NC0004987_MSS_Appendix A_20191231

Corrective Action Plan Update December 2019
Marshall Steam Station SynTerra
APPENDIX A
REGULATORY CORRESPONDENCE
Notice of Regulatory Requirements (August 13, 2014)
Background Soil and Groundwater Dataset Review (July 07, 2017)
Approval of Provisional Background Threshold Values, with Attachments (October 11,
2017)
Corrective Action Plan Content for Duke Energy Coal Ash Facilities (April 27, 2018)
Approval of Revised Background Threshold Values, with Attachments (June 15, 2018)
2018 Comprehensive Site Assessment Update Comments (August 17, 2018)
Completion of Permanent Water Supply Requirements Under General Statute
130A.309.211(c1), Marshall Steam Station (October 12, 2018)
Final Classification of the Coal Combustion Residuals Surface Impoundment located at
Duke Energy's Marshall Steam Station (November 13, 2018)
DEQ Coal Combustion Residuals Surface Impoundment Closure Determination,
Marshall Steam Station (April 1, 2019)
DEQ Response to Optimized Interim Monitoring Plans (April 04, 2019)
Final Comprehensive Site Assessment and Corrective Action Plan Approvals for Duke
Energy Coal Ash Facilities (April 5, 2019)
Coal Ash Impoundment Closures at Allen, Belews Creek, Cliffside/Rogers, Marshall,
Mayo and Roxboro Facilities (May 9, 2019)
Duke Energy Interpretation of Corrective Action Plan Content Guidance — NCDEQ
Response and Conditional Approval (September 10, 2019)
Approach to Managing Constituents of Interest for Purposes of Corrective Action Plans
(October 24, 2019)

A 4
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NCDENR
North Carolina Department of Environment and Natural Resources
Pat McCrory John E. Skvarla, III
Governor Secretary
August 13, 2014
CERTIFIED MAIL 7004 2510 0000 3651 1168
RETURN RECEIPT REQUESTED
Paul Newton
Duke Energy
526 South Church Street
Charlotte, NC 28202
Subject: Notice of Regulatory Requirements
Title 15A North Carolina Administrative Code (NCAC) 02L .0106
14 Coal Ash Facilities in North Carolina
Dear Mr. Newton:
Chapter 143, North Carolina General Statutes, authorizes and directs the Environmental
Management Commission of the Department of Environment and Natural Resources to protect
and preserve the water and air resources of the State. The Division of Water Resources (DWR)
has the delegated authority to enforce adopted pollution control rules.
Rule 15A NCAC 02L .0103(d) states that no person shall conduct or cause to be conducted any
activity which causes the concentration of any substance to exceed that specified in 15A NCAC
02L .0202. As of the date of this letter, exceedances of the groundwater quality standards at 15A
NCAC 02L .0200 Classifications and Water Quality Standards Applicable to the Groundwaters
of North Carolina have been reported at each of the subject coal ash facilities owned and
operated by Duke Energy (herein referred to as Duke).
Groundwater Assessment Plans
No later than September, 26 2014 Duke Energy shall submit to the Division of Water Resources
plans establishing proposed site assessment activities and schedules for the implementation,
completion, and submission of a comprehensive site assessment (CSA) report for each of the
following facilities in accordance with 15A NCAC 02L .0106(g):
Asheville Steam Electric Generating Plant
Belews Creek Steam Station
Buck Steam Station
Cape Fear Steam Electric Generating Plant
Cliffside Steam Station
1636 Mail Service Center, Raleigh, North Carolina 27699-1636
Phone: [phone] Internet: www.ncdenr.gov
An Equal Opportunity 1 Affirmative Action Employer— Made in part by recycled paper

Mr. Paul Newton
August 12, 2014
Page 2 of 3
Dan River Combined Cycle Station
H.F. Lee Steam Electric Plant
Marshall Steam Station
Mayo Steam Electric Generating Plant
Plant Allen Steam Station
Riverbend Steam Station
Roxboro Steam Electric Generating Plant
L.V. Sutton Electric Plant
Weatherspoon Steam Electric Plant
The site assessment plans shall include a description of the activities proposed to be completed
by Duke that are necessary to meet the requirements of 15A NCAC 02L .0106(g) and to provide
information concerning the following:
(1) the source and cause of contamination;
(2) any imminent hazards to public health and safety and actions taken to mitigate
them in accordance to 15A NCAC 02L .0106(f);
(3) all receptors, and significant exposure pathways;
(4) the horizontal and vertical extent of soil and groundwater contamination and all
significant factors affecting contaminant transport; and
(5) geological and hydrogeological features influencing the movement,. chemical, and
physical character of the contaminants.
For your convenience, we have attached guidelines detailing the information necessary for the
preparation of a CSA report. The DWR will review the plans and provide Duke with review
comments, either approving the plans or noting any deficiencies to be corrected, and a date by
which a corrected plan is to be submitted for further review and comment or approval. For those
facilities for which Duke has already submitted groundwater assessment plans, please update
your submittals to ensure they meet the requirements stated in this letter and referenced
attachments and submit them with the others.
Receptor Survey
No later than October 14t', 2104 as authorized pursuant to 15A NCAC 02L .0106(g), the DWR is
requesting that Duke perform a receptor survey at each of the subject facilities and submitted to
the DWR. The receptor survey is required by 15A NCAC 02L .0106(g) and shall include
identification of all receptors within a radius of 2,640 feet (one-half mile) from the established
compliance boundary identified in the respective National Pollutant Discharge Elimination
System (NPDES) permits. Receptors shall include, but shall not be limited to, public and private
water supply wells (including irrigation wells and unused or abandoned wells) and surface water
features within one-half mile of the facility compliance boundary. For those facilities for which
Duke has already submitted a receptor survey, please update your submittals to ensure they meet
the requirements stated in this letter and referenced attachments and submit them with the others.
If they do not meet these requirements, you must modify and resubmit the plans.

Mr. Paul Newton
August 12, 2014
Page 3 of 3
The results of the receptor survey shall be presented on a sufficiently scaled map. The map shall
show the coal ash facility location, the facility property boundary, the waste and compliance
boundaries, and all monitoring wells listed in the respective NPDES permits. Any identified
water supply wells shall be located on the map and shall have the well owner's name and
location address listed on a separate table that can be matched to its location on the map.
Failure to comply with the State's rules in the manner and time specified may result in the
assessment of civil penalties and/or the use of other enforcement mechanisms available to the
State.
We appreciate your attention and prompt response in this matter. If you have any questions,
please feel free to contact S. Jay Zimmerman, Water Quality Regional Operations Section Chief,
at [phone].
2hn
ierely,
E. Skvarla, III
Attachment enclosed
cc: Thomas A. Reeder, Director, Division of Water Resources
Regional Offices — WQROS
File Copy

Water Resources
Environmental Quality
July 7, 2017
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. JAY ZIMMERMAN
Director
Subject: Duke Energy Submittal - Background Soil and Groundwater Statistical Methodology for
14 Duke Energy Facilities a -mails submitted May 26, 2017
Dear Mr. Draovitch:
The North Carolina Department of Environmental Quality (DEQ) has received and reviewed the May 26,
2017 a -mails from Duke Energy providing background soil and groundwater datasets. These site -specific
data were compiled following direction provided in an April 28, 2017 letter from DEQ to address technical
concerns related to site assessment and corrective action along with revisions to the Statistical Methods for
Developing Reference Background Concentrations for Groundwater and Soil at Coal Ash Facilities (HDR
Engineering, Inc. and Synterra Corporation, January 2017) technical memorandum (TM).
Attached are reviews of the soil and groundwater datasets for each Duke Energy coal ash facility. These
reviews identify data that are appropriate for inclusion in the statistical analysis to determine background
threshold values for both media following the methodology outlined in the TM. Additional requirements
related to soil and groundwater background determinations are specified for each facility. With approval
of these background datasets, preliminary background determinations for each media are expected to be
completed and provided within 30 days of receipt of this letter for those facilities that will submit
Comprehensive Site Assessments (CSAs) by October 31, 2017. For all other facilities that will submit
CSAs later, preliminary background determinations for each media are due within 60 days of receipt of this
letter.
If you have any questions, please feel free to contact Steve Lanter at [phone].
Sincerely,
S. Jayinlerman, P.G., Director
Division of Water Resources
Attachments: DEQ Background Dataset Reviews for the 14 coal ash facilities
cc: WQROS Regional Offices
WQROS Central File Copy
State of North Carolina I Environmental Quality I Division of Water Resources
Water Quality Regional Operations Section
1636 Mail Service Center I Raleigh, North Carolina 27699-1636
919-707-9129

Allen Steam Station
Groundwater
• The following background wells are appropriate for use:
o BG-lS, BG-2S/D, BG-4S/DBR, GWA-19S, GWA-21SBR, GWA-23S, and
GWA-26S/D
• The following background wells are NOT appropriate for use:
o BG-lD — Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
o BG-2BR — Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included. (Note: while there does
appear to be a topographic divide additional evaluation is needed to determine if
this is just a shallow divide or if it is indeed a divide for all flow layers.)
o AB-4S/DBR — Groundwater elevations below the nearest pond elevation has been
observed in several sampling events since installation of AB-4S/D. Due to the
potential for groundwater flow from the basin toward/through the well cluster this
location should NOT be considered a background location. AB-4BR should also
NOT be considered a background location (potential vertical migration from the
unconsolidated zone). (Note: Duke will evaluate further regarding pond elevation
utilized for assessment.)
o GWA-21D —Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
• All identified sample event dates are appropriate for use.
• The dataset for the shallow flow layer meets the minimum requirement of 10 samples after
excluding samples.
• The dataset for the deep flow layer does NOT meet the minimum requirement of 10
samples after excluding samples. Additional samples are require .
• The dataset for the bedrock flow layer does NOT meet the minimum requirement of 10
samples after excluding samples. Only 4 valid samples, but when additional evaluation
regarding nearest pond elevation used for the AB-4S/DBR locations is provided additional
samples may be available for inclusion.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
• The following background samples are appropriate for use:
o BG-lD (1.0-2.0), BG-lD (9.0-10.5), BG-1D (19.0-20.5), BG-lD (45-50), BG-2D
(1.0-2.5), BG-2D (8.5-10.0), BG-2D (18.0-20.0), BG-3D (1-2.5), BG-3D (13.5-
15), BG-3D (18.5-20), GWA-14D (10.0-12.0), GWA-8D (38.5-40), and GWA-8D
(48.5-50)
• The following background samples are NOT appropriate for use:
o GWA-15D —Sample is at or immediately adjacent to the waste boundary west of
the ash storage area and was also collected in fill material (according to boring log).
Allen Steam Station Pagel of 2

o GWA-5D —Sample is at or immediately adjacent to the waste boundary east of the
ash basin (immediately downgradient) and was also collected in fill material
(according to the boring log).
• The dataset meets minimum requirement of 10 samples after excluding samples.
• The reporting limits for Antimony and Thallium were above the IHSB PSRG Protection of
Groundwater values. Therefore, the number of useable values in the background dataset
is severely limited for these constituents. Additional samples analyzed at a lower detection
limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Allen Steam Station Page 2 of 2

Asheville Steam Electric Plant
Groundwater
• All identified background wells are appropriate for use.
o MW-101 CB-01, CB-09, CB-09SL, NM-24S, CB-011), AMW-03B, and CB-09BR
o Duke Energy recommended adding wells GW-I, GW-1D, and GW-1BR to the
background dataset. Based on a review of the information provided, these wells
may be added to the background dataset. If these wells are added, the new raw
background dataset should be re -submitted to DWR.
• The datasets for each flow layer meets the minimum requirement of at least 10 samples.
• All identified sample event dates are appropriate for use.
• All identified outliers are acceptable and should be removed from the background dataset.
o If GW-1, GW-ID, and GW-1BR are added to the background dataset then re -test
the new dataset for outliers and re -submit to the DWR, including strikethroughs of
outliers and other unusable data (e.g high pH, high turbidity, autocorrelated data.
Soil
• The following background samples are appropriate for use:
o CB-01 SB (7-8), CB-01 SB (30-31), CB-09 SB (1-2), CB-09 SB (25-27), GW-01
SB (1-2), MW-11SB (1.5-2), MW-12 SB (1.5-2), MW-13SB (1.5-2), MW-13SB
(14.5-15), MW-14SB (1.5-2), MW-22 (1-2), MW-23BR (2-3), and NM-24SB (1-
2)
• The following background samples are NOT appropriate for use:
o MW-08 and MW-09 — Samples are at or immediately adjacent to the waste
boundary and should not be used as background locations, even though the samples
were collected above the seasonal high water table.
o CB-08, MW-03, MW-05, and MW-07 — Downgradient of site contamination.
o MW-13SB (22-22.5) — Sample was collected 3-feet below the water table and
should not be used.
• The dataset meets the minimum requirement of at least 10 samples after excluding samples.
• The reporting limits for Antimony, Thallium, and Selenium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the
background dataset is severely limited for these constituents. Additional samples analyzed
at a lower detection limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Asheville Steam Electric Plant Page 1 of 1

Belews Creek Steam Station
Groundwater
• All identified background wells are appropriate for use:
o BG-2S, BG-3S, MW-202S, MW-3, BG-1D, BG-2D, BG-3D, BG-202D, BG-2BR-
A, and MW-202BR
• The datasets for the shallow and deep flow layers meet the minimum requirement of 10
samples.
• The dataset for the bedrock flow layer does NOT meet the minimum requirement of 10
samples. Additional samples are required.
• All identified sample event dates are appropriate for use.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
• All identified background samples are appropriate for use:
o BG-1D (1-2), BG-1D (11), BG-1D (21), BG-lD (31), BG-2D (1-2), BG-2D (10-
12), BG-2D (20-22), BG-2D (30-32), BG-3S (1-2), BG-3S (10-12), BG-3S (20-
22), GWA-3D (34-35.5), GWA 4S (45-47), GWA-12D (10-12), GWA-12D (15-
17), GWA-12D (20-22), and GWA-12D (25-27)
• The dataset meets the minimum requirement of 10 samples.
• The reporting limits for Antimony, Thallium, and Selenium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the
background dataset is severely limited for these constituents. Additional samples analyzed
at a lower detection limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Belews Creek Steam Station Page 1 of 1

Buck Combined Cycle Station
Groundwater
• The following background wells are appropriate for use.
o BG-18, BG-2S/D, BG-3SBRU, NM-6S/D, GWA-lS, MW-613R, and MW-8S/D
• The following background wells are NOT appropriate for use:
o BG-1D/BR— Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
o BG-2BR — Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
o MW-8BR — Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
• All identified sample event dates are appropriate for use.
• The datasets for each flow layer meets the minimum requirement of 10 samples after excluding
samples.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
The following background samples are appropriate for use:
o BG-lD (1-2), BG-1D (9.8-11.2), BG-1D (16.4-17.9), BG-2D (2), BG-2D (10-11.5),
BG-2D (13.5-15), BG-3BRU (1-2), BG-3BRU (10-10.5), BG-3BRU (20-20.5), GWA-
lOD (3.0), and GWA-11D (19-20.5)
The following background samples are NOT appropriate for use:
o GWA-11) — Sample was collected from 0.3-0.6 ft. bgs. Per IHSB Guidance, these
samples were taken too shallow.
o GWA-6BRU — Sample is located downgradient of the Cells 2 and 3 and within 1 foot
of the water table.
o GWA-7D — Sample is located downgradient of the Cells 2 and 3 and within 1 foot of
the water table.
o GWA-91) — Sample is located downgradient of Cell 1, both sample intervals were
collected in fill material (according to boring log) and one sample interval was
collected within 1 foot of the water table.
o GWA-12S —Sample is located downgradient of the ash basin.
o GWA-22D — Sample is located downgradient of Cell 1 and sample interval was
collected in fill material (according to boring log).
• The dataset meets minimum requirement of 10 samples after excluding samples.
• The reporting limits for Antimony, Thallium, and Selenium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the background
dataset is severely limited for these constituents. Additional samples analyzed at a lower
detection limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing fill
should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Buck Combined Cycle Station Page 1 of 1

Cane Fear Steam Electric Plant
Groundwater
• All identified background wells are appropriate for use:
o MW-15SU, MW-15SL, MW-16S, MW-09, MW-9BR, MW-15BR, and MW-16BR
• The datasets for all flow layers meet the minimum requirement of 10 samples.
• The following sample event dates are NOT appropriate for use:
o MW-15BR
■ 3/2/16 — Less than 60 days from previous sample.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
• The following background samples are appropriate for use:
o BG-01(Geosyntec)(2.0-2.5), BG-02(Geosyntec)(2.0-2.5), BG-03(Geosyntec)(2.0-
2.5), MW-09 SB(2-3), MW-09 SB (6-7), and MW-22 SB (3-4)
• The following background samples are NOT appropriate for use:
o MW-05BR SB(0-2), MW-09 SB(0-2), MW-l0BR SB(0-2), MW-12BR SB(0-2),
MW-15 SB(0-2), MW-20 SB(0-2), MW-22 SB(0-2), and MW-23 SB(0-2) — Per
IHSB Guidance, these samples were taken too shallow.
o BG-04(Geosyntec)(2.0-2.5) and BG-05(Geosyntec)(2.0-2.5) — Samples taken
down -gradient of 1985 Ash Pond.
• The dataset does NOT meet the minimum requirement of 10 samples. Additional samples
are required.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Cape Fear Steam Electric Plant Page 1 of I

James E. Rogers Energy Complex
Groundwater
• All identified background wells are appropriate for use.
o BG-1S, CCPMW-1S, MW-305, MW-325, GWA-245, GWA-255, GWA-30S, BG-
1D, MW-24D, MW-32D, GWA-24D, MW-32BR, CCPMW-ID, MW-24DR,
GWA-24BR, GWA-30BR, MW-22BR, and MW-22DR
• The datasets for all flow layers meet the minimum requirement of 10 samples.
• All identified sample event dates are appropriate for use.
• The following outliers are NOT appropriate for use and should be removed from the
background dataset:
Soil
o Total Dissolved Solids — 10,700,000 ug/L (saprolite)
o Total Dissolved Solids — 4,410,000 ug/L (saprolite)
o Total Dissolved Solids—407,000 ug/L (transition zone)
o Total Dissolved Solids—116,000 ug/L (transition zone)
o Iron — 31200 ug/L (transition zone)
o Vanadium — 3 ug/L (transition zone)
The following background samples are appropriate for use:
o BG-ID (3.5-5), BG-ID (8.5-10), BG-2D (3.5-5), BG-2D (8.5-10), BG-2D (18.5-
20), BG-2D (28.5-30), MW-30D (3.5-5.5), MW-30D (8.5-10), MW-30D (18.5-20),
MW-30D (28.5-30), MW-32D (3.5-5), MW-32D (8.5-10), MW-32D (18.5-20),
MW-32S (22.5-24), MW-42D (28.5-30), and GWA-25D (8.5-10)
The following background samples are NOT appropriate for use:
o BG-lS (3.5-5), BG-IS (8.5-10), MW-30S (4-5), MW-30S (9-10), MW-30S (19-
20), and MW-30S (28-29), — Only analyzed for TOC.
o GWA-1 OD — Located at or immediately adjacent to the waste boundary at Units 1-
4 basin.
o GWA-31D (7), GWA-31D (8.7), and GWA-31BR — Located at or immediately
adjacent to and downgradient of the waste boundary at Unit 5 basin and are adjacent
to a road and parking lot.
o MW-38D (33.5-35) — This location is downgradient of the Unit 5 Inactive Ash
Basin and adjacent to the Broad River.
o GWA-3D (48.5-50) — Location is downgradient of the Unit 5 Inactive Ash Basin.
o GWA-12BRU (20-23.5) — Location is immediately downgradient of Units 1-4
Inactive Ash Basin. May be close to water table and is near the Broad River.
o GWA-21BRU (5) — This sample may be immediately above the water table and
more importantly, the location is potentially downgradient of a basin and is situated
adjacent to the Broad River where there a potentially significant fluctuations of
water levels by a discharge point.
o GWA-22S (3-5) — Location is side gradient of the Active Ash Basin and adjacent
to the Broad River. The sample was collected within the screen interval of the well.
James E. Rogers Energy Complex Page 1 of 2

o GWA-27D (13.5-15) and GWA-27D (24.9) — Location is adjacent to and
downgradient of the impoundment. The sample was collected within the screened
interval of the well.
o NM-40BRU (3.5-5) — Location is adjacent to and downgradient of the Unit 5
Inactive Ash Basin and near the Broad River, and the sample was collected from
within the screened interval.
o GWA-61) (28.5-30) — Location is immediately downgradient of Unit 5 Inactive Ash
Basin and may be close to water table and is near the Broad River.
• The dataset meets the minimum requirement of 10 samples after excluding samples.
• The reporting limits for Antimony, Thallium, and Selenium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the
background dataset is severely limited for these constituents. Additional samples for these
three parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• The following outlier is NOT appropriate for use and should be removed from the
background dataset:
o MW-32S (22.5-24)
■ Arsenic — 7.9 mg/kg
James E. Rogers Energy Complex Page 2 of 2

Dan River Combined Cycle Station
Groundwater
• The following background wells are appropriate for use:
o GWA-9S, BG-11), GWA-9D, MW-231), MW-23BR, BG-5S, BG-51), BG-IOS,
BG-101), and BG-10BR
o GWA-9S/D and BG-IOS/D/BR appear to be appropriate for use; however, further
evaluation will be needed to determine whether these wells are truly located up -
gradient of the ash storages.
• The following background wells are NOT appropriate for use:
o GWA-12S/D —It appears that coal ash constituent boron, have been detected in soil
samples taken from this well.
o MW-20S/D — This well could be impacted by groundwater flowing from the
storage 1 area.
• The datasets for the shallow and deep flow layers meet the minimum requirement of 10
samples after excluding samples.
• The dataset for the bedrock flow layer does NOT meet the minimum requirement of 10
samples. Additional samples are required.
• All identified sample event dates are appropriate for use.
o Provisional background threshold value for hexavalent chromium (shallow flow
layer), vanadium (shallow flow layer), and radionuclides (shallow flow layer) are
based on a limited dataset. Additional samples are required.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
The following background samples are appropriate for use:
o BG-513(1-2), GWA-2D(19-20), GWA-9D(20-21.5), GWA-1O1)(9-10), SB-1(1-2),
SB-1(10-11.5), SB-1(15-16.5), SB-1(20-21.5), SB-1(25-26.5), SB-2(1-2), SB-
2(10-11.5), SB-2(20-21.5), SB-2(30-31.25), SB-2(35-36), SB-2(65-65.3), SB-3(1-
2), SB-3(10-11), SB-3(20-21.5), and SB-3(35-36.5)
The following background samples are NOT appropriate for use:
o BG-1D(0-2) — Per IHSB Guidance, this sample was taken too shallow.
o GWA-3D(5-6.5) — Sample taken in close proximity to Ash Storage 1.
o GWA-6S(9-11) — Sample taken down -gradient of Ash Basin Primary Cell
o GWA-10D(19-20) and GWA-10D(25) — Samples taken down -gradient of Ash
Storage 2.
o GWA-1113(10-11.5) — Sample taken down -gradient of Ash Storage 1.
Th dataset meets minimum requirement of 10 samples after excluding samples.
The reporting limits for Antimony, Thallium, and Selenium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the
background dataset is severely limited for these constituents. Additional samples analyzed
at a lower detection limit for these parameters are necessary.
Dan River Combined Cycle Station Page 1 of 2

• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Dan River Combined Cycle Station Page 2 of 2

H. F. Lee Enerev Complex
Groundwater
• The following background wells are appropriate for use:
o AMW-11S, AMW-12S, AMW-13S, AMW-17S, IMW-01S, IMW-03S, AMW-
11BC, AMW-12BC, AMW-13BC, AMW-16BC, IMW-01BC, IMW-02BC, and
IMW-03BC.
o AMW-016BC —The location maybe near the contact with the Black Creek. Please
confirm.
The datasets for the surficial and Cape Fear flow layers meets the minimum requirement
of 10 samples.
The dataset for the Black Creek flow layer does NOT meet the requirement of 10 samples.
Additional samples are required.
The following sample event dates are NOT appropriate for use.
o AMW-12S
■ 3/1/16 — Less than 60 days from previous sample.
o AMW-13S
■ 3/1/16
—Less than 60 days from previous sample.
o AMW-12BC
■ 3/1/16
— Less than 60 days from previous sample.
o AMW-13BC
■ 3/1/16
— Less than 60 days from previous sample.
o IMW-0lBC
■ 3/4/16
— Less than 60 days from previous sample.
o IMW-02BC
• 3/3116 — Less than 60 days from previous sample.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
The following background samples are NOT appropriate for use:
o AMW-12 SB (5-6) — Sample may have been taken within 1 foot of the seasonal
high water table.
o IMW-05 SB (0-2.5) and IMW-05 SB (4-6). This location is in very close proximity
to the southeast corner of Inactive Basin 3 and possibly influenced by the presence
of the ash basin. Per IHSB Guidance, these samples were taken too shallow.
o AMW-18 SB (0-2.5) and AMW-18 SB (3-5). Samples were collected from the
core of the plume migrating from the Active Basin.
o AMW-04 SB (1-2) and AMW-04 SB (4-5). Samples are located at the western end
of the Active Basin, adjacent to the Neuse River.
o AMW-16BC (19-21).
o AMW-11 (0-2), AMW-12 SB (0-2), AMW-13 SB (0-2), and AMW-16BC (0-2) -
Per IHSB Guidance, these samples were taken too shallow.
H. F. Lee Energy Complex Pagel of 2

• The dataset does NOT meet the requirement of 10 samples. Additional samples are
required.
• The reporting limits for Antimony and Thallium were above the IHSB PSRG Protection of
Groundwater values. Therefore, the number of useable values in the background dataset
is severely limited for these constituents. Additional samples analyzed at a lower detection
limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
H. F. Lee Energy Complex Page 2 of 2

Marshall Steam Station
Groundwater
• The following background wells are appropriate for use.
o GWA-4S/D, GWA-5S/D, GWA-6S/D, GWA-8S/D, GWA-12SBR, BG-3BR, MS-
10, MW-4, and MW-4D
• The following background wells are NOT appropriate for use:
o BG-lBR — Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
o GWA-12D — Recently reinstalled due to water quality issues and reevaluation as
background location is necessary before being included.
• The datasets for each flow layer meets the minimum requirement of 10 samples after
excluding samples.
• All identified sample event dates are appropriate for use.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
• The following background samples are appropriate for use:
o BG-3D(1-2), BG-313(10-12), GWA-2DA(3-5), GWA-2DA(8-10), GWA-4D(52-
53), GWA-5D(27.5-29.0), GWA-14S(3-5), and GWA-14S(8-10)
• The following background samples are NOT appropriate for use:
o GWA-1BR — Sample is within the waste boundary downgradient of the ash basin
and coal pile.
o MW-14BR — Sample is located downgradient of the ash basin and Phase I Landfill
(unlined).
• The dataset does NOT meet minimum requirement of 10 samples. Additional background
samples are required.
• The reporting limits for Antimony and Thallium were above the IHSB PSRG Protection of
Groundwater values. Additional samples analyzed at a lower detection limit for these
parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Marshall Steam Station Page 1 of 1

Mayo Steam Electric Plant
Groundwater
• The following background wells are appropriate for use:
o MW-125, BG-02, MW-12D, BG-Ol, MW-13BR, and MW-14BR
• The following background wells are NOT appropriate for use:
o MW-IOBR
• The dataset for the surficial flow layer does NOT meet the minimum requirement of 10
samples. Additional samples are needed.
• The datasets for the transition zone and bedrock flow layers meets the minimum
requirement of 10 samples.
o Provisional background threshold values for radionuclides in the transition zone
flow layer are based on a limited dataset. Additional samples are required.
• The following sample event dates are NOT appropriate for use:
o BG-01
Soil
■ 11/3/2015 —Less than 60 days from previous sample.
■ 1/8/2016 — Less than 60 days from previous sample.
• 9/8/2016 — Less than 60 days from previous sample.
■ 3/28/17 — Less than 60 days from previous sample.
o MW-10BR
■ 1M16 —Less than 60 days from previous sample.
■ 9/7/16 —Less than 60 days from previous sample.
o MW-13BR
■ 1/7/2016 — Less than 60 days from previous sample.
• 9/6/2016 — Less than 60 days from previous sample.
All identified outliers are acceptable and should be removed from the background dataset.
The following background samples are appropriate for use:
o MW-08BR (0.75-1.25), MW-08BR (25.5-26), MW-IOBR (0.75-1.0), MW-12D (1-
2), MW-12D (25-26), SB-01 (1-2), and SB-01 (13.5-14.5)
The following background samples are NOT appropriate for use:
o MW-03BR (0.8-1.25) and MW-15BR (0.5-1) — Samples taken down -gradient of
Ash Basin.
o MW-11BR (0-2) and MW-13BR (0-2) —Per IHSB Guidance, these samples were
taken too shallow.
o SB-02 (0.5-2) and SB-02 (11.0-12.5) — Boring log indicates the presence of coal
ash.
o SB-03 (5-6) and SB-03 (17-18.5) — Boring log indicates the presence of coal ash.
o SB-05 and SB-06. Sample locations were adjacent to the 1981 landfill.
The dataset does NOT meet the minimum requirement of 10 samples. Additional samples
required.
Mayo Steam Electric Plant Page 1 of 2

• The reporting limits for Antimony and Thallium were above the IHSB PSRG Protection of
Groundwater values. Therefore, the number of useable values in the background dataset
is severely limited for these constituents. Additional samples analyzed at a lower detection
limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Mayo Steam Electric Plant Page 2 of 2

Riverbend Steam Station
Groundwater
• The following background wells are appropriate for use:
o BG-lS, MW-7SR, MW-7D, BG-4S, GWA-14S, BG-41), BG-5D, and BG-5BR
o MW-71) was listed under the shallow flow laver. Please re-evaluate.
• The following background wells are NOT appropriate for use:
o GWA-5S — Groundwater water elevations were similar and sometime lower than the
historical water elevation of ash basin. Also, the wells are within compliance boundary
and not far from the waste boundary.
• The datasets for shallow meets the minimum requirement of 10 samples after excluding
samples.
• The datasets for the deep and bedrock flow layers does NOT meet the minimum requirement
of 10 samples. Additional samples are required.
• All identified sample event dates are appropriate for use.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
• The following background samples are appropriate for use:
o BG-lD (5-6), BG-1D (14-15), BG-lD (24-25), BG-2D (3.5-5), BG-2D (48-49), BG-
3D (3-5), BG-31) (18.5-20), BG-3D (23-24), GWA-51) (58.5-60), GWA-6D-1(43.5-
45), GWA-6D-2(48.5-50), GWA-21D(3.5-5), GWA-211)(8.5-10), GWA-21D(18.5-
20), GWA-21D(48.5-50), MW-7BR(43.5-45), and OB-2(38.5-40.0)
• The following background samples are NOT appropriate for use:
o GWA-3D(18.5-19) — Sample taken down -gradient of Ash and Cinder Storage Areas.
o GWA-7S(7.0-8.0) — Sample taken down -gradient of Ash Basins.
o GWA-8D(8.5-10) — Sample taken down -gradient of Ash Basins.
o GWA-9D (1), GWA-10S (8-9), and NM-15D (3.5-5) — Downgradient location and
maybe within the High Seasonal Water Table.
o GWA-20D(40-41.5) — Sample taken in close proximity to Ash Storage Area.
o GWA-22D(38.5-40.0) — Sample taken in close proximity to Ash Storage Area.
o GWA-23D(33.5-35) — Sample taken within the waste boundary of the Ash Storage
Area.
o OB-1(33.5-35.0) — Sample taken inclose proximity to Ash Basin.
• The dataset meets the minimum requirement of 10 samples after excluding samples.
• The reporting limits for Antimony, Thallium, and Selenium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the background
dataset is severely limited for these constituents. Additional samples analyzed at a lower
detection limit for these parameters are necessary
• Please state whether any background sample included fill material. Samples containing fill
should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Riverbend Steam Station Page 1 of 1

Roxboro Steam Electric Plant
Groundwater
• The following background wells are appropriate for use:
o BG-1, MW-15D, MW-18D, BG-01BR MW-IOBR, MW-14BR, MW-15BR, MW-
18BR, and MW-19BRL
• The following background wells are NOT appropriate for use:
o MW-13BR, MW-16BR, and MW-17BR
• The datasets for all flow layers meet the minimum requirement of 10 samples after
excluding samples.
• The following sample event dates are NOT appropriate for use:
o BG-01
■ 9/8/2016 — Less than 60 days from previous sample.
■ 11/16/16 —Less than 60 days from previous sample.
o BG-01BR
■ 7/9/15 — Less than 60 days from previous sample.
o MW-17BR
• 11/10/16 —Less than 60 days from previous sample.
All identified outliers are acceptable and should be removed from the background dataset.
Soil
• The following background samples are appropriate for use:
o MW-08 (14-16), MW-08 (21-23), MW-13BR (22-24), MW-14BR (1-1.25), MW-
14BR (31-31.5), MW-14BR (37.5-38), MW-17 (29-31), MW-18 (31-33), and MW-
18 (37-38)
• The following background samples are NOT appropriate for use:
o MW-07 (0-2), MW-08 (0-2), MW-IOBR (0-2), MW-13BR (0-2), MW-15 (0-2),
MW-16 (0-2), and MW-18 (0-2) — Per IHSB Guidance, these samples were taken
too shallow.
• The dataset does NOT meet the minimum requirement of 10 samples. Additional samples
are required.
• The reporting limits for Antimony and Thallium were above the IHSB PSRG Protection of
Groundwater values. Samples for these two parameters need to be reported below these
values.
• Please state whether any background sample included fill material. Samples containing
fill should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
Roxboro Steam Electric Plant Page 1 of 1

L. V. Sutton Energy Complex
Groundwater
• All identified background wells are appropriate for use:
o MW-05A, MW-0513, MW-3713, MW-0413, MW-05C, MW-08, MW-37C, MW-05CD,
MW-05D, MW-37D, MW-05E, and MW-37E
o Lower Surficial Aquifer — An adequate dataset has been provided for all constituents,
with the exception chromium (VI). Additional samples are planned for collection to
bring the total number of valid chromium (VI) samples to ten by second quarter 2017.
• The datasets for the upper and lower surficial flow layer meet the minimum requirement of 10
samples.
• The dataset for the Upper Peedee flow layer does NOT meet the minimum requirement of 10
samples. Additional samples are planned for collection to bring the total number of valid
samples to ten (second quarter 2017 at the earliest). It was agreed upon to use a pH of less than
or equal to 9.7 S.U. as the upper threshold for these zones in the Peedee aquifer.
• The dataset for the Lower Peedee flow layer does NOT meet the minimum requirement of 10
samples. New and replacement wells have been added to the groundwater monitoring network
(MW-5R-E, MW-8E, MW-41E). Additional samples are planned for collection to bring the
total number of valid samples to 10 (second quarter 2017 at the earliest). It was agreed upon
to use a pH of less than or equal to 9.7 S.U. as the upper threshold for these zones in the Peedee
aquifer.
• All identified sample event dates are appropriate for use.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
• The following background samples are appropriate for use:
o AW-02C (10-11) and MW-37C (4-6)
• The following background sample are NOT appropriate for use:
o AW-01C (0-2), AW-02C (0-2), AW-03C (0-2), AW-04C (0-2), AW-06D (0-2), AW-
07D (0-2), MW-37C (0-2), SMW-01C (0-2), SMW-02C (0-2), SMW-03C (0-2),
SMW-04C (0-2), SMW-05C (0-2), and SMW-06D (0-2) — Per IHSB Guidance, these
samples were taken too shallow.
o AW-05C (4-6) and AW-05C (9-11) —Samples are down -gradient of the ash pond.
• The dataset does NOT meet the minimum requirement of 10 samples. Additional samples are
require .
• The reporting limits for Antimony, Cobalt, and Thallium were above the IHSB PSRG
Protection of Groundwater values. Therefore, the number of useable values in the background
dataset is severely limited for these constituents. Additional samples analyzed at a lower
detection limit for these parameters are necessary.
• Please state whether any background sample included fill material. Samples containing fill
should be omitted from the raw background dataset.
• All identified outliers are acceptable and should be removed from the background dataset.
L. V. Sutton Energy Complex Page 1 of 1

W.H. Weatherspoon Power Plant
Groundwater
• All identified background wells are appropriate for use.
o BW-02S, BW-03S, CCR-101-13G, MW-01, BW-03I, and BW-03D
• The dataset for the surficial flow layer meets the minimum requirement of 10 samples
• The dataset for the Lower Yorktown does NOT meet the minimum requirement of 10
samples. Additional samples are required.
• The dataset for the PeeDee does NOT meet the minimum requirement of 10 samples.
Additional samples are required.
• The following sample event dates are NOT appropriate for use.
o BW-03S
■ 3n116 — Less than 60 days from previous sample.
• All identified outliers are acceptable and should be removed from the background dataset.
Soil
No soil background data was provided. Please coordinate the collection of background
soil data with the DWR Fayetteville Regional Office.
W. H. Weatherspoon Power Plant Page 1 of I

K`
Water Resources
Environmental Quality
October 11, 2017
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. JAY ZIMMERMAN
Director
Subject: Approval of Provisional Background Threshold Values for Allen Steam Station,
Asheville Steam Electric Plant, Buck Combined Cycle Station, Cape Fear Steam
Electric Plant, James E. Rogers Energy Complex, Dan River Combined Cycle
Station, H. F. Lee Energy Complex, Marshall Steam Station, L. V. Sutton Energy
Complex, and W. H. Weatherspoon Power Plant
Dear Mr. Draovitch:
The North Carolina Department of Environmental Quality's Division of Water Resources (DWR)
has reviewed Duke Energy's calculated provisional background threshold values (PBTVs) for soil
and groundwater for the subject facilities. DWR calculated PBTVs based on the vetted
background data in the letter to Duke Energy dated July 7, 2017, using the Revised Statistical
Methods for Developing Reference Background Concentrations for Groundwater and Soil at Coal
Ash Facilities dated May 26, 2017 and any subsequent information provided.
Per 15A NCAC 02L .0202(b)(3), where naturally occurring substances exceed the established
standard, the standard shall be the naturally occurring concentration as determined by the Director.
Therefore, PBTVs that are calculated to be above the 15A NCAC 02L .0202 groundwater
standards or Interim Maximum Allowable Concentrations (IMACs) and accepted by DWR shall
become the enforceable groundwater standard. Otherwise, the enforceable groundwater standards
shall be those listed under 15A NCAC 02L .0202(h) including any effective IMACs.
The attachments document DWR's concurrence/non-concurrence with Duke Energy's calculated
PBTVs for groundwater and soil. For all Duke Energy's calculated PBTVs that DWR finds
acceptable, DWR hereby approves those values. If DWR does not find the Duke Energy's
calculated PBTVs acceptable, justification is provided on the attachments. Duke Energy will be
responsible to provide revised values for DWR to review and approve.
Please note that the approved PBTVs are based on the current data available. DWR recognizes
that, as new data is gathered going forward, the approved PBTVs may be refined. Thus, there will
be need for a periodic review of the data and recalculation of the PBTVs. The timeframes for the
State of North Carolina I Environmental Quality I Division of Water Resources
Water Quality Regional operations Section
1636 Mail Service Center I Raleigh, North Carolina 27699-1636
919-707-9129

periodic review will established by DWR at a later date and any revised PBTVs will be subject to
approval by the DWR's Director.
Along with the specific comments provided on the attachments, DWR offers the following general
comments with regards to the PBTVs
In cases where the PBTVs calculated by Duke Energy use groundwater and soil samples
that have less than 10 samples, the calculated values are acceptable per the guidance
provided in the Revised Statistical Methods for Developing Reference Background
Concentrations for Groundwater and Soil at Coal Ash Facilities dated May 26, 2017.
However, these calculated values may be open to revision by DEQ once additional valid
samples are collected.
Outliers are identified with three statistical lines of evidence: Box Plots, Q-Q Plots, and
95% Significance Levels. Based on these lines of evidence, if Duke Energy chooses not
to exclude an outlier, then additional rationale or justification shall be provided for DWR
review.
The PSRG for Chromium that will be applied shall be the more conservative value for
Chromium (VI) which is 3.8 mg/kg.
If you have any questions, please contact Debra Watts at [phone].
Sincerely,
�-elcc
JSIZiennanP.G., Director
Division of Water Resources
Attachments
cc: WQROS Regional Office Supervisors
WQROS Central File Copy

Allen Steam Station - Groundwater Provisional Background
Threshold Values
Parameter
Reporting
Units
Duke Ener t Calculated PBTVs
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flo% Unit
Flow Unit
Shallow
Deep I
Bedrock
Shallow
Deep
Bedrock
pH
S.U.
5.2 -7.5
6.7.8.4
7.5 - 7.8
6.5-8.5
Acceptable
Acceptable
Acceptable
Deep and bedrock data set is insufficient and must be updated with additional data.
Alkalinity
mg/L
188.773
74
83.4
NE
Acceptable
Acceptable
Acceptable
Aluminum
µg L
427
540
301
NE
Acceptable
Acceptable
Acceptable
Antimony
0.876
0.69
0.5
1
Acceptable
Acceptable
Acceptable
Arsenic
0.42
1.4
_
0.4
10
Acceptable
Acceptable
Acceptable
Barium
pg/L
78
52.4
21
700
Not Acceptable
Acceptable
Acceptable
Duke revised shallow value - 125.4 ug/L. Please revise table accordingly.
Deep and bedrock data set is insufficient and must be updated with additional data.
Beryllium
g/L
0.127
0.2
0.1
4
Acceptable
Acceptable
Acce table
Deep and bedrock data set is insufficient and must be updated with additional data.
Bicarbonate
mg/L
I88.',73
74 1
83.4
NE
Acceptable
Acceptable
Acceptable
Boron
WL
50
50
50
700
Acceptable
Acceptable
Acceptable
Cadmium
0.08
U.08
11.08
2
Acceptable
Acceptable
Acceptable
Calcium
mg/L
20
14.2
20.4
NE
Acceptable
Acceptable
Acceptable
Carbonate
mg/L
5
5
5
NE
Acceptable
Acceptable
Acceptable
Chloride
mg/L
10.9
6
Lb
250
Acceptable
Acceptable
Acceptable
Chromium (VI)
µg/L
7J42
1.2
0.2.3
NA
Acceptable
Acceptable
Acceptable
Duke should verify that only Chromium (VI) data was evaluated to establish value.
Deep and bedrock data set is insufficient and must be updated with additional data.
Chromium
@/L
1 6.927
6.8
5.6
10
Acceptable
Acceptable
Acceptable
Deep and bedrock data set is insufficient and must be updated with additional data.
Cobalt
4.338
0.5
0.27
1
Acceptable
Acceptable
Acceptable
Copper
2.265
1.7
1.2
1000
Acceptable
Acceptable
Acceptable
Iron
834.8
555
294
300
Acceptable
Acceptable
Acceptable
Lead
kmg/L
0. tt__
5.61
0.1
0.1
15
Acceptable
Acceptable
Acceptable
Magnesium
I 4.58
4.75
NE
Acceptable
Acce table
Acceptable
Manganese
577.9
60A
39.1
50
Acceptable
Acceptable
Acceptable
Memu
D.2
2.4
" 0.2
1
Acceptable
Acceptable
Acceptable
Methane
WL
11.4
.3 .9
10
NE
Acceptable
Acceptable
Acceptable
Page 1 of 2

Allen Steam Station - Groundwater Provisional Background Threshold Values
Parameter
Reporting Units
Duke Energl Calculated PBTVs
Flow Unit
15A NCAC 02L
Standard or
]MAC
DWR Concurrence(Acceptable/Not Acceptable)
Comments
Flow Unit
Shallow
Dee
Bedrock
Shallow
Dee
Bedrock
Molybdenum
y
µ91L
+
30._
4.4
NE
Acceptable
Not Acceptable
Acceptable
Duke should verify deep value with geometric mean and revise if needed.
D and bedrock data set is insufficient and must be updated with additional data.
Nickel
4.024
4.024
R.I
3.4
100
Acceptable
Acceptable
Acceptable
Deep and bedrock data set is insufficient and must be updated with additional data.
Nitrate + Nitrite
mg-N/L
1.8
0.94
0.41
11•
Acceptable
Acceptable
Acceptable
Potassium
mg/L
5.24
_
9.89
6.06
NE
Acceptable
Acceptable
Acceptable
Selenium
g/L.
0.5
0.5
0.5
20
1 Acceptable
Acceptable
Acceptable
Sodium
Strontium
mg/L
15.2.19
286
28.3
200
7.71
106
NE
NE
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acce table
Sulfate
mg/L
31,41
1 16.2
2.9
250
Acceptable
Acceptable
Acceptable
Sulfide
mg/L
0.1
_
0.12
0.1
NE
Acceptable
Acceptable
Acceptable
TDS
mg/L
180.957
12ti
147
500
Acceptable
Acceptable
Acceptable
Thallium
µg/L
0.1
0.1
0.1
0.2
Acceptable
Acceptable
Acceptable
TOC
mg/L
18.022
11
5.6
NE
Acceptable
Not Acceptable
Acceptable
Duke should verify deep value with geometric mean and revise if needed.
Deep and bedrock data set is insufficient and must be updated with additional data.
Vanadium
L
5.33
9.6
10.8
1 0.3
1 Acceptable
Acceptable
I Acceptable
Deep and bedrock data set is insufficient and must be updated with additional data.
Zinc
pg/L
R0.02
17J
15 t
1000
Acceptable
Not Acceptable
Not Acceptable
Duke should verify deep and bedrock value with geometric mean and revise if needed.
Deep and bedrock data set is insufficient and must be updated with additional data.
Radium (Total)
Umnium(Total)
pci/
p mL
1 iR6
0.001037
0.613
0.0005
1.103
0.00039
NE
NE
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Deep and bedrock data set is insufficient and must be updated with additional data.
NA - Not Applicable
NO - Not Detected
NE - Not Established
mglL - milligrams per liter
pCi/L - picocuries per liter
Radium (Total) - Radium-226 and Radium-228 combined
* lie 15A NCAC 02L Standard is 10 mg/L for Nitrate and I mg/L for Nitrite (added for a anal of I I mg/L)
S.U. -Standard Unit "Duke plans to update the shallow and deep data set in the near future. PBNs will be revised accordingly. Bedrock flow
layer data set will remain insufficient until additional sampling events are completed.`•
TOC - Total Organic Carbon
TDS - Total Dissolved Solids
pg/mL - micrograms per milliliter
pg/L - micrograms per liter
Uranium (Total) - Uranium-233. Uranium-234. Umnium-236. and Uranium-238 combined
Page 2 of 2

Allen Steam Station - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Fuergy
Calculated
PBI,vs
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Acceptable)
Comments
H
S.U.
3.3_- 6.8
NE
Acceptable
Aluminum
mg/kg
_ _
26991
NE
Acceptable
Antimony
mg/kg
N A
0.9
Not Acceptable
Use PSRG of 0.9. To be revised when valid data set is available.
Arsenic
mgfkg
3.7
5.8
Acceptable
Only 5 valid samples in data set.
Barium
mglkg
233
580
Acceptable
Beryllium
mg/kgmg/kg
1.304
63
Not Acceptable
Normal UTL - 1.78 mg/kg.
Boron
mg/kg
23.4
45
Acceptable
Only 9 valid samples in data set.
Cadmium
mg/kgmg/kg
0.368
3
Acceptable
Calcium
mg/kgmg/kg
1192
NE
Not Acceptable
Normal UTL - 859.9 mg/kg.
Chloride
mg/kgmg/kg
ND
NE
Acceptable
Chromium
mg/kgmg/kg
93.57
3.8
Not Acceptable
Normal UTL - 20.42 m
Cobalt
mg/kgmg/kg
48.6
0.9
Acceptable
Copper
mgIkg
78 15
700
Acceptable
Iron
mg/kgmg/kg
69316
150
Acceptable
Lead
mg/kgmg/kg
12.31
270
Acceptable
Magnesium
m
15100
NE
Acceptable
Manganese
mg/kg
_ _
1786
65
Acceptable
Mercury
mglkg
0.0233
1
Acceptable
Molybdenum
mgkg
4.6
NE
Acceptable
Nickel
mg/kgmg/kg
9.079
130
Not Acceptable
Log UTL - 10.91 m
Nitrate as N)
mg/kgmg/kg
ND
NE
Acceptable
Potassium
mg/kg
_ 13742 _
NE
Not Acceptable
Normal UTL - 14,097 mg/kg.
Selenium
mg/kg
NA
2.1
Not Acceptable
Use PSRG of 2.1. To be revised when valid data set is available.
Sodium
mg/kgmg/kg
_
461
NE
Acceptable
Strontium
me/kg
24.91
NE
Not Acceptable
Normal UTL - 14.41 mg/kg.
Sulfate
m kg
♦n
NE
Acceptable
Thallium
mg/kg
N A
0.28
Not Acceptable
Use PSRG of 0.28. To be revised when valid data set is available.
Vanadium
mg/kg
_
I.t2.2
6
Acceptable
Zinc
mg/kg
112.1
1200
Acceptable
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

Asheville Steam Electric Plant- Groundwater Background Threshold Values
Parameter
Reporting Units
Uuke Enerq Calculated PRIVs
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acce table/Not Acceptable)
Comments
Flow I:nit
Flow Unit
Alluvium ShallowF14.75
Bedrock
Alluvium
Shallow
Dee
Bedrock
H
S.U.
4.6-5.1 43.$.8
4.1-8.1
6.5-8.5
Acceptable
Acceptable
Acceptable
Acceptable
Alkalinity
m L
10.9 t4.2
70A
NE
Acceptable
Acceptable
Acceptable
Acceptable
Aluminum
L
73 602.2
199.3
NE
Accetable
Acce table
Acce table
A table
Antimon
µg/L
I �1
I
I.
Ac table
Acce table
Acc table
Acc table
Arsenic
I t I
1
10
Acceptable
Acceptable
Acceptable
Acceptable
Barium
µg/L
50 14a
41.16
700
Ac table
Acce table
Acc table
Acc table
B Ilium
µg/L
t1
1
4
A table
Acce table
Acce table
Acc table
Bicarbonate
Boron
mg/L
119fl,
10.9 1i
50 so -�
50
70A
50
NE
700
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Cadmium
_
1 __ _ "1_
2.6� _ Inn 1913
5 5 5
2
Acceptable
Acceptable
Acceptable
Acceptable
Calcium
mg/L
_ 24_I';_
5
NE
Acceptable
Acceptable
Acceptable
Acceptable
Carbonate
m
NE
Acceptable
Acceptable
Acceptable
Acceptable
Chloride
m
_
IS
_
l4
6.7
_
6.5
250
Acceptable
Acceptable
Acceptable
Acceptable
Chromium (VI)
1191
OAI
1313
0.261
0.423
NA
Acceptable
Ac table
Acceptable
Acceptable
Chromium
5
5
1 z2
_
1.1
10
Acceptable
Acceptable
Acceptable
Acceptable
Cobalt
AWL
429
S.ti.52
4.661, 1
1
Acceptable
Not Acceptable
Acceptable
Acceptable
Shallow: non -parametric distribution; 95% UTL (bootstrap and BCA bootstrap avenge) with 95% coverage = 6.9.
copper
5
5
i.Ox f- 1
1000
Acceptable
Acceptable
Acceptable
Acceptable
Iron
µg'L
598
_1050 1785- 1246
_ I _ _1 1
_R= T 3 371 t 330
725 380 104.7
03 0.2 0.05
300
Acceptable
Not Acceptable
Not Acceptable
Acceptable
Shallow: gamma distribution; 95% UTL (WE and HW avenge) with 95% coverage = 941.
Deep: notmaldistribution; 95%UTLwith95%coven a=779.
Lead
1191L
I
15
NE
50
Acceptable
Acceptable
Acceptable
Acceptable
A table
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Not Acceptable
Bedrock: non-pammetric distribution; 95% UTL (bootstrap and BCA bootstrap average) with 95% coverage = 93.
Magnesium
Manganese
mg/L
119/1.
3,86
363
Mercury
L
0.1
1
Acceptable
Acceptable
Acceptable
Acceptable
Methane
µg1-
230
10
10
Ill
NE
Not Acceptable
Acceptable
Acceptable
Acceptable
Alluvium: 230 is an outlier and Should be removed from dataset; normal distribution, 95% UTL with 95% coverage =
128.
Molybdenum
µPL
1
_ _ 1 I _ 3.7
t-- _ 10 u,82c 1.77
_ 2,4 0 RT__ _ _0.422
Lot 1.871 _ 4.785
1.88 I _t _ 1
_�._-
4.D6 _ 11 �; 9.013
93.98 _.i ➢'. Gi 88
50 _5_46' S.n
_ 6.1 _ 0.1 - _01 _
IU4p ! I II c
_. .r
0.2 _ 11.2 __ U.2
0.70R 0 599 _ LI02
0.625 0.41 OA32
NE
Acceptable
Acceptable
Acceptable
Acceptable
Nickel
g'L
5
100
le
Acceptable
Acceptable
Acceptable
Nitrate + Nitrite
m -N/L
0.113
11°
le
Acceptable
Acceptable
Acceptable
Potassium
mg/L
MR5
NE
20
le
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Selenium
f
Sodium
m
6.18
NE
le
Acceptable
Acceptable
Acceptable
Strontium
µ
20
NE
le
Acce table
Acce table
Acce table
Sulfate
m L
4,6
11.1
56
0,2
250
le
Acceptable
Acceptable
Acceptable
Sulfide
mg/L
NE
Acceptable
Acceptable
Acceptable
Acceptable
TDS
mg/L
500
Acceptable
Acceptable
Acceptable
Acceptable
Thallium
0.2
Acceptable
Acceptable
Acceptable
Acceptable
TOC
m L
0.72
NE
Acceptable
Acceptable
Acceptable
Acceptable
Vanadium
'L
03
0.3
Acceptable
Acceptable
Acceptable
Acceptable
Zinc
µg�L
22 45.4 27.57
5
1000
Acceptable
Acceptable
Acceptable
Acceptable
Radium (Total)
Ci/L
4.17 6.832 6.61
6554
NE
Acceptable
Acceptable
Acce table
Not Acce table
Bedrock: normal distribution; 95%UTL with 95%coven a=5.8.
Unnium(TmaT)
µ mL
O.OIro35 O.D0035 0.1100402
6.09045396
NE
A table
Acce table
Acce table
Acce table
NA -Not Applicable
ND -Not Detected
NE . Not Established
mg/L - milligrams per liter
pCi/L - picocuries per liter
Radium (Total)- Radium-226 and Radium-228 combined
-The 15A NCAC 02L Standard is 10 mg/L for Nitrate and l mg/L for Nitrite (added for a total of 11 mg/L)
S.U. - Standard Unit
TUC - Total Organic Carbon
TDS - Total Dissolved Solids
µg/mL. micrograms per milliliter
µg(L - micrograms per liter
Uranium (Total)- Umnium-233, Uranium-234, Uranium-236, and Umnium-238 combined

Asheville Steam Electric Plant - Soil Background Threshold Values
Parameter
Reporting
Units
Duke Fnergv
Calculated PB'1'l's
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not Acceptable)
Comments
H
S.U.
3.4 - 8.9
NE
Acceptable
Aluminum
mg/kg
33951
NE
Acceptable
Antimony
mg/kg
NA
0.9
Not Acceptable
Use PSRG of 0.9. To be revised when valid data set is available.
Arsenic
mg/kg
5.06
5.8
Acceptable
Barium
mg/kg
219.9
580
Acceptable
Beryllium
mg/kg
1.959
63
Acceptable
Boron
mg/kg
36.6
45
Acceptable
Cadmium
mg/kg
ti D
3
Not Acceptable
Use PSRG of 3. To be revised when valid data set is available.
Calcium
mg/kg
1295
NE
Acceptable
Chloride
mg/kg
NI)
NE
Acceptable
Chromium
mg/kg
64.89
3.8
Acceptable
Cobalt
mg/kg
49.6_2
0.9
Acceptable
Copper
mg/kg
_
76.6
700
Acceptable
Iron
mg/kg
53379
150
Acceptable
Lead
mg/kg
71.04
270
Acceptable
Magnesium
mg/kg
9673
NE
Acceptable
Manganese
mg/kg
1228
65
Acceptable
Mercury
mg/kg
0.070'
1
Acceptable
Molybdenum
mg/kg
ND
NE
Acceptable
Nickel
mg/kg
2758
130
Acceptable
Nitrate (as N)
mg/kg
NI)
NE
Acceptable
Potassium
mg/kg
4754)
NE
Acceptable
Selenium
mg/kg
7
2.1
Acceptable
Sodium
mg/kg
NI)
NE
Acceptable
Strontium
mg/kg
7.756
NE
Acceptable
Sulfate
mg/kg
N1)
NE
Acceptable
Thallium
mg/kg
NA
0.28
Not Acceptable
Use PSRG of 0.28. To be revised when valid data set is available.
Vanadium
mg/kg
_
82.78
6
Acceptable
Zinc
mg/kg
218.5
1200
Acceptable
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

Buck Combined Cycle Station - Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
_Duke Energy Calculated PBTVs
—
I7ow Enit
15A NCAC 02L
Standard or
MAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
—
Shallow
Dec
Bedrock
Shallow
Deep
Bedrock
pH
S.U.
4.5 - 6.4
5.9 - SA 1
5.8 - 7.8
6.5-8.5
Acceptable
Acceptable
Acceptable
Alkalinity
mg2
67.3
70.4
72
NE
Not Acceptable
Not Acceptable
Acceptable
Duke revised shallow - Gamma 117.2 ug/L and deep - Gamma 80.2 ug/L.
Please revise table accordingly.
Aluminum
µg/L
_
272.8
404
240
NE
Acceptable
Acceptable
Acceptable
Antimony
µg/L
I
1
1
1
Acceptable
Acceptable
Acceptable
Arsenic
µg/L
I
1
1
10
Acceptable
Acceptable
Not Acceptable
Duke revised bedrock - Gamma 3.3 ug/L. Please revise table accordingly.
Barium
µg/L
43.5
19
90.8
700
Not Acceptable
Acceptable
Acceptable
Duke agreed Shallow Nomal UTL - 50.6 ug/L.
Beryllium
µg L
0.139
1
0.2
4
Not Acceptable
Acceptable
Acceptable
Duke utilized Gamma UTL for shallow - 0.81 ug/L. Please revise table
accordin I .
Bicarbonate
mg/L
92.261
84.371
72
NE
Acceptable
Acceptable
Acce table
Boron
L
50
50
50
700
Acceptable
Acceptable
Acce [able
Cadmium
L
1
1
1
2
Acceptable
Acceptable
Acceptable
Calcium
mg/L
13.1
14
13.3
NE
Acceptable
Acceptable
Acceptable
Carbonate
mg/L
5
5
5
NE
Acceptable
Acceptable
Acceptable
Chloride
mg/L
7.559
_
4.454
4.818
250
Acceptable
Acceptable
Acceptable
Chromium (VI)
g/L
2.428
0.5
1.20
NA
Acceptable
Acceptable
Acceptable
Chromium
g/L
5.04
5
3.603
10
Acceptable
Acceptable
Acceptable
Cobalt
L
8.345
0.297
0.289
1
Acceptable
Acceptable
Acceptable
Copper
L
4.431
5
5.164
1000
Acceptable
Acceptable
Iron
L
64fiA
499.9
1 146.6
300
Acce table
Acceptable
Lead
µg/L
1
1
I
15
Acceptable
Acce table
n
Ma esium
m L
8.68
5.859
7.59
NE
Acc table
Acce table
Manganese
g/L
197.9
7
7
50
Acce table
Acce table
Page 1 of 2

Buck Combined Cycle Station - Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
fluke Energv Calculated PBTVs
Flow Unit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
Shallow
Deep
Bedrock
Shallow
Deep
Bedrock
Mercury
g/L
0.05
0.05
0.05
1
Not Acce table
Not Acceptable
Not Acceptable
Shallow, deep, and bedrock Non -Par. UTL - 0.2 u L.
Methane
µg/L
10
10
10
NE
Acceptable
Acceptable
Acceptable
Molybdenum
1
2
5.9
NE
Acceptable
Acceptable
Acceptable
Nickel
L
7.2
5
5
100
Acceptable
Acceptable
Acceptable
Nitrate + Nitrite
m -N/L
0.4
2
0.8712
ll*
Acceptable
Acceptable
Acceptable
Potassium
m
5
6.89
6.613
NE
Acceptable
Acceptable
Acceptable
Selenium
µg/L
1
1
1
20
Acceptable
Acceptable
Acceptable
Sodium
mg/L
8.22
13
9.8
NE
Acceptable
Acceptable
Acceptable
Strontium
µg/L
108
129
98.5
NE
Acceptable
Acceptable
Acceptable
Sulfate
m
3.3
6.7
2.4
250
Acceptable
Acceptable
Acceptable
Sulfide
m
0.1
0.1
0.1
NE
Acceptable
Acceptable
Acceptable
TDS
mg/L
212.02
130
145.049
500
Acceptable
Acceptable
Acceptable
Thallium
µg/L
0.2
0.2
1 0.2
0.2
Acceptable
Acceptable
Acceptable
TOC
mg/L
1100
1
1600
NE
Not Acceptable
Acceptable
Not Acceptable
Shallow background value should be 1.1 ug/L. Please revise accordingly.
Duke should verify bedrock value with geometric mean and revise if needed.
Vanadium
g/L
7.69
8.418
14.12
0.3
Acceptable
I Acceptable
Acceptable
Zinc
µg/L
26.39
10
17.4
1000
Acceptable
Acceptable
Acceptable
Radium (Total)
Ci/L
1.608
0.6
1.6
NE
Acceptable
Acceptable
Acceptable
Uranium Total
mL
0.0005
0.0005
0.0005
1 NE
Acceptable
Acceptable
Acceptable
NA - Not Applicable
ND - Not Detected
NE - Not Established
mg/L - milligrams per liter
pCi/L - picocuries per liter
Radium (Total) - Radium-226 and Radium-228 combined
*The 15A NCAC 02L Standard is 10 mg/L for Nitrate and I mg/L for Nitrite (added for a total of 11 mg/L)
S.U. - Standard Unit
TOC - Total Organic Carbon
TDS - Total Dissolved Solids
µg/mL - micrograms per milliliter
µg/L - micrograms per liter
Uranium (Total) - Uranium-233, Uranium-234, Uranium-236, and Uranium-238 combined
Page 2 of 2

Buck Combined Cycle Station - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
Calculated
PB'CN s
PSRG Protection
PSRG
of Groundwater
Concurrence
(Acceptable/Not
Acceptable)
Comments
H
S.U.
4.1 - 6.7
NE
Acceptable
Aluminum
M&g
25978
NE
Acceptable
Antimony
m
NA
0.9
Not Acceptable
Use PSRG of 0.9. To be revised when valid data set is available.
Arsenic
mg/kg
1.7
5.8
Acceptable
Only3 valid samples in data set.
Barium
m
_
U2.9
580
Acceptable
Beryllium
mg/kg
2.8
63
Not Acceptable
Gamma UTL - 4.52 mg/kg.
Boron
mg/kg
_
56.3
45
Acceptable
Cadmium
mg/kg
ND
3
Acceptable
Calcium
m
718
NE
Not Acceptable
Normal UTL - 999.1 mg/kg.
Chloride
mg/kg
ND
NE
Acceptable
Chromium
mg/kg
24,64
3.8
Acceptable
Cobalt
m
46.5
0.9
Acceptable
Copper
mg/kg
88.76
700
Acceptable
Iron
mg/kg
78988
150
Acceptable
Lead
mg/kg
15.36
270
Acceptable
Magnesium
m
33058
NE
Not Acceptable
Normal UTL - 14,554 mg/kg.
Manganese
mg/kg
1748
65
Acceptable
Mercury
mg/kg
0.0778
1
Acceptable
Molybdenum
mg/kg
ND
NE
Acceptable
Nickel
mg/kg
15.85
130
Acceptable
Nitrate as N)
mg/kg
ND
NE
Acceptable
Potassium
mg/kg
21444
NE
Not Acceptable
Normal UTL - 21,063.5 mg/kg.
Selenium
mglkg
N:%
2.1
Not Acceptable
Use PSRG of 2.1. To be revised when valid data set is available.
Sodium
ND
NE
Acceptable
Strontium
9.869
NE
Acceptable
Sulfate
ND
NE
Acceptable
Thallium
:iMjg/1Cg
N.4
0.28
Not Acce table
Use PSRG of 0.28. To be revised when valid data set is available.
Vanadium
202.6
6
Acc tableZinc
105.4
1200
Acceptable
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

Cape Fear Steam Electric Plant - Groundwater Provisional Background Threshold Values
Re
Rep MIS
Uuke b nugr (alauldcd PBI l's
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
host I nit
Flow Unit
._
SurFicial Bedrock
Surlieial
Bedrock
pH
S.U.
5.8 - 6.4 _5.5 - %.2
6.5-8.5
Acceptable
Acceptable
Alkalinity
mg/L
206 _ 237 Y _
323._3 _ _ _ 11%
I I _
3 6
NE
Acceptable
Acceptable
Aluminum
µg/L
NE
Acceptable
Acceptable
Antimony
Arsenic
L
l
10
Acceptable
Acceptable
Acceptable
Acceptable
Barium
_
183 _ 471
1 1
20M1 235
700
Acceptable
Acceptable
Beryllium
µg/L
4
Acceptable
Acceptable
Bicarbonate
m
NE
Acceptable
Acceptable
Boron
a
_ _ _
177 _ so
700
Acceptable
Acceptable
Cadmium
L
_ _ _
1 1_
2
NE
Acceptable
Acceptable
Acceptable
Acceptable
Calcium
mg/L
__ _
82.6
Carbonate
mgfL
5
_ _6.2b
5
NE
Acceptable
Acceptable
Chloride
mg/L
250
22o
250
Acceptable
Acceptable
Chromium (VI)
11911,
0.12
0!�3
NA
Acceptable
Acceptable
Chromium
pgfL
1
_ _
I
10
Acceptable
Acceptable
Cobalt
L
89
1.15
1
Acceptable
Acceptable
Copper
L
4
1
1000
Acceptable
I Acceptable
Iron
µg/L
375W
_ _
910
300
Acceptable
Not Acceptable
RRO calculated value of 750 ug/L for bedrock. Removed 4230, 2290, 1800, and 1220 as outliers. Duke Energy
notified ofdiscrepancy by email on 9-15-17
Lead
L
1
1
15
Acceptable
Acceptable
Magnesium
mg/L
32 c
30.8
NE
Acceptable
Acceptable
Manganese
g/L
9170
991
50
Acceptable
Acceptable
Mercury
L
0.05
0.05
1
Acceptable
Acceptable
Methane
L
1 10
25
NE
Acceptable
Acceptable
Molybdenum
L
1
11.5
NE
Acce table
Acceptable
Nickel
µg/L
78.11
2
100
Not Acceptable
Acceptable
RRO calculated value of48 ug/L. for surficial. Removed 150 as outlier. Duke Energy notified ofdiscrepacy by
email on 9-15-17
Nitrate -Nitrite
m -N/L
1.61
2.49
Il*
Acceptable
Acceptable
Potassium
mg/L
1
2.49
NE
Acceptable
Acceptable
Selenium
g/L
1
1."
20
Acceptable
Acceptable
Sodium
m
190
725
NE
Acceptable
Acceptable
Strontium
+L
994
a06
NE
Acceptable
Acceptable
Sulfate
I m 'L
510
1 %
250
Acceptable
Acceptable
Sulfide
mg/L
0.1
0.1
NE
Acceptable
Acceptable
TDS
m L
1200
675
500
Acceptable
Acceptable
Thallium
0.2
_
0.2
0.2
Acce table
Acceptable
TOC
m9fL
6.3 _
13
NE
Acceptable
Acceptable
Vanadium
L
1.268
2.37
0.3
Acceptable
Acceptable
Zinc
L
62
5
1000
Acceptable
Acceptable
Radium (Total)
pCi/L
3.459
NE
Acceptable
Acceptable
Uranium (Total)
g'mL
__1.03 _
O.01b"
0.00196
NE
Acceptable
Acceptable
NA. Not Appkeable
ND - Not Detected
NE - Not Established
mg/L- milligrams per liter
pCJL-picocuries per liter
Radimn (Total) . Radimn.226 and Radium-228 coinbeed
*The 1 SA NCAC 02L Standard is 10 mall, for Nitrate and I mg/L for Nitrite (added for a total of I I mg/L)
S.N. - Staudard Brut
TOC - Total Organic Cuban
TDS - Total Dissolved Solids
µghn]. - microgrmms per milliliter
pall. - micrograms per liter
❑mnimn (Total) - Uranium-233, Umnimn-234, Uranimn-236, and Uranium-238 combined

Cape Fear Steam Electric Plant - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
Calcualated
PB'iVs
of PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Acceptable)
Comments
pH
S.U.
5.2-6.7
NE
Acceptable
The PBTV was based on either the highest value or if the highest value is above an order of magnitude greater than
the geometric mean of all values, then the highest value should be considered an outlier and removed from further
use and the PBTV is computed to be the second highest value.
Aluminum
mg/kg
44400
NE
Acceptable
Antimony
mg/kg
0.177
0.9
Acceptable
Arsenic
mg/kg
8.1
5.8
Acceptable
Barium
mg/kg
224
580
Acceptable
Beryllium
mg/kg
1.2
63
Acceptable
Boron
mg/kg
14.4
45
Acceptable
Cadmium
mg/kg
0.69
3
Acceptable
Calcium
mg/kg
2750
NE
Acceptable
Chloride
mg/kg
301
NE
Acceptable
Chromium
mg/kg
40.4
360000
Acceptable
Cobalt
mg/kg
31.9
0.9
700
Acceptable
Acceptable
Copper
mg/kg
17.4
Iron
mg/kg
2%0
150
Acceptable
Lead
mg/kg
26.1
270
Acceptable
Magnesium
mg/kg
3420
NE
Acceptable
Manganese
mg/kg
370
65
Acceptable
Mercury
marJka
0.113
1
Acceptable
Molybdenum
mg/kg
3.3
NE
Acceptable
Nickel
mg/kg
9.2
130
Acceptable
Nitrate (as N)
mg/kg
30.1
NE
Acceptable
Potassium
mg/kg
427
NE
Acceptable
Selenium
mg/kg
4.4
2.1
Acceptable
Sodium
mg/kg
338
NE
Acceptable
Strontium
I mg/kg
35.8
NE
Acceptable
Sulfate
mg/kg
301
250
Acceptable
Thallium
mg/kg
0.349
0.28
Acceptable
Vanadium
mg/kg
I
42
6
Acceptable
Zinc
mg/kg
154
1200
Acceptable
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

James E. Rogers Energy Complex- Groundwater Provisional ackground Threshold Values
Parameter
Reporting
Units
Duke Energy Calculated PBM
Flo% Unit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
Shalon,
Ikeep
Bedrock
Shallow
Deep
Bedrock
pH
S.U.
4.4-6.1
41.E-6.1
5.4-7A
6.5-8.5
Acceptable
Acceptable
Acceptable
Alkalinity
m
13.67
19.74
53
NE
Acceptable
Acceptable
Acceptable
Aluminum
WL
253
290
208.2
NE
Acceptable
Acceptable
Acceptable
Antimony
µg/L
1
I
1
1
Acceptable
Acceptable
Acceptable
Arsenic
WIL
I
1.303
1
10
Acceptable
Acceptable
Acceptable
Barium
µglL
73.03
23
A933
700
Acceptable
Acceptable
Acceptable
Beryllium
L
0.188
0.2
1
4
Acceptable
Acceptable
Acceptable
nate
mg(L
14.42
18.13
68.92
NE
Acceptable
Acceptable
Acceptable
50
50
50
700
Acceptable
Acceptable
Acceptable
m
1
I
1
2
Acceptable
Acceptable
Acceptable
mg/L
3.221
I1
16
NE
Acce table
Acce table
Acceptable
te
m
5
5
5
NE
Acc table
Acc table
Ac fable
m
7.7
5.1 RAM
6.16 0.12
250
Acceptable
Acceptable
Ac table
m (vq
0.4.42
NA
Acceptable
Acc table
Acceptable
m
µg(L
3.96R 1'91 r567
_10.65 _ 9 041 _ 1 497
6.5ao n4-r '- 5
7653 ! 5.96220
1 _ I_ �1
2.4-4 _ 1.6 2.328
16X.6 _ _'8 zl 80.4
0.2 U2 f 0.2
10
Acce table
Acc table
Acceptable
1
Acceptable
Not Acceptable
Acceptable
Deep: non -parametric distribution; 95% UTL (bootstrapand BCA bootstrapaverage) with 95% -coverage = 5.1.
Copper
1000
Acceptable
Acceptable
Ac mble
Iron
Lead
µg/L
300
Not Acceptable
Not Acceptable
Acceptable
Shallow: log normal distribution; 95% UTL with 95% coverage = 684.
Deep: no -parametric distribution; 95% UTL(bootstrap and BCA bootstrap averse with 95%coverage =515.
IS
Acceptable
Acceptable
Acceptable
Magnesium
mg1L
NE
Acceptable
Acceptable
Acceptable
Manganese
ltS1L
50
Acceptable
Acceptable
Acceptable
Mercury
1
NE
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Methane
Molybdenum
µg/L
_
10 I! I51 _ In
1 _ I _ I 716
6.LS6 _
8.837_I^_2.R
NE
Acceptable
Acceptable
Acceptable
Nickel
Nitrate +Nitrite
IL91L
m-N/L
100
Acceptable
Acceptable
Acceptable
It-
Acceptable
Acceptable
Acceptable
Potassium
mg/L
5
g
_U.u�
s
NE
Acceptable
Acceptable
Acceptable
Selenium
9911.
1
1
1
20
Acceptable
Acceptable
Acceptable
Sodium
mg/L
6.139
4.41
7.42
NE
NE
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Strontium
36.71
56.14
107.1
Sulfate
mg/L
1.169
10
15.1
250
Acceptable
Acceptable
Acceptable
Sulfide
mg/L
0.1
0A
0.1
NE
Acceptable
Acceptable
Acceptable
TDS
mg/L
75A7
70.98
120
500
Acceptable
Acceptable
Acceptable
Thallium
0.117
0.063
0.2
0.2
Acceptable
Acceptable
Acceptable
TOC
mg/L
I
I
I
NE
Acceptable
Acceptable
Acceptable
Vanadium
µg/L
1.059
1.095
037
0.3
Not Acceptable
Acceptable
Acceptable
Shallow: normal distribution; 95% UTL with 95% coverage = 0.8.
All vanadium values reported as ", I ugtU'should be omitted from the background dataset because the detection
limit is above the IMAC.
D : vanadium = 3 u L(deep) is identified as an outlier and should be omitted from the damsel.
Zinc
µgfL
15
15.a3
10
1000
Acceptable
Acceptable
Acce table
Radium (Total)
Cill,
2.58
I51
d.l
NE
Acceptable
Acceptable
Acceptable
Uranium (Total
mL
0.0005
Q01g5
0.ODU5
NE
Acce mble
Acceptable
Acceptable
NA - Not Applicable
S.U. - Standard Unit
NO - Not Detected
TOC - Total Organic Carbon
NE - Not Established
TDS - Tom] Dissolved Solids
mg/L - milligrams per liter
µg/mL - microgams per milliliter
pCi/L - picocuries per liter
µg/L - micrograms per liter
Radium (Total) - Radium-226 and Radium-228 combined
Uranium (Total) - Uranium-233, Umnium-234, Umnium-236, and Umnium-238 combined
-The 15A NCAC 02L Standard is 10 mg/L for Nitrate and I mg/L for Nitrite (added for a total of 11 mg/L)

James E. Rogers Energy Complex - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
Calculated
PR r�•s
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not Acceptable)
Comments
H
S.U.
4.7 - 6.7
NE
Acceptable
Aluminum
mgfkg
36464
NE
Acceptable
Antimony
mgfkg
NA
0.9
Not Acceptable
Use PSRG of 0.9. To be revised when valid data set is available.
Arsenic
mgfkg
4.88
5.8
Acceptable
Barium
m
233
580
Acceptable
Beryllium
m
_ _ 38.9
63
Acceptable
Boron
mg/kg
1.92
45
Acceptable
Cadmium
mgfkg
ND
3
Not Acceptable
Use PSRG of 3. To be revised when valid data set is available.
Calcium
m
_ 304
NE
Acceptable
Chloride
m
ND
NE
Acceptable
Chromium
mg/kg
_ 109 _
3.8
Acceptable
Cobalt
m
_ 59.5
0.9
Not Acceptable
Normal distribution at 5% significance level; 95% UTL with 95% coverage = 43.
Copper
mg/kg
34.7
700
Acceptable
Iron
m
75162
150
Acceptable
Lead
mvJkQ
38.1
270
Acceptable
Magnesium
mgfkg
2.1562
NE
Acceptable
Manganese
m
1518
65
Not Acceptable
Gamma distribution at 5% significance level; 95% UTL WH and H W averse with 95% coverage = 1421.
Mercury
mg/kg
0.016
1 -
Acceptable
Molybdenum
mgfkg
U.97
NE
Acceptable
Nickel
m
66.2
130
Acceptable
Nitrate (as N)
m&g
ND
NE
Acceptable
Potassium
m
18460
NE
Acceptable
Selenium
mgfkg
_ 12 _
2.1
Not Acceptable
N < 10 so use maximum = 8.3
Sodium
mg/kg
194
NE
Acceptable
Strontium
mg/kg
14.1
NE
Acceptable
Sulfate
mg/kg
ND
250
Acceptable
Thallium
m
_ _ N n _
0.28
Not Acceptable
Use PSRG of 0.28. To be revised when valid data set is available.
Vanadium
m
142
6
Acceptable
Zinc
m
214
1200
Acceptable
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

Dan River Combinded Cycle Station- Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy Calculated PBTVs
Flow Unit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
Shallow
Deep
Bedrock
Shallow
Deep
Bedrock
H
S.U.
4.0-7.1
5.3-6.8
6.7-8.4
6.5-8.5
Acceptable
Acceptable
Acceptable
Alkalinity
mg/L
77.7
168
236
NE
Acceptable
Acceptable
Acceptable
Aluminum
118
113
100
NE
Acce table
Acceptable
Acceptable
Antimony
g/L
0.5
0.5
0.5
1
Acceptable
Acceptable
Acceptable
Arsenic
g/L
0.5
1.62
0.833
10
Acceptable
Acceptable
Acceptable
Barium
L
19
80.4
128
700
Acceptable
Acceptable
Acceptable
Beryllium
µg/L
0.429
0.0772
0.0625
4
Acceptable
Acceptable
Acceptable
Bicarbonate
mg/L
77.7
168
233
NE
Acceptable
Acceptable
Acceptable
Boron
50
50
50.9
700
Acceptable
Acceptable
Acceptable
Cadmium
L
0.08
0.08
0.08
2
Acceptable
Acceptable
Acceptable
Calcium
mg/L
19A
59
59.1
NE
Acceptable
Acceptable
Acceptable
Carbonate
mg/L
5
5
5
NE
Acceptable
Acceptable
Acceptable
Chloride
mg/L
7.3
6.8
7.1
250
Acceptable
Acceptable
Acceptable
Chromium I)
L
0.58
1.24
0.15
NA
Ace table
Acceptable
Acceptable
Chromium
µg/L
1.26
3.42
8.31
10
Acce table
Acceptable
Acceptable
-
Cobalt
µ L
2A
0.85
1
1
Ace table
Acceptable
Acceptable
Copper
I ggfL
2.67
2.29
13
1000
Acceptable
Acceptable
Acceptable
Iron
µg/L
152
2130
1400
300
Acceptable
Not Acceptable
Acceptable
Please explain why two distinguished subgroups of population exist and whether they should be
grouped together should also be evaluated.
Lead
AWL
0.1
0.13
1.4
15
Ace table
Acceptable
Acceptable
Magnesium
mgIL
12.2
15.9
20.7
NE
Acceptable
Acceptable
Acceptable
Manganese
81.2
552
38.9
50
Ace table
Acceptable
Acceptable
Mercury
AWL
0.2
0.2
0.2
1
Acceptable
Acceptable
Acceptable
Methane
pg/L
10
10
233
NE
Acceptable
Acceptable
Acceptable
Molybdenum
0.5
0.927
1.4
NE
Acceptable
Acceptable
Acceptable
Nickel
2.88
3.65
19.2
100
Acceptable
Acceptable
Acceptable
Nitrate + Nitrite
to -N/L
0.53
0.349
0.074
11•
Acceptable
Acce table
Acceptable
Potassium
mg/L
5
5
5
NE
Accept le
Acceptable
Acceptable
Selenium
0.5
0.5
1 0.5
20
Acceptable
Acceptable
Acceptable
Sodium
mg/L
17.3
17.8
19.2
NE
Acceptable
Acceptable
Acceptable
Strontium
P&I
211
481
2120
NE
Acceptable
Acceptable
Acceptable
Sulfate
mg/L
36.7
36.7
11.3
250
Acceptable
Acceptable
Acceptable
Sulfide
mg/L
0.1
0.1
0.1
NE
Acceptable
Acceptable
Acceptable
TDS
m L
187
244
284
500
Ace table
Acceptable
Acceptable
Thallium
µg/L
0.1
0.1
0.1
0.2
Ace table
Acceptable
Acc table
TOC
mg/L
1
1
1
NE
Ac table
Acceptable
Acce table
Vanadium
L
0.413
0.645
2.52
0.3
Ace table
Acceptable
Acceptable
Zinc
pg/L
46.3
10
16
1000
Acce table
Acce table
Acceptable
Radium (Total)
pCi/L
1.45
1.38
1.63
NE
Acceptable
Acceptable
Acceptable
Uranium Total
mL
0.005
0.00106
1 0.002
NE
Ace table
Acce [able
-Acce table
NA - Not Applicable
S.U. - Standard Unit
ND - Not Detected
TOC- Total Organic Carbon
NE - Not Established
TDS - Total Dissolved Solids
mg/L -milligrams per liter
µg/mL - micrograms per milliliter
pCi/L- picocuries per liter
pg/L- micrograms per liter
Radium (Total) - Radium-226 and Radium-228 combined
Uranium (Total) - Uranium-233, Uranium-234, Uranium-236, and Uranium-238 combined
*The 15A NCAC 02L Standard is 10 mg/L for Nitrate and 1 mg/L for Nitrite (added for a total of 11 mg/L)

Dan River Combined Cycle Station - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
Calculated
PBTVs
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Acceptable)
Comments
pH
S.U.
2.3 - 9.4
NE
Acceptable
Aluminum
mg/kg
34500
NE
Acceptable
Antimony
mg/kg
NA
0.9
Not Acceptable
Use PSRG of 0.9. To be revised when valid data set is available.
Arsenic
mg/kg
12.37
5.8
Acceptable
Barium
mg/kg
132.9
580
Acceptable
Beryllium
m
3.313
63
Acceptable
Boron
mg/kg
ND
45
Acceptable
Cadmium
mg/kg
ND
3
Acceptable
Calcium
mg/kg
2276
NE
Acceptable
Chloride
mg/kg
ND
NE
Acceptable
Chromium
mg/kg
44.54
3.8
Acceptable
Cobalt
mg/kg
29.23
0.9
Acceptable
Copper
mg/kg
87.34
700
Acceptable
Iron
mg/kg
68009
150
Acceptable
Lead
mg/kg
30.94
270
Acceptable
Magnesium
mg/kg
12119
NE
Acceptable
Manganese
mg/kg
802
65
Acceptable
Mercury
mg/kg
0.04
1
Acceptable
Molybdenum
mg/kg
ND
NE
Acceptable
Nickel
mg/kg
45.58
130
Acceptable
Nitrate (as N)
mg/kg
ND
NE
Acceptable
Potassium
mg/kg
3160
NE
Acceptable
Selenium
mg/kg
NA
2.1
Not Acceptable
Use PSRG of 2.1. To be revised when valid data set is available.
Sodium
mg/kg
ND
NE
Acceptable
Strontium
mg/kg
84.96
NE
Acceptable
Sulfate
mg/kg
ND
250
Acceptable
Thallium
mg/kg
NA
0.28
Not Acceptable
Use PSRG of 0.28. To be revised when valid data set is available.
Vanadium
mg/kg
58.73
6
Acc table
Zinc
m
191.8
1200
Acceptable
NA - Not applicable (dataset contains Zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

H. F. Lee Energy Complex - Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy Calculated PB"1"%'s
Flow Unit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not
Comments
Flow Unit
S6allosa. (alleFesur
Shallow
Cape Fear
H
S.U.
3.4-6.8 5.3-8.3
73 _ 219
6.5-8.5
Acceptable
Acceptable
Alkalinity
L
NE
Acceptable
Acceptable
Aluminum
1059 �- _ 264
NE
Acceptable
Acceptable
Antimony
µg/L
I I_ 1
I
Acceptable
Acceptable
Arsenic
1 _ _'� _ _ 1
o41 _"_ 342
1 1
10
Acceptable
Acceptable
Barium
700
Acceptable
Acceptable
Beryllium
4
Acceptable
Acceptable
Bicarbonate
mg/L
73.9
219
NE
Acceptable
Acceptable
Boron
50
700
Acceptable
Acceptable
Cadmium
µg/L
1
_256
1
2
Acceptable
Acceptable
Calcium
L
11.2 "
30.8
NE
Acceptable
Acceptable
Carbonate
m
5
5
NE
Acceptable
Acceptable
Chloride
M91L
19
72
250
Acceptable
Acceptable
Chromiurn(VI)
µg/L
0.354
0.15
NA
Acceptable
Acceptable
Chromium
I
1
10
Acceptable
Acceptable
Cobalt
13.7
8.07
1
Acceptable
Not Acce table
Cape Fear Aquifer PBTV -1 (99%ile)
Copper
4.39
1
1000
Acceptable
Acceptable
Iron
µg/L
6320
11600
300
Not Acceptable
Acceptable
SurficialAquifer PBTV-413.8(99%ile)
Lead
Z.61
/
15
Acceptable
Acceptable
Magnesium
m
6.55
6.94
NE
Acceptable
Acceptable
Manganese
µ
1140
111"
50
Not Acceptable
Acceptable
SurficialAquifer PBTV - 838 (99%ile)
Mercury
µg/L
0.05
0.05
1
Acceptable
Acceptable
Methane
16.7
7701
NE
Acceptable
Acceptable
Molybdenum
1
10.9
NE
Acceptable
Acceptable
Nickel
pg/L
9.81
15.3
100
Acceptable
Acceptable
Nitrate + Nitrite
m -N/L
II
0.953_
If*
Acceptable
Acceptable
Potassium
mg/L
4,95
5.2
NE
Acceptable
Acceptable
Selenium
1
1
20
Acceptable
Acceptable
Sodiwn
mg/L
11.5
102
NE
Acceptable
Acceptable
Strontium
119
13.1
NE
Acceptable
Acceptable
Sulfate
mg/L
54.7
23
250
Acceptable
Acceptable
Sulfide
mg/L
0.1 _
0.1
NE
Acceptable
Acceptable
TDS
L
163
385
500
Acceptable
Acceptable
Thallium
µg/L
0.2 �_ 0.2
0.2
NE
Acceptable
Acceptable
Acceptable
Acceptable
MOLL L
_
15 - - 1.7
n.411 2.18_
20+ _ R
2? a _ 3.01
n.002 iii 0.00114
Vanadium
0.3
Acce table
Not Acceptable
Cape Fear Aquifer PBTV - 0.3 (99%ile)
Zinc
L
1000
Acceptable
Acceptable
Radium (Totall
pCVL
NE
Acceptable
Acceptable
Uranium (Total)
mL
NE
Acceptable
Acceptable
NA - Not Applicable
ND - Not Detected
NE - Not Established
mg/L - milligrams per liter
pCYL - pic.enas per liter
Radium (Total) - Radium-226 and Radian-228 combined
'The 15A NCAC 02L Standard is 10 mg/L for Nitrate and 1 mail, for Nitrite (added for a total of I I my L)
S.U. - Standard Unit
TOC - Total Ortgnic Carbon
TDS - Total Dissolved Solids
µg/ml. - micrograms per milliliter
µg/L - micrograms per liter
Uranium (Total) - Uranium-233, Uranium-234, Umnium-236, and Ummum-238 combined

H. F. Lee Energy Com lex - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
Calculated
PB'f 4 s
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Acce table
Comments
H
S.U.
NE
Duke Energy/Synterra collected one soil sample that fit the criteria for background sampling prior to this submission.
Per Ryan Czop additional soil analyses and PBTV will be forthcoming in early October. To be revised when valid data set is
available.
Aluminum
mg/kg
NE
Antimony
m
0.9
Arsenic
mg/kg
5.8
Barium
m
580
Beryllium
mg/kg
63
Boron
m k
45
Cadmium
mg/kg
3
Calcium
mg/kg
NE
Chloride
mg/kg
NE
Chromium
mg/kg
3.8
Cobalt
mg/kg
0.9
Copper
m
700
Iron
mg/kg
150
Lead
mg/kg
270
Magnesium
mg/kg
NE
Manganese
mglkg
65
Mercury
mg/kg
I
Molybdenum
mg/kg
NE
Nickel
mg/kg
130
Nitrate as N)
m
NE
Potassium
mg/kg
NE
Selenium
mg/kg
2.1
Sodium
mg/kg
NE
Strontium
mg/kg
NE
Sulfate
mg/kg
250
Thallium
mg/kg
0.28
Vanadium
m
6
Zinc
m g
1200
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mgtkg - milligrams per kilogram
S.U. - Standard Unit

Marshall
Steam Station - Groundwater Provisional Back round Threshold Values
Parameter
Reporting
Units
Duke Energy Calculated PBTVs
Flow [;nit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
Shallow
Deep
Bedrock
Shallow
Deep
Bedrock
H
S.U.
4.8 - 6.1
5.8 - 7.9
5.9 - 7.1
6.5-8.5
Acceptable
Acceptable
Acceptable
Alkalinity
m
29.7
237.502
108
NE
Acceptable
Acceptable
Acceptable
Aluminum
925.6
190.1
463
NE
Not Acceptable
Acceptable
Acceptable
Shallow - Removed 1,200 u L Gamma UTL - 612.4 u . Please revise accordingly.
Antimony
1
11.5
1
1
Acceptable
Acceptable
Acceptable
Arsenic
11.219
1.5
1
10
Acceptable
Acceptable
Acceptable
Barium
148
45.53
66.9
700
1 Acceptable
Acceptable
Acceptable
Beryllium
PgL
0.374
0.0759
t
4
Acceptable
Acceptable
Acceptable
Bicarbonate
mg/L
30.8
237.502
108
NE
Not Acceptable
Acceptable
Acceptable
Shallow - Removed 186 ug/L Normal UTL - 36.93 mg/L. Duke should verify value removed to ensure value
was in proper units revise if needed.
Boron
L
50
50
50
700
Acceptable
Acceptable
Acceptable
Cadmium
0.08
1
2
Acceptable
Acceptable
Acceptable
Calcium
m L
6.115
_0.08
88.033
13.7
NE
Acceptable
Acceptable
Acceptable
Carbonate
m
5
5
5
NE
Acceptable
Acceptable
Acceptable
Chloride
mgIL
4.3
5.186
2.7
250
Acceptable
Acceptable
Acceptable
Chromium(VI)
µg/L
1.742
1.48
4.818
NA
Not Acceptable
Not Acceptable
Not Accetpable
Duke should verify values established for Chromium (VI) were done so using Chromium (VI) data and not
total Chromium.
Chromium
µg/L
4.822
2.545
5
IO
Not Acceptable
Not Acceptable
Not Accetpable
Duke should verify values established for Chromium were done so using Chromium data and not total
Chromium (VI).
Cobalt
3.7
2.4
3.802
1
Acceptable
Acceptable
Acceptable
Copper
1191L
3.131
3.7M
5
1000
Acceptable
Acceptable
Acceptable
Iron
AWL
817.5
336.6
675.8
300
Acceptable
Acceptable
Acceptable
Lead
0.738
0.348
1
15
Acceptable
Acceptable
Acce table
Magnesium
m
1.517
8.723
13.6
NE
Acceptable
Acceptable
Acc table
Man anew
82
187.1
310
50
Acceptable
Acceptable
Acceptable
Page 1 of 2

Marshall Steam Station - Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy Calculated PBTVs
Flow Unit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
Shallow
Deer
Bedrock
Shallow
Deep
Bedrock
Mercury
0.05
0.2
0.05
1
Not Acceptable
Acceptable
Not Acceptable
Shallow, deep, and bedrock Non -Par. UTL - 0.2 u
Methane
to
10
16.4
NE
Acceptable
Acceptable
Acceptable
Molybdenum
AgIL
0.684
9
4.262
NE.
Acceptable
Acceptable
Acceptable
Nickel
ggfL
5.944
7.325
5
100
Acceptable
Acceptable
Acceptable
Nitrate + Nitrite
m -N/L
1.6
0.8946
0.38118
ll*
Acceptable
Acceptable
Acceptable
Potassium
m
5
4.453
8.19
NE
Acceptable
Acceptable
Acceptable
Selenium
0.5
0.5
1
20
Acceptable
Acceptable
Acceptable
Sodium
mg/L
9.753
39.917
14
NE
Acceptable
Not Acceptable
Acceptable
Deep - Removed 7,550 ug/L Gamma UTL - 42.61 mg/L. Duke should verify value removed to ensure value
was in proper units revise if needed.
Strontium
197.1
548.2
195
NE
Acceptable
Acceptable
Acceptable
Sulfate
m
1.9
50.259
14.4
250
Acceptable
Acceptable
Acceptable
Sulfide
m
0.1
0.1
0.1
NE
Acceptable
Acceptable
Acceptable
TDS
mg/L
79.833
257.046
177
500
Acceptable
Not Acceptable
Acceptable
Deep Normal UTL - 221.1 ug/L. Please revise accordingly.
Thallium
0.2
0.1
0.2
0.2
Acceptable
Acceptable
Acceptable
TOC
mg/L
1 1
4
1
NE
Acceptable
Acceptable
Acceptable
Vanadium
99fL
6.884
4.373
22,93
0.3
Acceptable
Acceptable
Acceptable
Zinc
t5.93
31.05
10
1000
Acc table
Acce table
Acc table
Radium (Total)
Ci/L
U.47
NA
1.884
NE
Acc table
Acc table
Acc table
Uranium Total)
mL
0.0005
ti N
0.0005
NE
Acceptable
Acceptable
Acceptable
NA - Not Applicable
ND - Not Detected
NE - Not Established
S.U. - Standard Unit
TOC - Total Organic Carbon
TDS - Total Dissolved Solids
mg/L - milligrams per liter µg/mL - micrograms per milliliter
pCi/L - picocuries per liter µg/L - micrograms per liter
Radium (Total) - Radium-226 and Radium-228 combined Uranium (Total) - Uranium-233, Uranium-234, Umnium-236, and Uranium-238 combined
*The 15A NCAC 02L Standard is 10 mg/L for Nitrate and 1 mg/L for Nitrite (added for a total of I 1 mg(L)
Page 2 of 2

Marshall Steam Station - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energ}
Calculated
PBTVs
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Acceptable)
Comments
H
S.U.
4.1-6.7
NE
Acceptable
Aluminum
mg/kg
25978
NE
Acceptable
Antimony
mg/kg
NA
0.9
Not Acceptable
Use PSRG of 0.9. To be revised when valid data set is available.
Arsenic
mg/kg
3.7
5.8
Acceptable
Only 3 valid samples in data set.
Barium
mg/kg
312.9
580
Acceptable
Beryllium
m
2.8
63
Not Acceptable
Gamma UTL - 4.52 mg/kg
Boron
mg/kg
56.3
45
Acceptable
Cadmium
mgfkg
NO
3
Acceptable
Calcium
mgfkg
718
NE
Not Acceptable
Normal UTL - 999.1 mg/kg.
Chloride
mg/kg
NO
NE
Acceptable
Chromium
mg/kg
24.64
3.8
Acceptable
Cobalt
mg/kg
46.5
0.9
Acceptable
Copper
m
88.76
700
Acceptable
Iron
mg/kg
78988
150
Acceptable
Lead
m
_ 15.36
270
Acceptable
Magnesium
mg/kg
_
33058
NE
Not Acceptable -
Normal UTL - 14,554 m
Manganese
m
1748
65
Acceptable
Mercury
mg/kg
(1.07778
1
Acceptable
Molybdenum
m
_ 111)
NE
Acceptable
Nickel
mglkg
15.85 _
130
Acceptable
Nitrate as N)
m
NO
�21444
NE
Acceptable
Potassium
mgfkg
NE
Not Acceptable
Normal UTL - 21,063.5 mg/kg.
Selenium
mg/kg
NA
2.1
Not Acceptable
Use PSRG of 2.1. To be revised when valid data set is available.
Sodium
mg/kg
NO
NE
Acceptable
Strontium
mgtkg
9.869
NE
Acceptable
Sulfate
mg/kg
ND
NE
Acceptable
Thallium
mgIkg
N:%
0.28
Not Ace e table
jUse PSRG of 0.28. To be revised when valid data set is available.
Vanadium
mg/kg
2026.
6
Acceptable
Zinc
mg/kg
105.4
1200
Acceptable
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

L. V. Sutton Energy Complex- Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy Calculated PBT\'s
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Ace e table)
Comments
Flow Unit
Flow Unit
Surficial
t pier,
Surilcld Pee Dee
Lower 1'over
Pee flee
Lmvrer
Surficial
Upper
Surficial
Lower
Pee Dee
Upper
Pee Dec
Lower
H
S.U.
3.94 5
__ 5
95a
I
1 J::i,17
4.9 - 7.4 L R.2 - 8.9
9 - 9,7
6.5-8.5
Acceptable
Acceptable
Not Acceptable
Not Acce table
Insufficient datasets for the Upper and Lower Pee Dee. Additional samples am needed for valid
statistical analysis. To be revised when valid data set is available.
Alkalinity
mg/L
171 1 410
7. _ 593
I
464
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Aluminum
µg/L
73
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Antimony
µg/L
1
1
1
10
Acceptable
Acceptable
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Arsenic
3
Barium
Beryllium
g/L
µ
45
I
_
17
I 1
27
1
391
3520
1
700
4
NE
700
2
Acceptable
Ace table
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Not Acce table
Not Acce table
Not Acee table
Not Acceptable
Bicarbonate
mg/L
5
_ _
I'1 402
Boron
50
_
50 3010
Cadmium
1
_
1 1
Calcium
mg/L
0.996
22.6
9.47
48
NE
NE
Acceptable
Acceptable
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Carbonate
m L
S
5 _ _20
_ _21.o_ 68_0
Chloride
mg/L
4.73
1200
250
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Chromium (VI)
µgH-
0.03
0.11 0.26
0.1
NA
Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
Surficial Lower: Insufficient data set for hex chrome. To be revised when valid data set is available.
insufficient datasets for the Upper and Lower Pee Dec. Additional samples are needed for valid
statistical anaysis. To be revised when valid data set is available.
Chromium
L
1
4
I
3
2
1
1
10
Acc [able
Acceptable
Not Acceptable
Not Acceptable
Insufficient damsels for the Upper and Lower Pee Dee. Additional samples are needed for valid
statistical anaysia To be revised when valid data se[ is available.
Cobalt
1191L
1
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Copper
µg/L
1
I
_
1
1
1000
Acceptable
Acceptable
I Not Acceptable
Not Acceptable
Iron
g/L
1494
13416
336
102
300
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Lead
1
1
1
1
15
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Magnesium
m
0.589
W
13.5
13.7 .
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Manganese
38
746
63
5
50
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Mercury
L
I 0.05
0.05
0.05
0.05
1
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Methane
µg/L
25.8
36.1
121
19.6
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Molybdenum
µ
1
1
20.7
16.1
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Nickel
L
1
I 1
1
3.29
100
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Nitrate+ Nitrite
Potassium
Selenium
mg -NH-
mg/L
0.167
0.738
1
0.098
4.97
I
0.01 0.011
211.5 _ 48
I 5
11 a
NE
20
Acceptable
Acceptable
Acceptable
I Acceptable
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Not Acceptable
I Not Acceptable
Not Acceptable
Not Acceptable
Sodium
mg/L
_
3 _ 18,5 !
8 16-
15.6 16
0.1 _ r 0.1
25 210
_
584 _ 939
232 329
..20 SSU
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Strontium
µ L
NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Sulfate
mg/L
250
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Sulfide
m L
1 0.14
1.8
1 NE
Acceptable
Acceptable
Not Acceptable
Not Acceptable
TDS
mg/L
1700
1800
500
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Thallium
p9fL
0.2
0.2
0.2
0.2
0.2
Acceptable
Acceptable
Not Acceptable
Not Acceptable
TOC
mg/L
0.692
6.7
33
6.6
NE
I Acceptable
Acceptable
I Not Acceptable
Not Acceptable
Vanadium
0.621
1.68
1.88
0.481
0.3
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Zinc
µg/L
5
13
_
5
6
1000
Acceptable
Acceptable
Not Acceptable
Not Acceptable
Radium (Total)
Uranium (Total)
Ci/L
/ml,
2.75
0.00035
5.32
030a14
2 4�5.5.1
0.00153
0.00077
NE
NE
Acceptable
Acce table
Acceptable
Acce table
Not Acceptable
Not Aeee table
Not Acce table
Not Acce table
NA- Not Applicable
NO -Not Delected
NE -Not Established
mg/L - milligrams per liter
pCUL - picocuries per liter
Radium (Total) - Radiurn-226 and Radium--228 combined
'The 15A NCAC 02L Standard is 10 mg/L for Nitrate and 1 mg/L for Nitrite (added for a total of I I mg/L)
S.U. -Standard Unit
TOC - Total Organic Carbon
IDS - Total Dissolved Solids
pg/mL - micrograms per milliliter
jig - micrograms per liter
Uraniurn (TOW) - Ursedura-233, Uranimn-234, Uranimn-236, and Umnimn-238 combined

L. V. Sutton Energy Complex - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
�alrulated
PR.I,N s
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Acceptable)
Comments
H
S.U.
NE
Only two valid samples, therefore dataset is insufficient. Additional samples planned for collection. To be revised when valid data set is available.
Aluminum
mg/kg
_
NE
Antimony
mgIkg
0.9
Arsenic
m
5.8
Barium
m
580
Beryllium
mg/kg
63
Boron
mg/kg
45
Cadmium
mg/kg
3
Calcium
m
NE
Chloride
mgtkg
NE
Chromium
m
3.8
Cobalt
mg/kg
0.9
Copper
mg/kg
700
Iron
m
150
Lead
m
270
Magnesium
m
NE
Manganese
mglkg
65
Mercury
mgfkg
1
Molybdenum
mg/kg
NE
Nickel
mg/kg
jja.
130
NE
Nitrate (as N)
mg/kg
Potassium
mg/kg
NE
Selenium
mg/kg
2.1
Sodium
mg/kg
NE
Strontium
mg/kgmg1kg
NE
Sulfate
mgfkg
250
Thallium
mg/kg
0.28
Vanadium
m
6
Zinc
mglkg
1200
NA -Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligatns per kilogram
S-U. - Standard Unit

W. H. Weatherspoon Power Plant- Groundwater Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy ('alculated PH I V%
llnw Cnit
15A NCAC 02L
Standard or
IMAC
DWR Concurrence (Acceptable/Not Acceptable)
Comments
Flow Unit
Surficial
1'urktown
Pee Dee
Surficial
Yorktown
Pee Dee
H
S.U.
3.21-6.87
5.5.5.7
6.9-8.3
6.5-8.5
Acceptable
Acceptable
Acceptable
Alkalinity
mg/L
36.5
_17.4
89
NE
Acceptable
Acceptable
Acceptable
Aluminum
1191L
_
1460
492
66
NE
Acceptable
Acceptable
Acceptable
Antimony
L
♦D
1
1
1
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value, 1 L.
Arsenic
L
1.35
1
1
10
Acceptable
Acceptable
Acceptable
Barium
31.9
21
56
700
Acceptable
Acceptable
Acceptable
Beryllium
991L
ND
1
1
4
Not Acceptable
Acceptable
Acceptable
ISurficial should be a numeric value, 1 L.
Bicarbonate
mgfL
36.5
17.4
89
NE
Acceptable
Acceptable
Acceptable
Boron
W111,
ND
50
50
700
Not Acceptable
Acceptable
Acceptable
JSurficial should be a numeric value, I L.
Cadmium
L
ND
1
1
2
Not Acceptable
Acceptable
Acceptable
Surlicial should be a numeric value, I
Calcium
mgfL
14.5
7.92
M
NE
Acceptable
Acceptable
Acceptable
Carbonate
mg/L
ND
5
10
NE
Not Acceptable
Acceptable
Not Acceptable
Surficial should be a numeric value, 5 mg/L.
MDL for Pee Dee was 5 m l 5z 10 mg/1 only 3z .
Chloride
m
22.2
10
3.4
250
Acceptable
Acceptable
Acceptable
Chromium (VI)
uWL
01147
0.84
0.2
NA
Acceptable
Acceptable
Acceptable
Chromium
uWL
1.63
1 ?4
1
10
Acceptable
Acceptable
Acceptable
Cobalt
L
_
\ D
1
1
20'u
I
t 1
t I550
I
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value, I L.
Copper
L
ND
132_31
1000
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value I
Iron
300
Not Acceptable
Acceptable
Acceptable
Surficial calculated to be 9422
Lead
SU
1
1
15
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value, 1 L.
Magnesium
mg/L
I.39 0.487 _ a 1.11 _
39 _ 20 r 41
ti1105 005
NE
Acceptable
Acceptable
Acceptable
Manganese
50
Acceptable
Acceptable
Acceptable
Mercury
8&1
1
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value, 0.05
Methane
L
41'. iOxU 2J8
NE
Acceptable
Acceptable
Acceptable
Molybdenum
- j I 1
_ �D _ - - I _ 1
2.09 _ -0-11-1 11.01
1.16 _ O'shS L62
NE
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value 1
Nickel
100
Not Acceptable
Acceptable
Acceptable
Surficial should be a numeric value, 1
Nitrate + Nitrite
mg -NIL
it-
Acceptable
Acceptable
Acceptable
Potassium
mg/L
NE
Acceptable
Acceptable
Acceptable
Selenium
ND
I I
20
Not Acceptable
Acceptable
Acceptable
IStaficial should be a numeric value, 1
Section
m
13
xx
6 _ 272 _
41 164
1.l a 0.24
0.1 b 1 _ _
75 130_
NE
Acceptable
Acceptable
Ace table
Strontium
AWL
NE
Acceptable
Acceptable
Acceptable
Sulfate
IUZIL
13.7
250
Acceptable
Acceptable
Ace ble
Sulfide
ingfL
0.29
NE
Acceptable
Acceptable
Ace ble
TDS
mg/L
90 .3
500
Acceptable
Acceptable
Ace ble
Thallium
L
ND
0.2 0 2
0.2
Not Acceptable
Acceptable
Ace ble
Surficial should be a numeric value, 0.2 µg/L.
TOC
mg/L
7.9
3.5
1.1
NE
Acceptable
Acceptable
Ace table
Vanadium
L
4.65
E.61
0.32
0.3
Not Acceptable
Acceptable
Ace ble
Surficial calculated to be 4.2 L.
Zinc
µ
10
5
5
1000
Acceptable
Acceptable
Acc table
Radium Total
Ci/L
7.09
S.4
3.55
NE
Not Acceptable
Acceptable
A. ptable
JSurficial calculated to be 6.463 i/L.
Uranium (Total)
ggfmL
0.0006
0.001
1 0.6004
NE
Acceptable
Acc table
Acceptable
NA -Not Applicable
ND -Not Detected
NE - Not Established
mg/L -millibar. per Ike,
pCi/L - picocmies per liter
Radium (Total) - Radiun-226 and Radium-228 combined
-The ISA NCAC 02L Standard m 10 mg/L for Nitrate and 1 ,11, for Nitrite (added for a total of I I mg/L)
S.U.-Standard Unit
TUC - Tom[ Organic Carbon
TDS - Total Dissolved Sell&
µg/snL - micrograms per milli@er
µgo - micrograms per liter
Umoiam (Toml) - Uranium-233, Uranium-234, Umnimn-236, and Ummum-238 combined

W. H. Weatherspoon Power Plant - Soil Provisional Background Threshold Values
Parameter
Reporting
Units
Duke Energy
Calculated
PB -f%s
PSRG Protection
of Groundwater
DWR Concurrence
(Acceptable/Not
Accepts le)-
Comments
H
S.U.
NE
Insufficient dataset. Additional data to be provided by Duke Energy. To be revised when valid data set is available.
Aluminum
mg/kg
NE
Antimony
mg/kg
0.9
Arsenic
m
5.8
Barium-
m
580
Beryllium
- mg/kg
63
Boron
mg/kg
45
Cadmium
m
3
Calcium
m
NE
Chloride
mglkg
NE
Chromium
mg/kg
3.8
Cobalt
mg/kg
- - - -_
0.9
Copper
mg/kg
700
Iron
m
_—
150
Lead
m
270
Magnesium
m
_ _ _ _
NE
Manganese
mg/kg
65
Mercury
mg/kg
_
1
Molybdenum
mg/kg
NE
Nickel
mg/kg
130
Nitrate (as N)
mg/kg
NE
Potassium
m /k
NE
Selenium
mg/kg
2.1
Sodium
m /kg
NE
Strontium
m
NE
Sulfate
m
250
Thallium
m g
0.28
Vanadium
m /kg
6
Zinc
m o
1200
NA- Not applicable (dataset contains zero valid samples)
ND -Non-Detect
NE - Not Established
mgtkg - milligrams per kilogram
S.U. - Standard Unit

Water Resources .,
Environmental Quality
April 27, 2018
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
Subject: Corrective Action Plan Content for Duke Energy Coal Ash Facilities
Dear Mr. Draovitch:
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Interim Director
Attached is guidance related to technical content and format the Department requests be followed
for the upcoming Corrective Action Plan (CAP) Update documents associated with the Duke
Energy coal ash facilities. Please note that pursuant to Title 15A North Carolina Administrative
Code, Subchapter 02L (15A NCAC 02L) Rule .011l(a), any person subject to the requirements
for corrective action specified in 15A NCAC 02L .0106 shall submit to the Director written reports
in such detail as specified by the Director. The CAP shall contain sufficient information for the
Secretary to evaluate the plans in accordance with the specifications in 15A NCAC 02L .0106(i).
The CAP content for Duke Energy coal ash facilities is provided in Attachment 1. If you have any
questions, please feel free to contact me at [phone] or Steve Lanter in the Central Office at
[phone].
Sincerely,
S. Jay 2iinynerman, P.G.
Division of Water Resources
Attachments: Attachment 1 Corrective Action Plan Content for Duke Energy Coal Ash Facilities
cc: WQROS Regional Office Supervisors
WQROS Central File Copy
<-- "Nothing Cornpaires n�,
State of North Carolina I Environmental Quality I Division of Water Resources
Water Quality Regional Operations Section
1636 Mail Service Center I Raleigh, North Carolina 27699-1636
919-707-9129

CORRECTIVE ACTION PLAN CONTENT FOR
DUKE ENERGY COAL ASH FACILITIES
APRIL 27, 2018
Best professional judgement must be applied to generate the Corrective Action Plan (CAP) documents. In
general, all items described in this guidance are expected to be addressed in the CAPs. Duke Energy must
provide justification/rationale concerning any information not provided as stipulated in this guidance.
1 INTRODUCTION
A. Background
B. Purpose and Scope
C. Regulatory basis for closure and corrective action (note that "closure" refers here to source
control and (or) source excavation in accordance with Coal Ash Management Act (CAMA) and
(or) 15A NCAC 02L (02L) .0106, while "corrective action", "remediation", or "remedy" refer
here to the treatment of groundwater contamination)
a. CAMA requirements
b. 02L requirements, including Notice of Regulatory Requirement dated 8/13/14
c. Other requirements such as court order, Federal requirements, etc.
D. List of Criteria for Evaluation of Remediation Alternatives as referenced in 02L .0106 (i)
a. Extent of any violations
b. Extent of any threat to human health or safety
c. Extent of damage or potential adverse effects to the environment
d. Technology available to accomplish restoration
e. Potential for degradation of the contaminants in the environment
f. Time and costs estimated to achieve groundwater quality restoration
g. Public and economic benefits to be derived from groundwater quality restoration.
E. Facility Description (brief summary from Comprehensive Site Assessment [CSA))
a. Location and history of land use (to include period prior to Duke ownership)
b. Operations and waste streams (coal and non -coal)
c. Overview of existing permits and Special Orders by Consent (National Pollutant
Discharge Elimination System, storm water, sediment and erosion control, etc.)
2. RESPONSE TO COMPREHENSIVE SITE ASSESSMENT UPDATE COMMENTS IN SUPPORT OF CAP
DEVELOPMENT
A. Include the Facility -Specific Comprehensive Site Assessment (CSA) Comment Letter from DEQ
to Duke Energy
B. Duke Energy's response to the DEQ's letter. (NOTE: All deficiencies noted during the
Departments' review of the CSA Update report shall be addressed in the CAP.
1

a. For each comment in the letter, note the specific section(s) of the CAP report that
addresses that comment.
b. If specific sections of the CAP report do not fully or directly address the comment,
provide a separate narrative within the Appendix to address.
3 OVERVIEW OF SOURCE AREAS BEING PROPOSED FOR CORRECTIVE ACTION
Each source area has a unique waste footprint, waste volume and configuration, contaminant
configuration and transport characteristics, and receptors. Consequently, each source area will
potentially need to be remediated in a unique way. For purposes of remediation design and
approval, each source area should be addressed separately as described in this document.
Arranging the report in this way will support an organized, orderly, and efficient review of the
proposed remedy. For facilities in which only one source area is defined (or multiple source areas
that can be combined into a single largersource area), the CAP sections which pertain to additional
source areas would not be needed. It is not the intent to require a separate CAP Report submittal
for each source area, rather a single facility CAP (Cliffside, e.g.) submittal may contain the contents
of multiple source areas.
A. Small scale map showing the waste boundary of each source area proposed for corrective
action
a. For cases in which more than one smaller source area is being combined as one larger
source area, show each "sub area" on the waste boundary map (i.e. show the waste
boundaries of the individual smaller source areas that are within the larger source
area)
B. For cases in which there are source areas that are not being addressed within the CAP,
provide:
a. Rationale for omission
b. Certification that consensus was reached with the Division on this point.
c. Description that explains the implications for assessment overlap, corrective action
overlap, design, and approval, performance monitoring, potential corrective action
modification and schedule delays.
4 SUMMARY OF BACKGROUND DETERMINATIONS
A. Map showing all background sample locations for all media (groundwater, surface water, soil,
and sediments)
B. Table of background concentrations for soil. Include the corresponding Protection of
Groundwater (POG) Preliminary Soil Remediation Goal (PSRG). Approved Background
Threshold Values (BTVs) for soil and groundwater will be sent to Duke in a letter separate
from the CSA Comments. Please list the approved BTVs.
C. Table of background concentration for groundwater. Include the appropriate 2L/IMAC
Standards. Approved Background Threshold Values (BTVs) for soil and groundwater will be
sent to Duke in a letter separate from the CSA Comments. Please list the approved BTVs.

D. Table of background concentrations for surface water. Include the appropriate 2B/EPA
standards. Present results of all surface water samples and sample events from upstream
locations.
E. Table of background concentrations for sediments. Present results of all sediment samples
and sample events from upstream or otherwise unimpacted sample locations.
5 SUMMARY OF POTENTIAL RECEPTORS
A. Map of all supply wells identified by receptor surveys and per 130A-309.211(cl).
a. Incorporate the most current alternate water supply efforts. That is, indicate which
well owners selected whole -home filtration systems, public water, or opted -out of
any alternate water supply options.
b. Indicate which homes have whole -house filtration systems installed and which homes
have been connected to public water.
c. Indicate if any homes are remaining to be supplied alternate water and the
anticipated supply date.
B. Map of all surface waters (to include wetlands, pond, unnamed tributaries, seeps, etc.) within
%:-mile of the waste boundary of each source area or known extent of contamination
(whichever is greater).
a. Indicate on map all surface waters that are currently permitted as outfalls, along with
the permitted outfall name and NPDES sampling location
b. Indicate on map all surface waters that are currently covered under a Special Order
by Consent.
c. All of the surface waters within 0.5 miles of the perimeter of an impoundment or
known extent of contamination, whichever is greater.
d. For all surface waters shown, indicate stream classification and nearest downstream
supply intake, if applicable
6. SOURCE AREA 1
Contents listed in Section 6 should be prepared separately for each additional source area (i.e.
Source Area 2, Source Area 3, etc., as applicable) in need of remediation. Discussions with the
DWR Regional Office should be initiated prior to preparation of the CAP in order to determine
which individual source areas are appropriate to combine into larger source areas.
Maps prepared for Source Area 1 should be lame scale, typically 1" = 150 to 200 ft and include
topographic contour intervals as agreed upon. However, scale adjustments may be made to
accommodate far reaching receptors; please discuss with Regional Office if this is necessary.
All plan view maps used in the CAP report should be oriented to extend to all identified receptors
(all supply wells and all surface water features), to the extent possible, based on the map scale
and size of source area being depicted.
A. Extent of Contamination
a. Contamination within waste boundary
L Description of waste material and history of placement
3

L7
ii. Specific waste characteristics of source material
iii. Volume and physical horizontal and vertical extent of source material
mapped in plan -view and multiple cross sections
iv. Volume and physical horizontal and vertical extent of saturated source
material mapped in plan -view and multiple cross sections
v. Calculation of specific storage for Source Area 1 (i.e. amount of contaminated
water and COI mass that can be expelled from Source Area 1)
vi. Chemistry within waste boundary
1. Table of analytical results, subdivided as follows:
1. Ash solid phase
2. Ash SPLP
3. Soil (beneath ash)
4. Soil (beneath ash) SPLP
5. Ash pore water
2. Piper diagram(s) for ash pore water if additional pore water data
have become available since the piper diagrams were developed in
the CSA Updates. Otherwise, reference the location of the piper
diagrams that were presented in the CSA Update.
3. Ash pore water isoconcentration maps for each COI in plan -view and
2 or more cross sections
vii. Other source material (Does source contain other waste products besides
CCR? If so, have these been assessed?)
viii. Interim response actions conducted to date to remove or control source
material, if applicable
1. Source control conducted to date or planned to include but not
limited to excavation, dewatering, boundary control measures (e.g.
extraction wells), etc.
2. Source area stabilization conducted to date or planned (e.g. describe
dam safety, flood plain inundation issues, etc.)
Extent of contamination beyond the compliance boundary or waste boundary
(whatever is the point of compliance depending on whether the source area(s) are
covered by a permit or not)
i. Conceptual model of groundwater flow and transport from source to
receptor
1. Local groundwater flow directions and gradients
2. Particle track results, if available
3. Subsurface heterogeneities affecting flow and transport
4. Onsite and offsite pumping influences affecting flow and transport
5. Role of matrix diffusion in/out of bedrock (bedrock porosity) on
contaminant transport
6. Other influences affecting flow and transport
ii. Plan view map showing COI results (bubble inset at each seep location) for
seeps and SWs
iii. Table of analytical sampling results associated specifically with Source Area
1:
I. Soil, as applicable
2. Groundwater (per individual flow regime [e.g. shallow, deep,
bedrock)
rd

3. Seeps (up-, side-, and down -gradient)
4. SW data (up-, side-, and down -gradient)
5. Sediment (up-, side-, and down -gradient)
6. Supply wells (up-, side-, and down -gradient
iv. Piper diagram(s) for each groundwater flow regime, seeps, and all other SWs.
c. COIs
i. List of COls and their maximum concentrations (within and beyond the point
of compliance) that require corrective action based on 2L/IMAC/background
exceedances:
1. Soil
2. Groundwater
3. other media if applicable
ii. List of Cols that this CAP is designed to remedy:
1. Soil
2. Groundwater
3. other media if applicable
d. Isoconcentration maps in plan -view and two or more cross sections for:
L Contaminated soil (defined as any COI in the sample being above POG PSRG
or approved background concentration)
ii. Horizontal and vertical extent of groundwater in need of restoration for each
COI in each groundwater flow regime (shallow, deep, bedrock)
e. Plume Characteristics
L Movement of conservative COls (e.g. boron, sulfate, chloride) from source to
receptor
1. Describe whether plume is moving and (or) expanding
1. Flow path wells and transect wells used to assess plume
behavior
2. Method(s) used to analyze plume behavior (should be
discussed and agreed upon with Regional Office prior to CAP
submittal)
ii. Movement of non -conservative COls (e.g. Fe, Mn, Co, As, TI, etc.)
1. Conceptual model describing local, source area -specific geochemical
controls on COls
1. Basis for conceptual understanding (e.g. batch PHREEQC
results)
2. Representative flow path(s) used to develop and validate
numerical geochemical model
3. Adsorbent data collected along flow path
4. Aqueous speciation data collected along flow path
5. Simulated versus observed COI concentrations at selected
target wells (i.e. how well does geochemical model simulate
local groundwater chemistry?)
2. Variability of pH along representative flow path(s) and along other
flow paths of interest
3. Variability of Eh along representative flow path(s) and along other
flow paths of interest
5

Receptors associated with Source Area 1
a. Map of all surface waters, including wetlands, ponds, unnamed tributaries, seeps, etc.)
associated with Source Area 1 (up-, side-, and downgradient)
L Indicate on map all surface waters that are currently permitted as outfalls, along
with the permitted outfall name and sample location
ii. Indicate on map all surface waters that are currently covered under a Special
Order by Consent
iii. For all surface waters shown, indicate stream classification and nearest
downstream supply intake, if applicable
iv. Indicate on map (footnote) and in report text whether SW samples have been
collected using Division approved protocols ("21_-213" sampling protocols) to
evaluate whether contaminated groundwater is resulting in 213 violations;
include date(s) of 2L-2B sampling and antecedent rainfall
1. If 2L-2B sampling has been conducted, indicate location of all 2L-2B
sample collection points
2. If 2L-2B sampling has been conducted, indicate results of 2B
exceedances on map; also indicate which of those exceedances is a COI
for groundwater for Source Area 1
3. If 2L-2B sampling has not been conducted, explain why and indicate
whether it is being proposed and the proposed sample collection points
b. Map of all supply wells associated with Source Area 1(up-, side-, and down -gradient)
L Indicate on map which well owners did not accept alternative water
ii. Provide analytical results table for the supply wells; indicate in table whether
each well was determined to be impacted or unimpacted by coal ash
iii. For each supply well determined to be unimpacted by coal ash, provide or
reference evidence that substantiates that position, including water level
measurement -based potentiometric mapping, piper diagrams, assessment of
well -specific geochemical conditions that are affecting certain CON, modeling,
etc. The evidence provided or referenced here will be used to review and
accept or deny Duke's determination that a given well is unimpacted by coal
ash.
c. Map of future groundwater use areas associated with Source Area 1
L Indicate on map whether each parcel has or does not have access to alternative
water
ii. Indicate on map whether each parcel was modeled to be impacted or
unimpacted by coal ash now or in the future
C. Human and Ecological Risks
D. Evaluation of Remedial Alternatives
All contents requested below for Section a. should be re )eated for each remedial alternative
that is considered (i.e. Remedial Alternative 2, Remedial Alternative 3, etc.) as directed and
appropriate.
a. Remedial Alternative 1
Problem statement and remediation goals
1. Map of full 3-dimensional extent of contamination that will be
corrected by this alternative
11

2. List of CON within each groundwater flow unit (shallow, deep,
bedrock) that will be corrected by this alternative
3. Concentration clean up goals for each of the CON identified in D. a. i.
2. above
Conceptual model (i.e. simple description explaining how the proposed
source control/removal and corrective action will reduce COI concentrations
and protect human health and environment)
1. COls addressed
2. COls not addressed
3. For each COI not addressed by the proposed corrective action
describe how the constituent will be remedied along with a schedule
for implementation
Predictive modeling
1. Model used to predict movement conservative (sometimes referred
to as leading edge) COIs
2. Model used to predict movement non -conservative CON
3. Simulated versus observed concentrations at selected target wells
(i.e. how well does transport model simulate local groundwater
chemistry?)
4. For "baseline" predictive modeling that shows source removal
(excavation) and other source control measures but no active
groundwater remediation, provide a comprehensive list of all
potential receptors that are or are predicted to be impacted and a
map for each COI showing the maximum predicted radius of travel of
that COI above 2L/IMAC (or background, if higher than 2L/IMAC)
downgradient. Also determine (i) predicted maximum concentration
of each COI in groundwater and the time that occurs and (ii)
predicted time to reduce all COI concentrations in groundwater to 2L
standards/IMACs or background if higher at the following locations:
a. Along most susceptible portion of the compliance boundary
b. At most susceptible supply well
c. At most susceptible future groundwater use area
d. At most susceptible SW(s)
5. For "groundwater remediation" predictive modeling that shows
source removal (excavation) and other source control measures AND
active groundwater remediation, provide a comprehensive list of all
potential receptors that are or are predicted to be impacted and a
map for each COI showing the maximum predicted radius of travel of
that COI above 02L/IMAC (or background, if higher than 02L/IMAC)
downgradient. Also determine (i) predicted maximum concentration
of each COI in groundwater and the time that occurs and (ii)
predicted time to reduce all COI concentrations in groundwater to
02L standards/IMACs or background if higher at the following
locations:
a. Along most susceptible portion of the compliance boundary
b. At most susceptible supply well
C. At most susceptible future groundwater use area
d. At most susceptible SW(s)
VA

iv. For remedial alternative 1, describe:
1. Protection of human health and the environment
2. Compliance with applicable federal, state, and local regulations
3. Long-term effectiveness and permanence
4. Reduction of toxicity, mobility, and volume
5. Short term effectiveness at minimizing impact on the environment
and local community
6. Technical and logistical feasibility
7. Time required to initiate
8. Predicted time required to meet remediation goals described in D. a.
L 3. above
9. Cost
10. Community acceptance
E. Proposed remedial alternative(s) selected for the source area 1 and/or sub -areas of source
area 1.
Note that multiple corrective actions may be necessary to address different locations within
source area 1 or any of its sub -areas. This could involve "compartmentalizing" the source area
and describing the specific selected corrective actions for each "compartment."
a. Description of proposed remedial alternative and rationale for selection
L Specific section of 02L .0106 being addressed by the proposed remedy [e.g.
02L .0106 (1) or (k)]
ii. Will a hybrid remedy consisting of more than one corrective action be used?
If so, describe.
iii. Will proposed remedy or hybrid remedy meet concentration cleanup goals
defined in D. a. i. 3. above?
iv. Treatability studies
1. Results of post-CSA Update treatability studies, if applicable
v. Additional site characterization needed to support the proposed remedy
1. Locations and specific testing, sampling, modeling, and (or) data
analysis
2. Schedule for data collection and reporting
b. Design details
I. Process flow diagrams for all major components of proposed remedy
ii. Engineering designs with assumptions, calculations, specifications, etc.
iii. Permits needed for proposed remedy and approximate schedule for
obtaining them
iv. Schedule and cost of implementation
v. Measures to ensure the health and safety of all persons on and off site
vi. Description of all other activities and notifications being conducted to ensure
compliance with 02L, CAMA, and other relevant laws and regulations
c. For 02L .0106 (1) CAP, provide requirements outlined in DWR's Monitored Natural
Attenuation for Inorganic Contaminants in Groundwater. Guidance for Developing
Corrective Action Plans Pursuant to NCAC 15A [02L].0106(I).
d. For 02L .0106 (k) CAP, provide requirements outlined in 02L .0106 rule
e. Sampling and reporting
i. Proposed progress (i.e. "effectiveness") reports and schedule
ii. Proposed sampling and reporting plan during active remediation
8

iii. Proposed sampling and reporting plan after termination of active
remediation (if proposed)
1. Decision metrics for termination of active remediation and start of
"monitoring only" phase
A. Proposed wells for COI trend analysis
B. Proposed statistical method for trend analysis
f. Proposed interim activities prior to implementation
g. Contingency plan in case of insufficient remediation performance
i. Description of contingency plan
ii. Decision metrics (triggering events) for implementing contingency plan
7. PROFESSIONAL CERTIFICATIONS
Sealed and notarized professional statements of "true, accurate, and complete".
8. REFERENCES
9. TABLES
10. MAPS AND FIGURES
11. APPENDICES - Flow and Transport Modeling
For Flow model report content, refer to report titled 'Updated groundwater Flow and Transport
Modeling Report for Asheville Steam Electric Plant, Arden, NC (Ronald Falta and others, March
17, 2017). Also include the following:
• List of all model assumptions
• List all model limitations that affect output (including, for example, unconfirmed
boundary positions, unmodeled heterogeneities, scale of cell volume versus scale of well
observations, limited input data, limited data for calibration and calibration assessment,
etc.)
• List of variables for which sensitivity analyses were quantitatively presented
• Describe how model is being used in closure/corrective action design and review
For transport model report content, refer to report titled 'Updated groundwater Flow and
Transport Modeling Report for Asheville Steam Electric Plant, Arden, NC (Ronald Falta and others,
March 17, 2017). Also include the following:
• List of all model assumptions
• List all model limitations (including, for example, limitations of Kd, unconfirmed boundary
positions, unmodeled heterogeneities, scale of cell volume versus scale of well
observations, limited input data, limited data for calibration and calibration assessment,
etc.) that affect output
• List of variables for which sensitivity analyses were quantitatively presented
• Describe how model is being used in closure/corrective action design and review
APPENDICES - Geochemical Modeling
0

For geochemical report content, refer to memorandum titled, 'Geochemical modeling of
constituent behavior at CAMA disposal sites' (Brian Powell, January 29, 2018) and memo titled
'Summary and Comments on Geochemical Modeling Outline with MNA Considerations (Bill
Deutsch, February 7, 2018). Also include the following:
• List of all model assumptions
• List all model limitations (including, for example, lack of pertinent data for points along
an individual flow path, if applicable, heterogeneities, limited input data, etc.) that affect
output
• List of variables for which sensitivity analyses were quantitatively presented
• How model is being used in closure/corrective action design
APPENDICES — Other
10

J y
Water Resources
Environmental Quality
June 15, 2018
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
Subject: Approval of Revised Background Threshold Values
Marshall Steam Station
Dear Mr. Draovitch:
ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Interim Director
The North Carolina Department of Environmental Quality's (DEQ) Division of Water Resources
(DWR) has reviewed Duke Energy's calculated revised provisional background threshold values
(PBTVs) for soil and groundwater for the subject facility. DWR reviewed the calculated PBTVs based
on background data provided in the revised Comprehensive Site Assessment (January 2018), using the
Revised Statistical Methods for Developing Reference Background Concentrations for Groundwater
and Soil at Coal Ash Facilities dated May 26, 2017 and additional guidance provided in the December
7, 2017 email from Steve Lanter to Ed Sullivan and John Toepfer. DWR hereby approves all accepted
PBTVs for groundwater and soil as outlined in the attached tables. These accepted PBTVs shall
become the Background Threshold Values (BTVs) for the facility and will serve as a basis for the
proposed remedial alternatives in the upcoming Corrective Action Plans.
Per 15A NCAC 02L .0202(b)(3), where naturally occurring substances exceed the established
groundwater standard, the standard shall be the naturally occurring concentration as determined by the
Director. Therefore, BTVs calculated above the groundwater standards or Interim Maximum
Allowable Concentrations (IMACs) in accordance with the provisions in 15A NCAC 02L .0202 and
accepted by DWR, shall become the enforceable groundwater standard. Otherwise, the enforceable
groundwater standards shall be those listed under 15A NCAC 02L .0202(h) including any effective
IMAC s.
For soils, PBTVs that are calculated above the DEQ Division of Waste Management Inactive
Hazardous Sites Branch's (IHSB) Preliminary Soil Remediation Goals (PSRG) for the protection of
groundwater shall become the BTVs for use in developing an appropriate corrective action strategy.
For compounds that do not have an established PSRG, but do have a groundwater standard (i.e. chloride
and sulfate) pursuant to 15A NCAC 02L .0202, use the calculation provided in the PSRG table to
establish a PSRG if the required site -specific data are available. The PSRG table can found under the
IHSB website at: https:Hdeq.nc.gov/about/divisions/waste-management/Werf md-section/inactive-
hazardous-sites-program.
—'7�' Nothing C=pares ,.,
State of North Carolina I Environmental Quality I Division of Water Resources
Water Quality Regional Operations Section
1636 Mail Service Center I Raleigh, North Carolina 27699-1636
919-707-9129

The attached tables outline DWR's concurrence/non-concurrence with Duke Energy's proposed
calculated PBTVs for groundwater and soil. For all of Duke Energy's calculated PBTVs that are listed
as acceptable, DWR hereby approves those values. For those BTVs not found acceptable, justification
is provided on the attachment and Duke Energy is responsible for providing revised values for review
and approval. For any BTVs found to be unacceptable due to an inadequate dataset, Duke Energy shall
continue to collect data until an adequate dataset is achieved and a valid statistical calculation can be
performed.
Along with the specific comments provided on the attachments, DWR offers the following general
comments with regards to the BTVs:
• Please note that the IHSB's PSRG table was revised in February 2018. With respect to the
constituents being evaluated for the CSA, the following PSRG values have been revised.
o PSRG for Aluminum is currently 110,000 mg/kg.
o PSRG for Chromium is currently 3.8 mg/kg.
o PSRG for Molybdenum is currently 7.1 mg/kg.
o PSRG for Vanadium is currently 350 mg/kg.
DWR recognizes that, as new information is gathered going forward, the approved BTVs may be
refined. Thus, there will be need for a periodic review and recalculation of the BTVs. The timeframes
for the periodic review will be established by DWR at a later date and any revised BTVs will be subject
to approval by DWR's Director.
If you have any questions, please contact Brandy Costner (Mooresville Regional Office) at (704) 663-
1699 or Steve Lanter (Central Office) at [phone].
Sincerely,
Linda Culpepper, Director
Division of Water Resources
Attachments
cc: MRO WQROS Regional Office Supervisor
WQROS Central File Copy

Marshall Steam Station - Groundwater Background Threshold Values (6/15/2018)
Parameter
Reporting
Units
Duke Energy Calculated PBTVs from
CSA Report (January 31, 2018)
15A NCAC
Standard
or IMAC
DWR Concurrence (Acceptable/Not
Acceptable)
Comments
Flow Unit
Flow
Flow Unit
Shallow
Deep
Bedrock
Shallo,*
Deep
Bedrock
H
S.U.
4.6-6A
5.7-6.9
5.6-7.6
6.5-8.5
Acce lablc
Acceptable
Acceptable
Alkalini
mg/L
63
204
108
NE
Acceptable
Acceptable
Acceptable
Aluminum
jtL1.1,
757
128
300
NE
Accc table
Acceptable
Acceptable
juitirnorly
A91L
0.5
OS
0.5
1
Acceptable
Acceptable
Acceptable
Arsenic
jtF1,
0.4
0.6
0.6
10
Acceptable
Acceptable
Accr table
Barium
t 'L
310
127
435
700
Acceplable
Acceptable
Acceptable
Beryllium
lip -I.
0.2
0.1
1 0.2
4
Acceptable
Acceptable
Acceptable
Bicarbonate
mg'L.
63
204
108
NE
Acce table
Acceptable
Acceptable
Boron
L
50
50
50
700
Acceptable
Acceptable
Acceptable
Cadmium
i g L
0.08
0.08
0.08
2
Acceptable
Acceptable
Acceptable
Calcium
m '1
10.7
13.1
15
NE
Acceptable
Acceptable
Acceptable
CaT1113nate
m •IL
5
5
5
NE
Acceptable
Acceptable
Acceptable
Ebb ride
mg/L
5.5
4.7
4.5
250
Acceptable
Acceptable
Acceptable
Chromitim(VI)
L
5.7
3
3.9
NA
Acce table
Acceptable
Acce table
Chnimium
L
16.5
7.6
8.3
10
Acceptable
Acceptable
Acceptable
Cobalt
L
1.2
1.9
2.8
1
Acceptable
Accc table
Acce table
Copper
t 'L
3.8
2.8
4.2
1,000
Acec fable
Acceptable
Acceptable
Iron
L
744
272
792
300
Acceptable
Acceptable
Acce table
Lead
JLVIL
0.3
0.1
0.2
15
A[te Whle
Acceptable
Acceptable
Maemaiuni
nw!L
1.8
14.4
13.2
NE
Acceptable
Acceptable
Acceptable
Mattyaricsc
JIUL
75.3
141
26.6
50
Acceptable
Acceptable
Acceptable
Mercury
"L
0.2
0.2
0.2
1
Acceptable
Acceptable
Acceptable
Methane
jiv L
10
10
10
NE
Acce iable
Acceptable
Acceptable
Molybdenum
PgL
0.5
3.2
3
NE
Acceptable
Acceptable
Acceptable
Nickel
L
9.9
7.5
7.2
100
Acceptable
Acceptable
Acceptable
Nitralc+Nitrite
mg-N/L
2.7
1A
0.4
ll*
Acceptable
Acceptable
Potassium
mv.1
5
7.8
9.8
NE
I Acceptable
-Acceptable
Acceptable
Acceptable
Selenium
VgL
0.5
0.5
0.5
20
Acceptable
Acc table
Acceptable
Removed 10 as an outlier in the shallow
Sodium
m L
9.1
29.2
14
NE
Acce fable
Acceptable
Acceptable
Strontium
t • L
303
665
253
NE
Acc lablr
Acceptable
Acceptable
Sulfate
rML
4.2
17.7
18.4
250
Acceptable
Acceptable
Acceptable
Sulfide
m g IL
0.1
0.1
0.1
NE
Acceptable
Acceptable
Acceptable
TDS
mL/L
140
193
216
500
Acceptable
Acceptable
Acceptable
Thallium
jS L
0.1
0.1
0.1
0.2
Acceptable
Acceptable
Acceptable
Toc,
mvL
1
1
1
NE
Acceptable
Acceptable
Acce.table
Vanadium
L
5.6
3.8
16
0.3
Acceptable
Acceptable
Acceptable
Zinc
PPL
19.2
17
11.9
1,000
Acce sable
Acceptable
Acceptable
Radium (Total)
pCill,
3
2.8
5.7
NE
Accc tabk
Acceptable
Acceptable
Uranium (Total)
A&mL
0.0005
0.0005
0.0005
NE
Acceptable
Acceptable
Acceptable
NA - M1Or Appl�anl!
ND - Not Detected
NE - Not Established
mg/L - milligrams per liter
pCi/L - picocuries per liter
Radium (Total) - Radium-226 and Radium-228 combined
;The I SA NCAC 02L Standard is 10 mg/L for Nitrate and 1 mg/L for Nitrite (added for a total of I l mg/L)
S.U. - Standard Unit
TOC - Total Organic Carbon
TDS - Total Dissolved Solids
µg/mL - micrograms per milliliter
µg/L - micrograms per liter
Uranium (Total) - Uranium-233, Uranium-234, Uranium-236, and Uranium-238 combined
Page 1 of 1

Marshall
Steam Station - Soil
Background Threshold Values (6/15/2018)
Parameter
Reporting
Units
Duke Energy
Calculated PBTVs
from CSA Report
(January 31, 2018)
PSRG Protection of
Groundwater (as of
February 2018)
DWR Concurrence
(Acceptable/Not
Acceptable)
Comments
H
S.U.
4.7-6.1
NA
Acceptable
Aluminum
mwkg
56A37
110,000
Acceptable
Antimony
mg/kg
0.65
0.9
Acceptable
Arsenic
mg/kg
4.697
5.8
Acceptable
Barium
mg/kg
819
580
Acceptable
Beryllium
tn&g
3.9
63
Acceptable
Boron
mg/kg
8.7
45
Acceptable
Normal UTL=10.69
Cadmium
mg/kgmg?kg
0.11
3
Acceptable
Calcium
m k =
1.500
NE
Acceptable
Chloride
mg/kp,
13
NE*
Acceptable
Chromium
mg/kg
32.8
4
Acceptable
Cobalt
mg,kg
53.1
0.9
Acceptable
Copper
LaWkg
180
700
Acceptable
Iron
mg/kgmgikg
78,228
150
Acceptable
Lead
m
82.5
270
Acceptable
Magnesium
mgikg
32,462
NE
Acceptable
Manganese
mg/kg
2,872
65
Acceptable
Mercury
mg/kg
0.1
1
Acceptable
Molybdenum
mg/kg
3.5
7.1
Acceptable
Nickel
mg/kg
18.6
130
Acceptable
Normal UTL=19.55
Nitrate as N)
m
0.56
NE
Acceptable
Potassium
mg/-kgmg/-kg
29,937
NE
Acceptable
Selenium
m
1.77
2.1
Acceptable
Gamma UTL=2.44
Sodium
mg/kg
394
NE
Not Acceptable
Provide rationale on why the maximum concentration was used.
Strontium
mg/kg
7.53
NE
Acceptable
Normal UTL=8.59
Sulfate
mWkg
36
NE*
Acceptable
Thallium
my kg
1.1
0.28
Acceptable
Vanadium
m
210
350
Acceptable
Zinc
mg,-,-kgmg,-,-kg
125
1200
Acceptable
*Constituent has 2L Standard or IMAC. Use calculation in the PSRG table to determine value.
NA - Not applicable (dataset contains zero valid samples)
ND - Non -Detect
NE - Not Established
mg/kg - milligrams per kilogram
S.U. - Standard Unit

NORT44 CAROLINA
Poy COOPER Enwram"mat Quality
Govvm w
MICHAEL S.:REGAN
spa
UNDA GULP€PPER
lrtterfm Wrwtar
August 17, 2018
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
Subject: 2018 Comprehensive Site Assessment Update Comments
Marshall Steam Station
Dear Mr. Draovitch:
On January 31, 2018, the North Carolina Department of Environmental Quality's (DEQ's)
Division of Water Resources (DWR) received the Comprehensive Site Assessment (CSA) Update
for the subject facility. Based on the review conducted to date, the DWR has concluded that
sufficient information has been provided in the report to allow preparation of the Corrective Action
Plan (CAP); however, there are data gaps that must be addressed prior to, or in conjunction with,
preparation of an approvable CAP.
As described in the attached itemized list of CSA Update comments (Attachment 1), additional
data and/or data analysis will be needed to address data gaps, complete evaluation of exposure
pathways, predict time and direction of contaminant transport, and ultimately refine remedial
design. The assessment of all primary and secondary source areas (including, but not limited to,
impoundments, cinder storage areas, coal piles, and contaminated soils) must be included in the
CAP, or in a CAP amendment. The DWR expects that information collected regarding the source
areas will be used to formulate the CAP recommendations. For source areas where this may not
be possible or areas where pollutants may be hydraulically isolated, please contact me to discuss.
In an email dated April 18, 2018, Duke Energy proposed a CAP submittal date of October 31,
2018. However, as you are aware, Duke Energy and the DEQ are currently discussing revisions
.�.rr r�srarr
North Carolina Department of Environmental Quality , Division of Water Resources I AFOGW Section
512 North Salisbury Street 11636 Mail Service Center j Raleigh, North Carolina 27699-1636
919.707.9129

to the CAP deadlines and the final revised date for CAP submittal will be communicated to Duke
Energy in a separate correspondence.
An overview of CSA Update data gaps includes the following:
• The report contents are often presented in a data summary format, exhibiting a lack of
conclusive data analysis and interpretation of site conditions.
• The report fails to fully integrate and evaluate data collected from the CCR monitoring
program as well as previous versions of the CSA reports for the facility.
• The distribution of constituents of interest related to coal ash sources presented in the report
often fail, for at least some areas of the site, to fully and clearly delineate exceedances of the
15A NCAC 2L or 2B standards above background levels.
• The characterization of other primary and secondary sources other than impoundments that
contribute to the groundwater plumes is incomplete.
• As detailed more fully in the attached document, additional data gaps remain concerning
impacts from coal ash at the facility.
The data gaps related to the site assessment at the facility, including those related to primary and
secondary sources other than impoundments, may limit the cleanup remedy and site management
strategies for a source area. The lack of a well -documented interpretation of the existing data, or
missing data that the DEQ believes will be necessary to support proposed corrective action, may
limit DEQ's ability to approve certain corrective action measures [e.g. 15A NCAC 02L .0106(1)].
For example, monitored natural attenuation cannot be approved for source areas where surface
water samples have not been collected (but could be collected) and that demonstrate the
groundwater discharge does not result in exceedances of 15A NCAC 2B .0200 regulatory
standards.
Please refer to the letter to Duke Energy dated June 15, 2018, for approved background threshold
values developed for the facility as part of the CSA Update.
Duke Energy should contact the Mooresville Regional Office to initiate the scheduling of a
meeting between DWR and Duke Energy's technical staff (including contractors) to discuss data
gaps in greater detail. Promoting regular dialogue in a small group format assists in addressing
questions and problems that may come up during the development of the CAP, and better ensures
that Duke Energy is meeting DWR's expectations.

If you have any questions, please feel free to contact me at [phone]. Please contact Brandy
Costner (Mooresville Regional Office) at (704).663-1699 to discuss any additional questions
regarding the CSA Update data gaps in more detail.
Sincerely,
Jo i sgaard, Chief
imal Feeding Operations and Groundwater Protection
Section
Attachment: Marshall Steam Station CSA Update Comments
cc: MRO WQROS Regional Office Supervisor
WQROS Central File Copy

Marshall Steam Station
Condensed Comments for Comprehensive Site Assessment Update Report
Delineation of Groundwater Contamination
Horizontal and vertical delineation of groundwater impacts has not been completed at Marshall Steam
Station, which is a requirement of the Coal Ash Management Act (CAMA) and 15A NCAC 02L .0106.
The CAP shall include updated maps and adequate interpretation/evaluation that addresses the following:
• The report suggests there is inadequate data in the shallow flow layer beneath ash basin. It was
not explicitly called out as a data gap in the report; however, this is a data gap that should be
addressed accordingly to complete characterization of the shallow flow layer beneath the basins
and to support CAP development.
• Hexavalent chromium and total radium should be considered COIs at the site. Rationale for why
those constituents were not considered COIs at Marshall Steam Station should be provided.
• Based on review of the isoconcentration maps (Figures 11-1 thru 11-63), it is apparent that
vertical and horizontal extent of several COIs at several GWA/CCR well pair locations is
warranted (can be discussed in greater detail between MRO and Duke Energy staff prior to
completing the CAP).
• A letter dated June 15, 2018, was submitted to Duke Energy which detailed MRO comments and
general agreement with PBTVs (Appendix H of this report) calculated for the Marshall Steam
Station.
• The report stated, "However, the CCR data has not been fully incorporated into the analysis of
this CSA due to the data only becoming available as of mid -January 2018. For example,
analytical results from CCR Rule -specific monitoring wells are included on isoconcentration
maps and analytical summary tables, but not integrated into detailed mathematical analysis, such
as piper plots, box -and -whisker plots or background statistical calculations. ". While it is
accurate that the CCR data collected as part of the federal CCR Rule was not publicly available
until mid -January 2018, the data was available to Duke Energy and their consultants as it was
collected between 2016 to the present. CCR data could have and should have been utilized to the
fullest extent in this report, but it appears that it was not. During review of this report, it was
unclear when CCR data was utilized and included in evaluations and the extent to which it was
utilized. CCR groundwater data is expected to be fully incorporated into the CAP.
Groundwater Flow Contaminant Flow and Trans .ort
Additional information related to groundwater flow and the mechanisms affecting contaminant migration
is necessary. Comments include, but are not limited to the following:
During review of this report, it was noticed that data collected from select wells that continue to
exhibit high pH or turbidity (likely due to grout contamination) were not presented or included in
the evaluations as they were deemed invalid. This is contrary to what was agreed upon between
MRO, Duke Energy and their consultants in a meeting on June 15, 2017. In order to reach a
compromise regarding well replacements due to grout contaminated wells, MRO, Duke Energy
and their consultants agreed that boron and sulfate were seemingly unaffected by elevated pH
and/or turbidity and instead of installing replacement wells at select locations they would be
water level monitoring and sampling of boron and sulfate. Collection of these select parameters
would allow for monitoring of flow and transport of leading edge constituents which would also

be useful for modelling. If Duke Energy and their consultants do not support use of this data as
part of the assessment, then the wells should be replaced.
• Upward gradients were observed within the footprint of the Phase II landfill. An evaluation of
the upward gradients and COIs (i.e., increasing boron with depth and over time) observed at this
location should be provided and should also include discussion of the relevance in terms of
contaminant movement.
• Concentration trends were provided graphically (Figures 14-39 thru 14-76). While these figures
did give a graphical representation of the data, there was no discussion/evaluation provided on
how hydrogeological and/or geochemical factors affect COI migration and concentrations
observed across the site and what was likely causing the trends observed.
• Evaluations of groundwater data along transects were inconsistent (i.e., not using the same wells
along the transect) throughout the report. Wells should be used consistently throughout the report
to allow for a more appropriate evaluation/review of the data.
• It is stated in the report that the majority of ash in the ash basin is saturated. What is the
estimated total volume of saturated ash vs. unsaturated ash? If decanting/dewatering is
anticipated, what is the estimated volume of ash that will remain saturated? What implications
does this volume of ash that will remain saturated have on contaminant concentrations and
migration if the ash will be capped -in -place as the method of source control? Cap -in -place does
inhibit infiltration, but does not account for lateral groundwater/contaminant flow and this must
be factored in during the CAP. The CAP should explain how the lateral component of
groundwater flow and resulting contaminant flux will be addressed if source material will remain
in place.
• It is stated in the report that, "For basin closure, reduction of infiltrating water will have the
greatest positive impact on groundwater and surface water quality downgradient of the ash
basins. ". This statement needs to be substantiated considering the majority of ash at Marshall
Steam Station is below the water table and will be a continued source to groundwater impacts
under this closure option.
Other Potential PrimaEy and SecondaU Sources
As previously discussed, other primary and secondary sources must be assessed in regard to groundwater
impacts. Sources contributing to groundwater contamination associated with the impoundments
(comingled) must be assessed and results presented as well as incorporated into the CAP. Sources that
have impacted or have the potential to impact groundwater (contaminated soils, stockpiles, etc.) that are
not known or believed to have comingled with areas impacted by the impoundments may be assessed
separately in accordance with a schedule approved by the Department. Additional information needed
includes, but is not limited to the following:
• Based on review of Figure 14-77, delineation of soil impacts has not been completed at Marshall
Steam Station. Soil contamination should be delineated to either the site -specific PBTVs or
Protection of Groundwater (POG) Preliminary Soil Remediation Goals (PSRGs), whichever is
higher. Where appropriate, use the equation provided in the PSRG table to establish a POG
PSRG for a constituent with 02L standard that does have a PSRG established.
• Provide an explanation of how and why soil contamination occurs outside of the waste
boundaries, particularly soils which exhibit elevated concentrations of arsenic, barium,
chromium, iron, manganese, selenium, sulfate, strontium, and vanadium upgradient of the ash
basin.

Groundwater data suggests the Phase I/Phase II Landfills and the PV Structural fill are
contributing to groundwater impacts at the site and should be considered other primary sources,
but was not documented as such in this report. The coal pile is located west of the ash basin and
should be evaluated as another potential primary source, but was not documented as such in the
report. Further assessment is warranted in the areas mentioned above for purposes of delineation
and to understand contributions of groundwater impacts observed at the site.
2L-2B Surface Water Sampling
Collection of surface water samples to evaluate impacts from contaminated groundwater is necessary to
understand the impacts associated with the migration of contaminants from the groundwater system.
Failure to adequately characterize known and potential impacts to surface waters from groundwater will
affect the corrective action strategies that can be proposed and ultimately considered for approval by the
Department. Comments include, but are not limited to the following:
Duke Energy recognizes the need for additional surface water samples and submitted a proposal
to conduct 2L-2B compliance sampling at the facility. To date, only grab surface water samples
have been collected at the facility, which is not in compliance with 02B for calculating acute and
chronic values for select constituents. 2L-2B sampling is necessary to assess the leading edge of
the contaminant plume to allow for a better understanding of groundwater discharge to surface
waters. Also, it has a direct bearing on remedial technologies available for use at the site. If 2L-
2B compliance cannot be adequately demonstrated then MNA may not be considered a viable
option as a remedial technology.
Maw. Figures. and Tables
Revised and/or additional tables, maps and figures are necessary to better represent an understanding by
Duke Energy concerning the horizontal and vertical extent of soil and groundwater impacts, associated
risks to receptors, secondary source impacts, etc. These include, but are not limited to the following:
Vertical gradient maps (Figure 6-11): Evaluation of upward gradients observed at the site in
respect to contaminant movement should be discussed.
Isoconcentration maps (Figures 11-1 thru 11-63):
o ALL data points should be included on figures regardless of validity of data.
Maps/figures are visual representations of data, but when data is left off it can be
misleading and result in forming inappropriate conclusions. Notes should be added
regarding data validity and an explanation of why better -quality data is needed to provide
a more accurate assessment of actual site conditions.
o The maps indicated that data collected between February 2015 and September 2017. It
should be indicated on the map for each data point which sampling event the data is from
so that can be factored into the review/evaluation of data provided on the maps. If the
majority of the data is from the September 2017 sampling event and a small subset is
from other sampling events, simply state that in the legend and then on the map next to
the locations that differ put the date of the sampling event the data was obtained.
o Reporting limits should be utilized instead of ND (non -detect). This provides meaningful
information.
o There were instances where isoconcentration lines were not provided because it was
deemed attributable to background. This is misleading... the map should be
representative of available site data and then any evaluation/interpretation of that data
should be included in the report itself.
0

Modelling
Models are useful tools in understanding groundwater flow, contaminant transport and factors that hinder
or facilitate contaminant migration. Models also aid in the evaluation of corrective action technologies
and choosing the most effective technologies. Comments include, but are not limited to the following:
• Models were run out to 250 years. In previous models submitted, compliance was not achieved
for several constituents within that timeframe. It was stated in this report that simulations would
run until COI concentrations were below the 2L standard at the compliance boundary. I would
like to reiterate the necessity of this so that more informed decisions could be made regarding
what a technically feasible timeframe is, particularly in regard to metals.
• It was indicated in the report that models would only include data up to 4t' quarter 2017. This is
unacceptable and MRO expects 2018 data to be incorporated into the model updates to the extent
possible (dependent upon CAP submittal deadline) and submitted as part of the CAP.
• All COIs should be modeled unless rationale for why they should not be included is provided to
the Department.
• MRO would like to reiterate any direction given by Bill Duetch (NCDEQ Geochemical Advisor)
is expected to be incorporated into the geochemical models.

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Environmental Quality
October 12, 2018
Subject: Completion of Permanent Alternate Water Supply Requirements Under General
Statute 13 0A-3 09.211(c 1)
Marshall Steam Station
Dear Mr. Draovitch:
On August 31, 2018, the North Carolina Department of Environmental Quality (DEQ) received a
request from Duke Energy for Marshall Steam Station for confirmation of completion of the
permanent alternate water provision under the Coal Ash Management Act (CAMA) General
Statute (G.S.) 130A-309.211(cl). Based on our review of the submitted documentation, DEQ
hereby confirms that Duke Energy has satisfactorily completed the alternate water provision under
CAMA, G.S. 130A-309.211(c1) at the Marshall facility.
Please note that, since Duke Energy is currently in the process of preparing the updated Corrective
Action Plan for the Marshall Steam Station and the results of groundwater modeling have not yet
been received, DEQ reserves the right to determine that additional households are eligible and
shall be provided permanent alternate water solutions per G.S. 130A-309.21l(cl) based on any
new information provided. Any future determination of additional eligible households by DEQ
will not affect this confirmation of Duke's compliance with the October 15. 2018 deadline in G.S.
130A-309.211(cl). Further, this confirmation letter does not constitute a final classification for
any impoundment under G.S. 130A-309.213(d).
NORM �a--E
umee�tacmYc'ronrmi
North Carolina Department of Environmental Quality
217 West Jones Street 1 1601 Mail Service Center I Raleigh. North Carolina 27699-1601
919.707.8600

If you have any questions, please feel free to contact Debra Watts at [phone].
Sincerely,
Sheila Holman
Assistant Secretary for Environment
cc: Jessica Bednarcik, Duke Energy, 526 South Church Street, Mail Code EC12J, Charlotte,
NC 28202
WQROS MRO Supervisor
AFOGWS Central Office
0
North Carolina Department of Environmental Quality
217 West Jones Sireet 11601 Mail Service Center I Raleigh, North Carolina 27699-1601
919.707.8600

ROY COOPER
Governor
NCHAEL S. REGAN
Secretary
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Environmental Quality
November 13, 2018
Subject: Final Classification of the Coal Combustion Residuals Surface Impoundment
located at Duke Energy's Marshall Steam Station, Catawba County, NC, Pursuant
to N.C. Gen. Stat. § 130A-309.213(d)(1).
Dear Mr. Draovitch:
Pursuant to the Coal Ash Management Act (HB 630, Session Law 2016-95), the North Carolina
Department of Environmental Quality (NCDEQ) has determined that Duke Energy has met the
low -risk classification criteria set forth in N.C. Gen. Stat. § 130A-309.213(d)(1) for the coal
combustion residuals surface impoundment, called the Active Ash Basin, located at Duke
Energy's Marshall Steam Station in Catawba County, NC. NCDEQ makes the following
specific findings:
1. Duke Energy has established permanent water supplies as required for the above
referenced impoundment pursuant to N.C. Gen. Stat § 130A-309.21l(cl). See Exhibit 1
(Duke Energy Alternate Water Supply Submittal), Exhibit 2 (Alternate Water Supply
Supplemental Documents), and Exhibit 3 (NCDEQ Alternate Water Supply Approval);
and
2. Duke Energy has rectified any deficiencies identified by, and otherwise complied with
the requirements of, any dam safety order issued by the Environmental Management
Commission for the above referenced impoundment pursuant to N.C. Gen. Stat. § 143-
215.32. Specifically, NCDEQ has verified through inspection that Duke Energy has
rectified all deficiencies identified by Dam Safety Order 16-01 (issued on August 22,
2016) at Duke Energy's Marshall Steam Station. See Exhibit 4 (Dam Safety Order 16-
01), Exhibit 5 (Dam Inspection Report), Exhibit 6 (October 3, 2018 DEMLR Letter
Regarding Dam Safety Order 16-01 Compliance Status), and Exhibit 7 (October 10, 2018
EMC Meeting Minutes).
North Carolina Department of Environmental Quality
217 West Jones Street 1 1601 Mail Service Center I Raleigh, North Carolina 27699-1601
919.707.8600

Based upon the determinations above and in accordance with the Coal Ash Management Act,
NCDEQ classifies the coal combustion residuals surface impoundment, called the Active Ash
Basin, at Duke Energy's Marshall Steam Station as low -risk.
If you have any questions about NCDEQ's determinations provided in this letter, please contact
me at [phone].
Sincerely,
Sheila Holman
Assistant Secretary for Environment
cc: Linda Culpepper, NCDEQ, Director, Division of Water Resources (no attachments)
Michael Scott, NCDEQ, Director, Division of Waste Management (no attachments)
Toby Vinson, NCDEQ, Director, Division of Energy Mineral and Land Resources (no
attachments)
Bill Lane, NCDEQ, General Counsel (no attachments)
NCDEQ Central File
:9
North Carolina Department of Environmental Quality
217 West Jones Street 11601 Mail Service Center I Raleigh North Carolina 27699-1601
919.707.8600

OE
��E S� � OF w
DEQ Coal Combustion Residuals
Surface Impoundment
Closure Determination
Marshall Steam Station
April 1, 2019
QE

DEQ Coal Combustion Residuals Surface Impoundment Closure Determination
Marshall Steam Station
Executive Summa
The Coal Ash Management Act (CAMA) establishes criteria for the closure of coal
combustion residuals (CCR) surface impoundments. The CCR surface impoundment located at
Duke Energy Carolinas, LLC's (Duke Energy) Marshall Steam Station (Marshall) in Catawba
County, NC has received a low -risk classification. Therefore, according to N.C. Gen. Stat. §
130A-309.214(a)(3), the closure option for the CCR surface impoundment is at the election of
the North Carolina Department of Environmental Quality (DEQ). CAMA provides three principal
closure pathways: (a) closure in a manner allowed for a high -risk site, such as excavation and
disposal in a lined landfill [CAMA Option A]; (b) closure with a cap -in -place system similar to the
requirements for a municipal solid waste landfill [CAMA Option B]; or (c) closure in accordance
with the federal CCR rule adopted by EPA [CAMA Option C].
In preparing to make its election, DEQ requested information from Duke Energy related
to closure options. By November 15, 2018, Duke Energy provided the following options for
consideration: closure in place, full excavation, and a hybrid option that included some
excavation with an engineered cap on a smaller footprint of the existing CCR surface
impoundment. DEQ held a public information session on January 17, 2019 in Sherrills Ford, NC
where the community near Marshall had the opportunity to learn about options for closing coal
ash CCR surface impoundments and to express their views about proposed criteria to guide DEQ's
coal ash closure decision making process. To evaluate the closure options, the Department
considered environmental data gathered as part of the site investigation, permit requirements,
ambient monitoring, groundwater modeling provided by Duke Energy and other data relevant to
the CAMA requirements.
DEQ elects the provisions of CAMA Option A that require movement of coal ash to an
existing or new CCR, industrial or municipal solid waste landfill located on -site or off -site for
closure of the Active Ash Basin at the Marshall facility in accord with N.C. Gen. Stat. § 130A-
309-214(a)(3). In addition, DEQ is open to considering beneficiation projects where coal ash is
used as an ingredient in an industrial process to make a product as an approvable closure
option under CAMA Option A.
DEQ elects CAMA Option A because removing the coal ash from the unlined CCR surface
impoundment at Marshall is more protective than leaving the material in place. DEQ determines
that CAMA Option A is the most appropriate closure method because removing the primary
source of groundwater contamination will reduce uncertainty and allow for flexibility in the
deployment of future remedial measures.
Duke Energy will be required to submit a final Closure Plan for the CCR surface
impoundment at Marshall by August 1, 2019. The Closure Plan must conform to this election by
DEQ.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 1

Introduction
DEQ has evaluated the closure options submitted by Duke Energy for the CCR surface
impoundment at the Marshall Steam Station. This document describes the CAMA requirements
for closure of CCR surface impoundments, the DEQ evaluation process to make an election under
CAMA for the subject CCR surface impoundment at the Marshall site, and the election by DEQ
for the final closure option.
Site History
Duke Energy owns and operates the Marshall Steam Station which is located at 8320 NC
Highway 150 East in Terrell, Catawba County, North Carolina. Marshall, including the station and
supporting facilities, is approximately 1,446 acres in area. Marshall began operation in 1965 as a
coal-fired generating station and currently operates four coal-fired units with 2,090 megawatts
of total capacity. Coal combustion residuals consisting of bottom and fly ash material from
Marshall have historically been managed in the Marshall ash basin, located north of the station
adjacent to Lake Norman. Dry ash has been disposed of in other areas at Marshall, including the
dry ash landfill units (Phases I and 11) and Industrial Landfill No. 1.
There is one CCR surface impoundment at the site, called the Active Ash Basin. According
to the Duke Energy website and data current as of September 30, 2018, the Active Ash Basin is
approximately 394 acres in size and contains approximately 16,836,000 tons of CCR. The Active
Ash Basin is subject to the requirements of N.C. Gen. Stat. § 130A-309.214(a)(3).
III. CAMA Closure Reauirements
CAMA establishes closure requirements for CCR surface impoundments. The General
Assembly has mandated that DEQ "shall review a proposed Coal Combustion Residuals Surface
Impoundment Closure Plan for consistency with the minimum requirements set forth in
subsection (a) of this section and whether the proposed Closure Plan is protective of public
health, safety, and welfare; the environment; and natural resources and otherwise complies with
the requirements of this Part." N.C. Gen. Stat. § 130A-309.214(b). Similarly, the General
Assembly has required that DEQ "shall disapprove a proposed Coal Combustion Residuals Surface
Impoundment Closure Plan unless the Department finds that the Closure Plan is protective of
public health, safety, and welfare; the environment; and natural resources and other complies
with the requirements of this Part." N.C. Gen. Stat. § 130A-309.214(c).
CAMA requires DEQ to review any proposed Closure Plan for consistency with the
requirements of N.C. Gen. Stat. § 130A-309.214(a). See N.C. Gen. Stat. § 130A-309.214(b). DEQ
must disapprove any proposed Closure Plan that DEQ finds does not meet these requirements.
See N.C. Gen. Stat. § 130A-309.214(c). Therefore, an approvable Closure Plan must, at a
minimum, meet the requirements of N.C. Gen. Stat. § 130A-309.214(a).
Pursuant to N.C. Gen. Stat. § 130A-309.213(d)(1), DEQ has classified the CCR surface
impoundment at Marshall as low -risk. The relevant closure requirements for low -risk
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 2

impoundments are in N.C. Gen. Stat. § 130A-309.214(a)(3), which states the following:
• Low -risk impoundments shall be closed as soon as practicable, but no later
than December 31, 2029;
• A proposed closure plan for a low -risk impoundment must be submitted as
soon as practicable, but no later than December 31, 2019; and
• At a minimum, impoundments located in whole above the seasonal high
groundwater table shall be dewatered and impoundments located in whole or
in part beneath the seasonal high groundwater table shall be dewatered to the
maximum extent practicable.
In addition, N.C. Gen. Stat. § 130A-309.214(a)(3) requires compliance with specific closure
criteria set forth verbatim below in Table 1. The statute provides three principal closure
pathways: (a) [CAMA Option A] closure in a manner allowed for a high -risk site, such as
excavation and disposal in a lined landfill; (b) [CAMA Option B] closure with a cap -in -place system
similar to the requirements for a municipal solid waste landfill; or (c) [CAMA Option C] closure in
accordance with the federal CCR rule adopted by EPA. For each low -risk impoundment, the
choice of the closure pathway in CAMA is at the "election of the Department."
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 3

Table 1: CAMA Closure Options for Low -Risk CCR Surface Impoundments
N.C. Gen. Stat. § 130A-309.214(a)(3)
At the election of the Department, the owner of an impoundment shall either:
a. Close in any manner allowed pursuant to subdivision (1) of this subsection; [CAMA Option A]
b. Comply with the closure and post -closure requirements established by Section .1627 of Subchapter B
of Chapter 13 of Title 15A of the North Carolina Administrative Code, except that such impoundments
shall not be required to install and maintain a leachate collection system. Specifically, the owner of an
impoundment shall Comply with the closure and post -closure requirements established by Section
.1627 of Subchapter B of Chapter 13 of Title 15A of the North Carolina Administrative Code, except
that such impoundments shall not be required to install and maintain a leachate collection system.
Specifically, the owner of an impoundment shall install and maintain a cap system that is designed to
minimize infiltration and erosion in conformance with the requirements of Section .1624 of
Subchapter B of Chapter 13 of Title 15A of the North Carolina Administrative Code, and, at a minimum,
shall be designed and constructed to (i) have a permeability no greater than 1 x 10-5 centimeters per
second; (ii) minimize infiltration by the use of a low -permeability barrier that contains a minimum 18
inches of earthen material; and (iii) minimize erosion of the cap system and protect the low -
permeability barrier from root penetration by use of an erosion layer that contains a minimum of six
inches of earthen material that is capable of sustaining native plant growth. In addition, the owner of
an impoundment shall (i) install and maintain a groundwater monitoring system; (ii) establish financial
assurance that will ensure that sufficient funds are available for closure pursuant to this subdivision,
post -closure maintenance and monitoring, any corrective action that the Department may require,
and satisfy any potential liability for sudden and nonsudden accidental occurrences arising from the
impoundment and subsequent costs incurred by the Department in response to an incident, even if
the owner becomes insolvent or ceases to reside, be incorporated, do business, or maintain assets in
the State; and (iii) conduct post -closure care for a period of 30 years, which period may be increased
by the Department upon a determination that a longer period is necessary to protect public health,
safety, welfare; the environment; and natural resources, or decreased upon a determination that a
shorter period is sufficient to protect public health, safety, welfare; the environment; and natural
resources. The Department may require implementation of any other measure it deems necessary to
protect public health, safety, and welfare; the environment; and natural resources, including
imposition of institutional controls that are sufficient to protect public health, safety, and welfare; the
environment; and natural resources. The Department may not approve closure for an impoundment
pursuant to sub -subdivision b. of subdivision (3) of this subsection unless the Department finds that
the proposed closure plan includes design measures to prevent, upon the plan's full implementation,
post -closure exceedances of groundwater quality standards beyond the compliance boundary that
are attributable to constituents associated with the presence of the impoundment; [CAMA Option B]
or
c. Comply with the closure requirements established by the United States Environmental Protection
Agency as provided in 40 CFR Parts 257 and 261, "Hazardous and Solid Waste Management System;
Disposal of Coal Combustion Residuals From Electric Utilities." [CAMA Option C]
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 4

By referencing the closure options for high -risk CCR surface impoundments in
"subdivision (1)" or N.C. Gen. Stat. § 130A-309.214(a)(1), CAMA allows for closure of a low -risk
CCR surface impoundment in N.C. Gen. Stat. § 130A-309.214(a)(3) through the same removal
scenarios:
• "Convert the coal combustion residuals impoundment to an industrial landfill by
removing all coal combustion residuals and contaminated soil from the impoundment
temporarily, safely storing the residuals on -site, and complying with the requirements
for such landfills." N.C. Gen. Stat. § 130A-309.214(a)(1)a.; or
• "Remove all coal combustion residuals from the impoundment, return the former
impoundment to a nonerosive and stable condition and (i) transfer the coal
combustion residuals for disposal in a coal combustion residuals landfill, industrial
landfill, or municipal solid waste landfill or (ii) use the coal combustion products in a
structural fill or other beneficial use as allowed by law." N.C. Gen. Stat. § 130A-
309.214(a)(1)b.
IV. DEQ Election Process
Beginning with a letter to Duke Energy on October 8, 2018, DEQ began planning for a
thorough evaluation of the closure options for low -risk CCR surface impoundments before
making an election as outlined in Table 1 above. DEQ's objectives were to receive input on
closure options from Duke Energy and to engage with community members near low -risk sites.
DEQ outlined the following schedule in the October 8, 2018 letter:
• November 15, 2018 — Duke Energy submittal of revised option analyses and related
information
• January 17, 2019 — DEQ public meeting near Marshall
• April 1, 2019 — DEQ evaluation of closure options
• August 1, 2019 — Duke Energy submittal of closure plan
• December 1, 2019 — Duke Energy submittal of updated corrective action plan for all
sources at Marshall that are either CCR surface impoundments or hydrologically
connected to CCR impoundments
DEQ received the requested information from Duke Energy by November 15, 2018:
closure options analysis, groundwater modeling and net environmental benefits assessment.
These materials are posted on the DEQ website. Duke Energy provided the following options for
consideration: closure in place, full excavation with either an onsite or offsite landfill, and a hybrid
option that included some excavation with an engineered cap on a smaller footprint of the
existing CCR surface impoundment.
In preparing to make its election of the closure option, DEQ considered environmental
data contained in the comprehensive site assessment, permit requirements, ambient monitoring,
closure options analysis and groundwater modeling provided by Duke Energy and other data
relevant to the CAMA requirements. The Marshall site has extensive amounts of data that have
been collected during the site assessment process, and these data were used as part of the
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 5

evaluation of closure options. DEQ's evaluation of closure in place and hybrid option based on
groundwater monitoring and modeling data is provided in Attachment A. That analysis
demonstrates that the contaminated plume is already beyond the compliance boundary for the
site. All of these references are part of the record supporting DEQ's determination.
DEQ conducted a public meeting in Sherrills Ford, NC near Marshall on January 17, 2019.
There were 409 members of the public who attended the meeting. Approximately 1100
comments were received during the comment period, which closed on February 15, 2019. The
majority of comments received expressed a preference for excavation and removal to dry -lined
storage. The majority of these comments did not specify whether the storage should be on or
off -site, but instead requested that it be "away from our waterways and out of our groundwater."
A minority of comments expressed support for excavation and specified a preference for on -site
disposal in a lined landfill, provided additional feedback on other issues related to the closure
process, or expressed additional concerns related to coal ash. A review and response to
comments are included in Attachment B.
V. DEQ Evaluation of Closure Options
DEQ has evaluated the closure options proposed by Duke Energy for the CCR surface
impoundment at the Marshall facility. The purpose of this evaluation was to determine which
closure option or options may be incorporated into an approvable Closure Plan under CAMA.
DEQ elects the provisions of CAMA Option A that require movement of coal ash to an
existing or new CCR, industrial or municipal solid waste landfill located on -site or off -site for
closure of the Active Ash Basin at Marshall in accord with N.C. Gen. Stat. § 130A-309-214(a)(3).
In addition, DEQ is open to considering beneficiation projects where coal ash is used as an
ingredient in an industrial process to make a product as an approvable closure option under
CAMA Option A.
DEQ elects CAMA Option A because removing the coal ash from the unlined
impoundment at Marshall is more protective than leaving the material in place. DEQ determines
that CAMA Option A is the most appropriate closure method because removing the primary
source of groundwater contamination will reduce uncertainty and allow for flexibility in the
deployment of future remedial measures.
DEQ does not elect CAMA Option B for the CCR surface impoundment at Marshall. In N.C.
Gen. Stat. § 130A-309.214(a)(3)b, the General Assembly mandated that "[t]he Department may
not approve closure for an impoundment pursuant to [this] sub -subdivision ... unless the
Department finds that the proposed closure plan includes design measures to prevent, upon the
plan's full implementation, post -closure exceedances of groundwater quality standards beyond
the compliance boundary that are attributable to constituents associated with the presence of
the impoundment." N.C. Gen. Stat. § 130A-309.214(a)(3)b. In light of these requirements and
based on DEQ's review of the information provided by Duke Energy as well as DEQ's independent
analysis, DEQ does not believe that Duke Energy can incorporate CAMA Option B into an
approvable Closure Plan for Marshall.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 6

As DEQ considered the closure options presented by Duke Energy, DEQ evaluated
whether the closure in place or the hybrid options met the requirement for CAMA Option B.
Specifically, DEQ attempted to determine whether, upon full implementation of the closure plan,
the design would prevent any post -closure exceedances of groundwater standards beyond the
compliance boundary. To address this question, DEQ considered the current state of the
groundwater contamination and reviewed the results of the groundwater modeling submitted
by Duke Energy. The evaluation is provided in Attachment A. DEQ's overall conclusion is that
based on the current geographic scope and vertical extent of the groundwater contamination
plume, and the modeled extent of the plume in the future, DEQ does not believe these two
closure options can meet the requirements of CAMA Option B for the CCR surface impoundment
at Marshall.
DEQ does not elect CAMA Option C (i.e., closure under the federal CCR Rules found in 40
CFR Part 257) for the CCR surface impoundment at Marshall. DEQ has determined that:
a. Under the facts and circumstances here, CAMA Option C is less stringent than CAMA
Option A. Specifically, DEQ's election of Option A would also require Duke Energy to
meet the requirements of the federal CCR Rule (i.e., CAMA Option C) but election of
CAMA Option C would not require implementation of CAMA Option A.
b. Because CAMA Option A adds additional requirements or performance criteria
beyond Option C, it advances DEQ's duty to protect the environment (see N.C. Gen.
Stat. §§ 279B-2 & 143-211) and the General Assembly's mandate under CAMA that
DEQ ensure that any Closure Plan, which must incorporate an approvable closure
option, is protective of public health, safety, and welfare, the environment, and
natural resources (see N.C. Gen. Stat. § 130A-309.214(b) & (c)).
c. For the CCR surface impoundments for which the closure option(s) must be
determined, CAMA Option A provides a better mechanism for ensuring State
regulatory oversight of the closure process than Option C, as well as greater
transparency and accountability.
d. While the federal CCR Rule was written to provide national minimum criteria for CCR
surface impoundments across the country, CAMA was written specifically to address
the CCR surface impoundments in North Carolina.
e. While the federal CCR Rule allows CCR surface impoundment owners to select closure
either by removal and decontamination (clean closure) or with a final cover system
(cap in place), EPA anticipates that most owners will select closure through the less
protective method of cap in place.
f. There is considerable uncertainty regarding the status and proper interpretation of
relevant provisions of the federal CCR Rule. For instance, EPA is reconsidering
portions of the federal CCR Rule. Also, the performance standards in 40 CFR
257.102(d) for cap in place closure are the subject of conflicting interpretations (and
possible litigation) among industry and state authorities.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 7

VI. Final Closure Plan
The final closure plan is due on August 1, 2019 in accordance with this determination.
Based on DEQ's evaluation of the options submitted by Duke Energy, DEQ elects the provisions
of CAMA Option A that require movement of coal ash to an existing or new CCR, industrial or
municipal solid waste landfill located on -site or off -site for closure of the Active Ash Basin in
accord with N.C. Gen. Stat. § 130A-309.214(a)(3). In addition, DEQ is open to considering
beneficiation projects where coal ash is used as an ingredient in an industrial process to make a
product as an approvable closure option under CAMA Option A.
While beneficiation is not a requirement of the closure plan, DEQ encourages Duke
Energy to consider opportunities for beneficiation of coal ash that would convert coal
combustion residuals into a useful and safe product.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 8

ATTACHMENT A
DEQ EVALUATION OF CLOSURE IN PLACE AND HYBRID OPTIONS BASED ON
GROUNDWATER MONITORING AND MODELING DATA
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 9

DEQ EVALUATION OF CLOSURE IN PLACE AND HYBRID OPTIONS BASED ON
GROUNDWATER MONITORING AND MODELING DATA
Groundwater Monitoring Summary
As DEQ considered the closure options presented by Duke Energy, DEQ evaluated
whether the closure in place or the hybrid options met the requirement for CAMA Option B.
Specifically, DEQ attempted to determine whether the design would prevent any post -closure
exceedances of groundwater standards beyond the compliance boundary upon full
implementation of the closure plan. Significantly, the contaminated groundwater plume has
already extended beyond the compliance boundary in a portion of the CCR surface
impoundment. The inferred general extent of groundwater impacts above applicable Background
Threshold Values or 2L Standards are shown on Figure ES-1. Additional monitoring and
hydrogeological data is available in the Marshall Steam Station January 2018 CSA Update Report
(available on the DEQ website).
The groundwater site assessment at the Marshall Steam Station, as required by CAMA,
began in 2015 and is still on -going. Based on review of data submitted to date in various reports,
both soil and groundwater has been impacted by CCR handling activities at the site. Groundwater
within the area of the CCR surface impoundment generally flows from northwest to southeast
and discharges to Lake Norman as depicted on Figure ES-1 (below). The inferred general extent
of groundwater impacts above applicable PBTVs or 2L Standards are shown on Figure ES-1 from
the January 2018 CSA Update Report below. Boron concentrations above 2L Standards
approximates the leading edge of the CCR plume (area shaded yellow) at the site.
The vertical extent of most COls is within the shallow and transition flow layers. However,
data suggests the bedrock flow layer has been impacted by CCR handling activities at the site.
Manganese and strontium concentrations are fairly widespread in the bedrock flow layer. There
are isolated occurrences of boron, chloride, iron, molybdenum and TDS within and downgradient
of the ash basin.
DEQ concludes that the contaminated groundwater plume above 2L groundwater
standards has extended beyond the compliance boundary along the northern and eastern edge
on the shore of Lake Norman.
II. Groundwater Cross-section Modeling
As DEQ considered the closure options presented by Duke Energy, DEQ evaluated
whether the closure in place or the hybrid options met the requirement for CAMA Option B.
Specifically, DEQ attempted to determine whether the design would prevent any post -closure
exceedances of groundwater standards beyond the compliance boundary upon full
implementation of the closure plan. To address this question, DEQ considered the current state
of the groundwater contamination and reviewed the results of the groundwater modeling
submitted by Duke Energy.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 10

DEQ evaluated cross -sections of the groundwater modeling results provided by Duke
Energy to determine whether Duke Energy's final closure Option 1: Hybrid and Option 5: Closure -
in -Place would meet the criteria of CAMA Option B. DEQ considered if the agency could conclude
that the proposed closure option includes design measures to prevent any post closure
exceedances of the 2L groundwater quality standards at the compliance boundary upon the
plan's full implementation. Cross section A -A' was evaluated and can be seen in the figures below.
This cross section represents where the boron concentration above the 2L standard of 700 µg/L
has crossed the compliance boundary based on groundwater monitoring and modeling.
Next, the model results were evaluated based on the following model simulations:
• current conditions in 2017 when the model was calibrated based on raw field data
• upon completion of the final closure -in -place cover system at t=0 years
• closure -in -place option at t=120 years
• upon completion of the hybrid option at t=0 years
• hybrid option at t=120 years
The table below summarizes the results from the model simulations. The boron
concentrations depicted in the table represent the maximum boron concentration in any layer
(ash, saprolite, transition zone, and bedrock) of the model.
Marshall Modeling Results for Cross -Section A -A'
Model Simulation
Maximum Concentration of
Depth of GW Contamination
Width of
Boron Above 2L Beyond
Above 2L Beyond
Contamination Plume
Compliance Boundary
Compliance Boundary (feet
Beyond Compliance
(ug/L)
bgs)
Boundary
(feet)
Current Conditions
700-4,000
380
1500
Completion of Final
700-4,000
390
1500
Cover (t=0 yrs)
Final Cover
700-4,000
370
1500
(t=120 yrs)
Completion of Hybrid
700-4,000
310
1500
(t=0 yrs)
Hybrid (t=120 yrs)
700-4,000
360
1600
bgs — below ground surface
These data illustrate that after completion of closure with the final cover or hybrid option,
the groundwater plume still extends beyond the compliance boundary above the 2L groundwater
standard and the area of the plume requiring remediation is immense. Even 120 years beyond
completion of closure, the area of the plume requiring remediation remains extensive.
DEQ recognizes that there are no groundwater remediation corrective actions included in
the groundwater modeling simulations submitted to DEQ as part of Duke Energy's closure
options analysis documentation. However, based on the current geographic scope, vertical
extent of the groundwater contamination plume, and future modeled extent of the plume, DEQ
does not believe these two closure options can meet the requirements of CAMA Option B.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 11

Figure EG£ Marshall Steam Station 6 nua w 2018 C A Update Report
--mm— �t7, --�
UAR SH ± CLOSURE DETERQNAION-AP RILt 2019-2

Figure ES-1 Legend: Marshall Steam Station January 2018 CSA Update Report
LEGS In
AREA OF CONCENTRATION IN GROUNDWATER
ABOVE NC2L (BEE NOTE 5)
ASH BASIN WASTE BOUNDARY
APPROXIMATE LANDFILL WASTE BOUNDARY
APPROXIMATE STRUCTURAL FILL BOUNDARY
GENERALIZED GROUNDWATER FLOW DIRECTION
WATER SUPPLY WELL LOCATION
STREAM WITH FLOW DIRECTION
---- DUKE ENERGY PROPERTY BOUNDARY
NOTE.
1. OCTOBER, 2016 AERIAL PHOTOGRAPHY OBTAINED FROM GOOGLE EARTH PRO ON
SEPTEMBER 18, 2017_ AERIAL ❑ATED OCTOBER 28, 201S.
2. STREAMS OBTAINED FROM AM EC FOSTER WHEELER NRTR, MAY 2016.
3. GENERALIZED GROUNDWATER FLOW DIRECTION BASED ON SEPTEMBER 11, 2017
WATER LEVEL DATA.
d. PROPERTY BOUNDARY PROVIDED BY DUKE ENERGY.
S. GENERALIZED AREAL EXTENT OF MIGRATION REPRESENTED BY NCAC 02L
EXCEEDANCES OF MULTIPLE CONSTITUENTS IN MULTIPLE FLOW ZONES.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 13

MARSHALL CURRENT CONDITIONS IN 2018
MAX BORON ANY LAYER (ug/L) green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
)SURE DETERMINATION - APRIL 1, 2019 - 14

MARSHALL UPON COMPLETION OF FINAL COVER IN 2030, t = 0
MAX BORON ANY LAYER (ug/L) green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
RSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 15

MARSHALL FINAL COVER, 2150, t = 120 years
MAX BORON ANY LAYER (ug/L) green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 16

MARSHALL UPON COMPLETION OF HYBRID IN 2030, t =
MAX BORON ANY LAYER (ug/L) green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
SHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 17

MARSHALL UPON COMPLETION OF HYBRID IN 2150, t = 120 years
MAX BORON ANY LAYER (ug/L) green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 18

MARSHALL CURRENT CONDITIONS IN 2018
CROSS SECTION A -A' (VIEWED FROM SW SIDE OF DAM LOOKING NE)
MAX BORON ANY LAYER green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
dam
compliance w
Marshall model
Ash 1-4
Saprolite 5-7
TZ 8
Bedrock 9-20
Vertical
exaggeration X 3
rs:
w
-6-
A -A:
Lake
�t ■■ '� � SMffff}}��y1rL.. �C■ t��
Norman
16
~
100 ft
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 19
w

MARSHALL UPON COMPLETION OF FINAL COVER IN 2030, t = V
CROSS SECTION A -A' (VIEWED FROM SW SIDE OF DAM LOOKING NE)
MAX BORON ANY LAYER green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
Marshall model
Ash 1-4
Saprolite 5-7
TZ 8
Bedrock 9-20
Vertical
exaggeration X 3
rs:
A dam
• -compliance A
} }_� boundarl
A -A' —1200 ft
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 20

MARSHALL UPON COMPLETION OF FINAL COVER IN 2150, t = 120
CROSS SECTION A -A' (VIEWED FROM SW SIDE OF DAM LOOKING NE)
MAX BORON ANY LAYER green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
A dam
compliance A
boundary
Marshall model lavers:
Ash 1-4
Saprolite 5-7
TZ 8
Bedrock 9-20
Vertical
exaggeration X 3
A -A' —1200 ft
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 21

MARSHALL UPON COMPLETION OF HYBRID IN 2030, t = 0
CROSS SECTION A -A' (VIEWED FROM SW SIDE OF DAM LOOKING NE)
MAX BORON ANY LAYER green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
dam
compliance
A I boundary
1
1
Marshall model lavers: �
Ash 1-4
Saprolite 5-7
TZ 8
Bedrock 9-20
Vertical
exaggeration X 3
1
All
4 Lake
Norman
J F
y" •
Excavated "0 4
basin lake
at same
head as "
Lake �' a
Norman
00 t+
r
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 22

MARSHALL HYBRID IN 2150, t = 120 years
CROSS SECTION A -A' (VIEWED FROM SW SIDE OF DAM LOOKING NE)
MAX BORON ANY LAYER green = 75-700, tan = 700-4000, red = 4000-10,000, blue = 10,000-40,000
Marshall model
Ash 1-4
Saprolite 5-7
TZ 8
Bedrock 9-20
Vertical
exaggeration X 3
dam
10
A I compliance
boundary
rs:+ 11 t
Excavatec
basin IakE
at same
head as
Lake
Norman
Y ti,
Lake
Norman
/ 1
+ .. ■
y
� r 0, /
A -A' —1200 ft
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 23

ATTACHMENT B
RESPONSE TO COMMENTS
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 24

RESPONSE TO COMMENTS
I. Summary of Responses to Comments
The North Carolina Department of Environmental Quality (DEQ) received approximately
1,100 public comments regarding the closure options for coal combustion residuals (CCR) surface
impoundments at Duke Energy's Marshall Steam Station. The overwhelming majority of
comments received expressed a preference for excavation and removal to dry -lined storage. The
majority of these comments did not specify whether the storage should be on or off -site, but
instead requested that it be "away from our waterways and out of our groundwater." A minority
of comments expressed support for excavation and specified a preference for on -site disposal in
a lined landfill, provided additional feedback on other issues related to the closure process, or
expressed additional concerns related to coal ash.
II. Detailed Responses to Comments
A. Comments Opposing Cap in Place
Comment: Many comments opposed allowing Duke Energy to cap the existing ash in its
current location and supported excavation.
Response: DEQ agrees with these concerns and has determined that the CCR surface
impoundments at Marshall must be excavated.
Comment: One comment opposed "cap in place" and requested that DEQ perform an
independent analysis that "identifies the safest closure option for the long-term protection of
water supplies."
Response: DEQ agrees with these concerns and has determined that the CCR surface
impoundments at Marshall must be excavated.
Comment: One comment opposed "cap in place" and stated that professionals
recommend storage in lined landfills. This comment also raised concerns about a lack of research
regarding future impacts from beneficial reuse in building materials and expressed an opinion
that Duke Energy should not be able to pass cleanup costs on to consumers.
Response: DEQ understands these concerns and has determined that the CCR surface
impoundments at Marshall must be excavated. DEQ will continue to take this and future
comments into consideration when evaluating closure plans submitted by Duke, as required by
the Coal Ash Management Act. Analysis and evaluation of beneficial reuse may be included in the
closure plan. The issue of cost is not within the purview of DEQ. Instead, this issue rests with the
North Carolina Utilities Commission.
Comment: A commenter submitted an extensive written comment urging DEQ to require
the Marshall coal ash basins to be excavated to a lined landfill to protect the environment and
human health.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 25

The commenter claimed coal ash impoundments at Marshall are not eligible for closure -
in -place under CAMA. The commenter alleged that closure -in -place violates the North Carolina
groundwater rule. The commenter sets out several arguments it believes support that claim: 1)
Duke Energy's modelling demonstrates it will not meet groundwater standards if it chooses
closure -in -place; 2) Duke Energy's modelling underestimates the extent of contamination; 3)
Duke Energy tested groundwater compliance at the wrong location; 4) the groundwater rule
prohibits closure -in -place because the coal ash will contribute to violations of the groundwater
standard for centuries; and 5) closure -in -place is unavailable because it will not restore
groundwater to the legal standard.
The commenter next claimed that coal ash impoundments at Marshall are not eligible for
closure -in -place under the Coal Combustion Residuals (CCR) rule. The commenter alleged that:
1) the CCR rules' performance standards require separating ash from the groundwater and
precluding its future impoundment; and 2) the CCR rules' corrective action requirements
preclude closure -in -place.
The commenter continues by asserting that DEQ must base its closure determination on
effectiveness and not cost to the polluter. The commenter further maintains that DEQ should
reject Duke Energy's "Community Impact Analysis." The commenter claims that Duke's Energy's
report downplays well -established pollution risks and exaggerates the impact on communities of
excavating and trucking material to offsite landfills. Further, they claim that diesel emissions do
not meaningfully distinguish between closure methods and that the report's habitat analysis is
flawed. The commenter concludes by questioning the validity of Duke Energy's closure options
scoring system - and offers its own analysis to demonstrate why it believes Duke Energy
manipulated scores to suit a desired outcome.
Response: DEQ understands these concerns and has determined that the CCR surface
impoundments at Marshall must be excavated.
B. Comments Supporting Excavation
Comment: Many comments supported excavation but did not express a preference for
final disposition of the excavated materials.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station.
Comment: One comment supported excavation and implementation of a requirement to
publicly disclose the presence of contaminants and associated risks to current residents as well
as potential new residents/buyers.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. The Department is not aware of legal
authority that would enable it to require Duke Energy to provide the type of notice requested in
this comment.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 26

Comment: Several comments supported excavation and secure disposal of the excavated
materials but did not express a preference for what secure disposal would entail.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station.
Comment: One comment expressed support for excavation and legislative action to
prevent Duke Energy from escaping liability for future problems associated with the site.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. As an executive branch agency, DEQ does
not have the ability to implement legislative action.
Comment: One comment expressed support for excavation as a long term solution, while
expressing the opinion that the other options would only serve as short term solutions.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station.
Comment: Multiple comments expressed support for excavation, but expressed concern
over the timeframe for completion or compliance.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. However, the North Carolina General
Assembly has set forth the timeframe for completion of this process through the Coal Ash
Management Act.
Comment: One comment expressed support for excavation, but expressed concern over
pre-existing structural fills that utilized ash.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ will continue to take this and future
comments into consideration when evaluating closure plans submitted by Duke, as required by
the Coal Ash Management Act. Analysis and evaluation of preexisting structural fill sites will occur
separate and apart from the current proceedings.
Comment: One comment expressed support for excavation and removal to an
unpopulated area outside of North Carolina.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. The Department does not have the legal
authority to require Duke Energy to dispose of coal ash in an "unpopulated area outside of North
Carolina."
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 27

Comment: Two comments expressed support for excavation and testing of removed
material.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ will continue to take this and future
comments into consideration when evaluating closure plans submitted by Duke, as required by
the Coal Ash Management Act.
Comment: One comment expressed support for total excavation, including the
construction of a road through the property, but requested that total deforestation be avoided.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ will continue to take this and future
comments into consideration when evaluating closure plans submitted by Duke, as required by
the Coal Ash Management Act.
C. Comments Supporting Excavation and Transport to Dry Lined Storage
Comment: The overwhelming majority of comments requested excavation to dry lined
storage away from waterways and groundwater using the following form letter, or a derivation
that was substantially similar.
"Dear Coal Ash Comment Administrator North Carolina DEQ: Marshall,
The North Carolina Department of Environmental Quality (DEQ) should require Duke
Energy to remove its coal ash from its leaking, unlined pits and move it to dry lined storage away
from our waterways and out of our groundwater.
Duke Energy plans to leave its coal ash sitting in the groundwater at six sites in North
Carolina, where it will keep polluting our groundwater, lakes, and rivers. Recent monitoring shows
Duke Energy is polluting the groundwater at its coal ash ponds in North Carolina with toxic and
radioactive materials. We need cleanup —not coverup!
The communities around the coal ash ponds have come out time after time over the last
several years, making clear that we're concerned about pollution from Duke Energy's coal ash
and want Duke Energy to get its coal ash out of its unlined, leaking pits. It is long past time for
DEQ and Duke Energy to listen to the communities.
Duke Energy is already required to remove its coal ash at eight other sites in North Carolina
and all of its sites in South Carolina —our families and our community deserve the some
protections."
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ will continue to take this and future
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 28

comments into consideration when evaluating closure plans submitted by Duke, as required by
the Coal Ash Management Act.
Comment: Many (non -form letter) comments also requested excavation to dry lined
storage or landfills away from waterways.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ will continue to take this and future
comments into consideration when evaluating closure plans submitted by Duke, as required by
the Coal Ash Management Act.
Comment: Many comments requested excavation to off -site dry lined storage. One
specific comment went into significant detail about the commenters concerns regarding the
usage of existing on -site storage options.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ has not yet made a decision regarding
location for final disposition. DEQ will continue to take this and future comments into
consideration when evaluating closure plans submitted by Duke, as required by the Coal Ash
Management Act.
D. Comments Supporting Excavation and Removal to On -Site Dry Lined Storage
Comment: One comment expressed support for excavation and transport to dry lined
storage on Duke Energy property but requested that the distance the ash is moved be minimized.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ has not yet made a decision regarding
location for final disposition. DEQ will continue to take this and future comments into
consideration when evaluating closure plans submitted by Duke, as required by the Coal Ash
Management Act.
Comment: Numerous commenters submitted the following form letter requesting
excavation and on -site dry lined storage, or a derivation that was substantially similar.
Marshall Steam Station Comments
N.C. Department of Environmental Quality
RE: Public Comment on the Marshall Coal Ash Cleanup
• DEQ should require Duke Energy to remove its coal ash from its leaking, unlined pit and
move it to dry, lined storage on its own property — away from Lake Norman and out of
our groundwater.
• Duke Energy plans to leave its coal ash sitting in the groundwater at Marshall, where it
will keep polluting our groundwater, streams and rivers. Recent monitoring shows Duke
Energy is polluting the groundwater surrounding Marshall with toxic and radioactive
materials. We need cleanup —not coverup!
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 29

• The community has come out time after time over the last several years, making clear
that we're concerned about pollution from Duke Energy's coal ash and want Duke Energy
to get its coal ash out of its unlined, leaking pits. It is long past time for DEQ and Duke
Energy to remove the ash.
• Duke Energy is already required to remove its coal ash from eight other communities in
North Carolina and all of its sites in South Carolina, and the governor of Virginia recently
called for all the coal ash to be removed from Dominion's unlined sites —our families and
our community deserve the same protections.
• Duke Energy can dispose all the ash from its leaking pond onsite in safe, dry, lined
storage. Ash will not travel through the community or to other communities.
• Duke cannot exaggerate traffic concerns while downplaying the community's real
concern: Duke Energy's water pollution. None of these plans will have a significant
increase in offsite trucking, but only excavation will remove the source of the water
pollution.
• Duke Energy's own experts know that even cap -in -place will involve trucking
construction materials to the site —just like any other construction project. But even
under their estimates, the additional trucking impacts are minimal. Excavation would
cause only a 4% increase in daily truck traffic on community roads compared to a 7%
increase for the duration of the cap -in -place scenario.
• It is past time for DEQ to listen to the community —not Duke Energy's consultants —
about what our community needs. We need Duke to clean up its coal ash and stop the
water pollution.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ has not yet made a decision regarding
location for final disposition. DEQ will continue to take this and other comments into
consideration when evaluating closure plans submitted by Duke, as required by the Coal Ash
Management Act.
E. Comments in Support of Beneficial Reuse
Comment: Several comments supported excavation of ash to a lined landfill or being
recycled into concrete or other building materials.
Response: DEQ has determined that coal ash must be excavated and removed from CCR
surface impoundments at the Marshall Steam Station. DEQ agrees that it is proper for Duke
Energy to consider possible methods to beneficiate coal ash into a product.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 30

Comment: One comment requested the ash be recycled into concrete but did not express
any opinions on other closure plans.
Response: DEQ agrees that it is proper for Duke Energy to consider possible methods to
beneficiate coal ash into a product.
F. Other Comments
Comment: Numerous comments cited concerns or personal experiences with thyroid
cancer and other risks, stating that it was DEQ's responsibility to protect the public. Most
comments citing these concerns expressed a preference for excavation.
Response: DEQ understands and appreciates the need for a remedy that addresses
adverse impacts to water quality, human health, and the environment. DEQ will require Duke
Energy to comply with all applicable laws and regulations during the closure process. At this time,
DEQ has determined that coal ash must be excavated and removed from CCR surface
impoundments at the Marshall Steam Station.
Comment: Several comments expressed concerns with Duke Energy passing on removal
costs to consumers or requested that Duke Energy pay all costs of the cleanup.
Response: This issue is not within the purview of DEQ. Instead, this issue rests with the
North Carolina Utilities Commission.
Comment: Several comments expressed concerns with or complaints regarding the public
meeting process (preparedness, information presented, brevity of presentation, lack of answers
to questions) or requested that DEQ provide additional information to the public.
Response: DEQ will take this feedback into account for future public meetings.
Comment: One comment requested additional information regarding effective filtration
systems.
Response: DEQ does not typically identify or require specific filtration systems or
products.
Comment: Several comments did not express a preference for a specific closure option
but requested that DEQ clean up, or make sure that Duke Energy cleans up, the Marshall Steam
Station site.
Response: DEQ will require Duke Energy to comply with all applicable laws and
regulations during the closure process.
Comment: Several comments requested cleanup of a potential ash site near Lake Norman
High School.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 31

Response: DEQ has been made aware of this concern and will investigate.
Comment: Several comments expressed concern with Duke Energy clearcutting forest
during the cleanup process.
Response: DEQ understands this concern and will continue to protect the natural
resources of the State of North Carolina. DEQ will require Duke Energy to comply with all
applicable laws and regulations during the closure process. DEQ will continue to take this and
future comments into consideration when evaluating closure plans submitted by Duke, as
required by the Coal Ash Management Act.
Comment: Several comments expressed concerns with ancillary impacts of closure,
including air quality and traffic.
Response: DEQ will require Duke Energy to comply with all applicable laws and
regulations during the closure process. DEQ will continue to take this and future comments into
consideration when evaluating closure plans submitted by Duke, as required by the Coal Ash
Management Act.
Comment: One comment provided an in-depth analysis regarding options pertaining to
different types of capping in place and expressed an opinion that, if a site were capped in place,
an evaluation of all technologies available for dewatering should be considered.
Response: DEQ appreciates the information presented and will continue to take this and
future comments into consideration when evaluating closure plans submitted by Duke, as
required by the Coal Ash Management Act.
Comment: Several comments raised concerns regarding worker safety in and around ash
basins.
Response: DEQ appreciates this concern and will take these comments into consideration
when it reviews Duke Energy's closure plans.
Comment: One comment requested that DEQ ignore a Duke Energy report on estimated
greenhouse gas emissions associated with various closure options for the six unresolved coals
ash sites. The comment claimed DEQ should disregard this submission because it was made after
DEQ's deadline for Duke Energy to submit its materials and outside the public comment period,
thereby denying the public an opportunity to respond to it. The comment also claimed that DEQ
should disregard this submission because it is irrelevant to the decision facing DEQ, which is to
select a closure method that stops the ongoing pollution and continuing threat to our water
resources posed by Duke Energy's leaking coal ash basins.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 32

Response: At this time, DEQ has determined that coal ash must be excavated and
removed from CCR surface impoundments at the Marshall Steam Station. DEQ will require Duke
Energy to comply with all applicable laws and regulations during the closure process.
MARSHALL CLOSURE DETERMINATION - APRIL 1, 2019 - 33

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Director
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Environmental Quality
April 4, 2019
Subject: Response to the Optimized Interim Monitoring Plans (IMP) for 14 Duke Energy
Facilities - Modification Request Annual Reports - Modification Request
Dear Mr. Draovitch:
On March 20, 2019, the North Carolina Department of Environmental Quality Division of Water
Resources (Division) received the proposed Optimized IMP for 14 Duke Energy Facilities -
Modification Request Annual Reports - Modification Request (Modification Request). This letter
requested changes to direction provided to Duke Energy by the Division in the December 21, 2018
correspondence concerning the Optimized IMP along with proposed changes to the scope and/or
reporting schedule for Interim Action Effectiveness Reports for the Asheville, Belews Creek, and
Sutton facilities.
Modification of Interim MonitoringPlan
lans
The Division has reviewed and hereby approves Modification Request for implementation of the
Optimized IMPS apart from the following which require justification subject to approval. The
following changes were noted from the previous optimized IMPs approved by the Division on
December 21, 2018.
• Asheville
O Wells EXT-D and MW-8BR were moved from quarterly sampling to water
level only. Please provide justification for this change.
• Belews Creek
O Wells AB-1BRD, AB-2BR, AB-2BRD, and AB-3BRD were removed from
quarterly sampling. Please provide justification for this change.
North Carolina Department of Environmental Quality I Division of Water Resources
QE J 512 North Salisbury Street 1 1636 Mail Service Center I Raleigh, North Carolina 27699-1636
919.707.9000

• Roxboro
o Wells ABMW-7BRLL, MW-01BRL, MW-108BRL, MW-205BRL, and
MW-208BRL were removed from quarterly sampling. Please provide
justification for this change.
IMP Annual Monitoring Reports
The Division has reviewed and hereby approves the Modification Request concerning the due
dates for the IMP Annual Monitoring Reports. The due dates for these reports shall be as follows:
• April 30, 2019 —Allen, Belews Creek, Cliffside, Marshall, Mayo, and Roxboro.
• July 31, 2019 — Asheville, Buck, Cape Fear, Dan River, H. F. Lee, Riverbend, Sutton,
and Weatherspoon.
Interim Action Effectiveness Reports
The Division has reviewed and hereby approves Modification Request concerning Interim Action
Effectiveness Reports. The due dates for these reports shall be as follows:
May 15, 2019 — Sutton
July 31, 2019 — Asheville and Belews Creek
Revisions to the tables in the Modification Request are expected based on the detailed review items
documented in this letter unless compelling rationale is provided to substantiate these changes to
the December 21, 2018 Optimized IMP direction. The Division may require changes to the content,
format and schedule of the IMP Annual Monitoring Reports and Interim Action Effectiveness
Reports after review of the pending submittals.
If you have any questions, please contact Steve Lanter (Central Office) at [phone].
Sincerel , l
Jon Risga a d, Chief
Animal Feeding Operations and Groundwater Section
cc: WQROS Regional Offices
WQROS Central File Copy

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
Paul Draovitch
Senior Vice President
Environmental, Health, & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Environmental Quality
April 5, 2019
Subject: Final Comprehensive Site Assessment and Corrective Action Plan Approvals for
Duke Energy Coal Ash Facilities
Dear Mr. Draovitch:
The purpose of this letter is to establish submittal dates for Comprehensive Site Assessments (CSAs)
and Corrective Action Plans (CAPS) for all 14 Duke Energy Coal Ash Facilities (Facilities). The
schedule provided includes:
• Restatement of schedules for the six Facilities that were established in the North Carolina
Department of Environmental Quality (DEQ) October 8, 2018 letter.
• Clarification that the March 31, 2020 submittal date for evaluation of sources at the Facilities
that are not associated with the coal ash impoundments is for CSA Reports.
• Establishment of CSA and CAP submittal dates for the remaining eight Facilities considering
the November 5, 2018 Duke Energy proposed schedule and additional information regarding
justification for proposed submittal dates.
• List of primary sources to be included in each facility CSA or CAP.
The following is the approved schedule for the submittal of CSAs and CAPs for each facility.
Allen Steam Station
• Due December 1, 2019 — Updated CAP for impoundments and other primary and secondary
sources hydrologically connected to impoundments including the coal pile, retired ash basin
landfill, two structural fills, and two dry ash storage areas.
• Due March 31, 2020 — CSA for primary and secondary sources not associated with
impoundments including the gypsum pad.
-eo:: f Q. E� N
���
North Carolina Department of Environmental Quality
217 West Jones Street 1 1601 Mail Service Center I Raleigh. North Carolina 27699-1601
919.707.8600

Asheville Steam Electric Plant
• Due June 1, 2020 —Updated CSA for impoundments and other primary and secondary sources
including the raw coal pile.
• Due March 1, 2021 — Updated CAP for impoundments and other primary and secondary
sources.
Belews Creek Steam Station
• Due December 1, 2019 —Updated CAP for impoundments and other primary and secondary
sources hydrologically connected to impoundments including the Pine Hall Road Landfill.
• Due March 31, 2020 — CSA for primary and secondary sources not associated with
impoundments including the structural fill and coal pile.
Buck Combined Cycle Station
• Due October 1, 2020 — Updated CSA for impoundments and other primary and secondary
sources including the coal pile.
• Due July 1, 2021— Updated CAP for impoundments and other primary and secondary sources.
Cape Fear Steam Electric Plant
• Due September 1, 2020 — Updated CSA for impoundments and other primary and secondary
sources including the former coal pile storage areas.
• Due June 1, 2021— Updated CAP for impoundments and other primary and secondary sources.
James E. Rogers EnerRv Com lex
• Due December 1, 2019 — Updated CAP for impoundments and other primary and secondary
sources hydrologically connected to impoundments including the ash storage areas and newly
identified source east of Unit 6 and west of Suck Creek.
o Duke Energy has indicated that investigation of the newly identified source east of Unit
6 and west of Suck Creek may require additional well installation that would require
that the CAP due December 2019 not include this source area. In the event that this is
the case, Duke shall notify DWR, and provide a summary of up-to-date findings so an
appropriate schedule for this area can be established.
• Due March 31, 2020 — CSA for primary and secondary sources not associated with
impoundments including the raw coal piles north of Unit 6, switchyard ash disposal area, and
gypsum pile.
Dan River Combined Cycle Station
• Due July 1, 2020 — Updated CAP for impoundments and other primary and secondary sources
including the former coal yard.
H. F. Lee Energy Com lex
• Due October 1, 2020 — Updated CSA for impoundments and other primary and secondary
sources including the coal staging area/coal pile and lay of land area.
• Due July 1, 2021 — Updated CAP for impoundments and other primary and secondary sources.
Marshall Steam Station
• Due December 1, 2019 — Updated CAP for impoundments and other primary and secondary
sources hydrologically connected to impoundments including the coal pile and gypsum pile.
ceo:f RE Q�
North Carolina Department of Environmental Quality
217 West Jones Street 1 1601 Mall Service Center I Raleigh, North Carolina 27699-1601
919.707.8600

Mavo Steam Electric Plant
• Due December 1, 2019 — Updated CAP for impoundments and other primary and secondary
sources hydrologically connected to impoundments which may include the active coal storage
pile areas.
• Due March 31, 2020 — CSA for primary and secondary sources not associated with
impoundments including the gypsum pad and low volume wastewater pond.
Riverbend Steam Station
• Due May 1, 2020 —Updated CAP for impoundments and other primary and secondary sources
including the former coal yard.
Roxboro Steam Electric Plant
• Due December 1, 2019 — Updated CAP for impoundments and other primary and secondary
sources hydrologically connected to impoundments including the West Ash Basin Extension
Impoundment and associated discharge canal and the East Ash Basin Extension Impoundment
and associated discharge canal.
• Due March 31, 2020 — CSA for primary and secondary sources not associated with
impoundments including the coal storage pile.
L. V. Sutton Ener;;y Complex
• Due May 1, 2020 — Updated CAP for impoundments and other primary and secondary sources
including the former ash disposal area, former process area, and former coal stockpile area.
W. H. Weatherspoon Power Plant
• Due June 1, 2020 — Updated CSA for impoundments and other primary and secondary sources
including the coal storage area and cooling pond.
• Due March 1, 2021 — Updated CAP for impoundments and other primary and secondary
sources.
Any required assessment of source areas not permitted by the Division of Water Resources and not
hydrologically associated with the CCR impoundments (such as a solid waste landfill) will be at the
discretion of the permitting division/section of DEQ. If you have any questions, please contact me at
[phone].
Sincerely,
Sheila Holman
Assistant Secretary for Environment
Cc: Bill Lane
Ed Mussler, DWM
Jon Risgaard, DWR
George Eller, DEMLR
WQROS Regional Office Supervisors
DEQ Central File Copy
PO V_.;
North Carolina Department of Environmental Quality
217 West Jones Street 1 1601 Mail Service Center I Raleigh, North Carolina 27699-1601
919.7078600

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Environmental Quality
May 9, 2019
Subject: Coal Ash Impoundment Closures at Allen, Belews Creek, Cliffside/Rogers,
Marshall, Mayo and Roxboro Facilities
Dear Mr. Draovitch:
In light of the time constraints imposed by Duke Energy's filing of Petitions for Contested Case
Hearings on April 26, 2019 contesting the Department of Environmental Quality (DEQ) Closure
Determinations for the Allen, Belews Creek, Cliffside/Rogers, Marshal, Mayo, and Roxboro
facilities (the "Facilities"), DEQ hereby revises the schedule for yet -unfinished activities in its
letter of October 8, 2018 as follows:
• Duke Energy submittal of closure plans — December 31, 2019
• Duke Energy submittal of updated corrective action plans for all sources at the Facilities
that are either impoundments or hydrologically connected to impoundments — March 31,
2020
• Duke Energy submittal of comprehensive site assessments for sources at the Facilities
that are not associated with the coal ash impoundments — March 31, 2020
Pursuant to the Coal Ash Management Act (CAMA), specifically N.C. Gen. Stat. § 130A-
309.214, Duke Energy shall submit one closure plan for each CCR impoundment at the
Facilities. Each closure plan shall conform to the determination made by DEQ on April 1, 2019.
Outside of the two specific schedule changes noted above, this letter does not effect any other
change in any previous DEQ correspondence, including the October 8, 2018 letter.
DECK
North Carolina Department of Environmental Quality
217 West Jones Street 1 1601 Mail Service Center I Raleigh, North Carolina 27699-1601
919.707.8600

If you have any questions regarding this letter, please contact me at [phone].
Sincerely,
�Ei" ���
Sheila Holman
Assistant Secretary for Environment
aEQ�
North Carolina Department of Environmental Quality
217 West Jones Street 11601 Mad Service Center I Raleigh, North Carolina 27699-1601
919.707.8600

ROY COOPER
Governor
HCHAEL S. REGAN
Secretory
LINDA CULPEPPER
Director
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Envkmmental Qual ty
September 10, 2019
Subject: Duke Energy Interpretation of Corrective Action Plan Content Guidance (January 23,
2019) — North Carolina Department Environmental Quality Response and Conditional
Approval
Dear Mr. Draovitch:
On January 23, 2019, the North Carolina Department of Environmental Quality's (DEQ) Division of Water
Resources (DWR) received the Duke Energy Interpretation of Corrective Action Plan (CAP) Content
Guidance Provided by the DEQ. That document describes Duke Energy's proposed approach for preparing
the groundwater CAPS within the structure of the DWR's guidance titled "CAP Content for Duke Energy
Coal Ash Facilities" dated April 27, 2018. DWR has reviewed the proposed approach regarding CAP
development and conditionally approves its implementation with the following considerations and
conditions: In addition, DWR has provided the attached comments on Duke Energy's Supporting Rationale
for the Proposed Interpretations and Adjustments to the CAP Content Guidance that was produced with
respect to the April 27, 2018 letter (Attachment 2).
• Section 1.C.b. — Keep text that references the Notice of Regulatory Requirements (NORR).
Information related to the NORR needed to address DEQ Comprehensive Site Assessment (CSA)
Update comments shall be provided in the body of the CAPS in a comprehensive manner to
adequately evaluate site conditions and to refine remedial design to facilitate decision making
regarding corrective action.
• Section 1.D. — The proposed additional text is acceptable; however, the criteria that will be used
for evaluation and selection of remedial alternatives in the CAPS should be provided in Section 6.
• Section 1.E.b. — Duke Energy's clarification is acceptable, however, please acknowledge and
identify any other primary and secondary sources, non -coincident with the ash basins, that are on -
site and are currently or were formerly under the jurisdiction of DEQ.
• Sections 4.B. and 4.C. — A discussion of background concentrations in other similar settings is
acceptable; however, site -specific data will be the primary consideration for determination of
background threshold values (BTVs) for both soil and groundwater.
MENorth
� Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1636 Mail Service Center I Raleigh, North Carolina 27699-1636
mra� /'�� 919.707.9000

• Section 4.D. — Application of United States Environmental Protection Agency Nationally
Recommended Water Quality Criteria for Aquatic Life & Human Health by the DEQ is authorized
in the context of using narrative regulations for toxic controls where no surface water quality
standard has been adopted into state regulations. This is consistent with state authority under the
Clean Water Act, as well as state administrative code with respect to corrective action. DEQ will
work with Duke Energy to determine the appropriate response to exceedances of the 15A NCAC
02B surface water quality standards where applicable.
• Section 5 — Please include a 3-dimensional figure that illustrates groundwater impacts.
• Summary of Potential Receptors/Section 6 — The process of identifying potential receptors should
acknowledge that the hydraulics and groundwater/surface water flow patterns near the ash basins
have potentially changed over the years due to mounding and other site conditions; therefore, the
area that may have been impacted by may be more extensive than the area affected by current site
operations.
• Section 6 — Constituents of interest (COIs) that are subject to corrective action shall be constituents
with concentrations greater than the 15A NCAC .02L Groundwater Standards, Interim Maximum
Allowable Concentrations, or BTVs at or beyond the point of compliance, as well as, any
constituents within the compliance boundary that are predicted to cause a violation of any standard
in adjoining classified groundwaters, as directed by 15A NCAC .02L .0107(k). This concept shall
be reflected in any revised text.
• Section 6.A. — While the overall concept for data reduction to focus CAP development is
acceptable, sufficient data must be included to justify any proposed corrective action and an
agreement must be reached between Duke Energy and the DWR Regional Offices concerning
which COIs to address for corrective action. Also, providing data or responses to CSA Update
comments only in an appendix is not acceptable.
• Section 6.A.a.vi.3. — Consideration of constituents that will be mapped in the CAPS shall be based
on a review of site factors that affect flow and transport, including geochemical conditions, as well
as, public concern. The specific constituents that will be mapped in the CAPs shall be determined
by consensus between Duke Energy and the DEQ Regional Offices. If constituents display a
limited or discontinuous distribution that does not lend well to conventional mapping, then a
discussion of related site conditions should be provided in a manner that could understood by the
general public.
• Section 6.A.b. — The June 2019 cut-off date for inclusion of data into a CAP is acceptable for sites
where document submittals are scheduled for December 2019. However, CAPs due at later dates
should have different data cut-off dates based on Duke Energy's internal review process.
• Section 6.A.b.ii. —All 15A NCAC .02L Groundwater Standard exceedances should be
acknowledged and discussed. An agreement must be reached between Duke Energy and the
respective DWR Regional Offices concerning which COIs to address for corrective action.
• Section 6.A.c.i-ii — Removal of this section is acceptable. Under Section 6.D.a.i.ii, also list the
maximum concentrations of the COIs within and beyond the point of compliance for each media
(soil, groundwater, sediment, etc.).

• Section 6.B.a. — The process ofidentifying identifying potential receptors should acknowledge that the
hydraulics and groundwater/surface water flow patterns near the ash basins have potentially
changed over the years due to mounding and other site conditions, and therefore the area that may
have been impacted by past site operations may be more expanded than current site operations.
• Section 6.D.a.ii. — List the maximum concentrations of the COIs within and beyond the point of
compliance for each media (soil, groundwater, sediment, etc.).
• Section 6.D.a.iii. — Keep this Section and provide a succinct summary of modeling results,
including modeled concentrations above the 2L standards at or beyond the point of compliance for
the modeled time frame.
• Section 6.E.b and 6.E.b. iv. — Provide enough information and detail for the various remedial
alternatives considered to facilitate review. A higher level of cost detail shall be provided for the
remedial alternative selected in order to provide adequate information for decision making.
Otherwise, additional documentation may be required before an alternative is approved.
• Section 10 —Where applicable, isoconcentration maps shall provide mapping of analytical results
to background or non -detect levels to depict concentration gradients related to COI distribution. In
addition, all data points must be illustrated on maps. This level of detail is needed to evaluate
remedial design and address CSA Update document comments.
• Section 11. — Final content concerning appendices should be based on an agreement between Duke
Energy and the DEQ Regional Offices and should include all supporting documentation for
remedial alternative design.
Please include this correspondence as part of the CAP Update documents. If you have any questions, please
feel free to contact Steve Lanter (Central Office) at [phone].
Sincerely,
Ji �reggson, Deputy Director
Division of Water Resources
Attachments: (1) Duke Energy Interpretation of Corrective Action Plan Content Guidance Provided by
the North Carolina Department of Environmental Quality — January 23, 2019
(2) Supporting Rationale for Proposed Interpretation and Adjustments to the Corrective
Action Plan Content Guidance (NCDEQ April 2018) by Duke Energy January 2019
cc: WQROS Regional Office Supervisors
WQROS Central File Copy

ROY COOPER.
Governor
MICHAEL S. REGAN
Secretary
LINDA CULPEPPER
Director
Paul Draovitch
Senior Vice President
Environmental, Health & Safety
Duke Energy
526 South Church Street
Mail Code EC3XP
Charlotte, North Carolina 28202
NORTH CAROLINA
Environmental Quality
October 24, 2019
Subject: Approach to Managing Constituents of Interests for Purposes of Corrective Action
Plans
Dear Mr. Draovitch:
On September 4, 2019 Duke Energy presented a Constituent of Interest (COI) Management Plan (Plan) to
facilitate Corrective Action Plan (CAP) development required at its coal combustion residuals (CCR)
facilities. In lieu of a document to review, the North Carolina Department of Environmental Quality (DEQ)
has reviewed the content of the presentation to develop a position regarding the subject matter. The COI
Plan as presented to date is conditionally acceptable with notable revisions described in Attachment 1.
These revisions will assist Department review and ensure a consistent approach across the CCR facilities.
DEQ staff welcome the opportunity to discuss related COI Plan issues with Duke Energy, including
attending other facility -specific presentations. If you have questions or concerns regarding the
Department's position relative to the COI Plan provided in this correspondence, please contact Steve Lanter
in the DWR Central Office at [phone] and he will coordinate with the respective Regional Offices
to initiate discussion.
Sincerely,
Jtl�son, Deputy Director
Division of Water Resources
Attachments
Attachment 1 - Approach to Managing Constituents of Interests for Purposes of Corrective Action Plans
cc: WQROS Regional Offices (electronic copy)
GWRS Central File Copy
North Carolina Department of Environmental Quality 1 Division of Water Resources
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D_E � 512 North Salisbury Street 1 1636 Mail Service Center I Raleigh, North Carolina 27699-1636
�0-ft 919.707.9000

October 22, 2019 Attachment 1- Approach to Managing COls for Purposes of CAPS
Attachment 1
Approach to Managing Constituents of Interests for Purposes of Corrective Action Plans
On September 4, 2019, Duke Energy presented a Constituent of Interest (COI) Management Plan (Plan)
for Corrective Action Plan (CAP) development required at its coal combustion residuals (CCR) sites.
The presented Plan is conditionally acceptable with notable revisions described below. These revisions
Will assist Department review and ensure a consistent approach across coal ash facilities.
Framework as Presented by Duke on 9/04/19. As described in the 9/04/19 Duke presentation, COls
that occur above the criterion (defined as the greater of 15A NCAC 02L standards [02L], interim
maximum allowable concentrations [IMACs], or background threshold values [BTUs]) at/beyond the
compliance boundary (CB) will be identified for corrective action. Depending on their
observed/modeled occurrence and distribution and a "groundwater (GW) exceedance ratio", Duke
Energy proposes to map some COIs; other CON will, as proposed, be unmapped and only listed in a
table. The typical mobility of each COI will be described along with conditions that affect its mobility.
Attenuation mechanisms will be described for each COI along with the expected long-term stability of
those mechanisms.
Framework Response by DWR with Revisions. This COI Management Framework is a process
developed to facilitate corrective action planning. The Framework helps identify the areas and COls in
need of corrective action and the potential remedies that could be effective. Corrective actions are
being implemented in conjunction with and to support and augment basin closures. When CBs are
modified or expire, and compliance has not been achieved in an area no longer covered by a CB,
corrective actions will be required in those areas. Corrective actions may or may not need to be
"active" depending on factors evaluated in the Framework such as, for example, mobility of the CON in
question, stability of attenuation mechanism(s), remediation goals for the COls, etc. Rather than
computing a maximum mean and a GW exceedance ratio, use of a lower confidence limit (LCL)95 (95%
lower confidence limit)' is a more appropriate metric to identify and document areas in need of
corrective action. For each monitoring well, Duke Energy shall compute an LCL95 for the COI in
1 See, for example, United States Environmental Protection Agency (EPA) Unified Guidance (March 2009) and ProUCL
Technical guidance (2013), including discussion of parametric and non -parametric 95% LCLs. Note that if the well
sample dataset is shown to be trending for a given COI, an LCL95 may be computed on the trendline.
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October 22, 2019 Attachment 1- Approach to Managing COls for Purposes of CAPs
question by using data from all sample events at the wel12. If the computed LCL95 exceeds the
applicable criterion then that well -COI would be identified in the CAP as a localized area in need of
corrective action. If the localized area for the identified COI is isolated and does not represent a larger
scale plume, it may be mapped accordingly in the CAP by simply showing a large scale plan view map
with the well that contains the exceeding LCL95, along with the LCL95 value, representative pH and Eh
values, Kd, ratio of species concentrations for the C01 in question (if applicable and assuming
speciations have been measured/computed), and a dashed line containing the area in need of
corrective action. As described in the 9/4/19 presentation, a table(s) will also be provided containing
the list of CON, and their corresponding typical speciation (anion, cation, neutral), mobility under
acidic/alkaline conditions, mobility under reducing/oxidizing conditions, localized conditions that affect
mobility, propensity for sorption, ion exchange, and (or) precipitation, and expected long term stability
of the attenuation mechanisms. Influence of hyporheic zone on geochemical conditions and COI
mobility, if applicable, should also be considered/discussed, as should the influence of potential
surface water mixing on geochemical conditions and mobility during storm -induced rises in surface
water levels that can, in some cases, reverse groundwater gradients. The extent of boron above
background is to be shown on all maps as an approximate extent of hydraulic influence from the basin.
If the modeled boron plume has not yet stabilized (is continuing to move in time) then the extent of
boron above background at future year 2120 should also be shown on the maps to indicate the
predicted future extent of basin influence.
Transects referred to in the CAP shall be shown (a) in a plan view map along with the observed head
contours and corresponding flow lines, (b) in a plan view map along with modeled head contours, and
(c) in cross section with modeled head contours and velocity vectors.
Dissolved Groundwater Concentrations. Unfiltered (total) concentrations of constituents are
measured for most groundwater samples. However, for geochemical modeling purposes, dissolved
concentrations must be used in the input file of the computer code. For each CCR basin, a conceptual
2 Rather than using only data from 2018 to 2019 as presented by Duke, data from all sample events should be used. If
a technical reason exists to omit a portion of the historic dataset, an appendix may be provided that includes the well,
all values in the historic record for the COI in question, the values that should be omitted, and rationale for the
omission (e.g. early break-in issues, COI concentration -time trends, pH or turbidity issues, etc.). Future monitor wells
would also undergo LCL95 computation to identify additional areas in need of corrective action.
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October 22, 2019 Attachment 1- Approach to Managing Cols for Purposes of CAPS
geochemical model will be developed to represent current conditions and estimate how COI
concentrations may change in the future in response to changes in environmental conditions, such as
redox change due to decanting/dewatering. The results of ion speciation and mineral equilibrium
calculations from groundwater data along flowpaths from the source areas to downgradient locations
will be used to develop the geochemical conceptual site models. Dissolved concentration data for all
parameters (major/minor ions and COls) must be collected from the monitoring wells along the
flowpaths to develop these models. This will also be done for areas where anomalous geochemical
conditions occur such as the low pH area at Allen. In most cases, dissolved sampling conducted under
the Interim Monitoring Plans will be sufficient for modeling purposes.
Valence State Measurements. Several of the potential CON are redox-sensitive and occur in more
than one valence state [e.g., As (III,V), Se (-II, 0, IV, VI), Fe {II,III), Mn (II, III, IV)]. Because of the
perceived difficulty of preserving samples in the field for redox species measurement in the laboratory,
redox speciation is being calculated from the measured pH and Eh using a geochemical modeling code.
This method assumes redox equilibrium and may not always be appropriate. In situations where
anomalous groundwater concentrations of a redox-sensitive COI are present, it would be beneficial to
conduct sampling and laboratory analyses for the redox species of the COI to determine if speciation is
a factor leading to the anomalous behavior. This would require appropriate preservation of water
samples in the field for lab measurements of the specific redox species.
Additional sampling and analysis of redox species in selected wells would help to demonstrate that the
modeled speciations that have been calculated under an assumption of equilibrium conditions are
appropriately determined. The number and location of wells used for this purpose should be
appropriate to demonstrate confidence in the modeling approach, input data, and results.
COI Identification. The Plan process discussed in the meeting included a comparison of groundwater
concentrations to relevant regulatory criteria in order to select Cols based on exceedances of their
respective criteria. Consideration should also be given for those constituents that do not currently
exceed their criteria but may feasibly exceed that criteria in the future if environmental conditions
change. For example, if the arsenic criterion is 10 µg/L and the measured groundwater concentration
is 5 µg/L, then arsenic would be included in predictive geochemical modeling to determine if corrective
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October 22, 2019 Attachment 1- Approach to Managing COls for Purposes of CAPs
actions produce conditions that elevate the arsenic concentration above its criterion. For practical
purposes, constituents that are currently measured in a groundwater well beneath or downgradient of
a basin at an LCL95 concentration at or above 50% of the criterion (i.e. LCL95 >= COI criterion x 0.5)
would be included in the modeling of future conditions to estimate whether or not those future
conditions increase the groundwater level to a concentration greater than the criterion.
Conclusions and Discussion in CAPS. Findings and conclusions presented in the CAPS should pertain
to a specifically identified local area beneath and (or) downgradient of a basin. Each area identified for
corrective action, whether it be a plume, an isolated, localized area, or an anomalous area, should be
discussed individually and specifically. For consistency in the CAP, discussions and tables related to COI
management generally should refer to the LCL95 (rather than the mean or geomean) and the COI
criterion (rather than 2L, IMAC, or background). Where the CAP discusses performance or
effectiveness monitoring that will be conducted as part of corrective action implementation, an upper
confidence limit 95% (UCL95) would be the appropriate evaluation metric rather than the LCL95 (i.e.
corrective action continues until the UCL95 is below the cleanup criterion').
s See EPA (2018) Groundwater Statistics Tool — User's Guide.
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