Roxboro Background Soil Tech Memo_20161215

TECHNICAL MEMORANDUM
Date: December 15, 2016 File: 1026.107.20B
To: Kimberlee Witt (Duke Energy)
Cc: Kathy Webb (SynTerra)
From: Craig Eady
Subject: Quantification of Valid Background Soil Samples for Statistics Calculations
Roxboro 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 Roxboro Steam Electric Plant (Site)
in 2015. Table 1 provides a summary of the samples (sample locations and depth elevations)
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:
,01 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 ft. 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 presented in Table 1 for antimony (16 results), arsenic (8 results), cobalt (3
results), selenium (11 results), thallium (15 results), and vanadium (1 result) present laboratory
reporting limits that are greater than the PSRG for Protection of Groundwater (POG) 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 \ 107. Roxboro Ash Basin GW Assessment Plan \ 19.EG_CSASUP \ DEQ Request
12_2016\BG Soil Tech Memo.docx

Quantification of Valid Background Soil Samples for Statistics Calculations December 15, 2016
Roxboro 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 Statisitical Analysis
P: \ Duke Energy Progress.1026 \ 107. Roxboro Ash Basin GW Assessment Plan \ 19.EG_CSASUP \ DEQ Request
12_2016\BG Soil Tech Memo.docx

TABLE 1
BACKGROUND SOIL DATA SUMMARY
ROXBORO STEAM ELECTRIC PLANT
DUKE ENERGY PROGRESS, LLC, SEMORA, 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
0.9
5.8
580
63
45
3
NE
NE
360000
0.9
700
150
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 1
Elevation (ft.)
Analytical Results
MW-07(0-2)
04/15/2015
473
464.85
6.2
32800
<7.8
<7.8
87.5
0.76
<19.5
<0.94
2100
<371
24.1
21.4
77.3
49400
4.1j
3610
358
0.038
<3.9
5.9
<37.1
<390
<7.8
<390
20.2
<371
<7.8
177
24.4
MW-08 (0-2)
04/27/2015
478
443.23
5.7
5680
<6.9
<6.9
52.7
0.28 j
<17.2
<0.83
846
<336
1.5 j
3.5 j
20.2
11200
<6.9
2920
87.4
<0.011
<3.4
2.9
<33.6
206 j
<6.9
235 j
14.6
<336
<6.9
21.8
34
MW-08(14-16)
04/27/2015
464
443.23
7.6
4110
<5.2
<5.2
49.3
0.23j
<13.1
<0.63
1830
<263
0.82j
4.6j
2.4
10200
<5.2
2910
222
<0.0086
<2.6
1.4
<26.3
836
<5.2
221j
13.7
<263
<5.2
21.6
41.4
MW-08(21-23)
04/27/2015
457
443.23
7.3
14800
<5.7
<5.7
128
1.1
<14.2
<0.68
11200
<283
17.4
15.3
0.78j
20500
6
14300
496
<0.0092
<2.8
34.7
<28.3
5680
<5.7
211j
97.2
<283
<5.7
43.1
78.6
MW-10BR (0-2)
04/07/2015
531
514.13
5.6
18200
<7.2
<7.2
42.3
0.45
<18
<0.86
723
<359
10.7
5.6 j
10.9
31400
6.7 j
1530
57.8
0.018
<3.6
1.8j
<35.9
<359
<7.2
<359
8.3
<359
<7.2
94.7
20.1
MW-13BR (0-2)
03/04/2015
548
513.47
4.8
12100
<1.3
<1.3
28.7
0.092
8.9
<0.16
153
<322
4.2
1.9
6.8
13200
3.1
2970
51.5
<0.011
<0.65
1.4
<32.2
384
<1.3
84.5
4.4
<322
<1.3
30.4
20.2
MW-13BR (22-24)
03/04/2015
526
513.47
8.0
6730
<1.2
<1.2
102
0.14
9.2
<0.14
3890
<299
8.7
8.1
41
13100
<1.2
4020
132
<0.01
<0.6
4.4
<29.9
2320
<1.2
389
13.2
<299
<1.2
59.3
25.1
MW-14BR (1-1.25)
02/25/2015
509
463.36
4.8
11000
<1.2
<1.2
71.3
0.14j
<3.1
<0.15
593
<300
4.1
5.3
11.1
16100
4.8
4960
79.4
0.011
<0.62
3.4
<30
1110
<1.2
183
20.4
<300
<1.2
45.2
26.6
MW-14BR(31-31.5)
02/25/2015
479
463.36
8.8
8590
<1
<1
170
0.11j
<2.6
<0.12
2810
<254
9
8.6
23.1
12600
<1
6490
238
<0.0084
<0.51
6.5
<25.4
4830
<1
383
22.4
<254
<1
31
37.9
MW-14BR (37.5-38)
02/25/2015
473
463.36
8.0
12300
<1.1
<1.1
198
0.25
<2.8
<0.13
6340
<286
54
15.8
17.7
15200
<1.1
13100
290
<0.0089
<0.55
53.7
<28.6
3860
<1.1
174
57.5
<286
<1.1
33.3
49.6
MW-15 (0-2)
04/17/2015
503
500.40
5.5
26000
<6.6
<6.6
81.4
0.48
30.9
<0.79
2160
<335
120
26.3
49.7
50500
8.5
3340
230
0.027
<3.3
58.7
<33.5
244j
<6.6
<331
18.2
<335
<6.6
201
20.3
MW-16(0-2)
04/06/2015
516
491.18
7.7
13500
<6
<6
210
0.43
<14.9
<0.72
1530
<290
10.6
20.7
84.1
23700
<6
6440
168
<0.0092
<3
9.1
<29
1970
<6
250j
23.2
<290
<6
43.6
41.3
MW-17 (29-31)
04/21/2015
501
497.00
8.4
8530
<5.1
<5.1
84.3
0.32
17.9
<0.61
5300
<250
4.8
5.7
5.7
19800
<5.1
5920
315
<0.0081
<2.5
7.9
<25
857
<5.1
183 j
18.8
1250
<5.1
23
56.4
MW-18 (0-2)
05/16/2015
527
485.38
5.7
6890
<6.9
<6.9
28.8
0.17 j
<17.1
<0.82
354
<331
2.8
<6.9
2.1
7680
<6.9
580
39.1
<0.011
<3.4
<1.7
<33.1
281 j
<6.9
<343
6.1
<331
<6.9
9.9
15.2
MW-18(31-33)
05/16/2015
496
485.38
7.3
3420
<6
<6
31.3
0.22j
<15
<0.72
581
<292
1.9
<6
4.8
7000
<6
686
353
<0.0092
<3
<1.5
<29.2
731
<6
222j
8
<292
<6
3.1j
18.7
MW-18 (37-38)
05/16/2015
491
485.38
7.3
3600
<6.1
<6.1
18.4
0.18 j
<15.3
<0.73
670
<296
1.3 j
<6.1
22.4
3410
<6.1
708
175
<0.0098
<3.1
<1.5
<29.6
486
<6.1
<306
6.7
<296
<6.1
<6.1
16.2
Total Count of Valid Samples ,
16
16
0*
8
16
16
16
16
1 16
16
16
13
1 16
1 16
1 16
16
16
16
16*
16
16*
16
5*
16
16
16*
1*
15
16
Prepared by: ARL Checked by: CDE
Notes:
0 Concentration 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.
* = 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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