -- -- --
Excavation A -- -- -- -- -- -- --
Excavation B -- -- -- -- -- -- --
Hybrid -- -- -- -- -- -- --
“--” indicates “no meaningful risk.”
Current conditions and conditions under all closure options support provision of safe drinking
water, safe surface water, safe food, and safe recreation, satisfying the first objective of ash
basin closure—to protect human health from CCR constituent exposure.

1805956.000 - 5209 37
8 Conclusion 2: All closure options for the Allen ash
basins are protective of ecological health.
The second objective for ash basin closure, to protect ecological health from CCR exposure, is
represented by environmental services that provide safe surface water, safe food consumption,
and protection of biodiversity and natural beauty. For purposes of the NEBA, these
considerations were evaluated based on the following:
1. Risk to ecological receptors from CCR exposure, as characterized by
SynTerra (2018b; Appendix B) in the updated human health and ecological
risk assessment; and
2. Aquatic community health in Lake Wylie as reported in the most recent
environmental monitoring report (Abney et al. 2014).
Through these two lines of evidence, I evaluated whether CCR constituents pose a risk to
ecological populations now or after ash basin closure.
8.1 No meaningful risks to ecological receptors from CCR
exposure exist under current conditions or any closure
option.
To assess potential risk to ecological receptors both onsite and offsite using the most recent and
comprehensive data available, SynTerra (2018b) updated the Baseline Human Health and
Ecological Risk Assessment that was originally conducted by HDR (2016c) as a component of
the CAP part 2 (HDR 2016a). The updated ERA included updates to the conceptual site model,
EPCs for receptors with potentially complete exposure pathways, and screening level risk
assessments for ecological receptors with potentially complete exposure pathways. Updated
HQs were estimated for receptors with plausible complete exposure pathways to CCR-related
COPCs (SynTerra 2018b).
The ecological receptors evaluated in the ERA are common representatives of particular groups
of organisms inhabiting different habitats and aspects of the food web. Key receptors in

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SynTerra’s updated ERA (SynTerra 2018b) and their pathways for exposure included the
following:
 Birds: Avifauna species may be exposed by ingestion of food and surface
water and by incidental ingestion of sediment and soil. Aquatic/wetland
species included were mallard duck (omnivore) and great blue heron
(piscivore), and terrestrial species included were American Robin (omnivore)
and red-tailed hawk (carnivore).
 Mammals: Aquatic/wetland or terrestrial species may be exposed by
ingestion of food and surface water and by incidental ingestion of sediment
and soil. Aquatic/wetland species included were muskrat (omnivore) and
river otter (piscivore), and terrestrial species included were meadow vole
(herbivore) and red fox (carnivore).
Ecological risk for these indicator species was characterized by SynTerra (2018b) using a risk-
based screening approach that compared chemical exposure levels to chemical toxicity
references values (TRVs) to calculate HQs for COPCs. TRVs in the ERA included no-observed-
adverse-effects levels (NOAELs)51 and lowest-observed-adverse-effects levels (LOAELs)52
derived from the literature for each COPC.
HQ results for the site were evaluated for two exposure areas of the Allen Station53 (Figure 8-1).
HQs less than 1 indicate no meaningful risk to an ecological receptor species associated with
exposure to the COPCs evaluated.
 Exposure Area 1: All HQs <1, indicating no meaningful risk to receptors in
this area.

51 A NOAEL is a concentration below which no adverse effects have been observed for a specific receptor and
pathway of exposure. NOAELs are typically estimated from laboratory toxicity tests.
52 A LOAEL is a concentration associated with the lowest concentration level at which adverse effects have been
observed for a specific receptor and pathway of exposure. LOAELs are typically estimated from laboratory
toxicity tests.
53 The baseline ERA conducted by HDR in 2016 (HDR 2016c) included four exposure areas. However, Exposure
Area 2 (near the plant at the head of the heated water discharge channel) and Exposure Area 3 (south of the ash
basins) were determined by SynTerra (2018b) to have no CCR influence from the ash basins (SynTerra 2018).

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 Exposure Area 4: NOAEL HQ >1 for meadow vole exposure to aluminum;
however, LOAEL HQ <1 for meadow vole exposure to aluminum, indicating
no meaningful risk to this species. All other HQs<1, also indicating no
meaningful risk to the other ecological receptors.
Based on the updated ecological risk assessment (SynTerra 2018b), there are currently no
meaningful risks to ecological receptors associated with CCR exposure at Allen.
Additionally, the 2014 environmental monitoring report (Abney et al. 2014) for Lake Wylie
reported results from biological sampling (macroinvertebrates and fish) and water chemistry
analyses conducted between 2009 and 2013. The report concluded that the data indicate “a
balanced and indigenous aquatic population exists in the vicinity of [Allen Station]” (Abney et
al. 2014). Fish species collected in Lake Wylie near Allen “encompass multiple trophic guilds
(i.e., insectivores, omnivores, and piscivores) supporting a balanced fish community,” and
“macroinvertebrate densities and taxa diversity observed during 2009–2013 at locations uplake,
downlake and in the vicinity of [Allen Station] are indicative of balanced and indigenous
macroinvertebrate communities” (Abney et al. 2014).
Given the lack of meaningful risk from CCR exposure under current conditions, CIP,
excavation, and hybrid closure options would all be protective of ecological receptors since each
closure option reduces or eliminates potential exposure pathways.

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40
Figure 8-1. Exposure areas evaluated in the 2018 ecological risk assessment update (SynTerra 2018b).

1805956.000 - 5209 41
8.2 NEB A – Protection of Environmental Health from CCR
Exposure
Based on these analyses, no meaningful risk to ecological receptors from CCR exposure was
found under current conditions54 or under any closure option. Using the NEBA framework and
relative risk ratings, within the objective of protecting environmental health from exposure to
CCR constituents, these results are summarized in Table 8-1.

54 SynTerra’s updated ERA considered only potential exposure pathways that currently exist and could remain after
ash basin closure under any closure option. Any potential risk currently associated with seeps at Allen was not
evaluated in the ERA or considered in this analysis because any risk resulting from seeps will be eliminated,
reduced, or mitigated per the court-enforceable SOC that Duke entered with the North Carolina Environmental
Management Commission on April 18, 2018 (EMC SOC WQ S17-009; See Section 4.2).

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Table 8-1. Summary of relative risk ratings for attributes that characterize potential
hazards to ecological resources from CCR exposure in surface water, soil,
sediment, and food
Objective Protect Ecological Health from CCR
Hazard Exposure to CCR Potentially Affected Populations Fish/Shellfish Populations Aquatic Omnivore Birds (mallard) Aquatic Piscivore Birds (great blue heron) Aquatic Herbivore Mammals (muskrat) Aquatic Piscivore Mammals (river otter) Terrestrial Omnivore Birds (robin) Terrestrial Carnivore Birds (red tail hawk) Terrestrial Herbivore Mammals (meadow vole) Terrestrial Carnivore Mammals (red fox) Scenario
Baseline -- -- -- -- -- -- -- -- --
CIP -- -- -- -- -- -- -- -- --
Excavation A -- -- -- -- -- -- -- -- --
Excavation B -- -- -- -- -- -- -- -- --
Hybrid -- -- -- -- -- -- -- -- --
“--” indicates “no meaningful risk.”
Current conditions and conditions under all closure options support provision of safe surface
water, safe food consumption, and protection of biodiversity and natural beauty, satisfying the
second objective of ash basin closure—to protect ecological health from CCR constituent
exposure.

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9 Conclusion 3: Excavation closure to an offsite
landfill creates greater disturbance to
communities.
The third objective for ash basin closure, to minimize risk and disturbance to humans from
closure, is represented by environmental services that provide safe air quality and a safe
community environment. For purposes of the NEBA, these considerations were evaluated based
on the following:
1. Health risks from diesel exhaust emissions to the community living and
working along transportation corridors during trucking operations to haul
materials to and from the ash basin, as evaluated through the application of
diesel truck air emissions modeling and HHRA; and
2. The relative risk for disturbance and accidents resulting from trucking
operations affecting residents living and working along transportation
corridors during construction operations, as evaluated by comparing the
relative differences in trucking operations between the closure options.
All closure options require increased trucking activity to haul materials to the site (e.g., transport
cap material to the ash basin) or to haul materials away from the site (e.g., transport coal ash
from the ash basin to a lined landfill). These activities involve the use of diesel-powered dump
trucks, which increase local diesel exhaust emissions and traffic, both of which present potential
hazards to local populations in the form of air pollution and roadway hazards. Table 9-1
summarizes the transportation logistics associated with each of the closure options Duke Energy
is considering for Allen (Duke Energy 2018). Obvious from these numbers is that the amount of
trucking involved in the excavation closures to an offsite landfill (Excavation B) is substantially
greater than that involved in CIP, hybrid, or excavation closure to an onsite landfill (Excavation
A). These differences are reflected in the number of truck loads required and the number of
miles driven. Transportation logistics associated with CIP, excavation to an onsite landfill
(Excavation A), and hybrid closure are similar, though Excavation A closure requires
substantially more time than CIP or hybrid closure.

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Table 9-1. Summary of offsite transportation logistics associated with each closure
option (Duke Energy 2018)
Logistics CIP Excavation A Excavation
B Hybrid
Closure Duration (years) (years)a 9 22 20 10
Construction Duration (years)b 6 18 17 7
Offsite truck loads to haul cap & fill
materialc 10,915 12,471 11,842 9,800
Offsite miles driven to haul cap & fill
materialc 302,480 331,696 260,526 256,825
Offsite truck loads to excavate ash and
associated materialsd 0 0 836,790 0
Offsite miles driven to excavate all
materialsd 0 0 83,679,035 0
Total offsite truck loads 10,915 12,471 848,632 9,800
Total offsite miles driven 302,480 331,696 83,939,561 256,825
a Includes design and permitting, decanting, site preparation, construction, and site restoration.
b Includes site preparation, construction, and site restoration.
c Includes cover soil, top soil, and geosynthetic material.
d Includes ash, over-excavated soil, and removed dams and embankments.
Costs to society associated with trucking include accidents (fatalities, injuries, and property
damage), emissions (air pollution and greenhouse gases), noise, and the provision, operation,
and maintenance of public roads and bridges (Forkenbrock 1999). Generally, the magnitude of
these impacts scales with the frequency, duration, and intensity of trucking operations
(Forkenbrock 1999). Figure 9-1 illustrates the normalized differences between transportation
activities under the excavation and hybrid closure options compared to CIP. From these results,
it is clear that risk and disturbance associated with transportation activities will be substantially
greater under excavation closures to an offsite landfill (Excavation B) compared to CIP closure,
hybrid closure, or excavation closure to an onsite landfill (Excavation A).

1805956.000 - 5209 45

Figure 9-1. Normalized differences between transportation activities under the closure options.
Bars represent the increased activity under an excavation closure compared to
CIP.
9.1 There is no meaningful risk from diesel emissions to
people living and working along the transportation
corridor.
The types of large dump trucks that will be used in closure activities at Allen are generally
diesel powered, and diesel exhaust includes a variety of different particulates and gases,
including more than 40 toxic air contaminants.55 North Carolina does not have a diesel-specific
health-based toxicity threshold because diesel exhaust is not currently regulated as a toxic air
pollutant. North Carolina also does not regulate PM2.5 or PM1056 as toxic air pollutants. North
Carolina defers to EPA’s chronic non-cancer reference concentration (RfC) for diesel particulate
matter of 5 µg/m3 based on diesel engine exhaust to estimate risk from diesel emissions.57
California is, to my knowledge, the only state that currently regulates diesel as a toxic air
contaminant and has identified both an inhalation non-cancer chronic reference exposure level
(REL)58 of 5 µg/m3 and a range of inhalation potency factors indicating that a “reasonable

55 https://oehha.ca.gov/air/health-effects-diesel-exhaust
56 PM2.5 and PM10 are airborne particulate matter sizes. PM2.5 is particulate matter that is 2.5 µm or less in size;
PM10 is particulate matter that is 10 µm or less in size.
57 Integrated Risk Information System (IRIS). U.S. EPA. Diesel engine exhaust.
58 A chronic REL is a concentration level (expressed in units of micrograms per cubic meter [µg/m3]) for
inhalation exposure at or below which no adverse health effects are anticipated following long -term exposure.

1805956.000 - 5209 46
estimate” for the inhalation unit risk is 3.0×10-4 (µg/m3)-1 “until more definitive mechanisms of
toxicity become available” (OEHHA 2015). California bases the non-cancer and cancer health
factors on the whole (gas and particulate matter) diesel exhaust and uses PM10 as a surrogate
measure.
As PM10 is the basis for both the non-cancer and inhalation risk factors for diesel exhaust
exposure in California, I relied on a PM10 exposure model to evaluate potential non-cancer and
cancer health risks from diesel exhaust.59
A representative segment of road was simulated using EPA’s AERMOD model60 to quantify air
concentrations at set distances away from the road (U.S. EPA 2016). Diesel truck emissions
were configured in the model in a manner consistent with the recommendations from EPA’s
Haul Road Working Group (U.S. EPA 2011). The emission rate for diesel trucks was calculated
using the EPA Mobile Vehicle Emissions Simulator (MOVES) model (U.S. EPA 2015).61
Emission factors were then applied to the average number of anticipated truck trips each year to
define the average annual amount of diesel particulate matter emitted along the representative
road segment, and these exposures were then summed over seventy years.62 AERMOD
simulations were run for four transportation orientation directions and used five years of local
meteorological data to estimate EPCs at regular intervals from 10 to 150 m perpendicular to
either side of the road. The results of the model were translated into average PM10 exposure

EPA has defined long-term exposure for these purposes as at least 12% of a lifetime, or about eight years for
humans.
59 California regulations and guidance indicate that when comparing whole diesel exhaust to speciated
components of diesel (e.g., polycyclic aromatic hydrocarbons, metals) the cancer risk from inhalation of whole
diesel exhaust will outweigh the multi-pathway analysis for speciated components.
60 AERMOD will calculate both the downwind transport and the dispersion of pollutants emitted from a source.
Both transport and dispersion are calculated based on the observed meteorology and characteristics of the
surrounding land. AERMOD is maintained by EPA and is the regulatory guideline model for short-range
applications (transport within 50 km).
61 The MOVES model allows a user to determine fleet average emission factors (in units of grams of pollutant per
mile traveled) for specific classes of vehicles and specific years. In this application, factors defined by MOVES
for single-unit short-haul diesel truck were used.
62 For the cancer risk analysis, emissions were calculated as an average over the regulatory default 70-year
residential exposure duration. If the truck activity for a closure option occurs over a shorter period, the duration
of the truck activity exposure is factored into the 7 0-year averaging time (OEHHA 2015).

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(µg/m3) and excess cancer risk over a 70-year period using reasonable maximum exposure.63
Results of the exposure modeling are provided in Table 9-2. Full results and a more detailed
description of the model are provided in Appendix C.

63 Long-term exposure was incorporated into the air simulation as the average exposure given estimated trucking
rates for 12 hours per day—7am to 7 pm—6 days a week for the duration of the project trucking time.

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48
Table 9-2. Hazard indices (HI) and excess lifetime cancer risk (ELCR) from exposure to diesel
exhaust emissions along transportation corridors in south-central North Carolina.
Results are for the maximum exposures modeled.
Perpendicular
Distance from
the Road
CIP Excavation A Excavation B Hybrid
ELCR HI ELCR HI ELCR HI ELCR HI
10 m 3.12E-09 0.0000

1.76E-09 0.0000

1.37E-07 0.0004

2.24E-09 0.0000
20 m 2.72E-09 0.0000

1.53E-09 0.0000

1.19E-07 0.0003

1.95E-09 0.0000
30 m 2.16E-09 0.0000

1.22E-09 0.0000

9.48E-08 0.0003

1.55E-09 0.0000
40 m 1.79E-09 0.0000

1.01E-09 0.0000

7.86E-08 0.0002

1.29E-09 0.0000
50 m 1.53E-09 0.0000

8.61E-10 0.0000

6.71E-08 0.0002

1.10E-09 0.0000
60 m 1.33E-09 0.0000

7.50E-10 0.0000

5.85E-08 0.0002

9.59E-10 0.0000
70 m 1.18E-09 0.0000

6.64E-10 0.0000

5.17E-08 0.0001

8.48E-10 0.0000
80 m 1.06E-09 0.0000

5.95E-10 0.0000

4.63E-08 0.0001

7.59E-10 0.0000
90 m 9.55E-10 0.0000

5.37E-10 0.0000

4.19E-08 0.0001

6.87E-10 0.0000
100 m 8.70E-10 0.0000

4.90E-10 0.0000

3.81E-08 0.0001

6.25E-10 0.0000
110 m 7.98E-10 0.0000

4.49E-10 0.0000

3.50E-08 0.0001

5.73E-10 0.0000
120 m 7.35E-10 0.0000

4.13E-10 0.0000

3.22E-08 0.0001

5.28E-10 0.0000
130 m 6.85E-10 0.0000

3.85E-10 0.0000

3.00E-08 0.0001

4.92E-10 0.0000
140 m 6.45E-10 0.0000

3.63E-10 0.0000

2.83E-08 0.0001

4.63E-10 0.0000
150 m 6.09E-10 0.0000 3.43E-10 0.0000 2.67E-08 0.0001 4.38E-10 0.0000

1805956.000 - 5209 49
Based on the assumptions applied in the air model, no meaningful risk from diesel emissions
associated with ash basin closure trucking operations was identified for people living and
working along the transportation corridor. The exposure model and risk assessment applied here
represent a simple approach to estimate risk. A more refined estimate of risk could be computed
with a more sophisticated air and risk model; however, it is unlikely to change the conclusion
that there is no meaningful risk to people living and working along the transportation corridor
from diesel emissions associated with ash basin closure construction operations.
9.2 The likelihood of noise, traffic, and accidents from
transportation activities is greater under the offsite
excavation closure option.
Increased trucking increases noise and traffic congestion and creates a statistically based risk for
increased traffic accidents that could result in fatalities, injuries, and/or property damage
(Forkenbrock 1999; NHTSA 2016). Allen is located on NC 273 (S. Point Rd) on a peninsula of
Lake Wylie. Due to weight restrictions on the bridge to the north of Allen, trucks must exit the
plant to the south on NC 273. This route passes through a lakeside residential community with
low to moderate traffic volume before crossing the South Fork of the Catawba River arm of
Lake Wylie. There will be an increase in trucking traffic under all closure options along this
route and beyond, with a statistically increased likelihood of traffic accidents. These potential
accidents and associated risks to life, health, and property would generally scale with the
frequency and duration of trucking, total number of truckloads, number of roundtrip truck trips
per day, and duration of the closure.
For purposes of the NEBA two attributes of offsite truck traffic that create disturbance to local
communities were considered: (1) noise and congestion and (2) accidents. Noise and congestion
were evaluated by comparing the number of times a construction truck would be expected to
pass a given location within 11 miles along the transportation corridor during closure
construction activities. The difference in the likelihood of traffic accidents between the closure
options was assumed to be a function of the number of offsite road miles driven by construction
trucks (NHTSA 2016).

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9.2.1 Noise and Congestion
Regardless of the option, closure of the ash basins at Allen will result in an increased number of
large trucks64 on local roads (Table 9-1). Noise from these trucks includes engine and braking
noise, which can be disruptive to the communities through which they are passing,65 and trucks
frequently passing through rural communities may pose additional disturbance from roadway
congestion. To compare the disturbance of trucking noise and congestion between closure
options, I used the average daily number of truck passes for trucks carrying ash, earthen fill, and
geosynthetic material to the construction site (Table 9-1). The number of passes of trucks
hauling ash from the ash basin to an onsite landfill (Excavation A option) was not considered
because these trucks do not leave the site; 66 however, trucks hauling ash to an offsite
landfill(Excavation B option) was included in the analyses. For the CIP option, it is estimated
that a total of 21,830 truck passes would occur at locations along the transportation corridor
within 11 miles of the facility over the 76-month course of trucking activities, for an average of
11 passes per day, or about one truck every hour, assuming a 10-hour work day.67 The
excavation options average 24,942 (Excavation A), or 1,697,265 (Excavation B) truck passes
per day for 210 months (Excavation A) or 200 months (Excavation B), or about one truck every
2 hours for Excavation A or one truck every 2 minutes for Excavation B. For the hybrid option,
there would be 19,600 truck passes per day, or one truck every 70 minutes. These results and
their relative differences (as the ratio to CIP closure) are summarized in Table 9-3.
9.2.2 Traffic Accidents
Traffic accidents are assumed to be a function of the total number of offsite road miles driven by
construction trucks (NHTSA 2016). As with noise and congestion, only the miles driven hauling
materials offsite were considered. The CIP option requires approximately 300,000 miles of
driving; excavation closure options A and B require approximately 332,000and 84,000,000
miles of driving, respectively; and hybrid closure requires approximately 257,000 miles of

64 Twenty-ton dump trucks, or similar vehicles for bulk transport, are assumed to be the primary vehicles that will
be involved in transporting materials during closure construction activities.
65 A typical construction dump truck noise level is approximately 88 decibels 50 ft. from the truck.
(https://www.fhwa.dot.gov/ENVIRONMENT/noise/construction_noise/handbook/handbook09.cfm)
66 Offsite transportation of earthen fill and geosynthetic materials were included for the analysis of Excavation A.
67 All closure options assume 10-hour work days, 6-day work weeks, and 26 working days per month.

1805956.000 - 5209 51
driving. The number of miles driven is similar between CIP, excavation to an onsite landfill
(Excavation A), and hybrid closure of the Allen basins; however, the difference in distance
driven between Excavation B and hybrid closure, as an example, is equivalent to more than 175
round trips to the moon. Table 9-3 summarizes the results for all disturbances considered.
Table 9-3. Comparative metrics for increased noise and congestion and traffic
accidents

Months of
trucking
Noise and congestion Traffic Accidents
Average truck
passes per day
Ratio to
CIP Total offsite
road miles driven
Ratio to
CIP
CIP 76 11 1 302,480 1
Excavation A 210 5 0.4 331,696 1.1
Excavation B 200 326 30 83,939,561 278
Hybrid 88 9 0.78 256,825 0.85
9.3 NEB A – Minimize Human Disturbance
From these analyses, no meaningful health risk is expected from diesel exhaust emissions under
any closure option, but all the closure options are expected to produce different levels of
community disturbance in the form of noise and traffic congestion and risk from traffic
accidents.
I used the number of trucks per day passing68 a receptor along a near-site transportation corridor
to examine the differences in noise and traffic congestion under the closure options. I compared
the increase in the average number of trucks hauling ash, earthen fill, geosynthetic material, and
other materials under the closure options to the current number of truck passes for the same
receptor. I specified a baseline, or current, level of truck passes on the transportation corridor,
and the number of truck passes per day under the closure options derive directly from the
trucking projections and implementation schedules provided by Duke Energy (2018).

68 Truck passes per day is calculated as the total number of loads requir ed to transport earthen fill, geosynthetic
material, and other materials multiplied by two to account for return trips. The resulting total number of passes
is then divided evenly among the total number of months of trucking time multiplied by 26 working d ays per
month.

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A baseline estimate of trucking passes per day for transportation corridors near Allen was
derived from North Carolina Department of Transportation (NCDOT) data of annual average
daily traffic (AADT) at thousands of locations across the state69 and the proportion of road miles
driven by large trucks in Gaston County.70 Based on the assumed 110-truck-per-day baseline
level and the number of truck trips per day from Duke Energy’s projections, the offsite
excavation closure option would create significant noise and traffic congestion, with an impact
of 296% (Excavation B); CIP, excavation to an onsite landfill (Excavation A), and hybrid
closures have substantially lower impacts on noise and traffic congestion (CIP = 10%,
Excavation A = 4 %, hybrid = 8%). I input these percent impacts to the risk-ranking matrix
(Table 5-4) along with the total duration of construction activities (6 years CIP; 18 years
Excavation A; 17 years Excavation B; and 7 years Hybrid) to evaluate which of the closure
options best minimizes human disturbances (Table 9-4).
I evaluated risk from traffic accidents by comparing the average number of annual offsite road
miles driven between closure options relative to a baseline estimate of the current road miles
driven.71 I chose a baseline of 120 million annual road miles for Gaston County, North Carolina,
based on the reported total vehicle miles traveled in Gaston County (NCDMV 2017) multiplied
by the county average 5% contribution of trucks to total AADT (NCDOT 2015). I used the
increase in truck miles driven over baseline in the closure options as a surrogate for the potential
increase in traffic accidents.

69 Annual average daily traffic (AADT) values are derived from counts of axle pairs in every lane travelling in
both directions using a pneumatic tube counter. At each monitoring station, raw data is collected for two days,
and these raw counts are adjusted using axle and seasonal correction factors to estimate the AADT. AADT
results are compared to historical values at the same location and values at nearby stations to provide temporal
and spatial quality assurance. AADT data and a mapping application user interface are available online
(http://ncdot.maps.arcgis.com/apps/webappviewer/index.html?id=5f6fe58c1d90482ab9107ccc03026280 ).
70 A value of 2,100 AADT was chosen as a baseline value for all vehicle traffic by identifying potential
transportation routes to and from the Allen ash basins and selecting the AADT station along the route that
currently has the lowest traffic and would experience the greatest proportional increase in trucking traffic from
ash basin closure. The baseline AADT value (2,100) was then multiplied by the county average of large truck
traffic volume (5%) to derive an estimated 110 passes per day along the most sen sitive portion of the
transportation corridor to and from Allen (Appendix E).
71 The difference of baseline miles and closure option miles was divided by the baseline miles and multiplied by
100 to get a percent impact.

1805956.000 - 5209 53
Using the 120-million-truck-miles baseline assumption, the CIP option has a 0.04% impact;
excavation options A and B have 0.02 and 4% impacts, respectively; and the hybrid closure
option has a 0.03% impact. All closure options have a relative risk rating of <5%. The relative
risk ratings for CIP, Excavation A, and Hybrid options appear to be generally insensitive to
lower assumed baseline annual truck miles (see Appendix E for sensitivity analysis). However,
for the offsite excavation option, reducing the baseline assumption (i.e., that there are fewer than
110 truck passes/day) increases the expected percent impact and relative risk rating. Assuming
the minimum statewide trucking value (6.2 million annual road miles in Hyde County) increases
the percent impact of Excavation B to 81%. Results are summarized in the NEBA framework
Table 9-4) within the objective of minimizing disturbance to humans during closure.

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Table 9-4. Summary of relative risk ratings for attributes that characterize
potential hazards to communities during remediation activities.
Darker shading and higher codes indicate greater impact.
Objective Minimize Human Disturbance
Hazard
Noise and
Traffic
Congestion
Traffic
Accidents
Air
Pollution Potentially Affected Populations Local Residents/Visitors Local Residents/Visitors Reasonable Maximum Exposure Scenario Baseline baseline baseline baseline
CIP 3B 3A --
Excavation A 5A 5A --
Excavation B 5F 5A --
Hybrid 3B 3A --
“--” indicates “no meaningful risk.”
All closure options create disturbance and risk to human populations; however, the cumulative
impact to the community is greatest under excavation closure to an offsite landfill.72
All closure options support safe air quality from diesel truck emissions along the transportation
routes; however, each creates disturbance and risk that could adversely impact community
safety, with a greater magnitude of impact from excavation closure to an offsite landfill. CIP,
excavation to an onsite landfill, and hybrid closures better satisfy the third objective of ash basin
closure—to minimize risk and disturbance to humans from closure.

72 Sensitivity analyses exploring different assumptions for disturbance and subsequent effects to relative risk
ratings are provided in Appendix E.

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10 Conclusion 4: Both hybrid closure and excavation
to an onsite landfill minimize environmental
disturbance.
Environmental services are derived from ecological processes or functions that have value to
individuals or society, with provision of a healthy environment to humans being one of the most
essential environmental services. Environmental services that support human health include
functions to purify freshwater, provide food, supply recreational opportunities, and contribute to
cultural values (MEA 2005). For example, forests provide habitat for deer that are hunted for
food; surface water supports fish populations that are food for bald eagles, a previously
threatened and endangered species highly valued by our society;73 and soil and wetlands purify
groundwater and surface water, respectively, by adsorbing contaminants. Central to weighing
the net environmental benefits of the closure options under consideration here is understanding
how they differentially impact the variety of environmental services at the site and in the area.
Allen, though an industrial site, supports a diversity of habitats that provide environmental
services. Figure 10-1 illustrates the types of habitats at the site. The ash impoundment provides
habitat that supports birds and mammals; the open water habitat of the impoundment also
removes solids from surface water by providing a low-flow environment in which ash particles
and other solids can settle into the sediment before the treated water can enter Lake Wylie. The
onsite forest provides biodiversity protection in the form of foraging, shelter, and breeding
habitat for birds and mammals, among other types of organisms; watershed protection;
landscape beauty; and carbon sequestration (Bishop and Landell-Mills 2012). Beyond Allen,
Lake Wylie and the Catawba River provide aquatic habitat that supports a variety of fish and
aquatic life (Abney et al. 2014), which then provide food for birds and mammals.

73 Bald eagles were taken off the federal list of threatened and endangered species in 2007
(https://www.fws.gov/midwest/eagle/).

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56

Figure 10-1. Map of habitat types currently present at Allen.
Reproduced from CAP-2 Appendix F, Figure 2-6 (HDR 2016c)

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Plants serve a vital ecosystem role by converting solar energy and carbon dioxide into food (for
themselves) and oxygen. Plants then become food for other organisms. As such, “plants provide
the energy and air required by most life forms on Earth.”74 NPP represents a measure of the
mass of chemically fixed carbon produced by a plant community during a given period and
reflects the rate at which different ecosystems are able to sequester carbon. Given the
foundational role of primary production in supporting ecological food webs and healthy air,
NPP is a good surrogate for environmental services provided by different habitat types
(Efroymson et al. 2003). For example, the annual NPP of a temperate forest habitat is
approximately 2.5 times higher than for temperate grasslands or freshwater ecosystems
(Ricklefs 2008). By multiplying the acres of habitat type by NPP, NPP becomes a single metric
by which to compare the different levels of environmental services impacted by ash basin
closure.75
The fourth objective for ash basin closure, to minimize environmental disturbance, is
represented by the environmental services protection of biodiversity and natural beauty. For
purposes of the NEBA, these considerations were evaluated based on differences in habitat-
derived services estimated from the NPP of impacted habitat acres under the closure options.
10.1 Excavation closure to an offsite landfill and CIP closure
result in a greater net loss of environmental services tha n
hybrid closure or closure to an onsite landfill.
Regardless of the closure option, habitat, and habitat-derived environmental services, will be
altered. CIP closure requires removing existing habitat within the footprint of the ash basin,
possible temporary removal of forest habitat to create a borrow pit to source earthen materials
for the cap, and restoring the ash basin with grass cap habitat. Excavation closure and landfilling
require temporary loss and future modification of existing habitats within the footprint of the
ash basin and permanent conversion of forest habitat to grass cap at the landfill site. The hybrid
option requires temporary loss and future modification of existing habitats within the footprint

74 https://earthobservatory.nasa.gov/GlobalMaps/view.php?d1=MOD17A2_M_PSN
75 I used rates of NPP by stand age from He et al. (2012, Figure 2c.) for mixed forests as the basis for establishing
NPP of onsite wooded habitats and used relative rates of NPP from Ricklefs (2008) to scale NPP for other
habitat types.

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of the ash basin. All closure options include restoration of the ash basin footprint, but the
collateral losses of habitat, the differences in service levels of restored habitat, and the timelines
for recovery of the habitats vary based on construction schedules and the acreages and types of
habitat lost or restored. This makes it challenging to appreciate the net gain or loss of
environmental services. To address this challenge, I used a habitat equivalency analysis (HEA)
to quantify the differences in environmental services resulting from each closure option.
HEA is an assessment method widely used in NRDA to facilitate restoration scaling for
environmental services (Dunford et al. 2004; Desvousges et al. 2018; Penn undated). Numerous
damage assessment restoration plans based on the use of HEA can be found on the U.S. Fish
and Wildlife Service76 and NOAA77 websites and include sites such as the St. Lawrence River
near Massena, New York; Onondaga Lake near Syracuse, New York; and LaVaca Bay in Texas.
As Desvousges et al. (2018) describe, use of HEA has expanded in recent years beyond original
applications for NRDA to address environmental service losses from other causes such as forest
fires and climate change. As the authors note, HEA has also been used as an assessment tool in
NEBA applications, such as evaluating the effects of transmission line routing on habitats of
greater sage-grouse (Centrocercus urophasianus), a proposed threatened species.
The objective of HEA is to estimate the amount of compensatory services necessary to equal the
value of the services lost because of a specific release or incident. The method calculates debits
based on services lost because of resource losses and credits for services gained due to resource
gains. The latter are often scaled to compensate for, or offset, the loss in services. A discount
rate is used to standardize the different time intervals in which the debits and credits occur, so
the services are usually expressed in terms of discounted acre-years of equivalent habitat, or
DSAYs (Dunford et al. 2004; Desvousges et al. 2018; Penn undated).
The HEA methodology was used here to estimate changes in environmental service levels that
will accrue under closure options. Environmental services currently provided by the site will be
eliminated when the ash basin is closed. After closure is complete, there will be a new level of

76 www.doi.gov/restoration
77 www.darrp.noaa.gov

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environmental services provided as habitat is restored. Since post-closure habitats may differ
from those that currently occur onsite, future services could be greater or less than what occurs
at present. Similarly, land used as a borrow area or converted to landfill, as per the closure
options, will also impact the net level of services, as services currently provided by those
habitats may be reduced or eliminated. The environmental service losses and gains from onsite
and offsite habitats must be considered together when determining the overall net effect of a
closure option.
A common ecological metric is required to make comparisons between service gains and losses
from various habitat types. For purposes of this evaluation, I used annual NPP as the metric to
standardize across habitat types. In terms of habitats currently occurring on the site, wooded
areas have the highest NPP, so that is used as the basis for defining service level, and the service
levels for other habitat types (open fields, open water) are expressed as a proportion of that
baseline service. Based on He et al. (2012), and assuming a tree stand age of 50 years, NPP
would be approximately 6.4 tons of carbon per hectare per year (6.4 t C/ha/yr) in wooded areas
onsite. Based on relative rates of NPP from Ricklefs (2008), the NPP for open field and open
water habitats would be approximately 40% of the temperate forest rate. To prevent
overestimation of NPP in open water areas of the ash basin that may not provide the same level
of NPP as natural freshwater habitats (perhaps from limited abundance or diversity of
vegetation), I assumed that open water areas of the ash basin produce NPP that is 25% that of
natural ecosystems.78 Therefore, I applied a four-fold habitat quality factor to scale NPP at these
open water areas of the ash basin to approximately 10% of the rate for wooded habitats.
Deforested land for borrow areas was assumed to be reforested after closure was complete, and
landfill areas were assumed to recover to grass cap. The grass cap on landfill was given a
service value of 8%,79 as was done for CIP.

78 I observed open water areas of the ash basin that supported aquatic vegetation but do not know the extent of
vegetation in the open water areas of the ash basin. Thus, I made a conservative assumption (i.e., one that
reduces the present value of the habitat) that these areas of the ash basin provide a reduced level of NPP
compared to natural open freshwater areas.
79 An open field provides a relatively lower NPP service level than forest habitat (40% of forest NPP; Ricklefs
2008), and since a grass cap requires periodic maintenance mowing, for purposes of the HEA it was assumed
never to reach a level of NPP service equivalent to an open field. Grass cap was assumed to have 20% of the
NPP service level for open field, which is 8% of forest NPP.

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For each closure option, I used the acreage of existing habitat types and the level of service of
that habitat type to establish a baseline level of service. Based on the timelines for the various
closure alternatives, a HEA was conducted to calculate the net change in service flow of the
closure area over the next 150 years at a 3% discount rate.80 Similarly, a HEA was run to
calculate the net change in environmental services deriving from areas used either as borrow or
for landfill expansion. Because NPP standardizes service levels across habitat types, the DSAY
estimates for all affected habitats can be summed to calculate the net service gain/loss
associated with each closure option. In addition to the assumptions identified above, several
other assumptions were made to support the HEA, which are described in Appendix D.
Results of the HEA are presented in Table 10-181 and indicate that all closure options will result
in a net loss of environmental services primarily from temporary or permanent loss of forest
habitat for borrow and landfill areas, reduced NPP services provided by a grass cap (cap and
landfill areas), and the long delay for restoration of forested habitat in the ash basin (excavation
options). These factors, collectively, adversely affect environmental services provided by the
impacted habitat acres such that environmental services produced after closure will not
compensate for the service losses resulting from the closure.

80 Environmental services in future years are discounted, which places a lower value on benefits that will take
longer to accrue. The basis for this is that humans place greater value on services in the present and less value
on services that occur in the future.
81 A full description of the methods, assumptions, results, and sensitivity analyses for the HEA are provided in
Appendix D.

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Table 10-1. Summary of NPP DSAYs for closure options
CIP Excavation A Excavation B Hybrid
Ash basin losses Open field −566 −661 −702 −634

Grass Cap −74 −106 −113 −12

Open Water −139 −137 −145 −153

Wetland −611 −609 −647 −679
Broadleaf Forest −831 −238 −254 −242
Needleleaf Forest −443 −320 −342 −339
Scrub/Shrub −430 −369 −392 −296
Wetland Forest −120 −114

Total losses −3,216 −2,439 −2,594 −2,468
Ash basin post-closure gains Open field 37 245 376 82

Grass Cap 445 96 221

Open Water 126 141 67
Broadleaf Forest 311 888 1,335 891
Needleleaf Forest 256 732 1,100 733
Scrub/Shrub 36 235 361 79
Wetland Forest 2 5 7 5

Total gains 1,087 −2,327 3,321 2,078
Landfill/borrow losses Forest −1,086 −296 −2,744
Wetland −1

Total losses −1,086 −298 −2,744
Landfill/borrow post-closure gains Forest 732
Grass Cap 15 126

Total gains 732 15 126
Net Gain/Loss per Option −2,483 −395 −1,891 −391
Note: DSAYs for specific habitat types are reported here rounded to the nearest whole number. As such, the net
gain/loss per option differs slightly from the sum of the individual DSAYs reported in the table.
10.2 NEBA – Minimize Environmental Disturbance
The impact of the closure options on environmental services was computed as the percentage
difference in DSAYs produced by the closure option and the absolute value of the DSAY losses.
The DSAY losses represent the NPP services that would have been produced by the site, borrow
areas, and landfills but for the project closure. The DSAY gains represent the NPP services
restored after project closure plus any future gains realized from existing habitats before
remediation begins. The sum of DSAY losses and gains represents the net change of NPP
services for the project resulting from closure. Dividing the closure option net DSAYs by the
absolute value of the DSAY losses provides a percentage of the impact. Percent impacts from
the closure options evaluated are provided in Table 10-2. The percent impacts were input to the

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risk-ranking matrix (Table 5-4) along with the duration of the closure activities (6 years CIP; 18
years Excavation A; 17 years Excavation B; 7 years hybrid) to evaluate, within the NEBA
construct, which of the closure options best minimizes environmental disturbances (Table 10-3).
Table 10-2. Percent impact of ash basin closure options.
CIP Excavation A Excavation B Hybrid
DSAY Lossesa 4,302 2,737 5,338 2,468
DSAY Gains 1,819 2,342 3,447 2,078
Percent Impact (%) 58% 14% 35% 16%
a Absolute value of DSAY losses is equivalent to baseline services of the affected habitat, but for
the closure
Table 10-3. Summary of relative risk ratings for habitat changes
that affect provision of environmental services.
Darker shading and higher codes indicate greater impact.
Objective
Minimize Environmental
Disturbance
Hazard Habitat Change
Attribute DSAYs
Scenario
Baseline baseline
CIP 3D
Excavation A 5B
Excavation B 5C
Hybrid 3B
Within the objective of minimizing environmental disturbance from closure, my analyses
indicate that all closure options adversely impact habitat-derived environmental services;
however, the adverse impacts of excavation closure to an offsite landfill and CIP closure as
currently defined are substantially larger than that of hybrid closure or excavation to an onsite
landfill.82 As such, hybrid and excavation to an onsite landfill (Excavation A) closure minimizes
impacts to the protection of biodiversity and natural beauty, best satisfying the fourth objective
of ash basin closure—to minimize risk and disturbance to the local environment from closure.

82 Note, however, that the environmental services lost due to CIP could be offset (see discussion in Section 11) by
a suitable reforestation project that would then result in all closure options causing no net loss of habitat -derived
environmental services in the HEA model

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11 Conclusion 5: Hybrid closure maximizes
environmental services.
Identifying environmental actions that maximize environmental services (the fifth objective for
ash basin closure) is a function of NEBA (Efroymson et al. 2003, 2004) and the overarching
objective that encompasses each of the other four objectives and all of the environmental
services that have been considered to this point. Table 11-1 summarizes the relative risk ratings
for all attributes and objectives. Impacts to environmental services considered in this NEBA
focused on key community-relevant concerns. Risk to construction workers from construction
operations, risks to local and global populations from increased greenhouse gas emissions, and
“wear-and-tear” damage to roadways from trucking were not estimated. Each of these risks,
however, would scale with the duration, frequency, and intensity of construction operations.
Sensitivity analyses of the specifications of the NEBA framework show th at the specific relative
risk ratings presented in this NEBA can change depending on how baseline is defined (see
Appendix E). The purpose of the risk matrix, and the risk ratings that result from it, is to
consolidate the results from a variety of different analyses for a variety of different data types
and attributes into a single framework for comparative analysis. It is imperative, however, to
consider the underlying information used to develop the risk ratings to interpret the differences
between closure options, particularly when percent impacts or durations of closure options are
similar but receive different risk ratings.
As noted in Section 5, NEBA analysis provides an opportunity to better understand the net
environmental benefits of possible closure options. If Duke Energy’s preferred closure option
for reasons not considered in the NEBA does not best maximize environmental services to the
local community as currently defined, the NEBA results provide insight into how environmental
services could be improved for that closure option. For instance, if Duke Energy’s preferred
closure option for Allen is CIP closure but the HEA results for the currently defined CIP closure
option estimate a net environmental service loss of 2,483 DSAYs, Duke Energy could consider
incorporating into an updated CIP closure plan for Allen a mitigation project that compensates
for the net environmental service losses projected from the currently defined CIP closure option.

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As an example, if Duke Energy started a reforestation project outside of the ash basin in 2022
(when onsite preparation of the ash basin begins), the reforestation project would gain 24.3
DSAYs/acre over the lifetime of the site (150 years in the HEA), requiring an approximate 102
acre project to compensate for the 2,483 DSAY loss projected in the HEA. Re-analysis of the
HEA component of the NEBA for the updated possible closure options would then result in no
net environmental losses (as NPP services) from habitat alteration of the basin for CIP closure,
but net losses would remain under the hybrid and excavation closure options.
From the closure options considered and the analyses presented in this report, which are based
on a scientific definition of risk acceptability and include no value weighting, a hybrid closure
as currently defined best maximizes environmental benefits compared to other closure options
because it offers equivalent protection of human and ecological health from CCR exposure and
results in substantially less disturbance to humans and the environment because of the relatively
low levels and duration of impacts. Thus, hybrid closure best satisfies the fifth objective of ash
basin closure—to maximize local environmental services.

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65
Table 11-1. NEBA for closure of the ash basin at Allen.
Darker shading and higher alphanumeric codes indicates greater impact.
Objective Protect Human Health from CCR Protect Ecological Health from CCR Minimize Human Disturbance
Minimize
Environmental
Disturbance
Hazard Exposure to CCR Exposure to CCR
Noise and
Traffic
Congestion
Traffic
Accidents
Air
Pollution Habitat Change Potentially Affected Populations Local Residents/Visitors Onsite Trespassers Onsite Construction Workers Offsite Recreational Swimmers Offsite Recreational Waders Offsite Recreational Boaters Offsite Recreational Fishers Offsite Subsistence Fishers Fish Populations Aquatic Omnivore Birds (mallard) Aquatic Piscivore Birds (great blue heron) Aquatic Herbivore Mammals (muskrat) Aquatic Piscivore Mammals (river otter) Terrestrial Omnivore Birds (robin) Terrestrial Carnivore Birds (red tail hawk) Terrestrial Herbivore Mammals (meadow vole) Terrestrial Carnivore Mammals (red fox) Local Residents/Visitors Local Residents/Visitors Reasonable Maximum Exposure DSAYs
Scenario
Baseline -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- baseline baseline baseline baseline
CIP -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3B 3A -- 3D
Excavation A -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5A 5A -- 5B
Excavation B -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5F 5A -- 5C
Hybrid -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3B 3A -- 3B
“--” indicates “no meaningful risk.”

1805956.000 - 5209 66
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Appendix A

Curriculum Vitae of
Dr. Ann Michelle Morrison, Sc.D.

Ann Michelle Morrison, Sc.D.
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Professional Profile
Dr. Morrison has over 20 years of experience evaluating the relationship between anthropogenic
contamination and health effects to aquatic life and humans. Dr. Morrison specializes in natural resource
damage assessment (NRDA), environmental causal analysis, and assessments of water quality
conditions. Dr. Morrison has provided scientific consultation regarding the design of field studies for
NRDA, and she has worked closely with legal counsel during scientific assessments and settlement
negotiations with state and federal trustees. Dr. Morrison has performed detailed technical assessments
of injuries to aquatic resources, including vegetation, benthic infauna, fishes, shellfishes, and corals. She
has also developed site-specific sediment toxicity thresholds based on the empirical r elationships of
chemical concentrations to biological effects. She has provided expert testimony concerning injury to
aquatic resources and the net environmental benefits of remediation alternatives .

Projects she has been involved with have concerned oil spills, sewage releases, heavy metal
contamination, and various industrial and municipal facilities that have generated complex releases to the
environment. Dr. Morrison applies statistical tools and weight-of-evidence approaches to delineate
exposure zones, predict the likelihood of contamination events, evaluate net environmental benefits, and
assess causation. She uses a broad knowledge of aquatic life and human health to assess risk and injury
to these populations.
Academic Credentials & Professional Honors
Sc.D., Environmental Health, Harvard University, 2004

M.S., Environmental Health, Harvard University, 2001

B.S., Biology, Rhodes College, 1997
Prior Experience
Senior Scientist, Sole Proprietor, Morrison Environmental Data Services, 2004 –2007

Data Analyst, ETI Professionals, 2005

Scientist, NIH Toxicology Training Grant, Harvard School of Public Health, 2000 –2004

Guest Student, Woods Hole Oceanographic Institution, Stegeman Lab, 2001–2004

Science Intern, Massachusetts Water Resources Authority, 03-05/2000, 10/2000-10/2001

Ann Michelle Morrison, Sc.D.
Senior Managing Scientist | Ecological & Biological Sciences
1 Mill and Main Place, Suite 150 | Maynard, MA 01754
[phone] tel | [e-mail]

Ann Michelle Morrison, Sc.D.
12/17 | Page 2
Research technician, Bermuda Biological Station for Research, Inc., Benthic Ecology Research Program
(BERP), Bermuda, 01/1998-09/1999, 06-08/2000

Research Intern, Bermuda Biological Station for Research, Inc., Benthic Ecol ogy Research Program
(BERP), Bermuda, 05/1997-12/1997

NSF Research Experience for Undergraduates Fellowship, Bermuda Biological Station for Research, Inc.,
Benthic Ecology Research Program (BERP), Bermuda, 08-11/1996
Professional Affiliations
American Chemical Society — ACS

Society for Risk Analysis — SRA

Society of Environmental Toxicology and Chemistry — SETAC

North Atlantic Chapter of SETAC
Publications
Mearns AJ, Reish DJ, Bissell M, Morrison AM, Rempel-Hester MA, Arthur C, Rutherford N, Pryor R.
Effects of pollution on marine organisms. Water Environment Research 2018; 90(10):1206–1300.
Mearns AJ, Reish DJ, Oshida PS, Morrison AM, Rempel-Hester MA, Arthur C, Rutherford N, Pryor R.
Effects of pollution on marine organisms. Water Environment Research 2017; 89(10):1704–1798.

Morrison AM, Edwards M, Buonagurio J, Cook L, Murray K, Boehm P. Assessing the representativeness
and sufficiency of water samples collected during an oil spill. Proceedings, 2017 International Oil Spill
Conference, Vol 2017, No 1.

Mearns AJ, Reish DJ, Oshida PS, Morrison AM, Rempel-Hester MA, Arthur C, Rutherford N, Pryor R.
Effects of pollution on marine organisms. Water Environment Research 2016; 88(10):1693–1807.

Morrison AM, Kashuba R, Menzie CA. Evaluating alternative causes of environmental change.
Environmental Perspectives 2016; 1.

Boehm PD, Morrison AM, Semenova S, Kashuba R, Ahnell A, Monti C. Comprehensive oil spill liability
estimation. Environmental Perspectives 2016; 1.

Boehm PD, Morrison AM. Oil spill liability modeling: helping to manage existential risks. Oil & Gas Insight,
2016; 4.

Morrison AMS, Goldstone JV, Lamb DC, Kubota A, Lemaire B, Stegeman JJ. Identification, modeling and
ligand affinity of early deuterostome CYP51s, and functional characterization o f recombinant zebrafish
sterol 14α-demethylase. Biochimica et Biophysica Acta, 2014; 1840:1825 –1836.

Menzie C, Kane Driscoll SB, Kierski M, Morrison AM. Advances in risk assessment in support of sediment
risk management. In: Processes, Assessment and Remediation of Contaminated Sediments. Reible DD
(ed), SERDP ESTCP Environmental Remediation Technology, Vol. 6, pp. 107–130, 2014.

Mudge S, Morrison AM. Tracking sources of sewage in the environment. Environmental Forensic Notes,
2010; 9.

Ann Michelle Morrison, Sc.D.
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Pietari J, Bigham G, Morrison AM. Source tracking for identification of microbial pollution sources.
Environmental Forensic Notes, 2009; 6.

Goldstone JV, Goldstone HMH, Morrison AM, Tarrant AM, Kern SE, Woodin BR, Stegeman JJ.
Cytochrome P450 1 genes in early deuterostomes (tunicates and sea urchins) and vertebrates (chicken
and frog): Origin and diversification of the CYP1 gene family. Molecular Biology and
Evolution 24(12):2619–31, 2007.

Morrison AM. Receiver Operating Characteristic (ROC) Curve Analysis of Antecedent R ainfall and the
Alewife/Mystic River Receiving Waters. Boston: Massachusetts Water Resources Authority. Report
ENQUAD 2005-04, 2005. 26 p.

Morrison AM, Coughlin K. Results of intensive monitoring at Boston Harbor beaches, 1996–2004. Boston,
Massachusetts Water Resources Authority, Report ENQUAD 2005-05, 76 pp., 2004.

Morrison AM, Coughlin K, Shine JP, Coull BA, Rex AC. Receiver operating characteristic curve analysis
of beach water quality indicator variables. Applied and Environmental Microbiology, 2003 ; 69:6405–6411.

Coughlin K, Stanley AM. Boston Harbor beach study suggests a change in beach management.
Coastlines, 2001; Issue 11.6.

Coughlin K, Stanley AM. Water quality at four Boston Harbor beaches: Results of intensive monitoring
1996–2000. Boston, Massachusetts Water Resources Authority, Report ENQUAD 2001-18, 46 pp., 2001.

Published Abstracts

Stegeman J, Handley-Goldstone H, Goldstone J, Tarrant A, Morrison AM, Wilson J, Kern S. Pantomic
studies in environmental toxicology answers, questions and extrapolation. Journal of Experimental
Zoology Part a-Comparative Experimental Biology, 2006; 305A:181.

Goldstone JV, Goldstone HMH, Morrison AM, Tarrant A, Kern SE, Woodin BR, Stegeman JJ. Functional
evolution of the cytochrome P450I gene family: Eviden ce of a pre-vertebrate origin. Marine Environmental
Research, 2006; 62: S47

Handley HH, Goldstone JV, Morrison AM, Tarrant, Wilson JY, Godard CA, Woodin BR, Stegeman JJ.
Abstracts from the 12th International Symposium on Pollutant Responses in Marine Orga nisms (PRIMO
12) — Receptors and Regulation of Cytochrome P450. Marine Environmental Research, 2004; 58:131+.

Morrison AM, Stegeman JJ. Abstracts from the Twelfth International Symposium on Pollutant Responses
in Marine Organisms (PRIMO 12) — Cloning, Expression and Characterization of Cytochrome P450 51:
An investigation of CYP51 azole sensitivity in aquatic animals. Marine Environmental Research, 2004;
58:131+.

Morrison AM, Stegeman JJ. CYP51 azole sensitivity in lower vertebrates and invertebrate. Drug
Metabolism Reviews: Biotransformation and Disposition of Xenobiotics, 2003; 35(2):179.

Presentations

Morrison AM, Ma J, Gard N, Palmquist K, Lin C, Deines A. Ecosystem services accounting in support of
corporate environmental stewardship in a changing climate. Society of Environmental Toxicology and
Chemistry (SETAC) North America 39th Annual Meeting, Sacramento, CA. November 5–8, 2018.
Pietari J, Morrison AM, Kashuba R, Boehm PD. Incorporating a framework for risk assessment, risk
management, and risk mitigation of extreme weather events at Superfund sites. Society of Environmental

Ann Michelle Morrison, Sc.D.
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Toxicology and Chemistry (SETAC) North America 39th Annual Meeting, Sacramento, CA. November 5–
8, 2018.
Deines AM, Palmquist K, Morrison AM. Global Status and Risk of Non-Native Fish Aquaculture. 148th
Annual Meeting of the American Fisheries Society, Atlantic City, NJ. August 19–23, 2018.
Morrison AM, Palmquist K, Kashuba R. Baseline in the Open-Access and “Big Data” Era. Law Seminars
International. Washington, D.C. March 1, 2018.
Palmquist K, Morrison AM, Edwards ME. Addressing white hat bias: Lessons from environmental
litigation. Society of Environmental Toxicology and Chemistry (SETAC) North America 38th Annual
Meeting, Minneapolis, MN. November 12–16, 2017.

Palmquist KR, Ginn TC, Morrison AM, Boehm PD. 2017. Addressing Spatial Data Gaps in Deep-sea
Benthic Sediment Sampling Following a Large-Scale Oil Spill. Battelle Sediment Conference in New
Orleans, LA.

Morrison AM. The Science. Natural Resource Damages 101. Law Seminars International. Washington,
D.C. March 9, 2016.

Morrison AM, Murray KJ, Cook LC, Boehm PD. Spatial and Temporal Extent of PAHs Associated with
Surface Oil Distributions (Anomalies). Gulf of Mexico Research Initiative Conference. Tampa, F L.
February 1–4, 2016.

Boehm PD, Morrison AM. The Interplay of Data Needs and Data Analysis Frameworks to Optimize the
Collection and Use of Data from Oil Spills. Gulf of Mexico Research Initiative Conference. Tampa, F L.
February 1–4, 2016.

Whaley JE, Morrison AM, Savery LC. Using the Causal Analysis Framework to Investigate Marine
Mammal Unusual Mortality Events (poster), Society of Marine Mammalogy Biennial Conference, San
Francisco, CA. December 2015.

Kashuba R, Morrison AM, Menzie C. The Application and Misapplicat ion of Directed Acyclic Graphs for
Causal Inference in Ecology. Society of Environmental Toxicology and Chemistry (SETAC) North America
36th Annual Meeting, Salt Lake City, UT. November 1–5, 2015.

Kierski M, Morrison AM, Kane Driscoll S, Menzie C. A Refined Multi-Site Model to Estimate the Toxicity of
PAH-Contaminated Sediments at MGP Sites. Society of Environmental Toxicology and Chemistry
(SETAC) North America 36th Annual Meeting, Salt Lake City, UT. November 1–5, 2015.

Morrison AM, McArdle M, Menzie C. A Tiered Approach to Causal Analysis in Natural Resource Damage
Assessment. 35th Annual Society of Environmental Toxicology and Chemistry (SETAC) Meeting,
Vancouver, BC, Canada. November 9–13, 2014.

Morrison AM, Kane Driscoll S, McArdle M, Menzie C. Integrated environmental benefit analysis of
sediment remediation thresholds. 32nd Annual Society of Environmental Toxicology and Chemistry
(SETAC) Meeting, Boston, MA. November 14–17, 2011.

Kierski M, Morrison AM, Kane Driscoll S, Menzie C. A multi-site model to estimate the toxicity of PAH
contaminated sediments at MGP sites. 32nd Annual Society of Environmental Toxicology and Chemistry
(SETAC) Meeting, Boston, MA. November 14–17, 2011.

Kierski M, Morrison AM, Kane Driscoll S, Menzie C. Use of receiver operating characteristic curve
analysis to estimate ecological risk zones as part of an ecological risk assessment. 31st Annual Society

Ann Michelle Morrison, Sc.D.
12/17 | Page 5
of Environmental Toxicology and Chemistry (SETAC) Meeting, Portland, OR. November 7–11, 2010.

Morrison AM, Coughlin K, Rex A. Bayesian network predictions of Enterococcus exceedances at four
Boston Harbor beaches. Water Resources Conference 2008, Amherst, MA . April 8, 2008.

Stegeman J, Handley-Goldstone H, Goldstone J, Tarrant A, Morrison AM, Wilson J, Kern S. Pantomic
studies in environmental toxicology answers, questions and extrapolation. 15th International Congress of
Comparative Endocrinology, Boston, MA. 2005.

Goldstone JV, Goldstone HMH, Morrison AM, Tarrant A, Kern SE, Woodin BR, Stegeman JJ. Functional
evolution of the cytochrome P450I gene family: Evidence of a pre-vertebrate origin. 13th International
Symposium on Pollutant Responses in Marine Organisms (PRIMO 13), Alessandria, Italy, June 2005.

Morrison AM, Stegeman JJ. CYP51 azole sensitivity in lower vertebrates and invertebrate. 12th North
American Meeting of the International Society for the Study of Xenobiotics, Providence, RI . October 12–
16, 2003.

Morrison AM, Stegeman JJ. Cloning, expression and characterization of Cytochrome P450 51: An
investigation of CYP51 azole sensitivity in aquatic animals. 12th International Symposium, Pollutant
Responses in Marine Organisms, Tampa, FL. May 2003.

Handley HH, Goldstone JV, Morrison AM, Tarrant AM, Wilson JY, Godard CA, Woodin BR, Stegeman JJ.
12th International Symposium, Pollutant Responses in Marine Organisms, Tampa, FL. May 2003.

Morrison AM, Coughlin KA, Shine JP, Coull BA, Rex AC. Receiver operating characteristic curve analysis
of beach water quality indicator variables. Pathogens, Bacterial Indicators, and Watersheds: Treatment,
Analysis, Source Tracking, and Phase II Stormwater Issues. New England Watershed Association,
Milford, MA. May 14, 2003.

Stanley AM, Coughlin KA, Shine JP, Coull BA, Rex AC. Receiver operating characteristic analysis is a
simple and effective tool for using rainfall data to predict bathing beach bacterial water quality. 102nd
General Meeting, American Society for Microbiology, Salt Lake City, UT . May 2002.

Coughlin K, Stanley AM. Five years of intensive monitoring at Boston harbor beaches: Overview of beach
water quality and use of the Enterococcus standard to predict water quality. Massachusetts Coastal Zone
Marine Monitoring Symposium, Boston, MA. May 2001.

Smith SR, Grayston LM, Stanley AM, Webster G, McKenna SA. CARICOMP coral reef monitoring: A
comparison of continuous intercept chain and video transect techniques. Scientific Aspects of Coral Reef
Assessment, Monitoring and Management, National Coral Reef Institute (NCRI), Nova Southeastern
University, Ft. Lauderdale, FL. 1999.
Project Experience
Dr. Morrison has been involved in numerous complex projects relating to environmental contamination
and potential risk to humans and biological resources in the affected environment.

Risk Assessments and Natural Resource Assessments

Expert witness concerning net environmental benefits from coal ash closure alternatives at two coal ash
plants in North Carolina. Roanoke River Basin Association v. Duke Energy Progress, LLC, United States
District Court, Middle District of North Carolina, Case No. 1:16-cv-607 and Roanoke River Basin
Association v. Duke Energy Progress, LLC, United States District Court, Middle District of North Carolina,
Case No. No. 1:17-cv-452.

Ann Michelle Morrison, Sc.D.
12/17 | Page 6

Expert witness concerning potential damages to terrestrial and aquatic resources, including coral reefs,
endangered sea turtles, fish and shellfish, and seagrass beds, resulting from a coastal development
project on the Caribbean island of Nevis. Anne Hendricks Bass vs. Director of Physical Planning,
Development Advisory Committee, and Caribbean Development Consultant Limited. Eastern Caribbean
Supreme Court, in the High Court of Justice Saint Christopher and Nevis, Nevis Circuit, Civil Case No.
NEVHCV2016/0014.

Expert witness concerning potential impacts to California fishery populations from the Refugio oil spill.
Andrews et al. v. Plains All American Pipeline, L.P. et al. United States District Court, Central District of
California, Wester Division, Case No. 2:15-cv-04113-PSG-JEM.

Provided analysis and technical support in Florida v. Georgia United States Supreme Court case that
considered questions of causation relative to alleged adverse ecological changes in downstream river
and bay populations.

Conducted a comprehensive review of an environmental impact assessment of potential impacts to coral
reefs from a proposed dairy farm development in Hawaii.

Provided scientific support for the Deepwater Horizon NRDA in the Gulf of Mexico.

Developed a cooperative NRDA field study in the offshore waters of the Gulf of Mexico to collect
sediment samples for analysis of chemistry, toxicology, and benthic infauna.

Expert witness concerning alleged injuries to aquatic resources from disposal of bauxite ore processing
wastes for the case: Commissioner of the Department of Planning and Natural Resources, Alicia V.
Barnes, et al. v. Virgin Islands Alumina Company et al. District Court of the Virgin Islands, Division of St.
Croix, Civil Case No. 2005-0062.

Developed decision management products for beach water quality stakeholders using statistical data
analysis tools such as receiver operating characteristic (ROC) curves and Bayesian networks to improve
public beach advisories related to elevated fecal bacteria.

Developed net environmental benefit analysis (NEBA) for a lead contaminated river. This analysis used
site-specific data to evaluate the costs and benefits of two different remediation options that were being
considered. The NEBA was successfully used by the client to negotiate a higher remediation goal than
original proposed by the state Department of Environmental Protection.

Performed ROC curve analyses of site-specific polycyclic aromatic hydrocarbon (PAH) toxicity data to
assess the relationship between PAH concentration and toxicity at three ecological risk assessment
projects in Wisconsin. The curves were used to identify site-specific toxicity thresholds for PAH
concentration in sediment that were indicative of various zones of toxicity (no toxicity, low tox icity, and
high toxicity), with very limited misidentification of sediments.

Provided research support to calculate site-specific no-observed-adverse-effect level (NOAEL) and
lowest-observed-adverse-effect level (LOAEL) concentrations for mammals and birds for use in a
baseline ecological risk assessment in Wisconsin.

Performed ROC curve analysis of national mercury toxicity data to assess the relationship between
mercury concentration and toxicity. The curves were also used to identify a threshold mercur y
concentration for sediment that indicates likely toxicity, with very limited misidentification of sediments that
are not toxic.

Assembled and analyzed data and reviewed remedial investigations to conduct a screening-level

Ann Michelle Morrison, Sc.D.
12/17 | Page 7
ecological risk assessment for sediment, surface water, and groundwater for a site in Connecticut. The
chemicals considered were total petroleum hydrocarbons (TPH), metals, and PAHs.

Reviewed species lists and created summary descriptions of organisms that could be potentially impacted
by dam construction on a high-altitude river in the Caribbean. This information was important to develop
the risk assessment from dam construction.

Researched the toxicity of malathion to fish to support a technical review of the National Marine Fisherie s
biological opinion for the registration of pesticides containing malathion.

Ecological and Toxicity Studies

Conducted surveys to assess the health of coral reefs, seagrass beds, and mangrove swamps in the
nearshore environment of Bermuda. Projects included area-wide habitat surveys as well as targeted sites
potentially impacted by a heavy metals dump, hot water effluent from an incinerator, sedimentation from
cruise ship traffic, and chronic release of raw sewage. In addition to ecological surveys, wate r quality was
assessed through measurements of trace metals in water, sediment, and coral tissue.

Surveyed juvenile coral recruitment in the Florida Keys to evaluate if marine protected areas (MPA s)
provide a benefit to coral recruitment.

Studied cytochrome P450 family enzymes, including CYP51 and CYP1, examining their sensitivity to
environmental chemicals and their evolution through molecular biology and biochemistry approaches.

Environmental Forensics Projects

Performed document review, information m anagement, and technical writing for numerous complex
projects that dealt with historical petroleum contamination and multiple site owners in several types of
environmental media.

Reviewed documents, assembled data, and researched metal concentrations associated with crude oil
and railroads in support of a Superfund project in Oklahoma.

Examined the correlation of multiple contaminants (PAHs, metals) with polychlorinated biphenyl (PCB)
congeners at a historically contaminated site in Alabama to identify the likely origins of the PCB
contamination.

Performed statistical analysis to determine source contribution in a chemical fingerprinting case at a
Superfund site in Washington that involved hydrocarbons in water, sediment, and groundwater.

Human Health Projects

Organized, managed, and simplified a complex database of field sampling reports for a litigation case in
Louisiana regarding human air exposure to PAHs.

Performed data analysis and document review for a Superfund site in Oklahoma. The analyses us ed
hydrocarbon chromatograms and limited PAH and metal data to identify the likely sources of
contamination.

Researched and compiled screening-level human health inhalation toxicity values for refinery-related
gases for an overseas project.

Developed a questionnaire and related database for industrial hygiene surveys to support regulatory
compliance for a highly specialized industry.

Appendix B

Human Health and Ecological
Risk Assessment Summary
Update for Allen Steam
Station

tt Huddleston, Ph.D.
Senior Ma
Scientist
Heather Smith
Environmental Scientist

HUMAN HEALTH AND
ECOLOGICAL RISK ASSESSMENT
SUMMARY UPDATE
For

ALLEN STEAM STATION
253 PLANT ALLEN ROAD
BELMONT, NC 28012
NOVEMBER 2018
PREPARED FOR
DUKE ENERGY CAROLINAS, LLC
526 SOUTH CHURCH STREET
CHARLOTTE, NORTH CAROLINA 28202

Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 1
1.0 INTRODUCTION
This update to the Allen Steam Station (Allen or Site) human health and ecological risk
assessment incorporates results from sampling events conducted November 2004
through July 2018. The samples were collected from surface water, sediment, and
groundwater. This update was performed in support of a Net Environmental Benefits
Analysis. As set forth below in detail, this updated risk assessment concludes that: (1)
the Allen ash basins do not cause any material increase in risks to human health for
potential human receptors located on-Site or off-Site; and (2) the Allen ash basins do not
cause any material increase in risks to ecological receptors.
The original 2016 risk assessment was a component of the Corrective Action Plan Part 2
pertaining to Allen (HDR, 2016). To assist in corrective action decision making, the risk
assessment characterized potential effects on humans and wildlife exposed to naturally
occurring elements, often associated with coal ash, present in environmental media.
Corrective action is to be implemented with the goal of ensuring future site conditions
remain protective of human health and the environment, as required by the 2014 North
Carolina General Assembly Session Law 2014-122, Coal Ash Management Act (CAMA).
The risk assessment was updated as part of the 2018 Comprehensive Site Assessment
(CSA) Update report (SynTerra, 2018). This update follows the methods of the 2016 risk
assessment (HDR, 2016) and is based on U.S. Environmental Protection Agency
(USEPA) risk assessment guidance (USEPA, 1989; 1991; 1998).
Areas of wetness (AOWs), or seeps, are not subject to this risk assessment update.
AOWs associated with engineered structures, also referred to as “constructed seeps,”
have been addressed in a National Pollutant Discharge Elimination System (NPDES)
permit. Other AOWs (non-constructed seeps) are now addressed under a Special Order
by Consent (SOC) issued by the North Carolina Environmental Management
Commission (EMC SOC WQ S17-009). Many AOWs are expected to reduce in flow or
be eliminated after decanting (i.e., removal of the free water). The SOC requires that
any seeps remaining after decanting must be addressed with a corrective action plan
that must ”protect public health, safety, and welfare, the environment, and natural
resources” (EMC SOC WQ S17-009, 2. d.).
This risk assessment update includes results from samples of surface water, sediment,
and groundwater collected since the 2018 CSA update. New information regarding
groundwater flow and the treatment of source areas other than the ash basins has
resulted in refinement of exposure pathways and exposure areas. The Conceptual Site
Models (CSMs) (Figures 1 and 2) reflect potentially complete exposure pathways with
potential risks, and ecological exposure areas are depicted in Figure 3. Human health
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 2
risks were evaluated Site-wide and in adjacent areas, so no exposure area figure is
provided. Changes to the CSMs include:
• Exposure to coal combustion residual (CCR) constituents by Site workers is
considered incomplete, because Duke Energy maintains strict health and safety
requirements and training. The use of personal protective equipment (e.g., boots,
gloves, safety glasses) and other safety behaviors exhibited by Site workers limits
exposure to CCR constituents. Following conservative risk assessment practices,
the initial risk assessment report considered CCR constituent exposure pathways
for Site workers to be potentially complete. Further information has revealed
that on-Site worker exposure pathways are incomplete, and this risk assessment
update has been revised to reflect this change.
• The number of ecological exposure areas was reduced from four to two, as
depicted in Figure 3. Other ecological exposure areas evaluated in the 2016 risk
assessment were eliminated because updated modeling and data collection
demonstrate that they are not influenced by groundwater migration from the ash
basins.
• Surface water sampling and sediment sampling of the Catawba River allow for
the direct assessment, rather than using AOW data as a surrogate.
Results from samples of surface water, sediment, and groundwater were compared
with human health and ecological screening values (Attachments 1 and 2) to identify
constituents of potential concern (COPCs) for further review. Exposure point
concentrations (EPCs) were calculated for COPCs (Attachments 3 and 4) to incorporate
into human health and ecological risk models. Results of risk estimates (Attachments 5
and 6) are summarized below.
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 3
2.0 SUMMARY OF RISK FINDINGS
2.1 Human Health
There is no current exposure to residential receptors at Allen because no one lives on-
Site or near enough to the Site to be affected by groundwater migration from the ash
basins. Groundwater sample analytical results from monitoring wells between the ash
basins and residences do not indicate plume migration toward former supply wells.
CCR indicator constituents such as boron and sulfate have not been detected in the
monitoring wells or supply wells, or if detected, the concentrations were no greater
than a fraction of North Carolina’s applicable groundwater standards (15A NCAC
02L.0202), and similar to site-specific background values. Currently, residences west of
the Site are connected to domestic water lines from the city of Belmont. Therefore, the
exposure pathway for residential receptors via ingestion of groundwater is considered
incomplete.
Other potential receptors off-Site are recreational users of the Catawba River, including
swimmers, waders, boaters, and fishers. However, background concentrations in the
Catawba River of the same elements also present similar risks to the same potential
receptors. Those risks are not associated with the ash basins.
• There is no material increase in cancer risks attributable to the ash basins
associated with the boater, swimmer, and wader exposure scenarios.
o There is no material increase in cancer risks for the boater, swimmer, and
wader exposure scenarios attributable to the ash basins. Incorporating
hexavalent chromium concentrations in surface water samples collected
since the 2018 CSA update produced modeled potential carcinogenic risks
under the boater, swimmer, and wader scenarios. However, these
modeled risks are not materially greater than the background level of risk.
The hexavalent chromium EPC calculated based on sampling data for use
in the risk assessment was 0.3 µg/L, compared to the upstream
concentration of 0.03 µg/L. Although the EPCs are greater than the
background concentrations, they do not produce a materially greater
amount of risk in the model. There is, therefore, no material increase in
cancer risks attributable to the ash basins.
o No evidence of non-carcinogenic risks for the recreational swimmer,
wader, or boater exposure scenarios was identified.
• There is no material increase in cancer risks attributable to the ash basins
associated with the fisher exposure scenario.
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 4
o There is no material increase in cancer risks for the fisher exposure
scenario attributable to the ash basins. Hexavalent chromium
concentrations in surface water produced modeled results of potential
carcinogenic risks under the recreational and subsistence fishing exposure
scenarios. Subsistence fishing, defined by USEPA (2000) as ingestion of
170 grams (0.375 pounds) of fish per day, has not been identified on the
Catawba River or near the Site. But even if there were subsistence fishers
using these water bodies, there would be no material increase in risks to
them posed by the ash basins.1 Substituting hexavalent chromium
concentrations detected in surface water samples upstream of the Site also
resulted in modeled potential risks under the exposure assumptions. The
ash basins do not materially increase the background level of cancer risks
in the fisher scenario. Moreover, risk estimates from fish consumption are
based on CCR constituent concentrations in fish tissue modeled from
concentrations detected in surface water. Thus, the modeled
concentration of hexavalent chromium in fish tissue is likely
overestimated.2
o There is no evidence of non-carcinogenic risks associated with the
recreational and subsistence fish exposure scenarios.
• The updated risk assessment found no evidence of risks associated with
exposure to groundwater by Site workers. Trespasser exposure to AOWs was
not evaluated because AOWs are addressed in the SOC. There is, therefore, no
increase in risks associated with onsite exposure scenarios.
In summary, there is no material increase in risks to human health attributable to the
Allen ash basins.

1 To put the fish ingestion rate into context, a 170 gram per day fish meal is approximately equal to six
ounces or approximately five fish sticks per meal (see http://gortons.com/product/original-batter-
tenders); it is assumed that the subsistence fisher catches this amount of fish in the local water body and
has such a fish meal once per day, every day for years.
2 For conservative estimation of hexavalent chromium concentrations in fish tissue, the recreational and
subsistence fisher exposure models used in this risk assessment assume a hexavalent chromium
bioconcentration factor (BCF) of 200 (NRCP, 1996). Bioconcentration is the process by which a chemical is
absorbed by an organism from the ambient environment through its respiratory and dermal surfaces
(Arnot and Gobus, 2006). The degree to which bioconcentration occurs is expressed as the BCF.
Published BCFs for hexavalent chromium in fish can be as low as one, suggesting that potential
bioconcentration in fish is low (USEPA, 1980; 1984; Fishbein, 1981; ATSDR, 2012). The conservative BCF
of 200 used here likely overestimates the hexavalent chromium concentration in fish tissue.
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 5
2.2 Ecological
There is no evidence of ecological risks associated with the Catawba River (Exposure
Area 1) or the wetland area (Exposure Area 4).
• In practice, ecological risks are quantified by comparing an average daily dose
(ADD) of a constituent to a toxicity reference value (TRV) for a given wildlife
receptor. The ratio of the ADD and TRV is the hazard quotient (HQ), where an
HQ less than unity (1) indicates no evidence of risks. TRVs are generally no-
observed-adverse-effects-levels (NOAEL) or a lowest-observed-adverse-effects-
levels (LOAEL) from toxicity studies published in scientific literature.
• No HQs based on LOAELs exceeded unity for the wildlife receptors (mallard
duck, great blue heron, muskrat, river otter, American robin, red-tailed hawk,
meadow vole, red fox) exposed to surface water and sediments.
• One HQ based on a NOAEL of aluminum was 5.15 for the meadow vole. The
modeled risk related to aluminum is negligible. Moreover, the model likely
overestimates any real risk. Aluminum occurs naturally in soil, sediment and
surface water in this area. Per the U.S. Geological Survey (USGS), aluminum is
the third most abundant element following oxygen and silicon in the Earth's
crust (USGS, 2018). For example, the aluminum concentration in the Catawba
River surface water upstream of the Site was as much as 510 µg/L, compared to
the EPC used in the risk assessment of 314 µg/L.
In summary, the Allen ash basins do not cause any increase in risks to ecological
receptors.
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 6
3.0 REFERENCES
Agency for Toxic Substances and Disease Registry (ATSDR). (2012). Toxicological
Profile for Chromium. Atlanta, GA: U.S. Department of Health and Human
Services, Public Health Service.
Arnot, J.A. and F.A.P.C. Gobus. (2006). A review of bioconcentration factor (BCF) and
bioaccumulation factor (BAF) assessments for organic chemicals in aquatic
organisms. Environmental Reviews 14: 257–297.
Fishbein, L. (1981). Sources, transport and alterations of metal compounds: an
overview. I. Arsenic, beryllium, cadmium, chromium, and nickel.
Environmental Health Perspectives 40: 43-64.
HDR. (2016). Corrective Action Plan Part 2 - Allen Steam Station Ash Basin, February
19, 2016.
National Council on Radiation Protection and Measurements (NCRP). (1996).
Screening Models for Releases of Radionuclides to Atmosphere, Surface Water
and Ground. NCR Report No. 123. Cited in:
https://www.tn.gov/assets/entities/health/attachments/Screen.pdf
SynTerra. (2018). 2018 Comprehensive Site Assessment Update, January 31, 2018.
United States Environmental Protection Agency. (1980). Ambient water quality criteria
for chromium. Washington, D.C. EPA 440/5-80-035.
United States Environmental Protection Agency. (1984). Health assessment document
for chromium. Research Triangle Park, NC. EPA 600/8-83-014F.
United States Environmental Protection Agency. (1989). Risk Assessment Guidance for
Superfund: Volume 1 - Human Health Evaluation Manual (Part A). Office of
Emergency and Remedial Response, Washington, D.C. EPA/540/1-89/002.
United States Environmental Protection Agency. (1991). Risk Assessment Guidance for
Superfund: Volume 1 - Human Health Evaluation Manual (Part B, Development
of Risk-based Preliminary Remediation Goals). Office of Emergency and
Remedial Response, Washington, D.C. EPA/540/R-92/003.
United States Environmental Protection Agency. (1998). Guidelines for Ecological Risk
Assessment. Washington, D.C. EPA/630/R-95/002F.
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

Page 7
United States Environmental Protection Agency. (2000). Guidance for Assessing
Chemical Contaminant Data for Use in Fish Advisories. Volume 1, Fish
Sampling and Analysis, Third Edition. Office of Science and Technology, Office
of Water, Washington, D.C. EPA 823-B-00-007.
United States Geological Survey. (2018, October 29). Aluminum Statistics and
Information. Retrieved from
https://minerals.usgs.gov/minerals/pubs/commodity/aluminum/
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

FIGURES
š
Active Coal Ash
Basin
(d)
Post Excavation
Soil
AOWs (e)
Groundwater
Dust Outdoor Air
Soil Remaining
Post-Excavation
(f)
Surface Water
(Off-site)
(h)
Surface Water
(On -site)
(g)
Sediment
(Off-site)
(h)
Fish Tissue
(i)
Groundwater
(g)
Migration to
Surface Water
and Sediment
Inhalation
Incidental
Ingestion
Dermal Contact
Drinking Water
Use (b)
Incidental
Ingestion
Incidental
Ingestion
Dermal Contact
Incidental
Ingestion
Dermal Contact
Ingestion
Drinking Water
Use (b)
Dermal Contact
Incidental
Ingestion
Potential
Exposure
Route
Current/
Future Off-Site
Resident
Adult/Child
Current/
Future On-Site
Recreational
Trespasser
Current/
Future Off-Site
Recreational
Swimmer
Current/
Future Off-Site
Recreational
Wader
Current/
Future Off-Site
Recreational
Boater
Current/
Future Off-Site
Recreational /
Subsistence
Fisher
Current/
Future On-site
Commercial/
Industrial
Worker
Current/
Future On-Site
Construction
Worker
š š š š
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š š š š š
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š š š š š š š š š(C)š š
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š š š š ˜š š
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š š š š
Primary
Sources
Primary
Release
Mechanisms
Secondary
Sources
Secondary
Release
Mechanisms
Potential
Exposure
Media
Human Receptors
˜
š
(a)
Potentially complete exposure pathway based on results of 2018 risk assessment
update .
Pathway evaluated and found incomplete/insignificant.
Incidental surface water ingestion assumed only to occur for receptors for the swimming
and wading scenarios.
Infiltration/
Leaching
Runoff/Flooding
Infiltration/
Leaching
Dermal Contact š š š ˜˜
AOW Water
(On -site)Dermal Contact š š š š š
AOW Soil
(On -site)Dermal Contact
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(On -site)
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NOTES
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(d)
Catawba River is a source of public drinking water i.e., WS -IV, water is treated
before use. There are no private residences located hydraullically downgradient of
on-site groundwater.
Groundwater exposure evaluated in the risk assessment udate, although an
incomplete exposure pathway for construction worker.
Active and inactive ash basins and structural fill are present onsite as part of the
steam station.
š
(g)
Concentration of COPC in fish tissue modeled from surface water concentration .
FIGURE 1
HUMAN HEALTH RISK ASSESSMENT
CONCEPTUAL SITE MODEL
ALLEN STEAM STATION
BELMONT, NORTH CAROLINA
š š
š š
Catawba River. (h)
(i)
Site-wide data are used to evaluate on-site exposure.
Pathway incomplete as long as ash remains in place ; re-evaluation upon excavation
(if conducted) may be warranted.
(f)
Areas of Wetness (AOWs) are addressed in the Special Order by Consent (SOC) and
not evaluated in the risk assessment update at this time.
(e)
š š š š
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š š š š
š
š
˜
š
š
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MammalMammal
š š
š
˜˜
Red Fox
(Carnivore)
š
š
š
š
š
š
River Otter
(Piscivore )
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š
š
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š
š
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Robin
(Omnivore)
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š
š
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Avian
š
TERRESTRIAL RECEPTORS
Inhalation
Plant/Incidental
Ingestion
Direct Contact
Ingestion
Ingestion
Direct Contact
Plant/Incidental
Ingestion
Direct Contact
Ingestion
Direct Contact
Ingestion
Potential
Exposure Route Fish
š
š
š
Primary Sources Primary Release
Mechanisms
Secondary
Sources
Secondary Release
Mechanisms
Potential
Exposure Media
AQUATIC RECEPTORS
Direct Contact ˜(e)
Ingestion š
Plant/Incidental
Ingestion
Plant/Incidental
Ingestion
Direct Contact
š
š
š
š
š
š
š
š
š
Active Coal
Ash Basin
(a)
Post Excavation
Soil
AOWs (b)
Groundwater
Dust Outdoor Air
Soil Remaining
Post-Excavation
(c)
Surface Water
(Off-site )
Surface Water
(On-site)
Sediment
(Off-site)
Fish Tissue
(d)
Groundwater
Migration to
Surface Water
and Sediment
Infiltration/
Leaching
Runoff/Flooding
Infiltration/
Leaching
AOW Water
(On-site)
AOW Soil
(On-site)
Sediment
(On-site)
˜
š
Potentially complete exposure pathway based on results of 2018 risk assessment
update.
Pathway evaluated and found incomplete/insignificant.
Benthic
Invertebrates Mallard
(Omnivore)
Great Blue
Heron
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Muskrat
(Herbivore)
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Meadow Vole
(Herbivore)
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Red-Tailed
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š
š
š (a)Active and inactive ash basins and structural fill are present on-site as part of the steam
station.
(b)Areas of Wetness (AOWs) are addressed in the Special Order by Consent (SOC) and not
evaluated in the risk assessment update at this time.
š š
˜˜š š
š
š
NOTES
Pathway incomplete as long as ash remains in place ; re-evaluation upon excavation (if
conducted) may be warranted.
Based on screening against aquatic criteria.
CSM reflects exposure pathways evaluated quantitatively in the risk assessment .
š š š š š š š
š š š
š š
š š
š
š
FIGURE 2
ECOLOGICAL RISK ASSESSMENT
CONCEPTUAL SITE MODEL
ALLEN STEAM STATION
BELMONT, NORTH CAROLINA
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Concentration in fish tissue modeled from surface water concentration.
(c)
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S POINT RDSOUTHPOINT RD1. GENERA LIZED AREAL E XTENT OF MIGRATION REPRESENTED BY NCAC 02LEXCEEDANCES OF MULTIPL E CONS TITUENTS (BORON AND ARSENIC) IN MULTIPLEFLOW ZONES.
2. GENERA LIZED AREAL E XTENT OF MIGRATION REPRESENTED BY NCAC 02LEXCEEDANCES OF MULTIPL E CONS TITUENTS (B ERYLLIUM, NICKEL, SULFATE, ANDTHALLIUM) IN MULTIPLE FLOW ZONES. A S EPARATE ASSESSMENT IS PLANNED FORTHE COAL PILE AREA.
3. FOUR EXPOS URE AREAS WERE DEVELOPED TO EVALUATE ECOLOGICALEXPOSURE TO SURFACE WATER AND SEDIMENT. THE EXPOSURE AREASCONSIDER ECOL OGICA L HABITATS, NE ARBY WATER BODIES, AND WET AREAS.
4. EXPOS URE AREA 2 & 3 ARE N OT EVALUATED DUE TO NO CCR RELATEDINFLUENCE AT THES E LOCATIONS.
5. NATURAL RESOURCES TECHNICAL REPORT (NRTR) PREPARED BY AMEC FOSTERWHEELER, INC., MAY 29, 2015.
6. PROPE RTY BOUNDARY PROVIDED BY DUKE ENERGY CAROLINAS.
7. AERIAL PHOTOGRAPHY OBTAINE D F ROM GOOGLE EARTH PRO ON OCTOBER 11,2017. AERIAL WAS C OLLECT ED ON OCTOBER 8, 2016.
8. DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CAROLINA STATEPLANE COORDINATE SYSTEM FIPS 3200 (NAD83).
FIGURE 3HUMAN H EALTH ANDECOLOGICAL EXPOSURE AREASALLEN STEAM STATIONDUKE ENERGY CAROLINAS, LLCBELMONT, NORTH CAROLINADRAWN BY: B. YOUNGPROJECT MANAGER: C. SUTTELLCHECKED BY: L. DRAGO
DATE: 10/30/2018
148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE [phone]www.synterracorp.com
P:\Duke Energy Progress.1026\00 GIS B ASE DATA\A llen\M ap_Docs\MISC\Risk Assessment\Fig03_Allen_ExposureAreas.mxd
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GRAP HIC S CALE IN FEET
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EXPOSURE AREA 2
EXPOSURE AREA 3
EXPOSURE AREA 4
AR EA OF CONCENTRATION IN GROUNDWATERABOVE NC2L (SEE NOTE 1)
AR EA OF CONCENTRATION IN GROUNDWATERABOVE NC2L POTENTIALLY ATTRIBUTABLE TOTHE COAL PILE (SEE NOTE 2)ASH BASIN WASTE BOUNDARY
INACTIVE ASH BASIN WASTE BOUNDARY
LANDFILL BOUNDARY
DORS FILLS BOUNDARIES
ASH BASIN COMPLIANCE BOUNDARY
LANDFILL COMPLIANCE BOUNDARY
DUKE ENERGY CAROLINAS ALLEN PLANTSITE BOUNDARY
<STREAM (AMEC NRTR 2015)
WETLAND (AMEC NRTR 2015)
LEGEND
NOTES
Risk Assessment Summary Update November 2018
Allen Steam Station SynTerra

ATTACHMENTS

TABLE 1-1
HUMAN HEALTH SCREENING - GROUNDWATER
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Min.Max.
Aluminum 7429-90-5 742 555 7 101,000 101,000 NA NA 3,500 50 to 200 (i)4,000 3,500 Y
Antimony 7440-36-0 1,265 382 0.1 27 27 1 NA 1 6 1.56 (m)1 Y
Arsenic 7440-38-2 1,370 982 0.045 697 697 10 NA 10 10 0.052 (h,jj)10 Y
Barium 7440-39-3 1,370 1,345 2.5 1,640 1,640 700 NA 700 2,000 760 700 Y
Beryllium 7440-41-7 1,148 499 0.01 53 53 NA 4 4 4 5 4 Y
Boron 7440-42-8 1,352 639 25.2 6,200 6,200 700 NA 700 NA 800 700 Y
Cadmium 7440-43-9 1,370 215 0.025 13.1 13.1 2 NA 2 5 1.84 2 Y
Chromium (Total)7440-47-3 1,370 1,139 0.1 393 393 10 NA 10 100 4,400 (n)10 Y
Chromium (VI)18540-29-9 573 483 0.0094 31.1 31.1 NA NA 0.07 NA 0.035 (jj)0.07 Y
Cobalt 7440-48-4 1,148 1,050 0.011 5,350 5350 NA 1 1 NA 1.2 1 Y
Copper 7440-50-8 964 643 0.11 337 337 1,000 NA 1,000 1,300 (k)160 1,000 N
Lead 7439-92-1 1,370 473 0.028 14.6 14.6 15 NA 15 15 (l)15 (jj)15 N
Lithium 7439-93-2 528 510 0.088 820 820 NA NA NA NA 8 8 Y
Manganese 7439-96-5 964 843 2.5 240,000 240,000 50 NA 200 50 (i)86 50 Y
Mercury 7439-97-6 1,366 57 0.07 0.67 0.67 1 NA 1 2 1.14 (o)1 N
Molybdenum 7439-98-7 1,148 709 0.09 264 264 NA NA 18 NA 20 18 Y
Nickel 7440-02-0 937 626 0.14 1,130 1,130 100 NA 100 NA 78 (p)100 Y
Selenium 7782-49-2 1,370 424 0.17 1,200 1,200 20 NA 20 50 20 20 Y
Strontium 7440-24-6 733 732 3.6 3,200 3,200 NA NA 2,100 NA 2,400 2,100 Y
Thallium 7440-28-0 1,265 357 0.016 3.1 3.1 0.2 NA 0.2 2 0.04 (q)0.2 Y
Vanadium 7440-62-2 742 687 0.059 93.2 93.2 NA NA 0.3 NA 17.2 0.3 Y
Zinc 7440-66-6 964 522 2.5 2,390 2,390 1 NA 1 5,000 (i)1,200 1 Y
Notes:
AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources NC - North Carolina su - Standard units
CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services NCAC - North Carolina Administrative Code µg/L - micrograms/liter
North Carolina Session Law 2014-122, ESV - Ecological Screening Value ORNL - Oak Ridge National Laboratory USEPA - United States Environmental Protection Agency
HH - Human Health PSRG - Preliminary Soil Remediation Goal WS - Water Supply
/Senate/PDF/S729v7.pdf HI - Hazard Index Q - Qualifier < - Concentration not detected at or above the reporting limit
CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration RSL - Regional Screening Level j - Indicates concentration reported below Practical Quantitation Limit
CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level RSV - Refinement Screening Value (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated
CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram SMCL - Secondary Maximum Contaminant Level
COPC - Constituent of Potential Concern NA - Not Available SSL - Soil Screening Level
Number of
Samples
Frequency of
Detection
Range of Detection
(µg/L)COPC?Analyte CAS
http://www.ncleg.net/Sessions/2013/Bills
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Prepared by: HEG Checked by: HES
Concentration
Used for
Screening
(µg/L)
15A NCAC 02L
.0202 Standard
(e)
(µg/L)
15A NCAC
02L .0202
IMAC (e)
(µg/L)
DHHS
Screening
Level (d)
(µg/L)
Federal MCL/
SMCL (c)
(µg/L)
Tap Water RSL
HI = 0.2 (a)
(µg/L)
Screening
Value Used
(µg/L)
Page 1 of 2
TABLE 1-1
HUMAN HEALTH SCREENING - GROUNDWATER
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
(a) - USEPA Regional Screening Levels (May 2018). Values for Residential Soil, Industrial Soil, and Tap Water. HI = 0.2. Accessed October 2018.
https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
(b) - USEPA National Recommended Water Quality Criteria. USEPA Office of Water and Office of Science and Technology. Accessed October 2018.
https://www.epa.gov/wqc/national-recommended-water-quality-criteria-human-health-criteria-table
USEPA AWQC Human Health for the Consumption of Organism Only apply to total concentrations.
(c) - USEPA 2018 Edition of the Drinking Water Standards and Health Advisories. March 2018. Accessed October 2018.
https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf
(d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental
Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_l_id=1169848&folderId=24814087&name=DLFE-112704.pdf
(e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=1aa3fa13-2c0f-45b7-ae96-5427fb1d25b4&groupId=38364
Amended April 2013.
(f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20b/subchapter%20b%20rules.pdf
WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption of fish and water.
Human Health Standards are based on the consumption of fish only unless dermal contact studies are available.
For Class C, use the most stringent of freshwater (or, if applicable, saltwater) column and the Human Health column.
For a WS water, use the most stringent of Freshwater, WS and Human Health. Likewise, Trout Waters and High Quality Waters must adhere to the most stingent of all applicable standards.
(g) - USEPA Region 4. 2018. Region 4 Ecological Risk Assessment Supplemental Guidance. March 2018 Update.
https://www.epa.gov/sites/production/files/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update.pdf
(h) - Value applies to inorganic form of arsenic only.
(i) - Value is the Secondary Maximum Contaminant Level.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals
(j) - Value for Total Chromium.
(k) - Copper Treatment Technology Action Level is 1.3 mg/L.
(l) - Lead Treatment Technology Action Level is 0.015 mg/L.
(m) - RSL for Antimony (metallic) used for Antimony.
(n) - Value for Chromium (III), Insoluble Salts used for Chromium.
(o) - RSL for Mercuric Chloride used for Mercury.
(p) - RSL for Nickel Soluble Salts used for Nickel.
(q) - RSL for Thallium (Soluble Salts) used for Thallium.
(r) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(s) - Value for Inorganic Mercury.
(t) - Acute AWQC is equal to 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and
CMC1 and CMC2 are 185.9 µ/gL and 12.82 µ/gL, respectively. Calculated assuming that all selenium is present as selenate, a likely overly conservative assumption.
(u) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(v) - Chloride Action Level for Toxic Substances Applicable to NPDES Permits is 230,000 µ/gL.
(w) - Applicable only to persons with a sodium restrictive diet.
(x) - Los Alamos National Laboratory ECORISK Database. http://www.lanl.gov/community-environment/environmental-stewardship/protection/eco-risk-assessment.php
(y) - Long, Edward R., and Lee G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in the National Status and Trends Program.
NOAA Technical Memorandum NOS OMA 52. Used effects range low (ER-L) for chronic and effects range medium (ER-M) for acute.
(z) - MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Sloane, G.; and T. Bernacki. 2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection, Tallahassee, FL. Used threshold effect concentration (TEC) for the ESV and probable effect concentration (PEC) for the RSV.
(aa) - Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the protection and management of aquatic sediment quality in Ontario. Ontario Ministry of the Environment. Queen's Printer of Ontario.
(bb) - Los Alamos National Laboratory ECORISK Database. September 2017. http://www.lanl.gov/environment/protection/eco-risk-assessment.php (µg/kg dw)
(cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/gliclearinghouse/
(dd) - Suter, G.W., and Tsao, C.L. 1996. Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-96/R2.
http://www.esd.ornl.gov/programs/ecorisk/documents/tm96r2.pdf
(ee) - USEPA. Interim Ecological Soil Screening Level Documents. Accessed October 2018. http://www2.epa.gov/chemical-research/interim-ecological-soil-screening-level-documents
(ff) - Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-126/R2. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm126r21.pdf)
(gg) - Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-85/R3. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm85r3.pdf)
(hh) - North Carolina Preliminary Soil Remediation Goals (PSRG) Table. HI = 0.2. September 2015. http://portal.ncdenr.org/c/document_library/get_file?uuid=0f601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361
as part of a risk assessment based on potential toxic effects, therefore; pH was not investigated further as a category 1 COPC. Water quality relative to pH will be addressed as a component of water quality monitoring programs for the site.
(jj) - Hazard Index = 0.1
(ii) - As part of the water quality evaluation conducted under the CSA, pH was measured and is reported as a metric data set. The pH comparison criteria are included as ranges as opposed to single screening values. pH is not typically included
Page 2 of 2
TABLE 1-2
HUMAN HEALTH SCREENING - SEDIMENT
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Min.Max.
Aluminum 7429-90-5 1 1 NA 3,850 3,850 15,000 15,400 100,000 220,000 15,000 100,000 N N
Antimony 7440-36-0 1 0 ND ND ND 6.2 (m)6.2 (m)94 (m)94 (m)6.2 94 N N
Arsenic 7440-38-2 1 0 ND ND ND 0.68 (h)0.68 (h, jj)3 (h)3 (h, jj)0.68 3 N N
Barium 7440-39-3 1 1 NA 65.7 65.7 3,000 3,000 44,000 44,000 3,000 44,000 N N
Beryllium 7440-41-7 1 0 ND ND ND 32 32 460 460 32 460 N N
Boron 7440-42-8 1 0 ND ND ND 3,200 3,200 46,000 46,000 3,200 46,000 N N
Cadmium 7440-43-9 1 0 ND ND ND 14 14.2 200 196 14 200 N N
Chromium (III)16065-83-1 1 1 NA 3.8 3.8 24,000 24,000 100,000 360,000 24,000 100,000 N N
Cobalt 7440-48-4 1 1 NA 5.4 5.4 4.6 4.6 70 70 4.6 70 Y N
Copper 7440-50-8 1 1 NA 6.2 6.2 620 620 9,400 9,400 620 9,400 N N
Lead 7439-92-1 1 0 ND ND ND 400 400 (jj)800 800 (jj)400 800 N N
Manganese 7439-96-5 1 1 NA 293 293 360 360 5,200 5,200 360 5,200 N N
Mercury 7439-97-6 1 1 NA 0.025 0.025 4.6 (o)4.6 (o)3.1 (o)70 (o)4.6 3.1 N N
Molybdenum 7439-98-7 1 0 ND ND ND 78 78 1,200 1,160 78 1,200 N N
Nickel 7440-02-0 1 0 ND ND ND 300 (p)300 (p)4,400 (p)4,400 (p)300 4,400 N N
Selenium 7782-49-2 1 0 ND ND ND 78 78 1,200 1,160 78 1,200 N N
Strontium 7440-24-6 1 1 NA 4.5 4.5 9,400 9,400 100,000 140,000 9,400 100,000 N N
Thallium 7440-28-0 1 0 ND ND ND 0.16 (q)0.156 (q)2.4 (q)2.4 (q)0.16 2.4 N N
Vanadium 7440-62-2 1 1 NA 19.5 19.5 78 78 1,160 1,160 78 1,160 N N
Zinc 7440-66-6 1 1 NA 12 12 4,600 4,600 70,000 70,000 4,600 70,000 N N
Notes:
AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources NC - North Carolina su - Standard units
CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services NCAC - North Carolina Administrative Code µg/L - micrograms/liter
North Carolina Session Law 2014-122, ESV - Ecological Screening Value ORNL - Oak Ridge National Laboratory USEPA - United States Environmental Protection Agency
HH - Human Health PSRG - Preliminary Soil Remediation Goal WS - Water Supply
/Senate/PDF/S729v7.pdf HI - Hazard Index Q - Qualifier < - Concentration not detected at or above the reporting limit
CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration RSL - Regional Screening Level j - Indicates concentration reported below Practical Quantitation Limit
CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level RSV - Refinement Screening Value (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated
CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram SMCL - Secondary Maximum Contaminant Level
COPC - Constituent of Potential Concern NA - Not Available SSL - Soil Screening Level
(a) - USEPA Regional Screening Levels (May 2018). Values for Residential Soil, Industrial Soil, and Tap Water. HI = 0.2. Accessed October 2018.
https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
(b) - USEPA National Recommended Water Quality Criteria. USEPA Office of Water and Office of Science and Technology. Accessed October 2018.
https://www.epa.gov/wqc/national-recommended-water-quality-criteria-human-health-criteria-table
USEPA AWQC Human Health for the Consumption of Organism Only apply to total concentrations.
(c) - USEPA 2018 Edition of the Drinking Water Standards and Health Advisories. March 2018. Accessed October 2018.
https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf
(d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental
Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_l_id=1169848&folderId=24814087&name=DLFE-112704.pdf
(e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=1aa3fa13-2c0f-45b7-ae96-5427fb1d25b4&groupId=38364
Amended April 2013.
(f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20b/subchapter%20b%20rules.pdf
WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption of fish and water.
Human Health Standards are based on the consumption of fish only unless dermal contact studies are available.
For Class C, use the most stringent of freshwater (or, if applicable, saltwater) column and the Human Health column.
For a WS water, use the most stringent of Freshwater, WS and Human Health. Likewise, Trout Waters and High Quality Waters must adhere to the most stingent of all applicable standards.
(g) - USEPA Region 4. 2018. Region 4 Ecological Risk Assessment Supplemental Guidance. March 2018 Update.
https://www.epa.gov/sites/production/files/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update.pdf
(h) - Value applies to inorganic form of arsenic only.
(i) - Value is the Secondary Maximum Contaminant Level.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals
(j) - Value for Total Chromium.
Analyte CAS
Number
of
Samples
Frequency
of
Detection
Concentration
Used for
Screening
(mg/kg)
Range of Detection
(mg/kg)
NC PSRG
Residential Health
Screening Level
(hh)
(mg/kg)
Residential Soil
RSL (a)
HI = 0.2
(mg/kg)
NC PSRG
Industrial
Health
Screening Level
(hh)
(mg/kg)
Industrial Soil
RSL (a)
HI = 0.2
(mg/kg)
Residential
Screening
Value Used
(mg/kg)
Industrial
Screening
Value Used
(mg/kg)
http://www.ncleg.net/Sessions/2013/Bills
Industrial
COPC?
Residential
COPC?
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Prepared by: HEG Checked by: ARD
Page 1 of 2
TABLE 1-2
HUMAN HEALTH SCREENING - SEDIMENT
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
(k) - Copper Treatment Technology Action Level is 1.3 mg/L.
(l) - Lead Treatment Technology Action Level is 0.015 mg/L.
(m) - RSL for Antimony (metallic) used for Antimony.
(n) - Value for Chromium (III), Insoluble Salts used for Chromium.
(o) - RSL for Mercuric Chloride used for Mercury.
(p) - RSL for Nickel Soluble Salts used for Nickel.
(q) - RSL for Thallium (Soluble Salts) used for Thallium.
(r) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(s) - Value for Inorganic Mercury.
(t) - Acute AWQC is equal to 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and
CMC1 and CMC2 are 185.9 µg/L and 12.82 µg/L, respectively. Calculated assuming that all selenium is present as selenate, a likely overly conservative assumption.
(u) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(v) - Chloride Action Level for Toxic Substances Applicable to NPDES Permits is 230,000 µg/L.
(w) - Applicable only to persons with a sodium restrictive diet.
(x) - Los Alamos National Laboratory ECORISK Database. http://www.lanl.gov/community-environment/environmental-stewardship/protection/eco-risk-assessment.php
(y) - Long, Edward R., and Lee G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in the National Status and Trends Program.
NOAA Technical Memorandum NOS OMA 52. Used effects range low (ER-L) for chronic and effects range medium (ER-M) for acute.
(z) - MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Sloane, G.; and T. Bernacki. 2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection, Tallahassee, FL. Used threshold effect concentration (TEC) for the ESV and probable effect concentration (PEC) for the RSV.
(aa) - Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the protection and management of aquatic sediment quality in Ontario. Ontario Ministry of the Environment. Queen's Printer of Ontario.
(bb) - Los Alamos National Laboratory ECORISK Database. September 2017. http://www.lanl.gov/environment/protection/eco-risk-assessment.php (µg/kg dw)
(cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/gliclearinghouse/
(dd) - Suter, G.W., and Tsao, C.L. 1996. Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-96/R2.
http://www.esd.ornl.gov/programs/ecorisk/documents/tm96r2.pdf
(ee) - USEPA. Interim Ecological Soil Screening Level Documents. Accessed October 2018. http://www2.epa.gov/chemical-research/interim-ecological-soil-screening-level-documents
(ff) - Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-126/R2. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm126r21.pdf)
(gg) - Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-85/R3. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm85r3.pdf)
(hh) - North Carolina Preliminary Soil Remediation Goals (PSRG) Table. HI = 0.2. September 2015. http://portal.ncdenr.org/c/document_library/get_file?uuid=0f601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361
as part of a risk assessment based on potential toxic effects, therefore; pH was not investigated further as a category 1 COPC. Water quality relative to pH will be addressed as a component of water quality monitoring programs for the site.
(jj) - Hazard Index = 0.1
(ii) - As part of the water quality evaluation conducted under the CSA, pH was measured and is reported as a metric data set. The pH comparison criteria are included as ranges as opposed to single screening values. pH is not typically included
Page 2 of 2
TABLE 1-3
HUMAN HEALTH SCREENING - SURFACE WATER
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Min.Max.
Aluminum 7429-90-5 28 28 61.6 816 816 NA NA NA NA NA NA 50 to 200 (i)4,000 50 Y
Antimony 7440-36-0 28 28 0.14 0.56 0.56 1 NA NA NA 5.6 640 6 1.56 (m)1 N
Arsenic 7440-38-2 29 28 0.28 2.3 2.3 10 NA 10 10 0.018 (h)0.14 (h)10 0.052 (h, jj)10 N
Barium 7440-39-3 29 29 10.4 26.6 26.6 700 NA 1,000 NA 1,000 NA 2,000 760 700 N
Beryllium 7440-41-7 28 14 0.011 0.044 0.044 NA 4 NA NA NA NA 4 5 4 N
Boron 7440-42-8 29 28 31.8 383 383 700 NA NA NA NA NA NA 800 700 N
Cadmium 7440-43-9 29 1 0.18 0.18 0.18 2 NA NA NA NA NA 5 1.84 2 N
Chromium (Total)7440-47-3 29 28 0.14 8.8 8.8 10 NA NA NA NA NA 100 4,400 (n)10 N
Chromium (VI)18540-29-9 26 24 0.023 1.1 1.1 NA NA NA NA NA NA NA 0.035 (jj)0.035 Y
Cobalt 7440-48-4 28 28 0.075 0.68 0.68 NA 1 NA NA NA NA NA 1.2 1 N
Copper 7440-50-8 29 29 0.86 2.8 2.8 1,000 NA NA NA 1,300 NA 1,300 (k)160 1,000 N
Lead 7439-92-1 28 28 0.07 1.9 1.9 15 NA NA NA NA NA 15 (l)15 (jj)15 N
Lithium 7439-93-2 7 6 0.1 0.43 0.43 NA NA NA NA NA NA NA 8 8 N
Manganese 7439-96-5 28 28 19.4 176 176 50 NA 200 NA 50 100 50 (i)86 50 Y
Mercury 7439-97-6 29 27 5.11E-04 0.0181 0.0181 1 NA NA NA NA NA 2 1.14 (o)1 N
Molybdenum 7439-98-7 28 28 0.18 3 3 NA NA NA NA NA NA NA 20 20 N
Nickel 7440-02-0 29 14 0.13 2 2 100 NA 25 NA 610 4,600 NA 78 (p)100 N
Selenium 7782-49-2 29 4 0.18 0.72 0.72 20 NA NA NA 170 4,200 50 20 20 N
Strontium 7440-24-6 28 28 26.5 129 129 NA NA NA NA NA NA NA 2,400 2,400 N
Thallium 7440-28-0 29 5 0.017 0.043 0.043 0.2 NA NA NA 0.24 0.47 2 0.04 (q)0.2 N
Vanadium 7440-62-2 28 28 0.71 4 4 NA NA NA NA NA NA NA 17.2 17 N
Zinc 7440-66-6 29 16 2.6 10.6 10.6 1 NA NA NA 7,400 26,000 5,000 (i)1,200 1 Y
Notes:
AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources NA - Not Available SMCL - Secondary Maximum Contaminant Level
CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services NC - North Carolina SSL - Soil Screening Level
North Carolina Session Law 2014-122, ESV - Ecological Screening Value NCAC - North Carolina Administrative Code su - Standard units
http://www.ncleg.net/Sessions/2013/Bills/Senate/PDF/S729v7.pdf HH - Human Health ORNL - Oak Ridge National Laboratory µg/L - micrograms/liter
CAS - Chemical Abstracts Service HI - Hazard Index PSRG - Preliminary Soil Remediation Goal USEPA - United States Environmental Protection Agency
CCC - Criterion Continuous Concentration IMAC - Interim Maximum Allowable Concentration Q - Qualifier WS - Water Supply
CMC - Criterion Maximum Concentration MCL - Maximum Contaminant Level RSL - Regional Screening Level < - Concentration not detected at or above the reporting limit
COPC - Constituent of Potential Concern mg/kg - milligrams/kilogram RSV - Refinement Screening Value
Screening
Value Used
(µg/L)
15A NCAC 02B
Water Supply
(WS) (f)
(µg/L)
COPC?Analyte CAS Number of
Samples
Frequency of
Detection
Prepared by: HEG Checked by: HES
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise
noted.
15A NCAC 02B
Human Health
(HH) (f)
(µg/L)
USEPA AWQC
Consumption
of Water and
Organism (b)
(µg/L)
USEPA AWQC
Consumption
of Organism
Only (b)
(µg/L)
Range of
Detection
(µg/L)
15A NCAC 02L
.0202 Standard
(e)
(µg/L)
15A NCAC 02L
.0202 IMAC (e)
(µg/L)
Federal MCL/
SMCL (c)
(µg/L)
Tap Water RSL
HI = 0.2 (a)
(µg/L)
Concentration
Used for
Screening (µg/L)
Page 1 of 2
TABLE 1-3
HUMAN HEALTH SCREENING - SURFACE WATER
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
(a) - USEPA Regional Screening Levels (May 2018). Values for Residential Soil, Industrial Soil, and Tap Water. HI = 0.2. Accessed October 2018.
https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
(b) - USEPA National Recommended Water Quality Criteria. USEPA Office of Water and Office of Science and Technology. Accessed October 2018.
https://www.epa.gov/wqc/national-recommended-water-quality-criteria-human-health-criteria-table
USEPA AWQC Human Health for the Consumption of Organism Only apply to total concentrations.
(c) - USEPA 2018 Edition of the Drinking Water Standards and Health Advisories. March 2018. Accessed October 2018.
https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf
(d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental
Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_l_id=1169848&folderId=24814087&name=DLFE-112704.pdf
(e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=1aa3fa13-2c0f-45b7-ae96-5427fb1d25b4&groupId=38364
Amended April 2013.
(f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20b/subchapter%20b%20rules.pdf
WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption of fish and water.
Human Health Standards are based on the consumption of fish only unless dermal contact studies are available.
For Class C, use the most stringent of freshwater (or, if applicable, saltwater) column and the Human Health column.
For a WS water, use the most stringent of Freshwater, WS and Human Health. Likewise, Trout Waters and High Quality Waters must adhere to the most stingent of all applicable standards.
(g) - USEPA Region 4. 2018. Region 4 Ecological Risk Assessment Supplemental Guidance. March 2018 Update.
https://www.epa.gov/sites/production/files/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update.pdf
(h) - Value applies to inorganic form of arsenic only.
(i) - Value is the Secondary Maximum Contaminant Level.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals
(j) - Value for Total Chromium.
(k) - Copper Treatment Technology Action Level is 1.3 mg/L.
(l) - Lead Treatment Technology Action Level is 0.015 mg/L.
(m) - RSL for Antimony (metallic) used for Antimony.
(n) - Value for Chromium (III), Insoluble Salts used for Chromium.
(o) - RSL for Mercuric Chloride used for Mercury.
(p) - RSL for Nickel Soluble Salts used for Nickel.
(q) - RSL for Thallium (Soluble Salts) used for Thallium.
(r) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(s) - Value for Inorganic Mercury.
(t) - Acute AWQC is equal to 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and
CMC1 and CMC2 are 185.9 µg/L and 12.82 µg/L, respectively. Calculated assuming that all selenium is present as selenate, a likely overly conservative assumption.
(u) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(v) - Chloride Action Level for Toxic Substances Applicable to NPDES Permits is 230,000 µg/L.
(w) - Applicable only to persons with a sodium restrictive diet.
(x) - Los Alamos National Laboratory ECORISK Database. http://www.lanl.gov/community-environment/environmental-stewardship/protection/eco-risk-assessment.php
(y) - Long, Edward R., and Lee G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in the National Status and Trends Program.
NOAA Technical Memorandum NOS OMA 52. Used effects range low (ER-L) for chronic and effects range medium (ER-M) for acute.
(z) - MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Sloane, G.; and T. Bernacki. 2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection, Tallahassee, FL. Used threshold effect concentration (TEC) for the ESV and probable effect concentration (PEC) for the RSV.
(aa) - Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the protection and management of aquatic sediment quality in Ontario. Ontario Ministry of the Environment. Queen's Printer of Ontario.
(bb) - Los Alamos National Laboratory ECORISK Database. September 2017. http://www.lanl.gov/environment/protection/eco-risk-assessment.php (µg/kg dw)
(cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/gliclearinghouse/
(dd) - Suter, G.W., and Tsao, C.L. 1996. Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-96/R2.
http://www.esd.ornl.gov/programs/ecorisk/documents/tm96r2.pdf
(ee) - USEPA. Interim Ecological Soil Screening Level Documents. Accessed October 2018. http://www2.epa.gov/chemical-research/interim-ecological-soil-screening-level-documents
(ff) - Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-126/R2. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm126r21.pdf)
(gg) - Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-85/R3. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm85r3.pdf)
(hh) - North Carolina Preliminary Soil Remediation Goals (PSRG) Table. HI = 0.2. September 2015. http://portal.ncdenr.org/c/document_library/get_file?uuid=0f601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361
as part of a risk assessment based on potential toxic effects, therefore; pH was not investigated further as a category 1 COPC. Water quality relative to pH will be addressed as a component of water quality monitoring programs for the site.
(jj) - Hazard Index = 0.1
(ii) - As part of the water quality evaluation conducted under the CSA, pH was measured and is reported as a metric data set. The pH comparison criteria are included as ranges as opposed to single screening values. pH is not typically included
Page 2 of 2
TABLE 2-1
ECOLOGICAL SCREENING - SEDIMENT - LAKE WYLIE - EXPOSURE AREA 1
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Min.Max.ESV RSV
Aluminum 7429-90-5 1 1 NA 3,850 3,850 25,000 (x)58,000 (x)25,000 N
Antimony 7440-36-0 1 0 ND ND ND 2 (y)25 (y)2 N
Arsenic 7440-38-2 1 0 ND ND ND 9.8 (z)33 (z)10 N
Barium 7440-39-3 1 1 NA 65.7 65.7 20 (z)60 (z)20 Y
Beryllium 7440-41-7 1 0 ND ND ND NA NA NA N
Boron 7440-42-8 1 0 ND ND ND NA NA NA N
Cadmium 7440-43-9 1 0 ND ND ND 1 (z)5 (z)1 N
Chromium (Total)7440-47-3 1 1 NA 3.8 3.8 43.4 (z)111 (z)43 N
Cobalt 7440-48-4 1 1 NA 5.4 5.4 50 (aa)NA (aa)50 N
Copper 7440-50-8 1 1 NA 6.2 6.2 31.6 (z)149 (z)31.6 N
Lead 7439-92-1 1 0 ND ND ND 35.8 (z)128 (z)35.8 N
Manganese 7439-96-5 1 1 NA 293 293 460 (bb)1,100 (bb)460 N
Mercury 7439-97-6 1 1 NA 0.025 0.025 0.18 (z)1.1 (z)0.18 N
Molybdenum 7439-98-7 1 0 ND ND ND NA NA NA N
Nickel 7440-02-0 1 0 ND ND ND 22.7 (z)48.6 (z)22.7 N
Selenium 7782-49-2 1 0 ND ND ND 0.8 (bb)1.2 (bb)0.8 N
Strontium 7440-24-6 1 1 NA 4.5 4.5 NA NA NA N
Thallium 7440-28-0 1 0 ND ND ND NA NA NA N
Vanadium 7440-62-2 1 1 NA 19.5 19.5 NA NA NA N
Zinc 7440-66-6 1 1 NA 12 12 121 (z)459 (z)121 N
Notes:
AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources su - Standard units
CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services µg/L - micrograms/liter
North Carolina Session Law 2014-122, ESV - Ecological Screening Value USEPA - United States Environmental Protection Agency
HH - Human Health WS - Water Supply
/Senate/PDF/S729v7.pdf HI - Hazard Index < - Concentration not detected at or above the reporting limit
CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration j - Indicates concentration reported below Practical Quantitation Limit
CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated
CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram
COPC - Constituent of Potential Concern NA - Not Available
http://www.ncleg.net/Sessions/2013/Bills
Concentration
Used for
Screening
(mg/kg)
USEPA Region 4 Sediment
Screening Values (g)
(mg/kg)
Screening
Value
Used
(mg/kg)
COPC?Analyte CAS Number of
Samples
Frequency
of
Detection
Range of
Detection
(mg/kg)
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Prepared by: HEG Checked by: TCP
TABLE 2-1
ECOLOGICAL SCREENING - SEDIMENT - LAKE WYLIE - EXPOSURE AREA 1
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
(a) - USEPA Regional Screening Levels (May 2018). Values for Residential Soil, Industrial Soil, and Tap Water. HI = 0.2. Accessed October 2018.
https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
(b) - USEPA National Recommended Water Quality Criteria. USEPA Office of Water and Office of Science and Technology. Accessed October 2018.
https://www.epa.gov/wqc/national-recommended-water-quality-criteria-aquatic-life-criteria-table
USEPA AWQC Human Health for the Consumption of Organism Only apply to total concentrations.
(c) - USEPA 2018 Edition of the Drinking Water Standards and Health Advisories. March 2018. Accessed October 2018.
https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf
(d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental
Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_l_id=1169848&folderId=24814087&name=DLFE-112704.pdf
(e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=1aa3fa13-2c0f-45b7-ae96-5427fb1d25b4&groupId=38364
Amended April 2013.
(f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20b/subchapter%20b%20rules.pdf
WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption of fish and water.
Human Health Standards are based on the consumption of fish only unless dermal contact studies are available.
For Class C, use the most stringent of freshwater (or, if applicable, saltwater) column and the Human Health column.
For a WS water, use the most stringent of Freshwater, WS and Human Health. Likewise, Trout Waters and High Quality Waters must adhere to the most stingent of all applicable standards.
(g) - USEPA Region 4. 2018. Region 4 Ecological Risk Assessment Supplemental Guidance. March 2018 Update.
https://www.epa.gov/sites/production/files/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update.pdf
(h) - Value applies to inorganic form of arsenic only.
(i) - Value is the Secondary Maximum Contaminant Level.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals
(j) - Value for Total Chromium.
(k) - Copper Treatment Technology Action Level is 1.3 mg/L.
(l) - Lead Treatment Technology Action Level is 0.015 mg/L.
(m) - RSL for Antimony (metallic) used for Antimony.
(n) - Value for Chromium (III), Insoluble Salts used for Chromium.
(o) - RSL for Mercuric Chloride used for Mercury.
(p) - RSL for Nickel Soluble Salts used for Nickel.
(q) - RSL for Thallium (Soluble Salts) used for Thallium.
(r) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(s) - Value for Inorganic Mercury.
(t) - Acute AWQC is equal to 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and
CMC1 and CMC2 are 185.9 µg/L and 12.82 µg/L, respectively. Calculated assuming that all selenium is present as selenate, a likely overly conservative assumption.
(u) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(v) - Chloride Action Level for Toxic Substances Applicable to NPDES Permits is 230,000 µg/L.
(w) - Applicable only to persons with a sodium restrictive diet.
(x) - Los Alamos National Laboratory ECORISK Database. http://www.lanl.gov/community-environment/environmental-stewardship/protection/eco-risk-assessment.php
(y) - Long, Edward R., and Lee G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in the National Status and Trends Program.
NOAA Technical Memorandum NOS OMA 52. Used effects range low (ER-L) for chronic and effects range medium (ER-M) for acute.
(z) - MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Sloane, G.; and T. Bernacki. 2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection, Tallahassee, FL. Used threshold effect concentration (TEC) for the ESV and probable effect concentration (PEC) for the RSV.
(aa) - Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the protection and management of aquatic sediment quality in Ontario. Ontario Ministry of the Environment. Queen's Printer of Ontario.
(bb) - Los Alamos National Laboratory ECORISK Database. September 2017. http://www.lanl.gov/environment/protection/eco-risk-assessment.php (µg/kg dw)
(cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/gliclearinghouse/
(dd) - Suter, G.W., and Tsao, C.L. 1996. Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-96/R2.
http://www.esd.ornl.gov/programs/ecorisk/documents/tm96r2.pdf
(ee) - USEPA. Interim Ecological Soil Screening Level Documents. Accessed October 2018. http://www2.epa.gov/chemical-research/interim-ecological-soil-screening-level-documents
(ff) - Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-126/R2. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm126r21.pdf)
(gg) - Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-85/R3. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm85r3.pdf)
(hh) - North Carolina Preliminary Soil Remediation Goals (PSRG) Table. HI = 0.2. September 2015. http://portal.ncdenr.org/c/document_library/get_file?uuid=0f601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361
TABLE 2-2
ECOLOGICAL SCREENING - SURFACE WATER - CATAWBA RIVER - EXPOSURE AREA 1
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Min.Max.Total Dissolved Total Dissolved Total Dissolved Total Dissolved Total Dissolved Total
Aluminum 7429-90-5 28 28 61.6 816 816 NA NA NA NA 750 (b)NA 87 (b)NA 750 NA 87 NA 87 Y
Antimony 7440-36-0 28 28 0.14 0.56 0.56 NA NA NA NA 900 (cc)NA 190 (cc)NA NA NA NA NA 190 N
Arsenic 7440-38-2 29 28 0.28 2.3 2.3 NA 340 NA 150 340 (b, h)NA 150 (b, h)NA 340 (h)NA 150 (h)NA 150 N
Barium 7440-39-3 29 29 10.4 26.6 26.6 NA NA NA NA 2000 (cc)NA 220 (cc)NA NA NA NA NA 220 N
Beryllium 7440-41-7 28 14 0.011 0.044 0.044 NA 65 NA 6.5 31 (r, cc)NA 3.6 (r, cc)NA NA NA NA NA 4 N
Boron 7440-42-8 29 28 31.8 383 383 NA NA NA NA 34,000 (cc)NA 7,200 (cc)NA NA NA NA NA 7200 N
Cadmium 7440-43-9 29 1 0.18 0.18 0.18 NA NA NA NA 1.1 (r)NA 0.16 (r)NA NA 1.8 (r)0.27 (r)NA 0.16 Y
Chromium (Total)7440-47-3 29 28 0.14 8.8 8.8 NA NA 50 NA 1,022 (n, r)NA 48.8 (n, r)NA NA NA NA NA 50 N
Chromium (VI)18540-29-9 26 24 0.023 1.1 1.1 NA 16 NA 11 16 NA 11 NA NA 16 NA 11 11 N
Cobalt 7440-48-4 28 28 0.075 0.68 0.68 NA NA NA NA 120 (cc)NA 19 (cc)NA NA NA NA NA 19 N
Copper 7440-50-8 29 29 0.86 2.8 3 NA NA NA NA 7.3 (r)NA 5.16 (r)NA NA NA NA NA 5.16 N
Lead 7439-92-1 28 28 0.07 1.9 1.9 NA NA NA NA 33.8 (r)NA 1.32 (r)NA NA 65.0 (r)NA 2.5 (r)1 Y
Lithium 7439-93-2 7 6 0.1 0.43 0.43 NA NA NA NA 910 (cc)NA 440 (cc)NA NA NA NA NA 440 N
Manganese 7439-96-5 28 28 19.4 176 176 NA NA NA NA 1,680 (cc)NA 93 (cc)NA NA NA NA NA 93 Y
Mercury 7439-97-6 27 25 0.00051 0.0181 0.0181 NA NA 0.012 NA 1.4 (b, s)NA 0.77 (b, s)NA NA 1.4 (s)NA 0.77 (s)0.012 Y
Molybdenum 7439-98-7 28 28 0.18 3 3 NA NA NA NA 7,200 (cc)NA 800 (cc)NA NA NA NA NA 800 N
Nickel 7440-02-0 29 14 0.13 2 2 NA NA NA NA 261 (r)NA 29 (r)NA NA 470 (r)NA 52 (r)29 N
Selenium 7782-49-2 29 4 0.18 0.72 0.72 NA NA 5 NA 20 (cc)NA 5 (cc)NA NA NA NA NA 5 N
Strontium 7440-24-6 28 28 26.5 129 129 NA NA NA NA 48,000 (cc)NA 5,300 (cc)NA NA NA NA NA 5300 N
Thallium 7440-28-0 29 5 0.017 0.043 0.043 NA NA NA NA 54 (cc)NA 6 (cc)NA NA NA NA NA 6 N
Vanadium 7440-62-2 28 28 0.71 4 4 NA NA NA NA 79 (cc)NA 27 (cc)NA NA NA NA NA 27 N
Zinc 7440-66-6 29 16 2.6 10.6 10.6 NA NA NA NA 67 (r)NA 67 (r)NA 120 (r)NA 120 (r)NA 67 N
Notes:
AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources su - Standard units
CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services µg/L - micrograms/liter
North Carolina Session Law 2014-122, ESV - Ecological Screening Value USEPA - United States Environmental Protection Agency
HH - Human Health WS - Water Supply
/Senate/PDF/S729v7.pdf HI - Hazard Index < - Concentration not detected at or above the reporting limit
CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration j - Indicates concentration reported below Practical Quantitation Limit
CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated
CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram
COPC - Constituent of Potential Concern NA - Not Available
http://www.ncleg.net/Sessions/2013/Bills
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
USEPA Region 4
Freshwater Acute Screening
Values (g)
(µg/L)
USEPA Region 4
Freshwater Chronic
Screening Values (g)
(µg/L)
USEPA
AWQC (b)
CMC (acute)
(µg/L)
USEPA
AWQC (b)
CCC (chronic)
(µg/L)
Dissolved
Screening
Value Used
(µg/L)
COPC?Analyte CAS
Number
of
Samples
Frequency
of
Detection
Range of
Detection
(µg/L)
Prepared by: HEG Checked by: ARD
Concentration
Used for
Screening
(µg/L)
15A NCAC 2B
Freshwater Aquatic
Life Acute (f)
(µg/L)
15A NCAC 2B
Freshwater Aquatic Life
Chronic (f)
(µg/L)
Page 1 of 2
TABLE 2-2
ECOLOGICAL SCREENING - SURFACE WATER - CATAWBA RIVER - EXPOSURE AREA 1
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
(a) - USEPA Regional Screening Levels (May 2018). Values for Residential Soil, Industrial Soil, and Tap Water. HI = 0.2. Accessed October 2018.
https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
(b) - USEPA National Recommended Water Quality Criteria. USEPA Office of Water and Office of Science and Technology. Accessed October 2018.
https://www.epa.gov/wqc/national-recommended-water-quality-criteria-aquatic-life-criteria-table
USEPA AWQC Human Health for the Consumption of Organism Only apply to total concentrations.
(c) - USEPA 2018 Edition of the Drinking Water Standards and Health Advisories. March 2018. Accessed October 2018.
https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf
(d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental
Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_l_id=1169848&folderId=24814087&name=DLFE-112704.pdf
(e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=1aa3fa13-2c0f-45b7-ae96-5427fb1d25b4&groupId=38364
Amended April 2013.
(f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20b/subchapter%20b%20rules.pdf
WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption of fish and water.
Human Health Standards are based on the consumption of fish only unless dermal contact studies are available.
For Class C, use the most stringent of freshwater (or, if applicable, saltwater) column and the Human Health column.
For a WS water, use the most stringent of Freshwater, WS and Human Health. Likewise, Trout Waters and High Quality Waters must adhere to the most stingent of all applicable standards.
(g) - USEPA Region 4. 2018. Region 4 Ecological Risk Assessment Supplemental Guidance. March 2018 Update.
https://www.epa.gov/sites/production/files/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update.pdf
(h) - Value applies to inorganic form of arsenic only.
(i) - Value is the Secondary Maximum Contaminant Level.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals
(j) - Value for Total Chromium.
(k) - Copper Treatment Technology Action Level is 1.3 mg/L.
(l) - Lead Treatment Technology Action Level is 0.015 mg/L.
(m) - RSL for Antimony (metallic) used for Antimony.
(n) - Value for Chromium (III), Insoluble Salts used for Chromium.
(o) - RSL for Mercuric Chloride used for Mercury.
(p) - RSL for Nickel Soluble Salts used for Nickel.
(q) - RSL for Thallium (Soluble Salts) used for Thallium.
(r) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(s) - Value for Inorganic Mercury.
(t) - Acute AWQC is equal to 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and
CMC1 and CMC2 are 185.9 µg/L and 12.82 µg/L, respectively. Calculated assuming that all selenium is present as selenate, a likely overly conservative assumption.
(u) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(v) - Chloride Action Level for Toxic Substances Applicable to NPDES Permits is 230,000 µg/L.
(w) - Applicable only to persons with a sodium restrictive diet.
(x) - Los Alamos National Laboratory ECORISK Database. http://www.lanl.gov/community-environment/environmental-stewardship/protection/eco-risk-assessment.php
(y) - Long, Edward R., and Lee G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in the National Status and Trends Program.
NOAA Technical Memorandum NOS OMA 52. Used effects range low (ER-L) for chronic and effects range medium (ER-M) for acute.
(z) - MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Sloane, G.; and T. Bernacki. 2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection, Tallahassee, FL. Used threshold effect concentration (TEC) for the ESV and probable effect concentration (PEC) for the RSV.
(aa) - Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the protection and management of aquatic sediment quality in Ontario. Ontario Ministry of the Environment. Queen's Printer of Ontario.
(bb) - Los Alamos National Laboratory ECORISK Database. September 2017. http://www.lanl.gov/environment/protection/eco-risk-assessment.php (µg/kg dw)
(cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/gliclearinghouse/
(dd) - Suter, G.W., and Tsao, C.L. 1996. Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-96/R2.
http://www.esd.ornl.gov/programs/ecorisk/documents/tm96r2.pdf
(ee) - USEPA. Interim Ecological Soil Screening Level Documents. Accessed October 2018. http://www2.epa.gov/chemical-research/interim-ecological-soil-screening-level-documents
(ff) - Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-126/R2. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm126r21.pdf)
(gg) - Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-85/R3. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm85r3.pdf)
(hh) - North Carolina Preliminary Soil Remediation Goals (PSRG) Table. HI = 0.2. September 2015. http://portal.ncdenr.org/c/document_library/get_file?uuid=0f601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361
Page 2 of 2
TABLE 2-3
ECOLOGICAL SCREENING - SURFACE WATER - EXPOSURE AREA 4
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Min.Max.Total Dissolved Total Dissolved Total Dissolved Total Dissolved Total Dissolved Total
Aluminum 7429-90-5 6 6 170 47,300 47,300 NA NA NA NA 750 (b)NA 87 (b)NA 750 NA 87 NA 87 Y
Antimony 7440-36-0 6 0 NA ND ND NA NA NA NA 900 (cc)NA 190 (cc)NA NA NA NA NA 190 N
Arsenic 7440-38-2 6 5 0.5 12.4 12.4 NA 340 NA 150 340 (b, h)NA 150 (b, h)NA 340 (h)NA 150 (h)NA 150 N
Barium 7440-39-3 6 6 46 159 159 NA NA NA NA 2000 (cc)NA 220 (cc)NA NA NA NA NA 220 N
Beryllium 7440-41-7 6 5 0.058 34.8 34.8 NA 65 NA 6.5 31 (r, cc)NA 3.6 (r, cc)NA NA NA NA NA 4 Y
Boron 7440-42-8 6 6 190 10,900 10,900 NA NA NA NA 34,000 (cc)NA 7,200 (cc)NA NA NA NA NA 7,200 Y
Cadmium 7440-43-9 6 4 0.035 0.19 0.19 NA NA NA NA 1.1 (r)NA 0.16 (r)NA NA 1.8 (r)0.27 (r)NA 0.16 Y
Chromium (Total)7440-47-3 6 6 0.23 5.7 5.7 NA NA 50 NA 1,022 (n, r)NA 48.8 (n, r)NA NA NA NA NA 50 N
Chromium (VI)18540-29-9 6 0 NA ND ND NA 16 NA 11 16 NA 11 NA NA 16 NA 11 11 N
Cobalt 7440-48-4 6 6 4.3 268 268 NA NA NA NA 120 (cc)NA 19 (cc)NA NA NA NA NA 19 Y
Copper 7440-50-8 6 5 2.1 17.6 18 NA NA NA NA 7.3 (r)NA 5.16 (r)NA NA NA NA NA 5.16 Y
Lead 7439-92-1 6 4 0.12 17.7 17.7 NA NA NA NA 33.8 (r)NA 1.32 (r)NA NA 65.0 (r)NA 2.5 (r)1 Y
Lithium 7439-93-2 2 2 0.39 0.51 0.51 NA NA NA NA 910 (cc)NA 440 (cc)NA NA NA NA NA 440 N
Manganese 7439-96-5 6 6 190 22,100 22,100 NA NA NA NA 1,680 (cc)NA 93 (cc)NA NA NA NA NA 93 Y
Mercury 7439-97-6 6 6 0.00280 0.0087 0.0087 NA NA 0.012 NA 1.4 (b, s)NA 0.77 (b, s)NA NA 1.4 (s)NA 0.77 (s)0.012 N
Molybdenum 7439-98-7 6 3 0.091 0.19 0.19 NA NA NA NA 7,200 (cc)NA 800 (cc)NA NA NA NA NA 800 N
Nickel 7440-02-0 6 6 7.2 450 450 NA NA NA NA 261 (r)NA 29 (r)NA NA 470 (r)NA 52 (r)29 Y
Selenium 7782-49-2 6 5 0.77 87.1 87.1 NA NA 5 NA 20 (cc)NA 5 (cc)NA NA NA NA NA 5 Y
Strontium 7440-24-6 6 6 250 3,200 3200 NA NA NA NA 48,000 (cc)NA 5,300 (cc)NA NA NA NA NA 5,300 N
Thallium 7440-28-0 6 5 0.08 0.74 0.74 NA NA NA NA 54 (cc)NA 6 (cc)NA NA NA NA NA 6 N
Vanadium 7440-62-2 6 4 1.3 8.6 8.6 NA NA NA NA 79 (cc)NA 27 (cc)NA NA NA NA NA 27 N
Zinc 7440-66-6 6 6 8.2 75.6 75.6 NA NA NA NA 67 (r)NA 67 (r)NA 120 (r)NA 120 (r)NA 67 Y
Notes:
AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources su - Standard units
CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services µg/L - micrograms/liter
North Carolina Session Law 2014-122, ESV - Ecological Screening Value USEPA - United States Environmental Protection Agency
HH - Human Health WS - Water Supply
/Senate/PDF/S729v7.pdf HI - Hazard Index < - Concentration not detected at or above the reporting limit
CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration j - Indicates concentration reported below Practical Quantitation Limit
CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated
CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram
USEPA Region 4
Freshwater Acute Screening
Values (g)
(µg/L)
USEPA Region 4
Freshwater Chronic
Screening Values (g)
(µg/L)
USEPA
AWQC (b)
CMC (acute)
(µg/L)
USEPA
AWQC (b)
CCC (chronic)
(µg/L)
Dissolved
Screening
Value Used
(µg/L)
COPC?
Prepared by: TCP Checked by: HEG
Concentration
Used for
Screening
(µg/L)
15A NCAC 2B
Freshwater Aquatic
Life Acute (f)
(µg/L)
15A NCAC 2B
Freshwater Aquatic Life
Chronic (f)
(µg/L)
Range of
Detection
(µg/L)Analyte CAS
Number
of
Samples
Frequency
of
Detection
http://www.ncleg.net/Sessions/2013/Bills
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
Page 1 of 2
TABLE 2-3
ECOLOGICAL SCREENING - SURFACE WATER - EXPOSURE AREA 4
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
COPC - Constituent of Potential Concern NA - Not Available
(a) - USEPA Regional Screening Levels (May 2018). Values for Residential Soil, Industrial Soil, and Tap Water. HI = 0.2. Accessed October 2018.
https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables
(b) - USEPA National Recommended Water Quality Criteria. USEPA Office of Water and Office of Science and Technology. Accessed October 2018.
https://www.epa.gov/wqc/national-recommended-water-quality-criteria-aquatic-life-criteria-table
USEPA AWQC Human Health for the Consumption of Organism Only apply to total concentrations.
(c) - USEPA 2018 Edition of the Drinking Water Standards and Health Advisories. March 2018. Accessed October 2018.
https://www.epa.gov/sites/production/files/2018-03/documents/dwtable2018.pdf
(d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental
Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_l_id=1169848&folderId=24814087&name=DLFE-112704.pdf
(e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=1aa3fa13-2c0f-45b7-ae96-5427fb1d25b4&groupId=38364
Amended April 2013.
(f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015.
http://reports.oah.state.nc.us/ncac/title%2015a%20-%20environmental%20quality/chapter%2002%20-%20environmental%20management/subchapter%20b/subchapter%20b%20rules.pdf
WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption of fish and water.
Human Health Standards are based on the consumption of fish only unless dermal contact studies are available.
For Class C, use the most stringent of freshwater (or, if applicable, saltwater) column and the Human Health column.
For a WS water, use the most stringent of Freshwater, WS and Human Health. Likewise, Trout Waters and High Quality Waters must adhere to the most stingent of all applicable standards.
(g) - USEPA Region 4. 2018. Region 4 Ecological Risk Assessment Supplemental Guidance. March 2018 Update.
https://www.epa.gov/sites/production/files/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update.pdf
(h) - Value applies to inorganic form of arsenic only.
(i) - Value is the Secondary Maximum Contaminant Level.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standards-guidance-nuisance-chemicals
(j) - Value for Total Chromium.
(k) - Copper Treatment Technology Action Level is 1.3 mg/L.
(l) - Lead Treatment Technology Action Level is 0.015 mg/L.
(m) - RSL for Antimony (metallic) used for Antimony.
(n) - Value for Chromium (III), Insoluble Salts used for Chromium.
(o) - RSL for Mercuric Chloride used for Mercury.
(p) - RSL for Nickel Soluble Salts used for Nickel.
(q) - RSL for Thallium (Soluble Salts) used for Thallium.
(r) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(s) - Value for Inorganic Mercury.
(t) - Acute AWQC is equal to 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and
CMC1 and CMC2 are 185.9 µg/L and 12.82 µg/L, respectively. Calculated assuming that all selenium is present as selenate, a likely overly conservative assumption.
(u) - Criterion expressed as a function of total hardness (mg/L). Value displayed is the site-specific total hardness of mg/L.
(v) - Chloride Action Level for Toxic Substances Applicable to NPDES Permits is 230,000 µg/L.
(w) - Applicable only to persons with a sodium restrictive diet.
(x) - Los Alamos National Laboratory ECORISK Database. http://www.lanl.gov/community-environment/environmental-stewardship/protection/eco-risk-assessment.php
(y) - Long, Edward R., and Lee G. Morgan. 1991. The Potential for Biological Effects of Sediment-Sorbed Contaminants Tested in the National Status and Trends Program.
NOAA Technical Memorandum NOS OMA 52. Used effects range low (ER-L) for chronic and effects range medium (ER-M) for acute.
(z) - MacDonald, D.D.; Ingersoll, C.G.; Smorong, D.E.; Lindskoog, R.A.; Sloane, G.; and T. Bernacki. 2003. Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for
Florida Inland Waters. Florida Department of Environmental Protection, Tallahassee, FL. Used threshold effect concentration (TEC) for the ESV and probable effect concentration (PEC) for the RSV.
(aa) - Persaud, D., R. Jaagumagi and A. Hayton. 1993. Guidelines for the protection and management of aquatic sediment quality in Ontario. Ontario Ministry of the Environment. Queen's Printer of Ontario.
(bb) - Los Alamos National Laboratory ECORISK Database. September 2017. http://www.lanl.gov/environment/protection/eco-risk-assessment.php (µg/kg dw)
(cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/gliclearinghouse/
(dd) - Suter, G.W., and Tsao, C.L. 1996. Toxicological Benchmarks for Screening Potential Contaminants of Concern for Effects on Aquatic Biota: 1996 Revision. ES/ER/TM-96/R2.
http://www.esd.ornl.gov/programs/ecorisk/documents/tm96r2.pdf
(ee) - USEPA. Interim Ecological Soil Screening Level Documents. Accessed October 2018. http://www2.epa.gov/chemical-research/interim-ecological-soil-screening-level-documents
(ff) - Efroymson, R.A., M.E. Will, and G.W. Suter II, 1997a. Toxicological Benchmarks for Contaminants of Potential Concern for Effects on Soil and Litter Invertebrates and Heterotrophic Process:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-126/R2. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm126r21.pdf)
(gg) - Efroymson, R.A., M.E. Will, G.W. Suter II, and A.C. Wooten, 1997b. Toxicological Benchmarks for Screening Contaminants of Potential Concern for Effects on Terrestrial Plants:
1997 Revision. Oak Ridge National Laboratory, Oak Ridge, TN. ES/ER/TM-85/R3. (Available at http://www.esd.ornl.gov/programs/ecorisk/documents/tm85r3.pdf)
(hh) - North Carolina Preliminary Soil Remediation Goals (PSRG) Table. HI = 0.2. September 2015. http://portal.ncdenr.org/c/document_library/get_file?uuid=0f601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361
Page 2 of 2
TABLE 3-1
SUMMARY OF EXPOSURE POINT CONCENTRATIONS
HUMAN HEALTH - GROUNDWATER
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Constituent Reporting
Units
Number of
Samples
Frequency of
Detection
Minimum
Detected
Concentration
Maximum
Detected
Concentration
Mean of
Detected
Concentration
UCL Selected UCL Exposure Point
Concentration
Exposure Point
Concentration
(mg/L)
Aluminum µg/L 742 555 7 101,000 2,459 95% KM (Chebyshev) UCL 3,569 3569 3.569
Antimony µg/L 1,265 382 0.1 27 0.905 95% KM (Chebyshev) UCL 0.578 0.578 0.000578
Arsenic µg/L 1,370 982 0.045 697 4 95% KM (Chebyshev) UCL 6 6 0.006
Barium µg/L 1,370 1,345 2.5 1,640 65.49 95% KM (Chebyshev) UCL 77.61 77.61 0.07761
Beryllium µg/L 1,148 499 0.01 53 2.02 95% KM (Chebyshev) UCL 1.61 1.61 0.00161
Boron µg/L 1,352 639 25.2 6,200 680.5 95% KM (Chebyshev) UCL 410 410 0.41
Cadmium µg/L 1,370 215 0.025 13.1 1.216 95% KM (Chebyshev) UCL 0.379 0.379 0.000379
Chromium (Total)µg/L 1,370 1,139 0.1 393 4.794 95% KM (Chebyshev) UCL 5.921 5.921 0.005921
Chromium (VI)µg/L 573 483 0.0094 31.1 2.138 95% KM (Chebyshev) UCL 2.44 2.44 0.00244
Cobalt µg/L 1,148 1,050 0.011 5,350 93.54 95% KM (Chebyshev) UCL 156.6 156.6 0.1566
Lithium µg/L 528 510 0.088 820 19.36 95% KM (Chebyshev) UCL 33.73 33.73 0.03373
Manganese µg/L 964 843 2.5 240,000 3,600 95% KM (Chebyshev) UCL 6,056 6056 6.056
Molybdenum µg/L 1,148 709 0.09 264 3.121 95% KM (Chebyshev) UCL 3.185 3.185 0.003185
Nickel µg/L 937 626 0.14 1,130 31.52 95% KM (Chebyshev) UCL 38.93 38.93 0.03893
Selenium µg/L 1,370 424 0.17 1,200 26.75 95% KM (Chebyshev) UCL 16.81 16.81 0.01681
Strontium µg/L 733 732 3.6 3,200 263.5 95% KM (Chebyshev) UCL 318.1 318.1 0.3181
Thallium µg/L 1,265 357 0.016 3.1 0.22 95% KM (Chebyshev) UCL 0.132 0.132 0.000132
Vanadium µg/L 742 687 0.059 93.2 4.963 95% KM (Chebyshev) UCL 5.572 5.572 0.005572
Zinc µg/L 964 522 2.5 2,390 73.85 95% KM (Chebyshev) UCL 77.95 77.95 0.07795
Prepared by: HEG Checked by: HES
Notes:
---: Calculations were not performed due to lack of samples ND - Not Determined
Mean - Arithmetic mean UCL - 95% Upper Confidence Limit
mg/L - milligrams per liter
µg/L - micrograms per liter
(c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples.
(a)- Mean calculated by ProUCL using the Kaplan-Meier (KM) estimation method for non-detect values: only given for datasets with FOD less than 100% and that met the minimum sample size and FOD requirements for use with
ProUCL; see note (b).
(b)- Sample size was greater than or equal to 10 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by ProUCL. The UCL shown is the one recommended by ProUCL. If more than
one UCL was recommended, the higher UCL was selected. ProUCL, version 5.0
(d) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The ProUCL software performs a goodness-of-fit test that accounts for data sets without any non-detect observations, as well as data sets with non-detect
observations. The software then determines the distribution of the data set for which the EPC is being derived (e.g., normal, lognormal, gamma, or non-discernable), and then calculates a conservative and stable 95% UCL value in accordance with the
framework described in “Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites” (USEPA, 2002b). The software includes numerous algorithms for calculating 95% UCL values, and provides a recommended UCL value
based on the algorithm that is most applicable to the statistical distribution of the data set. ProUCL will calculate a 95% UCL where there are 3 or more total samples with detected concentrations. Where too few samples or detects are available, the maximum
detected concentration is used as the EPC.
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
TABLE 3-2
SUMMARY OF EXPOSURE POINT CONCENTRATIONS
HUMAN HEALTH - SEDIMENT
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Constituent Reporting
Units
Number of
Samples
Frequency of
Detection
Minimum
Detected
Concentration
Maximum
Detected
Concentration
Mean Detected
Concentration UCL Selected UCL
Exposure Point
Concentration
(mg/kg)
Cobalt mg/kg 1 1 NA 5 NA ------5.4
Prepared by: HEG Checked by: ARD
Notes:
---: Calculations were not performed due to lack of samples ND - Not Determined
Mean - Arithmetic mean UCL - 95% Upper Confidence Limit
mg/kg - milligrams per kilogram
(c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples.
(a)- Mean calculated by ProUCL using the Kaplan-Meier (KM) estimation method for non-detect values: only given for datasets with FOD less than 100% and that met the minimum sample size and FOD requirements for use with ProUCL; see
note (b).
(b)- Sample size was greater than or equal to 10 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by ProUCL. The UCL shown is the one recommended by ProUCL. If more than one UCL
was recommended, the higher UCL was selected. ProUCL, version 5.0
(d) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The ProUCL software performs a goodness-of-fit test that accounts for data sets without any non-detect observations, as well as data sets with non-
detect observations. The software then determines the distribution of the data set for which the EPC is being derived (e.g., normal, lognormal, gamma, or non-discernable), and then calculates a conservative and stable 95% UCL value in
accordance with the framework described in “Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites” (USEPA, 2002b). The software includes numerous algorithms for calculating 95% UCL values, and
provides a recommended UCL value based on the algorithm that is most applicable to the statistical distribution of the data set. ProUCL will calculate a 95% UCL where there are 3 or more total samples with detected concentrations. Where
too few samples or detects are available, the maximum detected concentration is used as the EPC.
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
TABLE 3-3
SUMMARY OF EXPOSURE POINT CONCENTRATIONS
HUMAN HEALTH - SURFACE WATER
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Constituent Number of
Samples
Frequency of
Detection
Minimum
Detected
Concentration
Maximum
Detected
Concentration
Mean Detected
Concentration UCL Selected UCL Exposure Point
Concentration
Exposure Point
Concentration
(mg/L)
Aluminum 28 28 61.6 816 248.8 95% Adjusted Gamma UCL 314.4 314.4 0.3144
Chromium (VI)26 24 0.023 1.1 0.102 95% KM (Chebyshev) UCL 0.277 0.277 0.000277
Manganese 28 28 19.4 176 48.8 95% Adjusted Gamma UCL 60.3 60.3 0.0603
Zinc 29 16 2.6 10.6 5.194 95% KM (BCA) UCL 5.843 5.843 0.005843
Notes:
---: Calculations were not performed due to lack of samples ND - Not Determined
Mean - Arithmetic mean UCL - 95% Upper Confidence Limit
mg/L - milligrams per liter
µg/L - micrograms per liter
(c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples.
(a)- Mean calculated by ProUCL using the Kaplan-Meier (KM) estimation method for non-detect values: only given for datasets with FOD less than 100% and that met the minimum sample size and FOD requirements for use with ProUCL; see note (b).
(b)- Sample size was greater than or equal to 10 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by ProUCL. The UCL shown is the one recommended by ProUCL. If more than one UCL was
recommended, the higher UCL was selected. ProUCL, version 5.0
(d) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The ProUCL software performs a goodness-of-fit test that accounts for data sets without any non-detect observations, as well as data sets with non-detect observations. The software then
determines the distribution of the data set for which the EPC is being derived (e.g., normal, lognormal, gamma, or non-discernable), and then calculates a conservative and stable 95% UCL value in accordance with the framework described in “Calculating Upper Confidence Limits
for Exposure Point Concentrations at Hazardous Waste Sites” (USEPA, 2002b). The software includes numerous algorithms for calculating 95% UCL values, and provides a recommended UCL value based on the algorithm that is most applicable to the statistical distribution of the
data set. ProUCL will calculate a 95% UCL where there are 3 or more total samples with detected concentrations. Where too few samples or detects are available, the maximum detected concentration is used as the EPC.
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Prepared by: HEG Checked by: HES
TABLE 4-1
SUMMARY OF EXPOSURE POINT CONCENTRATIONS
ECOLOGICAL - SEDIMENT - CATAWBA RIVER - EXPOSURE AREA 1
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Constituent Reporting
Units
Number of
Samples
Frequency of
Detection
Minimum
Detected
Concentration
Maximum
Detected
Concentration
Mean
Detected
Concentration
UCL Selected UCL
Exposure Point
Concentration
(mg/kg)
Barium mg/kg 1 1 NA 65.7 ---------65.7
Prepared by: HEG Checked by: TCP
Notes:
---: Calculations were not performed due to lack of samples µg/L - micrograms per liter
Mean - Arithmetic mean UCL - 95% Upper Confidence Limit
mg/kg - milligrams per kilogram
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
(c) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The ProUCL software performs a goodness-of-fit test that accounts for data sets without any non-detect observations, as well as data sets with non-
detect observations. The software then determines the distribution of the data set for which the EPC is being derived (e.g., normal, lognormal, gamma, or non-discernable), and then calculates a conservative and stable 95% UCL value in
accordance with the framework described in “Calculating Upper Confidence Limits for Exposure Point Concentrations at Hazardous Waste Sites” (USEPA, 2002b). The software includes numerous algorithms for calculating 95% UCL values, and
provides a recommended UCL value based on the algorithm that is most applicable to the statistical distribution of the data set. ProUCL will calculate a 95% UCL where there are 3 or more total samples with detected concentrations. Where
too few samples or detects are available, the maximum detected concentration is used as the EPC.
(a)- Sample size was greater than or equal to 10 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by ProUCL. The UCL shown is the one recommended by ProUCL. If more than one UCL
was recommended, the higher UCL was selected. ProUCL, version 5.0
(b) - 0 is defined as a number of samples analyzed or the frequency of detection among samples.
TABLE 4-2
SUMMARY OF EXPOSURE POINT CONCENTRATIONS
ECOLOGICAL - SURFACE WATER - CATAWBA RIVER - EXPOSURE AREA 1
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Constituent Reporting
Units
Number of
Samples
Frequency of
Detection
Minimum
Detected
Concentration
Maximum
Detected
Concentration
Mean
Detected
Concentration
UCL Selected UCL Exposure Point
Concentration
Exposure Point
Concentration
(mg/L)
Aluminum µg/L 28 28 61.6 816 248.8 95% Adjusted Gamma UCL 314.4 314.4 0.3144
Cadmium µg/L 29 1 0.18 0.18 0.18 ------0.18 0.00018
Lead µg/L 28 28 0.07 1.9 0.346 95% H-UCL 0.462 0.462 0.000462
Manganese µg/L 28 28 19.4 176 48.8 95% Adjusted Gamma UCL 60.3 60.3 0.0603
Mercury µg/L 27 25 0.00051 0.0181 0.00177 95% KM H-UCL 0.00195 0.00195 0.00000195
Prepared by: HEG Checked by: ARD
Notes:
---: Calculations were not performed due to lack of samples µg/L - micrograms per liter
Mean - Arithmetic mean UCL - 95% Upper Confidence Limit
mg/L - milligrams per liter
(b) - 0 is defined as a number of samples analyzed or the frequency of detection among samples.
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
(a)- Sample size was greater than or equal to 10 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by ProUCL. The UCL shown is the one recommended by ProUCL. If more than one UCL was recommended, the higher UCL was
selected. ProUCL, version 5.0
(c) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The ProUCL software performs a goodness-of-fit test that accounts for data sets without any non-detect observations, as well as data sets with non-detect observations. The software
then determines the distribution of the data set for which the EPC is being derived (e.g., normal, lognormal, gamma, or non-discernable), and then calculates a conservative and stable 95% UCL value in accordance with the framework described in “Calculating Upper Confidence
Limits for Exposure Point Concentrations at Hazardous Waste Sites” (USEPA, 2002b). The software includes numerous algorithms for calculating 95% UCL values, and provides a recommended UCL value based on the algorithm that is most applicable to the statistical distribution
of the data set. ProUCL will calculate a 95% UCL where there are 3 or more total samples with detected concentrations. Where too few samples or detects are available, the maximum detected concentration is used as the EPC.
TABLE 4-3
SUMMARY OF EXPOSURE POINT CONCENTRATIONS
ECOLOGICAL - SURFACE WATER - EXPOSURE AREA 4
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
Constituent Reporting
Units
Number of
Samples
Frequency of
Detection
Minimum
Detected
Concentration
Maximum
Detected
Concentration
Mean
Detected
Concentration
UCL Selected UCL Exposure Point
Concentration
Exposure Point
Concentration
(mg/L)
Aluminum µg/L 6 6 170 47,300 8681 ------47300 47.3
Beryllium µg/L 6 5 0.058 34.8 7.4 ------34.8 0.0348
Boron µg/L 6 6 190 10,900 2444 ------10900 10.9
Cadmium µg/L 6 4 0.035 0.19 0.1105 ------0.19 0.00019
Cobalt µg/L 6 6 4.3 268 63.1 ------268 0.268
Copper µg/L 6 5 2.1 17.6 5.64 ------17.6 0.0176
Lead µg/L 6 4 0.12 17.7 7.37 ------17.7 0.0177
Manganese µg/L 6 6 190 22,100 6218 ------22100 22.1
Nickel µg/L 6 6 7.2 450 97.7 ------450 0.45
Selenium µg/L 6 5 0.77 87.1 18.8 ------87.1 0.0871
Zinc µg/L 6 6 8.2 75.6 35.6 ------75.6 0.0756
Prepared by: TCP Checked by: HEG
Notes:
---: Calculations were not performed due to lack of samples µg/L - micrograms per liter
Mean - Arithmetic mean UCL - 95% Upper Confidence Limit
mg/L - milligrams per liter
(b) - 0 is defined as a number of samples analyzed or the frequency of detection among samples.
* Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted
(a)- Sample size was greater than or equal to 10 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by ProUCL. The UCL shown is the one recommended by ProUCL. If more than one UCL was recommended, the higher UCL was selected. ProUCL,
version 5.0
(c) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The ProUCL software performs a goodness-of-fit test that accounts for data sets without any non-detect observations, as well as data sets with non-detect observations. The software then determines the
distribution of the data set for which the EPC is being derived (e.g., normal, lognormal, gamma, or non-discernable), and then calculates a conservative and stable 95% UCL value in accordance with the framework described in “Calculating Upper Confidence Limits for Exposure Point Concentrations at
Hazardous Waste Sites” (USEPA, 2002b). The software includes numerous algorithms for calculating 95% UCL values, and provides a recommended UCL value based on the algorithm that is most applicable to the statistical distribution of the data set. ProUCL will calculate a 95% UCL where there are
3 or more total samples with detected concentrations. Where too few samples or detects are available, the maximum detected concentration is used as the EPC.

Risk-Based Concentration Ash Basin-
Groundwater
Non-Cancer Cancer Final Exposure Point
Concentration
(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 9.6E+04 nc 9.6E+04 nc 4 0.00004 nc
Antimony 7440-36-0 1.7E+01 nc 1.7E+01 nc 0.001 0.00003 nc
Arsenic 7440-38-2 2.9E+01 4.5E+02 2.9E+01 nc 0.006 0.0002 nc
Barium 7440-39-3 5.0E+03 nc 5.0E+03 nc 0.08 0.00002 nc
Beryllium 7440-41-7 4.8E+02 nc 4.8E+02 nc 0.002 0.000003 nc
Boron 7440-42-8 1.9E+04 nc 1.9E+04 nc 0.4 0.00002 nc
Cadmium 7440-43-9 1.0E+01 nc 1.0E+01 nc 0.0004 0.00004 nc
Chromium, Total 7440-47-3 8.6E+03 nc 8.6E+03 nc 0.006 0.0000007 nc
Chromium (VI)18540-29-9 2.8E+01 7.6E+01 2.8E+01 nc 0.002 0.00009 nc
Cobalt 7440-48-4 3.3E+02 nc 3.3E+02 nc 0.2 0.0005 nc
Lithium 7439-93-2 0.03 NA nc
Manganese 7439-96-5 2.2E+03 nc 2.2E+03 nc 6 0.003 nc
Molybdenum 7439-98-7 4.8E+02 nc 4.8E+02 nc 0.003 0.00001 nc
Nickel 7440-02-0 1.0E+03 nc 1.0E+03 nc 0.04 0.00004 nc
Selenium 7782-49-2 4.8E+02 nc 4.8E+02 nc 0.02 0.00004 nc
Strontium 7440-24-6 1.9E+05 nc 1.9E+05 nc 0.3 0.000002 nc
Thallium 7440-28-0 0.0001 NA nc
Vanadium 7440-62-2 9.6E+02 nc 9.6E+02 nc 0.006 0.00001 nc
Zinc 7440-66-6 3.1E+04 nc 3.1E+04 nc 0.08 0.000002 nc
Cumulative Risk 0.004 0.00E+00
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NA - No toxicity value available; remedial goal not calculated
c - Remedial goal based on cancer risk NC - Not Calculated
nc - Remedial goal based on non-cancer hazard index
Exposure Routes Evaluated
Incidental Ingestion Yes
Dermal Contact Yes
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
NA
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
TABLE 5-1
SUMMARY OF ON-SITE GROUNDWATER EPC/RBC COMPARISON
CONSTRUCTION - CONSTRUCTION WORKER (ADULT)
ALLEN STEAM STATION
Risk Ratio
Non-Cancer Cancer
COPC CAS
Basis
NA
Page 2 of 11
Sediment
Non-Cancer Cancer Final Exposure Point
Concentration
(mg/kg)(mg/kg)(mg/kg)(mg/kg)
Cobalt 7440-48-4 3.7E+03 nc 3.7E+03 nc 5.4 0.001 nc
0.001 0.00E+00
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern
c - Remedial goal based on cancer risk
nc - remedial goal based on non-cancer hazard index
Exposure Routes Evaluated
Incidental Ingestion Yes
Dermal Contact Yes
Particulate Inhalation No
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
TABLE 5-2
SUMMARY OF OFF-SITE SEDIMENT EPC/RBC COMPARISON
RECREATIONAL SWIMMER - CHILD, ADOLESCENT, and ADULT
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Risk-Based Concentration
Basis
COPC CAS
Non-Cancer Cancer
Risk Ratio
Cumulative Risk
Page 3 of 11
Surface Water
Non-Cancer Cancer Final Exposure Point
Concentration
(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 1.1E+03 nc 1.1E+03 nc 0.3 0.0003 nc
Chromium (VI)18540-29-9 3.3E-01 2.0E-02 2.0E-02 c 0.0003 0.0009 1.40E-02
Manganese 7439-96-5 4.1E+01 nc 4.1E+01 nc 0.06 0.001 nc
Zinc 7440-66-6 3.4E+02 nc 3.4E+02 nc 0.006 0.00002 nc
Cumulative Risk 0.003 1.40E-02
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NA - No toxicity value available; remedial goal not calculated
c - Remedial goal based on cancer risk NC - Not Calculated
(a) Final RBC value for lead is 15 ug/L based on USEPA's action level of 15 ug/L for lead in drinking water (USEPA, 2012b). Refer to Attachment D, Section 2.5 of the Allen Steam Station CAP (HDR 2015).
(b) Lead was not included in the cumulative risk calculation, as risk for lead is typically evaluted using biokinetic models. Lead concentrations are less than the conservative action level of 15 ug/L.
Exposure Routes Evaluated
Incidental Ingestion Yes
Dermal Contact Yes
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
TABLE 5-3
SUMMARY OF OFF-SITE SURFACE WATER EPC/RBC COMPARISON
RECREATIONAL SWIMMER - CHILD, ADOLESCENT, and ADULT
ALLEN STEAM STATION
nc - Remedial goal based on non-cancer hazard index
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Basis
Risk-Based Concentration
COPC CAS
Cancer
Risk Ratio
Non-Cancer
Page 4 of 11
Sediment
Non-Cancer Cancer Final Exposure Point
Concentration
(mg/kg)(mg/kg)(mg/kg)(mg/kg)
Cobalt 7440-48-4 3.7E+03 nc 3.7E+03 nc 5.4 0.001 nc
Cumulative Risk 0.001 0.00E+00
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern
c - Remedial goal based on cancer risk
Exposure Routes Evaluated
Incidental Ingestion Yes
Dermal Contact Yes
Particulate Inhalation No
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
nc - Remedial goal based on non-cancer hazard index
TABLE 5-4
SUMMARY OF OFF-SITE SEDIMENT EPC/RBC COMPARISON
RECREATIONAL WADER - CHILD, ADOLESCENT, and ADULT
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Risk-Based Concentration
Basis
COPC CAS
Risk Ratio
Non-Cancer Cancer
Page 5 of 11

Risk-Based Concentration Surface Water
Non-Cancer Cancer Final
Exposure
Point
Concentration
(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 1.2E+03 nc 1.2E+03 nc 0.3 0.0003 nc
Chromium (VI)18540-29-9 9.5E-01 8.3E-02 8.3E-02 c 0.0003 0.0003 3.3E-03
Manganese 7439-96-5 9.0E+01 nc 9.0E+01 nc 0.06 0.001 nc
Zinc 7440-66-6 3.6E+02 nc 3.6E+02 nc 0.006 0.00002 nc
Cumulative Risk 0.001 3.3E-03
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NC - Not Calculated
c - Remedial goal based on cancer risk
(a) Final RBC value for lead is 15 ug/L based on USEPA's action level of 15 ug/L for lead in drinking water (USEPA, 2012b). Refer to Attachment D, Section 2.5 of the Allen Steam Station CAP (HDR 2015).
(b) Lead was not included in the cumulative risk calculation, as risk for lead is typically evaluted using biokinetic models. Lead concentrations are less than the conservative action level of 15 ug/L.
Exposure Routes Evaluated
Incidental Ingestion Yes
Dermal Contact Yes
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
TABLE 5-5
SUMMARY OF OFF-SITE SURFACE WATER EPC/RBC COMPARISON
RECREATIONAL WADER - CHILD, ADOLESCENT, and ADULT
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Basis
nc - Remedial goal based on non-cancer hazard index
COPC CAS
Cancer
Risk Ratio
Non-Cancer
NA - No toxicity value available; remedial goal not calculated
Page 6 of 11

Surface Water
Non-Cancer Cancer Final
Exposure
Point
Concentration
(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 5.6E+04 nc 5.6E+04 nc 0.3 0.000006 nc
Chromium (VI)18540-29-9 2.1E+00 9.8E-01 9.8E-01 c 0.0003 0.0003 2.8E-04
Manganese 7439-96-5 3.1E+02 nc 3.1E+02 nc 0.06 0.0002 nc
Zinc 7440-66-6 2.8E+04 nc 2.8E+04 nc 0.006 0.0000002 nc
Cumulative Risk 0.0005 2.8E-04
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NA - No toxicity value available; remedial goal not calculated
c - Remedial goal based on cancer risk
(a) Final RBC value for lead is 15 ug/L based on USEPA's action level of 15 ug/L for lead in drinking water (USEPA, 2012b). Refer to Attachment D, Section 2.5 of the Allen Steam Station CAP (HDR 2015).
(b) Lead was not included in the cumulative risk calculation, as risk for lead is typically evaluted using biokinetic models. Lead concentrations are less than the conservative action level of 15 ug/L.
Exposure Routes Evaluated
Incidental Ingestion No
Dermal Contact Yes
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
TABLE 5-6
SUMMARY OF OFF-SITE SURFACE WATER EPC/RBC COMPARISON
RECREATIONAL BOATER - RECREATIONAL BOATER (ADULT)
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Risk-Based Concentration
Basis
nc - Remedial goal based on non-cancer hazard index
NC - Not Calculated
COPC CAS
Cancer
Risk Ratio
Non-Cancer
Page 7 of 11

Surface Water
Non-Cancer Cancer Final Exposure Point
Concentration
(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 5.6E+04 nc 5.6E+04 nc 0.3 0.00001 nc
Chromium (VI)18540-29-9 2.1E+00 9.8E-01 9.8E-01 c 0.0003 0.0003 2.82E-04
Manganese 7439-96-5 3.1E+02 nc 3.1E+02 nc 0.06 0.0002 nc
Zinc 7440-66-6 2.8E+04 nc 2.8E+04 nc 0.006 0.0000002 nc
Cumulative Risk 0.0005 2.8E-04
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NA - No toxicity value available; remedial goal not calculated
c - Remedial goal based on cancer risk
(a) Final RBC value for lead is 15 ug/L based on USEPA's action level of 15 ug/L for lead in drinking water (USEPA, 2012b). Refer to Attachment D, Section 2.5 of the Allen Steam Station CAP (HDR 2015).
(b) Lead was not included in the cumulative risk calculation, as risk for lead is typically evaluted using biokinetic models. Lead concentrations are less than the conservative action level of 15 ug/L.
Exposure Routes Evaluated
Incidental Ingestion No
Dermal Contact Yes
Ambient Vapor Inhalation No
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
TABLE 5-7
SUMMARY OF OFF-SITE SURFACE WATER EPC/RBC COMPARISON
RECREATIONAL FISHER - RECREATIONAL FISHER (ADULT)
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Risk-Based Concentration
Basis
nc - Remedial goal based on non-cancer hazard index
NC - Not Calculated
COPC CAS
Cancer
Risk Ratio
Non-Cancer
Page 8 of 11

Non-Cancer Cancer Final Non-Cancer Cancer Final Non-Cancer Cancer Final Exposure Point
Concentration
(mg/kg)(mg/kg)(mg/kg)(mg/kg)(mg/kg)(mg/kg)(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 4.6E+03 nc 4.6E+03 nc 5.8E+03 nc 5.8E+03 nc 4.6E+03 nc 2.7 1.7E+03 nc 1.7E+03 nc 0.3 0.0002 nc
Chromium (VI)18540-29-9 1.4E+01 6.4E+00 6.4E+00 c 1.7E+01 2.7E+00 2.7E+00 c 1.4E+01 2.7E+00 200 6.9E-02 1.4E-02 1.4E-02 c 0.0003 0.004 0.02
Manganese 7439-96-5 6.4E+02 nc 6.4E+02 nc 8.1E+02 nc 8.1E+02 nc 6.4E+02 nc 2.4 2.7E+02 nc 2.7E+02 nc 0.06 0.0002 nc
Zinc 7440-66-6 1.4E+03 nc 1.4E+03 nc 1.7E+03 nc 1.7E+03 nc 1.4E+03 nc 2059 6.7E-01 nc 6.7E-01 nc 0.006 0.01 nc
Cumulative Risk 0.01 2.1E-02
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NA - No toxicity value available; remedial goal not calculated BCF - Bioconcentration Factor
c - Remedial goal based on cancer risk NC - Not Calculated Surface water RBC = Fish Tissue RBC / BCF
nc - Remedial goal based on non-cancer hazard index
Exposure Routes Evaluated
Ingestion Yes
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
Surface Water Risk Ratio
Non-Cancer Cancer
TABLE 5-8
SUMMARY OF FISH TISSUE EPC/RBC COMPARISON
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
FISHER - RECREATIONAL (ADULT AND ADOLESCENT)
COPC CAS
Basis
Risk-Based Concentration - Surface Water
Basis
BCF
(unitless)
Risk-Based Concentration - Fish Tissue
Lowest
Non-
Cancer
RBC
Value
Lowest
Cancer
RBC
Value
Adult Adolescent (a)
Basis
Page 9 of 11

Non-Cancer Cancer Final Non-Cancer Cancer Final Non-Cancer Cancer Final Exposure Point
Concentration
(mg/kg)(mg/kg)(mg/kg)(mg/kg)(mg/kg)(mg/kg)(mg/L)(mg/L)(mg/L)(mg/L)
Aluminum 7429-90-5 4.7E+02 nc 4.7E+02 nc 1.5E+02 nc 1.5E+02 nc 1.5E+02 nc 2.7 5.7E+01 nc 5.7E+01 nc 0.3 0.01 nc
Chromium (VI)18540-29-9 1.4E+00 6.6E-01 6.6E-01 c 4.6E-01 3.6E-02 3.6E-02 c 4.6E-01 3.6E-02 200 2.3E-03 1.8E-04 1.8E-04 c 0.0003 0.1 1.5
Manganese 7439-96-5 6.6E+01 nc 6.6E+01 nc 2.1E+01 nc 2.1E+01 nc 2.1E+01 nc 2.4 8.9E+00 nc 8.9E+00 nc 0.06 0.01 nc
Zinc 7440-66-6 1.4E+02 nc 1.4E+02 nc 4.6E+01 nc 4.6E+01 nc 4.6E+01 nc 2059 2.2E-02 nc 2.2E-02 nc 0.006 0.3 nc
Cumulative Risk 0.4 1.54E+00
Prepared by: HHS Checked by: TCP
Notes:
COPC - Chemical of potential concern NA - No toxicity value available; remedial goal not calculated BCF - Bioconcentration Factor
c - Remedial goal based on cancer risk NC - Not Calculated Surface water RBC = Fish Tissue RBC / BCF
nc - remedial goal based on non-cancer hazard index
Exposure Routes Evaluated
Ingestion Yes
Target Hazard Index (per Chemical)1E+00
Target Cancer Risk (per Chemical)1E-04
Risk Ratio
Non-Cancer Cancer
TABLE 5-9
SUMMARY OF FISH TISSUE EPC/RBC COMPARISON
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
FISHER - SUBSISTENCE (ADULT AND CHILD)
COPC CAS
Basis Basis
Surface WaterRisk-Based Concentration - Surface Water
Basis
BCF
(unitless)
Risk-Based Concentration - Fish Tissue
Lowest
Non-
Cancer
RBC
Value
Lowest
Cancer
RBC
Value
Adult Child (a)
Page 10 of 11
Source Table
(PRG Tables)Media Exposure Pathway Risk Ratio - Non-
cancer
Risk Ratio -
cancer
TABLE 5-1 Groundwater-On-Site CONSTRUCTION - CONSTRUCTION WORKER (ADULT)0.004 0.00E+00
TABLE 5-2 Sediment- Off-Site OFF-SITE RECREATIONAL SWIMMER - CHILD, ADOLESCENT, and ADULT 0.001 0.00E+00
TABLE 5-3 Surface Water- Off-Site OFF-SITE RECREATIONAL SWIMMER - CHILD, ADOLESCENT, and ADULT 0.003 1.4E-02
TABLE 5-4 Sediment- Off-Site OFF-SITE RECREATIONAL WADER - CHILD, ADOLESCENT, and ADULT 0.001 0.00E+00
TABLE 5-5 Surface Water- Off-Site OFF-SITE RECREATIONAL WADER - CHILD, ADOLESCENT, and ADULT 0.001 3.3E-03
TABLE 5-6 Surface Water- Off-Site OFF-SITE RECREATIONAL BOATER - OFF-SITE RECREATIONAL BOATER (ADULT)0.0005 2.8E-04
TABLE 5-7 Surface Water- Off-Site OFF-SITE RECREATIONAL FISHER (ADULT)0.0005 2.8E-04
TABLE 5-8 Biota (fish)- Off-Site OFF-SITE FISHER - RECREATIONAL (ADULT AND ADOLESCENT)0.01 2.1E-02
TABLE 5-9 Biota (fish)- Off-Site OFF-SITE FISHER - SUBSISTENCE (ADULT AND ADOLESCENT)0.4 1.5E+00
Prepared by: HHS Checked by: TCP
TABLE 5-10
SUMMARY OF EXPOSURE POINT CONCENTRATION COMPARISON TO RISK-BASED CONCENTRATION
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELLMONT, NC
Page 11 of 11
Plants Mammal/Terr.
Vertebrates Fish Invertebrates Birds Soil
BW IRF IRW PF AM AF AI AB SF HR SUF
kg kg/kg BW/day L/kg BW/day %%%%%%hectares unitless
Meadow Volea 0.033 0.33 0.21 97.6%0%0%0%0%2.4%0.027 1
Muskratb 1.17 0.3 0.97 99.3%0%0%0%0%0.7%0.13 1
Mallard Duckc 1.134 0.068 0.057 48.3%0%0%48.3%0%3.3%435 1
American Robind 0.08 0.129 0.14 40%0%0%58%0%2%0.42 1
Red-Tailed Hawke 1.06 0.18 0.058 0%91.5%0%0%8.5%0%876 1
Bald Eaglef 3.75 0.12 0.058 0%28%58%0%13.5%0.5%2199 1
Red Foxg 4.54 0.16 0.085 6%89%0%2%0%3%1226 1
River Otterh 6.76 0.19 0.081 0%0%100%0%0%0%348 1
Great Blue Heroni 2.229 0.18 0.045 0%0%90%9.5%0%0.5%227 1
NOTES:
a BW, IRf, IRw, PF, HR from USEPA 1993 (sections 2-328 and 2-329); SF from Sample and Suter 1994
b BW, IRf, IRw, PF, HR from USEPA 1993 (sections 2-340 and 2-341); SF from TechLaw Inc. 2013; IRF from Nagy 2001
c BW, PF, AI, HR from USEPA 1993 (sections 2-43 and 2-45); SF from Beyer et al. 1994; IRF from Nagy 2001
d BW, PF, AI, HR from USEPA 1993 (sections 2-197 and 2-198); SF from Sample and Suter 1994; IRF from Nagy 2001
e BW, PF, AM, AB, IRF, HR from USEPA 1993 (sections 2-82 and 2-83)Ecological ReceptorsBW - Body Weight
kg - Kilograms
IR - Ingestion Rate
HR - Home Range
HERBIVORE
OMNIVORE
CARNIVORE
PISCIVORE
kg/kg BW/day - Kilograms Food per Kilograms Body Weight per Day
L/kg BW/day - Liters Water per Kilogram Body Weight per Day
Algorithm ID
Units
Parameter
Exposure Parameters for Ecological Receptors
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Table 1
Seasonal Use
Factorj
Home
RangeBody Weight Food Ingestion Rate Water Ingestion
Rate
Dietary Composition
f BW, PF, AF, AM, AB, HR from USEPA 1993 (sections 2-91 and 2-97); IRF from Nagy 2001
g BW, PF, AF, AI, HR from USEPA 1993 (sections 2-224 and 2-225); SF from Beyer et al. 1994
h BW, IRw, AF, HR from USEPA 1993 (sections 2-264 and 2-266); SF from Sample and Suter 1994; IRF from Nagy 2001
i BW, PF, AF, AI, HR from USEPA 1993 (sections 2-8 and 2-9); SF from Sample and Suter 1994; IRF from Nagy 2001
j Seasonal Use Factor is set to a default of 1 to be overly conservative and protective of ecological receptors.
SUF - Seasonal Use Factor
PF - Plant Matter Ingestion Percentage
AM - Mammal/Terrestrial Vertebrate ingestion percentage
AF - Fish Ingestion Percentage
AB - Bird Ingestion Percentage
SF - Soil Ingestion Percentage
Table 2
Toxicity Reference Values for Ecological Receptors
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Mallard Duck
(mg/kg/day)
Great Blue
Heron
(mg/kg/day)
Bald Eagle
(mg/kg/day)
Muskrat
(mg/kg/day)
River Otter
(mg/kg/day)
American
Robin
(mg/kg/day)
Red-Tailed
Hawk
(mg/kg/day)
Meadow Vole
(mg/kg/day)
Red Fox
(mg/kg/day)
Aluminuma 110 110 110 1.93 1.93 110 110 1.93 1.93
Antimonya NA NA NA 0.059 0.059 NA NA 0.059 0.059
Arsenicb 2.24 2.24 2.24 1.04 1.04 2.24 2.24 1.04 1.04
Bariumc 20.8 20.8 20.8 51.8 51.8 20.8 20.8 51.8 51.8
Berylliuma NA NA NA 0.532 0.532 NA NA 0.532 0.532
Borona, b 28.8 28.8 28.8 28 28 28.8 28.8 28 28
Cadmiuma 1.47 1.47 1.47 0.77 0.77 1.47 1.47 0.77 0.77
Calcium EN EN EN EN EN EN EN EN EN
Chromium, Totald 1 1 1 2740 2740 1 1 2740 2740
Chromium VI (hexavalent)a NA NA NA 9.24 9.24 NA NA 9.24 9.24
Chromium IIIa 2.66 2.66 2.66 2.4 2.4 2.66 2.66 2.4 2.4
Cobalta 7.61 7.61 7.61 7.33 7.33 7.61 7.61 7.33 7.33
Coppera 4.05 4.05 4.05 5.6 5.6 4.05 4.05 5.6 5.6
Iron EN EN EN EN EN EN EN EN EN
Leadb 1.63 1.63 1.63 4.7 4.7 1.63 1.63 4.7 4.7
Magnesium EN EN EN EN EN EN EN EN EN
Manganesea 179 179 179 51.5 51.5 179 179 51.5 51.5
Mercurye 3.25 3.25 3.25 1.01 1.01 3.25 3.25 1.01 1.01
Molybdenuma, d 3.53 3.53 3.53 0.26 0.26 3.53 3.53 0.26 0.26
Nickela 6.71 6.71 6.71 1.7 1.7 6.71 6.71 1.7 1.7
Potassium EN EN EN EN EN EN EN EN EN
Seleniuma 0.29 0.29 0.29 0.143 0.143 0.29 0.29 0.143 0.143
Sodium EN EN EN EN EN EN EN EN EN
Strontiuma, d NA NA NA 263 263 NA NA 263 263
Thalliuma NA NA NA 0.015 0.015 NA NA 0.015 0.015
Titanium NA NA NA NA NA NA NA NA NA
Vanadiuma 0.344 0.344 0.344 4.16 4.16 0.344 0.344 4.16 4.16
Zinca 66.1 66.1 66.1 75.4 75.4 66.1 66.1 75.4 75.4
Nitrated NA NA NA 507 507 NA NA 507 507
Analyte
Aquatic
TRVs (NOAEL)
Terrestrial
Mallard Duck
(mg/kg/day)
Great Blue
Heron
Bald Eagle
(mg/kg/day)
Muskrat
(mg/kg/day)
River Otter
(mg/kg/day)
American
Robin
Red-Tailed
Hawk
Meadow Vole
(mg/kg/day)
Red Fox
(mg/kg/day)
Aluminuma 1100 1100 1100 19.3 19.3 1100 1100 19.3 19.3
Antimonya NA NA NA 0.59 0.59 NA NA 0.59 0.59
Arsenicb 40.3 40.3 40.3 1.66 1.66 40.3 40.3 1.66 1.66
Bariumc 41.7 41.7 41.7 75 75 41.7 41.7 75 75
Berylliuma NA NA NA 6.6 6.6 NA NA 6.6 6.6
Borona, b 100 100 100 93.6 93.6 100 100 93.6 93.6
Cadmiuma 2.37 2.37 2.37 10 10 2.37 2.37 10 10
Calcium EN EN EN EN EN EN EN EN EN
Chromium, Totald 5 5 5 27400 27400 5 5 27400 27400
Chromium VI (hexavalent)a NA NA NA 40 40 NA NA 40 40
Chromium IIIa 2.66 2.66 2.66 9.625 9.625 2.66 2.66 9.625 9.625
Cobalta 7.8 7.8 7.8 10.9 10.9 7.8 7.8 10.9 10.9
Coppera 12.1 12.1 12.1 9.34 9.34 12.1 12.1 9.34 9.34
Iron EN EN EN EN EN EN EN EN EN
Leadb 3.26 3.26 3.26 8.9 8.9 3.26 3.26 8.9 8.9
Magnesium EN EN EN EN EN EN EN EN EN
Manganesea 348 348 348 71 71 348 348 71 71
Mercurye 0.37 0.37 0.37 0.16 0.16 0.37 0.37 0.16 0.16
Molybdenuma, d 35.3 35.3 35.3 2.6 2.6 35.3 35.3 2.6 2.6
Nickela 11.5 11.5 11.5 3.4 3.4 11.5 11.5 3.4 3.4
Potassium EN EN EN EN EN EN EN EN EN
Seleniuma 0.579 0.579 0.579 0.215 0.215 0.579 0.579 0.215 0.215
Sodium EN EN EN EN EN EN EN EN EN
Strontiuma, d NA NA NA 2630 2630 NA NA 2630 2630
Thalliuma NA NA NA 0.075 0.075 NA NA 0.075 0.075
Vanadiuma 0.688 0.688 0.688 8.31 8.31 0.688 0.688 8.31 8.31
Zinca 66.5 66.5 66.5 75.9 75.9 66.5 66.5 75.9 75.9
Nitrated NA NA NA 1130 1130 NA NA 1130 1130
TRV - Toxicity Reference Value
Analyte Aquatic
TRVs (LOAEL)
Terrestrial
NA - Not available
b USEPA 2005 EcoSSL
c Only a single paper (Johnson et al., 1960) with data on the toxicity of barium hydroxide to one avian species (chicken) was identified by USEPA (2005); therefore, an avian TRV could
not be derived and an Eco-SSL could not be calculated for avian wildlife (calculation requires a minimum of three results for two test species). Johnson et al. (1960) reports a subchronic
NOAEL of 208.26 mg/kg/d. The NOAEL was multiplied by an uncertainty factor of 0.1 to derive a very conservative TRV of 20.8 mg/kg/d.
d Sample et al. 1996
a CH2M Hill. 2014. Tier 2 Risk-Based Soil Concentrations Protective of Ecological Receptors at the Hanford Site. CHPRC-01311. Revision 2. July.
Http://pdw.hanford.gov/arpir/pdf.cfm?accession=0088115
Table 2 (Cont.)
NOTES:
NOAEL - No Observed Adverse Effects Level
LOAEL - Lowest Observed Effects Level
EN - Essential nutrient
Table 3
Exposure Area and Area Use Factors for Ecological Receptors
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Mallard
Duck
Great Blue
Heron Muskrat River
Otter Bald Eagle American
Robin
Red-Tailed
Hawk
Meadow
Vole Red Fox
Ecological Exposure Area 1 22.6 5.20%9.96%100%6.49%1.03%100%2.580%100%1.84%
NOTES:
Area Use Factor (AUF)
Exposure Point Exposure Areaa
(hectares)
a Ecological Exposure Area 1 is located east of the plant and active ash basin. The area includes the shoreline of the Catawba River and some open water habitat.
Table 4
EPCs for Use in the Risk Assessment
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
COPC CASRN
Sediment EPC Used in
Risk Assessmentc
(mg/kg)
Surface Water EPC Used
in Risk Assessment
(mg/L)
Aluminum 7429-90-5 0.314
Barium 7440-39-3 65.7
Cadmium 7440-43-9 0.00018
Cobalt 7440-48-4
Lead 7439-92-1 0.0004620
Manganese 7439-96-5 0.060
Mercury 7439-97-6 0.00000195
Vanadium 7440-62-2
Zinc 7440-66-6
Aquatic EPCsa, b
a EPCs for sediment are based on maximum values. EPCs for surface water are based on 95% UCLs.
b Aquatic receptors are evaluated based on surface water and sediment data.
c Analysis of solids (i.e., soil and sediment) was reported as dry weight.
NOTES:
COPC - Constituent of Potential Concern
CASRN - Chemical Abstracts Service Registration Number
EPC - Exposure Point Concentration
Table 5
Calculation of Average Daily Doses for Mallard Duck
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCp EPCi NIRw ADDW Pf NIRf NIRp ADDp Af NIRa ADDa Sf NIRs ADDs BF ADDt SUF AUF ADDtot
Analyte COPEC in Water
(mg/L)
COPEC in Solid
(mg/kg)
Slope, or Plant
Uptake (BAF)Intercept
Estimated1
Concentration
in Vegetation
(mg/kg dry)
Slope, or
Invertebrate
Uptake (BAF)
Intercept
Estimated2
Concentration
in
Invertebrates
(mg/kg dry)
Water
Ingestion Rate
(L/kg BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Plant Matter
(percent)
Food Ingestion
Rate, Wet
(kg/kg BW/day)
Plant Ingestion
Rate, Dry
(kg/kg BW/day)
Unadjusted
Average Daily
Dose Plant
(mg/kg/day)
Fraction Diet
Invertebrates
(percent)
Invertebrates
Ingestion Rate
(kg dry/kg
BW/day)
Unadjusted
Average Daily
Dose
Invertebrates
(mg/kg/day)
Fraction Diet
Soil (percent)
Soil Ingestion3
Rate (kg dry/kg
BW/day)
Unadjusted
Average Daily
Dose Soil
(mg/kg/day)
Bioavailability3
(percent)
Omnivore
Intake
(mg/kg/day)
Seasonal Use
Factor
(unitless)
Area Use Factor
(Exposure
Area/Home
Range)
Adjusted Total
Omnivore
Average Daily
Dose
(mg/kg/day)
Aluminum 0.3144 0.0008 0.0000 1 0.00 0.057 0.018 48%0.068 0.0049 0.000000 48%0.007 0.0000 3.3%0.00029 0.00000 100%0.02 1 0.052 0.000931
Barium 65.7000 0.03 1.9710 1 65.70 0.057 0.000 48%0.068 0.0049 0.009710 48%0.007 0.4747 3.3%0.00029 0.01917 100%0.5036 1 0.052 0.026164
Cadmium 0.0002 0.6 0.00 0.057 0.000010 48%0.068 0.0049 0.000000 48%0.007 0.0000 3.3%0.00029 0.00000 100%0.000 1 0.052 0.000001
Lead 0.0005 0.117 0.00 0.057 0.0000 48%0.068 0.0049 0.000000 48%0.007 0.0000 3.3%0.00029 0.00000 100%0.000026 1 0.052 0.000001
Manganese 0.0603 0.050 0.0 0.057 0.003 48%0.068 0.0049 0.000000 48%0.007 0.0000 3.3%0.00029 0.00000 100%0.00 1 0.052 0.000179
Mercury 0.000002 1.136 0 0.057 1.1115E-07 48%0.068 0.0049 0.000000 48%0.007 0.0000 3.3%0.00029 0.00000 100%1.1115E-07 1 0.052 0.000000
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
AVERAGE DAILY DOSE VIA:
WATER
1 Bechtel Jacobs Company 1998a; Baes et al. 1984 (Mo); Environmental Restoration Division - Manual ERD-AG-003 1999; default value of 1 is used for constituents for which a BAF could not be found.
2 Bechtel Jacobs Company 1998b, Table 2, median BAFs for sediment to benthic invertebrates for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn; Sample et al. 1998b (earthworms) for Mn; default value of 1 is used for constituents for which a BAF could not be found.
PLANTS/VEGETATION INVERTEBRATES SOIL
3 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
Table 6
Calculation of Average Daily Doses for Great Blue Heron
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCfish EPCi NIRw ADDw Af NIRf NIRa ADDa Af NIRa ADDa BF ADDt SUF AUF ADDtot
Analyte COPEC in
Water (mg/L)
COPEC in Solid
(mg/kg)
Fish Uptake
(BCF)
Estimated1
Concentration
in Fish (mg/kg)
Slope, or
Invertebrate
Uptake (BAF)
Intercept
Estimated2
Concentration
in
Invertebrates
(mg/kg dry)
Water
Ingestion Rate
(L/kg BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Animal Matter
(percent)
Food Ingestion
Rate, Wet
(kg/kg
BW/day)
Fish Ingestion
Rate (kg/kg
BW/day)
Unadjusted
Average Daily
Dose
(mg/kg/day)
Fraction Diet
Invertebrates
(percent)
Invertebrates
Ingestion Rate
(kg dry/kg
BW/day)
Unadjusted
Average Daily
Dose
Invertebrates
(mg/kg/day)
Bioavailability3
(percent)
Piscivore
Intake
(mg/kg/day)
Seasonal Use
Factor
(unitless)
Area Use
Factor
(Exposure
Area/Home
Range)
Adjusted Total
Piscivore
Average Daily
Dose
(mg/kg/day)
Aluminum 0.3144 0.1 0.03 1 0.31 0.045 0.014 90%0.18 0.162 0.005 10%0.004 0.0012 100%0.02 1 0.100 0.002
Barium 65.7000 4 0.00 1 0.00 0.045 0.000 90%0.18 0.162 0.000 10%0.004 0.0000 100%0.00000 1 0.100 0.000
Cadmium 0.0002 50 0.00900 0.6 0.00 0.045 0.000 90%0.18 0.162 0.001 10%0.004 0.0000 100%0.001 1 0.100 0.000
Lead 0.0005 300 0.14 0.117 0.00 0.045 0.000 90%0.18 0.162 0.022 10%0.004 0.0000 100%0.022474 1 0.100 0.002
Manganese 0.0603 400 24.12 0.682 -0.809 0.07 0.045 0.003 90%0.18 0.162 3.907 10%0.004 0.0002 100%3.91 1 0.100 0.389
Mercury 0.0000020 63000 0.12 1.136 2.2152E-06 0.045 0.000 90%0.18 0.0405 0.005 10%0.004 0.0000 100%0.005 1 0.100 0.000
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
WATER FISH INVERTEBRATES
AVERAGE DAILY DOSE VIA:
1 Al (Voigt et al. 2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division - Manual ERD-AG-003 1999.
3 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
2 Bechtel Jacobs Company 1998b, Table 2, median BAFs for sediment to benthic invertebrates for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn; Sample et al. 1998b (earthworms) for Mn; default value of 1 is used for constituents for which a BAF could not be found.
Table 7
Calculation of Average Daily Doses for Muskrat
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCp NIRW ADDw Pf NIRf NIRp ADDp Sf NIRs ADDs BF ADDt SUF AUF ADDtot
Analyte COPEC in Water
(mg/L)
COPEC in Solid
(mg/kg)
Slope, or Plant
Uptake (BAF)Intercept
Estimated1
Concentration
in Vegetation
(mg/kg dry)
Water Ingestion
Rate (L/kg
BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Plant Matter
(percent)
Food Ingestion
Rate, Wet
(kg/kg BW/day)
Plant Ingestion
Rate, Dry
(kg/kg/day)
Unadjusted
Average Daily
Dose Plant
(mg/kg/day)
Fraction Diet
Soil (percent)
Soil Ingestion
Rate (kg dry/kg
BW/day)
Unadjusted
Average Daily
Dose Soil
(mg/kg/day)
Bioavailability2
(percent)
Herbivore
Intake
(mg/kg/day)
Seasonal Use
Factor (unitless)
Area Use Factor
(Exposure
Area/Home
Range)
Adjusted Total
Herbivore
Average Daily
Dose
(mg/kg/day)
Aluminum 0.3144 0.0008 0.0000 0.97 0.30 99%0.3 0.045 0.00000 1%0.000273 0.00000 100%0.30 1 1 0.30
Barium 65.7000 0.03 1.9710 0.97 0.00 99%0.3 0.045 0.08807 1%0.000273 0.00233 100%0.09 1 1 0.09
Cadmium 0.0002 0.97 0.00 99%0.3 0.045 0.00000 1%0.000273 0.00000 100%0.00 1 1 0.00
Lead 0.0005 0.97 0.00 99%0.3 0.045 0.00000 1%0.000273 0.00000 100%0.00 1 1 0.00
Manganese 0.0603 0.050 0.0 0.97 0.06 99%0.3 0.045 0.00000 1%0.000273 0.00000 100%0.06 1 1 0.06
Mercury 0.000002 0.97 0.00 99%0.3 0.045 0.00000 1%0.000273 0.00000 100%0.00 1 1 0.00
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
AVERAGE DAILY DOSE VIA:
WATER PLANTS / VEGETATION SOIL
1 Bechtel Jacobs Company 1998a; Baes et al. 1984 (Mo); Environmental Restoration Division - Manual ERD-AG-003 1999; default value of 1 is used for constituents for which a BAF could not be found.
2 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
Table 8
Calculation of Average Daily Doses for River Otter
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCPREY NIRw ADDw Pf NIRf NIRa ADDa BF ADDt SUF AUF ADDtot
Analyte
COPEC in Water
(mg/L)
COPEC in Solid
(mg/kg)
Fish Uptake
(BCF)
Estimated1
Concentration
in Fish (mg/kg)
Water
Ingestion Rate
(L/kg BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Animal Matter
(percent)
Food Ingestion
Rate, Wet
(kg/kg BW/day)
Fish Ingestion
Rate (kg/kg
BW/day)
Unadjusted
Average Daily
Dose
(mg/kg/day)
Bioavailability2
(percent)
Piscivore Intake
(mg/kg/day)
Seasonal Use
Factor
(unitless)
Area Use Factor
(Exposure
Area/Home
Range)
Adjusted Total
Piscivore
Average Daily
Dose
(mg/kg/day)
Aluminum 0.3144 0.1 0.03 0.081 0.025 100%0.19 0.19 0.0060 100%0.031 1 0.065 0.002042
Barium 65.7000 4 0.00 0.081 0.000 100%0.19 0.19 0.000 100%0.000 1 0.065 0.000000
Cadmium 0.0002 50 0.00900 0.081 0.000 100%0.19 0.19 0.00171 100%0.002 1 0.065 0.000112
Lead 0.0005 300 0.14 0.081 0.000 100%0.19 0.19 0.026 100%0.026 1 0.065 0.001713
Manganese 0.0603 400 24.12 0.081 0.005 100%0.19 0.19 4.58 100%4.588 1 0.065 0.297936
Mercury 0.000002 63000 0.12 0.081 0.000 100%0.19 0.19 0.023 100%0.023 1 0.065 0.001516
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
AVERAGE DAILY DOSE VIA:
DRINKING WATER FISH
1 Al (Voigt et al. 2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division - Manual ERD-AG-003 1999.
2 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
Table 9
Hazard Quotients for COPCs - Aquatic Receptors
Ecological Exposure Area 1
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Mallard Duck Great Blue Heron Muskrat River Otter
Aluminum 8.46E-06 1.85E-05 1.58E-01 1.06E-03
Barium 1.26E-03 0.00E+00 1.75E-03 0.00E+00
Cadmium 3.63E-07 9.93E-05 2.27E-04 1.45E-04
Lead 8.39E-07 1.37E-03 9.53E-05 3.64E-04
Manganese 9.98E-07 2.17E-03 1.14E-03 5.79E-03
Mercury 1.78E-09 1.52E-04 1.87E-06 1.50E-03
Mallard Duck Great Blue Heron Muskrat River Otter
Aluminum 8.46E-07 1.85E-06 1.58E-02 1.06E-04
Barium 6.27E-04 0.00E+00 1.21E-03 0.00E+00
Cadmium 2.25E-07 6.16E-05 1.75E-05 1.12E-05
Lead 4.20E-07 6.86E-04 5.04E-05 1.92E-04
Manganese 5.13E-07 1.12E-03 8.24E-04 4.20E-03
Mercury 1.56E-08 1.34E-03 1.18E-05 9.47E-03

Hazard Quotients greater than or equal to 1 are highlighted in gray and in boldface.
Wildlife Receptor Hazard Quotient Estimated using the 'No Observed Adverse Effects Level'
AquaticAnalyte
Analyte
Wildlife Receptor Hazard Quotient Estimated using the 'Lowest Observed Adverse Effects
Aquatic
NOTES:
NM - Not measured due to lack of a Toxicity Reference Value
Plants Mammal/Terr.
Vertebrates Fish Invertebrates Birds Soil
BW IRF IRW PF AM AF AI AB SF HR SUF
kg kg/kg BW/day L/kg BW/day %%%%%%hectares unitless
Meadow Volea 0.033 0.33 0.21 97.6%0%0%0%0%2.4%0.027 1
Muskratb 1.17 0.3 0.97 99.3%0%0%0%0%0.7%0.13 1
Mallard Duckc 1.134 0.068 0.057 48.3%0%0%48.3%0%3.3%435 1
American Robind 0.08 0.129 0.14 40%0%0%58%0%2%0.42 1
Red-Tailed Hawke 1.06 0.18 0.058 0%91.5%0%0%8.5%0%876 1
Bald Eaglef 3.75 0.12 0.058 0%28%58%0%13.5%0.5%2199 1
Red Foxg 4.54 0.16 0.085 6%89%0%2%0%3%1226 1
River Otterh 6.76 0.19 0.081 0%0%100%0%0%0%348 1
Great Blue Heroni 2.229 0.18 0.045 0%0%90%9.5%0%0.5%227 1
NOTES:
SUF - Seasonal Use Factor
PF - Plant Matter Ingestion Percentage
AM - Mammal/Terrestrial Vertebrate ingestion percentage
AF - Fish Ingestion Percentage
AB - Bird Ingestion Percentage
SF - Soil Ingestion Percentage
f BW, PF, AF, AM, AB, HR from USEPA 1993 (sections 2-91 and 2-97); IRF from Nagy 2001
g BW, PF, AF, AI, HR from USEPA 1993 (sections 2-224 and 2-225); SF from Beyer et al. 1994
h BW, IRw, AF, HR from USEPA 1993 (sections 2-264 and 2-266); SF from Sample and Suter 1994; IRF from Nagy 2001
i BW, PF, AF, AI, HR from USEPA 1993 (sections 2-8 and 2-9); SF from Sample and Suter 1994; IRF from Nagy 2001
j Seasonal Use Factor is set to a default of 1 to be overly conservative and protective of ecological receptors.
Table 1
Seasonal Use
Factorj
Home
RangeBody Weight Food Ingestion Rate Water Ingestion
Rate
Dietary Composition
Algorithm ID
Units
Parameter
Exposure Parameters for Ecological Receptors
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Ecological ReceptorsBW - Body Weight
kg - Kilograms
IR - Ingestion Rate
HR - Home Range
HERBIVORE
OMNIVORE
CARNIVORE
PISCIVORE
kg/kg BW/day - Kilograms Food per Kilograms Body Weight per Day
L/kg BW/day - Liters Water per Kilogram Body Weight per Day
a BW, IRf, IRw, PF, HR from USEPA 1993 (sections 2-328 and 2-329); SF from Sample and Suter 1994
b BW, IRf, IRw, PF, HR from USEPA 1993 (sections 2-340 and 2-341); SF from TechLaw Inc. 2013; IRF from Nagy 2001
c BW, PF, AI, HR from USEPA 1993 (sections 2-43 and 2-45); SF from Beyer et al. 1994; IRF from Nagy 2001
d BW, PF, AI, HR from USEPA 1993 (sections 2-197 and 2-198); SF from Sample and Suter 1994; IRF from Nagy 2001
e BW, PF, AM, AB, IRF, HR from USEPA 1993 (sections 2-82 and 2-83)
Table 2
Toxicity Reference Values for Ecological Receptors
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Mallard Duck
(mg/kg/day)
Great Blue
Heron
(mg/kg/day)
Bald Eagle
(mg/kg/day)
Muskrat
(mg/kg/day)
River Otter
(mg/kg/day)
American
Robin
(mg/kg/day)
Red-Tailed
Hawk
(mg/kg/day)
Meadow Vole
(mg/kg/day)
Red Fox
(mg/kg/day)
Aluminuma 110 110 110 1.93 1.93 110 110 1.93 1.93
Antimonya NA NA NA 0.059 0.059 NA NA 0.059 0.059
Arsenicb 2.24 2.24 2.24 1.04 1.04 2.24 2.24 1.04 1.04
Bariumc 20.8 20.8 20.8 51.8 51.8 20.8 20.8 51.8 51.8
Berylliuma NA NA NA 0.532 0.532 NA NA 0.532 0.532
Borona, b 28.8 28.8 28.8 28 28 28.8 28.8 28 28
Cadmiuma 1.47 1.47 1.47 0.77 0.77 1.47 1.47 0.77 0.77
Calcium EN EN EN EN EN EN EN EN EN
Chromium, Totald 1 1 1 2740 2740 1 1 2740 2740
Chromium VI (hexavalent)a NA NA NA 9.24 9.24 NA NA 9.24 9.24
Chromium IIIa 2.66 2.66 2.66 2.4 2.4 2.66 2.66 2.4 2.4
Cobalta 7.61 7.61 7.61 7.33 7.33 7.61 7.61 7.33 7.33
Coppera 4.05 4.05 4.05 5.6 5.6 4.05 4.05 5.6 5.6
Iron EN EN EN EN EN EN EN EN EN
Leadb 1.63 1.63 1.63 4.7 4.7 1.63 1.63 4.7 4.7
Magnesium EN EN EN EN EN EN EN EN EN
Manganesea 179 179 179 51.5 51.5 179 179 51.5 51.5
Mercurye 3.25 3.25 3.25 1.01 1.01 3.25 3.25 1.01 1.01
Molybdenuma, d 3.53 3.53 3.53 0.26 0.26 3.53 3.53 0.26 0.26
Nickela 6.71 6.71 6.71 1.7 1.7 6.71 6.71 1.7 1.7
Potassium EN EN EN EN EN EN EN EN EN
Seleniuma 0.29 0.29 0.29 0.143 0.143 0.29 0.29 0.143 0.143
Sodium EN EN EN EN EN EN EN EN EN
Strontiuma, d NA NA NA 263 263 NA NA 263 263
Thalliuma NA NA NA 0.015 0.015 NA NA 0.015 0.015
Titanium NA NA NA NA NA NA NA NA NA
Vanadiuma 0.344 0.344 0.344 4.16 4.16 0.344 0.344 4.16 4.16
Zinca 66.1 66.1 66.1 75.4 75.4 66.1 66.1 75.4 75.4
Nitrated NA NA NA 507 507 NA NA 507 507
Analyte
Aquatic
TRVs (NOAEL)
Terrestrial
Mallard Duck
(mg/kg/day)
Great Blue
Heron
(mg/kg/day)
Bald Eagle
(mg/kg/day)
Muskrat
(mg/kg/day)
River Otter
(mg/kg/day)
American
Robin
(mg/kg/day)
Red-Tailed
Hawk
(mg/kg/day)
Meadow Vole
(mg/kg/day)
Red Fox
(mg/kg/day)
Aluminuma 1100 1100 1100 19.3 19.3 1100 1100 19.3 19.3
Antimonya NA NA NA 0.59 0.59 NA NA 0.59 0.59
Arsenicb 40.3 40.3 40.3 1.66 1.66 40.3 40.3 1.66 1.66
Bariumc 41.7 41.7 41.7 75 75 41.7 41.7 75 75
Berylliuma NA NA NA 6.6 6.6 NA NA 6.6 6.6
Borona, b 100 100 100 93.6 93.6 100 100 93.6 93.6
Cadmiuma 2.37 2.37 2.37 10 10 2.37 2.37 10 10
Calcium EN EN EN EN EN EN EN EN EN
Chromium, Totald 5 5 5 27400 27400 5 5 27400 27400
Chromium VI (hexavalent)a NA NA NA 40 40 NA NA 40 40
Chromium IIIa 2.66 2.66 2.66 9.625 9.625 2.66 2.66 9.625 9.625
Cobalta 7.8 7.8 7.8 10.9 10.9 7.8 7.8 10.9 10.9
Coppera 12.1 12.1 12.1 9.34 9.34 12.1 12.1 9.34 9.34
Iron EN EN EN EN EN EN EN EN EN
Leadb 3.26 3.26 3.26 8.9 8.9 3.26 3.26 8.9 8.9
Magnesium EN EN EN EN EN EN EN EN EN
Manganesea 348 348 348 71 71 348 348 71 71
Mercurye 0.37 0.37 0.37 0.16 0.16 0.37 0.37 0.16 0.16
Molybdenuma, d 35.3 35.3 35.3 2.6 2.6 35.3 35.3 2.6 2.6
Nickela 11.5 11.5 11.5 3.4 3.4 11.5 11.5 3.4 3.4
Potassium EN EN EN EN EN EN EN EN EN
Seleniuma 0.579 0.579 0.579 0.215 0.215 0.579 0.579 0.215 0.215
Sodium EN EN EN EN EN EN EN EN EN
Strontiuma, d NA NA NA 2630 2630 NA NA 2630 2630
Thalliuma NA NA NA 0.075 0.075 NA NA 0.075 0.075
Vanadiuma 0.688 0.688 0.688 8.31 8.31 0.688 0.688 8.31 8.31
Zinca 66.5 66.5 66.5 75.9 75.9 66.5 66.5 75.9 75.9
Nitrated NA NA NA 1130 1130 NA NA 1130 1130
TRV - Toxicity Reference Value
Table 2 (Cont.)
NOTES:
NOAEL - No Observed Adverse Effects Level
LOAEL - Lowest Observed Effects Level
EN - Essential nutrient
NA - Not available
b USEPA 2005 EcoSSL
c Only a single paper (Johnson et al., 1960) with data on the toxicity of barium hydroxide to one avian species (chicken) was identified by USEPA (2005); therefore, an avian TRV could not
be derived and an Eco-SSL could not be calculated for avian wildlife (calculation requires a minimum of three results for two test species). Johnson et al. (1960) reports a subchronic
NOAEL of 208.26 mg/kg/d. The NOAEL was multiplied by an uncertainty factor of 0.1 to derive a very conservative TRV of 20.8 mg/kg/d.
d Sample et al. 1996
a CH2M Hill. 2014. Tier 2 Risk-Based Soil Concentrations Protective of Ecological Receptors at the Hanford Site. CHPRC-01311. Revision 2. July.
Http://pdw.hanford.gov/arpir/pdf.cfm?accession=0088115
Analyte Aquatic
TRVs (LOAEL)
Terrestrial
Table 3
Exposure Area and Area Use Factors for Ecological Receptors
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
Mallard
Duck
Great Blue
Heron Muskrat River
Otter
Bald
Eagle
American
Robin
Red-Tailed
Hawk
Meadow
Vole Red Fox
Ecological Exposure Area 4 0.57 0.13%0.25%100%0.16%0.03%100%0.065%100%0.05%
NOTES:
Area Use Factor (AUF)
Exposure Point Exposure Areaa
(hectares)
a Ecological Exposure Area 4 consists of a small wetland area west of the active ash basin.
Table 4
EPCs for Use in the Risk Assessment
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
COPC CASRN Soil EPC Used in Risk
Assessmentc (mg/kg)
Surface Water EPC Used
in Risk Assessment
(mg/L)
Aluminum 7429-90-5 47.3
Beryllium 7440-41-7 0.0348
Boron 7440-42-8 10.9
Cadmium 7440-43-9 0.00019
Cobalt 7440-48-4 0.268
Copper 7440-50-8 0.0176
Lead 7439-92-1 0.0177
Manganese 7439-96-5 22.1
Nickel 7440-02-0 0.45
Selenium 7782-49-2 0.0871
Zinc 7440-66-6 0.0756
Terrestrial EPCsa
a EPCs for this exposure area are based on maximum values.
b Terrestrial receptors were evaluated for this exposure area based on surface water and sediment data.
c Analysis of solids (i.e., soil and sediment) was reported as dry weight.
NOTES:
COPC - Constituent of Potential Concern
CASRN - Chemical Abstracts Service Registration Number
EPC - Exposure Point Concentration
Table 5
Calculation of Average Daily Doses for American Robin
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCp EPCinv NIRw ADDw Pf NIRf NIRp ADDp Af NIRa ADDa Sf NIRs ADDs BF ADDt SUF AUF ADDtot
Analyte COPEC in Water
(mg/L)
COPEC in Solid
(mg/kg)
Slope, or Plant
Uptake (BAF)Intercept
Estimated1
Concentration
in Vegetation
(mg/kg dry)
Slope, or
Invertebrate
Uptake (BAF)
Intercept
Estimated2
Concentration
in Invertebrates
(mg/kg dry)
Water Ingestion
Rate (L/kg
BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Plant Matter
(percent)
Food Ingestion
Rate, Wet
(kg/kg BW/day)
Plant Ingestion
Rate, Dry
(kg/kg BW/day)
Unadjusted
Average Daily
Dose Plant
(mg/kg/day)
Fraction Diet
Invertebrates
(percent)
Invertebrates
Ingestion Rate
(kg dry/kg
BW/day)
Unadjusted
Average Daily
Dose
Invertebrates
(mg/kg/day)
Fraction Diet
Soil (percent)
Soil Ingestion
Rate (kg dry/kg
BW/day)
Unadjusted
Average Daily
Dose Soil
(mg/kg/day)
Bioavailability3
(percent)
Omnivore
Intake
(mg/kg/day)
Seasonal Use
Factor
Area Use Factor
(Exposure
Area/Home
Range)
Adjusted Total
Omnivore
Average Daily
Dose
(mg/kg/day)
Aluminum 47.3 0.14 6.6 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%6.6 1 1.0 6.62
Beryllium 0.0348 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.005 1 1.0 0.005
Boron 10.9 0.14 1.5 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%1.53 1 1.0 1.53
Cadmium 0.0002 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.000 1 1.0 0.000
Cobalt 0.2680 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.04 1 1.0 0.04
Copper 0.0176 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.00 1 1.0 0.00
Lead 0.0177 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.00248 1 1.0 0.002478
Manganese 22.1 0.14 3.1 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%3.09 1 1.0 3.09
Nickel 0.5 0.14 0.1 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.063 1 1.0 0.063
Selenium 0.0871 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.012 1 1.0 0.012
Zinc 0.0756 0.14 0.0 40%0.129 0.01 0.000000 58%0.0097 0.00000000 2%0.00034 0.00000 100%0.01 1 1.0 0.011
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
AVERAGE DAILY DOSE VIA:
WATER PLANTS/VEGETATION INVERTEBRATES SOIL
3 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
1 Bechtel Jacobs Company 1998a; Baes et al. 1984 (Mo); Environmental Restoration Division - Manual ERD-AG-003 1999; default value of 1 is used for constituents for which a BAF could not be found.
2 Sample et al. 1998b; EPA 1999 (Screening Level Ecological Risk Assessment Protocol for Hazardous Waste Combustion Facilities); Environmental Restoration Division - Manual ERD-AG-003 1999; default value of 1 is used for constituents for which a BAF could not be found.
Table 6
Calculation of Average Daily Doses for Red-Tailed Hawk
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCmb NIRw ADDw PT PA NIRf NIRa ADDa BF ADDt SUF AUF ADDTOT
Analyte COPEC in
Water (mg/L)
COPEC in Solid
(mg/kg)
Slope, or
Vertebrate
Uptake (BAF)1
Intercept
Estimated
Concentration in
Mammals and
Birds (mg/kg)
Water
Ingestion Rate
(L/kg BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Terrestrial
Vertebrates
(percent)
Fraction Diet
Avian
Vertebrates
(percent)
Food
Ingestion
Rate, Wet
(kg/kg
BW/day)
Vertebrate
Ingestion Rate
(kg/kg
BW/day)
Unadjusted
Average Daily
Dose
(mg/kg/day)
Bioavailability2
(percent)
Carnivore
Intake
(mg/kg/day)
Seasonal Use
Factor
(unitless)
Area Use
Factor
(Exposure
Area/Home
Range)
Adjusted Total
Carnivore
Average Daily
Dose (mg/kg/day)
Aluminum 47.3 1 0 0.058 2.74 91.5%8.5%0.18 0.18 0.0000000 100%2.74 1 0.0007 0.00179
Beryllium 0.0348 0.05 0 0.058 0.00 91.5%8.5%0.18 0.18 0.0000000 100%0.00 1 0.0007 0.0000
Boron 10.9 1 0 0.058 0.63 91.5%8.5%0.18 0.18 0.0000000 100%0.6 1 0.0007 0.000
Cadmium 0.0002 0.058 0.00 91.5%8.5%0.18 0.18 0.0000000 100%0.00 1 0.0007 0.0000
Cobalt 0.2680 0.058 0.02 91.5%8.5%0.18 0.18 0.0000000 100%0.02 1 0.0007 0.00001
Copper 0.0176 0.058 0.00 91.5%8.5%0.18 0.18 0.0000000 100%0.00 1 0.0007 0.00000
Lead 0.0177 0.058 0.00 91.5%8.5%0.18 0.18 0.0000000 100%0.00103 1 0.0007 0.0000007
Manganese 22.1 0.004 0 0.058 1.28 91.5%8.5%0.18 0.18 0.0000000 100%1.28 1 0.0007 0.0008
Nickel 0.5 0.058 0.03 91.5%8.5%0.18 0.18 0.0000000 100%0.03 1 0.0007 0.0000
Selenium 0.0871 0.058 0.01 91.5%8.5%0.18 0.18 0.0000000 100%0.01 1 0.0007 0.0000
Zinc 0.0756 0.058 0.00 91.5%8.5%0.18 0.18 0.0000000 100%0.0 1 0.0007 0.0000
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
AVERAGE DAILY DOSE VIA:
WATER VERTEBRATE PREY
1 Sample et al. 1998a; EPA 2007 EcoSSLs, Att 4-1, Table 4a
2 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
Table 7
Calculation of Average Daily Doses for Meadow Vole
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs EPCp NIRW ADDW Pf NIRf NIRp ADDp Sf NIRS ADDS BF ADDt SUF AUF ADDtot
Analyte COPEC in
Water (mg/L)
COPEC in Solid
(mg/kg)
Slope, or Plant
Uptake (BAF)Intercept
Estimated1
Concentration in
Vegetation
(mg/kg dry)
Water
Ingestion Rate
(L/kg BW/day)
Unadjusted
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Plant Matter
(percent)
Food Ingestion
Rate, Wet
(kg/kg
BW/day)
Plant
Ingestion
Rate, Dry
(kg/kg/day)
Unadjusted
Average Daily
Dose Plant
(mg/kg/day)
Fraction Diet
Soil (percent)
Soil Ingestion
Rate (kg
dry/kg
BW/day)
Unadjusted
Average Daily
Dose Soil
(mg/kg/day)
Bioavailability2
(percent)
Herbivore
Intake
(mg/kg/day)
Seasonal Use
Factor
Area Use
Factor
(Exposure
Area/Home
Range)
Adjusted Total
Herbivore
Average Daily
Dose
(mg/kg/day)
Aluminum 47.3 0.0008 0.0000 0.21 9.93 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%9.933 1 1.0 9.93
Beryllium 0.0348 0.002 0.0000 0.21 0.01 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.007 1 1.0 0.007
Boron 10.9 1 0.0000 0.21 2.29 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%2.289 1 1.0 2.289
Cadmium 0.0002 0.21 0.00 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.000 1 1.0 0.000
Cobalt 0.2680 0.004 0.0000 0.21 0.06 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.056 1 1.0 0.056
Copper 0.0176 0.21 0.00 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.004 1 1.0 0.00
Lead 0.0177 0.21 0.00 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.004 1 1.0 0.003717
Manganese 22.1 0.050 0.0 0.21 4.64 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%4.641 1 1.0 4.64
Nickel 0.5 0.21 0.09 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.095 1 1.0 0.095
Selenium 0.0871 0.21 0.02 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.018 1 1.0 0.018
Zinc 0.0756 0.21 0.02 97.6%0.33 0.048 0.000000 2.4%0.001 0.00000 100%0.016 1 1.0 0.02
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
AVERAGE DAILY DOSE VIA:
WATER PLANTS / VEGETATION SOIL
1 Bechtel Jacobs Company 1998a; Baes et al. 1984 (Mo); Environmental Restoration Division - Manual ERD-AG-003 1999; default value of 1 is used for constituents for which a BAF could not be found.
2 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
Table 8
Calculation of Average Daily Doses for Red Fox
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
EPCw EPCs epcm epcp epcinv NIRw ADDw Pf NIRf NIRp ADDp Ai NIRi ADDi Am NIRm NIRm ADDm Sf NIRs ADDs BF ADDt SUF AUF ADDtot
Analyte COPEC in
Water (mg/L)
COPEC in
Solid (mg/kg)
Slope, or
Mammal
Uptake (BAF)
Intercept
Estimated1
Concentration
in Mammals
(mg/kg)
Slope, or
Plant Uptake
(BAF)
Intercept
Estimated2
Concentration
in Vegetation
(mg/kg dry)
Slope, or
Invertebrate
Uptake (BAF)
Intercept
Estimated3
Concentration
in Invertebrates
(mg/kg dry)
Water
Ingestion
Rate (L/kg
BW/day)
Average Daily
Dose Water
(mg/kg/day)
Fraction Diet
Plant Matter
(percent)
Food
Ingestion
Rate, Wet
(kg/kg
BW/day)
Plant
Ingestion
Rate, Dry
(kg/kg
BW/day)
Average Daily
Dose Plant
(mg/kg/day)
Fraction Diet
Invertebrates
(percent)
Invertebrates
Ingestion
Rate (kg
dry/kg
BW/day)
Average Daily
Dose
Invertebrates
(mg/kg/day)
Fraction Diet
Animal
Matter
(percent)
Food
Ingestion
Rate, Wet
(kg/kg
BW/day)
Mammal
Ingestion
Rate (kg/kg
BW/day)
Unadjusted
Average Daily
Dose
(mg/kg/day)
Fraction Diet
Soil (percent)
Soil Ingestion
Rate (kg
dry/kg
BW/day)
Average Daily
Dose Soil
(mg/kg/day)
Bioavailability4
(percent)
Carnivore
Intake
(mg/kg/day)
Seasonal Use
Factor
Area Use
Factor
(Exposure
Area/Home
Range)
Adjusted
Total
Carnivore
ADD
(mg/kg/day)
Aluminum 47.3 1 0.00000 0.0008 0.0000000 0.22 0.00000 0.085 4.021 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%4.021 1 0.0005 0.00187
Beryllium 0.0348 0.05 0.00000 0.002 0.0000000 0.22 0.00000 0.085 0.003 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.003 1 0.0005 0.00000
Boron 10.9 1 0.00000 1 0.0000000 1 0.00000 0.085 0.927 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.927 1 0.0005 0.0004
Cadmium 0.0002 0.085 0.000 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.000 1 0.0005 0.00000
Cobalt 0.2680 0.085 0.023 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.023 1 0.0005 0.00001
Copper 0.0176 0.085 0.001 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.001 1 0.0005 0.000
Lead 0.0177 0.085 0.002 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.002 1 0.0005 0.00000070
Manganese 22.1 0.085 1.879 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%1.879 1 0.0005 0.0009
Nickel 0.5 0.085 0.038 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.038 1 0.0005 0.00002
Selenium 0.0871 0.085 0.007 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.007 1 0.0005 0.00000
Zinc 0.0756 0.085 0.006 6%0.16 0.0014 0.0000000000 2%0.0004 0.00000000 89%0.16 0.14 0.0000000 3.0%0.00062 0.00000 100%0.006 1 0.0005 0.0000
NOTES:
EPC - Exposure Point Concentration BF - Bioavailability Factor SUF - Seasonal Use Factor
NIR - Normalized Ingestion Rate BAF - Bioaccumulation Factor AUF - Area Use Factor
ADD - Average Daily Dose BCF - Bioconcentration Factor
4 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors.
AVERAGE DAILY DOSE VIA:
SOILMAMMAL PREYWATERINVERTEBRATE PREYPLANTS/VEGETATION
1 Sample et al. 1998a; EPA 2007 EcoSSLs, Att 4-1, Table 4a; default value of 1 is used for constituents for which a BAF could not be found.
2 Bechtel Jacobs Company 1998a; Environmental Restoration Division - Manual ERD-AG-003 1999 for non-reproductive tissues; default value of 1 is used for constituents for which a BAF could not be found.
3 Sample et al. 1998b; Environmental Restoration Division - Manual ERD-AG-003 1999; default value of 1 is used for constituents for which a BAF could not be found.
Table 9
Hazard Quotients for COPCs - Terrestrial Receptors
Ecological Exposure Area 4
Baseline Ecological Risk Assessment
Duke Energy
Allen Steam Station
American Robin Red-Tailed Hawk Meadow Vole Red Fox
Aluminum 6.02E-02 1.62E-05 5.15E+00 9.69E-04
Beryllium NC NC 1.37E-02 2.59E-06
Boron 5.30E-02 1.43E-05 8.18E-02 1.54E-05
Cadmium 1.81E-05 4.88E-09 5.18E-05 9.75E-09
Cobalt 4.93E-03 1.33E-06 7.68E-03 1.44E-06
Copper 6.08E-04 1.64E-07 6.60E-04 1.24E-07
Lead 1.52E-03 4.10E-07 7.91E-04 1.49E-07
Manganese 1.73E-02 4.66E-06 9.01E-02 1.70E-05
Nickel 9.39E-03 2.53E-06 5.56E-02 1.05E-05
Selenium 4.20E-02 1.13E-05 1.28E-01 2.41E-05
Zinc 1.60E-04 4.32E-08 2.11E-04 3.96E-08

American Robin Red-Tailed Hawk Meadow Vole Red Fox
Aluminum 6.02E-03 1.62E-06 5.15E-01 9.69E-05
Beryllium NC NC 1.11E-03 2.08E-07
Boron 1.53E-02 4.11E-06 2.45E-02 4.60E-06
Cadmium 1.12E-05 3.03E-09 3.99E-06 7.51E-10
Cobalt 4.81E-03 1.30E-06 5.16E-03 9.72E-07
Copper 2.04E-04 5.49E-08 3.96E-04 7.45E-08
Lead 7.60E-04 2.05E-07 4.18E-04 7.86E-08
Manganese 8.89E-03 2.40E-06 6.54E-02 1.23E-05
Nickel 5.48E-03 1.48E-06 2.78E-02 5.23E-06
Selenium 2.11E-02 5.68E-06 8.51E-02 1.60E-05
Zinc 1.59E-04 4.29E-08 2.09E-04 3.94E-08
Hazard Quotients greater than or equal to 1 are highlighted in gray and in boldface.
NOTES:
NC - Not calculated due to lack of a Toxicity Reference Value
Analyte
Analyte
Wildlife Receptor Hazard Quotient Estimated using the 'Lowest Observed Adverse Effects
Level'
Terrestrial
Wildlife Receptor Hazard Quotient Estimated using the 'No Observed Adverse Effects
Level'
Terrestrial

Appendix C

Exposure Modeling and
Human Health Risk
Assessment for Diesel
Emissions

1805956.000 - 5209 C-1
Air Dispersion Modeling for Allen Ash Basin Closure
I used screening models to evaluate the potential for both cancer and non-cancer risks from
diesel exhaust emissions due to increased trucking operations related to the closure of the coal
ash basin at the Duke Energy Allen Steam Station. The calculated cancer and non-cancer risks
are associated with increased diesel trucking activity near residential properties that lie along
transportation corridors near the Allen Station. Modelling was conducted for the cap in place
(CIP) closure option, the onsite and offsite excavation closure options (A and B)1, and the
hybrid closure option. Details of these scenarios are provided in the main body of the report.
Emission rates for the fleet of diesel trucks operating as part of closure activities were calculated
based on truck activity and emission factors representative of the region from the U.S.
Environmental Protection Agency (EPA) Mobile Vehicle Emissions Simulator (MOVES). I
estimated airborne concentrations of emitted pollutants using the EPA model AERMOD for
atmospheric dispersion and transport. AERMOD is a Gaussian plume model that accounts for
the impacts of meteorology and land characteristics on airborne pollutants. Together these tools
allowed for the estimation of airborne concentrations of diesel particulate matter (DPM) emitted
from passing trucks and subsequent calculation of potential non-cancer health impacts (hazard
index [HI]) and cancer risk estimates (excess lifetime cancer risk [ELCR]).
The following sections detail the data and models used in this evaluation, including the
meteorological data, trucking operations, emissions calculations, and dispersion modeling. I also
include additional discussion of the results and associated uncertainties.

1 Excavation closure option A involves excavation of ash from the Allen ash basin and placement in a new onsite
landfill; excavation closure option B involves excavation of the ash from the Allen basin and transportation of
the ash to an offsite landfill 50 miles away from Allen.

1805956.000 - 5209 C-2
Methodology
Meteorological Data
AERMOD-ready five-year 2 meteorological data sets of hourly surface meteorological data for
the years 2012–2016 were generated from the National Weather Service (NWS) Automated
Surface Observing System (ASOS) station at the Charlotte/Douglas International Airport
(KCLT) in Charlotte, North Carolina.3 The Charlotte/Douglas International Airport is located
approximately 5 km from the Allen Station. I judged this station to be representative of the
meteorology in the region of the Allen Station. Surface parameters applied to the modeling
study included wind speed and direction, temperature, pressure, relative humidity, and cloud
cover. Twice daily rawinsonde 4 observations of upper air winds and temperatures were also
taken from Piedmont Triad International Airport (KGSO), which at 140 km is the closest upper
air sounding site.5
The meteorological data were processed using AERMET (v16216) with default options.6 To
better resolve lower wind speeds and avoid overestimating calm conditions, AERMINUTE was
also applied.7 AERSURFACE 8 was used to define the land-use characteristics in the region

2 Use of five years of meteorological data is standard in regulatory application of AERMOD (EPA Guideline on
Air Quality Models, Section 8.3.1, 2005).
3 Integrated surface hourly weather observations are available at ftp://ftp.ncdc.noaa.gov/pub/data/noaa/. 2-minute
average ASOS wind data are available at ftp://ftp.ncdc.noaa.gov/pub/data/asos-onemin/.
4 A rawinsonde is a device typically carried by weather balloons that collects meteorological and atmospheric
data, especially regarding winds.
5 Not all meteorological stations will record upper air data (soundings); however, the difference in locations does
not substantively affect the model because the atmosphere at higher levels has less spatial variability. Thus,
upper atmospheric conditions at Greensboro, North Carolina, are likely to be similar to those at Charlotte, North
Carolina, and by extension at the Allen Station
6 AERMET is an EPA program that will read standard recorded meteorological observations, calculate boundary
layer meteorological parameters, and output the data in a format readable by the AERMOD model (U.S. EPA
2016).
7 Because the Charlotte/Douglas International Airport has an ASOS where 2-minute average wind direction and
wind speed data are recorded every minute, it was possible to use AERMINUTE with AERMOD. More
frequent measurements of wind data allow for better resolution of wind characteristics.

1805956.000 - 5209 C-3
around the surface observational site (i.e., Charlotte/Douglas International Airport). The surface
characteristics, which are important when calculating the level of atmospheric dispersion in
meteorological modeling, include surface roughness, albedo,9 and Bowen ratios.10
Trucking Operations
Diesel emissions estimates from trucking are based on the number of trucks passing a given
receptor location along offsite transportation corridors used during ash basin closure. The total
number of truckloads required for transporting ash, earthen fill, and geosynthetic materials
under the Allen closure options were projected by Duke Energy (2018). These truckloads equate
to 21,830 total truck passes for CIP; 24,942 total truck passes for onsite Excavation A;
1,697,265 truck passes for Excavation B; and 19,600 truck passes for hybrid closure. Trucks
hauling earthen fill are assumed to travel 11 miles one way from the site, and trucks hauling
geosynthetic material are assumed to travel 200 miles one way from Georgetown, South
Carolina. The number of truckloads in the Excavation B option, which assumes an offsite
landfill 50 miles from the Allen Station, does not include loads hauling landfill capping
materials (i.e., topsoil and geosynthetic material) because at 50 miles distant, the community
impacts by landfill construction activities were judged to be separate from the local Allen
Station community. Air modeling is conducted for a receptor along the transportation route
within the 11-mile radius traveled by trucks hauling ash, earthen fill, and geosynthetic material,
depending on the closure option. Trucks are assumed to travel in round trips, so the number of
material loads was doubled to represent the number of truck passes.

8 AERSURFACE is the EPA model used to calculate average land-use characteristics. It can read standard
databases and calculate the average values of surface roughness, albedo, and Bowen ratios, consistent with EPA
recommended methods.
9 Albedo is the ratio of reflected flux density to incident flux density. It indicates how much incoming energy is
absorbed by the land surface. Light surfaces (such as snow) will reflect higher levels of incoming energy.
10 The Bowen ratio is the ratio of sensible to latent heat fluxes from the earth’s surface up into the air. A lower
Bowen ratio indicates greater water content in the land surface.

1805956.000 - 5209 C-4
AERMOD
The AERMOD modeling system (U.S. EPA 2016) is a steady-state plume model that
incorporates air dispersion based on planetary boundary layer turbulence structure and scaling
concepts, including treatment of surface and elevated sources. EPA’s “Guideline on Air Quality
Models” (U.S. EPA 2016) identifies AERMOD as the preferred refined dispersion modeling
technique for receptors within 50 km of a modeled source.
The latest version of AERMOD (v16216r) was used with default options to conduct the
modeling.
Modeled Source and Receptors
AERMOD was configured to simulate an approximately 1-km stretch of road. This road
segment was assumed representative of any segment along the proposed transportation
corridors. The road emission source was modeled as a continuous distribution of emission along
the road due to the passage of multiple trucks. In the cross-road direction, the emissions drop off
based on a normal (or Gaussian) distribution. The road emissions were represented using a line
of closely spaced volume sources running down the center of the road. Volume sources define
the initial pollutant distribution based on an initial release height and the standard deviation of
the normal distribution in both the vertical and horizontal directions (sigma-y and sigma-z). The
appropriate values for the release height and standard deviations were calculated based on
guidance in EPA’s Haul Road Working Group Final Report (U.S. EPA 2010).
Transport and dispersion of pollutants away from the road segment may be sensitive to the
predominant wind directions at the site and the orientation of the road compared to those
predominant wind directions. To fully evaluate the impacts of any road segment, four
orientations of the road were considered. Modeled orientations included roads running
north/south, east/west, northeast/southwest, and northwest/southeast. For each modeled road
orientation, receptors were included on both sides of the road to represent impacts at distances

1805956.000 - 5209 C-5
between 10 and 150 m from the edge of the road. The representative road segments and
sampling receptor locations are shown in Figure C-1.
AERMOD was run for the five-year period (2012–2016) defined by the meteorological data.
The resulting five-year average dispersion factors were assumed representative of long-term
average dispersion of truck roadway emissions along roads in this region.

1805956.000 - 5209 C-6

Figure C-1. Location of road sources (blue) and sampling receptors (red) for each of 4 road
orientations

1805956.000 - 5209 C-7
Source Emission Rates
Emission rates for mobile sources are typically calculated based on a combination of emission
factors and activity rates. The emission factors define the amount of pollutant emitted per unit
distance traveled (grams of pollutant per kilometer traveled), and the activity rates define how
much activity occurs (i.e., the number of kilometers driven by the vehicles). Emission factors
will be specific to the type of vehicle being considered, the model year, the age of the vehicle,
and the local climate. For this evaluation, EPA’s MOVES model was used to define fleet
average emission factors for various years between 2018 and 2050 (2050 is the last year
simulated by MOVES) (U.S. EPA 2015). These emission factors are specific to North Carolina
and have been selected to represent large, single-unit diesel trucks.
Tailpipe emissions from diesel trucks (DPM) are the subset of PM10 of particular interest when
evaluating the cancer and non-cancer risk estimates in this analysis. The DPM emission factors
generated by MOVES were multiplied by the expected number of trucks under each of the
considered closure options to calculate emission rates for each one.
For the cancer risk analysis, emissions were calculated as an average over the regulatory default
70-year residential exposure duration. If the truck activity for a scenario occurs over a shorter
period, the duration of the truck activity exposure is factored into the 70-year averaging time
(OEHHA 2015). These average emission rates were multiplied by the dispersion factors
calculated by AERMOD to predict airborne concentrations. The resulting values were then
multiplied by the cancer unit risk factor 11 to quantify cancer risk.

11 A “reasonable estimate” for the inhalation unit risk of 3.0×10-4 (µg/m3)-1 was applied based on California
guidelines (OEHHA 2015).

1805956.000 - 5209 C-8
For the non-cancer analysis, airborne concentrations of DPM were calculated and compared to
the non-cancer risk threshold of 5 µg/m3.12 In this case, the average concentrations are not tied
to a 70-year period and are calculated over the period of operation for each closure option.

12 North Carolina defers to EPA’s chronic non-cancer reference concentration (RfC) for DPM of 5 µg/m3 based on
diesel engine exhaust to estimate risk from diesel emissions (Integrated Risk Information System [IRIS]. U.S.
EPA. Diesel engine exhaust).

1805956.000 - 5209 C-9
Uncertainties
A number of uncertainties should be considered when evaluating the modeled results. First, air
dispersion modeling is a mathematical calculation of pollutant transport and dispersion and may
differ from real world conditions. Typically, for regulatory applications, air dispersion models
are expected to predict concentrations within a factor of two (40 CFR Part 51). Longer
averaging periods, such as those used in this study, would often have lower uncertainties
compared with shorter average periods such as 1-hour or 24-hour averages.
The calculation of emission factors is meant to represent fleet average characteristics. The fleet
of trucks used at this specific site may differ from the average values included in MOVES. This
may result in higher or lower actual emission rates. Additionally, MOVES includes predictions
of future year emission factors based on typical patterns of vehicle turnover and any regulations
scheduled to be implemented in future years. Not all future regulations are presently known and
future conditions may vary from these estimates.
For the non-cancer risk, an evaluation of the average concentrations was calculated over the
actual period of activity, which varies between closure options. For this portion of the
evaluation, there was no accounting for how long the emissions were present. The non-cancer
risk value is generally considered applicable over a period of approximately eight years. For
activities that occur for less than eight years, comparison with this risk value may overstate the
actual risk. Correspondingly, for activities that run significantly longer than eight years, there
may be sub-periods with higher average concentrations and higher associated non-cancer risk.

1805956.000 - 5209 C-10
Results
Worst-case impacts were calculated for each distance from the modeled road. The worst-case
result represents the highest value calculated over the four road orientations. This may not be
the same orientation for all distances. For example, a road that runs northeast/southwest aligns
with the predominant wind direction. This results in higher concentrations for receptors close to
the road. For receptors farther away from the edge of the road, the worst case occurs for a
northwest/southeast road where winds are perpendicular to the road. Worst-case results are
reported in Table 9-2 of the main report. The following sections include results for all road
orientations and distances from both sides of the road.
Model-estimated cancer risk
ELCR results for the four road orientations and both sides of the road are provided in Table C-1.

1805956.000 - 5209 C-11
Table C-1. ELCR estimates from DPM exposure due to trucking operations
associated with closure of the Allen Plant ash basin under CIP closure,
excavation closure, and hybrid closure. Results for each road orientation
and distances from both sides of the road (ELCR columns per orientation).
E-W Run NE-SW Run N-S Run NW-SE Run
CIP
10 m 2.2E-09 2.2E-09 2.9E-09 2.8E-09 3.1E-09 2.9E-09 2.2E-09 2.3E-09
20 m 2.2E-09 2.2E-09 2.5E-09 2.4E-09 2.7E-09 2.4E-09 2.2E-09 2.3E-09
30 m 1.8E-09 1.8E-09 2.0E-09 1.9E-09 2.2E-09 1.9E-09 1.8E-09 1.9E-09
40 m 1.5E-09 1.5E-09 1.7E-09 1.6E-09 1.8E-09 1.6E-09 1.5E-09 1.6E-09
50 m 1.3E-09 1.3E-09 1.4E-09 1.3E-09 1.5E-09 1.3E-09 1.3E-09 1.4E-09
60 m 1.1E-09 1.1E-09 1.2E-09 1.2E-09 1.3E-09 1.1E-09 1.1E-09 1.2E-09
70 m 1.0E-09 1.0E-09 1.1E-09 1.0E-09 1.2E-09 9.8E-10 9.8E-10 1.1E-09
80 m 9.2E-10 9.2E-10 9.6E-10 9.2E-10 1.1E-09 8.7E-10 8.8E-10 1.0E-09
90 m 8.4E-10 8.4E-10 8.7E-10 8.3E-10 9.6E-10 7.8E-10 8.0E-10 9.1E-10
100 m 7.7E-10 7.7E-10 8.0E-10 7.6E-10 8.7E-10 7.0E-10 7.4E-10 8.4E-10
110 m 7.2E-10 7.2E-10 7.3E-10 7.0E-10 8.0E-10 6.4E-10 6.8E-10 7.8E-10
120 m 6.7E-10 6.7E-10 6.8E-10 6.4E-10 7.3E-10 5.9E-10 6.3E-10 7.3E-10
130 m 6.2E-10 6.2E-10 6.3E-10 6.0E-10 6.8E-10 5.4E-10 5.9E-10 6.8E-10
140 m 5.9E-10 5.9E-10 5.9E-10 5.6E-10 6.3E-10 5.0E-10 5.5E-10 6.4E-10
150 m 5.5E-10 5.5E-10 5.5E-10 5.2E-10 5.9E-10 4.6E-10 5.2E-10 6.1E-10
Excavation A
10 m 1.2E-09 1.3E-09 1.6E-09 1.6E-09 1.8E-09 1.6E-09 1.2E-09 1.3E-09
20 m 1.2E-09 1.3E-09 1.4E-09 1.4E-09 1.5E-09 1.4E-09 1.2E-09 1.3E-09
30 m 9.9E-10 1.0E-09 1.1E-09 1.1E-09 1.2E-09 1.1E-09 9.9E-10 1.1E-09
40 m 8.4E-10 8.6E-10 9.3E-10 8.9E-10 1.0E-09 8.8E-10 8.3E-10 9.0E-10
50 m 7.3E-10 7.4E-10 7.9E-10 7.6E-10 8.6E-10 7.4E-10 7.1E-10 7.8E-10
60 m 6.4E-10 6.5E-10 6.9E-10 6.6E-10 7.5E-10 6.3E-10 6.2E-10 6.9E-10
70 m 5.7E-10 5.8E-10 6.1E-10 5.8E-10 6.6E-10 5.5E-10 5.5E-10 6.2E-10
80 m 5.2E-10 5.2E-10 5.4E-10 5.2E-10 5.9E-10 4.9E-10 5.0E-10 5.6E-10
90 m 4.7E-10 4.7E-10 4.9E-10 4.7E-10 5.4E-10 4.4E-10 4.5E-10 5.1E-10
100 m 4.3E-10 4.4E-10 4.5E-10 4.3E-10 4.9E-10 4.0E-10 4.1E-10 4.7E-10
110 m 4.0E-10 4.0E-10 4.1E-10 3.9E-10 4.5E-10 3.6E-10 3.8E-10 4.4E-10
120 m 3.8E-10 3.7E-10 3.8E-10 3.6E-10 4.1E-10 3.3E-10 3.5E-10 4.1E-10
130 m 3.5E-10 3.5E-10 3.5E-10 3.4E-10 3.8E-10 3.0E-10 3.3E-10 3.9E-10
140 m 3.3E-10 3.3E-10 3.3E-10 3.1E-10 3.6E-10 2.8E-10 3.1E-10 3.6E-10
150 m 3.1E-10 3.1E-10 3.1E-10 2.9E-10 3.3E-10 2.6E-10 2.9E-10 3.4E-10

1805956.000 - 5209 C-12
Table C-1. (cont.) ELCR estimates from DPM exposure due to trucking operations
associated with closure of the Allen Plant ash basin under CIP closure,
excavation closure, and hybrid closure. Results for each road orientation
and distances from both sides of the road (ELCR columns per orientation).
E-W Run NE-SW Run N-S Run NW-SE Run
Excavation B
10 m 9.5E-08 9.9E-08 1.2E-07 1.2E-07 1.4E-07 1.3E-07 9.7E-08 1.0E-07
20 m 9.5E-08 9.8E-08 1.1E-07 1.1E-07 1.2E-07 1.1E-07 9.5E-08 1.0E-07
30 m 7.7E-08 8.0E-08 8.8E-08 8.4E-08 9.5E-08 8.4E-08 7.7E-08 8.3E-08
40 m 6.5E-08 6.7E-08 7.2E-08 6.9E-08 7.9E-08 6.8E-08 6.5E-08 7.0E-08
50 m 5.7E-08 5.7E-08 6.1E-08 5.9E-08 6.7E-08 5.7E-08 5.5E-08 6.1E-08
60 m 5.0E-08 5.0E-08 5.3E-08 5.1E-08 5.8E-08 4.9E-08 4.9E-08 5.4E-08
70 m 4.4E-08 4.5E-08 4.7E-08 4.5E-08 5.2E-08 4.3E-08 4.3E-08 4.8E-08
80 m 4.0E-08 4.1E-08 4.2E-08 4.0E-08 4.6E-08 3.8E-08 3.9E-08 4.4E-08
90 m 3.7E-08 3.7E-08 3.8E-08 3.6E-08 4.2E-08 3.4E-08 3.5E-08 4.0E-08
100 m 3.4E-08 3.4E-08 3.5E-08 3.3E-08 3.8E-08 3.1E-08 3.2E-08 3.7E-08
110 m 3.1E-08 3.1E-08 3.2E-08 3.1E-08 3.5E-08 2.8E-08 3.0E-08 3.4E-08
120 m 2.9E-08 2.9E-08 3.0E-08 2.8E-08 3.2E-08 2.6E-08 2.8E-08 3.2E-08
130 m 2.7E-08 2.7E-08 2.8E-08 2.6E-08 3.0E-08 2.4E-08 2.6E-08 3.0E-08
140 m 2.6E-08 2.6E-08 2.6E-08 2.4E-08 2.8E-08 2.2E-08 2.4E-08 2.8E-08
150 m 2.4E-08 2.4E-08 2.4E-08 2.3E-08 2.6E-08 2.0E-08 2.3E-08 2.7E-08
Hybrid
10 m 1.6E-09 1.6E-09 2.0E-09 2.0E-09 2.2E-09 2.1E-09 1.6E-09 1.7E-09
20 m 1.6E-09 1.6E-09 1.8E-09 1.7E-09 2.0E-09 1.8E-09 1.6E-09 1.7E-09
30 m 1.3E-09 1.3E-09 1.4E-09 1.4E-09 1.6E-09 1.4E-09 1.3E-09 1.4E-09
40 m 1.1E-09 1.1E-09 1.2E-09 1.1E-09 1.3E-09 1.1E-09 1.1E-09 1.1E-09
50 m 9.3E-10 9.4E-10 1.0E-09 9.7E-10 1.1E-09 9.4E-10 9.1E-10 1.0E-09
60 m 8.2E-10 8.3E-10 8.8E-10 8.4E-10 9.6E-10 8.1E-10 8.0E-10 8.8E-10
70 m 7.3E-10 7.4E-10 7.7E-10 7.4E-10 8.5E-10 7.1E-10 7.1E-10 7.9E-10
80 m 6.6E-10 6.6E-10 6.9E-10 6.6E-10 7.6E-10 6.3E-10 6.4E-10 7.2E-10
90 m 6.0E-10 6.1E-10 6.3E-10 6.0E-10 6.9E-10 5.6E-10 5.8E-10 6.6E-10
100 m 5.5E-10 5.6E-10 5.7E-10 5.5E-10 6.3E-10 5.1E-10 5.3E-10 6.1E-10
110 m 5.1E-10 5.1E-10 5.3E-10 5.0E-10 5.7E-10 4.6E-10 4.9E-10 5.6E-10
120 m 4.8E-10 4.8E-10 4.9E-10 4.6E-10 5.3E-10 4.2E-10 4.5E-10 5.2E-10
130 m 4.5E-10 4.5E-10 4.5E-10 4.3E-10 4.9E-10 3.9E-10 4.2E-10 4.9E-10
140 m 4.2E-10 4.2E-10 4.2E-10 4.0E-10 4.5E-10 3.6E-10 3.9E-10 4.6E-10
150 m 4.0E-10 4.0E-10 4.0E-10 3.7E-10 4.2E-10 3.3E-10 3.7E-10 4.4E-10

1805956.000 - 5209 C-1
Model-estimated non-cancer risk
HI results for the four road orientations and both sides of the road are provided in Table C-2.
Table C-2. HI estimates from DPM exposure due to trucking operations associated
with closure of the Allen Plant ash basin under CIP closure, excavation
closure, and hybrid closure. Results for each road orientation and
distances from both sides of the road (HI columns per orientation).
E-W Run NE-SW Run N-S Run NW-SE Run
CIP
10 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
20 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
30 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
40 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
50 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
60 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
70 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
80 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
90 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
100 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
110 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
120 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
130 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
140 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
150 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
Excavation A
10 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
20 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
30 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
40 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
50 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
60 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
70 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
80 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
90 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
100 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
110 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
120 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
130 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
140 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
150 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

1805956.000 - 5209 C-2
Table C-2. (cont.) HI estimates from DPM exposure due to trucking operations
associated with closure of the BCSS ash basin under CIP closure,
excavation closure, and hybrid closure. Results for each road orientation
and distances from both sides of the road (HI columns per orientation).
E-W Run NE-SW Run N-S Run NW-SE Run
Excavation B
10 m 0.0003 0.0003 0.0003 0.0003 0.0004 0.0004 0.0003 0.0003
20 m 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003 0.0003
30 m 0.0002 0.0002 0.0002 0.0002 0.0003 0.0002 0.0002 0.0002
40 m 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002
50 m 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002 0.0002
60 m 0.0001 0.0001 0.0001 0.0001 0.0002 0.0001 0.0001 0.0002
70 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
80 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
90 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
100 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
110 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
120 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
130 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
140 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
150 m 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001
Hybrid
10 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
20 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
30 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
40 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
50 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
60 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
70 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
80 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
90 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
100 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
110 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
120 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
130 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
140 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000
150 m 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

Appendix D

Habitat Equivalency Analysis

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Habitat Equivalency Analysis
Habitat equivalency analysis (HEA) was used to estimate changes in environmental service
levels under different closure options for the Duke Energy Allen Steam Station (Allen). The
extent of environmental service flows currently provided by ash basin habitats (wooded areas,
open field, open water, etc.) and associated sites (borrow/landfill areas) were calculated and
compared to service flows provided by post-closure habitats in these areas.
The HEA proceeded in four steps:
1. Estimate habitat areas: The acres of different habitat types (e.g., forest,
open field, open water, wetland) that would be affected by closure under each
closure option (i.e., cap in place [CIP], excavation, and hybrid closures) were
estimated from aerial imagery.
2. Evaluate environmental service levels: The relative level of environmental
services provided by these habitats was estimated in terms of net primary
productivity (NPP).
3. Apply discounting for future services: The relative levels of environmental
services were calculated over time according to the construction
implementation schedule developed by Duke Energy (2018) and expressed in
units of discounted service acre-years (DSAYs).
4. Calculate discounted environmental services: DSAYs were summed
across the gains and losses of each habitat type to produce a net gain or loss
in environmental service levels for each closure option.
Estimate Habitat Areas
Acreages of current habitat types were calculated from geographic information system (GIS)
files provided by Duke Energy that included spatial representations of the current acreage of
open field, wetland, wooded area, and open water habitats surrounding the ash basin. The
acreages of ash basin to be closed and land converted to landfill or borrow pits were based on
information provided by Duke Energy (2018) according to the assumptions below. For the

1805956.000 - 5209 D-2
excavation and hybrid options, the closure-by-removal portions of the ash basin were assumed
to be restored to historical, pre-basin conditions. Historical acreage of forested, open field, and
stream habitat types were estimated by measuring aerial photographs from 1948 provided in the
comprehensive site assessment (CSA; SynTerra 2018a) using GIS. Unclassified current habitat
areas in the ash basin footprint were assumed to be bare ground and to have a 0% service value.
Historical habitat types were broadly classified into forest, open water, and open-unclassified
areas since not all currently measured habitat types (e.g., scrub-shrub) could be resolved from
historical images. Historical areas of forest sub-habitat types not resolved in the historical
imagery were estimated by assuming the current (non-basin) site-wide percentages of broadleaf
forest (50%), needleleaf forest (50%), and wetland forest (<1%) were applied to the historical
forest areas within the ash basin footprint. Historical areas of open-unclassified (as forest or
open water) habitat types were estimated by assuming the current site-wide percentages of
scrub-shrub (45%), emergent wetland (<1%), and open field (55%) applied to these areas within
the historical ash basin footprint. It is important to note that not all closure options impacted all
basin habitat areas, thus different closure options may be modeled in the HEA using different
total areas.
Additional assumptions used to calculate habitat areas included:
 Stream habitats in the ash basin were not indicated for Allen in historical
imagery and not included in the NPP services in ash basin restoration.
 Fill material for closure was assumed to be derived from excavation of basin
dam features and new onsite borrow pits. The areal extent of these borrow
pits was calculated from the volume (cubic yards) of required earthen fill
material, assuming borrow pits would be dug to 15 ft.
 Area lost to borrow pit excavation was assumed to contain forest habitat,
which is the predominant non-basin habitat type on the Allen property.
 Borrow material required for CIP closure of the Unit 5 basin was assumed to
not be available from closure activities in the active ash basin.

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Evaluate Environmental Services
NPP was used to standardize environmental services across habitat types. NPP is a measure of
how much photosynthesis occurs in an area greater than the amount required by the plants for
immediate respiration needs. Fundamentally, NPP is a measure of the energy available to
perform environmental services and is a useful currency for comparing habitats (Efroymson et
al. 2003). NPP is often referred to in terms of carbon fixation or carbon storage, as the removal
of carbon from the atmosphere is a primary reaction of photosynthesis.
Of the habitats currently occurring on the site, broadleaf, needleleaf, and mixed forested areas
have the highest NPP; that is, per acre of forest, photosynthesis fixes more carbon/produces
more energy for environmental services (Ricklefs 2008). As such, NPP service levels for all
habitat types were normalized to the NPP service level of forested habitat. Specifically, the
service levels for all habitat types were expressed as a proportion of the maximum wooded area
service level (He et al. 2012).
To compare results between the different closure options, a set of assumptions was used for all
options evaluated.
 Figure 22.12 from Ricklefs (2008) was used as the basis for determining
relative rates of NPP for different ecosystem types. For this evaluation,
temperate forest (woodland) was considered the base habitat with a relative
NPP of 100%. Other habitat types were normalized as a proportion of that
value based on the relative levels of NPP shown in Ricklefs’ Figure 22.12
(2008), using temperate grassland as representative of open fields and
freshwater environments as representative of open water.
 Based on Ricklefs’ Figure 22.12 (2008), NPP values for open field
and open water habitats were assumed to be 40% of the forest value.
However, because aquatic habitats of the ash basin may not be
functionally equivalent to naturally occurring freshwater ecosystems
(e.g., less abundant or diverse vegetation), a habitat quality

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adjustment factor of 4 was applied, lowering the relative NPP value
for ash basin open water habitat to 10% of temperate forest NPP.
 Figure 2c from He et al. (2012) was used to estimate NPP of woodland areas
based on stand age.
 The NPP functions for the three forest types (broadleaf, needleleaf,
mixed) from Figure 2c of He et al. (2012) were digitized to allow
calculation of NPP by stand age. For example, for mixed forests this
function shows rapidly increasing NPP up to a maximum at 45 years,
after which the NPP declines slightly to level off at approximately
85% of the maximum.
 All wooded areas currently occurring in the ash basin or on borrow or
landfill areas were assumed to be 50 years old, which, based on He et
al. (2012), provide approximately 97% of maximum NPP function in
the case of broadleaf and mixed forests and 84% for needleleaf
forests. Other habitats were normalized from the higher value using
the relative rates of NPP described above.
 Baseline levels of service (NPP) in the absence of closure activities were
assumed to continue at the current rate for 150 years, accounting for slight
changes in wooded area NPP by age as calculated from the NPP function of
He et al. (2012).
Apply Discounting for Future Services
HEA applies a discounting function when calculating the amount of environmental services
derived from an acre over a year and uses as its metric a discounted service acre-year, or DSAY.
Discounting is necessary because environmental services occurring in the future are assumed to
be less valuable to people than the same services performed now (Dunford et al. 2004;
Desvousges et al. 2018; Penn undated). This allows the environmental services occurring far in
the future to be considered on par with contemporary services. Thus, factors determining when

1805956.000 - 5209 D-5
closure and remediation begin and the duration of these processes are important parameters of
the final DSAY estimate.
I used the closure schedule provided by Duke Energy (2018) to develop timelines for habitat
loss and gain under each closure option. For purposes of the HEA, only site preparation,
construction, and site restoration times were included. Pre-design and design permitting periods
were assumed to have no effect on environmental services. The closure schedule estimated
duration of each activity in months; however, since the HEA model calculates DSAYs on an
annual basis, the activity durations were rounded up the nearest full year. This has a negligible
impact on DSAY estimates.
The following assumptions were then used to standardize timing of activities among the closure
options:
 For all closure options, removal of existing onsite habitats was assumed to
occur in the year that construction begins and was assumed to be completed
the same year such that no environmental service is provided by the end of
the first construction year.
 Environmental services of areas used for borrow or as landfill were assumed
to be lost in the year construction starts, and borrow/landfill site preparation
was assumed to be complete the same year such that no environmental
service is provided by the end of the first construction year.
 Environmental service gains from restoration (ash basin and borrow area)
were assumed to begin in the year following completion of construction
activities.
 Post-closure habitats were presumed eventually to provide the same level of
service as equivalent pre-closure habitats with the following conditions:
 Forests would be age 0 in the year when restoration was completed
and would generate an increasing level of NPP as they grow,

1805956.000 - 5209 D-6
following the rates calculated from the NPP curves of He et al.
(2012).
 Restored open field habitat would take five years (based on
professional judgement) to reach the baseline relative to forest NPP of
40%, with service levels increasing linearly over that time.
 Restored wetland and stream habitat would be functionally equivalent
to natural freshwater ecosystems and would provide an NPP relative
to forests of 40% after five years (based on professional judgement),
increasing linearly over that time.
 Periodic mowing is required to maintain a grass cap, so grass cap was
assumed never to reach a level of service equivalent to an open field.
Grass cap was assumed to have 20% of the NPP service level for open
field, which is 8% of forest NPP. Grass cap was assigned a post-
closure service level of 8%, with full service attained in 2 years.
 Bare ground was assumed to provide no environmental service.
 The base year for discounting is 2019 for all closure options.
 A discount rate of 3% is applied for all closure options.
 The HEA is run for 150 years for all closure options.
Calculate Discounted Environmental Services
Calculation of DSAYs is a summation of the discounted losses and gains in service values
across habitat types. The net DSAYs calculated for each closure option are reported in Table 10-
1 of the main body of this report.
A sensitivity analysis of key parameters (based on professional experience) and assumptions
used in the HEA was conducted to evaluate how sensitive the HEA results are to changes in (1)
the duration over which the services were evaluated (i.e., 150 years), (2) the assumed relative
NPP of ash basin open water and open fields, and (3) habitat created by restoration of borrow

1805956.000 - 5209 D-7
areas. The results are discussed in the context of uncertainty in the net environmental benefit
analysis (NEBA) in Appendix E.

Appendix E

Net Environmental Benefit
Analysis

1805956.000 - 5209 E-1
Net Environmental Benefit Analysis
Net environmental benefit analysis (NEBA) is a structured framework for comparing impacts
and benefits to environmental services to support decision-making (Efroymson et al. 2003,
2004). In the NEBA application for the Allen Steam Station (Allen) ash basin closure, a risk-
ranking approach, based on that described by Robberson (2006), was applied. The risk-ranking
approach develops alphanumerical estimates of relative risk by closure option and by attribute
(e.g., risk to a receptor, change in environmental services), which allows comparison of the
relative differences in impact between closure options to a variety of attributes. In this way,
tradeoffs can be visualized to inform decision-making.
Risk-Ranking Matrix
The risk-ranking matrix includes two axes that characterize risk. The y-axis shows the level of
impact, or risk, to an attribute, and the x-axis shows the duration of the impact (which is directly
related to the time to recovery). Both are important to evaluate the relative differences in risk
posed by closure options. A moderate level of impact over a long duration can potentially have
an overall greater negative impact on the environment than a higher impact over a very short
period (Robberson 2006). The pattern of shading of the risk matrix conveys this general
principle, though the exact shading of the cells is based on best professional judgement.
Robberson (2006) describes darker shading as indicating a higher level of concern over the level
of impact to a resource or environmental service. The NEBA matrix developed by the
Operational Science Advisory Team-2 (OSAT 2011) used a similar color coding approach to
compare risk from further cleanup of oil on beaches of the Gulf of Mexico following the
Deepwater Horizon oil spill. The risk-ranking matrix used in the NEBA of closure options for
the Allen ash basins is shown in Table E-1.

1805956.000 - 5209 E-2
Table E-1. Risk-ranking matrix for impacts and risk from closure activities. Darker
shading and higher codes indicate greater impact.

Duration of Impact (years)
16-25
(5)
10–15
(4)
5–9
(3)
1–4
(2)
<1
(1) % Impact No meaningful risk -- -- -- --
<5% (A) 5A 4A 3A 2A 1A
5–19% (B) 5B 4B 3B 2B 1B
20–39% (C) 5C 4C 3C 2C 1C
40–59% (D) 5D 4D 3D 2D 1D
60–79% (E) 5E 4E 3E 2E 1E
>80% (F) 5F 4F 3F 2F 1F
The percent impact levels (e.g., <5%, 5–19%) were defined based on best professional
judgement and regulatory precedent. A <5% impact characterizes a very minor potential or
expected impact that may be functionally indistinct from baseline conditions due to uncertainty
in metrics or the estimated effects. As such, this level of impact was given no shading,
regardless of the duration of impact. Impacts between 5–19% are considered low in the NEBA
framework (Efroymson et al. 2003). This impact level was shaded to reflect this low risk. Levels
of impact >20% were separated at intervals of 20% based on best professional judgement and
consistent with the risk-ranking approach used by Robberson (2006).
Similarly, the categories used to define duration of impact were based on best professional
judgment and regulatory precedent. Robberson (2006) defines recovery in <1 year as “rapid,”
with shading that indicates a generally low level of concern across the levels of impact. The
remaining time categories in the risk-ranking matrix were divided to separate relatively short
duration and time to recovery (e.g., 1–4 years, 5–9 years) from longer periods of time (e.g., 16–
25 years). Approximately five-year periods were used to divide duration categories up to 15
years; after 15 years, approximately 10-year periods were used. This reflects that smaller
differences in time are more important to distinguishing impacts from closure activities that last
for shorter periods; however, as impact duration increases differences in a few years are a
diminishing fraction of the total duration of the closure activities.
1805956.000 - 5209 E-3
As Robberson (2006) notes, the exact size of the risk matrix is a function of decisions made
about scaling the matrix, which is a function of the closure and remediation being considered
and the attributes included in the NEBA. The risk-ranking matrix applied here could have been
defined differently. For example, the duration of impact categories could have been expanded to
eight (e.g., <1 year, 1–3 years, 3–6 years, 6–9 years, 9–12 years, 12–15 years, 15–20 years, 20–
25 years), which would have changed the alphanumeric risk ratings and perhaps some of the
shading of attributes evaluated in the NEBA. The purpose of the risk matrix, and the risk ratings
that result from it, is to consolidate the results from a variety of different analyses for a variety
of different data types and attributes into a single framework for comparative analysis. It is
imperative, however, to consider the underlying information used to develop the risk ratings to
interpret the differences between closure options, particularly when percent impacts or durations
of closure options are similar but receive different risk ratings. It is inappropriate to assume a
risk rating for one attribute is scientifically equivalent to the risk rating of another attribute
because the comparative metrics that form the foundation of the risk ratings can be
fundamentally different (e.g., a hazard quotient for risk to a bird species is different from
discounted service acre-years [DSAYs] for environmental services from a habitat). Thus, the
risk ratings in the NEBA matrix permit a relative comparison of impacts between closure
options within attributes. Decision-makers can use the NEBA framework to identify the relative
impacts of closure options across many different attributes, but the NEBA matrix does not, by
design, elevate, or increase the value of, any specific risk or benefit in the framework.
Risk Rating Sensitivity
Uncertainty in a NEBA can be evaluated by examining the uncertainty in the assumptions and
analyses used as inputs to the risk-ranking matrix. The following sections examine how
differences in assumptions could affect relative risk ratings in the NEBA framework for
attributes found to have different levels of impact. Attributes for which no meaningful risk was
found (e.g., human health risk assessments, ecological health risk assessments) are not included
in the following discussion.
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Noise and congestion from trucking traffic
I used the number of trucks per day passing 1 a receptor along a near-site transportation corridor
as a metric to examine the differences in noise and traffic congestion under the closure options. I
compared the increase in truck passes due to hauling earthen fill, geosynthetic material, and
other materials under the closure options 2 to the current number of truck passes for the same
receptor.
The current (or baseline) number of truck passes was estimated from North Carolina
Department of Transportation (NCDOT) annual average daily traffic (AADT) data collected at
thousands of locations across the state and the proportion of road miles driven by large trucks in
North Carolina. AADT is an estimated daily traffic volume at a specific location, which
captures traffic in all lanes traveling in both directions and is assumed to represent typical traffic
volume for a year.3 Not all AADT data, however, differentiate between large trucks such as
those to be used in ash basin closure and other traffic such as cars, which is a relevant
distinction when considering impacts to communities from increased noise. NCDOT performs
vehicle classification 4 on trucking routes to estimate annualized truck percentage to apply to
AADT to determine truck AADT (NCDOT 2015). The average annualized truck percentage for
Gaston County is 5%.
The precise transportation corridor for trucks travelling to and from Allen during ash basin
closure is unknown; however, likely corridors in the communities local to Allen can be
identified by examining road maps and AADT statistics. Allen Station is located on NC 273 (S.

1 Truck passes per day resulting from trucking activities is calculated as the total number of loads required to
transport earthen fill, geosynthetic materials, and other materials multiplied by two to account for return trips.
The resulting total number of passes is then divided evenly among the total number of months of trucking time
multiplied by 26 working days per month.
2 Truck trips to haul ash were not included in the estimate for Allen ash basin closures because trucks hauling ash
would not leave the Allen property and would not affect community receptors along the transportation
corridors.
3 AADT is calculated from two days of traffic counts at each station during weekdays, excluding holidays. Raw
monitoring data consists of counts of axle pairs made by pneumatic tube counters that are converted to traffic
volume by applying axle correction factors and expanded to annual estimates by seasonal correction factors.
Derived AADT values are checked for quality against nearby stations and historical station-specific values
(NCDOT 2015).
4 Vehicle classification is assigned based on number of axles, space between axles, weight of the first axle, and
total weight of the vehicle.
1805956.000 - 5209 E-5
Point Rd) on a peninsula of Lake Wylie. NCDOT Station ID 3500688 near the intersection with
the main plant road reported 8,300 AADT in 2016 (Figure E-1). Due to weight limit restrictions
on the bridge immediately north of the plant on NC 271, trucks hauling construction materials
must enter and exit the plant to/from the south on NC 273. This route passes through a lakeside
residential community before crossing the South Fork of the Catawba River arm of Lake Wylie.
In this community, NCDOT Station ID 3502009 reported 6,000 AADT on NC 273 in 2016.
Nearby, South Point Rd intersects NC 273 and serves residential areas at the tip of the
peninsula. NCDOT Station ID 3501559 on this road reported 2,100 AADT in 2016. After
crossing Lake Wylie, NC 273 intersects NC 279 and continues south toward South Carolina,
passing NCDOT Station ID 3502010, which reported 7,700 AADT in 2016. Northward on
NC279, NCDOT Station ID 3500687 reported 3,200 AADT in 2016. State road (SR) 2523
(Dixon Rd) connects US 279 to lakeside residences where Station ID 3501560 reported 1,600
AADT in 2016. While this 1,600 AADT value on Dixon Rd is the lowest AADT in vicinity of
the assumed transportation corridor, it is very unlikely trucks would use this side street. To best
capture trucking related impacts to sensitive communities along this transportation corridor, I
assumed a baseline truck passes per day of 110, which was computed by multiplying 2,100
AADT (2016 estimate from South Point Rd NCDOT Station ID 3501559) by the average
percent of truck AADT for Gaston county (5%; NCDOT 2015).5 The South Point Rd station
appears to best represent a sensitive AADT value within the residential community immediately
adjacent to Allen, which could also be used to haul material to or from the southern end of the
ash basin.

5 AADT data are not available for every road or every location along a road. It is possible during closure of the
Allen ash basins that trucks will utilize less traveled roads (i.e., with lower AADT), which would have a lower
baseline truck passes per day estimate and result in a higher percent impact from ash basin closure for these
sensitive communities; however, by choosing the lowest AADT in the vicinity of Allen proximate to the most
likely transportation corridors to and from Allen to a major road (e.g., highway), my analyses have considered
sensitive communities that would be more affected by traffic noise and congestion from ash basin closure
trucking.
1805956.000 - 5209 E-6

Figure E-1. NCDOT annual average daily traffic (AADT) measurement stations near Allen
Station. Traffic stations and AADT values considered when determining the
baseline number of truck passes are indicated as squares.
The sensitivity of the NEBA relative risk ratings to the baseline assumption of 110 trucks per
day was evaluated by calculating relative risk ratings for a range of baseline truck traffic levels,
based on the minimum and maximum AADT values for any NCDOT station within a 50-mile
radius of the Allen Station ash basins, using AADT from the most recent year that data are
available for a particular station, and assuming 5% truck traffic as previously described. Figure
E-2 plots the resulting percent impact for closure options along with the resulting relative risk
rating across the range of 1 to 9,555 truck passes per day.
1805956.000 - 5209 E-7

Figure E-2. Sensitivity of NEBA relative risk rating for noise and congestion impacts from
trucking operations. The vertical line indicates the assumed baseline 110 truck
passes per day. The y-axis is plotted on a log10 scale and the X axis is
truncated at 500 to improve visualization.
Using a baseline truck passes per day of 110, the excavation closure options range from the
lowest risk (A, <5% impact, Excavation A) to the highest risk (F, >80% impact, Excavation B).
The CIP and hybrid closure options both fall into the second lowest relative risk rating (B, 5–
19%) for traffic-induced noise and congestion during closure of the Allen ash basins (Figure E-
2). The assigned relative risk rating for Excavation B could be reduced to the next lower rating
(E) if the baseline traffic assumption is increased to about 410 truck passes per day. The risk
rating for Excavation A is very close to the next highest risk rating (B) and would be increased
to the next highest level (B) by a small decrease in the baseline truck passes from 110 to 101
passes. For the CIP closure option, the baseline truck volume could be approximately halved or
doubled without altering the risk rating. The hybrid option is insensitive to baseline changes of
about 65 fewer trucks per day, or increases of up to 70 additional truck passes per day.
1805956.000 - 5209 E-8
Traffic accidents
I evaluated risk of traffic accidents by comparing the average number of annual offsite road
miles driven between closure options relative to a baseline estimate of the current annual road
miles driven.6 I chose a baseline of 120 million annual truck road miles based on the reported
total vehicle miles traveled in Gaston County, North Carolina (NCDOT 2017), multiplied by the
county average 5% contribution of trucks to total AADT (NCDOT 2015).
The sensitivity of the NEBA relative risk ratings to the baseline assumption of 120 million truck
miles per year was evaluated by calculating relative risk ratings for alternative baseline truck
mile assumptions derived from the counties in North Carolina with the minimum (Hyde County)
and maximum (Mecklenburg County) reported vehicle miles driven, resulting in a sensitivity
range estimated from 6.2 million to 641 million truck miles per year. Figure E-3 plots the
resulting percent impact for the closure options, along with the resulting relative risk ratings
across this range of truck miles per year.

6 The difference between the baseline miles assumption and the closure assumption was divided by the baseline
miles assumption and multiplied by 100 to get a percent impact.
1805956.000 - 5209 E-9

Figure E-3. Sensitivity of NEBA relative risk rating for traffic accidents due to trucking
activities. The vertical line indicates the assumed baseline 60.4 million truck
miles per year. The y-axis is plotted on a log10 scale to improve visualization.
Using the 120-million-truck-miles baseline assumption, all closure options have an impact of
4% or less and a relative risk rating of A (<5%). The vertical lines in Figure E-3 indicate the
location of the baseline assumption. The relative risk ratings for the CIP, hybrid, and Excavation
A closure options do not appear to be sensitive to lower assumed baseline annual truck miles. At
the minimum statewide trucking values (6.2 million truck miles in Hyde County), risk remains
rated A for these options. A baseline reduction of about 20 million truck miles (to 101 million)
would increase the Excavation B risk rating to a B.
Habitat Equivalency Analysis
Uncertainty in the habitat equivalency analysis (HEA) that examined disruption of
environmental services from ash basin closure was explored through sensitivity analyses of key
assumptions in the HEA. To test sensitivity, I re-ran HEA models with the following changes:
1. Running the HEA for 100 years instead of 150 years.
1805956.000 - 5209 E-10
2. Assuming the open water habitats of the ash ponds provide environmental
services at 40% of wooded areas instead of 10%.
3. Assuming open field habitats provide environmental services at 20% of
wooded areas instead of 40%.
4. Assuming borrow area under the CIP option is restored to open field, not
reforested.
For each sensitivity analysis, all parameters in the base model were held constant except the one
parameter varied to understand the sensitivity of the model to each assumption (Table E-2).
Table E-2. Change in DSAYs from base modela for key HEA assumptions
Closure Option 100-year
modelb
Ash basin
water 40%c
Borrow
becomes fieldd
Open Field
20%e
CIP 91 −418 −399 80
Excavation A −51 −410 0 213
Excavation B −5 −435 0 168
Hybrid 5 −459 0 174
a Base models were run for 150 years with ash basin open water NPP services at 10%, borrow fields
were assumed to become forest (CIP) or grass cap (excavation to onsite and offsite landfill options),
and open field NPP services at 40%.
b Base models except the HEA was run for 100 years.
c Base models except ash basin open water NPP service at 40%.
d Base models except borrow pits were assumed to become open field for CIP option.
e Base models except open field NPP services decreased to 20%.
Running HEAs for 100 years increased net DSAYs slightly for the CIP and hybrid options and
decreased net DSAYs slightly for the other closure options. Increasing the ash basin open water
service level to 40% resulted in approximately similar net negative DSAYs for all options, the
differences among options being due to different start years for remedial activities. The same
rationale explains the increase in net DSAYs for all options under the assumption that existing
open field habitat only provides a 20% service level. Assuming borrow areas would be returned
to open field resulted in a decrease in net DSAYs for the CIP closure option. There are no
borrow areas that will be reforested under the other closure options so there is no net change in
DSAYs for those options.
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Looking at the change in net DSAYs between the sensitivity models and their base models, the
changes in assumptions have relatively consistent effects on net DSAYs. For example, changing
ash basin open water services from 10 to 40% affects all closure options similarly. Assuming
open field services at 20% results in a small net benefit since the level of service lost from open
fields currently present on both basins is halved. Changing the service level of borrow acreage
habitat after borrow is complete only affects closure options that assume the borrow area will be
restored to forested habitat (CIP). However, since the directionality of net NPP services
provided by the closure options does not change under this sensitivity analysis (i.e., all options
still result in a net loss of NPP services), this demonstrates that the model can differentiate
between relative differences in NPP service level changes with consistency.
Changes in net DSAYs with changing assumptions may change the relative risk rating applied
to a closure option in the NEBA. However, the relative similarity in the way DSAYs change
with assumptions between the various closure options and the results that all options produce
net losses in NPP services—but with hybrid closure and excavation to an onsite landfill closure
resulting in the smallest net NPP service losses—under any sensitivity analysis supports the
relative risk ratings for decision support in the NEBA.
Closure Option Assumptions
The following assumptions were used to calculate NEBA input values related to trucking
activities and habitat acreages.
• The density of ash was assumed to be 1.2 ash tons/CY.
• Borrow pit acreage required to supply earthen fill and cover material was
assumed to be dug to a depth of 15 ft to meet volume requirements. Borrow
pits not specifically identified were assumed to contain a mixed forest habitat
that would be restored upon closure completion.
• Excavation was assumed to proceed at a rate of 1,000,000 CY/year for all
types of excavation material combined including ash, underlying over-
excavated or residual soil, and dam and embankment material.
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• CIP cover systems were assumed to require two layers of geosynthetic
material. New landfill areas were assumed to require five layers of
geosynthetic material. Geosynthetic material was assumed to be transported
from Georgetown, South Carolina, at a rate of six loads per day and 3 acres
per load.
• Covers/caps for both CIP and landfills were assumed to receive 18 in. of
cover soil plus 6 in. of topsoil. New landfills also were assumed to receive 2
ft of liner soil. Topsoil was assumed to come from an offsite commercial
facility requiring no additional borrow area.
• Unless otherwise specified, offsite borrow material and topsoil were assumed
to be from sources 11 miles away (one way).
• Offsite truck capacity was assumed to be 20 CY of ash or earthen material.
• Working hours were assumed to be 10 hr/day, 6 days/week, and 26
days/month.
• Earthen fill material was assumed to be hauled in at a rate based on 1,000,000
CY/year.
• In excavated areas, 1 ft of over-excavation of residual soil was assumed.
When restoring these areas, 6 in. of top soil addition was assumed necessary
to establish vegetative stabilization over the total area.