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HomeMy WebLinkAboutRoxboro_NEBA_REVISED_CommunityImpactAnalysis_20190115Updated Community Impact Analysis of Ash Basin Closure Options at the Roxboro Steam Electric Plant Exponent Updated Community Impact Analysis of Ash Basin Closure Options at the Roxboro Steam Electric Plant Prepared on behalf of Duke Energy Progress, LLC Prepared by Dr. Ann Michelle Morrison Exponent 1 Mill & Main Place, Suite 150 Maynard, MA 01754 January 14, 2019 © Exponent, Inc. 1707466.000 - 3651 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 Material 4 4 Introduction 5 4.1 Site Setting 6 4.2 Closure of the Ash Impoundments at the Roxboro Plant 11 5 Approach to Forming Conclusions 17 5.1 Net Environmental Benefit Analysis 19 5.2 Linking Stakeholder Concerns to NEBA 21 5.3 NEBA Risk Ratings 27 5.4 Risk Acceptability 28 6 Summary of Conclusions 30 7 Conclusion 1: All closure options for the Roxboro ash basins are protective of human health. 32 7.1 Private water supply wells pose no meaningful risk to the community around the Roxboro Plant. 32 7.2 CCR constituents from the Roxboro ash basins pose no meaningful risk to human populations. 33 7.3 NEBA — Protection of Human Health from CCR exposure 35 1707466.000 - 3651 11 8 Conclusion 2: All closure options for the Roxboro ash basins are protective of ecological health. 37 8.1 No meaningful risks to ecological receptors from CCR exposure exist under current conditions or any closure option. 37 8.2 NEBA — Protection of Ecological Health from CCR Exposure 42 9 Conclusion 3: Excavation closure to an offsite landfill creates greater disturbance to local communities. 44 9.1 There is no meaningful risk from diesel emissions to people living and working along the transportation corridor. 48 9.2 The likelihood of noise, traffic, and accidents from transportation activities is greater under excavation closure to an offsite landfill. 51 9.2.1 Noise and Congestion 53 9.2.2 Traffic Accidents 53 9.3 NEBA — Minimize Human Disturbance 54 10 Conclusion 4: Most closure options for the Roxboro ash basins produce a net loss of habitat -derived environmental services. 59 10.1 Excavation closures result in greater net losses of environmental services than other closure options. 61 10.2 NEBA — Minimize Local Environmental Disturbance 66 11 Conclusion 5: CIP or hybrid closure of the EAB and hybrid closure of the WAB maximize local environmental services. 68 12 References 71 Appendix A Curriculum vitae of Dr. Ann Michelle Morrison, Sc.D. Appendix B Human Health and Ecological Risk Assessment Summary Update for Roxboro Steam Electric Plant Appendix C Exposure Modeling and Human Health Risk Assessment for Diesel Emissions Appendix D Habitat Equivalency Analysis Appendix E Net Environmental Benefit Analysis 1707466.000 - 3651 111 List of Figures Figure 4-1. Map of the Roxboro Plant. Page 8 Figure 4-2. Photos from the EAB at the Roxboro Plant, October 30, 2017. 9 Figure 4-3. Photos from the WAB at the Roxboro Plant, October 30, 2017. 10 Figure 4-4. Elemental composition of bottom ash, fly ash, shale, and volcanic ash. 12 Figure 8-1. Exposure areas evaluated in the 2018 ERA update (SynTerra 2018) 41 Figure 9-1. Normalized differences between all offsite transportation activities under CIP, excavation, and hybrid options. 47 Figure 9-2. Map of proposed transportation route between Duke Energy's Roxboro Plant ash basins and the landfill at the Mayo Plant (reproduced from Duke Energy 2018a). 52 Figure 10-1. Map of habitat types currently present at the Roxboro Plant 60 1707466.000 - 3651 1V List of Tables Page Table 4-1. Ash basin closure options provided by Duke Energy (2018a,b) 14 Table 4-2. Overview of some key logistical differences among closure options for the Roxboro Plant ash basin. 15 Table 5-1. Relationships between environmental services and concerns to the local community associated with CCR and ash basin closure hazards 23 Table 5-2. Associations between objectives for closure and remediation of the Roxboro ash basins and environmental services 24 Table 5-3. Matrix of key environmental services, attributes, and comparative metrics applied in the NEBA 25 Table 5-4. Risk -ranking matrix for impacts and risk from remediation and closure activities 28 Table 7-1. Summary of human health risk assessment hazard index (HI) and excess lifetime cancer risk (ELCR) from SynTerra (2016c) 35 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 36 Table 8-1. Summary of relative risk rating for attributes that characterize potential hazards to ecological resources from CCR exposure in surface water, soil, sediment, and food 42 Table 9-1. Summary of transportation logistics associated with combinations of Roxboro EAB and WAB closure options (Duke Energy 2018a, 2018b, 2019) 46 Table 9-2. Hazard indices (HI) and excess lifetime cancer risk (ELCR) from exposure to diesel exhaust emissions along transportation corridors in northern North Carolina. 50 Table 9-3. Comparative metrics for increased noise and congestion and traffic accidents 54 Table 9-4. Summary of relative risk ratings for attributes that characterize potential hazards to communities during closure activities. 57 Table 10-1. Summary of NPP DSAYs for CIP and excavation closure options 65 Table 10-2. Percent impact of ash basin closure options 66 Table 10-3. Summary of relative risk ratings for habitat changes that affect protection of biodiversity and natural beauty. 67 1707466.000 - 3651 v Table 11-1. NEBA for closure of the ash basins at the Roxboro Plant. 70 1707466.000 - 3651 Vl Acronyms and Abbreviations AADT annual average daily traffic AOW area of wetness ASOS Automated Surface Observing System 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 Progress, LLC DSAY discounted service acre -year EAB East Ash Basin ELCR excess lifetime cancer risk EPA U.S. Environmental Protection Agency EPC exposure point concentration ERA ecological risk assessment FGD flue -gas desulfurization GIS geographic information system HEA habitat equivalency analysis HHRA human health risk assessment HI hazard index HQ hazard quotient IMAC interim maximum allowable concentration LOAEL lowest -observed -adverse -effects level MOVES Mobile Vehicle Emissions Simulator NCDEQ North Carolina Department of Environmental Quality NCDOT North Carolina Department of Transportation NEBA net environmental benefit analysis 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 RCRA Resource Conservation and Recovery Act REL reference exposure level Roxboro Plant Roxboro Steam Electric Plant 1707466.000 - 3651 Vll SOC Special Order by Consent TDS total dissolved solids TRV toxicity references value TVA Tennessee Valley Authority WAB West Ash Basin 1707466.000 - 3651 Vlll Limitations This 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 Progress, 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. As an example, some of the excavation options presented in this report assume that landfilling of excavated ash can be accommodated within the boundaries of the currently permitted landfill space at Duke Energy's Mayo Steam Electric Plant (Mayo Plant).' The currently permitted landfill space at the Mayo Plant was sized to accommodate future ash production and did not include the addition of excavated ash from the Roxboro Steam Electric Plant (Roxboro Plant) ash basins. If additional landfill space is required to accommodate both excavated ash and future ash production, then additional habitat destruction would be necessary, and that impact has not been factored into this analysis. ' The Mayo Plant is located approximately 11 miles, 15 miles by road, from the Roxboro Plant and approximately 10 miles northeast of the town of Roxboro, North Carolina. 1707466.000 - 3651 1X Executive Summary' 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 Progress, LLC's (Duke Energy's) Roxboro Plant has two onsite ash basins. The East Ash Basin (EAB) began operation in the mid- 1960s, and the West Ash Basin (WAB) was constructed in the early 1970s. In the late 1980s, an unlined landfill was constructed on top of the EAB for placement of dry ash, and a lined landfill was constructed on top of the unlined landfill around 2004 (SynTerra 2015a). Duke Energy has evaluated three representative types of closure for each of the two ash basins at the Roxboro Plant—CIP, excavation to either onsite landfills or an offsite landfill at Duke Energy's Mayo Plant, and hybrid closure —the latter of which involves excavating and 2 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. 1707466.000 - 3651 x consolidating ash within the basin footprint to reduce the spatial area of CIP closure. The hybrid option for the EAB includes transport of the excavated portion of the ash basin to the Mayo Plant landfill(s) rather than consolidation within the EAB footprint. I have evaluated every combination of the CIP, excavation to an offsite landfill, and hybrid closure options for each basin as well as an additional option for excavation closure of both basins to onsite landfills, for a total of ten closure options. 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 services3 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 closure, or a hybrid CIP and excavation closure of the ash basins at the Roxboro Plant. The NEBA framework relies on scientifically supported estimates of risk to compare the reduction of risk associated with the chemicals of potential concern (COPCs)4 under different remediation and closure alternatives alongside the creation of any risk during remediation and closure, providing an objective, scientifically structured foundation for weighing the tradeoffs between remedial and closure alternatives. s Environmental services, or ecosystem services, are ecological processes and functions that provide value to individuals or society (Efroymson et al. 2003, 2004). a 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" (hlWs:Hofinpub.epa. og v/sor_internet/regi, stry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?de tails=&glossgryName=Eco%20Risk%2OAssessment%20G10 ssaa). 1707466.000 - 3651 Xl 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 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 environmental 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 that 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 1707466.000 - 3651 Xll provided a side -by -side comparison of the impacts of a "no action," "closure -in -place," and "closure -by -removal" action. 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 environmental impact, shorter schedules, and less cost" (TVA 2016). The Roxboro ash basin closure 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 the Roxboro Plant, I reviewed written communications submitted to and summarized by the North Carolina Department of Environmental Quality (NCDEQ) related to ash basin closure plans for the Roxboro Plant (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 1707466.000 - 3651 Xlll (e.g., fishing, swimming), and protection of natural beauty and biodiversity.5 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 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. s 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. 1707466.000 - 3651 X1V 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 Safe surface Safe air Safe food Protection of Recreation Natural Safe community water quality water quality quality quality biodiversity beauty environment CCR Concerns Drinking water X X X contamination Groundwater X X X contamination Surface water X X X X X X X contamination Fish/wildlife X X X X X contamination Contamination impacting X X X X X X X property value Contamination impacting X X X natural beauty Contamination impacting X X X X X recreational enjoyment Contamination impacting X X X X swimming safety Failure of the ash X X X X X X X impoundment Closure Hazards Habitat loss X X X X X Contamination of air X X X X Noise, Traffic, Accidents X X 1707466.000 - 3651 Xv 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 in this matter 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 metrics6 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 net primary productivity (NPP)7 and discounted service acre -years (DSAYs)8 to characterize 6 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 to birds, acreage of habitat) that can be measured and compared between closure options. 7 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:Hearthobservatory.nasa.gov/GlobalMUs/view.php?d1=MOD17A2_M PSN). 1707466.000 - 3651 XVl 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. 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 Amec Foster Wheeler Environment & Infrastructure, Inc. and submitted to NCDEQ indicates "the construction, design, operation, and maintenance of the CCR surface impoundments have been consistent with recognized and generally accepted engineering standards for protection of public safety and the environment" (Williams and Tice 2018). Ten possible closure options were identified by Duke Energy (2018a,b) for closure of the ash basins at the Roxboro Plant and are 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. 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 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). 1707466.000 - 3651 XVll Table ES-2. Ash basin closure options provided by Duke Energy (2018a,b) Closure Option EAB WAB Closure Construction (EAB/WAB) Duration Duration (years)a.b (years)b,° CIP/CIP CIP CIP 7 5 CIP/Excavation Offsite CIP Excavate to Mayo landfill 16 14 CIP/Hybrid CIP Partially excavate to 9 7 consolidate ash and CIP consolidated ash Excavation Offsite/CIP Excavate to Mayo landfill CIP 7 5 Excavation Offsite/ Excavate to Mayo landfill Excavate to Mayo landfill 16 14 Excavation Offsite Excavation Excavate to Mayo landfill Partially excavate to 9 7 Offsite/Hybrid consolidate ash and CIP consolidated ash Hybrid/CIP Partially excavate to Mayo CIP 7 5 landfill and CIP consolidated ash Hybrid/Excavation Partially excavate to Mayo Excavate to Mayo landfill 16 14 Offsite landfill and CIP consolidated ash Hybrid/Hybrid Partially excavate to Mayo Partially excavate to 9 7 landfill and CIP consolidate ash and CIP consolidated ash consolidated ash Excavation Onsite/ Excavate to new onsite Excavate to new onsite 20 17 Excavation Onsite landfill landfill a Includes pre -design investigation, design and permitting, site preparation, construction, and site restoration. b Duration estimates assume simultaneous closure of the EAB and WAB. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer. ° 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 1707466.000 - 3651 XVlll magnitude of the effect according to the extent and duration of an impact.9 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. Table ES-3. Risk -ranking matrix for impacts and risk from closure activities. Darker shading/higher codes indicate greater impact. Duration of Impact (years) 16-25 10-15 (5) (4) 5-9 (3) 1-4 (2) <1 (1) No meaningful risk -- -- -- -- <5% (A) 5A 4A 3A 2A 1A 5-19% (B) 5B 4B 3B 2B 1 B 20-39% (C) I 5C 4C 3C 2C 1C 40-59% (D) I 3D 2D 1 D E 60-79% (E) 2E 1E 80-99% (F) 1F 0 100-149% (G) 150-199% (H) 200-299% (1) 300-399% (J) 400-499% (K) >500% (L) NEBA analysis of possible closure options for the ash basin at the Roxboro Plant 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 local environmental services, closure plans for that option can be re-examined, and opportunities to better maximize environmental benefits can be identified (e.g., including offsite habitat 9 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. 1707466.000 - 3651 X1X mitigation 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 Roxboro 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: 1. Provision of alternative permanent drinking water supplies to private well water supply users within a 0.5-mile radius of the Roxboro ash basin compliance boundary (Holman 2018); 2. Concentrations of CCR constituents of interest (COIs) in drinking water wells that could potentially affect local residents and visitors, as characterized by SynTerra (2015a, 2016b, 2017) 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 (2018; Appendix B). 1707466.000 - 3651 xx 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 Table ES-4 within the objective of protecting human health from exposure to CCR constituents. 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 the Roxboro Plant 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 August 15, 2018 (EMC SOC WQ S18-005; 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 S 18-005). 1707466.000 - 3651 XXl 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 c O L L N Y 7 C O L N O IL > U) C: °r Q U) O U N >, c U fC U O = J � m a� 0 O IL Scenario (EAB/WAB) Baseline -- -- -- C I P/C I P -- -- -- CIP/Excavation Offsite -- -- -- CIP/Hybrid -- -- -- Excavation Offsite/CIP -- -- -- Excavation Offsite/Excavation Offsite -- -- -- Excavation Offsite/Hybrid -- -- -- Hybrid/CIP -- -- -- Hybrid/Excavation Offsite -- -- -- Hybrid/Hybrid -- -- -- Excavation Onsite/Excavation Onsite -- -- -- --" 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. 1707466.000 - 3651 XXll Conclusion 2: All closure options for the Roxboro 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: 1. Risk to ecological receptors from CCR exposure, as characterized by SynTerra (2018; Appendix B) in the baseline human health and ecological risk assessment; and 2. Aquatic community health in Hyco Lake as reported in the 2016 environmental monitoring report (Duke Energy 2017). Based on these analyses, no evidence of impacts to ecological receptors from CCR exposure was identified under current conditions11 or under any closure option, and Hyco Lake 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. 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 the Roxboro Plant 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 August 15, 2018 (EMC SOC WQ S 18-005; 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 518-005). 1707466.000 - 3651 XXlll 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 N L O N _ Y N X O M - (n E > Q E _ Q. (� E } M�' L a L Li VI (6 �, a o a cn E E E E m a) v� E N E M y U o m m a) M o m a N p Q 0- > E O O 'E L a) L E O % O _ Q ii p i L ca U i L U L = U Li < D =3 = a) L Q Q QLi LL� M MM === • • i M I - ��� 111111110iiIII����� Hybrid/Excavation Offsite -- II I waLGJ IIV I I I GQ I I I I K�. I U 1110N Conclusion 3: Excavation closure to an offsite landfill creates greater disturbance to local 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: 1707466.000 - 3651 XX1V 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 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 the closure options, but all closure options are expected to produce different levels of community disturbance in the form of noise, 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 options to the current number of truck passes for the same receptor. I specified a baseline level of truck passes13 on the transportation corridor under current conditions of 52 passes per day. Based on the assumed 52-truck-passes-per-day baseline level and the number of truck trips per day from Duke Energy's projections (Table ES-6), all but one closure option had greater than 100% impact. The lowest percent impact from noise and traffic congestion resulted from excavation closure of both basins to new onsite landfills (Excavation Onsite/Excavation Onsite), with a 65% impact resulting from an average of 34 additional truck passes per day. The highest percent impact from noise and traffic congestion was 770% for excavation closure of both ash basins to an offsite landfill, resulting from 400 additional truck passes per day on average. I input the percent impacts for these and all other 12 Truck passes per day are calculated as the total number of loads required to transport ash (offsite excavation closures), earthen fill, and geosynthetic 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 construction time multiplied by 26 working days per month. 13 A baseline estimate of trucking passes per day for transportation corridors near the Roxboro Plant 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). 1707466.000 - 3651 xxv closure options (CIP/Hybrid = I I I%, Hybrid/Hybrid = 134%, and CIP/CIP 151%, Hybrid/CIP = 187%, Excavation Offsite/Hybrid = 380%, Excavation Offsite/CIP = 578%, CIP/Excavation Offsite = 632%, Hybrid/Excavation Offsite = 643%) into the risk -ranking matrix (Table ES-3) along with the total duration of trucking activities (Table ES-2) to evaluate which of the closure options best minimizes human disturbances. Table ES-6. Comparative metrics for increased noise and congestion and traffic accidents Noise and congestion Traffic Accidents Closure Option p Months of Average Total offsite (EAB/WAB) trucking a truck asses p Ratio to road miles Ratio to per day CIP/CIP driven CIP/CIP CIP/CIP 54 79 1.0 1,756,324 1.0 CIP/Excavation Offsite 168 328 4.2 21,582,158 12.3 CIP/Hybrid 86 58 0.7 1,990,576 1.1 Excavation Offsite/CIP 54 301 3.8 6,477,739 3.7 Excavation Offsite/Excavation Offsite 168 401 5.1 26,303,573 15.0 Excavation Offsite/Hybrid 86 198 2.5 6,711,991 3.8 Hybrid/CIP 54 97 1.2 2,155,104 1.2 Hybrid/Excavation Offsite 168 335 4.3 21,980,938 12.5 Hybrid/Hybrid 86 70 0.9 2,389,356 1.4 Excavation Onsite/Excavation Onsite 202 34 0.43 2,812,545 1.6 a Duration estimates assume simultaneous closure of the EAB and WAB. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer. I 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 Person County, North Carolina. I specified a current, or baseline, level of annual road miles driven in Person County of 33.5 million miles,14 and the road miles driven under the closure options are from the trucking projections provided by Duke Energy (2018a,b). Using the 33.5- in baseline assumption, all but one closure option has less than a 5%impact. The CIP/Hybrid, Hybrid/Hybrid, and CIP/CIP options had 0.83, 0.99, and 1.2% impacts, 14 To estimate the number of baseline truck miles, I multiplied the number of total vehicle miles traveled in Person County (NCDMV 2017) by the Person County average 9.5% contribution of trucks to total AADT (NCDOT 2015). 1707466.000 - 3651 XXVl respectively. The Hybrid/CIP option had a 1.4% impact. Excavation Onsite/Excavation Onsite had a 0.5% impact, and all options that include an offsite excavation closure had a percent impact greater than 2% (Excavation Offsite/Hybrid = 2.8%, Excavation Offsite/CIP = 4.3%, CIP/Excavation Offsite = 4.6%, Hybrid/Excavation Offsite = 4.7%, and Excavation Offsite/Excavation Offsite = 5.6%). 1707466.000 - 3651 XXVIl Table ES-7 summarizes the NEBA relative risk ratings based on the trucking projections and implementation schedules provided by Duke Energy (2018a,b) for the objective of minimizing disturbance to humans during closure. All closure options create disturbance and risk to human populations; however, the magnitude and duration of impacts to the community are substantially greater under closure options that include offsite excavation of one or both ash basins. All closure options support safe air quality from additional 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 offsite excavation closures. Excavation of both the EAB and WAB to onsite landfills produces the lowest daily and annual impacts compared to other closure options, but this closure option also affects the community for longest duration (almost 17 years). CIP and hybrid closure options produce slightly higher daily disturbance to the community from truck passes and similar and negligibly low increased annual risk from traffic accidents compared to excavation closure to onsite landfills; however, CIP and hybrid closures require a substantially shorter duration (4.5 years for CIP and just over 7 years for hybrid closures) and may better satisfy the third objective of ash basin closure —to minimize risk and disturbance to humans from closure —depending on stakeholder preferences.15 15 If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 - 3651 XXVIll Table ES-7. Summary of relative risk ratings for attributes that characterize potential hazards to communities during closure activities. Darker shading and higher alphanumeric codes indicate greater impact. Objective Minimize Human Disturbance Noise and Traffic Hazard Traffic Air Pollution Congestion Accidents N C � O r L L U) Q Q X O w a > > E V c =3 E a> c m m Q a, — Ca cO R U O U O rZ O = J J N O a Scenario (EAB/WAB) Baseline baseline baseline baseline CIP/CIP 3A -- CIP/Excavation Offsite 4A -- CIP/Hybrid 3A -- Excavation Offsite/CIP 3A -- Excavation Offsite/Excavation Offsite I4B -- Excavation Offsite/Hybrid 3A -- Hybrid/CIP 3A -- Hybrid/Excavation Offsite 4A -- Hybrid/Hybrid 3A -- Excavation Onsite/Excavation Onsite 5A -- --" indicates "no meaningful risk." Conclusion 4: Most closure options for the Roxboro ash basins produce a net loss of habitat -derived environmental services. 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 based on differences in the NPP of impacted habitats under alternative closure options, as estimated by the number of DSAYs calculated by a habitat equivalency analysis (HEA). 1707466.000 - 3651 XX1X The results of the HEA indicate that closure of the WAB is the most important determinant of the net habitat -derived environmental services resulting from closure. Seven closure options will result in a net loss of environmental services, while the three closure options that include hybrid closure of the WAB produce a net gain in environmental services as indicated by a positive DSAY total. Net losses of environmental services are due primarily to loss of forest habitat for borrow and landfill areas and reduced NPP services provided by a grass cap.16 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. Closure options that include hybrid closure of the WAB reduce the footprint of grass cap and restore forest sooner than options that include excavation or CIP of the WAB. A summary of the results of the HEA are provided in Table ES-8. 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. 1707466.000 - 3651 xxx Table ES-8. Summary of NPP DSAYs for closure options (EAB/WAB) CIP/CIP CIP/ EXC OFF CIP/HYB EXC OFF/ CIP EXC OFF/ EXC OFF EXC OFF/ HYB HYB/CIP HYB/ EXC OFF HYB/HYB EXC ON/ EXC ON Ash basin Open Field -450 -437 -450 -450 -437 -450 -450 -437 -450 -437 losses Grass Cap -1 -1 -1 -1 -1 -1 -1 -1 -1 -197 Open Water -313 -305 -313 -313 -304 -313 -313 -304 -313 -304 Wetland -126 -123 -126 -126 -123 -126 -126 -123 -126 -124 Wooded -155 -155 -155 -150 -150 -150 -150 -150 -150 -183 Total losses -11046 -1,021 -1,046 -1,040 -1,014 -1,040 -1,040 -1,014 -1,040 -1245 Ash basin post- Open Field 351 665 401 557 871 607 351 665 401 947 closure gains Grass Cap 521 140 310 381 0 170 486 105 275 0 Open Water 100 365 427 92 356 418 97 362 424 312 Stream 9 2 3 12 5 1 10 3 12 Wetland 2 2 2 3 3 1 2 2 5 Wooded 98 1,665 1,199 983 2,550 2,084 419 1,986 1,520 3769 Total gains 1,070 2,844 2,341 2,017 3,792 3,288 1,355 3,129 2,626 5044 Landfill/borrow Wetland -3 losses Forest -1,425 -4,175 -1,660 -2,267 -5,016 -2,501 -1,440 -4,189 -1,675 -6008 Open Field -495 Open Water -62 Total losses -1,425 -4,175 -1,660 -2,267 -5,016 -2,501 -1,440 -4,189 -1,675 -6569 Landfill/borrow Forest 1,033 724 1,155 721 412 843 769 460 891 792 post -closure Grass Cap 161 84 245 84 26 187 26 273 gains Total gains 1,033 884 1,155 805 656 927 795 647 917 1065 Net Gain/Loss per site -369 -1,467 790 -484 -1,582 675 -330 -1,428 829 -1704 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. Closure duration estimates assume simultaneous closure of the EAB and WAB. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer and change the results of the HEA. 1707466.000 - 3651 The impact of the closure options on habitat -derived 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 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. A summary of the percent impacts is provided in Table ES-9. These percent impacts were input to the risk -ranking matrix (Table ES-3) along with the duration of the closure activities (Table ES- 2) to evaluate, within the NEBA construct, which of the closure options best minimizes local environmental disturbances (Table ES-10). Table ES-9. Percent impact of ash basin closure options (EAB/ CIP/ CIP/ CIP/ EXC OFF/ EXC OFF/ EXC OFF/ HYB/ HYB/ EXC HYB/ EXC ON/ WAB) CIP EXC OFF HYB CIP EXC OFF HYB CIP OFF HYB EXC ON DSAY Losses 2,471 5,195 2,706 3,306 6,030 3,541 2,479 5,204 2,714 7,813 DSAY Gains 2,102 3,728 3,496 2,822 4,448 4,215 2,150 3,776 3,543 6,109 Percent Impact(%) 15% 28% 0% 15% 26% 0% 13% 27% 0% 22% 1707466.000 - 3651 XXXll Table ES-10. Summary of relative risk ratings for habitat changes that affect protection of biodiversity and natural beauty. Darker shading and higher alphanumeric codes indicate greater impact. Minimize Local Objective Environmental Disturbance Hazard Habitat Change Attribute Service Acres Scenario (EAB/WAB) Baseline baseline CIP/CIP 3B CIP/Excavation Offsite 4C CIP/Hybrid -- Excavation Offsite/CIP 313 Excavation Offsite/Excavation Offsite 4C Excavation Offsite/Hybrid -- Hybrid/CIP 313 Hybrid/Excavation Offsite Hybrid/Hybrid -- Excavation Onsite/Excavation Onsite _ --" indicates "no meaningful risk." Within the objective of minimizing local environmental disturbance from closure, my analyses indicate that all closure options that include hybrid closure of the WAB produce comparable net benefits in habitat -derived environmental services, regardless of the closure option selected for the EAB. All other closure options produce net losses of habitat -derived services, though CIP closure of the WAB results in a relatively small net DSAY loss that is substantially less than the net loss under any excavation closure of the WAB. Closure options that include hybrid closure of the WAB best satisfy the fourth objective of ash basin closure —to minimize risk and disturbance to the local environment from closure.17 Conclusion 5: CIP or hybrid closure of the EAB and hybrid closure of the WAB maximize environmental services. Identifying environmental actions that maximize local environmental services (the fifth objective for ash basin closure) is a function of NEBA (Efroymson et al. 2003, 2004) and the If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 - 3651 XXXlll 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: 1. Protect human health from CCR constituent exposure All closure options for the Roxboro ash basins are protective of human health. 2. Protect ecological health from CCR constituent exposure All closure options for the Roxboro 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 local communities. 4. Minimize risk and disturbance to the local environment from closure Most closure options for the Roxboro ash basins produce a net loss of habitat -derived environmental services. 5. Maximize local environmental services CIP or hybrid closure of the EAB and hybrid closure of the WAB maximize local environmental services. Table ES-11 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, CIP or hybrid closure of the EAB and hybrid closure of the WAB (CIP/Hybrid or Hybrid/Hybrid) best maximize environmental benefits compared to the other closure options because they offer equivalent protection of human and ecological health from CCR exposure, result in less disturbance to the community over time compared to excavation closure options to an offsite landfill, and produce net gains in habitat -derived environmental services. Thus, CIP or hybrid closure of the EAB and hybrid closure of the WAB (CIP/Hybrid or Hybrid/Hybrid) best satisfy the fifth objective of ash basin closure —to maximize local environmental services. 1707466.000 - 3651 XXX1V As noted previously, 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 local environmental services 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 the Roxboro Plant is CIP closure of both basins but the HEA results for the currently defined CIP closure option estimate a net environmental service loss of an approximate 369 DSAYs, Duke Energy could consider incorporating into an updated CIP closure plan for the Roxboro Plant a mitigation project that compensates for the net environmental service losses projected from the currently defined CIP closure option. As an example, if Duke Energy started a reforestation project outside of the ash basin in 2021 (when on -site preparation of the ash basin begins), the reforestation project would gain 25.1 DSAYs/acre over the lifetime of the site (150 years in the HEA), requiring an approximate 14.7 acre project to compensate for the 369 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 basins for CIP closure. 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 Roxboro ash basins, I conclude, with a reasonable degree of scientific certainty, that CIP or hybrid closure of the EAB and hybrid closure of the WAB (CIP/Hybrid or Hybrid/Hybrid) best maximize environmental benefits to the local community compared to the other closure options because they offer equivalent protection of human and ecological health from CCR exposure, result in less disturbance to the community over time compared to excavation closure to an offsite landfill, and produce net gains in habitat -derived environmental services.18 '$ If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 - 3651 xxxv Table ES-11. NEBA for closure of the ash basins at the Roxboro Plant. Darker shading and higher codes indicate greater impact. Protect Human Minimize Objective Health from Protect Ecological Health from CCR Minimize Human Disturbance Environmental CCR Disturbance Exposure to Noise and Traffic Air Hazard Exposure to CCR Traffic Habitat Change CCR Accidents Pollution Congestion y O E O O � O O m O U E E ER n O Q- o r E a m a Co m E E O O W O a > V O � co oo > E> Q m o O E c5 O > En > N � E O y > c O O >a O E M >3 Ox c X DSAYs C N do > -2G Ea)0) O ) o E 6 a) U O o T E >, U ii O co co co ( m o U Q � Q _� n3 0) o a a O 0- Q Q J J (6 O Q 0) � a Scenario (EAB/WAB) Baseline -- -- -- -- -- -- -- -- -- -- -- -- -- baseline baseline baseline baseline CIP/CIP -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- 313 CIP/EXC OFF -- -- -- -- -- -- -- -- -- -- -- -- - 4A -- 4C CIP/HYB -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- -- EXC OFF/CIP -- -- -- -- -- -- -- -- -- -- -- -- -- 3A I -- 313 EXC OFF/EXC OFF -- -- -- -- -- -- -- -- -- -- -- -- - 413 I -- 4C EXC OFF/HYB -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- -- HYB/CIP -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- 313 HYB/EXC OFF -- -- -- -- -- -- -- -- -- -- -- -- -- 4A -- 4C HYB/HYB -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- EXC ON/EXC ON -- -- -- -- -- -- -- -- -- -- -- -- -- 5A -- 5C --" indicates no meaningful risk. 1707466.000 - 3651 XXXV1 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 1707466.000 - 3651 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. 1707466.000 - 3651 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 Progress, LLC's (Duke Energy's) Roxboro Steam Electric Plant (Roxboro Plant) 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 the Roxboro Plant, 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 the Roxboro Plant on October 30, 2017, and I reviewed expert reports prepared for related matters involving the Roxboro Plant. A list of the primary documents I relied upon in formulating my conclusions is provided in Section 3 of this report. 1707466.000 - 3651 3 Reliance Material 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 Roxboro Steam Electric Plant (SynTerra 2015a, 2016b, 2017) • Corrective Action Plan (CAP) for the Roxboro Steam Electric Plant (SynTerra 2015b, 2016a) o Baseline Human Health and Ecological Risk Assessment for the Roxboro Steam Electric Plant (SynTerra 2016c [Appendix D of CAP 2]) • 2016 Environmental Monitoring Report (Duke Energy 2017) • NCDEQ Roxboro Meeting Officer Report (NCDEQ 2016) o Attachment V. Written Public Comments Received o Attachment VIII. Public Comment Summary Spreadsheet • Human Health and Ecological Risk Assessment Summary Update for Roxboro Steam Electric Plant (SynTerra 2018; Appendix B) • Closure logistics estimates (Duke Energy 2018a, 2018b, 2019). 1707466.000 - 3651 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's Roxboro Plant has two onsite ash basins. The East Ash Basin (EAB) began operation in the mid- 1960s, and the West Ash Basin (WAB) was constructed in the early 1970s. In the late 1980s, an unlined landfill was constructed on top of the EAB for placement of dry ash, and a lined landfill was constructed on top of the unlined landfill around 2004 (SynTerra 2015a). Duke Energy has evaluated three representative types of closure for each of the ash basins at the Roxboro Plant—CIP, excavation to either onsite landfills or an offsite landfill at Duke Energy's Mayo Steam Electric Plant (Mayo Plant),19 and hybrid closure —the latter of which involves 19 The Mayo Plant is located approximately 11 miles, 15 miles by road, from the Roxboro Plant and approximately 10 miles northeast of the town of Roxboro, North Carolina. 1707466.000 - 3651 excavating and consolidating ash within the basin footprint to reduce the spatial area of CIP closure. The hybrid option for the EAB includes transport of the excavated portion of the ash basin to the Mayo Plant landfill(s) rather than consolidation within the EAB footprint. I have evaluated every combination of the CIP, excavation to an offsite landfill, and hybrid closure options for each basin and an additional option for excavation closure of both basins to onsite landfills, for a total of ten closure options. 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 services20 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. 4.1 Site Setting The Roxboro Plant is a coal-fired power plant in Person County in north -central North Carolina, near the North Carolina/Virginia border, near Semora, and approximately 8 miles northwest of the town of Roxboro (Figure 4-1). The Roxboro Plant is located on the east side of Hyco Lake and began operation in 1966, with additional generating capacity added in 1968, 1973, and 1980.21 Over its history, CCR have been wet sluiced into two onsite ash basins or transported dry to the onsite landfill. The Roxboro Plant began dry ash handling in the late 1980s. The footprint of the current EAB includes an eastern extension and a landfill (Figure 4-2). The EAB discharge canal is separated from the EAB and receives only surface water flow from the EAB extension. The WAB was constructed in 1973. In 1986, the main dam was raised and an additional settling basin was created in the southern end of the basin. Lined flue -gas desulfurization (FGD) ponds, which are substantially elevated above the original basin level, were constructed within the WAB footprint in 2008. The footprint of the WAB contains areas of open water, wetland, and grass (Figure 20 Environmental services, or ecosystem services, are ecological processes and functions that provide value to individuals or society (Efroymson et al. 2003, 2004). 21 Information presented in this section was derived from reviews of the comprehensive site assessment (CSA) documents prepared by SynTerra (2015a, 2016b, 2017). 1707466.000 - 3651 6 4-3). Surface water in the main portion of the WAB flows through a filter dike into the Southern Extension Impoundment and, from there, into the Western Discharge Canal. The WAB discharge canal receives effluent from WAB ash sluicing, EAB leachate, discharge from the FGD ponds, cooling tower blowdown, domestic sewage treatment plant discharge, and stormwater runoff from both ash basins (SynTerra 2017). The WAB discharge canal enters the heated water discharge canal, which ultimately discharges to Hyco Lake through NPDES Outfall 003 under Permit NC0003425. The EAB and WAB combined cover approximately 495 acres and contain an estimated 19.4 million tons of CCR. The EAB landfill contains an additional 6.8 million tons of CCR, and the ash fill areas contain approximately 7.8 million tons of CCR. A map of the Roxboro Plant is shown in Figure 4-1. 1707466.000 - 3651 Figure 4-1. Map of the Roxboro Plant. Reproduced and adapted from Figure 2-1 of the 2017 CSA Update (SynTerra 2017). The location of the ash basin discharge point to Hyco Lake was added (NPDES Outfall 003). Orange lines outline the boundaries of the ash basins. Green lines indicate landfill areas, and blue lines indicate streams. 1707466.000 - 3651 d. Figure 4-2. Photos from the EAB at the Roxboro Plant, October 30, 2017. (a, b) Mixed broadleaf and coniferous forest beyond the active landfill. (c) Open grass field covering the ash basin and landfill. (d) Open water habitat, with fringing wetlands and mixed forest. 1707466.000 - 3651 9 S e: Cr Figure 4-3. Photos from the WAB at the Roxboro Plant, October 30, 2017. WAB discharge canal with (a) submerged aquatic vegetation, (b) fringing wetland along the canal, and (c) primarily broadleaf forest and open water. (d) Open water, exposed ash, and marsh within the footprint of the WAB. The region surrounding the Roxboro Plant is an ecological transitional zone between the Appalachian Mountains and the Atlantic coastal plain.22 Much of the region was transformed historically from oak -hickory -pine forests to farmland and more recently from farmland again to woodlands characterized by successional pine and hardwood forest (Griffith et al. 2002). Current aerial imagery and onsite observations from CSA studies show that approximately 80% of the Roxboro Plant property is forested, and I observed extensive secondary forest habitat areas onsite and near the site during my October 2017 site visit. The many acres of game lands adjacent to the Roxboro Plant and Hyco Lake support annual hunting harvests of deer and turkey.23 22 The Roxboro facility is categorized as Northern Inner Piedmont by EPA's ecoregion classification system (hLtj2s://www.epa.j4ov/eco-research/ecoreizions). 23 http://www.ncwildlife.org/Hunting/Seasons-Limits/Harvest-Statistics. 1707466.000 - 3651 10 Hyco Lake is an approximately 3,750-acre impoundment of North Hyco Creek, South Hyco Creek, and Cobbs Creek and is the predominant ecological feature of the area abutting the Roxboro Plant (SynTerra 2015a). The lake was originally constructed by Carolina Power & Light Co., a predecessor to Duke Energy, to provide cooling water to the power station and receiving waters for heated water discharge24 and has since become a popular location for recreational boating and fishing activities.25 The lake supports a typical freshwater ecosystem and fishery for the area, including fish species such as bluegill sunfish (Lepomis macrochirus) and largemouth bass (Micropterus salmoides) (Duke Energy 2017). A notable addition to the fish fauna of Hyco Lake is blue tilapia (Oreochromis aureus), a warm -water, globally invasive species originally from Africa (Deines et al. 2016). Hyco Lake is at the northern edge of the possible tilapia range (Deines et al. 2016), and tilapia are only able to overwinter because of heated water discharge from the Roxboro Plant. Nonetheless, tilapia are useful forage fish for predators and have been proposed as forage for the introduction of additional popular angling species.26 4.2 Closure of the Ash Impoundments at the Roxboro Plant Coal ash, or CCR, includes fly ash, bottom ash, boiler slag, and FGD 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 the 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 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 4-4). Trace elements such as arsenic, cadmium, lead, mercury, selenium, and chromium generally constitute za Discharge into Hyco Lake is regulated by a NCDEQ NPDES permit NC0003425 at Outfall 003. 2s For example: http://www.hycolake.orW. 26 http://www.gameandfishmag.com/fishin 2017-top-north-carolina-bass-fishing-spots/ 1707466.000 - 3651 11 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).27 100% 90% p 80% p 70% Q 0 60% U 50 4091. 30% 20% 10% 0% Volcanic Ash Shale Fly Ash Bottom Ash Si —Al Fe Ca ■Other Major Elements Minor Elements ■Trace Elements Figure 4-4. 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 monitoring28 of CCR landfills and surface impoundments, as well as unit closure and corrective action, under certain circumstances. Owners and operators of CCR landfills and impoundments that are required to close under the regulation must either close by removal of CCR and meet the groundwater protection standards or close by leaving CCR in place and conduct an analysis of the effectiveness of potential corrective measures (a corrective measures assessment) and select a remedy. Per § 257.97(b), the selected strategy must at a 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, 27 https://www.epa.gov/coalash/coal-ash-rule 28 Groundwater must be evaluated for boron, calcium, fluoride, pH, sulfate, and total dissolved solids JDS), 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, molybdenum, selenium, thallium, and radium 226 and 228 combined. 1707466.000 - 3651 12 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 the Roxboro Plant, under the CCR rule and pursuant to the administrative process set forth in CAMA. Ultimately, a final closure plan will be approved by NCDEQ. Ten possible closure options 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. 1707466.000 - 3651 13 Table 4-1. Ash basin closure options provided by Duke Energy (2018a,b) Closure Option (EAB/WAB) EAB WAB Closure Duration (years),,b Construction Duration (years)b,0 CIP/CIP CIP CIP 7 5 CIP/Excavation CIP Excavate to Mayo Offsite landfill 16 14 CIP/Hybrid CIP Partially excavate to consolidate ash and CIP consolidated ash 9 7 Excavation Excavate to Mayo CIP Offsite/CIP landfill 7 5 Excavation Offsite/ Excavate to Mayo Excavate to Mayo Excavation Offsite landfill landfill 16 14 Excavation Offsite/ Excavate to Mayo Partially excavate to Hybrid landfill consolidate ash and CIP consolidated ash 9 7 Hybrid/CIP Partially excavate to CIP Mayo landfill and CIP consolidated ash 7 5 Hybrid/ Partially excavate to Excavate to Mayo Excavation Offsite Mayo landfill and CIP landfill consolidated ash 16 14 Hybrid/Hybrid Partially excavate to Partially excavate to Mayo landfill and CIP consolidate ash and consolidated ash CIP consolidated ash 9 7 Excavation Onsite/ Excavate to new Excavate to new Excavation Onsite onsite landfill onsite landfill 20 17 a Includes pre -design investigation, design and permitting, site preparation, construction, and site restoration. b Duration estimates assume simultaneous closure of the EAB and WAB. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer. ° 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 is necessary for excavation closure of the WAB; (2) substantially more deforestation is required under closure options that include excavation closure of the WAB; and (3) substantially more average truck trips per day and total truck miles are required under all offsite excavation closure options. 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 1707466.000 - 3651 14 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 among closure options for the Roxboro Plant ash basin. Data provided by Duke Energy (2018a,b). Closure Option Closure Deforested Average Total truck (EAB/WAB) Completion Time Acresb Truck milesd (years)a trips/day° CIP/CIP 7 46 39 1,756,324 CIP/Excavation Offsite 16 138 164 21,582,158 CIP/Hybrid 9 53 29 1,990,576 Excavation Offsite/CIP 7 75 150 6,477,739 Excavation Offsite/ 16 166 200 26,303,573 Excavation Offsite Excavation Offsite/ 9 82 99 6,711,991 Hybrid Hybrid/CIP 7 47 49 2,155,104 Hybrid/ 16 139 167 21,980,938 Excavation Offsite Hybrid/Hybrid 9 54 35 2,389,356 Excavation Onsite/ 20 245 17 2,812,545 Excavation Onsite a Includes pre -design investigations, design and permitting, site preparation, construction, and site restoration. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer. b Includes areas deforested to create borrow pits and/or landfill. Assumes simultaneous closure of the EAB and WAB. Includes the total number of offsite roundtrip truck trips to haul earthen, ash, and geosynthetic material to and from the ash basin averaged over the length of construction months. d Includes the total number of offsite truck miles driven over the duration of construction operations to haul material to and from the ash basin. 1707466.000 - 3651 15 Closure of the ash basins at Roxboro involves decanting any overlying water in the basins 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 CCR Rule concern constructed29 and non-constructed30 seeps associated with the ash basin .31 A Special Order by Consent (SOC; EMC SOC WQ S 18-005) was signed by the North Carolina Environmental Management Commission and Duke Energy on August 15, 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 S 18-005). 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 S 18-005). 29 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. '0 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 Roxboro that require monitoring (and potentially action if they are not eliminated after ash basin decanting) are listed in the SOC (EMC SOC WQ S 18-005). 31 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 S 18-005). 1707466.000 - 3651 16 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); 1707466.000 - 3651 17 • 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 the Roxboro Plant. 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 (2009), remediation 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 of the Roxboro Plant. 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 (SynTerra 2015a, 2016b, 2017) and CAP (SynTerra 2015b, 2016a) 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, 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. 1707466.000 - 3651 18 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)32 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 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 (i.e., stakeholders may have different priorities for 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 environmental services (e.g., provision of safe drinking water, protection of biodiversity33) 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. 3z 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" (htWs:Hofmpub.epa. og v/sor_internet/registry/termreiz/searchandretrieve/glossariesandkeywordlists/search.do?de tails=&IzlossaryName=Eco%20Risk%20Assessment%20G10 ssary). 33 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. 1707466.000 - 3651 19 EPA supports the use of NEBA (U.S. EPA 2009) 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 1707466.000 - 3651 20 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).34 Consequently, the higher remediation goal was applied to that segment of the river. These examples of NEBA are particularly relevant to the issues at the Roxboro Plant. 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 over closure of the ash basins at Roxboro, I reviewed written communications about ash basin closure plans for the Roxboro Plant submitted to and summarized by 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 34 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. 1707466.000 - 3651 21 the local community: provision of safe drinking water and food, safe recreational enjoyment (e.g., fishing, swimming), and 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 resulting from transportation activities; and traffic, noise, and accidents that could result in property damage, injuries, and fatalities. Table 5-1 links concerns related to CCR exposure and potential hazards created by ash basin closure to environmental services that could be affected by closure activities. 1707466.000 - 3651 22 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 Safe surface Safe air Safe food Protection of Recreation Natural Safe community water quality water quality quality quality biodiversity beauty environment CCR Concerns Drinking water X X X contamination Groundwater X X X contamination Surface water X X X X X X X contamination Fish/wildlife X X X X X contamination Contamination impacting X X X X X X X property value Contamination impacting X X X natural beauty Contamination impacting X X X X X recreational enjoyment Contamination impacting X X X X swimming safety Failure of the ash X X X X X X X impoundment Closure Hazards Habitat loss X X X X X Contamination of air X X X X Noise, Traffic, Accidents X X 1707466.000 - 3651 23 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: l . 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 Roxboro ash basins and environmental services Ash Basin Closure Objectives Protect Protect Minimize risk Minimize risk Maximize local human health ecological health and and disturbance environmental from CCR from CCR disturbance to the local services Environmental constituent constituent to humans environment Services exposure exposure from closure from closure Safe drinking X X X water quality Safe surface X X X water quality Safe air quality X X Safe food quality X X X Recreation X X Natural beauty X X X Protection of X X X biodiversity Safe community X X environment 1707466.000 - 3651 24 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 Ecological Net Primary Transportation Risk Health Risk Productivitv 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 Loaistics Notes: DSAYs — discounted service acre -years ELCR — excess lifetime cancer risk HI — hazard index HQ — hazard quotient 2 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 1707466.000 - 3651 25 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)35 and discounted service acre -years (DSAYs)36 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. 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 basin dam (NCDEQ 2016). The most recent dam safety report produced by Amec Foster Wheeler Environment & Infrastructure, Inc. and submitted to NCDEQ indicates "the construction, design, operation, and 35 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/GlobaIMaps/view.php?d1=MOD17A2_M PSN). 36 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 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). 1707466.000 - 3651 26 maintenance of the CCR surface impoundments have been consistent with recognized and generally accepted engineering standards for protection of public safety and the environment" (Williams and Tice 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, respectively. Shading of cells within the matrix supports visualization of the magnitude of the effect according to the extent and duration of an impact.37 When there is no meaningful risk, the cell is not given an alphanumeric code. Risk ratings for each attribute and closure option 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. 37 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. 1707466.000 - 3651 27 Table 5-4. Risk -ranking matrix for impacts and risk from remediation and closure activities Duration of Impact (years) 16-25 (5) 110-15 (4) 5-9 3 1-4 2 <1 1 No meaningful risk -- -- -- -- <5% (A) 5A 4A 3A 12A 1 A 5-19% (B) 5B 4B 3B 12B 1 B 20-39% (C) 5C 4C 3C 12C 1C 40-59% (D) I 3D 12D 1 D 60-79% (E) I 2E 11 E E 80-99% (F) 1F 0 100-149% (G) 150-199% (H) 200-299% (1) 300-399% (J) 400-499% (K) >500% (L) NEBA analysis of possible closure options for the ash basin at the Roxboro Plant 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 local environmental services, closure plans for that option can be re-examined, and opportunities to better maximize environmental benefits can be identified (e.g., including offsite habitat mitigation 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, 1707466.000 - 3651 28 without such a baseline, how can it ever be possible to set guideline values and standards, given that life can never be risk free?" 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)38 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. 38 A conservative estimate of the chemical concentration available from a particular media and exposure pathway. 1707466.000 - 3651 29 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 Roxboro ash basins are protective of human health. Current conditions39 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 Roxboro ash basins are protective of ecological health. Current conditions40 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 local communities. All closure options support safe air quality from additional diesel truck emissions along the transportation routes; however, each creates disturbance and risk that could adversely 39 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 AOWs) at the Roxboro Plant 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 Energy entered with the North Carolina Environmental Management Commission on August 15, 2018 (EMC SOC WQ 518-005; 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 518-005). 40 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 the Roxboro Plant 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 August 15, 2018 (EMC SOC WQ S18-005; 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 S 18-005). 1707466.000 - 3651 30 impact community safety, with a substantially greater magnitude of impact from excavation closure of the basins to an offsite landfill because of the increased amount of offsite road transportation activities. CIP, hybrid, and excavation closure to onsite landfill closure options produce less risk and disturbance to the community and better satisfy the third objective of ash basin closure —to minimize risk and disturbance to humans from closure.41 Conclusion 4: Most closure options for the Roxboro ash basins produce a net loss of habitat -derived environmental services. Closure of the WAB is the most important determinant of the net habitat -derived environmental services resulting from closure. The three closure options that include hybrid closure of the WAB produce comparable net benefits in habitat -derived environmental services, regardless of the closure option selected for the EAB, while all other closure options produce net losses of habitat -derived services, though CIP closure of the WAB results in a relatively small net DSAY loss that is substantially less than the net loss under any excavation closure of the WAB. Closure options that include hybrid closure of the WAB best satisfy the fourth objective of ash basin closure —to minimize risk and disturbance to the local environment from closure.42 Conclusion 5: CIP or hybrid closure of the EAB and hybrid closure of the WAB maximize local environmental services. CIP or hybrid closure of the EAB and hybrid closure of the WAB (CIP/Hybrid or Hybrid/Hybrid) best maximize local environmental benefits compared to the other closure options because they offer equivalent protection of human and ecological health from CCR exposure, result in less disturbance to the community over time compared to excavation closure options to an offsite landfill, and produce net gains in habitat -derived environmental services,4' best satisfying the fifth objective of ash basin closure —to maximize local environmental services.42 Each conclusion will be discussed in detail in the following sections. 41 If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 12 As noted in Section 5 and further discussed in Section 11, loss of habitat -derived environmental services from CIP closure could be offset with an appropriate reforestation project. 1707466.000 - 3651 31 7 Conclusion 1: All closure options for the Roxboro 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: 1. Provision of permanent alternative drinking water supplies to private well water supply users within a 0.5-mile radius of the Roxboro ash basin compliance boundary (Holman 2018); 2. Concentrations of CCR constituents of interest (COIs) in drinking water wells that could potentially affect local residents and visitors, as characterized by SynTerra (2015a, 2016b, 2017) in the 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 (2018; Appendix B). Through these lines of evidence, I evaluated whether CCR constituents are currently impacting drinking water wells, whether they will in the future, and whether other exposures to CCR constituents pose a risk to human populations now or with closure of the ash basins. 7.1 Private water supply wells pose no meaningful risk to the community around the Roxboro Plant. Per H.B. 630, Sess. L. 2016-95, all residents with drinking water supply wells within a 0.5-mile radius of the Roxboro ash basin compliance boundary have been provided with permanent alternative drinking water supplies (i.e., filtration systems; Draovitch 2018),43 eliminating drinking water as a potential CCR exposure pathway for local residents or visitors. a3 NCDEQ determined Duke Energy had satisfactorily completed the permanent alternative water provision under CAMA General Statute (G.S.) 130A-309.21 1(cl) on October 12, 2108 (Holman 2018). 1707466.000 - 3651 32 Additionally, available data indicate that public and private well water conditions are not impacted by CCR constituents. As of 2017, there were three public wells within a 0.5-mile radius of the Roxboro Plant ash basin compliance boundary (SynTerra 2017). The two wells at the Woodland Elementary School are upgradient of the WAB, while the third is located northeast of the EAB. CCR constituent concentrations in these wells were found to be consistent with groundwater provisional background threshold values (PBTVs), and geochemistry results do not indicate CCR impact (SynTerra 2017). Approximately 102 private water supply wells also exist within the 0.5-mile radius of the ash basin compliance boundary but upgradient or cross -gradient of them (SynTerra 2017). In 2015, seven private wells were sampled, and exceedances of the North Carolina Groundwater Quality Standards (2L)/Interim Maximum Allowable Concentrations (IMACs)44 were identified for manganese, vanadium, and total dissolved solids (TDS)45 among the COIs (SynTerra 2015a); however, background concentrations (PBTVs) of these constituents were also elevated compared to the 2L groundwater standards (SynTerra 2017). Vanadium concentrations in two wells were slightly higher compared to the groundwater PBTVs calculated by SynTerra (2016b); but because other key CCR-related constituents, such as boron, were not found in these wells, CCR are not the source of the vanadium. Approximately two times the 2L exceedance values for TDS were noted in one well, though another sample from the same property did not exceed for TDS. Based on these analyses, SynTerra (2015a, 2017) concluded that water supply wells within a 0.5-mile radius of the ash basin compliance boundary are not impacted by CCR constituents. 7.2 CCR constituents from the Roxboro 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 baseline HHRA (SynTerra 2018) originally conducted by SynTerra (2016c) as a component of the CAP part 2 (SynTerra 2016a). The "2L" criteria are defined by the North Carolina Administrative code 15A NCAC 02L Groundwater Rules. The 2L Rule allows for IMACs to also be defined for evaluating water quality. 15 TDS are inorganic salts (e.g., calcium, magnesium, potassium, sodium, chlorides, etc.) dissolved in water. 1707466.000 - 3651 33 updated HHRA included updates46 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 COPCs47 with plausible complete exposure pathways. Consistent with the 2016 baseline human health and ecological risk assessment (SynTerra 2016c), the updated HHRA (SynTerra 2018) examined CCR constituent exposure to a range of human populations, including onsite trespassers and onsite construction workers, under different pathways (i.e., exposure to sediment, surface water, or groundwater). HIs and ELCRs were estimated for closure options with plausible complete exposure pathways. CCR exposure pathways evaluated in the updated HHRA included the following (SynTerra 2018):48 • Onsite trespassers via onsite sediment and surface water • Onsite construction workers via groundwater.49 Since all households with drinking water supply wells within a 0.5-mile radius of the Roxboro ash basin compliance boundary have received permanent alternative water supplies (Holman 2018) and no residences are located downgradient of the plant (SynTerra 2017), drinking water risks were not further evaluated, because there was not a complete exposure pathway. A 46 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). 47 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" (htWs:Hofmpub.epa. og v/sor_internet/registry/termreg/searchandretrieve/glossariesandkeywordlists/search.do?de tails=&IzlossaryName=Eco%20Risk%20Assessment%20G10 ssary). 48 The 2016 HHRA (SynTerra 2016c) considered exposure to offsite recreational users of Hyco Lake (e.g., offsite recreational swimmers, offsite recreational waders, offsite recreational boaters, offsite recreational and subsistence fishers) and onsite commercial and industrial workers. SynTerra (2018) explains that the updated HHRA did not include these receptors because "[u]pdated modeling shows no direct groundwater impacts to Hyco Lake" and because "use of personal protective equipment (e.g., boots, gloves, safety glasses) and other safety behaviors exhibited by Site workers limits exposure to CCR constituents." 49 Groundwater exposure to onsite construction workers was evaluated in the updated HHRA, though a pathway for exposure was considered incomplete by SynTerra (2018). 1707466.000 - 3651 34 summary of the risk assessment results from the HHRA (SynTerra 2016c) is provided in Table 7-1. Table 7-1. Summary of human health risk assessment hazard index (HI) and excess lifetime cancer risk (ELCR) from SynTerra (2016c) Media Receptor HI ELCR Sediment Trespasser 0.005 NC Surface Water Trespasser 0.007 2.Ox10-8 Groundwater (Surficial Aquifer) Construction Worker 0.003 NC Groundwater (Transition/Bedrock) Construction Worker 0.001 NC Notes: NC - Risk based concentration based on non -cancer HI. All exposure scenarios assessed by SynTerra (2018b) indicated that exposure to CCR poses no meaningful risks to humans. 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 human health. 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. so 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 AOWs) at the Roxboro Plant 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 Energy entered with the North Carolina Environmental Management Commission on August 15, 2018 (EMC SOC WQ S18-005; 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 518-005). 1707466.000 - 3651 35 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 N C O i N O O O a > C: 4 a O LL� L Q O >,75- U o O a+ C J O N Oa+ O a Scenario (EAB/WAB) Baseline -- -- -- CIP/CIP -- -- -- CIP/Excavation Offsite -- -- -- CIP/Hybrid -- -- -- Excavation Offsite/CIP -- -- -- Excavation Offsite/Excavation Offsite -- -- -- Excavation Offsite/Hybrid -- -- -- Hybrid/CIP -- -- -- Hybrid/Excavation Offsite -- -- -- Hybrid/Hybrid -- -- -- Excavation Onsite/Excavation Onsite -- -- -- --" 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. 1707466.000 - 3651 3 8 Conclusion 2: All closure options for the Roxboro 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: 1. Risk to ecological receptors from CCR exposure, as characterized by SynTerra (2018; Appendix B) in the updated human health and ecological risk assessment; and 2. Aquatic community health in Hyco Lake as reported in the 2016 environmental monitoring report (Duke Energy 2017). Through these two lines of evidence, I evaluated whether CCR constituents pose a risk to ecological populations now or after closure of the ash basins. 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 (2018) updated the Baseline Human Health and Ecological Risk Assessment that was originally performed by SynTerra (2016c) as a component of the CAP part 2 (SynTerra 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 the receptors with potentially complete exposure pathways to CCR related COPCs (SynTerra 2018). 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 1707466.000 - 3651 37 SynTerra's updated ERA (SynTerra 2018) 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), bald eagle (carnivore)51 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 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 (2018) 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)52 and lowest -observed -adverse -effects levels (LOAELs)53 derived from the literature for each COPC. si The bald eagle was added to this risk assessment model because the species is federally protected and represents a raptor that preys upon fish, primarily, while the red-tailed hawk primarily preys upon small terrestrial vertebrates (e.g., rodents, snakes, etc.). HQ calculations for the bald eagle include hypothetical consumption of fish that inhabit adjacent surface water areas in addition to terrestrial vertebrates that inhabit upland areas. 52 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. 53 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. 1707466.000 - 3651 38 HQ results for the Roxboro Plant were evaluated for two exposure areas of the Roxboro Plants4 (Figure 8-1). HQs less than 1 indicate no meaningful risk to an ecological receptor associated with exposure to the COPC's evaluated. • Eastern Discharge Canal: NOAEL and LOAEL HQs>l for meadow vole and red fox aluminum exposure; NOAEL HQ>1 for muskrat aluminum and American robin exposure, but LOAEL HQ<l. Aluminum does not represent a potential ecological risk to terrestrial receptors (e.g., meadow vole or red fox) unless the pH of the soil is below 5.5 (U.S. EPA 2003).55 The pH values associated with the sediment samples56 collected in the eastern discharge canal ranged from 6.1-7.0. SynTerra's updated ERA (2018) also notes that background concentrations of aluminum would indicate similar levels of risk; therefore, there is no meaningful risk to ecological receptors from aluminum in the eastern discharge canal. All HQs<1 for other terrestrial and aquatic ecological receptors, indicating no meaningful risk to ecological receptors in this area. • Cooling Water Intake Basin: All HQs<l, indicating no meaningful risk to ecological receptors in this area. Additionally, the 2016 environmental monitoring report (Duke Energy 2017) for Hyco Lake reported results from biological sampling and water chemistry analyses conducted in 2016. The report concluded that impacts from the Roxboro Plant to water quality and aquatic life are minimal. Based on analyses of fish community composition, the fish community was reported to be balanced and self-sustaining (Duke Energy 2017). s4 The baseline ERA conducted by SynTerra in 2016 (SynTerra 2016c) included five exposure areas: East Ash Basin area, Gypsum Storage Pad Area, WAB Extension Impoundment, EAB Extension Impoundment, and Hyco Lake. Several of these exposure areas have been eliminated from the updated ERA (SynTerra 2018) because they were determined by SynTerra to have no influence from groundwater migration from the ash basins (Hyco Lake); because they have been recognized as part of the ash basins (WAB Extension Impoundment and EAB Extension Impoundment) and, as such, part of the permitted wastewater treatment facilities; or because they are not associated with CCR from the ash basins (Gypsum Storage Pad Area). ss According to EPA (2003), "Aluminum is identified as a COPC only at sites where the soil pH is less than 5.5." s6 SynTerra (2018) used sediment data collected in the eastern discharge canal as a surrogate for soil data for terrestrial receptors because soil data was not available. 1707466.000 - 3651 39 Given the lack of meaningful ecological risk from CCR exposure under current conditions,57 all closure options would be protective of ecological receptors since each closure option reduces exposure compared to current conditions or eliminates potential exposure pathways. 57 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 Roxboro 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 August 15, 2018 (EMC SOC WQ S18-005; 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 S 18-005). 1707466.000 - 3651 40 }• ` % :COLING WATER v\ � ' BASIN XPOS . � :•• �. :_ —jam 'xPOSLLRE AREA " le�.r,scHARco. i LEGEN t f, • SURFACE WATER LOCATION f' ^ —EASTERN DISCHARGE CANAL EXPOSURE ANf - _ - L " tl. - f � COOLING WATER INTAKE BASIN. EXPOSURE AREA •.� , rI GYPSUM STORAGEAREA EXPOSURE AREA f7 �EAB EXTENSION IMPOUNDMENT y •�. EXPOSURE AREA v. NYCO LAKE EXPOSURE AREA DUKE ENERGY PROGRESS ROXBORO PLAN' r• 'i` ... L'=.'-'COMPLIANCE BOUNDARY ` /, '•� OWASTE BOUNDARY ..,1n •.` _ STREAM � • _ ^ •, `—LANOFILLAREA i1RRp�Rrc epuxpuev n, ovipmavwxEENsaev XRosaEss `^. SIB ��� 4MIE+AEaSEeMw. �fROLLTE M91 Asg6%B�IIG... NOT WFi.IJENC£PT'GRWu[WAT9L MCi4MNFPJMl1EAM B4•MS 1 /; HEtneL fXpiocRARXr usnunEurawl woGLEE.mXR.appXgRlEM1ER n, � Mil fERIfLw�LS[Ou£CifBOxu..XE1). M�F yAti�' `QLRA'MNG XAs �w sETwrtXA i. �'Y cuxLxAaIME R.ti` 1 ` : L J � . C]OPOWAIE SY SIEM FIP53MOtlMC03'A '.:i i ®" FIGURE A 466N+' _ EXPOSURE AREAS �~ S)AlTeffd a.m GICAL RISK ASSESSMENT �:. -;" RECOLOOXBORO STEAM ELECTRIC PLANT r' DUKE DUKE ENERGY PROGRESS, LLC ENERGYSEMORA, NORTH CAROLINA PROGRESS Figure 8-1. Exposure areas evaluated in the 2018 ERA update (SynTerra 2018) 1707466.000 - 3651 41 8.2 NEBA — Protection of Ecological Health from CCR Exposure Based on these analyses, no meaningful risk to ecological receptors from CCR exposure was found under current conditions or under any closure option. Using the NEBA framework and relative risk ratings, these results are summarized in Table 8-1 within the objective of protecting ecological health from CCR constituent exposure. Table 8-1. Summary of relative risk rating 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 a� tq C O O ^ Y o >i C a L :3 a> Y (n O L a) O L CO O CO O _ E CuN E > `/ o E E °° _ L a m E ca E o m E CO Ca 41 Q a0 O m a) L O L O E a) L O a) L Q > Q 21 E L O > > L O > � L O > _ > L L O Cu O co L Cu CD O 0 Cu O Q Cr Cu L Q Q 0- Q L� L MMMMMMMMM -- 111UiUa1LcO 1IU IIMCIIwiyiui Tian. 1707466.000 - 3651 42 Current conditions and conditions under any closure option 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. 1707466.000 - 3651 43 9 Conclusion 3: Excavation closure to an offsite landfill creates greater disturbance to local 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 basins, 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 various closure options. All closure options require increased trucking activity to haul materials to the site (e.g., transport cap material from a borrow site to the ash basin) or to haul materials away from the site (e.g., transport coal ash from the ash basin to an offsite 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 described in Table 4-1. Obvious from these numbers is that the amount of trucking involved in any closure option that includes excavation to an offsite landfill is substantially greater than that involved in closure options that do not include excavation with offsite 1707466.000 - 3651 44 landfilling. These differences are reflected in the total volume moved, the number of truck loads required, and the number of miles driven.58 58 It is important to note that estimates of the duration of closure and construction assume that both the EAB and the WAB can be closed simultaneously, an assumption that has not received a feasibility analysis. If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 - 3651 45 Table 9-1. Summary of transportation logistics associated with combinations of Roxboro EAB and WAB closure options (Duke Energy 2018a, 2018b, 2019) EXC OFF/ EXC OFF/ EXC OFF/ HYB/ EXC ON/ Logistics CIP/CIP CIP/EXC OFF CIP/HYB CIP EXC OFF HYB HYB/CIP EXC OFF HYB/ HYB EXC ON Closure Duration (years)3 7 16 9 7 16 9 7 16 9 20 Construction Duration (years)a•b 5 14 7 5 14 7 5 14 7 17 Offsite truck loads to haul cap & fill materials 55,667 42,324 64,735 40,614 27,271 49,682 42,513 29,170 51,581 88,216 Offsite miles driven to haul cap & fill materials 1,756,324 1,380,821 1,990,576 1,318,427 942,924 1,552,679 1,364,474 988,971 1,598,726 2,812,545 Offsite truck loads to excavate ash and associated materialsd 0 673,378 0 171,977 845,355 171,977 26,354 699,732 26,354 0 Offsite miles driven to excavate all materialsd 0 20,201,337 0 5,159,312 25,360,649 5,159,312 790,631 20,991,968 790,631 0 Total offsite truck loads 55,667 715,702 64,735 212,591 872,626 221,659 68,867 728,902 77,935 88,216 Total offsite miles driven 1,756,324 21,582,158 1,990,576 6,477,739 26,303,573 6,711,991 2,155,104 21,980,938 2,389,356 2,812,545 a Includes design and permitting, decanting, site preparation, construction, and site restoration. Assumes closure of the basins can occur simultaneously. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer. b Includes site preparation, construction, and site restoration. c Includes cover soil, top soil, and geosynthetic material. d Includes ash, and over -excavated soil, and removed dams and embankments. 1707466.000 - 3651 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 offsite transportation activities under all closure options compared to CIP closure for both basins. From these results, it is clear that risk and disturbance associated with transportation activities will be substantially greater under closure options that include excavation to an offsite landfill of either ash basin, with the greatest potential for risk and disturbance from excavation closure of the WAB to an offsite landfill. CIP closure of both basins produces the least potential for risk and disturbance from closure of the basins based on the total volume of materials moved, the total number of truck loads required, and the total number of miles driven. 18 16 O 14 O > O V 12 c>5 cC (D a 10 (D .Q 8 Q U 6 2 4 2 0 Projected Construction Time (years) CIPI CIPI EXC EXC OFF/ EXC OFF/ Hybrid/ Hybrid/ Hybrid/ EXC ON/ EXC OFF Hybrid OFF/CIP EXC OFF Hybrid CIP EXC OFF Hybrid EXC ON Figure 9-1. Normalized differences between all offsite transportation activities under CIP, excavation, and hybrid options. Bars represent the increased activity under closure options compared to CIP for both basins. 1707466.000 - 3651 47 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 the Roxboro Plant are generally diesel powered, and diesel exhaust includes a variety of different particulates and gases, including more than 40 toxic air contaminants.59 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 PMIo60 as toxic air pollutants. North Carolina defers to EPA's chronic non -cancer reference concentration (RfC) for diesel particulate matter (DPM) of 5 µg/m3 based on diesel engine exhaust to estimate risk from diesel emissions.61 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)62 of 5 µg/m3 and a range of inhalation potency factors indicating that a "reasonable estimate" for the inhalation unit risk is 3.Ox 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 PMIo as a surrogate measure. As PMIo is the basis for both the non -cancer and inhalation risk factors for diesel exhaust exposure in California, I relied on a PMIo exposure model to evaluate potential non -cancer and cancer health risks from diesel exhaust.63 59 htWs:Hoehha.ca.gov/air/health-effects-diesel-exhaust 60 PM2.5 and PMIo are airborne particulate matter sizes. PM2.5 is particulate matter that is 2.5 µm or less in size; PMIo is particulate matter that is 10 µm or less in size. 61 Integrated Risk Information System (IRIS). U.S. EPA. Diesel engine exhaust. 62 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. Long-term exposure for these purposes has been defined by EPA as at least 12% of a lifetime, or about eight years for humans. 63 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. 1707466.000 - 3651 48 A representative segment of road was simulated using EPA's AERMOD mode164 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).65 Emission factors were then applied to the number of offsite truck trips each year to define the average annual amount of DPM emitted along the representative road segment, and these exposures were then summed over seventy years.66 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 in perpendicular to either side of the road. The results of the model were translated into average PMIo exposure (µg/rn) and excess cancer risk over a 70-year period using reasonable maximum exposure.67 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. 64 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). 65 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 trucks were used. 66 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 70-year averaging time (OEHHA 2015). 67 Long-term exposure was incorporated into the air simulation as the average exposure given estimated trucking rates for 12 hours per day —lam to 7 pm-6 days a week for the duration of the project construction time. 1707466.000 - 3651 49 Table 9-2. Hazard indices (HI) and excess lifetime cancer risk (ELCR) from exposure to diesel exhaust emissions along transportation corridors in northern North Carolina. Results are for the maximum exposures modeled (EAB/WAB). Perpendicular CIP/CIP CIP/EXC OFF CIP/HYB EXC OFF/CIP EXC OFF/EXC OFF EXC OFF/HYB HYB/CIP HYB/EXC OFF HYB/HYB EXC ON/EXC ON distance from the road ELCR HI ELCR HI ELCR HI ELCR HI ELCR HI ELCR HI ELCR HI ELCR HI ELCR HI ELCR HI 10 m 2.25E-08 0.0002 1.73E-07 0.0006 2.16E-08 0.0001 8.60E-08 0.0009 2.11E-07 0.0007 7.38E-08 0.0005 2.79E-08 0.0003 1.76E-07 0.0006 2.59E-08 0.0002 1.76E-08 0.0000 20m 1.83E-08 0.0002 1.40E-07 0.0005 1.75E-08 0.0001 6.99E-08 0.0007 1.71E-07 0.0006 6.00E-08 0.0004 2.27E-08 0.0002 1.43E-07 0.0005 2.11E-08 0.0001 1.43E-08 0.0000 30m 1.44E-08 0.0001 1.11E-07 0.0004 1.38E-08 0.0001 5.50E-08 0.0006 1.35E-07 0.0005 4.72E-08 0.0003 1.78E-08 0.0002 1.13E-07 0.0004 1.66E-08 0.0001 1.13E-08 0.0000 40 m 1.18E-08 0.0001 9.08E-08 0.0003 1.13E-08 0.0001 4.52E-08 0.0005 1.11E-07 0.0004 3.88E-08 0.0003 1.47E-08 0.0002 9.25E-08 0.0003 1.36E-08 0.0001 9.26E-09 0.0000 50m 1.00E-08 0.0001 7.70E-08 0.0003 9.61E-09 0.0001 3.83E-08 0.0004 9.39E-08 0.0003 3.29E-08 0.0002 1.24E-08 0.0001 7.84E-08 0.0003 1.16E-08 0.0001 7.85E-09 0.0000 60m 8.78E-09 0.0001 6.73E-08 0.0002 8.40E-09 0.0001 3.35E-08 0.0003 8.21E-08 0.0003 2.88E-08 0.0002 1.09E-08 0.0001 6.86E-08 0.0002 1.01E-08 0.0001 6.86E-09 0.0000 70 m 7.81E-09 0.0001 5.99E-08 0.0002 7.48E-09 0.0000 2.98E-08 0.0003 7.30E-08 0.0002 2.56E-08 0.0002 9.66E-09 0.0001 6.10E-08 0.0002 9.00E-09 0.0001 6.11E-09 0.0000 80 m 7.03E-09 0.0001 5.39E-08 0.0002 6.73E-09 0.0000 2.69E-08 0.0003 6.58E-08 0.0002 2.30E-08 0.0001 8.70E-09 0.0001 5.49E-08 0.0002 8.10E-09 0.0001 5.50E-09 0.0000 90m 6.39E-09 0.0001 4.90E-08 0.0002 6.12E-09 0.0000 2.44E-08 0.0003 5.98E-08 0.0002 2.09E-08 0.0001 7.91E-09 0.0001 4.99E-08 0.0002 7.36E-09 0.0000 5.00E-09 0.0000 100 m 5.85E-09 0.0001 4.49E-08 0.0001 5.60E-09 0.0000 2.24E-08 0.0002 5.47E-08 0.0002 1.92E-08 0.0001 7.24E-09 0.0001 4.57E-08 0.0002 6.74E-09 0.0000 4.58E-09 0.0000 110 m 5.39E-09 0.0001 4.14E-08 0.0001 5.16E-09 0.0000 2.06E-08 0.0002 5.04E-08 0.0002 1.77E-08 0.0001 6.67E-09 0.0001 4.21E-08 0.0001 6.22E-09 0.0000 4.22E-09 0.0000 120 m 5.00E-09 0.0001 3.83E-08 0.0001 4.78E-09 0.0000 1.91E-08 0.0002 4.67E-08 0.0002 1.64E-08 0.0001 6.18E-09 0.0001 3.90E-08 0.0001 5.76E-09 0.0000 3.91E-09 0.0000 130 m 4.65E-09 0.0000 3.57E-08 0.0001 4.45E-09 0.0000 1.78E-08 0.0002 4.35E-08 0.0001 1.52E-08 0.0001 5.76E-09 0.0001 3.63E-08 0.0001 5.36E-09 0.0000 3.64E-09 0.0000 140 m 4.35E-09 0.0000 3.33E-08 0.0001 4.16E-09 0.0000 1.66E-08 0.0002 4.06E-08 0.0001 1.42E-08 0.0001 5.38E-09 0.0001 3.40E-08 0.0001 5.01E-09 0.0000 3.40E-09 0.0000 150 m 4.08E-09 0.0000 3.13E-08 0.0001 3.90E-09 0.0000 1.56E-08 0.0002 3.81E-08 0.0001 1.34E-08 0.0001 5.04E-09 0.0001 3.18E-08 0.0001 4.70E-09 0.0000 3.19E-09 0.0000 1707466.000 - 3651 50 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 excavation closure to an offsite landfill. Increased trucking increases noise and traffic congestion and creates a statistically based risk of increased traffic accidents that could result in fatalities, injuries, and/or property damage (Forkenbrock 1999; NHTSA 2016), and all closure options increase the amount of trucking compared to current (baseline) levels. Excavation closure of the WAB to an offsite landfill requires large increases in trucking along highway routes near the Roxboro Plant, in particular along the route between the Roxboro Plant and Duke Energy's neighboring Mayo Plant where ash will be disposed of in an onsite lined landfill (Figure 9-2). There will also be an increased likelihood of accidents along the transportation corridor through which earthen and geosynthetic material is brought to the Roxboro Plant under all closure options. These accidents and associated risks to life, health, and property will 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 along the proposed route between the Roxboro Plant and the Mayo Plant 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 road miles driven by construction trucks (NHTSA 2016). 1707466.000 - 3651 51 Figure 9-2. Map of proposed transportation route between Duke Energy's Roxboro Plant ash basins and the landfill at the Mayo Plant (reproduced from Duke Energy 2018a). The route is approximately 15 miles. 1707466.000 - 3651 52 9.2.1 Noise and Congestion Regardless of the option, closure of the ash basins at Roxboro will result in an increased number of large trucks68 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,69 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 and from the construction site (Table 9-1). CIP closure of both ash basins (CIP/CIP) produces the least number of total daily truck passes of the ten closure options considered, with a total of 111,334 truck passes that would occur at locations along the transportation corridors near the facility over the 54-month course of trucking activities, for an average of approximately 79 passes per day, or one truck every 8 minutes.70 Excavation closure of both ash basins to an offsite landfill (Excavation Offsite/Excavation Offsite) has the largest number of total truck passes, with a total of 1,745,252, averaging 401 truck passes per day, or one truck every 90 seconds for the 14-year duration of the trucking.7' These results and their relative differences (as the ratio between excavation closures 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). CIP closure of both basins (CIP/CIP) requires the fewest total offsite trucking miles, approximately 1.8 million miles of driving, while excavation closure of both basins to an offsite landfill (Excavation Offsite/Excavation Offsite) requires the largest number of trucking miles, with 26.3 million miles of trucking. The 24.5 million mile difference 68 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. 69 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). 70 Excavation closure of both basins to onsite landfills (Excavation Onsite/Excavation Onsite) has the lowest number of average truck passes per day (34); however, this lower average results from a larger total number of total truck passes (176,433) divided by substantially more months of trucking (202 months). 71 All closure options assume 10-hour work days, 6-day work weeks, and 26 working days per month. 1707466.000 - 3651 53 in distance driven between CIP closure of both basins (CIP/CIP) and offsite excavation closure of both basins (Excavation Offsite /Excavation Offsite) is slightly greater than 50 roundtrips to the moon. Table 9-3 summarizes the results for all closure options considered. Table 9-3. Comparative metrics for increased noise and congestion and traffic accidents Noise and congestion Traffic Accidents (EAB/WAB) Months of trucking' Average Ratio to Total offsite Ratio to truck passes per day CIP/CIP road miles driven CIP/CIP CIP/CIP 54 79 1.0 1,756,324 1.0 CIP/EXC OFF 168 328 4.2 21,582,158 12.3 CIP/HYB 86 58 0.7 1,990,576 1.1 EXC OFF/CIP 54 301 3.8 6,477,739 3.7 EXC OFF/EXC OFF 168 401 5.1 26,303,573 15.0 EXC OFF/HYB 86 198 2.5 6,711,991 3.8 HYB/CIP 54 97 1.2 2,155,104 1.2 HYB/EXC OFF 168 335 4.3 21,980,938 12.5 HYB/HYB 86 70 0.9 2,389,356 1.4 EXC ON/EXC ON 202 34 0.43 2,812,545 1.6 a Duration estimates assume simultaneous closure of the EAB and WAB. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer. 9.3 NEBA — 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, traffic congestion, and risk of traffic accidents. I used the number of trucks per day passing72 a receptor along a near -site transportation corridor to examine the differences in noise and traffic congestion under the closure options. I compared 72 Truck passes per day are calculated as the total number of loads required to transport ash (excavation closures to an offsite landfill), earthen fill, and geosynthetic 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. 1707466.000 - 3651 54 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 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 (2018a,b). A baseline estimate of trucking passes per day for the anticipated transportation route between the Roxboro Plant and the Mayo Plant was derived from North Carolina Department of Transportation (NCDOT) data of annual average daily traffic (AADT) at thousands of locations across the state73 and the proportion of road miles driven by large trucks in Person County.74 Based on the assumed 52 trucks per day baseline level and the number of truck trips per day from Duke Energy's projections, the lowest percent impact from noise and traffic congestion for all options was 65% resulting from the additional 34 truck passes per day along the transportation corridor for excavation of both basins to onsite landfills. The highest percent impact from noise and traffic congestion was 770% resulting from an additional 401 truck passes per day along the transportation corridor for excavation closure of both the EAB and WAB to an offsite landfill. I input the percent impacts for these and all other closure options (CIP/Hybrid = I I I %, Hybrid/Hybrid = 134%, and CIP/CIP = 151 %, Hybrid/CIP = 187%, Excavation Offsite/Hybrid = 380%, Excavation Offsite/CIP = 578%, CIP/Excavation Offsite = 632%, Hybrid/Excavation Offsite = 643%) into the risk -ranking matrix (Table 5-4) along with the total duration of trucking activities (Table 9-1) to evaluate which of the closure options best minimizes human disturbances (Table 9-4). 73 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/gpps/webgppviewer/index.html?id=5f6fe58c 1 d9O482ab9l O7cccO3O26280). 74 A value of 540 AADT was chosen as a baseline value for all vehicle traffic by examining the anticipated transportation route for excavated ash between the Roxboro Plant and the landfill at the Mayo Plant 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 (540) was then multiplied by the county average of large truck traffic volume in Person County (9.5%) to derive an estimated 52 passes per day along the most sensitive portion of the transportation corridor between the Roxboro Plant and the Mayo Plant (Appendix E). 1707466.000 - 3651 55 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.75 I chose a baseline of 33.5 million annual road miles for Person County, North Carolina, based on the reported total vehicle miles traveled in Person County (NCDMV 2017) multiplied by the county average 9.5% 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. Using the 33.5-million-truck-miles baseline assumption, excavation closure to onsite landfills (Excavation Onsite/Excavation Onsite) has the lowest percent impact (0.5%) of the ten closure options considered. Excavation of both the EAB and WAB to an offsite landfill (Excavation Offsite/Excavation Offsite) has the highest impact (5.6%) of the closure options considered. The relative risk ratings appear to be only slightly sensitive to lower assumed baseline annual truck miles (see Appendix E for sensitivity analysis). Results for these and other options (CIP/Hybrid = 0.83%, Hybrid/Hybrid = 0.99%, CIP/CIP = 1.2%, Hybrid/CIP = 1.4%, Excavation Offsite/Hybrid = 2.8%, Excavation Offsite/CIP = 4.3%, CIP/Excavation Offsite = 4.6%, and Hybrid/Excavation Offsite = 4.7%) are summarized in the NEBA framework (Table 9-4) within the objective of minimizing disturbance to humans during closure. 75 The difference of baseline miles and closure option miles was divided by the baseline miles and multiplied by 100 to get a percent impact. 1707466.000 - 3651 56 Table 9-4. 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 Noise and Traffic Hazard Traffic Air Pollution Congestion Accidents N C � O r L L U) Q Q X O w a > > E V c =3 E a> c m m a) a Q a, — Ca FU CO R U O U O rZ O = J J N O a Scenario (EAB/WAB) Baseline baseline baseline baseline CIP/CIP 3A -- CIP/Excavation Offsite 4A -- CIP/Hybrid 3A -- Excavation Offsite/CIP 3A -- Excavation Offsite/Excavation Offsite I 4B -- Excavation Offsite/Hybrid 3A -- Hybrid/CIP 3A -- Hybrid/Excavation Offsite 4A -- Hybrid/Hybrid 3A -- Excavation Onsite/Excavation Onsite 5A -- --" indicates "no meaningful risk." All closure options create disturbance and risk to human populations along the transportation corridors near the Roxboro Plant, especially on the route between the Roxboro Plant and the Mayo Plant under excavation closures to an offsite landfill; however, the magnitude and duration of impacts to the community are substantially greater for options that include excavation closure to an offsite landfill of either or both ash basins.76 The large amount of 76 Sensitivity analyses exploring different assumptions and subsequent effects to relative risk ratings are provided in Appendix E. 1707466.000 - 3651 57 trucking required for excavation closure to an offsite landfill for both basins creates the greatest potential for risk and disturbance to local communities. Excavation of both the EAB and WAB to onsite landfills produces the lowest daily and annual impacts compared to other closure options, but this closure option also affects the community for longest duration (almost 17 years). CIP and hybrid closure options produce slightly higher daily disturbance to the community from truck passes and similar and negligibly low increased annual risk from traffic accidents compared to excavation closure to onsite landfills; however, CIP and hybrid closures require a substantially shorter duration (4.5 years for CIP and just over 7 years for hybrid closures) and may better satisfy the third objective of ash basin closure —to minimize risk and disturbance to humans from closure —depending on stakeholder preferences.77 77 If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 - 3651 58 10 Conclusion 4: Most closure options for the Roxboro ash basins produce a net loss of habitat -derived environmental services. Environmental services are derived from ecological processes or functions that provide value to individuals or society, with the 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;78 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. The Roxboro Plant, 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 WAB provides habitat that supports birds and mammals; the open water habitat of the WAB 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 Hyco Lake. 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 the Roxboro Plant, Hyco Lake provides aquatic habitat that supports a variety of fish and aquatic life (Duke Energy 2017), which then provide food for birds and mammals. 78 Bald eagles were taken off the federal list of threatened and endangered species in 2007 (https://www.fws.gov/midwest/eagle/). 1707466.000 - 3651 59 LEGEND ❑ Ash basin ❑ Wetland ❑ Open field ❑ Open water ice,+ ❑ Wooded area n0 0.5 Miles l I ��huu\\ 0 Figure 10-1. Map of habitat types currently present at the Roxboro Plant Kibmelers 1707466.000 -3651 .2 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. ,79 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.80 The fourth objective for ash basin closure, to minimize local 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 closures result in greater net losses of environmental services than other closure options. 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, and temporary removal of forest habitat to create a borrow pit to source earthen materials for the cap. Excavation and landfilling require temporary loss and future modification of existing habitats within the footprint of the ash basin and permanent conversion of forest and other habitat to grass cap at the landfill site. The hybrid option requires temporary loss and future modification of existing habitats within the footprint of the ash basin. All closure options include restoration of the ash basin footprint, but the collateral losses of habitat, the differences 79 htWs://earthobservatoiy.nasa.izov/GlobalMaps/view.php?dl=MOD17A2_M PSN 80 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. 1707466.000 -3651 61 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 Service81 and NOAA82 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 its 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 service 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 basins are closed. After closure is complete, there will be a new level of 81 www.doi.gov/restoration 82 wWW.duM.noaa.goy 1707466.000 -3651 62 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 basins 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 basins produce NPP that is 25% that of natural ecosystems.83 Therefore, I applied a four -fold habitat quality factor to scale NPP at these open water areas of the ash basins 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 an NPP service value of 8%,84 as was done for CIP. 83 I observed open water areas of the ash basins that supported aquatic vegetation but do not know the extent of vegetation in the open water areas of the ash basins. Thus, I made a conservative assumption (i.e., one that reduces the present value of the habitat) that these areas of the ash basins provide a reduced level of NPP compared to natural open freshwater areas. 84 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. 1707466.000 -3651 63 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 options, 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.85 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 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 10-1 and indicate that closure of the WAB is the most important determinant of the net habitat -derived environmental services resulting from closure. Seven closure options will result in a net loss of environmental services, while the three closure options that include hybrid closure of the WAB produce a net gain in environmental services as indicated by a positive DSAY total. Net losses of environmental services are due primarily to loss of forest habitat for borrow and landfill areas and reduced NPP services provided by a grass cap. 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. Closure options that include hybrid closure of the WAB, however, reduce the footprint of grass cap and restore forest sooner than options that include excavation of the basin. 85 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. 1707466.000 -3651 64 Table 10-1. Summary of NPP DSAYs for CIP and excavation closure options CIP/ EXC OFF/ EXC OFF/ EXC OFF/ HYB/ EXC ON/ (EAB/WAB) CIP/CIP EXC OFF CIP/HYB CIP EXC OFF HYB HYB/CIP EXC OFF HYB/HYB EXC ON Ash basin losses Open Field -450 -437 -450 -450 -437 -450 -450 -437 -450 -437 Grass Cap -1 -1 -1 -1 -1 -1 -1 -1 -1 -197 Open Water -313 -305 -313 -313 -304 -313 -313 -304 -313 -304 Wetland -126 -123 -126 -126 -123 -126 -126 -123 -126 -124 Wooded -155 -155 -155 -150 -150 -150 -150 -150 -150 -183 Total losses -1,046 -1,021 -1,046 -1,040 -1,014 -1,040 -1,040 -1,014 -1,040 -1245 Ash basin post- Open Field 351 665 401 557 871 607 351 665 401 947 closure gains Grass Cap 521 140 310 381 0 170 486 105 275 0 Open Water 100 365 427 92 356 418 97 362 424 312 Stream 9 2 3 12 5 1 10 3 12 Wetland 2 2 2 3 3 1 2 2 5 Wooded 98 1,665 1,199 983 2,550 2,084 419 1,986 1,520 3769 Total gains 1,070 2,844 2,341 2,017 3,792 3,288 1,355 3,129 2,626 5044 Landfill/borrow Wetland -3 losses Forest -1,425 -4,175 -1,660 -2,267 -5,016 -2,501 -1,440 -4,189 -1,675 -6008 Open Field -495 Open Water -62 Total losses -1,425 -4,175 -1,660 -2,267 -5,016 -2,501 -1,440 -4,189 -1,675 -6569 Landfill/borrow Forest 1,033 724 1,155 721 412 843 769 460 891 792 post -closure gains Grass Cap 161 84 245 84 26 187 26 273 Total gains 1,033 884 1,155 805 656 927 795 647 917 1065 Net Gain/Loss per site -369 -1,467 790 -484 -1,582 675 -330 -1,428 829 -1704 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. Closure duration estimates assume simultaneous closure of the EAB and WAB. A construction feasibility analysis of this assumption has not been conducted. If the basins were to be closed sequentially, the duration of the estimated closure for each option would be substantially longer and change the results of the HEA. 1707466.000 -3651 65 10.2 NEBA — Minimize Local Environmental Disturbance The impact of the closure options on habitat -derived 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 net DSAYs by the absolute value of the DSAY losses provides a percentage of the impact. A summary of the percent impacts is provided in Table 10-2.86 I input these percent impacts to the risk -ranking matrix (Table 5-4) along with the duration of the closure activities (Table 4-1) to evaluate, within the NEBA construct, which of the closure options best minimizes local environmental disturbances (Table 10-3). Table 10-2. Percent impact of ash basin closure options CIP/ CIP/ EXC OFF/ EXC OFF/ EXC OFF/ HYB/ HYB/ HYB/ EXC ON/ (EAB/WAB) CIP/CIP EXC OFF HYB CIP EXC OFF HYB CIP EXC OFF HYB EXC ON DSAY Losses 2,471 5,195 2,706 3,306 6,030 3,541 2,479 5,204 2,714 7,813 DSAY Gains 2,102 3,728 3,496 2,822 4,448 4,215 2,150 3,776 3,543 6,109 Percent Impact (%) 15% 28% 0% 15% 26% 0% 13% 27% 0% 22% 86 As noted in Section 5 and discussed in more detail in Section 11, habitat impact could be offset with an appropriate reforestation project. 1707466.000 -3651 66 Table 10-3. Summary of relative risk ratings for habitat changes that affect protection of biodiversity and natural beauty. Darker shading/higher codes indicate greater impact. Minimize Local Objective Environmental Disturbance Hazard I Habitat Change Attribute I Service Acres Scenario (EAB/WAB) Baseline baseline CIP/CIP 3B CIP/Excavation Offsite 4C CIP/Hybrid -- Excavation Offsite/CIP 3B Excavation Offsite/Excavation Offsite 4C Jim Excavation Offsite/Hybrid -- Hybrid/CI P 3 Hybrid/Excavation Offsite Hybrid/Hybrid -- Excavation Onsite/Excavation Onsite --" indicates "no meaningful risk." Within the objective of minimizing local environmental disturbance from closure, my analyses indicate that all closure options as currently defined that include hybrid closure of the WAB produce comparable net benefits in habitat -derived environmental services, regardless of the closure option selected for the EAR All other closure options as currently defined produce net losses of habitat -derived services, though CIP closure of the WAB results in a relatively small net DSAY loss that is substantially less than the net loss under any excavation closure of the WAR Closure options that include hybrid closure of the WAB best satisfy the fourth objective of ash basin closure —to minimize risk and disturbance to the local environment from closure.$$ 87 Note that the environmental services lost due to the currently defined CIP closure could be offset (see discussion in Section 11) by a suitable reforestation project that would then result in CIP closure producing no net loss of habitat -derived environmental services in the HEA model. 88 If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 -3651 67 11 Conclusion 5: CIP or hybrid closure of the EAB and hybrid closure of the WAB maximize local environmental services. Identifying environmental actions that maximize local 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 that the specific relative risk ratings presented in this NEBA can change depending on how impact 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 local environmental services 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 the Roxboro Plant is CIP closure of both basins but the HEA results for the currently defined CIP closure option estimate a net environmental service loss of an approximate 369 DSAYs, Duke 1707466.000 -3651 68 Energy could consider incorporating into an updated CIP closure plan for the Roxboro Plant a mitigation project that compensates for the net environmental service losses projected from the currently defined CIP closure option. As an example, if Duke Energy started a reforestation project outside of the ash basin in 2021 (when onsite preparation of the ash basin begins), the reforestation project would gain 25.1 DSAYs/acre over the lifetime of the site (150 years in the HEA), requiring an approximate 14.7 acre project to compensate for the 369 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 basins for CIP closure. 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 CIP or hybrid closure of the EAB and hybrid closure of the WAB (CIP/Hybrid or Hybrid/Hybrid) best maximize local environmental benefits compared to the other closure options, among the closure options as currently defined, because they offer equivalent protection of human and ecological health from CCR exposure, result in less disturbance to the community over time compared to excavation closure to an offsite landfill, and produce net gains in habitat -derived environmental services. Thus, CIP or hybrid closure of the EAB and hybrid closure of the WAB (CIP/Hybrid or Hybrid/Hybrid) best satisfy the fifth objective of ash basin closure —to maximize local environmental services.89 89 If for any reason (e.g., safety of personnel), the basins cannot be closed simultaneously, the duration of closure activities would be additive to an unknown degree for each basin, which has not been considered in my analyses and may change risk ratings and NEBA conclusions. 1707466.000 -3651 69 Table 11-1. NEBA for closure of the ash basins at the Roxboro Plant. Darker shading and higher codes indicate greater impact. Protect Human Minimize Objective Health from Protect Ecological Health from CCR Minimize Human Disturbance Environmental CCR Disturbance Exposure to Noise and Traffic Air Hazard Exposure to CCR Traffic Habitat Change CCR Accidents Pollution Congestion O E O O O O m Ro U n U) o E � E E O Q- n N C E a m CoU5 -2m E E O O WC a > O � co 0g > > Ea) 0- o >> °> ^x ° E � E > c oo > O E M 3 o c -O X DSAYs 0- UNN O a)T 0 Q � Q �° °' �' �' 0 0 0 O 0- Q Q 0) J J (6 O Q 0) � a Scenario (EAB/WAB) Baseline -- -- -- -- -- -- -- -- -- -- -- -- -- baseline baseline baseline baseline CIP/CIP -- -- -- -- -- -- -- -- -- -- -- -- -- 3 A -- 313 CIP/EXC OFF -- -- -- -- -- -- -- -- -- -- -- -- -- 4A -- 4C CIP/HYB -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- -- EXC OFF/CIP -- -- -- -- -- -- -- -- -- -- -- -- - 3A -- 313 EXC OFF/EXC OFF -- -- -- -- -- -- -- -- -- -- -- -- - 413 -- 4C EXC OFF/HYB -- -- -- -- -- -- -- -- -- -- -- -- -- 3A I -- -- HYB/CIP -- -- -- -- -- -- -- -- -- -- -- -- -- 3A -- 313 HYB/EXC OFF -- -- -- -- -- -- -- -- -- -- -- -- -- 4A -- 4C HYB/HYB -- -- -- -- -- -- -- -- -- -- -- -- -- I 3A -- EXC ON/EXC ON -- -- -- -- -- -- -- -- -- -- -- -- -- 5A -- 5C --" indicates no meaningful risk. 1707466.000 -3651 70 12 References Bishop, J., and N. 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Amec Foster Wheeler Environment & Infrastructure, Inc. May 16, 2018. 1707466.000 -3651 74 Appendix A Curriculum Vitae of Dr. Ann Michelle Morrison, Sc.D. 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 relationships 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. 12/17 1 Pagel 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 Ecology 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 of recombinant zebrafish sterol 14a-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. 12/17 1 Page 2 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 Rainfall 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 P4501 gene family: Evidence 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 Organisms (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. 12/17 1 Page 3 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, FL. 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, FL. 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 Misapplication 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 1 Page 4 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 P4501 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 1 Page 5 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 toxicity, 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 mercury 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 1 Page 6 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 Fisheries 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, water 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 (MPAs) 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 management, 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 used 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. Ann Michelle Morrison, Sc.D. 12/17 1 Page 7 Appendix B Human Health and Ecological Risk Assessment Summary Update for Roxboro Steam Electric Plant 410 synTerra HUMAN HEALTH AND ECOLOGICAL RISK ASSESSMENT SUMMARY UPDATE For ROXBORO STEAM ELECTRIC PLANT 1700 DUNNAWAY ROAD SEMORA, NORTH CAROLINA 27343 NOVEMBER 2018 PREPARED FOR DUKE ENERGY PROGRESS, LLC 410 SOUTH WILMINGTON STREET RALEIGH,. NORTH CAROLINA 27601 (ft� DUKE t, ENERGY PROGRESS 1, 4z, d, ey, �,- � - Matt Huddleston, Ph.D. Senior Scientist Heather Smith Environmental Scientist Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant SynTerra 1.0 INTRODUCTION This update to the Roxboro Steam Electric Plant (Roxboro or Site) human health and ecological risk assessment incorporates results from sampling events conducted March 2000 through May 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 Roxboro ash basins do not cause any increase in risks to human health for potential human receptors located on -Site or off -Site; and (2) the Roxboro ash basins do not cause any increase in risks to ecological receptors. The original 2016 risk assessment was a component of the Corrective Action Plan Part 2 pertaining to Roxboro (SynTerra, 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 wth 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 2017 Comprehensive Site Assessment (CSA) Update report (SynTerra, 2017). This update follows the methods of the 2016 risk assessment (SynTerra, 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," are being addressed in the ongoing renewal of the 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 S18-005). 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 S18-005, 2. d.). This risk assessment update includes results from samples of surface water, sediment, and groundwater collected since the 2017 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 Page 1 Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant SynTerra potential risks, and exposure areas are depicted in Figures 3 and 4. 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 human exposure areas reduced from two to one (Figure 3), and the number of ecological exposure areas reduced from five to two (Figure 4). Other exposure areas evaluated in the 2016 risk assessment were eliminated because either they are not influenced by groundwater migration from the ash basins (Hyco Lake) or because they have been recognized as part of the ash basins (Western Ash Basin Extension Impoundment and Eastern Ash Basin Extension Impoundment). As part of the permitted wastewater treatment facilities, these areas need not be included. Off -Site exposures at Hyco Lake have been excluded. Surface water from the ash basins flows through NPDES- permitted outfalls before reaching Hyco Lake. Updated modeling shows no direct groundwater impacts to Hyco Lake. 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. Page 2 Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant SynTerra 2.0 SUMMARY OF RISK FINDINGS 2.1 Human Health There is no exposure to residential or other off -Site receptors at Roxboro, because groundwater migrating from the ash basins is not reaching off -Site receptors. Potential receptors on -Site include trespasser and construction worker. However, background concentrations of the same elements also present similar risks to the same potential receptors. These risks are not associated with the ash basins. • There is no increase in cancer risks attributable to the ash basins associated with the trespasser exposure scenario. o There is no increase in cancer risks for the trespasser exposure scenarios attributable to the ash basins. Incorporating hexavalent chromium concentrations in surface water samples collected since the 2017 CSA update produced modeled potential carcinogenic risks under the trespasser scenario. However, hexavalent chromium concentrations in upgradient surface water (maximum 0.07 µg/L) were greater than the EPC (0.05 µg/L) calculated based upon sampling data for use in the risk assessment. The ash basins at Roxboro, therefore, do not increase the modeled risks. o No evidence of non -carcinogenic risks for the trespasser exposure scenario was identified. • There is no evidence of risk associated with the constructions worker exposure scenario. o There is no increase in health risks for the construction worker exposure scenario. The updated risk assessment found no evidence of risks associated with exposure to groundwater by Site workers. In summary, there is no increase in risks to human health attributable to the Roxboro ash basins. Page 3 Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant SynTerra 2.2 Ecological Surface water and sediment results were used to evaluate potential risks to aquatic and terrestrial receptors associated with the Eastern Discharge Canal (EDC) exposure area and aquatic receptors associated with the Water Intake Basin (WIB) exposure area (Figure 4 and Attachment 6). • 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. • NOAEL based HQs related to aluminum in sediment samples and surface water samples were greater than unity for the American robin (HQ =1.5), meadow vole HQ = 36.5), red fox (HQ = 25.1), and muskrat (HQ = 2.5) in the EDC exposure area. • LOAEL based HQs related to aluminum in sediment and surface water samples were greater than unity for the meadow vole (HQ = 3.7) and red fox (HQ = 2.5). • The modeled risk related to aluminum is negligible and likely overstates 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). Aluminum concentrations in the upstream sample collected from the WIB were 338 µg/L and the concentration in sediment was 34,000 mg/kg. Comparatively, the aluminum EPCs used in the risk assessment were 1,350 µg/L in surface water and 22,000 mg/kg in sediments in the EDC exposure area. Using the background aluminum concentrations in the models also indicates similar risks. In summary, the Roxboro ash basins do not cause any increase in risks to ecological receptors. Page 4 Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant SynTerra 3.0 REFERENCES SynTerra. (2016). Corrective Action Plan Part 2 - Roxboro Steam Electric Plant, February 29, 2016. SynTerra. (2017). 2017 Comprehensive Site Assessment Update, October 31, 2017. 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. United States Geological Survey. (2018, October 29). Aluminum Statistics and Information. Retrieved from https:Hminerals.usgs.gov/minerals/pubs/commodity/aluminum/ Page 5 Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant FIGURES SynTerra Primary Primary Secondary Sources Release Sources Mechanisms Active Coal Ash Infiltration/ Post Excavation Basin Leaching Soil Run off/Flooding Infiltration/ Leaching Groundwater AOWs (a) Secondary Potential Release Exposure Mechanisms Media Dust 0 Outdoor Air Soil Remaining Post -Excavation (b) Surface Water (Off - s it e) (c) Migration to Surface Water and Sediment Sediment (Off - s it e) (c) Fish Tissue (d) NOTFS Potentially complete exposure pathway based on results of 2018 risk assessment update. O Pathway evaluated and found incomplete/insignificant. (a) Areas of wetness (AO Ws) are addressed in the Special Order by Consent (SOC) and not evaluated in the risk assessment update at this time. (b) Pathway incomplete as long as ash remains in place; re-evaluation upon excavation (if conducted) may be warranted. (c) Hyco Reservoir. (d) Concentration of COPC in fish tissue modeled from surface water concentration. (e) Incidental surface water ingestion assumed only to occurfor receptors for the swimming and wading scenarios.. (f) Groundwater exposure evaluated in the risk assessment update, although an i ncomplete exposure pathway for construction worker.. Groundwater AOW Water (On -site) AOW Soil (On -site) Surface Water (On -site) F(on-Sement site) Human Receptors Current/ Current/ Current/ Current/ Current/ Current/ Current/ Current/ Potential Future Off -Site Future On -site Future Off -Site Future On -Site Future Off -Site Future Off -Site Future Off -Site Future On -Site Exposure Recreational / Commercial/ Resident Recreational Recreational Recreational Recreational Construction Route Adult/Child Trespasser Swimmer Wader Boater Subsistence Industrial Worker Fisher Worker Inhalation O O O O O O O O Incidental O O O O O O O O Ingestion Dermal Contact O O O O O O O O Drinking Water O O O O O O O O Use (e) Incidental O O O(e) O(e) O O O O Ingestion Dermal Contact O O O O O O O O Incidental O O O O _F Ingestion Dermal Contact O O O O Ingestion O O O O Drinking Water O O O O Use Incidental O O O O Ingestion Dermal Contact O O O O Dermal Contact I O O O O O O O O O O O O O O O O O O O O O O O O (f) O O O O (f) Dermal Contact O O O O O Incidental Ingestion O • O O O Dermal Contact O O O O O Incidental Ingestion O O O O O Dermal Contact O O O O O L' synTerra O O O O O O O O O O O O O O O FIGURE 1 HUMAN HEALTH RISK ASSESSMENT CONCEPTUAL SITE MODEL ROXBORO STEAM ELECTRIC PLANT SEMORA, NORTH CAROLINA Primary Sources Primary Release Secondary Mechanisms Sources Active Coal Ash Basin Infiltration/nPostvation (a)Leachingl Runoff/Flooding Infiltration/ Leaching Groundwater AOWs (a) AQUATIC RECEPTORS TERRESTRIAL RECEPTORS Avian (e) Mammal Avian Mammal Secondary Release Potential Potential Fish Benthic Great Blue Red -Tailed Mechanisms Exposure Media Exposure Route Invertebrates Mallard Heron Muskrat River Otter Robin Hwk Meadow Vole Red Fox (Omnivore) (p sc ore) (Herbivore) (Piscivore) (Omnivore) (Cara vore) (Herbivore) (Carnivore) Dust Outdoor Air Inhalation O O O O O O O O O O Plant/Incidental Soil Remaining Ingestion O O O O O O O O O O Post -Excavation (b) Direct Contact O O O O O O O O O O Ingestion O O O O O O O O O O Surface Water (Off -site) Direct Contact O(d) O(d) O O O O O O O O tion to Plant/Incidental O O O O O O O O O O e Water F Sediment Ingestion ediment (Off -site) Direct Contact O O(d) O O O O O O O O LD Fish Tissue NOTES Potentially complete exposure pathways based on results o 2018 risk assessment update. O Pathway evaluated and found incomplete/insignificant. (a) Areas of wetness (AOWs) are addressed in the Special Order by Consent (SOC) and not evaluated in the risk assessment update at this time. (b) Pathway incomplete as long as ash remains in place; re-evaluation upon excavation (if conducted) may be warranted. (c) Concentration of COPC in fish tissue modeled fromsurface water concentration. (d) Based on screening against aquatic life criteria. (e) Bald eagle (carnivore) included in the ecological risk assessment. Ingestion O O O O O O O O O O Ingestion G roun dwater Direct Contact AOW Water Ingestion (On site) AOW Soil (On -site) O O O O O O O O O O O O O O O O O O Ingestion O O O O O O O • • •(d) O O O O O O • • O O O O O • • • • •(d) O O O O O O • • AL FIGURE 2 ECOLOGICAL RISK ASSESSMENT CONCEPTUAL SITE MODEL synTerra ROXBORO STEAM ELECTRIC PLANT SEMORA, NORTH CAROLINA r--1 1 a 9 HYCO LAK w - - EDC-05 KE RSW RSW AI COOLING WATER ROXBORO STEAM INTAKE BASIN GYPSUM STORA GE ELECTRIC PLANT RSW-1 AREA �ILR RSW-2 EDC-03 i 7 14 d., r •-4 .. i 1 rr - r� 0 350 700 1,400 2,100 synTerra IN FEET 148 RIVER STREET, SUITE 220 GREENVILLE, SOUTH CAROLINA 29601 w19999 PHONE 864 mxorn rr r . ww. n co DUKE DRAWN BY A FEIGL DATE 10/30/2018 CHECKED BY: K. CAWING ENERGY PROGRESS PROJECT MANAGER: C. EADY P:\Duke En— Pro —A U0 00 GIS BASE DATA\Roxboi LEGEND ■ SURFACE WATER LOCATION GYPSUM STORAGE EXPOSURE AREA/ ASH BASIN EXPOSURE AREA HYCO LAKE EXPOSURE AREA :']DUKE ENERGY PROGRESS ROXBORO PLANT L-::: —' COMPLIANCE BOUNDARY WASTE BOUNDARY — I STREAM LANDFILL AREA NOTES: 1) PROPERTY BOUNDARY PROVIDED BYDUKE ENERGYPROGRESS 2) THERE ARE NO SURFACE WATER OR GROUNDWATER INPUTS TO HYCO LAKE FROM THE ASH BASIN, EXCEPT FOR NPDES PERMITTED INPUTS. THEREFORE, HYCO LAKE WAS NOT EVALUATED AS PART OF THIS ASSESSMENT. 3) AERIAL PHOTOGRAPHY OBTAINED FROM GOOGLE EARTH PRO ON SEPTEMBER 27, 2017. AERIAL WAS COLLECTED ON JUNE 13, 2016. 4) DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CAROLINA STATE PLANE COORDINATE SYSTEM RIPS 3200 (NAD83/2011). FIGURE 3 EXPOSURE AREAS HUMAN HEALTH RISK ASSESSMENT ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC SEMORA,oNORTH CAROLINA r'.$ s t •, i "N v - roo s \ �• � -ram■. ■ • E. J 0100.00101 r . a -aa a• IMPOUNDMENT as \ < AV as , ■ r )OLING WATER TAKE BASIN (POSURE AREA RN DISCHARGE CANAL URE AREA 4 ■ ■ -q! kftma. 14 e 1 ■■ 0 350 700 1,400 2,100 synTerra IN FEET 148 RIVER STREET, SUITE 220 GREENVILLE, SOUTH CAROLINA 29601 wwwPO ynt64 4219999 . DUKE DRAWN BY A FEIGL DATE 10/30/2018 CHECKED BY: K. CAWING ENERGY PROJECT MANAGER: C. EADY PROGRESS P:\Duke Enerav Pro ress.1026\00 GIS BASE DATA\Roxboi LEGEND ■ SURFACE WATER LOCATION EASTERN DISCHARGE CANAL EXPOSURE AREA COOLING WATER INTAKE BASIN EXPOSURE AREA GYPSUM STORAGE AREA EXPOSURE AREA 4 EAB EXTENSION IMPOUNDMENT EXPOSURE AREA HYCO LAKE EXPOSURE AREA 7DUKE ENERGY PROGRESS ROXBORO PLANT L-::: —' COMPLIANCE BOUNDARY WASTE BOUNDARY —)0- STREAM LANDFILL AREA NOTES: 1) PROPERTY BOUNDARY PROVIDED BYDUKE ENERGYPROGRESS 2) GREY SHADED EXPOSURE AREAS ELIMINATED FROM THE RISK ASSESSMENT BECAUSE THEY REPRESENT THE ASH BASINS, AREAS OF WETNESS, OR LOCATIONS NOT INFLUENCED BY GROUNDWATER MIGRATION FROM THE ASH BASINS. 3) AERIAL PHOTOGRAPHY OBTAINED FROM GOOGLE EARTH PRO ON SEPTEMBER 27, 2017. AERIAL WAS COLLECTED ON JUNE 13, 2016. 4) DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CAROLINA STATE PLANE COORDINATE SYSTEM RIPS 3200 (NAD83/2011). FIGURE 4 EXPOSURE AREAS ECOLOGICAL RISK ASSESSMENT ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC SEMORA, NORTH CAROLINA n n... i—lla —,n Ri<k A---t\Fm0A R—hnrn Frn1—i-1 —d Risk Assessment Summary Update November 2018 Roxboro Steam Electric Plant ATTACHMENTS SynTerra TABLE 1-1 HUMAN HEALTH SCREENING - GROUNDWATER (SAPROLITE) ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyto CAS Number of Samples Frequency of Detection Range of Detection (Ng/L) Concentration Used for Screening (pg/L) 15A NCAC 02L .0202 Standard (e) (pg/L) 15A NCAC 02L .0202 IMAC (e) (Ng/L) DHHS Screening Level (d) OWL) Federal MCL/ SMCL (c) (N9/L) Tap Water RSL HI = 0.2 (a) (p9/L) Screening Value Used (N9/L) COPC- Min. Max. Aluminum 7429-90-5 13 12 6 133 133 NA NA 3,500 50 to 200 (i) 4,000 3,500 N Antimony 7440-36-0 85 0 ND ND ND 1 NA 1 6 1.56 (m) 1 N Arsenic 7440-38-2 108 28 1.01 24.4 24.4 10 NA 10 10 0.052 (h,jj) 10 Y Barium 7440-39-3 108 108 49 855 855 700 NA 700 2,000 760 700 Y Beryllium 7440-41-7 83 0 ND ND ND NA 4 4 4 5 4 N Boron 7440-42-8 85 77 105 40,600 40,600 700 NA 700 NA 800 700 Y Cadmium 7440-43-9 83 0 ND ND ND 2 NA 2 5 1.84 2 N Chromium (Total) 7440-47-3 108 25 0.725 17.2 17.2 10 NA 10 100 4,400 (n) 10 Y Chromium (VI) 18540-29-9 10 5 0.058 0.14 0.14 NA NA 0.07 NA 0.035 (A) 0.07 Y Cobalt 7440-48-4 85 72 0.975 43.4 43.4 NA 1 1 NA 1.2 1 Y Copper 7440-50-8 13 5 0.534 1.68 1.68 1,000 NA 1,000 1,300 (k) 160 1,000 N Lead 7439-92-1 85 0 ND ND ND 15 NA 15 15 (1) 15 (jj) 15 N Lithium 7439-93-2 76 28 5 17 17 NA NA NA NA 8 8 Y Manganese 7439-96-5 13 13 22 4,180 4,180 50 NA 200 50 (i) 86 50 Y Mercury 7439-97-6 85 16 0.05 0.19 0.19 1 NA 1 2 1.14 (o) 1 N Molybdenum 7439-98-7 85 70 0.672 266 266 NA NA 18 NA 20 18 Y Nickel 7440-02-0 13 10 3.64 8.23 8.23 100 NA 100 NA 78 (p) 100 N Selenium 7782-49-2 108 7 2 6.91 6.91 20 NA 20 50 20 20 N Strontium 7440-24-6 13 13 493 2,580 2,580 NA NA 2,100 NA 2,400 2,100 Y Thallium 7440-28-0 85 1 0.211 0.211 0.211 0.2 NA 0.2 2 0.04 (q) 0.2 Vanadium 7440-62-2 13 13 4.25 6.39 6.39 NA NA 0.3 NA 17.2 0.3 Zinc 7440-66-6 13 3 3.874 7 7 1 NA 1 5,000 (i) 1,200 1 ]LJ * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources NC - North Carolina CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services NCAC - North Carolina Administrative Code North Carolina Session Law 2014-122, ESV - Ecological Screening Value ORNL - Oak Ridge National Laboratory htto://www.ncleg.net/Sessions/2013/Bills HH - Human Health PSRG - Preliminary Soil Remediation Goal /Senate/PDF/S729v7.pdf HI - Hazard Index Q - Qualifier CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration RSL - Regional Screening Level CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level RSV - Refinement Screening Value 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 Prepared by: HEG Checked by: HES su - Standard units Pg/L - micrograms/liter USEPA - United States Environmental Protection Agency WS - Water Supply < - Concentration not detected at or above the reporting limit j - Indicates concentration reported below Practical Quantitation Limit (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated Page 1 of 2 TABLE 1-1 HUMAN HEALTH SCREENING - GROUNDWATER (SAPROLITE) ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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/reg ional-screeni ng-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/nationa I-recom mend ed-water-q ua lity-criteria-h u ma n-hea lth-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/docu ments/dwtab le20l8. 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&folderld=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=laa3fal3-2cOf-45b7-ae96-5427fbld25b4&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-%20envi ron menta I"/o20q ual ity/chapter°/n2002%20-%20environ mental%20ma nagement/subchapter°/u20b/subchapter%20b%20ru les. pdf WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption offish 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/prod uction/files/2018-03/docu ments/era_reg ional_su pp lemental_g uid a nce_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/dwstanda rdsreg ulations/seconda ry-d rin ki ng-water-standards-guidance-nuisance-chemicals (j) - Value for Total Chromium. (k) - Copper Treatment Technology Action Level is 1.3 mg/L. (1) - 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/[(fl/CMCS) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMCS and CMC2 are 185.9 p/gL and 12.82 p/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 V/gL. (w) - Applicable only to persons with a sodium restrictive diet. (x) - Los Alamos National Laboratory ECORISK Database. http://www.lani.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 (pg/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.orni.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.orni.gov/programs/ecorisk/documents/tml26r2l.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.orni.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=Of60lffa-574d-4479-bbb4-253af0665bf5&groupId=38361 (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 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 Page 2 of 2 TABLE 1-2 HUMAN HEALTH SCREENING - GROUNDWATER (TRANSITION/BEDROCK) ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyto CAS Number of Samples Frequency of Detection Range of Detection (Ng/L) Concentration Used for Screening (pg/L) 15A NCAC 02L .0202 Standard (e) (pg/L) 15A NCAC 02L .0202 IMAC (e) (Ng/L) DHHS Screening Level (d) OWL) Federal MCL/ SMCL (c) (N9/L) Tap Water RSL HI = 0.2 (a) (p9/L) Screening Value Used (N9/L) COPC- Min. Max. Aluminum 7429-90-5 700 641 2.253 6,130 6,130 NA NA 3,500 50 to 200 (i) 4,000 3,500 Y Antimony 7440-36-0 1,105 24 0.336 2.85 2.85 1 NA 1 6 1.56 (m) 1 Y Arsenic 7440-38-2 1,298 211 0.004 32 32 10 NA 10 10 0.052 (h,jj) 10 Y Barium 7440-39-3 1,298 1,276 5 1,610 1,610 700 NA 700 2,000 760 700 Y Beryllium 7440-41-7 1,002 11 1.02 17.3 17.3 NA 4 4 4 5 4 Y Boron 7440-42-8 1,220 550 3.9 53,800 53,800 700 NA 700 NA 800 700 Y Cadmium 7440-43-9 1,286 25 0.033 119 119 2 NA 2 5 1.84 2 Y Chromium (Total) 7440-47-3 1,298 330 0.034 824 824 10 NA 10 100 4,400 (n) 10 Y Chromium (VI) 18540-29-9 475 219 0.025 7.1 7.1 NA NA 0.07 NA 0.035 (A) 0.07 Y Cobalt 7440-48-4 1,014 289 0.381 755 755 NA 1 1 NA 1.2 1 Y Copper 7440-50-8 893 250 0.354 4,700 4,700 1,000 NA 1,000 1,300 (k) 160 1,000 Y Lead 7439-92-1 1,298 38 0.0744 126 126 15 NA 15 15 (1) 15 (jj) 15 Y Lithium 7439-93-2 522 170 1.993 739 739 NA NA NA NA 8 8 Y Manganese 7439-96-5 893 689 0.231 30,000 30,000 50 NA 200 50 (i) 86 50 Y Mercury 7439-97-6 1,298 48 0.017 1.11 1.11 1 NA 1 2 1.14 (o) 1 Y Molybdenum 7439-98-7 1,014 759 0.13 3,140 3,140 NA NA 18 NA 20 18 Y Nickel 7440-02-0 815 320 0.364 808 808 100 NA 100 NA 78 (p) 100 Y Selenium 7782-49-2 1,298 312 0.103 416 416 20 NA 20 50 20 20 Y Strontium 7440-24-6 595 594 67 6,320 6,320 NA NA 2,100 NA 2,400 2,100 Y Thallium 7440-28-0 1,220 44 0.059 6.8 6.8 0.2 NA 0.2 2 0.04 (q) 0.2 Y Vanadium 7440-62-2 602 540 0.129 41.5 41.5 NA NA 0.3 NA 17.2 0.3 Y Zinc 7440-66-6 893 277 1.1 16,800 16,800 1 NA 1 5,000 (i) 1,200 1 Y * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources NC - North Carolina CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services NCAC - North Carolina Administrative Code North Carolina Session Law 2014-122, ESV - Ecological Screening Value ORNL - Oak Ridge National Laboratory htti)://www.ncleg.net/Sessions/2013/Bills HH - Human Health PSRG - Preliminary Soil Remediation Goal /Senate/PDF/S729v7.pdf HI - Hazard Index Q - Qualifier CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration RSL - Regional Screening Level CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level RSV - Refinement Screening Value 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 Prepared by: HEG Checked by: HES su - Standard units Pg/L - micrograms/liter USEPA - United States Environmental Protection Agency WS - Water Supply < - Concentration not detected at or above the reporting limit j - Indicates concentration reported below Practical Quantitation Limit (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated Page 1 of 2 TABLE 1-2 HUMAN HEALTH SCREENING - GROUNDWATER (TRANSITION/BEDROCK) ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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/reg ional-screeni ng-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/nationa I-recom mend ed-water-q ua lity-criteria-h u ma n-hea lth-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/docu ments/dwtab le20l8. 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&folderld=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=laa3fal3-2cOf-45b7-ae96-5427fbld25b4&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-%20envi ron menta I"/o20q ual ity/chapter°/n2002%20-%20environ mental%20ma nagement/subchapter°/u20b/subchapter%20b%20ru les. pdf WS standards are applicable to all Water Supply Classifications. WS standards are based on the consumption offish 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/prod uction/files/2018-03/docu ments/era_reg ional_su pp lemental_g uid a nce_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/dwstanda rdsreg ulations/seconda ry-d rin ki ng-water-standards-guidance-nuisance-chemicals (j) - Value for Total Chromium. (k) - Copper Treatment Technology Action Level is 1.3 mg/L. (1) - 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/[(fl/CMCS) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMCS and CMC2 are 185.9 p/gL and 12.82 p/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 V/gL. (w) - Applicable only to persons with a sodium restrictive diet. (x) - Los Alamos National Laboratory ECORISK Database. http://www.lani.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 (pg/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.orni.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.orni.gov/programs/ecorisk/documents/tml26r2l.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.orni.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=Of60lffa-574d-4479-bbb4-253af0665bf5&groupId=38361 (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 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 Page 2 of 2 TABLE 1-3 HUMAN HEALTH SCREENING - SEDIMENT ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyte CAS Number of Samples Frequency of Detection Range of Detection (mg/kg) Concentration Used for Screening (mg/kg) Residential Screening Value Used (mg/kg) Industrial Screening Value Used (mg/kg) Residential COPC? Industrial COPC? Min. Max. Aluminum 7429-90-5 18 18 9,700 66,000 66,000 15,000 100,000 Y N Antimony 7440-36-0 18 10 0.12 0.51 0.51 6.2 94 N N Arsenic 7440-38-2 18 16 0.52 48 48 0.68 3 y y Barium 7440-39-3 18 18 16 360 360 3,000 44,000 N N Beryllium 7440-41-7 18 18 0.36 3.3 3.3 32 460 N N Boron 7440-42-8 18 13 1.5 58 58 3,200 46,000 N N Cadmium 7440-43-9 18 12 0.034 1.4 1.4 14 200 N N Chromium (Total) 7440-47-3 18 18 8.1 73 73 24,000 100,000 N N Cobalt 7440-48-4 18 18 7.3 37 37 4.6 70 Y N Copper 7440-50-8 18 18 13 100 100 620 9,400 N N Lead 7439-92-1 18 17 2 14 14 400 800 N N Manganese 7439-96-5 18 18 330 2,400 2,400 360 5,200 y N Mercury 7439-97-6 18 7 0.033 2.27 2.27 4.6 3.1 N N Molybdenum 7439-98-7 18 12 3 45 45 78 1,200 N N Nickel 7440-02-0 18 18 6 120 120 300 4,400 N N Selenium 7782-49-2 18 13 0.68 96 96 78 1,200 y N Strontium 7440-24-6 18 18 20 1 130 130 1 9,400 1 100,000 1 N N Thallium 7440-28-0 8 5 0.079 0.11 0.11 0.16 2.4 N N Vanadium 7440-62-2 18 18 21.2 130 130 78 1,160 Y N Zinc 7440-66-6 18 18 26 220 220 4,600 70,000 N N * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Prepared by: HEG Checked by: HES Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources NC - North Carolina LAMA - Coal Ash Management Act DHHS - Department of Health and Human Services NCAC - North Carolina Administrative Code North Carolina Session Law 2014-122, ESV - Ecological Screening Value ORNL - Oak Ridge National Laboratory htto://www.nclea.net/Sessions/2013/Bills HH - Human Health PSRG - Preliminary Soil Remediation Goal /Senate/PDF/S729v7.pdf HI - Hazard Index Q - Qualifier CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration RSL - Regional Screening Level CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level RSV - Refinement Screening Value 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-screen i ng-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-qual ity-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_I_id=1169848&folderld=24814087&name=DLFE-112704.pdf Page 1 of 2 TABLE 1-3 HUMAN HEALTH SCREENING - SEDIMENT ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC (e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=laa3fal3-2cOf-45b7-ae96-5427fbld25b4&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 offish 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/fi les/2018-03/docu ments/era_regional_supplemental_gu idance_report-march-2018_u pdate. pdf (h) - Value applies to inorganic form of arsenic only. (1) - 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. (1) - 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/[(fl/CMCl) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMC1 and CMC2 are 185.9 pg/L and 12.82 Ng/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 pg/L. (w) - Applicable only to persons with a sodium restrictive diet. (x) - Los Alamos National Laboratory ECORISK Database. http://www.lani.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.; Lindsk0og, 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.lani.gov/environment/protection/eco-risk-assessment.php (pg/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.orni.gov/programs/ecorisk/documents/tmg6r2.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.orni.gov/programs/ecorisk/documents/tml26r2l.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.orni.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/getfile?uuid=Of60lffa-574d-4479-bbb4-253af0665bf5&grou (11) - 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 rangy 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 qua (jj) - Hazard Index = 0.1 Page 2 of 2 TABLE 1-4 HUMAN HEALTH SCREENING - ONSITE SURFACE WATER ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Anal Y to CAS Number of Samples Frequency of Detection Range of Detection (Ng/L) Concentration Used for Screening (Ng/L) USEPA AWQC Consumption of Or Organism Only g y (b) (Ng/L) Federal MCL/ SMCL c () (Ng/L) Tap Water RSL HI = 0.2 a () (Ng/L) Screening Value Used (Ng/L) COPC? Min. I Max. Aluminum 7429-90-5 51 51 7 5,460 5,460 NA 50 to 200 (i) 4,000 50 Y Antimony 7440-36-0 51 0 ND ND ND 640 6 1.56 (m) 1 N Arsenic 7440-38-2 51 46 0.75 5.59 5.59 0.14 (h) 10 0.052 (h,jj) 10 N Barium 7440-39-3 51 51 28 4,990 4,990 NA 2,000 760 700 Y Beryllium 7440-41-7 42 1 0.358 0.358 0.358 NA 4 5 4 N Boron 7440-42-8 51 51 594 5,510 5,510 NA NA 800 700 Y Cadmium 7440-43-9 51 4 0.043 0.114 0.114 NA 5 1.84 2 N Chromium (Total) 7440-47-3 51 15 0.337 0.734 0.734 NA 100 4,400 (n) 10 N Chromium (VI) 18540-29-9 35 30 0.027 0.065 0.065 NA NA 0.035 0j) 0.035 Y Cobalt 7440-48-4 42 8 0.635 5.69 5.69 NA NA 1.2 1 Y Copper 7440-50-8 51 49 1.07 4 4 NA 1,300 (k) 160 1,000 N Lead 7439-92-1 51 1 0.925 0.925 0.925 NA 15 (1) 15 (A) 15 N Manganese 7439-96-5 51 51 33 5,110 5,110 100 50 (i) 86 50 Y Mercury 7439-97-6 51 47 5.12E-04 0.00833 0.00833 NA 2 1.14 (0) 1 N Molybdenum 7439-98-7 51 51 2.82 89.9 89.9 NA NA 20 20 Y Nickel 7440-02-0 51 35 0.352 2.75 2.75 4,600 NA 78 (p) 100 N Selenium 7782-49-2 51 44 0.616 2.69 2.69 4,200 50 20 20 N Strontium 7440-24-6 42 42 112 4,990 4,990 NA NA 2,400 2,400 Y Thallium 7440-28-0 51 8 0.085 0.913 0.913 0.47 2 0.04 (q) 0.20 Y Vanadium 7440-62-2 42 42 0.314 2.21 2.21 NA NA 17.2 17 N Zinc 7440-66-6 1 51 20 1.671 4,950 4,950 26,000 5,000 (i) 1,200 1 Y * Data evaluation includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria CAMA - Coal Ash Management Act North Carolina Session Law 2014-122, httD://www.ncleci.net/Sessions/2013/Bills /Senate/PDF/S729v7.pdf CAS - Chemical Abstracts Service DENR - Department of Environment and Natural Resources DHHS - Department of Health and Human Services ESV - Ecological Screening Value HH - Human Health HI - Hazard Index IMAC - Interim Maximum Allowable Concentration CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram COPC - Constituent of Potential Concern NA - Not Available NC - North Carolina NCAC - North Carolina Administrative Code ORNL - Oak Ridge National Laboratory PSRG - Preliminary Soil Remediation Goal Q - Qualifier RSL - Regional Screening Level RSV - Refinement Screening Value SMCL - Secondary Maximum Contaminant Level 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 Prepared by: HEG Checked by: HES Page 1 of 2 TABLE 1-4 HUMAN HEALTH SCREENING - ONSITE SURFACE WATER ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Epidemiology Branch. http://portal.ncdenr.org/c/document_library/get_file?p_I_id=1169848&folderld=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=laa3fal3-2cOf-45b7-ae96-5427fbld25b4&groupId=38364 Amended April 2013. (f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015. http://reports.oa h. state. nc. us/ncac/title%2015a%20-%20envi ron menta 1%20quality/chapter%2002%20-%20environ menta I%20ma na g eme nt/subchapter%20b/subchapter%20 b%20 ru les. 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 offish 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. (1) - 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/[(fl/CMC1) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMC1 and CMC2 are 185.9 Ng/L and 12.82 Ng/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 Ng/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.lani.gov/environment/protection/eco-risk-assessment.php (Ng/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/tml26r2l.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=Of60lffa-574d-4479-bbb4-253af0665bf5&groupId=38361 (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 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. Uj) - Hazard Index = 0.1 Page 2 of 2 TABLE 2-1 ECOLOGICAL SCREENING - SEDIMENT - EASTERN DISCHARGE CANAL ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyte CAS Number of Samples Frequency of Detection Range of Detection (mg/kg) Concentration Used for Screening (mg/kg) USEPA Region 4 Sediment Screening Values(g) (mg/kg) Screening Value Used (mg/kg) COPC? Min. Max. ESV RSV Aluminum 7429-90-5 7 7 9,700 66,000 66,000 25,000 M 58,000 M 25,000 y Antimony 7440-36-0 7 4 0.12 0.51 0.51 2 (y) 25 (y) 2 N Arsenic 7440-38-2 7 6 6.8 40 40 9.8 (z) 33 (z) 9.8 y Barium 7440-39-3 7 7 17.8 360 360 20 (z) 60 (z) 20 y Beryllium 7440-41-7 7 7 0.36 3.3 3.3 NA NA NA N Boron 7440-42-8 7 5 3 34 34 NA NA NA N Cadmium 7440-43-9 7 4 0.034 0.096 0.096 1 (z) 5 (z) 1 N Chromium (Total) 7440-47-3 7 7 8.1 57 57 43.4 (z) 111 (z) 43.4 y Cobalt 7440-48-4 7 7 7.3 37 37 50 (aa) NA (aa) 50 N Copper 7440-50-8 7 7 13 95 95 31.6 (z) 149 (z) 31.6 y Lead 7439-92-1 7 6 3.5 12 12 35.8 (z) 128 (z) 35.8 N Manganese 7439-96-5 7 7 380 2,400 2,400 460 (bb) 1,100 (bb) 460 y Mercury 7439-97-6 7 4 0.033 0.0801 0.0801 0.18 (z) 1.1 (z) 0.18 N Molybdenum 7439-98-7 7 6 3 45 45 NA NA NA N Nickel 7440-02-0 7 7 6 32 32 22.7 (z) 48.6 (z) 22.7 y Selenium 7782-49-2 7 5 0.68 4.6 4.6 0.8 (bb) 1.2 (bb) 0.8 y Strontium 7440-24-6 7 7 21 93 93 NA NA NA N Thallium 7440-28-0 3 2 0.079 0.089 0.089 NA NA NA N Vanadium 7440-62-2 7 7 21.2 130 130 NA NA NA N Zinc 7440-66-6 7 1 7 1 26.7 1 110 110 1 121 (z) 459 (z) 121 N * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services North Carolina Session Law 2014-122, ESV - Ecological Screening Value htto://www.ncleg.net/Sessions/2013/Bills HH - Human Health /Senate/PDF/S729v7.pdf HI- Hazard Index CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram COPC - Constituent of Potential Concern NA - Not Available Prepared by: HEG Checked by: HES su - Standard units pg/L - micrograms/liter USEPA - United States Environmental Protection Agency WS - Water Supply < - Concentration not detected at or above the reporting limit j - Indicates concentration reported below Practical Quantitation Limit (PQL) but above Method Detection Limit (MDL) and therefore concentration is estin Page 1 of 2 TABLE 2-1 ECOLOGICAL SCREENING - SEDIMENT - EASTERN DISCHARGE CANAL ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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-quaI ity-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/prod ucti on/fi I es/2018-03/documents/dwta bl e20l8. pdf (d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental Epidemiology Branch. http://porta1.ncdenr.org/c/document_library/get_file?p_I_id=1169848&folderld=24814087&name=DLFE-112704.pdf (e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://porta1.ncdenr.org/c/document_library/get_file?uuid=Iaa3fa13-2cOf-45b7-ae96-5427fbld25b4&groupId=38364 Amended April 2013. (f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015. http://reports. oa h. state. nc. us/ncac/title%2015a%20-0/`20envi ron menta I %20q ua I ity/chapter%2002%20-%20envi ron m ental%20m an agem ent/subchapter%20b/subchapter%20b%20ru I es. 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/prod uction/fi I es/2018-03/documents/era_reg i ona I_su ppi ementa I_g u i da nce_re port-march-2018_u pdate. pdf (h) - Value applies to inorganic form of arsenic only. (i) - Value is the Secondary Maximum Contaminant Level. https://www.epa.gov/dwstandardsregulations/secondary-dri nki ng-water-standards-guidance-nuisance-chemica Is (j) - Value for Total Chromium. (k) - Copper Treatment Technology Action Level is 1.3 mg/L. (1) - 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/[(fl/CMCl) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMC1 and CMC2 are 185.9 pg/L and 12.82 pg/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 pg/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 (pg/kg dw) (cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/giiciearinghouse/ (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.orni.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/tml26r2l.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?uuld=Of601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361 (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 i 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 monitorin Page 2 of 2 TABLE 2-2 ECOLOGICAL SCREENING - SURFACE WATER - EASTERN DISCHARGE CANAL ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyte CAS Number of Samples Frequency of Detection Range of Detection (pg/L) Concentration Used for Screening (pg/L) 15A NCAC 2B Freshwater Aquatic Life Acute (f) (pg/L) 15A NCAC 2B Freshwater Aquatic Life Chronic (f) (pg/L) USEPA Region 4 Freshwater Acute Screening Values (g) (pg/L) USEPA Region 4 Freshwater Chronic Screening Values (g) (pg/L) USEPA AWQC (b) CMC (acute) (pg/L) USEPA AWQC (b) CCC (chronic) (pg/L) Screening Value Used (pg/L) � COPC. Min. Max. Total Dissolved Total Dissolved Total Dissolved Total Dissolved Total Dissolved Total Dissolved Aluminum 7429-90-5 26 26 7 469 469 NA NA NA NA 750 (b) NA 87 (b) NA 750 NA 87 NA 87 Y Antimony 7440-36-0 26 0 ND ND ND NA NA NA NA 900 (cc) NA 190 (cc) NA NA NA NA NA 190 N Arsenic 7440-38-2 26 21 0.977 5.59 5.59 NA 340 NA 150 340 (b, h) NA 150 (b, h) NA 340 (h) NA 150 (h) NA 150 N Barium 7440-39-3 26 26 36 68 68 NA NA NA NA 2,000 (cc) NA 220 (cc) NA NA NA NA NA 220 N Beryllium 7440-41-7 17 0 ND ND ND NA 65 NA 6.5 31 (r, cc) NA 3.6 (r, cc) NA NA NA NA NA 3.6 N Boron 7440-42-8 26 26 662 2,530 2,530 NA NA NA NA 34,000 (cc) NA 7,200 (cc) NA NA NA NA NA 7,200 N Cadmium 7440-43-9 26 2 0.043 0.074 0.074 NA NA NA NA 1.1 (r) NA 0.16 (r) NA NA 1.8 (r) NA 0.72 (r) 0.16 N Chromium (Total) 7440-47-3 26 1 0.378 0.378 0.378 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 10 5 0.027 0.031 0.031 NA 16 NA 11 16 NA 11 NA NA 16 NA 11 11 N Cobalt 7440-48-4 17 8 0.635 5.69 5.69 NA NA NA NA 120 (cc) NA 19 (cc) NA NA NA NA NA 19 N Copper 7440-50-8 26 24 1.07 4 4 NA NA NA NA 7.3 (r) NA 5.16 (r) NA NA NA NA NA 5 N Lead 7439-92-1 26 0 ND ND ND NA NA NA NA 33.8 (r) NA 1.32 (r) NA NA 65 (r) NA 2.5 (r) 1 N Manganese 7439-96-5 26 26 33 4,860 4,860 NA NA NA NA 1,680 (cc) NA 93 (cc) NA NA NA NA NA 93 Y Mercury 7439-97-6 26 22 5.12E-04 0.00308 0.00308 NA NA 0.012 NA 1.4 (b, s) NA 0.77 (b, s) NA NA 1.4 (s) NA 0.77 (s) 0.01 N Molybdenum 7439-98-7 26 26 19.2 89.9 89.9 NA NA NA NA 7,200 (cc) NA 800 (cc) NA NA NA NA NA 800 N Nickel 7440-02-0 26 10 0.352 2.75 2.75 NA NA NA NA 261 (r) NA 29 (r) NA NA 470 (r) NA 52.0 (r) 29 N Selenium 7782-49-2 26 19 0.926 2.69 2.69 NA NA 5 NA 20 (cc) NA 5 (cc) NA NA NA NA NA 5 N Strontium 7440-24-6 17 17 338 1,150 1,150 NA NA NA NA 48,000 (cc) NA 5,300 (cc) NA NA NA NA NA 5,300 N Thallium 7440-28-0 26 11 0.776 2.13 2.13 NA NA NA NA 54 (cc) NA 6 (cc) NA NA NA NA NA 6 N Vanadium 7440-62-2 17 9 0.314 6 6 NA NA NA NA 79 (cc) NA 27 (cc) NA NA NA NA NA 27 N Zinc 7440-66-6 26 13 2.31 7 7 NA NA NA -4 NA 67 (r) NA 67 (r) NA 120 (r) NA 120 (r) NA 67 N * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources LAMA - Coal Ash Management Act DHHS - Department of Health and Human Services North Carolina Session Law 2014-122, ESV - Ecological Screening Value htto://www.ncleg.net/Sessions/2013/Bills HH - Human Health /Senate/PDF/S729v7.pdf HI - Hazard Index CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram su - Standard units pg/L - micrograms/liter USEPA - United States Environmental Protection Agency WS - Water Supply < - Concentration not detected at or above the reporting limit j - Indicates concentration reported below Practical Quantitation Limit (PQL) but above Method Detection Limit (MDL) and therefore concentration is estimated Prepared by: HEG Checked by: HES Page 1 of 2 TABLE 2-2 ECOLOGICAL SCREENING - SURFACE WATER - EASTERN DISCHARGE CANAL ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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-mis-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/dwtable20l8. 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_I_id=1169848&folderld=24814087&name=DLFE-112704.pdf (a) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://portal.ncdenr.org/c/document_library/get_file?uuid=laa3fal3-2cOf-45b7-ae96-5427fbld25b4&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- / 20envimnmental / 20management/subchapter / 20b/subchapter%20b / 20ruies.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/fi les/2018-03/documents/era_regional_supplemental_guidance_report-march-2018_update. pdf (h) - Value applies to inorganic form of arsenic only. (1) - 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. (1) - 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/[(fl/CMCS) + (f2/CMC2)] where fl and 1`2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMC1 and CMC2 are 185.9 pg/L and 12.82 pg/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 pg/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 (pg/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.orni.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.orni.gov/programs/ecorisk/documents/tml26r2l.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=Of60lffa-574d-4479-bbb4-253af0665bf5&groupId=38361 Page 2 of 2 TABLE 2-3 ECOLOGICAL SCREENING - SEDIMENT - WATER INTAKE BASIN ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyte CAS Number of Samples Frequency of Detection Range of Detection (mg/kg) Concentration Used for Screening (mg/kg) USEPA Region 4 Sediment Screening Values(g) (mg/kg) Screening Value Used (mg/kg) COPC? Min. Max. ESV RSV Aluminum 7429-90-5 5 5 15,000 22,000 22,000 25,000 M 58,000 M 25,000 N Antimony 7440-36-0 5 0 ND ND ND 2 (y) 25 (y) 2 N Arsenic 7440-38-2 5 4 0.52 1.8 1.8 9.8 (z) 33 (z) 9.8 N Barium 7440-39-3 5 5 16 100 100 20 (z) 60 (z) 20 y Beryllium 7440-41-7 5 5 0.47 0.85 0.85 NA NA NA N Boron 7440-42-8 5 2 1.5 1.9 1.9 NA NA NA N Cadmium 7440-43-9 5 2 0.057 0.064 0.064 1 (z) 5 (z) 1 N Chromium (Total) 7440-47-3 5 5 16 31 31 43.4 (z) 111 (z) 43.4 N Cobalt 7440-48-4 5 5 12 16 16 50 (aa) NA (aa) 50 N Copper 7440-50-8 5 5 33 51 51 31.6 (z) 149 (z) 31.6 y Lead 7439-92-1 5 5 2 3.8 3.8 35.8 (z) 128 (z) 35.8 N Manganese 7439-96-5 5 5 360 1,000 1,000 460 (bb) 1,100 (bb) 460 y Mercury 7439-97-6 5 0 ND ND ND 0.18 (z) 1.1 (z) 0.18 N Molybdenum 7439-98-7 5 0 ND ND ND NA NA NA N Nickel 7440-02-0 5 5 8.3 16 16 22.7 (z) 48.6 (z) 22.7 N Selenium 7782-49-2 5 2 0.84 0.85 0.85 0.8 (bb) 1.2 (bb) 0.8 y Strontium 7440-24-6 5 5 35 130 130 NA NA NA N Thallium 7440-28-0 5 3 0.081 0.11 0.11 NA NA NA N Vanadium 7440-62-2 5 5 59 87 87 NA NA NA N Zinc 7440-66-6 5 5 26 56 56 121 (z) 459 (z) 121 N * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources CAMA - Coal Ash Management Act DHHS - Department of Health and Human Services North Carolina Session Law 2014-122, ESV - Ecological Screening Value htto://www.ncleg.net/Sessions/2013/Bills HH - Human Health /Senate/PDF/S729v7.pdf HI- Hazard Index CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram COPC - Constituent of Potential Concern NA - Not Available Prepared by: HEG Checked by: HES su - Standard units pg/L - micrograms/liter USEPA - United States Environmental Protection Agency WS - Water Supply < - Concentration not detected at or above the reporting limit j - Indicates concentration reported below Practical Quantitation Limit (PQL) but above Method Detection Limit (MDL) and therefore concentration is estin Page 1 of 2 TABLE 2-3 ECOLOGICAL SCREENING - SEDIMENT - WATER INTAKE BASIN ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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-quaI ity-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/prod ucti on/fi I es/2018-03/documents/dwta bl e20l8. pdf (d) - DHHS Screening Levels. Department of Health and Human Services, Division of Public Health, Epidemiology Section, Occupational and Environmental Epidemiology Branch. http://porta1.ncdenr.org/c/document_library/get_file?p_I_id=1169848&folderld=24814087&name=DLFE-112704.pdf (e) - North Carolina 15A NCAC 02L .0202 Groundwater Standards & IMACs. http://porta1.ncdenr.org/c/document_library/get_file?uuid=Iaa3fa13-2cOf-45b7-ae96-5427fbld25b4&groupId=38364 Amended April 2013. (f) - North Carolina 15A NCAC 02B Surface Water and Wetland Standards. Amended January 1, 2015. http://reports. oa h. state. nc. us/ncac/title%2015a%20-0/`20envi ron menta I %20q ua I ity/chapter%2002%20-%20envi ron m ental%20m an agem ent/subchapter%20b/subchapter%20b%20ru I es. 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/prod uction/fi I es/2018-03/documents/era_reg i ona I_su ppi ementa I_g u i da nce_re port-march-2018_u pdate. pdf (h) - Value applies to inorganic form of arsenic only. (i) - Value is the Secondary Maximum Contaminant Level. https://www.epa.gov/dwstandardsregulations/secondary-dri nki ng-water-standards-guidance-nuisance-chemica Is (j) - Value for Total Chromium. (k) - Copper Treatment Technology Action Level is 1.3 mg/L. (1) - 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/[(fl/CMCl) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMC1 and CMC2 are 185.9 pg/L and 12.82 pg/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 pg/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 (pg/kg dw) (cc) - Great Lakes Initiative (GLI) Clearinghouse resources Tier II criteria revised 2013. http://www.epa.gov/giiciearinghouse/ (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.orni.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/tml26r2l.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?uuld=Of601ffa-574d-4479-bbb4-253af0665bf5&groupId=38361 (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 i 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 monitorin Page 2 of 2 TABLE 2-4 ECOLOGICAL SCREENING - SURFACE WATER - WATER INTAKE BASIN ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Analyte CAS Number of Samples Frequency of Detection Range of Detection (Ng/L) Concentration Used for Screening (pg/L) USEPA Region 4 Freshwater Chronic Screening Values (g) (pg/L) USEPA AWQC (b) CMC (acute) (pg/L) USEPA AWQC (b) CCC (chronic) (pg/L) Screening Value Used (pg/L) COPC? Min. Max. Total Dissolved Total Dissolved Total TDissolved Aluminum 7429-90-5 25 25 141 5,460 5,460 87 (b) NA 750 NA 87 NA 87 Y Antimony 7440-36-0 25 0 ND ND ND 190 (cc) NA NA NA NA NA 190 N Arsenic 7440-38-2 25 25 0.75 0.952 0.952 150 (b, h) NA 340 (h) NA 150 (h) NA 150 N Barium 7440-39-3 25 25 28 4,990 4,990 220 (cc) NA NA NA NA NA 220 Y Beryllium 7440-41-7 25 1 0.358 0.358 0.358 3.6 (r, cc) NA NA NA NA NA 3.6 N Boron 7440-42-8 25 25 594 5,510 5,510 7,200 (cc) NA NA NA NA NA 7,200 N Cadmium 7440-43-9 25 2 0.078 0.114 0.114 1 0.16 (r) NA NA 1.8 (r) NA 0.72 (r) 0.16 N Chromium (Total) 7440-47-3 1 25 14 0.337 0.734 0.734 48.8 (n, r) NA NA NA NA NA 50 N Chromium (VI) 18540-29-9 25 25 0.035 0.065 0.065 11 NA NA 16 NA 11 11 N Cobalt 7440-48-4 25 0 ND ND ND 19 (cc) NA NA NA NA NA 19 N Capper 7440-50-8 25 25 1.41 2.02 2.02 5.16 (r) NA NA NA NA NA 5 N Lead 7439-92-1 25 1 0.925 0.925 0.925 1.32 (r) NA NA 65 (r) NA 2.5 (r) 1 N Manganese 7439-96-5 25 25 48 5,110 5,110 93 (cc) NA NA NA NA NA 93 Y Mercury 7439-97-6 1 25 25 0.00115 0.00833 1 0.00833 0.77 (b, s) NA NA 1.4 (s) NA 0.77 (s) 0.01 N Molybdenum 7439-98-7 25 25 2.82 3.4 3.4 800 (cc) NA NA NA NA NA 800 N Nickel 7440-02-0 25 25 0.626 0.977 0.977 29 (r) NA NA 470 (r) NA 52.0 (r) 29 N Selenium 7782-49-2 25 25 0.616 0.809 0.809 5 (cc) NA NA NA NA NA 5 N Strontium 7440-24-6 25 25 112 4,990 4,990 5,300 (cc) NA NA NA NA NA 5,300 N Thallium 7440-28-0 2 1 6 1 0.085 0.147 0.147 6 (cc) NA NA NA NA NA 6 N Vanadium 7440-62-2 25 25 1.12 2.21 2.21 27 (cc) NA NA NA NA NA 27 N Zinc 7440-66-6 25 15 1.671 4,950 4,950 67 (r) NA 120 (r) NA 120 (r) NA 67 Y * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: AWQC - Ambient Water Quality Criteria DENR - Department of Environment and Natural Resources LAMA - Coal Ash Management Act DHHS - Department of Health and Human Services North Carolina Session Law 2014-122, ESV - Ecological Screening Value htty://www.ncleg.net/Sessions/2013/Bills HH - Human Health /Senate/PDF/S729v7. pdf HI- Hazard Index CAS - Chemical Abstracts Service IMAC - Interim Maximum Allowable Concentration CCC - Criterion Continuous Concentration MCL - Maximum Contaminant Level CMC - Criterion Maximum Concentration mg/kg - milligrams/kilogram Prepared by: HEG Checked by: HES Revised by: TCP Checked by: HES Page 1 of 2 TABLE 2-4 ECOLOGICAL SCREENING - SURFACE WATER - WATER INTAKE BASIN ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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-screeni ng-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-qual ity-criteria-aquatic-1 ife-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/dwtable20l8.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_I_id=1169848&folderld=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=laa3fal3-2cOf-45b7-ae96-5427fbld25b4&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. (1) - Value is the Secondary Maximum Contaminant Level. https:H/ ww.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. (1) - 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/[(fl/CMCl) + (f2/CMC2)] where fl and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMCS and CMC2 are 185.9 pg/L and 12.82 pg/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 pg/L. (w) - Applicable only to persons with a sodium restrictive diet. (x) - Los Alamos National Laboratory ECORISK Database. http://www.lani.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.lani.gov/environment/protection/eco-risk-assessment.php (pg/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/pmgrams/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.orni.gov/programs/ecorisk/documents/tml26r2l.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_Iibrary/get_file?uuid=Of60lffa-574d-4479-bbb4-253af0665bf5&groupId=38361 Page 2 of 2 TABLE 3-1 SUMMARY OF EXPOSURE POINT CONCENTRATIONS HUMAN HEALTH - GROUNDWATER (SAPROUTE) ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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 m L Arsenic Ng/L 108 28 1.01 24.4 7,309 95% KM (Chebyshev) UCL 4.81 4.81 0.00481 Barium /L 108 108 49 855 225.1 95% Cheb shev Mean, Sd UCL 310.3 310.3 0.3103 Boron /L 85 77 105 40,600 11,620 95% KM Cheb shev UCL 17,274 17,274 17.274 Chromium (Total) /L 108 25 0.725 17.2 3.92 95% KM Cheb shev UCL 2.631 2.631 0.002631 Chromium (VI) /L 10 5 0.058 0.14 0.0878 0.14 0.00014 Cobalt /L 85 72 0.975 43.4 9.351 95% KM Cheb shev UCL 12.77 12.77 0.01277 Lithium /L 76 28 5 17 8.429 95d/0KM t UCL 6.751 6.751 0.006751 Manganese /L 13 13 22 4,180 1,623 99% Cheb shev Mean, Sd UCL 6,579 4,180 4.18 Molybdenum /L 85 70 0.672 266 39.75 1 95% KM Cheb shev UCL 1 61.99 1 61.99 0.06199 Strontium /L 13 13 493 2,580 1,837 95% Cheb shev Mean, Sd UCL 2,781 2,580 2.58 Thallium p /L 85 1 0.211 0.211 0.211 0.211 0.000211 Vanadium ug/L 13 13 4.25 6.39 5.424 95% Student's-t UCL 5.746 5.746 0.005746 Zinc --M/l 13 3 3.874 7 5.625 7 0.007 ' Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted 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 pg/L - micrograms per liter (a)- Mean calculated by PmUCL 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 far use with PmUCL; see note (b). (b)- Sample size was greater than or equal to 30 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by PmUCL. The UCL shown is the one recommended by PmUCL. If more than one UCL was recommended, the higher UCL was selected. ProUCL, version 5.0 (c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples. (d) - The 95% UCL values are calculated using the PmUCL software (V. 5.0; U5EPA, 2013a). The PmUCL software performs a goodness-OM1fit test that accounts nor 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 far 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. PmUCL 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 3-2 SUMMARY OF EXPOSURE POINT CONCENTRATIONS HUMAN HEALTH - GROUNDWATER (TRANSITION/BEDROCK) ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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 m L Aluminum pg/L 700 641 2.253 6,130 190.9 95% KM (Chebyshev) UCL 264.1 264.1 0.2641 Antimony /L 1,105 24 0.336 2.85 1.143 95% KM t UCL 0.459 0.459 0.000459 Arsenic /L 1,298 211 0.004 32 2.081 95% KM Cheb shev UCL 0.767 0.767 0.000767 Barium /L 1,298 1,276 5 1,610 120 95% KM Cheb shev UCL 138.7 138.7 0.1387 Beryllium /L 1,002 11 1.02 17.3 6.027 95% KM t UCL 0.304 0.304 0.000304 Boron /L 1,220 550 3.9 53,800 3,397 95% KM Cheb shev UCL 2,179 2,179 2.179 Cadmium /L 1,286 25 0.033 119 5.609 95% KM Cheb shev UCL 0.595 0.595 0.000595 Chromium (Total) /L 1,298 330 0.034 824 10.1 95% KM Cheb shev UCL 6.054 6.054 0.006054 Chromium (VI) I Ug/L 475 1 219 0.025 7.1 0.511 95% KM Cheb shev UCL 0.39 1 0.39 0.00039 Cobalt /L 1,014 289 0.381 755 18.15 95% KM Cheb shev UCL 10.04 10.04 0.01004 Copper /L 893 250 0.354 4,700 37.84 95% KM Cheb shev UCL 40.32 40.32 0.04032 Lead /L 1,298 38 0.0744 126 6.369 95% KM Cheb shev UCL 0.789 0.789 0.000789 Lithium /L 522 170 1.993 739 46.9 95% KM Cheb shev UCL 32.76 32.76 0.03276 Manganese /L 893 689 0.231 30,000 808 KM H-UCL 1,828 1,828 1.828 Mercury /L 1,298 48 0.017 1.11 0.163 KM H-UCL N/A 1.11 0.00111 Molybdenum /L 1,014 759 0.13 3,140 36.55 95% KM Cheb shev UCL 58.23 58.23 0.05823 Nickel /L 815 320 0.364 808 16.99 95% KM Cheb shev UCL 14.73 14.73 0.01473 Selenium /L 1,298 312 0.103 416 37.58 95% KM Cheb shev UCL 13.39 13.39 0.01339 Strontium pg/L 595 594 67 6,320 554.6 951/o KM (Chebyshev) UCL 652.7 652.7 0.6527 Thallium pg/L 1,220 44 0.059 6.8 0.796 95n/o KM (Chebyshev) UCL 0.162 0.162 0.000162 Vanadium pg/L 602 540 0.129 41.5 5.745 95% KM (Chebyshev) UCL 6.62 6.62 0.00662 Zinc /L 893 277 1.1 16,800 101.8 95% KM Cheb shev UCL 116 116 0.116 = Data evaluated Incluaes data rmin 2015 to Ina quarter 2U1b, unless oche -se noted Prepared by: 1- Chetima 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 pg/L - micrograms per liter (a)- Mean calculated by PmUCL 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 PmUCL; see note (b). (b)- Sample site was greater than or equal to 30 and the number of detected values was greater than or equal to 6, therefore, a 95% UCL was calculated by PmUCL. The UCL shown is the one recommended by PmUCL. If more than one UCL was recommended, the higher UCL was selected. PmUCL, version 5.0 (c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples. (d) - The 95% UCL values are calculated using the PmUCL software (V. 5.0; U5EPA, 2013a). The PmUCL software performs a goodness-ot-tit 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 3-3 SUMMARY OF EXPOSURE POINT CONCENTRATIONS HUMAN HEALTH - SEDIMENT ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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) Aluminum mg/kg 18 18 9,700 66,000 24,983 95% Adjusted Gamma UCL 32,109 32,109 Arsenic mg/kg 18 16 0.52 48 19.94 97.5 KM (Chebyshev) UCL 43.39 43.39 Cobalt mg/kg 18 18 7.3 37 19.24 95% Student's-t UCL 22.57 22.57 Manganese mg/kg 18 18 330 2,400 823.2 95% Student's-t UCL 1,050 1,050 Selenium mg/kg 18 13 0.68 96 12.43 Gamma Adjusted KM-UCL 35.57 35.57 Vanadium m k 18 18 21.2 130 85.07 95% Student's-t UCL 96.11 96.11 * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted 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 Prepared by: HEG Checked by: HES (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 (c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples. (d) - The 95% UCL values are calculated using the ProUCL software (V. 5.0; USEPA, 2013a). The PmUCL 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 3-4 SUMMARY OF EXPOSURE POINT CONCENTRATIONS HUMAN HEALTH - ONSITE SURFACE WATER ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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 m L Aluminum Ng/L 51 51 7 5,460 265.4 95% Chebyshev (Mean, Sd) UCL 722.6 722.6 0.7226 Barium Ng/L 51 51 28 4,990 138.3 95% Chebyshev (Mean, Sd) UCL 561.3 561.3 0.5613 Boron pg/L 51 51 594 5,510 1,121 95% Modified-t UCL 1,317 1,317 1.317 Chromium (VI) pg/L 35 30 0.027 0.065 0.0499 KM H-UCL 0.0518 0.0518 0.0000518 Cobalt pg/L 42 8 0.635 5.69 1.56 95% KM (Chebyshev) UCL 1.415 1.415 0.001415 Manganese pg/L 51 51 33 5,110 464.9 95% Chebyshev (Mean, Sd) UCL 1,063 1,063 1.063 Molybdenum pg/L 51 1 51 1 2.82 1 89.9 1 23.66 95% Chebyshev (Mean, Sd) UCL 37.6 1 37.6 0.0376 Strontium I pg/L 42 42 112 4,990 382.3 95% Chebyshev (Mean, Sd) UCL 893.3 893.3 0.8933 Thallium Pg/L 51 8 0.085 0.913 0.21 95% KM (Chebyshev) UCL 0.205 0.205 0.000205 Zinc I pg/L 1 51 1 20 1 1.671 1 4,950 1 251.5 95% KM (Chebyshev) UCL 529.5 529.5 0.5295 * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted 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 pg/L - micrograms per liter Prepared by: HEG Checked by: HIES Revised by: TCP Checked by: HIES (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 (c) - 0 is defined as a number of samples analyzed or the frequency of detection among samples. (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. TABLE 4-1 SUMMARY OF EXPOSURE POINT CONCENTRATIONS ECOLOGICAL - SEDIMENT - EASTERN DISCHARGE CANAL ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, 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) Aluminum mg/kg 7 7 9,700 66,000 29,243 66,000 Arsenic mg/kg 7 6 6.8 40 16.53 40 Barium Mg/kgMg/kg 7 7 17.8 360 145.8 360 Chromium Total mg kg 7 7 8.1 57 34.3 57 Co er m k 7 7 13 95 46.14 95 Man anese mg/ko 7 7 380 2,400 1,200 2,400 Nickel mg/kg 7 7 6 32 15.93 32 Selenium mg/kq 7 5 0.68 4.6 2.644 4.6 + Data evaluated includes data from 2015 to end quarter 2018, unless otherwise noted fi tee: ---: Calculations were not performed due W lack of samples pg/L - micrograms per liter Mean - An hmetic mean UCL - 95% Upper Confidence Limit mg/kg - milligrams per kilogram Prepared by: HEG Checked by: HES (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 Pr.UCL. The UCL shown is the one recommended by ProUCL. If more than one UCL ended, the higher UCL was selected. PnoUCL, version 5.0 (b)5 r0cis defined as a number of samples analyzed or the frequency of dection among samples. (c) - The 95% UCL valte ues 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 ccordance 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 4-2 SUMMARY OF EXPOSURE POINT CONCENTRATIONS ECOLOGICAL - SURFACE WATER - EASTERN DISCHARGE CANAL ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Minimum Maximum Mean Reporting Number of Frequency of Detected Detected Detected Exposure Point Exposure Point Constituent Units Samples Detection Concentrati Concentrati Concentrati UCL Selected UCL Concentration Concentration (mg/L) on on on Aluminum I Ng/L 1 26 26 1 7 1 469 104.7 1 95% Student's-t UCL 137.1 137.1 0.1371 Man anese L 1 26 26 1 33 1 4,860 640.8 1 950/6 Adjusted Gamma UCL 1 956.5 956.5 0.9565 )ata evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise not Notes: ---: Calculations were not performed due to lack of samples pg/L - micrograms per liter Mean - Arithmetic mean UCL - 95% Upper Confidence Limit mg/L - milligrams per liter Prepared by: HEG Checked by: HES (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. (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 - SEDIMENT - WATER INTAKE BASIN ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Reporting Number of Frequency of Minimum Maximum Mean Kaplan- Meier Exposure Point Constituent Units Samples Detection Detected Detected Detected Method Mean UCL Selected UCL Concentration Concentration Concentration Concentration (mg/kg) Barium mg/kg 5 5 16 100 51.4 100 Copper mg kg 5 5 33 51 39.6 51 Manganese mg/kg 5 5 360 1,000 552 1,000 Selenium m k 5 2 0.84 0.85 0.845 0.85 ` Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted M.= ---: Calculations were not performed due to lack of samples pg/L - micrograms per liter Mean - Arithmetic mean UCL - 95% Upper Confidence Limit mg/kg - milligrams per kilogram Prepared by: HEG Checked by: HES (a)- Sample size was greater than or equal W 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 d—ion among samples. (c) - The 95% UCL values are calculated using the PmUCL 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 m 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 distributon of the data set. PmUCL 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 'PC. TABLE 4-4 SUMMARY OF EXPOSURE POINT CONCENTRATIONS ECOLOGICAL -SURFACE WATER- WATER INTAKE BASIN ROXBORO STEAM STATION DUKE ENERGY CAROLINAS, LLC, SEMORA, NC Minimum Maximum Mean Exposure Point Reporting Number of Frequency of Exposure Point Constituent Units Samples Detection Detected Detected Detected UCL Selected UCL Concentration Concentration Concentration Concentration Concentration (mg/L) Aluminum Ng/L 25 25 141 5,460 432.6 95% Chebyshev (Mean, Sd) UCL 1,348 1,348 1.348 Barium Ng/L 25 25 28 4,990 228.5 95% Chebyshev (Mean, Sd) UCL 1,093 1,093 1.093 Manganese Ng/L 25 25 48 5,110 282 95% Chebyshev (Mean, Sd) UCL 1,159 1,159 1.159 Zinc /L 1 25 15 1.671 4,950 333.5 95% Chebyshev Mean Sd UCL 1,064 1,064 1.064 * Data evaluated includes data from 2015 to 2nd quarter 2018, unless otherwise noted Notes: ---: Calculations were not performed due to lack of samples pg/L - micrograms per liter Mean - Arithmetic mean UCL - 950% Upper Confidence Limit mg/L - milligrams per liter Prepared by: HEG Checked by: HES (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. (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 5-1 SUMMARY OF ON -SITE SEDIMENT EPC/RBC COMPARISON ON -SITE TRESPASSER - ADOLESCENT (AGE 6 to <16) ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC SEMORA, NC COPC CAS Risk -Based Concentration On -site Sediment Risk Ratio Non -Cancer Cancer Final Basis Exposure Point Concentration Non -Cancer Cancer (mg/kg) (mg/kg) (mg/kg) (mg/kg) Aluminum 7429-90-5 3.6E+07 nc 3.6E+07 nc 32,109 0.001 nc Arsenic 7440-38-2 6.1E+03 9.5E+03 6.1E+03 nc 43 0.007 nc Cobalt 7440-48-4 1.1E+04 1.1E+04 nc 23 0.002 nc Manganese 7439-96-5 5.0E+05 nc 5.0E+05 nc 1,050 0.002 nc Selenium 7782-49-2 1.8E+05 nc 1.8E+05 nc 36 0.0002 nc Vanadium 7440-62-2 1.8E+05 nc 1.8E+05 nc 96 0.001 nc Cumulative Risk 0.005 0.0E+00 Notes• COPC - Chemical of potential concern c - Remedial goal based on cancer risk nc - Remedial goal based on non -cancer hazard index Incidental Ingestion Dermal Contact Particulate Inhalation Ambient Vapor Inhalation Exposure Routes Evaluated No Yes No No Target Hazard Index (per Chemical) 1E+00 Target Cancer Risk (per Chemical) 1E-04 Prepared by: HHS Checked by: TCP Page 1 of 1 TABLE 5-2 SUMMARY OF ON -SITE SURFACE WATER EPC/RBC COMPARISON ON -SITE TRESPASSER - ADOLESCENT (AGE 6 to <16) ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC SEMORA, NC COPC CAS Risk -Based Concentration On -site Surface Water Risk Ratio Non -Cancer Cancer Final Basis Exposure Point Concentration Non -Cancer Cancer (mg/L) (mg/L) (mg/L) (mg/__1 iQ Aluminum 7429-90-5 1.3E+04 nc 1.3E+04 nc 0.7 0.0001 nc Barium 7440-39-3 5.5E+02 nc 5.5E+02 nc 0.6 0.001 nc Boron 7440-42-8 2.6E+03 nc 2.6E+03 nc 1 0.0005 nc Chromium VI 18540-29-9 1.7E+00 2.6E-01 2.6E-01 c 0.00005 0.0002 1.96E-04 Cobalt 7440-48-4 4.6E+00 nc 4.6E+00 nc 0.001 0.0003 nc Manganese 7439-96-5 2.4E+02 nc 2.4E+02 nc 1 0.004 nc Molybdenum 7439-98-7 6.5E+01 nc 6.5E+01 nc 0.04 0.0006 nc Strontium 7440-24-6 7.7E+03 nc 7.7E+03 nc 0.9 0.0001 nc Thallium 7440-28-0 NA 0.0002 NC nc Zinc 7440-66-6 4.4E+03 nc 4.4E+03 nc 0.5 0.0001 nc Cumulative Risk 0.01 1.96E-04 Notes: COPC - Chemical of potential concern c - Remedial goal based on cancer risk nc - Remedial goal based on non -cancer hazard index (a) Final RBC value for lead is 15 ug/L or surface/seep water exposures (b) Lead was not included in the cumulative risk calculation. 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 Prepared by: HHS Checked by: TCP NA - No toxicity value available; remedial goal not calculated NC - Not Calculated Refer to Attachment D, Section 2.5 of the Mayo Steam Electric Plant CAP (SynTerra 2015). Page 1 of 1 TABLE 5-3 SUMMARY OF ON -SITE GROUNDWATER EPC/RBC COMPARISON CONSTRUCTION - CONSTRUCTION WORKER (ADULT) ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC SEMORA, NC COPC CAS Risk -Based Concentration On -site Saprolite Groundwater Risk Ratio Non -Cancer Cancer Final Basis Exposure Point Concentration Non -Cancer Cancer (mg/L) (mg/L) (mg/L) (mg/L) Arsenic 7440-38-2 2.9E+01 4.5E+02 2.9E+01 nc 0.005 0.00017 nc Barium 7440-39-3 5.0E+03 nc 5.0E+03 nc 0.3 0.00006 nc Boron 7440-42-8 1.9E+04 nc 1.9E+04 nc 17 0.00090 nc Chromium, Total 7440-47-3 8.6E+03 nc 8.6E+03 nc 0.003 0.0000003 nc Chromium (VI) 18540-29-9 2.8E+01 7.6E+01 2.8E+01 nc 0.0001 0.00000 nc Cobalt 7440-48-4 3.3E+02 nc I 3.3E+02 nc 0.01 0.00004 nc Lithium 7439-93-2 NA 0.01 NC nc Manganese 7439-96-5 2.2E+03 nc 2.2E+03 nc 4.2 0.0019 nc Molybdenum 7439-98-7 4.8E+02 nc 4.8E+02 0.06 0.00013 nc Strontium 7440-24-6 1.9E+05 nc 1.9E+05 3 0.00001 nc Thallium 7440-28-0 NA dnc 0.0002 NC nc Vanadium 7440-62-2 9.6E+02 nc 9.6E+02 0.006 0.0000060 nc Zinc 7440-66-6 1 3.1E+04 nc 3.1E+04 nc 0.01 1 0.0000002 nc Cumulative Risk 1 0.003 1 0.00E+00 F,repareo Dy: hh5 C.necKea Dy: 1 Ur COPC CAS Risk -Based Concentration On -site Transition/Bedrock Groundwater Risk Ratio Non -Cancer Cancer Final Basis Exposure Point Concentration Non -Cancer Cancer (mg/L) (mg/L) (mg/L) (mg/L) Aluminum 7429-90-5 9.6E+04 nc 9.6E+04 nc 0.3 0.000003 nc Antimony 7440-36-0 1.7E+01 nc 1.7E+01 nc 0.0005 0.00003 nc Arsenic 7440-38-2 2.9E+01 4.5E+02 2.9E+01 nc 0.001 0.00003 nc Barium 7440-39-3 5.0E+03 nc 5.0E+03 nc 0.1 0.00003 nc Beryllium 7440-41-7 4.8E+02 nc 4.8E+02 nc 0.0003 0.000001 nc Boron 7440-42-8 1.9E+04 nc 1.9E+04 nc 2 0.0001 nc Cadmium 7440-43-9 1.0E+01 nc 1.0E+01 nc 0.0006 0.00006 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 0.0004 0.00001 nc Cobalt 7440-48-4 3.3E+02 nc 3.3E+02 nc 0.01 0.00003 nc Copper 7440-50-8 3.8E+03 nc 3.8E+03 nc 0.04 0.00001 nc Lead 7439-92-1 NA 0.001 NC nc Lithium NA 0.03 NC nc Manganese 7439-96-5 2.2E+03 nc 2.2E+03 nc 2 0.0008 nc Mercury 7439-97-6 5.0E+01 nc 5.0E+01 nc 0.001 0.00002 nc Molybdenum 7439-98-7 4.8E+02 nc 4.8E+02 nc 0.06 0.0001 nc Nickel 7440-02-0 1.0E+03 nc 1.0E+03 nc 0.01 0.00001 nc Selenium 7782-49-2 4.8E+02 nc 4.8E+02 nc 0.01 0.00003 nc Strontium 7440-24-6 1.9E+05 nc 1.9E+05 nc 0.7 0.000003 nc Thallium 7440-28-0 NA 0.0002 NC nc Vanadium 7440-62-2 9.6E+02 nc 9.6E+02 nc 0.007 0.000007 nc Zinc 7440-66-6 1 3.1E+04 nc 3.1E+04 nc 0.1 0.000004 nc Cumulative Risk 0.001 0.00E+00 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 Dermal Contact Ambient Vapor Inhalation Target Hazard Index (per Chemical) Target Cancer Risk (per Chemical) Yes Yes No 1E+00 1 E-04 NA - No toxicity value available; remedial goal not calculated NC - Not Calculated Prepared by: HHS Checked by: TCP Page 1of1 TABLE 5-4 SUMMARY OF EXPOSURE POINT CONCENTRATION COMPARISON TO RISK -BASED CONCENTRATION ROXBORO STEAM ELECTRIC PLANT DUKE ENERGY PROGRESS, LLC SEMORA, NC Source Table (PRG Tables) Media Exposure Pathway Risk Ratio - Non -cancer Risk Ratio - Cancer TABLE 5-1 Sediment - On -site ON -SITE TRESPASSER - ADOLESCENT (AGE 6-<16) 0.005 0.00E+00 TABLE 5-2 Surface Water - On -site ON -SITE TRESPASSER - ADOLESCENT (AGE 6-<16) 0.007 1.96E-04 Groundwater-Surficial Aquifer CONSTRUCTION - CONSTRUCTION WORKER (ADULT) 0.003 0.00E+00 TABLE 5-3 Groundwater -Transition /Bedrock CONSTRUCTION - CONSTRUCTION WORKER (ADULT) 0.001 0.00E+00 Page 1 of 1 Table 1 Exposure Parameters for Ecological Receptors Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant Parameter Body Weight Food Ingestion Rate Water Ingestion Rate Dietary Composition Home Range Seasonal Use Factor' Plants Mammal/Terr. Vertebrates Fish Invertebrates Birds Soil Algorithm ID BW IRF IRw PF AM AF A, AB SF HR SUF Units kg kg/kg BW/day L/kg BW/day % % % % % % hectares unitless HERBIVORE Meadow Vole' 0.033 0.33 0.21 97.6% 0% 0% 0% 0% 2.4% 0.027 1 Muskrat' 1.17 0.3 0.97 99.3% 0% 0% 0% 0% 0.7% 0.13 1 OMNIVORE $ a Mallard Duck` 1.134 0.068 0.057 48.3% 0% 0% 48.3% 0% 3.3% 435 1 °; v American Robin' 0.08 0.129 0.14 40% 0% 0% 58% 0% 2% 0.42 1 CARNIVORE m Red -Tailed Hawke 1.06 0.18 0.058 0% 91.5% 0% 0% 8.5% 0% 876 1 0 o Bald Eaglef 3.75 0.12 0.058 0% 28% 58% 0% 13.5% 0.5% 2199 1 Red Fox' 4.54 0.16 0.085 6% 89% 0% 2% 0% 3% 1226 1 PISCIVORE River Otter' 6.76 0.19 0.081 0% 0% 100% 0% 0% 0% 348 1 Great Blue Heron' 2.229 0.18 0.045 0% 0% 90% 9.5% 0% 0.5% 227 1 NOTES: BW - Body Weight Pr - Plant Matter Ingestion Percentage kg/kg BW/day - Kilograms Food per Kilograms Body Weight per Day kg - Kilograms AM - Mammal/Terrestrial Vertebrate ingestion percentage L/kg BW/day - Liters Water per Kilogram Body Weight per Day IR - Ingestion Rate AF - Fish Ingestion Percentage HR - Home Range AB- Bird Ingestion Percentage SUF - Seasonal Use Factor SF - Soil Ingestion Percentage ' 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 `BW, PF, A,, HR from USEPA 1993 (sections 2-43 and 2-45); SF from Beyer et al. 1994; IRF from Nagy 2001 d BW, PF, Al, HR from USEPA 1993 (sections 2-197 and 2-198); SF from Sample and Suter 1994; IRF from Nagy 2001 ' BW, PF, AM, AB, IRF, HR from USEPA 1993 (sections 2-82 and 2-83) f BW, PF, AD AM, AB, HR from USEPA 1993 (sections 2-91 and 2-97); IRF from Nagy 2001 g BW, PF, AD Al, 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 BW, PF, AF, Al, HR from USEPA 1993 (sections 2-8 and 2-9); SF from Sample and Suter 1994; IRF from Nagy 2001 f Seasonal Use Factor is set to a default of 1 to be overly conservative and protective of ecological receptors. Table 2 Toxicity Reference Values for Ecological Receptors Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant Analyte TRVs (NOAEL) Aquatic 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 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 Barium` 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 Boron a,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, Total' 1 1 1 1 2740 2740 1 1 2740 2740 Chromium VI (hexavalent)' NA NA NA 9.24 9.24 NA NA 9.24 9.24 Chromium Illa 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 Copper' 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 Lead 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 Mercury' 3.25 3.25 3.25 1.01 1.01 3.25 3.25 1.01 1.01 Molybdenum''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 Selenium' 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 NitratedI NA NA NA 507 507 NA NA 507 507 Table 2 (Cont.) Analyte TRVs (LOAEL) Aquatic Terrestrial Mallard Duck (mg/kg/day) Heron (mg/kg/day) Bald Eagle (mg/kg/day) Muskrat (mg/kg/day) River Otter (mg/kg/day) Robin (mg/kg/day) Hawk (mg/kg/day) Meadow Vole (mg/kg/day) Red Fox (mg/kg/day) Aluminum' 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 Barium` 41.7 41.7 41.7 75 75 41.7 41.7 75 75 Beryllium' NA NA NA 6.6 6.6 NA NA 6.6 6.6 Boron a,b 100 100 100 93.6 93.6 100 100 93.6 93.6 Cadmium' 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, Total' 5 5 5 27400 27400 5 5 27400 27400 Chromium VI (hexavalent)' 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 Cobalt' 7.8 7.8 7.8 10.9 10.9 7.8 7.8 10.9 10.9 copper 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 Lead 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 Manganese 348 348 348 71 71 348 348 71 71 Mercury' 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 Nickel' 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 ThaiIiuma NA NA NA 0.075 0.075 NA NA 0.075 0.075 Vanadium' 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 NOTES: NOAEL - No Observed Adverse Effects Level LOAEL - Lowest Observed Effects Level EN - Essential nutrient NA- Not available TRV - Toxicity Reference Value 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 b USEPA 2005 EcoSSL ` 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 Table 3 Exposure Area and Area Use Factors for Ecological Receptors Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant Exposure Point p Exposure Areaa Area Use Factor (AUF) Mallard Great Blue River Bald American Red -Tailed Meadow (hectares) Muskrat Red Fox Duck Heron Otter Eagle Robin Hawk Vole Eastern Discharge Canal 6.3 1.45% 2.78% 100% 1.81% 0.29% 100% 0.719% 100% 0.51% NOTES: a The Eastern Discharge Canal Exposure Area is a shallow channel that runs from the Eastern Extension Impoundment to the Water Intake Basin. The area includes aquatic and terrestrial habitats. Table 4 EPCs for Use in the Risk Assessment Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant Terrestrial EPCsa Aquatic EPCsa' b COPC CASRN Soil EPC Used in Risk Assessment` (mg/kg) Seep Water EPC Used in Risk Assessment (mg/L) Sediment EPC Used in Risk Assessment (mg/kg) Surface Water EPC Used in Risk Assessment (mg/L) Aluminum 7429-90-5 66,000 0.1371 66,000 0.1371 Arsenic 7440-38-2 40 40 Barium 7440-39-3 360 360 Chromium, Total 7440-47-3 57 57 Copper 7440-50-8 95 95 Manganese 7439-96-5 2,400 0.9565 2,400 0.9565 Nickel 7440-02-0 32 32 Selenium 1 7782-49-2 4.6 1 1 4.6 Created By: TCP Checked By: HES NOTES: COPC - Constituent of Potential Concern CASRN - Chemical Abstracts Service Registration Number EPC - Exposure Point Concentration a EPCs for surface water are based on 95% UCLs. EPCs for sediment are based on maximum concentrations. b Terrestrial EPCs listed are values from the Aquatic EPCs list and are used to evaluate exposure to terrestrial receptor groups in this model. `Analysis of solids (i.e., soil and sediment) was reported as dry weight. wATFR i JINIE ") SOIL I -D. I BF I ADD, I SUF I AUF 7- 'P, I EPC.— 1­ 1 P, I NIR, I NIA. I ADD, 1 & ADI I I -. NIIEI: BF- B—Pbility Facor —:S —.1—F.— :A - Ei.--- F.— AUF A—U-- A.. 11 1 CF - ---w F— 'Becht�l J.— C BaezM.), Environmental --t— D,-w - M.—I ER-3 1999, d—t value of l is uA,d for constituents f., -0 . EAF could not b, —d, 4-11, EPA —A (--hg LevelErological Risk --.1 protocolfor H.—us W.- Combustion Restoration Division -Manual ERDAG-003 1999; default value of1 i, uxdfor conrtituents for -6 . RAF could notbe found. Table 6 Calculation of Average Daily Doses for Red -Tailed Hawk Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant AVERAGE DAILY DOSE VIA: WATER VERTEBRATE PREY NIRw AD% Pr Pp NIP, NIR, ADD, BF ADD, SUF AUF ADD­ EPCw EPC, EPC­ Area Use Slope, or Slope, Estimated Water Unadjusted Fraction Diet Fraction Diet Ingestion Vertebrate Unadjusted Carnivore Seasonal Use Factor Adjusted Total COPEC in COPEC in Solid Concentration in Average Daily Terrestrial Avian Ingestion Rate Average Daily Bioavailability' Carnivore Analyte Water (mg/L) (mg/kg) Vertebrate Uptake (BAF)i Intercept Mammals and Ingestion Rate (L/kg BW/day) Dose Water Vertebrates Vertebrates Rate, Wet (kg/kg Dose (percent) Intake (mg/kg/day) Factor (unitless) (Exposure Area/Home Average Daily Birds (mg/kg) (mg/kg/day) (percent) (percent) W/da BW/day) BW/day) (mg/kg/day) Range) Dose (mg/kg/day) Aluminum 0.1371 66,000 1 66,000 0,058 0,008 91.5% 8.5% 0.18 0.18 11,880 100% 11,880.01 1 0.0072 85,43841 Arsenic 40 0.8188 -4.8471 0.16 0.058 0 91.5% 8.5% 0.18 0.18 0.0289715 100% 0.02897 1 0.0072 0.00020836 Barium 360 0.7 -1.412 15.0033 0.058 0 91.5% 8.5% 0.18 0.18 2.7006011 100% 2.701 1 0.0072 0.019422 Chromium, Total 57 0.1444 -1.4599 0.42 0.058 0 91.5% 8.5% 0.18 0.18 0.0749539 100% 0.075 1 0.0072 0.0005391 Co er 95 0.1444 2.042 14.87 0.058 0 91.5% 8.5% 0.18 0.18 2.6772266 100% 2.68 1 0.0072 0.01925 Man anese 0.9565 2,400 0.004 9.6 0.058 0.055 91.5% 8.5% 0.18 0.18 1.728 100% 1.78 1 0.0072 0.0128 Nickel 32 0.4658 -0.2462 3.93 0.058 0 91.5% 8.5% 0.18 0.18 0.7070466 100% 0.71 1 0.0072 0.0051 Selenium 4.6 0.3764 -0.4158 1.17 0.058 0 91.5% 8.5% 0.18 0.18 0.210938 100% 0.21 1 0.0072 0.0015 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 i Sample et al. 1998a; EPA 2007 EcoSSLs, All 4-1, Table 4a ' 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 Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant AVERAGE DAILY DOSE VIA: WATER PLANTS / VEGETATION SOIL Nifix ADD, Pr NIR, I NIR, ADDe S, NIR, ADD, BF ADD, SUF AUF ADD_ EPCw EPC, EPC, Area Use Adjusted Total Estimated' Water Unadjusted Fraction Diet Food Ingestion Plant Unadjusted Soil Ingestion Unadjusted Herbivore Factor Herbivore Analyte COPEC in COPEC in Solid Slope, or Plant Intercept Concentration in Ingestion Rate Average Daily Plant Matter Rate, Wet Ingestion Average Daily Fraction Diet Rate (kg Average Daily eioavailabilityz Intake Seasonal Use (Exposure Average Daily Water (mg/L) (mg/kg) Uptake (BAF) Vegetation Dose Water (kg/kg Rate, Dry Dose Plant Soil (percent) dry/kg Dose Soil (percent) Factor (mg/kg dry) (L/kg BW/day) (mg/kg/day) (percent) BW/day) (kg/kg/day) (mg/kg/day) BW/day) (mg/kg/day) (mg/kg/day) Area/Home Dose Range) (mg/kg/day) Aluminum 0.1371 66,000 0.0008 52.8 0.21 0.029 97.6% 0.33 0.048 2.550874 2.4% 0.001 67.9536 100% 70.533 1 1 70.53 Arsenic 40 0.564 -1.992 1.0926 0.21 0 97.6% 0.33 0.048 0,052784 2.4% 0.001 0.04118 100% 0.094 1 1 0.094 Barium 360 0.03 10.8 0.21 0 97.6% 0.33 0.048 0.52177 2.4% 0.001 0.37066 100% 0.892 1 1 0.892 Chromium, Total 57 0.0015 0.0855 0.21 0 97.6% 0.33 0.048 0,004131 2.4% 0.001 0105869 300% 0.063 1 1 0.063 Co a 95 0.39 0.669 11.7 0.21 0 97.6% 0.33 0.048 0.567311 2.4% 0.001 0109781 100% 0.665 1 1 0.665 Manganese 0.9565 2,400 0.050 120 0.21 0.201 97.6% 0.33 0.048 5.79744 2.4% 0.001 2.47104 100% 8.469 1 1 8.469 Nickel 32 0.748 -2.224 1.4454 0.21 0 97.6% 0.33 0.048 0.069829 2.4% 0.001 0.03295 100% 0.103 1 1 0.103 Selenium 4.6 1.104 -0.678 2.7367 0.21 0 97.6% 0.33 0.048 0,132217 2.4% 0.001 0100474 100% 0A37 1 1 0.137 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 ' Bechtel Jacobs Company 1998a; Baes et al. 1984 (Mo); Environmental Restoration Division - Manual ERD-AG-0031999; default value of 1 is used for constituents for which a BAF could not be found. z Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors. ��m�a������� �a m��� ��� ���� �a� ��a ��m��������� ��®������aa� as as ���� m��� m�� m�� ���a ���� �a� �a� ��a ��a ��m�a������� ��a��������� as as m��� m��� m�� m�� ���� ���� �a� �a� ��a�� ��a ��®��������� ������������ as as m��� m��� m�� m�� ���� ���� �a� �a� ��a ��a AVEILAGE DAILY DOSE VIA —ER P—/VEGE-DON A. I DIVERIrEll ... S- I D.. NI .11I—I, EF S F Seasonal U. -I., N.1-1- Ingestion R- BAF B—L..1 — —t., AUF A.. U. F.— ADDD— BCF F—, 1998b, le for setli — 1. —hil Invertebratesfor Cr, C., DO, NI, Pb, 5.,Yple .1 a,, 19986 �Wnbwormz�for Mn; default value of1is used for ronstituents forwbitria BAF roultl not be found. Bi—ilbbilfty — I . df..lt d — 1. --- — P—lim. d l.Nll.I I—pl— Table 1D Calculation W Average Daily Doses for Great Blue Heron Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant AVERAGE DAILY DOSE VIA: WATER FISH INVERTEBRATES EPI C.. I EPC. EI PC.... EPC. NIR-. ADD... A. HR. I NIR. I ADD_ I A. I NIR- I ADD_ RF ADD. I SUF I AUF I ADD.-. �mooa�o �o��o �0000 NOTES: EPC-Exposure Point Concentration BF- Bioavailability Factor SUF- Seasonal Use Factor NIR- Normalized ingmtion Rate BAF-Bioacamulation Factor AUF - Area Use F.— ADD - Average Daily Dose BCF- Bioconce—ion Factor AI (Volgt et al. 2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division- Manual ERD-AG-0031999. Bechtel Jacobs Company 1998b, Table 2, median RAF, for sediment to benthic invertebrates for As, Cd, Cr, Cu, H& Ni, Pb, and Zn: Sample et a1. 1999b (earthworm,( for Mn; default value of 1 is used for constituents for which a RAF could not be found. ' Bioavailability is set to a default of 100%to be conservative and protective of ecological receptors. Table 11 Ulcula[Ion of Average Dally Doses for Bald Eagle Eastern Discharge Canal aseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant NOTES: EPC- Exposure Point Concentration BF- Bioevailability Factor SUF- Seasonal Use Factor NIR-Normalizad Ingestion Rate BAF-Bioaccumulekan Facor AUF-Free Use F.— ADD - Average Daily Dose BCF- Biocon—ndion Factor 'Sample et a1. 1998a; EPA 200J EwSSLs, Att 4-1, Table la ' AI (Voigt et al.2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division- Manual EP0.AG-0031999. B.—ailab111ty is set to a default of 100%to be conservative and protective of ecological receptors. Table 12 Calculation of Average Daily Doses for Muskrat Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant AVERAGE DAILY DOSE VIA: PUNTS VEGETATION Adj... Total Estimated' Water Ingestion Unadjusted Fraction Diet Phint 1. gealm Unadjusted Unadjusted AreaUselFetr Harbiwore COP EC in Water COPEC in Solid Slope.or Plant Cn,..,at,.n ME Seasonal Us. Exposure Average Daily Im.) mg/kg) Uptake BAF) in Veget tion Factor (-itlen) A —/Flo e D a IN, (mg/kg try) Range) (.g/kg`/day) NOTES: EPC- Expo sure Point Concentration BF- Bioavailability Factor SUF- Seasonal Use Factor NIR- Normalizedingestion Rate BAF- Bioaccumulalicn Factor AUF - Area Use Factor ADD- Average Daily Dose BCF- Bioconcentration Factor Bechtel Jacobs Company 1998a; Bores et al. 1984 (Me); Environmental Restoration Division - Manual ERD-AG-0031999; default value of 1 is used for constituents for which a BAF could not be found. ' eioavailability is set to a default of 100%to be conservative and protective of ecological receptors. Table 13 Calculation of Average Daily Doses for River Otter Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant AVERAGE DAILY DOSE VIA: DRINKING WATER FISH NIRw ADD„, Pf NIRf NIRa ADDa BF ADDS SUF AUF ADD— EPCw EPCa EPCPREY Area Use Adjusted Total Unadjusted Unadjusted COPEC in COPEC in Solid Fish Uptake Estimated Water Average Daily Fraction Diet Food Ingestion Fish Ingestion Average Daily i Bioavailability Piscivore Seasonal Use Factor Piscivore Watterer (mg/L) (mg/kg) (BCF) Concentration Ingestion Rate Dose Water Animal Matter Rate, Wet Rate (kg/kg Dose (percent) ) Intake Factor (Exposure Average Daily in Fish m k ( g) (L/kg BW/da y) (percent) (p ) k k BW da (� g / Y) BW da / Y) (mg/kg/day) (unitless) Area/Home Dose Analyze (mg/kg/day) (mg/kg/day) Range) (mg/kg/day) Aluminum 0.1371 66,000 0.1 0.01 0.081 0.011 100% 0.19 0.19 0.0026 100% 0.014 1 0.018 0,000248 Arsenic 40 280 0 0.081 0 100% 0.19 1 0.19 0 100% 0 1 1 0.018 0 Barium 360 4 0 0.081 0 100% 0.19 0.19 0 100% 0 1 0.018 0 Chromium, Total 57 200 0 0.081 0 100% 0.19 0.19 0 100% 0 1 0.018 0 Copper 95 50 0 0.081 0 100% 0.19 0.19 0 100% 0 1 0.018 0 Manganese 0.9565 2,400 400 382.6 0.081 0.077 100% 0.19 0.19 72.69 100% 72.771 1 0.018 1.317415 Nickel 32 100 0 1 0.081 0 100% 0.19 0.19 01 100% 0 1 0.018 0 Selenium 4.6 8 0 1 0.081 0 100% 0.19 0.19 0 1 100% 0 1 0.018 0 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 - Bioconcenlration Factor Al (Voigt et al. 2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division - Manual ERD-AG-003 1999. Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors. Table 14 Hazard Quotients for COPCs - Terrestrial Receptors Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant Analyte Wildlife Receptor Hazard Quotient Estimated using the 'No Observed Adverse Effects Level' Terrestrial American Robin Red -Tailed Hawk Meadow Vole I Red Fox Aluminum 1.49E+00 7.77E-01 3.65E+01 2.51E+01 Arsenic 2.39E-02 9.30E-05 9.04E-02 2.51E-04 Barium 4.69E-02 9.34E-04 1.72E-02 2.39E-04 Chromium, Total 1.08E-01 5.39E-04 2.29E-05 1.85E-07 Copper 7.30E-02 4.75E-03 1.19E-01 2.02E-03 Manganese 1.53E-02 7.17E-05 1.64E-01 3.15E-04 Nickel 5.25E-02 7.58E-04 6.05E-02 1.78E-03 Selenium 2.54E-01 5.23E-03 9.58E-01 6.28E-03 Analyte Wildlife Receptor Hazard Quotient Estimated using the'Lowest Observed Adverse Effects Level' Terrestrial American Robin Red -Tailed Hawk Meadow Vole Red Fox Aluminum 1.49E-01 7.77E-02 3.65E+00 2.51E+00 Arsenic 1.33E-03 5.17E-06 5.66E-02 1.57E-04 Barium 2.34E-02 4.66E-04 1.19E-02 1.65E-04 Chromium, Total 2.17E-02 1.08E-04 2.29E-06 1.85E-08 Copper 2.44E-02 1.59E-03 7.12E-02 1.21E-03 Manganese 7.88E-03 3.69E-05 1.19E-01 2.28E-04 Nickel 3.06E-02 4.42E-04 3.02E-02 8.89E-04 Selenium 1.27E-01 2.62E-03 6.37E-01 4.18E-03 NOTES: Hazard Quotients greater than or equal to 1 are highlighted in gray and in boldface. NC - Not calculated due to lack of a Toxicity Reference Value Table 15 Hazard Quotients for COPCs - Aquatic Receptors Eastern Discharge Canal Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant Analyte Wildlife Receptor Hazard Quotient Estimated using the 'No Observed Adverse Effects Level' Aquatic Mallard Duck Great Blue Heron Bald Eagle Muskrat River Otter Aluminum 6.54E-02 2.25E-06 6.54E-05 2.51E+00 1.29E-04 Arsenic 3.77E-04 3.21E-03 4.83E-02 Barium 1.92E-03 3.46E-04 9.56E-03 Chromium, Total 8.43E-04 7.19E-03 2.13E-06 Copper 4.13E-03 1.78E-03 9.43E-02 Manganese 1.61E-04 9.62E-03 4.02E-05 1.24E-01 2.56E-02 Nickel 2.78E-04 1.07E-03 3.87E-02 Selenium 1.90E-03 2.48E-02 8.56E-01 Analyte Wildlife Receptor Hazard Quotient Estimated using the 'Lowest Observed Adverse Effects Level' Aquatic Mallard Duck Great Blue Heron Bald Eagle Muskrat River Otter Aluminum 6.54E-03 2.25E-07 6.54E-06 2.51E-01 1.29E-05 Arsenic 2.10E-05 1.78E-04 3.03E-02 Barium 9.58E-04 1.72E-04 6.60E-03 Chromium, Total 1.69E-04 1.44E-03 2.13E-07 Copper 1.38E-03 5.94E-04 5.65E-02 Manganese 8.31E-05 4.95E-03 2.07E-05 8.98E-02 1.86E-02 Nickel 1.62E-04 6.25E-04 1.93E-02 Selenium I 9.53E-04 1.24E-02 5.70E-01 NOTES: Hazard Quotients greater than or equal to 1 are highlighted in gray and in boldface. NM - Not measured due to lack of a Toxicity Reference Value 1 The bald eagle was added to this risk assessment model because the species is federally protected and represents a raptor that preys upon fish, primarily, while the Red -Tailed Hawk primarily preys upon small terrestrial vertebrates (e.g., rodents, snakes, etc.). Hazard quotient calculations for the Bald Eagle include hypothetical consumption of fish that inhabit adjacent surface water areas in addition to terrestrial vertebrates that inhabit adjacent areas. Table 1 Exposure Parameters for Ecological Receptors Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, NC Parameter Body Weight Food Ingestion Rate Water Ingestion Rate Dietary Composition Home Range Seasonal Use Factor' Plants Mammal/Terr. Vertebrates Fish Invertebrates Birds Soil Algorithm ID BW IRF IRw PF AM AF A, AB SF HR SUF Units kg kg/kg BW/day L/kg BW/day % % % % % % hectares unitless HERBIVORE Meadow Vole' 0.033 0.33 0.21 97.6% 0% 0% 0% 0% 2.4% 0.027 1 Muskrat' 1.17 0.3 0.97 99.3% 0% 0% 0% 0% 0.7% 0.13 1 OMNIVORE $ a Mallard Duck` 1.134 0.068 0.057 48.3% 0% 0% 48.3% 0% 3.3% 435 1 °; v American Robin' 0.08 0.129 0.14 40% 0% 0% 58% 0% 2% 0.42 1 CARNIVORE m Red -Tailed Hawke 1.06 0.18 0.058 0% 91.5% 0% 0% 8.5% 0% 876 1 0 o Bald Eaglef 3.75 0.12 0.058 0% 28% 58% 0% 13.5% 0.5% 2199 1 Red Fox' 4.54 0.16 0.085 6% 89% 0% 2% 0% 3% 1226 1 PISCIVORE River Otter' 6.76 0.19 0.081 0% 0% 100% 0% 0% 0% 348 1 Great Blue Heron' 2.229 0.18 0.045 0% 0% 90% 9.5% 0% 0.5% 227 1 NOTES: BW - Body Weight Pr - Plant Matter Ingestion Percentage kg/kg BW/day - Kilograms Food per Kilograms Body Weight per Day kg - Kilograms AM - Mammal/Terrestrial Vertebrate ingestion percentage L/kg BW/day - Liters Water per Kilogram Body Weight per Day IR - Ingestion Rate AF - Fish Ingestion Percentage HR - Home Range AB- Bird Ingestion Percentage SUF - Seasonal Use Factor SF - Soil Ingestion Percentage ' 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 `BW, PF, A,, HR from USEPA 1993 (sections 2-43 and 2-45); SF from Beyer et al. 1994; IRF from Nagy 2001 d BW, PF, Al, HR from USEPA 1993 (sections 2-197 and 2-198); SF from Sample and Suter 1994; IRF from Nagy 2001 ' BW, PF, AM, AB, IRF, HR from USEPA 1993 (sections 2-82 and 2-83) f BW, PF, AD AM, AB, HR from USEPA 1993 (sections 2-91 and 2-97); IRF from Nagy 2001 g BW, PF, AD Al, 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 BW, PF, AF, Al, HR from USEPA 1993 (sections 2-8 and 2-9); SF from Sample and Suter 1994; IRF from Nagy 2001 f Seasonal Use Factor is set to a default of 1 to be overly conservative and protective of ecological receptors. Table 2 Toxicity Reference Values for Ecological Receptors Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, INC Analyte TRVs (NOAEL) Aquatic 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 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 Barium` 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 Boron a,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, Total' 1 1 1 1 2740 2740 1 1 2740 2740 Chromium VI (hexavalent)' 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 copper 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 Lead 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 manganese 179 179 179 51.5 51.5 179 179 51.5 51.5 Mercury 3.25 3.25 3.25 1.01 1.01 3.25 3.25 1.01 1.01 Molybdenuma,l 3.53 3.53 3.53 0.26 0.26 3.53 3.53 0.26 0.26 Nickel' 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 ThaiIiuma NA NA NA 0.015 0.015 NA NA 0.015 0.015 Titanium NA NA NA NA NA NA NA NA NA Vanadium' 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 Nitrate' NA NA NA 507 507 NA NA 507 507 Table 2 (Cont.) Analyte TRVs (LOAEL) Aquatic Terrestrial Mallard Duck (mg/kg/day) Heron (mg/kg/day) Bald Eagle (mg/kg/day) Muskrat (mg/kg/day) River Otter (mg/kg/day) Robin (mg/kg/day) Hawk (mg/kg/day) Meadow Vole (mg/kg/day) Red Fox (mg/kg/day) Aluminum' 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 Barium` 41.7 41.7 41.7 75 75 41.7 41.7 75 75 Beryllium' NA NA NA 6.6 6.6 NA NA 6.6 6.6 Boron a,b 100 100 100 93.6 93.6 100 100 93.6 93.6 Cadmium' 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, Total' 5 5 5 27400 27400 5 5 27400 27400 Chromium VI (hexavalent)' 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 Cobalt' 7.8 7.8 7.8 10.9 10.9 7.8 7.8 10.9 10.9 copper 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 Lead 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 Manganese 348 348 348 71 71 348 348 71 71 Mercury' 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 Nickel' 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 ThaiIiuma NA NA NA 0.075 0.075 NA NA 0.075 0.075 Vanadium' 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 NOTES: NOAEL - No Observed Adverse Effects Level LOAEL - Lowest Observed Effects Level EN - Essential nutrient NA- Not available TRV - Toxicity Reference Value 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 b USEPA 2005 EcoSSL ` 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 Table 3 Exposure Area and Area Use Factors for Ecological Receptors Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, NC Exposure Point p Exposure Areaa Area Use Factor (AUF) Mallard Great Blue River Bald American Red -Tailed Meadow (hectares) Muskrat Red Fox Duck Heron Otter Eagle Robin Hawk Vole Water Intake Basin 14.8 3.40% 6.52% 100% 4.25% 0.67% 100% 1.689% 100% 1.21% NOTES: a The Water Intake Basin Exposure Area is noth of the Gypsum Storage and Ash Basins and includes aquatic habitat. Table 4 EPCs for Use in the Risk Assessment Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, NC Aquatic EPCsa, b COPC CASRN Sediment EPC Used in Risk Assessment` (mg/kg) Surface Water EPC Used in Risk Assessment (mg/L) Aluminum 7429-90-5 1.348 Barium 7440-39-3 100 1.093 Copper 7440-50-8 51 Manganese 7439-96-5 1,000 1.159 Selenium 7782-49-2 0.85 Zinc 7440-66-6 1.064 Created By: TCP Checked By: HES Revised By: TCP Checked By: HES COPC - Constituent of Potential Concern CASRN - Chemical Abstracts Service Registration Number EPC - Exposure Point Concentration a EPCs for surface water are based on 95% UCLs. EPCs for sediment are based on maximum concentrations. b Aquatic receptors in this area are evaluated using surface water and sediment data. `Analysis of solids (i.e., soil and sediment) was reported as dry weight. AVEILAGE DAILY DOSE VIA ., —ER ADP—/VEGE-DON 1 1 INVERTrES, ADD. S- FEP—�--] EK k I N I P, I Nik I NIR. I ADD. A, N I S, I MIRL I ADDI IF I ADD, EPC N­.1—ml—Illim EF Fedor S F EII.—I Use FA-, N.1-1- ­1 .1 R- BAF B—L— — FFI,t., AUF Brea U. F.— ADDD— BCF BA--t-., FA-, —.—F—L-OV--M .... ' F 1998b, le - for .— 1. —hil k, C� C., DO, NI, Pb, — Sple .1 a,, I Table 1D Calculation W Average DWIV Doses for Great Bloe Hemn Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, $emara, NC AVERAGE DAILY DOSE VIA: IF WATER FISH INVERTEBRATES T A. MR. I ADD_ NOTES: EPC-Exposure Point ConcentmtioR BF- Bioavailability Faclm SUF- Seasonal Use Factor NIR- Normalized ingmtml It- BAF-Bioacamulation Factor AUF - Area Use Factor ADD- Average Daily Dose BCF-Bioconcenbalion Factor ' Al (Volgt et M. 2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division - Manual ERD-AG-0031999. ' Bechtel Jacobs Company 1998b, Table 2, median RAF, for sediment to benthic invertebrates for As, Cd, Cr, Cu, H& Ni, Pb, and Zn; Sample et a1. 1999b (earthworm,) for Mn; default value of 1 is used for constituents for which a BAF could not be found. ' Bioavailability is set to a default of 100%to be conservative and protective of ecological receptors. Table 11 CeNola[Ion of Average Daily Doses for Bald Eagle Water Intake Basin Duke Energy Roxboro Steam Electric Plant, Semora, NC NOTES: EPC- Exposure Point Concentration BF- Bioavailability Factor SUF-SeasonalUseF.— NIP-Normala.dlog—rt Rate BAF-Bioaccumuladon F.— AUF-Area Use Factor ADD- Average Daily Dose BCF-Bioconceniration Factor r Sampleeta1. 1998a;EPA20DJE Ly Att-,Table Oa r AI (Voigt et al.2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division- Manual EP0.AG-0031999. a eioavailability Is setto a default of S00%to be conservative and protective of ecological receptors. Table 12 Calculation of Average Daily Doses for Muskrat Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, NC AVERAGE DAILY DOSE VIA: WATER PLANTS / VEGETATION SOIL EPC... EPC. EPC_ NIR— ADD... P. NIR NIR_ ADD_ S. NIR. ADD. BF ADD. SUF ALIF ADD... NOTES: EPC - Expo sure Point Concentration BF- Bioavailabllily, Factor SUF- Seasonal Use Factor NIR- Normalized Ingestion Rate BAF- Bioaccumulation Factor AUF - Area Use Factor ADD- Average Daily Dose BCF- Bicconcentrsticn Factor ' Bechtel Jacobs Company 1998a; Baes et al. 1984 (Me); Environmental Restoration Division - Manual ERD-AG-0031999; default value of 1 is used for constituents for which a BAF could not be found. z..availability is set to a default of 100%to be conservative and protective of ecological receptors. Table 13 Calculation of Average Daily Doses for River Otter Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, NC AVERAGE DAILY DOSE VIA: DRINKING WATER I FISH NIRw ADDw Pr NIRr NIRa ADDa BF ADD, SUF AUF ADD_ EPCw EPC, EPCPRrY Area Use Adjusted Total Unadjusted Unadjusted COPEC in COPEC in Solid Fish Uptake Estimated' Water Average Daily Fraction Diet Food Ingestion Fish Ingestion Average Daily Bioavailability' Piscivore Seasonal Use Factor Piscivore (rang) Concentration Ingestion ion Ingestion Rate Animal Matter Rate, Wet Rate (kg/kg Intake Factor (Exposure Average Daily Water (mg/L) (mg/kg) (BCF) Dose Water Dose (percent) Analyte in Fish day) (mg/kg/day) (percent) (kg/kg BW/day) BW/day) (mg/kg/day) (mg/kg/day) (unitless) Area/Home Range) Dose (mg/kg/day) Aluminum 1.348 0.1 0.13 0.081 0.109 100% 0.19 0.19 0.0256 100% 0.135 1 0.043 0.005733 Barium 1.093 100 4 4.37 0.081 0.089 100% 0.19 0.19 0.831 100% 0.92 1 0.043 0.039093 Copper 51 50 0 0.081 10 100% 0.19 0.19 0 100% 0 1 0.043 0 Manganese 1.159 1,000 400 463.6 0.081 0.094 100% 0.19 0.19 88.08 100% 88.178 1 0.043 3.75009 Selenium 0.85 8 0 0.081 0 100% 0.19 0.19 0 100% 0 1 0.043 0 Zinc 1.064 1,000 1,064 0.081 0.086 100% 0.19 0.19 202.16 100% 202.246 1 0.043 8.601274 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 Al (Voigt et al. 2015), mean of fish tissue BAFs; Cu (USEPA 1980); Environmental Restoration Division - Manual ERD-AG-003 1999. 1 Bioavailability is set to a default of 100% to be conservative and protective of ecological receptors. Table 15 Hazard Quotients for COPCs - Aquatic Receptors Water Intake Basin Baseline Ecological Risk Assessment Duke Energy Roxboro Steam Electric Plant, Semora, NC Analyte Wildlife Receptor Hazard Quotient Estimated using the 'No Observed Adverse Effects Level' Aquatic Mallard Duck Great Blue Heron Bald Eagle Muskrat River Otter Aluminum 2.38E-05 5.19E-05 6.12E-05 6.77E-01 2.97E-03 Barium 1.36E-03 2.39E-03 3.24E-04 2.31E-02 7.55E-04 Copper 5.32E-03 1.66E-03 7.37E-02 Manganese I 1.83E-04 2.74E-02 3.76E-05 6.59E-02 7.28E-02 Selenium 7.79E-04 2.32E-02 1.33E-01 Zinc 3.12E-05 4.26E-02 1.02E-04 1.37E-02 1.14E-01 Analyte Wildlife Receptor Hazard Quotient Estimated using the 'Lowest Observed Adverse Effects Level' Aquatic Mallard Duck Great Blue Heron Bald Eagle` Muskrat River Otter Aluminum 2.38E-06 5.19E-06 6.12E-06 6.77E-02 2.97E-04 Barium 6.76E-04 1.19E-03 1.61E-04 1.60E-02 5.21E-04 Copper 1.78E-03 5.56E-04 4.42E-02 Manganese I 9.40E-05 1.41E-02 1.93E-05 4.78E-02 5.28E-02 Selenium 3.90E-04 1.16E-02 8.83E-02 Zinc 3.10E-05 I 4.23E-02 I 1.01E-04 I 1.36E-02 I 1.13E-01 NOTES: Hazard Quotients greater than or equal to 1 are highlighted in gray and in boldface. NM - Not measured due to lack of a Toxicity Reference Value 1 The bald eagle was added to this risk assessment model because the species is federally protected and represents a raptor that preys upon fish, primarily, while the Red -Tailed Hawk primarily preys upon small terrestrial vertebrates (e.g., rodents, snakes, etc.). Hazard quotient calculations for the Bald Eagle include hypothetical consumption of fish that inhabit adjacent surface water areas in addition to terrestrial vertebrates that inhabit adjacent areas. Appendix C Exposure Modeling and Human Health Risk Assessment for Diesel Emissions Air Dispersion Modeling for Roxboro 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 Roxboro Plant. The calculated cancer and non -cancer risks are associated with increased diesel trucking activity near residential properties that lie along transportation corridors near the Roxboro Plant. Modelling was conducted for ten closure options representing all possible combinations of three closure methods for the east ash basin (EAB) and the west ash basin (WAB): cap -in -place (CIP), excavation to an offsite landfill, and hybrid closure, as well as a tenth option for excavation of both the EAB and WAB to onsite landfills. For closure options involving excavation to an offsite landfill of either of the ash basins or hybrid closure of the EAB, ash from the closure by removal areas will be hauled to lined landfills at the nearby Mayo Plant for disposal. Details of these closure options 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. 1707466.000 - 3651 C-1 Methodology Meteorological Data AERMOD-ready five -years 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 Danville Regional Airport (KDAN) in Danville, Virginia.2 The Danville Regional Airport is located approximately 33 km from Duke Energy's Roxboro Plant. I judged this station to be representative of the meteorology in the region of the Roxboro Plant. Surface parameters applied to the modeling study included wind speed and direction, temperature, pressure, relative humidity, and cloud cover. Twice daily rawinsonde3 observations of upper air winds and temperatures were taken from Greensboro, North Carolina (KGSO), which, at 105 km from Roxboro Plant, is the closest upper air sounding site.4 The meteorological data were processed using AERMET (v16216) with default options.5 To better resolve lower wind speeds and avoid over -estimating calm conditions, AERMINUTE was also applied.6 AERSURFACE7 was used to define the land -use characteristics in the region around the surface observational site (i.e., Danville Regional Airport). The surface 1 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). 2 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.goy//pub/data/asos-onemin/. 3 A rawinsonde is a device typically carried by weather balloons that collects meteorological and atmospheric data, especially regarding winds. 4 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 Danville, Virginia, and, by extension, at the Roxboro Plant. 5 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). 6 Because the Danville Regional 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. 7 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. 1707466.000 - 3651 C-2 characteristics, which are important when calculating the level of atmospheric dispersion in meteorological modeling, include surface roughness, albedo,8 and Bowen ratio.9 Trucking Operations Diesel emissions estimates from trucking are based on the number of trucks passing a given receptor location along transportation corridors used during ash basin closure. The total number of truckloads required for transporting ash, earthen fill, and geosynthetic materials under the Roxboro closure options were projected by Duke Energy (2018a,b). These truckloads equate to a minimum of 11,134 total truck passes for the CIP/CIP closure option and a maximum of 1,745,252 total truck passes for Excavation Offsite/Excavation Offsite closure. The total truck passes for the other options are (EAB/WAB): CIP/Excavation Offsite = 1,431,403, CIP/Hybrid = 129,470, Excavation Offsite/CIP = 425,182, Excavation Offsite/Hybrid = 443,318, Hybrid/CIP = 137,734, Hybrid/Excavation Offsite = 1,457,804, Hybrid/Hybrid = 155,870, and Excavation Onsite/Excavation Onsite = 176,433. I included loads hauling ash (excavation closure to offsite landfill only), earthen fill, geosynthetic materials, and other materials in transportation emissions estimates. Trucks hauling ash and earthen fill are assumed to travel 15 miles one way from the site (the estimated distance to the Mayo Plant), and trucks hauling geosynthetic material are assumed to travel 275 miles one way from Georgetown, South Carolina. Air modeling is conducted for a receptor along the transportation route within the radius traveled by trucks hauling ash, earthen fill, and geosynthetic material. Trucks are assumed to travel in round trips, so the number of material loads was doubled to represent the number of truck passes. 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 a 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. 9 Bowen ratio is the ratio of sensible to latent heat fluxes from the earth's surface up into the air. Lower Bowen ratio indicates greater water content in the land surface. 1707466.000 - 3651 C-3 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 between 10 and 150 in 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. 1707466.000 - 3651 C-4 Figure C-1. Location of road sources (blue) and sampling receptors (red) for each of 4 road orientations 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). The 2050 emission factors were retained for all years 1707466.000 - 3651 C-5 after 2050. 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 PMio 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 option. 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 factorlo to quantify cancer risk. For the non -cancer analysis, airborne concentrations of DPM were calculated and compared to the non -cancer risk threshold of 5 µg/m3.11 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. io A "reasonable estimate" for the inhalation unit risk of 3.OX 10-4 (µg/m3)-1 was applied based on California guidelines (OEHHA 2015). " North Carolina defers to the 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). 1707466.000 - 3651 C-6 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. Longer averaging periods, such as those used in this study, would often have lower uncertainties as 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. 1707466.000 - 3651 C-/ 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. 1707466.000 - 3651 p C-O Table C-1. ELCR estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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/CIP 10 m 1.7E-08 1.6E-08 2.0E-08 2.3E-08 1.8E-08 1.4E-08 1.3E-08 1.3E-08 20 m 1.6E-08 1.5E-08 1.6E-08 1.8E-08 1.7E-08 1.3E-08 1.3E-08 1.4E-08 30 m 1.3E-08 1.2E-08 1.3E-08 1.4E-08 1.4E-08 1.1E-08 1.1E-08 1.2E-08 40 m 1.1E-08 9.7E-09 1.0E-08 1.2E-08 1.2E-08 8.9E-09 9.2E-09 1.0E-08 50 m 9.3E-09 8.3E-09 8.5E-09 1.0E-08 1.0E-08 7.7E-09 7.9E-09 8.8E-09 60 m 8.2E-09 7.2E-09 7.3E-09 8.7E-09 8.8E-09 6.7E-09 7.0E-09 7.8E-09 70 m 7.3E-09 6.4E-09 6.3E-09 7.7E-09 7.8E-09 6.0E-09 6.3E-09 7.0E-09 80 m 6.6E-09 5.7E-09 5.5E-09 6.8E-09 7.0E-09 5.4E-09 5.7E-09 6.3E-09 90 m 6.1E-09 5.2E-09 4.9E-09 6.1E-09 6.4E-09 5.0E-09 5.2E-09 5.8E-09 100 m 5.6E-09 4.7E-09 4.4E-09 5.5E-09 5.9E-09 4.6E-09 4.8E-09 5.3E-09 110 m 5.2E-09 4.3E-09 4.0E-09 5.0E-09 5.4E-09 4.3E-09 4.4E-09 5.0E-09 120 m 4.8E-09 4.0E-09 3.7E-09 4.6E-09 5.0E-09 4.0E-09 4.1E-09 4.6E-09 130 m 4.5E-09 3.7E-09 3.4E-09 4.3E-09 4.7E-09 3.7E-09 3.9E-09 4.3E-09 140 m 4.2E-09 3.5E-09 3.1E-09 3.9E-09 4.3E-09 3.5E-09 3.7E-09 4.1E-09 150 m 4.0E-09 3.3E-09 2.9E-09 3.6E-09 4.1E-09 3.3E-09 3.5E-09 3.9E-09 CIP/Excavation Mite 10 m 1.3E-07 1.2E-07 1.6E-07 1.7E-07 1.4E-07 1.1E-07 1.0E-07 1.0E-07 20 m 1.2E-07 1.1E-07 1.3E-07 1.4E-07 1.3E-07 1.0E-07 1.0E-07 1.1E-07 30 m 9.9E-08 9.0E-08 9.7E-08 1.1E-07 1.1E-07 8.1E-08 8.3E-08 9.2E-08 40 m 8.3E-08 7.5E-08 7.8E-08 9.1E-08 8.9E-08 6.8E-08 7.0E-08 7.8E-08 50 m 7.2E-08 6.3E-08 6.5E-08 7.7E-08 7.7E-08 5.9E-08 6.1E-08 6.8E-08 60 m 6.3E-08 5.5E-08 5.6E-08 6.7E-08 6.7E-08 5.2E-08 5.4E-08 6.0E-08 70 m 5.6E-08 4.9E-08 4.8E-08 5.9E-08 6.0E-08 4.6E-08 4.8E-08 5.4E-08 80 m 5.1E-08 4.4E-08 4.3E-08 5.2E-08 5.4E-08 4.2E-08 4.3E-08 4.9E-08 90 m 4.6E-08 4.0E-08 3.8E-08 4.7E-08 4.9E-08 3.8E-08 4.0E-08 4.4E-08 100 m 4.3E-08 3.6E-08 3.4E-08 4.3E-08 4.5E-08 3.5E-08 3.7E-08 4.1E-08 110 m 4.0E-08 3.3E-08 3.1E-08 3.9E-08 4.1E-08 3.3E-08 3.4E-08 3.8E-08 120 m 3.7E-08 3.1E-08 2.8E-08 3.5E-08 3.8E-08 3.0E-08 3.2E-08 3.5E-08 130 m 3.4E-08 2.9E-08 2.6E-08 3.3E-08 3.6E-08 2.9E-08 3.0E-08 3.3E-08 140 m 3.2E-08 2.7E-08 2.4E-08 3.0E-08 3.3E-08 2.7E-08 2.8E-08 3.1E-08 150 m 3.0E-08 2.5E-08 2.2E-08 2.8E-08 3.1E-08 2.5E-08 2.7E-08 3.0E-08 1707466.000 - 3651 C-9 Table C-1. (cont). ELCR estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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/Hybrid 10 m 1.6E-08 1.5E-08 1.9E-08 2.2E-08 1.7E-08 1.3E-08 1.3E-08 1.3E-08 20 m 1.5E-08 1.4E-08 1.6E-08 1.8E-08 1.6E-08 1.3E-08 1.3E-08 1.4E-08 30 m 1.2E-08 1.1E-08 1.2E-08 1.4E-08 1.3E-08 1.0E-08 1.0E-08 1.1E-08 40 m 1.0E-08 9.3E-09 9.8E-09 1.1E-08 1.1E-08 8.5E-09 8.8E-09 9.7E-09 50 m 8.9E-09 7.9E-09 8.1E-09 9.6E-09 9.6E-09 7.3E-09 7.6E-09 8.4E-09 60 m 7.9E-09 6.9E-09 7.0E-09 8.3E-09 8.4E-09 6.4E-09 6.7E-09 7.5E-09 70 m 7.0E-09 6.1E-09 6.0E-09 7.3E-09 7.5E-09 5.8E-09 6.0E-09 6.7E-09 80 m 6.4E-09 5.5E-09 5.3E-09 6.5E-09 6.7E-09 5.2E-09 5.4E-09 6.1E-09 90 m 5.8E-09 4.9E-09 4.7E-09 5.9E-09 6.1E-09 4.8E-09 5.0E-09 5.5E-09 100 m 5.3E-09 4.5E-09 4.3E-09 5.3E-09 5.6E-09 4.4E-09 4.6E-09 5.1E-09 110 m 4.9E-09 4.1E-09 3.9E-09 4.8E-09 5.2E-09 4.1E-09 4.3E-09 4.7E-09 120 m 4.6E-09 3.8E-09 3.5E-09 4.4E-09 4.8E-09 3.8E-09 4.0E-09 4.4E-09 130 m 4.3E-09 3.6E-09 3.2E-09 4.1E-09 4.5E-09 3.6E-09 3.7E-09 4.2E-09 140 m 4.0E-09 3.3E-09 3.0E-09 3.8E-09 4.2E-09 3.4E-09 3.5E-09 3.9E-09 150 m 3.8E-09 3.1E-09 2.7E-09 3.5E-09 3.9E-09 3.2E-09 3.3E-09 3.7E-09 Excavation Offsite/CIP 10 m 6.5E-08 6.2E-08 7.7E-08 8.6E-08 6.8E-08 5.3E-08 5.0E-08 5.1E-08 20 m 6.1E-08 5.6E-08 6.3E-08 7.0E-08 6.5E-08 5.0E-08 5.1E-08 5.5E-08 30 m 4.9E-08 4.5E-08 4.9E-08 5.5E-08 5.3E-08 4.1E-08 4.2E-08 4.6E-08 40 m 4.1E-08 3.7E-08 3.9E-08 4.5E-08 4.4E-08 3.4E-08 3.5E-08 3.9E-08 50 m 3.6E-08 3.2E-08 3.2E-08 3.8E-08 3.8E-08 2.9E-08 3.0E-08 3.4E-08 60 m 3.1E-08 2.7E-08 2.8E-08 3.3E-08 3.4E-08 2.6E-08 2.7E-08 3.0E-08 70 m 2.8E-08 2.4E-08 2.4E-08 2.9E-08 3.0E-08 2.3E-08 2.4E-08 2.7E-08 80 m 2.5E-08 2.2E-08 2.1E-08 2.6E-08 2.7E-08 2.1E-08 2.2E-08 2.4E-08 90 m 2.3E-08 2.0E-08 1.9E-08 2.3E-08 2.4E-08 1.9E-08 2.0E-08 2.2E-08 100 m 2.1E-08 1.8E-08 1.7E-08 2.1E-08 2.2E-08 1.8E-08 1.8E-08 2.0E-08 110 m 2.0E-08 1.7E-08 1.5E-08 1.9E-08 2.1E-08 1.6E-08 1.7E-08 1.9E-08 120 m 1.8E-08 1.5E-08 1.4E-08 1.8E-08 1.9E-08 1.5E-08 1.6E-08 1.8E-08 130 m 1.7E-08 1.4E-08 1.3E-08 1.6E-08 1.8E-08 1.4E-08 1.5E-08 1.7E-08 140 m 1.6E-08 1.3E-08 1.2E-08 1.5E-08 1.7E-08 1.3E-08 1.4E-08 1.6E-08 150 m 1.5E-08 1.2E-08 1.1E-08 1.4E-08 1.6E-08 I 1.3E-08 1.3E-08 1.5E-08 1707466.000 - 3651 C-10 Table C-1. (cont). ELCR estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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 Ottsite/Excavation Ottsite 10 m 1.6E-07 1.5E-07 1.9E-07 2.1E-07 1.7E-07 1.3E-07 1.2E-07 1.3E-07 20 m 1.5E-07 1.4E-07 1.5E-07 1.7E-07 1.6E-07 1.2E-07 1.2E-07 1.4E-07 30 m 1.2E-07 1.1E-07 1.2E-07 1.3E-07 1.3E-07 9.9E-08 1.0E-07 1.1E-07 40 m 1.0E-07 9.1E-08 9.6E-08 1.1E-07 1.1E-07 8.3E-08 8.6E-08 9.5E-08 50 m 8.7E-08 7.7E-08 8.0E-08 9.4E-08 9.4E-08 7.2E-08 7.4E-08 8.2E-08 60 m 7.7E-08 6.7E-08 6.8E-08 8.1E-08 8.2E-08 6.3E-08 6.5E-08 7.3E-08 70 m 6.9E-08 6.0E-08 5.9E-08 7.2E-08 7.3E-08 5.6E-08 5.8E-08 6.5E-08 80 m 6.2E-08 5.3E-08 5.2E-08 6.4E-08 6.6E-08 5.1E-08 5.3E-08 5.9E-08 90 m 5.7E-08 4.8E-08 4.6E-08 5.7E-08 6.0E-08 4.6E-08 4.8E-08 5.4E-08 100 m 5.2E-08 4.4E-08 4.2E-08 5.2E-08 5.5E-08 4.3E-08 4.5E-08 5.0E-08 110 m 4.8E-08 4.0E-08 3.8E-08 4.7E-08 5.0E-08 4.0E-08 4.2E-08 4.6E-08 120 m 4.5E-08 3.7E-08 3.4E-08 4.3E-08 4.7E-08 3.7E-08 3.9E-08 4.3E-08 130 m 4.2E-08 3.5E-08 3.1E-08 4.0E-08 4.3E-08 3.5E-08 3.6E-08 4.1E-08 140 m 3.9E-08 3.3E-08 2.9E-08 3.7E-08 4.1E-08 3.3E-08 3.4E-08 3.8E-08 150 m 3.7E-08 3.0E-08 2.7E-08 3.4E-08 3.8E-08 3.1E-08 3.2E-08 3.6E-08 Excavation Offsite/Hybrid 10 m 5.6E-08 5.3E-08 6.6E-08 7.4E-08 5.9E-08 4.6E-08 4.3E-08 4.4E-08 20 m 5.2E-08 4.8E-08 5.4E-08 6.0E-08 5.6E-08 4.3E-08 4.4E-08 4.7E-08 30 m 4.2E-08 3.8E-08 4.2E-08 4.7E-08 4.5E-08 3.5E-08 3.6E-08 3.9E-08 40 m 3.5E-08 3.2E-08 3.4E-08 3.9E-08 3.8E-08 2.9E-08 3.0E-08 3.3E-08 50 m 3.1E-08 2.7E-08 2.8E-08 3.3E-08 3.3E-08 2.5E-08 2.6E-08 2.9E-08 60 m 2.7E-08 2.4E-08 2.4E-08 2.9E-08 2.9E-08 2.2E-08 2.3E-08 2.6E-08 70 m 2.4E-08 2.1E-08 2.1E-08 2.5E-08 2.6E-08 2.0E-08 2.0E-08 2.3E-08 80 m 2.2E-08 1.9E-08 1.8E-08 2.2E-08 2.3E-08 1.8E-08 1.9E-08 2.1E-08 90 m 2.0E-08 1.7E-08 1.6E-08 2.0E-08 2.1E-08 1.6E-08 1.7E-08 1.9E-08 100 m 1.8E-08 1.5E-08 1.5E-08 1.8E-08 1.9E-08 1.5E-08 1.6E-08 1.8E-08 110 m 1.7E-08 1.4E-08 1.3E-08 1.7E-08 1.8E-08 1.4E-08 1.5E-08 1.6E-08 120 m 1.6E-08 1.3E-08 1.2E-08 1.5E-08 1.6E-08 1.3E-08 1.4E-08 1.5E-08 130 m 1.5E-08 1.2E-08 1.1E-08 1.4E-08 1.5E-08 1.2E-08 1.3E-08 1.4E-08 140 m 1.4E-08 1.1E-08 1.0E-08 1.3E-08 1.4E-08 1.1E-08 1.2E-08 1.3E-08 150 m 1.3E-08 1.1E-08 9.4E-09 1.2E-08 1.3E-08 1.1E-08 1.1E-08 1.3E-08 1707466.000 - 3651 C-11 Table C-1. (cont). ELCR estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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 Hybrid/CI P 10 m 2.1E-08 2.0E-08 2.5E-08 2.8E-08 2.2E-08 1.7E-08 1.6E-08 1.7E-08 20 m 2.0E-08 1.8E-08 2.0E-08 2.3E-08 2.1E-08 1.6E-08 1.6E-08 1.8E-08 30 m 1.6E-08 1.5E-08 1.6E-08 1.8E-08 1.7E-08 1.3E-08 1.3E-08 1.5E-08 40 m 1.3E-08 1.2E-08 1.3E-08 1.5E-08 1.4E-08 1.1E-08 1.1E-08 1.3E-08 50 m 1.2E-08 1.0E-08 1.1E-08 1.2E-08 1.2E-08 9.5E-09 9.8E-09 1.1E-08 60 m 1.0E-08 8.9E-09 9.0E-09 1.1E-08 1.1E-08 8.3E-09 8.6E-09 9.6E-09 70 m 9.1E-09 7.9E-09 7.8E-09 9.5E-09 9.7E-09 7.4E-09 7.7E-09 8.6E-09 80 m 8.2E-09 7.1E-09 6.9E-09 8.4E-09 8.7E-09 6.7E-09 7.0E-09 7.8E-09 90 m 7.5E-09 6.4E-09 6.1E-09 7.6E-09 7.9E-09 6.2E-09 6.4E-09 7.2E-09 100 m 6.9E-09 5.8E-09 5.5E-09 6.9E-09 7.2E-09 5.7E-09 5.9E-09 6.6E-09 110 m 6.4E-09 5.4E-09 5.0E-09 6.2E-09 6.7E-09 5.3E-09 5.5E-09 6.1E-09 120 m 5.9E-09 5.0E-09 4.5E-09 5.7E-09 6.2E-09 4.9E-09 5.1E-09 5.7E-09 130 m 5.6E-09 4.6E-09 4.2E-09 5.3E-09 5.8E-09 4.6E-09 4.8E-09 5.4E-09 140 m 5.2E-09 4.3E-09 3.8E-09 4.9E-09 5.4E-09 4.3E-09 4.5E-09 5.1E-09 150 m 4.9E-09 4.0E-09 3.6E-09 4.5E-09 5.0E-09 4.1E-09 4.3E-09 4.8E-09 Hybrid/Excavation Offsite 10 m 1.3E-07 1.3E-07 1.6E-07 1.8E-07 1.4E-07 1.1E-07 1.0E-07 1.0E-07 20 m 1.2E-07 1.1E-07 1.3E-07 1.4E-07 1.3E-07 1.0E-07 1.0E-07 1.1E-07 30 m 1.0E-07 9.2E-08 9.9E-08 1.1E-07 1.1E-07 8.3E-08 8.5E-08 9.3E-08 40 m 8.5E-08 7.6E-08 8.0E-08 9.3E-08 9.1E-08 6.9E-08 7.2E-08 7.9E-08 50 m 7.3E-08 6.5E-08 6.6E-08 7.8E-08 7.8E-08 6.0E-08 6.2E-08 6.9E-08 60 m 6.4E-08 5.6E-08 5.7E-08 6.8E-08 6.9E-08 5.3E-08 5.5E-08 6.1E-08 70 m 5.7E-08 5.0E-08 4.9E-08 6.0E-08 6.1E-08 4.7E-08 4.9E-08 5.5E-08 80 m 5.2E-08 4.5E-08 4.3E-08 5.3E-08 5.5E-08 4.2E-08 4.4E-08 4.9E-08 90 m 4.7E-08 4.0E-08 3.9E-08 4.8E-08 5.0E-08 3.9E-08 4.0E-08 4.5E-08 100 m 4.4E-08 3.7E-08 3.5E-08 4.3E-08 4.6E-08 3.6E-08 3.7E-08 4.2E-08 110 m 4.0E-08 3.4E-08 3.1E-08 3.9E-08 4.2E-08 3.3E-08 3.5E-08 3.9E-08 120 m 3.8E-08 3.1E-08 2.9E-08 3.6E-08 3.9E-08 3.1E-08 3.2E-08 3.6E-08 130 m 3.5E-08 2.9E-08 2.6E-08 3.3E-08 3.6E-08 2.9E-08 3.0E-08 3.4E-08 140 m 3.3E-08 2.7E-08 2.4E-08 3.1E-08 3.4E-08 2.7E-08 2.9E-08 3.2E-08 150 m 3.1E-08 2.5E-08 2.2E-08 2.8E-08 3.2E-08 2.6E-08 2.7E-08 3.0E-08 1707466.000 - 3651 C-12 Table C-1. (cont). ELCR estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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 Hybrid/Hybrid 10 m 2.0E-08 1.9E-08 2.3E-08 2.6E-08 2.1E-08 1.6E-08 1.5E-08 1.5E-08 20 m 1.8E-08 1.7E-08 1.9E-08 2.1E-08 2.0E-08 1.5E-08 1.5E-08 1.7E-08 30 m 1.5E-08 1.4E-08 1.5E-08 1.7E-08 1.6E-08 1.2E-08 1.3E-08 1.4E-08 40 m 1.2E-08 1.1E-08 1.2E-08 1.4E-08 1.3E-08 1.0E-08 1.1E-08 1.2E-08 50 m 1.1E-08 9.5E-09 9.8E-09 1.2E-08 1.2E-08 8.8E-09 9.1E-09 1.0E-08 60 m 9.5E-09 8.3E-09 8.4E-09 1.0E-08 1.0E-08 7.8E-09 8.1E-09 9.0E-09 70 m 8.5E-09 7.3E-09 7.3E-09 8.8E-09 9.0E-09 6.9E-09 7.2E-09 8.0E-09 80 m 7.7E-09 6.6E-09 6.4E-09 7.8E-09 8.1E-09 6.3E-09 6.5E-09 7.3E-09 90 m 7.0E-09 5.9E-09 5.7E-09 7.0E-09 7.4E-09 5.7E-09 6.0E-09 6.7E-09 100 m 6.4E-09 5.4E-09 5.1E-09 6.4E-09 6.7E-09 5.3E-09 5.5E-09 6.2E-09 110 m 5.9E-09 5.0E-09 4.6E-09 5.8E-09 6.2E-09 4.9E-09 5.1E-09 5.7E-09 120 m 5.5E-09 4.6E-09 4.2E-09 5.3E-09 5.8E-09 4.6E-09 4.8E-09 5.3E-09 130 m 5.2E-09 4.3E-09 3.9E-09 4.9E-09 5.4E-09 4.3E-09 4.5E-09 5.0E-09 140 m 4.9E-09 4.0E-09 3.6E-09 4.5E-09 5.0E-09 4.0E-09 4.2E-09 4.7E-09 150 m 4.6E-09 3.8E-09 3.3E-09 4.2E-09 4.7E-09 3.8E-09 4.0E-09 4.4E-09 Excavation Onsite/ Excavation Onsite 10 m 1.3E-08 1.3E-08 1.6E-08 1.8E-08 1.4E-08 1.1E-08 1.0E-08 1.0E-08 20 m 1.2E-08 1.1E-08 1.3E-08 1.4E-08 1.3E-08 1.0E-08 1.0E-08 1.1E-08 30 m 1.0E-08 9.2E-09 9.9E-09 1.1E-08 1.1E-08 8.3E-09 8.5E-09 9.4E-09 40 m 8.5E-09 7.6E-09 8.0E-09 9.3E-09 9.1E-09 7.0E-09 7.2E-09 7.9E-09 50 m 7.3E-09 6.5E-09 6.6E-09 7.8E-09 7.8E-09 6.0E-09 6.2E-09 6.9E-09 60 m 6.4E-09 5.6E-09 5.7E-09 6.8E-09 6.9E-09 5.3E-09 5.5E-09 6.1E-09 70 m 5.7E-09 5.0E-09 4.9E-09 6.0E-09 6.1E-09 4.7E-09 4.9E-09 5.5E-09 80 m 5.2E-09 4.5E-09 4.3E-09 5.3E-09 5.5E-09 4.3E-09 4.4E-09 4.9E-09 90 m 4.7E-09 4.0E-09 3.9E-09 4.8E-09 5.0E-09 3.9E-09 4.1E-09 4.5E-09 100 m 4.4E-09 3.7E-09 3.5E-09 4.3E-09 4.6E-09 3.6E-09 3.7E-09 4.2E-09 110 m 4.0E-09 3.4E-09 3.1E-09 3.9E-09 4.2E-09 3.3E-09 3.5E-09 3.9E-09 120 m 3.8E-09 3.1E-09 2.9E-09 3.6E-09 3.9E-09 3.1E-09 3.2E-09 3.6E-09 130 m 3.5E-09 2.9E-09 2.6E-09 3.3E-09 3.6E-09 2.9E-09 3.0E-09 3.4E-09 140 m 3.3E-09 2.7E-09 2.4E-09 3.1E-09 3.4E-09 2.7E-09 2.9E-09 3.2E-09 150 m 3.1E-09 2.5E-09 2.2E-09 2.8E-09 3.2E-09 2.6E-09 2.7E-09 3.0E-09 1707466.000 - 3651 C-13 Model -estimated non -cancer risk HI results for the four road orientations and both sides of the road are provided in Table C-2. 1707466.000 - 3651 C-14 Table C-2. HI estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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/CIP 111 111 .111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 111 111 .111 111 .111 111 .111 111 111 111 , 111 111 .111 1111 .1111 111 1 111 1 111 , 1 111 1 11 . 1 11 1 111 . 1 111 1 111 1 111 1 111 . 1 111 1 111 . 1 111 1 111 . 1 1/ 1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 . 1 111 1 111 . 1 111 1 111 . 1 1/ 1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 11 1 111 1 111 . 1 111 1 111 . 1 111 1 111 . 1 1 / 1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/ 1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 / 11 1 111 . 1 111 1 111 . 1 111 1 111 . 1 1 / 1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 /11 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 CIP/Excavation Offsite 111 111 , 111 111 .111 111 .111 111 1/1 111 , 111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 �1 111 111 .111 111 .111 111 .111 111 111 111 .111 111 .111 111 .111 111 111 111 .111 111 .111 111 .111 111 .� 111 111 .111 111 .111 111 .111 111 11 111 111 .111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 111 111 , 1111 111 .111 111 .111 111 1 11 1 111 , 1 111 1 11 . 1 11 1 111 . 1 111 1 11 1 11 1 111 , 1 11/ 1 11 . 1 11 1 1/1 . 1 111 1 11 1 11 1 111 , 1 111 1 111 . 1 11 1 111 . 1 111 1 111 1707466.000 - 3651 C-15 Table C-2. (cont). HI estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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/Hybrid 1 11 1 11 , 1 11 1 11 . 1 11 1 111 . 1 111 1 111 1 111 1 111 , 1 11 1 11 . 1 11 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 /11 . 1 111 1 111 . 1 1/1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 ,1 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 11/ . 1 111 1 111 1 11 / 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 11 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 11 / 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 11 / 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 Excavation Offsite/CIP 1 11 I II , I II 1 11� . 1 11 111 . 1 11 1 11 111 111 , 111 111 .111 111 .111 111 1 11 I I I , I I I 1 11 . 111 1 11 . 1 11 1 11 1 11 I II , I II 1 11 . 111 1 11 . 1 II 1 11 .1 111 111 , 111 111 .111 111 .11/ 111 1 11 I I I , I I I 1 11 . 1 11 111 . 1 11 1 11 111 111 , 111 111 .111 111 .11/ 111 •1 1 11 I I I , 1 11 1 11 . 1 11 111 . 1 11 1 11 11 1 11 1 11 , 1 11 1 / 1 . 1 11 1 11 . 1 11 1 11 111 111 .111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .11/ 111 111 111 , 111 111 .111 111 .111 111 1707466.000 - 3651 C-16 Table C-2. (cont). HI estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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 Offs ite/Excavati on Offsite 111 111 .111 111� .111 111 .111 111 111 111 .111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 ,1 111 111 .111 111 .111 111 .111 111 111 111 .111 111 .111 111 .111 111 111 111 , 111 1/1 . / 11 111 .111 111 111 111 .111 111 .111 111 .111 111 11 111 111 , 111 111 .111 111 .111 111 111 111 .111 111 .111 111 .111 111 111 111 , 111 111 .111 111 .111 111 111 111 .111 111 .111 111 .111 111 111 111 .1111 111 .111 111 .111 111 111 111 , 1111 111 .111 111 .111 111 Excavation Offsite/Hybrid 111 111 .111 111 .111 111 .111 111 1 11 I I I . 1 11 1 11 . 1 11 111 . 1 11 I I I 111 111 .111 111 .111 111 .111 111 1 11 I II . I II 1 /1 . 1 11 111 . 1 11 1 II 1 11 I II . I II 1 11 . 1 11 1 11 . 1 11 1 II .1 111 111 .111 111 .111 111 .111 111 1 11 I II . I II 1 11 . 1 11 111 . 1 11 I II 111 111 .111 111 .111 111 .111 111 .1 1 11 1 11 . I I I 1 11 . 1 11 111 . 1 11 1 I I 11 1 11 1 11 . 1 111 1 11 1 111 . 1 111 1 11 . 1 11 1 111 . 1 111 1 11 1 11 1 111 . 1 111 1 111 . 1 11 1 111 . 1 111 1 111 1 111 1 111 . 1 111 1 /11 . / 111 1 111 . 1 111 1 111 1 111 1 I11 . 1 I11 1 111 . 1 111 1111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . / 111 1 11/ . 1 111 1 111 1707466.000 - 3651 C-17 Table C-2. (cont). HI estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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 Hybrid/CIP TIME111 111 , 111 111 0111 111 0111 111 TIME111 111 , 111 111 0111 111 0111 111 TIME111 111 , 111 111 0111 111 1111 111 TIME111 111 , 111 111 0111 111 0111 / 11 TIME111 111 , 111 111 0111 1111 1111 111 TIME1 11 1 111 , 1 111 1 11 . 1 11 1 111 . 1 111 1 111 TIME1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 TIME1 111 1 111 , 1 111 1 111 . 1 111 1 11/ . 1 111 1 111 TIME1 11 / 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 TIME1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 TIME1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 TIME1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 TIME1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 TIME1 11 / 1 111 , 1 111 1 111 . 1 111 1 111 Eno 111 1 111 TIME1 11 / 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 Hybrid/Excavation Offsite TIME111 111 , 111 111 0111 111 .111 111 TIME1 11 I I I , I I I 1 11 . 1 11 111 . 1 11 1 11 TIME111 111 , 111 111 0111 111 .111 111 TIME1 11 I I I , I I I 1 11 . 1 11 111 . 1 11 1 11 TIME1 11 I II , I II 1 11 . 1 11 1 11 . 1 II 1 11 TIME111 111 , 111 111 0111 111 .11/ 111 TIME1 11 I I I , I I I 1 11 . 1 11 111 . 1 11 1 11 TIME111 111 , 111 111 .111 111 111/ 111 TIME1 11 I I I , 1 11 1 11 . 1 11 111 . 1 11 1 11 TIME 1 11 1 11 , 1 11 1 / 1 . 1 11 1 11 .TIME 1 11 1 11 TIME111 111 .111 111 .111 111 .111 111 111 111 , 1111 111 .111 111 .111 111 TIME 1 11 1 111 , 1 11/ 1 11 . 1 11 1 111 . 1 1/ 1 11 TIME1 11 1 111 , 1 111 1 11 . 1 11 1111 . 1 111 1 11 1 11 1 111 , 1 111 1 111 . 1 11 1 111 . 1 1/1 1 11 1707466.000 - 3651 C-18 Table C-2. (cont). HI estimates from DPM exposure due to trucking operations associated with closure of the Roxboro ash basins under combinations of CIP closure, excavation closure, and hybrid closure. Results are 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 Hybrid/Hybrid MINES1 11 1 11 , 1 11 1 11 . 1 11 1 11 . 1 111 1 11 M1111111 111 , 111 111 0111 1111 .1111 111 M1111 111 1 111 , 1 111 1 11 . 1 11 1 111 . 1 1/1 1 111 M11111 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 ENOS1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 ,1 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 MMMM1 111 1 111 , 1 111 1 111 . 1 111 1 11/ . 1 111 1 111 M11111 11 / 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 EVEN1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 EVEN1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 THIS1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 THEM1 111 1 111 , 1 111 1 111 . 1 111 1 111 Eno 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 1/1 1 111 Excavation Onsite/Excavation Onsite 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 M1111 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 M11111 111 1 111 , 1 111 1 111 . 1 11/ 1 11/ . 1 111 1 111 M11111 111 I I11 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 M11111 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 M11111 111 I I11 , 1 111 1 111 . 1 111 1 11/ . 1 111 1 111 M11111 111 I I11 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 M11111 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 M11111 111 I I11 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 EVEN1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 IRWIN1 111 I I11 , 1 111 1 111 . 1 111 1 1/1 . 1 111 1 111 EVEN1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 In 111 1 111 . 1 111 1 111 . 1 111 1 111 THIN1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1 111 1 111 , 1 111 1 111 . 1 111 1 111 . 1 111 1 111 1707466.000 - 3651 C-19 Appendix D Habitat Equivalency Analysis Habitat Equivalency Analysis Habitat equivalency analysis (HEA) was used to estimate changes in ecological service levels under different closure options for the Roxboro Plant ash basins. The extent of ecological 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 ecological 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 (2018a,b) 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 were based on information provided by Duke Energy (2018a,b) according to the assumptions below. For the 1707466.000 - 3651 D-1 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 pre -basin aerial photographs provided in the comprehensive site assessment (CSA; SynTerra 2015a) 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 unclassified open areas since not all currently measured habitat types (e.g., wetland) could be resolved from historical images. Historical open unclassified areas (i.e., not forest or open water habitat types) were estimated by assuming the current site -wide percentages of wetland (<1%) and open field (99%) 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: The historical stream habitat area was available only as linear spatial feature. To calculate the area of restored stream features as open water, I assumed a restored stream would have a width of 6 ft and an intermittent stream would have a width of 3ft. • Fill material for closure was assumed to be derived from offsite borrow pits. The area 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 Roxboro property. Evaluate Ecological Services NPP was used to standardize ecological 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 ecological services and is a useful currency for comparing habitats (Efroymson et al. 1707466.000 - 3651 D-2 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, mixed forested areas have the highest NPP; that is, per acre of forest, photosynthesis fixes more carbon/produces more energy for ecological 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 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 1707466.000 - 3651 D-3 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 ecological services derived from an acre over a year and uses as its metric a discounted service acre -year, or DSAY. Discounting is necessary because ecological 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 ecological services occurring far in the future to be considered on par with contemporary services. Thus, factors determining when 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 (2018a,b) 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 ecological services. The closure schedule estimated duration of each activity in months; however, since the HEA model calculates DSAYs on an annual 1707466.000 - 3651 D-4 basis, the activity durations were rounded up to 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 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 ecological service is provided by the end of the first construction year. • Ecological 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 ecological service is provided by the end of the first construction year. • Ecological 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, 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. 1707466.000 - 3651 D-5 — 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 ecological service. • The base year for discounting is 2019 in all scenarios. • A discount rate of 3% is applied in all scenarios. • The HEA is run for 150 years for all closure options. Calculate Discounted Ecological 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 areas. The results are discussed in the context of uncertainty in the net environmental benefit analysis (NEBA) in Appendix E. 1707466.000 - 3651 D-6 Appendix E Net Environmental Benefit Analysis 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 Roxboro 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 ecological 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 Roxboro ash basin is shown in Table E-1. 1707466.000 - 3651 E-1 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) No meaningful risk -- -- -- -- <5% (A) 5A 4A 3A 2A 1 A 5-19% (B) 5B 4B 3B 2B 1 B 20-39% (C) I 5C 4C 3C 2C 1 C 40-59% (D) I F"Mm_13D 2D 1 D 0 E 60-79% (E) - I 2E 1E 80-99% (F) 1 F 0 100-149% (G) 150-199% (H) 200-299% (1) 300-399% (J) 400-499% (K) >500% (L) 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% up to 100% impact, at intervals of 50% up to 200% impact, and at intervals of 100% above 200% impact based on best professional judgement and consistent with the risk -ranking approach used by Robberson (2006) for impacts below 100%. 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 1707466.000 - 3651 E-2 duration and time to recovery (e.g., 1-4 years, 5-9 years) from longer periods (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. 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 six (e.g., <1 year, 1-5 years, 6-10 years, 11-15 years, 16-20 years, >20 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 1707466.000 - 3651 E-3 differences in assumptions could affect relative risk ratings in the NEBA framework for attributes found to have 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. Noise and congestion from trucking traffic I used the number of trucks per day passings 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 ash, earthen fill, geosynthetic material, and other materials under the closure options 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.2 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 on trucking routes to estimate annualized truck percentage to apply to AADT to determine truck AADT (NCDOT 2015). The average annualized truck percentage for Person County is 9.5%. 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 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). 3 Vehicle classification is assigned based on number of axles, space between axles, weight of the first axle, and total weight of the vehicle. 1707466.000 - 3651 E-4 The anticipated transportation route for excavated ash and borrow material between the Roxboro Plant and the landfill at Duke Energy's Mayo Steam Electric Plant (Mayo Plant) is plotted in (Figure E-1). To best capture trucking related impacts to sensitive communities along this transportation corridor, I assumed a baseline truck passes per day of 52, which was computed based on the lowest AADT value on the identified transportation route (NCDOT Station ID 7201509 on Shilo Church Rd. reported 540 AADT in 2016) multiplied by the Person County average percent of truck AADT (9.5%; NCDOT 2015).4 LEGEND Annual average daily traffic (Baseline consideration) ■ 500 - 999 1,00 - 1,999 ■ 2,000 - 3,499 ❑ 3,500 - 5,499 Annual average daily traffic • 80 - 199 • 200 - 499 • 500 - 999 • 1,000 - 1,999 • 2,000 - 3,499 • 3,500 - 5,499 • 5,500 - 8,499 • 8,500 - 12,499 12,500 - 17,499 17,500 - 31,000 0 2.5 5 Miles 0 3 6 Kilometers Figure E-1. NCDOT annual average daily traffic (AADT) measurement stations near Roxboro. 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 52 trucks per day was evaluated by calculating relative risk ratings for a range of baseline truck traffic levels, 4 AADT data are not available for every road or every location along a road. It is possible during closure of the Roxboro 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 available AADT estimate from the most likely transportation corridor between Roxboro and Mayo, my analyses have considered sensitive communities that would be more affected by traffic noise and congestion from ash basin closure trucking. 1707466.000 - 3651 E-5 based on the minimum and maximum AADT values for any NCDOT station within a 50-mile radius of the Roxboro ash basins, using AADT from the most recent year that data are available for a particular station and assuming 9.5% 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 3 to 18,541 truck passes per day. 1707466.000 - 3651 E-6 104.0 103.0 10z-0 1070 1 00.0 104.0 103.0 102.0 1010 1 oa.0 co CL E 0 1040 103.0 1020 101.0 100.0 104.0 103.0 102.0 10to 1060 0 100 200 300 400 500 0 100 200 300 400 500 0 100 200 300 400 500 Assumed Baseline Truck Passes Per Day Risk Rating A• B • C • D• E• F •G •H •I J •K *L Figure E-2. Sensitivity of NEBA relative risk rating for noise and congestion impacts from trucking operations. The vertical line indicates the assumed baseline 52 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 52, excavation closure of both basins to onsite landfills (Excavation Onsite/Excavation Onsite) produces the lowest percent impact (65%) and falls into the E (60-79%) risk rating category. All other closure options fall into relative risk rating 1707466.000 - 3651 E-7 categories of G or greater (>100%) for traffic -induced noise and congestion during closure of the Roxboro ash basins (Figure E-2). The highest risk rating results from excavation closure of both basins to an offsite landfill (Excavation Offsite/Excavation Offsite) at 770%, based on 400 additional average daily truck passes due to closure activities. Lower risk ratings would result from a higher baseline truck traffic assumption. The most sensitive option to increases in baseline truck traffic volume is CIP closure of both basins (CIP/CIP), where increasing baseline truck volume by 1 truck pass per day (i.e., from 52 to 53 truck passes per day) lowers the risk rating from H to G. The onsite excavation option (Excavation Onsite/Excavation Onsite) is also sensitive to an increase in baseline truck traffic volume; the risk rating drops from E to D if the baseline increases by 4 trucks per day and rises to F if the baseline decreases by 11 trucks per day. Excavation Offsite/Hybrid, Hybrid/CIP, and Hybrid/Hybrid share the same level of sensitivity, in that each of their risk ratings rises if the baseline decreases by 6 or more trucks per day, while their risk ratings all drop if the baseline increases by approximatelyl3-18 trucks per day. CIP/Hybrid and Excavation Offsite/CIP share another level of sensitivity, in that the risk ratings drop if the baseline increases by 6 or 9 trucks (respectively), while a higher risk rating results from a decrease in the baseline by greater than 10 trucks per day. CIP/Excavation Offsite, Hybrid/Excavation Offsite, and Excavation Offsite/Excavation Offsite are less sensitive to the baseline number of trucks, as the risk ratings only change if the baseline number of trucks changes by more than 10 trucks per day. The sensitivity thresholds for all closure options can be identified by examining the proximity of the vertical line in Figure E-2 (representing the assumed baseline trucking volume of 52 truck passes per day) to the changes in line color representing changes in risk ratings. 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.5 1 chose a baseline of 33.5 million annual truck road miles based on the reported total vehicle miles traveled in Person County, North Carolina (NCDMV 2017), multiplied by the county average 9.5% contribution of trucks to total AADT (NCDOT 2015). 5 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. 1707466.000 - 3651 E-8 The sensitivity of the NEBA relative risk ratings to the baseline assumption of 33.5 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 impacts for the all closure options, along with the resulting relative risk ratings across the range of truck miles per year. 1707466.000 - 3651 E-9 10ts 1070 100.5 100.0 1 V-5 1 D-1-0 1 o-1.5 10,.5 . 101.0 1 00.5 100.0. 10-0 5 O. 1 Q-1.5 . 0 101.5 101.0 100.5 100_0 10-0.5 1 o-1.0 101-5 101 ° 100.s 100.0 10-0.5 10-,.0 1 O-, _5 EXC OFF/CIP EXC OFF/EXC OFF 0 100 200 300 400 500 Assumed Baseline Million Truck Miles Per Year Risk Rating A B C Figure E-3. Sensitivity of NEBA relative risk rating for traffic accidents due to trucking activities. The vertical line indicates the assumed baseline 33.5 million truck miles per year. The y-axis is plotted on a log10 scale to improve visualization. Using the 33.5-million-truck-miles baseline assumption, all but one closure option has a relative risk rating of A (<5%). Excavation closure of both the EAB and WAB to an offsite landfill (Excavation Offsite/Excavation Offsite) has a B risk rating at 5.6% impact. Increasing the baseline trucking 11% (from 33.5 million annual truck miles to 37.4 million truck miles) would 1707466.000 - 3651 E-10 reduce the relative risk rating of the Excavation Offsite/Excavation Offsite option to an A. Decreasing the baseline trucking volume to the statewide minimum of 6.2 million annual truck miles (Hyde County) would increase the risk rating to B (5-19% impact) for CIP/CIP, Hybrid/CIP, and Hybrid/Hybrid closure options. The Excavation Offsite/CIP, CIP/Excavation Offsite, Hybrid/Excavation Offsite, and Excavation Offsite/Excavation Offsite options would have a C risk rating (20-39% impact). These sensitivity thresholds for all closure options can be identified by examining the proximity of the vertical line in Figure E-3 (representing the assumed baseline trucking miles) to the changes in line color representing risk ratings. Habitat Equivalency Analysis Uncertainty in the habitat equivalency analysis (HEA) that examined disruption of ecological 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. 2. Assuming the open water habitats of the ash ponds provide ecological services at 40% of wooded areas instead of 10%. 3. Assuming open field habitats provide ecological services at 20% of wooded areas instead of 40%. 4. Assuming borrow areas under the CIP option are restored to open fields, 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). 1707466.000 - 3651 E-1 1 Table E-2. Change in DSAYs from base models for key HEA assumptions Closure Option (EAB/WAB) 100-year Ash basin Borrow Open Field modelb water 40%` becomes 20%e field CIP/CIP -3 -940 -564 60 CIP/Excavation Offsite -21 -915 -395 -94 CIP/Hybrid -77 -940 -630 37 Excavation Offsite/CIP -8 -938 -393 -37 Excavation Offsite/Excavation Offsite -26 -913 -225 -190 Excavation Offsite/Hybrid -82 -938 -460 -60 Hybrid/CIP -5 -938 -420 60 Hybrid/Excavation Offsite -23 -913 -251 -94 Hybrid/Hybrid -79 -938 -486 37 Excavation Onsite/Excavation Onsite -134 -913 -432 -264 'Base models were run for 150 years with ash basin open water NPP services at 10%, borrow fields were assumed to become forest (CIP closure) or a combination of forest and grass cap (hybrid and excavation closure), and open field NPP services at 40%. b Base models except the HEA was run for 100 years. Base models except ash basin open water NPP service at 40%. d Base models except forested borrow pit areas were assumed to become open field 'Base models except open field NPP services decreased to 20%. Running HEAs for 100 years decreased net DSAYs for all closure options, with a greater impact on the Excavation Onsite/Excavation Onsite option due to the longer duration of the construction period and the reduced time for recovery of the habitat under a 100-year model. Increasing the ash basin open water service level to 40% resulted in large but comparable net decreases in DSAYs for all options. Assuming borrow areas would be returned to open field resulted in a moderate decrease in net DSAYs for all options. Decreasing open field services to 20% reduced net DSAYs in all options that include excavation in either basin, with the greatest impact to excavation closure of both basins with onsite landfilling (Excavation Onsite/Excavation Onsite) due to the long construction period and the delay in reaching open field services in the restored ash basin footprint. 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, since the same level of service change is applied over the same area (44.7 combined acres of both basins) 1707466.000 - 3651 E-12 in all closure options. The difference in DSAY losses among options is due to differences in the year construction starts and hence existing services are lost. Assuming open field services at 20% has a larger effect on the excavation options since those options restore a greater open field acreage than the options including grass cap (CIP or landfill covers). Changing the forest areas of borrow habitat to open field habitat after borrow is complete affects all options similarly since the amount of area assumed to be forested only varies 2-3 fold among options. However, since the directionality of net NPP services provided by the closure options does not change under this sensitivity analysis (i.e., all options that include hybrid closure of the WAB produce positive NPP services, with hybrid closure of both basins producing the largest net benefit in 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 how DSAYs change with assumptions between the various closure options and the result that hybrid closure of both basins always results in the greatest net DSAYs under any sensitivity analysis support 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, unless otherwise specified by Duke Energy (2018a,b). • The density of ash was assumed to be 1.2 ash tons/CY. • Borrow pit acreage required to supply earthen fill and cover material (including topsoil) 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. 1707466.000 - 3651 E-13 • 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. • Cover, fill, and topsoil earthen material were assumed to be from sources 15 miles away (one way) and would travel along the designated transportation route between the Roxboro and Mayo Plants. • 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. • For offsite excavation of both the EAB and WAB (Excavation Offsite/Excavation Offsite), all ash is assumed to be transported to the landfill at Mayo. 1707466.000 - 3651 E-1 4