Revised Background GW Tech Memo_20170922

TECHNICAL MEMORANDUM
Date: September 22, 2017 File: 1026.19
To: Melonie Martin (Duke Energy)
Cc: Kathy Webb ( Terra) �'%
From: Jerry Wyli & Ted Volsskay SynTerra)
Subject: Revised Background Threshold Values for Groundwater
Dan River Steam Station — Eden, NC
The North Carolina Department of Environmental Quality (NCDEQ) provided a response letter
to Duke Energy (Zimmerman to Draovitch, July 7, 2017) requiring background constituent
concentrations (referred to herein as background threshold values [BTVs]) in groundwater and
soil at each Duke Energy coal ash facility be determined and submitted within 60 days from
receipt of the letter for facilities submitting Comprehensive Site Assessments (CSAs) later than
October 31, 2017. NCDEQ also provided within the response letter groundwater and soil data
appropriate for use in the statistical determination of BTVs for the each facility. BTVs in
addition to revised background groundwater and soil datasets for each coal ash facility were
subsequently submitted to NCDEQ on September 5, 2017. On September 11, 2017, NCDEQ
provided an email response to Duke Energy (Wang to Toepfer) requesting Duke Energy
resubmit revised groundwater BTVs for the Dan River Steam Station (Dan River) incorporating
additional background well data.
The initial groundwater BTVs for Dan River submitted to NCDEQ were determined using data
obtained from background wells BG -5S, BG -5D, MW -23D and MW-23BR. Monitoring wells
BG -10S, BG -10D, BG-10BR, GWA-9S and GWA-9D were only conditionally approved for use in
the determination of BTVs and were therefore not included in the initial determination of BTVs.
NCDEQ requested that BTVs be revised for groundwater using data from background wells
BG -10S, BG -10D, BG-10BR, GWA-9S, and GWA-9D in addition to the data used for the initial
BTV determinations.
GROUNDWATER BACKGROUND DATASETS
The current background monitoring well network consists of wells installed within three flow
zones — shallow, deep, and bedrock. Monitoring well locations are presented in Figure 1. An
updated background groundwater dataset including sample results obtained through third
quarter 2017 is provided in Table 1. The updated background dataset has been screened for
statistical outliers and invalid sample results. Statistical outliers and invalid sample results are
identified in Table 1.
P: \ Duke Energy Carolinas \ Statistics_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO \ Dan River \ Groundwater \ Revised Memo \ Dan River - Background GW Tech Memo.docx

Background Threshold Values for Groundwater September 22, 2017
Dan River Steam Station Page 2 of 3
The updated datasets for the shallow and deep flow zones meet the minimum requirement of
10 valid samples for all constituents except total organic carbon (TOC). The updated
background bedrock dataset meets the minimum requirement of 10 valid samples for all
constituents except chromium (VI), methane, radium (total), TOC, and uranium (total). With
the exception of constituent datasets containing less than 10 valid samples, BTVs were
calculated for constituents using formal UTL statistics. For constituent datasets containing less
than 10 valid samples, the provisional background threshold value (PBTV) was calculated to be
either the maximum value, or, if the maximum value was above an order of magnitude greater
than the geometric mean of all values, the second highest value. BTVs for each flow zone are
presented in Table 2.
All statistical tests were performed in accordance the the revised Statistical Methods for
Developing Reference Background Concentrations for Groundwater and Soil at Coal Ash Facilities
(statistical methods document) (HDR Engineering, Inc. and SynTerra Corporation, May 2017).
Microsoft Excel spreadsheets tabulating statistical results and documenting ProUCL outputs are
provided as a separate submittal.
LIST OF FIGURES:
Figure 1 Background Groundwater Monitoring Well Location Map
LIST OF TABLES:
Table 1 Background Groundwater Results through August 2017
Table 2 Revised Background Groundwater Threshold Values
P: \ Duke Energy Carolinas \ Statistics_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO \Dan River \ Groundwater \ Revised Memo \Dan River - Background GW Tech Memo.docx

Background Threshold Values for Groundwater September 22, 2017
Dan River Steam Station
FIGURE
P: \ Duke Energy Carolinas \ Statistics_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO\Dan River\ Groundwater\ Revised Memo\Dan River -Background GW Tech Memo.docx

Y
E ,(
• + 't
PIP
� , r
ti
i
1 � °
i
ww
NOTES:
REFERENCED BOUNDARIES AND WELL LOCATIONS ARE
APPROXIMATE.
AERIAL PHOTOGRAPHY OBTAINED FROM USDA FSA NAIP ON JULY
21, 2017 VIA ESRI MAP SERVER, DATED 5/25/2016.
DRAWING HAS BEEN SET WITH A PROJECTION OF NORTH
CAROLINA STATE PLANE COORDINATE SYSTEM FIPS 3200
(NAD83/2011).
w
.8S
�8 D
�8BR �
IW -317B
-W°AS-8 D]"
AS -813R
FA
;GWA=7S } ;1
GWA-7D MW
MW=20S GWA-18
MW-T20D
12 GWA-1S
GWA-1 D
`2D
A6 -5S
T I'�•
11S
11D f.......... A
j MW.' -22D
MW=22BR
GWA-20S
GWA-20 D
GRAPHIC SCALE
300 150 0 300 600
IN FEET
148 RIVER STREET, SUITE 220
GREENVILLE, SOUTH CAROLINA 29601
PHONE [phone]
Terra
n
cJ.
DRAWN BY: A. FEIGL DATE: 08/15/2017
PROD
PROJECT MANAGER: J. MAHAN
MANAGER:
CHECKED BY: B. WYLIE
LEGEND
BACKGROUND MONITORING WELL
O LOCATIONS - ACCEPTED BY NCDEQ -
JULY 7, 2017
BACKGROUND MONITORING WELL
Q LOCATIONS - CONDITIONAL ACCEPTED
BY NCDEQ - JULY 7, 2017
MONITORING WELL LOCATION
WASTE BOUNDARY
�••� COMPLIANCE BOUNDARY
••— DUKE ENERGY DAN RIVER PLANT
BOUNDARY
FIGURE 1
BACKGROUND GROUNDWATER
SAMPLE LOCATION
DAN RIVER STEAM STATION
EDEN, NORTH CAROLINA

Background Threshold Values for Groundwater September 22, 2017
Dan River Steam Station
TABLES
P: \ Duke Energy Carolinas \ Statistics_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO \Dan River \ Groundwater \ Revised Memo \Dan River - Background GW Tech Memo.docx

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH AUGUST 2017
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, DAN RIVER, NC
Analytical Parameter pH Turbidity Alkalinity Aluminum Antimony Arsenic Barium Beryllium Bicarbonate Boron Cadmium Calcium Carbonate Chloride Chromium Chromium (VI) Cobalt Copper Iron Lead Magnesium
15A NCAC 02L Standard 6.5-8.5 NE NE NE 1 10 700 4 NE 700 2 NE NE 250000 10 0.07 1 1000 300 15 NE
Reporting Unit SU NTU ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L ug/L
Well ID Sample Collection Date Field Parameters Analytical Results
Shallow
86-5S
6/24/2^1s
6-.44
5.23
77689
599
5
9 8 j
24
&$87 j
77688
<§0
3 8a
F5880
6989
2-.-6
-
2-1-
2-1F
898
4-.-7
i §()()
BG SS9/g/,finiis
6-.2
S
88800
2�9
E$59
9 29 j
2-2
E$2
80809
ESO
E0.98
2i$(A)
<5090
62-99
0.89
-
9.i
9.45 j
i#$9
0 69
14899
BG SS
++ 16 ,i ) cer
6-2
387
75i$9
338
X0.5
<0.5
3�
E$2-
75i$9
<-50
<0.08
i7600
<S900
6$88
4-}+
0.35
E$r
-<-1-
4-49
844
ii499
BG -5S
12/15/2015
6.06
2.95
70600
<100
<0.5
<0.5
11
<0.2
70600
<50
<0.08
17200
<5000
6900
0.73 j+
0.41
<0.5
<1
27 j
9.()§j
11300
BG -5S
3/28/2016
6.4
2.07
73600
118
<0.5
<0.1
18.7
<0.1
73600
<50
<0.08
16800
<5000
6700
0.81 j+
0.45
0.037j
0.17j
83.2
<0.1
11400
BG -5S
6/21/2016
5.9
1.2
77900
69.9 j
<0.5
0.05 j
11.8
0.038 j
77900
<50
<0.08
19200
<5000
6500
0.54
0.48
<0.1
0.13 j
29.8 j
<0.1
12200
BG -5S
9/28/2016
5.9
4.3
77000
75.1 j+
0.2 j+
<0.1
11.7
0.07 j+
77000
<50
<0.08
19500
<5000
7300
0.77 j+
0.38 j+
0.051]
0.59 j+
79.2
<0.1
12500
BG -5S
12/15/2016
6
1.3
77700
88.5j
<0.5
<0.1
12.5
0.024j
77700
<50
<0.08
19400
<5000
7200
<0.5
0.58
<0.1
<0.5
61.7
<0.1
11300
BG -5S
2/22/2017
6
2
73100
83.9 j
<0.5
<0.1
12.3
0.014 j
73100
<50
<0.08
17100
---
7100
0.8
0.46
0.05 j
0.14 j
110
<0.1
11000
BG -5S
5/8/2017
5.6
1.9
70100
<100
<0.50
<0.10
10.5
0.038 j
70100
<50.0
<0.080
16600
<5000
7100
0.70 j+
0.5
0.047 j+
0.50 j
42.9 j
0.098 j
10300
BG -5S
8/24/2017
6.0
2.9
75600
<100
<0.5
0.041j
10.9
0.016j
75600
<50
<0.08
17500
<5000
7600
0.62
0.48
0.034j
0.24j
<50
<0.1
11200
<50
<0.08
28500
Ago
5800
0.22 j
0.07
0.03 j
0.89
83
<0.1
16100
BG -5D
9/28/2016
6.4
3.7
BG -10S
8/11/2017
4.6
9.6
12600
140
0.19j
0.15
3.2j
0.074]
12600
<50
<0.08
3540
<5000
6500
3:3
<0.1
0.22
1.9
152
0.13
1920
GWA 9S
9 /nom
�. l
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<O.5
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33
0�3
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11/16/2015
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835 j
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218
0.39
7-53
GWA-9S
12/15/2015
5.3
8.2
7800
380
<0.5
<0.5
14
0.19 J
7800
<50
0.037 j
1130
<5000
4200
0.58 j+
0.0271
6 5
1.8
378
9.25
896
GWA-9S
3/28/2016
5.7
6.14
12300
96.9j
<0.5
<0.1
8.7
0.098j
12300
<50
<0.08
1050
<5000
4300
0.33 j+
0.077
3.3
0.89
111
0.09j
537
GWA-9S
6/17/2016
5.1
2.5
6800
<100
<0.5
<0.1
7.8
0.13
6800
<50
<0.08
468
<5000
3800
0.9
0.14 j
2.4
0.84
34.5 j
<0.1
458
GWA-9S
9/28/2016
5.3
8.47
6800
69.8 j+
0.15 j+
<0.1
8.6
0.16 j+
6800
<50
<0.08
360
<5000
4400
1.1 j+
0.17
1.3
0.95 j+
66.2
<0.1
445
GWA-9S
12/15/2016
5.2
4
6200
<100
<0.5
<0.1
9.1
0.018 j
6200
<50
<0.08
342
<5000
4200
0.13 j
0.24
<0.1
0.3 j
<50
<0.1
410
GWA-9S
2/22/2017
5.2
1.7
6600
<100
<0.5
<0.1
8.5
0.19
6600
<50
<0.08
311
---
4300
0.69
0.18
1.1
0.6
<50
<0.1
400
GWA-9S
5/8/2017
4.5
1.4
6400
<100
<0.50
<0.10
9.3
0.2
6400
<50.0
<0.080
560
<5000
4300
0.22 j+
0.11 j+
2
0.73
32.83
<0.10
608
GWA-9S
8/24/2017
5.2
1.9
6000
<100
<0.5
0.042j
7.8
0.19
6000
<50
0.057j
302
<5000
4500
0.46j
0.26
0.91
0.6
61.9
<0.1
418
Deep
..
IF
IF
ILV
BG 5D
6 /23 /lei C
133900
-
4-
240
17409
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19/ I11C
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7490
9.47
9.41j
9.36j
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6909
9.48 j t
0.024 +
E-0.5
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84
9 j
44909
BG -5D
12/15/2015
6.57
1.75
125000
<100
<0.5
<0.5
16
<0.2
125000
<50
<0.08
28300
<5000
6000
0.18 j+
0.03 j
<0.5
<1
<50
^. 9551
15900
BG -5D
3/28/2016
6.6
0.35
116000
<100
<0.5
<0.1
16.5
<0.1
116000
<50
<0.08
25000
<5000
---
0.81 j+
---
0.031 j
<0.5
<50
<0.1
14700
$6-58
4/4/2016
8-.5
257
-
-
-
-
-
-
-
-
-
-
-
6290
-
0.-072
-
-
-
-
-
BG -51D
6/21/2016
6.5
3.2
117000
77.5 j
<0.5
0.052 j
16.9
0.028 j
117000
<50
<0.08
28500
<5000
5800
0.22 j
0.07
0.03 j
0.89
83
<0.1
16100
BG -5D
9/28/2016
6.4
3.7
120000
<100
<0.5
<0.1
17.1
0.01 j+
120000
<50
<0.08
29400
<5000
6500
0.45 j+
0.1 j+
0.032 j
<0.5
71.8
<0.1
15500
P:\Duke Energy Carol i nas\Statisti cs_CAMA\Backg round Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Dan River\Groundwater\Revised Memo\Tables\TABLE 1 - Dan River -All BG GW Data -Updated Page 1 of 6

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH AUGUST 2017
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, DAN RIVER, NC
Manganese
Analytical Parameter
Mercury
Methane
Molybdenum
Nickel
Nitrate + Nitrite
Potassium
Selenium
Sodium
Strontium
Sulfate
Sulfide
Thallium
Total Dissolved Solids
Total Organic Carbon
Total Suspended Solids
Vanadium
Zinc
Radium (Total)
Uranium (Total)
50
15A NCAC 02L Standard
1
NE
NE
100
NE
NE
20
NE
NE
250000
NE
0.2
500000
NE
NE
0.3
1000
NE
NE
ug/L
Reporting Unit
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
pCi/L
ug/L
Well ID
Sample Collection Date
Analytical Results
Shallow
(�
4(V�
B�^ ��
SS
G/2Ayg
�2
2�1
�
`
j
j
�/�/�/�
Tp(p�/09
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2-2-G�
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().()19j
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1�(�-.�7(v�(00
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94285
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BG
DG SS
9/9,'2()15
. 2
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x(.11
CO.S9
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1T
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360
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17996
ZTp
38790
< 199
�0T
451996
���T('�C(-1
< 1900
�^�(�(��-
6290
Tom`
476
DG SS
1 11 1 /1 s
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2-.'5'-i
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i6799
2 -GG
34699
X100
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1 C�
25899
7.2 j
<5
BG -5S
12/15/2015
<0.2
2.3 j+
<0.5
0.64
430
<5000
<0.5
16300
200
36700
<100
<0.1
187000
-S�
<2500
0.3 j
<10
---
---
<5
BG -5S
3/28/2016
<0.2
1.5 j+
<0.5
0.66
460
<5000
<0.5
17000
206
33600
<100
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165000
<1000
<2500
0.2 j
2.5 j
0.376
0.5
<5
BG -5S
6/21/2016
<0.2
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0.56
460
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16800
204
33700
<100
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160000
---
<2500
0.22 j
2.5 j
0.341
0.5
4.1 j
BG -5S
9/28/2016
<0.2
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0.6
500
<5000
<0.5
18600
206
37500
<100
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204000
---
<2500
0.16 j
22.3 j+
-0.337
5
6
BG -5S
12/15/2016
<0.2
1.4 j
<0.5
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500
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17300
214
36100
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---
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0.14 j
<10
0.0498
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3.4 j
BG -5S
2/22/2017
<0.2
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490
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207
35300
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180000
---
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0.26 j
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0.3364
0.5
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BG -5S
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14400
211
32800
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159000
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<2500
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2.5 j+
0.595
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8/11/2017
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4560j
41
2600
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41000
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41.9
0.2773
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<5000
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6460
15
7000
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36000
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5900
9.74j}
16
---
---
76.3
GWA-9S
3/28/2016
<0.2
1.5 j+
<0.5
2.2
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3250 j
<0.5
7150
23.9
4100
<100
<0.1
70000
<1000
2800
0.1 j
32.2
0.3432
0.5
56.6
GWA-9S
6/17/2016
<0.2
<10
<0.5
2
73
<5000
<0.5
5950
10.1
2600
<100
<0.1
<25000
---
2900
<0.3
<10
1.299
0.5
35.4
GWA-9S
9/28/2016
0.09 j+
<10
<0.5
1.7
69
<5000
<0.5
5850
7.3
1200
<100
<0.1
62000
---
21100
<0.3
5.7 j+
0.495
5
29.2
GWA-9S
12/15/2016
<0.2
1.7 j
<0.5
<0.5
76
<5000
<0.5
5560
6.2
1100
<100
<0.1
39000
---
<2500
<0.3
<10
0.294
0.5
28.4
GWA-9S
2/22/2017
<0.2
<10
<0.5
1.6
76
<5000
<0.5
5420
6.7
9603
<100
<0.1
37000
---
<2500
<0.3
5.4 j
-0.1843
0.5
56.8
GWA-9S
5/8/2017
<0.20
<10.0
<0.50
2.3
69
<5000
<0.50
5650
9.8
3300
<100
0.017 j
48000
<1000
<2500
0.24 j+
6.4 j+
0.759
<0.50
26.1
GWA-9S
8/24/2017
<0.2
---
<0.5
1.6
83
<5000
<0.5
5510
5.7
1100
<100
0.027j
29000
2009
<2500
0.09j
3.4j
---
<0.5
Deep
Emu
747G
BG 59 GG /')'] �'] 11 i C^f 11 i C
Bp/G�
9'�5 c ....-
3 i 7 c)
01�/T�//�r
�5
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157 0 9
6 -� /�
2909
ZTJT
TZV
947/
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BG 59 9/9/'29iC
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i"'"
9-36 j
�'GC(�]G/O�-
<O
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TOO
BG 5D 11 /11 /1
�2
�L
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�
:: OGD-
<0.5
16509
��. (�
ZOO
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04500
���/�/�/�
104000
�E 1999-
�T�G�O(�9
X2500
3.3 j
130
BG -5D 12/15/2015
<0.2
2.3 j+
<0.5
<0.5
120
<5000
<0.5
16700
250
34300
<100
<0.1
204000
33889
<2500
6 j
---
---
13.9
BG -5D 3/28/2016
<0.2
---
0.25 j
<0.5
240
<5000
<0.5
17800
248
---
<100
<0.1
165000
<1000
<2500
0.11 j
<10
---
0.4
BG 513 4/4/2016
iLji
on�
-
111
BG -5D 6/21/2016
<0.2
<10
0.15 j
<0.5
220
<5000
<0.5
17000
242
33100
<100
<0.1
180000
---
<2500
0.2 j
<10
0.821
0.53
91.7
BG -5D 9/28/2016
<0.2
<10
0.17 j
<0.5
410
<5000
<0.5
18800
247
36700
<100
<0.1
232000
---
<2500
0.17 j
2.9 j+
0.6397
0.55
P:\Duke Energy Carol i nas\Statisti cs_CAMA\Backg round Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Dan River\Groundwater\Revised Memo\Tables\TABLE 1 - Dan River -All BG GW Data -Updated Page 2 of 6

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH AUGUST 2017
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, DAN RIVER, NC
Analytical Parameter
pH
Turbidity
Alkalinity
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bicarbonate
Boron
Cadmium
Calcium
Carbonate
Chloride
Chromium
Chromium (VI)
Cobalt
Copper
Iron
Lead
Magnesium
15A NCAC 02L Standard
6.5-8.5
NE
NE
NE
1
10
700
4
NE
700
2
NE
NE
250000
10
0.07
1
1000
300
15
NE
Reporting Unit
SU
NTU
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Well ID
Sample Collection Date
Field Parameters
Analytical Results
Deep (Continued)
BG -5D
12/15/2016 6.8
3.3
128000
<100
<0.5
<0.1
16.6
0.025 j
128000
<50
<0.08
31400
<5000
6300
<0.5
0.061
<0.1
<0.5
<50
<0.1
15500
BG -5D
2/22/2017 6.5
1.3
123000
<100
<0.5
0.086 j
15.5
0.084 j
---
<50
0.078 j
26100
<5000
6500
0.56 j+
0.24
0.092 j
0.31 j
<50
0.093 j
14900
BG -5D
5/8/2017 6.6
4.1
119000
<100
<0.50
<0.10
14.2
0.038 j
119000
<50.0
<0.080
27800
<5000
6600
0.16 j+
0.081 j+
0.055 j+
0.32 j
37.2 j
<0.10
15400
BG -5D
8/24/2017 6.5
3.6
125000
<100
<0.5
0.046J
15.5
<0.10
125000
<50
<0.08
28800
<5000
AMN
6800
1.5
0.1
0.043j
0.5j
<50
<0.1
15800
BG -10D
8/11/2017 5.3
9i��5 6-.3
9.7
11900
119
<0.5
0.14
<5
2Cf
0.045j
E<$2
11900
<50
<0.08
3050
<5000
5300
0.66
0.2
0.12
0.51
107
0.11
1900
47600
t�100
E<O.S
.67
4�7 00
E50
E<0.08
ip4�200
<5000
z�2166
1.2 j!
&/3$j
GWA 99
F��
z�2000
f<0.1
2620
/"'W 99
11i 16 "t /li C �
(0.9-�
9..97
32090
ZTCI
.5
SOT
1-5
SVT
X909
338i
X0.08
8270
2990
�+
(-( �
t'0.pT
�T
VTr
ZWV
932
2269
GWA-91D
12/15/2015 5.8
1.9
25400
<100
<0.5
0.84
13
<0.2
25400
<50
<0.08
7150
<5000
3100
1.4 j+
<0.03
0.88
0.47 j
2300
0.14
2030
GWA-9D
3/28/2016 6
4.19
24700
<100
<0.5
0.56
13
0.039 j
24700
<50
<0.08
6790
<5000
3100
0.27 j+
<0.03
0.84
<0.5
2120
<0.1
1980
GWA-9D
GWA-9D
6/17/2016 5.8
12/15/2016 6
1.9
0.8
28000
26800
<100
68.8j
<0.5
<0.5
0.57
0.13
11.6
12.3
0.0321
0.03j
28000
26800
<50
<0.08
6580
<5000
2400
0.36 j
2
<0.03
0.48
0.85
0.67
2130
<0.1
1870
<50
<0.08
7410
<5000
2900
0.2
1.2
1820
<0.1
1900
GWA-91D
2/22/2017 6
2.4
27400
<100
<0.5
0.53
12.6
0.039 j
---
<50
<0.08
6850
<5000
3000
0.23 j
<0.25
0.83
<0.5
2110
<0.1
1960
GWA-9D
5/8/2017 5.9
2.2
29400
<100
<0.50
0.56
10.8
0.049j
29400
<50.0
<0.080
6750
<5000
3000
0.34 j+
0.53
0.81
0.31j
2070
<0.10
1950
GWA-91)
8/24/2017 5.9
1.8
23700
<100
<0.5
0.48
11
0.052j
23700
<50
<0.08
6760
<5000
3100
0.18j
<0.12
0.84
0.45j
1700
<0.1
1970
■
Nor
'^'ftfP R'
5/8/2013 6-.6-5
8,24
M\A3D
9,r/,T'29•1 7 6-.-7-8
7• 8
TT1
1'4100
MW -23D
12/15/2015 5.95
9.73
168000
<100
<0.5
0.33 j
16
<0.2
168000
<50
<0.08
59000
<5000
5200
1.5
1.1
0.3 j
0.87 j
48 j
13000
moot-
4
MW -23D
9/29/2016 6.1
8.5
76300
34-2
<0.5
0.15
42
0.027 j+
76300
<50
<0.08
29000
<5000
5000
2.1 j+
1.1
0.12
0.64 j+
290
0.12
9410
MW -23D
12/15/2016 6.7
3.1
156000
81.8j
4-.-5
1.8
80.4
0.046j
156000
<50
<0.08
52000
<5000
6000
2.2
0.19
0.24
3.3
46.7j
0.13
12500
MW -23D
2/22/2017 6.6
4.9
136000
95.2 j
<0.5
0.16
50.5
<0.1
---
<50
<0.08
40000
<5000
5700
0.83
0.42
1.2
236
<0.1
11800
MW -23D
5/8/2017 5.8
2.9
80600
87.5 j
<0.50
0.26
48.7
0.011 j
80600
<50.0
<0.080
28400
<5000
4400
0.19 j+
0.065 j+
0.16
0.40 j
66
<0.10
8290
MW -23D
8/24/2017 6.7
9.6
178000
113
<0.5
0.36
87.7
0.014j
178000
<50
<0.08
62200
<5000
7300
1.2
0.28
1.6
172
<0.1
15000
P:\Duke Energy Carol i nas\Statisti cs_CAMA\Backg round Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Dan River\Groundwater\Revised Memo\Tables\TABLE 1 - Dan River -All BG GW Data -Updated Page 3 of 6

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH AUGUST 2017
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, DAN RIVER, NC
Manganese Analytical Parameter
Mercury
Methane
Molybdenum
Nickel
Nitrate + Nitrite
Potassium
Selenium
Sodium
Strontium
Sulfate
Sulfide
Thallium
Total Dissolved Solids
Total Organic Carbon
Total Suspended Solids
Vanadium
Zinc
Radium (Total)
Uranium (Total)
50 15A NCAC 02L Standard
1
NE
NE
100
NE
NE
20
NE
NE
250000
NE
0.2
500000
NE
NE
0.3
1000
NE
NE
ug/L Reporting Unit
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
pCi/L
ug/L
Well ID
Sample Collection Date
Analytical Results
Deep (Continued)
114 BG -5D 12/15/2016
<0.2
1.3 j
<0.5
<0.5
150
<5000 <0.5
16900
265
34800
<100
<0.1
191000
---
<2500
0.094 j
<10
0.0109
0.82
95.5 BG -5D 2/22/2017
<0.2
<10
0.31 j
<0.5
200
<5000 <0.5
15300
249
35200
<100
0.096 j
190000
---
<2500
0.32 j+
<10
0.348
0.72
136 BG -5D 5/8/2017
<0.20
<10.0
0.25 j
0.76
150
<5000 <0.50
15600
272
33600
<100
0.055 j
185000
<1000
<2600
0.27 j+
3.9 j+
0.2347
0.91
145 BG -5D 8/24/2017
<0.2
---
0.26j
1.1
200
<5000 <0.5
16300
257
35200
< 100
<0.1
193000
9081
<2500
0.12j
<10
---
---
6-58
<5000 <0.5
E5000 0.5
4460j
564-9
30.5
2000
<100
19.4 BG -10D 8/11/2017
<0.2
<9.2-
---
<0.5
0.6
<0.1
41000
<1000
<2500
0.47
<10
0.1334
<0.5
7-29 GWA 91) 9/9/2()15
3-}+
8 2 j
4-2
<20
55
4300
<100
<0.1
91889
37589
E5800
10
6-.I9 GWA-99 11 iii n1 C
-E (). 2
2.6 j+
8 j
ter.7
E-29
r5000 E$5r
5099
3-1
6909
-E190
<04
42999
E1$99-
5589
9381
42-1+
-
-
530 GWA-9D 12/15/2015
<0.2
1.9 j+
<0.5
2.5
<20
<5000 <0.5
4850 j
27
6000
<100
<0.1
90000
<1000
5900
0.39 j
16
---
---
520 GWA-9D 3/28/2016
<0.2
1.7 j+
0.12 j
2
<20
<5000 <0.5
4890 j
28.1
7100
<100
<0.1
81000
<1000
<2500
<0.3
5.2 j
0.0736
0.5
522 GWA-9D 6/17/2016
in F11 11111111101wig-111190M,
<0.2
<10
Lon
<0.5
L�:
2.2
<20
M
<5000 <0.5
<5000 <0.5
4600 j
26.8
25.4
5200
<100
<100
<0.1
<0.1
46000
M..
51000
---
<2500
<0.3
421
<10
0.012
0.5
<20
4840 j
5600
---
<2500
6-.7-
0.098
0.5
482 GWA-9D 12/15/2016
<0.2
2.1 j
1
1.2
518 GWA-9D 2/22/2017
<0.2
<10
<0.5
2
<20
<5000 <0.5
4660 j
27.4
5500
<100
<0.1
64000
---
<5000
0.13 j
<10
0.359
0.5
521 GWA-9D 5/8/2017
<0.20
<10.0
0.14 j
2.4
<20
<5000 <0.50
4640 j
26.7
5800
<100
<0.10
69000
<1000
<2500
0.22 j+
3.3 j+
0.491
<0.50
479 GWA-9D 8/24/2017
<0.2
---
<0.5
2
13j
<5000 <0.5
4680j
24.2
6300
<100
0.029j
66000
<1000
<2500
<0.3
■
<10
---
<0.5
6-I- nnwn3II 5/o�
3i999
-5f , nn�nrTw 239 9/4/291
E -I--
7299
39099
25 MW -23D 12/15/2015
<0.2
0.12 j
1
36
<5000 <0.5
6400
110
27700
<100
<0.1
279000
<1000
3500
2.6 j
---
---
Ali
F0
A.,
15.2 MW -23D 9/29/2016
<0.2
<10
0.14 j
1.4
50
<5000 <0.5
6480
186
24700
<100
<0.1
82000
---
<2500
0.66
3.2 j+
1.3775
0.5
102 MW -23D 12/15/2016
<0.2
2.2 j
0.97
60
<5000 0.47 j
7710
481
27000
<100
<0.1
190000
---
<5000
?
<10
0.628
0.066
36 MW -23D 2/22/2017
<0.2
<10
0.87
81
<5000 <0.5
6350
364
26700
< 100
<0.1
184000
---
<2500
0.46
<10
0.593
0.085
78.5 MW -23D 5/8/2017
<0.20
<10.0
0.12 j
0.57
48
<5000 <0.50
5270
253
24500
<100
<0.10
140000
<1000
<2500
0.28 j+
6.0 j+
-0.063
<0.50
336 MW -23D 8/24/2017
<0.2
---
0.7
4.4
150
< 5000 <0.5
8280
627
38200
< 100
<0.1
244000
3389
3400
0.42
3.4j
---
---
P:\Duke Energy Carol i nas\Statisti cs_CAMA\Backg round Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Dan River\Groundwater\Revised Memo\Tables\TABLE 1 - Dan River -All BG GW Data -Updated Page 4 of 6

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH AUGUST 2017
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, DAN RIVER, NC
Analytical Parameter
pH
Turbidity
Alkalinity
Aluminum
Antimony
Arsenic
Barium
Beryllium
Bicarbonate
Boron
Cadmium
Calcium
Carbonate
Chloride
Chromium
Chromium (VI)
Cobalt
Copper
Iron
Lead
Magnesium
15A NCAC O2L Standard
6.5-8.5
NE
NE
NE
1
10
700
4
NE
700
2
NE
NE
250000
10
0.07
1
1000
300
15
NE
Reporting Unit
SU
NTU
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
Well ID
Sample Collection Date
Field Parameters
Analytical Results
Bedrock
BG-10BR
6/30/2016
7.7
9.75
142000
336
0.28j
0.57
23.8
0.03j
142000
<50
<0.08
36100
<5000
2900
1.8
0.098
0.1
1.2
265
0.22
7340
BG-10BR
8/11/2017
54..9j
0. 34j
0.44
1i3,.C4
<0.i10
<�5/0
<0.,08
37�700'�
<5000
22000
3'.i3
2-4
0./046j
0.74
3�8..4j
0..11
pq\_. l SR
6/i�J
X7.5
7ASJ
X4..6^
p 22
�16�20�00
220000
8
1Ti
6�
TJ6
�T
�16/2�/0�/0�0�
220000
<SO
-T
7700
3300
�T
�T
8.46
13II
iT
�7p6(3/0�
ZV909
PqW 23BR
9"19 /2915
73
4
283880 j-
E190
E0.5
14
3-28
E0.20
293880
21�
<�98
48599
E5880
3889
<0.50
-
<0.5
3-.-2
X998
<0.10
3890&
MW-23BR
12/15/2015
7.51
1.2
233000j
66j
<0.5
0.65
120
<0.2
233000
<50
<0.08
54500
<5000
4100
<0.5
0.014 j
<0.5
0.27 j
1200j
<0.1
19400
MW-23BR
3/29/2016
7.4
0.01
217000
<100
<0.5
0.47 j+
110
<1
217000
<50
<0.08
57100
<5000
4200
<5
<0.03
<1
<5
1130
<1
20100
MW-23BR
6/20/2016
7.5
0.3
231000
<100
<0.5
0.62 j
128
<1
231000
31 j
<0.08
55500
<5000
3900
<5
<0.03
<1
11.7
1010
1.4
19400
MW-23BR
9/28/2016
7.6
3.2
236000
<100
0.21 j+
0.36
122
0.025 j+
233000
30.8 j
<0.08
59100
3200j
4700
0.46 j+
<0.15
0.017 j+
0.42 j+
1230
<0.1
20700
MW-23BR
12/15/2016
8
0.3
233000
<100
0.25 j
0.25
123
0.039 j
233000
34.3 j
<0.08
58900
<5000
4600
2.1
0.3
0.93
0.58
1400
0.14
19100
MW-23BR
2/22/2017
7.5
1
226000
<100
<0.5
0.34
128
0.012 j
226000
39.9 j
<0.08
51200
---
4900
0.18 j
<0.12
<0.1
0.68
884
<0.1
18600
MW-23BR
5/8/2017
7.7
0.4
223000
<100
<0.50
0.33
128
0.034 j
223000
41.1 j
<0.080
53800
<5000
5200
0.22 j+
<0.025
<0.10
0.13 j
1320j
<0.10
19000
MW-23BR
8/11/2017
7.0
2.1
225000
<100
<0.5
0.36
128
0.028j
225000
43.Oj
<0.08
49600
<5000
5300
0.14j
<0.12
<0.10
<0.5
949
<0.1
18100
Prepared by: JHG Checked by: CDE
Notes:
54 - Indicates value omitted from dataset.
- Indicates parameter not measured or analyzed.
- Indicates data removed/identified as an outlier
- Indicates data removed due to autocorrelation
- Indicates data removed; data observed as elevated concentration significantly different from majority background well dataset distribution
< - concentration not detected at or above the adjusted reporting limit.
j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
j- - Estimated concentration, biased low.
j+ - Estimated concentration, biased high.
NE - Not established
NTU - Nephelometric turbidity unit
pCi/L - picocuries per liter
S.U. - Standard Unit
ug/L - Micrograms per liter
P:\Duke Energy Carol i nas\Statisti cs_CAMA\Backg round Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Dan River\Groundwater\Revised Memo\Tables\TABLE 1 - Dan River -All BG GW Data -Updated Page 5 of 6

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH AUGUST 2017
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, DAN RIVER, NC
Manganese
Analytical Parameter
Mercury
Methane
Molybdenum
Nickel
Nitrate + Nitrite
Potassium
Selenium
Sodium
Strontium
Sulfate
Sulfide
Thallium
Total Dissolved Solids
Total Organic Carbon
Total Suspended Solids
Vanadium
Zinc
Radium (Total)
Uranium (Total)
50
15A NCAC 02L Standard
1
NE
NE
100
NE
NE
20
NE
NE
250000
NE
0.2
500000
NE
NE
0.3
1000
NE
NE
ug/L
Reporting Unit
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
pCi/L
ug/L
Well ID
Sample Collection Date
Analytical Results
Bedrock
38.8
BG-10BR
6/30/2016
<0.2
<10
0.63
1.1
74
<5000
<0.5
12100
196
2600
<100
<0.1
179000
---
<5000
2
6.21
0.988
2
7.4
BG-10BR
8/11/2017
<0.2
---
0.35j
1.6
57
<5000
<'0i.5
<�1�0(0
<0..�1
<�1�0p00
<2500
0.994
<10
0.927
1.5
3-
MW 23SR
6/iy /�5
�
��
6-54
X102000
13209
13322/0�/9�
�1(7�2(
T/J�/40
�1�7(0(�0/
i2c)�(K)
<�190
-2-70000
Z�T7C0]/000
449
E5000
1�,p
-
2-9
�A\A�PI
9/19/2915
r�2_v
`<v0.L2,
�
�
���/�
X50
�
T5000
'/cC�/�
<V.59
15299
1990
8409
1QV
/G-55
<V.1
266999
�Z"/�f9
'� 1000-
`2500-
�T
�7
x-10
.-
30
MW-23BR
12/15/2015
45.5
1.1
0.47 j
<20
<5000
<0.5
14000
1900
11000
<100
<0.1
276000
29eeq j
<2600
0.31 j
16j+
---
---
25
MW-23BR
3/29/2016
<0.2
41.3
1.3 j
<5
<20
<5000
<5
13900
1710
11300
<100
<0.1
245000
<1000
<2600
<0.3
<10
1.229
5
29.8
MW-23BR
6/20/2016
<0.2
105
1.2 j
<5
<20
<5000
<5
15000
1960
10400
<100
<0.1
250000
---
3500
1.3 j
88.9
0.416
0.36
31.6
MW-23BR
9/28/2016
<0.2
118
1.2
<0.5
<20
<5000
<0.5
16000
1890
10000
<100
<0.1
284000
---
<2500
<0.3
9.4 j+
1.252
5
30.8
MW-23BR
12/15/2016
<0.2
<10
0.63
2.5
<20
<5000
<0.5
15000
1990
10400
<100
<0.1
260000
---
<2500
1.2
2.6 j
0.2259
0.37
28.6
MW-23BR
2/22/2017
<0.2
188
1.3
<0.5
<20
<5000
<0.5
14100
1960
10400
<100
<0.1
241000
---
<2500
0.12 j
9.61
0.101
0.37
33.6
MW-23BR
5/8/2017
<0.20
233
1.4
<0.50
<20
<5000
<0.50
15300
2120
10500
<100
0.042 j
255000
<1000
<2500
0.097 j+
5.5 j+
1.626
0.34 j
34.4
MW -2313R
8/11/2017
<0.2
---
1.3
<0.5
11j
<5000
<0.5
15400
2080
10700
<100
<0.1
241000
<1000
<2500
<0.3
<10
---
---
Prepared by: JHG Checked by: CDE
Notes:
34 - Indicates value omitted from dataset.
- Indicates parameter not measured or analyzed.
- Indicates data removed/identified as an outlier
- Indicates data removed due to autocorrelation
- Indicates data removed; data observed as elevated concentration significantly different from majority background well dataset distribution
< - concentration not detected at or above the adjusted reporting limit.
j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
j- - Estimated concentration, biased low.
j+ - Estimated concentration, biased high.
NE - Not established
NTU - Nephelometric turbidity unit
pCi/L - picocuries per liter
S.U. - Standard Unit
ug/L - Micrograms per liter
P:\Duke Energy Carol i nas\Statisti cs_CAMA\Backg round Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Dan River\Groundwater\Revised Memo\Tables\TABLE 1 - Dan River -All BG GW Data -Updated Page 6 of 6

TABLE 2
REVISED BACKGROUND GROUNDWATER THRESHOLD VALUES
DAN RIVER STEAM STATION
DUKE ENERGY CAROLINAS, LLC, EDEN, NC
Parameter
Reporting Unit
NCAC 02L Standard
Background Threshold Values
Shallow
Deep
Bedrock
pH*
S. U.
6.5-8.5
4.0 -7.1
5.3 - 6.8
6.7 -8.4
Alkalinity
mg/L
NE
77.7
168
236
Aluminum
pg/L
NE
118
113
loot
Antimony
pg/L
1°
0.5
0.5
0.5
Arsenic
pg/L
10
0.5
1.62
0.833
Barium
pg/L
700
19
80.4
128
Beryllium
pg/L
4A
0.429
0.0772
0.0525
Bicarbonate
mg/L
NE
77.7
168
233
Boron
pg/L
700
50
50
50.9
Cadmium
pg/L
2
0.08
0.08
0.08
Calcium
mg/L
NE
19.4
59
59.1
Carbonate
mg/L
NE
5
5
5
Chloride
mg/L
250
7.3
6.8
7.1
Chromium (VI) 1
pg/L
10
0.5
1.24
0.151
Chromium
pg/L
10
1.26
3.42
8.31
Cobalt
pg/L
1°
2.4
0.85
1
Copper
pg/L
1000
2.67
2.29
13
Iron
pg/L
300
152
2130
1400
Lead
fag/L
15
0.1
0.13
1.4
Magnesium
mg/L
NE
12.2
15.9
20.7
Manganese
pg/L
50
81.2
522
38.8
Mercury
pg/L
1
0.2
0.2
0.2
Methane
pg/L
NE
10
10
233t
Molybdenum
pg/L
NE
0.5
0.927
1.4
Nickel
pg/L
100
2.88
3.65
19.2
Nitrate + Nitrite
mg-N/L
NE
0.53
0.349
0.074
Potassium
mg/L
NE
5
5
5
Selenium
pg/L
20
0.5
0.5
0.5
Sodium
mg/L
NE
17.3
17.8
19.2
Strontium
pg/L
NE
211
481
2120
Sulfate
mg/L
250
36.7
36.7
11.3
Sulfide
mg/L
NE
0.1
0.1
0.10
TDS
mg/L
500
187
244
284
Thallium
pg/L
0.2°
0.1
0.1
0.1
TOC
mg/L
NE
it
it
it
Vanadium
pg/L
0.3°
0.413
0.645
2.52
Zinc
pg/L
1000
46.3
10
16t
Radium (Total)
pCi/L
NE
1.45
1.38
1.63t
Uranium (Total)
pg/mL
NE
0.005
0.00106
0.002t
Prepared by: JHG Checked by: CDE
Notes:
* - Upper and lower tolerance limits calculated for parameter
A - Interim Maximum Allowable Concentrations (IMACs) of 15A NCAC .02L Standard, Appendix 1, April 1, 2013
Ng/L - micrograms per liter
pg/mL - micrograms per milliliter
t - Provisional; dataset contains less than 10 valid samples
1 - Hexavalent chromium does not have a NC 2L/IMAC standard; therefore, the NC 2L standard for total chromium is relied upon as a surrogate.
mg - N/L - Milligrams nitrogen per liter
mg/L - milligrams per liter
NE - Not Established
pCi/L - picocuries per liter
Radium (Total) - Radium -226 and Radium -228 combined
S.U. - Standard Unit
TOC - Total Organic Carbons
TDS - Total Dissolved Solids
Uranium (Total) - Uranium -233, Uranium -234, Uranium -236, and Uranium -238 combined
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TABLE 2 - Dan River -Groundwater BTVs_Updated Page 1 of 1