REVISED_Duke_BelewsCreek_GypsumPad_Assessment_WorkPlan_20190627

161P
synTerra
GYPSUM PAD ASSESSMENT WORK PLAN
FOR
BELEWS CREEK STEAM STATION
3195 PINE HALL ROAD
BELEWS CREEK, NC 27009
SUBMITTED: MAY 2019
REVISED: JUNE 2019
PREPARED FOR
DUKE ENERGY CAROLINAS, LLC
r� DUKE
ENERGY..
CAROLINAS
PREPARED BY
%VNTFRRA CnRPAR,&TTAN
David Avard
Project Scientist

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC - Belews Creek Steam Station SynTerra
TABLE OF CONTENTS
SECTION
PAGE
1.0 INTRODUCTION.........................................................................................................1-1
1.1 Regulatory Background...........................................................................................1-1
1.2 Site Description.........................................................................................................1-2
2.0 STRUCTURAL FILL ASSESSMENT OBJECTIVES..............................................2-1
2.1 Soil Assessment......................................................................................................... 2-1
2.2 Groundwater Assessment....................................................................................... 2-2
3.0 REPORTING..................................................................................................................3-3
LIST OF FIGURES
Figure 1 Proposed Gypsum Pad Assessment Sample Locations
LIST OF TABLES
Table 1 Proposed Gypsum Pad Assessment Soil Samples and Monitoring Wells
Table 2 Soil Analytical Parameters
Table 3 Groundwater Analytical Parameters
List of Attachments
Attachment A Gypsum Pad Assessment Work Plan Comments — Belews Creek Steam
Station (June 24, 2019)
Page i

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
1.0 INTRODUCTION
This revised work plan provides a description of groundwater and soil assessment
activities proposed for the Gypsum Pad area at the Belews Creek Steam Station (BCSS,
Station, or Site), with consideration of comments received by North Carolina
Department of Environmental Quality (NCDEQ) on June 24, 2019 (Attachment A).
BCSS is owned and operated by Duke Energy Carolinas, LLC (Duke Energy). The Site,
located in Stokes County, North Carolina, encompasses approximately 6,100 acres of
company -owned property along Belews Reservoir. The Gypsum Pad is located between
two branches of Belews Reservoir (Figure 1), north of the FGD Landfill and south of the
power plant.
1.1 Regulatory Background
In 2014, The North Carolina General Assembly passed the Coal Ash Management Act
(CAMA). CAMA required owners of a coal combustion residuals (CCR) surface
impoundment to conduct detailed assessment of site groundwater within and around
the CCR surface impoundments. The primary source of CCR-related constituents at
BCSS was identified as the ash basin during the Comprehensive Site Assessment (CSA)
(HDR, 2015) and the CSA Update (SynTerra, 2017).
The Gypsum Pad is not coincident with the ash basin hydrologic flow system. The
Gypsum Pad is located approximately 3,000 feet southeast of the ash basin, separated
from the ash basin hydrologic flow system by topographic divides (SynTerra, 2017) and
Belews Reservoir. Based on previous groundwater assessments of the nearby Flue Gas
Desulfurization (FGD) Landfill (HDR, 2017), groundwater flow direction in the area of
the FGD Landfill and Gypsum Pad is predicted to be predominantly away from the
FGD landfill and toward the Gypsum Pad to the north, and Belews Reservoir to the
northwest.
Duke Energy submitted two FGD Landfill Groundwater Assessment reports (HDR,
2012 and 2014) that reported findings of sulfate and total dissolved solids (TDS)
concentrations greater than the groundwater regulatory standards in the area between
the FGD Landfill and the Gypsum Pad. Conclusions from the two reports suggest
effects on groundwater in the area of the FGD Landfill and Gypsum Pad might be a
result of infiltration from precipitation runoff from the FGD landfill and non -contact
storm water basins west of the landfill, or related to the adjacent Gypsum Pad. An
Additional Assessment of Groundwater Exceedances — Phase I Report (HDR, 2017)
stated that concentrations of sulfate and selenium greater than groundwater regulatory
Page 1-1
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Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
standards near the Gypsum Pad and FGD Landfill were not consistent with the FGD
Landfill as the source. In 2015, efforts to reduce fugitive dust from the Gypsum Pad
began. Those efforts have helped result in decreased effects on groundwater in the area.
In October 2018, groundwater monitoring wells (CCR-FGD-11S/D and CCR-FGD-
12S/D) were installed as dual-purpose monitoring wells for the FGD Landfill CCR
compliance network and the Gypsum Pad groundwater assessment network (Figure 1).
With the exception of groundwater monitoring wells CCR-FGD-11S/D and CCR-FGD-
12S/D, no pre-existing monitoring wells are located in areas predicted to be
downgradient, in the direction of groundwater flow from the Gypsum Pad. No data is
available from the newly installed dual purpose wells at this time. Because there are
limited groundwater sampling results available for use in assessing the area, and
previous groundwater assessments in the area have indicated the Gypsum Pad as a
potential source of inorganic constituents to groundwater, assessment of inorganic
constituents in soils and groundwater in the Gypsum Pad area is planned.
Duke Energy understands the Gypsum Pad area groundwater and soils could be
primary and secondary sources of inorganic constituents that are to be further assessed
apart from CAMA or the CCR Rule.
1.2 Site Description
Detailed descriptions of the Site operational history, physical setting and features,
geology/hydrogeology, and results of the findings of Site assessment -related works are
documented in the following documents:
• Comprehensive Site Assessment Report — Belews Creek Steam Station Ash Basin (HDR
Engineering, Inc. of the Carolinas (HDR, 2015a).
• Corrective Action Plan Part 1— Belews Creek Steam Station Ash Basin (HDR, 2015b).
• Corrective Action Plan Part 2 (included CSA Supplement 1 as Appendix A) — Belews
Creek Steam Station Ash Basin (HDR, 2016a).
• Comprehensive Site Assessment Supplement 2 — Belews Creek Steam Station Ash Basin
(HDR, 2016b).
• Comprehensive Site Assessment Update — Belews Creek Steam Station Ash Basin
(SynTerra, 2017).
• 2018 CAMA Annual Interim Monitoring Report —Belews Creek Steam Station
(SynTerra, April 2018).
Page 1-2
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Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
The Gypsum Pad was constructed in 2006 and 2007 for the storage of gypsum only from
FGD residue from BCSS operations. An underlying synthetic geomembrane liner was
installed during construction of the storage pad (Figure 1). The gypsum is conveyed to
the storage area via transfer belts. A mechanical radial stacker places the gypsum in
stacked piles on the semicircular storage pad. The unit's capacity is approximately
10,000 tons of gypsum. The footprint of the Gypsum Pad area, including the radial
stacker and storage pad, is approximately 5 acres, with the storage pad comprising
roughly half of the footprint. The Gypsum Pad has been identified as a potential source
of inorganic constituents in groundwater by NCDEQ.
Page 1-3
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Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
2.0 GYPSUM PAD ASSESSMENT OBJECTIVES
Objectives of the Gypsum Pad assessment include the following:
• Characterize unsaturated soil inorganic constituents for assessment of potential
secondary sources to groundwater.
• Determine groundwater flow direction.
• Compare inorganic constituent concentrations in the Gypsum Pad area with site
background concentrations evaluated during the CAMA ash basin assessment
and with other applicable regulatory criteria.
• Evaluate potential constituent transport.
2.1 Soil Assessment
Gypsum Pad area soils would be sampled and analyzed for inorganic parameters to
determine whether they are a secondary source of inorganic constituents that can leach
into underlying groundwater. Soil samples would be collected at prescribed depths, as
described on Table 1, from proposed monitoring well locations (Figure 1) as part of
well installation activities. Soil samples would be collected at approximately 2-foot
intervals to the top of the groundwater table. An additional soil sample would be
collected below the water table within the new well screen interval. Soil samples would
be analyzed for inorganic parameters listed on Table 2, with adjusted reporting limits
appropriate for comparison of soil analytical results with the Primary Soil Remediation
Goals Protection of Groundwater (PSRG POG).
Soil samples would also be analyzed using a synthetic precipitation leaching procedure
(SPLP) to understand potential leaching effects from the solid media. Soil SPLP samples
would be collected at a frequency of two per well cluster location with one unsaturated
sample collected from 2 to 3 feet below ground surface, and one saturated sample
collected 2 to 3 feet below the water table. Soil SPLP samples would be analyzed for
inorganic parameters listed on Table 2.
Soil or rock samples would be collected from depths that coincide with the screen
intervals of newly installed wells for potential analysis of metal oxy-hydroxide phases
of iron and aluminum (HFO and HAO). After the first round of groundwater sampling,
wells that are geochemically significant at the Site would be selected for analysis as
necessary.
Page 2-1
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Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
2.2 Groundwater Assessment
Eight Gypsum Pad assessment groundwater monitoring wells (designated as "GP ")
would be installed in shallow, deep, and bedrock groundwater zones in designated
areas of the Gypsum Pad. For vertical delineation, two bedrock wells (GP-11BR and GP-
1213R) are recommended for installation adjacent to existing dual-purpose well pairs
(CCR-FGD-11S/D and CCR-FGD-12S/D). Installation of a well cluster (GP-10S/D/BR) is
recommended to the northwest of the Gypsum Pad and installation of a second well
cluster (GP-13S/D/BR) is recommended to the southeast. Proposed well installation
locations are shown on Figure 1, and proposed well details are provided as Table 1.
Specific well locations may be shifted depending on access and field conditions at the
time of installation.
Well installation procedures and well construction materials and lengths would be
consistent with ongoing CAMA assessment activities in accordance with the approved
Proposed Groundwater Assessment Work Plan (Rev. 1) (SynTerra, 2014). During boring
installation, soil/rock cuttings would be described for lithologic information, including
color and soil/rock type. Each well would be constructed in accordance with NCAC
Title 15A, Subchapter 2C, Section .0100 Well Construction Standards and consist of 2-
inch diameter NSF schedule 40 PVC flush -joint threaded casings and prepacked
screens.
After installation, the monitoring wells would be developed in order to remove drill
fluids, clay, silt, sand, and other fines, which might have been introduced into the
formation or sand pack during drilling and well installation, and to establish
communication of the well with the aquifer. After well completion, the newly installed
wells would be surveyed for location and elevation.
Groundwater samples would be collected using low -flow sampling techniques per the
groundwater sampling procedures provided in the Low Flow Sampling Plan, Duke Energy
Facilities, Ash Basin Groundwater Assessment Program, North Carolina, June 10, 2015 (Low
Flow Sampling Plan). Groundwater samples would be analyzed for constituent
parameters in Table 3.
Water levels would be collected within a 24-hour time frame. Data would be used for
depicting water elevation contours and determining groundwater flow directions. Slug
testing would be performed for each groundwater monitoring well installed, and on
existing wells CCR-FGD-11S/D and CCR-FGD-12S/D, to evaluate hydraulic
conductivity of each flow zone. Horizontal and vertical gradients and groundwater
velocity would be calculated.
Page 2-2
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Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

Gypsum Pad Assessment Work Plan Submitted May 2019; Revised June 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
3.0 REPORTING
The Gypsum Pad assessment findings would be presented in a CSA report that would
be submitted to the NCDEQ Division of Water Resources (DWR) on March 31, 2020, as
requested in an April 5, 2019, letter to Duke Energy. The report will include the
following components:
1) Site History and Source Characterization
2) Site Geology and Hydrogeology
3) Sampling Results
4) Site Conceptual Model
5) Conclusions and Recommendations
Page 3-3
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Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

Gypsum Pad Assessment Work Plan June 26, 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
Figures
P:\Duke Energy Carolinas\20. BELEWS CREEK\29.Structural Fill, Coal Pile and Gypsum Pad
Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

O
BELEWS
RESERVOIR
LAYDOWN AREA
(NO DISTURBANCE ANTICIPATED)
;ET SCALE: 1'=100"
!
! I !! TRANSFER BE'u
LT &
INSET SCALE: 1'=100" J RADIAL STACKER SYSTEM
r�
rt
0
" i
INSET SCA
DUKE
ENERGY.
GRAPHIC SCALE
175 0 175 350
CAROLINAS
(IN FEET)
DRAWN BY: B. YOUNG DATE: 06/05/2019
REVISED BY: B. YOUNG DATE: 06/27/2019
CHECKED BY: A. ALBERT DATE: 06/27/2019
APPROVED BY: A. ALBERT DATE: 06/27/2019
synTerra
PROJECT MANAGER: A. ALBERT
www.s7nterracorp.com
Rl
FIGURE 1
PROPOSED GYPSUM PAD
ASSESSMENT SAMPLE LOCATIONS
BELEWS CREEK STEAM STATION
BELEWS CREEK, NORTH CAROLINA

Gypsum Pad Assessment Work Plan June 26, 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
Tables
P:\Duke Energy Carolinas\20. BELEWS CREEK\29.Structural Fill, Coal Pile and Gypsum Pad
Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

TABLE 1
PROPOSED GYPSUM STORAGE AREA ASSESSMENT SOIL SAMPLES AND MONITORING WELLS
BELEWS CREEK STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELEWS CREEK NC
Monitoring
Well ID
Estimated
Well Depth
(feet bgs)1
Soil Sample ID
(Estimated Depth
Interval in feet bgs)Z
Preferred Drilling Method3
Comments'
GP-10SB (2-4)
Near -surface unsaturated soil sample, water table —10 feet bgs
--
--
GP-10SB (5-7)
--
Unsaturated soil sample, water table —10 feet bgs
--
GP-10SB (8-10)
Unsaturated to partially saturated soil sample, water table —10 feet bgs
GP-10S
30
GP-10SB (20-30)
Hollow -Stem Auger
Soil sample from shallow well screened interval and HAO/HFO sample
GP-10D
60
GP-10SB (50-60)
Hollow -Stem Auger/Air Rotary or Sonic
Soil/partially weathered rock sample from deep well screened interval and HAO/HFO sample
GP-10BR
100
GP-10SB (90-100)
Hollow -Stem Auger/Air Rotary or Sonic
Rock sample from bedrock well screened interval and HAO/HFO sample
--
GP-11SB (2-4)
Near -surface unsaturated soil sample, water table —10 feet bgs
--
--
GP-11SB (5-7)
--
Unsaturated soil sample, water table —10 feet bgs
GP-11SB (8-10)
Unsaturated to partially saturated soil sample, water table —10 feet bgs
GP-11S13 (28-38)
Soil sample from existing shallow well CCR-FGD-11S screened interval and HAO/HFO sample
--
GP-11S13 (46-56)
Soil/partially weathered rock sample from existing deep well CCR-FGD-11D screened interval and HAO/HFO sample
GP-11BR
100
GP-11S13 (90-100)
Hollow -Stem Auger/Air Rotary or Sonic
Rock sample from bedrock well screened interval and HAO/HFO sample
--
--
GP-12SB (2-4)
--
Near -surface unsaturated soil sample, water table —10 feet bgs
--
--
GP-12SB (5-7)
--
Unsaturated soil sample, water table —10 feet bgs
--
--
GP-12SB (8-10)
--
Unsaturated to partially saturated soil sample, water table —10 feet bgs
--
--
GP-12SB (15-25)
--
Soil sample from shallow well existing CCR-FGD-12S screened interval and HAO/HFO sample
--
--
GP-12SB (34-44)
--
Soil/partially weathered rock sample from deep well existing CCR-FGD-12D screened interval and HAO/HFO sample
GP-12BR
80
GP-12SB (70-80)
Hollow -Stem Auger/Air Rotary or Sonic
Rock sample from bedrock well screened interval and HAO/HFO sample
--
--
GP-13SB (2-4)
--
Near -surface unsaturated soil sample, water table —10 feet bgs
--
--
GP-13SB (5-7)
--
Unsaturated soil sample, water table —10 feet bgs
--
--
GP-13SB (8-10)
--
Unsaturated to partially saturated soil sample, water table —10 feet bgs
GP-13S
20
GP-13SB (20-30)
Hollow -Stem Auger
Soil sample from shallow well screened interval and HAO/HFO sample
GP-13D
40
GP-13SB (50-60)
Hollow -Stem Auger/Air Rotary or Sonic
Soil/partially weathered rock sample from deep well screened interval and HAO/HFO sample
GP-13BR
80
GP-13SB (70-80)
Hollow -Stem Auger/Air Rotary or Sonic
lRock sample from bedrock well screened interval and HAO/HFO sample
Prepared by: ALA Checked by: CDE
Notes:
bgs - below ground surface
- Approximately
HAO - Hydrous aluminum Oxide
HFO - Hydrous ferric oxides
'Proposed boring depths and screened intervals are estimates based on well construction information from nearest spatitally existing wells; actual screened intervals and total boring depths will be determined based on field observations and approved
by a NC Licensed Geologist. SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet
Number of soil samples shown is approximate. A shallower water table will result in fewer samples, and a deeper water table will result in additional samples.
3SynTerra recommends a combination of hollow stem auger and air rotary or sonic drilling methods for boring and well installation
'Soil sample for inorganic analysis and HAO/HFO sample collection by means of split spoon techniques within the open borehole provide sufficient material for soil sampling and lithologic description. SynTerra recommends each well screen be
submerged beneath the water table and have a length of at least 10 feet
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TABLE 2
SOIL ANALYTICAL PARAMETERS
BELEWS CREEK STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELEWS CREEK, NC
INORGANIC COMPOUNDS
UNITS
METHOD
Aluminum
mg/kg
EPA 6010D
Antimony
mg/kg
EPA 6020B
Arsenic
mg/kg
EPA 6020A
Barium
mg/kg
EPA 6010C
Beryllium
mg/kg
EPA 6020B
Boron
mg/kg
EPA 6010C
Cadmium
mg/kg
EPA 6020A
Calcium
mg/kg
EPA 6010C
Chloride
mg/kg
EPA 9056A
Chromium
mg/kg
EPA 6010C
Cobalt
mg/kg
EPA 6020A
Copper
mg/kg
EPA 6010C
Iron
mg/kg
EPA 6010C
Lead
mg/kg
EPA 6020A
Magnesium
mg/kg
EPA 6010C
Manganese
mg/kg
EPA 6010C
Mercury
mg/kg
EPA Method 7471B
Molybdenum
mg/kg
EPA 6010C
Nickel
mg/kg
EPA 6010C
Nitrate as Nitrogen
mg/kg
EPA 9056A
pH
SU
EPA 9045D
Potassium
mg/kg
EPA 6010C
Selenium
mg/kg
EPA 6020A
Sodium
mg/kg
EPA 6010C
Strontium
mg/kg
EPA 6010C
Sulfate
mg/kg
EPA 9056A
Thallium (low level) (SPLP Extract only)
mg/kg
EPA 6020A
Total Organic Carbon
mg/kg
EPA 9060
Vanadium
mg/kg
EPA 6020A
Zinc
mg/kgmg/kg
EPA 6010C
Prepared by: RBI Checked by: CIS
Notes•
1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted above.
2. Ash samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045; select ash
samples will also be analyzed for leaching potential using SPLP Extraction Method 1312 in conjunction with USEPA Methods 6010/6020.
3. Analytical methods and reporting limits as presented were applicable at time of CSA field implementation in 2015. Analytical methods
and reporting limits are updated periodically and applied as appropriate.
meq/100g - millequivalents per 100 grams
mg/kg - Milligrams per kilogram
my - Millivolts
S.U. - Standard Unit
P:\Duke Energy Carolinas\20. BELEWS CREEK\29.Structural Fill, Coal Pile and Gypsum Pad Assessment\03.Gypsum Pad Groundwater
Assessment\Tables\
Table 2 - Soil Analytical Parameters Page 1 of 1

TABLE 3
GROUNDWATER ANALYTICAL PARAMETERS
BELEWS CREEK STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELEWS CREEK, NC
PARAMETER
RL
UNITS
METHOD
FIELD PARAMETERS
H
NA
SU
Field Water Quality Meter
Specific Conductance
NA
PS/cm
Field Water Quality Meter
Oxidation/Reduction Potential
NA
mV
Field Water Quality Meter
Temperature
NA
oC
Field Water Quality Meter
Eh
NA
mV
Field Water Quality Meter and Calculation
Dissolved Oxygen
NA
m /L
Field Water Quality Meter
TurbiditV
NA
NTU
Field Water Quality Meter
INORGANICS (total and dissolved)
Aluminum
5
pg/L
EPA 200.7
Antimony
1
pg/L
EPA 200.8
Arsenic
1
pg/L
EPA 200.8
Barium
5
pg/L
EPA 200.7
Beryllium
1
pg/L
EPA 200.8
Boron
50
pg/L
EPA 200.7
Cadmium
0.1
pg/L
EPA 200.8
Chromium
1
pg/L
EPA 200.8
Chromium (VI)
0.025
pg/L
EPA 218.7
Cobalt
1
pg/L
EPA 200.8
Copper
1
pg/L
EPA 200.8
Iron
10
pg/L
EPA 200.7
Lead
1
pg/L
EPA 200.8
Manganese
5
pg/L
EPA 200.7
Mercury (low level)
0.0005
pg/L
EPA 1631E
Molybdenum
1
pg/L
EPA 200.8
Nickel
1
pg/L
EPA 200.8
Selenium
1
pg/L
EPA 200.8
Silver
0.3
pg/L
EPA 200.8
Strontium
5
pg/L
EPA 200.7
Thallium (low level)
0.2
pg/L
EPA 200.8
Vanadium (low level)
0.3
pg/L
EPA 200.8
Zinc
5
L
EPA 200.7
ANIONS/CATIONS/OTHER
Alkalinity (as CaCO3)
5
mg/L
SM 2320B
Bicarbonate
5
mg/L
SM 2320B
Calcium
0.01
mg/L
EPA 200.7
Carbonate
5
mg/L
SM 2320B
Chloride
0.1
mg/L
EPA 300.0
Fluoride
0.1
m /L
EPA 300.0
Magnesium
0.005
m /L
EPA 200.7
Nitrate + Nitrite
0.01
m -N/L
EPA 353.2
Potassium
0.1
m /L
EPA 200.7
Sodium
0.05
m /L
EPA 200.7
Sulfate
0.1
m /L
EPA 300.0
Sulfide
0.1
mg/L
SM 4500-S2D
Total Dissolved Solids
25
mg/L
SM 2540C
Total Phosphorus
0.05
m /L
EPA 365.1
Total Organic Carbon
0.1
m /L
SM5310C/EPA9060A
Total Suspended Solids
2.5
m L
SM 2540D
Prepared by: REB Checked by: KHG
Notes•
OC - Degrees Celsius
µg/L - Micrograms per liter
µS/cm - micro -Siemens per centimeter
RL - Reporting limit
mg - N/L - Milligrams nitrogen per liter
mg/L - Milligrams per liter
mV - Millivolts
NA - Not analyzed
NTU - Nephelometric turbidity unit
S.U. - Standard Unit
P:\Duke Energy Carolinas\20. BELEWS CREEK\29.Structural Fill, Coal Pile and Gypsum Pad Assessment\03.Gypsum Pad Groundwater
Assessment\Tables\
Table 3 - Groundwater Analytical Parameters Page 1 of 1

Gypsum Pad Assessment Work Plan June 26, 2019
Duke Energy Carolinas, LLC — Belews Creek Steam Station SynTerra
Attachment A
P:\Duke Energy Carolinas\20. BELEWS CREEK\29.Structural Fill, Coal Pile and Gypsum Pad
Assessment \ 03.Gypsum Pad Groundwater Assessment \ Belews Creek Gypsum Pad Assessment Work Plan.docx

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
June 24, 2019
Subject: Gypsum Pad Assessment Work Plan Comments — Belews Creek Steam Station
Dear Mr. Draovitch:
On May 24, 2019, the North Carolina Department of Environmental Quality Division of Water
Resources (Division) received the proposed Gypsum Pad Assessment Work Plan for the Belews
Creek Steam Station. The Division has reviewed and hereby approves the proposed assessment
activities under the condition that the following items are addressed as part of the plan
implementation and the results reported in the comprehensive site assessment concerning the
subject area.
• The soil and groundwater characterization should include both the Gypsum Pad and
Gypsum Storage areas. Therefore, in order to properly evaluate the numbers and locations
of the proposed monitoring wells, the footprints of both the Gypsum Storage Area and
Gypsum Pad should be clearly indicated on Figure 1. Components and associated features
should also be labeled including the extent of any liners.
• Verify FGD residue stored on the Gypsum Pad was limited to gypsum. If FGD residue
other than gypsum was stored, please provide a characterization.
• Data should also be collected from each proposed well to evaluate hydraulic parameters
such as hydraulic conductivity and flow velocity in the area.
If applicable, the results should also be incorporated into the updated CAP's revised geochemical
and groundwater fate and transport models. If the results of the modeling show current or future
impacts to groundwater and/or surface water from this area, then appropriate remedial strategies
shall be proposed in the CAP.
North Carolina Department of Environmental Quality I Division of Water Resources
M E 512 North Salisbury Street 1 1636 Mail Service Center I Raleigh, North Carolina 27699-1636
=fir" orW"a 919.707.9000

If you have any questions, please contact Shuying Wang (Winston-Salem Regional Office) at
[phone] or Steve Lanter (Central Office) at [phone].
Sincerely,
on Ris d, Chief
Anima Feeding Operations and Groundwater Section
cc: WSRO WQROS Regional Office
WQROS Central File Copy