Mayo Background Soil Tech Memo Dec 2016_20171005

TECHNICAL MEMORANDUM
Date: December 15, 2016 File: 1026.105.19
To: Kimberlee Witt (Duke Energy)
Cc: Kathy Webb SynTerra)
From: Jerry Wylie
Subject: Quantification f Valid Background Soil Samples for Statistics Calculations —
Mayo Steam Electric Plant
Proposed Preliminary Background Threshold Values (PPBTVs) for site soils will be calculated
for CAMA assessment constituents. Soil samples were collected from soil borings during the
Comprehensive Site Assessment (CSA) field activities at the Mayo Steam Electric Plant (Site) in
2015. Table 1 provides a summary of the samples (locations and depth intervals) which are
considered for use in statistical calculations to determine concentrations of naturally occurring
(background) inorganic constituents in Site soil. Figure 1 indicates the location of soil samples
to be used for statistical calculations.
Soil samples that meet the following criteria are considered valid for use in the statistic
calculations for background concentrations:
0 Soil sample is collected from a location that is not impacted by coal combustion
residuals or coal associated materials;
0 Soil sample is collected from a location that is not impacted by other potential
anthropogenic sources of constituents; and
Ei Soil sample is collected from the unsaturated zone, >_ 1 foot above the seasonal high
water table elevation.
Based on the minimum eight sample dataset requirement provided in the Pro UCL guidance
document, no additional background soil samples are projected for the Site.
The analytical results in Table 1 for antimony, arsenic, cobalt, selenium, and thallium present
reporting limits that are greater than the PSRG for Protection of Groundwater (POG) for some
or all samples 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.
The statistical calculation process will include a review of data to determine if outliers exist.
Professional judgment can be used to retain data that does not satisfy one or more of the valid
soil sample criteria. Likewise, professional judgement can be used to reject soil sample data
that does satisfy all valid soil sample criteria. However, the decision to retain data that does not
satisfy valid soil sample criteria, and the decision to reject data that satisfy valid soil sample
P: \ Duke Energy Progress.1026 \ 105. Mayo Ash Basin GW Assessment Plan \ 19.EG_CSASUP \ Statistics \ Background
Soil Dec 2016\MAYO BG Soil Tech Memo FINAL 1215 2016.docx

Quantification of Valid Background Soil Samples for Statistics Calculation December 15, 2016
Mayo Steam Electric Plant
Page 2 of 2
criteria, must be documented. A revised Background Soil Data Summary table will be provided
following review of updated analytical reports.
ATTACHMENTS:
Table 1: Background Soil Data Summary
Figure 1: Background Soil Locations for Statistical Analysis
P: \ Duke Energy Progress.1026 \ 105. Mayo Ash Basin GW Assessment Plan \ 19.EG_CSASUP \ Statistics \ Background
Soil Dec 2016\MAYO BG Soil Tech Memo FINAL 1215 2016.docx

TABLE 1
BACKGROUND SOIL DATA SUMMARY
MAYO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, ROXBORO, NC
Analytical Parameter
pH
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chloride
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Nitrate
(as N)
Potassium
Selenium
Sodium
Strontium
Sulfate
Thallium
Vanadium
Zinc
Reporting Units
S.U.
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
mg/kg
PSRG Protection of Groundwater
NE
NE
0.9
5.8
580
63
45
3
NE
NE
360000
0.9
700
ISO
270
NE
65
1
NE
130
NE
NE
2.1
NE
NE
NE
0.28
6
1200
Sample ID
Sample Collection
Date
Sample Depth
Elevation (ft.)
Water Table
Elevation (ft.)'
Analytical Results
MW-03BR (0.8-1.25)
02/05/2015
434
423.68
5.0
7030
<3
<3
57.6
0.341
<3
<0.36
332
<299
11.3
5.4
6.3
8480
3.3
2500
327
0.013
<6
5.1
<29.9
1070
<3
<59.7
5.4
<299
<3
16
25.3
MW-08BR (0.75-1.25)
02/11/2015
466
433.17
6.0
14500
<3.2
<3.2
147
0.82
<63.4
<0.38
1120
<309
62.2
21.3
34.7
24700
8.9
10500
1230
<0.0096
<12.7
29.4
<30.9
6590
<3.2
<1270
13.2
<309
<3.2
50.6
88.9
MW-08BR (25.5-26)
02/11/2015
441
433.17
7.4
23700
<2.7
<2.7
193
0.39
31 j
<0.33
3740
<272
419
32.9
45.7
31300
2 j
29900
933
'0.0089
<10.9
157
<27.2
S4SO
<2.7
173
33.6
<272
<2.7
75.8
59.4
MW-IOBR (0.75-1.0)
02/23/2015
S12
501.37
6.3
7640
<1.1
1.4
81.8
0.4
13.6 j
0.1 j
1210
NA
41.9
12.4
28.9
18600
9.8
SS90
527
O.00S3 j
<0.57
16.3
NA
2660
1.4
93.4
9.4
NA
<1.1
35.1
61.3
MW-11SR (0-2)
04/14/2015
522
492.41
5.2
19700
<7.5
<7.5
43.1
<0.38
<18.8
<0.89
1690
<354
22.6
6.4 j
59.1
52900
6.1 j
1590
52.6
0.13
<3.8
1.4 j
<35.4
<376
<7.5
<376
18.6
<354
<7.S
208
17.2
MW-12D (1-2)
04/26/2015
586
558.78
4.9
11000
<6
3.6 j
19.6
<0.3
27.4
<0.72
<ISO
<302
43.6
<6
12.4
31200
6.8
139 j
22.1
0.036
<3
0.83 j
<30.2
182 j
<6
<299
<3
<302
<6
61
5.2 j
MW-12D(25-26)
04/27/2015
562
558.78
5.9
3530
<6
<6
67.4
<0.3
9.8j
<0.72
<149
<301
3.2
6
22.4
11900
7.2
1190
39S
<O.0095
<3
<1.S
<30.1
1520
<6
<299
<3
<301
<6
8.2
15
MW-13BR (0-2)
04/12/2015
525
500.13
4.9
IS500
<6.5
<6.5
72.9
0.33
<16.3
<0.78
38.1
<334
6.1
<6.S
10.9
19600
6.2 j
1840
82.8
0.029
0.42 j
0.53
<33.4
1360
<6.5
<65.1
1.8
<334
<6.5
32.4
25.4
MW-1SBR(O.S-1)
OS/09/2015
460
409.01
5.2
8440
<6.2
<6.2
64.6
0.241
<15.5
<0.74
451
<305
10.4
3.9j
12.5
15600
4.7j
3760
108
O.00S6j
<3.1
1.3j
<30.5
1370
<6.2
<309
11.2
<305
<6.2
27.1
18.9
SB-01(1-2)
03/04/2015
525
Not encountered
6.3
7030
<1.4
1.2j
49.6
0.24
9.6
<0.17
65S
<362
15.7
3.7
8.8
12400
9.6
1670
104
0.033
<0.7
2.5
<36.2
881
<1.4
3S.4j
6
<362
<1.4
28.3
14.5
SB-01(13.5-14.5)
03/04/2015
S13
Not encountered
S.S
4960
<1.3
1.2j
61.5
0.56
<15.9
<0.15
270
<312
<1.6
8.9
20.6
8490
2.9
2440
678
<0.01
<3.2
<1.6
<31.2
1550
1.4
40.71
8.3
<312
<1.3
17.8
13.2
SB-02 (0.5-2)
03/03/2015
SS3
Not encountered
S.3
10200
<1.6
1.9
65.7
0.52
16.3 j
0.13 j
227
<392
12.9
6.4
22.8
18300
7.5
2420
365
0.02
<0.8
1.7
<39.2
2020
1.3 j
<79.8
4.3
<392
<1.6
44.8
27.3
SB-02 (11.0-12.5)
03/03/2015
S43
Not encountered
6.0
5930
<1.2
1.S
31.3
0.39
7.8
<0.15
22.2 j
<309
10.8
1.6
5.5
10300
4.8
1070
69.4
<0.0096
0.89
0.91
<30.9
800
0.85 j
30.9 j
1.1
<309
<1.2
23.8
14.9
SB-03 (S-6)
03/04/2015
SSO
Not encountered
8.6
5030
<1.1
0.64 j
SS.2
0AS
S.7
0.094 j
1420
<272
20.7
4.9
14
8070
2.4
3810
348
0.0096
1.1
7.7
<27.2
29SO
<1.1
104
11
<272
<1.1
15
30.8
SB-03(17-18.5)
03/04/2015
537
Not encountered
4.9
11800
<1.5
1.6
51.4
0.26
12.9
<0.18
208
<360
35.6
5.2
15.5
18100
8.2
4250
120
<0.012
<0.75
10.9
<36
2410
<1.5
40.91
4.4
<360
<1.S
38.4
32.4
SB-OS (1-2)
03/04/2015
496
Not encountered
6.0
5320
<1.4
1.8
47.1
0.36
<17
0.12 j
313
<346
<1.7
2.8
11.1
8280
5.4
1940
406
<0.011
<3.4
<1.7
<34.6
1730
1.9
<340
4.2
<346
<1.4
6.8
36.3
SB-OS (2.3-3.3)
03/04/2015
495
Not encountered
5.9
3510
<1.1
1.1
40.9
0.35
<13.5
0.0911
189
<271
<1.4
1.7
3.9
6670
5.5
1660
393
<0.0086
<2.7
<1.4
<27.1
1550
1.2
<271
5.2
<271
<1.1
5.9
31.6
SB-OS (8-9)
03/04/2015
489
Not encountered
6.S
1480
<1.1
1 j
22.2
O.S
<13.7
<O. 13
81.4
<272
<1.4
2.2
43.8
5790
11.8
368
195
<0.0093
0.36 j
<0.27
<27.2
111
0.87 j
46.7 j
3.1
<272
<1.1
4.8
12.3
SB-06 (1-2)
03/04/2015
509
Not encountered
S.9
2510
<1.3
1.2 j
54.8
0.17
2.9 j
<O.1S
<3 .1
<309
0.74
2.5
13.1
3920
4.2
816
192
10.0093
<0.64
O.SS
<30.9
801
0.9 j
67.2
4.1
<309
<1.3
2.7
14.7
Total Count of Valid Samples
19
19
0*
15
19
19
18
19
19
18*
19
1.7
19
19
19
1919
19
19
19
18*
19
11
19
19
Is*
0*
19
19
Prepared by: RKD Checked by: JAW
Notes:
ncentration or detection limit greater than PSRG Protection of Groundwater Standard
mg/kg = milligrams per kilogram
NE = Not established
S.U. = Standard Units
j = Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit.
< = concentration not detected at or above the adjusted reporting limit.
NA = Not analyzed
* = No detectable concentrations within data set
PSRG Protection of Groundwater = NCDEQ IHSB Preliminary Soil Remediation Soil Remediation Goals Table - October 2016
- Water table elevations collected during site -wide well gauging event on June 23-24, 2016.
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