NC0038377_Correspondence_20231129

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
NORTH CAROLINA
Environmental Quality
December 5, 2023
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
Dear Ms. Bednarcik:
Subject: Draft NPDES Permit
Permit NCO038377
Mayo Steam Electric
Generating Plant
Person County
Facility Class I
Enclosed with this letter is a copy of the draft Permit for your facility. Please review the draft very
carefully to ensure thorough understanding of the conditions and requirements it contains.
The draft Permit contains the following significant changes from your current permit:
1. The description of Outfall 002 flows has been updated since all the process wastewater has
been rerouted to the Lined Retention Basin.
2. The Effluent Page for the decanting phase has been removed from the permit since the
facility moved to the dewatering phase in early October.
3. Internal Outfall 009 has been removed from the permit because all the FGD wastewater is
being evaporated by the VCE.
4. The sampling frequency for the instream monitoring has been reduced from Monthly to
Quarterly based on the review of the instream data.
5. The sampling frequency for the fish tissue monitoring has been reduced from annual to
once every five years based on the review of the fish tissue data.
6. The language for 316(b) condition has been updated to reflect the most recent decision to
recognize the existing intake structure as BTA for meeting impingement and entrainment
requirement of the CWA.
7. The Water Quality Based Effluent Limits for Total Cadmium were added to the permit
(Outfall 002A — lined retention basin) based on the results of the RPA.
The Division cannot grant the facility's request to remove 85% requirement to avoid violation of the
CWA anti -backsliding provision.
North Carolina Department of Environmental Quality I Division of Water Resources
NORTH CAROLINA
v 512 North Salisbury Street 11611 Mail Service Center I Raleigh, North Carolina 27699-1611
919.707.9000
Deportment of Emlmnmenbl 0.4l

The Division cannot grant the facility's request to reduce WET frequency until the dewatering phase
is completed to ensure protection of the receiving stream.
Please provide any comments you have regarding the draft permit to this office by January
9, 2024. At this time, the Division is also publishing a notice in the newspapers of general
circulation in Person County, inviting public comment on the draft permit. Following the 30-day
comment period, we will review all pertinent comments received and take appropriate action on the
permit renewal.
The NPDES Standard Conditions (Parts II, III, and M are not included with this draft. They can
be found at the following link if you would like to review them in conjunction with this draft permit.
https: / /bit.ly/2BZ4xxx
If you have any questions about the NPDES permit process, please contact me at the following e-
mail address: sergei.chernikov, ,deq.nc.gov.gov, or telephone number: 919-707-3606.
Sincerely,
Sergei Chernikov, Ph.D.
Environmental Engineer III
Complex NPDES Permitting Unit
cc: NPDES Files
EPA Region IV (e-copy)
Raleigh Regional Office / Surface Water Protection (e-copy)
Raleigh Regional Office / Public Water Supply (e-copy)
Aquatic Toxicology Unit (e-copy)
TACU (e-copy)
D E Q�� North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1611 Mail Service Center I Raleigh, North Carolina 27699-1611
NORrH CAROLINA 919.707.9000
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