NC0004961_RBSS CSA Rpt_Appx D_Soil and Rock Char_20150818

Appendix D
Soil and Rock Characterization
• Sampling Procedures
• Sampling Variances

Sampling Procedures

Sampling Overview
Characterization of subsurface materials was conducted through the completion of soil borings
and borings performed for installation of monitoring wells as described in Section 6. Installation
details for soil borings and monitoring wells, as well as estimated sample quantities and depths,
are described below.
For nested monitoring wells, the deep monitoring well boring was utilized for characterization of
subsurface materials and collection of samples for laboratory analysis. Shallow, deep, and
bedrock monitoring well borings were logged in the field as described below.
Ash and Soil Borings
Characterization of ash and underlying soil was accomplished through the completion and
sampling of 17 borings advanced at the locations of planned monitoring wells in the area of the
active ash basin. Four borings (designated AB-1 and AB-2) were completed on the ash basin
secondary cell dam, 5 borings (designated AB-3 and AB-4) were completed on the intermediate
dike between the primary and secondary cell, 6 borings (designated AB-5 through AB-7) were
completed within the active ash basin primary cell, and 2 borings (designated AB-6) were
completed on the ash basin primary dam. Seven borings (designate AS-1 through AS-3) were
completed at planned monitoring well location within the ash storage area. In addition, borings
(designated GWA-1 through GWA-10 and GWA-20 through GWA 23) were completed outside
of ash management areas to provide additional soil chemistry data, and borings (designated
BG-1 through BG-3) were completed to provide information on background soil conditions.
Field data collected during boring advancement was used to evaluate:
• the presence or absence of ash
• areal extent and depth/thickness of ash
• groundwater flow and transport characteristics if groundwater was encountered

Borings were advanced using hollow stem auger, roller cone drilling, or sonic drilling techniques
to facilitate collection of down-hole data. Standard Penetration Testing (SPT) (ASTM D 1586)
and split-spoon sampling were performed at 5-foot increments using an 18-inch split-spoon
sampler. Continuous coring was performed from auger refusal into partially weathered/fractured
rock at locations where monitoring wells were to be set into the transition zone between
saprolite/weathered rock and competent bedrock (designated as D soil boring/monitoring well
locations), and coring was performed to a depth of at least 50 feet into competent bedrock for
installation of bedrock monitoring wells (designated as BR soil boring/ monitoring wells).
Borings were logged and ash/soil samples were photographed, described, and visually
classified in the field for origin, consistency/relative density, color, and soil type in accordance
with the Unified Soil Classification System (ASTM D2487/D2488).
Borings within Ash Basin Waste Boundary
In areas where ash was known or suspected to be present (i.e., AB- and S-borings), solid phase
samples were collected for laboratory analysis from the following intervals in each boring:
• Shallow Ash – approximately 3 feet to 5 feet bgs
• Deeper Ash – approximately 2 feet above the ash/soil interface
• Upper Soil – approximately 2 feet below the ash/soil interface
• Deeper Soil – approximately 8 feet to 10 feet below the ash/soil interface

If ash was observed to be greater than 30 feet thick, a third ash sample was collected from the
approximate mid-point depth between the shallow and deeper samples. The ash samples were
used to evaluate geochemical variations in ash located in the ash basin and ash storage. The
upper and deeper soil samples were used to delineate the vertical extent of potential soil
impacts beneath the ash basin and ash storage.
Ash and soil samples were analyzed for total inorganic compounds.
Select ash samples were analyzed for leachable inorganic compounds using the Synthetic
Precipitation Leaching Procedure (SPLP) to evaluate the potential for leaching of constituents
from ash into underlying soil. The ash SPLP analytical results were compared to Class GA
Standards as found in 15A NCAC 02L .0202 Groundwater Quality Standards, last amended on
April 1, 2013 (2L Standards).
Ash was located at varying depths beneath the ponded water areas within the active ash basin.
Due to safety concerns, borings were not completed where ponded water was present within
the ash basin. Safety concerns may also prevent access to proposed boring locations on ash
areas where saturated ash presents stability issues.
Borings Outside Ash Basin Waste Boundary
Borings located outside the ash basin waste boundary were designated as GWA and BG
borings.
The GWA soil samples were used to provide additional characterization of soil conditions
outside the ash basin boundary. Solid phase samples were collected for laboratory analysis
from the following intervals in each boring:
• Approximately 2 feet to 3 feet above the water table
• Approximately 2 feet to 3 feet below the water table
• Within the saturated upper transition zone material (if not already included in the two
sample intervals above)
• From a primary, open, stained fracture within fresh bedrock if existent (bedrock core
locations only)

The boring locations designated as BG borings were used to evaluate site-specific background
soil quality. Solid phase samples were collected for laboratory analysis from the following
intervals in each boring:
• At approximately 10-foot intervals until reaching the water table (i.e., 0 feet to 2 feet, 10
feet to 12 feet, 20 feet to 22 feet, and so forth)
• Approximately 2 feet to 3 feet above the water table
• Approximately 2 feet to 3 feet below the water table
• Within the saturated upper transition zone material (if not already included in the two
sample intervals above)
• From a primary, open, stained fracture within fresh bedrock if existent (bedrock core
locations only)

The laboratory analyses performed on the GWA and BG samples depended on the nature and
quantity of material collected.
One or more of the above listed sampling intervals may be combined if field conditions indicate
they were in close proximity to each other (i.e., one sample was obtained that was applicable to
more than one interval).
Index Property Sampling and Analyses
In addition, physical properties of ash and soil were tested in the laboratory to provide data for
use in groundwater modeling. Split-spoon samples were collected at selected locations with the
number of samples collected from the material types as follows:
• Fill - 5 samples
• Ash - 5 samples
• Alluvium - 5 samples
• Soil/Saprolite - 5 samples
• Soil/Saprolite - immediately above refusal - 5 samples
Select split-spoon samples were tested for:
• Natural Moisture Content Determination in accordance with ASTM D-2216
• Grain size with hydrometer determination in accordance with ASTM Standard D-422
Split-spoon samples were collected from the following boring locations:
• Fill – AB-1D, AB-2D, AB-3D, AB-4D, AB-6D
• Ash – AB-3D, AB-5D, AB-7D, AS-3D, C-2D
• Alluvium – GWA-10D (3.5 – 5’)
• Soil and Saprolite/Weathered Rock – GWA-4D, GWA-5D, GWA-6D, GWA-7D, and
GWA-8D

The depth intervals of the select split-spoon samples were determined in the field by the Lead
Geologist/Engineer.
In addition to split-spoon sampling, a minimum of five thin-walled undisturbed tubes (“Shelby”
Tubes) in fill, ash, and soil/saprolite layers were collected. Sample depths were determined in
the field based on conditions encountered during borehole advancement. The Shelby Tubes
were transported to a soil testing laboratory and each tube was tested for the following:
• Natural Moisture Content Determination in accordance with ASTM D-2216
• Grain size with hydrometer determination in accordance with ASTM Standard D-422
• Hydraulic Conductivity Determination in accordance with ASTM Standard D-5084
• Specific Gravity of Soils in accordance with ASTM Standard D-854

Undisturbed samples were collected from the following boring locations:
• Fill – AB-1S, AB-2S, AB-3S, AB-4S, AB-6S
• Soil and Saprolite/Weathered Rock – AB-1D, AB-2D, AB-5SL, AB-6D, AB-8S, BG-1S,
GWA-1S, GWA-2S, GWA-3S, GWA-4S, GWA-5S, GWA-7S, GWA-8S, GWA-9BR,
GWA-10S, and MW-9BR

The results of the laboratory soil and ash property determination were used to determine
additional soil properties such as porosity, transmissivity, and specific storativity. The results
from these tests were used in the groundwater fate and transport modeling. The specific borings
where these samples were collected from were determined based on field conditions with
consideration given to their location relative to use in the groundwater model.

Sampling Variances
Va
r
i
a
n
c
e
s

f
r
o
m

G
r
o
u
n
d
w
a
t
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r

A
s
s
e
s
s
m
e
n
t

W
o
r
k

P
l
a
n

So
i
l

a
n
d

R
o
c
k

C
h
a
r
a
c
t
e
r
i
z
a
t
i
o
n

Va
r
i
a
n
c
e

No
.

As

P
r
o
p
o
s
e
d

As

C
o
m
p
l
e
t
e
d

Ba
s
i
s

f
o
r

V
a
r
i
a
n
c
e

1
GW
A
-
1
D

t
o
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a
l

i
n
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g
a
n
i
c
s

u
p
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tr
a
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s
i
t
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z
o
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GW
A
-
1
B
R
U

t
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s
t
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be
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La
c
k

o
f

P
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a
t

l
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c
a
t
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2
GW
A
-
3
S

K
d
+
H
F
O

1
0
’

b
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w

w
a
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ta
b
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MW
-
9

K
d
+
H
F
O

1
0
’

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w

w
a
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t
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b
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Sa
m
p
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t

d
u
e

t
o

m
i
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c
o
m
m
u
n
i
c
a
t
i
o
n

3
GW
A
-
4
D

t
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a
l

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g
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u
p
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tr
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z
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No
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La
c
k

o
f

P
W
R

a
t

l
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c
a
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4
No
n
e

G
W
A
-
7
D

t
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a
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i
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a
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s
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A
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s
a
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5
GW
A
-
9
D

S
P
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2
-
3
’

a
b
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w
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ta
b
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i
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AB
-
1
D

S
P
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P

4
-
5
’

a
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f
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in
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Sa
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p
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.

S
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c
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in
AB
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6
GW
A
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1
0
S

S
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2
-
3
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a
b
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w
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-
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1
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5
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p
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.

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c
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AB
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D

7
GW
A
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B
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p
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8
No
n
e

A
S
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2
D

S
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2
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a
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a
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s
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Ad
d
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s
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9
No
n
e

AS
-
2
S

T
O
C

3
0
’

b
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w

w
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t
a
b
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i
n

so
i
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Ad
d
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s
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;

o
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t
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1
0
’

b
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wa
t
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t
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10

C-
1
D

t
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g
a
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2
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-
2
5
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i
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s
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N
o
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A
s
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l
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t
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3
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f
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t

t
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11

C-
1
D

S
P
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8
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1
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b
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a
s
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/
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in
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No
n
e

Sa
m
p
l
e

l
e
f
t

o
f
f

s
a
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p
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p
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n

12

C-
2
D

t
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i
n
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g
a
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2
0
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2
5
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i
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a
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N
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A
s
h

l
e
s
s

t
ha
n

3
0

f
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t
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13

AB
-
5
D

S
P
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P

8
-
1
0
’

b
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l
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w

a
s
h
/
s
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in
t
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f
a
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-
3
D

S
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P

2
’

b
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w

a
s
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/
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i
n

s
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Mi
s
c
o
m
m
u
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c
a
t
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o
n
;

a
d
d
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t
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n
a
l

s
a
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p
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e

c
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l
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c
t
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d

a
t

AB
-
3
D

14

AB
-
7
D

K
d
+
H
F
O

f
o
r

u
p
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t
r
a
n
s
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zo
n
e

AB
-
3
D

K
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+
H
F
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f
o
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u
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t
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s
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t
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o
n

zo
n
e

La
c
k

o
f

P
W
R

a
t

l
o
c
a
t
i
o
n
;

a
d
d
e
d

P
W
R

K
d
+
H
F
O

t
o

AB
-
3

15

No
n
e

AB
-
1
D

S
P
L
P

a
b
o
u
t

3
0

f
t

b
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w

w
a
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le
v
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l

Ad
d
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t
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n
a
l

S
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s
a
m
p
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e

16

AB
-
4
D

t
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t
a
l

i
n
o
r
g
a
n
i
c
s

i
n

s
o
i
l

a
t

3
5
-
40
’

No
n
e

A
s
h

w
a
s

o
n
l
y

2
0

f
e
e
t

t
h
i
c
k

a
n
d

a
l
r
e
a
d
y

h
a
d

a

sa
m
p
l
e

n
e
a
r

p
r
o
p
o
s
e
d

r
a
n
g
e

Va
r
i
a
n
c
e

No
.

As

P
r
o
p
o
s
e
d

As

C
o
m
p
l
e
t
e
d

Ba
s
i
s

f
o
r

V
a
r
i
a
n
c
e

17

No
n
e

AB
-
4
D

S
P
L
P

2
’

a
b
o
v
e

a
s
h
/
s
o
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l

in
t
e
r
f
a
c
e

Ad
d
i
t
i
o
n
a
l

s
a
m
p
l
e

18

No
n
e

A
B
-
4
S

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

8
-
1
0
’

b
e
l
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w

as
h
/
s
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l

i
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t
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r
f
a
c
e

Ad
d
i
t
i
o
n
a
l

s
a
m
p
l
e

19

No
n
e

AB
-
4
D

S
P
L
P

8
-
1
0
’

b
e
l
o
w

a
s
h
/
s
o
i
l

in
t
e
r
f
a
c
e

Ad
d
i
t
i
o
n
a
l

s
a
m
p
l
e

20

GW
A
-
2
0
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

i
n

u
p
p
e
r

tr
a
n
s
i
t
i
o
n

z
o
n
e

No
n
e

L
a
c
k

o
f

P
W
R

a
t

l
o
c
a
t
i
o
n

21

No
n
e

BG
-
1
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

1
5
’

b
e
l
o
w

wa
t
e
r

t
a
b
l
e

Ad
d
i
t
i
o
n
a
l

s
a
m
p
l
e

22

BG
-
1
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

i
n

u
p
p
e
r

tr
a
n
s
i
t
i
o
n

z
o
n
e

No
n
e

L
a
c
k

o
f

P
W
R

a
t

l
o
c
a
t
i
o
n

23

BG
-
2
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

a
n
d

S
P
L
P

8.
5
-
1
0
’

b
g
s

BG
-
2
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

a
n
d

S
P
L
P

8
-
10
’

b
e
l
o
w

w
a
t
e
r

t
a
b
l
e

In
c
o
r
r
e
c
t
l
y

l
a
b
e
l
e
d

“
f
o
r

b
e
l
o
w

w
a
t
e
r

t
a
b
l
e
”

o
n

s
a
m
p
le
pl
a
n
;

s
a
m
p
l
e

c
o
l
l
e
c
t
e
d

w
h
e
r
e

l
i
s
t
e
d

o
n

p
l
a
n

24

BG
-
2
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

1
8
.
5
-
2
0
’

b
g
s

B
G
-
2
D

t
o
t
a
l

i
n
or
g
a
n
i
c
s

a
n
d

S
P
L
P

2
5
’

be
l
o
w

w
a
t
e
r

t
a
b
l
e

Mi
s
s
e
d

s
a
m
p
l
e

c
o
l
l
e
c
t
e
d

l
o
w
e
r

i
n

t
h
e

s
o
i
l

c
o
l
u
m
n

25

BG
-
3
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

a
n
d

S
P
L
P

8.
5
-
1
0
’

b
g
s

BG
-
3
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

a
n
d

S
P
L
P

8
-
10
’

b
e
l
o
w

w
a
t
e
r

t
a
b
l
e

In
c
o
r
r
e
c
t
l
y

l
a
b
e
l
e
d

“
f
o
r

b
e
l
o
w

w
a
t
e
r

t
a
b
l
e
”

o
n

s
a
m
p
le
pl
a
n

26

No
n
e

B
G
-
3
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

5
0
’

b
e
l
o
w

wa
t
e
r

t
a
b
l
e

Sa
m
p
l
e

c
o
l
l
e
c
t
e
d

f
r
o
m

s
o
i
l

i
n
s
t
e
a
d

o
f

r
o
c
k

27

BG
-
3
D

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

i
n

u
p
p
e
r

tr
a
n
s
i
t
i
o
n

z
o
n
e

No
n
e

La
c
k

o
f

P
W
R

a
t

l
o
c
a
t
i
o
n

28

MW
-
9

t
o
t
a
l

i
n
o
r
g
a
n
i
c
s

2
-
3
’

a
b
o
v
e

wa
t
e
r

t
a
b
l
e

No
n
e

W
a
t
e
r

t
a
b
l
e

a
t

0
.
2

f
e
e
t

b
g
s

i
n

M
W
-
9
.

29

GW
A
-
2
1
S
/
D
/
B
R

GW
A
-
2
1
S

GW
A
-
2
1
D

w
a
s

i
n
a
c
c
e
s
s
i
b
l
e

f
o
r

s
a
m
p
l
i
n
g

d
u
r
i
n
g

t
h
e

co
m
p
l
e
t
i
o
n

o
f

d
r
i
l
l
i
n
g

G
W
A
-
2
1
B
R

a
s

o
f

t
h
e

i
s
s
u
a
n
c
e

of

t
h
i
s

r
e
p
o
r
t