NC0038377_Effluent Limitation and Monitoring Requirements_20170725

DUKE
�ENERGY®
July 25, 2017
Mr. Jeffery Poupart, Section Chief
NC Division of Water Resources
1617 Mail Service Center
Raleigh, NC 27699-1617
Subject Mayo Steam Electric Generating Station
Effluent Limitations and Monitoring Requirements
NPDES Permit No NC0038377
Person County
Dear Mr. Poupart.
REGF:NEDINGDE0JD\NR
AUG -1,2017
Nater Quality
Fermin►n9 gect►on
The purpose of this letter is to provide notification to the Division of Water Quality that,
effective September 1, 2017, the Mayo Station will begin sampling and reporting outfall 002 on
the basis of having no flue gas desulfurization (FGD) wastewater in the effluent stream per
permit condition A (3). Duke requests that the eDMR system be updated to accept the
appropriate sampling terms beginning on that date
As discussed with Duke Energy's staff members Richard Baker and Shannon Langley on July 5,
2017, in accordance with the terms of the Special Order by Consent EMC SOC 10-012, Duke
Energy processes FGD blowdown at the subject facility via a vapor compression evaporator
(VCE) system. This system eliminated discharges of FGD wastewater and was finalized for
facility use in February 2015 Prior to the VCE system coming online, the facility was in an
extended outage with the last discharge of FGD wastewater occurring in November 2014 Since
that time, no FGD wastewater has been discharged through outfalls 009 or 002 No future
discharges of FGD wastewater are planned.
Mayo Steam Etech
10660 Boston Ro,
Roxboro, NC 275,
The currently active Mayo NPDES permit, which became effective on November 1, 2009,
contains two alternative conditions for discharges through Outfall 002 to Mayo Reservoir
Condition A (3) applies to discharges through 002 that do not contain FGD wastewater, while
condition A.(4) applies to discharges through 002 that contain FGD wastewater The Mayo
Station has been collecting and subsequently reporting samples per permit condition A (4) of the
permit, however, as described above, there has been no discharge of FGD wastewater since
November 2014 We have recently recognized that, in the absence of FGD wastewater, A (3) is
actually the condition that applies to Mayo's current operations, and we understand that the
Division agrees with this basis

Attached, you will find graphical representations of the selenium, chlorides, and boron discharge
rates for outfall 002. These graphs reflect the significant reduction of mass of these constituents
discharged since the VCE has been in operation.
If there are any questions relating to this request please contact Lori Tollie at 1-336-854-4916 or
at [e-mail]
Sincerely,
Tom Copolo
Mayo Steam Electric Manager

800
700
600
500
400
300
200
100
Chloride (mg/1)
Outfall 002
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8/26/2009 8/26/2010 8/26/2011 8/26/2012 8/26/2013 8/26/2014 8/26/2015 8/26/2016
A)
Boron (Ibs/day)
Outfall 002
800
700
SOC Daily Max
-
600
683.0 Ibs/day
500
400
300
200
100
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700
600
500
400
300
200
100
Chloride (mg/1)
Outfall 002
U
8/26/2009 8/26/2010 8/26/2011 8/26/2012 8/26/2013 8/26/2014 8/26/2015 8/26/2016
A)

0.3
0.25
0.2
0.15
0.1
0.05
Selenium (Ibs/day)
Outfall 002
1/2/2013 1/2/2014 1/2/2015 1/2/2016 1/2/2017
Se (Ibs)