NC0003468_Correspondence_20220921

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
NORTH CAROLINA
Environmental Quality
September 23, 2022
Ms. Jessica Bednarcik, Senior Vice President
Environmental, Health and Safety
Duke Energy Carolinas, LLC
Mail Code EC13K
P.O. Box 1006
Charlotte, North Carolina 28201-1006
Subject: Final NPDES Permit
Permit NC0003468
Dan River Combined Cycle
Station
Rockingham County
Facility Class I
Dear Ms. Bednarcik:
The Division of Water Resources is forwarding herewith the Final Permit for Dan River Combined
Cycle Station. This permit renewal is 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 October 15, 2007 (or as subsequently amended).
The Final Permit contains the following significant changes from your Draft Permit:
• The item "e" from the Special Condition A. (6.) was deleted since the DWR biologists already
determined that the proposed temperature mixing zone will have negligible impact on the
aquatic organisms.
The Final Permit maintains the following significant changes contained in the Draft
Permit:
• Once through cooling water and treated domestic wastewater have been removed from the
list of authorized discharges.
• The monitoring requirements for Mercury have been removed from the permit based on the
results of the Reasonable Potential Analysis.
• The monitoring requirements for Iron have been removed from the permit based on the
elimination of the state standards for Iron.
• The footnote associated with temperature requirement of once -through cooling system has
been removed from the permit due to the conversion to the closed -cycle cooling system.
• The monitoring and limits for pH have been removed from internal Outfall 001A to be
consistent with the requirements of 40 CFR 423.
1:tE
NORTH CAROLINA
Department of Environmental Duali�
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11611 Mail Service Center I Raleigh, North Carolina 27699-1611
919.707.9000

• The 316(a) variance has been removed from the permit and substituted with the Thermal
Mixing Zone based on the new modeling information and due to the conversion to the closed -
cycle cooling system.
• The downstream sampling site was relocated closer to the discharge from 2 miles to 85 ft.
based on the results of the thermal model.
• The effluent temperature limit has been increased to 37.2°C from 35°C and was changed from
Monthly Average to Daily Maximum based on the results of the thermal model. This change
will make the limit more stringent because it will not allow any excursions above 37.2°C.
• The following permit conditions have been removed due to the elimination of the discharges
associated with operations of the former coal ash ponds:
1. Effluent pages for Outfall 002.
2. Effluent pages for 3 seeps.
3. Chronic toxicity conditions for Outfall 002.
4. Special Condition for Structural Integrity of the Ash Pond Dam.
5. Special Condition for Instream Monitoring.
6. Special Condition for Applicable State Law — Senate Bill 729.
7. Special Condition for Discharge from Seepage.
8. Special Condition for Fish Tissue Monitoring Near Ash Pond Discharge (Outfall 002).
If any parts, measurement frequencies, or sampling requirements contained in this permit 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, 6714 Mail Service Center, Raleigh, North Carolina 27699-6714. Unless such
a demand is made, this permit shall be final and binding.
Please note that this permit is not transferable except after notice to the Division. The Division may
require modification or revocation and reissuance of the permit. This permit does not affect the legal
requirements to obtain other permits which may be required by the Division of Water Resources or
any other Federal, State, or Local governmental regulations.
If you have any questions or need additional information, please contact Sergei Chernikov, telephone
number [phone] or email: [e-mail].
cc: Central Files
NPDES Files
Winston-Salem Regional Office/Water Quality
WSS/Aquatic Toxicology Unit (e-copy)
EPA Region IV (e-copy)
cD_EQ
-4
NORTH CAROLINA
Department of Environmental Deellry
Sincerely,
Richard E. Rogers, Jr., Director
Division of Water Resources
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 11611 Mail Service Center I Raleigh, North Carolina 27699-1611
919.707.9000