Sutton - GW BTV TM FINAL_20170905

Lip
synTerra
TECHNICAL MEMORANDUM
Date: September 5, 2017 File: 1026.108
To: John Toepfer (Duke Energy)
Cc: Kathy Webb (SynTerra) 49
From: Perry Waldrep (SynTerra)
Subject: Background Threshold Values r Grou
L.V. Sutton Energy Complex- Wilming
An updated background groundwater dataset was provided to the North Carolina Department
of Environmental Quality (NCDEQ) for L.V. Sutton Energy Complex (Sutton) on May 26, 2017.
Additionally, 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) was provided to NCDEQ. On July 7, 2017, NCDEQ
provided a response letter (Zimmerman to Draovitch, July 7, 2017) for each Duke Energy coal
ash facility that identified soil and groundwater data appropriate for inclusion in the statistical
analysis to determine background threshold values (BTVs) for both media. As outlined in the
NCDEQ July 7, 2017 letter, Duke Energy is required to provide BTVs for both media within 60
days from receipt of the NCDEQ letter for facilities submitting Comprehensive Site
Assessments (CSAs) later than October 31, 2017. BTVs for soil are provided under separate
cover.
The updated background groundwater dataset provided to NCDEQ on May 26, 2017 addressed
comments provided in a letter by NCDEQ (Zimmerman to Draovitch, April 28, 2017). NCDEQ
requested Duke Energy collect at least 10, rather than the previously planned eight, valid
samples from background monitoring wells prior to determination of BTVs for constituents
within each flow system. For groundwater datasets with less than 10 valid samples available
for determination of BTVs, no formal upper tolerance limit (UTL) statistics could be run and the
provisional BTV (PBTV) for a constituent and groundwater flow system was computed to be
either:
h The highest value, or
y If the highest value is above an order of magnitude greater than the geometric mean
of all values, then the highest value should be considered an outlier and removed
from further use and the PBTV is computed to be the second highest value.
P:\Duke Energy Progress.1026\Statistics—LAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO \ Sutton \ Groundwater \ Sutton - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater September 5, 2017
L.V. Sutton Energy Complex Page 2 of 4
NCDEQ requested that the updated background groundwater dataset exclude data from the
background data set due to one or more of the following conditions:
y Sample pH is greater than 8.5 standard units (S.U.) unless the regional DEQ office
has determined an alternate background threshold pH for the site;
Sample turbidity is greater than or equal to 10 Nephelometric Turbidity Units
(NTUs);
0 Result is a statistical outlier identified for background sample data presented to
NCDEQ on May 26, 2017;
47 Sample collection occurred less than a minimum 60 days between sampling events;
and,
41, Non -detect results are greater than 2L/lMAC.
Additional site -specific requirements related to background groundwater dataset for Sutton as
outlined in the July 7, 2017 NCDEQ letter have been incorporated.
This technical memorandum summarizes the revised background groundwater datasets and
statistically determined BTVs. Statistical determinations of BTVs were performed in accordance
with 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).
GROUNDWATER BACKGROUND DATA
The current background monitoring well network consists of wells installed within four flow
zones -upper and lower surficial, upper and lower Pee Dee. Well locations are presented on
Figure 1. Background datasets provided to NCDEQ on May 26, 2017 were revised based on
input from NCDEQ in the July 7, 2017 letter. Revised background datasets for each flow system
utilized to statistically determine naturally occurring concentrations of inorganic constituents in
groundwater are provided in Table 1. The following sections summarize the refined
background datasets along with results of statistical evaluations for determining BTVs.
UPPER SURFICIAL
Three wells - MW-5A, MW-5B, and, MW-37B - monitor background groundwater quality
within the upper surficial zone. NCDEQ concurred with the data proposed for the upper
surficial flow zone background dataset. Samples collected less than 60 days between sampling
events, statistical outliers, and invalid data have been omitted from use in statistical
determinations. The upper surficial background groundwater dataset meets the minimum
requirement of 10 samples for all constituents. The revised upper surficial background dataset
is presented in Table 1. BTVs were calculated for constituents monitored within the upper
surficial flow system using formal UTL statistics and are presented in Table 2.
P:\Duke Energy Progress.1026\Statistics—LAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO \ Sutton \ Groundwater \ Sutton - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater September 5, 2017
L.V. Sutton Energy Complex Page 3 of 4
LOWER SURFICIAL
Four wells - MW-413, MW-5C, MW-8, and MW-37C - monitor background groundwater quality
within the lower surficial zone. NCDEQ concurred with the data proposed for the lower
surficial flow zone background dataset. Samples collected less than 60 days between sampling
events, statistical outliers, and invalid data have been omitted from use in statistical
determinations. The revised background dataset for the lower surficial ozone (Table 1) used to
determine BTVs consists of data collected through first quarter 2017. The revised dataset meets
the minimum requirement of 10 samples for all constituents except chromium (VI). As of third
quarter 2017, continued sampling of background wells has increased the number of background
samples for chromium (VI) to 12. BTVs will be determined using the expanded dataset at a
later date.. No formal UTL statistics were performed for hexavalent chromium at this time and
the PBTV was computed to be either the highest value, or, if the highest value was above an
order of magnitude greater than the geometric mean of all values, the highest value was
considered an outlier and removed from further use and the PBTV was computed to be the
second highest value. BTVs were calculated for all remaining constituents monitored within the
lower surficial flow system using formal UTL statistics and are presented in Table 2.
UPPER PEE DEE
Three wells - MW-05CD, MW-05D, and MW-37D - monitor background groundwater quality
within the upper Pee Dee flow zone. NCDEQ concurred with the data proposed for the upper
Pee Dee flow zone background dataset. Samples collected less than 60 days between sampling
events, statistical outliers, and invalid data have been omitted from use in statistical
determinations. Due to naturally occuring pH conditions at this depth, background samples
with a pH greater than 8.5, but less than 9.7, were approved by NCDEQ for inclusion in the
background dataset. The revised background dataset for the upper Pee Dee (Table 1) used to
determine BTVs represents data collected through first quarter 2017 and does not meet the
minimum requirement of 10 samples. As of third quarter 2017, continued sampling of
background wells has increased the number of background samples for the lower Pee Dee
dataset to 11. BTVs will be determined using the expanded dataset at a later date. No formal
UTL statistics were run for the upper Pee Dee flow zone at this time, and the PBTV was
computed to be either the highest value, or, if the highest value was above an order of
magnitude greater than the geometric mean of all values, the highest value was considered an
outlier and removed from further use and the PBTV was computed to be the second highest
value. PBTVs were calculated for all constituents monitored within the upper Pee Dee and are
presented in Table 2.
LOWER PEE DEE
Four background wells - MW-5R-E, MW-8E, MW-37E, and MW-41E - monitor background
groundwater quality within the lower Pee Dee flow zone. Samples collected less than 60 days
between sampling events, statistical outliers, and invalid data have been omitted from use in
statistical determinations. Due to naturally occuring pH conditions at this depth, background
samples with a pH greater than 8.5, but less than 9.7, were approved by NCDEQ for inclusion in
P:\Duke Energy Progress.1026\Statistics-LAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO \ Sutton \ Groundwater \ Sutton - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater September 5, 2017
L.V. Sutton Energy Complex Page 4 of 4
the background dataset. The revised background dataset for the lower Pee Dee (Table 1) used
to determine BTVs represents data collected through first quarter 2017 and does not meet the
minimum requirement of 10 samples. As of third quarter 2017, MW-5R-E, MW-8E, and MW-
41E have been installed to augment the background dataset the lower Pee Dee flow zone.
Sampling of MW-5E has ceased since a replacement well (MW-5R-E) was installed in its place.
Samples collected from the three newly installed wells in addition to continued sampling of
MW-37E has increased the number of background samples for the lower Pee Dee dataset to 10.
BTVs will be determined using the expanded dataset at a later date. No formal UTL statistics
were run for the lower Pee Dee flow zone at this time, and the PBTV was computed to be either
the highest value, or, if the highest value was above an order of magnitude greater than the
geometric mean of all values, the highest value was considered an outlier and removed from
further use and the PBTV was computed to be the second highest value. PBTVs were calculated
for all constituents monitored within Lower Pee Dee and are presented in Table 2.
LIST OF FIGURES:
Figure 1 Well Location Map
LIST OF TABLES:
Table 1 Background Dataset for Groundwater through March 2017
Table 2 Background Threshold Values for Groundwater
P:\Duke Energy Progress.1026\Statistics—LAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO \ Sutton \ Groundwater \ Sutton - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater September 5, 2017
L.V. Sutton Energy Complex
FIGURE
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO \ Sutton \ Groundwater \ Sutton - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater September 5, 2017
L.V. Sutton Energy Complex
TABLES
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 72017\BTV TECH
MEMO \ Sutton \ Groundwater \ Sutton - GW BTV TM_FINAL.docx

TABLE 1
BACKGROUND GROUNDWATER ANALYTICAL RESULTS THROUGH MARCH 2O17
L.V. SUTTON ENERGY COMPLEX
DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC
P.
Turbidity
Alkalinity
Aluminum
Antimony
Arsenic
Barium
Beryllium
bB.i
Car at.
Alkalinity
B—.
.,.-ide
Cadmium
Calcium
Carl, ... to
Alkalinity
Chloride
Chro -
(voolum
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Me ... ry
Surfici.l Upper
P:\Duke Energy P,ogress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Sutton\Groundwater\Tables\TABLE 1 - Sutton_BG GW Data.xlsx Page 1 of 4

TABLE 1
BACKGROUND GROUNDWATER ANALYTICAL RESULTS THROUGH MARCH 2O17
L.V. SUTTON ENERGY COMPLEX
DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC
Analytical Parameter
Methane
Molybdenum
Nickel
Nitrate + Nitrite
Potassium
Selenium
Sodium
Strontium
Sulfate
Sulfide
Thallium
Total Dissolved Solids
Total Organic Carbon
Vanadium
Zinc
Radium-226
Radium-228
Uranium-233
Uranium-234
Uranium-236
Uranium-238
Reporting Units
ug/L
ug/L
ug/L
mg-N/L
mg/L
ug/L
mg/L
ug/L
mg/L
mg/L
ug/L
mg/L
mg/L
ug/L
ug/L
pCi/L
pCi/L
ug/mL
ug/mL
ug/mL
ug/mL
ISA NCAC 02L Standard
NE
NE
100
NE
NE
20
NE
NE
250
NE
0.2*
500
NE
0.3-
1000
NE
NE
NE
NE
NE
NE
Sample ID
Sample
Date
its
Analytical Results
Surficial Upper
MW-05A
12/04/2015
<10
<1
<1
0.107
0.423
<1
1.09
5
14
<0.1
<0.2
<25
0.544
<0.3
15
-
-
-
-
-
-
MWESR
4-.a
<1
<1
0-018
0-.163
<1
4-24
<-5
6:5
<-04.
<-B-2
<25
0365
<0-.3
<5
-
-
-
-
-
-
MW-OSA
03/08/2016
23.6
<1
<1
0.016
0.439
<1
1.36
<5
5.9
<0.1
<0.2
<25
0.604
<0.3
<5
<1
<3
<0.00005
<0.00005
<0.00005
<0.0002
MW-BSR
06116f20i6
234
<1
<}
10,$1
9432
<1
4,09
K
7-:S
<-04.
<A2
<25
0-943
0-073-B2
<5
0fi44
0368
<$:00005
<0:00005
<8.A0005
<0-:0002
MW-05A
O8/08/2016
25.8
<1
<1
c0.01
0.368
<1
1.06
<5
8.2
<0.1
<0.2
<25
0.646
<0.3
<5
0.487
0.513
<0.00005
<0.00005
<0.00005
<0.0002
MW-BSA
<4
<}
<4
<0.8BBB5
<&.80005
<490085
<B.BBB2
MW-05A
12/01/2016
28.4 N2
<1
<1
c0.01
0.402
<1
1.09
<5
8
<0.1
<0.2
<25
0.692 B2
<0.3
<5
0.428
1.04
<0.00005
<0.00005
<0.00005
<D.0002
MW-05A
03/13/2017
254
<1
<1
<0.01
0.311
<1
1.1
<5
9.2
<0.1
<0.2
<25
0.718 B2
0.621 B
<5
0.277
<1
<0.00005
<0.00005
<0.00005
<0.0002
MW-05B
05/23/2014
-
<-1-:7
<15
-
1.02
<8:4
0.00202
<10
5.4
-
<6:4
<30
-
<2
<40
-
-
-
-
-
-
MW-05B
12/04/2015
<10
<1
<1
0.093
0.224
<1
0.984
<5
7.5
<0.1
<0.2
<25
0.29
<0.3
6
-
-
-
-
-
-
NW--B58
1�
<1
<1
0.898
<1
i-:4k
7
2-3
«.1
<8.2
- 25
04. "
<63
6
---
---
-
-
-
-
MW-05B
03/08/2016
15.5
<1
<1
0.077
0.691
<1
1.38
8
6.3
<0.1
<0.2
<25
0.271
<0.3
5
<1
<3
<0.00005
<0.00005
<0.00005
<0.0002
MW-BSB
06f16}2916
<iB
<1
<1
0-069
B:i61
<1
3-48
7
84
8
0:982
0:157
c9-BBBgS
<9.BBBBS
<9,BB805
<9.gBB2
MW-05B
O8/08/2016
<30
<1
<1
10.059
0.738
<1
1.5
7
7.7
<0.1
<0.2
<25
0.309
<0.3
<5
0.721
<1
<0.00005
<0.00005
<0.00005
<0.0002
MW-BSB
14l,'1g,4016
<i0-P12
<}
<1
0d44
0.729
c-}
}A4-B2
8
5
<-0:}
<-D2-82
23
0-33
<83
1
OS8 4
g{67
<0-00005
<8.BB085
<O.B0005
<B,BBB2
MW-05B
12/01/2016
25.6 N2
<I
<1
0.015
0.734
<I
1.48
8
9.5
<0A
<0.2
<25
0.289 82
<0.3
6
<1
1.4
<0.00005
<0.00005
<0.00005
<0.0002
MW-05B
03/13/2017
<10
<1
<1
0.056
0.694
<1
1.51
8
15
<0.1
<0.2
<25
0.306
0.604B
<5
0.462
<1
<0.00005
<0.00005
<0.00005
<0.0002
MW-37B
03/27/2015
<10
<I
<1
0.102
0.263
<I
3.08
6
4.6
<0.1
<0.2
<25
0.663
<0.3
<5
-
-
-
-
-
-
MW-37B
06/02/2015
<10
<1
<1
0.096
0.204
<1
2.31
<5
7.2
<0.1
<0.2
<25
0.514
<0.3
10
---
--
-
---
-
-
MW-37B
09/23/2015
-
<1
<1
-
0.242
<1
1.82
<5
-
-
B35
-
-
<0.3
<5
-
-
-
-
-
-
-
MW-37B
12/03/2015
<10
<I
<1
0.088
0.235
<I
1.8
<5
5.1
<0.1
<0.2
<25
0.61
<0.3
<5
-
-
-
-
-
-
i9w-33B
<}0
<}
<1
0. 104
Bd33
«
2:03
K
6.8
<-04
<8.2
<25
0i56
<0.3
K
-
---
-
-
-
-
MW-37B
03/08/2016
<10
<1
<5
0.103
0.234
<I
2
<5
5.4
<0.1
<0.2
<25
0.638
<0.3
<0.005 B2
0.546
H
<0.00005
<0.00005
<0.00005
<0.0002
MW-37B
06/14/2016
<10
<1
<5
0.108
0.216
<1
1.76
<5
7.7
<0.1
<0.2
<25
0.622
<0.3
<5
0.521
0.667
<0.00005
<0.00005
<O.00005
<0.0002
MW378
<19
<1
H
0-098
B: A6
<}
4-5
7
8-. 2
-.04
<$.2
<25
0-.798
<43
<5
<}
0,872
<&00805
.4-00005
<8-:00005
<0-:BBB2
MW-37B
10H8j2016
<10-N2
<-}
<1
0.878
0.-23}
<-}
4-h482
<-5
63
<-B-1
-
<25
0:.
<-..3
K
1-58
1
< .
<-&.90805
<0-:80005
<-&.9002
MW-37B
11/30/2016
<10 N2
<1
<1
0.091
0.214
<1
1.26
<5
7.6
<0.1
<0.2
<25
0.539
<0.3
<5
0.409
1.08
<0.00005
<0.00005
10.00005
<0.0002
MW-37B
03/13/2017
<10
<1
<1
..073
..226
<1
1.68
<5
7.1
<0.1
<0.2
<25
0.567
0.75 B3,B
<5
<1
<1
<0..0005
c0.00005
<0.00005
c0.0002
Surficial Lower
MW-04B
03/02/2011
-
-
<5
-
-
<10
-
-
7.9 B
-
<0.1
116 B
-
-
<10
-
-
-
-
-
-
MW-04B
10/04/2011
-
-
<5
-
-
<10
-
-
7.1
-
<0.1
105
-
-
<10
-
-
-
-
-
-
MW-04B
03/06/2012
-
-
<5
-
-
<10
-
-
6.9
-
<0.1
168
-
-
<10
-
-
-
-
-
-
MW-04B
06/05/2012
-
-
<5
-
-
<10
-
-
8.9
-
<0.1
153
-
-
<10
-
-
-
-
-
-
MW-04B
10/02/2012
-
-
<5
-
-
<10
-
-
8.5
-
<0.1
145
-
-
<10
-
-
-
-
-
-
MW-04B
03/12/2013
-
-
<5
-
-
<1
-
-
8.1
-
<0.2
140
-
-
15
-
-
-
-
-
-
MW-04B
06/12/2013
-
-
<5
-
-
<1
-
-
8.8
-
<0.2
130
-
-
6
-
-
-
-
-
-
MW-D4B
10/02/2013
-
-
<5
-
-
<1
-
-
8.1
-
<0.2
180
-
-
<5
-
-
-
-
-
-
MW-04B
03/04/2014
-
-
<5
-
-
<1
-
-
8.8
-
<0.2
180
-
-
5
-
-
-
-
-
-
MW-0413
06/02/2014
--
-
<5
--
-
<1
--
-
8.6
-
<0.2
170
--
--
<5
--
--
--
--
-
-
MW-04B
10/01/2014
-
-
<5
-
-
<1
-
-
9.4
-
<0.2
210
-
-
<5
-
-
-
-
-
-
MW-04B
03/11/2015
-
-
<5
-
-
<1
-
-
9.3
-
<0.2
180
-
-
<5
-
-
-
-
-
-
MW-04B
06/O1/2015
-
<1
<5
-
2.36
<1
5.61
-
10
-
<0.2
210
-
-
<5
-
-
-
-
-
-
MW-04B
10/12/2015
-
<1
<5
-
2.73
<1
6.7
167
10
-
<0.2
230
-
c0.3
<5
-
-
-
-
-
-
mvt- 6
12jG4R#15
}03
<}
<1
<08}
2Si8
<}
638
442
44
<G4
<0-2
240
2
<03
<6
-
-
-
-
-
-
Mw-0as
0-02
2:69
<}
6.63
140
14
<0--4
<0:2
220
1.8
<0:3
-S
-
-
-
-
-
-
MW-04B
03/08/2016
254
<I
<5
<0.01
2.73
<1
6.73
146
10
<0.1
<0.2
200
2
<0.3
6 B2
0.723
3.4
<0.00005
<0.00005
<0.00005
0.000086j
MW-04B
06/14/2016
-
<1
<5
-
2.74
<1
7.13
171
12
-
<0.2
260
-
<0.3
<5
-
-
-
-
-
-
MW-04B
10/18/2016
384 N2,CH,P2
<1
<1
<0.01
2.63
<1
6.68 B2
148
10
<0.1
<0.2
200
2.1
<0.3
5
1.5
0.727
<0.00005
<0.00005
<0.00005
0.000128j
-
MW-05C
03/07/2012
-
-
<5
-
-
<10
-
-
7.8
-
<0.1
59
-
-
<10
-
-
-
-
-
-
MW-05C
06/06/2012
-
-
<5
-
-
<10
-
-
8.8
-
<0.1
52
-
-
<10
-
-
-
-
-
-
MW-05C
10/02/2012
-
-
<5
-
-
<10
-
-
11.9
-
<0.1
59
-
-
<10
-
-
-
-
-
-
MW-OSC
03/13/2013
-
-
<5
-
-
<1
-
-
9.6
-
<0.2
47-
MW-05C
06/13/2013
-
-
<5
-
-
<1
-
-
7a
-
<0.2-
MW-OSC
SO/03/2013
-
-
<5
-
-
<1
-
-
13
-
<0.2
]2
-
-
<5
-
-
-
-
-
-
P:\Duke Energy Progress.1026\Statistirs_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Sutton\Groundwater\Tables\TABLE 1 - Sutton_BG GW Dataxlsx Page 2 Of 4

TABLE 1
BACKGROUND GROUNDWATER ANALYTICAL RESULTS THROUGH MARCH 2O17
L.V. SUTTON ENERGY COMPLEX
DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC
Analytical ipammeter�
PH
Turbidity
Alkalinity
Aluminum
Antimony
Arsenic
Barium
B.,Ylli.m
.i_
carb ... t.
Alkalinity
Boron
Bromide
Cadmium
Calcium
Carlo ... to
Alkalinity
Chloride
Chromium
(VI),
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Analytical Res, It,
��
®�
eve®e®weave®�®vee�eee®
��
®�
eemmmee�emeaae®a®�ma�e
t
Pee Dee upper
�����
P—ared bv: JHG Checked bv: RHJ
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
< - concentration not detected at or above the adjusted reporting limit. pCi/L - picocuries per liter
mg - N/L- Milligrams nitrogen per liter S.U. - Standard Unit
mg/L- Milligrams per liter ug/L- Micrograms per liter
HE - Not established ug/mL - micrograms per milliliter
NTU - Nephelometrlc turbidity unit
* - Interim Maximum Allowable Concentrations (IMACs) of the 15A NCAC 02L Standard, Appendix 1, April, 1, 2013.
- Hexavalent chromium does not have a NC 2L/IMAC standard; therefore, the INC 2L standard for total chromium is relied upon as a surrogate.
B - Target analyte detected in method blank at or above the reporting limit. Target analyte concentration in sample is less than 10X the concentration in the method blank. Analyte concentration in sample could be due to blank contamination.
31 - Target analyte detected In method blank at or above the reporting limit. Target analyte concentration in sample was greater than 10X the concentration in the method blank. Analyte concentration in sample is not affected by blank contamination.
32 - Target analyte was detected in blank(s) at a concentration greater than 1/2 the reporting limit but less than the reporting limit, Analyte concentration in sample is valid and may be used for compliance purposes.
B3 - Target analyte was detected in Continuing Calibration Blank(s) at a concentration greater than 1/2 the reporting limit but less than the reporting limit. Analyte concentration in sample is valid and may be used for compliance purposes.
CH - The continuing calibration for this compound is outside of Pace Analytical acceptance limits. The results may be biased high.
D3 - Sample was diluted due to the presence of high levels of non -target analytes or other matrix Interference.
j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
MI - Matrix spike recovery was high: the associated Laboratory Control Spike (LCS) was acceptable.
M2 -Matrix spike recovery was Low: the associated Laboratory Control Spike (LCS) was acceptable.
M4 - The. spike recovery value was unusable since the analyte concentration in the sample was disproportionate to the spike level. The associated Laboratory Control Spike recovery was acceptable.
NI - This sample was inadvertently collected with sample running through the flow cell and should be considered invalid based on possible contamination from the flow cell,
N2 - The lab does not hold accreditation for this parameter.
P2 - Re -extraction or re -analysis could not be performed due to insufficient sample amount.
P:\Duke Energy Progress.1026\Statistirs_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Sutton\Groundwater\Tables\TABLE 1 - Sutton_BG GW Data.xlsx Page 3 of 4

TABLE 1
BACKGROUND GROUNDWATER ANALYTICAL RESULTS THROUGH MARCH 2O17
L.V. SUTTON ENERGY COMPLEX
DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC
���e®ae�ee�e��va®avae®e
��ee®ee�va®eeee®evae®�
��ee®ee®ee®ems®va®avae®®
000©000©®©©0000©epee®®
000©o�®©o©o®�oo�©e®eeee
000©©o®o®0000000©o©��o
000©©o®000©��000®oo��o
��eeeee�eeeee�eeeeeeeee
��ee®ee�va�e��va�aeeeee
��ee®ee�e�®e��ee�eeeeee
��ee®ae�aaee�®vaoavaeee
owe©©vo©®©�e�oe©©e®eeee
0000000©00000000©�0��0
0000©000©©0000��oo©��oo
0000®moo©oo���o®�©o©��oo
000®®oo®oo®®oo®oo©0000
Prepared by: JHG Checked by: LWD
Notes:
54 - Indicates value omitted from dateset.
Indicates parameter not measured or analyzed.
® Indicates data removed /identified as an outlier
Indicates data removed due to autocorrelation
< - concentration not detected at or above the adjusted reporting limit. pCi/L - picocuries per liter
mg - N/L- Milligrams nitrogen per liter S.U. - Standard Unit
mg/L- Milligrams per liter ug/L- Micrograms per liter
NE - Not established ug/mL- micrograms per milliliter
NTU - Nephelometric turbidity unit
* - Interim Maximum Allowable Concentrations (IMACs) of the 15A NCAC 02L Standard, Appendix 1, April, 1, 2013.
- Hexavalent chromium does not have a NC 2L/IMAC standard; therefore, the NC 2L standard for total chromium is relied upon as a surrogate.
B - Target analyte detected in method blank at or above the reporting limit. Target analyte concentration in sample is less than 10X the concentration in the method blank. Analyte concentration in sample could be due to blank contamination.
Bl - Target analyte detected In method blank at or above the reporting limit. Target analyte concentration in sample was greater than 10X the concentration in the method blank. Analyte concentration in sample is not affected by blank contamination.
82 - Target analyte was detected in blank(s) at a concentration greater than 1/2 the reporting limit but less than the reporting limit, Analyte concentration in sample is valid and may be used for compliance purposes.
B3 - Target analyte was detected in Continuing Calibration Blank(s) at a concentration greater than 1/2 the reporting limit but less than the reporting limit. Analyte concentration in sample is valid and may be used for compliance purposes.
CH - The continuing calibration for this compound is outside of Pace Analytical acceptance limits. The results may be biased high.
D3 - Sample was diluted due to the presence of high levels of non -target analytes or other matrix Interference.
j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
MI - Matrix spike recovery was high: the associated Laboratory Control Spike (LCS) was acceptable.
M4 - The spike recovery value was unusable since the analyte concentration in the sample was disproportionate to the spike level. The associated Laboratory Control Spike recovery was acceptable.
M4 - The. spike recovery value Was unusable since the analyte concentration in the sample was disproportionate to the spike level. The associated Laboratory Control Spike recovery was acceptable.
NI - This sample was inadvertently collected with sample running through the flow cell and should be considered invalid based on possible contamination from the flow cell.
N2 - The lab does not hold accreditation for this parameter.
P2 - Re -extraction or re -analysis could not be performed due to insufficient sample amount.
P:\Duke Energy Progress.1026\Statistirs_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Sutton\Groundwater\Tables\TABLE 1 - Sutton_BG GW Data.xlsx Page 4 of 4

TABLE 2
GROUNDWATER BACKGROUND THRESHOLD VALUES
L.V. SUTTON ENERGY COMPLEX
DUKE ENERGY PROGRESS, LLC, WILMINGTON, NC
Parameter
Reporting
Unit
NCAC 02L
Standard
Background Threshold Values
Surficial
Upper
Surficial
Lower
Pee Dee
Uppert
Pee Dee
Lowert
pH*
S.U.
6.5-8.5
3.94 - 5
4.9 - 7.4
8.2 - 8.9
9 - 9.7
Alkalinity
mg/L
NE
5
171
410
464
Aluminum
pg/L
NE
958
51.7
593
73
Antimony
pg/L
I
1
1
1
1
Arsenic
pg/L
10
1
5
3
1
Barium
pg/L
700
45
97
17
27
Beryllium
pg/L
4°
1
1
1
1
Bicarbonate
mg/L
NE
5
171
402
391
Boron
pg/L
700
50
50
3010
3520
Cadmium
pg/L
2
1
1
1
1
Calcium
mg/L
NE
0.996
74
22.6
9.47
Carbonate
mg/L
NE
5
5
20.7
98
Chloride
mg/L
250
4.73
23.6
680
1200
Chromium (VI) 1
pg/L
10
0.03
0.11t
0.26
0.1
Chromium
pg/L
10
1
1
2
2
Cobalt
pg/L
1A
4
3
1
1
Copper
pg/L
1000
1
1
1
1
Iron
pg/L
300
1494
13416
336
102
Lead
pg/L
15
1
1
1
1
Magnesium
mg/L
NE
0.589
3.43
13.5
13.7
Manganese
pg/L
50
38
746
63
5
Mercury
pg/L
1
0.05
0.05
0.05
0.05
Methane
pg/L
NE
25.8
363
121
18.6
Molybdenum
Ng/L
NE
1
1
20.7
16.1
Nickel
Ng/L
100
1
1
1
3.29
Nitrate + Nitrite
mg-N/L
NE
0.107
0.098
0.01
0.011
Potassium
mg/L
NE
0.738
4.97
20.5
48
Selenium
Ng/L
20
1
1
1
5
Sodium
mg/L
NE
3
18.5
584
939
Strontium
Ng/L
NE
8
167
232
329
Sulfate
mg/L
250
15.6
16
220
230
Sulfide
mg/L
NE
0.1
0.1
0.14
1.8
TDS
mg/L
500
25
210
1700
1800
Thallium
Ng/L
0.2°
0.2
0.2
0.2
0.2
TOC
mg/L
NE
0.692
6.7
3.3
6.6
Vanadium
Ng/L
0.3A
0.621
1.68
1.88
0.481
Zinc
Ng/L
1000
5
13
5
6
Radium (Total)
pCi/L
NE
2.75
5.32
2
1 5.53
Uranium (Total)
pg/mL
NE
0.00035
0.0004
0.00153
1 0.00077
Prepared by: LWD Checked by: THE
Notes:
* - Upper and lower tolerance limits calculated for parameter
4 - Interim Maximum Allowable Concentrations (IMACs) of 15A NCAC .021 Standard, Appendix 1, April 1, 2013
t - Provisional; dataset contains less than 10 valid samples
- 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/L - milligrams per liter
mg - N/L - Milligrams nitrogen per liter
NE - Not Established
pCi/L - picocuries per liter
Radium (Total) - Radium-226 and Radium-228 combined
S.U. - Standard Unit
TDS - Total Dissolved Solids
TOC - Total Organic Carbon
pg/L - micrograms per liter
pg/mL - micrograms per milliliter
P:\Duke Energy Progress. 1026\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO\Sutton\Groundwater\Tables\
TABLE 2 - Sutton GW BG Threshold Values Page 1 of 1