NC0004961_Coal Pile Assessment Work Plan_20180116

TECHNICAL MEMORANDUM

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CLT\Coal Pile Assessment Tech Memo.docx
Date: January 12, 2018 File: 1026.15.05I
To: Bristol Grohol (Duke Energy)
Cc: Kathy Webb (SynTerra)
From: Judd Mahan
Subject: Soil and Groundwater Assessment – Former Coal Pile – Riverbend Steam Station
Duke Energy Carolinas, LLC (Duke Energy) owns and operated the Riverbend Steam
Station (RBSS or Site) in Mount Holly, NC. The Site encompasses approximately 340.7
acres. RBSS began operation as a coal-fired generating station in 1929 and was retired in
April 2013. Coal used for electricity generation was transported to the Site by railroad
and stored on approximately 12 acres northeast of the power generation plant. Ash
generated by the coal-fired power-generating units was sluiced to ash management
areas located northeast of the plant operations. Groundwater and soil assessment
activities for the former coal storage area (coal pile) are described herein.
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 impoundment.
Groundwater monitoring wells were installed near the eastern edge of the former coal
pile during CAMA-associated fieldwork. Boron, an inorganic constituent, is commonly
used as an indicator of CCR impacts to groundwater. Groundwater sampling results
from the wells near the former coal pile did not indicate elevated concentrations of
boron. However, the data indicated beryllium in groundwater samples at
concentrations uncharacteristic of other samples from around the coal ash management
areas. For these reasons, Duke Energy understands the former coal pile area soils and
underlying groundwater to be a potential “secondary source” of inorganic constituents
that will be assessed apart from CAMA.
Soil and Groundwater Assessment – Former Coal Pile January 12, 2018
Riverbend Steam Station Page 2 of 3
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Station Description
Coal-fired power generation operations began at RBSS in 1929 and ended in April 2013
when the coal-fired units were retired. Coal was transported on-site by rail and
offloaded onto the coal pile area where it was stored until burned by the coal-powered
energy generating units. The former coal pile area is approximately 12 acres and is
located adjacent to the RBSS power house building and the Catawba River. Coal
removal from the area was completed in September 2014. Commingled coal and soil
material removal was completed in December 2016. A visual inspection was performed
to verify commingled coal and soil material was removed.
The topography at RBSS generally slopes downward from the south to the Catawba
River on the north. The site layout is shown on Figure 1.
Coal Pile Area Assessment Objectives
Objectives of the coal pile area assessment include the following:
Characterize inorganic constituents associated with coal pile area soils
Characterize inorganic constituent concentrations in shallow groundwater
underlying the coal pile area and along the coal pile area perimeter
Compare inorganic constituent concentrations in coal pile area groundwater and
site background groundwater

Soil Assessment
Coal pile area soils will be sampled and analyzed for inorganic parameters to determine
if they are a secondary source of coal pile constituents that can leach into underlying
groundwater. Soil samples will be collected at proposed monitoring well locations
(CPA-1 through CPA-7) as part of well installation activities. Two proposed sample
locations (CPA-4 and CPA-5) are within the footprint of the former coal pile (Figure 1).
Soil samples will be collected at approximately 2-foot intervals to the top of the
groundwater table. An additional soil sample will be collected below the water table
within the new well screened intervals. Soil samples will be analyzed for inorganic
parameters as listed on Table 1.
Groundwater Assessment
Fourteen coal pile assessment (CPA) groundwater monitoring wells will be installed to
characterize coal pile area groundwater. Seven shallow (“S”) and seven deep (“D”)
groundwater monitoring wells (CPA-1S/D, CPA-2S/D, CPA-3S/D, CPA-4S/D, CPA-
5S/D, CPA-6S/D, and CPA-7S/D) will be installed as well pairs. Four wells (CPA-4S/D
and CPA-5S/D) will be installed within the former coal pile footprint. Proposed
approximate CPA well installation locations are shown on Figure 1 and proposed well
Soil and Groundwater Assessment – Former Coal Pile January 12, 2018
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details are provided as Table 2. Specific well locations may be shifted depending upon
access and field conditions at the time of installation. Groundwater samples will be
analyzed for inorganic constituents as listed on Table 3.
Coal Pile Assessment Report
A coal pile assessment report will be prepared once all soil and groundwater sample
analytical data is received. 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

ATTACHMENTS:
Table 1: Soil Analytical Methods
Table 2: Proposed Coal Pile Assessment Soil Samples and Monitoring Wells
Table 3: Groundwater Analytical Methods
Figure 1: Proposed Monitoring Well Locations
Soil and Groundwater Assessment – Former Coal Pile January 12, 2018
Riverbend Steam Station

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ATTACHMENTS

TABLE 1
SOIL ANALYTICAL METHODS
RIVERBEND STEAM STATION
DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, 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/kg EPA 6010C
Notes:
1. Soil samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045, as noted above.
meq/100g - millequivalents per 100 grams
mg/kg - Milligrams per kilogram
mV - Millivolts
S.U. - Standard Unit
Prepared by: RBI Checked by: SRW/TCP
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.
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Table 1 Soil Analytical Methods Page 1 of 1
TABLE 2
PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS
RIVERBEND STEAM STATION
DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC
Monitoring
Well ID
Estimated
Well Depth
(feet bgs)
Soil Sample ID
(Estimated Depth
Interval in feet bgs)
Comments
----CPA-1SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-1SB (5-6)Unsaturated soil sample
----CPA-1SB (8-9)Unsaturated soil sample
----CPA-1SB (11-12)Unsaturated soil sample
----CPA-1SB (14-15)Unsaturated soil sample
----CPA-1SB (17-18)Unsaturated soil sample
----CPA-1SB (20-21)Unsaturated soil sample
----CPA-1SB (23-24)Unsaturated soil sample
CPA-1S 35 CPA-1SB (30-31)Soil sample from shallow well screened interval
CPA-1D 150 CPA-1SB (145-146)Soil sample from deep well screened interval
----CPA-2SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-2SB (5-6)Unsaturated soil sample
----CPA-2SB (8-9)Unsaturated soil sample
----CPA-2SB (11-12)Unsaturated soil sample
----CPA-2SB (14-15)Unsaturated soil sample
----CPA-2SB (17-18)Unsaturated soil sample
----CPA-2SB (20-21)Unsaturated soil sample
----CPA-2SB (23-24)Unsaturated soil sample
CPA-2S 35 CPA-2SB (30-31)Soil sample from shallow well screened interval
CPA-2D 150 CPA-2SB (145-146)Soil sample from deep well screened interval
----CPA-3SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-3SB (5-6)Unsaturated soil sample
----CPA-3SB (8-9)Unsaturated soil sample
----CPA-3SB (11-12)Unsaturated soil sample
----CPA-3SB (14-15)Unsaturated soil sample
----CPA-3SB (17-18)Unsaturated soil sample
----CPA-3SB (20-21)Unsaturated soil sample
----CPA-3SB (23-24)Unsaturated soil sample
CPA-3S 35 CPA-3SB (30-31)Soil sample from shallow well screened interval
CPA-3D 150 CPA-3SB (145-146)Soil sample from deep well screened interval
----CPA-4SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-4SB (5-6)Unsaturated soil sample
----CPA-4SB (8-9)Unsaturated soil sample
----CPA-4SB (11-12)Unsaturated soil sample
----CPA-4SB (14-15)Unsaturated soil sample
----CPA-4SB (17-18)Unsaturated soil sample
----CPA-4SB (20-21)Unsaturated soil sample
----CPA-4SB (23-24)Unsaturated soil sample
CPA-4S 35 CPA-4SB (30-31)Soil sample from shallow well screened interval
CPA-4D 150 CPA-4SB (145-146)Soil sample from deep well screened interval
----CPA-5SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-5SB (5-6)Unsaturated soil sample
----CPA-5SB (8-9)Unsaturated soil sample
----CPA-5SB (11-12)Unsaturated soil sample
----CPA-5SB (14-15)Unsaturated soil sample
----CPA-5SB (17-18)Unsaturated soil sample
----CPA-5SB (20-21)Unsaturated soil sample
----CPA-5SB (23-24)Unsaturated soil sample
CPA-5S 35 CPA-5SB (30-31)Soil sample from shallow well screened interval
CPA-5D 150 CPA-5SB (145-146)Soil sample from deep well screened interval
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TABLE 2
PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS
RIVERBEND STEAM STATION
DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC
Monitoring
Well ID
Estimated
Well Depth
(feet bgs)
Soil Sample ID
(Estimated Depth
Interval in feet bgs)
Comments
----CPA-6SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-6SB (5-6)Unsaturated soil sample
----CPA-6SB (8-9)Unsaturated soil sample
----CPA-6SB (11-12)Unsaturated soil sample
----CPA-6SB (14-15)Unsaturated soil sample
----CPA-6SB (17-18)Unsaturated soil sample
----CPA-6SB (20-21)Unsaturated soil sample
----CPA-6SB (23-24)Unsaturated soil sample
CPA-6S 35 CPA-6SB (30-31)Soil sample from shallow well screened interval
CPA-6D 150 CPA-6SB (145-146)Soil sample from deep well screened interval
----CPA-7SB (2-3)
Near-surface unsaturated soil sample (water table ~25 feet
bgs)
----CPA-7SB (5-6)Unsaturated soil sample
----CPA-7SB (8-9)Unsaturated soil sample
----CPA-7SB (11-12)Unsaturated soil sample
----CPA-7SB (14-15)Unsaturated soil sample
----CPA-7SB (17-18)Unsaturated soil sample
----CPA-7SB (20-21)Unsaturated soil sample
----CPA-7SB (23-24)Unsaturated soil sample
CPA-7S 35 CPA-7SB (30-31)Soil sample from shallow well screened interval
CPA-7D 150 CPA-7SB (145-146)Soil sample from deep well screened interval
Prepared by: JDM Checked by: PBT
Notes:
bgs = below ground surface
~ = Approximately
SynTerra recommends rotosonic drilling methods for boring and well installation.
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 GWA-3, GWA-11 and GWA-12 well clusters.
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.
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TABLE 3
GROUNDWATER ANALYTICAL METHODS
RIVERBEND STEAM STATION
DUKE ENERGY CAROLINAS, LLC, MOUNT HOLLY, NC
PARAMETER RL UNITS METHOD
pH NA SU Field Water Quality Meter
Specific Conductance NA µS/cm Field Water Quality Meter
Temperature NA ºC Field Water Quality Meter
Dissolved Oxygen NA mg/L Field Water Quality Meter
Oxidation Reduction Potential NA mV Field Water Quality Meter
Turbidity NA NTU Field Water Quality Meter
Ferrous Iron NA mg/L Field Test Kit
Aluminum 0.005 mg/L EPA 200.7 or 6010D
Antimony 0.001 mg/L EPA 200.8 or 6020B
Arsenic 0.001 mg/L EPA 200.8 or 6020A
Barium 0.005 mg/L EPA 200.7 or 6010C
Beryllium 0.001 mg/L EPA 200.8 or 6020A
Boron 0.05 mg/L EPA 200.7 or 6010C
Cadmium 0.001 mg/L EPA 200.8 or 6020A
Chromium 0.001 mg/L EPA 200.8 or 6010C
Cobalt 0.001 mg/L EPA 200.8 or 6020A
Copper 0.001 mg/L EPA 200.8 or 6020B
Iron 0.01 mg/L EPA 200.7 or 6010C
Lead 0.001 mg/L EPA 200.8 or 6020A
Manganese 0.005 mg/L EPA 200.7 or 6010C
Mercury (low level)0.005 ng/L 1631 ONLY
Molybdenum 0.001 mg/L EPA 200.8 or 6020B
Nickel 0.001 mg/L EPA 200.8 or 6020B
Phosphorus 0.005 mg/L EPA 365.1
Selenium 0.001 mg/L EPA 200.8 or 6020A
Strontium 0.005 mg/L EPA 200.7 or 6010C
Thallium (low level)0.0002 mg/L EPA 200.8 or 6020A
Vanadium (low level)0.0003 mg/L EPA 200.8 or 6020A
Zinc 0.005 mg/L EPA 200.7 or 6010C
Alkalinity (as CaCO3)5 mg/L SM 2320B
Bicarbonate 5 mg/L SM 2320
Calcium 0.01 mg/L EPA 200.7
Carbonate 5 mg/L SM 2320
Chloride 0.1 mg/L EPA 300.0 or 9056A
Magnesium 0.005 mg/L EPA 200.7
Methane 0.01 mg/L RSK 175
Nitrate as Nitrogen 0.01 mg-N/L EPA 353.2
Potassium 0.1 mg/L EPA 200.7
Sodium 0.05 mg/L EPA 200.7
Sulfate 0.1 mg/L EPA 300.0 or 9056A
Sulfide 0.1 mg/L SM4500S2-D
Total Dissolved Solids 25 mg/L SM 2540C
Total Organic Carbon 0.1 mg/L SM 5310C/EPA9060A
Total Suspended Solids 2.5 mg/L SM 2450D
Prepared by: RBI Checked by: SRW/TCP
Notes:
ºC - Degrees Celsius
µS/cm = micro-Siemens per centimeter
mg/L - Milligrams per liter
mg - N/L - Milligrams nitrogen per liter
mV - 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
2.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.
INORGANICS
FIELD PARAMETERS
1. Select constituents will be analyzed for total and dissolved concentrations.
ANIONS/CATIONS
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BG-4S/D/BR
MW-9/BR
AB-2D
MW-15D/BR
BG-5D/BR
MW-8S/I/D GWA-21S/D/BR
MW-11SR/DR
MW-13
MW-10 MW-14
OB-1 OB-2
GATE 7
AB-1S/D
AB-2S/D
AB-3S/D/BR
AB-5S/SL/D
AB-6S/BRU
AB-7S/I/D
AB-8S/D
BG-1S/D
BG-2S/D/BR
BG-3S/D
C-1S/BRU
C-2S/D
GWA-10S/BRU
GWA-11S/D
GWA-12S/D
GWA-14S
GWA-1S/BRU
GWA-20S/D/BR
GWA-22S/D/BR-A
GWA-23S/D/BR
GWA-2S/BR/BRU
GWA-3S-A/D
GWA-4S/D/BR
GWA-5S/D
GWA-6S/D
GWA-7S/D/BR
GWA-8S/D
GWA-9S/D/BR
MW-1S/D
MW-2S/D
MW-3S/D MW-4S/D
MW-5S/D
MW-6S/D
MW-7S/D/BRCPA-5S/D
CPA-7S/D
CPA-6S/D
CPA-1S/D
CPA-4S/D
CPA-3S/D
CPA-2S/D
FIGURE 1PROPOSED MONITORING WELL LOCATIONSCOAL PILE ASSESSMENTRIVERBEND STEAM STATIONDUKE ENERGY CAROLINAS, LLCMOUNT HOLLY, NORTH CAROLINADRAWN BY: A . FEIGLPROJECT MANAGER: J. MAHANCHECKED BY: B. WYLIE
DATE: 12/15/2017
148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE [phone]www.synterracorp.com
P:\Duke Energy Progress.1026\00 GIS BASE DATA\Riverbend\MapDocs\Vetting\CoalPileAssess\Riverbend_CoalPileAssess_20171214.mxd
300 0 300 600150
GRAPHIC SCALE IN FEET
LEGEND
!(PROPOSED COAL PILE ASSESSMENTMONITORING WELL LOCATION
&<EXISTING MONITORING W ELL LOCATION
&<OBSERVATION WELL LOCATION
WETLANDS [AMEC]
CULTURAL AREA [AMEC]
RAILROAD
TRANSMISSION LINE
APPROXIMATE WASTE BOUNDARY
DUKE POWER PLANT BOUNDARY
NOTES:
PROPOSED WELL LOCATIONS SHOWN ARE APPROXIMATED.EXACT WELL LOCATIONS WILL BE DETERMINED BASED ONACCESS AND FIELD CONDITIONS AT THE TIME OF WELLINSTALLATION.
ALL BOUNDARIES ARE APPROXIMATE.
SITE AERIAL ORTHOPHOTOGRAPHY OBTAINED FROMMECKLENBURG COUNTY GIS, DATED 2017. ADDITIONAL AERIALORTHOPHOTOGRAPHY OBTAINED FROM WSP, 10/30/2015.
DRAWING HAS BEEN SET WITH A PROJECTION OF NORTHCAROLINA STATE PLANE COORDINATE SYSTEM FIPS 3200
CATAWBA RIVERCATAWBA RIVER
FORMERCOAL PILE
ASH BASINSECONDARY CELL
ASH BASINPRIMARY CELL
ASH STORAGE
CINDERSTORAGE