NC0004979_Draft Permit (Major Modification)_20210406

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ROY COOPER4 141 __„,z1
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Governor ir°
DIONNE DELLI-GATTI
Secretary *4*m... oe
S.DANIEL SMITH NORTH CAROLINA
Director Environmental Quality
April 6, 2021
Mr. Paul Draovitch, Senior Vice President
Environmental, Health and Safety
Duke Energy Progress, LLC
Mail Code EC13K
P.O. Box 1006
Charlotte, North Carolina 28201-1006
Subject: Draft NPDES Major Modification
Permit NC0004979
Allen Steam Station
Gaston County
Facility Class I
Dear Mr. Draovitch:
The Division has received your request for a Major Modification of the subject
permit. The request has been granted. Please review this Major Modification to ensure
thorough understanding of the conditions and requirements it contains.
The draft permit modification contains the following significant changes from
your current permit:
• The Bottom Ash Purge was added to the list of waste streams discharged to the
Retention Basin.
• The wastewater generated by the dewatering process and extracted
groundwater were added to the to the Retention Basin to achieve timely closure
of the Ash Pond and provide greater operational flexibility.
• The flow limit for dewatering operations was increased from 1.0 MGD to 3.0
MGD to achieve timely closure of the Ash Pond.
• The Upstream and Downstream monitoring locations were moved to monitor
discharge from the Retention Basin.
• The pH limits at the Internal Outfall 005 were removed to be consistent with the
requirements in 40 CFR 423.
• The Technology Based Effluent Limits for Total Arsenic, Total Mercury, Total
Selenium, and Nitrate/nitrite as N were removed from the permit (Outfall 005 -
North Carolina Department Environmental Quality of rces
v512 North Salisbury Street 1 of1617 Mail Service Center I Raleigh,Division NorthWater Carolina Resou27699-1617
NORTH OAROUNA
DepnrImal a EnrIrorensatml WOW 919.707.9000

FGD wastewater) based on the latest update to the 40 CFR 423 and due to the
early retirement of the Allen Steam Station. The Monthly Average and Daily
Maximum numeric limits for these parameters were replaced with the Quarterly
Average numeric limits for Total Arsenic, Total Selenium, and Total Mercury
and a narrative limit that requires the facility to properly operate and maintain
the existing FGD wastewater treatment equipment.
• The Technology Based Effluent Limits for TSS and Oil and Grease were added
to the permit (Outfall 005) based on the latest update to the 40 CFR 423.
• The Annual Progress Report requirement was added to the permit (see Special
Condition A. (19.) based on the latest update to the 40 CFR 423.
• The RPA for Retention Basin was conducted by adding the highest reported
concentration of the contaminants in the interstitial wastewater. The flow
volume was also increased from 3.3 MGD to 3.5 MGD based on the latest
estimates that incorporate flor from the CCR landfill. The limits for As were
added as a result of this RPA (Outfall 006).
• The RPA for Ash Basin dewatering phase was conducted by increasing flow from
1.0 MGD to 3.0 MGD. No new limits were added as a result of this RPA (Outfall
002).
• The Special Condition that requires electronic submittal of all discharge
monitoring reports was changed based on the latest update to the NPDES
Electronic Reporting Rule (See Special Condition A. (26.)).
• The Toxicity Test Instream Waste Concentrations for dewatering and Retention
basin have been adjusted (Outfall 002 dewatering and Outfall 006) to account for
the increased flow volume.
Please provide any comments you have regarding the draft permit to this
office by May 7, 2021. At this time, the Division is also publishing a notice in the
newspapers of general circulation in Gaston County, inviting public comment on the
Draft Major Modification. Following the 30-day comment period, we will review all
pertinent comments received and take appropriate action on the permit modification.
If you have any questions about the NPDES permit process, please contact me
at the following e-mail address: sergei.chernikovAncdenr.gov, or telephone number:
919-707-3606.
Sincerely, 4
Sergei Chern ov, Ph.D.
Environmental Engineer III
Industrial NPDES Permitting Unit
cc: Central Files
NPDES Files
EPA Region IV (e-copy)
Mooresville Regional Office/Water Quality (e-copy)
Mooresville Regional Office/PWS (e-copy)
WSS/Aquatic Toxicology Unit (e-copy)
Q.)1NorthNorth CarolinaSalisbury DepaStrrtmenteet1 of1617 EnMvironmentalailService Center I Raleig Quality 1 Division
h. of WaterNorthCarolina Resources
512 699-1617
°ipiY"itl a ei1me"^W�'"\ /.4°. 919.707.9000

Permit NC0004979
STATE OF NORTH CAROLINA
DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF WATER RESOURCES
Draft PERMIT
TO DISCHARGE WASTEWATER UNDER THE
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
In compliance with the provision of North Carolina General Statute 143-215.1,other lawful standards and
regulations promulgated and adopted by the North Carolina Environmental Management Commission,and the
Federal Water Pollution Control Act,as amended,
Duke Energy Carolinas, LLC
is hereby authorized to discharge wastewater from a facility located at the
Allen Steam Station
253 Plant Allen Road (NCSR 2525)
Belmont
Gaston County
to receiving waters designated as the Catawba River(Lake Wylie),unnamed tributary to the Catawba River,and
South Fork Catawba River in the Catawba River Basin in accordance with effluent limitations,monitoring
requirements,and other applicable conditions set forth in Parts I,II,and III.
This permit modification shall become effective
This permit and authorization to discharge shall expire at midnight on July 31,2023.
Signed this day
S.Daniel Smith,Director
Division of Water Resources
By Authority of the Environmental Management Commission
Page 1 of 26

Permit NC0004979
SUPPLEMENT TO PERMIT COVER SHEET
All previous NPDES Permits issued to this facility,whether for operation or discharge are hereby revoked.As of
this permit issuance,any previously issued permit bearing this number is no longer effective.Therefore,the
exclusive authority to operate and discharge from this facility arises under the permit conditions,requirements,
terms,and provisions included herein.
Duke Energy Carolinas,LLC is hereby authorized to:
1. Continue to discharge:
• Outfall 001: once through cooling water.
• Outfall 002:Ash Basin discharge.This outfall includes domestic wastewater,stormwater from the
coal pile area,miscellaneous stormwater flows,ash sluice,wastewater from turbine non-destructive
testing,landfill leachate,FGD blowdown,yard drain sump,water treatment filter backwash,
extracted groundwater,laboratory wastes,and the power house sump at Unit 5. The domestic
waste is pre-treated by a septic tank. Outfall 002 wastewater is treated using chemical coagulation,
settling,and pH neutralization. Outfall 002 and Outfall 006 might be operational at the same time
during the transition period.
• Outfall 002A: coal yard sump overflow(discharge from coal handling and storage areas).
• Outfall 002B:power house sump overflow(floor wash water,boiler blowdown,water treatment
waste,condensates,equipment cooling water,sealing water and miscellaneous leakage).
• Outfall 003: miscellaneous equipment non-contact cooling and sealing water.
• Outfall 004:miscellaneous non-contact cooling water,vehicle washwater,and intake screen
backwash.
• Outfall 006:Upon completion of construction of the Retention Basin,discharge domestic
wastewater,wastewater from ash pond dewatering process,stormwater from the coal pile area,
miscellaneous stormwater flows,ash sluice,wastewater from turbine non-destructive testing,CCR
landfill leachate,FGD blowdown,yard drain sump,water treatment filter backwash,bottom ash
purge from the submerged flight conveyers (purge volume not to exceed 10%of the water systems
volume),extracted groundwater,laboratory wastes,and the power house sump at Unit 5. The
domestic waste is pre-treated by a septic tank. Outfall 006 wastewater is treated using chemical
coagulation,settling,and pH neutralization. Outfall 002 and Outfall 006 might be operational at
the same time during the transition period:
• Outfall 007: the emergency spillway of the new Retention Basin.The spillway is designed for a
flood greater than 100-year event.Sampling of this spillway is waived due to unsafe conditions
associated with sampling during an overflow event.
• Outfall 008: the emergency spillway of the retired Ash Pond.The spillway is designed for a flood
greater than 100-year event.Sampling of this spillway is waived due to unsafe conditions associated
with sampling during an overflow event.
• Toe Drain Outfalls 103 (lat.-35°10.512';long. -8100.360'), 104(lat.-35°10.541';long.-81°0.364'),
108(lat.-35°10.710';long-81°0.384'),and 108B (lat. -35°10.689';long-81°0.391'):4 potentially
contaminated toe drains.
From a facility located at the Plant Allen Steam Station on Plant Allen Road(NCSR 2525),south of
Belmont in Gaston County,and
2. Without adding detergents or chemicals of any kind,discharge Asiatic clam/debris filter backwash from the
intake filter screen,in accordance with condition A. (10.),and
3. Continue to operate a Flue Gas Desulfurization (FGD)wet scrubber wastewater treatment system
discharging to the Ash Basin/Line Retention Basin through Internal Outfall 005;consisting of:
• A flow equalization tank and a maintenance tank
• Feed systems for lime,sulfide,iron addition,polymer,hydrochloric acid,and nutrient addition
• Two clarifiers
Page 2 of 26

Permit NC0004979
• Dual heat exchangers
• Selenium reduction bioreactors
• A sludge treatment system including three filter presses;and
4. Discharge from said treatment works at the location specified on the attached map into the Catawba River
classified as WS-IV B (outfalls 002,002A,002B,004,006,008, 103, 108,and 108B),the unnamed tributary
to Catawba River classified as WS-IV B (Outfall 104),and the South Fork Catawba River classified as WS-V
(outfalls 001 and 003),in the'Catawba River Basin.
Page 3 of 26

Permit NC0004979
Part I
A. (1.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 001)
[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 001-Condenser Cooling Water(CCW). Such discharges shall be limited
and monitored2 by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Type Sample Location
Average Max. Frequency
Flow,MGD Daily Pump Logs Effluent
Temperature 38.9°C DailyGrab or Effluent
(June 1 —September 30)1 (102°F) Instantaneous
Temperature 35°C DailyGrab or Effluent
(October 1 —May 31)1 (95°F) Instantaneous
Notes:
1. Based upon studies conducted by the permittee and submitted to the Division,it has been determined pursuant
to Section 316(a) of the Clean Water Act that the thermal component of the discharge assures the protection
and propagation of a balanced,indigenous population of shellfish, fish and wildlife in the receiving water body.
2. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
Chlorination of the once through condenser cooling water,discharged through outfall 001,is not allowed
under this permit. Should Duke Energy Carolinas,LLC wish to chlorinate its condenser cooling water,a
permit modification must be obtained beforehand.
Page 4 of 26

Permit NC0004979
A. (2.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 002-normal
operation/decanting)
[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 effluent(decanting the free water above the settled ash
layer that does not involve mechanical disturbance of the ash). Such discharges shall be limited and
monitored4 by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS Monthly Daily Measurement Sample Type Sample
Average Maximum Frequency Location
Instantaneous Influent or
Flow,MGD Weekly
or Estimate Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Monthly Grab Effluent
Total Suspended Solids8 30.0 mg/L 50.0 mg/L Monthly Grab Effluent
Total Copper 1 1.0 mg/L 1.0 mg/L Monthly Grab Effluent
Total Iron 1 1.0 mg/L 1.0 mg/L Monthly Grab Effluent
BOD,5-day,20°C6 30.0 mg/L 45.0 mg/L Monthly Grab Effluent
Fecal Coliform(geo.mean)6 200/100 mL 400/100 mL Monthly Grab Effluent
Total Selenium,µg/L Weekly Grab Effluent
Total Arsenic,µg/L Weekly Grab Effluent
Total Silver 0.255 µg/L 1.081 µg/L Weekly Grab Effluent
Total Nickel,µg/L Monthly Grab Effluent
Total Lead,µg/L Monthly Grab Effluent
Total Mercury 2,ng/L Weekly Grab Effluent
Total Nitrogen Quarterly Grab Effluent
(NO2+NO3 +TKN),mg/L
Total Phosphorus,mg/L Quarterly Grab Effluent
Chronic Toxicity 3 Quarterly Grab Effluent
Total Hardness,mg/L Monthly Grab Effluent
Turbidity5,NTU Monthly Grab Effluent
Bromide,mg/L Monthly Grab Effluent
pH7 Between 6.0 and 9.0 standard Monthly Grab Effluent
units
Footnotes:
1. The limits for total copper and total iron only apply when chemical metal cleaning wastewaters are being
discharged.
2. Mercury shall be measured using EPA Method 1631E.
3. Whole Effluent Toxicity shall be monitored by chronic toxicity(Ceriodaphnia)P/F at 23.6%,see Special
Condition A. (17).
4. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
Page 5 of 26

Permit NC0004979
5. 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. Therefore,if the effluent measurement exceeds 50 NTU, the Permittee shall
sample upstream and downstream turbidity in the receiving waterbody,within 24 hours, to demonstrate the
existing turbidity level in the receiving waterbody was not increased.All data shall be reported on the DMRs.
(See 15A NCAC 2B .0211 (21)). NTU -Nephelometric Turbidity Unit.
6. The limit and monitoring apply only when the domestic wastewater is being discharged to the basin.
7. The facility shall continuously monitor pH when the decanting process commences (and the pump is operating)
and the decanting pump shall be shutoff automatically when the 15 minutes running average pH falls below 6.1
standard units or rises above 8.9 standard units. Pumping will be allowed to continue if interruption might result
in a dam failure or damage.The continuous pH monitoring is only required when the pumps are employed for
decanting.
8. The facility shall continuously monitor TSS concentration when the decanting process commences (and the
pump is operating) and the decanting pump shall be shutoff automatically when one half of the Daily Maximum
limit(15 minutes average) is exceeded. Pumping will be allowed to continue if interruption might result in a dam
failure or damage.The continuous TSS monitoring is only required when the pumps are employed for
decanting.
There shall be no discharge of floating solids or visible foam in other than trace amounts.
If any one of the pollutants (As, Se,Hg,Ni, and Pb) reaches 85%of the allowable level during the
decanting/dewatering, the facility shall immediately discontinue discharge of the wastewater and report it
to the Regional Office and Complex NPDES Permitting Branch via telephone and e-mail.
The facility is allowed to drawdown the wastewater in the ash pond to no less than three feet above the
ash. The rate for lowering the liquid level in a coal ash pond shall not exceed one (1) foot per day unless a
higher rate is supported to the satisfaction of DEMLR and in accordance with NCAC,Title 15A,
Subchapter 2K.
The facility shall use a floating pump suction pipe with free water skimmed from the basin surface using
an adjustable weir.
Lowering the level below the three feet mark triggers the limits and conditions in Section A. (3.) of the
permit.
By November 1,2018 there shall be no discharge of pollutants in fly ash transport water.This requirement
only applies to fly ash transport water generated after November 1,2018.
In accordance with the N.C.G.S. § 130A-309.210,by December 31,2019,the facility shall convert to the
disposal of dry bottom ash, as defined in the Coal Ash Management Act("CAMA").
The facility shall notify via e-mail DWR Complex NPDES Permitting Unit and DWR Mooresville
Regional Office,in writing, seven calendar days prior to the commencement of the decanting.
When the facility commences the ash pond/ponds decanting, the facility shall treat the wastewater
discharged from the ash pond/ponds using physical-chemical treatment, if necessary, to assure state
Water Quality Standards are not contravened in the receiving stream. Duke Energy shall notify DWR
NPDES Permitting and DWR Mooresville Regional Office,in writing,within seven calendar days of
installing additional physical-chemical treatment at this Outfall.
Page 6 of 26

Permit NC0004979
A. (3.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 002-dewatering)
[15A NCAC 02B.0400 et seq.,02B .0500 et seq.]
During the period beginning on the commencement of dewatering and lasting until expiration,the Permittee is
authorized to discharge from outfall 002—ash pond effluent(dewatering-removing the interstitial water).
Such discharges shall be limited and monitored4 by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS Monthly Daily Measurement Sample Type Sample
Average Maximum Frequency Location
I low,MGD 3.09 Daily Instantaneous Influent or
or Estimate Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Weekly Grab Effluent
Total Suspended Solids6 30.0 mg/L 50.0 mg/L Weekly Grab Effluent
Total Copper' 1.0 mg/L 1.0 mg/L Weekly Grab Effluent
Total Iron' 1.0 mg/L 1.0 mg/L Weekly Grab Effluent
BOD, 5-day,20°C 7 30.0 mg/L 45.0 mg/L Weekly Grab Effluent
Fecal Coliform(geo.mean)7 200/100 mL 400/100 mL Weekly Grab Effluent
Total Selenium,µg/L Weekly Grab Effluent
Total Arsenic,µg/L Weekly Grab Effluent
Total Silver 3.74 ug/l. 15.13 µg/L Weekly Grab Effluent
Total Mercury 2,ng/L Weekly Grab Effluent
Total Nitrogen
(NO2+NO3 +TKN),mg/L. Weekly Grab Effluent
Total Phosphorus,mg/L Weekly Grab Effluent
Chronic Toxicity 3 Monthly Grab Effluent
Total Hardness,mg/L Weekly Grab Effluent
Turbidity5,NTU Weekly Grab Effluent
Bromide,mg/L Weekly Grab Effluent
Total Chromium,µg/L Weekly Grab Effluent
Total Lead,µg/L Weekly Grab Effluent
Total Nickel,pg/L Weekly Grab Effluent
Total Cadmium,µg/L Weekly Grab Effluent
Total Zinc,µg/L Weekly Grab Effluent
TDS,mg/L Weekly Grab Effluent
Between 6.0 and 9.0 standard Grab
pH8 Weekly Effluent
units
Footnotes:
1. The limits for total copper and total iron only apply when chemical metal cleaning wastewaters are being
discharged.
2. Mercury shall be measured using EPA Method 1631E.
3. Whole Effluent Toxicity shall be monitored by chronic toxicity(Ceriodaphnia)P/F at 4.7%,see Special
Condition A. (17.).
Page 7 of 26

Permit NC0004979
4. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR
application system. Please See Special Condition A. (26.).
5. 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. Therefore,if the effluent measurement exceeds 50 NTU,the Permittee shall
sample upstream and downstream turbidity in the receiving waterbody,within 24 hours,to demonstrate the
existing turbidity level in the receiving waterbody was not increased.All data shall be reported on the DMRs.
(See 15A NCAC 2B.0211 (21)).NTU-Nephelometric Turbidity Unit.
6. The facility shall continuously monitor TSS concentration when the dewatering process commences (and the
pump is operating) and the dewatering pump shall be shutoff automatically when one half of the Daily
Maximum limit(15 minutes average)is exceeded.Pumping will be allowed to continue if interruption might
result in a dam failure or damage.The continuous TSS monitoring is only required when the pumps are
employed for dewatering.
7. The limit and monitoring apply only when the domestic wastewater is being discharged to the basin.
8. The facility shall continuously monitor pH when the dewatering process commences (and the pump is
operating) and the dewatering pump shall be shutoff automatically when the 15 minutes running average pH
falls below 6.1 standard units or rises above 8.9 standard units.Pumping will be allowed to continue if
interruption might result in a dam failure or damage.The continuous pH monitoring is only required when the
pumps are employed for dewatering.
9. The limit applies only when pumping is used for dewatering.
There shall be no discharge of floating solids or visible foam in other than trace amounts.
If any one of the pollutants (As,Se,Hg,Ni,and Pb) reaches 85%of the allowable level during the
decanting/dewatering,the facility shall immediately discontinue discharge of the wastewater and report it
to the Regional Office and Complex NPDES Permitting Branch via telephone and e-mail.
The rate for lowering the liquid level in a coal ash pond shall not exceed one(1) foot per day unless a
higher rate is supported to the satisfaction of DEMLR and in accordance with NCAC,Title 15A,
Subchapter 2K.
The facility shall use a floating pump suction pipe with free water skimmed from the basin surface using
an adjustable weir.
By November 1,2018 there shall be no discharge of pollutants in fly ash transport water.This requirement
only applies to fly ash transport water generated after November 1,2018.
In accordance with the N.C.G.S. §130A-309.210,by December 31,2019,the facility shall convert to the
disposal of dry bottom ash,as defined in the Coal Ash Management Act("CAMA").
The facility shall notify DWR Complex NPDES Permitting Unit and DWR Mooresville Regional Office
seven calendar days,in writing,prior to the commencement of the dewatering.
When the facility commences the ash pond/ponds dewatering,the facility shall treat the wastewater
discharged from the ash pond/ponds using physical-chemical treatment,if necessary,to assure state
Water Quality Standards are not contravened in the receiving stream. Duke Energy shall notify DWR
NPDES Permitting and DWR Mooresville Regional Office,in writing,within seven calendar days of
installing additional physical-chemical treatment at this Outfall.
Page 8 of 26

Permit NC0004979
A. (4.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 002A)
[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 002A—Coal Yard Sump Overflows. Such discharges shall be limited and
monitored2 by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample Location1
Average Maximum Frequency Type
Flow,MGD Per discharge event Estimate Effluent
pH Between 6.0 and 9.0 standard Per discharge event Grab Effluent
units
Oil and Grease 15.0 mg/L 20.0 mg/L Per discharge event Grab Effluent
v
Total Suspended Solids 30.0 mg/L 50.0 mg/L Per discharge event Grab Effluent
BOD, 5-day, 20°C4 30.0 mg/L 45.0 mg/L Per discharge event Grab Effluent
Fecal Coliform (geo. 200/100 mL 400/100 mL Per discharge event Grab Effluent
mean)4
Total Copper3 1.0 mg/L 1.0 mg/L Per discharge event Grab Effluent
Total Iron3 1.0 mg/L 1.0 mg/L Per discharge event Grab Effluent
Footnotes:
1. Effluent sampling shall be conducted at a point upstream of discharge to the receiving stream.
2. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
3. The limits for total copper and total iron only apply when chemical metal cleaning wastewaters are being
discharged.
4. The limit and monitoring apply only when the domestic wastewater is being discharged to the basin.
There shall be no discharge of floating solids or visible foam in other than trace amounts.
All flows shall be reported on monthly DMRs. If no flow occurs during a given month,the words "no
flow"should be clearly written on the front of the DMR. All samples shall be of a representative
discharge.
Page 9 of 26

Permit NC0004979
A. (5.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 002B)
[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 002B—Power House Sump Overflows. Such discharges shall be limited and
monitored3 by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Type Sample
Average Maximum Frequency Location'
Flow,MGD Per discharge Estimate Effluent
event
pH Between 6.0 and 9.0 standard Per discharge Grab Effluent
units event
Oil and Grease 15.0 mg/L 20.0 mg/L Per discharge Grab Effluent
event
Total Suspended Solids 30.0 mg/L 100.0 mg/L Per discharge Grab Effluent
event
Total Copper2 1.0 mg/L 1.0 mg/I. Per discharge Grab Effluent
event
Total Iron2 1.0 mg/L 1.0mg/L Per discharge Grab Effluent
event
Footnotes:
1. Effluent sampling shall be conducted at a point upstream of discharge to the receiving stream.
2. The limits for total copper and total iron only apply when chemical metal cleaning wastewaters are being
discharged.
3. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
There shall be no discharge of floating solids or visible foam in other than trace amounts.
All flows shall be reported on monthly DMRs. If no flow occurs during a given month,the words "no
flow" should be clearly written on the front of the DMR. All samples shall be of a representative
discharge.
Page 10 of 26

Permit NC0004979
A. (6.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 003)
[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 003—miscellaneous equipment non-contact water and sealing water.
Such discharges shall be limited and monitored' by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Type Sample Location
Average Maximum Frequency
Flow,MGD Weekly Estimate Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
Chlorination of the once through cooling water,discharged through outfall 003,is not allowed under this
permit. If Duke Energy Carolinas, LLC wishes to chlorinate this once through cooling water,a permit
modification must be obtained beforehand.
A. (7.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 004)
[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 004-miscellaneous non-contact cooling water,vehicle washwater, and
intake screen backwash. Such discharges shall be limited and monitored' by the Permittee as specified below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Type Sample
Average Maximum , Frequency Location
Flow,MGD Weekly Estimate Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Quarterly Grab Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
Chlorination of the once through cooling water,discharged through outfall 004,is not allowed under this
permit. If Duke Energy Carolinas, LLC wishes to chlorinate this once through cooling water, a permit
modification must be obtained beforehand.
Page 11 of 26

Permit NC0004979
A. (8.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Internal Outfall 005)
[15A NCAC 02B .0400 et seq.,02B .0500 et seq.]
During the period beginning on the effective date of this permit and lasting until permit expiration,the Permittee is
authorized to discharge from internal outfall 005-treated FGD wet scrubber wastewater to ash settling
basin/Line Retention Basin. Such discharges shall be limited and monitored2 by the Permittee as specified
below:
EFFLUENT LIMITS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency Type Location'
Pump logs or
Flow,MGD Monitor&Report Monthly similar Effluent
readings
Total Arsenic,µg/L Quarterly Grab Effluent
Total Mercury3,ng/L Quarterly Grab Effluent
Total Selenium,µg/L Quarterly Grab Effluent
Nitrate/nitrite as N,mg/L Quarterly Grab Effluent
Oil and Grease Quarterly Grab Effluent
Total Suspended Solids 30.0 mg/L 100.0 mg/L Monthly Grab Effluent
pH Monthly Grab Effluent
Footnotes:
1. "Effluent"shall be defined as the discharge from the FGD wastewater treatment system prior to commingling
with other waste streams.
2. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26).
3. The facility shall use method 1631E.
All flows shall be reported on monthly DMRs. If no flow occurs during a given month,the words "no
flow"shall be clearly written on the front of the DMR. All samples shall be of a representative discharge.
The permittee will operate the FGD wastewater system until all coal-fired generation units at the site are
retired. Performance of the FGD wastewater treatment system shall be optimized to maximize pollutant
reduction and minimize variability. For the purposes of this requirement,optimization may be
demonstrated by quarterly averages at or below 8 ug/L for Total Arsenic,34 ng/L for Total Mercury,and
12 ug/L for Total Selenium
In accordance with 40 CFR 423.19,The permittee shall submit a Notice of Planned Participation to the
Department no later than October 13,2021 and an annual recertification to the permitting authority,within
60 days of submitting annual electricity production data to the Energy Information Administration.
Annually,after submission of the Notice of Planned Participation,a progress report shall be filed with the
Department.
Page 12 of 26

Permit NC0004979
A. (9.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 006)
[15A NCAC 02B .0400 et seq.,02B .0500 et seq.]
During the period beginning upon commencement of operations and lasting until expiration,the Permittee is
authorized to discharge from outfall 006—Retention Basin discharge. Such discharges shall be limited and
monitored1 by the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency Type Location
Flow,MGD Weekly Instantaneous Effluent
or Estimate
pH Between 6.0 and 9.0 standard Monthly Grab Effluent
units
TSS 30.0 mg/L 100.0 mg/L Monthly Grab Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Monthly Grab Effluent
BOD,5-day,20°Cs 30.0 mg/L 45.0 mg/L Monthly Grab Effluent
Fecal Coliform(geo.mean)5 200/100 mL 400/100 mL Monthly Grab Effluent
Fluoride,mg/L Monthly Grab Effluent
Total Mercury2,ng/L Monthly Grab Effluent
Total Silver 1.17 µg/L 4.79 µg/L Monthly Grab Effluent
Total Irons 1.0 mg/L 1.0 mg/L Monthly Grab Effluent
Total Zinc,µg/L Monthly Grab Effluent
Total Arsenic 2,776 µg/L 5,201 µg/L Monthly Grab Effluent
Total Cadmium,µg/L Monthly Grab Effluent
Total Chromium,µg/L Monthly Grab Effluent
Total Coppers 1.0 mg/L 1.0 mg/L Monthly Grab Effluent
Total Lead,µg/L Monthly Grab Effluent
Total Nickel,µg/L Monthly Grab Effluent
Total Selenium,µg/L Monthly Grab Effluent
Total Nitrogen Quarterly Grab Effluent
(NO2 +NO3 +TKN),mg/L
Total Phosphorus,mg/L Quarterly Grab Effluent
Sulfates,mg/L Monthly Grab Effluent
Chlorides,mg/L Monthly Grab Effluent
Bromide,mg/L Monthly Grab Effluent
TDS,mg/L Monthly Grab Effluent
Total Hardness,mg/L Monthly Grab Effluent
Temperature,°C Monthly Grab Effluent
Conductivity,µmho/cm Monthly Grab Effluent
Chronic Toxicity4 Monthly Grab Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
2. The facility shall use EPA method 1631E.
3. The limits for total copper and total iron only apply when chemical metal cleaning wastewaters are being
discharged.
4. Whole Effluent Toxicity shall be monitored by chronic toxicity(Ceriodaphnia)P/F at 5.4%,see Special
Condition A. (17.).
5. The limit and monitoring apply only when the domestic wastewater is being discharged to the basin.
Page 13 of 26

Permit NC0004979
Except for those discharges authorized below,or when the bottom ash transport water is used in the FGD
scrubber,there shall be no discharge of pollutants in bottom ash transport water.Bottom ash transport
water shall be discharged to the FGD scrubber during normal operations.
If the FGD Scrubber is unavailable to receive bottom ash transport water,the discharge of pollutants in
bottom ash transport water(bottom ash purge water) from a properly installed,operated,and maintained
bottom ash system to the Lined Retention Basin is authorized under the following conditions:
A. To maintain system water balance when precipitation-related inflows are generated from a 10-year
storm event of 24-hour or longer duration (e.g.,30-day storm event) and cannot be managed by
installed spares,redundancies,maintenance tanks,and other secondary bottom ash system equipment;
or
B. To maintain system water balance when regular inflows from waste streams other than bottom ash
transport water exceed the ability of the bottom ash system to accept recycled water and segregating
these other waste streams is feasible;or
C. To maintain system water chemistry where current operations at the facility are unable to currently
manage pH,corrosive substances, substances or conditions causing scaling,or fine particulates to
below levels which impact system operation or maintenance;or
D. To conduct maintenance not otherwise described above and not exempted from the definition of
transport water in 40 C.F.R. §423.11(p),and when water volumes cannot be managed by installed
spares,redundancies,maintenance tanks,and other secondary bottom ash system equipment.
In no event shall the total volume of the discharge to the Lined Retention Basin exceed a 30-day rolling
average of ten percent of the primary active wetted bottom ash system volume.The volume of daily
discharges used to calculate the 30-day rolling average shall be calculated using measurements from flow
monitors or pump logs. Based on a calculated bottom ash transport system volume of 640,800 gallons,the
30 day rolling average discharge shall not exceed 0.064 MGD.
There shall be no discharge of floating solids or visible foam in other than trace amounts.
A. (10.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 007)
[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 007—Emergency spillway of the new Retention Basin.Such discharges shall
be limited and monitored.' by the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency Type Location
Flow,MGD Waived Estimate Effluent
pH Waived Grab Effluent
TSS Waived Grab Effluent
Oil and Grease Waived Grab Effluent
The emergency spillway is designed for a flood greater than 100-year event in Gaston County. Sampling of
this spillway is waived due to unsafe conditions associated with sampling during an overflow event.
Monitoring is required for any other rain event that might trigger a discharge.
Page 14 of 26

Permit NC0004979
A. (11.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 008)
[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 008—Emergency spillway of the retired ash basin. Such discharges shall be
limited and monitored' by the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency Type Location
Flow,MGD Waived Estimate Effluent
pH Waived Grab Effluent
TSS Waived Grab Effluent
Oil and Grease Waived Grab Effluent
The emergency spillway is designed for a flood greater than 100-year event in Gaston County. Sampling of
this spillway is waived due to unsafe conditions associated with sampling during an overflow event.
Monitoring is required for any other rain event that might trigger a discharge.
Page 15 of 26

Permit NC0004979
A. (12.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 103)
[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 103—Toe Drain Discharge.Such discharges shall be limited and monitored.' by
the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency2 Type Location
Flow,MGD Monthly/Quarterly Estimate Effluent
pH3 Monthly/Quarterly Grab Effluent
TSS 30.0 mg/L 100.0 mg/L Monthly/Quarterly Grab Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Monthly/Quarterly Grab Effluent
Fluoride,mg/L Monthly/Quarterly Grab Effluent
Total Mercury4,ng/L Monthly/Quarterly Grab Effluent
Total Barium,mg/L Monthly/Quarterly Grab Effluent
Total Iron,mg/L Monthly/Quarterly Grab Effluent
Total Manganese,pg/L Monthly/Quarterly Grab Effluent
Total Zinc,pg/L Monthly/Quarterly Grab Effluent
Total Arsenic,µg/L Monthly/Quarterly Grab Effluent
Total Cadmium,µg/L Monthly/Quarterly Grab Effluent
Total Chromium,µg/L Monthly/Quarterly Grab Effluent
Total Copper,µg/L Monthly/Quarterly Grab Effluent
Total Lead,µg/L Monthly/Quarterly Grab Effluent
Total Nickel,µg/L Monthly/Quarterly Grab Effluent
Total Selenium,pg/L Monthly/Quarterly Grab Effluent
Nitrate as N,mg/L Monthly/Quarterly Grab Effluent
Sulfates,mg/L Monthly/Quarterly Grab Effluent
Chlorides,mg/L Monthly/Quarterly Grab Effluent
TDS,mg/L Monthly/Quarterly Grab Effluent
Total Hardness,mg/L Monthly/Quarterly Grab Effluent
Temperature,°C Monthly/Quarterly Grab Effluent
Conductivity,µmho/cm Monthly/Quarterly Grab Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
2. The facility shall conduct monthly sampling from the effective date of the permit.After one year from the
effective date of the permit the monitoring will be reduced to quarterly
3. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
4. The facility shall use EPA method 1631E.
If no discharge occurs during the reporting period or the Permittee is unable to obtain a representative
sample due to low-flow conditions at the toe drain,the Permittee shall submit its DMR,as required,and
indicate"No Flow"for the toe drain(15A NCAC 02B .0506(a)(1)(E)).
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 16 of 26

Permit NC0004979
A. (13.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfa11104)
[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 104—Toe Drain Discharge. Such discharges shall be limited and monitored' by
the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency2 Type Location
Flow,MGD Monthly/Quarterly Estimate Effluent
pH3 Monthly/Quarterly Grab Effluent
TSS 30.0 mg/L 100.0 mg/L Monthly/Quarterly Grab Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Monthly/Quarterly Grab Effluent
Fluoride,mg/L Monthly/Quarterly Grab Effluent
Total Mercury4,ng/L Monthly/Quarterly Grab Effluent
Total Barium,mg/L Monthly/Quarterly Grab Effluent
Total Iron,mg/L Monthly/Quarterly Grab Effluent
Total Manganese,µg/L Monthly/Quarterly Grab Effluent
Total Zinc,µg/L Monthly/Quarterly Grab Effluent
Total Arsenic,µg/L Monthly/Quarterly Grab Effluent
Total Cadmium,µg/L Monthly/Quarterly Grab Effluent
Total Chromium,µg/L Monthly/Quarterly Grab Effluent
Total Copper,µg/L Monthly/Quarterly Grab Effluent
Total Lead,µg/L Monthly/Quarterly Grab Effluent
Total Nickel,µg/L Monthly/Quarterly Grab Effluent
Total Selenium,µg/L Monthly/Quarterly Grab Effluent
Nitrate as N,mg/L Monthly/Quarterly Grab Effluent
Sulfates,mg/L Monthly/Quarterly Grab Effluent
Chlorides,mg/L Monthly/Quarterly Grab Effluent
1'DS,mg/L Monthly/Quarterly Grab Effluent
Total Hardness,mg/L Monthly/Quarterly Grab Effluent
Temperature,°C Monthly/Quarterly Grab Effluent
Conductivity,µmho/cm Monthly/Quarterly Grab Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
2. The facility shall conduct monthly sampling from the effective date of the permit.After one year from the
effective date of the permit the monitoring will be reduced to quarterly
3. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
4. The facility shall use EPA method 1631E.
If no discharge occurs during the reporting period or the Permittee is unable to obtain a representative
sample due to low-flow conditions at the toe drain, the Permittee shall submit its DMR, as required, and
indicate "No Flow" for the toe drain (15A NCAC 02B .0506(a)(1)(E)).
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 17 of 26

Permit NC0004979
A. (14.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 108)
[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 108—Toe Drain Discharge. Such discharges shall be limited and monitored.' by
the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum _ Frequency2 Type Location
Flow,MGD Monthly/Quarterly Estimate Effluent
pH3 Monthly/Quarterly Grab Effluent _
TSS 30.0 mg/L 100.0 mg/L Monthly/Quarterly Grab Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Monthly/Quarterly Grab Effluent
Fluoride,mg/L Monthly/Quarterly Grab Effluent
Total Mercury4,ng/L Monthly/Quarterly Grab Effluent
Total Barium,mg/L Monthly/Quarterly Grab Effluent
Total Iron,mg/L Monthly/Quarterly Grab Effluent
Total Manganese,µg/L Monthly/Quarterly Grab Effluent
Total Zinc,µg/L Monthly/Quarterly Grab Effluent
Total Arsenic,µg/L Monthly/Quarterly Grab Effluent
Total Cadmium,µg/L Monthly/Quarterly Grab Effluent
Total Chromium,µg/L Monthly/Quarterly Grab Effluent
Total Copper,µg/L Monthly/Quarterly Grab Effluent
Total Lead,µg/L Monthly/Quarterly Grab Effluent
Total Nickel,µg/L Monthly/Quarterly Grab Effluent
Total Selenium,µg/L Monthly/Quarterly Grab Effluent
Nitrate as N,mg/L Monthly/Quarterly Grab Effluent
Sulfates,mg/L Monthly/Quarterly Grab Effluent
Chlorides,mg/L Monthly/Quarterly Grab Effluent
TDS,mg/L Monthly/Quarterly Grab Effluent
Total Hardness,mg/L Monthly/Quarterly Grab Effluent
Temperature,°C Monthly/Quarterly Grab Effluent
Conductivity,µmho/cm Monthly/Quarterly Grab Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
2. The facility shall conduct monthly sampling from the effective date of the permit.After one year from the
effective date of the permit the monitoring will be reduced to quarterly
3. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
4. The facility shall use EPA method 1631E.
If no discharge occurs during the reporting period or the Permittee is unable to obtain a representative
sample due to low-flow conditions at the toe drain,the Permittee shall submit its DMR,as required,and
indicate"No Flow"for the toe drain(15A NCAC 02B .0506(a)(1)(E)).
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 18 of 26

Permit NC0004979
A. (15.) EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS (Outfall 108B)
[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 108B—Toe Drain Discharge. Such discharges shall be limited and monitored'
by the Permittee as specified below:
EFFLUENT DISCHARGE LIMITATIONS MONITORING REQUIREMENTS
CHARACTERISTICS
Monthly Daily Measurement Sample Sample
Average Maximum Frequency2 Type Location
Flow,MGD Monthly/Quarterly Estimate Effluent
pH3 Monthly/Quarterly Grab Effluent
TSS 30.0 mg/L 100.0 mg/L Monthly/Quarterly Grab Effluent
Oil and Grease 15.0 mg/L 20.0 mg/L Monthly/Quarterly Grab Effluent
Fluoride,mg/L Monthly/Quarterly Grab Effluent
Total Mercury4,ng/L Monthly/Quarterly Grab Effluent
Total Barium,mg/L Monthly/Quarterly Grab Effluent
Total Iron,mg/L Monthly/Quarterly Grab Effluent
Total Manganese,µg/L Monthly/Quarterly Grab Effluent
Total Zinc,µg/L Monthly/Quarterly Grab Effluent
Total Arsenic,µg/L Monthly/Quarterly Grab Effluent
Total Cadmium,µg/L Monthly/Quarterly Grab Effluent
Total Chromium,µg/L Monthly/Quarterly Grab Effluent
Total Copper,µg/L Monthly/Quarterly Grab Effluent
Total Lead,µg/L Monthly/Quarterly Grab Effluent
Total Nickel,µg/L Monthly/Quarterly Grab Effluent
Total Selenium,µg/L Monthly/Quarterly Grab Effluent
Nitrate as N,mg/L Monthly/Quarterly Grab Effluent
Sulfates,mg/L Monthly/Quarterly Grab Effluent
Chlorides,mg/L Monthly/Quarterly Grab Effluent
IDS,mg/L Monthly/Quarterly Grab Effluent
Total Hardness,mg/L Monthly/Quarterly Grab Effluent
Temperature,°C Monthly/Quarterly Grab Effluent
Conductivity,µmho/cm Monthly/Quarterly Grab Effluent
Footnotes:
1. The permittee shall submit Discharge Monitoring Reports electronically using NC DWR's eDMR application
system. Please See Special Condition A. (26.).
2. The facility shall conduct monthly sampling from the effective date of the permit.After one year from the
effective date of the permit the monitoring will be reduced to quarterly
3. The pH shall not be less than 6.0 standard units nor greater than 9.0 standard units.
4. The facility shall use EPA method 1631E.
If no discharge occurs during the reporting period or the Permittee is unable to obtain a representative
sample due to low-flow conditions at the toe drain, the Permittee shall submit its DMR, as required, and
indicate "No Flow" for the toe drain (15A NCAC 02B .0506(a)(1)(E)).
There shall be no discharge of floating solids or visible foam in other than trace amounts.
Page 19 of 26

Permit NC0004979
A. (16.) SPECIAL CONDITION FOR THE DISCHARGE OF ASIATIC CLAM/DEBRIS FILTER
BACKWASH
[NCGS 143-215.3(a) (2) and NCGS 143-215.66]
The permittee may backwash the intake filter for Unit 5 condenser cooling water on an as-needed basis. It is
understood that this wash water will contain materials indigenous to the Catawba River such as Asiatic clams and
light debris. As these are naturally occurring in the river environment,they may be discharged with no adverse
affects to the receiving stream. The Permittee may not add any detergent,chemicals or other non-indigenous
material to the wash water without explicit permission from the Division of Water Resources.
A. (17.) CHRONIC TOXICITY PASS/FAIL PERMIT LIMIT (QUARTERLY/MONTHLY) (Outfall 002
and Outfall 006)
[15A NCAC 02B.0200 et seq.]
The effluent discharge shall at no time exhibit observable inhibition of reproduction or significant mortality to
Ceriodapbnia dubia at an effluent concentration of 23.6% for decanting/normal operations (Outfall 002),5.4%
for retention basin discharge(Outfall 006),and 4.7% for dewatering(Outfall 002).
The permit holder shall perform at a minimum,quarterly(for normal operation/decanting at Outfall 002 and Outfall
006),and monthly(for dewatering at Outfall 002)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
1621 Mail Service Center
Raleigh,North Carolina 27699-1621
Or,results can be sent to the email,ATForms.ATBna,ncdenr.gov.
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
Page 20 of 26

Permit NC0004979
Flow"in the comment area of the form. The report shall be submitted to the Water Sciences Section at the address
cited above.
Should the permittee fail to monitor during a month in which toxicity monitoring is required,monitoring will be
required during the following month.Assessment of toxicity compliance is based on the toxicity testing quarter,
which is the three month time interval that begins on the first day of the month in which toxicity testing is required
by this permit and continues until the final day of the third month.
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. (18.) BIOCIDE CONDITION
[NCGS 143-215.1]
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 receiving stream. Completion of Biocide Worksheet Form 101 is not necessary for those
outfalls containing toxicity testing.Division approval is not necessary for the introduction of new biocides into outfalls
currently tested for whole effluent toxicity.
A. (19.)ADDITIONAL CONDITIONS AND DEFINITIONS
[NCGS 143-215.3 (a) (2) and NCGS 143-215.66]
1. The facility shall provide an Annual Report(in pdf format) on the Closure Activities to demonstrate the
progress towards closing the power generating units by the end of 2028.
2. EPA methods 200.7 or 200.8 (or the most current versions) shall be used for analyses of all metals except
for total mercury(EPA Method 1631E).
3. All effluent samples for all external outfalls shall be taken at the most accessible location after the final
treatment but prior to discharge to waters of the U.S. (40 CFR 122.41(j)).
4. The term low volume waste sources means wastewater from all sources except those for which specific
limitations are otherwise established in this part(40 CFR 423.11 (b)).
5. The term chemical metal cleaning waste means any wastewater resulting from cleaning any metal process
equipment with chemical compounds,including,but not limited to,boiler tube cleaning(40 CFR 423.11
(c)).
6. The term metal cleaning waste means any wastewater resulting from cleaning[with or without chemical
cleaning compounds] any metal process equipment including,but not limited to,boiler tube cleaning,boiler
fireside cleaning,and air preheater cleaning(40 CFR 423.11 (d)).
7. For all outfalls where the flow measurement is to be"estimated"the estimate can be done by using
calibrated V-notch weir,stop-watch and graduated cylinder,or other method approved by the Division.
8. The term "FGD wet scrubber wastewater" means wastewater resulting from the use of the flue-gas
desulfurization wet scrubber.
9. There shall be no discharge of polychlorinated biphenyl compounds.
10. The permittee shall report the presence of cenospheres observed in any samples on the DMRs.
11. The applicant is permitted to discharge chemical metal cleaning wastes to the ash basin.
Page 21 of 26

Permit NC0004979
12. Nothing contained in this permit shall be construed as a waiver by the permittee of any right to a hearing it
may have pursuant to State or Federal laws and regulations.
A. (20.) STRUCTURAL INTEGRITY INSPECTIONS OF ASH DAMS
[15A NCAC 02K.0208]
The facility shall meet the dam design and dam safety requirements per 15A NCAC 2K.
A. (21.) CLEAN WATER ACT SECTION 316 (a)THERMAL VARIANCE
[40 CFR 125,Subpart H]
The thermal variance granted under Section 316(a) terminates on expiration of this NPDES permit. Should the
permittee wish a continuation of its 316(a) thermal variance beyond the term of this permit,reapplication for such
continuation shall be submitted in accordance with 40 CFR Part 125,Subpart H and Section 122.21(m)(6) not later
than 3.5 years from the effective date of the permit.Reapplication shall include a basis for continuation such as a)
plant operating conditions and load factors are unchanged and are expected to remain so for the term of the
reissued permit;b) there are no changes to plant discharges or other discharges in the plant site area which could
interact with the thermal discharges;and c) there are no changes to the biotic community of the receiving water
body which would impact the previous variance determination.
The next 316(a) studies shall be performed in accordance with the Division of Water Resources approved plan. The
temperature analysis and the balanced and indigenous study plan shall conform to the specifications outlined in 40
CFR 125 Subpart H,the EPA's Draft 316(a) Guidance Manual,dated 1977,and the Region 4 letter to NCDENR,
dated June 3,2010. EPA shall be provided an opportunity to review the plan prior to the commencement of the
study.
The facility shall select a new cold water reference area approved by the Division of Water Resources
during the next 316(a) study.
Copies of all the study plans,study results,and any other applicable materials should be submitted to:
1) Electronic Version Only(pdf)
Division of Water Resources
WQ Permitting Section-NPDES
1617 Mail Service Center
Raleigh,NC 27699-1617
2) Electronic Version (pdf) and Hard Copy
Division of Water Resources
Water Sciences Section
1623 Mail Service Center
Raleigh,NC 27699-1623
A. (22.) CLEAN WATER ACT SECTION 316 (b)
[40 CFR 125.95]
The permittee shall comply with the Cooling Water Intake Structure Rule per 40 CFR 125.95.The permittee shall
submit all the materials required by the Rule 3.5 years from the effective date of the permit.
Copies of all the study plans,study results,and any other applicable materials should be submitted to:
1) Electronic Version Only(pdf)
Division of Water Resources
WQ Permitting Section-NPDES
Page 22 of 26

Permit NC0004979
1617 Mail Service Center
Raleigh,NC 27699-1617
2) Electronic Version(pdf) and Hard Copy
Division of Water Resources
Water Sciences Section
1623 Mail Service Center
Raleigh,NC 27699-1623
Pursuit to 40 CFR 125.98 the Director has determined that operating and maintaining the existing traveling screen
system which includes a fish handling return system meets the requirements for the interim BTA.
Nothing in this permit authorizes take for the purposes of a facility's compliance with the Endangered Species Act.
A. (23.) FISH TISSUE MONITORING NEAR ASH POND DISCHARGE
[NCGS 143-215.3(a) (2)]
The facility shall conduct fish tissue monitoring annually and submit the results with the NPDES permit renewal
application.The objective of this monitoring is to evaluate potential uptake of pollutants by fish tissue near the ash
pond discharge. The parameters analyzed in fish tissue shall be arsenic,selenium,and mercury.The monitoring shall
be conducted in accordance with the sampling plan approved by the Division. The plan should be submitted to the
Division within 180 days from the effective date of the permit.Upon approval,the plan becomes an enforceable part
of the permit.
Copies of all the study plans,study results,and any other applicable materials should be submitted to:
1) Electronic Version Only(pdf)
Division of Water Resources
WQ Permitting Section-NPDES
1617 Mail Service Center
Raleigh,NC 27699-1617
2) Electronic Version (pdf) and Hard Copy
Division of Water Resources
Water Sciences Section
1623 Mail Service Center
Raleigh,NC 27699-1623
A. (24.) INSTREAM MONITORING
[
15A NCAC 02B.0500 ET SEQ.]
The facility shall conduct monthly in-stream monitoring for total arsenic, total selenium, total mercury, total
chromium, dissolved lead, dissolved cadmium, dissolved copper, dissolved zinc, total bromide, total hardness (as
CaCO3), turbidity, temperature, and total dissolved solids (IDS). The monitoring results shall be reported on the
facility's Discharge Monitoring Reports and included with the NPDES permit renewal application.The upstream site
is approximately 250 meters upstream of Outfall 006 and the downstream location is approximately 250 meters
downstream of Outfall 006.
A. (25.)PRIORITY POLLUTANT ANALYSIS
[NCGS 143-215.1 (b)]
The permittee shall conduct a priority pollutant analysis (in accordance with 40 CFR Part 136) once per permit cycle
at all external outfalls and submit the results with the application for permit renewal.
Page 23 of 26

Permit NC0004979
A. (26.) ELECTRONIC REPORTING OF DISCHARGE MONITORING REPORTS
[G.S. 143-215.1(b)]
Federal regulations require electronic submittal of all discharge monitoring reports (DMRs) and program reports.
The final NPDES Electronic Reporting Rule was adopted and became effective on December 21,2015.
NOTE: This special condition supplements or supersedes the following sections within Part II of this permit
(Standard Conditions forNPDES Permits):
• Section B. (11.) Signatory Requirements
• Section D. (2.) Reporting
• Section D. (6.) Records Retention
• Section E. (5.) Monitoring Reports
1. Reporting Requirements [Supersedes Section D. (2.) and Section E. (5.) (a)1
The permittee shall report discharge monitoring data electronically using the NC DWR's Electronic Discharge
Monitoring Report(eDMR)internet application.
Monitoring results obtained during the previous month(s) shall be summarized for each month and submitted
electronicallyusingeDMR. The eDMR system allowspermitted facilities to enter monitoringdata and submit
Y
DMRs electronically using the internet. The eDMR system may be accessed at:
https://deq.nc.gov/about/divisions/water-resources/edmr.
If a permittee is unable to use the eDMR system due to a demonstrated hardship or due to the facility being
physically located in an area where less than 10 percent of the households have broadband access,then a
temporary waiver from the NPDES electronic reporting requirements may be granted and discharge monitoring
data may be submitted on paper DMR forms (MR 1, 1.1,2,3) or alternative forms approved by the Director.
Duplicate signed copies shall be submitted to the following address:
NC DEQ/Division of Water Resources /Water Quality Permitting Section
A 1"1"hNTION: Central Files
1617 Mail Service Center
Raleigh,North Carolina 27699-1617
See"How to Request a Waiver from Electronic Reporting"section below.
Regardless of the submission method,the first DMR is due on the last day of the month following the issuance
of the permit or in the case of a new facility,on the last day of the month following the commencement of
discharge.
Starting on December 21,2025,the permittee must electronically report the following compliance monitoring
data and reports,when applicable:
• Sewer Overflow/Bypass Event Reports;
• Pretreatment Program Annual Reports;and
• Clean Water Act(CWA) Section 316(b)Annual Reports.
The permittee may seek an electronic reporting waiver from the Division (see"How to Request a Waiver from
Electronic Reporting"section below).
Page 24 of 26

Permit NC0004979
2. Electronic Submissions
In accordance with 40 CFR 122.41(1)(9),the permittee must identify the initial recipient at the time of each
electronic submission. The permittee should use the EPA's website resources to identify the initial recipient for
the electronic submission.
Initial recipient of electronic NPDES information from NPDES-regulated facilities means the entity(EPA or
the state authorized by EPA to implement the NPDES program) that is the designated entity for receiving
electronic NPDES data [see 40 CFR 127.2(b)].
EPA plans to establish a website that will also link to the appropriate electronic reporting tool for each type of
electronic submission and for each state. Instructions on how to access and use the appropriate electronic
reporting tool will be available as well. Information on EPA's NPDES Electronic Reporting Rule is found at:
https://www.federalregister.gov/documents/2015/10/22/2015-24954/national-pollutant-discharge-
elimination-system-npdes-electronic-reporting-rule
Electronic submissions must start by the dates listed in the"Reporting Requirements"section above.
3. How to Request a Waiver from Electronic Reporting
q P g
The permittee may seek a temporary electronic reporting waiver from the Division. To obtain an electronic
reporting waiver,a permittee must first submit an electronic reporting waiver request to the Division. Requests
for temporary electronic reporting waivers must be submitted in writing to the Division for written approval at
least sixty(60) days prior to the date the facility would be required under this permit to begin submitting
monitoring data and reports. The duration of a temporary waiver shall not exceed 5 years and shall thereupon
expire. At such time,monitoring data and reports shall be submitted electronically to the Division unless the
permittee re-applies for and is granted a new temporary electronic reporting waiver by the Division. Approved
electronic reporting waivers are not transferrable. Only permittees with an approved reporting waiver request
may submit monitoring data and reports on paper to the Division for the period that the approved reporting
waiver request is effective.
Information on eDMR and the application for a temporary electronic reporting waiver are found on the
following web page:
http://deq.nc.gov/about/divisions/water-resources/edmr
4. Signatory Requirements [Supplements Section B. (11.) (b) and Supersedes Section B. (11.) (d)]
All eDMRs submitted to the permit issuing authority shall be signed by a person described in Part II,Section B.
(11.)(a) or by a duly authorized representative of that person as described in Part II,Section B. (11)(b). A
person,and not a position,must be delegated signatory authority for eDMR reporting purposes.
For eDMR submissions,the person signing and submitting the DMR must obtain an eDMR user account and
login credentials to access the eDMR system. For more information on North Carolina's eDMR system,
registering for eDMR and obtaining an eDMR user account,please visit the following web page:
http: ide .nc. ov/about/divisions/water-resources/edmr
9 g
Certification. Any person submitting an electronic DMR using the state's eDMR system shall make the
following certification [40 CFR 122.22]. NO OTHER STATEMENTS OF CERTIFICATION WILL BE
ACCEPTED:
"I certify,under penalo 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
Page 25 of 26

Permit NC0004979
on my inquiry of the person or persons who manage the system, or those persons directly responsible forgathering 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."
5. Records Retention [Supplements Section D. (6.)]
The permittee shall retain records of all Discharge Monitoring Reports,including eDMR submissions. These
records or copies shall be maintained for a period of at least 3 years from the date of the report. This period
may be extended by request of the Director at any time [40 CFR 122.41].
A. (27.) APPLICABLE STATE LAW(State Enforceable Only)
[NCGS 143-215.1(b)]
This facility shall meet the General Statute requirements under NCGS § 130A-309.200 et seq.This permit may be
reopened to include new requirements imposed under these Statutes.
A. (28.) COMPLIANCE BOUNDARY
[15A NCAC 02L.0107]
The compliance boundary for the disposal system shall be specified in accordance with 15A NCAC 02L.0107(a)or
(b) dependent upon the date permitted. An exceedance of groundwater standards at or beyond the compliance
boundary is subject to remediation action according to 15A NCAC 02L.0106(c), (d),or(e) as well as enforcement
actions in accordance with North Carolina General Statute 143-215.6A through 143-215.6C.The compliance
boundary map for this facility is incorporated herein and attached hereto as Attachment A.
Page 26 of 26

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Duke Energy Corporation
Allen Steam Station
StateGrid/Ouad: GI4NE/Belmont Permitted Flow: Not limited Map not to scale
Receiving Streams: Catawba and South Fork Catawba Rivers
Stream Class: WS-IV B&WS-V B 8-Digit HUC 03050102
Drainage Basin: Catawba River Basin Sub-Basin: 03-08-34
Latitude(001): 35°11'23" N Longitude(001): 81°00'45" W
Latitude(002): 35°10'30" N Longitude(002): 81°00'23" W Facility
Latitude(002A): 35°11'34" N Longitude(002A): 81°00'22" W x
Latitude(002B): 35°11'36" N Longitude(002B): 81°00'30" W Location
Latitude(003): 35°11'23" N Longitude(003): 81°00'45" W
Latitude(004): 35°11'35" N Longitude(004): 81°00'22" W ..
Latitude(006): 35°10'50" N Longitude(006): 81°00'49" W NPDES Permit No. NC0004979
Latitude(007): 35°11'55" N Longitude(007): 81°00'36" W North Gaston County
Latitude(008): 35°10'55" N Longitude(008): 81°00'24" W