HomeMy WebLinkAboutAQ_F_1000067_20050110_CEM_GenCorr raMrw
NCDENR
North Carolina Department of Environment and Natural Resources
Michael F. Easley, Governor Division of Air Quality William G. Ross,Jr., Secretary
January 10,2005 B. Keith Overcash, P.E., Director
Mr. Tracy Patterson
Air Quality Manager
Cogentrix Field Support Office
4411 Crossings Boulevard
Prince George, VA 23875
Subject: Monitor Span Requirements in Acid Rain (Part 75) Rule and NSPS Subpart Db-Permit Conditions
Facility ID 33/00146; 73/00056; 10/00067
Dear Mr. Patterson:
This letter is in response to your December 13, 2004 request for concurrence with your interpretation that it is acceptable to
use the NOx span calculations from Acid Rain(Part 75)to satisfy the NOx span requirements in NSPS Subpart Db even
though that a different section in subpart Db(40 CFR 60.48b(e) states for NOx monitor to set span value to 1000ppm.
After reviewing the information contained in your letter as well as the regulations cited in your letter including 40 CFR Part
75, Appendix A 2.1.2.1 and 2.1.2.3, 40 CFR 60.48b(e) and 60.48b(b)(2), the Division of Air Quality concurs with your
interpretation that the span value calculated from Part 75 rule is appropriate to be used to meet the NOx span requirements
for Subpart Db as long as the NOx CEM is installed to meet both rules. In fact,this interpretation is consistent with 40
CFR 60.48b(b)(2). We also agree that the span setting from Part 75 is a more stringent quality assurance provision and
would provide a"tighter tolerance" for daily calibration checks, linearity and relative accuracy tests.
As stated in 40 CFR 60.48b(e), please note that a span value of 1000ppm would be required for NOx CEMs that are not
installed to meet Part 75 regulations.
If you have any questions regarding this letter please contact me at(919)733- 1467.
Sincerely,
Dennis U. Igboko
Environmental Engineer
CC: Michael Aldridge
Wayne Cook—WIRO
Ernie Fuller-RRO
Central Files -Brunswick Co.
Edgecombe Co.
Person Co
IMPAQ—Documents—3300146 (Rocky Mount)
7300056 (Roxboro)
1000067 (Southport)
One
1641 Mail Service Center,Raleigh,North Carolina 27699-1641 NorthCarolina
2728 Capital Blvd.,Raleigh, North Carolina 27604
Phone: 919-733-1728/FAX 91 9-733-1 81 2 1 Internet: www.ncair.org Naturally
An Equal Opportunity/Affirmative Action Employer—50%Recycled/30%Post Consumer Paper
Cogentrix
Cogentrix Field 4411 Crossings Boulevard
Support Office Prince GmiVe,VA 2387.5
304-541-4246
Fax 804-541-7961
December 13, 2004
Mr. Dennis Igboko
Division of Air Quality
North Carolina Department of Environment
and Natural Resources
1641 Mail Service Center
Raleigh, NC 27699-1641
Subject: Permit Conditions —Monitor Spans
Cogentrix Facilities in North Carolina
Dear Mr. Igboko,
This letter is submitted to request your assistance in providing proper clarification and
interpretation of the monitoring requirements for the continuous monitoring systems at
our facilities in North Carolina. In our telephone discussion regarding this condition, the
current specification presents some confusion for compliance inspectors when
interpreting the proper span settings for the nitrogen oxides monitors that are installed to
provide data for both NSPS Subpart Db and 40 CFR 75 emission monitoring.
The requirements of 40 CFR 75 Appendix A 2.1.2.1 and 2.1.2.3 require the facility to set
the calibrated span of the NOx monitor to a value between 1 and 1.25 times the maximum
potential concentration (MPC) as determined from several options. Our review of the
previous 12-months of quality assured data, as required by 40 CFR 75 indicates that the
MPC for this facility is 290 ppm of NOx. Following the requirements of 40 CFR 75, the
calibrated span for the monitors must be set to 400 ppm.
As we discussed, the requiferneats of 40 CFR 75 are rnore stringent than the requirements
from 40 CFR 60.48b(e) of 1000 ppm for the analyzer span. As stated by 40 CFR
60.48b(b)(2), if the owner or operator has installed a nitrogen oxide emission rate
continuous emission monitoring system (CEMS) to meet the requirements of part 75 and
is continuing to meet the ongoing requirements of part 75, that CEMS may be used to
meet the requirements of this section. The allowance does not allow the use of substituted
data to meet the reporting requirements of 60.49b.
Certainly, using the lower span setting and following the more stringent quality assurance
requirements of 40 CFR 75 is exactly what 60.48b(b) is allowing. The part 75 QA
requirements from using a lower span setting will require a tighter tolerance for daily
calibration drifts as well as the quarterly QA tests for linearity and for the annual relative
accuracy testing. Changing the span to the lower setting will allow us to keep the
Mr. Dennis Igboko
Letter December 13, 2004
Page 2
monitoring system operating in accordance with the Part 75 rules and also satisfy the
NSPS monitoring requirements.
We are requesting that you provide a written confirmation of this interpretation of the
NSPS monitoring requirement. Your concurrence will remove any uncertainty from the
demonstration of compliance with both sets of regulations and simplify the review of
compliance determination for NCDENR inspection personnel.
Thank you for your time during our telephone discussion on this matter and for
processing this request. As I mentioned, we will need to make the change to the span
value in our system prior to the annual Relative Accuracy Tests currently scheduled for
February of 2005. Please call me at (804) 541-4246 if you have any questions or require
additional information.
S in�erely,
Aoz r"',—"
Tracv L. Patterson
Air Quality Manager
cc:
Gary Willer, Gary Hickey—CNC
Mark Casper—Cogentrix
File EHS 2.1.2