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ROY COOPER NORTH CAROLINA
Governor Environmental Quality
MICHAEL S.REGAN
Secretary
MICHAEL ABRACZINSKAS January 27, 2020
Director
Ms. Cynthia Winston, P.E.
Manager, Carolinas Permitting and Compliance
Duke Energy,NCRH 15
410 S. Wilmington Street
Raleigh,NC 27601-1849
Subject: Approval of Sulfur Dioxide Continuous Emissions Monitoring Systems
Use of Diluent Cap During Periods of Start-up and Shutdown on
Ash Beneficiation—STAR®Process
Reference: Buck Combined Cycle Facility, Permit No. 03786T,Facility No. 8000004
H.F. Lee Steam Electric Plant, Permit No. 01812T,Facility No. 9600017
Cape Fear STAR Facility, Permit No. 10583R, Facility No. 1900134
Dear Ms. Winston:
Your letter of June 6, 2019, to Gary Saunders, requested approval for the usage of a
sulfur dioxide(S02) continuous emissions monitoring systems(CEMS) diluent cap during
periods of startup and shutdown on the fly ash beneficiation staged turbulent air reactor
(STAR®)process. The S02 CEMS will be used to determine compliance with the 2.3
lb/mmBtu emission standard in 15A NCAC 2D .0516—Sulfur Dioxide Emissions from
Combustion Sources. The CEMS measures S02 concentration(ppm)that is used in
conjunction with an Fc-factor(scf CO2/mmBtu) and diluent concentration(%)to convert
measurements to units of the standard(lb/mmBtu). Diluent concentration is used in the
denominator of the conversion equation and approaches zero during periods of startup and
shutdown thereby causing nonrepresentative pollutant emission results.
Based on our review, and in conjunction with our authority under 15A NCAC
2D .0606(g), the Division of Air Quality approves your request to revise the above-referenced
permits to include a diluent cap; however,we ask that you include the following footnote
within the permit as indicated by an asterisk to read,
"*The S02 monitored value subject to the 0.03 lb/mmBtu limit will have a 5% CO2
diluent cap, or a 14%02 diluent cap, substituted in the emission rate calculation
whenever the actual CO2 concentration is lower than 5%or whenever the actual 02
concentration is higher than 14%."
NfJR ,JAJL A
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North Carolina Department of Environmental Quality I Division of Air Quality
217 West Jones Street 11641 Mail Service Center I Raleigh.North Carolina 27699-1641
919.707.8400

Ms. Cynthia Winston
January 27, 2020
Page 2
If you should have any questions,please contact Dennis Igboko at(919) 707-8410 or
[e-mail].
Sincerely,
'Z/ d- Z�-w
Stephen G. Hall, Chief
Technical Services Section
Division of Air Quality,NCDEQ
SGH/ad
c: Randy Wooten,Duke Energy
Erin Wallace,Duke Energy
Dan Markley, Duke Energy
Geoff Russell, Duke Energy
Todd Wilson, SEFA (e-copy)
Gary Saunders, DAQ SSCB
William Willets, DAQ Permits
Central File: Rowan County,Wayne County, Chatham County
IBEAM Documents, 8000004, 9600017, 1900134