2016-0418_Duke_App_G_Roxboro_F_20160418

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www.haleyaldrich.com
EVALUATION OF WATER SUPPLY WELLS IN THE VICINITY OF DUKE
ENERGY COAL ASH BASINS IN NORTH CAROLINA
APPENDIX G - ROXBORO STEAM ELECTRIC PLANT
by Haley & Aldrich, Inc.
Boston, Massachusetts
for Duke Energy
File No. 43239
April 2016

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Table of Contents
Page
List of Tables
List of Figures
iii
List of Attachments
iv
List of Acronyms
v
G. Roxboro
1
G.1 INTRODUCTION
1
G.1.1
Facility Location and Description
1
G.1.1.1 Facility Setting
1
G.1.1.2 Past and Present Operations
2
G.1.1.3 Facility Geological/Hydrogeological Setting
3
G.1.2
Current CAMA Status
3
G.1.2.1 Receptor Survey, September 2014, updated November 2014
4
G.1.2.2 Comprehensive Site Assessment, Round 1 Sampling Event, March —
September 2015
4
G.1.2.3 Round 2 Sampling Event, September through October 2015
4
G.1.2.4 Corrective Action Plan — Part 1, 1 December 2015
5
G.1.2.5 Round 3 (December 2015) and Round 4 (January 2016) Background
Well
Sampling
5
G.1.2.6 Corrective Action Plan — Part 2, 2 March 2016
5
G.1.3
Investigation Results
6
G.1.4
Selected Remedial Alternative and Recommended Interim Activities
7
G.1.5
Risk Classification Process
7
G.1.6
Purpose and Objectives
11
G.2 WATER SUPPLY WELL DATA EVALUATION
11
G.2.1
Data Sources
12
G.2.2
Screening Levels
12
G.2.3
Results
12
G.3 STATISTICAL
EVALUATION OF BACKGROUND
13
G.3.1
Initial Data Evaluation
14
G.3.1.1 Regional Background Water Supply Well Data
14
G.3.1.2 Facility Background Monitoring Well Data
14
G.3.2
Raw Data Evaluation
15
G.3.2.1 Regional Background Water Supply Well Data
15
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G.3.2.2 Facility Background Monitoring Well Data
G.3.3
Testing of Statistical Assumptions
G.3.3.1 Regional Background Water Supply Well Data
G.3.3.2 Facility Background Monitoring Well Data
G.3.4
BTV Estimates
G.3.5
Comparison of Water Supply Well Data to the Regional BTVs
G.4 GROUNDWATER FLOW EVALUATION
G.4.1
Introduction
G.4.2
Site Geology
G.4.3
Site Hydrogeology
G.4.3.1 Site Conceptual Model
G.4.3.2 Groundwater Flow Direction
G.4.3.3 Groundwater Seepage Velocities
G.4.3.4 Constituents Associated with CCR
G.4.3.5 Extent of Boron Exceedances in Groundwater
G.4.3.6 Bedrock Flow and Depth of Water Supply Wells
G.4.3.7 Groundwater Mounding
G.4.3.8 Summary
G.4.4
Water Supply Well Capture Zone Analysis
G.4.4.1 Methodology
G.4.4.2 Results
G.4.5
Summary and Conclusions
G.5 GROUNDWATER CHARACTERISTICS EVALUATION
G.5.1
Evaluation Approach
G.5.2
CCR-Related Constituents Screening for Signature Development
G.5.3
Data Analysis Methods
G.5.3.1 Data Sources
G.5.3.2 Data Aggregation
G.5.3.3 Box Plot
G.5.3.4 Correlation Plot
G.5.3.5 Piper Plot
G.5.4
Evaluation Results
G.5.4.1 Box Plot Comparison
G.5.4.2 Correlation Plot Evaluation
G.5.4.3 Piper Plot
G.5.5
Conclusions
G.6 SUMMARY
G.7 REFERENCES
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Appendix G — Roxboro
List of Tables
Table No.
Title
G2-1
Comparison of NCDEQ Water Supply Well Data to 2L Screening Levels
G2-2
Comparison of NCDEQ Water Supply Well Data to MCL Screening Levels
G2-3
Comparison of NCDEQ Water Supply Well Data to DHHS Screening Levels
G2-4
Comparison of NCDEQ Water Supply Well Data to RSL Screening Levels
G2-5
Comparison of Duke Energy Background Well Data to 2L Screening Levels
G2-6
Comparison of Duke Energy Background Well Data to MCL Screening Levels
G2-7
Comparison of Duke Energy Background Well Data to DHHS Screening Levels
G2-8
Comparison of Duke Energy Background Well Data to RSL Screening Levels
G2-9
Do Not Drink Letter Summary
G3-1
Duke Energy Background Water Supply Well Data
G3-2
Facility Specific Background Data for Bedrock and Deep Monitoring Wells
G3-3
Background Data Statistical Evaluation
G3-4
Comparison of NCDEQ Water Supply Well Sampling Data to Background
Threshold Values
G3-5
Comparison of NCDEQ Water Supply Well Sampling Data to Facility Specific
Background Threshold Values
List of Figures
Figure No.
Title
G1-1
Location Map
G1-2
Key Features
G1-3
Location of Water Supply Wells and Facility Groundwater Conditions
G3-1
Facility Background Wells
G4-1
Site Conceptual Model — Plan View
G4-2
Boron Isoconcentration Map
G4-3
Cross -Section Location Map
G4-4
Conceptual Cross -Section A -A'
G4-5
Conceptual Cross -Section B-B'
G4-6
Conceptual Cross -Section C-C'
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Appendix G — Roxboro
G5-1
Pourbaix Diagrams for Manganese with Measured Eh and pH from Site
Monitoring Wells
G5-2
Example Box Plot and Piper Plot
G5-3
Box Plot Comparison for Major Coal Ash Constituents
G5-4
Box Plot Comparison for Barium and Cobalt
G5-5
Box Plot Comparison for Dissolved Oxygen, Iron, and Manganese
G5-6
Bedrock Groundwater Wells and Direction of Groundwater Flow
G5-7
Correlation Plot for Boron and Sulfate
G5-8
Correlation Plot for Boron and Dissolved Oxygen
G5-9
Sampled Water Supply Wells
G5-10
Piper Plot Evaluation - Ash Basin Porewater and Facility Downgradient Bedrock
Wells
G5-11
Piper Plot Evaluation - Water Supply and Upgradient and Side Gradient Facility
Bedrock Wells
G5-12
Piper Plot Comparison - Water Supply Wells and Regional Survey by USGS
G5-13
Piper Plot Evaluation - Water Supply, Facility Bedrock, and Ash Basin Porewater
Wells
List of Attachments
Attachment Title
G-1 Histograms and Probability Plots for Selected Constituents
G-2 Results of Statistical Computations
G-3 Method Computation Details
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Appendix G — Roxboro
List of Acronyms
213 Standards North Carolina Surface Water Quality Standards as specified in
T15 NCAC 026.0211 and .0216
2L Standards North Carolina Groundwater Quality Standards as specified in Title 15A NCAC.0202L
amsl Above mean sea level
BR Bedrock
BTV Background Threshold Value
CAMA North Carolina Coal Ash Management Act of 2014
CAP Corrective Action Plan
CC Confidence Coefficient
CFR Code of Federal Regulations
CCR Coal Combustion Residuals
CSA Comprehensive Site Assessment
D Deep
DWR Division of Water Resources
EPRI Electric Power Research Institute
FGD Flue Gas Desulfurization
GOF Goodness -Of -Fit
HSL Health Screening Levels
IID Independent, Identically Distributed
IMAC Interim Maximum Allowable Concentrations
IQR Interquartile Range
KM Kaplan -Meier
µg/L Micrograms per Liter
MCL Maximum Contaminant Level
MDL Method Detection Limit
MNA Monitored Natural Attenuation
NCAC North Carolina Administrative Code
NCDEQ North Carolina Department of Environmental Quality
ND Non -Detect
NPDES National Pollutant Discharge Elimination System
NCDHHS North Carolina Department of Health and Human Services
PPBC Proposed Provisional Background Concentration
ROS Robust Regression on Order Statistics
RSL Risk -Based Screening Level
S Shallow
SCM Site Conceptual Model
SMCL Secondary Maximum Contaminant Level
TDS Total Dissolved Solids
TZ Transition Zone
UPL95 95% Upper Prediction Limit
USEPA U.S. Environmental Protection Agency
USGS U.S. Geological Survey
UTL95-95 Upper Tolerance Limit with 95% confidence and 95% coverage
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Appendix G — Roxboro
G. Roxboro
The contents of this document supplements previous work completed by Duke Energy to meet the
requirements of the North Carolina Coal Ash Management Act of 2014 (CAMA) for the Roxboro Steam
Electric Plant (Roxboro, or site), a coal-fired generating station. The purpose of this document is to
provide the North Carolina Department of Environmental Quality (NCDEQ) with the additional
information it needs to develop a final risk classification for the Roxboro ash basins under the CAMA
requirements. A technical weight of evidence approach has been used to evaluate the available data for
the Roxboro site, and the evaluation demonstrates that groundwater utilized by local water supply wells
near the Roxboro ash basins is not impacted by coal ash sources. These results indicate that a Low
classification for the Roxboro Steam Electric Plant under the CAMA is warranted.
G.1 INTRODUCTION
The first section of this document provides a description of the facility location, setting, past and present
operations, a summary of activities conducted to meet the CAMA requirements, a summary of the on -
site and background data evaluation findings and recommendations of the following reports:
• Comprehensive Site Assessment (CSA; SynTerra, 2015a);
• Corrective Action Plan Part 1 (CAP-1; SynTerra, 2015b); and
• Corrective Action Plan Part 2 (CAP-2; SynTerra, 2016).
A review of the risk classification process and the status of that process are also provided.
This report provides technical evaluations in four important assessment areas: 1) an evaluation of the
private and public water supply well data collected by the NCDEQ with respect to groundwater
standards and screening levels; 2) additional statistical analysis of regional background groundwater
data, and facility -specific background groundwater data; 3) a more comprehensive evaluation of
groundwater flow with respect to local water supply wells, including a water supply well capture zone
analysis; and 4) a detailed comparison of facility -specific coal ash groundwater chemistry, background
groundwater chemistry (both regional and facility -specific), and water supply well chemistry.
G.1.1 Facility Location and Description
Duke Energy owns and operates Roxboro which is located in Person County near Semora, North
Carolina, as shown on Figure G1-1.
G.1.1.1 Facility Setting
Roxboro is situated on a 6,095-acre parcel of land located on the east bank of Hyco Reservoir, a lake
formed from the impoundment of the Hyco River, as shown on Figure G1-2. The area surrounding
Roxboro generally consists of wooded land, and the Hyco Reservoir. Properties located within a 0.5-mile
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Appendix G — Roxboro
radius of the Roxboro ash basin compliance boundary (see below) generally consist of wooded land
transected by transmission lines to the east, south, and west, and Hyco Reservoir to the west and north.
Per the North Carolina Administrative Code (15A NCAC 02L.0102), "Compliance Boundary" means a
boundary around a disposal system at and beyond which groundwater quality standards may not be
exceeded and only applies to facilities that have received a permit issued under the authority of North
Carolina General Statute (G.S.) 143-215.1 or G.S. 130A. The ash basin system compliance boundary is
defined in accordance with 15A NCAC 02L.0107(a) as being established at either 500 feet from the waste
boundary or at the property boundary, whichever is closer to the waste.
Three public water supply wells and 58 private water supply wells were located within a 0.5-mile radius
of the ash basin system compliance boundary (Figure G1-3). None of the wells were found to be located
downgradient of the ash basins. No wellhead protection areas were identified within a 1,500-foot-mile
radius of the ash basin system compliance boundary. Several surface water bodies were identified
within a 0.5-mile radius of the ash basin compliance boundary.
G.1.1.2 Past and Present Operations
Roxboro began operations in 1966 as a coal-fired electrical generating station and additional units were
added in 1968, 1973, and 1980. The site currently operates four coal-fired units. Roxboro has an
electric generating capacity of 2,422 megawatts.
The major ash -related structures at Roxboro include the active west ash basin, the semi -active east ash
basin, the unlined landfill, the lined landfill, the gypsum pad which contains a base of coal combustion
residual (CCR) structural fill, and the unnamed eastern extension impoundment. These key features are
shown on Figure G1-2.
The semi -active east ash basin was constructed in 1966 and is located southeast of the plant. The active
west ash basin was constructed in 1973 and is located south of the plant. The ash basins are impounded
by earthen dams. The approximate size of the combined ash basins is 495 acres. CCRs were deposited
in the ash basins by hydraulic sluicing operations until the plant was modified for dry fly ash handling
operations in the 1980s. Fly ash continues to be sluiced when performing maintenance on the dry
handling system.
An unlined landfill was constructed on the east ash basin in the late 1980s for the placement of dry fly
ash, and a lined landfill was subsequently constructed over the unlined landfill in 2004. Surface water
runoff from the east ash basin and the lined landfill are routed into the west ash basin to allow settling.
Discharges from the ash basins are permitted by the NCDEQ Division of Water Resources (DWR) under
the National Pollution Discharge Elimination System (NPDES) Permit NC0003425.
The gypsum pad located adjacent to the east ash basin contains a base of CCR materials, and CCR
materials may also have been deposited in the unnamed eastern extension impoundment to the east
ash basin.
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Appendix G — Roxboro
G.1.1.3 Facility Geological/Hydrogeological Setting
Roxboro is located in the geologic region known as the Piedmont Province which stretches from New
Jersey to central Alabama. The widest portion of the Piedmont is located in North Carolina. Elevations
near Roxboro range between 410 feet above mean sea level (amsl) during full pool at Hyco Reservoir to
570 feet amsl near the Dunnaway Road and McGhees Mill Road intersection southeast of the site.
Topography generally slopes from the natural undisturbed areas along the perimeter of the site inward
toward the active areas of the site. Several drainage features trend southeast to northwest across the
site to the Hyco Reservoir. The elevation of Hyco Reservoir and drainage canals at the site is
approximately 410 feet amsl. Surface elevations of the east ash basin and landfill range from 470 to
530 feet amsl. Surface elevations in the west ash basin range from approximately 450 to 480 feet amsl.
Based on the CSA investigation, the groundwater system in the natural materials (alluvium, soil,
soil/weathered bedrock, and bedrock) at Roxboro is consistent with the Piedmont regolith-fractured
rock system and is an unconfined, connected system of flow layers. In general, groundwater within the
shallow alluvium/soil, and deep soil/weathered bedrock layers (S, and D or transition zone [TZ] wells),
and bedrock layer (BR wells) flows to the north/northwest at the site. The presence of groundwater is
inconsistent in the shallow zone, but is more common in the transition zone.
More detail on the site hydrogeology is provided in Section G.4.
G.1.2 Current CAMA Status
The CAMA is primarily administered by the NCDEQ. The CAMA requires the NCDEQ to, as soon as
practicable, but no later than 31 December 2015, prioritize for the purpose of closure and remediation
CCR surface impoundments, including active and retired sites, based on these sites' risks to public
health, safety, and welfare, the environment, and natural resources.
To this end, CAMA includes the following requirements for coal -fueled facilities that manage coal ash or
CCR, the material that results from the combustion of coal for the creation of electric energy:
• An assessment of groundwater at CCR surface impoundments, and
• Corrective action for the restoration of groundwater quality at CCR surface impoundments.
Duke Energy owns and operates, or has operated, 14 coal -fueled electric generating facilities in the state
of North Carolina. Per the CAMA, the investigation reporting milestones for each facility include the
following:
• Groundwater Assessment Work Plan;
• Groundwater Assessment Report, referred to as a Comprehensive Site Assessment (CSA); and
• Corrective Action Plan (CAP), Note: As agreed with NCDEQ, the CAP reports were prepared in
two parts: CAP-1 and CAP-2.
Duke Energy has submitted the Groundwater Assessment Work Plans, CSAs, and CAP reports as required
by the CAMA schedule. The CSA reports were submitted for all facilities by 2 September 2015. The
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Appendix G — Roxboro
CAP-1 reports were submitted for all facilities by 8 December 2015. CAP-2 reports were submitted by
7 March 2016. The CAP-2 reports include a site -specific human health and ecological risk assessment
that will be used to inform the remedial decision making for each facility.
The CAMA also requires a survey of drinking water supply wells and replacement of water supplies if
NCDEQ determines a well is contaminated by CCR-derived constituents. NCDEQ has yet to make such a
determination under the CAMA. Duke Energy provided the NCDEQ with an evaluation of the NCDEQ-
sampled water supply well (private well) data in December 2015 (Haley & Aldrich, 2015). This report
serves to augment the evaluations provided in the December 2015 report.
A brief summary of the objectives and approach for the CSA, CAP-1, and CAP-2 is provided below.
G.1.2.1 Receptor Survey, September 2014, updated November 2014
The receptor survey was conducted by Duke Energy for the purpose of identifying drinking water wells
within a 0.5-mile (2,640-foot) radius of the Roxboro ash basin system compliance boundary.
Supplemental receptor survey information was obtained from responses to water supply well survey
questionnaires mailed to property owners within the required distance requesting information on the
presence of water supply wells, well details, and well usage. Figure G1-3 shows the water supply wells
within this 0.5-mile radius.
G.1.2.2 Comprehensive Site Assessment, Round 1 Sampling Event, March — September 2015
The purpose of the Roxboro CSA was to collect information necessary to characterize the extent of
impacts resulting from historical production and storage of coal ash, evaluate the chemical and physical
characteristics of CCR constituents, investigate the geology and hydrogeology of the site including
factors relating to contaminant transport, and examine risk to potential receptors and exposure
pathways. The following assessment activities were performed as part of the CSA:
• Collection of groundwater sampled from 51 groundwater monitoring wells.
• Collection of seep, surface water, and sediment samples.
• Collection and analysis of chemical, physical, and hydrogeological parameters of subsurface
materials encountered within and beyond the waste and Compliance Boundary.
• Evaluation of laboratory analytical data to support the development of the site conceptual
model (SCM).
• Update of the receptor survey previously completed in September 2014
(updated November 2014) (SynTerra, 2014a, 2014b).
• Completion of a screening -level human health and ecological risk assessment.
G.1.2.3 Round 2 Sampling Event, September through October 2015
A total of 53 groundwater monitoring wells were sampled during the Round 2 event. Samples were
analyzed for total and dissolved CCR constituents.
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Appendix G — Roxboro
G.1.2.4 Corrective Action Plan — Part 1, 1 December 2015
The purpose of the CAP-1 report was to summarize CSA findings, evaluate background conditions by
calculating Proposed Provisional Background Concentrations (PPBCs) for soil and groundwater, evaluate
exceedances per sample medium with regard to PPBCs, refine the SCM, and present the results of the
groundwater flow and contaminant fate and transport model, and the groundwater to surface water
interaction model.
The Roxboro CAP-1 (SynTerra, 2015b) presented PPBCs for groundwater, and soil. The PPBCs and other
applicable regulatory standards were compared to the current site data from each of these media to
determine the CCR constituents to be addressed in a potential corrective action to be proposed in
CAP-2. This evaluation is updated in the subsequent CAP-2 report, as additional data were collected and
evaluated against regulatory standards for each medium.
Groundwater modeling of the fate and transport of CCR constituents identified to exceed standards was
conducted to inform the corrective action plan. Three modeling scenarios were completed to assess the
impact of potential corrective actions as follows: existing conditions were modeled into the future over
a 30-year period; the effect of capping the CCR source areas to reduce rainfall infiltration was modeled
over a 30-year timeframe; and the effect of excavating CCR materials was modeled over a 30-year
timeframe.
Recommendations for future work were provided at the end of the CAP-1 report as follows: conduct an
additional risk assessment evaluation, evaluate the potential remedial alternatives, and present the
recommended remedial approach in CAP-2.
G.1.2.5 Round 3 (December 2015) and Round 4 (January 2016) Background Well Sampling
In response to an NCDEQ request, Duke Energy collected two rounds of groundwater samples from
background wells. Facility background wells within the compliance boundary were identified and based
on the SCM during preparation of the CSA Work Plan.
See Section G.3 for a statistical evaluation of background concentrations.
G.1.2.6 Corrective Action Plan — Part Z 2 March 2016
The purpose of the CAP-2 report is to provide the following:
• A description of exceedances of groundwater quality standards, surface water quality standards,
and sample results greater than the Interim Maximum Allowable Concentrations (IMAC) and
North Carolina Department of Health and Human Services (NCDHHS) health screening levels
(HSL);
• Present Round 3 of background sampling results;
• A refined SCM;
• Refined groundwater flow and fate and transport model results;
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• Site geochemical model results;
• Findings of the human health and ecological risk assessment;
• Evaluation of methods for achieving groundwater quality restoration;
• Conceptual plan(s) for recommended proposed corrective action(s);
• A schedule for implementation of the proposed corrective action(s); and
• A plan for monitoring and reporting of the effectiveness of the proposed corrective action(s).
Groundwater data collected during the four sampling rounds were compared to the following standards:
• North Carolina Groundwater Quality Standards as specified in Title 15A NCAC.0202L (21-
Standards);
• IMAC;
• North Carolina Surface Water Quality Standards as specified in T15 NCAC 0213.0211 and.0216
(amended effective January 2015) (213 Standards); and/or
• Site -specific PPBCs for groundwater at Roxboro.
G.1.3 Investigation Results
Based on the CSA, CAP-1, and CAP-2 results, general observations regarding the spatial distribution of
constituents in groundwater at Roxboro are depicted in Figure G1-3 and are described as follows:
• Impacts from CCR-constituents in groundwater are spatially limited to areas beneath the ash
basin, beneath the gypsum pad, and in limited areas immediately downgradient of the east and
west ash basins within the compliance boundary.
• Groundwater impacts are present in the shallow soil/alluvium, deep soil/weathered bedrock,
and the bedrock flow layers at the site.
• Surface water impacts were identified in water bodies within the east ash basin and in surface
water features west of the ash basin areas between the site and Hyco Reservoir.
• Regional groundwater flow direction is generally to the west/northwest toward the Hyco
Reservoir.
Constituents identified to exceed the applicable state and federal regulatory standards are listed by
location below:
Groundwater: boron, chloride, copper, iron, lead, manganese, selenium, sulfate, total dissolved
solids (TDS), and vanadium. Note that iron, selenium, sulfate, TDS, and vanadium were also
detected above their groundwater quality standard or criteria in site background groundwater.
Further sampling and analyses are necessary to determine if constituent exceedances are the
result of source -related impacts or naturally occurring conditions.
• Sediment: barium, copper, manganese, and selenium.
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• Seep and surface water: aluminum, boron, cobalt, manganese, and vanadium.
• Soil: aluminum, arsenic, cobalt, iron, manganese, nickel, selenium, thallium, and vanadium.
Boron, pH, sulfate, and TDS, all of which exceeded their 2L Standards and PPCBs either beneath or
downgradient of the source areas, are considered to be detection monitoring constituents in 40 CFR 257
Appendix III of the U.S. Environmental Protection Agency (USEPA) Hazardous and Solid Waste
Management System; Disposal of Coal Combustion Residuals from Electric Utilities (CCR Rule) (USEPA,
2015a). The USEPA detection monitoring constituents are potential indicators of groundwater
contamination from CCR as these constituents are associated with CCR and move with groundwater
flow unlike other constituents whose movement is impeded by chemical or physical interactions with
soil and weathered rock.
G.1.4 Selected Remedial Alternative and Recommended Interim Activities
The recommended remedial alternative selected for Roxboro is the combination of remediation
technologies: 1) capping the ash basin; 2) potential ash removal/excavation from the unnamed eastern
extension impoundment; and 3) monitored natural attenuation (MNA). Groundwater modeling showed
that the construction of an engineered cap to reduce infiltration would result in the retreat of the
constituent plume and a reduction in constituent concentrations downgradient of the ash basins.
Geochemical modeling demonstrated that CCR constituents are removed from groundwater through a
combination of sorption, chemical precipitation, and dilution by surface water and fresh groundwater
infiltration. A MNA program including collection and evaluation of groundwater data would be
implemented until remedial objectives are reached.
Additional groundwater monitoring well installation, along with additional sediment and surface water
sampling was recommended for implementation in 2016. The final closure option may be modified
based on the final risk classification proposed by the NCDEQ.
G.1.5 Risk Classification Process
Duke is required by the CAMA to close the Roxboro ash basin system no later than 1 August 2029 or as
otherwise dictated by NCDEQ risk ranking classification. On 31 January 2016, NCDEQ released draft
proposed risk classifications for Duke Energy's coal ash impoundments in North Carolina (NCDEQ, 2016).
The proposed risk classifications for the Roxboro ash basins were as follows: low for the west ash basin,
low to intermediate for the east ash basin, and intermediate for the unnamed eastern extension
impoundment. Risk classifications were based upon potential risk to public health and the environment.
A public meeting was held by NCDEQ regarding the proposed risk classification for the Roxboro ash
basins. NCDEQ will release the final risk classifications after review of public comments.
According to the NCDEQ document "Coal Combustion Residual Impoundment Risk
Classifications, January 2016," (NCDEQ, 2016), the west ash basin at Roxboro is ranked "low," while the
east ash basin is ranked "low to intermediate," and the unnamed eastern extension impoundment is
ranked "intermediate." The following are the classification factors as provided in the NCDEQ document.
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Appendix G — Roxboro
Groundwater Key Factor:
If either it is determined that no receptor is impacted by the coal ash impoundments or
alternate water is made available to all residents whose wells are being impacted by coal
ash impoundments, the overall groundwater risk would be low. Based on the information
received to date, there appears to be no downgradient receptors located 1,500 feet
downgradient of the impoundment compliance boundary. The following data gaps related
to groundwater uncertainty include:
- Additional areas adjacent to the current impoundment may contain CCR and would
therefore require additional assessment.
- Incomplete capture zone modeling in fractured bedrock for up -gradient and side -
gradient supply wells in the immediate vicinity of the impoundment.
- Incomplete geochemical modeling.
- Incomplete background concentration determination.
Groundwater Key Factor. If either it is determined that no receptor is impacted by the coal
ash impoundments or alternate water is made available to all residents whose wells are
being impacted by coal ash impoundments, the overall groundwater risk would be low.
Based on the information received to date, there appears to be no downgradient receptors
located 1,500 feet downgradient of the impoundment compliance boundary. The following
data gaps related to groundwater uncertainty include:
- This impoundment was just recently identified by Duke Energy and assessment is
currently underway.
- The location of the impoundment is in close proximity to potential receptors.
Based on the data provided in CSA Report and results of the groundwater modeling results
presented in the CAP Report, the number of down -gradient receptors (well users) 1,500 feet
from the compliance boundary that are potentially or currently known to be exposed to
impacted groundwater from source(s) or migration pathways related to the CCR
impoundments:
- East Ash Pond. LOW RISK. There are no reported supply wells within 1,500 feet
downgradient of the impoundment compliance boundary.
- West Ash Pond. LOW RISK. There are no reported supply wells within 1,500 feet
downgradient of the impoundment compliance boundary.
- Unnamed Eastern Extension Impoundment. LOW RISK. There are no reported
supply wells within 1,500 feet downgradient of the impoundment compliance
boundary.
• Exceedance of 2L Standard or IMAC at or Beyond the Established CCR Impoundment
Compliance Boundary:
- East Ash Pond. HIGH RISK. manganese and vanadium were detected beyond the
compliance boundary in MW-16BR greater than the 2L Standards or IMAC. It may
be determined at a later time that this well is located up -gradient of the
impoundment and the presence of constituents may be due to naturally occurring
geochemistry. Monitoring wells at or beyond the compliance boundary on the
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Appendix G — Roxboro
expected down -gradient side for this ash pond are not presently installed. Optional
install locations are limited in this area but it may be necessary to re-evaluate the
need for additional monitoring wells.
- West Ash Pond. HIGH RISK. Several constituents were detected at or beyond the
compliance boundary greater than the 2L Standards or IMAC including (but not
limited to) boron, cobalt and vanadium. MW-5D has boron and cobalt detections
greater than the 2L Standard. MW-5BR has detections of vanadium greater than the
2L Standard.
- Unnamed Eastern Extension Impoundment. HIGH RISK. The impoundment has not
yet been characterized, but site conditions are assumed to be similar to the East Ash
Pond.
• Population Served by Water Supply Wells Within 1,500 feet Up -Gradient or Side -Gradient of
the Established CCR Impoundment Compliance Boundary:
- East Ash Pond. LOW/INTERMEDIATE RISK. DW-33 from Duke WSW survey. With
the assumption of 2.5 users per well, there would be 2.5 users.
- West Ash Pond. LOW/INTERMEDIATE RISK. DW-33 from Duke WSW survey. With
the assumption of 2.5 users per well, there would be 2.5 users.
- Unnamed Eastern Extension Impoundment. LOW/INTERMEDIATE RISK. The
impoundment has not yet been characterized, but site conditions are assumed to be
similar to the East Ash Pond.
• Population Served by Water Supply Wells within 1,500 Feet Downgradient of the Established
CCR Impoundment Compliance Boundary:
- East Ash Pond. LOW RISK. Based on information in the CSA Report and groundwater
modeling presented in the CAP Report, there are no water supply wells that are
located in the overall downgradient groundwater flow direction of the impoundment
compliance boundary. Well DW-49 is located on the adjacent industrial lot across a
hydraulic divide and may be used as a public water supply.
- West Ash Pond. LOW RISK. Based on information in the CSA Report and
groundwater modeling presented in the CAP Report, there are no water supply wells
that are located in the overall downgradient groundwater flow direction of the
impoundment compliance boundary.
- Unnamed Eastern Extension Impoundment. LOW RISK. Based on information in the
CSA Report and groundwater modeling presented in the CAP Report, there are no
water supply wells that are located in the overall downgradient groundwater flow
direction of the impoundment compliance boundary. Well DW-49 is located on the
adjacent industrial lot across a hydraulic divide and maybe used as a public water
supply.
Proximity of 2L Standard or IMAC Exceedances Beyond the Established CCR Impoundment
Compliance Boundary with Respect to Water Supply Wells:
- East Ash Pond. HIGH RISK. DW-26 (Duke WSW survey) is less than 500 feet with
respect to MW-17BR. Monitoring well MW-17BR has detections of Vanadium (but
not limited to) at 0.968 micrograms per liter (µg/L). MW-17BR is located
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Appendix G — Roxboro
approximately 1,400 feet from the compliance boundary in what is expected to be
generally up -gradient of the impoundments. The intent of this well location was to
serve as background location for the naturally occurring groundwater geochemistry.
- West Ash Pond. INTERMEDIATE RISK. DW-46 (Duke WSW survey) is between a
horizontal distance of 500 to 1,500 feet with respect to BG-1. Monitoring well BG-1
has detections of vanadium and cobalt (but not limited to) at 17.1 µg/L and 1.28
ug/L.
- Unnamed Eastern Extension Impoundment. HIGH RISK. The impoundment has not
yet been characterized, but site conditions are assumed to be similar to the East Ash
Pond.
• Groundwater Emanating from the Impoundment that Exceeds 2L Standard or IMAC and that
Discharges into a Surface Water Body:
- East Ash Pond. HIGH RISK. Seeps S-9 and S-13 have had detections of boron and
vanadium that exceed the 2L Standards or IMAC. The final discharge point is the
channel and associated CCR impoundment north of the CCR impoundment. The
channel and associated CCR impoundment is interconnected with Hyco Reservoir.
Wells MW-11BR and MW-6D have detections of vanadium greater than the 2L
Standard or IMAC. This well pair may represent a flowpath from the ash
impoundment to a surface water extension of Hyco Reservoir.
- West Ash Pond. HIGH RISK. Wells CW-02 and CW-02D have detections of vanadium
greater than the 2L Standard or IMAC. The wells are located adjacent to the
discharge CCR impoundment below the ash basin which discharges into Hyco
Reservoir. The wells are in a location generally downgradient from the CCR
impoundment.
- Unnamed Eastern Extension Impoundment. HIGH RISK. The impoundment has not
yet been characterized, but site conditions are assumed to be similar to the East Ash
Pond.
• Data Gaps and Uncertainty Related to Transport of Contaminants to Potential Receptors:
- East Ash Pond. HIGH RISK. Receptor sampling has detected the presence of
constituents that may or may not be associated with the CCR impoundment. In light
of this data additional assessment may be necessary. NCDEQ is currently awaiting a
determination of the naturally occurring background concentrations for constituents
at this facility which may have a significant impact to this ranking category.
- West Ash Pond. HIGH RISK. Receptor sampling has detected the presence of
constituents that may or may not be associated with the CCR impoundment. In light
of this data additional assessment may be necessary. NCDEQ is currently awaiting a
determination of the naturally occurring background concentrations for constituents
at this facility which may have a significant impact to this ranking category.
- Unnamed Eastern Extension Impoundment. HIGH RISK. This impoundment has just
recently been identified by Duke Energy. Assessment is currently underway with
respect to the extent of the impoundment and any potential groundwater
contamination resulting from the impoundment. The location of this impoundment
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Appendix G — Roxboro
is in close proximity to residential water supply wells. NCDEQ is currently awaiting a
determination of the naturally occurring background concentrations for constituents
at this facility which may have a significant impact to this ranking category.
G.1.6 Purpose and Objectives
The purpose of this document is to provide additional detailed evaluation of Roxboro related data to
clarify the subjects noted in the NCDEQ risk classification comments (see previous section). More
specifically, this appendix is written to provide a technical evaluation to determine if water supply wells
in the vicinity of Roxboro may be affected by CCR constituents and provide a better understanding of
whether those metals and other constituents present in water supply wells are naturally occurring or
whether they are present due to migration from the groundwater in the vicinity of the ash basins.
This document is divided into four sections:
• Section G.2 provides an evaluation of the water supply well data with respect to regulatory
standards and health -risk -based screening levels.
• Section G.3 presents additional statistical evaluation of the water supply well data and
background data to provide a more detailed and critical evaluation of the constituents that may
be present either due to the influence of nearby ash basins or are naturally occurring and
commonly found in groundwater not affected by Roxboro operations.
• Section G.4 provides the hydrogeologic findings of addition groundwater modeling and an
additional evaluation of groundwater flow patterns in the vicinity of Roxboro with respect to the
locations of the water supply wells.
• Section G.5 provides an evaluation of the geochemical fingerprint of pore water and
groundwater at the ash basin and related coal ash facilities compared to the geochemical
fingerprint of water supply wells and regional background wells. This comparison provides a
statistical evaluation of constituent data for specific data sets: ash basin pore water, facility
groundwater, facility background, water supply wells, and regional background, and identifies
where these fingerprints are the same, similar, or significantly different. An interpretation of
the data is provided together with specific conclusions regarding areas that show the potential
presence of CCR constituents within and outside of the compliance boundary for Roxboro.
Section G.6 provides a summary of conclusions and a discussion of their potential impact on the
risk classification for this site.
G.2 WATER SUPPLY WELL DATA EVALUATION
The purpose of this section is to evaluate data for water supply wells in the vicinity of Roxboro with
respect to applicable screening levels.
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Appendix G — Roxboro
G.2.1 Data Sources
As part of the receptor survey, 3 public water supply wells and 58 private water supply wells were
located within a 0.5-mile radius of the ash basin system compliance boundary (Figure G2-1). This
section presents an evaluation of the water supply well data from the following two sources:
• A total of 15 samples collected by the NCDEQ from 15 wells within a 0.5-mile radius of the
Roxboro ash basin system compliance boundary; and
• A total of 26 samples collected by Duke Energy from background water supply wells located
within a 2- to 10-mile radius from the Roxboro site boundary.
Where there were multiple results for a single well in the NCDEQ-sampled local water supply well
dataset, a representative value was identified to be used in the evaluation, which is defined as the
maximum of the detected values if the analytical results are not detected values. If the analytical results
are all not detected, the lowest reporting limit is defined as the representative value.
G.2.2 Screening Levels
Analytical data from the NCDEQ-sampled water supply wells and the background water supply wells
were compared to the following state and federal drinking water levels:
• North Carolina Statute 15A NCAC 02L.0202 (2L Standard) groundwater standards (NCAC, 2013);
• Federal Safe Drinking Water Act maximum contaminant levels (MCLs) and secondary drinking
water standards (SMCLs) (USEPA, 2012);
• NCDHHS screening levels (NCDHHS, 2015); and
• USEPA Risk -Based Screening Levels (RSLs) (USEPA, 2015b).
As discussed in the main report, the IMAC value used by NCDEQ and the NCDHHS screening level for
vanadium has been changed, but to date the new screening level has not been released. Similarly, the
NCDHHS screening level for hexavalent chromium has been changed, but to date the new screening
level has not been released. Thus, these screening tables use the publicly available values for these two
constituents.
G.2.3 Results
Tables G2-1 through G2-4 present the comparison of the NCDEQ data for the water supply wells located
within a 0.5-mile radius of the Roxboro ash basin system compliance boundary to 2L standards, USEPA
MCLs, NCDHHS screening levels, and USEPA RSLs, respectively.
Tables G2-5 through G2-8 present the comparison of the Duke Energy data for the background water
supply wells to 2L standards, USEPA MCLs, NCDHHS screening levels, and USEPA RSLs, respectively.
The concentration of boron and the other potential coal ash indicators (discussed in Section 3 of the
main report) were low and not above screening levels in the water supply wells sampled by NCDEQ with
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Appendix G — Roxboro
the exception of one well where chloride and TDS were above the 2L Standards. The 2L Standards are
the same as the federal SMCLs for these constituents, which are based on aesthetics. Boron was
detected infrequently (2 of 15 samples) in the NCDEQ-sampled water supply wells, as well as in the Duke
Energy background wells (2 of 26 samples). Lead was below the drinking water standard in 14 of the 15
NCDEQ sampled water supply wells. pH was below the drinking water standard range in 5 of the 15
NCDEQ-sampled water supply wells; pH was not included in the background water supply well sampling.
In general, these pH results are not unexpected, based on a study published by the United States
Geological Survey (USGS) (Chapman, et al., 2013) and additional North Carolina specific studies (Brief,
1997) showing that groundwater pH in the state is commonly below the MCL range of 6.5 to 8.5.
None of the NCDEQ-sampled water supply well results were above Federal primary drinking water
standards (MCLs), with the exception of the few pH results and lead result noted above. Approximately
a third of the manganese and iron results were above the SMCL, as were 1 of the results for sulfate,
total dissolved solids, and aluminum; however, the SMCLs are based on aesthetics. Moreover, the
aluminum, manganese, and iron results for the NCDEQ-sampled water supply wells were within the
range of concentrations from the Duke Energy background wells.
"Do Not Drink" Letters were issued by NCDHHS for 7 water supply wells in the vicinity of Roxboro, with
hexavalent chromium and vanadium being the primary constituents listed in the letters (see Table G2-9),
though these were based on the now -outdated screening levels, and those "Do Not Drink" warnings
have been lifted for these two constituents. Letters were issued for constituents other than hexavalent
chromium and vanadium, primarily for sodium (4 wells), lead (1 well), and manganese (1 well).
A detailed statistical evaluation of background and comparison to the water supply well data is provided
in the next section.
G.3 STATISTICAL EVALUATION OF BACKGROUND
The purpose of the background evaluation is to develop a site -specific or facility -specific descriptor of
background for constituents of interest, i.e., a background threshold value (BTV). If a sample result is
below the BTV, there is reasonable confidence that the constituent concentration is consistent with
background. However, a sample result above a BTV does not mean that it is not consistent with
background, only that statistically it cannot be determined based on the available background dataset.
Two datasets are available to describe background groundwater conditions in the vicinity of Roxboro:
• The Duke Energy background water supply well dataset; and
• The Roxboro facility background monitoring wells.
The Duke Energy background water supply well dataset is referred to here as regional background, and
the Roxboro background monitoring wells are referred to as facility -specific background.
Ten constituents were selected for the background evaluation studies at Roxboro. The subset of
constituents was defined first by whether "Do Not Drink" letters were issued for those constituents, and
second by the needs of the groundwater chemistry evaluation, which is presented in Section G.S. The
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Appendix G — Roxboro
BTV values were estimated for the ten constituents at Roxboro by using a stepwise approach outlined
below.
1) Initial evaluation of background input data sources.
2) Raw data evaluation by descriptive statistics, histograms, outlier tests, and trend tests.
3) Testing of statistical assumptions of the input data by checking for independent, identically
distributed (IID) measurements and goodness -of -fit (GOF) distribution tests.
4) Selection of an appropriate parametric or non -parametric analysis method to estimate
constituents BTVs.
5) Summarizing the statistical analysis results and drawing conclusions.
The statistical methodology and the conclusions for the background evaluation are presented in the
following sections.
G.3.1 Initial Data Evaluation
The initial statistical evaluation was performed to check the homogeneity of variance assumption for
multiple groups of wells included in the Roxboro facility -specific background monitoring well dataset,
before combining each into a single dataset. In this step, data from discrete data sources for each
background dataset were tested for statistical variations using Levine's test. The test examines if the
differences in sample variances occur because of random sampling. Note that the original focus of the
background evaluation was on vanadium and hexavalent chromium, as these were the two constituents
for which the majority of the "Do Not Drink" letters were issued. This statistical analysis was begun
prior to the lifting of the "Do Not Drink" letters, however, the use of these two constituents for the
purpose of determining whether the datasets can be combined is appropriate.
G.3.1.1 Regional Background Water Supply Well Data
The regional background dataset for Roxboro was provided by Duke Energy. Therefore, as one regional
background dataset is available, a test for homogeneity is not required. Table G3-1 presents the
regional background water supply well dataset for Roxboro.
G.3.1.2 Facility Background Monitoring Well Data
Water supply wells in this region of North Carolina are predominantly bedrock wells. Section GA
discusses this in more detail.
Background wells sampled at Roxboro for the CSA included BG-01, BG-01BR, MW-10BR, MW-13BR, MW-
14BR, MW-15BR, MW-15D, MW-16BR, MW-17BR, and MW-18BR. The initial facility -specific background
evaluation for Roxboro was performed on two background deep (transition zone) wells and eight
background bedrock monitoring wells (BG-01, BG-01BR, MW-10BR, MW-13BR, MW-14BR, MW-15BR,
MW-15D, MW-16BR, MW-17BR, and MW-18BR) (see Figure G3-1). Background wells screened in the
shallow formation were excluded from the analysis to limit the data used to that same flow layer that
the off -site water supply wells draw from. The facility -specific background monitoring well data that is
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Appendix G — Roxboro
used in the background data evaluation for Roxboro is presented in Table G3-2. The sample size for
both vanadium and hexavalent chromium consists of less than five samples per well. The results of the
statistical computations indicated that there are no significant differences between monitoring well data
for vanadium and hexavalent chromium. Although decisions based upon statistics computed using
discrete data sets of small sizes (e.g., < 8) are generally not used to make decisions, based on facility -
specific knowledge developed during the detailed environmental investigations and the limited
statistical evaluation, the data from facility -specific background monitoring wells presented in Table G3-
2 and Figure G3-1 were combined for the facility BTV estimates. The results of the Levine's test are
presented in Attachment G-1.
G.3.2 Raw Data Evaluation
In the raw data evaluation for Roxboro, the descriptive statistics for ten constituents for both the
regional and facility -specific datasets were computed and tabulated in Table G3-3. The most common
descriptive statistics included the following: Frequency of Detection (Column 3), Percent Non -Detects
(ND) (Column 4), Range of Non -Detects (Column 5), Mean (Column 6), Variance (Column 7), Standard
Deviation (Column 8), Coefficient of Variation (Column 9), 50th percentile (Column 10), 95th Percentile
(Column 11), and Maximum Detects (Column 12). Critical information such as the requirement for a
certain minimum number of samples and percent NDs were evaluated during this step. Ideally, 8-10
background measurements would be available, and preferably more, to perform meaningful statistical
tests.
In cases where there is a small fraction of non -detects in a dataset (10-15% or less) censored at a single
reporting limit, simple substitution methods were utilized by substituting each non -detect with an
imputed value of the method detection limit (MDL). In complicated situations such as the presence of
multiple MDLs intermingled with difference non -detect levels or when the proportion of non -detects
was larger, strategies such as Kaplan -Meier (KM) and Robust Regression on Order Statistics (ROS) were
utilized.
Visual plots such as histograms and probability plots were plotted to examine the data closely and
visually determine if there were extreme outliers in the dataset. If extreme outliers were visually
identified, then outlier tests (Dixon's and Rosner's) were performed to confirm if there are outliers at a
5% significance level. The decision to include or exclude outliers in statistical computations was decided
by the project team based on constituent and facility -specific knowledge. If the presence of an outlier
was confirmed, and if there was enough evidence to remove the outlier, then the outlier was removed
from further statistical analysis. The results of the outlier tests, Outlier Presence (Column 13) and
Outlier Removal (Column 14), for ten constituents for both regional and facility -specific datasets are
presented in Table G3-3. Attachment G-1 presents the histograms, probability plots and outlier tests for
the ten constituents.
G.3.2.1 Regional Background Water Supply Well Data
The descriptive statistics for the regional background water supply wells indicated the presence of a high
percentage of non -detects (NDs) for boron, cobalt, hexavalent chromium, vanadium and nickel;
<_ 2 samples out of 25 had detections of boron, cobalt; 5 samples out of 25 had detected values for
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Appendix G — Roxboro
hexavalent chromium; 8 samples out of 25 had detected values for vanadium; and 9 samples out of 25
had detected values for nickel. Due to the presence of high percentage of NDs in the dataset, the outlier
test statistics were computed using the detected data alone. As presented in Table G3-3 (Columns 13 -
14), an analysis using visual plots and the Dixon's Outlier Test indicated the presence of outliers in the
data set, specifically with regard to well DBKG-RO14. Sampling results from this well showed significant
concentration variations for cobalt, iron, manganese, and vanadium and, therefore, the samples
collected from this regional background well were removed from further analysis, and descriptive
statistics were recalculated.
G.3.2.2 Facility Background Monitoring Well Data
The descriptive statistics performed on facility -specific background data indicated that greater than
40 percent of samples had NDs for boron, cobalt, hexavalent chromium, lead, and nickel. Boron had no
detects and lead had one detect out of 59 samples; cobalt had 26 detects out of 46 samples; hexavalent
chromium had 6 detects out of 22 samples; and nickel had 24 detects out of 43 samples. Statistical
computations indicated the presence of outliers in the dataset. However, outliers are inevitable in most
environmental data and the decisions to exclude them are made based on existing knowledge about the
facility and groundwater conditions. In this instance, based on existing knowledge, that these are data
from background locations not adjacent to the facility, no outliers were removed from the facility
background monitoring well dataset.
G.3.3 Testing of Statistical Assumptions
After performing the initial statistical evaluation and addressing outliers as discussed in the previous
section, two critical statistical assumptions were tested for IID measurements and normality. In general,
the background groundwater data for both the regional and facility -specific datasets were assumed to
have IID measurements for statistical analysis because the design and implementation of a monitoring
program typically results in IID measurements. The groundwater samples are not statistically
independent when analyzed as aliquots or splits from a single physical sample. Therefore, split sample
data were treated as described in Section G.2.1, such that a single value for each constituent was used in
the statistical evaluations.
To test for normality, the data was first analyzed visually by generating histograms and probability plots.
This was followed by an evaluation using GOF tests. The GOF statistics were generated using USEPA
ProUCL software (USEPA, 2013), which tests for normal, lognormal and gamma distributions to establish
the appropriate distribution. If the GOF test statistics suggested the data to follow normal, lognormal or
gamma distributions, parametric methods were utilized to estimate BTV values. If the normality
assumption was not met the data was considered to be distribution free, and non -parametric statistical
methods were used to estimate BTV values.
A common difficulty in checking for normality among groundwater measurements is the frequent
presence of non -detect values, known in statistical terms as left -censored (positively skewed)
measurements. The magnitude of these sample concentrations is unknown and they fall somewhere
between zero and the detection or reporting limit. Many positively skewed data sets follow a lognormal
as well as a gamma distribution. It is well-known that for moderately skewed to highly skewed data
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Appendix G — Roxboro
sets, the use of a lognormal distribution tends to yield inflated and unrealistically large values of the
decision statistics especially when the sample size is small (e.g., <20-30). In general, it has been
observed that the use of a gamma distribution tends to yield reliable and stable values. The
distributions determined by GOF tests (Column 15) for ten constituents for both regional and facility -
specific datasets are presented in Table G3-3. Attachment G-2 presents the GOF tests statistics.
G.3.3.1 Regional Background Water Supply Well Data
The test statistics revealed that barium, hexavalent chromium, iron, manganese, and vanadium follow a
parametric distribution; hence, parametric methods were used to compute BTVs. Non -parametric test
methods were used to compute the BTVs for lead and nickel. No further evaluation was performed on
boron and cobalt due to the presence of <_ 2 detects.
G.3.3.2 Facility Background Monitoring Well Data
The test statistics revealed that cobalt, hexavalent chromium, iron, and vanadium follow a parametric
distribution; hence, parametric methods were used to compute BTVs. Non -parametric test methods
were used to compute the BTV for barium, manganese, nickel, and chloride. No further evaluation was
performed on boron and lead due to the presence of <_ 1 detects.
G.3.4 BTV Estimates
In this step, an appropriate parametric or non -parametric test method to estimate BTVs was selected
based on conclusions from the above sections. When selecting parametric methods or non -parametric
methods, it is implicitly assumed that the background dataset used to estimate BTVs represents an
unimpacted, single statistical population that is free from outliers. However, since outliers are
inevitable in most environmental data (high percentage of NDs), when present, outliers were treated on
a facility -specific basis using all existing knowledge about the facility, groundwater conditions, and
reference areas under investigation as discussed in the previous section. The BTVs for the constituents
were estimated using ProUCL (USEPA, 2013) by using one of the following methods.
• Parametric or non -parametric 95 %Upper Prediction Limits (UPL95)
• Parametric or non -parametric Upper Tolerance Limits (UTL95-95) with 95% confidence and 95%
coverage
A prediction interval is the interval (based upon background data) within which a newly and
independently obtained (future observation) site observation (e.g., onsite, downgradient well) of the
predicted variable (e.g., boron) falls with a given probability (or Confidence Coefficient [CC]).
Prediction interval tells about the distribution of values, not the uncertainty in determining the
population mean. A UPL95 represents that statistical concentration, such that an independently -
collected new/future observation from the population will exhibit a concentration less than or equal to
the UPL95 with a CC of 0.95.
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A tolerance limit is a confidence limit on a percentile of the population rather than a confidence limit on
the mean. A UTL95-95 represents that statistic such that 95% of the observations (current and future)
from the target population will be less than or equal to the UTL95-95 with a CC of 0.95. Stated
differently, the UTL95-95 represents a 95% UCL of the 95th percentile of the data distribution. A UTL95-
95 is designed to simultaneously provide coverage for 95% of all potential observations (current and
future) from the background population with a CC of 0.95. A UTL95-95 can be used when many
(unknown) current or future on -site observations need to be compared with a BTV. For moderately to
highly skewed data sets (high percentage of NDs), upper limits using KM estimates in gamma UCL and
UTL equations provide better results, if the detected observations in the left -censored data set follow a
gamma distribution.
The nonparametric upper limits (e.g., UTLs, UPLs) are computed by the higher order statistics such as
the largest, the second largest, the third largest, and so on of the background data. The order of the
statistic used to compute a nonparametric upper limit depends on the sample size, coverage probability,
and the desired CC. In practice, non -parametric upper limits do not provide the desired coverage to the
population parameter (upper threshold) unless the sample size is large.
Table G3-3 presents the estimated BTV values (Column 16) and applicable methods (Column 17) used in
estimating the upper threshold values. Attachment G-3 presents the proUCL output of the BTVs
computations.
G.3.5 Comparison of Water Supply Well Data to the Regional BTVs
The data for the water supply wells located within the 0.5-mile radius from the ash basin system
compliance boundary were compared to the regional background BTVs presented in Table G3-3.
Comparison to the regional background BTVs are presented in Table G3-4, and comparison to the
facility -specific background BTVs are presented in Table G3-5.
There are a total of 15 water supply well sample results. Barium, boron, hexavalent chromium, lead,
manganese, and vanadium each have only one result of the 15 that is at a concentration above the
regional BTV. Each of these results is from a different well, thus, there is no distinguishable pattern in
terms of areal distribution. The remaining results are all below the regional BTVs.
Boron had one result of the 15 at a concentration above the facility -specific BTV. Lead had 13 results of
the 15 at a concentration above the facility -specific BTV; all but one of these values are below the 2L
Standard and the MCL.
G.4 GROUNDWATER FLOW EVALUATION
[The evaluation in Section G.4, including figures and tables, was provided by SynTerra Corporation.]
G.4.1 Introduction
The objective of this section is to expand upon the site -specific groundwater flow and water quality data
that were presented in the CSA report (SynTerra, 2015a) for the Roxboro Steam Electric Plant to
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demonstrate that ash impacted groundwater associated with the ash basin system has not migrated
toward or intercepted water supply wells located up- and side gradient of the ash basin system.
The CSA was conducted to comply with the CAMA. Fieldwork for the CSA was implemented in
accordance with the NCDEQ approved Groundwater Assessment Plan (Work Plan) (SynTerra, 2014c)
which included an evaluation of groundwater quality and flow characteristics from eight existing
monitoring wells and the installation of 33 additional monitoring wells. The new wells were installed at
specific locations and depths to delineate potential impacts to groundwater from the two ash basins
(East Ash Basin and West Ash Basin). Eight of the newly installed/existing monitoring wells are located
in upgradient locations to characterize background conditions. Additional upgradient background wells
have been installed in 2016 to supplement the CSA data. To date, four groundwater CSA sampling
events have been conducted. Water level measurements are collected during each sampling event to
evaluate the groundwater flow direction. Prior to the CSA, routine groundwater monitoring has been
conducted two or three times a year since at least 2000 with groundwater levels and flow direction
determined for each event. The information consistently indicates the groundwater flow direction is
from upland areas south and east of the plant toward streams which flow north and toward Hyco Lake,
as would be expected by the local topography.
Groundwater flow within the slope -aquifer system is directly influenced by the underlying geologic
framework of the site. The geology is presented in Section G.4.2, the regional groundwater system and
the hydrogeological SCM are presented in Section G.4.3.1, and the location of water supply wells in the
vicinity of the facility and hydrogeology of the site is presented in Section G.4.3.2. Detailed data have
been used to evaluate groundwater flow direction, horizontal and vertical gradients, and the velocity of
groundwater flow as described in Section G.4.3. The data were used to support the development of a
groundwater flow model, which resulted in an understanding of past and potential future groundwater
conditions. The model incorporated the effects of the water supply well pumping in the vicinity of the
site. The groundwater modeling results are discussed in Section G.4.4.
G.4.2 Site Geology
The Roxboro site is located in the Piedmont Province of North Carolina. The geology observed during
the installation of the monitoring wells includes:
• Alluvium (S) - Alluvium is unconsolidated sediment that has been eroded and redeposited by
streams. Alluvium was observed on the north side of the east ash basin (ABMW-5); and would
be anticipated to be present in the vicinity of current and former stream channels.
Residuum (Regolith-Residual Soils; M1) — Residuum is shallow structureless soil that has
developed over time from the in -place weathering of the parent bedrock. Residuum was
observed to be relatively thin and typically dry at the site. Residual soils consisting of silty sands
or clays were usually encountered in the upper 20 feet and generally graded downward to
saprolite soil.
Saprolite/Weathered Rock (Regolith; M2) — Saprolite is also soil that developed by the in -place
weathering of parent bedrock but still exhibits the relict rock structure (texture and layering).
Saprolite was observed at depths ranging from 3 to 48 feet below ground surface and also
tended to be dry at the site.
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Appendix G — Roxboro
Partially Weathered/Fractured Rock (TZ) — This material consists of partially weathered and/or
highly fractured bedrock below the saprolite and above competent bedrock. The partially
weathered/fractured rock layer is also referred to as the 'transition zone.' When observed, the
thickness ranged from 5 to 20 feet. When saturated, the transition zone can be the most
dominant component of the groundwater flow system. However, at Roxboro the transition
zone was observed to be mostly dry.
Bedrock — Bedrock is solid rock that is unweathered to slightly weathered and relatively
unfractured. The dominant rock types observed at Roxboro were metamorphic biotite gneiss,
felsic gneiss or granitic gneiss. Biotite gneiss was more common in the north/northwest portion
of the site, felsic gneiss in the central portion, and granitic gneiss/granite in the south
southeastern portion of the site.
Ash and structural fill overlay the natural materials in both ash basins. The ash was generally found to
be sand -sized with abundant silt and clay size particles. The thickness of the ash ranged from 11 to
78 feet below ground surface. Additional information on the site geology is in the CSA Section 6.1
(SynTerra, 2015a).
G.4.3 Site Hydrogeology
G.4.3.1 Site Conceptual Model
A SCM was developed during preparation of the CSA Work Plan to inform decisions regarding the field
exploration (i.e., monitoring well locations, screened intervals, target depths, etc.). The SCM was based
largely on the LeGrand (1988, 1989) conceptual model of the groundwater setting in the Piedmont and
incorporated Harned and Daniel's (1992) two -medium system, the overburden and competent bedrock.
The generalized conceptual model is a slope -aquifer system where a surface drainage basin is contained
within one or more adjacent topographic divides, located along a ridge tops serving as the upper
hydraulic boundaries and a stream, river, or lake serving as the lower hydraulic boundary (LeGrand,
1988).
Each surface drainage basin is similar to adjacent drainage basins with conditions being generally
repetitive from basin to basin within each ridgeline to adjacent surface water feature. Within a drainage
basin, movement of groundwater is generally restricted to the area extending from the topographic
ridges to perennial streams (LeGrand, 1988; 1989; 2004). Rarely does groundwater move beneath a
perennial stream to another more distant stream or across drainage divides (LeGrand, 1989). The crests
of the water table underneath topographic drainage divides represent natural groundwater divides
within the slope -aquifer system and control the direction of groundwater flow within each drainage
basin. The concave topographic areas between the topographic divides may be considered as flow
compartments that are open-ended down slope. As a result, natural groundwater flow paths in the
Piedmont are confined to the area underlying the topographic slope extending from a topographic ridge
or drainage divide to an adjacent stream or water feature, with the water feature serving as the
groundwater discharge location (or surface expression of groundwater). Under natural conditions, the
general direction of groundwater flow can be approximated from the surface topography (LeGrand,
2004).
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Appendix G — Roxboro
The two -medium system consists of two interconnected layers, or media: 1) residual soil/saprolite and
weathered fractured rock (regolith), overlying 2) fractured crystalline bedrock (Heath, 1980; Harned and
Daniel, 1992). The residual soil grades into saprolite, a coarser grained material that retains the
structure of the parent bedrock. Beneath the saprolite, partially weathered/fractured bedrock occurs
with depth until sound bedrock is encountered. This mantle of residual soil and saprolite (regolith) is a
hydrogeologic unit that covers and crosses various types of rock (LeGrand, 1988). These layers serve as
the principal groundwater storage reservoir and provide an intergranular medium through which the
recharge and discharge of water from the underlying fractured rock occurs (Daniel and Harned, 1998).
Within the fractured crystalline bedrock layer, the fractures control both the hydraulic conductivity and
storage capacity of the bedrock. A transition zone at the base of the regolith is present in many areas of
the Piedmont. Harned and Daniel (1992) described the zone as "being the most permeable part of the
system, even slightly more permeable than the soil zone." Additional details of the SCM are presented
in Sections 5.0 and 6.3 of the CSA report and Section 3.0 of the Roxboro CAP-1 (SynTerra, 2015b).
Based on the results of the CSA, the groundwater system in the in -situ materials (alluvium, soil,
soil/saprolite, and bedrock) and the overlying ash and fill at Roxboro is consistent with the slope-
aquifer/regolith-fractured rock groundwater model and is an unconfined, connected aquifer system.
The hydrostratigraphic layers (layers of material that have different hydraulic parameters) at the site
consist of in -situ units, Alluvium, Residuum (Regolith-Residual Soil), Saprolite/Weathered Rock
(Regolith), Partially Weathered/Fractured Rock (TZ), Bedrock, and anthropogenic units, ash and fill, as
described in Section G.4.2. These units are used in the groundwater model of the site discussed in
Section G.4.4. Additional information concerning the development of the hydrostratigraphic layers is
presented in Section 11.1 of the CSA (SynTerra, 2015a).
G.4.3.2 Groundwater Flow Direction
The Roxboro groundwater system is divided into three flow layers referred to as the shallow (S), deep (D
or TZ), and bedrock (BR) flow layers to distinguish the layers within the connected, unconfined aquifer
system. Monitoring wells have been installed with screens placed in each of these flow layers.
Groundwater elevations measured in monitoring wells show that groundwater flow in all three flow
layers is somewhat complex with a generalized flow from upland areas south and southeast (as recharge
areas) to the north/northwest toward Hyco Lake and its tributaries. Localized areas of groundwater
discharge occur from the two ash basins and the topographic ridge separating the basins. Minor
influences to groundwater flow include the earthen impoundments creating the basins; the intake canal,
the west cooling reservoir, and the discharge canal (present on the west side of the West Ash Basin)
with discharge to Hyco Lake.
The location of water supply wells and groundwater flow direction are shown on Figure G4-1. The
groundwater flow direction is consistent with the slope -aquifer system and shows that groundwater
flow is away from off -site water supply wells and toward the discharge feature, Hyco Lake and its
tributaries.
Vertical gradients, as measured by differences in groundwater elevations at various monitoring wells,
indicate that the higher topographic areas serve as a groundwater recharge zones and that Hyco Lake
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Appendix G — Roxboro
and its tributaries serve as the groundwater discharge zones in the vicinity of the Roxboro Plant.
Groundwater elevation data collected from background well pairs, MW-15D/BR and MW-18D/BR,
indicate a downward vertical gradient indicative of a groundwater recharge zone.
G.4.3.3 Groundwater Seepage Velocities
Groundwater seepage velocities were estimated for the hydrostratigraphic units at the site. The
seepage velocity is a measure of the lateral flow within a groundwater flow layer, and is calculated using
the average horizontal hydraulic conductivity values from field slug tests, average effective porosity
from laboratory testing or from technical literature (CSA, SynTerra, 2015a) and measured horizontal
hydraulic gradients between a number of wells within the same hydrostratigraphic unit (CSA,
Section 6.2.2; Table 6-7). The estimated groundwater seepage velocities are provided in Table 6-7 of the
CSA (SynTerra, 2015a).
Additional details on the field testing and laboratory testing for estimating hydrogeologic parameters
are presented in Section 6.2 of the CSA (SynTerra, 2015a).
G.4.3.4 Constituents Associated with CCR
Certain constituents present in coal ash can serve as indicators of a release from a coal ash management
area to groundwater; these have been used by USEPA to design the groundwater monitoring program
under recent regulation. This section builds upon that knowledge to evaluate the presence of
constituents in groundwater associated with a release from the ash basins. Evaluation of constituent
presence or absence in each flow layer, and the magnitude of the concentrations provide an
independent means of assessing the horizontal and vertical flow of groundwater, and the ability of
groundwater to migrate vertically between the flow layers.
On April 17, 2015, the USEPA published its final rule "Disposal of Coal Combustion Residuals from
Electric Utilities" (Final CCR Rule) to regulate the disposal of CCR as solid waste under subtitle D of the
Resource Conservation and Recovery Act (USEPA, 2015a). The USEPA defined a phased approach to
groundwater monitoring. The first phase is detection monitoring where groundwater is monitored to
detect the presence of specific constituents that are considered to be indicators of a release from a coal
ash management area (e.g., metals) and other monitoring parameters (e.g., pH, TDS). These data are
used to determine if there has been a release from a coal ash management area. Detection monitoring
is performed for the following list of "indicator" constituents identified in Appendix III of the CCR Rule:
• Boron;
• Calcium;
• Chloride;
• Fluoride (this constituent was not analyzed for in the CSA);
• pH;
• Sulfate; and
• TDS.
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Appendix G — Roxboro
In selecting the constituents for detection monitoring, USEPA chose constituents that are present in CCR
and that are more soluble and move through the soil column and with groundwater without
retardation, relative to other constituents. Thus, groundwater monitoring for these constituents allows
for an evaluation of whether constituents are migrating from a CCR unit. Coal ash constituents do not
measurably increase the density of groundwater or have a separate liquid phase in groundwater as
compared to other dense liquids that would "sink" in the aquifer, like saltwater. Thus, releases from
coal ash management areas tend to remain in the shallower groundwater zones.
G.4.3.5 Extent of Boron Exceedances in Groundwater
Groundwater at Roxboro was monitored for a wide range of constituents, as required by the CAMA, and
listed in the CSA (SynTerra, 2015a). Boron may be one of the more common indicators for evaluation of
groundwater for releases from coal ash management areas due to boron concentrations in CCR leachate
being usually higher than in typical groundwater. Boron also tends to be highly mobile in groundwater.
For these reasons, boron is often used as an indicator constituent for CCR leachate (Electric Power
Research Institute [EPRI], 2005).
At Roxboro, boron exceedances of the 2L Standards reported in groundwater during 2015 are shown in
plan view (Figure G4-2) and in cross-section view (Figures G4-3 through G4-6) to illustrate where this
leading indicator associated with CCR is located across the site. Boron was selected since it is prevalent
in CCR and is not detectable in site background wells. As illustrated in the figures, the boron
exceedances of the 2L Standards in groundwater are located on the northern sides of the ash basins and
are constrained to the south and east by streams (groundwater discharge zones). Boron has not been
detected south or east of these groundwater discharge zones, confirming the groundwater flow
direction is not toward the water supply wells.
G.4.3.6 Bedrock Flow and Depth of Water Supply Wells
Monitoring wells installed during the CSA investigation were located and screened at depths to
characterize potential vertical and horizontal extent of impacts from the ash basins. These monitoring
wells are located in areas of suspected impacts, in presumed background areas, and in areas between
the ash basins and offsite water supply wells. Bedrock monitoring wells installed in upgradient locations
between the ash basins and the water supply wells have confirmed that impacted groundwater in
shallow bedrock is not flowing towards the water supply wells. Additional, deeper bedrock monitoring
wells installed during the first quarter of 2016 in upgradient perimeter areas confirm these observations
(Figures G4-3 through G4-6).
The public water supply wells and 58 private water supply wells are located within a 1,500-foot radius of
the ash basin system compliance boundary, with most of the wells positioned along McGhees Mill Road
and Dunnaway Road to east and southeast of the site. Duke Energy mailed water supply well
questionnaires to surrounding well owners during the Receptor Survey in 2015; however, very few of
the returned questionnaires provided well construction information, such as surface casing depths, total
well depths, pump placement, and flow rates. Most of the wells installed in the Piedmont Province are
assumed to be open boreholes installed within the upper 100 feet of bedrock; however, most in the
region are generally less than 250 feet deep with yields of 10 to 20 gallons per minute (Daniel and
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Appendix G — Roxboro
Dahlen, 2002). It is our understanding that the NCDEQ requested that their third -party samplers record
well construction information (if available) during sampling of the supply wells, but Duke Energy has not
been provided with that data.
Water supply wells are generally cased though the regolith (soil/saprolite), with additional boring
performed as needed into bedrock to produce the desired well yield. Although these water supply wells
may be drilled into bedrock, the storage characteristics of the overlying saprolite and transition zone
control the sustained quantity of water available to the well (Harned, 1989). It is the regolith
(soil/saprolite) that provides the majority of water used in the water supply wells and the bedrock
fractures convey that stored groundwater to the water supply well (Harned, 1989).
This conceptual model, supported by the wealth of data described herein and provided in the CSA and
CAP-1/CAP-2 reports, is depicted in the cross -sections in Figures G4-3 through G4-6. Each cross-section
shows the generalized locations and depths of off -site water supply wells in the vicinity of that cross-
section. Each cross-section also shows the area of groundwater that exhibits boron concentrations
above the 2L standards. As can be seen, these areas are localized, and in contact with the ash basins
and CCR material. Boron from the coal ash basins does not generally occur in detectable concentrations
outside of the site.
As noted above, bedrock flow is away from the off -site water supply wells and towards Hyco Lake and its
tributaries. The data collection and analysis of flow in all three groundwater flow layers at the site was
conducted while the off -site water supply wells were under normal operations. Therefore, the effect of
pumping of off -site water supply wells on the direction of groundwater flow at the site would be
reflected in the water levels measured in the existing network of monitoring wells. Thus, the
measurements of groundwater flow velocity and direction, and the potentiometric flow maps, reflect
groundwater conditions under normal use of the off -site water supply wells. The effect of pumping
water supply wells on groundwater flow and direction is discussed in more detail in Section G.4.5.
G.4.3.7 Groundwater Mounding
Groundwater mounding refers to the extent to which ash ponds, or any other pond, may raise or
variably influence the natural groundwater levels causing flow to leave the basin radially against the
prevailing slope -aquifer gradient. Topographical and monitoring well groundwater data can be used to
establish the extent to which localized hydraulic mounding may emanate from an ash basin and if this
may affect the local groundwater flow direction. A review of topographic and monitoring well
groundwater data at Roxboro indicate potential mounding would be contained within the groundwater
flow systems on the north sides of the tributaries to Hyco Lake.
G.4.3.8 Summary
The hydrogeologic SCM presented in the CSA report (SynTerra, 2015a) and refined in the CAP-2 report
(SynTerra, 2016) describes groundwater flow in the shallow, deep (TZ), and bedrock groundwater zones
as predominantly horizontal with flow to the north/northwest toward Hyco Lake and its tributaries. The
basis for this conclusion is the analysis of monitoring well water elevation data during the sampling
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Appendix G — Roxboro
events. Hyco Lake serves as the hydrologic discharge boundaries for groundwater at the site. There are
no water supply wells located between the ash basin system and Hyco Lake.
G.4.4 Water Supply Well Capture Zone Analysis
A well capture zone analysis was performed to delineate well capture zones for the active water supply
wells near the Duke Energy property boundary at Roxboro. A well capture zone is the area of an aquifer
in which all the water will be removed by pumping wells within a specified time period (Grubb, 1993).
Consequently, mobile constituents within the capture zone would also be removed by pumping within
this timeframe. Groundwater pumping produces a low pressure area in the groundwater flow field that
induces groundwater flow towards the well. The pressure front does not propagate evenly through the
aquifer as groundwater upgradient from the well has higher potential energy and is already flowing
towards the well (positive kinetic energy). The pressure front extends outward into the aquifer until
equilibrium is reached. At this point, the aquifer volume contributing water stabilizes and the flow rate
of water into the well equals the pumping rate. Consequently, the miscible and mobile constituents in
groundwater, if present, within the capture zone are removed by pumping.
In the capture zone analysis, a model is used to simulate the normal pumping of the water supply wells
and the capture zones generated by the model are compared to the footprints of the ash basin waste
boundary. This comparison can be used to identify potential impacts to the recharge areas used by the
water supply wells. The capture zone analysis accounts for the potential effect of adjacent water supply
wells pumping at the same time, and considers the effects of local groundwater flow and other relevant
conditions, such as the location and water elevations of the ash basin system.
As previously discussed in Section G.4.3, in an unconfined aquifer system, such as at Roxboro,
groundwater flow normally follows the surface topography flowing from areas of higher elevation
(higher water levels) to areas of lower elevation (lower water levels) due to gravity (Freeze and Cherry,
1979). Typically, aquifer recharge occurs at higher elevations where vertical downward flow is
predominant. Aquifer discharge areas (e.g., a groundwater seep line near a stream) are found at lower
elevations. The well capture zone will extend further upgradient than downgradient, as that is the
predominant source of water recharge to the well.
G.4.4.1 Methodology
The steady-state groundwater flow and contaminant transport model developed for the Roxboro CAP-2
report (SynTerra, 2016) was utilized for this study. The capture zone was simulated using a similar
approach as the contaminant transport model to predict concentrations; however, MODPATH is used in
the calibrated flow model instead of MT3DMS. The model MODPATH, widely used by the USGS, is a
"particle tracking" model that traces the groundwater flow lines from any desired starting position.
MODPATH can be used with the reverse tracking feature to trace the groundwater flow lines around
each well to see where the water that is pumped from the well originates. This well-known procedure is
called a well capture zone analysis, because it identifies the zone from which all of the water entering
the well is captured. The groundwater flow model was calibrated to match water levels measured
in June 2015 for shallow, deep (TZ), and bedrock wells and specifically considered the potential effects
of local water table mounding from the ash basins due to enhanced infiltration from the basins. A
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Appendix G — Roxboro
primary concern at each of the ash basins was possible impacts to domestic and public wells from the
ash basins. The calibrated groundwater flow model used to assess these possible impacts by
considering pumping from all of the private and public wells within the model domain of the site.
The model solution for groundwater flow for the Roxboro CAP-2 was performed under existing
conditions. Although pumping rates for the individual household wells at the site was not available, an
assumption equal to the average US household water use rate of 400 gallons per day (USEPA, 2008) was
used. It was assumed that all of the wells in the model domain were pumping continuously unless they
were known to be inactive. Additional information on the groundwater model is included in CAP-1
Section 2 and CAP-2 Section 3 (SynTerra, 2015b, 2016).
G.4.4.2 Results
A numerical capture zone analysis for the Roxboro site was conducted to evaluate potential impact to
upgradient water supply pumping wells. The analysis for water supply wells near the Roxboro site
indicates that well capture zones projected well into the indefinite future are limited to the immediate
vicinity of the well head and do not extend toward the ash basins and the impoundment as
demonstrated in the figure below. Further, none of the particle tracks originating in the ash basin or the
impoundment moved into the well capture zones.
The supply well capture zones are represented in this figure by the yellow particle tracks and the ash
basins are outlined in orange. The blue arrows show the overall directions of groundwater flow. In
general, the shape of a given capture zone is a function of various hydrogeologic parameters including
recharge, hydraulic conductivity, flow rate, and hydraulic gradient. For the Roxboro site, the primary
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Appendix G — Roxboro
influence on the shape of the capture zone is the hydraulic gradient. When the prevailing hydraulic
gradient is small and relatively flat, the capture zone approaches a circular configuration. As the
hydraulic gradient increases, the shape becomes elongated in a locally upgradient direction. As can be
seen from this figure, the recharge areas supplying water to the private water wells are away from the
direction of the ash basins due to topographic ridge lines that separate the recharge areas.
The analysis found that the source of groundwater for the water supply wells is upgradient of the ash
basin, and supplied by recharge falling on areas not impacted by coal ash. The groundwater flow
directions are consistent with the slope -aquifer system and show that groundwater flow is away from
off -site water supply wells and toward the discharge feature, Hyco Lake. Note that certain limitations
and assumptions were made while developing the model. The limitations and assumptions produce
conservative results and do not affect the findings as presented above. Results are considered
conservative because particle tracking has been assessed for the greatest amount of time since the ash
basin system began operating, and water supply wells were conservatively assumed to pump
continuously at 400 gallons/day, which is the average household usage rate.
G.4.5 Summary and Conclusions
Major findings from the evaluation of groundwater flow at the Roxboro Plant are as follows:
The groundwater system at Roxboro is consistent with the conceptual model of groundwater
within an unconfined, two -medium system (regolith consisting of soil, saprolite and transition
zone overlying bedrock) within a slope -aquifer system. Within the basin footprint, ash, fill, and
alluvium are additional layers that overlie the two -medium system. Three primary flow layers
(as defined by the regolith, the transition zone and bedrock) are present in the unconfined
groundwater system at the site; shallow (S - water table), deep (D - TZ), and bedrock (BR).
• Site -specific water level measurements confirm that groundwater flow, primarily within the
transition zone (where saturated) and fractures in the upper bedrock, with a generalized flow
from upland areas south and southeast (as recharge areas) to the north/northwest toward Hyco
Lake and its tributaries, and also confirm the flow model predictions.
• A review of topographic and monitoring well groundwater data at Roxboro indicate potential
mounding would be contained within the groundwater flow systems on the north sides of the
tributaries to Hyco Lake.
• Boron exceedances of the 2L Standards in groundwater are located on the northern sides of the
ash basins and are constrained to the south and east by streams (groundwater discharge zones).
Boron has not been detected south or east of these groundwater discharge zones, confirming
the groundwater flow direction is not toward the water supply wells.
• The water supply well capture zone analysis, as delineated by reverse particle tracking, shows
that the water supply wells are supplied with water from precipitation recharge to the regolith
(soil/saprolite) surrounding the pumping well(s) and the capture zones do not intersect or
originate in the coal ash sources. This analysis considered the potential combined effects of
adjacent pumping wells. Site -specific water level measurements and groundwater modeling
confirm that the combined pumping effect of the water supply wells is not affecting the overall
site groundwater flow direction.
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Appendix G — Roxboro
Based on this evidence, groundwater utilized by water supply wells near the coal ash
impoundments is not impacted by the coal ash sources.
G.5 GROUNDWATER CHARACTERISTICS EVALUATION
The results from the local water supply well testing conducted by the NCDEQ in the vicinity of the
Roxboro facility indicated that some constituents were present at concentrations above state and/or
federal standards and/or screening levels. As noted previously, these constituents are naturally
occurring, and some can be associated with releases from coal ash basin system. Thus, it is critical to
understand the naturally occurring background conditions, the groundwater conditions in the tested
local water supply wells, and the conditions in groundwater at the facility where CCR-impacts have been
demonstrated. A detailed statistical evaluation of background groundwater data compared to the local
water supply well data was presented in Section G.3. As indicated in Section G.4.4, the local water
supply wells generally obtain water through the bedrock fractures that convey stored groundwater in
the regolith. Based on the groundwater transport modeling results in Section E.4.4.2, the source of
groundwater for the local water supply wells is upgradient of the ash basin system, and supplied by
recharge falling on areas not impacted by coal ash. In this section, the chemistry of the groundwater at
the facility in both CCR-impacted areas and areas not impacted by a CCR release is compared to the
chemistry of the local water supply wells. The objective of the evaluation is to understand, from the
groundwater chemistry perspective, whether the CCR-impacted groundwater at the facility has resulted
in the water quality exceedances found in the local water supply wells.
The evaluation consists of the following two key steps:
• Identify site -specific CCR-related signature constituents that can effectively serve as indicators
to evaluate the extent of the CCR-impacted groundwater.
• Compare the absolute and relative abundance of major common constituents and signature
constituents among various well groups to determine whether CCR-impacted groundwater at
the site has resulted in the water quality exceedances found in the local water supply wells.
Based on the results of this evaluation, there is no relationship between the CCR-impacted groundwater
and the water quality exceedances reported in the local water supply wells.
More details regarding the evaluation approach, data analysis methods, results, and conclusions are
presented below.
G.5.1 Evaluation Approach
A multiple -lines -of -evidence approach, as summarized below, was used to facilitate the development of
chemical signatures of the CCR impacted groundwater. The approach consists of the following key
components:
Screen the geochemical and transport behaviors of typical CCR-related constituents to establish
candidate constituents for further evaluation.
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Appendix G — Roxboro
Assess the presence and magnitude of candidate constituents in the groundwater beneath the
site as a result of a release from the ash basin system by comparing the concentration
magnitude of these constituents in the four major well groups below:
— Ash basin porewater monitoring wells;
— Other facility monitoring wells, including wells screened in the shallow flow layer
(shallow wells), wells screened in the transition zones (deep wells), and bedrock wells;
— Local water supply wells (data from NCDEQ); and
— Regional background wells (data from Duke Energy).
Note that the wells in a major group may be further divided into multiple subgroups in order to
evaluate the spatial trends of the groundwater data; for example, the facility bedrock wells may
be further divided into two subgroups based on the groundwater flow direction in the bedrock
unit: (a) facility bedrock wells that are likely to be within the area of CCR-impacted groundwater
and (b) facility bedrock wells that are likely to be outside of this area.
• Identify useful reduction -oxidation (redox) sensitive constituents that can also serve as an
indicator or a signature for CCR-impacted groundwater by comparing the concentration
magnitude of dissolved oxygen, iron, and manganese, among various well groups.
• Select effective constituents that can differentiate the site -related impacts from background
conditions to serve as signature constituents to assess the potential relationship between the
facility CCR-impacted groundwater and the local water supply wells.
• Compare the relative abundance patterns of major cations and anions in groundwater among
various well groups to assess the data clustering pattern and correlation among various well
groups.
• Apply the site -specific geochemical principles and the knowledge of the groundwater flow field,
which have been developed and documented in the CSA and CAP reports (SynTerra, 2015a,
2015b, 2016) and summarized in Section G.4, to coherently interpret the groundwater data
trends and to verify or reject the connection between the CCR-impacted groundwater and the
water quality exceedances found in the local water supply wells.
G.5.2 CCR-Related Constituents Screening for Signature Development
The first step for the identification of the CCR-impacted signature constituents is to identify the
constituents that have the following characteristics:
• They are recalcitrant to degradation and transformation under site -specific conditions.
• They are very soluble and subject to little sorption. Based on the chemical properties of CCR
related constituents and the site -specific geochemical evaluation (SynTerra, 2016), typical major
cations (e.g., sodium and calcium) and anions (e.g., chloride and sulfate), boron, manganese
(under the reducing conditions), and cobalt can meet this requirement.
• During the transport process, the constituents of interest are not likely subject to a mechanism
that can increase or decrease their concentrations.
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Appendix G — Roxboro
Their concentrations or values are substantially different from the background concentrations or
values.
Based on these criteria and a review of the chemical data in the CSA report (SynTerra, 2015a), the
following constituents are considered to be the candidates for signature development:
Boron, calcium, sulfate, chloride, and TDS: Based on the understanding of the behavior of
constituents that can be released from coal ash into groundwater, USEPA has identified those
constituents that are considered to be indicators of a potential release from coal ash. These
constituents belong to the CCR Rule Appendix III constituents (USEPA, 2015a). Of these, boron
and sulfate are the most common constituents used to evaluate the potential for an ash
management area impact in groundwater, as will be shown in the evaluation presented below.
• Barium and cobalt: These two trace metals are less sensitive to the redox conditions and not
readily sorbed to mineral surfaces, and can be associated with CCR impacts to groundwater
(USEPA, 2015a). These two trace metals are also selected as candidate constituents. Total
barium and cobalt concentrations were used in this evaluation.
• Dissolved oxveen. dissolved iron. and dissolved maneanese: Groundwater in the ash basin area
generally contains very low concentrations of dissolved oxygen, but high concentrations of
dissolved iron and dissolved manganese (SynTerra, 2015a). The site -specific geochemical
analysis indicates that the groundwater in the ash basin area is generally in the manganese
reducing condition (Figure G5-1) (SynTerra, 2016). It is noted that, because groundwater
samples collected from the regional background wells and local water supply wells only
analyzed for total iron, total iron concentrations were used to conservatively represent the iron
concentrations in these groundwater samples. Because the concentrations of dissolved iron and
manganese are sensitive to the presence of dissolved oxygen, including iron and manganese in
this evaluation is expected to help compare the redox conditions among different well groups.
G.5.3 Data Analysis Methods
G.5.3.1 Data Sources
The groundwater analytical data used in this evaluation are from the following sources:
• Facility groundwater monitoring well data;
• Local water supply well data from NCDEQ; and
• Duke Energy background water supply well data.
G.5.3.2 Data Aggregation
The general rules for data aggregation are described here. When multiple sampling events occur for a
well, the following rules were used to find a representative concentration value for the box plot and
correlation plot evaluations:
• For boron, calcium, chloride, sulfate, TDS, barium, and cobalt, the representative value is
defined as the maximum of the detected values if the analytical results are not all NDs. If the
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Appendix G — Roxboro
analytical results are all NDs, the lowest reporting limit is defined as the representative value.
Using the maximum concentrations will help not underestimate the CCR impacts to the local
water supply wells and facility monitoring wells.
• For dissolved oxygen, total and dissolved iron, and total and dissolved manganese, the average
concentration is used as the representative value for the general conditions observed in a well.
• For piper plots, the average concentration is used as the representative values for the general
conditions observed in a well.
• The reporting limits are used to represent the non -detect results.
G.5.3.3 Box Plot
The comparisons of the concentration magnitude among different well groups for various potential
indicators were made using the box plots produced by the ProUCL software (USEPA, 2013). Figure G5-2
defines the various components of the box plot. The location of the upper whisker is the lesser of
1.5 times the interquartile range (IQR) above the 75 percentile or the maximum value; the location of
the lower whisker is the greater of 1.5 times the IQR below the 25 percentile or the minimum value.
This analysis includes both detected and non -detected values.
G.5.3.4 Correlation Plot
The constituents found to be signature indicators of the CCR-impacted groundwater can be used to
generate correlation plots to further evaluate the relationships among various data groups. To create a
correlation plot, different data groups can be plotted using different symbols with the concentrations of
one constituent on the x-axis and the concentrations of the other constituent on the y-axis. The
clustering patterns or trends will illustrate the correlations among data groups.
G.5.3.5 Piper Plot
Piper plots have been frequently used to assess the relative abundance of general cations (sodium,
potassium, magnesium, calcium) and anions (chloride, sulfate, bicarbonate, and carbonate) in
groundwater and to differentiate different water sources in hydrogeology (Domenico and Schwartz,
1998). Groundwater resulting from different water sources or in different geologic units may exhibit
distinct clustering patterns on a piper plot. Because calcium and sulfate are common coal ash
constituents, it is expected the CCR-impacted groundwater may show a different clustering pattern than
the background groundwater or the groundwater that has not been impacted by CCR.
In the CSA report (SynTerra, 2015a), the piper plots were used to evaluate the water chemistry between
the porewater in the ash basin system and groundwater in other groups of facility monitoring wells. An
example figure is shown in Figure G5-2, which compares the general water chemistry among the
porewater in the ash basin system, surface water in the ash basin system, and groundwater in the
bedrock wells. The piper plot consists of three subplots: a cation composition trilinear plot in the lower
left corner, an anion composition trilinear plot in the lower right corner, and a diamond plot in between.
The red lines on each subplot show how to read the meanings of a data point in a subplot. For example,
in the cation subplot, the data point of AB-21S shows about 20 percent of the total cation charges from
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Evaluation of Water Supply Wells
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Appendix G — Roxboro
sodium and potassium, approximately 25 percent from calcium, and about 55 percent from magnesium.
In the anion subplot, the data point of MW-14B shows about 18 percent of the total anion charges from
sulfate, approximately 20 percent from chloride and nitrate related anions (NO2- and NO3-), and
62 percent from carbonate (CO3'-) plus bicarbonate (HCO3-) anions. In the diamond subplot, the data
point of AB-17S shows about 47 percent of the total anion charges from chloride, nitrate related anions,
and sulfate, and approximately 80 percent of the total cation charges from calcium and magnesium.
The piper plots for this evaluation were generated using the GW_Chart program developed by the USGS
(Winston, 2000).
G.5.4 Evaluation Results
G.5.4.1 Box Plot Comparison
The box plot comparison of boron, calcium, chloride, sulfate and TDS concentrations among various well
groups is shown in Figure G5-3. The most significant concentration differences between the results of
the ash basin porewater wells and the local water supply wells were found to be boron and sulfate. The
differences for other constituents are not as noticeable as those for boron and sulfate. The box plot
comparison of barium and cobalt is provided in Figure G5-4. The barium and cobalt concentration
differences between the ash basin porewater and the groundwater in local water supply wells are also
not as significant as boron and sulfate.
Because boron and sulfate are very mobile, subject to little sorption onto mineral surfaces, and not
susceptible to degradation or transformation, and because they show the most elevated concentrations
(relative to the concentrations found in the local water supply wells), they are thus considered to be
effective signature constituents.
The box plot comparison of dissolved oxygen, iron, and manganese is shown in Figure G5-5. The trend
of dissolved oxygen concentrations shows that the groundwater in the local water supply wells is
generally more oxygenic than the porewater in the ash basin system. The observed low oxygen
concentrations in the ash basin porewater are consistent with the understanding that coal ash leachate
is a chemically reduced solution (USEPA, 1980). The depletion of dissolved oxygen in the leachate is
attributed to the occurrence of sulfite or other oxidation processes when oxygenic water contacts with
coal ash (USEPA, 1980).
It is noted that dissolved oxygen occurs in groundwater through recharge by precipitation and air within
the unsaturated zone. Dissolved oxygen remains in groundwater until it is used by bacteria, organic
material, or reduced elements in minerals (Cunningham and Daniel, 2001). High dissolved oxygen
concentrations in groundwater may indicate relatively rapid groundwater recharge (Cunningham and
Daniel, 2001). The range of the dissolved oxygen concentrations observed in the local water supply
wells is within the range of dissolved oxygen concentrations found in similar geologic environments (i.e.,
fractured crystalline rocks mantled with weathered regolith in the Piedmont Physiographic Province) by
the USGS (Brief, 1997).
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There is some uncertainty associated with the dissolved oxygen concentrations observed in local water
supply wells and regional background wells. These concentration values may be less accurate because
the sampling protocol for these wells is not known and the dissolved oxygen measurements may be
affected by the interference from well and plumbing configurations that admit air to the sample water
(Donnahue and Kibler, 2007). Although the dissolved oxygen concentrations may be overestimated in
some cases, the trend of dissolved oxygen data collected from water supply wells have been used for
other studies to help understand the general geochemical conditions (Winograd and Robertson, 1982;
Cunningham and Daniel, 2001; Donnahue and Kibler, 2007).
The manganese concentration trends are opposite to that of dissolved oxygen. Based on the
site -specific geochemical evaluation, the ash basin porewater generally favors the presence of reduced
manganese (SynTerra, 2016), which is consistent with the low oxygen content. The box plot results are
consistent with manganese geochemical behavior in that manganese tends to form precipitates under
oxygenic conditions, and are removed from the groundwater. The trend of iron is not as clear as
manganese; nonetheless, the median value of the iron concentrations for the ash basin porewater is an
order of magnitude higher than those for the other facility monitoring, local water supply, and regional
background wells.
The lack of dissolved oxygen in the ash basin porewater may serve as a useful signature. If the
groundwater obtained by a local water supply well is primarily from the ash basins, it is expected that
the dissolved oxygen concentration would be low because there is no effective mass transfer process to
increase the dissolved oxygen concentration during groundwater transport in the deep overburden and
bedrock units. In contrast, reduced iron and manganese ions can be re -oxidized and form precipitates
when they migrate into an aquifer system containing mineral oxides. Dissolved oxygen is, thus,
considered to be a more useful signature constituent in comparison with iron and manganese.
G.5.4.2 Correlation Plot Evaluation
Boron, sulfate, and dissolved oxygen were identified to be the useful signature constituents to assess
the extent of the CCR-impacted groundwater. The spatial patterns of boron and sulfate concentrations
in wells were first evaluated using the boron and sulfate concentrations observed in the ash basin
monitoring, facility bedrock, and local water supply wells.
In this correlation plot evaluation, the boron and dissolved oxygen concentration pairs are grouped as
follows:
• Ash basin porewater wells;
• Water supply wells;
• Regional background wells; and
— Subgroup 1 (Downgradient): The bedrock wells are located beneath or hydraulically
downgradient of the ash basin system or groundwater flowing through these wells is
likely originated from the ash basin system. CCR-impacted groundwater is more likely to
impact these wells based on the understanding of the groundwater flow field at the site
(SynTerra, 2015a, 2015b).
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Appendix G — Roxboro
— Subgroup 2 (Side Gradient): These wells are located cross gradient of the ash basin
system or groundwater flowing through these wells is not likely to subsequently flow
beneath the footprint of the ash basin system. These wells are not expected to be
influenced by the ash basin groundwater.
— Subgroup 3 (Upgradient): Groundwater flowing through the bedrock wells in this
subgroup is expected to subsequently flow beneath the ash basin system. The locations
of the wells are likely upgradient of the CCR-impacted groundwater and thus the
groundwater therein would resemble background groundwater water quality.
The data obtained from the facility bedrock wells may help identify the potential groundwater chemistry
characteristics of a CCR-impacted bedrock well and help illustrate the spatial pattern of CCR-impacted
facility bedrock wells, which may be used to help assess the potential impacts to the local water supply
wells. It should be noted that the groundwater flow field at the site is very complicated, as shown in
Figure G5-6; therefore, the subgroups above were preliminarily constructed to facilitate data analysis.
A correlation plot of boron and sulfate concentrations is shown in Figure G5-7. Panel (a) shows the
correlation plot for the ash basin porewater wells and the facility downgradient bedrock wells. The
porewater wells are distinguished by elevated boron concentrations and relatively high sulfate
concentrations (> 100,000 micrograms per liter [µg/L]). Several facility downgradient bedrock well data
are clustered in the vicinity of the ash basin porewater well data, indicating that CCR impacts are
present in these wells. MW-01BR and ABMW-01BR exhibit elevated boron concentrations (> 100 µg/L),
but their sulfate concentrations are lower than typical sulfate concentrations in the porewater wells.
There is a cluster of facility downgradient bedrock wells at the boron concentration of 50 µg/L; in fact,
boron is not detected at the reporting limit of 50 µg/L in these wells, indicating that these downgradient
bedrock wells receive little CCR impacts. Panel (b) shows the data from the facility side gradient and
upgradient bedrock wells in addition to the data in Panel (a). Boron is not detected at the reporting
limit of 50 µg/L in the upgradient and side gradient wells, except for GMW-09 (68.2 µg/L).
Panel (c) shows the overlay of the data from the local water supply wells on the data in Panel (b). The
plot shows that the ash basin porewater data are clustered in Area 1 and the local water supply well
data are clustered in Area 2. It is noted that the upper boundary of Area 2 is set at 100,000 µg/L, which
is lower than the 50th percentile of the sulfate concentrations observed in the Piedmont Province by the
USGS (Brief, 1997). The variability of the sulfate concentrations in the local water supply wells is similar
to the range of the facility upgradient and side gradient bedrock wells. The data outside Area 1 and
Area 2 are labeled with their well names. Except RO-03 and GWM-09, all other wells (CW-01, CW-02D,
and MW-05BR) are facility downgradient bedrock wells, which are expected to be subject to some
degree of CCR impacts.
The high sulfate concentration (77,600 µg/L) in RO-03 is correlated with the high sulfate concentrations
in the nearby local water supply wells, including RO-02 (71,000 µg/L), RO-11 (31,100 µg/L), and RO-12
(71,800 µg/L). Because no elevated boron concentrations were found in these local water supply wells
(<50 µg/L in RO-02, <5 µg/L in RO-11, and 6.1 µg/L in RO-12), it is considered that the high sulfate
concentration in RO-03 is naturally occurring.
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Appendix G — Roxboro
The local water supply wells RO-04, RO-07, and RO-13 are located near the Unnamed Eastern Extension
Impoundment. The boron concentrations in these wells are all NDs with a reporting limit of 20 µg/L for
RO-04, and a reporting limit of 5 µg/L for RO-07 and RO-11. Therefore, the Unnamed Eastern Extension
Impoundment is not likely impacting the groundwater quality of the local water supply wells.
The sulfate concentration in GMW-09 appears to be very high. As mentioned in Section G.5.3, the
maximum sulfate concentration in each well was used as the representative concentration in the
correlation plot. The average sulfate concentration in GMW-09 is approximately 24,000 µg/L, which is
well within the range of the sulfate concentrations for the local water supply wells and for the facility
upgradient and side gradient bedrock wells. Because the high sulfate concentration in the boron versus
sulfate correlation plot is not representative, GMW-09 is probably not impacted by CCR.
Based on Figures G5-3 and Figure G5-5, boron and dissolved oxygen concentration may also be useful
indicators for CCR-impacted groundwater. The boron versus oxygen correlation plot is shown in
Figure G5-8. Panel (a) shows the correlation plot for the ash basin porewater wells and the facility
downgradient bedrock wells. The porewater wells are distinguished by elevated boron concentrations
and relatively low dissolved oxygen concentrations (< 2,000 µg/L).
The distribution of the facility downgradient bedrock wells is quite spread -out; however, there are
recognized patterns:
• The facility bedrock wells within the red -dashed -line box generally share the characteristics of
the ash basin porewater — elevated boron concentrations and low dissolved oxygen
concentrations. The bedrock groundwater at these locations is considered to be significantly
impacted by the ash basin porewater.
• The facility bedrock wells within the blue box are all NDs (< 50 µg/L) for boron, indicating that
CCR-impacted groundwater has little impacts on many of the bedrock wells either beneath or
downgradient of the ash basin system. As it will be shown below, the variability of dissolved
oxygen concentrations for these downgradient bedrock wells are within the variability observed
in other bedrock and local water supply wells.
The facility bedrock wells within the elongated ellipse show a noticeable deviation from other
data. These three wells show both boron detected above 100 µg/L and higher dissolved oxygen
concentrations (> 2,000 µg/L) in comparison with the ash basin porewater. The data suggest
that both CCR-impacted groundwater and background groundwater are present in these wells.
It is likely that the some fractures connected to these bedrock wells provide background
groundwater and some fractures allow CCR-impacted groundwater to flow through the wells.
The concentrations observed in these wells may be the result of mixing of these two sources of
groundwater into the wells.
Panel (b) shows the data from the facility side gradient and upgradient bedrock wells in addition to the
data in Panel (a). Except for GMW-09, these added wells have no boron detected above 50 µg/L and are
all clustered in the blue box, indicating little impacts from the ash basin porewater. The boron
concentration for GWM-09 on the correlation plot is the maximum boron concentration (68 µg/L)
measured in this well, which occurred in 2015; all three other samples collected from this well in 2015
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Appendix G — Roxboro
were below 50 µg/L. It is also noted that the variability of dissolved oxygen is similar to those of the
facility downgradient wells in the blue box. Since GMW-09 has a much higher dissolved oxygen
concentration than those observed in the ash basin porewater, the groundwater in this well is not likely
to be CCR-impacted groundwater.
Panel (c) shows the overlay of the data from the local water supply wells on the data in Panel (b). Most
of these added local water supply wells are distinguished by very low to non -detect levels of boron (< 5
µg/L) and a similar variability of dissolved oxygen concentrations. It should be noted that the boron was
not detected in local water supply wells, RO-02 (< 50 µg/L) and RO-04 (< 20 µg/L). The only detected
boron concentration that is above the general boron reporting limit for the facility bedrock wells
(50 µg/L) occurs in RO-03 (86 µg/L). The location of the local water supply well, RO-03, is shown in
Figure G5-9.
The RO-03 boron data plotted in Panel (c) of Figures G5-6 and G5-7 are from the first sample taken from
the well. The well was resampled later and the boron concentration was 8.7 µg/L. In two nearby facility
bedrock wells, MW-13BR and MW-10BR, the boron concentrations have been always below the
reporting limit of 50 µg/L and the boron concentrations in the nearby local water supply wells, RO-08
and RO-11, were below the reporting limit of 5 µg/L. Because the RO-03 resampling result is lower than
the facility -specific boron BTV value (50 µg/L) and regional BTV value (9 µg/L) (Table G.3-1) and because
no elevated boron concentration have been observed in the nearby bedrock monitoring and the local
water supply wells, RO-03 is not likely to be impacted by CCR.
It is noted that dissolved oxygen concentrations in two local water supply wells are already very low
(<1,000 µg/L), suggesting that uncertainty resulting from the interference from the sampling protocol or
well and plumbing configurations that admit air to the sample water is within 1,000 µg/L for these wells.
In summary, Panel (c) shows that the groundwater data are primarily clustered in two distinct areas.
Area 1 contains the data from the ash basin porewater wells and several of the facility downgradient
bedrock wells that receive significant impacts. Area 2 contains the data from most of the local water
supply wells and the facility bedrock wells showing no sign of CCR impacts. The very low boron
concentration found in RO-03 after re -sampling and the low boron concentrations observed in the
nearby facility bedrock and local water supply wells indicate that RO-03 has not likely been impacted by
CCR.
In summary, the results of the boron versus sulfate correlation plot are consistent with the results of the
boron versus dissolved oxygen correlation plot. By evaluating the boron, dissolved oxygen, and sulfate
concentrations concurrently with the data of the nearby monitoring and local water supply wells, it is
concluded that the CCR impacts are likely to occur only in the ash basin system footprint and in the
downgradient area. It should be noted that this correlation plot evaluation uses groundwater
concentration data under the influence of historic pumping of the local water supply wells.
The lack of elevated concentrations of CCR-related signatures in the local water supply wells and the
distinct discrepancy between the data patterns of the ash basin porewater wells and the local water
supply wells in the correlation plots indicate that the ash basin porewater is not the primary
groundwater source for the local water supply wells.
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Appendix G — Roxboro
G.5.4.3 Piper Plot
Two piper plots were created to evaluate the relative abundance patterns of major ions in the ash basin
porewater and in the facility downgradient bedrock wells. The results are shown in Figure G5-10. Panel
(a) shows the data for the ash basin porewater wells. The cation subplot shows that calcium is the
dominant cation in the porewater. The diamond subplot shows that the relative abundance of calcium
and magnesium in the porewater are larger than 75 percent. The anion subplot shows that the relative
abundance of chloride is generally less than 20 percent, and the relative abundance of sulfate is
generally larger than 50 percent.
Panel (b) shows the data for both the ash basin porewater wells and the facility downgradient bedrock
wells. As shown in the diamond and anion subplots, the data for many facility downgradient bedrock
wells are plot away from the data for the ash basin porewater wells, indicating different water
chemistry. The results are consistent with the results of the correlation plot evaluation, in which many
of the facility downgradient bedrock wells did not have detectable levels of boron. It is noted that the
blue circle on the anion subplot generally contains the facility downgradient bedrock wells that have low
concentrations or NDs for boron.
The piper plots for the local water supply, upgradient, and side gradient bedrock wells are provided in
Figure G5-11. Panel (a) of Figure G5-11 shows the data for the local water supply wells. As can be seen,
these well data plot generally close to each other. This indicates that the groundwater in the local water
supply wells has similar major ion characteristics. Moreover, the grouping pattern is different from the
ash basin -related wells in Figure G5-10. Panel (b) of Figure G5-11 shows the data for two subgroups of
the facility bedrock wells (upgradient and side gradient) on top of the data in Panel (a). When viewed
this way, it is clear that the upgradient and side gradient facility bedrock wells show similar major ion
characteristics to those of the local water supply wells.
Figure G5-12 shows a piper plot comparison between the local water supply well data and the regional
water quality data collected from Orange County, North Carolina by the USGS (Cunningham and Daniel,
2001). The similarity of the data clustering patterns in these two piper plots affirms that the
groundwater in local water supply wells generally represents the regional background conditions.
Figure G5-13 shows a side -by -side comparison of the ash basin related well data in Panel (a), and the
local water supply well related data in Panel (b). The apparent difference in groundwater characteristics
between the CCR-impacted wells and the local water supply wells is shown in their diamond subplots.
The area defined by the blue dotted lines in Panel (b) encloses almost all the local water supply well
data, but excludes the ash basin porewater data in Panel (a). The names of the wells near the blue
dotted lines are also shown in Panel (b); all of these wells have no detectable concentrations of boron (<
50 µg/L). It is noted that the major ion compositions in the local water supply well, RO-03, which
exhibits a slightly elevated boron concentration (86 µg/L), is also consistent with the ion compositions in
the other local water supply wells, indicating the major water source for the RO-03 is background
groundwater.
In summary, the piper plot evaluation indicates that the major ion characteristics in many of the facility
downgradient bedrock wells are substantially different from the ash basin porewater; therefore, the
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Evaluation of Water Supply Wells
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Appendix G — Roxboro
area of CCR-impacted groundwater in the bedrock unit beneath or downgradient of the ash basin
system is very limited. The evaluation also confirms that the major ion characteristics in the local water
supply wells are substantially different from the groundwater observed in the porewater wells, but
similar to the regional groundwater survey by the US Geological Survey. The overall results indicate that
the major source water for the local water supply wells is not CCR-impacted groundwater.
G.5.5 Conclusions
This evaluation has reached the following key conclusions:
The boron and sulfate concentrations in the ash basin porewater are considerably higher than
the maximum plausible boron concentration found in the local water supply wells. Because
boron and sulfate exhibit little sorption to mineral surfaces and are not expected to precipitate
or be degraded under the site geochemical conditions, they are considered to be the most
effective signature constituents among the coal ash related constituents for evaluating the
groundwater impacts from the ash basin system.
• The boron concentrations detected in many local water supply wells are very low (< 5 µg/L);
therefore, any water quality exceedance for these wells cannot be attributed to the impacts
from the ash basin porewater.
The CCR-impacted facility bedrock wells identified using the correlation and piper plots are
consistent with the knowledge of the groundwater flow field in the vicinity of the facility, as
described in Section G.4. The local water supply wells are generally upgradient or side gradient
of the ash basin system.
The evaluation uses groundwater concentration data under the influence of historic pumping of
the local water supply wells. The lack of elevated concentrations of CCR-related signatures in
most of the local water supply wells and the distinct discrepancy between the data patterns on
the correlation plots and piper plots indicate that the pumping of the local water supply wells is
not able to reverse the natural hydraulic gradient to the extent that can capture CCR-impacted
groundwater for the local water supply wells.
• The correlation and piper plots show very different clustering patterns for the ash basin
porewater wells and the local water supply wells. The source water for the local water supply
wells is not CCR-impacted groundwater.
• The Unnamed Eastern Extension Impoundment does not impact the groundwater quality of the
local water supply wells; boron was not detected in these wells.
• This evaluation has provided additional lines of evidence, using (1) the presence of CCR
signature constituents and (2) general major ion chemistry, to support the groundwater flow
and transport results presented in Section G.4.5.
• It is concluded that there is no connection between the CCR-impacted groundwater and the
water quality exceedances found in the local water supply wells.
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Appendix G — Roxboro
G.6 SUMMARY
This document presents the results of supplemental technical evaluations in four important assessment
areas to determine whether or not the water supply wells located within a 1,500-foot radius of the
Roxboro ash basins compliance boundary could be impacted by CCR releases from the ash basins. The
evaluations in this document are based on the currently available data, which includes: generally one
sampling round from the water supply wells (note some wells had one or more re -analyses), three to
four sampling rounds from the ash basin wells, and multiple years of compliance well sampling. The
conclusion from the detailed weight of evidence demonstrates that water supply wells in the vicinity of
the Roxboro facility are not impacted by CCR releases from the ash basin.
The evaluation of the private and public water supply well data collected by NCDEQ and the detailed
statistical analysis of regional background groundwater data indicate that constituent concentrations in
the water supply wells are generally consistent with background. Boron was detected infrequently (2 of
15 samples) in the NCDEQ sampled water supply wells, as well as in the Duke Energy background wells
(2 of 26 samples). pH was below the drinking water standard range in 5 of the 15 NCDEQ-sampled
water supply wells; this is consistent with literature on the pH of groundwater in North Carolina (Brief,
1997; Chapman, et al., 2013). Lead was below the drinking water standard in 14 of the 15 NCDEQ-
sampled water supply wells. The NCDEQ-sampled water supply well results were below Federal primary
drinking water standards (MCLs), with the exception of the few pH results and lead result noted above,
and one well with chloride and TDC above their SMCLs. Approximately a third of the manganese and
iron results were above the SMCL, as were 1 of the results for sulfate, TDS, and aluminum; however, the
SMCLs are based on aesthetics. Moreover, the aluminum, manganese, and iron results for the NCDEQ-
sampled water supply wells were within the range of concentrations from the Duke Energy background
wells.
The comprehensive evaluation of groundwater flow with respect to local water supply wells
demonstrates that groundwater flow is to the north toward Hyco Lake from the topographic divides
south of the ash basin system, away from where the water supply wells are located. The water supply
well capture zone analysis indicates that groundwater utilized by water supply wells near the coal ash
impoundments is not impacted by the coal ash sources.
This conclusion is confirmed by the detailed characterization of groundwater chemistry including
evaluation of CCR indicators, redox conditions, and correlation evaluations. The results of the chemical
correlation analyses indicate that, based on the different constituent clustering patterns from the ash
basin porewater wells and the water supply wells, the source water for the water supply wells is not
CCR-impacted groundwater. Coal ash constituents do not measurably increase the density of
groundwater or have a separate liquid phase in groundwater as compared to other dense liquids that
would "sink" in the aquifer, like saltwater. Thus, releases from coal ash management areas tend to
remain in the shallower groundwater flow layers.
Based on this combined weight of evidence, groundwater utilized by water supply wells near the coal
ash impoundments is not impacted by the coal ash sources. These results indicate that a Low
classification for the Roxboro Steam Electric Plant under the CAMA is warranted.
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Appendix G - Roxboro
G.7 REFERENCES
1. Briel, L.I. 1997. Water quality in the Appalachian Valley and Ridge, the Blue Ridge, and the
Piedmont physiographic provinces, eastern United States (Professional Paper No. 1422-D). U.S.
Geological Survey.
2. CAMA. 2014. North Carolina Coal Ash Management Act. Senate Bill S729v7. Available at:
http://www.ncleg.net/Sessions/2013/Bills/Senate/PDF/S729v7.PDF
3. Chapman, M.J., Cravotta III, C.A., Szabo, Z. and Lindsay, B.D. 2013. Naturally occurring
contaminants in the Piedmont and Blue Ridge crystalline -rock aquifers and Piedmont Early
Mesozoic basin siliciclastic-rock aquifers, eastern United States, 1994-2008 (Scientific
Investigations Report No. 2013-5072). U.S. Geological Survey.
4. Cunningham, W.L. and Daniel, C.C. 2001. Investigation of Ground -Water Availability and Quality
in Orange County, North Carolina (Water Resources Investigation No. 4286). US Department of
the Interior, U.S. Geological Survey.
5. Daniel, C.C. III and Dahlen, P. 2002. Preliminary Hydrogeologic Assessment and Study Plan for a
Regional Ground -Water Resource Investigation of the Blue Ridge and Piedmont Provinces of
North Carolina. USGS Water Resources Investigation Report 02-4105.
6. Daniel, C.C., III and Harned, D.A. 1998. Ground -water recharge to and storage in the regolith-
fractured crystalline rock aquifer system, Guilford County, North Carolina: U.S. Geological
Survey Water -Resources Investigations Report 97-4140, 65p.
7. Domenico, P.A. and Schwartz, F.W. 1998. Physical and chemical hydrogeology (Vol. 44). New
York: Wiley.
8. Donnahue, J.C. and Kibler, S.R. 2007. Ground Water Quality in Piedmont/Blue Ridge Unconfined
Aquifer System of Georgia, Georgia Department of Natural Resources, Environmental Protection
Division, Watershed protection branch, regulatory support program, Circular 12U, Atlanta.
9. EPRI. 2005. Chemical Constituents in Coal Combustion Product Leachate: Boron. Electric Power
Research Institute Report 1005258. March 2005.
10. Freeze, R.A. and Cherry, J.A. 1979. Groundwater, Englewood Cliffs, NJ, Prentice -Hall.
11. Grubb, S. 1993. Analytical Model for Estimation of Steady -State Capture Zones of Pumping
Wells in Confined and Unconfined Aquifers. Ground Water, Vol. 31, No. 1, January -February
1993.
12. Haley & Aldrich. 2015. Evaluation of NCDEQ Private Well Data. December 2015.
APRIL 2016 40 %UICH

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
13. Harned, D.A. 1989. The Hydrogeologic Framework and a Reconnaissance of Ground -Water
Quality in the Piedmont Province of North Carolina, with a Design for Future Study (Water -
Resources Investigations Report 88-4130, 55p.). U.S. Geological Survey.
14. Harned, D.A. and Daniel, C.C., III. 1992. The transition zone between bedrock and regolith:
Conduit for contamination?, p. 336-348, in Daniel, C. C., III, White, R. K., and Stone, P. A., eds.,
Groundwater in the Piedmont: Proceedings of a Conference on Ground Water in the Piedmont
of the Eastern United States, October 16-18, 1989, Clemson University, 693p.
15. Heath, R.C. 1980. Basic elements of groundwater hydrology with reference to conditions in
North Carolina (Open File Report 80-44, 86p.). U.S. Geological Survey.
16. LeGrand, H.E. 1988. Region 21, Piedmont and Blue Ridge. In Hydrogeology, The Geology of
North America, vol. 0-2, ed. W.B. Back, J.S. Rosenshein, and P.R. Seaber, 201-207. Geological
Society of America. Boulder CO: Geological Society of America.
17. LeGrand, H.E. 1989. A conceptual model of ground water settings in the Piedmont region. In
Ground Water in the Piedmont, ed. C.C. Daniel III, R.K. White, and P.A. Stone, 693. Proceedings
of a Conference on Ground Water in the Piedmont of the Eastern United States, Clemson
University, Clemson, South Carolina. Charlotte, NC: U.S. Geological Survey.
18. LeGrand, H.E. 2004. A Master Conceptual Model for Hydrogeological Site Characterization in
the Piedmont and Mountain Region of North Carolina, A Guidance Manual, North Carolina
Department of Environment and Natural Resources Division of Water Quality, Groundwater
Section.
19. NCAC. 2013. 15A NCAC 02L.0202. Groundwater Standard (2L), Classifications and Water
Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative
Code. April 1, 2013. Available at:
http://Portal.ncdenr.org/c/document library/get file?uuid=laa3fa13-2cOf-45b7-ae96-
5427fb1d25b4&groupld=38364
20. NCDHHS. 2015. DHHS Screening Levels. Department of Health and Human Services, Division of
Public Health, Epidemiology Section, Occupational and Environmental Epidemiology
Branch. April 24, 2015. Available at:
http://Portal.ncdenr.org/c/document library/get file?p I id=1169848&folderld=24814087&na
me=DLFE-112704.PDF
21. NCDEQ. 2016. Coal Combustion Residual Impoundment Risk Classifications. North Carolina
Department of Environmental Quality. January 2016. Available at:
https://ncdenr.s3.amazonaws.com/s3fs-public/document-
library/1.29.16 Coal%20Combustion%20Residual%201mpoundment%20CIassifications.pdf
22. SynTerra. 2014a. Roxboro Steam Electric Plant — Ash Basin Drinking Water Supply Well and
Receptor, Survey. SynTerra Corporation. [Online] URL:
http://portal.ncdenr.org/web/wq/drinking-water-receptor-surveys
APRIL 2016 41 %UICH

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G - Roxboro
23. SynTerra. 2014b. Roxboro Steam Electric Plant - Ash Basin Supplement to Drinking Water
Supply Well and Receptor Survey. SynTerra Corporation. [Online] URL:
http://portal.ncdenr.org/web/wq/drinking-water-receptorsurveys
24. SynTerra. 2014c. Roxboro Steam Electric Plant, Proposed Groundwater Assessment Work Plan.
SynTerra Corporation.
25. SynTerra. 2015a. Comprehensive Site Assessment Report, Roxboro Steam Electric
Plant, September 2, 2015. SynTerra Corporation.
26. SynTerra. 2015b. Corrective Action Plan Part 1. Roxboro Steam Electric Plant, December 2016.
SynTerra Corporation.
27. SynTerra. 2016. Corrective Action Plan Part 2. Roxboro Steam Electric Plant, February 29, 2016.
SynTerra Corporation.
28. USEPA. 1980. Effects of Coal -ash Leachate on Ground Water Quality. U.S. Environmental
Protection Agency. EPA-600/7-80-066. March.
29. USEPA. 2008. Indoor Water Use in the United States., EPA Water Sense., U.S. Environmental
Protection Agency. [Online] URL: https://www3.epa.gov/watersense/docs/ws indoor508.pdf.
30. USEPA. 2012. 2012 Edition of the Drinking Water Standards and Health Advisories. Spring
2012. U.S. Environmental Protection Agency. Available at:
http://water.epa.gov/drink/contaminants/index.cfm
31. USEPA. 2013. Statistical Software ProUCL 5.0.00 for Environmental Applications for Data Sets
with and without Nondetect Observations. U.S. Environmental Protection Agency. Software:
http://www2.epa.gov/land-research/proucl-software, and User's Guide:
https://www.epa.gov/sites/production/files/2015-03/documents/proucl v5.0 tech.pdf
32. USEPA. 2015a. Coal Combustion Residual (CCR) Rule (Hazardous and Solid Waste Management
System; Disposal of Coal Combustion Residuals From Electric Utilities; FR 80(74): 21302-
21501, April 19, 2015. U.S. Environmental Protection Agency. Available at:
http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/PDF/2015-00257.PDF
33. USEPA. 2015b. USEPA Regional Screening Levels (RSLs). November 2015. U.S. Environmental
Protection Agency. Available at: http://www.epa.gov/reg3hwmd/risk/human/rb-
concentration table/Generic Tables/index.htm
34. Winograd, I.J. and Robertson, F.N. 1982. Deep oxygenated ground water: anomaly or common
occurrence? Science, 216(4551), pp.1227-1230.
35. Winston, R.B. 2000. Graphical User Interface for MODFLOW, Version 4 (Open -File Report 00-
315). U.S. Geological Survey. Software:
http://water.usgs.gov/nrp/gwsoftware/GW Chart/GW Chart.html
APRIL 2016 42 %UICH

Table G2-1
Comparison of NCDEQ Water Supply Well Data to 2L Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Page 1 of 3
15A NCAC 0ard(a): Groundwater Standard (a)
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
NS
20
0.2
Federal M L(b):
(• denotes secondary standard)
NS
N5
•250
6.5-8.5
•250
•500
6
10
2000
4
5
100
NS
15
2
NS
50
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
1 L
18
20
0.2
RSL 2015(d):
4000
NS
NS
NS
NS
NS
7.8
0.052
3800
25
9.2
22000
6
15
5.7
100
100
0.2
Appendix
III
Appendix
IV
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
Molybdenum
Selenium
Thallium
Plant
Well Owner ID
u L
u L
m L
su
m L
m L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
Roxboro
R01
< 50
83000
41
6.91
51
405
< 3
< 2
3.62
< 1
< 0.5
< 10
< 5
1.73
< 0.2
< 10
2.39
< 1
Roxboro
RO10
<100
<1000
230
7.1
24
<5
<5
<100
<3
<1
<10
<10
<5
<0.5
<10
<5
<2
Roxboro
RO10-1
< 50
150000
335
7.2
26
999
< 5
< 5
300
< 2
< 0.8
< S
< 5
< 1
< 0.2
< 5
< 5
< 1
Roxboro
RO10-2
<50
83000
37
7.1
36
369
<5
<5
119
<2
<0.8
<5
<S
1.7
<0.2
<5
<5
<1
Roxboro
RO11
<5
43800
31.2
6.4
31.1
326
<0.5
<0.5
125
<0.2
<0.08
1.7
<0.5
2.3
<0.2
2
<0.5
<0.1
Roxboro
RO12
6.1
84200
26.7
6.82
71.8
463
<0.5
<0.5
67.1
<0.2
<0.08
<0.5
<0.5
0.24
<0.2
5.9
<0.5
<0.1
Roxboro
RO13
<5
14700
8.4
5.98
2.6
138
<0.5
<0.5
30.9
<0.2
<0.08
1.3
<0.5
1.3
<0.2
<0.5
<0.5
<0.1
Roxboro
RO14
<5
74000
31
7.07
52.3
382
<0.5
<0.5
48.6
<0.2
<0.08
<0.5
<0.5
0.76
<0.2
0.52
1.1
<0.1
Roxboro
R015
<5
50700
44.5
7
47.1
456
<0.5
<0.5
59
<0.2
<0.08
1.3
<0.5
0.64
<0.2
4.2
<0.5
<0.1
Roxboro
RO16
< 5
15100
7.8
6.05
19.2
175
< 0.5
< 0.5
18.7
< 0.2
< 0.08
1.4
< 0.5
0.56
< 0.2
< 0.5
< 0.5
< 0.1
Roxboro
RO2
<50
50700
24
6.63
71
383
<5
<5
64.4
<2
<0.8
<5
<5
1.8
<0.2
<S
<S
<1
Roxboro
RO3
86
66200
47
6.34
77.6
465
< 0.5
< 0.5
79.1
< 0.2
0.072
< 0.5
'0.5
0.44
< 0.2
2.5
< 0.5
< 0.1
Roxboro
RO4
<20
47800
17
6.77
7
267
<0.4
0.2
66.1
<0.11
<0.06
2.69
0.25
0.43
<0.01
0.38
0.51
<0.06
Roxboro
RO7
<5
30000
19.4
6.18
7.1
200
<0.5
<0.5
67.8
<0.2
<0.08
6.2
<0.5
0.25
<0.2
<0.5
<0.5
<0.1
Roxboro
RO8
<5
59700
44.2
6.69
29.3
1 366
<0.5
<0.5
54.3
<0.2
<0.08
0.6
<0.5
40.3
<0.2
0.76
<0.5
<0.1
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx 2L April 2016

Table G2-1
Comparison of NCDEQ Water Supply Well Data to 2L Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1SA NCAC 02L .020
Groundwater Standard (a):
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1
NS
NS
NS
NS
Federal MCL/SMCL (b):
(* denotes secondary standard)
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5
NS
NS
NS
NS
DHHS Screening Level (c):
0.3
3500
1
2500
0.07
NS
200
100
NS
20000
2100
1
NS
NS
NS
NS
RSL 2015(d):
86
20000
0.8
14000
44(e)
NS
430
390
NS
NS
12000
6
NS
NS
NS
NS
Constituents Not Identified
in the CCR
Rule
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Plant
Well Owner ID
u L
u L
m L
u L
u L
u L
u L
u L
u L
u L
u L
m L
m L
m L
m L
m L
Roxboro
R01
2.84
< 50
< 0.002
< 50
< 20
34000
8.29
< 2
1800
25000
410
0.0147
274
274
< 1
< 5
Roxboro
RO10
< 10
< 10
< 0.05
< 100
< 1000
< 30
< 10
< 1000
370000
< 50
< 0.05
376
Roxboro
RO10-1
< 10
< 10
< 0.01
200
0.062
61200
1010
< 5
6800
59800
936
< 0.05
268
259
< 5
< 2.5
Roxboro
RO10-2
<10
155
<0.01
1280
<0.03
26000
920
<5
4390
32000
331
<0.05
271
214
<5
7.8
Roxboro
RO11
10.6
< 10
0.0195
< 50
1.2
25700
1.5
0.56
1 3540
25300
1 236
0.0363
196
1 196
< 5
< 2.5
Roxboro
RO12
< 1
< 10
0.0013
1100
< 0.03
28200
494
< 0.5
5900
36500
326
0.0122
286
286
< 5
< 2.5
Roxboro
RO13
3.1
< 10
0.0932
< 50
0.92
5250
3.7
< 0.5
1240
9990
166
0.0511
63.3
63.3
< 5
< 2.5
Roxboro
RO14
5.6
<10
0.0076
827
<0.03
27000
5.9
<0.5
6640
16500
244
0.0299
241
241
<5
<2.6
Roxboro
RO15
16.1
12.7
0.0134
< 50
0.83
41300
0.62
0.61
3610
64700
190
0.243
317
317
< 5
< 2.5
Roxboro
RO16
5.5
<10
0.0078
<50
1.2
4240
0.98
1.4
1780
17200
121
0.0289
52.2
52.2
<5
<2.5
Roxboro
RO2
< 10
< 100
0.0391
< 500
0.11
25100
< S
< 5
3500
34000
191
0.0874
204
204
< 5
5.1
Roxboro
RO3
2.8
< 10
0.0228
< 50
0.17
26200
< 0.5
1.3
5260
34000
206
0.0452
203
203
< 5
< 2.5
Roxboro
RO4
1.38
<10
0.00227
221
2.69
10800
144
1.35
E710
16400
260
0.0196
164
<2.5
Roxboro
RO7
5.9
< 10
0.0101
53.8
0.57
10700
29.4
1.9
1960
16300
268
0.0407
111
111
< 5
< 2.5
Roxboro
ROB
5.2
<10
0.0254
1 <50
0.28
22400
1.9
<0.5
4310
19600
255
0.0414
178
178
<5
<2.5
Page 2 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx 2L April 2016

Table G2-1
Comparison of NCDEQ Water Supply Well Data to 2L Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1SA NCAC 02L .020
Groundwater Standard (a):
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
(• denotes secondary standard)
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
RSL 2015(d):
NS
NS
NS
NS
NS
Constituents
Not Identified in
the CCR Rule
Plant
Well Owner ID
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
NTU
°C
umhos cm
m L
my
Roxboro
R01
< 1
16.6
505
4.01
Roxboro
R010
Roxboro
RO10-1
1.5
21.8
184.2
3.8
205.3
Roxboro
R010-2
6.2
19.2
631
0.61
219.2
Roxboro
RO11
< 1
22.7
470.1
3.42
172.4
Roxboro
RO12
8.9
21.3
662
0.89
<
Roxboro
RO13
< 1
23.1
145.1
5.07
193.3
Roxboro
RO14
7.4
23.6
647
0.95
<
Roxboro
RO15
< 1
18.4
799
2.14
176.7
Roxboro
RO16
< 1
17.2
188.4
2.4
191
Roxboro
RO2
< 1
17.2
640
5.1
259.3
Roxboro
RO3
0.15
20.2
692
5.4
181.5
Roxboro
RO4
< 1
12.9
400
4.72
Roxboro
RO7
< 1
22.3
260.5
4.12
180.5
Roxboro
ROB
< 1
21.6
594.2
3.3
257.7
Page 3 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx 2L April 2016

Comparison of NCDEQ Water Supply Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
A - Denotes IMAC value.
* - Denotes SMCL value.
°C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC- Interim Maximum Allowable Concentration.
MCL - Maximum Contaminant Level.
MDL - Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA - Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL- Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
so -standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
B Detected in method blank (MB).
1 Estimated result between PQL and MDL.
12 Spike recovery outside quality assurance limits @ 135%.
Zb Sample was clear but contained sand -like particles.
Zc Well depth was 635 feet per well tag.
18 Temperature of the sample was exceeded during storage.
BH Method Blank (MB) greater than one half of the Reporting Level (RL), but the sample concentrations are greater than 10x the MB.
** Alkalinity = carbonate + bicarbonate.
S1 Matrix spike and / or matrix spike duplicate sample recovery was not within control limits due to matrix interference. Laboratory Control Sample (LCS) was within control limits.
Z Sample was re -digested and re -analyzed with similar sample and spike results.
M1 Matrix spike recovery exceeded QC limits. Batch accepted based on laboratory control sample (LCS) recovery.
D6 The relative percent difference (RPD) between the sample and sample duplicate exceeded laboratory control limits.
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards2012.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screening-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http://epa-prgs.orni.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) -The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value is above the sreening level.
Reporting limit is above the screening level.
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx 4/10/2016

Table G2-2
Comparison of NCDEQ Water Supply Well Data to MCL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
water. 02L.020
Groundwater Standard a:
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
NS
20
0.2
Federal MCL/SMCL (b):
*' standard)NS
denotes seconds
NS
*250
6.5-8.5
*250
*500
6
10
2000
4
5
100
NS
15
2
NS
50
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
1 L
18
20
0.2
RSL 2015 (d):
4000
NS
NS
NS
NS
NS
7.8
0.052
3800
25
9.2
22000
6
15
5.7
100
100
0.2
Appendix
III
Appendix
IV
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
Molybdenum
Selenium
Thallium
Plant
Well Owner ID
u L
u L
m L
su
m L
m L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
Roxboro
ROl
<50
83000
41
6.91
51
405
<3
<2
3.62
<1
<0.5
<10
<5
1.73
c0.2
<10
2.39
<1
Roxboro
R010
<100
<1000
230
7.1
24
<5
<5
<100
<3
<1
<10
<10
<5
<0.5
<10
<5
<2
Roxboro
R010-1
<50
150000
335
7.2
26
999
<5
<5
300
<2
<0.8
<5
<5
<1
<0.2
<5
<5
<1
Roxboro
R010-2
<50
83000
37
7.1
36
369
<5
<5
119
<2
<0.8
<5
<5
1.7
<0.2
<5
<5
<1
Roxboro
R011
<5
43800
31.2
6.4
31.1
326
<0.5
<0.5
125
<0.2
<0.08
1.7
<0.5
2.3
<0.2
2
<0.5
<0.1
Roxboro
R012
6.1
84200
26.7
6.82
71.8
463
<0.5
<0.5
67.1
<0.2
<0.08
<0.5
<0.5
0.24
<0.2
5.9
<0.5
<0.1
Roxboro
R013
<5
14700
8.4
5.98
2.6
138
<0.5
<0.5
30.9
<0.2
<0.08
1.3
<0.5
1.3
<0.2
<0.s
<0.5
<0.1
Roxboro
R014
<5
74000
31
7.07
52.3
382
<0.5
<0.5
48.6
<0.2
<0.08
<0.5
<0.5
0.76
<0.2
0.52
1.1
<0.1
Roxboro
R015
<5
50700
44.5
7
47.1
456
<0.5
<0.5
59
<0.2
<0.08
1.3
<0.5
0.64
<0.2
4.2
<0.5
<0.1
Roxboro
R016
<5
15100
7.8
6.05
19.2
175
<0.5
<0.5
18.7
<0.2
<0.08
1.4
<0.5
0.56
<0.2
<0.5
<0.5
<0.1
Roxboro
R02
<50
50700
24
6.63
71
383
<5
<5
64.4
<2
<0.8
<5
<5
1.8
<0.2
<5
<5
<1
Roxboro
R03
86
66200
47
6.34
77.6
465
<0.5
<0.5
79.1
<0.2
0.072
<0.5
<0.5
0.44
<0.2
2.5
<0.5
<0.1
Roxboro
R04
<20
47800
17
6.77
7
267
<0.4
0.2
66.1
<0.11
<0.06
2.69
0.25
0.43
<0.01
0.38
0.51
<0.06
Roxboro
R07
<5
30000
19.4
6.18
7.1
200
<0.5
<0.5
67.8
<0.2
<0.08
6.2
<0.5
0.25
<0.2
<0.5
<0.5
<0.1
Roxboro
R08
<5
59700
44.2
6.69
29.3
366
<0.5
<0.5
54.3
<0.2
<0.08
0.6
<0.5
40.3
<0.2
0.76
<0.5
<0.1
Page 1 of 2
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx MCL April 2016

Table GZ-2
Comparison of NCDEQ Water Supply Well Data to MCL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Page 2 of 2
15AN.".nd..020
Groundwater Standard a:
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1
NS
NS
NS
NS
NS
NS
NS
NS
N5
Federal MCL/SMCL(b):
* denotes secondary standard
NS
•50 to 200
1.3
"300
NS
NS
*50
NS
NS
NS
NS
*S
NS
NS
NS
NS
NS
NS
N5
NS
N5
DHHS Screening Level (c):
0.3
3500
1
2500
0.07
NS
200
100
NS
20000
2100
1
NS
NS
NS
NS
NS
NS
NS
NS
NS
RSL 2015(d):
86
20000
0.8
14000
44(e)
NS
430
390
NS
NS
12000
6
NS
NS
NS
NS
NS
NS
NS
NS
NS
Constituents
Not Identified
in the OCR
Rule
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
Plant
Well Owner ID
u L
u L
m L
u L
u L
u L
u L
u L
u L
u L
u L
m L
.91L
m L
m L
m L
NTU
'C
umhos cm
m L
mV
Roxboro
R01
2.84
< 50
< 0.002
< 50
< 20
34000
8.29
< 2
1800
25000
410
0.0147
274
274
< 1
< 5
< 1
16.6
505
4.01
Roxboro
RO10
'10
<10
< 0.05
< 100
< 1000
< 30
< 10
< 1000
370000
< 50
< 0.05
376
Roxboro
R010-1
<10
<10
<0.01
200
0.062
61200
1010
<5
6800
59800
936
<0.05
268
259
<5
<2.5
1.5
21.8
184.2
3.8
2053
Roxboro
R010-2
<10
155
<0.01
1280
<0.03
26000
920
<5
4390
32000
331
<0.05
271
214
<5
7.8
6.2
19.2
631
0.61
219.2
Roxboro
R011
10.6
<10
0.0195
< 50
1.2
25700
1.5
0.56
3540
25300
236
0.0363
196
196
<5
< 2.5
< 1
22.7
1 470.1
3.42
172.4
Roxboro
RO12
< 1
<10
0.0013
1100
< 0.03
28200
494
< 0.5
5900
36500
326
0.0122
286
286
<5
< 2.5
8.9
21.3
662
0.89
<
Roxboro
RO13
3.1
<10
0.0932
<50
0.92
5250
3.7
<0.5
1240
9990
166
0.0511
63.3
63.3
<5
<2.5
<1
23.1
145.1
5.07
193.3
Roxboro
RO14
5.6
<10
0.0076
827
<0.03
27000
5.9
<0.5
6640
16500
244
0.0299
241
241
<5
<2.6
7.4
23.6
647
0.95
<
Roxboro
RO15
16.1
12.7
0.0134
< 50
0.83
41300
0.62
0.61
3610
64700
190
0.243
317
317
< 5
< 2.5
< 1
18.4
799
2.14
176.7
Roxboro
RO16
5.5
< 10
0.0078
< 50
1.2
4240
0.98
1.4
1780
17200
121
0.0289
52.2
52.2
<5
< 2.5
< 1
17.2
188.4
2.4
191
Roxboro
R02
.10
< 100
0.0391
< 500
0.11
25100
< 5
< 5
3500
34000
191
0.0874
204
204
<5
5.1
< 1
17.2
640
5.1
259.3
Roxboro
R03
2.8
<10
0.0228
<50
0.17
26200
<0.5
1.3
5260
34000
206
0.0452
203
203
<5
<2.5
0.15
20.2
692
5.4
181.5
Roxboro
R04
1.38
< 10
0.00227
228
2.69
10800
144
1.35
2750
16400
260
0.0196
164
< 2.5
< 1
12.9
400
4.72
Roxboro
R07
5.9
<10
0.0101
53.8
0.57
10700
29.4
1.9
1960
16300
268
0.0407
ill
ill
<5
<2.5
<1
22.3
260.5
4.12
180.5
Roxboro
R08
5.2
<10
0.0254
<50
1 0.28
1 22400
1.9
<0.5
4310
19600
255
0.0414
1 178
1 178
1 <5
<2.5
<1
21.6
594.2
3.3
257.7
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx MCL April 2016

Comparison of NCDEQ Water Supply Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
A - Denotes IMAC value.
* - Denotes SMCL value.
°C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC- Interim Maximum Allowable Concentration.
MCL - Maximum Contaminant Level.
MDL - Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA - Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL- Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su -standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
B Detected in method blank (MB).
1 Estimated result between PQL and MDL.
12 Spike recovery outside quality assurance limits @ 135%.
Zb Sample was clear but contained sand -like particles.
Zc Well depth was 635 feet per well tag.
18 Temperature of the sample was exceeded during storage.
BH Method Blank (MB) greater than one half of the Reporting Level (RL), but the sample concentrations are greater than 10x the MB.
** Alkalinity = carbonate + bicarbonate.
S1 Matrix spike and / or matrix spike duplicate sample recovery was not within control limits due to matrix interference. Laboratory Control Sample (LCS) was within control limits.
Z Sample was re -digested and re -analyzed with similar sample and spike results.
M1 Matrix spike recovery exceeded QC limits. Batch accepted based on laboratory control sample (LCS) recovery.
D6 The relative percent difference (RPD) between the sample and sample duplicate exceeded laboratory control limits.
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards2012.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screening-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http://epa-prgs.orni.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) -The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value is above the sreening level.
Reporting limit is above the screening level.
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx 4/10/2016

Table G2-3
Comparison of NCDEQ Water Supply Well Data to DHHS Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Page 1 of 3
15A NCAC 02L.0202
d(a): Groundwater Standard (a)
700
NS
250
6.5-8.5
250
S00
1
10
700
4
2
10
1
1s
1
NS
20
0.2
Federal MCL/SMCL(b):
(• denotes secondary standard)
NS
NS
*250
6.5-8.5
*250
*500
6
10
2000
4
5
100
NS
1s
2
NS
50
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
30
1
1s
1 L
18
20
0.2
RSL 2015(d):
4000
NS
NS
NS
NS
NS
7.8
0.052
3800
25
9.2
22000
6
is
5.7
100
100
0.2
Appendix
III
Appendix
IV
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
Molybdenum
Selenium
Thallium
Plant
Well Owner ID
u L
u L
m L
su
m L
m L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
Roxboro
R01
< 50
83000
41
6.91
51
405
< 3
< 2
3.62
< 1
< 0.5
< 10
< 5
1.73
< 0.2
< 10
2.39
< 1
Roxboro
RO10
<100
<1000
230
7.1
24
<5
<5
<100
<3
<1
<10
<10
<5
<0.5
<10
<5
<2
Roxboro
RO10-1
< 50
150000
335
7.2
26
999
< 5
< 5
300
< 2
< 0.8
< S
< 5
< 1
< 0.2
< 5
< 5
< 1
Roxboro
RO10-2
<50
83000
37
7.1
36
369
<5
<5
119
<2
<0.8
<5
<S
1.7
<0.2
<5
<5
<1
Roxboro
RO11
<5
43800
31.2
6.4
31.1
326
<0.5
<0.5
125
<0.2
<0.08
1.7
<0.5
2.3
<0.2
2
<0.5
<0.1
Roxboro
RO12
6.1
84200
26.7
6.82
71.8
463
<0.5
<0.5
67.1
<0.2
<0.08
<0.5
<0.5
0.24
<0.2
5.9
<0.5
<0.1
Roxboro
RO13
<5
14700
8.4
5.98
2.6
138
<0.5
<0.5
30.9
<0.2
<0.08
1.3
<0.5
1.3
<0.2
<0.5
<0.5
<0.1
Roxboro
RO14
<5
74000
31
7.07
52.3
382
<0.5
<0.5
48.6
<0.2
<0.08
<0.5
<0.5
0.76
<0.2
0.52
1.1
<0.1
Roxboro
R015
<5
50700
44.5
7
47.1
456
<0.5
<0.5
59
<0.2
<0.08
1.3
<0.5
0.64
<0.2
4.2
<0.5
<0.1
Roxboro
RO16
< 5
15100
7.8
6.05
19.2
175
< 0.5
< 0.5
18.7
< 0.2
< 0.08
1.4
< 0.5
0.56
< 0.2
< 0.5
< 0.5
< 0.1
Roxboro
RO2
<50
50700
24
6.63
71
383
<5
<5
64.4
<2
<0.8
<5
<5
1.8
<0.2
<S
<S
<1
Roxboro
RO3
86
66200
47
6.34
77.6
465
< 0.5
< 0.5
79.1
< 0.2
0.072
< 0.5
'0.5
0.44
< 0.2
2.5
< 0.5
< 0.1
Roxboro
RO4
<20
47800
17
6.77
7
267
<0.4
0.2
66.1
<0.11
<0.06
2.69
0.25
0.43
<0.01
0.38
0.51
<0.06
Roxboro
RO7
<5
30000
19.4
6.18
7.1
200
<0.5
<0.5
67.8
<0.2
<0.08
6.2
<0.5
0.25
<0.2
<0.5
<0.5
<0.1
Roxboro
RO8
<5
59700
44.2
6.69
29.3
1 366
<0.5
<0.5
54.3
<0.2
<0.08
0.6
<0.5
40.3
<0.2
0.76
<0.5
<0.1
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx DHHS April 2016

Table G2-3
Comparison of NCDEQ Water Supply Well Data to DHHS Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L .020
Groundwater Standard (a):
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1
NS
NS
NS
NS
Federal MCL/SMCL (b):
(• denotes secondary standard)
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5
NS
NS
NS
NS
DHHS Screening Level (c):
0.3
3500
1
2500
0.07
NS
200
100
NS
20000
2100
1
NS
NS
NS
NS
RSL 2015(d):
86
20000
0.8
14000
44(e)
NS
430
390
NS
NS
12000
6
NS
NS
NS
NS
Constituents Not Identified
in the CCR
Rule
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Plant
Well Owner ID
u L
u L
m L
u L
u L
u L
u L
u L
u L
u L
u L
m L
m L
m L
m L
m L
Roxboro
R01
2.84
< 50
< 0.002
< 50
< 20
34000
8.29
< 2
1800
25000
410
0.0147
274
274
< 1
< 5
Roxboro
RO10
< 10
< 10
< 0.05
< 100
< 1000
< 30
< 10
< 1000
370000
< 50
< 0.05
376
Roxboro
RO10-1
< 10
< 10
< 0.01
200
0.062
61200
1010
< 5
6800
59800
936
< 0.05
268
259
< 5
< 2.5
Roxboro
RO10-2
<10
155
<0.01
1280
<0.03
26000
920
<5
4390
32000
331
<0.05
271
214
<5
7.8
Roxboro
RO11
10.6
< 10
0.0195
< 50
1.2
25700
1.5
0.56
1 3540
25300
1 236
0.0363
196
1 196
< 5
< 2.5
Roxboro
RO12
< 1
< 10
0.0013
1100
< 0.03
28200
494
< 0.5
5900
36500
326
0.0122
286
286
< 5
< 2.5
Roxboro
RO13
3.1
< 10
0.0932
< 50
0.92
5250
3.7
< 0.5
1240
9990
166
0.0511
63.3
63.3
< 5
< 2.5
Roxboro
RO14
5.6
<10
0.0076
827
<0.03
27000
5.9
<0.5
6640
16500
244
0.0299
241
241
<5
<2.6
Roxboro
R015
16.1
12.7
0.0134
< 50
0.83
41300
0.62
0.61
3610
64700
190
0.243
317
317
< 5
< 2.5
Roxboro
RO16
5.5
<10
0.0078
<50
1.2
4240
0.98
1.4
1780
17200
121
0.0289
52.2
52.2
<5
<2.5
Roxboro
RO2
< 10
< 100
0.0391
< 500
0.11
25100
< S
< 5
3500
34000
191
0.0874
204
204
< 5
5.1
Roxboro
RO3
2.8
< 10
0.0228
< 50
0.17
26200
< 0.5
1.3
5260
34000
206
0.0452
203
203
< 5
< 2.5
Roxboro
RO4
1.38
<10
0.00227
221
2.69
10800
144
1.35
2750
16400
260
0.0196
164
<2.5
Roxboro
RO7
5.9
< 10
0.0101
53.8
0.57
10700
29.4
1.9
1960
16300
268
0.0407
111
111
< 5
< 2.5
Roxboro
ROB
5.2
<10
0.0254
1 <50
1 0.28
1 22400
1.9
1 <0.5
4310
1 19600
255
1 0.0414
1 178
178
<5
<2.5
Page 2 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx DHHS April 2016

Table G2-3
Comparison of NCDEQ Water Supply Well Data to DHHS Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L .020
Groundwater Standard (a):
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
(• denotes secondary standard)
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
RSL 2015(d):
NS
NS
NS
NS
NS
Constituents
Not Identified in
the CCR Rule
Plant
Well Owner ID
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
NTU
°C
umhos cm
m L
my
Roxboro
R01
< 1
16.6
505
4.01
Roxboro
R010
Roxboro
RO10-1
1.5
21.8
184.2
3.8
205.3
Roxboro
R010-2
6.2
19.2
631
0.61
219.2
Roxboro
R011
< 1
22.7
470.1
3.42
172.4
Roxboro
R012
8.9
21.3
662
0.89
<
Roxboro
R013
< 1
23.1
145.1
5.07
193.3
Roxboro
R014
7.4
23.6
647
0.95
<
Roxboro
R015
< 1
18.4
799
2.14
176.7
Roxboro
R016
< 1
17.2
188.4
2.4
191
Roxboro
R02
< 1
17.2
640
5.1
259.3
Roxboro
R03
0.15
20.2
692
5.4
181.5
Roxboro
R04
< 1
12.9
400
4.72
Roxboro
R07
< 1
22.3
260.5
4.12
180.5
Roxboro
R08
< 1
21.6
594.2
3.3
257.7
10
Page 3 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx DHHS April 2016

11
Comparison of NCDEQ Water Supply Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
A - Denotes IMAC value.
* - Denotes SMCL value.
°C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC- Interim Maximum Allowable Concentration.
MCL - Maximum Contaminant Level.
MDL - Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA - Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL- Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su -standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
B Detected in method blank (MB).
1 Estimated result between PQL and MDL.
12 Spike recovery outside quality assurance limits @ 135%.
Zb Sample was clear but contained sand -like particles.
Zc Well depth was 635 feet per well tag.
18 Temperature of the sample was exceeded during storage.
BH Method Blank (MB) greater than one half of the Reporting Level (RL), but the sample concentrations are greater than 10x the MB.
** Alkalinity = carbonate + bicarbonate.
S1 Matrix spike and / or matrix spike duplicate sample recovery was not within control limits due to matrix interference. Laboratory Control Sample (LCS) was within control limits.
Z Sample was re -digested and re -analyzed with similar sample and spike results.
M1 Matrix spike recovery exceeded QC limits. Batch accepted based on laboratory control sample (LCS) recovery.
D6 The relative percent difference (RPD) between the sample and sample duplicate exceeded laboratory control limits.
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards2012.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screening-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http://epa-prgs.orni.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) -The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value is above the sreening level.
Reporti ng limit i s a bove the screening level.
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx
4/10/2016

Table G2-4
Comparison of NCDEQ Water Supply Well Data to RSL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202
d(a): Groundwater Standard (a)
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
NS
20
0.2
Federal M ry standard) L (b):
(•denotes secondary stan
NS
NS
*250
6.5 - 8.5
*250
*500
6
10
2000
4
5
100
NS
15
2
NS
50
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
1 L
18
20
0.2
RSL 2015(d):
4000
NS
NS
NS
NS
NS
7.8
0.052
3800
25
9.2
22000
6
15
5.7
100
100
0.2
Append
x III f
Appendix
IV
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
Molybdenum
Selenium
Thallium
Plant
Well Owner ID
u L
u L
m L
su
m L
m L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
u L
Roxboro
R01
<50
83000
41
6.91
51
405
<3
<2
3.62
<1
<0.5
<10
<5
1.73
<0.2
<10
2.39
<1
Roxboro
R010
<100
<1000
230
7.1
24
<5
<5
<100
<3
<1
<10
<10
<5
<0.5
<10
<5
<2
Roxboro
RO10-1
<50
150000
335
7.2
26
999
<5
<5
300
<2
<0.8
<5
<5
<1
<0.2
<5
<5
<1
Roxboro
RO10-2
<50
83000
37
7.1
36
369
<5
<5
119
<2
<0.8
<5
<5
1.7
<0.2
<5
<5
<1
Roxboro
RO11
<5
43800
31.2
6.4
31.1
326
<0.5
<0.5
125
<0.2
<0.08
1.7
<0.5
2.3
<0.2
2
<0.5
<0.1
Roxboro
RO12
6.1
84200
26.7
6.82
71.8
463
<0.5
<0.5
67.1
<0.2
<0.08
<0.5
<0.5
0.24
<0.2
5.9
<0.5
<0.1
Roxboro
RO13
<5
14700
8.4
5.98
2.6
138
<0.5
<0.5
30.9
<0.2
<0.08
1.3
<0.5
1.3
<0.2
<0.5
<0.5
<0.1
Roxboro
RO14
<5
74000
31
7.07
52.3
382
<0.5
<0.5
48.6
<0.2
<0.08
<0.5
<0.5
0.76
<0.2
0.52
1.1
<0.1
Roxboro
RO15
<5
50700
44.5
7
47.1
456
<0.5
<0.5
59
<0.2
<0.08
1.3
<0.5
0.64
<0.2
4.2
<0.5
<0A
Roxboro
RO16
<5
15100
7.8
6.05
19.2
175
<0.5
<0.5
18.7
<0.2
<0.08
1.4
<0.5
0.56
<0.2
<0.5
<0.5
<0.1
Roxboro
RO2
<50
50700
24
6.63
71
383
<5
<5
64.4
<2
<0.8
<5
<5
1.8
<0.2
<5
<5
<1
Roxboro
RO3
86
66200
47
6.34
71
465
<0.5
<0.5
79.1
<0.2
0.072
<0.5
<0.5
0.44
<0.2
2.5
<0.5
<0.1
Roxboro
RO4
< 20
47800
17
6.77
7
267
< 0.4
0.2
66.1
< 0.11
< 0.06
2.69
0.25
0.43
< 0.01
0.38
0.51
< 0.06
Roxboro
RO7
<5
30000
19.4
6.18
7.1
200
<0.5
<0.5
67.8
<0.2
<0.08
6.2
<0.5
0.25
<0.2
<0.5
<0.5
<0.1
Roxboro
RO8
<S
59700
44.2
6.69
29.3
366
<0.5
<0.5
54.3
<0.2
<0.08
0.6
<0.5
40.3
<0.2
0.76
<0.5
<0.1
12
Page 1 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx RSL April 2016

Table G2-4
Comparison of NCDEQ Water Supply Well Data to RSL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L .020
Groundwater Standard (a):
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1
NS
NS
NS
NS
Federal MCL/SMCL (b):
(* denotes secondary standard)
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5
NS
NS
NS
NS
DHHS Screening Level (c):
0.3
3500
1
2500
0.07
NS
200
100
NS
20000
2100
1
NS
NS
NS
NS
RSL 2015(d):
86
20000
0.8
14000
44(e)
NS
430
390
NS
NS
12000
6
NS
NS
NS
NS
Constituents
Not Identified
in the CCR Rule
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Plant
Well Owner ID
u L
u L
m L
u L
u L
u L
u L
u L
u L
u L
u L
m L
m L
m L
m L
m L
Roxboro
RO1
2.84
< 50
< 0.002
< 50
< 20
34000
8.29
< 2
1800
25000
410
0.0147
274
274
< 1
< 5
Roxboro
R010
< 10
< 10
< 0.05
< 100
< 1000
< 30
< 10
< 1000
370000
< 50
< 0.05
376
Roxboro
R010-1
<10
<10
<0.01
200
0.062
61200
1010
<5
6800
59800
936
<0.05
268
259
<5
<2.5
Roxboro
1 11010-2
<10
155
<0.01
1280
<0.03
26000
920
<5
4390
32000
331
<0.05
271
214
<5
7.8
Roxboro
RO11
10.6
<10
1 0.0195
<50
1.2
25700
1.5
0.56
3540
25300
236
0.0363
196
196
<5
<2.5
Roxboro
RO12
< 1
< 10
0.0013
1100
< 0.03
28200
494
< 0.5
5900
36500
326
0.0122
286
286
< 5
< 2.5
Roxboro
RO13
3.1
< 10
0.0932
< 50
0.92
5250
3.7
< 0.5
1240
9990
166
0.0511
63.3
63.3
< 5
< 2.5
Roxboro
RO14
5.6
< 10
0.0076
827
< 0.03
27000
5.9
< 0.5
6640
16500
244
0.0299
241
241
< 5
< 2.6
Roxboro
RO15
16.1
12.7
0.0134
< 50
0.83
41300
0.62
0.61
3610
64700
190
0.243
317
317
< 5
< 2.5
Roxboro
RO16
5.5
< 30
0.0078
< 50
1.2
4240
0.98
1.4
1780
17200
121
0.0289
52.2
52.2
< 5
< 2.5
Roxboro
RO2
< 10
< 100
0.0391
< 500
0.11
25100
< 5
<5
3500
34000
191
0.O874
204
204
< 5
5.1
Roxboro
RO3
2.8
<10
0.0228
<50
0.17
26200
<0.5
1.3
5260
34000
206
0.0452
203
203
<5
<2.5
Roxboro
RO4
1.38
<10
0.00227
22S
2.69
10800
144
1.35
2750
16400
260
0.0196
164
<2.5
Roxboro
RO7
5.9
<10
0.0101
53.8
0.57
10700
29.4
1.9
1960
16300
268
0.0407
111
111
<5
<2.5
Roxboro
RO8
5.2
<10
0.0254
<50
0.28
22400
1.9
<0.5
4310
19600
255
0.0414
178
178
<5
<2.5
13
Page 2 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx RSL April 2016

Table G2-4
Comparison of NCDEQ Water Supply Well Data to RSL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1SA NCAC 02L .020
Groundwater Standard (a):
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
(• denotes secondary standard)
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
RSL 201S(d):
NS
NS
NS
NS
NS
Constituents Not Identified in the CCR Rule
Plant
Well Owner ID
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
NTU
°C
umhos cm
m L
my
Roxboro
RO1
< 1
16.6
505
4.01
Roxboro
R010
Roxboro
RO10-1
1.5
21.8
184.2
3.8
205.3
Roxboro
RO10-2
6.2
19.2
631
0.61
219.2
Roxboro
RO11
< 1
22.7
470.1
3.42
172.4
Roxboro
RO12
8.9
21.3
662
0.89
<
Roxboro
RO13
< 1
23.1
145.1
5.07
193.3
Roxboro
RO14
7.4
23.6
647
0.95
<
Roxboro
RO15
< 1
18.4
799
2.14
176.7
Roxboro
RO16
< 1
17.2
188.4
2.4
191
Roxboro
RO2
< 1
17.2
640
5.1
259.3
Roxboro
RO3
0.15
20.2
692
5.4
181.5
Roxboro
RO4
< 1
12.9
400
4.72
Roxboro
RO7
< 1
22.3
260.5
4.12
180.5
Roxboro
RO8
< 1
21.6
594.2
3.3
257.7
14
Page 3 of 3
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx RSL April 2016

15
Comparison of NCDEQ Water Supply Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
A - Denotes IMAC value.
* - Denotes SMCL value.
°C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC- Interim Maximum Allowable Concentration.
MCL - Maximum Contaminant Level.
MDL - Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA - Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL- Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su -standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
B Detected in method blank (MB).
1 Estimated result between PQL and MDL.
12 Spike recovery outside quality assurance limits @ 135%.
Zb Sample was clear but contained sand -like particles.
Zc Well depth was 635 feet per well tag.
18 Temperature of the sample was exceeded during storage.
BH Method Blank (MB) greater than one half of the Reporting Level (RL), but the sample concentrations are greater than 10x the MB.
** Alkalinity = carbonate + bicarbonate.
S1 Matrix spike and / or matrix spike duplicate sample recovery was not within control limits due to matrix interference. Laboratory Control Sample (LCS) was within control limits.
Z Sample was re -digested and re -analyzed with similar sample and spike results.
M1 Matrix spike recovery exceeded QC limits. Batch accepted based on laboratory control sample (LCS) recovery.
D6 The relative percent difference (RPD) between the sample and sample duplicate exceeded laboratory control limits.
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards2012.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screening-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http://epa-prgs.orni.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
http://www.gpo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) -The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value is above the sreening level.
Reporting limit i s a bove the screening level.
Haley & Aldrich, Inc.
Tables G2-1-G2-4 NCDEQ Data Water Supply Well Screen_2016-04.xlsx
4/10/2016

16
Table G2-5 Page 1 of 3
Comparison of Duke Energy Background Well Data to 21. Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202
Groundwater Standard a:
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
*250
6.5 - 8.5
*250
*500
6
10
2,000
4
5
100
NS
15
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
11.
RSL 2015 (d):
4,000
NS
NS
NS
NS
NS
7.8
0.052
3,800
25
9.2
22,000
6
15
5.7
Appendix III (f)
Appendix IV (g)
Station
Well ID
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
ug/L
ug/L
mg/L
SI Units
mg/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-RO1
<50
7850
<1
<1
<0
<1
<1
<5
<1
<1
<0.05
Roxboro
DBKG-RO2
<50
14
<1
1.4
<5
<1
1.17
<5
<1
<0
<0.05
Roxboro
DBKG-RO3
< 50
18900
< 1
< 1
5
< 1
< 1
< 5
< 1
1.09
< 0.05
Roxboro
DBKG-RO4
< 50
22100
< 1
2.98
5
< 1
< 1
< 5
< 1
11.3
< 0.05
Roxboro
DBKG-RO5
< 50
2280
< 1
< 1
64
< 1
< 1
< 5
< 1
1.61
< 0.05
Roxboro
DBKG-RO6
< 50
9990
< 1
< 1
35
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO7
< 50
51000
< 1
< 1
68
< 1
< 1
< 5
< 1
1.21
< 0.05
Roxboro
DBKG-RO8
<50
7410
<1
<1
<5
<1
<1
<5
<1
16.4
<0.05
Roxboro
DBKG-RO9
< 50
71700
1.2
< 1
42
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO10
< 50
2620
1.15
< 1
29
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RC11
<5
214
<0.5
<0.5
2.1
<0.2
<0.08
0.79
<0.5
1.2
<0.2
Roxboro
DBKG-RO12
< 5
5560
1.1
< 0.5
5.9
0.38
< 0.08
0.54
< 0.5
3
< 0.2
Roxboro
DBKG-RO13
<5
21600
1.1
0.82
12.4
<0.2
<0.08
<0.5
3.6
0.14
<0.2
Roxboro
DBKG-RO14
<5
28300
1.1
<0.5
58.1
0.5
0.099
157
25.9
3.7
<0.2
Roxboro
DBKG-RO15
<5
7480
1.1
<0.5
3.3
0.37
<0.08
<0.5
<0.5
0.64
<0.2
Roxboro
DBKG-RO16
<5
3210
1.1
<0.5
11.2
<0.2
<0.08
<0.5
<0.5
0.81
<0.2
Roxboro
DBKG-RO17
<5
28200
0.99
<0.5
5.6
<0.2
<0.08
<0.5
<0.5
2.3
<0.2
Roxboro
DBKG-RO18
<5
9870
1.1
<0.5
18.6
<0.2
<0.08
<0.5
<0.5
0.61
<0.2
Roxboro
DBKG-RO19
8.5
65100
1.1
<0.5
15.3
<0.2
<0.08
<0.5
<0.5
<0.1
<0.2
Roxboro
DBKG-RO20
<5
38900
1
<0.5
26.4
<0.2
<0.08
0.68
<0.5
0.4
<0.2
Roxboro
DBKG-RO21
9
34400
1.1
<0.5
8
<0.2
<0.08
1.9
<0.5
0.91
<0.2
Roxboro
DBKG-RO22
<5
27500
0.96
<0.5
18.8
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO23
<5
1750
0.97
<0.5
48.4
<0.2
<0.08
<0.5
<0.5
0.86
<0.2
Roxboro
DBKG-RO24
< 5
24900
0.94
< 0.5
48.6
< 0.2
< 0.08
2.4
< 0.5
0.33
< 0.2
Roxboro
DBKG-RO25
<5
21600
0.92
<0.5
61.9
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO26
<5
58100
0.92
<0.5
127
<0.2
<0.08
0.5
<0.5
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx 2L April 2016

17
Table GZ-S Page 2 of 3
Comparison of Duke Energy Background Well Data to 21. Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCA0 d
Groundwater Standard a ja): NS
20
0.2
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1,000
Federal MCL/SMCL (b): NS
* denotes secondary standard
50
2
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5000
DHHS Screening Level (c): 18
20
0.2
0.3
3,500
1
2,500
0.07
NS
200
100
NS
20,000
2,100
1,000
RSL 2015 (d): 100
100
0.2
86
20,000
0.8
14,000
44 (e)
NS
430
390
NS
NS
12,000
6,000
Appendix IV (g)
Constituents Not Identified in the CCR Rule
Station
Well ID
Molybdenum
Selenium
Thallium
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
ug/L
ug/L
ug/L
ug/L
ug/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-RO1
< 1
< 1
< 0.2
1.43
7
0.067
43
3260
< S
'S
47S
6510
63
25
Roxboro
DBKG-RO2
<1
<1
<0.2
<0.3
<S
<O.005
11
<S
<S
<S
123
74200
<S
11
Roxboro
DBKG-RO3
< 1
< 1
< 0.2
1.28
< S
0.014
13
3700
< S
< S
360
5230
86
46
Roxboro
DBKG-RO4
< 1
< 1
< 0.2
2.43
78
0.093
2560
4160
39
< S
1840
8310
73
70
Roxboro
DBKG-RCS
< 1
< 1
< 0.2
< 0.3
< S
0.025
356
573
11
< S
2470
9220
19
118
Roxboro
DBKG-RO6
< 1
< 1
< 0.2
3.87
8
0.224
881
4570
8
< S
2210
8450
80
34
Roxboro
DBKG-RC7
< 1
< 1
< 0.2
< 0.3
6
0.047
2290
16300
680
< S
2870
12000
202
17
Roxboro
DBKG-RO8
< 1
< 1
< 0.2
< 0.3
6
0.578
43
2430
73
380
598
11300
44
24SO
Roxboro
DBKG-RO9
< 1
< 1
< 0.2
< 0.3
19
< 0.005
1030
12900
782
< S
4760
12900
191
< S
Roxboro
DBKG-RO10
< 1
< 1
< 0.2
< 0.3
< S
< 0.005
66
818
< S
< S
1370
6340
22
110
Roxboro
DBKG-RO11
'0.5
< 0.5
< 0.1
< 1
< 10
0.0031
< SO
0.11
128
0.86
< 0.5
146
763
1.3
64.6
Roxboro
DBKG-RO12
<0.5
<0.5
<0.1
<1
<10
0.0416
<SO
0.4
1080
4.9
1.3
1SS0
6250
27.5
22.6
Roxboro
DBKG-RO13
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0011
10300
< 0.6
26600
595
8.9
2510
15200
120
144
Roxboro
DBKG-RO14
3.4
<O.5
<0.1
112
32200
0.0802
45000
0.12
36800
1820
62.9
5800
9970
95.1
286
Roxboro
DBKG-RO15
2.8
< 0.5
< 0.1
< 1
< 10
0.011
103
< 0.03
2970
24.3
< 0.5
1310
10700
26.6
76.5
Roxboro
DBKG-RO16
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0032
< SO
< 0.03
596
34.2
< 0.5
1570
7670
14.3
42.8
Roxboro
DBKG-RO17
0.86
< 0.5
< 0.1
< 1
< 10
0.0044
< SO
< 0.6
5040
26
< 0.5
3570
9620
66.5
16.5
Roxboro
DBKG-RO18
0.96
<0.5
<0.1
<1
14.1
0.0073
<50
0.097
1300
1.5
0.53
1440
10200
49.9
13.9
Roxboro
DBKG-RO19
0.77
< 0.5
< 0.1
< 1
< 10
< 0.001
75.6
< 0.03
11300
57.4
< 0.5
3870
15900
156
34.1
Roxboro
DBKG-RO20
<0.5
<0.5
<0.1
1.6
S9
0.0063
100
0.05
23600
34.3
1.2
1680
11900
246
8
Roxboro
DBKG-RO21
0.52
<0.5
<0.1
1.8
73.9
0.0026
129
<0.6
8400
86.8
1
3010
13300
359
166
Roxboro
DBKG-RO22
0.52
< 0.5
< 0.1
< 1
< 10
< 0.001
1200
< 0.6
3240
207
< 0.5
2090
9550
171
479
Roxboro
DBKG-RO23
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0472
< SO
< 0.6
624
3
< 0.5
2500
8670
16.1
59.1
Roxboro
DBKG-RO24
< 0.5
< 0.5
< 0.1
S.
< 10
0.0091
73.7
1.2
7720
4.4
0.6
1930
11000
349
42.2
Roxboro
DBKG-RO25
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0016
8390
< 0.6
16SOO
1030
1.2
3470
18800
134
54.7
Roxboro
DBKG-RO26
< 0.5
1.5
< 0.1
12.6
< 10
1 0.0213
1 < SO
< 0.6
46300
< 0.5
1 0.63
1 5020
21000
1 194
1 11.4
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx 2L April 2016

18
Table G2-5 Page 3 of 3
Comparison of Duke Energy Background Well Data to 21. Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202NS
Groundwater Standard a
NS
NS
NS
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
NS
NS
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
NS
NS
NS
NS
RSL 2015(d):
NS
NS
NS
NS
NS
NS
NS
NS
NS
Constituents Not Identified in the CCR Rule
Station
Well ID
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
mg/L
Roxboro
DBKG-R01
Roxboro
DBKG-RO2
Roxboro
DBKG-RO3
Roxboro
DBKG-RO4
Roxboro
DBKG-RO5
Roxboro
DBKG-RO6
Roxboro
DBKG-RO7
Roxboro
DBKG-RO8
Roxboro
DBKG-RO9
Roxboro
DBKG-RO10
Roxboro
DBKG-RO11
Roxboro
DBKG-RO12
Roxboro
DBKG-RO13
Roxboro
DBKG-RO14
Roxboro
DBKG-RO15
Roxboro
DBKG-RO16
Roxboro
DBKG-RO17
Roxboro
DBKG-RO18
Roxboro
DBKG-RO19
Roxboro
DBKG-RO20
Roxboro
DBKG-RO21
Roxboro
DBKG-RO22
Roxboro
DBKG-RO23
Roxboro
DBKG-RO24
Roxboro
DBKG-RO25
Roxboro
DBKG-RO26
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx 2L April 2016

Comparison of Duke Energy Background Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
^ - Denotes IMAC value.
* - Denotes SMCL value.
'C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC - Interim Maximum Allowable Concentration.
MCL- Maximum Contaminant Level.
MDL- Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA- Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL - Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su - standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards20l2.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screen ing-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http:Hepa-prgs.ornl.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
httP://www.gPo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) - The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value is above the sreening level.
_ Reporting limit is above the screening level.
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx
19
Page 1 of 1
4/10/2016

20
Table G2-6 Page 1 of 3
Comparison of Duke Energy Background Well Data to MCL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1SA NCAC 02L.0202
Groundwater Standard a
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
*250
6.5 - 8.5
*250
*500
6
10
2000
4
5
100
NS
15
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
1L
RSL 2015 (d):
4,000
NS
NS
NS
NS
NS
7.8
0.052
3,800
25
9.2
22,000
6
15
5.7
Appendix III (f)
Appendix IV (g)
Station
Well ID
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
ug/L
ug/L
mg/L
SI Units
mg/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-RO1
<50
7850
<1
<1
<0
<1
<1
<5
<1
<1
<0.05
Roxboro
DBKG-RO2
<50
14
<1
1.4
<5
<1
1.17
<5
<1
<0
<0.05
Roxboro
DBKG-RO3
< 50
18900
< 1
< 1
5
< 1
< 1
< 5
< 1
1.09
< 0.05
Roxboro
DBKG-RO4
< 50
22100
< 1
2.98
S
< 1
< 1
< 5
< 1
11.3
< 0.05
Roxboro
DBKG-ROS
< 50
2280
< 1
< 1
64
< 1
< 1
< 5
< 1
1.61
< 0.05
Roxboro
DBKG-RO6
< 50
9990
< 1
< 1
35
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO7
< 50
51000
< 1
< 1
68
< 1
< 1
< 5
< 1
1.21
< 0.05
Roxboro
DBKG-RO8
<50
7410
<1
<1
<5
<1
<1
<5
<1
16.4
<0.05
Roxboro
DBKG-RO9
< 50
71700
1.2
< 1
42
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO10
< 50
2620
1.15
< 1
29
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RC11
<5
214
<0.5
<0.5
2.1
<0.2
<0.08
0.79
<0.5
1.2
<0.2
Roxboro
DBKG-RO12
< 5
5560
1.1
< 0.5
5.9
0.38
< 0.08
0.54
< 0.5
3
< 0.2
Roxboro
DBKG-RO13
<5
21600
1.1
0.82
12.4
<0.2
<0.08
<0.5
3.6
0.14
<0.2
Roxboro
DBKG-RO14
<5
28300
1.1
<0.5
58.1
0.5
0.099
157
25.9
3.7
<0.2
Roxboro
DBKG-RO15
<5
7480
1.1
<0.5
3.3
0.37
<0.08
<0.5
<0.5
0.64
<0.2
Roxboro
DBKG-RO16
<5
3210
1.1
<0.5
11.2
<0.2
<0.08
<0.5
<0.5
0.81
<0.2
Roxboro
DBKG-RO17
<5
28200
0.99
<0.5
5.6
<0.2
<0.08
<0.5
<0.5
2.3
<0.2
Roxboro
DBKG-RO18
<5
9870
1.1
<0.5
18.6
<0.2
<0.08
<0.5
<0.5
0.61
<0.2
Roxboro
DBKG-RO19
8.5
65100
1.1
<0.5
15.3
<0.2
<0.08
<0.5
<0.5
<0.1
<0.2
Roxboro
DBKG-RO20
<5
38900
1
<0.5
26.4
<0.2
<0.08
0.68
<0.5
0.4
<0.2
Roxboro
DBKG-RO21
9
34400
1.1
<0.5
8
<0.2
<0.08
1.9
<0.5
0.91
<0.2
Roxboro
DBKG-RO22
<5
27500
0.96
<0.5
18.8
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO23
<5
1750
0.97
<0.5
48.4
<0.2
<0.08
<0.5
<0.5
0.86
<0.2
Roxboro
DBKG-RO24
< 5
24900
0.94
< 0.5
48.6
< 0.2
< 0.08
2.4
< 0.5
0.33
< 0.2
Roxboro
DBKG-RO25
<5
21600
0.92
<0.5
61.9
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO26
<5
58100
0.92
<0.5
127
<0.2
<0.08
0.5
<0.5
1 1.2
<0.2
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx MCL April 2016

21
Table GZ-6 Page 2 of 3
Comparison of Duke Energy Background Well Data to MCL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202
Groundwater Standard a
d(a)
NS
20
0.2
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1,000
Federal MCL/SMCL (b):
* denotes secondary standard
NS
50
2
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5000
DHHS Screening Level(c):
18
20
0.2
0.3
3,500
1
2,500
0.07
NS
200
100
NS
20,000
2,100
1,000
RSL 2015 (d):
100
100
0.2
86
20,000
0.8
14,000
44 (e)
NS
430
390
NS
NS
12,000
6,000
Appendix IV (g)
Constituents Not Identified in the CCR Rule
Station
Well ID
Molybdenum
Selenium
Thallium
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
ug/L
ug/L
ug/L
ug/L
ug/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-RO1
< 1
< 1
< 0.2
1.43
7
0.067
43
3260
< S
'S
47S
6510
63
25
Roxboro
DBKG-RO2
<1
<1
<0.2
<0.3
<S
<O.005
11
<S
<S
<S
123
74200
<S
11
Roxboro
DBKG-RO3
< 1
< 1
< 0.2
1.28
< S
0.014
13
3700
< S
< S
360
5230
86
46
Roxboro
DBKG-RO4
< 1
< 1
< 0.2
2.43
78
0.093
2560
4160
39
1 < S
1840
8310
73
1 70
Roxboro
DBKG-RCS
< 1
< 1
< 0.2
< 0.3
< S
0.025
356
573
11
< S
2470
9220
19
118
Roxboro
DBKG-RO6
< 1
< 1
< 0.2
3.87
8
0.224
881
4570
8
< S
2210
8450
80
34
Roxboro
DBKG-RC7
< 1
< 1
< 0.2
< 0.3
6
0.047
2290
16300
680
< S
2870
12000
202
17
Roxboro
DBKG-RO8
< 1
< 1
< 0.2
< 0.3
6
0.578
43
2430
73
380
598
11300
44
24SO
Roxboro
DBKG-RO9
< 1
< 1
< 0.2
< 0.3
19
< 0.005
1030
12900
782
< S
4760
12900
191
< S
Roxboro
DBKG-RO10
< 1
< 1
< 0.2
< 0.3
< S
< 0.005
66
818
< S
< S
1370
6340
22
110
Roxboro
DBKG-RO11
'0.5
< 0.5
< 0.1
< 1
< 10
0.0031
< SO
0.11
128
0.86
< 0.5
146
763
1.3
64.6
Roxboro
DBKG-RO12
<0.5
<0.5
<0.1
<1
<10
0.0416
<SO
0.4
1080
4.9
1.3
1SS0
6250
27.5
22.6
Roxboro
DBKG-RO13
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0011
10300
< 0.6
26600
595
8.9
2510
15200
120
144
Roxboro
DBKG-RO14
3.4
<O.5
<0.1
112
32200
0.0802
45000
0.12
36800
1820
62.9
5800
9970
95.1
286
Roxboro
DBKG-RO15
2.8
< 0.5
< 0.1
< 1
< 10
0.011
103
< 0.03
2970
24.3
< 0.5
1310
10700
26.6
76.5
Roxboro
DBKG-RO16
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0032
< SO
< 0.03
596
34.2
< 0.5
1570
7670
14.3
42.8
Roxboro
DBKG-RO17
0.86
< 0.5
< 0.1
< 1
< 10
0.0044
< SO
< 0.6
5040
26
< 0.5
3570
9620
66.5
16.5
Roxboro
DBKG-RO18
0.96
<0.5
<0.1
<1
14.1
0.0073
<50
0.097
1300
1.5
0.53
1440
10200
49.9
13.9
Roxboro
DBKG-RO19
0.77
< 0.5
< 0.1
< 1
< 10
< 0.001
75.6
< 0.03
11300
57.4
< 0.5
3870
15900
156
34.1
Roxboro
DBKG-RO20
<0.5
<0.5
<0.1
1.6
S9
0.0063
100
0.05
23600
34.3
1.2
1680
11900
246
8
Roxboro
DBKG-RO21
0.52
<0.5
<0.1
1.8
73.9
0.0026
129
<0.6
8400
86.8
1
3010
13300
359
166
Roxboro
DBKG-RO22
0.52
< 0.5
< 0.1
< 1
< 10
< 0.001
1200
< 0.6
3240
207
< 0.5
2090
9550
171
479
Roxboro
DBKG-RO23
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0472
< SO
< 0.6
624
3
< 0.5
2500
8670
16.1
59.1
Roxboro
DBKG-RO24
< 0.5
< 0.5
< 0.1
5.2
< 10
0.0091
73.7
1.2
7720
4.4
0.6
1930
11000
349
42.2
Roxboro
DBKG-RO25
< 0.5
< 0.5
< 0.1
< 1
< 10
0.0016
8390
< 0.6
16SOO
1030
1.2
3470
18800
134
54.7
Roxboro
DBKG-RO26
< 0.5
1.5
< 0.1
12.6
< 10
1 0.0213
1 < SO
I < 0.6
1 46300
< 0.5
0.63
5020
21000
194
11.4
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx MCL April 2016

22
Table G2-6 Page 3 of 3
Comparison of Duke Energy Background Well Data to MCL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202NS
Groundwater Standard a
NS
NS
NS
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
NS
NS
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
NS
NS
NS
NS
RSL 2015(d):
NS
NS
NS
NS
NS
NS
NS
NS
NS
Constituents Not Identified in the CCR Rule
Station
Well ID
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
mg/L
Roxboro
DBKG-R01
Roxboro
DBKG-RO2
Roxboro
DBKG-RO3
Roxboro
DBKG-RO4
Roxboro
DBKG-RO5
Roxboro
DBKG-RO6
Roxboro
DBKG-RO7
Roxboro
DBKG-RO8
Roxboro
DBKG-RO9
Roxboro
DBKG-RO10
Roxboro
DBKG-RO11
Roxboro
DBKG-RO12
Roxboro
DBKG-RO13
Roxboro
DBKG-RO14
Roxboro
DBKG-RO15
Roxboro
DBKG-RO16
Roxboro
DBKG-RO17
Roxboro
DBKG-RO18
Roxboro
DBKG-RO19
Roxboro
DBKG-RO20
Roxboro
DBKG-RO21
Roxboro
DBKG-RO22
Roxboro
DBKG-RO23
Roxboro
DBKG-RO24
Roxboro
DBKG-RO25
Roxboro
DBKG-RO26
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx MCL April 2016

Comparison of Duke Energy Background Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
^ - Denotes IMAC value.
* - Denotes SMCL value.
'C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC - Interim Maximum Allowable Concentration.
MCL- Maximum Contaminant Level.
MDL- Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA- Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL - Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su - standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards20l2.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screen ing-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http:Hepa-prgs.ornl.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
httP://www.gPo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) - The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value is above the sreeni ng level.
_ Reporting limit is above the screening level.
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx
23
Page 1 of 1
4/10/2016

24
Table G2-7 Page 1 of 3
Comparison of Duke Energy Background Well Data to DHHS Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1SA NCAC 02L.0202
Groundwater Standard a:
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
*250
6.5 - 8.5
*250
*500
6
10
2,000
4
5
100
NS
15
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
1L
RSL 2015 (d):
4,000
NS
NS
NS
NS
NS
7.8
0.052
3,800
25
9.2
22,000
6
15
5.7
Appendix III (f)
Appendix IV (g)
Station
Well ID
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
ug/L
ug/L
mg/L
SI Units
mg/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-RO1
<50
7850
<1
<1
<0
<1
<1
<5
<1
<1
<0.05
Roxboro
DBKG-RO2
<50
14
<1
1.4
<5
<1
1.17
<5
<1
<0
<0.05
Roxboro
DBKG-RO3
< 50
18900
< 1
< 1
5
< 1
< 1
< 5
< 1
1.09
< 0.05
Roxboro
DBKG-RO4
< 50
22100
< 1
2.98
S
< 1
< 1
< 5
< 1
11.3
< 0.05
Roxboro
DBKG-RO5
< 50
2280
< 1
< 1
64
< 1
< 1
< 5
< 1
1.61
< 0.05
Roxboro
DBKG-RO6
< 50
9990
< 1
< 1
35
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO7
< 50
51000
< 1
< 1
68
< 1
< 1
< 5
< 1
1.21
< 0.05
Roxboro
DBKG-RO8
<50
7410
<1
<1
<5
<1
<1
<5
<1
16.4
<0.05
Roxboro
DBKG-RO9
< 50
71700
1.2
< 1
42
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO10
< 50
2620
1.15
< 1
29
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RC11
<5
214
<0.5
<0.5
2.1
<0.2
<0.08
0.79
<0.5
1.2
<0.2
Roxboro
DBKG-RO12
< 5
5560
1.1
< 0.5
5.9
0.38
< 0.08
0.54
< 0.5
3
< 0.2
Roxboro
DBKG-RO13
<5
21600
1.1
0.82
12.4
<0.2
<0.08
<0.5
3.6
0.14
<0.2
Roxboro
DBKG-RO14
<5
28300
1.1
<0.5
58.1
0.5
0.099
157
25.9
3.7
<0.2
Roxboro
DBKG-RO15
<5
7480
1.1
<0.5
3.3
0.37
<0.08
<0.5
<0.5
0.64
<0.2
Roxboro
DBKG-RO16
<5
3210
1.1
<0.5
11.2
<0.2
<0.08
<0.5
<0.5
0.81
<0.2
Roxboro
DBKG-RO17
<5
28200
0.99
<0.5
5.6
<0.2
<0.08
<0.5
<0.5
2.3
<0.2
Roxboro
DBKG-RO18
<5
9870
1.1
<0.5
18.6
<0.2
<0.08
<0.5
<0.5
0.61
<0.2
Roxboro
DBKG-RO19
8.5
65100
1.1
<0.5
15.3
<0.2
<0.08
<0.5
<0.5
<0.1
<0.2
Roxboro
DBKG-RO20
<5
38900
1
<0.5
26.4
<0.2
<0.08
0.68
<0.5
0.4
<0.2
Roxboro
DBKG-RO21
9
34400
1.1
<0.5
8
<0.2
<0.08
1.9
<0.5
0.91
<0.2
Roxboro
DBKG-RO22
<5
27500
0.96
<0.5
18.8
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO23
<5
1750
0.97
<0.5
48.4
<0.2
<0.08
<0.5
<0.5
0.86
<0.2
Roxboro
DBKG-RO24
< 5
24900
0.94
< 0.5
48.6
< 0.2
< 0.08
2.4
< 0.5
0.33
< 0.2
Roxboro
DBKG-RO25
<5
21600
0.92
<0.5
61.9
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO26
<5
58100
0.92
<0.5
127
<0.2
<0.08
0.5
<0.5
1 1.2
<0.2
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx DHHS April 2016

25
Table G2-7 Page 2 of 3
Comparison of Duke Energy Background Well Data to DHHS Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L .020
Groundwater Standard a:
NS
20
0.2
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1,000
Federal MCL/SMCL (b):
* denotes secondary standard
NS
50
2
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5000
DHHS Screening Level (c):
18
20
0.2
0.3
3,500
1
2,500
0.07
NS
200
100
NS
20,000
2,100
1,000
RSL 2015 (d):
100
100
0.2
86
20,000
0.8
14,000
44 (e)
NS
430
390
NS
NS
12,000
6,000
Appendix IV (g)
Constituents Not Identified in the CCR Rule
Station
Well ID
Molybdenum
Selenium
Thallium
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
ug/L
ug/L
ug/L
ug/L
ug/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-ROS
<1
<1
<0.2
1.43
7
0.067
43
3260
<5
<5
475
6510
63
25
Roxboro
DBKG-RO2
<1
<1
<0.2
<0.3
<S
<0.005
11
<5
<5
<5
123
74200
<5
11
Roxboro
DBKG-RO3
< 1
< 1
< 0.2
1.28
< 5
0.014
13
3700
< 5
< 5
360
5230
86
46
Roxboro
DBKG-RO4
<1
<1
<0.2
2.43
78
0.093
2560
4160
39
<5
1840
8310
73
70
Roxboro
DBKG-RO5
<1
<1
<0.2
<0.3
<5
0.025
3S6
573
11
<5
2470
9220
19
118
Roxboro
DBKG-RO6
< 1
< 1
< 0.2
3.87
8
0.224
881
4570
8
< 5
2210
8450
80
34
Roxboro
DBKG-RO7
<1
<1
<0.2
<0.3
6
0.047
2290
16300
680
<5
2870
12000
202
17
Roxboro
DBKG-RO8
<1
<1
<0.2
<0.3
6
0.578
43
2430
73
380
598
11300
44
2450
Roxboro
DBKG-RO9
< 1
< 1
< 0.2
< 0.3
19
< 0.005
1030
12900
782
< 5
4760
12900
191
< 5
Roxboro
DBKG-ROSO
< 1
< 1
< 0.2
< 0.3
< 5
< 0.005
66
818
< 5
< 5
1370
6340
22
110
Roxboro
DBKG-RO11
<0.5
<0.5
<0.1
<1
<10
0.0031
<SO
0.11
128
0.86
<0.5
146
763
1.3
64.6
Roxboro
DBKG-RO12
<0.5
<0.5
<0.1
<1
<10
0.0416
<SO
0.4
1080
4.9
1.3
1550
6250
27.5
22.6
Roxboro
DBKG-RO13
<0.5
<0.5
<0.1
<1
<10
0.0011
10300
<0.6
26600
595
8.9
2510
15200
120
144
Roxboro
DBKG-RO14
3.4
<0.5
<0.1
112
32200
0.0802
45000
0.12
36800
1820
62.9
5800
9970
95.1
286
Roxboro
DBKG-RO15
2.8
<0.5
<0.1
<1
<10
0.011
103
<0.03
2970
24.3
<0.5
1310
10700
26.6
76.5
Roxboro
DBKG-RO16
<0.5
<0.5
<0.1
<1
<10
0.0032
<50
<0.03
596
34.2
<0.5
1570
7670
14.3
42.8
Roxboro
DBKG-RO17
0.86
<0.5
<0.1
<1
<10
0.0044
<50
<0.6
5040
26
<0.5
3570
9620
66.5
16.5
Roxboro
DBKG-RO18
0.96
<0.5
<0.1
<1
14.1
0.0073
<50
0.097
1300
1.5
0.53
1440
10200
49.9
13.9
Roxboro
DBKG-RO19
0.77
<0.5
<0.1
<1
<10
<0.001
75.6
<0.03
11300
57.4
<0.5
3870
15900
156
34.1
Roxboro
DBKG-RO20
<0.5
<0.5
<0.1
1.6
59
0.0063
100
0.05
23600
34.3
1.2
1680
11900
246
8
Roxboro
DBKG-RO21
0.52
<0.5
<0.1
1.8
73.9
0.0026
129
<0,6
8400
86.8
1
3010
13300
359
166
Roxboro
DBKG-RO22
0.52
<0.5
<0.1
<1
<10
<0.001
1200
<0.6
3240
207
<0.5
2090
9550
171
479
Roxboro
DBKG-RO23
<0.5
<0.5
<0.1
<1
<10
0.0472
<50
<0.6
624
3
<0.5
2500
8670
16.1
59.1
Roxboro
DBKG-RO24
<0.5
<0.5
<0.1
5.2
<10
0.0091
73.7
1.2
7720
4.4
0.6
1930
11000
349
42.2
Roxboro
DBKG-RO25
<0.5
<0.5
<0.1
<1
<10
0.0016
8390
<0.6
16500
1030
1.2
3470
18800
134
54.7
Roxboro
DBKG-RO26
<0.5
1.5
<0.1
12.6
<10
0.0213
<50
<0.6
46300
<0.5
0.63
5020
21000
194
11.4
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx DHHS April 2016

26
Table G2-7 Page 3 of 3
Comparison of Duke Energy Background Well Data to DHHS Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202NS
Groundwater Standard a
NS
NS
NS
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
NS
NS
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
NS
NS
NS
NS
RSL 2015(d):
NS
NS
NS
NS
NS
NS
NS
NS
NS
Constituents Not Identified in the CCR Rule
Station
Well ID
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
mg/L
Roxboro
DBKG-R01
Roxboro
DBKG-RO2
Roxboro
DBKG-RO3
Roxboro
DBKG-RO4
Roxboro
DBKG-RO5
Roxboro
DBKG-RO6
Roxboro
DBKG-RO7
Roxboro
DBKG-RO8
Roxboro
DBKG-RO9
Roxboro
DBKG-RO10
Roxboro
DBKG-RO11
Roxboro
DBKG-RO12
Roxboro
DBKG-RO13
Roxboro
DBKG-RO14
Roxboro
DBKG-RO15
Roxboro
DBKG-RO16
Roxboro
DBKG-RO17
Roxboro
DBKG-RO18
Roxboro
DBKG-RO19
Roxboro
DBKG-RO20
Roxboro
DBKG-RO21
Roxboro
DBKG-RO22
Roxboro
DBKG-RO23
Roxboro
DBKG-RO24
Roxboro
DBKG-RO25
Roxboro
DBKG-RO26
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx DHHS April 2016

Comparison of Duke Energy Background Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
^ - Denotes IMAC value.
* - Denotes SMCL value.
'C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC - Interim Maximum Allowable Concentration.
MCL- Maximum Contaminant Level.
MDL- Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA- Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL - Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su - standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards20l2.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screen ing-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http:Hepa-prgs.ornl.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
httP://www.gPo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) - The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value isabovethe sreening level.
Reporting limit is above the screening level.
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx
27
Page 1 of 1
4/10/2016

28
Table G2-8 Page 1 of 3
Comparison of Duke Energy Background Well Data to RSL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1SA NCAC 02L.0202
Groundwater Standard a:
700
NS
250
6.5-8.5
250
500
1
10
700
4
2
10
1
15
1
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
*250
6.5 - 8.5
*250
*500
6
10
2,000
4
5
100
NS
15
2
DHHS Screening Level (c):
700
NS
250
NS
250
NS
1
10
700
4
2
10
1
15
1L
RSL 2015 (d):
4,000
NS
NS
NS
NS
NS
7.8
0.052
3,800
25
9.2
22,000
6
15
5.7
Appendix III (f)
Appendix IV (g)
Station
Well ID
Boron
Calcium
Chloride
pH
Sulfate
Total
Dissolved
Solids
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Lead
Mercury
ug/L
ug/L
mg/L
SI Units
mg/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-RO1
<50
7850
<1
<1
<0
<1
<1
<5
<1
<1
<0.05
Roxboro
DBKG-RO2
<50
14
<1
1.4
<5
<1
1.17
<5
<1
<0
<0.05
Roxboro
DBKG-RO3
< 50
18900
< 1
< 1
5
< 1
< 1
< 5
< 1
1.09
< 0.05
Roxboro
DBKG-RO4
< 50
22100
< 1
2.98
S
< 1
< 1
< 5
< 1
11.3
< 0.05
Roxboro
DBKG-ROS
< 50
2280
< 1
< 1
64
< 1
< 1
< 5
< 1
1.61
< 0.05
Roxboro
DBKG-RO6
< 50
9990
< 1
< 1
35
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO7
< 50
51000
< 1
< 1
68
< 1
< 1
< 5
< 1
1.21
< 0.05
Roxboro
DBKG-RO8
<50
7410
<1
<1
<5
<1
<1
<5
<1
16.4
<0.05
Roxboro
DBKG-RO9
< 50
71700
1.2
< 1
42
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RO10
< 50
2620
1.15
< 1
29
< 1
< 1
< 5
< 1
< 1
< 0.05
Roxboro
DBKG-RC11
<5
214
<0.5
<0.5
2.1
<0.2
<0.08
0.79
<0.5
1.2
<0.2
Roxboro
DBKG-RO12
<5
5560
1.1
<0.5
5.9
0.38
<0.08
0.54
<0.5
3
<0.2
Roxboro
DBKG-RO13
<5
21600
1.1
0.82
12.4
<0.2
<0.08
<0.5
3.6
0.14
<0.2
Roxboro
DBKG-RO14
<5
28300
1.1
<0.5
58.1
0.5
0.099
157
25.9
3.7
<0.2
Roxboro
DBKG-RO15
<5
7480
1.1
<0.5
3.3
0.37
<0.08
<0.5
<0.5
0.64
<0.2
Roxboro
DBKG-RO16
<5
3210
1.1
<0.5
11.2
<0.2
<0.08
<0.5
<0.5
0.81
<0.2
Roxboro
DBKG-RO17
<5
28200
0.99
<0.5
5.6
<0.2
<0.08
<0.5
<0.5
2.3
<0.2
Roxboro
DBKG-RO18
<5
9870
1.1
<0.5
18.6
<0.2
<0.08
<0.5
<0.5
0.61
<0.2
Roxboro
DBKG-RO19
8.5
65100
1.1
<0.5
15.3
<0.2
<0.08
<0.5
<0.5
<0.1
<0.2
Roxboro
DBKG-RO20
<5
38900
1
<0.5
26.4
<0.2
<0.08
0.68
<0.5
0.4
<0.2
Roxboro
DBKG-RO21
9
34400
1.1
<0.5
8
<0.2
<0.08
1.9
<0.5
0.91
<0.2
Roxboro
DBKG-RO22
<5
27500
0.96
<0.5
18.8
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO23
<5
1750
0.97
<0.5
48.4
<0.2
<0.08
<0.5
<0.5
0.86
<0.2
Roxboro
DBKG-RO24
<5
24900
0.94
<0.5
48.6
<0.2
<0.08
2.4
<0.5
0.33
<0.2
Roxboro
DBKG-RO25
<5
21600
0.92
<0.5
61.9
<0.2
<0.08
<0.5
<0.5
0.62
<0.2
Roxboro
DBKG-RO26
<5
58100
0.92
<0.5
1 127
<0.2
<0.08
0.5
<0.5
1.2
<0.2
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx RSL April 2016

29
Table G2-8 Page 2 of 3
Comparison of Duke Energy Background Well Data to RSL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L .020
Groundwater Standard a:
NS
20
0.2
0.3
NS
1
300
NS
NS
50
100
NS
NS
NS
1,000
Federal MCL/SMCL (b):
* denotes secondary standard
NS
50
2
NS
*50 to 200
1.3
*300
NS
NS
*50
NS
NS
NS
NS
*5000
DHHS Screening Level (c):
18
20
0.2
0.3
3,500
1
2,500
0.07
NS
200
100
NS
20,000
2,100
1,000
RSL 201S(d):
100
100
0.2
86
20,000
0.8
14,000
44(e)
NS
430
390
NS
NS
12,000
6,000
Appendix IV (g)
Constituents Not Identified in the CCR Rule
Station
Well ID
Molybdenum
Selenium
Thallium
Vanadium
Aluminum
Copper
Iron
Hexavalent
Chromium
Magnesium
Manganese
Nickel
Potassium
Sodium
Strontium
Zinc
ug/L
ug/L
ug/L
ug/L
ug/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Roxboro
DBKG-ROS
<1
<1
<0.2
1.43
7
0.067
43
3260
<5
<5
475
6510
63
25
Roxboro
DBKG-RO2
<1
<1
<0.2
<0.3
<5
<0.005
11
<5
<5
<5
123
74200
<5
11
Roxboro
DBKG-RO3
< 1
< 1
< 0.2
1.28
< 5
0.014
13
3700
< 5
< 5
360
5230
86
46
Roxboro
DBKG-RO4
< 1
< 1
< 0.2
2.43
78
0.093
2560
4160
39
< 5
1840
8310
73
70
Roxboro
DBKG-RO5
< 1
< 1
< 0.2
< 0.3
< 5
0.025
356
573
11
< 5
2470
9220
19
118
Roxboro
DBKG-RO6
< 1
< 1
< 0.2
3.87
8
0.224
881
4570
8
< 5
2210
8450
80
34
Roxboro
DBKG-RO7
<1
<1
<0.2
<0.3
6
0.047
2290
16300
680
<5
2870
12000
202
17
Roxboro
DBKG-RO8
<1
<1
<0.2
<0.3
6
0.578
43
2430
73
380
598
11300
44
2450
Roxboro
DBKG-RO9
< 1
< 1
< 0.2
< 0.3
19
< 0.005
1030
12900
782
< 5
4760
12900
191
< 5
Roxboro
DBKG-ROSO
<1
<1
<0.2
<0.3
<5
<0.005
66
818
<5
<5
1370
6340
22
110
Roxboro
DBKG-RO11
<0.5
<0.5
<0.1
<1
<10
0.0031
<50
0.11
128
0.86
<0.5
146
763
1.3
64.6
Roxboro
DBKG-RO12
<0.5
<0.5
<0.1
<1
<10
0.0416
<50
0.4
1080
4.9
1.3
1550
6250
27.5
22.6
Roxboro
DBKG-RO13
<0.5
<0.5
<0.1
<1
<10
0.0011
10300
<0.6
26600
595
8.9
2510
15200
120
144
Roxboro
DBKG-RO14
3.4
<0.5
<0.1
112
32200
0.0802
45000
0.12
36800
1820
62.9
5800
9970
95.1
286
Roxboro
DBKG-RO15
2.8
<0.5
<0.1
<1
<10
0.011
103
<0.03
2970
24.3
<0.5
1310
10700
26.6
76.5
Roxboro
DBKG-RO16
<0.5
<0.5
<0.1
<1
<10
0.0032
<50
<0.03
596
34.2
<0.5
1570
7670
14.3
42.8
Roxboro
DBKG-RO17
0.86
<0.5
<0.1
<1
<10
0.0044
<50
<0.6
5040
26
<0.5
3570
9620
66.5
16.5
Roxboro
DBKG-RO18
0.96
<0.5
<0.1
<1
14.1
0.0073
<50
0.097
1300
1.5
0.53
1440
10200
49.9
13.9
Roxboro
DBKG-RO19
0.77
<0.5
<0.1
<1
<10
<0.001
75.6
<0.03
11300
57.4
<0.5
3870
15900
156
34.1
Roxboro
DBKG-RO20
<0.5
<0.5
<0.1
1.6
59
0.0063
100
0.05
23600
34.3
1.2
1680
11900
246
8
Roxboro
DBKG-RO21
0.52
<0.5
<0.1
1.8
73.9
0.0026
129
<0.6
8400
86.8
1
3010
13300
359
166
Roxboro
DBKG-RO22
0.52
<0.5
<0.1
<1
<10
<0.001
1200
<0.6
3240
207
<0.5
2090
9550
171
479
Roxboro
DBKG-RO23
<0.5
<0.5
<0.1
<1
<10
0.0472
<50
<0.6
624
3
<0.5
2500
8670
16.1
59.1
Roxboro
DBKG-RO24
<0.5
<0.5
<0.1
5.2
<10
0.0091
73.7
1.2
7720
4.4
0.6
1930
11000
349
42.2
Roxboro
DBKG-RO25
<0.5
<0.5
<0.1
<1
<10
0.0016
8390
<0.6
16500
1030
1.2
3470
18800
134
54.7
Roxboro
DBKG-RO26
<0.5
1.5
<0.1
12.6
<10
0.0213
<50
<0.6
46300
<0.5
0.63
5020
21000
194
11.4
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx RSL April 2016

30
Table G2-8 Page 3 of 3
Comparison of Duke Energy Background Well Data to RSL Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
15A NCAC 02L.0202NS
Groundwater Standard a
NS
NS
NS
NS
NS
NS
NS
NS
Federal MCL/SMCL (b):
* denotes secondary standard
NS
NS
NS
NS
NS
NS
NS
NS
NS
DHHS Screening Level (c):
NS
NS
NS
NS
NS
NS
NS
NS
NS
RSL 2015(d):
NS
NS
NS
NS
NS
NS
NS
NS
NS
Constituents Not Identified in the CCR Rule
Station
Well ID
Alkalinity
Bicarbonate
Carbonate
Total
Suspended
Solids
Turbidity
Temperature
Specific
Conductance
Dissolved
Oxygen
Oxidation
Reduction
Potential
mg/L
Roxboro
DBKG-R01
Roxboro
DBKG-R02
Roxboro
DBKG-RO3
Roxboro
DBKG-R04
Roxboro
DBKG-R05
Roxboro
DBKG-R06
Roxboro
DBKG-R07
Roxboro
DBKG-RO8
Roxboro
DBKG-R09
Roxboro
DBKG-RO10
Roxboro
DBKG-R011
Roxboro
DBKG-RO12
Roxboro
DBKG-RO13
Roxboro
DBKG-RO14
Roxboro
DBKG-RO15
Roxboro
DBKG-RO16
Roxboro
DBKG-RO17
Roxboro
DBKG-RO18
Roxboro
DBKG-RO19
Roxboro
DBKG-R020
Roxboro
DBKG-R021
Roxboro
DBKG-R022
Roxboro
DBKG-R023
Roxboro
DBKG-R024
Roxboro
DBKG-R025
Roxboro
DBKG-R026
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx RSL April 2016

Comparison of Duke Energy Background Well Data to Screening Levels
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
^ - Denotes IMAC value.
* - Denotes SMCL value.
'C - Degrees Celsius.
Blank data cells indicate no data available.
CCR - Coal Combustion Residual.
DEQ- Department of Environmental Quality.
DHHS - Department of Health and Human Services.
HI - Hazard Index.
IMAC - Interim Maximum Allowable Concentration.
MCL- Maximum Contaminant Level.
MDL- Method Detection Limit.
mg/L - milligrams/liter.
mV - millivolts.
NA- Not available.
NS - No Standard Available.
NTU - Nephelometric Turbidity Units.
PQL - Practical Quantitation Limit (h).
RSL - Risk Based Screening Level.
SMCL - Secondary Maximum Contaminant Level.
su - standard units.
USEPA - United States Environmental Protection Agency.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Data Qualifiers
< Measurement limited by threshold (cannot detect measureable amount below this number). Actual detectable amount below threshold is unknown.
(a) - Classifications and Water Quality Standards Applicable to Groundwaters of North Carolina. North Carolina Administrative Code. April 1, 2013.
http://portal.ncdenr.org/web/wq/ps/csu/gwstandards
(b) - USEPA 2012 Edition of the Drinking Water Standards and Health Advisories. Spring 2012. http://www.epa.gov/sites/production/files/2015-09/documents/dwstandards20l2.pdf.
(c) - 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
(d) - USEPA Risk Based Screening Levels (November 2015). Values for tapwater. HI = 1.
http://www.epa.gov/risk/risk-based-screen ing-table-generic-tables
(e) - Alternative screening level calculated for hexavalent chromium using RSL calculator (http:Hepa-prgs.ornl.gov/cgi-bin/chemicals/csl_search) and current dose -response data from the USEPA's
Integrated Risk Information System. Available at: http://www.epa.gov/IRIS/. The RSL for hexavalent chromium is not a drinking water standard, and the basis of the draft oral cancer toxicity value
used in the calculation of the RSL has been questioned by USEPA's Science Advisory Board; therefore, RSL for Chromium (IV) is based on the noncancer values developed by USEPA.
(f) - The CCR Rule lists these constituents as Constituents for Detection Monitoring (Appendix III).
httP://www.gPo.gov/fdsys/pkg/FR-2015-04-17/pdf/2015-00257.pdf
(g) - The CCR Rule lists these constituents as Constituents for Assessment Monitoring (Appendix IV).
(h) - Each analytical procedure has a PQL, which is defined as "the lowest level achievable among laboratories within specified limits during routine laboratory operation". The PQL is about three to
five times the calculated MDL for the analytical procedure, and represents a practical and routinely achievable reporting limit with a relatively good certainty that any reported value is reliable.
Detected value isabuve the sreeni ng level.
_ Reporting limit is above the screening level.
Haley & Aldrich, Inc.
Tables G2-5-G2-8 Duke Bkg Well Screen_2016-04.xlsx
31
Page 1 of 1
4/10/2016

Page 1 of 1
32
Table G2-9
Do Not Drink Letter Summary
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Constituents Listed in Part 1 of Letter
Hex
Facility
Well ID
Vanadium
Chromium
Chloride
Chromium
Cobalt
Iron
Lead
Manganese
Sodium
Strontium
Sulfate
Thallium
Zinc
Roxboro
R-01
X
X
Roxboro
R-03
X
X
X
X
Roxboro
R-04
Roxboro
R-08
X
X
X
Roxboro
R-02
R-02
X
X
Roxboro
-T
X
X
Roxboro
R-02
X
X
Total number of Constituent Letters
4
5
0
0
0
0
1
1
4
0
0
0
0
Total Number of "Do Not Drink" Letters
(Excluding Hexavalent Chromium and
6
Vanadium)
Total Number of "Do Not Drink" Letters
(Including Hexavalent Chromium and
7
Vanadium)
Total Number of "Do Not Drink" Letters
5
for Hexavalent Chromium
Total Number of "Do Not Drink" Letters
4
for Vanadium
Haley & Aldrich, Inc.
Table G2-9 Do Not Drink Summary.xlsx April 2016

33
Table G3-1 Page 1 of 2
Duke Energy Background Water Supply Well Data
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Notes:
<- Not detected, value is the reporting limit.
°C - Degrees Celsius,
mg/L- milligrams/liter.
mv- millivolts.
NTU - Nephelometric Turbidity Units.
so - standard units.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Haley & Aldrich, Inc.
Table G3-1 Duke Energy Background Well Data_2016-04.xlsx April 2016

34
Table G3-1 Page 2 of 2
Duke Energy Background Water Supply Well Data
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
MMMOMMMMMOMMMM
=mom
Notes:
<- Not detected, value is the reporting limit.
°C - Degrees Celsius.
mg/L - milligrams/liter.
my - millivolts.
MU - Nephelometric Turbidity Units.
su - standard units.
ug/L - micrograms/liter.
umhos/cm - micromhos/centimeter.
Haley & Aldrich, Inc.
Table G3-1 Duke Energy Background Well Data_2016-04.xlsx April 2016

35
Table G3-2
Facility Specific Background Data for Bedrock and Deep Monitoring Wells
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Well ID
Sample ID
Date Sampled
Barium
(ug/L)
Boron
(ug/L)
Cobalt
(ug/L)
Hexavalent Chromium
(ug/L)
Iron
(ug/L)
Lead
(ug/L)
Manganese
(ug/L)
Nckel, Dissolved
(ug/L)
Vanadium
(ug/L)
Chloride
(ug/L)
BG-01
BG-01-20101130
30-Nov-10
69.7
< 50
881
< 5
27.2
14200
BG-01
BG-01-20110420
20-Apr-11
73.1
< 50
499
< 5
18.5
13400
BG-01
BG-01-20110713
13-Jul-11
84
<50
752
<5
25.8
12700
BG-01
BG-01-20111102
02-Nov-11
75.6
< 50
307
< 5
7.8
13400
BG-01
BG-01-20120402
02-Apr-12
72.3
< 50
286
< 5
6.5
15500
BG-01
BG-01-20120711
11-Jul-12
81
<50
866
<5
18.7
14500
BG-01
BG-01-20121106
06-Nov-12
84.2
< 50
532
< 5
11.1
15000
BG-01
BG-01-20130408
08-Apr-13
79
< 50
113
< 1
5
14000
BG-01
BG-01-20130708
08-Jul-13
83
<50
368
<1
9
15000
BG-01
BG-01-20131111
11-Nov-13
83
< 50
507
< 1
11
14000
BG-01
BG-01-20140403
03-Apr-14
86
< 50
370
< 1
8
17000
BG-01
BG-01-2014071S
IS-Jul-14
81
<50
218
<1
6
16000
BG-01
BG-01-20141112
12-Nov-14
87
< 50
437
< 1
9
16000
BG-01
BG-01-20150416
16-Apr-15
95
< 50
2.54
283
< 1
54
16000
BG-01
BG-01-20150709
09-Jul-15
90
< 50
1.28
518
< 1
36
17.1
17000
BG-01
BG-01-20150916
16-Sep-15
91
< 50
< 1
811
< 1
21
1.31
22.7
16000
BG-01
BG-01-20151105
05-Nov-15
92
< 50
< 1
594
< 1
21
18.1
17000
BG-01
BG-01-20151205
05-Dec-15
86
< 50
0.62
6.2
360
< 0.1
16
1.7
14.5
16400
BG-01
BG-01-20160105
05-Jan-16
91
< 50
< 1
4.5
484
< 1
17
1.51
17.5
18000
BG-01BR
BG-01BR-20150610
10-Jun-15
21
< 50
1.44
225
< 1
690
< 1
1.94
15000
BG-01BR
BG-01BR-20150912
12-Sep-15
27
< 50
< 1
374
< 1
614
< 1
0.425
13000
BG-01BR
BG-01BR-20151205
05-Dec-15
30
< 50
< 0.5
< 0.03
380
< 0.1
420
1.3
< 1
11700
BG-01BR
BG-01BR-20160105
05-Jan-16
33
<50
<1
<0.03
375
<1
445
1.43
1.25
12000
MW-101311
MW-10BRDUP-20151204
04-Dec-15
102
<50
5.16
<0.03
75
<1
656
<1
1.38
17000
M W-10BR
M W-10BR-20150527
27-May-15
93
< 50
8.2
33
< 1
478
< 1
2.09
17000
MW-10BR
MW-10BR-20150629
29-Jun-15
0.064
M W-10BR
M W-10BR-20150912
12-Sep-15
107
< 50
50.97
46
< 1
840
< 1
1.34
16000
M W-10BR
M W-10BR-20151204
04-Dec-15
107
< 50
5.15
< 0.03
65
< 1
811
< 1
1.3
17000
MW-10BR
MW-10BR-20160106
06-Jan-16
120
<50
6.38
<0.03
87
<1
752
<1
1.28
18000
MW-13BR
MW-13BRDUP-20150530
30-May-15
329
<50
3.44
3320
<1
969
1.34
0.455
84000
MW-13BR
MW-13BRDUP-20160106
06-Jan-16
349
<50
5.5
<0.03
6140
<1
1220
1.47
0.386
92000
MW-13BR
MW-13BR-20150530
30-May-15
323
<50
3.97
4000
<1
1140
1.28
0.364
84000
MW-13BR
MW-13BR-20150913
13-Sep-15
309
<50
3.71
4130
<1
1080
2.37
0.819
76000
MW-13BR
MW-13BR-20151205
05-Dec-15
330
<50
4.2
<0.03
5900
<0.1
1300
1.2
<1
77500
MW-13BR
MW-13BR-20160106
06-Jan-16
349
<50
5.31
<0.03
6080
<1
1200
1.59
0.398
93000
MW-14BR
MW-14BRDUP-20150610
10-Jun-15
33
<50
1.12
871
<1
328
1.61
0.465
41000
MW-14BR
MW-14BR-20150610
10-Jun-15
32
< 50
1.1
898
< 1
328
< 1
0.444
40000
MW-14BR
MW-14BR-20150912
12-Sep-15
37
<50
1.86
2990
<1
395
11.7
1.84
40000
M W-14BR
M W-14BR-20151206
06-Dec-15
34
< 50
0.94
< 0.03
2200
< 0.1
340
1.5
< 1
41900
Haley & Aldrich, Inc.
Table G3.2_Facility Bkg Data.xlsx
Page 1 of 2
April 2016

36
Page 2 of 2
Table G3-2
Facility Specific Background Data for Bedrock and Deep Monitoring Wells
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Well ID
Sample ID
Date Sampled
Barium
(ug/L)
Boron
(ug/L)
Cobalt
(ug/L)
Hexavalent Chromium
(ug/L)
Iron
(ug/L)
Lead
(ug/L)
Manganese
(ug/L)
Nckel, Dissolved
(ug/L)
Vanadium
(ug/L)
Chloride
(ug/L)
MW-14BR
MW-14BR-20160106
06-Jan-16
38
< 50
1.25
< 0.03
1780
< 1
291
1.28
0.362
43000
MW-15BR
MW-15BR-20150616
16-Jun-15
19
< 50
< 1
541
< 1
36
< 1
0.503
34000
MW-15BR
MW-15BR-20150912
12-Sep-15
19
< 50
< 1
456
< 1
30
< 1
0.369
34000
MW-15BR
MW-15BR-20151205
05-Dec-15
15
< 50
< 0.5
< 0.03
230
< 0.1
19
< 0.5
< 1
33200
MW-15BR
MW-15BR-20160105
05-Jan-16
16
< 50
< 1
< 0.03
262
< 1
10
< 1
< 0.3
34000
MW-15D
MW-15D-20150530
30-May-15
10
<50
4.01
163
<1
316
17.9
4.96
43000
MW-15D
MW-15D-20150912
12-Sep-15
9
<50
1.11
671
<1
80
15
7.66
43000
MW-15D
MW-15D-20151205
05-Dec-15
5
< 50
< 0.5
2.1
58
< 0.1
45
13.7
6.5
41200
MW-15D
MW-15D-20160105
05-Jan-16
8
< 50
< 1
1.5
240
< 1
48
14.9
8.03
40000
MW-16BR
MW-16BR-20150527
27-May-15
64
< 50
< 1
106
< 1
272
1.13
2.1
12000
MW-16BR
MW-16BR-20150630
30-Jun-15
0.135
MW-16BR
MW-16BR-20150913
13-Sep-15
69
< 50
< 1
275
< 1
182
1.12
1.83
13000
MW-16BR
MW-16BR-20151205
05-Dec-15
76
<50
<0.5
0.074
170
0.11
170
1.3
2.5
11900
MW-16BR
MW-16BR-20160106
06-Jan-16
75
< 50
< 1
0.099
116
< 1
138
1.14
3.08
13000
MW-17BR
MW-17BR-20150616
16-Jun-15
107
<50
<1
118
<1
354
<1
0.968
15000
MW-17BR
MW-17BR-20150915
15-Sep-15
110
< 50
< 1
486
< 1
328
< 1
2.03
16000
MW-17BR
MW-17BR-20151206
06-Dec-15
100
< 50
< 0.5
< 0.03
750
< 0.1
320
1.5
< 1
15000
MW-17BR
MW-17BR-20160106
06-Jan-16
100
< 50
< 1
< 0.03
756
< 1
359
< 1
0.454
15000
MW-18BR
MW-18BR-20150602
02-Jun-15
77
< 50
20.1
95
< 1
789
< 1
0.931
120000
MW-18BR
MW-18BR-20150629
29-Jun-15
<0.021
MW-18BR
MW-18BR-20150914
14-Sep-15
52
< 50
1.03
363
< 1
475
< 1
< 0.3
130000
MW-18BR
MW-18BR-20151205
05-Dec-15
49
<50
1.9
<0.03
1000
<0.1
660
<0.5
<1
124000
MW-18BR
MW-18BR-20160105
05-Jan-16
1 62
< 50
1.63
< 0.03
1260
< 1
874
< 1
< 0.3
120000
Notes:
<- Not Detected, value is the reporting limit.
ug/L- Microgram per liter.
Haley & Aldrich, Inc.
Table G3.2_Facility Bkg Data.xlsx April 2016

37
Page 1 of 1
Table G3-3
Background Data Statistical Evaluation
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
1 2 3 4 5 6 1 7 8 1 9 1 10 11 12 13 14 15 16 17
Regional Background Evaluation
Variable
Units
Frequency of Detection
Percent
Non-
Detects
Range of Non-
Detects
KM Mean
KM
Variance
KM Standard
Deviation
KM Coefficient
of Variation
50th
Percentile
(Q2)
95th
Percentile
Maximum
Detect
Outlier
Presence*
Outlier
Removed
Distribution
BTV
Method
Barium
ug/L
22 / 24
8%
5 5
27.79
866.8
29.44
1.06
16.95
67.4
127
Yes
No
Gamma
126.8
95%Approx. Gamma UTL WH and KM
Boron
ug/L
2 / 25
92%
5 50
5.5
1.633
1.278
0.232
5
50
9
NA
No
NA
9
Maximum Detect
Cobalt
ug/L
1 / 25
96%
0.5 1
0.624
0.369
0.607
0.974
0.5
1
3.6
NA
Yes (a)
NA
3.6
Maximum Detect
Hexavalent Chromium
ug/L
5 / 25
80%
0 0.6
0.0851
0.0607
0.246
2.896
0.03
0.6
1.2
Yes
No
Normal
0.65
95% KM UTL
Iron
ug/L
18 / 25
28%
50 50
1114
6428291
2535
2.275
73.7
7224
10300
Yes
Yes
Gamma
6862
95%Approx. Gamma UTL WH and KM
Lead
ug/L
19 / 24
21%
0.1 1
1.981
13.77
3.71
1.873
1
10.06
16.4
Yes
No
Distribution free
16.4
Maximum Detect (95% UTL)
Manganese
ug/L
20 / 25
20%
0.5 5
148.5
80069
283
1.905
24.3
761.6
1030
Yes
Yes
Gamma
952.1
95%Approx. Gamma UTL WH and KM
Nickel
ug/L
9 / 25
64%
0.5 5
16.21
5517
74.28
4.582
1.2
8.12
380
Yes
No
Distribution free
380
Maximum Detect (95% UTL)
Vanadium
ug/L
8 / 25
68%
0.3 1
1.412
6.713
2.591
1.834
1
4.934
12.6
Yes
Yes
Normal
7.351
95% KM UTL
Chloride
ug/L
0 / 0
NA
NA NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
NA
Facility Specific Background Evaluation
Variable
Units
Frequency of Detection
Percent
Non-
Detects
Range of Non-
Detects
KM Mean
KM
Variance
KM Standard
Deviation
KM Coefficient
of Variation
50th
Percentile
(Q2)
95th
Percentile
Maximum
Detect
Outlier
Presence*
Outlier
Removed
Distribution
BTV
Method
Barium
ug/L
59 / S9
0%
NA NA
92.02
7581
87.07
0.946
79
329.1
349
No
No
Distribution free
349
Maximum Detect (9S% UTL)
Boron
ug/L
0 / 59
100%
50 50
NA
NA
NA
NA
50
50
NA
NA
No
NA
50
Maximum RL
Cobalt
ug/L
26 / 46
43%
0.5 1
3.372
61.03
7.812
2.317
1.065
7.745
50.97
Yes
No
Lognormal
14.41
95% KM UTL
Hexavalent Chromium
ug/L
6 / 22
73%
0.03 0.03
0.68
2.51
1.584
2.331
0.03
4.38
6.2
Yes
No
Normal
4.401
95% KM UTL
Iron
ug/L
59 / 59
0%
NA NA
970.7
2201331
1484
1.528
437
4307
6140
Yes
No
Lognormal
5368
95% KM UTL
Lead
ug/L
1 / 59
98%
0.1 5
0.101
9.88E-06
0.00314
0.0311
1
5
0.11
NA
No
NA
0.11
Maximum Detect
Manganese
ug/L
59 / 59
0%
NA NA
341.2
143620
379
1.111
272
1146
1300
No
No
Distribution free
1220
95% UTL
Nickel
ug/L
24 / 43
44%
0.5 1
2.553
19.92
4.463
1.748
1.14
14.78
17.9
Yes
No
Distribution free
17.9
Maximum Detect (95% UTL)
Vanadium
ug/L
36 / 45
20%
0.3 1
3.381
3.07E+01
5.541
1.639
1
17.42
22.7
Yes
No
Lognormal
19.26
95% KM UTL
Chloride
ug/L
59 / 59
0%
NA NA
34703
1.06E+09
32498
0.936
17000
120000
130000
No
No
Distribution free
130000
Maximum Detect (95% UTL)
Notes:
* -Tested at 5%significance level.
BTV - Background Threshold Value.
KM - Kaplan -Meier Method.
NA - Not Available.
RL - Reporting Limit.
ug/L- Microgram per liter.
UPLs - Upper Prediction Limits.
UTLs - Upper Tolerance Limits.
Var - Variance.
WH - Wilson Hilferty Transformation.
(a) - Data is removed as part of the outlier test for other constituents
BTV values and statistics were calculated using ProUCL v. 5.0.00.
Haley & Aldrich, Inc.
Table G3-3_Bnkgro d Evaluati- Roxb.-Asx April 2016

38
Page 1 of 1
Table G3-4
Comparison of NCDEQ Water Supply Well Sampling Data to Regional Background Threshold Values
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Constituents
Units
Frequency of
Detection (a)
Range of Detected
Concentrations
Mean
Detect
loth
Percentile
25th
Percentile
50th
Percentile
75th
Percentile
90th
Percentile
Regional
Background Threshold
Value (BTV) (b)
Number of Samples
Above Regional BTV
Barium
ug/L
14 / 15
3.62 - 300
78.83
23.58
51.45
66.1
89.55
122.6
126.8
1
Boron
ug/L
2 / 15
6.1 - 86
46.05
5
5
6.1
50
71.6
9
1
Cobalt
ug/L
1 / 15
0.25 - 0.25
0.25
0.5
0.5
0.5
5
5
3.6
0
Hexavalent Chromium
ug/L
10 / 14
0.062 - 2.69
0.803
0.03
0.074
0.425
1.13
2.243
0.65
5
Iron
ug/L
6 / 15
53.8 - 1280
614.8
50
50
53.8
364
990.8
6862
0
Lead
ug/L
13 / 15
0.24 - 40.3
4.035
0.322
0.5
1
1.765
3.92
16.4
1
Manganese
ug/L
12 / 15
0.62 - 1,010
218.4
0.764
1.7
5.9
87
749.6
952.1
1
Nickel
ug/L
6 / 15
0.56 - 1.9
1.187
0.5
0.53
1.35
3.5
5
380
0
Vanadium
ug/L
10 / 15
1.38 - 16.1
5.902
1.948
2.97
5.6
10
10.36
7.351
2
Notes:
BTV - Background Threshold Value.
DEQ- Department of Environmental Quality.
NC - North Carolina.
ug/L - micrograms/liter.
(a) - Frequency of Detection: number of detects / total number of results.
(b) - BTV values shown on Table G3-3.
Haley & Aldrich, Inc.
Table G3-4 NCDEQ Water Supply Well Data Compared to Regional BTVs.xlsx April 2016

39
Table G3-5
Comparison of NCDEQ Water Supply Well Sampling Data to Facility Specific Background Threshold Values
Roxboro Steam Electric Plant
Water Supply Well Evaluation
Duke Energy
April 2016
Constituents
Units
Frequency of
Detection (a)
Range of Detected
Concentrations
Mean
Detect
loth
Percentile
25th
Percentile
50th
Percentile
75th
Percentile
90th
Percentile
Facility Specific
Background Threshold
Value (BTV) (b)
Barium
ug/L
14 / 15
3.62 - 300
78.83
23.58
51.45
66.1
89.55
122.6
349
Boron
ug/L
2 / 15
6.1 - 86
46.05
5
5
6.1
50
71.6
50
Cobalt
ug/L
1 / 15
0.25 - 0.25
0.25
0.5
0.5
0.5
5
5
14.41
Hexavalent Chromium
ug/L
10 / 14
0.062 - 2.69
0.803
0.03
0.074
0.425
1.13
2.243
4.401
Iron
ug/L
6 / 15
53.8 - 1280
614.8
50
50
53.8
364
990.8
5368
Lead
ug/L
13 / 15
0.24 - 40.3
4.035
0.322
0.5
1
1.765
3.92
0.11
Manganese
ug/L
12 / 15
0.62 - 1,010
218.4
0.764
1.7
5.9
87
749.6
1220
Nickel
ug/L
6 / 15
0.56 - 1.9
1.187
0.5
0.53
1.35
3.5
5
17.9
Vanadium
ug/L
10 / 15
1.38 - 16.1
5.902
1.948
2.97
5.6
10
10.36
19.26
Chloride
ug/L
15 / 15
7.8 - 335
62.95
11.84
21.7
31.2
44.35
156.8
130000
Notes:
BTV - Background Threshold Value.
DEQ- Department of Environmental Quality.
NA - Not Available.
NC - North Carolina.
ug/L - micrograms/liter.
(a) - Frequency of Detection: number of detects / total number of results.
(b) - BTV values shown on Table G3-3.
Page 1 of 1
Haley & Aldrich, Inc.
Table G3-5 NCDEQ Water Supply Well Data Compared to Facility Specific BTVs.xlsx
April 2016

L I, III III I
J f I I.1 liii i
VIRGINIA
--------' --- MAYO
I --------- II• ROXBORO, NC
BELEWS CREEK R MORA, NC
O
BELEWS CREEK, NC
• I •
L u,
L II
L.I Li l ,i II BUCK
I + + I MARSHALL SALISBURY, NC
I, dl TERELL, NC
� =li File
I I •,• III•
CLIFFSIDE
MOORESBORO,NC ALLEN
BELMONT, NC
+ •ai ill
IIIIIIII 3' ff
SOUTH
CAROLINA
,III •I I
NORTH
CAROLINA

HYCOLAKE i I
r _
GYPSUM
ROXBORO STEAM PAD EXTENT OF
ELECTRIC PLANT UNLINED LANDFILL
A y
1966 I �a
SEMI -ACTIVE
BASIN LINED
l� LANDFILL
C �
MORq RO
_ o
RO /
441CH
/ ARCHIE p<
�Z
L
LEGEND
NOTES
FN Tal
ITA
ull

HYCO LAKE
I
I
lqw_�
LEGEND
ROXBORO STEAM PAD/ EXTENT OF
ELECTRIC PLANT 1v/ UNLINED LANDFILL
ANDFILL �
1966 I
SEMI -ACTIVE I
BASIN �� LINED O NOTES
LANDFILL
4 °
� o
i
1973 ACTIVE O
ASH BASIN 4 ��
NNAWAY RD
i
o �
o

LEGEND
v 1 HYCOLAKE
MW-14BR I
GYPSUM-
ROXBORO STEAM PAD EXTENT OF
ELECTRIC PLANT UNLINED LANDFILL
1966
SEMI -ACTIVE
BASIN
LINED
LANDFILL I NOTES
0
J
MW-17BR
MW-13BR R
MW-16BR
DUNNAVVAY RO -
\ �MW-108R r
\
C \
\ \ BG.01 BR
\ BG-01
\ \ MW-15D
SFMOk �0,MW-15BR
q RO )
L-
'rla I -iP,-�
FN Tal
ITA
ulky

A 1
LEGEND
44
ol
1 p
In
x.
�M1'r�f , � � E r �' :Y' h _ h'�'r •.J 45�'� #Y f °
.. _ .. _ 'may
l� GYPSUM �a3r '
° PADS
c
I[
- .use-��'` brt�..l'J�l�a_J ,td• _ - _ ?. •4j r ��' '4 ��Ice`en
I
—ram 4
SEMI -AC ACTIVE'
}'
t
1 4i
� i
BASIN_
av
t
s 040
O Grp
t"1973 ACTIVE Ir.�
t. ASH BASIN
� Il; tz: .I 4. 'a � i7_+�p '•�:� � NOTES:
i
a
G
r O
O f
- y
SR-1377
w
-
.s
a
. 'DUKEENERGY
Q
O- PROGRESS
O r -
ES
_
: � w
FIGURE G4-1
SITE CONCEPTUAL MODEL -PLAN VIEW
w
ROXBORO STEAM ELECTRIC PLANT w
r
w

r
<50 (< 50)
S) Aesm
4060
< 50 (Ngo
A
i �♦
MW 08BR4
go 10
, r r la
< 5(< 50)
a`
ABMW-01 BR'
176 (183)--
MW-120 BR'
< 50 (< 50)
1973 ACTIVE
ASH BASIN
MW-07B mm
+ +, 01G10113R4
fy ## <50(<50)
.. # >.
k• * .... 700
. a " ♦ 700
vV-03BR
MW-03BR'
2310 (2290)
GYPSUM`S r ♦.
PAD
y
GMW-11Z
r'.
-
z X O*MW 01BR'
GMW-10 708 (NS) CW-01'
- --•
< 50 (NS) 592 (574) < 50 (NS)
MW-06BR
"IABMW-07BR r
< 50 (< 50)
1966
659 (674) go
SEMhACTIVE•
'•, �■ r fir`
MW-11BR'
BASINw
;BR' < 50 (< 50)
'
< 50)
A,ABMW-04BR'
c 50 (< 50)
a
ABMW-06BR' f '
t
< 50 (< 50)1r t
GMW_07
♦ ♦
or 66'(NS). �
'
�M1N-02BR'
< 50`(< 50)
♦ `
"
GMW-OSz
4050i(N31' GA GMW-09z
(700)
-y y (700)
NS
■ NORTH CAROLINA 2L CONTOUR
■
■
■
•�.._j
MW-17BR4
5.50 (< 50)
y y
t
MW-13BR' I '
MW-16BR'
i
< 50 ( .50)
W%
.
_ - -
M-1100BR' y�
50)
1 1
MW-18131 y' t
1
DUKE
ENERGY
synTerra PROGRESS

LEGEND
S ABMW-5BR CSA MONITORING WELL
4eFQ_G-_31
CSA DATA CAP MONITORING WELL
l CW-1
COMPLIANCE MONITORING WELL
❑ BG-1D
BACKGROUND COMPLIANCE MONITORING WELL
9 GMW-8
LANDFILL MONITORING WELL
MW-02
MONITORING WELL
4)PZ-12
PIEZOMETER
O P-102
PIEZOMETER (BLACKROCK GEOTECH EVALUATION)
■ SW-06
SURFACE WATER & SEDIMENT SAMPLE LOCATION
®
SEEP SAMPLE LOCATION
NC DEQ SAMPLED PRIVATE WELL (APPROXIMATE)
---
DUKE ENERGY PROGRESS PARCEL LINE
PERSON COUNTY PARCEL LINE
COMPLIANCE BOUNDARY
WASTE BOUNDARY
NAP MW-14S
MW-14D
MW-14BR 3
— S-13
/ MW 3BR fi
cr
� TowEltio_ _ `♦ i �
e'.. POND /
' GMW-2A
' GMW-2 GMW 10 _� MW-1BR ► CW 1
COOLINGti GMW 11
INOTAED
KE POND
1 ELECTRICAL SUBSTATION
MW 6D GMW-1 � ® R016
LINED LANDFILL LIMIT (APPROXIMATE) / I
AERIAL IMAGES: MW-6BR GMW-1A (, PZ-14 ABMW 7
APRIL 17, 2014 AERIAL PHOTOGRAPH OBTAINED FROM WSP. i / 'r ABM W-7 BR
FEBRUARY 20, 2013 AERIAL PHOTOGRAPHS OUTSIDE OF THE WSP AERIAL COVERAGE ABM W-5 DG-7 WERE OBTAINED FROM THE NC GEOSPATIAL PORTAL AT �';- ABMW-5D
http://data.nconemap.gov/geoportal/catalog/main/home.page -
MW-11BR S EAST ASH S-10
HYCO RESERVOIR ., ,, MW-5D BASIN _ O s-o9
O
ABMW 4
:. MW 5BR ABMW 6 ABMW-4BR LINED ASH s-11 I 'A DG-3
CW 2 CW_5
ABMW 6BR MONOFILL
CW 2D 6 4 PZ-12 4 O S-12 ALI
S W-W-'
■ SW-03 0
ABMW-3 DG 5I---
ABMW-3BR
- _ MW-02 4 � � � EASTERN EXTENSION -
1 MW 2BR % I IMPOUND T3 R04
R07 R013
„� / MW 17BR S ■
GMW 8 1
? SW-02 MW 8BR S 1 ABMW-1BR�!,� '1r GMW 9
\ WEST
j
�, MW 12BR ti POND
- - EASTPOND
FGD
T 5�rri
\ N / p-102 '
®FGD L� _�� OF MW 13BR
PO
No i I' ! R09
\ ➢ WEST ASH BASIN` DG 2
MW 7BR \ 1 .���*;R05
ti MW 10BR ,
R02_7
o�NN��
1 R03 •� R08 R011 Ro • R015
1 �2
CW 3 `" _ 1 z
CW 3D \ �,
4;
13
r DG 1 '0� FIGURE G4-3
CROSS-SECTION LOCATION MAP
BG-01BR 0S I FB Mw 4BR ti ROXBORO STEAM ELECTRIC PLANT
BG 1D 1 CW-4
'/ ,: SW-05
SOUTHERN EXTENSION IMPOUNDMENT -
1700 DUNAWAY RD
Flip
loo SEMORA, NORTH CAROLINA
v ./ RA SCALE
R010 _ � GRAPHIC S AL
MW-15D
"`^' ' 500 0 500 1000
IN FEET
SFy0Q9 RO(NO „ M W 15BR , 148 RIVER STREET, SUITE 220
GREENV
LLE, SOUTH
i WN/GywgYg"-_ 81-429999AROLINA
WOODLAND PHONE 64
29601
: �� wwwsynterracorp.com
ELEMENTARY SCHOOL MW 18D r
rra
i Te DRAWN BY: JOHN CHASTAIN DATE: 04/07/2016
MW 18BR
' PROJECT MANAGER: CRAIG EADY
- ... ti-.. ❑ S�/_04 I I w LAYOUT: FIG (CROSS-SECTION LOC MAP)
t
� s.'

A -
(SOUTH)
J
O
O
2
U
to
tr
z F
r,
JZ
W
O
02
08
O LU
�W
00
O�
O
w
_I
m
C
Z
W
C7
Q
U
W
?
REGOLITH
Q
TD 437' msl.
REPORTED 280' DEEP WELL AT
THE WOODLAND ELEMENTARY
SCHOOL (IN USE)
t260' msl.
THE
USE)
t 65' msl.
SOURCE INFORMATION:
EXISTING GROUND SURFACE BASED ON A DRAWING PROVIDED BY THE WSP GROUP, TITLED "ROXBORO FINAL", DATED JUNE 8, 2015.
HISTORIC GROUND SURFACE BASED ON THE 7-1/2' USGS TOPOGRAPHIC MAP FOR OLIVE HILL, NC DATED 1968, REVISED 1994.
MONITORING WELL DATA WAS OBTAINED FROM THE COMPREHENSIVE SITE ASSESSMENT REPORT PREPAREED BY SYNTERRA, DATED SEPTEMBER 2, 2015.
PRIVATE WATER SUPPLY WELL INFORMATION WAS OBTAINED FROM A LIST PROVIDED BY DUKE ENERGY PROGRESS
MONITORING WELL WATER LEVELS WERE COLLECTED BY SYNTERRA ON DECEMBER 5-6, 2015.
UKE ENERGY ROXBORO STEAM ELECTRIC PLANT PROPERTY
COMPLIANCE BOUNDARY
WASTE BOUNDARY
� O
O Q
W J
EAST >
BIO-REACTOR FGD
BUILDING cD /�*�ASHISOIL"ul"���
FGDPOND cs
ASH
LE BASED ON F
TOPOGRAPHIC
349' msl.
PORE WATER
ASH
TO
0
a
0
W
a
0
166'
� a
Q
O
o_
r
o.
TO 435' msl.
D 382' msl.:
AREA OF BORON CONCENTRA
IN GROUNDWATER ABOVE 2L
VERTICAL EXAGGERATION 5X
VIP 148 RIVER STREET, SUITE 220
GREENVILLE, SOUTH CAROLINA 29601
PHONE [phone]
www.synterraco rp.com
Terra PROJECT
NBM MANAGER:
CRAIG DATE 04/08/2016
PROJECT MANAGER: CT'O' EADY
LAYOUT: FIG G4-4 (SECTION A)
04/12/201610:43 AM 71ule Berp Pro mss.1026 14. Cor
_ A.
(NORTH)
PIPE TRENCH
Z
a
a
U_
�
o
w
J
` ¢
W
ELECTRIC
a SUBSTATION
w
Q
F-
__—REGOLITH
Z
N
LEGEND
GENERALIZED WATER TABLE
® NCDWR WATER SUPPLY WELL OWNER ID
NCDWR WATER SUPPLY WELL ID
BG-01BR MONITORING WELL
TO 233' msl. TOTAL DEPTH ELEVATION OF WELL
0 IN FEET MEAN SEA LEVEL (msl)
FIGURE G44
CONCEPTUAL CROSS-SECTION A -A'
DUKE ENERGY PROGRESS
ROXBORO STEAM ELECTRIC PLANT
1700 DUNNAWAY RD
SEMORA, NORTH CAROLINA
2. Management Re orts Roxboro SECTIONS DWG DE ROXBORO SECTIONS.dw

B
B'
(SOUTH)
(NORTH)
DUKE ENERGY ROXBORO STEAM ELECTRIC PLANT PROPERTY
COMPLIANCE BOUNDARY
0
WASTE BOUNDARY
z
w o
o
Ir uJ w
z
m
M
LINED LANDFILL
0
M O_ N Lu
�G o a a aa—
�
a
av
REGOLITH
g ?�
m
ASH a m
L o
0
REGOLITH ASH Q r
?� ¢
z
COOLING TOWER
TD493'msl.
\
a
a0
o
TD 465' msl.
TD 460 msl.
—
TO 460' msl. ASH —
�'
a ni
o
m o
; >
GENERALIZ ED GROUNDWATER
ASH
�"
\
z
J
¢ ¢
a
FLOW DIRECTION
PROFILE BASED ON HISTORIC ASH PORE WATER
TD
421'
INTAKE CANAL HYCO LAKE
BEDROCK
USGS TOPOGRAPHIC MAP TO 398' msl.
TD ? ?
i
TD 383' msl. ' TO
BEDROCK
391' msl.
BEDROCK
mommono-
—►
GENERALIZED
TD 339' msl.'
GROUNDWATER
FLOW DIRECTION \ ' �
AREA OF BORON CONCENTRATIONS
PROFILE BASED ON HISTORIC
IN GROUNDWATER ABOVE 2L
USGS TOPOGRAPHIC MAP
FORMER SARGENTS
CREEK CHANNEL
TO 253' msl.
--------------
TD 177' msl.
BEDROCK
BEDROCK
LEGEND
GENERALIZED WATER TABLE
NCDWR WATER SUPPLY WELL OWNER ID
® NCDWR WATER SUPPLY WELL ID
BG-13BR MONITORING WELL
TO 253' msl. TOTAL DEPTH ELEVATION OF WELL
IN FEET MEAN SEA LEVEL (msl)
VERTICAL EXAGGERATION
5X
FIGURE G4-5
CONCEPTUAL CROSS-SECTION B-B'
SOURCE INFORMATION:
DUKE ENERGY PROGRESS
148 RIVER STREET, SUITE 220
EXISTING GROUND SURFACE BASED ON A DRAWING PROVIDED BYTHE WSP GROUP, TITLED "ROXBORO FINAL", DATED JUNE 8, 2015.
GREENVPHONE 8ILLE, SOUTH 9CCAROLINA 29601
ROXBORO STEAM ELECTRIC PLANT
HISTORIC GROUND SURFACE BASED ON THE 7-1/2' USGS TOPOGRAPHIC MAP FOR OLIVE HILL, NC DATED 1968, REVISED 1994.
www.synterracorp.com
1700 D U N NAWAY RD
DRAWN BY: CHASTAIN DATE: 03/31/2016
PROJECT MANAGER: CRAIG EADY
MONITORING WELL DATA WAS OBTAINED FROM THE COMPREHENSIVE SITE ASSESSMENT REPORT PREPAREED BYSYNTERRA, DATED SEPTEMBER 2, 2015.
syn����
SENORA CARD LI NA
PRIVATE WATER SUPPLY WELL INFORMATION WAS OBTAINED FROM A LIST PROVIDED BY DUKE ENERGY PROGRESS
LAYOUT: FIG G4-5 (SECTION B)
,NORTH
MONITORING WELL WATER LEVELS WERE COLLECTED BY SYNTERRA ON DECEMBER 5-6, 2015.
04/12/20163:43 PM P:\Duke Energy Progress.1026\14.
Corporate
SU ort\02. Management Reports\Roxboro\SECTIONS\Dwc\DE ROXBORO SECTIONS.dwg

C-
(SOUTH)
w w
p U U
>_ w w U
'LLI
¢ o g z
Lu
w
�„� N w w o
jaz
w
REGOLITH
ITO?
_� TD ? c
GENERALIZED TD ?
GROUNDWATER FLOW 1
MW-17BR
WELL HAS A WATER
LEVEL OF 496" msl.
DG-3
IS AN ARTESIAN WELL
WITH THE GROUND
SURFACE AT 488' msl.
TD
EASTERN EXTENSION
IMPOUNDMENT
WE=465' msl
PROFILE BASED ON AMEC FOSTER
DUKE ENERGY ROXBORO STEAM ELECTRIC PLANT PROPERTY
COMPLIANCE BOUNDARY
WASTE BOUNDARY
LINED LANDFILL
EAST ASH BASIN
ASH
p
w
Q
J
J
w
Q
C
of
G
CS
U
C7
ASH 1 � �
PROFILE BASED ON HISTORIC USGS TOPOGRAPHIC MAP AREA OF BORON CONCENTRATIONS
WHEELER WATER DEPTHS IN GROUNDWATER ABOVE 2L
GENERALIZED GROUNDWATER FLOW DIRECTION
SOURCE INFORMATION:
EXISTING GROUND SURFACE BASED ON A DRAWING PROVIDED BY THE WSP GROUP, TITLED "ROXBORO FINAL", DATED JUNE 8, 2015.
HISTORIC GROUND SURFACE BASED ON THE 7-1/2' USGS TOPOGRAPHIC MAP FOR OLIVE HILL, NC DATED 1968, REVISED 1994.
THE SURFACE BOTTOM IN THE EASTERN EXTENSION IMPOUNDMENT WAS BASED ON INFORMATION OBTAINED FROM THE AMEC FOSTER WHEELER
DOCUMENT TITLED "SUMMARY REPORT FOR INVESTATION RESULTS EAST ASH POND SEDIMENT SAMPLING (ISSUE ROX-115)", DATED SEPTEMBER 16, 2015. ����
MONITORING WELL DATA WAS OBTAINED FROM THE COMPREHENSIVE SITE ASSESSMENT REPORT PREPAREED BY SYNTERRA, DATED SEPTEMBER 2, 2015.
PRIVATE WATER SUPPLY WELL INFORMATION WAS OBTAINED FROM A LIST PROVIDED BY DUKE ENERGY PROGRESSwz z z
MONITORING WELL WATER LEVELS WERE COLLECTED BY SYNTERRA ON DECEMBER 5-6, 2015,
TO
450' msl
0 0
d' d'
J J
p <
w
N
c�
? 0
TD
391' msl.
COOLING
TOWER POND
C'
(NORTH)
LEGEND
GENERALIZED WATER TABLE
FR-0-4-1
NCDWR WATER SUPPLY WELL OWNER ID
DW-26
NCDWR WATER SUPPLY WELL ID
MW-176R
MONITORING WELL
TD 233' msl.
TOTAL DEPTH ELEVATION OF WELL
IN FEET MEAN SEA LEVEL (msl)
VERTICAL EXAGGERATION 5X FIGURE G4-6
CONCEPTUAL CROSS-SECTION C-C'
148 RIVER STREET, SUITE 220 DUKE ENERGY PROGRESS
GREENVILLE, SOUTH CAROLINA 29601
PHONE[phone] ROXBORO STEAM ELECTRIC PLANT
RAW WN BY:JOHNCHA.com 1700 DUNNAWAY RD
PROJECT
MANAGER:
DATE:04/08/2016 SEMORA, NORTH CAROLINA
PROJECT MANAGER: CRAIG EADY
LAYOUT: FIG G4-6 (SECTION Q

AI-AUIHUK: UKANI BUWLN-UFFIUt: PHA
T TT
1
Todomkda
mn
0
w
Hausmanrite
aochros
AIalbandlte
m
OH (a
MnIFi
50
0 2 4 6 8 10 12 14
pH
NOTE
ROXBORO STEAM ELECTRIC PLANT
WATER SUPPLY
FOR TRHE AMS ROXBORO STEAM ELECTRIC PLANT BY SYNTERR ADOPTED FROM APPENDIX C OF THE CAP-2REPORT `' M��" � DUKE ENERGY WELL EVALUATION
DIAGPOURBAIX DIAGRAMS FOR
MANGANESE WITH MEASURED
Eh AND pH FROM SITE
MONITORING WELLS
APRIL2016 FIGURE G5-1

Panel (a): Example Box Plot
Possible Outlier
Upper Whiskers
751h (Percentile
aka 3fd Quartile
"
The "Notch"
55% Confidence Interval of . "•.
: Interquartile (IOR)
the Median
i 150 Percent of Datal
Median +1- 1.57 x IORlna.s .
25th Percentile
aka tst Quamle
Lower Whiskers
NOTES
1. BOX PLOT EXPLANATION DIAGRAM ADOPTED FROM
HTTP://SITES.GOOGLE.COM/SITE/DAV I DSSTATISTICS/HOME/
NOTCHED -BOX -PLOTS.
2. PIPER PLOT ADOPTED FROM CSA REPORT FOR
MARSHALL STEAM STATION BY HDR.
Panel (b): Example Piper Plot
Ash Basin Pwewater
Ash Basin Water
$ All "BR" Wells
4
100 100
an
60
ao uSt 40
zn 20
0
Calf Chlom]d NarDger-NO2 plusNO3
CATIONS ANIONS

ROXBORO
Boron Calcium Chloride
1000000
100000
ai
10000
c
L
1000
c
L)
100 T
,0
1
AB FM RBG WSW AB FM RBG WSW AB FM RBG WSW
NOTES
1. ACRONYMS:
AB =ASH BASIN POREWATER WELL
FM = OTHER FACILITY MONITORNG WELL
RBG = REGIONAL BACKGROUND WELL
WSW = WATER SUPPLY WELL
2. NO REGIONAL BACKGROUND DATA FOR
CHLORIDE, SULFATE, AND TOTAL DISSOLVED
SOLIDS.
Sulfate Total Dissolved Solids
AB FM RBG WSW AB FM RBG WSW

1Barium
000.o
100.0
L
� 10.0
d
U
1.0
0.1
AB FM RBG
NOTE
ACRONYMS:
AB = ASH BASIN POREWATER WELL
FM = OTHER FACILITY MONITORNG WELL
RBG = REGIONAL BACKGROUND WELL
WSW = WATER SUPPLY WELL
WSW
ROXBORO
AB
Cobalt
WSW

100000.0 Dissolved Oxygen
10000.0
1000.0
J
GI
7
Ib
L
100.0
d
c
10.0
1.0
0.1
AB
DISSOLVED
ROXBORO
Iron
TOTAL
TOTAL
DISSOLVED
DISSOLVED
TOTAL
............
TOTAL
FM RBG WSW AB FM RBG WSW AB FM RBG WSW
NOTES
1. ACRONYMS:
AB = ASH BASIN POREWATER WELL
FM = OTHER FACILITY MONITORNG WELL
RBG = REGIONAL BACKGROUND WELL
WSW = WATER SUPPLY WELL
2. NO REGIONAL BACKGROUND DATA FOR
DISSOLVED OXYGEN.

LEGEND
HYCOLAKE i I
Q-�
I NTA-14BR — — —
MW-3BR J
(
GYPSUM
ROXBORO STEAM PAD EXTENT OF — — —
ELECTRIC PLANT UNLINED LANDFILL
GMW-10 IVi c;. - ✓
GMW-6 GMW-11 CW 1 f
�MW-6BR
1966 ABMW78R I
MW-11BR SEMI•ACTIVE I
CW-2G BASIN "W� LINED
OW 96R � ABMW-4BR LANDFILL I NOTES
MW-5BR
ABMW-3BR ABMW66R GMW-7
MW-2BR M J
MW-17BR
®MW-86R ABMW-1BRGMW-8 GMW9
MW-12BR
1973 ACTIVE MW-13BR
`.� ASH BASIN ABMW2BR MW-16BR /
N `R
MW-7BR DUNAY ,�� �
MW.108R r
CW3D
�BG1BR �MW-4BR O
\ MW-15SR
kq Ro MW-186R' I iS{ E° NCH
` 1 I ARC��

10000,1131D0 Panel (a)
■ ! ■
1,aaD,00O
A ■ ■
100,000 • ■
Boron non -detect i ��� MW-01BR
m <50 )1gj L
10,000
ABMW-01BR • Ash Basin PurewaterWell
01 acility Bedrock Well (Uowngradieot)
1 000 - - -
1 10 1DD 1,000 1o,0oo 1o0,00o
Boron Concentration (ug/L)
10,000,000 Panel (b)
■ ■
1000.000 - � ■
GMW49 ■
p ■ ■
m 10W=
Boron non -detect �MW o16R
o <50 gdL 0 - AkOi Basin Pprewater Well
� 10,000 • tarality Bedrock Well (0own8radient) -
ABMW- 18R ptadlityBercck Well (Side Gradient)
0 f acility Bedrock Well (U pg r adierr1)
1 10 100 1,D00 10,wo 10D,000
Baron Concentration {yg(L)
10,aDD,Daa
Panel (c)
— ----------------------t
1
Area 1
CW-01 i ■ ■
u M
1 Oa0 006Gm+
MW-05BR
�.■. �rl
1
1 ■ �`
.
1 �
CW-02jaU 1 ■
1
I____#_______ A_.�
100,000
'_
1
MW-016RR
-03 IAsh Basin Porewater Well
10,000
1
1
*Facility Bedrock Well (Dcw,ngradi ent)
1 ♦ t
1
1 OFaGlity Berctk Well (Side Gradient(
1 ABMW-01BR
i
R©-04
1: 0 Facility Bedmr.k WMI (Upgradient)
1
a Water supply w6l
1,t100
1
10
100 1,00D 10,D00 200,000
Baron Concentration (ug/.LJ
NOTES
1. ONLY WELLS SAMPLED FOR BOTH BORON AND SULFATE ARE PLOTTED.
2. BORON IS BELOW THE REPORTING LIMIT IN RO-04 (20 Ng/L).
3. RO-03 HAS BEEN SAMPLED TWICE WITH BORON DETECTED AT
86 Ng/L (3112/15) AND 8.7 Ng/L (8/19/15).
4. AREA 1 IS DEFINED BY THE DATA CLUSTERING PATTERN OF THE ASH
BASIN POREWATER; AREA 2 IS DEFINED BY THE DATA CLUSTERING
PATTERN OF THE WATER SUPPLY WELLS.

10.000 -
m
4
m 6A00
c
4,000
O
2,000
O
0
no] I*�
Panel
*Ash Basin Porewater Well
* Facility Bedrock Well (Oowngradient) h
•
Boron non -detect
<50 }Ig/L •
_-
1
1 — — —_-. - -------
1
1� A _ AL■_A I
1 10 100 1,000 10,000 100,000
Boron Concentration (ug/L)
10,000
J
m
C'— 8,000
9
b
d 6,000
uo
c
e 4,000
x
O
2,000 -----1
1
1
r
■ I
1 10 100 1,000 10,00() 100,000
Boron Concentration (ug/L)
0
Panel (b)
*Ash Basin Porewater Well
GMW-09 *facility Bedrock Well (powngradlent)
O Ofacility Serock well (Side Gradient)
OF adlity Bedrock Well (Upgradlent)
•
Boron non -detect �
s— � —►
�
1 �
Panel (0)
10,000
P..oron non -detect AAsh Basin Porewater well
5}ig/L
GMW-09 *Facility Bedrock Well(Oowngradient)
B,DoO
QFacllity Berock Well (Side Gradient)
Q 0facility Bedrock Well (Upgradient)
b
RO-04
110-02 ♦ Water Supply well
FiU}-03
m
6,000 .
t
_ 1 GMW-10
c
1
r GMW-07
pa
4,000
j
ire
t
GMW-11
Are
'
2,000
�—
+ MW-01 Area 1
— -------
o
i
S Li
�A�MW-0iBR d l
1
p��_�.a
1 1`
---------._� _�•——�_--—---1
1
10 100 1,000 10,000 100,000
Boron Concentration (ug/L)
1. ONLY WELLS SAMPLED FOR BOTH BORON AND DISSOLVED OXYGEN
ARE PLOTTED.
2. BORON IS BELOW THE REPORTING LIMIT IN RO-02 (<50 pg/L) AND
IN RO-04 (20 pg/L).
3. RO-03 HAS BEEN SAMPLED TWICE WITH BORON DETECTED AT
86 pg/L (3112/15) AND 8.7 pg/L (8/19/15).
4. AREA 1 IS DEFINED BY THE DATA CLUSTERING PATTERN OF THE ASH
BASIN POREWATER; AREA 2 IS DEFINED BY THE DATA CLUSTERING
PATTERN OF THE WATER SUPPLY WELLS.

HYCO LAKE
/
OR01 /// Q_�
I `
(
r_voe� m�
lqw_
LEGEND
0
0
ROXBORO STEAM PAD/ EXTENT OF
ELECTRIC PLANT V UNLINED LANDFILL
ANDFILL � O
O
R016D
O
1966 I ,
SEMI -ACTIVE I
BASIN LINED O NOTES
LANDFILL
R04 J O O
I
4 °
�"R013
R07 ­7•
1973 ACTIVE O R099 : OO
ASH BASIN 4
NNAWAY RD R06
R08 � R015
R02 R03 _ R01k0 a
R05 R012
R010
t•J RD

(a) Ash Basin Porewater Wells Only
EXPLANATION too
♦ Ash Basin Porewater Well
\ I
♦♦
100 0 / `\� \ / \ 0 100
V
\\ I
` /♦
-A—A.-- x--- — — — ---y -- ie--- ---
\� / \ / \ / \ / 100
0 ♦ \� `\/ \� \\/ 100 100
100 0 0
Ca"
CATIONS
NOTE
LOW BORON CONCENTRATIONS FOUND IN THE FACILITY
DOWNGRADIENT BEDROCK WELLS IN THE BLUE CIRCLE,
WHICH COINCIDES A LOWER RELATIVE ABUNDANCE OF
SULFATE AMONG ANIONS.
CI -
ANIONS
(b) Ash Basin Porewater and Downgradient Facility Bedrock Wells
EXPLANATION Too
♦ Ash Basin Porewater Well / \
A Facility Background Well (Downgradicnt) /
AA
`y \/ p`Y/
0 0
/<\
100 0 /p `\ \ I `\ \ 0 100
V
x
A\ / A
\ ppj(/b
`L —
0 0 100 .00 0
too 100 0 0 100
Ca,� CI
CATIONS ANIONS

EXPLANATION
• Water Supply Well
0 L-
100
Ca''
CATIONS
(a) Water Supply Wells
100
CI"
ANIONS
(b) Water Supply Wells and Up- and Side Gradient Fracility Bedrock Wells
EXPLANATION I o0
• Water Supply Well n
■ Facility Background Wcll (Upgradicnt)
❑ Facility Background Well (Side Gradient)
Y d,r
❑ \Y� \ / \Y
•/r A /\
100 0 % \\ I \\ \\ 0 100
v
—_Dv---- 2---y----
/\ e. x
--r'��V/ 9L\k/
\ /\ ■ a /\ / 100
0 0 ❑ \ / \� \ / loo too m \ 0
t00 100 0 0 100
Caz'
CATIONS
Cl-
ANIONS

(a) Roxboro Related Wells
EXPLANATION 100
Water Supply Well n
0'L.
100
G Y / N
A /\
\ I
100 0 /A\ \V / A\ \\ 0 100
v
A
ti --
100
Too 100 �• \/ 0 OL
0 0 100 �o
Ca" CI
CATIONS ANIONS
(b) Regional Groundwater Data Collected in Orange County, North Carolina
(Cunningham and Daniel, 2001)
O
5 x
X do
Q 9
Q� O X k
100 �o ad 0100
SO o©� 20 80
� tiP
00 (GJ r 60 h $ 00 PG
a Q� r
�� �w 9fi
s G� �40
4
�o XX X
!J7 pO ?O O O 4
CALCIUM CHLORIDE, FLUORIDE, NITRITE PLUS NITRATE

(a) Ash Basin Porewater and Downgradient Facility Bedrock Wells
(b) Water Supply Wells and Up- and Side -Gradient Facility Bedrock Wells
EXPLANATION too EXPLANATION too
♦ Ash Basin Porewater Well 0 Water Supply Well
A Facility Background Well (Downgradient) ■ Facility Background Wcll (Upgradient)
\ AA ❑ Facility Background Well (Side Gradient)
\\ \ \ 6 \ /
\\y `/ a\v MW-17BR \y R / 03 \v
so
p� `�/ \,� `\/ MW-16BR `�/ \�\/
0 t 0 0 t o
100 0 \\` ' \\ A' \\` / `\\ o too 00 o i r \ / im,�\1 3 R o too
n \/ \/ A \/
i\ ii \ \ ,MW-A4BR
--- — --- ---
\ ♦
''b \` / \\ i A\4
-A—�;r-- ie--� °-- is--- `L--- --�y " `�--- ! -- ie--- `L---
e ---� 100 \� -- \ /\ / \ /\ ■ a /\ too
` / td \\ / ■ \ \� / \ \\ / \\ ■ `\ \` i
0 too 100 0 0 0 too 100 0
100 0 0 100 100 0 0 100
Cat, Cl-Ca" CI
CATIONS ANIONS CATIONS ANIONS
NOTE
BLUE DIAMOND DEFINES THE GENERAL DATA CLUSTERING
PATTERN OF THE WATER SUPPLYAND FACILITY UPGRADIENT
AND SIDE GRADIENT WELLS.

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
ATTACHMENT G-1
Histograms and Probability Plots for Selected Constituents
APRIL 2016 U'CH

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-1: Roxboro Regional Background Water Supply Well
Data Test for Equal Variances
APRIL 2016 U'CH

ROXBORO FACILITY BACKGROUND MONITORING WELL DATA
Test for Equal Variances: Chromium (VI) - ug/L - T versus sys_loc_code
Method
Null hypothesis All variances are equal
Alternative hypothesis At least one variance is different
Significance level a = 0.05
95% Bonferroni Confidence Intervals for Standard Deviations
sys loc code N StDev CI
BG-01 2 1.20208
BG-01BR 2 0.00000
MW-10BR 4 0.01700 (0.0013981, 0.581)
MW-13BR 3 0.00000
MW-14BR 2 0.00000
MW-15BR 2 0.00000
MW-15D 2 0.42426
MW-16BR 3 0.03066 (0.0000306, 217.467)
MW-17BR 2 0.00000 (
MW-18BR 3 0.00520 (0.0000052, 36.850)
Individual confidence level = 99%
Tests
Method
Multiple comparisons
Levene
Test
Statistic P-Value
- 0.000
1452.02 0.000
* NOTE * The graphical summary cannot be displayed because the multiple comparison
intervals
cannot be calculated.
Test for Equal Variances: Vanadium - ug/L - T versus sys_loc_code
Method
Null hypothesis All variances are equal
Alternative hypothesis At least one variance is different
Significance level a = 0.05
95% Bonferroni Confidence Intervals for Standard Deviations
sys_loc_code N StDev CI
BG-01 5 2.97523 (0.426182, 47.3570)
BG-01BR 4 0.62774 (0.034950, 37.8045)
MW-10BR 5 0.34427 (0.035951, 7.5166)
MW-13BR 6 0.27056 (0.023872, 5.7622)
MW-14BR 5 0.62248 (0.097512, 9.0602)
MW-15BR 4 0.31611 (0.013848, 24.1951)
MW-15D 4 1.38172 (0.093633, 68.3669)
MW-16BR 4 0.54322 (0.036367, 27.2074)
MW-17BR 4 0.66055 (0.030266, 48.3378)

MW-18BR 4 0.38526 (0.064889, 7.6695)
Individual confidence level = 99.50
Tests
Method
Multiple comparisons
Levene
Test
Statistic P-Value
— 0.052
1.85 0.094
Test for Equal Variances: Vanadium - ug/L - T vs sys_loc_code
Multiple comparison intervals for the standard deviation, a = 0.05
BG-01
BG-01BR
I a
MW-IOBR
I —I
MW-13BR
H
O
Vi MW-14BR
1
V
OI MW-15BR
1
MW-15D
MW-16BR
H—�
MW-17BR
f�
MW-18BR
�--1
0 5 10 15 20
If intervals do not overlap, the corresponding stdevs are significantly different.
Multiple Comparisons
P-Value 0.052
Levene's Test
P-Value 0.094

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-2: Histograms and Probability Plots for Background Regional Background
Water Supply Well Data and Facility Background Monitoring Well Data
APRIL 2016 U'CH

Histogram of Background Constituents - Roxboro (Regional)
10 Barium (ug/L Boron (ug/q Cobalt (ug/U
10. 10
5
5
0 0
h ... ups
0 20 40 60 80 100 120 10 20 30 40 50 0.5 LO 1.5 10 15 3.0 3.1
Hexavalent Chromium u Iron(ue/U Lead u L
V 10
a) 10
Cr 5 10 5
LL
° °
0.0 0.3 0.6. 0.9 L2 0 2000 4000 6000 8000 10000 0 4 8 12 16
Manganese u L Nickel u Vanadium u
18 �
20
8 0 B
0 L 0 0
0 200 400 600 800 1000 0 100 200 300 400 0 2 4 6 8 10 12
99
90
�so
a�
10
10
1
Probability Plot of Background Constituents- Roxboro
Normal - 95% CI (Regional)
Barium u 99 Boron u 99Zcobalt90 9050 5010 10
-80 0 80 -fi0 0 60 0 2 4
,/,o
�1 0
-80 a000 -1° 0 10
11 rz 10 AN
...�
1000 U 0 0 8
I
1 000
20-
CT 7
1000 -300
300 -8
40-
Histogram of Background Constituents- Roxboro (Facility)
Barium-u /L-T Boron-u /L-T Cobalt-u /L-T Chromium (VQ-u /L-T
50 30 20
20 —
10- 25 15 30
>� Iron-ug/L Lead -uQ/L
Man -T Nickel-u L-D
V 40-
OJ 20 20
7
� 10 2°- 10
LL
0 0 0-
° vrys ,yo-d' hes peril � o° vti vo- he o-$ ° � � h8 vti8 o a ro �1 w
Vanadium-u /L-T Chloride- -T
20
10
0
o h 10 .,y .IO
Probability Plot of Background Constituents- Roxboro
Normal - 95% CI (Facility)
PRIVLEGED & CONFIDENTIAL —ATTORNEY -CLIENT COMMUNICATION —ATTORNEY
WORK PRODUCT — DO NOT DISTRIBUTE WITHOUT APPROVAL OF COUNSEL

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-3: Roxboro Regional Background Water Supply Well
Data Outlier Test Statistics
APRIL 2016 U'CH

Attachment G-1: Roxboro Regional Background Water Supply Well Data Outlier Test Statistics
Page 1 of 3
Outlier Tests for Selected
Uncensored Variables
User Selected Options
Date/Time of Computation 4/4/2016 5:00:43 PM
From File WorkSheet.xls
Full Precision OFF
Rower's Outlier Test for Barium (ug/L)
Mean 29.18
Standard Deviation 29.9
Number of data 25
Number of suspected outliers 1
Potential Obs. Test
Critical
Critical
# Mean sd outlier Number value
value (5%)
value (1%)
1 29.18 29.29 127 25 3.339
2.82
3.14
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 127
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 127
Rower's Outlier Test for Cobalt (ug/L)
Mean 1.788
Standard Deviation 4.956
Number of data 26
Number of suspected outliers 1
Potential Obs. Test
Critical
Critical
# Mean sd outlier Number value
value (5%)
value (1%)
1 1.788 4.86 25.9 14 4.961
2.84
3.16
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 25.9
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 25.9
Rosner's Outlier Test for Hexavalent Chromium (ug/L)
Mean 0.241
Standard Deviation 0.326
Number of data 26
Number of suspected outliers 1
Potential Obs. Test
Critical
Critical
# Mean sd outlier Number value
value (5%)
value (1%)
1 0.241 0.319 1.2 24 3.003
2.84
3.16
Haley & Aldrich, Inc.
Outlier test stats before removing outlier_regional.xlsx
4/9/2016

Attachment G-1: Roxboro Regional Background Water Supply Well Data Outlier Test Statistics
Page 2 of 3
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 1.2
For 1 % Significance Level, there is no Potential Outlier
Rosner's Outlier Test for Iron (ug/L)
Mean 2808
Standard Deviation 8970
Number of data 26
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 2808 8796 45000 14 4.797 2.84 3.16
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 45000
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 45000
Rosner's Outlier Test for Lead (ug/L)
Mean 2.122
Standard Deviation 3.698
Number of data 25
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 2.122 3.624 16.4 7 3.94 2.82 3.14
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 16.4
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 16.4
Rosner's Outlier Test for Manganese (ug/L)
Mean 213.2
Standard Deviation 432.8
Number of data 26
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 213.2 424.4 1820 14 3.786 2.84 3.16
Haley & Aldrich, Inc.
Outlier test stats before removing outlier_regional.xlsx
4/9/2016

Attachment G-1: Roxboro Regional Background Water Supply Well Data Outlier Test Statistics
Page 3 of 3
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 1820
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 1820
Rosner's Outlier Test for Nickel (ug/L)
Mean 19.49
Standard Deviation 74.51
Number of data 26
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 19.49 73.06 380 8 4.934 2.84 3.16
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 380
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 380
Rower's Outlier Test for Vanadium (ug/L)
Mean 5.962
Standard Deviation 21.77
Number of data 26
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 5.962 21.35 112 14 4.967 2.84 3.16
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 112
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 112
Haley & Aldrich, Inc.
Outlier test stats before removing outlier_regional.xlsx
4/9/2016

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part 4: Roxboro Facility Background Monitoring Well Data Outlier Test Statistics
APRIL 2016 U'CH

Attachment G-1: Roxboro Facility Background Monitoring Well Data Outlier Test Statistics
Page 1 of 3
Outlier Tests for Selected
Uncensored Variables
User Selected Options
Date/Time of Computation 4/8/2016 12:02:59 PM
From File ProUCL input_Facility.xls
Full Precision OFF
Rosner's Outlier Test for Barium - ug/L - T
Mean 92.02
Standard Deviation 87.07
Number of data 59
Number of suspected outliers 1
Potential Obs. Test
Critical Critical
# Mean sd outlier Number value
value (5%) value (1%)
1 92.02 86.33 349 38 2.977
3.193 3.552
For 5% Significance Level, there is no Potential Outlier
For 1 % Significance Level, there is no Potential Outlier
Rosner's Outlier Test for Cobalt - ug/L - T
Mean 3.509
Standard Deviation 7.851
Number of data 46
Number of suspected outliers 1
Potential Obs. Test
Critical Critical
# Mean sd outlier Number value
value (5%) value (1%)
1 3.509 7.765 50.97 19 6.112
3.09 3.45
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 50.97
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 50.97
Dixon's Outlier Test for Chromium (VI) - ug/L - T
Number of Observations = 22
10% critical value: 0.382
5% critical value: 0.43
1 % critical value: 0.514
1. Observation Value 6.2 is a Potential Outlier (Upper Tail)?
Test Statistic: 0.665
For 10% significance level, 6.2 is an outlier.
Haley & Aldrich, Inc.
Outlier test stats_facility.xlsx
4/9/2016

Attachment G-1: Roxboro Facility Background Monitoring Well Data Outlier Test Statistics
Page 2 of 3
For 5% significance level, 6.2 is an outlier.
For 1 % significance level, 6.2 is an outlier.
2. Observation Value 0.03 is a Potential Outlier (Lower Tail)?
Test Statistic: 0.000
For 10% significance level, 0.03 is not an outlier.
For 5% significance level, 0.03 is not an outlier.
For 1 % significance level, 0.03 is not an outlier.
Rosner's Outlier Test for Iron - ug/L - T
Mean 970.7
Standard Deviation 1484
Number of data 59
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 970.7 1471 6140 39 3.514 3.193 3.552
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 6140
For 1 % Significance Level, there is no Potential Outlier
Rosner's Outlier Test for Manganese - ug/L - T
Mean 341.2
Standard Deviation 379
Number of data 59
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 341.2 375.7 1300 23 2.552 3.193 3.552
For 5% Significance Level, there is no Potential Outlier
For 1 % Significance Level, there is no Potential Outlier
Rosner's Outlier Test for Nickel - ug/L - D
Mean 2.751
Standard Deviation 4.43
Number of data 43
Number of suspected outliers 1
Haley & Aldrich, Inc.
Outlier test stats_facility.xlsx 4/9/2016

Attachment G-1: Roxboro Facility Background Monitoring Well Data Outlier Test Statistics
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 2.751 4.378 17.9 7 3.46 3.07 3.41
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 17.9
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 17.9
Rower's Outlier Test for Vanadium - ug/L - T
Mean 3.45
Standard Deviation 5.569
Number of data 45
Number of suspected outliers 1
Potential Obs. Test Critical Critical
# Mean sd outlier Number value value (5%) value (1%)
1 3.45 5.507 22.7 1 3.496 3.09 3.44
For 5% Significance Level, there is 1 Potential Outlier
Potential outliers is: 22.7
For 1 % Significance Level, there is 1 Potential Outlier
Potential outliers is: 22.7
Rosner's Outlier Test for Chloride - ug/L - T
Mean 34703
Standard Deviation 32498
Number of data 59
Number of suspected outliers 1
Potential Obs.
# Mean sd outlier Number
1 34703 32221 130000 57
For 5% Significance Level, there is no Potential Outlier
For 1 % Significance Level, there is no Potential Outlier
Test Critical Critical
value value (5%) value (1%)
2.958 3.193 3.552
Page 3 of 3
Haley & Aldrich, Inc.
Outlier test stats_facility.xlsx
4/9/2016

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
ATTACHMENT G-2
Results of Statistical Computations
APRIL 2016 U'CH

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-1: Roxboro Regional Background Water Supply Well Data GOF Statistics
APRIL 2016 U'CH

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 1 of 10
Goodness -of -Fit Test Statistics for Data Sets with Non -Detects
User Selected Options
Date/Time of Computation 4/4/2016 5:05:44 PM
From File WorkSheet.xls
Full Precision OFF
Confidence Coefficient 0.95
Barium (ug/L)
Num Obs
Num Miss
Num Valid
Detects
NDs
% NDs
Raw Statistics
26
2
24
22
2
8.33%
Number
Minimum
Maximum
Mean
Median
SD
Statistics (Non -Detects Only)
2
5
5
5
5
0
Statistics (Detects Only)
22
2.1
127
30.07
18.7
30.42
Statistics (All: NDs treated as DL value)
24
2.1
127
27.98
16.95
29.91
Statistics (All: NDs treated as DL/2 value)
24
2.1
127
27.77
16.95
30.09
Statistics (Normal ROS Imputed Data)
24
-25.22
127
25.96
16.95
32.27
Statistics (Gamma ROS Imputed Data)
24
0.01
127
27.56
16.95
30.28
Statistics (Lognormal ROS Imputed Data)
24
1.865
127
27.77
16.95
30.09
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
Statistics (Detects Only)
1.086
0.968
27.68
2.877
1.126
0.392
Statistics (NDs = DL)
1.027
0.927
27.23
2.771
1.134
0.409
Statistics (NDs = DL/2)
0.951
0.86
29.19
2.714
1.21
0.446
Statistics (Gamma ROS Estimates)
0.584
0.538
47.22
Statistics (Lognormal ROS Estimates)
2.71
1.219
0.45
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2Normal ROS
Correlation Coefficient R 0.901 0.887 0.891 0.898
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.82
0.911
Data Not Normal
0.19
0.189
Data Not Normal
0.796
0.916
Data Not Normal
0.204
0.181
Data Not Normal
0.802
0.916
Data Not Normal
0.201
0.181
Data Not Normal
0.896
0.916
Data Not Normal
0.171
0.181
Data Appear Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/2aamma RO:
Correlation Coefficient R 0.988 0.988 0.989 0.984
Anderson -Darling (Detects Only)
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
Test value Crit. (0.05) Conclusion with Alpha(0.05)
0.314 0.769
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 2 of 10
Kolmogorov-Smirnov (Detects Only)
0.112
0.19
Detected Data Appear Gamma Distributed
Anderson -Darling (NDs = DL)
0.553
0.771
Kolmogorov-Smirnov (NDs = DL)
0.149
0.183
Data Appear Gamma Distributed
Anderson -Darling (NDs = DL/2)
0.413
0.774
Kolmogorov-Smirnov (NDs = DL/2)
0.131
0.183
Data Appear Gamma Distributed
Anderson -Darling (Gamma ROS Estimates)
0.497
0.798
Kolmogorov-Smirnov (Gamma ROS Est.)
0.124
0.187
Data Appear Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.988 0.982 0.983 0.986
Test value
Crit. (0.05)
Shapiro -Wilk (Detects Only)
0.968
0.911
Lilliefors (Detects Only)
0.109
0.189
Shapiro -Wilk (NDs = DL)
0.954
0.916
Lilliefors (NDs = DL)
0.143
0.181
Shapiro -Wilk (NDs = DL/2)
0.953
0.916
Lilliefors (NDs = DL/2)
0.114
0.181
Shapiro -Wilk (Lognormal ROS Estimates)
0.959
0.916
Lilliefors (Lognormal ROS Estimates)
0.112
0.181
Note: Substitution methods such as DL or DU2 are not recommended.
Hexavalent Chromium (ug/L)
Conclusion with Alpha(0.05)
Data Appear Lognormal
Data Appear Lognormal
Data Appear Lognormal
Data Appear Lognormal
Data Appear Lognormal
Data Appear Lognormal
Data Appear Lognormal
Data Appear Lognormal
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 26 1 25 5 20 80.00%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Number
Minimum
Maximum
Mean
Median
SD
20
0
0.6
0.215
0.015
0.29
5
0.05
1.2
0.371
0.11
0.483
25
0
1.2
0.246
0.03
0.331
25
0
1.2
0.16
0.015
0.259
25
-2.205
1.2
-0.777
-0.846
0.818
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.861 0.852 0.777 0.562
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.751
0.762
Data Not Normal
0.306
0.396
Data Appear Normal
0.727
0.918
Data Not Normal
0.299
0.177
Data Not Normal
0.624
0.918
Data Not Normal
0.269
0.177
Data Not Normal
0.98
0.918
Data Appear Normal
0.0839
0.177
Data Appear Normal
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 3 of 10
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/2aamma RO'
Correlation Coefficient R N/A N/A N/A N/A
Test value
Crit. (0.05) Conclusion with Alpha(0.05)
Anderson -Darling (Detects Only)
0.425
0.695
Kolmogorov-Smirnov (Detects Only)
0.316
0.365 Detected Data Appear Gamma Distributed
Anderson -Darling (NDs = DL)
N/A
N/A
Kolmogorov-Smirnov (NDs = DL)
N/A
N/A
Anderson -Darling (NDs = DL/2)
N/A
N/A
Kolmogorov-Smirnov (NDs = DL/2)
N/A
N/A
Anderson -Darling (Gamma ROS Estimates)
N/A
N/A
Kolmogorov-Smirnov (Gamma ROS Est.)
N/A
N/A
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R N/A N/A N/A N/A
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.929
0.762 Data Appear Lognormal
Lilliefors (Detects Only)
0.268
0.396 Data Appear Lognormal
Shapiro -Wilk (NDs = DL)
N/A
N/A
Lilliefors (NDs = DL)
N/A
N/A
Shapiro -Wilk (NDs = DL/2)
N/A
N/A
Lilliefors (NDs = DL/2)
N/A
N/A
Shapiro -Wilk (Lognormal ROS Estimates)
N/A
N/A
Lilliefors (Lognormal ROS Estimates)
N/A
N/A
Note: Substitution methods such as DL or DU2 are
not recommended.
Iron (ug/L)
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 26 1 25 18 7 28.00%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Statistics (Gamma ROS Imputed Data)
Statistics (Lognormal ROS Imputed Data)
Number
Minimum
Maximum
Mean
Median
SD
7
50
50
50
50
0
18
11
10300
1537
116
2963
25
11
10300
1121
73.7
2585
25
11
10300
1114
73.7
2588
25
-3426
10300
689.3
73.7
2914
25
0.01
10300
1107
73.7
2591
25
2.244
10300
1113
73.7
2588
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
Statistics (Detects Only)
0.373
0.348
4122
5.552
2.088
0.376
Statistics (NDs = DL)
0.349
0.334
3212
5.093
1.911
0.375
Statistics (NDs = DL/2)
0.322
0.31
3458
4.899
2.057
0.42
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 4 of 10
Statistics (Gamma ROS Estimates) 0.175 0.18 6334
Statistics (Lognormal ROS Estimates) 4.742 2.272 0.479
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2Normal ROS
Correlation Coefficient R 0.748 0.683 0.684 0.686
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.57
0.897
Data Not Normal
0.323
0.209
Data Not Normal
0.481
0.918
Data Not Normal
0.336
0.177
Data Not Normal
0.483
0.918
Data Not Normal
0.335
0.177
Data Not Normal
0.72
0.918
Data Not Normal
0.27
0.177
Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO;
Correlation Coefficient R 0.966 0.954 0.958 0.971
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
1.001
0.827
0.249
0.219
Data Not Gamma Distributed
2.728
0.841
0.318
0.188
Data Not Gamma Distributed
2.408
0.847
0.296
0.189
Data Not Gamma Distributed
0.751
0.923
0.175
0.195
Data Appear Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.976 0.932 0.941 0.98
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.94
0.897
Data Appear Lognormal
Lilliefors (Detects Only)
0.185
0.209
Data Appear Lognormal
Shapiro -Wilk (NDs = DL)
0.862
0.918
Data Not Lognormal
Lilliefors (NDs = DL)
0.235
0.177
Data Not Lognormal
Shapiro -Wilk (NDs = DL/2)
0.873
0.918
Data Not Lognormal
Lilliefors (NDs = DL/2)
0.191
0.177
Data Not Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.951
0.918
Data Appear Lognormal
Lilliefors (Lognormal ROS Estimates)
0.159
0.177
Data Appear Lognormal
Note: Substitution methods such as DL or DU2 are
not recommended.
Lead (ug/L)
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 5 of 10
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 26 2 24 19 5 20.83%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Statistics (Gamma ROS Imputed Data)
Statistics (Lognormal ROS Imputed Data)
Statistics (Detects Only)
Statistics (NDs = DL)
Statistics (NDs = DL/2)
Statistics (Gamma ROS Estimates)
Statistics (Lognormal ROS Estimates)
Number
Minimum
Maximum
Mean
Median
SD
5
0.1
1
0.82
1
0.402
19
0.14
16.4
2.382
0.91
4.186
24
0.1
16.4
2.056
1
3.763
24
0.05
16.4
1.971
0.725
3.793
24
-4.777
16.4
1.659
0.835
4.109
24
0.01
16.4
1.913
0.725
3.82
24
0.0808
16.4
1.972
0.827
3.794
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
0.777
0.69
3.063
0.101
1.122
11.06
0.805
0.732
2.554
-0.0156
1.106
-70.83
0.718
0.656
2.744
-0.16
1.2
-7.5
0.473
0.441
4.047
-0.163
1.187
-7.297
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.701 0.666 0.668 0.722
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.511
0.901
Data Not Normal
0.363
0.203
Data Not Normal
0.465
0.916
Data Not Normal
0.381
0.181
Data Not Normal
0.466
0.916
Data Not Normal
0.371
0.181
Data Not Normal
0.638
0.916
Data Not Normal
0.335
0.181
Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma ROc
Correlation Coefficient R 0.913 0.884 0.897 0.928
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
1.829
0.778
0.292
0.206
Data Not Gamma Distributed
2.32
0.78
0.311
0.185
Data Not Gamma Distributed
2.17
0.786
0.281
0.185
Data Not Gamma Distributed
1.188
0.812
0.21
0.189
Data Not Gamma Distributed
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 6 of 10
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.95 0.944 0.951 0.965
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.915
0.901
Data Appear Lognormal
Lilliefors (Detects Only)
0.205
0.203
Data Not Lognormal
Shapiro -Wilk (NDs = DL)
0.904
0.916
Data Not Lognormal
Lilliefors (NDs = DL)
0.218
0.181
Data Not Lognormal
Shapiro -Wilk (NDs = DL/2)
0.92
0.916
Data Appear Lognormal
Lilliefors (NDs = DL/2)
0.177
0.181
Data Appear Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.939
0.916
Data Appear Lognormal
Lilliefors (Lognormal ROS Estimates)
0.175
0.181
Data Appear Lognormal
Note: Substitution methods such as DL or DU2 are
not recommended.
Manganese (ug/L)
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 26 1 25 20 5 20.00%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Statistics (Gamma ROS Imputed Data)
Statistics (Lognormal ROS Imputed Data)
Statistics (Detects Only)
Statistics (NDs = DL)
Statistics (NDs = DL/2)
Statistics (Gamma ROS Estimates)
Statistics (Lognormal ROS Estimates)
Number
Minimum
Maximum
Mean
Median
SD
5
0.5
5
4.1
5
2.012
20
0.86
1030
185.1
34.25
313.5
25
0.5
1030
148.9
24.3
288.6
25
0.25
1030
148.5
24.3
288.8
25
-476.1
1030
100.2
24.3
335.9
25
0.01
1030
148.1
24.3
289
25
0.137
1030
148.5
24.3
288.8
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
0.392
0.366
472.4
3.536
2.106
0.596
0.346
0.331
429.9
3.059
2.154
0.704
0.327
0.314
454.4
2.92
2.296
0.786
0.233
0.231
636.9
2.827
2.44
0.863
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2Normal ROS
Correlation Coefficient R 0.795 0.751 0.751 0.752
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.634
0.905
Data Not Normal
0.373
0.198
Data Not Normal
0.57
0.918
Data Not Normal
0.385
0.177
Data Not Normal
0.571
0.918
Data Not Normal
0.385
0.177
Data Not Normal
0.805
0.918
Data Not Normal
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 7 of 10
Lilliefors (Normal ROS Estimates) 0.316 0.177 Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO;
Correlation Coefficient R 0.957 0.959 0.959 0.955
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.897
0.825
0.199
0.208
Detected Data appear Approximate Gamma Distri
1.537
0.841
0.203
0.188
Data Not Gamma Distributed
1.375
0.846
0.189
0.189
Data Not Gamma Distributed
0.547
0.884
0.126
0.192
Data Appear Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.987 0.981 0.983 0.991
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.961
0.905
Data Appear Lognormal
Lilliefors (Detects Only)
0.112
0.198
Data Appear Lognormal
Shapiro -Wilk (NDs = DL)
0.95
0.918
Data Appear Lognormal
Lilliefors (NDs = DL)
0.15
0.177
Data Appear Lognormal
Shapiro -Wilk (NDs = DL/2)
0.955
0.918
Data Appear Lognormal
Lilliefors (NDs = DL/2)
0.119
0.177
Data Appear Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.971
0.918
Data Appear Lognormal
Lilliefors (Lognormal ROS Estimates)
0.0924
0.177
Data Appear Lognormal
Note: Substitution methods such as DL or DU2 are
not recommended.
Nickel (ug/L)
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 26 1 25 9 16 64.00%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Statistics (Gamma ROS Imputed Data)
Statistics (Lognormal ROS Imputed Data)
Number
Minimum
Maximum
Mean
Median
SD
16
0.5
5
3.031
5
2.306
9
0.53
380
43.93
1.2
126.1
25
0.5
380
17.75
1.2
75.51
25
0.25
380
16.78
1.2
75.69
25
-269.8
380
-59.98
-44.75
130.5
25
0.01
380
17.15
0.01
75.89
25
0.00226
380
16.06
0.316
75.84
K hat
Statistics (Detects Only) 0.239
Statistics (NDs = DL) 0.311
K Star Theta hat Log Mean Log Stdv Log CV
0.234 183.5 0.794 2.104 2.65
0.3 57.12 0.671 1.534 2.286
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx 4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 8 of 10
Statistics (NDs = DL/2) 0.27 0.265 62.06 0.228
Statistics (Gamma ROS Estimates) 0.149 0.157 115.4
Statistics (Lognormal ROS Estimates) -1.486
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.609 0.447 0.439 0.422
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
1.592 6.995
2.669 -1.796
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.403
0.829
Data Not Normal
0.498
0.295
Data Not Normal
0.229
0.918
Data Not Normal
0.507
0.177
Data Not Normal
0.221
0.918
Data Not Normal
0.501
0.177
Data Not Normal
0.869
0.918
Data Not Normal
0.187
0.177
Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma ROc
Correlation Coefficient R 0.93 0.781 0.791 0.878
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
2.045
0.832
0.442
0.306
Data Not Gamma Distributed
4.726
0.849
0.407
0.189
Data Not Gamma Distributed
5.258
0.866
0.459
0.191
Data Not Gamma Distributed
4.395
0.947
0.333
0.197
Data Not Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.813 0.87 0.877 0.975
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.68
0.829
Data Not Lognormal
Lilliefors (Detects Only)
0.378
0.295
Data Not Lognormal
Shapiro -Wilk (NDs = DL)
0.768
0.918
Data Not Lognormal
Lilliefors (NDs = DL)
0.19
0.177
Data Not Lognormal
Shapiro -Wilk (NDs = DL/2)
0.785
0.918
Data Not Lognormal
Lilliefors (NDs = DL/2)
0.253
0.177
Data Not Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.958
0.918
Data Appear Lognormal
Lilliefors (Lognormal ROS Estimates)
0.132
0.177
Data Appear Lognormal
Note: Substitution methods such as DL or DU2 are
not recommended.
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 9 of 10
Vanadium (ug/L)
Num Obs
Num Miss
Num Valid
Detects
NDs
% NDs
Raw Statistics
26
1
25
8
17
68.00%
Number
Minimum
Maximum
Mean
Median
SD
Statistics (Non -Detects Only)
17
0.3
1
0.753
1
0.345
Statistics (Detects Only)
8
1.28
12.6
3.776
2.115
3.819
Statistics (All: NDs treated as DL value)
25
0.3
12.6
1.72
1
2.531
Statistics (All: NDs treated as DL/2 value)
25
0.15
12.6
1.464
0.5
2.626
Statistics (Normal ROS Imputed Data)
25
-18.06
12.6
-4.901
-5.321
7.45
Statistics (Gamma ROS Imputed Data)
25
0.01
12.6
1.215
0.01
2.733
Statistics (Lognormal ROS Imputed Data)
25
0.02
12.6
1.37
0.354
2.668
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
Statistics (Detects Only)
1.72
1.158
2.195
1.011
0.787
0.779
Statistics (NDs = DL)
1.121
1.014
1.534
0.0345
0.939
27.25
Statistics (NDs = DL/2)
0.734
0.672
1.996
-0.437
1.201
-2.749
Statistics (Gamma ROS Estimates)
0.238
0.236
5.098
Statistics (Lognormal ROS Estimates)
-0.945
1.668
-1.766
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.829 0.699 0.702 0.702
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.704
0.818
Data Not Normal
0.263
0.313
Data Appear Normal
0.515
0.918
Data Not Normal
0.327
0.177
Data Not Normal
0.517
0.918
Data Not Normal
0.323
0.177
Data Not Normal
0.98
0.918
Data Appear Normal
0.117
0.177
Data Appear Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO:
Correlation Coefficient R 0.956 0.886 0.925 0.986
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.609
0.726
0.233
0.298
Detected Data Appear Gamma Distributed
1.93
0.77
0.258
0.179
Data Not Gamma Distributed
1.922
0.785
0.323
0.182
Data Not Gamma Distributed
4.009
0.881
0.431
0.192
Data Not Gamma Distributed
4/9/2016

Attachment G-2: Roxboro Regional Background Water Supply Well Data GOF Statistics
Page 10 of 10
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.944 0.933 0.944 0.996
Test value
Crit. (0.05)
Shapiro -Wilk (Detects Only)
0.888
0.818
Lilliefors (Detects Only)
0.204
0.313
Shapiro -Wilk (NDs = DL)
0.871
0.918
Lilliefors (NDs = DL)
0.245
0.177
Shapiro -Wilk (NDs = DL/2)
0.885
0.918
Lilliefors (NDs = DL/2)
0.264
0.177
Shapiro -Wilk (Lognormal ROS Estimates)
0.985
0.918
Lilliefors (Lognormal ROS Estimates)
0.0825
0.177
Note: Substitution methods such as DL or DU2 are not recommended.
Conclusion with Alpha(0.05)
Data Appear Lognormal
Data Appear Lognormal
Data Not Lognormal
Data Not Lognormal
Data Not Lognormal
Data Not Lognormal
Data Appear Lognormal
Data Appear Lognormal
Haley & Aldrich, Inc.
GOF test stats after removing outlier_regional.xlsx
4/9/2016

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
APRIL 2016 U'CH

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 1 of 9
Goodness -of -Fit Test Statistics for Data Sets with Non -Detects
User Selected Options
Date/Time of Computation 4/8/2016 12:05:16 PM
From File ProUCL input_Facility.xls
Full Precision OFF
Confidence Coefficient 0.95
Cobalt - ug/L - T
Num Obs
Num Miss
Num Valid
Detects
NDs
% NDs
Raw Statistics
46
0
46
26
20
43.48%
Number
Minimum
Maximum
Mean
Median
SD
Statistics (Non -Detects Only)
20
0.5
1
0.875
1
0.222
Statistics (Detects Only)
26
0.62
50.97
5.535
2.99
10.05
Statistics (All: NDs treated as DL value)
46
0.5
50.97
3.509
1.065
7.851
Statistics (All: NDs treated as DL/2 value)
46
0.25
50.97
3.319
1.065
7.918
Statistics (Normal ROS Imputed Data)
46
-25.17
50.97
-2.42
1.065
12.45
Statistics (Gamma ROS Imputed Data)
46
0.01
50.97
3.133
1.065
7.99
Statistics (Lognormal ROS Imputed Data)
46
0.0422
50.97
3.262
1.065
7.941
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
Statistics (Detects Only)
0.901
0.822
6.147
1.062
1.012
0.953
Statistics (NDs = DL)
0.811
0.773
4.327
0.525
0.996
1.898
Statistics (NDs = DL/2)
0.629
0.602
5.279
0.224
1.242
5.557
Statistics (Gamma ROS Estimates)
0.275
0.272
11.4
Statistics (Lognormal ROS Estimates)
-0.0332
1.563
-47.1
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.653 0.58 0.593 0.607
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.456
0.92
Data Not Normal
0.351
0.174
Data Not Normal
0.377
0.945
Data Not Normal
0.351
0.131
Data Not Normal
0.392
0.945
Data Not Normal
0.349
0.131
Data Not Normal
0.866
0.945
Data Not Normal
0.175
0.131
Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO;
Correlation Coefficient R 0.865 0.819 0.849 0.915
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Anderson -Darling (Detects Only) 1.687 0.778
Kolmogorov-Smirnov (Detects Only) 0.209 0.177 Data Not Gamma Distributed
Anderson -Darling (NDs = DL) 4.589 0.787
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 2 of 9
Kolmogorov-Smirnov (NDs = DL)
0.258
0.135 Data Not Gamma Distributed
Anderson -Darling (NDs = DL/2)
3.228
0.802
Kolmogorov-Smirnov (NDs = DL/2)
0.191
0.137 Data Not Gamma Distributed
Anderson -Darling (Gamma ROS Estimates)
2.869
0.874
Kolmogorov-Smirnov (Gamma ROS Est.)
0.275
0.143 Data Not Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.959 0.921 0.953 0.994
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.924
0.92
Data Appear Lognormal
Lilliefors (Detects Only)
0.123
0.174
Data Appear Lognormal
Shapiro -Wilk (NDs = DL)
0.851
0.945
Data Not Lognormal
Lilliefors (NDs = DL)
0.225
0.131
Data Not Lognormal
Shapiro -Wilk (NDs = DL/2)
0.903
0.945
Data Not Lognormal
Lilliefors (NDs = DL/2)
0.204
0.131
Data Not Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.984
0.945
Data Appear Lognormal
Lilliefors (Lognormal ROS Estimates)
0.0742
0.131
Data Appear Lognormal
Note: Substitution methods such as DL or DU2 are not recommended.
Chromium (VI) - ug/L - T
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 45 23 22 6 16 72.73%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Statistics (Gamma ROS Imputed Data)
Statistics (Lognormal ROS Imputed Data)
Statistics (Detects Only)
Statistics (NDs = DL)
Statistics (NDs = DL/2)
Statistics (Gamma ROS Estimates)
Statistics (Lognormal ROS Estimates)
Number Minimum Maximum Mean Median SD
16 0.03 0.03 0.03 0.03 1.433E-17
6 0.074 6.2 2.412 1.8 2.468
22 0.03 6.2 0.68 0.03 1.622
22 0.015 6.2 0.669 0.015 1.626
22 -15.94 6.2 -4.946 -5.116 5.886
22 0.01 6.2 0.665 0.01 1.628
22 2.3137E-6 6.2 0.663 0.0048 1.629
K hat K Star Theta hat Log Mean Log Stdv Log CV
0.641 0.432 3.76-0.0734 1.918 -26.14
0.313 0.301 2.168 -2.57 1.824 -0.709
0.264 0.258 2.537 -3.074 2.101 -0.683
0.241 0.239 2.757
-5.248 4.158 -0.792
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2Normal ROS
Correlation Coefficient R 0.956 0.677 0.678 0.686
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.897
0.788
Data Appear Normal
Lilliefors (Detects Only)
0.217
0.362
Data Appear Normal
Shapiro -Wilk (NDs = DL)
0.472
0.911
Data Not Normal
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 3 of 9
Lilliefors (NDs = DL)
0.458
0.189
Data Not Normal
Shapiro -Wilk (NDs = DL/2)
0.474
0.911
Data Not Normal
Lilliefors (NDs = DL/2)
0.455
0.189
Data Not Normal
Shapiro -Wilk (Normal ROS Estimates)
0.99
0.911
Data Appear Normal
Lilliefors (Normal ROS Estimates)
0.0759
0.189
Data Appear Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO:
Correlation Coefficient R 0.948 0.962 0.968 0.971
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.382
0.727
0.227
0.346
Detected Data Appear Gamma Distributed
5.04
0.845
0.436
0.201
Data Not Gamma Distributed
4.806
0.866
0.441
0.203
Data Not Gamma Distributed
4.705
0.876
0.444
0.204
Data Not Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.933 0.755 0.769 0.993
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.847
0.788
Data Appear Lognormal
Lilliefors (Detects Only)
0.265
0.362
Data Appear Lognormal
Shapiro -Wilk (NDs = DL)
0.567
0.911
Data Not Lognormal
Lilliefors (NDs = DL)
0.423
0.189
Data Not Lognormal
Shapiro -Wilk (NDs = DL/2)
0.588
0.911
Data Not Lognormal
Lilliefors (NDs = DL/2)
0.431
0.189
Data Not Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.976
0.911
Data Appear Lognormal
Lilliefors (Lognormal ROS Estimates)
0.0949
0.189
Data Appear Lognormal
Note: Substitution methods such as DL or DL/2 are
not recommended.
Nickel - ug/L - D
Num Obs Num Miss Num Valid Detects NDs % NDs
Raw Statistics 45 2 43 24 19 44.19%
Statistics (Non -Detects Only)
Statistics (Detects Only)
Statistics (All: NDs treated as DL value)
Statistics (All: NDs treated as DL/2 value)
Statistics (Normal ROS Imputed Data)
Statistics (Gamma ROS Imputed Data)
Statistics (Lognormal ROS Imputed Data)
Number Minimum Maximum Mean Median SD
19 0.5 1 0.947 1 0.158
24 1.12 17.9 4.178 1.485 5.568
43 0.5 17.9 2.751 1.14 4.43
43 0.25 17.9 2.541 1.14 4.522
43 -17.5 17.9 -1.383 1.14 7.985
43 0.01 17.9 2.337 1.14 4.622
43 0.0416 17.9 2.454 1.14 4.564
K hat K Star Theta hat Log Mean Log Stdv Log CV
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 4 of 9
Statistics (Detects Only)
0.959
0.867
4.357
0.825
0.984
1.192
Statistics (NDs = DL)
0.99
0.937
2.778
0.428
0.868
2.028
Statistics (NDs = DL/2)
0.74
0.704
3.435
0.122
1.091
8.943
Statistics (Gamma ROS Estimates)
0.287
0.282
8.15
Statistics (Lognormal ROS Estimates)
-0.203
1.459
-7.2
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.758 0.667 0.693 0.716
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.572
0.916
Data Not Normal
0.422
0.181
Data Not Normal
0.454
0.943
Data Not Normal
0.454
0.135
Data Not Normal
0.488
0.943
Data Not Normal
0.434
0.135
Data Not Normal
0.923
0.943
Data Not Normal
0.21
0.135
Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO:
Correlation Coefficient R 0.901 0.86 0.892 0.927
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
4.614
0.774
0.407
0.183
Data Not Gamma Distributed
8.796
0.778
0.398
0.139
Data Not Gamma Distributed
5.722
0.79
0.33
0.14
Data Not Gamma Distributed
3.597
0.867
0.279
0.147
Data Not Gamma Distributed
Lognormal GOF Test Results
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.81 0.804 0.897 0.971
Test value Crit. (0.05) Conclusion with Alpha(0.05)
Shapiro -Wilk (Detects Only)
0.647
0.916
Data Not Lognormal
Lilliefors (Detects Only)
0.368
0.181
Data Not Lognormal
Shapiro -Wilk (NDs = DL)
0.652
0.943
Data Not Lognormal
Lilliefors (NDs = DL)
0.315
0.135
Data Not Lognormal
Shapiro -Wilk (NDs = DL/2)
0.8
0.943
Data Not Lognormal
Lilliefors (NDs = DL/2)
0.214
0.135
Data Not Lognormal
Shapiro -Wilk (Lognormal ROS Estimates)
0.937
0.943
Data Not Lognormal
Lilliefors (Lognormal ROS Estimates)
0.168
0.135
Data Not Lognormal
Note: Substitution methods such as DL or DL/2 are
not recommended.
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 5 of 9
Vanadium - ug/L - T
Num Obs
Num Miss
Num Valid
Detects
NDs
% NDs
Raw Statistics
45
0
45
36
9
20.00%
Number
Minimum
Maximum
Mean
Median
SD
Statistics (Non -Detects Only)
9
0.3
1
0.767
1
0.35
Statistics (Detects Only)
36
0.362
22.7
4.121
1.36
6.054
Statistics (All: NDs treated as DL value)
45
0.3
22.7
3.45
1
5.569
Statistics (All: NDs treated as DL/2 value)
45
0.15
22.7
3.373
0.968
5.607
Statistics (Normal ROS Imputed Data)
45
-9.714
22.7
2.506
1.25
6.528
Statistics (Gamma ROS Imputed Data)
45
0.01
22.7
3.308
0.968
5.644
Statistics (Lognormal ROS Imputed Data)
45
0.0505
22.7
3.363
0.968
5.614
K hat
K Star
Theta hat
Log Mean
Log Stdv
Log CV
Statistics (Detects Only)
0.693
0.654
5.946
0.543
1.301
2.398
Statistics (NDs = DL)
0.685
0.654
5.034
0.354
1.249
3.527
Statistics (NDs = DL/2)
0.615
0.589
5.483
0.215
1.361
6.319
Statistics (Gamma ROS Estimates)
0.41
0.397
8.076
Statistics (Lognormal ROS Estimates)
0.131
1.491
11.38
Normal GOF Test Results
No NDs NDs = DL NDs = DL/2 Normal ROS
Correlation Coefficient R 0.805 0.766 0.768 0.786
Shapiro -Wilk (Detects Only)
Lilliefors (Detects Only)
Shapiro -Wilk (NDs = DL)
Lilliefors (NDs = DL)
Shapiro -Wilk (NDs = DL/2)
Lilliefors (NDs = DL/2)
Shapiro -Wilk (Normal ROS Estimates)
Lilliefors (Normal ROS Estimates)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
0.648
0.935
Data Not Normal
0.328
0.148
Data Not Normal
0.592
0.945
Data Not Normal
0.351
0.132
Data Not Normal
0.595
0.945
Data Not Normal
0.345
0.132
Data Not Normal
0.813
0.945
Data Not Normal
0.28
0.132
Data Not Normal
Gamma GOF Test Results
No NDs NDs = DL NDs = DL/23amma RO:
Correlation Coefficient R 0.96 0.952 0.956 0.965
Anderson -Darling (Detects Only)
Kolmogorov-Smirnov (Detects Only)
Anderson -Darling (NDs = DL)
Kolmogorov-Smirnov (NDs = DL)
Anderson -Darling (NDs = DL/2)
Kolmogorov-Smirnov (NDs = DL/2)
Anderson -Darling (Gamma ROS Estimates)
Kolmogorov-Smirnov (Gamma ROS Est.)
Test value
Crit. (0.05)
Conclusion with Alpha(0.05)
2.165
0.794
0.228
0.153
Data Not Gamma Distributed
3.304
0.796
0.24
0.138
Data Not Gamma Distributed
3.132
0.802
0.217
0.138
Data Not Gamma Distributed
1.224
0.835
0.152
0.141
Data Not Gamma Distributed
Lognormal GOF Test Results
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 6 of 9
No NDs NDs = DL NDs = DL/2 Log ROS
Correlation Coefficient R 0.958 0.955 0.963 0.984
Test value
Crit. (0.05)
Shapiro -Wilk (Detects Only)
0.896
0.935
Lilliefors (Detects Only)
0.134
0.148
Shapiro -Wilk (NDs = DL)
0.893
0.945
Lilliefors (NDs = DL)
0.134
0.132
Shapiro -Wilk (NDs = DL/2)
0.91
0.945
Lilliefors (NDs = DL/2)
0.191
0.132
Shapiro -Wilk (Lognormal ROS Estimates)
0.957
0.945
Lilliefors (Lognormal ROS Estimates)
0.108
0.132
Note: Substitution methods such as DL or DL/2 are not recommended.
Conclusion with Alpha(0.05)
Data Not Lognormal
Data Appear Lognormal
Data Not Lognormal
Data Not Lognormal
Data Not Lognormal
Data Not Lognormal
Data Appear Lognormal
Data Appear Lognormal
Goodness -of -Fit Test Statistics for Uncensored Full Data Sets without Non -Detects
User Selected Options
Date/Time of Computation
4/8/2016 12:05:50 PM
From File
ProUCL input_Facility.xls
Full Precision
OFF
Confidence Coefficient
0.95
Barium - ug/L - T
Raw Statistics
Number of Valid Observations
59
Number of Distinct Observations
49
Minimum
5
Maximum
349
Mean of Raw Data
92.02
Standard Deviation of Raw Data
87.07
Khat
1.471
Theta hat
62.56
Kstar
1.407
Theta star
65.39
Mean of Log Transformed Data
4.145
Standard Deviation of Log Transformed Data
0.929
Normal GOF Test Results
Correlation Coefficient R
0.831
Approximate Shapiro Wilk Test Statistic
0.686
Approximate Shapiro Wilk P Value 4.441
E-16
Lilliefors Test Statistic
0.3
Lilliefors Critical (0.05) Value
0.115
Data not Normal at (0.05) Significance Level
Gamma GOF Test Results
Correlation Coefficient R 0.917
A-D Test Statistic 2.192
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 7 of 9
A-D Critical (0.05) Value 0.769
K-S Test Statistic 0.191
K-S Critical(0.05) Value 0.118
Data not Gamma Distributed at (0.05) Significance Level
Lognormal GOF Test Results
Correlation Coefficient R
0.96
Approximate Shapiro Wilk Test Statistic
0.917
Approximate Shapiro Wilk P Value 4.3342E-4
Lilliefors Test Statistic
0.182
Lilliefors Critical (0.05) Value
0.115
Data not Lognormal at (0.05) Significance Level
Iron - ug/L - T
Raw Statistics
Number of Valid Observations
59
Number of Distinct Observations
59
Minimum
33
Maximum
6140
Mean of Raw Data
970.7
Standard Deviation of Raw Data
1484
Khat
0.766
Theta hat
1266
Kstar
0.739
Theta star
1314
Mean of Log Transformed Data
6.099
Standard Deviation of Log Transformed Data
1.232
Normal GOF Test Results
Correlation Coefficient R
0.769
Approximate Shapiro Wilk Test Statistic
0.594
Approximate Shapiro Wilk P Value
0
Lilliefors Test Statistic
0.333
Lilliefors Critical (0.05) Value
0.115
Data not Normal at (0.05) Significance Level
Gamma GOF Test Results
Correlation Coefficient R
0.947
A-D Test Statistic
2.501
A-D Critical (0.05) Value
0.791
K-S Test Statistic
0.188
K-S Critical(0.05) Value
0.12
Data not Gamma Distributed at (0.05) Significance Level
Lognormal GOF Test Results
Correlation Coefficient R 0.988
Approximate Shapiro Wilk Test Statistic 0.963
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 8 of 9
Approximate Shapiro Wilk P Value 0.152
Lilliefors Test Statistic 0.0982
Lilliefors Critical (0.05) Value 0.115
Data appear Lognormal at (0.05) Significance Level
Manganese - ug/L - T
Raw Statistics
Number of Valid Observations
59
Number of Distinct Observations
54
Minimum
5
Maximum
1300
Mean of Raw Data
341.2
Standard Deviation of Raw Data
379
Khat
0.571
Theta hat
598
Kstar
0.553
Theta star
617.1
Mean of Log Transformed Data
4.741
Standard Deviation of Log Transformed Data
1.803
Normal GOF Test Results
Correlation Coefficient R
0.915
Approximate Shapiro Wilk Test Statistic
0.818
Approximate Shapiro Wilk P Value 1.3554E-9
Lilliefors Test Statistic
0.199
Lilliefors Critical (0.05) Value
0.115
Data not Normal at (0.05) Significance Level
Gamma GOF Test Results
Correlation Coefficient R 0.944
A-D Test Statistic 1.84
A-D Critical (0.05) Value 0.809
K-S Test Statistic 0.152
K-S Critical(0.05) Value 0.122
Data not Gamma Distributed at (0.05) Significance Level
Lognormal GOF Test Results
Correlation Coefficient R
0.952
Approximate Shapiro Wilk Test Statistic
0.877
Approximate Shapiro Wilk P Value 2.4119E-6
Lilliefors Test Statistic
0.193
Lilliefors Critical (0.05) Value
0.115
Data not Lognormal at (0.05) Significance Level
Chloride - ug/L - T
Raw Statistics
Number of Valid Observations 59
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Attachment G-2: Roxboro Facility Background Monitoring Well Data GOF Statistics
Page 9 of 9
Number of Missing Observations 4
Number of Distinct Observations 30
Minimum 11700
Maximum 130000
Mean of Raw Data 34703
Standard Deviation of Raw Data 32498
Khat 1.729
Theta hat 20077
Kstar 1.652
Theta star 21008
Mean of Log Transformed Data 10.14
Standard Deviation of Log Transformed Data 0.743
Normal GOF Test Results
Correlation Coefficient R
0.836
Approximate Shapiro Wilk Test Statistic
0.689
Approximate Shapiro Wilk P Value 6.661E-16
Lilliefors Test Statistic
0.307
Lilliefors Critical (0.05) Value
0.115
Data not Normal at (0.05) Significance Level
Gamma GOF Test Results
Correlation Coefficient R 0.947
A-D Test Statistic 5.203
A-D Critical (0.05) Value 0.766
K-S Test Statistic 0.306
K-S Critical(0.05) Value 0.118
Data not Gamma Distributed at (0.05) Significance Level
Lognormal GOF Test Results
Correlation Coefficient R
0.911
Approximate Shapiro Wilk Test Statistic
0.808
Approximate Shapiro Wilk P Value 4.448E-10
Lilliefors Test Statistic
0.287
Lilliefors Critical (0.05) Value
0.115
Data not Lognormal at (0.05) Significance Level
Haley & Aldrich, Inc.
GOF test stats_facility.xlsx
4/9/2016

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
ATTACHMENT G-3
Method Computation Details
APRIL 2016 U'CH

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-1: Roxboro Regional Background Water Supply Well Data BTVs Statistics
APRIL 2016 U'CH

Attachment G-3: Roxboro Regional Background Water Supply Well Data BTVs Statistics
Page 1 of 6
Background Statistics for Data Sets with Non -Detects
User Selected Options
Date/Time of Computation
4/4/2016 5:06:04 PM
From File
WorkSheet.xls
Full Precision
OFF
Confidence Coefficient
95%
Coverage
95%
Different or Future K Observations
1
Number of Bootstrap Operations
2000
Barium (ug/L)
Total Number of Observations
Number of Distinct Observations
Number of Detects
Number of Distinct Detects
Minimum Detect
Maximum Detect
Variance Detected
Mean Detected
Mean of Detected Logged Data
General Statistics
24
21
22
21
2.1
127
925.2
30.07
2.877
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.309
Number of Missing Observations
Number of Non -Detects
Number of Distinct Non -Detects
Minimum Non -Detect
Maximum Non -Detect
Percent Non -Detects
SD Detected
SD of Detected Logged Data
d2max (for USL)
2
2
1
5
5
8.333%
30.42
1.126
2.644
Gamma GOF Tests on Detected Observations Only
A-D Test Statistic
0.314 Anderson -Darling GOF Test
5% A-D Critical Value
0.769 Detected data appear Gamma Distributed at 5% Significance Level
K-S Test Statistic
0.112 Kolmogrov-Smirnoff GOF
5% K-S Critical Value
0.19 Detected data appear Gamma Distributed at 5% Significance Level
Detected data appear Gamma Distributed at 5% Significance Level
Gamma Statistics on Detected Data Only
k hat (MLE)
1,086 k star (bias corrected MLE) 0.968
Theta hat (MLE)
27.68 Theta star (bias corrected MLE) 31.05
nu hat (MLE)
47.79 nu star (bias corrected) 42.61
MLE Mean (bias corrected)
30.07
MLE Sd (bias corrected)
30.56 95% Percentile of Chisquare (2k) 5.868
Gamma ROS Statistics using Imputed Non -Detects
GROS may not be used when data set has > 50% NDs with many tied observations at multiple DLs
GROS may not be used when kstar of detected data is small such as < 0.1
For such situations, GROS method tends to yield inflated values of UCLs and BTVs
For gamma distributed detected data, BTVs and UCLs may be computed using gamma distribution on KM estimates
Minimum 0.01 Mean 27.56
Maximum 127 Median 16.95
SD 30.28 CV 1.099
k hat (MLE) 0.584 k star (bias corrected MLE) 0.538
Theta hat (MLE) 47.22 Theta star (bias corrected MLE) 51.19
Haley & Aldrich, Inc.
BTV test stats after removing outlier_regional.xlsx 4/9/2016

Attachment G-3: Roxboro Regional Background Water Supply Well Data BTVs Statistics
Page 2 of 6
nu hat (MLE) 28.02 nu star (bias corrected)
25.85
MLE Mean (bias corrected) 27.56 MLE Sd (bias corrected)
37.56
95% Percentile of Chisquare (2k) 4.029 90% Percentile
73.41
95% Percentile 103.1 99% Percentile
175.6
The following statistics are computed using Gamma ROS Statistics on Imputed Data
Upper Limits using Wilson Hilferty (WH) and Hawkins Wixley (HW) Methods
WH HW WH
HW
95% Approx. Gamma UTL with 95% Coverage 153.7 193.3 95% Approx. Gamma UPL 102.6
119.3
95% Gamma USL 191.1 251.6
The following statistics are computed using gamma distribution and KM estimates
Upper Limits using Wilson Hilferty (WH) and Hawkins Wixley (HW) Methods
k hat (KM)
0.891
nu hat (KM)
42.76
WH
HW
WH
HW
95% Approx. Gamma UTL with 95% Coverage 126.8
139.2
95% Approx. Gamma UPL 88.29
92.53
95% Gamma USL 154.5
174.5
Hexavalent Chromium (ug/L)
General Statistics
Total Number of Observations
25
Number of Missing Observations
1
Number of Distinct Observations
8
Number of Detects
5
Number of Non -Detects
20
Number of Distinct Detects
5
Number of Distinct Non -Detects
3
Minimum Detect
0.05
Minimum Non -Detect
0
Maximum Detect
1.2
Maximum Non -Detect
0.6
Variance Detected
0.234
Percent Non -Detects
80%
Mean Detected
0.371
SD Detected
0.483
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL)
2.292
d2max (for USL)
2.663
Normal GOF Test on Detects Only
Shapiro Wilk Test Statistic
0.751
Shapiro Wilk GOF Test
5% Shapiro Wilk Critical Value
0.762
Data Not Normal at 5% Significance Level
Lilliefors Test Statistic
0.306
Lilliefors GOF Test
5% Lilliefors Critical Value
0.396
Detected Data appear Normal at 5% Significance Level
Detected Data appear Approximate Normal at 5% Significance Level
Kaplan Meier (KM) Background Statistics Assuming Normal Distribution
Mean
0.0851
SD
0.246
95% UTL95% Coverage
0.65
95% KM UPL (t)
0.515
90% KM Percentile (z)
0.401
95% KM Percentile (z)
0.491
99% KM Percentile (z)
0.658
95% KM USL
0.741
DU2 Substitution Background Statistics Assuming Normal Distribution
Mean
0.16
SD
0.259
95% UTL95% Coverage
0.754
95% UPL (t)
0.613
90% Percentile (z)
0.492
95% Percentile (z)
0.587
99% Percentile (z)
0.763
95% USL
0.851
DL/2 is not a recommended method. DU2 provided for comparisons and historical reasons
Haley & Aldrich, Inc.
BTV test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-3: Roxboro Regional Background Water Supply Well Data BTVs Statistics
Page 3 of 6
Iron (ug/L)
General Statistics
Total Number of Observations
25
Number of Distinct Observations
18
Number of Detects
18
Number of Distinct Detects
17
Minimum Detect
11
Maximum Detect
10300
Variance Detected 8777819
Mean Detected
1537
Mean of Detected Logged Data
5.552
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.292
Number of Missing Observations 1
Number of Non -Detects
7
Number of Distinct Non -Detects
1
Minimum Non -Detect
50
Maximum Non -Detect
50
Percent Non -Detects
28%
SD Detected
2963
SD of Detected Logged Data
2.088
d2max (for USL) 2.663
Gamma GOF Tests on Detected Observations Only
A-D Test Statistic 1.001 Anderson -Darling GOF Test
5% A-D Critical Value 0.827 Data Not Gamma Distributed at 5% Significance Level
K-S Test Statistic 0.249 Kolmogrov-Smirnoff GOF
5% K-S Critical Value 0.219 Data Not Gamma Distributed at 5% Significance Level
Data Not Gamma Distributed at 5% Significance Level
Gamma Statistics on Detected Data Only
k hat (MLE) 0.373 k star (bias corrected MLE)
0.348
Theta hat (MLE) 4122 Theta star (bias corrected MLE)
4420
nu hat (MLE) 13.42 nu star (bias corrected)
12.52
MLE Mean (bias corrected) 1537
MLE Sd (bias corrected) 2606 95% Percentile of Chisquare (2k)
3.031
Gamma ROS Statistics using Imputed Non -Detects
GROS may not be used when data set has > 50% NDs with many tied observations at multiple DLs
GROS may not be used when kstar of detected data is small such as < 0.1
For such situations, GROS method tends to yield inflated values of UCLs and BTVs
For gamma distributed detected data, BTVs and UCLs may be computed using gamma distribution on KM estimates
Minimum 0.01 Mean
1107
Maximum 10300 Median
73.7
SD 2591 CV
2.342
k hat (MLE) 0.175 k star (bias corrected MLE)
0.18
Theta hat (MLE) 6334 Theta star (bias corrected MLE)
6134
nu hat (MLE) 8.735 nu star (bias corrected)
9.02
MLE Mean (bias corrected) 1107 MLE Sd (bias corrected)
2605
95% Percentile of Chisquare (2k) 1.908 90% Percentile
3338
95% Percentile 5851 99% Percentile
12892
The following statistics are computed using Gamma ROS Statistics on Imputed Data
Upper Limits using Wilson Hilferty (WH) and Hawkins Wixley (HW) Methods
WH HW WH
HW
95% Approx. Gamma UTL with 95% Coverage 7907 9905 95% Approx. Gamma UPL 4543
4982
95% Gamma USL 10940 14873
Haley & Aldrich, Inc.
BTV test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-3: Roxboro Regional Background Water Supply Well Data BTVs Statistics
Page 4 of 6
The following statistics are computed using gamma distribution and KM estimates
Upper Limits using Wilson Hilferty (WH) and Hawkins Wixley (HW) Methods
k hat (KM) 0.193 nu hat (KM) 9.657
WH HW WH HW
95% Approx. Gamma UTL with 95% Coverage 6862 7368 95% Approx. Gamma UPL 4128 4069
95% Gamma USL 9274 10535
Lead (ug/L)
Manganese (ug/L)
General Statistics
Total Number of Observations
24
Number of Missing Observations
2
Number of Distinct Observations
19
Number of Detects
19
Number of Non -Detects
5
Number of Distinct Detects
17
Number of Distinct Non -Detects
2
Minimum Detect
0.14
Minimum Non -Detect
0.1
Maximum Detect
16.4
Maximum Non -Detect
1
Variance Detected
17.52
Percent Non -Detects
20.83%
Mean Detected
2.382
SD Detected
4.186
Mean of Detected Logged Data
0.101
SD of Detected Logged Data
1.122
Critical Values for
Background Threshold Values (BTVs)
Tolerance Factor K (For UTL)
2.309
d2max (for USL)
2.644
Nonparametric Distribution Free Background Statistics
Data appear to follow a Discernible Distribution at 5% Significance Level
Nonparametric Upper Limits for BTVs(no distinction made between detects and nondetects)
Order of Statistic, r 24 95% UTL with95% Coverage 16.4
Approximate f 1.263 Confidence Coefficient (CC) achieved by UTL 0.708
95% UPL 15.13 95% USL 16.4
95% KM Chebyshev UPL 18.49
General Statistics
Total Number of Observations
25
Number of Distinct Observations
22
Number of Detects
20
Number of Distinct Detects
20
Minimum Detect
0.86
Maximum Detect
1030
Variance Detected
98302
Mean Detected
185.1
Mean of Detected Logged Data
3.536
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.292
Number of Missing Observations 1
Number of Non -Detects
5
Number of Distinct Non -Detects
2
Minimum Non -Detect
0.5
Maximum Non -Detect
5
Percent Non -Detects
20%
SD Detected
313.5
SD of Detected Logged Data
2.106
d2max (for USL) 2.663
Gamma GOF Tests on Detected Observations Only
A-D Test Statistic 0.897 Anderson -Darling GOF Test
5% A-D Critical Value 0.825 Data Not Gamma Distributed at 5% Significance Level
Haley & Aldrich, Inc.
BTV test stats after removing outlier_regional.xlsx
4/9/2016

Attachment G-3: Roxboro Regional Background Water Supply Well Data BTVs Statistics
Page 5 of 6
K-S Test Statistic 0.199 Kolmogrov-Smirnoff GOF
5% K-S Critical Value 0.208 Detected data appear Gamma Distributed at 5% Significance Level
Detected data follow Appr. Gamma Distribution at 5% Significance Level
Gamma Statistics on Detected Data Only
k hat (MLE) 0.392 k star (bias corrected MLE)
0.366
Theta hat (MLE) 472.4 Theta star (bias corrected MLE)
505.2
nu hat (MLE) 15.68 nu star (bias corrected)
14.66
MLE Mean (bias corrected) 185.1
MLE Sd (bias corrected) 305.8 95% Percentile of Chisquare (2k)
3.138
Gamma ROS Statistics using Imputed Non -Detects
GROS may not be used when data set has > 50% NDs with many tied observations at multiple DLs
GROS may not be used when kstar of detected data is small such as < 0.1
For such situations, GROS method tends to yield inflated values of UCLs and BTVs
For gamma distributed detected data, BTVs and UCLs may be computed using gamma distribution on KM estimates
Minimum 0.01 Mean
148.1
Maximum 1030 Median
24.3
SD 289 CV
1.951
k hat (MLE) 0.233 k star (bias corrected MLE)
0.231
Theta hat (MLE) 636.9 Theta star (bias corrected MLE)
640.3
nu hat (MLE) 11.63 nu star (bias corrected)
11.57
MLE Mean (bias corrected) 148.1 MLE Sd (bias corrected)
307.9
95% Percentile of Chisquare (2k) 2.291 90% Percentile
446.6
95% Percentile 733.4 99% Percentile
1505
The following statistics are computed using Gamma ROS Statistics on Imputed Data
Upper Limits using Wilson Hilferty (WH) and Hawkins Wixley (HW) Methods
WH HW WH
HW
95% Approx. Gamma UTL with 95% Coverage 1059 1317 95% Approx. Gamma UPL 625.3
691.2
95% Gamma USL 1446 1934
The following statistics are computed using gamma distribution and KM estimates
Upper Limits using Wilson Hilferty (WH) and Hawkins Wixley (HW) Methods
k hat (KM)
0.276
nu hat (KM)
13.78
WH
HW
WH
HW
95% Approx. Gamma UTL with 95% Coverage 952.1
1073
95% Approx. Gamma UPL 577.2
594
95% Gamma USL 1282
1531
Nickel (ug/L)
General Statistics
Total Number of Observations
25
Number of Missing Observations
1
Number of Distinct Observations
10
Number of Detects
9
Number of Non -Detects
16
Number of Distinct Detects
8
Number of Distinct Non -Detects
2
Minimum Detect
0.53
Minimum Non -Detect
0.5
Maximum Detect
380
Maximum Non -Detect
5
Variance Detected
15890
Percent Non -Detects
64%
Mean Detected
43.93
SD Detected
126.1
Mean of Detected Logged Data
0.794
SD of Detected Logged Data
2.104
Haley & Aldrich, Inc.
BTV test stats after removing outlier_regional.xlsx 4/9/2016

Attachment G-3: Roxboro Regional Background Water Supply Well Data BTVs Statistics
Page 6 of 6
Vanadium (ug/L)
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.292 d2max (for USL) 2.663
Nonparametric Distribution Free Background Statistics
Data do not follow a Discernible Distribution (0.05)
Nonparametric Upper Limits for BTVs(no distinction made between detects and nondetects)
Order of Statistic, r 25 95% UTL with95% Coverage 380
Approximate f 1.316 Confidence Coefficient (CC) achieved by UTL 0.723
95% UPL 268.7 95% USL 380
95% KM Chebyshev UPL 346.4
General Statistics
Total Number of Observations
25
Number of Missing Observations
1
Number of Distinct Observations
10
Number of Detects
8
Number of Non -Detects
17
Number of Distinct Detects
8
Number of Distinct Non -Detects
2
Minimum Detect
1.28
Minimum Non -Detect
0.3
Maximum Detect
12.6
Maximum Non -Detect
1
Variance Detected
14.58
Percent Non -Detects
68%
Mean Detected
3.776
SD Detected
3.819
Mean of Detected Logged Data
1.011
SD of Detected Logged Data
0.787
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.292 d2max (for USL) 2.663
Normal GOF Test on Detects Only
Shapiro Wilk Test Statistic 0.704 Shapiro Wilk GOF Test
5% Shapiro Wilk Critical Value 0.818 Data Not Normal at 5% Significance Level
Lilliefors Test Statistic 0.263 Lilliefors GOF Test
5% Lilliefors Critical Value 0.313 Detected Data appear Normal at 5% Significance Level
Detected Data appear Approximate Normal at 5% Significance Level
Kaplan Meier (KM) Background Statistics Assuming Normal Distribution
Mean
1.412
SD
2.591
95% UTL95% Coverage
7.351
95% KM UPL (t)
5.933
90% KM Percentile (z)
4.733
95% KM Percentile (z)
5.674
99% KM Percentile (z)
7.44
95% KM USL
8.312
DL/2 Substitution Background Statistics Assuming Normal Distribution
Mean
1.464
SD
2.626
95% UTL95% Coverage
7.482
95% UPL (t)
6.045
90% Percentile (z)
4.829
95% Percentile (z)
5.783
99% Percentile (z)
7.572
95% USL
8.456
DL/2 is not a recommended method. DL/2 provided for comparisons and historical reasons
Haley & Aldrich, Inc.
BTV test stats after removing outlier_regional.xlsx 4/9/2016

Evaluation of Water Supply Wells
in the Vicinity of Duke Energy Coal Ash Basins
Appendix G — Roxboro
Part-2: Roxboro Facility Background Monitoring Well Data BTVs Statistics
APRIL 2016 U'CH

Attachment G-3: Roxboro Facility Background Monitoring Well Data BTVs Statistics
Page 1 of 5
User Selected Options
Date/Time of Computation
From File
Full Precision
Confidence Coefficient
Coverage
Different or Future K Observations
Number of Bootstrap Operations
Barium - ug/L - T
General Statistics
Background Statistics for Data Sets with Non -Detects
4/8/2016 12:08:31 PM
ProUCL input_Facility.xls
OFF
95%
95%
1
2000
Total Number of Observations
59
Number of Distinct Observations
49
Minimum
5
First Quartile
35.5
Second Largest
349
Median
79
Maximum
349
Third Quartile
94
Mean
92.02
SD
87.07
Coefficient of Variation
0.946
Skewness
2.081
Mean of logged Data
4.145
SD of logged Data
0.929
Nonparametric Distribution Free Background Statistics
Data do not follow a Discernible Distribution (0.05)
Nonparametric Upper Limits for Background Threshold Values
Order of Statistic, r
58
95% UTL with 95% Coverage
349
Approximate f
1.526
Confidence Coefficient (CC) achieved by UTL
0.801
95% Percentile Bootstrap UTL with 95% Coverage
349
95% BCA Bootstrap UTL with 95% Coverage
349
95% UPL
330
90% Percentile
157.8
90% Chebyshev UPL
355.4
95% Percentile
329.1
95% Chebyshev UPL
474.7
99% Percentile
349
95% USL
349
Cobalt - ug/L - T
Note: The use of USL to estimate a BTV is recommended only when the data set represents a background
data set free of outliers and consists of observations collected from clean unimpacted locations.
The use of USL tends to provide a balance between false positives and false negatives provided the data
represents a background data set and when many onsite observations need to be compared with the BTV.
General Statistics
Total Number of Observations
46
Number of Missing Observations
0
Number of Distinct Observations
28
Number of Detects
26
Number of Non -Detects
20
Number of Distinct Detects
26
Number of Distinct Non -Detects
2
Minimum Detect
0.62
Minimum Non -Detect
0.5
Maximum Detect
50.97
Maximum Non -Detect
1
Variance Detected
101.1
Percent Non -Detects
43.48%
Mean Detected
5.535
SD Detected
10.05
Mean of Detected Logged Data
1.062
SD of Detected Logged Data
1.012
Critical Values for Background Threshold Values (BTVs)
Haley & Aldrich, Inc.
BTV test stats_facility.xlsx 4/9/2016

Attachment G-3: Roxboro Facility Background Monitoring Well Data BTVs Statistics
Tolerance Factor K (For UTL) 2.079
Page 2 of 5
d2max (for USL) 2.924
Lognormal GOF Test on Detected Observations Only
Shapiro Wilk Test Statistic
0.924 Shapiro Wilk GOF Test
5% Shapiro Wilk Critical Value
0.92 Detected Data appear Lognormal at 5% Significance Level
Lilliefors Test Statistic
0.123 Lilliefors GOF Test
5% Lilliefors Critical Value
0.174 Detected Data appear Lognormal at 5% Significance Level
Detected Data appear
Lognormal at 5% Significance Level
Background Lognormal ROS Statistics Assuming Lognormal Distribution Using Imputed Non -Detects
Mean in Original Scale
3.262
Mean in Log Scale
-0.0332
SD in Original Scale
7.941
SD in Log Scale
1.563
95% UTL95% Coverage
24.93
95% BCA UTL95% Coverage
39.82
95% Bootstrap (%) UTL95% Coverage
43.25
95% UPL (t)
13.73
90% Percentile (z)
7.167
95% Percentile (z)
12.64
99% Percentile (z)
36.68
95% USL
93.34
Statistics using KM estimates on
Logged Data and Assuming Lognormal Distribution
KM Mean of Logged Data
0.338 95% KM UTL (Lognormal)95% Coverage
14.41
KM SD of Logged Data
1.12
95% KM UPL (Lognormal)
9.393
95% KM Percentile Lognormal (z)
8.855
95% KM USL (Lognormal)
37.11
Background DL/2 Statistics Assuming Lognormal Distribution
Mean in Original Scale
3.319
Mean in Log Scale
0.224
SD in Original Scale
7.918
SD in Log Scale
1.242
95% UTL95% Coverage
16.56
95% UPL (t)
10.31
90% Percentile (z)
6.146
95% Percentile (z)
9.652
99% Percentile (z)
22.51
95% USL
47.3
DU2 is not a Recommended Method. DU2 provided for comparisons and historical reasons.
Chromium (VI) - ug/L - T
General Statistics
Total Number of Observations
22
Number of Missing Observations
23
Number of Distinct Observations
7
Number of Detects
6
Number of Non -Detects
16
Number of Distinct Detects
6
Number of Distinct Non -Detects
1
Minimum Detect
0.074
Minimum Non -Detect
0.03
Maximum Detect
6.2
Maximum Non -Detect
0.03
Variance Detected
6.091
Percent Non -Detects
72.73%
Mean Detected
2.412
SD Detected
2.468
Mean of Detected Logged Data
-0.0734
SD of Detected Logged Data
1.918
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.349 d2max (for USL) 2.603
Normal GOF Test on Detects Only
Shapiro Wilk Test Statistic 0.897 Shapiro Wilk GOF Test
5% Shapiro Wilk Critical Value 0.788 Detected Data appear Normal at 5% Significance Level
Lilliefors Test Statistic 0.217 Lilliefors GOF Test
5% Lilliefors Critical Value 0.362 Detected Data appear Normal at 5% Significance Level
Detected Data appear Normal at 5% Significance Level
Haley & Aldrich, Inc.
BTV test stats_facility.xlsx 4/9/2016

Attachment G-3: Roxboro Facility Background Monitoring Well Data BTVs Statistics
Page 3 of 5
Iron - ug/L - T
General Statistics
Manganese - ug/L - T
General Statistics
Kaplan Meier (KM) Background Statistics Assuming Normal Distribution
Mean
0.68
SD
1.584
95% UTL95% Coverage
4.401
95% KM UPL (t)
3.467
90% KM Percentile (z)
2.71
95% KM Percentile (z)
3.286
99% KM Percentile (z)
4.365
95% KM USL
4.803
DU2 Substitution Background Statistics Assuming Normal Distribution
Mean
0.669
SD
1.626
95% UTL95% Coverage
4.489
95% UPL (t)
3.53
90% Percentile (z)
2.753
95% Percentile (z)
3.343
99% Percentile (z)
4.452
95% USL
4.901
DU2 is not a recommended method. DU2 provided for comparisons and historical reasons
Total Number of Observations
59
Minimum
33
Second Largest
6080
Maximum
6140
Mean
970.7
Coefficient of Variation
1.528
Mean of logged Data
6.099
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.02
Number of Distinct Observations
59
First Quartile
227.5
Median
437
Third Quartile
838.5
SD
1484
Skewness
2.511
SD of logged Data
1.232
d2max (for USL) 3.021
Lognormal GOF Test
Shapiro Wilk Test Statistic 0.963 Shapiro Wilk Lognormal GOF Test
5% Shapiro Wilk P Value 0.152 Data appear Lognormal at 5% Significance Level
Lilliefors Test Statistic 0.0982 Lilliefors Lognormal GOF Test
5% Lilliefors Critical Value 0.115 Data appear Lognormal at 5% Significance Level
Data appear Lognormal at 5% Significance Level
Background Statistics assuming Lognormal Distribution
95% UTL with 95% Coverage 5368
95% UPL (t) 3554
95% USL 18403
Total Number of Observations
59
Minimum
5
Second Largest
1220
Maximum
1300
Mean
341.2
Coefficient of Variation
1.111
Mean of logged Data
4.741
Critical Values for Background Threshold Values (BTVs)
90% Percentile (z) 2160
95% Percentile (z) 3380
99% Percentile (z) 7825
Number of Distinct Observations
54
First Quartile
20
Median
272
Third Quartile
546
SD
379
Skewness
1.037
SD of logged Data
1.803
Haley & Aldrich, Inc.
BTV test stats_facility.xlsx 4/9/2016

Attachment G-3: Roxboro Facility Background Monitoring Well Data BTVs Statistics
Page 4 of 5
Tolerance Factor K (For UTL) 2.02 d2max (for USL) 3.021
Nonparametric Distribution Free Background Statistics
Data do not follow a Discernible Distribution (0.05)
Nonparametric Upper Limits for Background Threshold Values
Order of Statistic, r
58 95% UTL with
95% Coverage
1220
Approximate f
1.526 Confidence Coefficient (CC) achieved by UTL
0.801
95% Percentile Bootstrap UTL with 95% Coverage
1228 95% BCA Bootstrap UTL with
95% Coverage
1228
95% UPL
1200
90% Percentile
893
90% Chebyshev UPL
1488
95% Percentile
1146
95% Chebyshev UPL
2007
99% Percentile
1254
95% USL
1300
Nickel - ug/L - D
General Statistics
Total Number of Observations
43
Number of Missing Observations
2
Number of Distinct Observations
23
Number of Detects
24
Number of Non -Detects
19
Number of Distinct Detects
21
Number of Distinct Non -Detects
2
Minimum Detect
1.12
Minimum Non -Detect
0.5
Maximum Detect
17.9
Maximum Non -Detect
1
Variance Detected
31
Percent Non -Detects
44.19%
Mean Detected
4.178
SD Detected
5.568
Mean of Detected Logged Data
0.825
SD of Detected Logged Data
0.984
Critical Values for
Background Threshold Values (BTVs)
Tolerance Factor K (For UTL)
2.097
d2max (for USL)
2.897
Nonparametric Distribution Free Background Statistics
Data do not follow a Discernible Distribution (0.05)
Nonparametric Upper Limits for BTVs(no distinction made between detects and nondetects)
Order of Statistic, r 43 95% UTL with95% Coverage 17.9
Approximate f 2.263 Confidence Coefficient (CC) achieved by UTL 0.89
95% UPL 14.98 95% USL 17.9
95% KM Chebyshev UPL 22.23
Vanadium - ug/L - T
General Statistics
Total Number of Observations
45
Number of Missing Observations
0
Number of Distinct Observations
38
Number of Detects
36
Number of Non -Detects
9
Number of Distinct Detects
36
Number of Distinct Non -Detects
2
Minimum Detect
0.362
Minimum Non -Detect
0.3
Maximum Detect
22.7
Maximum Non -Detect
1
Variance Detected
36.65
Percent Non -Detects
20%
Mean Detected
4.121
SD Detected
6.054
Mean of Detected Logged Data
0.543
SD of Detected Logged Data
1.301
Haley & Aldrich, Inc.
BTV test stats_facility.xlsx
4/9/2016

Attachment G-3: Roxboro Facility Background Monitoring Well Data BTVs Statistics
Page 5 of 5
Chloride - ug/L - T
General Statistics
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.085 d2max (for USL) 2.915
Lognormal GOF Test on Detected Observations Only
Shapiro Wilk Test Statistic 0.896 Shapiro Wilk GOF Test
5% Shapiro Wilk Critical Value 0.935 Data Not Lognormal at 5% Significance Level
Lilliefors Test Statistic 0.134 Lilliefors GOF Test
5% Lilliefors Critical Value 0.148 Detected Data appear Lognormal at 5% Significance Level
Detected Data appear Approximate Lognormal at 5% Significance Level
Background Lognormal ROS Statistics Assuming Lognormal Distribution Using Imputed Non -Detects
Mean in Original Scale
3.363
Mean in Log Scale
0.131
SD in Original Scale
5.614
SD in Log Scale
1.491
95% UTL95% Coverage
25.52
95% BCA UTL95% Coverage
21.78
95% Bootstrap (%) UTL95% Coverage
21.78
95% UPL (t)
14.35
90% Percentile (z)
7.702
95% Percentile (z)
13.24
99% Percentile (z)
36.56
95% USL
87.98
Statistics using KM estimates on
Logged Data and Assuming Lognormal Distribution
KM Mean of Logged Data
0.248 95% KM UTL (Lognormal)95% Coverage
19.26
KM SD of Logged Data
1.3
95% KM UPL (Lognormal)
11.66
95% KM Percentile Lognormal (z)
10.87
95% KM USL (Lognormal)
56.65
Background DL/2 Statistics Assuming Lognormal Distribution
Mean in Original Scale
3.373
Mean in Log Scale
0.215
SD in Original Scale
5.607
SD in Log Scale
1.361
95% UTL95% Coverage
21.17
95% UPL (t)
12.52
90% Percentile (z)
7.094
95% Percentile (z)
11.63
99% Percentile (z)
29.4
95% USL
65.52
DL/2 is not a Recommended Method. DU2 provided for comparisons and historical reasons.
Nonparametric Distribution Free Background Statistics
Data appear to follow a Discernible Distribution at 5% Significance Level
Total Number of Observations 59
Minimum 11700
Second Largest 124000
Maximum 130000
Mean 34703
Coefficient of Variation 0.936
Mean of logged Data 10.14
Critical Values for Background Threshold Values (BTVs)
Tolerance Factor K (For UTL) 2.02
Number of Distinct Observations 30
Number of Missing Observations 4
First Quartile 15000
Median 17000
Third Quartile 41100
SD 32498
Skewness 1.722
SD of logged Data 0.743
d2max (for USL) 3.021
Haley & Aldrich, Inc.
BTV test stats_facility.xlsx 4/9/2016