NC0004961_Error Correction Letter_20161123

Water Resources
ENVIRONMENTAL QUALITY
PAT MCCRORY
Governor
DONALD R VAN DER VAART
Secretary
S JAY ZIMMERMAN
Director
November 23, 2016
Mr. Harry Sideris, Senior Vice President
Environmental, Health and Safety
Duke Energy Carolinas, LLC
Mail Code EC 13K
P.O. Box 1006
Charlotte, North Carolina 28201-1006
Dear Mr. Sideris:
Subject: Error Correction Letter
Permit No. NC0004961
Riverbend Steam Station
Gaston County
On February 12, 2016, the Division of Water Resources issued NPDES Permit No.
NC0004961 for Riverbend Steam Station. It has been brought to our attention that the
Permit has inconsistent monitoring frequency for the Whole Effluent Toxicity testing.
The correct monitoring frequency shall be Monthly.
Therefore, the Division made a correction to the appropriate pages in the NPDES
Permit. Please insert the enclosed corrected sheets and discard the old sheets. This
permit modification becomes effective on the effective date of the permit.
All other terms and conditions in the original permit remain unchanged and in full
effect. These modifications are issued pursuant to the requirements of North Carolina
General Statute 143-215.1 and the Memorandum of Agreement between North Carolina
and the U.S. Environmental Protection Agency dated December 6, 1983.
In addition, due to the withdrawal of the contested case by Duke Energy, the effective
date of the permit shall be December 1, 2016.
If any parts, measurement frequencies or sampling requirements contained in this
modification are unacceptable to you, you have the right to an adjudicatory hearing
upon written request within thirty (30) days following receipt of this letter. This request
must be in the form of a written petition, conforming to Chapter 150B of the North
Carolina General Statutes, and filed with the Office of Administrative Hearings, Post
Office Drawer 11666, Raleigh, North Carolina 27604. Unless such demand is made,
this decision shall be final and binding. If you have any questions concerning this
permit, please contact Sergei Chernikov at telephone number [phone].
State of North Carolina I Environmental Quality I Water Resources
1617 Mail service Center I Raleigh, North Carolina 27699-1611
919 707 9000

Sincerely,
S. Jay Zimmerman, P.G.
Director, Division of Water Resources
Hardcopy: Central Files
NPDES Files
Wilmington Regional Office, SWPS
E -copy: US EPA, Region IV
Aquatic Toxicology Unit
Carrie Ruhlman, WSS

(� DUKE
ENERGY
November 16, 2016
Mr. Jeff Poupart
NC DEQ— DWR
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
Subject: Request for Confirmation of Permit Effective Date and
Correction of Typographical Errors in NPDES Permit
Riverbend Station
NPDES Permit NC0004961
Gaston County
Dear Mr. Poupart:
Richard E Bakerk
Director Environmental Programs
EHS CCP
526 S Church Street
Mail Code EC13K
Charlotte, NC 28202
[phone]
On February 12, 2016, the Division of Water Resources (the Division) issued a renewed NPDES permit for
Duke Energy's Riverbend Station. Duke Energy filed a contested case over the terms of that permit in
the North Carolina Office of Administrative Hearings, staying the effective date of the permit terms.
The contested case has been resolved through issuance of a Special Order by Consent. Duke Energy is
preparing the necessary paperwork to withdraw the contested case in accordance with the terms of the
Special Order by Consent. It is our current understanding that the proposed effective date of the
Riverbend permit will be December 1, 2016 based on Duke Energy's withdrawal of our contested case as
required by the terms of the Special Order by Consent. Duke Energy requests confirmation of this
effective date for our files.
Additionally, the permit that was issued in February 2016 contains a number of typographical errors that
could not be addressed in the Special Order by Consent process. These items were present in previous
versions of the draft permit and were noted by Duke Energy in its December 15, 2014 written comments
on the draft permit. Duke Energy requests the following items be corrected.
1. On Page 4 of 27 (Note 3), there is an inconsistent sampling frequency requirement for the
Chronic Toxicity test. Duke requests this be made consistent and be adjusted to monthly by
removal of the specific months in the footnote. This is consistent with all other recently issued
NPDES permits.
On Page 6 of 27 (Note 4), there is an inconsistent sampling frequency requirement for the
Chronic Toxicity test. Duke requests this error be corrected and the sampling frequency be
made consistent and adjusted to a monthly requirement. This is consistent with all other
recently issued permits. On Page 8 of 27, Condition A.(5) still refers to quarterly requirement
for Toxicity testing. Duke requests that this error be corrected to align with the changes made
above.
Duke Energy requests your prompt correction of the above items. This will allow Duke Energy to
effectively implement the conditions of the permit and assure the permit requirements are clear to
anyone reading the permit. Safe storage of coal ash across all of our coal fired generation fleet is a

priority for Duke Energy. The issuance of the final NPDES permit is a critical prerequisite to de -watering
the ash basins at Riverbend and moving forward with the Company's previously announced intent to
excavate the Riverbend ash basins. If you have any questions pertaining to this request, please contact
me at [phone] or shannon.langley at [phone] or [e-mail].
Sincerely,
�U � 0/-t
Richard E Baker Jr.
Director Environmental Programs
EHS CCP
Cc- Brad Loveland
Shannon Langley -via email
Riverbend EC
Sergei Chernikov—via email

Permit NC0004961
A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall
002 -normal operation) [15A NCAC 02B.0400 et seq., 02B.0500 et seq.]
During the period beginning on the effective date of this permit and lasting until expiration, the
Permittee is authorized to discharge from outfall 002 — Ash Pond Discharge (removing the free
water above the settled ash layer that does not involve mechanical movement of the ash).
Such discharges shall be limited and monitored6 by the Permittee as specified below:
EFFLUENT
CHARACTERISTICS
LIMITS
Monthly Daily
Average Maximum
MONITORING REQUIREMENTS
Measurement Sample Type Sample Location
Frequency
Flow
5 74 MGD
Daily
Pump logs or
estimate
Influent or Effluent
Total Suspended Solids8
23 0 m /L
75 0 m /L
Weekly
Grab
Effluent
and Grease
11.0 m /L
15 0 m /L
Weekly
Grab
Effluent
-Oil
Total Copper'
1.0 m /L
10 m /L
Weekly
Grab
Effluent
Total Iron'
10 m /L
10 m /L
Weekly
Grab
Effluent
Total Arsenic
52 5 /L
72.5 /L
Weekly
Grab
Effluent
Total Selenium
68.0 /L
127 5 /L
Weekly
Grab
Effluent
Nitrate/nitrite as N
0 65 m /L
0 85 m /L
Weekly
Grab
Effluent
Total Arsenic
10 5 /V
14 5 /L7
Weekly
Grab
Effluent
Total Selenium
13 6 /V
25 5 /V
Weekly
Grab
Effluent
Total Mercury
47 0 ng/Ls
47 0 n /LS
Weekly
Grab
Effluent
Nitrate/nitrite as N
0.13 m 1U
017 m IU
Weekly
Grab
Effluent
Total Phosphorus, m /L
Weekly
Grab
Effluent
Total Nitrogen (NO2 + NO3 + TKN),
m /L
Weekly
Grab
Effluent
H2
Weekly
Grab
Effluent
Chronic Toxicit 3
Monthly
Grab
Effluent
NTU
Weekly
Grab
Effluent
-Turbidity4,
Total Chromium, /L
Weekly
Grab
Effluent
Total Cadmium, /L
Weekly
Grab
Effluent
Total Lead, /L
Weekly
Grab
Effluent
TDS, m /L
Weekly
Grab
Effluent
Notes:
1. The limits for total copper and total iron only apply when chemical metal cleaning wastewaters
are being discharged.
2. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units. The facility
shall conduct a real time pH monitoring with an auto shut-off if the 15 -minute running average
pH falls below 6.1 standard units or rises above 8.9 standard units.
3. Whole Effluent Toxicity shall be monitored by chronic toxicity (Ceriodaphnia) P/F at 2.7%, see
Part A. (5.) for details.
4. The discharge from this facility shall not cause turbidity in the receiving stream to exceed 50
NTU. If the instream turbidity exceeds 50 NTU due to natural background conditions, the
discharge cannot cause turbidity to increase in the receiving stream.
NTU - Nephelometric Turbidity Unit.
5. The facility shall use EPA method 1631E.
6. No later than 270 days from the effective date of this permit, begin submitting discharge
monitoring reports electronically using NC DWR's eDMR application system. See Special
Condition A. (18.).
7. The TBEL limits shall be met no later than December 31, 2019. This time period is provided
in order for the facility to budget, design, and construct the treatment system. Permit might
be re -opened to implement the final EPA Effluent Guidelines and more stringent limits
might be added.
8. The facility shall continuously monitor TSS concentration and the dewatering pump shall be
shutoff automatically when the one half of the Daily Maximum limit (15 minutes average) is
Page 4 of 27

.
Permit NC0004961
A. (3.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall
002 -dewatering phase) [15A NCAC 02B.0400 et seq., 0213 .0500 et seq.]
During the period beginning on the commencement date of the dewatering operations and lasting
until expiration, the Permittee is authorized to discharge from outfall 002 - Ash Pond Discharge
(Dewatering -removing the interstitial water). Such discharges shall be limited and monitored7 by
the Permittee as specified below -
EFFLUENT
CHARACTERISTICS
LIMITS
MONITORING REQUIREMENTS
Monthly' Daily Measurement Sample Type Sample Location
Average' Maximum Frequenc
Flow
1.45 MGD
Weekly
Pump logs or
estimate
Influent or Effluent
Total Suspended Solids'
23.0 m /L
75.0 m /L
Weekly
Grab
Effluent
Oil and Grease
110 m /L
15 0 m /L
Weekly
Grab
Effluent
Total Copper2
10 m /L
10 m /L
Weekly
Grab
Effluent
Total Ironz
10 m /L
10 m /L
Weekly
Grab
Effluent
Total Arsenic
10.5 /L
14 5 /L
Weekly
Grab
Effluent
Total Selenium
13 6 /L
25 5 /L
Weekly
Grab
Effluent
Total Aluminum
318 m /L
3.18 m /L
Weekly
Grab
Effluent
Total Mercury
47 0 n /L6
47 0 n /L6
Weekly
Grab
Effluent
Nitrate/nitrate as N
013 m /L
017 m /L
Weekly
Grab
Effluent
Total Phosphorus, m /L
Weekly
Grab
Effluent
Total Nitrogen (NO2 + NO3 + TKN),
m /L
Weekly
Grab
Effluent
H3
Weekly
Grab
Effluent
Chronic Toxicit 4
Monthly
Grab
Effluent
Turbidity5, NTU
Weekly
Grab
Effluent
Notes:
1. The facility shall continuously monitor TSS concentration and the dewatering pump shall be
shutoff automatically when the limits are exceeded.
2. The limits for total copper and total iron only apply when chemical metal cleaning
wastewaters are being discharged.
3. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
4. Whole Effluent Toxicity shall be monitored by chronic toxicity (Ceriodaphnia) P/F at 2.7%, see
Part A. (5.) for details.
5. The discharge from this facility shall not cause turbidity in the receiving stream to exceed 50
NTU. If the instream turbidity I exceeds 50 NTU due to natural background conditions, the
discharge cannot cause turbidity to increase in the receiving stream.
NTU - Nephelometric Turbidity Unit.
6. The facility shall use EPA method 1631E.
7. No later than 270 days from the effective date of this permit, begin submitting discharge
monitoring reports electronically using NC DWR's eDMR application system. See
Special Condition A. (18.).
The metal cleaning waste, coal pile runoff, ash transport water, domestic wastewater,
and low volume waste shall be discharged into the ash settling pond.
No chemicals, cleaners, or other additives may be present in the vehicle wash water
to be discharged from this outfall. There shall be no discharge of floating solids or
visible foam in other than trace � amounts.
The level of water in the pond should not be lowered more than 1 ft/week unless
approved by the DEQ Dam Safety Program.
Page 6 of 27

Permit NC0004961
A. (5.) CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT (Outfall 002) [15A NCAC
02B .0200 et seq.]
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant
mortality to Ceriodaphnia dubia at an effluent concentration of 2 7%.
The permit holder shall perform at a minimum, monthlu monitoring using test procedures outlined in
the "North Carolina Ceriodaphnia Chronic Effluent Bioassay Procedure," Revised December 2010, or
subsequent versions or "North Carolina Phase II Chronic Whole Effluent Toxicity Test Procedure"
(Revised- December 2010) or subsequent versions Effluent sampling for this testing must be
obtained during representative effluent discharge and shall be performed at the NPDES permitted
final effluent discharge below all treatment processes.
If the test procedure performed as the first test of any single month results in a failure or ChV
below the permit limit, then multiple -concentration testing shall be performed at a minimum,
in each of the two following months as described in "North Carolina Phase II Chronic Whole
Effluent Toxicity Test Procedure" (Revised -December 2010) or subsequent versions.
All toxicity testing results required as part of this permit condition will be entered on the Effluent
Discharge Monitoring Form (MR -1) for the months in which tests were performed, using the
parameter code TGP3B for the pass/fail results and THP3B for the Chronic Value. Additionally,
DWR Form AT -3 (original) is to be sent to the following address -
Attention. North Carolina Division of Water Resources
Water Sciences Section/Aquatic Toxicology Branch
1623 Mail Service Center
Raleigh, North Carolina 27699-1623
Completed Aquatic Toxicity Test Forms shall be filed with the Water Sciences Section no later than
30 days after the end of the reporting period for which the report is made.
Test data shall be complete, accurate, include all supporting chemical/ physical measurements and
all concentration/ response data, and be certified by laboratory supervisor and ORC or approved
designate signature. Total residual chlorine of the effluent toxicity sample must be measured and
reported if chlorine is employed for disinfection of the waste stream.
Should there be no discharge of flow from the facility during a month in which toxicity monitoring is
required, the permittee will complete the information located at the top of the aquatic toxicity (AT)
test form indicating the facility name, permit number, pipe number, county, and the month/year of
the report with the notation of "No Flow" in the comment area of the form The report shall be
submitted to the Water Sciences Section at the address cited above.
Should any test data from this monitoring requirement or tests performed by the North Carolina
Division of Water Resources indicate potential impacts to the receiving stream, this permit may be
re -opened and modified to include alternate monitoring requirements or limits
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum
control organism survival, minimum control organism reproduction, and appropriate environmental
controls, shall constitute an invalid test and will require immediate follow-up testing to be
completed no later than the last day of the month following the month of the initial monitoring.
A. (6.) BIOCIDE CONDITION
The permittee shall not use any biocides except those approved in conjunction with the permit
application. The permittee shall notify the Director in writing not later than ninety (90) days prior to
instituting use of any additional biocide used in cooling systems which may be toxic to aquatic life
other than those previously reported to the Division of Water Resources. Such notification shall
include completion of Biocide Worksheet Form 101 and a map locating the discharge point and
Page 8 of 27