NC0038377_NOV-2023-LV-0104_Resp Rvcd_20230313

(' DUKE
ENERGY®
File: Mayol2520-R
NC Dept of Environmental Quality
MAR f _ 2023
Raleigh Regional Office
Ms. Vanessa E. Manuel
North Carolina Division of Environmental Quality
1628 Mail Service Center
Raleigh, NC 27699-1628
Mayo Steam Electric
Duke Energy Progress, LLC
10660 Boston Road
Roxboro_ NC 27574
March 7, 2023
Subject: Mayo Electric Generating Plant
NPDES Permit No.0038377
Notice of Violation & Intent to Access Civil Penalty N
NOV-2023-LV-0104
Ms. Manuel:
The Mayo Steam Station received your letter March 1, 2023, transmitting allo
to Assess Civil Penalty (NOV-2023-LV-0104) for North Carolina General Stat
the facility's NPDES permit. For the November 2022 Discharge Monitoring Ri
reported one daily maximum Thallium exceedance for Outfall 002. The analyti
15, 2022 was 2.67 ug/L. Typical Thallium values at Outfall 002 are >0.2 ug/L.
compliance the following week, with the November 22 sample result being 0.8
383 -1-:�
Of Violation and Intent
(G.S.) 143-215.6A and
rt, Duke Energy
result for November
�utfall 002 returned to
ug/L.
Duke Energy believes the increase in Thallium resulted from fall outage activits, specifically
air pre -heater and boiler washes. These washes have been completed in prior outages without any permit
exceedances; however, this was a first-time evolution since installing the Lined Retention Basin (LRB) as
part of ash basin closure. All future washing activities will be coordinated to munage the quantity of
water discharged into the LRB to ensure compliance.
If you have any questions concerning this response, please contact Ms. Lori To lie at (336)-408-2591 or at
Lori.TolIic( duke-energy.com.
"I certify, under penalty of law, that this document and all attaehmen were prepared under my
direction or supervision in accordance with a system designed to assu a that qualified personnel
properly gather and evaluate the information submitted. Based on in inquiry of the person or
persons who manage the system, or those persons directly responsible for gathering the
information, the information submitted is, to the best of my knowledge and belief, true, accurate,
and complete. I am aware that there are significant penalties for sul Pinitting false information,
including the possibility offines and imprisonment for knowing violati s. "
Sincerely,
�,�V
Jason Talbott
General Manger III — Mayo Steam Station