NC0004979_Coal Pile Assessment Tech Memo_20180116

TECHNICAL MEMORANDUM

P:\Duke Energy Carolinas\17.ALLEN\05J. Coal Pile\Assessment\Work Plan\Final\Allen - Coal Pile Assessment
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Date: January 12, 2018 File: 1026.17.05J
To: Sean DeNeale (Duke Energy)
Cc: Kathy Webb (SynTerra)
From: Chris Suttell
Subject: Allen Steam Station Coal Pile Assessment Work Plan
Duke Energy Carolinas, LLC (Duke Energy) owns and operates the Allen Steam Station
(Allen, Plant, or Site) in Belmont, Gaston County, North Carolina. The Site encompasses
approximately 1,009 acres. Groundwater and soil assessment activities proposed for
the 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 impoundments.
Primary sources of CCR-related constituents were identified during the Comprehensive
Site Assessment (CSA) for CAMA to be the ash basins, which consists of the active ash
basin and the inactive ash basin. Groundwater monitoring wells were installed south
and west of the coal pile during CAMA-associated fieldwork. Additionally, wells were
installed for compliance with the Environmental Protection Agency’s Coal Combustion
Residuals (CCR) Rule in the vicinity of the coal pile area. 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, CAMA and CCR assessment data
indicated constituents, such as arsenic, beryllium, cadmium, nickel, selenium, thallium,
and zinc in groundwater samples at concentrations uncharacteristic of other samples
from around the ash basins. For these reasons, Duke Energy understands the former
coal pile area soils and underlying groundwater to be a potential additional primary
and “secondary source” of inorganic constituents that will be assessed apart from
CAMA or the CCR Rule.
Station Description
Power generating operations began at Allen in 1957 and the Plant remains active. Coal
used to fuel power generating units is transported to Allen by railroad and is stored on
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approximately 18.5 acres south of the power generation plants and north of the ash
basins. CCR have been sluiced to the ash basin system located south of the power
generating units, which includes an active ash basin and the inactive ash basin.
Topography at the site generally slopes downward from the west to the Catawba River
to the east of the Plant and coal pile area.
Currently, a portion of the coal pile is being modified as part of the Allen Steam Station
Water Re-direction Program to allow construction of a lined holding basin on the east
side of the historical coal pile footprint. Part of the construction of the holding basin
includes installation and operation of extraction wells to de-water the area. As of the
date of this memorandum, construction of the dewatering system is complete and the
system is operating at an approximate flowrate of 80 gallons per minute. Eight
observation wells were installed in the vicinity of the holding basin construction project,
and water levels are being recorded on a daily basis. Pressure transducers have also
been installed in wells surrounding the coal pile to monitor water level changes on a
more frequent basis.
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 soil and groundwater along
the coal pile perimeter
Compare inorganic constituent concentrations in coal pile area to Site
background concentrations

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 (CP-
1 through CP-6) as part of well installation activities (Figure 1). Soil samples will be
collected at approximately 2-foot intervals to the top of the groundwater table
(approximately 10 feet below ground surface). 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 listed on Table 1.
Groundwater Assessment
Twelve coal pile assessment (CP) groundwater monitoring wells will be installed to
characterize coal pile area groundwater in shallow and deep groundwater zones. The
shallow zone is considered groundwater within soil and saprolite material. The deep
zone is considered groundwater within partially weathered rock transition zone
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material underlying the shallow zone and overlying competent bedrock. Six shallow
(“S”) and six deep (“D”) groundwater monitoring wells (CP-1S/D through CP-6S/D)
will be installed as well pairs. Proposed CP well installation locations are shown on
Figure 1 and proposed well 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 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 Coal Pile Assessment Sample Locations
Allen Steam Station Coal Pile Assessment Work Plan January 12, 2018
Allen Steam Station

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ATTACHMENTS
TABLE 1
SOIL ANALYTICAL METHODS
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
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Table 1 Soil Analytical Methods Page 1 of 1
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.
TABLE 2
PROPOSED COAL PILE ASSESSMENT SOIL SAMPLES AND MONITORING WELLS
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
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Table 2 - Allen Proposed Coal Pile Assessment Boring & Well Depths Page 1 of 1
Monitoring
Well ID
Estimated
Well Depth
(feet bgs)
Soil Sample ID
(Estimated Depth
Interval in feet bgs)
Comments
----CP-1SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs
----CP-1SB (5-6)Unsaturated soil sample, water table ~10 feet bgs
----CP-1SB (8-9)Unsaturated soil sample, water table ~10 feet bgs
CP-1S 30 CP-1SB (25-26)Soil sample from shallow well screened interval
CP-1D 140 CP-1SB (135-136)Soil sample from deep well screened interval
----CP-2SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs
----CP-2SB (5-6)Unsaturated soil sample, water table ~10 feet bgs
----CP-2SB (8-9)Unsaturated soil sample, water table ~10 feet bgs
CP-2S 30 CP-2SB (27-28)Soil sample from shallow well screened interval
CP-2D 125 CP-2SB (122-123)Soil sample from deep well screened interval
----CP-3SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs
----CP-3SB (5-6)Unsaturated soil sample, water table ~10 feet bgs
----CP-3SB (8-9)Unsaturated soil sample, water table ~10 feet bgs
CP-3S 25 CP-3SB (22-23)Soil sample from shallow well screened interval
CP-3D 115 CP-3SB (112-113)Soil sample from deep well screened interval
----CP-4SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs
----CP-4SB (5-6)Unsaturated soil sample, water table ~10 feet bgs
----CP-4SB (8-9)Unsaturated soil sample, water table ~10 feet bgs
CP-4S 25 CP-4SB (22-23)Soil sample from shallow well screened interval
CP-4D 115 CP-4SB (112-113)Soil sample from deep well screened interval
----CP-5SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs
----CP-5SB (5-6)Unsaturated soil sample, water table ~10 feet bgs
----CP-5SB (8-9)Unsaturated soil sample, water table ~10 feet bgs
CP-5S 25 CP-5SB (22-23)Soil sample from shallow well screened interval
CP-5D 115 CP-5SB (112-113)Soil sample from deep well screened interval
----CP-6SB (2-3)Near-surface unsaturated soil sample, water table ~10 feet bgs
----CP-6SB (5-6)Unsaturated soil sample, water table ~10 feet bgs
----CP-6SB (8-9)Unsaturated soil sample, water table ~10 feet bgs
CP-6S 25 CP-6SB (22-23)Soil sample from shallow well screened interval
CP-6D 115 CP-6SB (112-113)Soil sample from deep well screened interval
Prepared by: LWD Checked by: CJS
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-4, GWA-5 and GWA-7 well clusters.
SynTerra recommends each well screen be submerged beneath the water table and have a length of at least 10 feet
SynTerra proposes soil samples be collected from well screen intervals for potential use in MNA analysis.
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.
TABLE 3
GROUNDWATER ANALYTICAL METHODS
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC, BELMONT, NC
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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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LAKE WYLIE
ALLEN STEAM STATION
COAL PILE
INACTIVE ASH BASIN
S-9
GWA-6S/D/DA/BR
GWA-7S/D
AB-33S/D
CP-6S/D
CP-5S/D
CP-4S/D
CP-3S/D
CP-2S/D
CP-1S/D
CCR-9S/D
CCR-8S/DCCR-7S/DCCR-6S/D
CCR-5S/D
CCR-4S/D
600
610
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0 5906
3
0
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570
660600600
57
0
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8
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610
580
590
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590
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610 6005906
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0
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9
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6405905905
8
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610FIGURE 1PROPOSED COAL PILE ASSESSMENT SAMPLE LOCATIONS
ALLEN STEAM STATION
DUKE ENERGY CAROLINAS, LLC
BELMONT, NORTH CAROLINADRAWN BY: A. FEIGLPROJECT MANAGER: C. SUTTELLCHECKED BY: L. DRAGO
DATE: 11/30/2017
148 RIVER STREET, SUITE 220GREENVILLE, SOUTH CAROLINA 29601PHONE [phone]www.synterracorp.com
P:\Duke Energy Progress.1026\00 GIS BASE DATA\Allen\Map_Docs\MISC\ALLEN_PropCoalPile_AssessmentWells.mxd
80 0 80 16040
GRAPHIC SCALE IN FEET
NOTES:
PROPOSED WELL AND BORING LOCATIONS ARE APPROXIMATEAND MAY BE ADJUSTED BASED ON ACCESSIBILITY AND FIELDCONDITIONS.
2014 AERIAL ORTHOPHOTOGRAPHY OBTAINED FROM WSP, APRIL2014.
DRAWING HAS BEEN SET WITH A PROJECTION OF NORTHCAROLINA STATE PLANE COORDINATE SYSTEM FIPS 3200(NAD83/2011).
LEGEND
&<PROPOSED COAL PILE ASSESSMENT SOILBORING AND MONITORING WELL
&<EXISTING CCR RULE MONITORING WELLLOCATION (APPROXIMATE)
&<EXISTING CAMA GROUNDWATERMONITORING WELL LOCATION
!(AOW AND SEDIMENT SAMPLE
APPROXIMATE EXTENT OF COAL PILESTORAGE AREA
WASTE BOUNDARY
DUKE ENERGY PLANT BOUNDARY
TOPOGRAPHIC CONTOURS (10' INTERVAL)
TOPOGRAPHIC CONTOURS (2' INTERVAL)