Revised - Roxboro BTV GW Tech Memo_20170816

TECHNICAL MEMORANDUM
Date: August 16, 2017 File: 1026.107
To: Kimberlee Witt (Duke Energy)
Cc: Kathy Webb (SynTerra)
From: Craig Eady (SynTerra) �-
Subject: Background Threshold Values for Groundwater
Roxboro Steam Electric Plant - Semora, NC
An updated background groundwater dataset was provided to the North Carolina Department
of Environmental Quality (NCDEQ) for Roxboro Steam Electric Plant (Roxboro) 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 30 days from receipt of the NCDEQ letter for facilities submitting Comprehensive
Site Assessments (CSAs) by October 31, 2017, and 60 days from receipt of the NCDEQ letter for
all other facilities. 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:
01 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_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO \ Roxboro \ Groundwater \ FINAL \ Roxboro - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater August 16, 2017
Roxboro Steam Electric Plant Page 2 of 3
NCDEQ requested that the updated background groundwater dataset exclude data from the
background data set due to one or more of the following conditions:
h Sample pH is greater than or equal to 8.5 standard units (S.U.) unless the regional
DEQ office has determined an alternate background threshold pH for the site;
h Sample turbidity is greater than 10 Nephelometric Turbidity Units (NTUs);
0 Result is a statistical outlier identified for background sample data presented to
NCDEQ on May 26,2017;
y Sample collection occurred less than a minimum 60 days between sampling events;
and,
y Non-detected results are greater than 2L/IMAC.
Additional site-specific requirements related to background groundwater dataset for Roxboro
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
Groundwater across the Site is unconfined and found within the ash basins and three flow
systems - residuum/saprolite, transition zone, and fractured bedrock. However, saturated
conditions are not evident within the residuum/saprolite units in background locations due to
the nature of the former natural drainage features in which the ash basins were created. The
current background monitoring well network consists of wells installed within the transition
zone and fractured bedrock. Well locations are presented on Figure 1. Provided in Table 1 is
the revised background datasets for each flow system, based on input from July 7, 2017 NCDEQ
letter, utilized to statistical determine naturally occurring concentrations of inorganic
constituents in groundwater. The following sections summarize the refined background
datasets along with the results of the statistical evaluations for determining BTVs.
TRANSITION ZONE
Three background wells - BG -01, MW -15D, and MW -18D - monitor background groundwater
quality within the transition zone. In the July 7, 2017 letter, NCDEQ identified two samples
collected from BG -01 (BG -01: 9/8/16 and 11/16/16) that were collected less than 60 days between
P: \ Duke Energy Progress.1026 \ Statistics_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO \ Roxboro \ Groundwater \ FINAL \ Roxboro - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater August 16, 2017
Roxboro Steam Electric Plant Page 3 of 3
sampling events and are not appropriate for use in statistical determinations. The revised
transition zone background dataset is presented in Table 1. The revised transition background
dataset satisfies the minimum requirement of 10 samples to use formal UTL statistics to derive
BTVs for each constituent monitored within the transition zone. BTVs for transition zone are
presented in Table 2.
BEDROCK
Six background wells — BG-1BR, MW-10BR, MW-14BR, MW-15BR, MW-18BR, and MW-19BRL
— monitor background groundwater quality within fractured bedrock. In the July 7, 2017 letter,
NCDEQ recommended that the three wells (MW-13BR, MW-16BR, and MW-17BR) previously
identified in the background dataset be removed. Additionally, NCDEQ identified one sample
each from BG-01BR (7/9/15) and MW-17BR (11/10/16) that were collected less than 60 days
between sampling events are not appropriate for use in statistical determinations.
Prior to statistical determinations, the background bedrock dataset was re -screened for outliers
to adjust for the removal of monitoring wells MW-13BR, MW-16BR, and MW-17BR from the
dataset. A revised background dataset including updated outliers is presented in Table 1. The
background bedrock dataset meets the minimum requirement of 10 samples to use formal UTL
statistics to derive BTVs for each constituent monitored within the bedrock flow system. BTVs
for bedrock are presented in Table 2.
LIST OF FIGURES:
Figure 1 Well Location Map
LIST OF TABLES:
Table 1 Background Groundwater Results Through January 2017
Table 2 Background Threshold Values for Groundwater
P: \ Duke Energy Progress.1026 \ Statistics_CAMA \ Background Determinations for NCDEQ July 7 2017 \ BTV TECH
MEMO \ Roxboro \ Groundwater \ FINAL \ Roxboro - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater August 16, 2017
Roxboro Steam Electric Plant
FIGURES
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 72017\13TV TECH
MEMO \ Roxboro \ Groundwater \ FINAL \ Roxboro - GW BTV TM_FINAL.docx

Background Threshold Values for Groundwater August 16, 2017
Roxboro Steam Electric Plant
TABLES
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 72017\13TV TECH
MEMO \ Roxboro \ Groundwater \ FINAL \ Roxboro - GW BTV TM_FINAL.docx

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH JANUARY 2017
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
P:\Duke Energy Progress.1026\St,ti,tics_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Roxboro\Groundwater\FINAL\TABLE 1 - Roxboro BG GW )—_—i.ed Page t of I
t, Alk,li,ity
oo��000�0000�o©o���000000
oo��00000000©000��000©000
����eeeeeeeeeeeeeeeeeeeee
oo��©000©o©000®o®®o©000®o
000®00000000©�©o®moo©o©o©o
oo®��00000©moo©o®oo®00000
oo®�00000000©o©o®moo©o©000
����eeeeeeee�eeeeeeeee�ee
oo��000®®o©o©�00000©�®000
oo®000®0000®�©o®o®000®oma
P:\Duke Energy Progress.1026\St,ti,tics_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Roxboro\Groundwater\FINAL\TABLE 1 - Roxboro BG GW )—_—i.ed Page t of I

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH JANUARY 2017
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ My 7 2017\BW TECH MEMO\Roxboro\Groundwater\FINAL\TABLE 1 - Roxboro BG GW Data_-ised Page 2 of 4
Analytical Parameter
Methane
Molybtlenum
Nickel
Nitrate+ Nitrite
Pptassium
Selenium
Sodium
Strontium
Sulfate
5ui1itle
Thallium
Total Dissolved Solids
Total Organic Carbon
Vanatlium
Zinc
Radium (Total)
Uranium (Total)
Reporting Units
ug/L
ug/L
ug/L
mg-N/L
mq/L
up/L
mg/L
ug/L
mg/L
mg/L
uq/L
mq/L
mg/L
uq/L
uq/L
pCi/L
ug/mL
15A NCAC 02L Standard
NE
NE
loo
NE
NE
20
NE
NE
25o
NE
o.2�
500
o.3*
1000
NE
NE
Sample ID
Sample
Collection Date
Analytical Results
Transition Zone
BG-Ol
11/30/2010
-
-
<5
-
-
<38
-
-
12.5
-
<0.1
299
-
-
12.3
---
- -
B - 1
1
-
-_
17.4
-
___
-
-
1
___
<0.1
282
___
_ .
-
-
---
---
BG -01
07/13/2011
-
-
45.1'.-B
-
-
HB
-
-
11.6 B
-
<0.1
248 B
----
BG-01
11/02/2011
-
-
12
-
-
HB
-
-
12.4
-
<0.1
263 B
-
-
<SO
---
---
BG-01
04/02/2012
-
-
<5
-
-
<30
-
-
11.7
-
<0.1
298
-
-
<10
- -
---
86-01
07/11/2012
-
-
c5
-
-
H6
-
-
14.2
-
<0.1
312
-
-
c10
---
---
86-01
11/06/2012
-
-
6.2
-
-
<30
-
-
14.3
-
<0.1
300
-
-
<10
---
---
EG -01
04/08/2013
-
-
-
__
<I
-
-
11
-0.2
310
-
-
5
BG -01
07/08/2013
-
-
6
-
-
<1
-
-
12
-
<0.2
330
-
-
15
---
---
BG-01
11/11/2013
-
-
c5
-
-
<I
-
-
12
-
<0.2
320
-
-
12
---
---
BG-01
04/03/2014
-
-
<5
-
-
<1
-
-
13
-
<0.2
320
-
-
15
---
---
BG-01
07/15/2014
-
-
c5
-
-
<I
-
-
14
-
<0.2
330
-
-
c5
---
---
BG-01
11/12/2014
-
-
7
-
-
<I
-
-
13
-
<0.2
310
-
-
11
---
---
BG-01
04/16/2015
-
3.04
c5
-
3.44
3.57
35.4
--
40
--
<0.2
370
--
-
7
---
---
BG -OS
09/16/2015
<10
<1
1.96
1.9
1.52
1.44
30.5
414
27
<0.1
0.231
32(1
0.672
22.7
14
---
---
86-01
:'�fe5r'>:e'n
�-F0
0.65
}3
25
K
}-2
324
44g
28-6
HB:1
EPt
333
H
343
H0
---
-..
EG-
01/05/2016
<10
<1
2.96
2.6
1.87
1.01
31.6
445
23
<0.1
<0.2
350
0.579
17.5
<5
---
EG -01
04/07/201604/07/2016
c10
<1
5
2.7
1.65
1.78
31.5
436
24
<0.1
<0.2
330
0.704
24.4
<5
5.45
0.000661
BG -01
07/12/2016
130 12,CL
11
15
2.6
1.94
<i
31.8
442
21
-A
<0.2
330
0.682
18.3
15
2.23
0.000674
86�}
<-ib
H
}.9F
23
lT'O
c}
300.
443
<0;}
E8.-2
330
033
19,8
6
214
B,BB063;<
BG-Ol
11/01/2016
--
<1
15
--
1.86
<1
32.1
442
20
<0.2
340
- -
18.8
BG -01
11/10/2016
c10 N2
<S
2.59
2.3
1.92
<1
30.3
457
19
<0.1
<0.2
340
0.764
15.8
<5
---
---
BG-01
11/16/2016
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2
0.000624
BG -01
01/26/2017
c10 N2
<1
1.61
2.4
1.81
ci
30.8
456
IB
<0.1
c0.2
320
0.735
18.7
c5
2
0.00035
MW -1513
05/30/2015
<30
1.11
20.8
2.9
1.09
<1
28.4
243
29
<0.1
<0.2
410
1.1
4.96
<5
- -
---
MW-i5D
09/12/2015
<10
<1
16.7
3.4
1.11
<1
29.2
241
28
<0.1
c0.2
400
0.925
7.66
c5
---
---
MW -33B
-
<-45
133
33
K
<-45
29-2
246
243
-
-
421
}.-2
63
<38
MW -1513
01/05/2016
c10
cl
15.2
3
cl
<3
26.3
231
24
<0.1 MI
<0.2
430
0.935
8.03
<5
---
---
MW -151)
06/23/2016
<10
<1
11.5
3.6
1.05
<3
28.9
239
29
<0.1
<0.2
430
1.1
9.15
<5
2
0.000823
MW -}5p
3e
<}8
<}
i -h9
33
398
<}
364
248
33
E41
<6...
420
}:}
936
K
1-664
6:666855
MW -15D
09/08/2016
<10
<1
10.9
3
1.04
<3
28.1
241
29
<0.1
<42
410
1
9.36
<5
3.762
0.000831
MW -15D
11/09/2016
<10 N2
1.56
11.1
3.2
1.02
<1
27.1
242
30
<0.1
<0.2
400 Hl
1
9.73
<5
1.773
0.000915
MW -15D
01/25/2017
<30 N2
1.78
9.12
3.4
1.11
<1
28.4
246
29
<0.1
<42
420
1.1
9.4 E2
<5
1.221
0.000898
MW --186
H6
84
3
0.21
5-.6.+1
23
326
6;<8
43-}
<9-.1
e41
554
2-1-141
3-7
<..t0
-
-
MW -18D
01/05/2016
<10
6.08
<1
0.198
2.96
1.64
21.9
629
39
<0.1
<0.2
610
2.4
1.1
8
---
- -
MW�BB
H6
,.93
2%
0.-201
4:32
3-25
21:5
Nag
3J
EP1
<+).2
640
1-:8
3.33
<-
2i-2
6.80449
MW -181)
07/14/2016
<10
1.44
4.13
0.102
4.28
<S
27.9
730
37
<0.1
<0.2
540
1.9
0.551
<5
3.36
0.00516
MW -IBD
09/13/2016
<10
4.17
<i
0.125
3.87
<3
25.8
760
31
<0.1
c0.2
540
1.7
1.23
<5
2.183
0.00396
MW -18D
01/25/2017
<10 N2
149
<S
0.209
4.13
<S
28.3
767
33
<O.1
<0.2
6.0
1.7
1.35 62
<5
1.535
0.00402
Bedrock
BG-OSBR
06/10/2015
<10
16.5
1.86
o-94
5.36
<1
36.4
183
28
<0.2
<0.2
350
1.3
1.94
44
---
- -
BG-03BR
07/09/2015
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
2.41
0.00137
BG-DlBR
09/12/2015
<10
5.36
1.3
0.089
5.51
<1
24.6
160
20
<0.1
<0.2
300
1
0.425
23
---
--
86-01814
}2(OSF2&K
HB
3:2
634
iia
e8:i
23
}60
i3
<0.}
ems}
297
33.6
�-1
HB
-
---
BG-016R
01/05/2016
<lo
9.26
2.1
0.295
5.09
<I
21.9
163
21
<0.1
<0.2
330
0.693
1.25
53
---
--
BG-01BR
04/07/2016
29.6
7.42
1.45
0.192
5.18
<3
23.5
166
20
<0.1
<0.2
300
0.703
1.23
6
1-
0.001082
5G-01BR
07/14/2016
1120
4.18
1.08
0.229
5.54
<3
20.5
162
20
<0.1
<42
300
0.795
1.67
7
2
0.001111
86-0}BR
09/e0r28}e
til&
Z38
}.}5
639
5r.
i -F
224-M4
3}i
20
<0:.1
<0.1
260
Gam.
44
K
2
090}6}3
BG-DlBR
11/09/2016
569 N2
5.11
1.34
0.381
5.1
<S
21.8
169
19
<0.1
<0.2
330
0.773
1.79
15
2.09
0.00099
BG-01BR
01/25/2017
367 N2
7.57
1.1
0.43
5.29
<1
24.2
183
19
c0.1
<0.2
330
0.849
2.34 B2
c5
2
0.00137
MW-10BR
05/27/2015
<10
24.1
2.44
0.225
9.05
11
36.5
194
40
<O.1
<0.2
350
1.1
2.09
<5
--
---
MW-10BR
09/12/2015
c10
24.3
<1
0.083
9.28
<1
37.6
201
40
c0.1
<0.2
350
1
1.34
c5
---
-
MW-1o8R
<iB
2�3
<-k
8-039
939
<3
37-5
396
44
E&2
E&2
338
8:342
H
K
-
-
MW -1080.
01/06/2016
c10
22.7
<i
0.049
9.21
<3
36.7
196
42
<0.1
c0.2
370
0.902
1.28
<5
---
---
MW-10BR
04/07/2016
<30
19
<3
0.136
8.41
<3
37.2
181
41
<0.1
<0.2
330
0.952
1.51
cit
3.771
0.00324
MW-IOBR
07/14/2016
c10
19.2
<1
0.082
30
c1
40
191
41
<0.1
<0.2
340
0.993
1.68
c5
2.49
0.00316
MW-10BR
09/14/2016
<30
18.4
<3
0.152
9.11
<3
36.7
188
41
<0.1
<0.2
826
1.1
2.04
<5
1.621
0.00293
lOW--4080.
+1{Oq/?616
H6Ii2
+"
N
o 2.
i %
F3
$5;6
360
12
<9-.1
<0.2-82
236
6992
266
K
1-716
600305
MW -1060.
01/26/2017
<10 N2
16.3
<S
0.213
8.1
<S
37
176
40
<0.1
<0.2
330
0.966
2.91
<5
2
0.00324
MW-13BR
05/3D/2015
c10
1.33
1.22
0.17
4.62<3
35.6
409
30
<0.1
c0.2
380
4
0.364
15
---
---
MW-13BR
09/13/2015
30
1.35
1.06
0018
5.33
<i
35.9
411
18
429
<0.2
370
4.2
0.819
MW -13.
}2{85{28}5
441
0.82
0:78
io92
619
E8:511
1
}(,7B:
A3
<Pi
390
-
<-1--
MW-13BR
01/06/2016
40.6
1.09
1.07
0.017
5.6
<I
39.8
416
29
<0.1
<0.2
420
3.8
0.398
32
--
---
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ My 7 2017\BW TECH MEMO\Roxboro\Groundwater\FINAL\TABLE 1 - Roxboro BG GW Data_-ised Page 2 of 4

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH JANUARY 2017
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Prepared bv: JHG Checked bv: RHJ
Notes.
Sa - Indicates value omitted from dataset.
Indicates parameter not measuredor analyzed.
Indicates data removed/identified as an outlier
- mmtares data removed due ro autocorrelation
< - concentration not detected at or above the adj—d reporting limit. pCi/L - picocufies per liter
mg - N/L - Milligrams nitrogen per liter S.U. - Standard Unit
mg/I- - Milligrams per liter ug/L - Micrograms per liter
NE - Not established ug/mL - micrograms per milliliter
NTU - Nephelometric turbidity unit
* - Intenm Maximum Allowable Concentrations (LMAC,) of the ISA NCAC 02L Standard, Appendix 1, April, 1, 2013.
B - Target analyte detected in method blank at or above the reporting limit. Target analyte concentration in sample m less than 10X the concentration in the method blank. Analyte concentration in sample could be due to blank contamination.
B1 - Target analyte detected In method blank at or above the reporting Ilmit. Target analyte concentration in sample was greater than 1OX the concentration In the method blank. Analyte concentration In sample is not affected by blank contamination.
B2 - Target analyte was detected in blank(,) at a ,ncent,.ti.n greater than 1/2 the reporting limit but less than the reporting limit Analyte concentration in sample m valid anti may be used for compliance purposes.
CH The continuing wIib,.ti.n for this compound is outside of Pace Analytical acceptance limits. The results may be biased high.
CL- The continuing calibration for this compound is .—ice of Pace Analytical acceptance limits. The results may be biased low.
D3 mwas - Saple diluted due to the presence of high levels of non -target analytes or other matrix intefferente.
HI - Analysis conduded o,t,ide the EPA method holding time.
j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
0 - Analyte recovery in the laboratory control sample (l -CS) exceeded quality control (QC) limits. Analyte presence below reporting limits in associated samples. Results unaffected by high bias.
M1 - Matrix spike rerovery was high: the associated Laboratory Control Spike (LCS) was acceptable.
M2 - Matrix spike rerovery was Low: [he associated Laboratory Control Spike (LCS) was acceptable.
M4 - The spike recovery value was unusable since the analyte concen-twn in the sample was disproportionate tc the spike level. The associated Laboratory Control Spike recovery was acceptable.
M6 -Matrix spike and Matrix spike duplicate recovery not evaluated against control limits due to sample dilution.
N2 - The lab does not hold accreditation for this p—nneter.
P2 - Re -extraction or re -analysis could not be pefformed due to insufficient sample amount.
RI - Relative Percent Difference (RPD) value was outside control limits.
S - Assonated calibmtlon check did not meet specified trite...
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Roxboro\Groundwater\FINAL\TABLE 1 - Roxboro BG GW Data_revised Page 3 of 4
A ly P—nnete]
P.
Tulthi,ity
A—li-fly
A—munn
—i—y
A—i.
..H--
'I-
t, Alk,li,ity
Boron
C.—m.
le All,.Iimil,
Ch-ide
Ch--iu-
C-11
CoPP-
Lend
-cine-nn
Men—...
Me—,,
oOAAoo®©0000®o®oOoo®o®o©O
DO®A®0®®®0®0©0®000®0®®0
oO�A�oo®0000©moo©000®�©�®®
oo��®oo�oo©000®oma®o®o��o®
mo®�oo��m���oo®©o®o®mono®
oo��oo��o�00000®000©0000®
oo®moo©�0000©o®0000000000
oo®000®0000©o©0000©oo®oo
Prepared bv: JHG Checked bv: RHJ
Notes.
Sa - Indicates value omitted from dataset.
Indicates parameter not measuredor analyzed.
Indicates data removed/identified as an outlier
- mmtares data removed due ro autocorrelation
< - concentration not detected at or above the adj—d reporting limit. pCi/L - picocufies per liter
mg - N/L - Milligrams nitrogen per liter S.U. - Standard Unit
mg/I- - Milligrams per liter ug/L - Micrograms per liter
NE - Not established ug/mL - micrograms per milliliter
NTU - Nephelometric turbidity unit
* - Intenm Maximum Allowable Concentrations (LMAC,) of the ISA NCAC 02L Standard, Appendix 1, April, 1, 2013.
B - Target analyte detected in method blank at or above the reporting limit. Target analyte concentration in sample m less than 10X the concentration in the method blank. Analyte concentration in sample could be due to blank contamination.
B1 - Target analyte detected In method blank at or above the reporting Ilmit. Target analyte concentration in sample was greater than 1OX the concentration In the method blank. Analyte concentration In sample is not affected by blank contamination.
B2 - Target analyte was detected in blank(,) at a ,ncent,.ti.n greater than 1/2 the reporting limit but less than the reporting limit Analyte concentration in sample m valid anti may be used for compliance purposes.
CH The continuing wIib,.ti.n for this compound is outside of Pace Analytical acceptance limits. The results may be biased high.
CL- The continuing calibration for this compound is .—ice of Pace Analytical acceptance limits. The results may be biased low.
D3 mwas - Saple diluted due to the presence of high levels of non -target analytes or other matrix intefferente.
HI - Analysis conduded o,t,ide the EPA method holding time.
j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
0 - Analyte recovery in the laboratory control sample (l -CS) exceeded quality control (QC) limits. Analyte presence below reporting limits in associated samples. Results unaffected by high bias.
M1 - Matrix spike rerovery was high: the associated Laboratory Control Spike (LCS) was acceptable.
M2 - Matrix spike rerovery was Low: [he associated Laboratory Control Spike (LCS) was acceptable.
M4 - The spike recovery value was unusable since the analyte concen-twn in the sample was disproportionate tc the spike level. The associated Laboratory Control Spike recovery was acceptable.
M6 -Matrix spike and Matrix spike duplicate recovery not evaluated against control limits due to sample dilution.
N2 - The lab does not hold accreditation for this p—nneter.
P2 - Re -extraction or re -analysis could not be pefformed due to insufficient sample amount.
RI - Relative Percent Difference (RPD) value was outside control limits.
S - Assonated calibmtlon check did not meet specified trite...
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Roxboro\Groundwater\FINAL\TABLE 1 - Roxboro BG GW Data_revised Page 3 of 4

TABLE 1
BACKGROUND GROUNDWATER RESULTS THROUGH JANUARY 2017
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Prepared by: JHG Checked by: CDE
Notes.
Sa - Intlicates value omitt,d from d,taset.
Intlicates parameter not measured or enaly.d.
Indicates tlata removetl/d entitled as an outlier
- mmcares tlata --ed due ro autocoralation
< - concentration not detected at or above the atljustetl reporting limit. pCi/L - picvcurles 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 ISA NCAC 02L Standard, App-dix 1, April, 1, 2013.
B - Target analyte detected in methotl blank at or above the reporting limit. Target analyte concentration fn sample m less than 10X the concentration in the methotl blank. Analyte concentation in sample could be due W blank contamination.
Bt - Target analyte detected m method blank at or above the reporting Ilmit. Target analyte concentration in sample was greater than 1OX the concentration In the method blank. Analyte concentration In sample is not aff,,Id by blank mntaminabon.
B'- Target analyte was detected m blank(s) at a ronc,nhation greater than 1/2 the reporting limit but less than the reporting limit. Analyte concentration m sample m -lid antl may be —d for compliance purposes.
CH - The continuing calibration for this compountl is outside of Pace Analytical acceptance limits. The results may be biasetl high.
CL - The continuing calibration for this compountl m —id. of Pace Analytical acceptance limits. The results may be biasetl low.
D3 - Sample was diluted due to the presence of high levels of non -target analytes or other matrix interference.
HI - Analysis conducted outsitle the EPA methotl holding time.
j - Estim—d concentration above the atljustetl methotl detection limit antl below the atljustetl reporting limit.
0 - Amalyte recovery m the laboratory control sample (I -CS) exteeded quality control (QC) limits. Analyte presence below reporting limits in associated samples. Results unaffected by high bias.
M1 - Matrix spike rerovery was high: the associated Laboratory Control Spike (I -CS) was acceptable.
M2 - Matrix spike rerovery was Low: [he associated Laboratory Control Spike (I -CS) was acceptable.
M4 - The spike recovery value was unusable sloe, the analyte concentation in the sample was disproportionate W the spike level. The associated Laboratory Control Spike recovery was acceptable.
M6 -Matrix spike and Matrix spike duplicate recovery not evaluated against control limits due to sample dilub—
N2 - The lab does not hold accreditation for this paamete,
P2 - Re -extraction or re -analysis could not be performed due to insufficient sample amount.
RI - Relative Percemt Difference (RPD) value was outside control limits.
S - Assonated calibration check did not meet specified criteria.
P:\Duke Energy Progress.1026\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Roxboro\Grountlwater\FINAL\TABLE 1 - Roxboro BG GW Data_revised Page 4 of 4

TABLE 2
GROUNDWATER BACKGROUND THRESHOLD VALUES
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, NC
Parameter
Reporting Unit
NCAC 02L Standard
Background Threshold Values
Transition Zone Bedrock
pH*
S.U.
6.5-8.5
6.3 -7.6
6.8 -8.3
Alkalinity
mg/L
NE
243
273
Aluminum
pg/L
NE
1059
174
Antimony
pg/L
18
ND
ND
Arsenic
pg/L
10
ND
ND
Barium
pg/L
700
91
182
Beryllium
pg/L
4°
ND
ND
Bicarbonate
mg/L
NE
243
273
Boron
pg/L
700
ND
ND
Cadmium
pg/L
2
ND
ND
Calcium
mg/L
NE
127
102
Carbonate
mg/L
NE
ND
ND
Chloride
mg/L
250
150
120
Chromium (VI)
pg/L
10
17
1
Chromium
pg/L
10
26
4
Cobalt
pg/L
18
2
11
Copper
pg/L
1000
10
2
Iron
pg/L
300
1141
5339
Lead
pg/L
15
ND
ND
Magnesium
mg/L
NE
42
31
Manganese
pg/L
50
405
1196
Mercury
pg/L
1
ND
ND
Methane
pg/L
NE
ND
367
Molybdenum
pg/L
NE
6
36
Nickel
pg/L
100
19
2
Nitrate + Nitrite
mg-N/L
NE
3
0.3
Potassium
mg/L
NE
5
10
Selenium
pg/L
20
10
ND
Sodium
mg/L
NE
36
38
Strontium
pg/L
NE
767
268
Sulfate
mg/L
250
37
48
Sulfide
mg/L
NE
ND
ND
TDS
mg/L
500
600
530
Thallium
pg/L
0.2°
ND
ND
TOC
mg/L
NE
2
4
Vanadium
pg/L
0.3°
29
3
Zinc
pg/L
1000
12
51
Radium (Total)
pCi/L
NE
5
4
Uranium (Total)
pg/mL
NE
0.004
0.004
Prepared by: JHG Checked by: CDE / LWD
Notes:
Transition Zone background wells: BG -1, MW -15D, and MW -18D
Bedrock background wells: BG-1BR, MW-10BR, MW-14BR, MW-15BR, MW-18BR, and MW-19BRL
* - Upper and lower tolerance limits calculated for parameter
A - Interim Maximum Allowable Concentrations (IMACs) of 15A NCAC .021- Standard, Appendix 1, April 1, 2013
mg/L - milligrams per liter
ND - Not Detected
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\Roxboro\Groundwater\FINAL\TABLE 2 - Roxboro GW BG Threshold Values
Page 1 of 1