NC0004961_Additional Information Request_20141204

dens
DUKE HarryK Srident
ENERGY® ental, HealtVice h
& President
Environmental, Health &Safety
526 S Church Street
Marl Code EC3XP
Charlotte, NC 28202
[phone]
December 4, 2014
North Carolina Division of Water Resources
Mr. Tom Reeder, Director
1617 Mail Service Center
Raleigh NC 27699-1617
Subject: NPDES Wastewater Permit Application
NC0004961
Additional Information Request
Riverbend Steam Station, Gaston County
Dear: Mr. Reeder,
Duke Energy is in receipt of your letter dated August 12, 2014 requesting additional information
to process the permit renewal application for the Riverbend Steam Station As you are aware
we are planning to remove coal combustion residuals (CCR) from the site in the near future.
We are planning to discharge the wastewater generated by the dewatering and removal of ash
from the site through existing Outfall 002. We have characterized the wastewater to be
generated by sampling free water and entrapped, or interstitial, water in the ash basin. The
attached document provides responses to the questions in your August 12 letter, an overview
description of our intended dewatering process and definitional language regarding the
wastewaters to be generated through this process. We expect that the free water will meet
current NPDES permit limits, but that additional treatment will be needed as dewatering
proceeds.
We trust that this information will answer your questions and enable the Division to move
forward with permit coverage for dewatering.
If you have any questions regarding this response to your request for additional information,
please contact Mr. Steve Cahoon at [phone] or [e-mail]
I certify, under penalty of law, that this document and all attachments were prepared under my direction or
supervision in accordance with a system designed to assure that qualified personnel properly gather and
evaluate the information submitted. Based on my inquiry of the person or persons who manage the system, or
those persons directly responsible for gathering the information, the information submitted is, to the best of my
knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for
submitting false information, including the possibility of fines and imprisonment for knowing violations
ySinceely,
Harry K. Sidens, SVP
Environmental Health and Safety

Duke Energy Response to
August 12, 2014 Additional Information Request
Riverbend Steam Station
(NCDENR's information request appears in italics below, followed by Duke Energy's response)
1) Location of the loading/dewatering site
Please see the attached draft drawing depicting the proposed wastewater treatment
system and collection areas in the basins.
2) Projected volume of ash that will be processed through the site.
The primary basin has approximately 2,050,000 tons of material.
The secondary basin has approximately 680,000 tons of material.
3) Projected volume of wastewater generated on this site.
The dewatering and removal of ash from the site is expected to generate between 213
and 241 million gallons of extractable wastewater from the ash.
Free water will be removed from the secondary basin from elevation 708 ft. to
approximately elevation 685 ft. Dewatering will not exceed the maximum drawdown
rate established by Dam Safety of one foot per week. At approximately elevation 685 ft.
the bulk dewatering phase will transition to the interstitial water removal phase, which
will continue until closure.
4) Chemical Characterization of wastewater generated onsite. The wastewater should be
analyzed for the following parameters: Cl, F, SO4i Hg, (Method 1631E), Al, Ba, 8, Fe, Mn,
Zn, Sb, As, Cd, Cr, Cu, Pb, Mo, Ni, Se, Tl, pH, TDS, TSS, temperature and specific
conductance.
See the attached table showing results of chemical analysis for water samples taken
within the ash basin. The attached map shows the sampling locations. The bulk water
sample is free water above the ash in the basin (sampled near the water surface), the
well water sample is entrapped, or interstitial, water within the ash in the
basin(sampled below the surface of the ash), and the filtered water samples are
entrapped water that has been filtered with one of 2 filter sizes. Please be aware that
reporting limits are not consistent because some of the samples required varying
dilutions.
5) Location of the outfall for this wastewater, including latitude and longitude and
topographic map. Alternatively the facility can use the existing Outfall 002 for the
wastewater discharge. However this new waste stream shall be sampled prior to mixing
with the existing flow in the concrete conveyance that is used for outfall 002.

r
At the present time Duke Energy is expecting to discharge the wastewater generated
from the removal of ash (including dewatering of ash basins to allow excavation and
dewatering of excavated ash prior to being loaded onto trucks or rail cars) from the site
through the current Outfall 002. It is anticipated that as dewatering proceeds some
additional treatment may be needed to meet permit discharge limits at Outfall 002.
The following definitions may be useful as you consider these activities:
Ash basin free water: Water in an ash basin located above the settled layer of
ash. Ash basin free water has undergone treatment in the ash basin, has the
same general characteristics as water discharged when the facility was active
sluicing ash to the ash basin, is largely devoid of Total Suspended Solids and
meets all applicable NPDES permit limits.
Ash basin interstitial water: Water in an ash basin that is located within the pore
space of accumulated wastewater sludge or slurry. Ash basin interstitial water
must be removed by some means such as trenching, well points, etc. and would
likely require additional treatment before being released to the environment.
The process we envision for dewatering the ash basins to enable excavation and ash
removal is as follows:
Secondary Basin and Primary Basin free water removal will occur simultaneously.
Initial drawdown of the Secondary Basin will be accomplished by removal of upper
layer stop logs. Primary Basin free water will be pumped to the Secondary Basin as
stop logs are removed from the Secondary Basin discharge tower to initiate dewatering.
Only the upper layer of stop logs will be removed. The Secondary Basin will be drawn
down to approximately elevation 707 ft. by stop log removal. No more than two 6
inch high stop logs will be raised every week to limit the drawdown to the acceptable
rate of 1 ft. every 7 days.
Stop logs will be removed in a controlled manner to limit the discharge rate to less than
the historical average discharge rate of 1,010 gpm. This can be achieved by first raising
the top stop log a maximum of 2.0 in to limit pressure flow through the opening
between the stop logs. The maximum pressure flow rate through the 2.0 in opening
is approximately 930 gpm. After the water drops below the bottom of the raised top
stop log, weir flow will occur. With a maximum head of 2 in, the maximum weir
flow is 360 gpm. Once the water level has stabilized, the next stop log may be
raised. A maximum of 2 stop logs may be raised per week to control the dewatering
rate to 1 ft. per 7 days.
A duplex floating pump station will be used to dewater the Secondary Basin following
removal of all upper layer stop logs from the Secondary Basin discharge tower. The
duplex floating pump station will be anchored to the dike at four points around the dike

perimeter using stainless steel aircraft cable guy wire and a heavy duty manual winch
anchored to a concrete deadman. The pump station will be constructed of hot -dipped
galvanized steel. It will be equipped with a 3 ft. 3 inch deep wet well. The wet well will
be filled by free water skimmed from the surface of the basin using a ballast -adjustable
weir submerged a minimum of 3 in and a maximum of 9 in below the basin surface. The
pump station will discharge to a single, floated 12 inch high density polyethylene (HDPE)
pipe that will connect to the Secondary Basin discharge tower.
For operational control, TSS concentration and pH in the Secondary Basin floating pump
discharge pipe will be monitored using real-time meters with sensors inserted in
the discharge pipe. In addition to the real-time monitoring, handheld TSS and pH
meters will be used daily to measure TSS concentration at the pump discharge. A small
sample line will tee off the pump discharge pipe and run to the shore. Samples for
daily measurements will be taken from this sample line. The handheld TSS meter will
undergo laboratory validated calibration and site-specific field verification. Daily pH
monitoring will be conducted with a portable pH meter which has been laboratory
calibrated. Carbon dioxide (CO2), sulfuric acid and sodium hydroxide may be added for
pH control if needed during the dewatering process. Compliance monitoring required
by the NPDES Permit will be performed as specified in the NPDES permit.
As the dewatering process transitions from the free water phase to the interstitial water
phase it is anticipated that a filtration system will be used to maintain compliance with
permit limits. Please include a provision in the modified permit to allow the use of a
coagulant or flocculent from the state's approved list to facilitate the filtration process if
needed.

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RIVERBEND STEAM STATION
PRIMARY " +}'4 ;` 1 ASH BASIN DEWATERING
ii, s ASH BASIN MOUNT HOLLY NORTH CAROLINA
41
DRAFT WORK IN PROGRESS - FOR REVIEW ONLY 6� 21
2 a a 5 e1 n
N

Riverbend Water Sampling Locations

Sample
Bulk Water
Well
Well (20 u filtered)
Well (0.45 µ filtered)
values below detection limits
Total
Nitrite +
Kjeldahl
Nitrate
Aluminum
Calcium
(Colorimetr
Nitrogen
Bromide
Chloride
Fluoride
Sulfate
(Al)
Barium (Ba)
Boron (B)
(Ca)
Iron (Fe)
(Colorimetr
ic)
ic)
mg-N/L
mg-N/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
0.01
0.15
0.1
<D5
0.16
56
0.056
0.135
0.344
15.8
0.013
0.505
1.2
0.1
3.5
12015
4
1.05
16
�8j
0.663
0.53
0.1
3.5
0.52
»n
0 SA
0.87
0.9�
111
0.272 _
0.674
0.57
0.1
3.6
0.53
120
0.074
0.816
0.942
110
0.01
values below detection limits

Magnesium Manganese Phosphorus
Zinc (Zn)
Antimony
Arsenic (As)
Cadmium
Chromium
Copper
Lead (Pb)
Molybdenu
Nickel (Ni)
Selenium
(Mg)
(Mn)
(P)
(Sb)
(Cd)
(Cr)
(Cu)
m (Mo)
(Se)
mg/L
mg/L
mg/L
mg/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
ug/L
3.2
0.005
0.02
0.007
2.21
25.9
1
1
1
1
32.5
5.25
1.18
18.7
r—T1_8
0.762
0 ''
10
10
10 2
5� 8 `
2��
88.1
X25.
�0�
17.2
0.126
0.309
0.005
6.48
288
1
1
1.84
1
84.5
1
16.4
0.12
0.278
5
6.71 ;
277
1
1
1
1
81.9
3.26
1

Thallium
(TI) Low Mercury TDS TSS pH Sp Cond
Level (CVAFS)
ug/L
ng/L
mg/L
mg/L
Su umhos/cm
0.928
1.16
93
5
2.67
0.500
460
1000
0.474
0.500
440
19
8.11 752
0.363
0.500
450
5
8.26 760

Riverbend Steam Station 2014 Freshwater RPA - 95% Probability/95% Confidence Outfall 002
NC0004961 MAXIMUM DATA POINTS = 58 Qw = 0.19 MGD
Qw (MGD) =
1Q10S (cfs) =
7Q OS (cfs) =
7QI OW (cfs) =
30Q2 (cfs) =
Avg. Stream Flow, QA (cfs) =
Receiving Stream
0.19
WWTP/WTP Class: 1
65.40
IWC @ 1Q10S = 0.448287%
80.00
IWC @ 7Q10S = 0.366775%
NO 7Q10w DATA
IWC @ 7Q10W = N/A
80.00
IWC @ 30Q2 = 0.366775%
2700.00
IWC @ QA = 0.010906%
Catawba River
Stream Class: WS -IV B -CA
PARAMETER
STANDARDS & CRITERIA (2)
N
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
(1)
NC WQS / Applied /z FAV /
a
z
Max Pred
7
11 " Dct. Allowable C\\
Chronic Standard Acute
CN,
Acute: NO WQS
Arsenic
C
50 FW(7QIOs)
Ug/L
21 21
87.9
no limit
---------------------------------------------
Chronic: 13,632
No
o value > All_ w_able Cw
Arsenic
C
10 HH/WS(Qavg)
ua/L
21 21
87.9
_
Chronic: 91,690 8
keep quarterly monitoring
No value > Allowable Cw
Acute: NO WQS
Beryllium
NC
6.5 FW(7QIOs)
u_l
1 0 0.5
no limit
Note: n!5 9 Default C.V.
_ _ _ _____ _ _
Chronic: 1,772.2
________________________ _
Limited data set
No value > Allowable Cw
Acute: 3,346.1
Cadmium
NC
2 FW(7QIOs) L
ug/L,1
I 0.4
no limit
Note: n!5 9 Default C.V.
_
Chronic: 545.3
Limited data set
No value > Allowable Cw
Acute: NO WQS
Chlorides (AL)
NC
230 FW(7Q1Os)
mg/L
0 0
\ A_
no data
_ _
Chronic --62,709—
-- — — — — — — — — — — ——
Acute: NO WQS
Chlorinated Phenolic Compounds
NC
1 A(30Q2)
uc
\ \
N/A
_
Chroni--- —
c: 272.6
--------------------------
Acute: NO WQS
Total Phenolic Compounds
NC
300 A(30Q2)
up/L
1 1
12.0
no limit
Note: n59
Default C.V.
Chronic: 81,794___1
Limited data set
No value > Allowable Cw
Acute: 227,978.9
Chromium
NC
50 FW(7QIOs) 1022
a>/L
1 0 0.5
see the fact sheet
Note: n:5 9 Default C.V.
_ ___ _ _ _
Chronic 13,632.3
__________________
Limited data set
No value > Allowable Cw
Acute: 1,628.4
Copper (AL)
NC
7 FW(7QIOs) 7.3
ug 1,
21 5
15.5
no limit
_ _ _ _ _
Chronic: 1,908.5
_ _ _ _ _ _ _ _ _ _ _ _ _
keep quarterly monitoring
No value > Allowable Cw
Acute: 4,907.6
Cyanide
NC
5 FW(7QIOs) 22
10
u,- 1.
1 0 5.0
no limit
Note. n < 9 Default C.V
_ _ _ _ _ _
Chronic: 1,363.2
_ _ _ _ _ _ _ _ _ _ _ _ _
Limited data set
No value > Allowable Cw
Page 1 of 2 4961 -RPA -2014, rpa
g 11/7/2014

Riverbend Steam Station 2014 Freshwater RPA - 95% Probability/95% Confidence
NC0004961 MAXIMUM DATA POINTS = 58
Outfall 002
Qw=0.19 MGD
4961 -RPA -2014, rpa
?age L c` L
11/7/2014
Acute. NO WQS
Fluoride
NC
1800 FW(7Q10s)
ug/L.
I I
110.0—
1
no limit
Note: n 5 9
Default C.V.
Chronic: 490,764.3
Limited data set
No value > Allowable Cw
Acute: 7,539.8
Lead
NC
25 FW(7QIOs) 3
ug/L
1 0
0.5
no limit
Note: n:5 9
Default C.V.
__
Chronic 6,816.2
Limited data set
No value > Allowable Cw
Acute: NO WQS
Mercury
NC
12 FW(7QIOs)
0.5
n g / L
12 12
2.3
no limit
Chronic: 3
keep quarterly monitoring
w
No value > Allowablee Cw
Acute: NO WQS
Molybdenum
NC
160 WS(7QIOs)
ug/L
1 1
21.0
no limit
Note: n!5 9
Default C.V.
Chronic: 43,623.5
Limited data set
No value > Allowable Cw
58,221.6
NC
25 WS(7QIOs) 261
uc%1
1 1 23.6
no limpNickel
\ote: n <_ 9 Default C.V.
;Acute:
_ _ _
ic: 6,816.2
Limited data set
No> Allowable Cw
e: 12,492.0
Selenium
NC
5 FW(7QIOs) 56
t2l
7
3.3
___—__
no limit
__—__——_—_——
Chronic: 1e
keep quarterly monitoring
Cw
No value > Allowable Cw
Acute: 274.378
no limit
Silver (AL)
NC
0.06 FW(7QIOs) I ' 3
ug/L
1 0
0.500
_
Note: n S 9
Default C.V.
__
Chronic 16.359
Limited data set
No value > Allowable Cw
Acute: 14,945.8
Zinc (AL)
NC
50 FW(7QIOs) 67
ug/L
1 79Default
99.0
___
no limit
Note: n
C.V.
______
Chronic 13,632.3
Limited data set
No value > Allowable Cw
Acute: NO WQS
Iron
NC
1000 WS(7Q10s)
µg/L
21 21
1,192.80000
no limit
_ _ __
Chronic: 272646.859____0
- — - — - — - — - — - — - — - — - — - — - — - — - —
No value > Allowable Cw
Acute:
N/A
_
Chronic:--------
----------------------
Acute:
N/A
Chronic:----- — —
--------------------------
Acute:
N/A
Chronic:
4961 -RPA -2014, rpa
?age L c` L
11/7/2014

0
REASONABLE POTENTIAL ANALYSIS
1
Date
Data
BDL=1/2DL
Arsenic -
FW Standard
1
Date Data BDL=1/2DL
Results
1
31.9
31.9
Std Dev.
2
62.6
62.6
Mean
3
49.7
49.7
C.V.
4
19.8
19.8
n
5
33
33
1/0/1900
6
65.6
65.6
Mult Factor =
7
52.9
52.9
Max. Value
8
32
32
Max. Pred Cw
9
33.3
33.3
65.6
10
59.3
59.3
7
11
29.2
29.2
52.9
12
19.3
19.3
1/0/1900
13
41.5
41.5
Max. Fred Cw
14
60.3
60.3
0
15
32.7
32.7
16
27.4
27.4
59.3
17
35.4
35.4
11
18
2.9
2.9
29.2
19
2.3
2.3
1/0/1900
20
4.59
4.59
21
4.56
4.56
0
22
41.5
23
1/0/1900
0
60.3
24
15
25
0
32.7
32.7
26
16
1/0/1900
27
27.4
27.4
28
17
1/0/1900
0
29
35.4
30
1/0/1900
0
2.9
31
19
32
0
2.3
2.3
33
20
1/0/1900
34
4.59
4.59
35
21
1/0/1900
0
36
4.56
37
38
23
39
40
24
41
42
25
43
44
45
27
46
47
28
48
49
29
50
51
52
31
53
54
32
55
56
33
57
58
2
Use "PASTE SPECIAL
Values" then "COPY" Automatically copies
. Maximum data Arsenic - HH/VUS Standards Arsenic data from FW
Standard entries
points = 58
33.3452
0.5998
21
1.34
65.6 ug/L
87.9 ug/L
flE
4961 -RPA -2014, data
9/22/2014
Date
Data
BDL=1/2DL
Results
1
1/0/1900
0
31.9
31.9
Std Dev.
20.0011
2
1/0/1900
0
62.6
62.6
Mean
33.3452
3
1/0/1900
0
49.7
49.7
C.V.
0.5998
4
1/0/1900
0
19.8
19.8
n
21
5
1/0/1900
0
33
33
6
1/0/1900
0
65.6
65.6
Mult Factor =
1.34
7
1/0/1900
0
52.9
52.9
Max. Value
65.6 ug/L
8
1/0/1900
0
32
32
Max. Fred Cw
87.9 ug/L
9
1/0/1900
0
33.3
33.3
10
1/0/1900
0
59.3
59.3
11
1/0/1900
0
29.2
29.2
12
1/0/1900
0
19.3
19.3
13
1/0/1900
0
41.5
41.5
14
1/0/1900
0
60.3
60.3
15
1/0/1900
0
32.7
32.7
16
1/0/1900
0
27.4
27.4
17
1/0/1900
0
35.4
35.4
18
1/0/1900
0
2.9
2.9
19
1/0/1900
0
2.3
2.3
20
1/0/1900
0
4.59
4.59
21
1/0/1900
0
4.56
4.56
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
flE
4961 -RPA -2014, data
9/22/2014

3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
REASONABLE POTENTIAL ANALYSIS
Beryllium
Use "PASTE SPECIAL
values. then "COPY"
4
Cadmium
. Maximum data
_
points = 58
Date Data BDL=1/2DL Results
Date Data BDL=1/2DL
Results
< 1 0.5 Std Dev.
N/A
1
0.42 0.42
Std Dev.
Mean
0.5000
2
Mean
C.V.
0.0000
3
C.V.
n
1
4
n
5
Mult Factor =
1.00
6
Mult Factor =
Max. Value
0.5 ug/L
7
Max. Value
Max. Pred Cw
0.5 ug/L
8
Max. Fred Cw
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
-2-
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
N/A
0.4200
0.0000
1
1.00
0.4 ug/L
0.4 ug/L
4961 -RPA -2014, data
9/22/2014

u
5
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
REASONABLE POTENTIAL ANALYSIS
_
Chlorides (AL)
Use "PASTE SPECIAL-
Values" then "COPY".
6
Use "PASTE Sf
Chlorinated Phenolic Compounds
Values" then "
. Maximum
Maximum data points =
points = 5
58
Date Data BDL=1/2DL Results
Date Data BDL=1/2DL Results
Std Dev.
NO DATA
1
Std Dev.
NO DATA
Mean
NO DATA
2
Mean
NO DATA
C.V.
NO DATA
3
C.V.
NO DATA
n
0
4
n
0
5
Mull Factor =
N/A
6
Mult Factor =
N/A
Max. Value
N/A mg/L
7
Max. Value
N/A
Max. Pred Cw
N/A mg/L
8
Max. Pred Cw
N/A
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
3-
4961 -RPA -2014, data
9/22/2014

U)
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J
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0
REASONABLE POTENTIAL ANALYSIS
5 -
"PASTE SF
jes" then
Maximum
points = 6
5.00
0.0000
1
1.00
5.0
5.0
4961 -RPA -2014, data
9/22/2014
10
Use "PASTE SPE
VD.te
Copper(AL)
. Maximum dat
points = 68
Data
BDL=1/2DL
Results
1
<
5 2.5
Std Dev.
3.8571
2
<
5 2.5
Mean
C.V.
3
<
5 2.5
C.V.
5
4
1.41
5 5
n
11.0 ug/L
5
<
5 2.5
8
Max. Pred Cw
6
<
5 2.5
Mult Factor =
ug/L
7
<
5 2.5
Max. Value
ug/L
8
<
5 2.5
Max. Pred Cw
9
<
5 2.5
15
10
<
5 2.5
11
<
5 2.5
18
12
<
5 2.5
20
13
<
5 2.5
14
<:
5 2.5
23
15
<
5 2.5
25
16
<
5 2.5
17
<
5 2.5
28
18
29
10 10
30
19
11 11
20
6 6
33
21
34
9 9
35
22
36
23
38
24
39
40
25
41
26
43
27
44
45
28
46
29
48
30
49
50
31
51
32
53
33
54
55
34
56
35
58
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
5 -
"PASTE SF
jes" then
Maximum
points = 6
5.00
0.0000
1
1.00
5.0
5.0
4961 -RPA -2014, data
9/22/2014
10
Use "PASTE SPE
Values" then "C
Cy8f11C�e
. Maximum dat
points = 68
Date Data BDL=1/2DL Results
2.7438
1
< 10 5 Std Dev.
3.8571
2
Mean
0.7114
3
C.V.
21
4
n
5
1.41
6
Mult Factor =
11.0 ug/L
7
Max. Value
15.5 ug/L
8
Max. Pred Cw
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
5 -
"PASTE SF
jes" then
Maximum
points = 6
5.00
0.0000
1
1.00
5.0
5.0
4961 -RPA -2014, data
9/22/2014

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n
REASONABLE POTENTIAL ANALYSIS
4961 -RPA -2014, data
- 7 - 9/22/2014
14
MercuryMaximum
Use"PASTE SPECIAL
Values" then "COPY"
Use"PASTE SF
Molybdenum.
Values" then",
VD.te
data
points = 58
Maximum,
points
Data
BDL=1/2DL
Results
Date Data BDL=1/2DL
Results
1
1.25
1.25
Std Dev.
0.3856
1
21 21
Std Dev.
N/A
2
0.54
0.54
Mean
0.8483
2
Mean
21.0000
3
0.5
0.5
C.V.
0.4545
3
C.V.
0.0000
4
1.56
1.56
n
12
4
n
1
5
1.34
1.34
5
6
0.89
0.89
Mult Factor =
1.46
6
Mult Factor =
1.00
ug/L
7
0.83
0.83
Max. Value
1.6 ng/L
7
Max. Value
21.0
ug/L
8
0.62
0.62
Max. Pred Cw
2.3 ng/L
8
Max. Pred Cw
21.0
9
0.5
0.5
9
10
0.5
0.5
10
11
0.5
0.5
11
12
1.15
1.15
12
13
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
4961 -RPA -2014, data
- 7 - 9/22/2014

REASONABLE POTENTIAL ANALYSIS
4961 -RPA -2014, data
- 8 - 9/22/2014
15
Nickel
E
Use"PASTE SPECIAL
Values" then "COPY"
Maximum data
16
Selenium
points = 5a
Date Data BDL=1/2DL Results
Date Data
BDL=1/2DL
Results
1
23.6 23.6 Std Dev.
N/A
1
2.4
2.4
Std Dev.
2
Mean
23.6000
2
2.6
2.6
Mean
3
C.V.
0.0000
3
1.8
1.8
C.V.
4
n
1
4
1.2
1.2
n
5
5
<
2
1
6
Mutt Factor =
1.00
6
2.4
2.4
Mutt Factor =
ug/L
7
Max. Value
23.6 ug/L
7
2.2
2.2
Max. Value
ug/L
8
Max. Pred Cw
23.6 ug/L
8
1.6
1.6
Max. Pred Cw
9
9
1.4
1.4
10
10
2.3
2.3
11
11
2
2
12
12
1
1
13
13
1.2
1.2
14
14
2.3
2.3
15
15
1.4
1.4
16
16
1.2
1.2
17
17
1.4
1.4
18
18
1.2
1.2
19
19
<
1
0.5
20
20
<
1
0.5
21
21
<
1
0.5
22
22
23
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
4961 -RPA -2014, data
- 8 - 9/22/2014

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DENR/DWR
FACT SHEET FOR NPDES PERMIT DEVELOPMENT
PERMIT RENEWAL
NPDES No. NC0004961
Facility Information
Applicant/Facility Name:
Duke Energy Carolinas, LLC — Riverbend Steam Station
Applicant Address:
P.O. Box 1006, Charlotte, North Carolina 28201
Facility Address:
175 Steam Plant Road; Mount Holly, North Carolina 28120
Permitted Flow
No limit
Type of Waste:
100% industrial
Prim. SIC Code: 4911 — Electric Services
Facility/Permit Status:
Class I/Active; Renewal
County:
Gaston County
Miscellaneous
Receiving Stream:
Catawba River
(Mt. Island Lake
Regional Office:
Mooresville
Stream Classification:
WS -1V and B -CA
State Grid / USGS Quad:
F15Sw
303(d) Listed?
No
Permit Writer:
Sergei Chernikov,
Ph.D.
Subbasin:
03-08-33
Date:
May 21, 2014
Drainage Area (mi'):
1800
AAW
001: Lat. 35'21'28"N ' Long. 800 58' 12" W
002: Lat. 35 22' 06" N Long. 80157' 31" W
002B: Lat. 35° 21' 51" N Long. 80° 58' 11" W
011: Lat. 35° 21' 38" N Long. 80° 58' 38" W
Summer 7Q10 (cfs)
80
Winter 7Q10 (cfs):
30Q2 (cfs)
Average Flow (cfs):
2700
IWC %for Outfall 002:
(%)
0.4 — discharge
g
2.7 — dewatering
SUMMARY
Duke Energy's Riverbend Steam Station was a coal fired steam electric plant in Gaston County,
the electricity generation was discontinued on 04/1/2013. The facility has 5 permitted outfalls in
the current NPDES discharge permit. The sources of wastewater for these outfalls include non -
contact cooling water, ash basin discharge, sanitary waste, stormwater from process areas, sump
overflows, and potentially contaminated groundwater seeps. The facility has no FGD scrubber.
Currently, discharge of cooling water has discontinued (only plant chiller system is discharging)
and discharge from the ash pond significantly decreased.
In addition to NPDES Permit NC0004961, the facility also holds 0388R20 (air permit) and
NCD024717423 (Hazardous wastes). The facility is subject to 40 CFR 423 — Steam Electric Power
Generation.
The following descriptions of the wastes at each outfall are offered:
001 —Water from the plant chiller system.
002 — Ash basin discharge consisting of stormwater from roof drains and paving, treated
groundwater, track hopper sump (groundwater), coal pile runoff, general plant/trailer
Fact Sheet
NPDES NC0004961 Renewal
Page 1

sanitary wastewater, turbine and boiler rooms sumps, vehicle rinse water, and stormwater
from pond areas, upgradient watershed, and miscellaneous stormwater flows.
002A- Yard drain sump overflow, discharge occurs rarely.
101-112 —Flow from seeps.
011 — Former stormwater Outfall 1. Contains stormwater and groundwater flow, also
includes wastewater from 10,000 gallon oil separator tank #3. The drainage basin includes
a 2.7 acre portion of the main switchyard and 8,700 ft2 of the plant yard between power
house and combustion turbine area. The powerhouse covers about 1.5 acres of the drainage
basin. 100% of the drainage basin is paved or roofed.
This facility discharges to the Mountain Island Lake (Catawba River) in sub -basin 03-08-33. The
receiving stream is not listed as impaired.
Duke Energy Submitted Application dated May 15, 2014. The current permit expires February 28,
2015.
Duke Energy is required by the Coal Ash Management Act to remove all ash from the site by
August 1, 2019.
The discharge pipe for NPDES outfall 002 from the secondary ash basin discharge tower at
Riverbend Steam Station will be slip lined to ensure integrity. While this pipe is being slip lined,
an alternative arrangement to convey wast water to the permitted NPDES outfall 002 will be
utilized. Temporary piping will be posit�ned in the secondary ash basin and the treated
wastewater will be pumped to the NPDES outfall 002 discharge flow weir, located before the
concrete flume that discharges into Mountain Island Lake. Once the slip line repairs are
completed, the system will be returned to its original configuration. NPDES monitoring
requirements will continue to be collected during the slip line project at the NPDES outfall 002
discharge flow weir.
SEEPS
The facility identified 12 unpermitted seeps ( 1 non -engineered) from the ash settling basin, 10
of the seeps has been classified as "jurisdictio al waters" by the United States Army Corps of
Engineers.
For the jurisdictional waters seeps the facility hall determine within 90 days from the effective
date of the permit if a seep meets the state wat r quality standards established in 15A NCAC 2B
.0200 and submit the results of this determinat' n to the Division.
If the standards are not contravened, the facili shall conduct quarterly monitoring for the
parameters specified in Table 1 for the duratio of the permit. If any of the water quality
standards are exceeded (with the exception of t e Action Level standards), the facility shall be
considered in violation of the Clean Water Act. The facility shall:
1) Submit a complete application for 404 P rmit (within 30 days after determining that a
water quality standards exceeded) to p p the seep discharge to one of the existing
outfalls, install a pipe to discharge the se p to the Catawba River, or install an in-situ
treatment system. After the 404 Permit i obtained, the facility shall complete the
installation of the pump, pipe, or treatment system within 180 days from the date of the
404 permit receipt and begin pumping/discharging or treatment.
Fact heet
NPDES NC00 4961 Renewal
Pag 2

2) Demonstrate through modeling that the decanting and dewatering of the ash basin will
result in the elimination of the seep and submit the modeling results to the Division
within 120 days from the effective date of the permit. Within 180 days from the
completion of the dewatering the facility shall confirm that the seep flow ceased. If the
seep flow continues, the facility shall choose one of the other options in the Special
Condition, OR
3) Demonstrate that the seep is discharging through the designated "Effluent Channel" and
the water quality standards in the receiving stream are not contravened.
Until one of the options is fully implemented, the facility shall conduct monthly monitoring for
the parameters specified in the Table 1. After one of the options is fully implemented the
monitoring will be reduced to quarterly for the seeps that continue to flow.
If a jurisdictional water seep contravenes an Action Level Standard, the facility shall conduct a
Whole Effluent Toxicity Test (WET test). If the WET result passes, the facility shall be
considered in compliance with the state water quality standards. If the WET result fails and the
Toxicity Identification Evaluation determines that the parameter contravening the water quality
standard is responsible for the failure the facility shall be in considered in violation and shall
implement one of the 3 options identified above.
For the non jurisdictional water seeps the facility shall demonstrate that they will not violate
water quality standards in the receiving stream or that the seep does not discharge to the
jurisdictional water or that the seep does not carry pollutants indicating ash characteristics and
submit this demonstration to the Division within 90 days from the effective date of the permit.
The facility shall conduct monthly sampling of the parameters in Table 1 during the first year
from the effective date of the permit, the sampling frequency shall be reduced to quarterly for the
remainder of the permit term. If such demonstration is not possible or not approved by the
Division, the facility shall choose one of the 3 options identified above.
If new seeps emerge, the facility shall follow the procedures outlined above, the deadlines shall
be calculated from the date of the seep discovery.
Table 1. Seep Monitoring Parameters
Parameter
Monitoring Frequency
Chlorides m
Monthly/Quarterly
Fluoride, m
Monthly/Quarterly
Total Mercury
(Method 1631E),
n
Monthly/Quarterly
Total Barium, m
Monthly/Quarterly
Total Iron*, m
Monthly/Quarterly
Total Manganese*,
m
Monthly/Quarterly
Total Zinc,
Monthly/Quarterly
Total Arsenic, /L
Monthly/Quarterly
Total Cadmium,
Monthly/Quarterly
Total Chromium,
Monthly/Quarterly
Fact Sheet
NPDES NC0004961 Renewal
Page 3

Total Copper,
Monthly/Quarterly
Total Lead, jLgIL
Monthly/Quarterly
Total Nickel,
Monthly/Quarterly
Total Selenium, /L
Monthly/Quarterly
Nitrate as N, m
Monthly/Quarterly
Sulfates m
Monthly/Quarterly
H
Monthly/Quarterly
TDS, m
Monthly/Quarterly
Total Hardness,
m
Monthly/Quarterly
TSS, m
Monthly/Quarterly
Temperature, °C
Monthly/Quarterly
_
Specific
Conductance,
mho/cm
Monthly/Quarterly
* Federally enforceable only.
If the facility is unable to obtain a seep sample due to the dry or low flow conditions preventing
the facility from obtaining a representative sample, the "no flow" should be reported on the
DMR. This requirement is established in the Section D of the Standard Conditions and 40 CFR
122.410).
ASH POND DAMS
Seepage through earthen dams is common an is an expected consequence of impounding water
with an earthen embankment. Even the tighte t, best -compacted clays cannot prevent some
water from seeping through them. Seepage is not necessarily an indication that a dam has
structural problems, but should be kept in check through various engineering controls and
regularly monitored for changes in quantity or'iquality which, over time, may result in dam
failure.
REASONABLE POTENTIAL ANALYSIS (RPA)
The Division conducted EPA -recommended analyses to determine the reasonable potential for
toxicants to be discharged at levels exceeding ater quality standards/EPA criteria by this
facility from outfall 002 (Ash Pond). For the poses of the RPA, the background
concentrations for all parameters were assumed tmibe below detections level. The RPA uses 95%
probability level and 95% confidence basis in accordance with the EPA Guidance entitled
"Technical Support Document for Water Quality -based Toxics Control."
Calculations included: As, Be, Cd, Total Phenolic Compounds, Cr, Cu, CN, Pb, Hg, Mo, Ni, Se,
Ag, Zn, and Fe (please see attached). The renew 1 application listed 0.19 MGD as a current flow.
The analysis indicates no reasonable potential tov olate the surface water quality standards or EPA
criteria.
The Division also considered data for other parameters of concern in the EPA Form 2C that the
facility submitted for the renewal. The majority o�he parameters were not detected in the
discharge. The Division reviewed the following p ameters that were detected in the discharge
and have applicable state standards or EPA criteria for Class C WS -IV stream: fecal coliform,
nitrate, Al, Ba, B, Co, Mn, Sb, and Tl. Most of the a parameters were well below the state
standards/EPA criteria. Only 1 parameter exceeded EPA criteria: Al (162 ug/L is above 87 ug/L).
Considering the in -stream waste concentration of o y 0.4%, even Al is not expected to violate
applicable water quality criterion.
Fact She t
NPDES NC0004911 Renewal
Page 4 1

The RPA was also conducted for the combined flow from all the seeps. The highest
concentration for each constituent was chosen from one of the 12 seeps and used for the RPA.
The RPA was not considered for the parameters that don't have an applicable state water quality
standard. Calculations included: As, Cd, Chlorides, Cr, Cu, F, Pb, Hg, Ni, Se, Zn, Ba, Fe, and
Mn (please see attached). The analysis indicates no reasonable potential to violate the water
quality standards or EPA criteria. The combined flow volume for all the seeps was measured at
0.14 MGD. However, the flow of 0.5 MGD was used for the RPA to incorporate a safety factor,
account for potential new seeps that might emerge in the future or increase in flow volume at the
existing seeps.
The RPA was also conducted for the Outfall 011. Calculations included: As, Cd, Chlorides, Cr,
Cu, F, Pb, Hg, Ni, Se, Zn, Ba, Fe, and Mn (please see attached). The analysis indicates no
reasonable potential to violate the water quality standards or EPA criteria. The flow volume for
the Outfall 011 was measured at 0.00036 MGD. However, the flow of 0.001 MGD was used for
the RPA to incorporate a safety factor and potential increase in flow.
The RPA analysis indicates that existing discharges from the facility outfalls will not cause
contravention of the state water quality standards/ EPA criteria.
The proposed permit requires that EPA methods 200.7 or 200.8 (or the most current versions)
shall be used for analyses of all metals except for total mercury.
DEWATERING — OUTFALL 002
To meet the requirements of the Coal Ash Management Act of 2014, the facility needs to
dewater two ash ponds by removing the interstitial water from ash ponds and excavate the ash to
deposit it in the landfills. The facility highest discharge rate from the dewatering process will be
1.45 MGD. The facility submitted data for the surface water in the ash ponds, interstitial water
in the ash, and interstitial ash water that was treated by 20 µm filter and 0.45 µm filter. To
evaluate the impact of the dewatering on the receiving stream the RPA was conducted for the
wastewater that will be generated by the dewatering process. To introduce the margin of safety,
the highest measured concentration for a particular parameter was used. The RPA was conducted
for As, Cd, Chlorides, Cr, Cu, F, Pb, Mo, Hg, Ni, Se, Zn, Ba, Fe, and Mn, SO4, Al, B, Sb, and Tl
(please see attached).
Based on the results of the RPA, the limit for Total Aluminum will be added to the dewatering
effluent page.
TECHNOLOGY BASED EFFLUENT LIMITS OUTFALL002 AND OUTFALL 010
The existing federal regulations require development of Technology Based Effluent Limits
(TBELs) for the parameters of concern. Since the EPA has not promulgated any new Effluent
Guidelines for Power Plants since 1982, the Division has reviewed the performance of the
existing coal-fired power plants to establish TBELs: Marshall Steam Station, Belews Steam
Station, and Allen Steam Station. Two of these facilities (Belews and Allen) were used by EPA
to establish the proposed Effluent Guidelines for Power Plants. The Division focused on the
following parameters: Total Arsenic, Total Mercury, Total Selenium, and Nitrate/nitrite as N.
These parameters are consistent with the parameters selected by EPA in the proposed Effluent
Guidelines. The Division agrees with the EPA statement from the proposed Effluent Guidelines
that justifies TBEL limitations for only four pollutants of concern: "Effluent limits and
monitoring for all pollutants of concern is not necessary to ensure that the pollutants are
adequately controlled because many of the pollutants originate from similar sources, have similar
Fact Sheet
NPDES NC0004961 Renewal
Page 5

treatabilities, and are removed by similar mechanisms. Because of this, it may be sufficient to
establish effluent limits for one pollutant as a surrogate or indicator pollutant that ensures the
removal of other pollutants of concern."
Based on the review of the effluent data for the past 5 years the Division established the
following TBELs for the coal-fired power plants in North Carolina. The monthly average limits
for Total Arsenic and Total Selenium are based on 95th percentile of the effluent data, which is
consistent with the EPA methodology, and daily maximum limits for these constituents are based
on the 99.9' percentile of the effluent data. The Total Mercury limit is based on the Statewide
Mercury TMDL implementation strategy and was established by the Division previously.
Total Arsenic —10.5 µg/L (Monthly Average); 14.5 µg/I, (Daily Maximum)
Total Selenium —13.6 µg/L (Monthly Average); 25.5 pg/L (Daily Maximum)
Total Mercury — 47.0 ng/L (Monthly Average); 47.0 ng/L (Daily Maximum)
The Division does not have any long-term data for Nitrate/nitrate as N. Therefore, the limits for
this parameter are based on the proposed EPA Effluent Guidelines.
Nitrate/nitrite as N — 0.13 mg/L (Monthly Average); 0.17 mg/L (Daily Maximum)
Facility is allowed 4.5 years from the effective date of the permit to comply with the TBELs
(Outfall 002 only—Ash Pond Discharge). This time period is provided in order for the facility to
budget, design, and construct the treatment system. The compliance schedule is consistent with
the proposed EPA Effluent Guidelines that require compliance with the TBELs "as soon as
possible within the next permit cycle beginning July 1, 2012". Since the permit cycle is 5 years,
the Effluent Guidelines will allow the facility to comply with the TBELs by June 30, 2022. This
permit has a more stringent requirements, the facility shall comply with the TBELs by the end of
2019.
In the interim, the facility shall comply with the BPJ temporary limits that are derived by
multiplying the proposed TBELs by 5, please se below:
Total Arsenic — 52.5 µg/L (Monthly Average); 7 .5 µg/L (Daily Maximum)
Total Selenium — 68.0 µg/L (Monthly Average); 127.5 µg/L (Daily Maximum)
Nitrate/nitrite as N — 0.65 mg/L (Monthly Avera e); 0.85 mg/L (Daily Maximum)
Although these interim limits higher than the proposed TBELs, they are significantly lower than
the allowable concentrations determined by the Reasonable Potential Analysis (RPA) and should
be protective of the water quality in the receiving �tream. The RPA allowable concentrations are
listed below:
Total Arsenic —13,632.3 µg/L (Monthly Average) 91,690.8 pg/L (Daily Maximum)
Total Selenium —1,363.2 pg/L (Monthly Average) 12,492.0 µg/L (Daily Maximum)
MERCURY EVALUATION
The State of North Carolina has a state-wide mercu impairment. The TMDL has been developed
to address this issue in 2012. The TMDL included he implementation strategy, both documents
were approved by EPA in 2012.
The mercury evaluation was conducted in accordancelwith the Permitting Guidelines for Statewide
Mercury TMDL.
Fact Sheet
NPDES NC0004961
Page 6

Year
2011
2012
2013
2014
Annual average
0.76
1.15
0.54
0.83
concentration (ng/L)
Maximum sampling
1.25
1.56
0.62
1.15
result (ng/L)
Allowable mercury concentration for this facility is 439.1 ng/L. All Annual average mercury
concentrations are below allowable. All maximum sampling results are below TBEL of 47.0 ng/L.
Based on the Permitting Guidelines for Statewide Mercury TMDL, the limits are not required.
TEMPERATURE VARIANCE REMOVAL -OUTFALL 001
The facility historically had a temperature variance in accordance with CWA Section 316(a). In
order to maintain the variance the facility had to conduct annual biological and chemical
monitoring of the receiving stream to demonstrate that it has a balanced and indigenous
macroinvertebrate and fish community. The latest BIP (balanced and indigenous population)
report was submitted to DWQ in August of 2009. The ESS has reviewed the report and
concluded that the Mountain Island Lake near Riverbend Station has a balanced and indigenous
macroinvertebrate and fish community.
Since the facility discontinued electricity generation in 2013, it does not wish to request
continuation of the temperature variance. Therefore, Effluent Sheet A. (l.) was modified to
reflect temperature requirements without a variance.
CWA SECTION 316(B)
Since the facility discontinued electricity generation in 2013 and does not use cooling water, it
will not be the subject to the Section 316(b) of Clean Water Act.
INSTREAM MONITORING -OUTFALL 002
The facility historically had 7 monitoring station, 2 located upstream and 5 located downstream.
It is recommended that the monitoring will continue.
The permit also required semi-annual upstream and downstream monitoring of the ash pond
discharge. Upstream site (Station B) is approximately 2 miles upstream of the discharge and
downstream location (Station C) is approximately 0.5 miles downstream of the discharge. These
monitoring stations have been established through the BIP monitoring program, which was
required to maintain 316(a) temperature variance. The monitored parameters are: As, Cd, Cr, Cu,
Hg, Pb, Se, Zn, and Total Dissolved Solids (TDS). The majority of the results are below
detection level (As, Cd, Cr, Pb, Se, Hg, Zn) the rest of the results are below water quality
standards (Cu and TDS). Only Cu demonstrated an increase at the downstream monitoring
location. These results are consistent with the previous monitoring results.
It is required that the monitoring at the stations B and C will continue until discharges from the
station are ceased. It is also required that the facility uses low level method 1631 E for all Hg
analysis.
FISH TISSUE MONITORING -OUTFALL 002
The permit required fish tissue monitoring for As, Se, and Hg near the ash pond discharge once
every 5 years. This frequency is consistent with EPA guidance. Sunfish and bass tissues were
analyzed for these trace elements. The results were below action levels for Se and Hg (10.0 µg/g
— Se, 0.40 µg/g — Hg, NC) and screening value for As (1.20 — pg/g, EPA). These results are
consistent with the previous monitoring results.
Fact Sheet
NPDES NC0004961 Renewal
Page 7

TOXICITY TESTING- Outfall 002:
Current Requirement: 24hr Chronic P/F @ 10%
Recommended Requirement: 24hr Chronic P/F @ 2.7% (flow during dewatering)
Monitoring Schedule: January, April, July, October
This facility has passed all chronic toxicity tests during the previous permit cycle, please see
attached. The change in the instream waste concentration was made based on the significant
decrease in the discharge volume.
For the purposes of the permitting, the long term average flow was used in conjunction with the
7Q 10 summer flow to calculate the percent effluent concentrations to be used for WET.
COMPLIANCE SUMMARY
Notwithstanding the civil lawsuit filed for unauthorized discharges and groundwater
exceedances/violations, based on the monitoring required under the current version of the permit
there were no violations of effluent standards gontained in the permit.
PERMIT LIMITS DEVELOPMENT
• The pH limits (Outfalls 002, 002A, and 10) in the permit are based on the North Carolina
water quality standards (15A NCAC 2B 0200).
• The limits for Oil and Grease and Total Suspended Solids (Outfall 002 and Outfall 002A)
are based on the Best Professional Judgment and are lower than prescribed in the 40 CFR
423.
• The limits for Total Copper and Total Iro (Outfall 002 and Outfall 002A) were
established in accordance with the 40 CF 423.
• The temperature limits (Outfall 001) ar based on the North Carolina water quality
standards (15A NCAC 2B .0200).
• The turbidity limit in the permit (Outfall 00 ) is based on the North Carolina water
quality standards (15A NCAC 2B .0200).
• The Whole Effluent Toxicity limit (Outfall 02) is based on the requirements of 15A
NCAC 2B.0500.
• The limits in seep outfalls are based on the N water quality standards.
REQUESTED MODIFICATIONS
With the permit application for renewal, Duke Energy Carolinas, LLC has requested the following
modifications:
Monitoring Frequencies (Outfall 002)
Parameter
Present
Proposed
Flow
Total Nitro en
Weekly
2/ ear
Monthly
1 / ear
Total Phosphorus
2/year
1/ ear
Total Copper
Quarterly
none
Total Iron
Quarterly
none
These requests could not be granted because the Divis
with the water quality standards and criteria during the
process.
Fact Sheet
NPDES NC0004961
Page 8
needs these data to assure compliance
;oming ash pond decanting/dewatering

PROPOSED CHANGES:
• Monitoring requirements for Outfall 001 were adjusted due to the discontinuation of
once -through cooling water discharges.
• The Ash Pond Closure Special Condition was updated (Please see A. (15.)).
• The Seep Outfall 010 (Please see A. (5.)) and Seep Pollutant Analysis Special Condition
(Please see A. (17.)) were added to the permit.
• The Appendix A and Appendix B were added to the permit.
• A separate effluent page for the dewatering of the ash ponds (Outfall 002) was added to
the permit (Please see Special Condition A. (3.)).
• The Boiler Cleaning Waste Special Condition was eliminated due to the discontinuation
of the power generation.
• The Section 316(a) of CWA Thermal Variance Special Condition was eliminated due to
the discontinuation of the power generation.
• The Section 316(b) of CWA Special Condition was eliminated due to the discontinuation
of the power generation.
• The turbidity limit was added to the permit to meet the state turbidity standard per 15A
NCAC 2B .0211(3) (k) (Outfall 002).
• The Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total Selenium,
and Nitrate/nitrite as N were added to the permit and are based on the requirements of 40
CFR 125.3(a) , 40 CFR 122.44(a)(1); 40 CFR 125.3(c) and (d) (Outfall 002 and Outfall
010).
• The Interim Technology Based Effluent Limits (Outfall 002) for Total Arsenic, Total
Selenium, and Nitrate/nitrate as N were added to the permit and are based on the
requirements of 40 CFR 125.3(a) , 40 CFR 122.44(a)(1); 125.3(c) and (d).
• Proposed federal regulations require electronic submittal of all discharge monitoring
reports (DMRs) and specify that, if a state does not establish a system to receive such
submittals, then permittees must submit DMRs electronically to the Environmental
Protection Agency (EPA). The Division anticipates that these regulations will be adopted
and is beginning implementation.
The requirement to begin reporting discharge monitoring data electronically using the NC
DWR's Electronic Discharge Monitoring Report (eDMR) internet application has been
added to the permit. (Please see Special Condition A. (18.)).
• The Applicable State Law Special Condition was added to the permit to meet the
requirements of Senate Bill 729 (Coal Ash Management Act, Please see Special Condition
A. (19.)).
• The Outfall 011 (former Stormwater Outfall 1) was added to the permit (Please see A.
(20.)).
PROPOSED SCHEDULE:
Draft Permit to Public Notice: March 6, 2015 (est.)
Permit Scheduled to Issue: July 27, 2015 (est.)
STATE CONTACT:
If you have any questions on any of the above information or on the attached permit, please contact
Sergei Chernikov at [phone] or [e-mail]
Fact Sheet
NPDES NC0004961 Renewal
Page 9

CHANGES IN THE FINAL PERMIT:
• The Outfall 010 was eliminated and the Special Condition A. (16.) was updated to meet
the requirements of The Water Quality Standard Regulatory Revisions Final Rule that
has become effective on October 20, 2015.
• Fish tissue monitoring was increased to annually from once every five years to address
the EPA comment. Please see Special Condition A. (12.).
• The Additional Conditions and Definitions Special Condition was added to the permit
to address the EPA comment. Please see Special Condition A. (20.).
• Measurement frequency was changed from "Episodic' to "Per discharge event"
(Outfall 002A) to address the EPA comment.
• The Flow limit was added for Outfall 002 (dewatering phase) to address the EPA
comment.
• The automatic pump shutoff requirements for TSS limit exceedance was added for
Outfall 002 to address the EPA comment.
• The variance from Monthly Average TSS limit (Outfall 002 and Outfall 011) was
eliminated to address the EPA comment.
• Monitoring frequency for all parameters was increased to Weekly for Outfall 002 to
address the EPA comment.
• The specific date of December 31, 2019 replaced 4.5 years for Outfall 002. This change
was made to address EPA comment. Please see Special Condition A. (2.).
• Clarifying language was added to define the discharge from the ash pond under normal
operating conditions to address the Hearing Officer recommendation and the comment
from the permittee. Please see Special Condition A. (2.).
• The definition of dewatering was added%commendation
Special Condition A. (3.). The definition was
added to address the Hearing Office and the comment from the
permittee.
• The effluent concentration for Whole Effluent Toxicity was changed to correct a typo,
the correct concentration is 2.7%. Please see footnote to Special Conditions A. (2.) and
A. (3.).
• The footnote describing conditions for in nitoring Total Copper and Total Iron was
removed (Outfall 011) to correct an error.
• Description of the wastewater sources for utfall 001 and Outfall 002 was updated to
reflect the current status of the facility.
• Clarifying language was added to the Outf 1002 to define the conditions under which
the limits for Total Copper and Total Iron are applicable. This change was made to
address the Hearing Officer recommendatio .
ADDITIONAL i
• A distinct outfall was created for each seep ith the effluent limits equivalent to the
water quality standards, Technology -Based 1 its (TSS and Oil & Grease) were also
added in accordance with the 40 CFR 423.
• The monthly seep monitoring was extended to a 12 month period, after which the
monitoring will be reduced to quarterly.
• The following requirements were added to the
limit; use of a floating pump station with free
using an adjustable weir; daily monitoring of f
auto pump shut-off if TSS concentration (15 n
daily TSS limit (pumping will be allowed to ci
failure or damage); real time pH monitoring w
Fact Sheet
NPDES NC0004961
Page 10
)ndition A. (2.). — Outfall 001: flow
ter skimmed from the basin surface
v; continuous monitoring of TSS with
ate average) exceeds half the maximum
inue if interruption might result in a dam
an auto shut-off if the 15 -minute

running average pH falls below 6.1 standard units or rises above 8.9 standard units;
drawdown to no less than three feet above the ash; and monitoring for total chromium,
total lead, total cadmium, and total dissolved solids.
Fact Sheet
NPDES NC0004961 Renewal
Page 11

sS)V,IL
Seep Flows and Analytical Results
Riverbend Seep Monitoring
April 2014
4
Notes
1 Flow measurements and analytical samples were collected on April 29, 2014
2 N/A indicates not applicable
0,lns , M 1)
Nn
I -Z, 0
IA 11
CM
Units
Ash Basin
(in- process)
S-1
S-2
S-3
S-4
S-5
S-6
5-7
S-8
S-9
S-li
5-12
2775
a
' FS�� t�
278
✓v SLS
-- Oil &Grease
mg/I
<
5
<
5
<
5
<
5
<
5
<
5
<
5
<
5
<
5
<
5
<
5
<
5
u <
5
<
5
-- COD
m /I
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
<
20
Cl - Chloride 00940
m /l
5
46
57
3
66
7
63
52
27
67
59
7
5
49
Fluoride
m /I
<
1
<
<
<
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
SO4 - Sulfate 00945
m /I
55
63
6
49
31
38
20
3 1
15
30
26
41
39
38
H - Mercury 71900
u /I
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
<
005
Al -Aluminum 01105
m /I
0 119
0 115
0 034
0 065
0 193
394
0 022
0 159
0 216
0 366
0 047
0 029
0 237
0 158
Ba - Barium 01007
m /I
0 129
005
0 039
0 091
0 043
0 059
0 017
0 024
0 019
0 043
0 027
CO 098
0 015
0 014
B - Boron 01022
m /I
0 294
0 089
0 371
0 349
0 361
qQ,443
0 154
0 082
<
005
0 388
0 259
0 2
<
005
<
005
+=.. Ca -Calcium
m /I
153
142
409
105
683
514
294
376
749
633
355
332
409
406
Hardness
m /I CaCO3
51
588
131
406
419
371
315
261
293
396
214
33
175
174
` Fe - Iron 01045
m /l
0 051
51
0 078
014
0 539
103
0 293
088
215
072
0 472
0 374
021
0 132
"— Mg -Magnesium
m /I
313
568
709
348
604
589
587
405
258
577
304
6
178
177
q Mn - Manganese 01055
m /I
0 123
103
0 597
0 841
0 429
0 282
1
0 345
0 028
0208
123
114
002
0 014
Zn - Zinc 01092
m /I
007
<
0 005
<
0 005
0 019
<
0 005
<
0 005
<
0 005
<
0 005
<
0 005
<
0 005
<
0 005
0 018
<
0 005
<
0 005
Sb - Antimony 01097
u /I
128
<
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
As - Arsenic 01002
u /l
741
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
Cd - Cadmium 01027
u /I
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
Cr - Chromium 01034
u /1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
Cu - Copper 01042
gra
321
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1158
163
168
Pb - Lead 01051
u /I
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
Molybdenum Mo
u /L
227
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
Ni - Nickel 01067
u /I
21
<
1
<
1
8 77
<
1
247
1
207
<
1
148
11
633
<
1
<
1
Se - Selenium 01147
u /I
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
<
1
TI-Thalhum 01059
u /I
0917
<
02
<
02
<
02
<
02
<
02
<
02
<
02
<
02
<
02
<
02
<
02
<
02
<
02
TDS - Total Diss Solids 70300
m /l
95
140
190
90
88
86
66
51
81
84
56
78
39
38
o TSS -Total Suspended Solids
m /L
<
5
it
26
<
5
<
5
9
<
5
7
<
5
11
<
5
<
5
<
5
<
5
H
su
712
59
676
557
798
629
762
662
676
638
59
602
719
721
Temperature
°C
2099
1581
168
1675
1584
1649
1659
1571
1723
16 01
1556
1753
17 96
1799
Specific conductance
u5/cm
1606
207 1
296
150
133
134
104
70
83
126
952
1293
579
577
Flow
MGD
0 163
000056 1
00044 1
000562
001754 1
000287 1
002085
00332
00245
001206
000835
000568
NIA
N A
Notes
1 Flow measurements and analytical samples were collected on April 29, 2014
2 N/A indicates not applicable
0,lns , M 1)
Nn
I -Z, 0
IA 11
CM