Allen Background Soil Dataset Evaluation - December 2016

F)2
Technical Memorandum
Date: Tuesday, December 13, 2016
Project: Allen Steam Station
To: Sean DeNeale
From: Chad Hearn
Subject: Quantification of Valid Background Soil Samples for Statistical Calculations
The purpose of this memorandum is to provide the basis for evaluation of soil samples proposed for use
in determining site-specific background concentrations using statistical methods. The soil samples
evaluated herein were principally collected during Comprehensive Site Assessment (CSA) fieldwork
conducted between February and June 2015. The locations of soil samples evaluated for use in
background statistical calculations are shown on Figure 1.
Viability of samples for use in statistical calculations 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.
These samples were collected from the following locations on-site: BG -1D located beyond the compliance
boundary southwest of the active ash basin; BG -2D located beyond the compliance boundary
west/northwest of the inactive ash basin; BG -3D 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-5D located east of the retired ash basin (RAB) ash landfill; GWA-6D located north of the RAB
ash landfill; and GWA-8D 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 per well are provided in Table 1. Note that laboratory reporting
limit 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.
Revised laboratory reports that will provide the non -detect values and method detection limits are in the
process of being obtained from the lab.

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NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. WASTE BOUNDARY IS APPROXIMATE.
3. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY.
4. SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.
5. DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.
6. BEDROCK MONITORING WELLS (BR) ARE SCREENED ACROSS A ROCK FRACTURE ZONE WITHIN COMPETENT BEDROCK.
7. ORTHOPHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.
8. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L.0107 (a).
9. HYDROGRAPHY WAS OBTAINED FROM USGS 7.5 -MINUTE SERIES TOPOGRAPHIC MAPS BELMONT, NC -SC, AND CHARLOTTE WEST, NC.
10. VOLUNTARY MONITORING WELL AB -8 WAS FOUND DAMAGED AND ABANDONED IN 2010.
SCALE (FEET)
200' 0 200' 400'
I" = 400'
A
4
L
LEGEND:
- -
DUKE ENERGY PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY
-..
AB -2
ASH BASIN COMPLIANCE BOUNDARY
AB -2D
DUKE PROPERTY BOUNDARY
STREAM
F
EXISTING ASH BASIN COMPLIANCE GROUNDWATER
MONITORING WELL
EXISTING ASH BASIN VOLUNTARY GROUNDWATER
MONITORING WELL
WAS X'"�G •;
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Y
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NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. WASTE BOUNDARY IS APPROXIMATE.
3. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY.
4. SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.
5. DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.
6. BEDROCK MONITORING WELLS (BR) ARE SCREENED ACROSS A ROCK FRACTURE ZONE WITHIN COMPETENT BEDROCK.
7. ORTHOPHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.
8. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L.0107 (a).
9. HYDROGRAPHY WAS OBTAINED FROM USGS 7.5 -MINUTE SERIES TOPOGRAPHIC MAPS BELMONT, NC -SC, AND CHARLOTTE WEST, NC.
10. VOLUNTARY MONITORING WELL AB -8 WAS FOUND DAMAGED AND ABANDONED IN 2010.
SCALE (FEET)
200' 0 200' 400'
I" = 400'
A
4
L
LEGEND:
- -
DUKE ENERGY PROPERTY BOUNDARY
ASH BASIN WASTE BOUNDARY
-..
LANDFILL/ASH STORAGE AREA BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
c
l�
DUKE PROPERTY BOUNDARY
STREAM
F
EXISTING ASH BASIN COMPLIANCE GROUNDWATER
MONITORING WELL
EXISTING ASH BASIN VOLUNTARY GROUNDWATER
MONITORING WELL
SOIL BORING/GROUNDWATER MONITORING WELL
LOCATION
p
SOIL BORING LOCATION
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Y
.., ,,: .. '�..,, .; -,.,, _ - - :q ♦� 1 '•.: {' ?�..;.r " � F `�'`. �. tia a-!.'. �.
NOTES:
1. PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE.
2. WASTE BOUNDARY IS APPROXIMATE.
3. AS -BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY.
4. SHALLOW MONITORING WELLS (S) ARE SCREENED ACROSS THE SURFICIAL WATER TABLE.
5. DEEP MONITORING WELLS (D) ARE SCREENED IN THE TRANSITION ZONE BETWEEN COMPETENT BEDROCK AND THE REGOLITH.
6. BEDROCK MONITORING WELLS (BR) ARE SCREENED ACROSS A ROCK FRACTURE ZONE WITHIN COMPETENT BEDROCK.
7. ORTHOPHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 2014.
8. THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCAC 02L.0107 (a).
9. HYDROGRAPHY WAS OBTAINED FROM USGS 7.5 -MINUTE SERIES TOPOGRAPHIC MAPS BELMONT, NC -SC, AND CHARLOTTE WEST, NC.
10. VOLUNTARY MONITORING WELL AB -8 WAS FOUND DAMAGED AND ABANDONED IN 2010.
SCALE (FEET)
200' 0 200' 400'
I" = 400'
A
4
L
MONITORING WELL AND SAMPLE LOCATIONS
DUKE ENERGY CAROLINAS, LLC
ALLEN STEAM STATION ASH BASIN
,:sTord couNrr, rineTH caeoLiri;
N
DATE
DECEMBER 2016
1=111:19
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
STREAM
EXISTING ASH BASIN COMPLIANCE GROUNDWATER
MONITORING WELL
EXISTING ASH BASIN VOLUNTARY GROUNDWATER
MONITORING WELL
SOIL BORING/GROUNDWATER MONITORING WELL
LOCATION
p
SOIL BORING LOCATION
MONITORING WELL AND SAMPLE LOCATIONS
DUKE ENERGY CAROLINAS, LLC
ALLEN STEAM STATION ASH BASIN
,:sTord couNrr, rineTH caeoLiri;
N
DATE
DECEMBER 2016
1=111:19

Table 1. 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
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
ltalic/undedlne- 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
m
Nickel
Selenium
Strontium
Thallium
Vanadium
Zinc
Calcium
Chloride
Magnesium
Nitrate
Potassium
Sodium
Sulfate
pH (field)
Total
Organic
Carbon
CAS RN
7429-90-5
7440-36-0
7440-38-2
7440-39-3
744041-7
7440-42-8
744043-9
7440-47-3
7440-48-4
7440-50-8
7439-89.6
7439-92-1
7439-96-5
7439-97-6
7439-98-7
7440-02-0
7782-49.2
7440-24-6
7440-28-0
7440-62-2
7440-66-6
7440-70-2
16887-00-6
7439-954
14797-55-8
7440-09-7
7440-23-5
14808-79-8
PH
TOC
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/k g
mg/kg
mg g
mg/kg
mg/kg
mgIkg
mglkg
mgIkg
mgIkg
mglkg
Std. Units
mglkg
NCDEQ PSRG Intl
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 -1D (1.0-2.0)
4/27/2015
55.83 - 58.68
15300
6.3 U
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
6.3 U
3.3
6.3 U
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
6.8 U
6.8 U
42.8
0.61
16.9 U
0.61 U
4.6
6.8 U
26.7
53600
7.1
293
0.016
3.4 U
1.7 U
6.8 U
3.4 U
6.8 U
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
6.2 U
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
6.2 U
3.1 U
6.2 U
68.1
13.2
155 U
304 U
903
30.4 U
752
310 U
304 U
5.3
475 J
BG -1 D (45-50)
5/1/2015
55.83 - 58.68
20100
7.6 U
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
7.6 U
10.1
7.6 U
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
627
0.026
4.4 U
2.2 U
6.5 U
3.9 J
8.7 U
81.6
64.4
127 J
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
6.4 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 U
5.5
6.4 U
49
59.4
195
315 U
8930
31.5 UJ
8720
322 U
315 U
5.4 J
744 U
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
1.8 U
5.3 U
16.7
7 U
77.5
64.3
1260
336 U
9490
33.6 UJ
7790
351 U
336 U
6J
415J
BG -3D (1-2.5)
2/23/2015
64.35 - 67.99
11800
1.4 U
3.4 UJ
229
0.85
17.2 U
0.111
30.9
19.8
31.2
24900
6.1
712
0.017
3.4 U
53.5
2.3 J
12
1.4 U
48.5
52.3
517
345 U
4780
34.5 UJ
3370
344 U
345 U
5.1 J
521 J
BG -3D (13.5-15)
2/23/2015
64.35 - 67.99
8570 1
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
3U
1.5
1.2 U
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
1.2 U
15.3
16.8
773
291 U
1160
29.1 UJ
1110
59.5 U
291 U
6.9 J
3470
GWA-513 (2.0-4.0)
5/14/2015
11.00 - 17.12
17900
6.2 U
6.2 U
143
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 U
70.8
39.9
859
292 U
5350
29.2 UJ
4300
309 U
489
5.7 J
1090
GWA-8D (38.5-40)
2/18/2015
6.04-66.77
12100 J+
1.5 U
3.7 U
13641.3
0.18 U
47.3
32.6
59.5
44300 J+
3.3
1190
0.01 U
0.75 U
20.8
3.7 U
7.5 U
1.5 U
90
23.2
373 U
372 U
3090
37.2 UJ
2150
746 U
372 U
8.2
892 U
GWA-8D (48.5-50)
2/18/2015
6.04-66.77
17200 J+
1.5 U
3.6 U
211
42.5
0.18 U
48.8
39.8
53.8
43000 J+
4.8
1280
0.01 U
7.3 U
50.6
3.6 U
7.3 U
1.5 U
89.9
72.3
365 U
375 U
6490
37.5 UJ
4440
730 U
375 U
5.9
901 U
GWA-14D (10.0-12.0)
6/9/2015
23.73 - 30.84
11200
9.2 U
9.2 U
84.3
g6U
23.1 U
1.1 U
4.9
5.7 J
30.3
34700
5.8 J
501
0:014 UGWA-15D
(1.9-2.0)
6/8/2015
4.64-9.98
8260
7.2 U
7.2 U
55.9
18 U
0.86 U
10.1
3.8 J
11.6
22400
14.8Total
Number of Viable Soil Samples »
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
15
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
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
ltalic/undedlne- 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.