Coal Pile Additional Assessment Tech Memo_20200522

526 South Church St.
DUKE
Charlotte, NC 28202
Mailing Address
ENE R�Y7
P.O. Box 1006
Mail Code EC 1
Charlotte, NC 2828201-1006
980-373-2779
May 22, 2020
North Carolina Department of Environmental Quality
Division of Water Resources
Mooresville Regional Office
610 East Center Avenue Suite 301
Mooresville, NC 28115
Attn: Mr. Andrew Pitner
Re: Former Coal Pile Additional Assessment
Buck Steam Station
1555 Dukeville Road
Salisbury, NC 28146
Dear Mr. Pitner:
Results of the initial investigation at the Buck Steam Station Former Coal Pile Area have indicated
a need for additional assessment. Attached is a technical memorandum and associated figures and
tables outlining proposed activities including additional monitoring well installation. Duke Energy
requests concurrence with the proposed activities. If you have any questions or need any
clarification regarding the information provided, feel free to contact me at Ryan.Czop@duke-
energy.com or at 980-373-2779 at your convenience.
Respectfully submitted,
4, 4-9�
Y4--,
Ryan Czop
Duke Energy, Environmental Services
cc (via email): Ms. Brandy Costner — DEQ MRO
Mr. Eric Smith — DEQ Central Office
Mr. Steve Lanter — DEQ Central Office
Mr. Rick Bolich — DEQ Central Office
Ms. Tyler Hardin - Duke Energy
Mr. John Toepfer — Duke Energy
Mr. Ed Sullivan — Duke Energy
Mr. Walter Gerald — SynTerra
Mr. John Thao — SynTerra
Attachment: Technical Memorandum- Buck Steam Station — Additional Assessment at Former
Coal Pile Area

,(VIP
synTerra
Date:
To:
Cc:
From
May 19, 2020
Ryan Czop (Duke Energy)
TECHNICAL MEMORANDUM
File: 1026.16
Michael Harazim (Duke Energy), Kathy Webb, and John Thao (SynTerra)
Walter Gerald, North Carolina LG #0446
Subject: Buck Steam Station - Additional Assessment at Former Coal Pile Area
Duke Energy Carolinas, LLC (Duke Energy) owns and formerly operated the Buck
Steam Station (Buck, BSS, Site), located on the Yadkin River in Rowan County near
Salisbury, North Carolina. The Site encompasses approximately 640 acres. The
topography at the Site generally slopes downward from the south to the Yadkin River
to the north. Pertinent features of the Site layout are shown on Figure 1.
BSS was put into operation in 1926 as a coal-fired power -generating station. The Buck
Combined Cycle Plant natural gas facility was put into operation in late 2011.
Subsequently, BSS was decommissioned and taken offline in April 2013. The former
coal pile area is downgradient of ash basin cell 1 to the north/northwest of the Site and
south of the Yadkin River. The coal pile was removed as part of decommissioning the
steam station.
Proposed groundwater and soil assessment activities pertaining to the former coal pile
area are described herein.
Regulatory Background
The Coal Ash Management Act of 2014 (CAMA) requires owners of a coal combustion
residuals (CCR) surface impoundment to conduct a detailed assessment of site
groundwater within and surrounding the CCR surface impoundments.
Ash basin cells 1, 2, and 3 and the ash storage area were the primary sources of CCR-
related constituents identified in the initial CAMA-related Comprehensive Site
Assessment (CSA) (HDR, 2015). Duke Energy submitted a work plan for performing
an assessment of the former coal pile area on December 11, 2018. The North Carolina
Department of Environmental Quality (NCDEQ) approved the work plan with
comments via letter dated January 11, 2019. Duke Energy provided a revised work
plan on January 15, 2019 addressing those comments. The former coal pile area was
evaluated as a potential additional source area after steam station decommissioning
activities were completed. During initial assessment activities, 13 groundwater
monitoring wells were installed within the limits of the former coal pile area in
November 2019 and February 2020, and one upgradient well was installed outside the
footprint of the former coal pile area in November 2019 (Figure 1).

Additional Assessment of the Former Coal Pile Work Plan
May 19, 2020
Buck Steam Station
Page 2 of 4
Initial groundwater analytical data collected from the wells installed during the initial
assessment indicated the presence of sulfate and strontium as well as other
constituents. A relative lack of boron in the groundwater samples indicates that these
constituents are likely attributed to historic storage of coal, as opposed to management
of CCRs. Initial groundwater analytical data for sulfate are shown in Figure 1. The
purpose of the additional assessment activities outlined herein will be to delineate the
downgradient horizontal and vertical extent of constituents in soil and groundwater
that might be related to the former coal pile area.
Prior Assessment Activities
Groundwater monitoring wells were installed in six locations around the limits of the
former coal pile area. The occurrence of sulfate in groundwater at each location is
illustrated on Figure 1. Sulfate is used as a surrogate compound for other constituents
because it is frequently associated with coal, it is readily soluble in groundwater, and it
will advect with groundwater flow. Groundwater elevation contours in the bedrock
flow zone from the first quarter 2020 sampling are also illustrated on Figure 1.
The distribution of sulfate in groundwater indicates the need for additional assessment
downgradient, to the north of the Coal Pile, between the former coal pile area and the
Yadkin River.
Objectives of Additional Assessment of the Former Coal Pile Area
Objectives of the additional assessment of the former coal pile area include the
following:
• Further characterization and delineation of constituent concentrations in
groundwater downgradient of the former coal pile area
• Refine the understanding of groundwater flow direction in the former coal pile
area
• Incorporate the data in the upcoming site -wide Comprehensive Site Assessment
Update report (February 2021) to evaluate the potential need for corrective action
pertaining to the former coal pile area
Additional Soil Assessment at the Former Coal Pile
Drilling and assessment activities will be performed in accordance with the approved
work plan for the Coal Pile Assessment (SynTerra, January 14, 2019), and as outlined
below.

Additional Assessment of the Former Coal Pile Work Plan May 19, 2020
Buck Steam Station Page 3 of 4
The sampling and analysis of additional unsaturated soils is proposed. The purpose of
that sampling and analysis is to establish inorganic parameters that would support
further horizontal and vertical delineation downgradient of the former coal pile area.
Soil samples would be collected at proposed monitoring well locations CPA-7 and CPA-
8 during well installation activities (Figure 1). Soil samples would be collected from 2
feet below ground surface and 2 feet above the water table. An additional soil sample
would be collected below the water table, within the new well's screened interval, for
analysis of hydrous ferric oxide (HFO) and hydrous aluminum oxide (HAO). Soil
samples would be analyzed for inorganic parameters listed on Table 1.
Additional Assessment of the Former Coal Pile Groundwater
One additional lower bedrock well (well number suffix BRL) will also be installed at the
existing CPA-6 well cluster location during this event to assist with vertical delineation
of groundwater located at the former coal pile area. Two additional well clusters (CPA-
7 and CPA-8) are intended for additional horizontal and vertical delineation
downgradient of the former coal pile area. Proposed well installation locations are
shown on Figure 1, and proposed well details are provided in Table 2.
Field screening for sulfates would be performed during bedrock drilling activities. That
screening would help delineate the vertical extent of sulfate concentrations prior to
selection of an interval to set the well screen.
Specific well locations may be shifted depending on access and field conditions at the
time of installation. After completion of well installation, dedicated pumps will be
installed in each well, groundwater samples will be collected (initial sampling event),
and slug testing activities will be performed. Groundwater samples will be analyzed for
the field parameters (e.g., pH, conductivity, and turbidity) and inorganic constituents
consistent with ongoing CAMA assessment activities (Table 3).
Additional Assessment Report
The additional assessment activities outlined above will be included in the upcoming
Comprehensive Site Assessment Update report (February 2021), which will include the
soil and groundwater analytical data.
Attachments;
Table 1: Soil Analytical Methods
Table 2: Proposed Soil Samples and Monitoring Wells
Table 3: Groundwater Analytical Methods
Figure 1: Proposed Additional Former Coal Pile Assessment Well Locations

Work Plan for Additional Assessment of the Former Coal Pile May 19, 2020
Buck Steam Station
ATTACHMENTS

TABLE 1
SOIL ANALYTICAL METHODS
COAL PILE ASSESSMENT
BUCK STEAM STATION
DUKE ENERGY CAROLINAS, LLC, SALISBURY, NC
INORGANIC CONSTITUENTS
UNITS
METHOD
Aluminum
mg/kg
EPA 6010D
Antimony
mg/kg
EPA 6020B
Arsenic
mg/kg
EPA 6020B
Barium
mg/kg
EPA 6010D
Beryllium
mg/kg
EPA 6010D
Boron
mg/kg
EPA 6010D
Cadmium
mg/kg
EPA 6020B
Calcium
mg/kg
EPA 6010D
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 6020B
Magnesium
mg/kg
EPA 6010D
Manganese
mg/kg
EPA 6010C
Mercury
mg/kg
EPA 7471 B
Molybdenum
mg/kg
EPA 6010D
Nickel
mg/kg
EPA 6010C
Nitrate as Nitrogen
mg/kg
EPA 9056A
pH
Su
EPA 9045D
Potassium
mg/kg
EPA 6010D
Selenium
mg/kg
EPA 6020B
Sodium
mg/kg
EPA 6010D
Strontium
mg/kg
EPA 6010D
Sulfate
mg/kg
EPA 9056A
Thallium (total, low level)
mg/kg
EPA 6020B
Total Organic Carbon
mg/kg
EPA 9060
Vanadium
mg/kg
EPA 6020B
Zinc
mg/kgmg/kg
EPA 6010C
Prepared by: RBI Checked by: WJW
Notes:
1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted
above.
mg/kg - milligrams per kilogram
S.U. - Standard Unit
Table 1 - Soil Analytical Methods Page 1 of 1

TABLE 2
PROPOSED SOIL SAMPLES AND MONITORING WELLS
COAL PILE ASSESSMENT
BUCK STEAM STATION
DUKE ENERGY CAROLINAS, LLC, SALISBURY, NC
Estimated
Soil Sample ID
Planned
Monitoring
Well Depth
(Estimated Depth
Screened
Comments
Well ID
(feet bgs)
Interval, feet bgs)
Interval
(feet bgs)
--
--
--
--
Installation of 6" surface casing to — 60 bgs
CPA-613RL
200
CPA-6SB (195-196)
190-200
Rock sample from bedrock well screened interval
Near -surface unsaturated soil sample (water table "10
CPA-7SB (2-3)
feet bgs)
Near -top of water table unsaturated soil sample
CPA-7SB (8-9)
(estimated depth, will be determined in the field)
CPA-7S
30
CPA-7SB (25-26)
20-30
Soil sample from shallow well screened interval
CPA-713
70
CPA-7SB (65-66)
60-70
Soil sample from deep well screened interval
CPA-76R
120
CPA-7SB (115-116)
110-120
Soil sample from bedrock well screened interval
Near -surface unsaturated soil sample (water table —10
CPA-8SB (2-3)
feet bgs)
Near -top of water table unsaturated soil sample
CPA-8SB (8-9)
(estimated depth, will be determined in the field)
CPA-8S
30
CPA-8SB (25-66)
20-30
Soil sample from shallow well screened interval
CPA-813
70
CPA-8SB (65-66)
60-70
Soil sample from deep well screened interval
CPA-813R
120
CPA-8SB (115-116)
110-120
Soil sample from bedrock well screened interval
Prepared by: JYT Checked by: WCG
Notes:
bgs = below ground surface
— = Approximately
Continuous cores from sonic drilling provide sufficient material for soil sampling and lithologic description.
Estimated well and soil sample depths based on data from the CPA-1BR, CPA-4BR, and CPA-6BR wells.
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.
SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet.
SynTerra recommends rotosonic drilling methods for boring and well installation of CPA-6BRL, CPA-7S/D/BR, and CPA-8S/D/BR wells.
Table 2 - Buck Proposed Coal Pile Assessment Boring & Well Depths Page 1 of 1

TABLE 3
GROUNDWATER ANALYTICAL METHODS
COAL PILE ASSESSMENT
BUCK STEAM STATION
DUKE ENERGY CAROLINAS, LLC, SALISBURY, NC
PARAMETER I RL JUNITS IMETHOD
FIELD PARAMETERS
H
NA
SU
Field Water Quality Meter
Specific Conductance
NA
PS/Cm
Field Water Quality Meter
Temperature
NA
oC
Field Water Quality Meter
Dissolved Oxygen
NA
m L
Field Water Quality Meter
Oxidation Reduction Potential
NA
mV
Field Water Quality Meter
Eh
NA
mV
Field Water Quality Meter
Turbidity
NA
jNTU
I Field Water Quality Meter
INORGANICS
Aluminum
0.005
m L
EPA 200.7 or 6010D
Antimony
0.001
m L
EPA 200.8 or 6020B
Arsenic
0.001
m L
EPA 200.8 or 6020B
Barium
0.005
m L
EPA 200.7 or 6010D
Beryllium
0.001
m L
EPA 200.8 or 6020B
Boron
0.05
m L
EPA 200.7 or 6010D
Cadmium
0.001
m L
EPA 200.8 or 6020B
Chromium
0.001
m L
EPA 200.8 or 6020B
Cobalt
0.001
m L
EPA 200.8 or 6020B
Copper
0.001
m L
EPA 200.8 or 6020B
Hexavalent Chromium
0.000025
m L
EPA 218.7
Iron
0.01
m L
EPA 200.7 or 6010D
Lithium
0.005
m L
EPA 200.7 or 6010D
Lead
0.001
m L
EPA 200.8 or 6020B
Manganese
0.005
m L
EPA 200.7 or 6010D
Mercury
0.00005
m L
EPA 245.1 or 7470A
Molybdenum
0.001
m L
EPA 200.8 or 6020B
Nickel
0.001
m L
EPA 200.8 or 6020B
Selenium
0.001
m L
EPA 200.8 or 6020B
Strontium
0.005
m L
EPA 200.7 or 6010D
Thallium low level
0.0002
m L
EPA 200.8 or 6020B
Vanadium low level
0.0003
m L
EPA 200.8 or 6020B
Zinc
0.005
m L
EPA 200.7 or 6010D
RADIONUCLIDES
Radium 226
1
Ci L
EPA 903.1 Modified
Radium 228
1
Ci L
EPA 904.0 SW846 9320 Modified
Uranium 233 234 236 238
Varies by isotope
µ /mL
SW846 3010A/602013
Total Uranium
NA
/mL
Calculated
ANIONS/CATIONS/OTHER
Alkalinity as CaCO3
5
m L
SM 2320B
Bicarbonate
5
m L
SM 2320B
Calcium
0.01
m L
EPA 200.7
Carbonate
5
m L
SM 2320B
Chloride
0.1
m L
EPA 300.0 or 9056A
Fluoride
0.1
m L
EPA 300.0 or 9056A
Magnesium
0.005
m L
EPA 200.7 or 6010D
Potassium
0.1
m L
EPA 200.7
Sodium
0.05
m L
EPA 200.7
Sulfate
0.1
m L
EPA 300.0 or 9056A
Sulfide
0.1
m L
SM 4500 S2 D
Total Dissolved Solids
25
m L
ISM 2540C
Total Phosphorus
0.05
m L
I EPA 365.1
Total Organic Carbon
0.1
m L
SM5310C EPA9060A
Total Suspended Solids
5
m L
ISM 2450D
Notes:
1. Select constituents will be analyzed for total and dissolved concentrations.
OC - degrees Celsius
VS/cm = micro -Siemens per centimeter
mg/L - milligrams per liter
mg - N/L - milligrams nitrogen per liter
my - millivolts
NA - not analyzed
NTU - Nephelometric turbidity unit
pCi/L - picoCuries per liter
RL = reporting limit
S.U. - Standard Unit
ug/mL - micrograms per milliliter
Prepared by: HHS Checked by: RHJ
Page 1 of 1

NOTES:
1. SAMPLE LOCATIONS WERE DERIVED FROM VARIOUS SOURCES AND ARE
AMIX OF SURVEYED AND APPROXIMATE LOCATIONS. THEREFORE, SAMPLE
LOCATIONSARE TO BE DEEMED APPROXIMATE.
2. AERIAL PHOTOGRAPHY OBTAINED FROM GOOGLE EARTH PRO AND IS DATED
APRIL 8, 2017. WSP SURVEY CONDUCTED APRIL 17, 2014.
3. THE WATERS OF THE US HAVE NOT BEEN APPROVED BY THE US ARMY
CORPS OF ENGINEERS AT THE TIME OF THE MAP CREATION. THIS MAP IS A
PRELIMINARY JURISDICTIONAL DETERMINATION ONLY. THE PRELIMINARY
WETLANDS AND STREAMS BOUNDARIES WERE OBTAINED FROM AMEC
FOSTER WHEELER ENVIRONMENTAL & INFRASTRUCTURE, INC. NATURAL
RESOURCE TECHNICAL REPORT FOR BUCK STEAM STATION DATED MAY
29,2015.
4. DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH CAROLINA STATE
PLANE COORDINATE SYSTEM RIPS 3200 (NAD83).
5. SULFATE CONCENTRATIONS BOLDED IF GREATER THAN SCREENING
CRITERIA.
6. WATER LEVELS IN BEDROCK WELLS MEASURED ON MARCH 9, 2020.
7. SO4 DATA POSTED FROM WELLS SAMPLED ON JAN.22-23 AND FEB. 26, 2020.
P - • P : t'.
04 SCFeeningValue (mg1L)
02 L 250
2017 BTV Shallow 3
2017 BTV Transition 7
2017 BTV Bedrock 2
I -r
CPA-8S/D/BR
■r'�! -- -r' T -�
;PA-6BRL
i31.91
m
Sulfate (m,/L)
i
' CPA-1BR
627.07
s^
_ y '
CCR-27D A
GWA-12S/BRU
Sulfate (mg/L)
CPA-15 2000 - +
CPA -ID 1900 �__��_i`a_ �•
CPA-11311 820�
CPA-2BR r
1639.15
Sulfate m L _ ■
7CPA-3BR
636.16 CPA-2D
Sulfate(mg/L) losr.iu Sulfatelmg/LI
• !? CPA-26R GWA-6S/E
• CPA-4D 200 • CPA-3D 3500
' CPA-4BR 310 • • CPA-3BR 1600 ..-
,.- • ••• - �� MW-1f
IN
• CCR-26BR ".1
\.
Sulfate( g Q �' ,
CPA -SD 41 - r j•
- � CPA-SBR INS
6. �rl• v � �� � — � _r GWA-7S/D �� 1 _ _
Woo
CCR-8D r ■
• �^"" Sulfate (mg/L) P'
GWA-19S 22.9
�• . } GWA-19D 36.8 _J,
CCR-9D
1 / `. •+� _ '1` 1. GWA-198R 23 0
}
I'i• _ F / GWA-19BR � —,_ or _
655.95 rrr rrr— •
7"M
,h0000 �.
y
LEGEND
PROPOSED WELL LOCATION
• COAL PILE WELL- INSTALLED
!
O MONITORING WELL
INFERRED GROUNDWATER FLOW DIRECTION (BEDROCK)
INFERRED WATER LEVEL CONTOUR
FORMER COAL PILE BOUNDARY
WASTE BOUNDARY
;
ASH STORAGE BOUNDARY
- - - COMPLIANCE BOUNDARY
• • DUKE ENERGY CAROLINAS PROPERTY LINE
{ ♦ �_ GWA-9S/D/BR/BRA
671.24 �O /
I•
40000,
r
_ I �6•
mp r • 4T .
Ile
CCR-7S/D
Ile
�►' ' . '" /
.00*O
. / . DUKE
GWA-22D / ENERGY,
CCR-6S/D AS
MW-9S/D
1
. - ///
F �- •� synTerra
4
CCR-8S/D
GRAPHIC SCALE
150 0 150 300
(IN FEET)
DRAWN BY: J. KIRTZ DATE: 09/26/2019
REVISED BY: J. KIRTZ DATE: 05/20/2020
CHECKED BY: J. THAD DATE: 05/20/2020
APPROVED BY: J. THAD DATE: 05/20/2020
PROJECT MANAGER: W. GERALD
CCR-9S/D
('
FIGURE 1
PROPOSED MONITORING WELL LOCATIONS
COAL PILE ASSESSMENT
BUCK STEAM STATION
SALISBURY, NORTH CAROLINA