Allen Soil Background Tech Memo_REV1_20170526

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Technical Memorandum
Date: Friday, May 26, 2017
Project: Allen Steam Station
To: Sean DeNeale
From: Chad Hearn
Subject: Quantification of Valid Background Soil Samples for Statistical Calculations — Revision 1
The purpose of this revised technical memorandum (TM) is to address the North Carolina Department of
Environmental Quality's (NCDEQ's) requirement identified below. In addition, this revised TM provides the
basis for evaluation of soil samples proposed for use in determining site-specific background
concentrations using statistical methods for the Allen Steam Station (Allen) as originally presented in the
TM dated December 20, 2016.
Following submittal of the TM dated December 20, 2016, Duke Energy submitted the Statistical Methods
for Developing Reference Background Concentrations for Groundwater and Soil at Coal Ash Facilities
(Background Methodology) to NCDEQ on January 20, 2017. NCDEQ subsequently requested additional
information regarding the Background Methodology via a letter dated April 28, 2017. As part of the April
28, 2017 letter, NCDEQ requested the following information:
Provide up-to-date digital spreadsheets of raw background soil data for each facility by May 26,
2017. Any soil data collected since submittal of the Comprehensive Site Assessments (CSAs)
should be included in the table and existing soil data should be reviewed to identify any quality
control issues (i.e., sampling intervals, corresponding boring sample ID, etc.) along with
identification of outliers and revised accordingly.
The up-to-date raw background soil data for background determinations at Allen are provided in Table 1
of this revised TM. Note the remainder of the requirements in the April 28, 2017 NCDEQ letter are
addressed in a revision to the Background Methodology under separate cover.
The soil samples evaluated herein were principally collected during CSA fieldwork conducted between
February and June 2015. The locations of soil samples to be evaluated for use in the background
determinations are shown on Figure 1.
Viability of samples for use in developing background concentrations was evaluated using the following
criteria:
• Soil sample is collected from a location that is not impacted by coal combustion residuals or coal -
associated materials;
• Soil sample is collected from a location that is not impacted by other potential anthropogenic
sources of constituents;
• Soil sample is collected from the unsaturated zone, above the maximum groundwater elevation
measured in shallow wells between September 2015 and September 2016; and
• Soil sample collected from a location not impacted by periodic flooding.
A total of 64 soil samples were collected at Allen during CSA activities. Of these 64 samples, 16 samples
satisfy the four criteria listed above and are considered viable samples for use in statistical calculations.

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These samples were collected from the following locations on-site: BG -1 D located beyond the compliance
boundary southwest of the active ash basin; BG -21D located beyond the compliance boundary
west/northwest of the inactive ash basin; BG -31D located beyond the compliance boundary northwest of
the station discharge canal; GWA-1 D located near the compliance boundary southeast of the active ash
basin; GWA-51D located east of the retired ash basin (RAB) ash landfill; GWA-61D located north of the RAB
ash landfill; and GWA-81D located near the compliance boundary north of the inactive ash basin. Note that
viable samples collected from borings near the waste boundary or down -gradient of ash management
areas were collected a minimum of one foot above the maximum measured groundwater elevation and
are assumed to have not been impacted by groundwater migrating from ash sources.
Soil sampling data used in this evaluation, including the range of groundwater elevations for shallow wells
in each well cluster and analytical results of soil samples are provided in Table 1. Note that laboratory
reporting limits for antimony, arsenic, cobalt (one sample), selenium, and thallium exceeded the North
Carolina Protection of Groundwater (POG) Preliminary Soil Remediation Goals, as revised in October
2016.

Z I
n
N
AL U.)
I
BG -3S \1
I BG -3D
If
it Q\SC�P� I GWA-17D
II I /I AB -1R
II- BG -25 f e II
I BG -2D
I BG-2BR
/ G �
I� I
/ GWA-16D
DUKE ENERGY PROPERTY GWA-16S
N
u
/ / z
r / GWA-19D
\ / GWA-19S
RIVER RUN
GWA-15S
GWA-15D
BG -4S
BG -4D
BG-4BR
GWA-18D
GWA-18S
INACTIVE AB -38S
ASH BASIN AB -38D
AB-38BR V
INACTIVE
ASH BASIN
AB -37S
4AB-37D OAB-36S
AB-14BR
5: AB -14D
WARREN DRIVE
4 m SOUTHPOINT DRIVE
to GWA-14S
yFgT GWA-14D
m
yF� m
GLEN LN
x
Ab
•j�r ,�y�l
ARMSTRONG RD
HIGHLAND WP.Y
,+
GWA-24S
GWA-24 D
GWA-24BR
GWA-21S
GWA-21D
GWA-21BR o
r
O
O
0
D
z
rn
GWA-9S
GWA-9D
GWA-9BR
M DWOOD ROAD
WILDLIFE ROAD
AB -4D
AB -4S
AB-4BR
AB -20S
AB -20D
AB -2
AB -26
DISCHARGE C4/VAI
ANSWO16
GWA-8S
GWA-8D
PLANT ALLEN RD
A ASH
SH
STORAGE
A
-396
SB -5
SB -2,--1 SB -4
ASH
STORAGE
SB -1
GWA-22S
GWA-22D
PRIMARY
AB -13S POND 1
AB -13D
SB -7
reum,I"MellM
ANWWO01
GWA-7Do
GWA-7S
ALLEN STEAM
STATION
GWA-6D* GWA-6BR
{ GWA-6S
GWA-6DA
1
I
I
1
C
�. •SW -6
ANWWO04
AB -34D
DISCHARGE TOWER
AB -34S
TRUCTURAL
TRUCTURA
FILL
FILL
S-9
AB-25BR
AB -3355
AB 33D
AB -35D
SB -6
AB-35BR
AB -33S
ANFDO01
GWA-22S
GWA-22D
PRIMARY
AB -13S POND 1
AB -13D
SB -7
reum,I"MellM
ANWWO01
GWA-7Do
GWA-7S
ALLEN STEAM
STATION
GWA-6D* GWA-6BR
{ GWA-6S
GWA-6DA
1
I
I
1
C
�. •SW -6
ANWWO04
AB -24S
y AB-24SL
AB -24D
AB-24BR
GWA-23S AB 23S
GWA 23D AB-23BRU
CIF WELL
SB -8
AB -21S
AB-21BRLAB-21SL
>AB -21D
AB-21BR
AB -25S
WELL ID
DISCHARGE TOWER
ANTD001
AB -26D
GWA-3BR
AB-25BRU
AB -26S
S-9
AB-25BR
AB 33D
SB -9
ANSP005
AB -33S
S-8
ANSP003 S-2 I
I
S-7
Lu
Y
•`
AB -32D
0
GWA 5S
GWA 5D
GWA-26S
AB 32S
6
ACTIVE ASH
GWA-56R
-*\S-5
BASIN
RETIRED ASH BASIN
GWA-1D,,-&,
/
/
=
I
GWA-IBR
ASH LANDFILL
AB-22BR ANSP001
AB -10D
z
AB -22D h
\
S-4 -Q' 5
PERMIT NO. 3612
AB -22S
/
ANSP002 S-3
o
BG -1D O
AB -31S
AB-31Dr!
I
IGWA-4BR
GWA-41)
GWA-4S
SAB 11D
\
�t
R
S-1
LANDFILL EDGE OF WASTE
NUTALL OAK LN
AB -29S
AB -30S
'O�
AB-29SL
AB -9D
AB -30D
AB -29D
NORTH DIKE
AB 27BR
•ANSWO15
AB -27D
SW -7
AB 28 S Q
AB -27S
AB -28S
LAKE WYLIE
sW-40
(CATAWBA RIVER)
SW -3
• PRIMARY
PRIMARY
POND 3
POND 2
AB -24S
y AB-24SL
AB -24D
AB-24BR
GWA-23S AB 23S
GWA 23D AB-23BRU
CIF WELL
SB -8
AB -21S
AB-21BRLAB-21SL
>AB -21D
AB-21BR
AB -25S
WELL ID
DISCHARGE TOWER
AB-25SL
AB -26D
GWA-3BR
AB-25BRU
AB -26S
GWA-3D
AB-25BR
GWA-3S
SB -9
ANSP005
S-8
ANSP003 S-2 I
I
S-7
Lu
Y
•`
0
GWA-2D
GWA-26S
Lu
6
ACTIVE ASH
GWA-1S
-*\S-5
BASIN
SW -2 •
GWA-1D,,-&,
/
/
=
\
GWA-IBR
AB -10S\
AB-22BR ANSP001
AB -10D
z
AB -22D h
\
S-4 -Q' 5
AB -22S
/
ANSP002 S-3
o
BG -1D O
ABBIR
AB 6A
WOODBEND DR
WELL ID
DISCHARGE TOWER
�ANWW002
\
fF
529039.97
1399093.63
SW -1 •
AB -12S
AB -12D
PH WELL
ANSP003 S-2 I
OAB-5
'
GWA-2D
GWA-26S
GWA-2S
NO
GWA-26D
GWA-1S
c
GWA-1D,,-&,
/
/
=
GWA-IBR
O
z
i
E'Ak
BG-1S
o
BG -1D O
�\\SOLAR
SAB 11D
\
�t
R
S-1
NUTALL OAK LN
NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. WASTE BOUNDARY IS APPROXIMATE.
3. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L.0107 (a).
4. EXISTING MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY AND WSP.
5. EXISTING SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.
6. EXISTING DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.
7. EXISTING BEDROCK MONITORING WELLS (BR) ARE SCREENED ACROSS WATER BEARING FRACTURES IN COMPETENT BEDROCK.
8. TOPOGRAPHY DATA FOR ONSITE WAS OBTAINED FROM WSP (DATED 2015).
9. TOPOGRAPHY DATA FOR OFFSITE WAS OBTAINED FROM NCDOT GEOGRAPHIC INFORMATION SYSTEM (GIS) WEB SITE (DATED 2007).
10. AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.
SCALE (FEET)
250' 0 250' 500'
I" = 500'
1
ABANDONED WELLS
WELL ID
NORTHING
EASTING
GWA-6D
529039.97
1399093.63
* DENOTES THAT WELL HAS BEEN ABANDONED
•
•
LEGEND:
DUKE ENERGY PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY
LANDFILL/ASH STORAGE AREA BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY COINCIDENT WITH
DUKE PROPERTY BOUNDARY
ASH BASIN COMPLIANCE
GROUNDWATER MONITORING WELL
ASH BASIN VOLUNTARY
GROUNDWATER MONITORING WELL
CSA GROUNDWATER MONITORING WELL
POST -CSA ADDITIONAL ASSESSMENT GROUNDWATER
MONITORING WELL
ABANDONED MONITORING WELL
ONSITE WATER SUPPLY WELL (NON POTABLE)
CSA SOIL BORING LOCATION (2015)
SURFACE WATER SAMPLE LOCATION
AREA OF WETNESS SAMPLE LOCATION
NCDENR SAMPLE LOCATION
SAMPLE LOCATION MAP DATE
CAMA AND NPDES PROGRAMS MAY 2017
DUKE ENERGY CAROLINAS, LLC
ALLEN STEAM STATION ASH BASIN FIGURE
cASroN roUrar. NORTH c;aRouN= �
N

Table 1. Allen Steam Station Background Soil Analytical Results
General Notes:
Depth -to -Groundwater data was collected in: 6/15, 9/15, 11/15, 12/15, 3/16, 5/16, and 9/16 (month/year)
"Strike-throughs" indicate samples that are not included in the viable sample count due to the method detection limit (MDL) for the non -detect result being greater than the North Carolina Protection of Groundwater (POG) Preliminary Soil Remediation Goal (PSRG) for that constituent.
mg/kg - milligrams per kilogram
NA - Not analyzed or not reported by analytical laboratory
Std. Units - pH units
Comparison Criteria:
NS - No applicable standard for this parameter
Shading indicates exceedance of either applicable criteria.
bold - indicates exceedance of NCDEQ Industrial
Health Based PSRG
Italic/underins- indicates exceedance of NCDEQ
Protection of Groundwater PSRG
North Carolina Department of Environmental Quality Division of Waste Management Soil
Remediation Goals Table (October 2016) - Preliminary Industrial Health Based Soil
Remediation Goal (PSRG) and Protection of Groundwater PSRG.
"'Note: No PSRG for Total Chromium is currently available, as a surrogate the PSRG for
Trivalent Chromium was used for comparison purposes only.
Qualifier Notes:
U -- Not detected above the reporting detection limit.
J -- Estimated concentration
J+- Estimated concentration, biased high.
J ---Estimated concentration, biased low.
Analyte
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Chromium
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Molybdenum
Nickel
Selenium
Strontium
Thallium
Vanadium
Zinc
Calcium
Chloride
Magnesium
Nitrate
Potassium
Sodium
Sulfate
pH (field)
Total
Organic
Carbon
Result Unit
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
Slid. Units
mg/kg
NCDEQ PSRG Ind
100000
94
3
44000
460
46000
200
100000
70
9400
100000
800
5200
8
1200
4400
1200
100000
2.4
1200
70000
NS
NS
NS
100000
NS
NS
NS
NS
NS
NCDEQ PSRG POG
NS
0.9
5.8
580
63
45
3
360000
0.9
700
150
270
65
1
NS
130
2.1
NS
0.28
6
1200
NS
NS
NS
NS
NS
NS
NS
NS
NS
Sample Name
Sample Date
Range of Depth -to -Water (ft)
BG -1 D (1.0-2.0)
4/27/2015
55.83 - 58.68
15300
6311
6.3 U
20.5
0.32 U
15.8 U
0.76 U
15.2
13.3
8.1
35100
10.9
340
0.074
3.2 U
2.2
6211
3.3
6311
78.1
10.1
462
305 U
297
30.5 U
162 J
316 U
305 U
5.8
2750
BG -1 D (9.0-10.5)
4/27/2015
55.83 - 58.68
6450
6311
6.8 U
42.8
0.61
16.9 U
0.81 U
4.6
6-"
26.7
53600
7.1
293
0.016
3.4 U
1.7 U
6-"
3.4 U
6.311
143
14.7
169 U
357 U
433
35.7 U
339 U
339 U
357 U
5.5
798 J
BG -1D (19.0-20.5)
4/28/2015
55.83 - 58.68
4990
6211
6.2 U
46.2
0.36
15.5 U
0.74 U
14.7
14.5
11.9
27600
7.6
436
0.0094 U
3.1 U
1.8
6-,U
3.1 U
6211
68.1
13.2
155 U
304 U
903
30.4 U
752
310 U
304 U
5.3
475J
BG -1D (45-50)
5/1/2015
55.83 - 58.68
20100
7-"
7.6 U
203
0.91
23.4 J+
0.92 U
6.2
18.7
29
33600
6.9 J
1060
0.011 U
3.8 U
5.3
7611
10.1
7611
79.3
88.2
245
363 U
10000
36.3 UJ
10100
384 U
363 U
5.7 J
878 U
BG -2D (1.0-2.5)
5/14/2015
51.40 - 54.60
29200
8.7-U
8.7 U
216
0.38 J
21.8 U
1 U
6.7
5.6 J
34.3
51300
6.3 J
fi27
0.026
4.4 U
2.2 U
6.5-U
3.9 J
8.Z -U
81.6
64.4
127J
423 U
10400
42.3 UJ
9740
436 U
423 U
51
826 J
BG -2D (8.5-10.0)
5/14/2015
51.40 - 54.60
17800
64-U
6.4 U
208
0.35
16.1 U
0.77 U
3.1
9.7
3.2
23100
3.6 J
587
0.0082 J
3.2 U
1.4 J
4:8-4
5.5
6..4
49
59.4
195
315 U
8930
31.5 UJ
8720
322 U
315 U
5.4 J
744U
BG -2D (18.0-20,0)
5/14/2015
51.40 - 54.60
15500
7-U
7 U
233
0.95
17.6 U
0.84 U
2.7
19.4
55.7
32400
3.9 J
1340
0.011 U
3.5 U
IS U
6.3-4
16.7
74
77.5
64.3
1260
336 U
9490
33.6 UJ
7790
351 U
336U
6 J
415 J
BG -3D (1-2.5)
2/23/2015
64.35 - 67.99
11800
IA U
3.4 UJ
229
0.85
17.2 U
0.11 J
30.9
19.8
31.2
24900
6.1
712
0.017
3.4 U
53.5
12
4A -U
48.5
52.3
517
345 U
4780
34.5 UJ
3370
344 U
345 U
5.11
521 J
BG -3D (13.5-15)
2/23/2015
64.35 - 67.99
8570
1.2 U
3 U
109
0.36 UJ
3 U
0.35
1.7
28.5
10.3
13600
31.6
962
0.0071 J
0.6 U
2.1
3 U
1.5
4.211
40.9
36.4
59.8
311 U
4890
31.1 UJ
5220
33.3 J
311 U
5.4 J
488J
BG -3D (18.5-20)
2/23/2015
64.35 - 67.99
2500
1.2 U
1.2 U
26.3
0.071 J
3 U
0.14 U
7.6
3_9
18.2
6400
1.7
172
0.01 U
0.69
0.78
1.2 U
1.3
4-211
15.3
16.8
773
291 U
1160
29.1 UJ
1110
59.5 U
291 U
6.9 J
3470
GWA-14D (10.0-12.0)
6/9/2015
23.73 - 30.84
11200
&:2{4
9.2 U
84.3
0.46 U
23.1 U
1.1 U
4.9
5-7J
30.3
34700
5.8 J
501
0.014 U
4.6 U
5.1
9-2-4
4.6 U
9.211
89.8
23.9
231 U
437 U
2680
43.7 U
2430
461 U
437 U
5.1
1060 J
GWA-15D (1.9-2.0)
6/8/2015
4.64-9.98
8260
7244
7.2 U
55.9
0.36 U
18 U
0.86 U
10.1
3.8 J
11.6
22400
14.8
302
0.082
3.6 U
3.6
7211
6.2
7241
57.4
21.3
1250
374 U
762
37.4 U
416
360 U
374 U
7
4020
GWA-5D (2.0-4.0)
5/14/2015
11.00 - 17.12
17900
6.311
6.2 U
143
0.75
15.5 U
0.74 U
9.5
16.2
19.2
24200
5.4 J
578
0.016
3.1 U
6.2
2.5 J
7
6.2-4
70.8
39.9
859
292 U
5350
29.2 UJ
4300
309 U
489
5.7 J
1090
GWA-BD (38.5-40)
2/18/2015
6.04 - 66.77
12100 J+
t.5 U
3.7 U
136
1.3
41.3
0.18 U
47.3
32.6
59.5
74t!!J+
3.3
1190
0.01 U
0.75 U
20.8
3-7-U
7.5 U
3.511
90
23.2
373 U
372 U
3090
37.2 UJ
2150
746 U
372 U
6.2
892 U
GWA-8D (48.5-50)
2/18/2015
6.04 - 66.77
17200 J+
1.5 U
3.6 U
211
1.5
42.5
0.18 U
48.8
39.8
53.8
43000 J+
4.8
1280
0.01 U
7.3 U
50.6
3§U
7.3 U
4:"
89.9
72.3
365 U
375 U
6490
37.5 UJ
4440
730 U
375 U
5.9
901 U
Total Number of Viable Soil Samples »
15
15
5
15
15
15
15
15
15
14
15
15
15
15
15
15
15
4
15
0
15
15
15
15
15
15
15
15
15
15
15
General Notes:
Depth -to -Groundwater data was collected in: 6/15, 9/15, 11/15, 12/15, 3/16, 5/16, and 9/16 (month/year)
"Strike-throughs" indicate samples that are not included in the viable sample count due to the method detection limit (MDL) for the non -detect result being greater than the North Carolina Protection of Groundwater (POG) Preliminary Soil Remediation Goal (PSRG) for that constituent.
mg/kg - milligrams per kilogram
NA - Not analyzed or not reported by analytical laboratory
Std. Units - pH units
Comparison Criteria:
NS - No applicable standard for this parameter
Shading indicates exceedance of either applicable criteria.
bold - indicates exceedance of NCDEQ Industrial
Health Based PSRG
Italic/underins- indicates exceedance of NCDEQ
Protection of Groundwater PSRG
North Carolina Department of Environmental Quality Division of Waste Management Soil
Remediation Goals Table (October 2016) - Preliminary Industrial Health Based Soil
Remediation Goal (PSRG) and Protection of Groundwater PSRG.
"'Note: No PSRG for Total Chromium is currently available, as a surrogate the PSRG for
Trivalent Chromium was used for comparison purposes only.
Qualifier Notes:
U -- Not detected above the reporting detection limit.
J -- Estimated concentration
J+- Estimated concentration, biased high.
J ---Estimated concentration, biased low.