AQ_F_0400056_20220301_ST_WaiverResp

ROY COOPER
Governor
ELIZABETH S.BISER
Secretary
MICHAEL ABRACZINSKAS NORTH CAROLINA
vr„wtor En� RECE1\1ED
February 14,2022 MAR - 1 2022
Adam Long
VP, Gas Pipeline Operations
Piedmont Natural Gas OEO-FAYETTEVILLF-RE&ONAL OFFICE
410 South Wilmington Street
Raleigh,NC 27601
Subject: Revised Approval of Waiver Request for Emissions Testing of One Natural Gas Engine as
Representative of Four Engines COMP01-COMP04
Piedmont Natural Gas-Wadesboro Compressor Station
Wadesboro, Anson County,North Carolina
Facility ID No. 0400056;Air Permit No. 10097TO2
Dear Mr. Long:
On December 21,2021,the Division of Air Quality(DAQ)issued an approval letter in response to
a performance testing waiver request dated September 22,2021 for the subject facility. After receiving
feedback from your company,DAQ is herein reissuing the waiver approval letter to offer more clarity and
flexibility in the conditions that allow the waiver to apply on ongoing basis. This revised waiver approval
letter is intended to replace the December 21,2021 approval letter in its entirety.
In the original request,your company asked for a waiver from the performance testing
requirements of 40 CFR 60 Subpart JJJJ-Standards of Performance for Stationary Spark Ignition Internal
Combustion Engines, as related to four identical,natural gas-fired, intemal combustion engines(Permit ID
Nos. COMPOI through COMP04)at the Piedmont Natural Gas-Wadesboro Compressor Station(PNG-
Wadesboro). Specifically,PNG-Wadesboro requested to conduct performance testing on one of the four
engines as representative of emissions from all identical engines on site to demonstrate compliance with
the 40 CFR 60 Subpart JJJJ testing requirements.
40 CFR 60 Subpart JJJJ requires periodic testing of subject engines once every three years or
every 8760 hours of operation,whichever occurs first.Upcoming performance testing during calendar year
2022 will be conducted to meet the three-year testing requirement since the engines at the PNG-
Wadesboro site operate less than 8760 hours in a three-year period.Pursuant to 40 C.F.R. § 60.8(b)(4),
performance tests shall be conducted in accordance with the test methods and procedures contained in each
applicable subpart unless the Administrator(DAQ in this case)waives the requirement for performance
tests because the owner or operator of a source has demonstrated by other means to the Administrator's
satisfaction that the affected emission source can continually comply with the standard.
Section VH.2 of the US EPA's April 27,2009, Clean Air Act National Stack Testing Guidance
states that a performance test waiver for identical emissions units may be appropriate when the following
conditions are met:
1. the units are located at the same facility;
2. the units were produced by the same manufacturer,have the same model number or other
manufacturers designation in common, and have the same rated capacity and operating
specifications;
DE � North Carolina Department of Environmental Quality I Division of Air Quality
_ 217 West Jones Street 1 1641 Mail Service Center I Raleigh,North Carolina 27699-1641
�"\ 919.707.8400

Piedmont Natural Gas-Wadesboro Compressor Station
February 14,2022
Page 2
3. the units are operated and maintained in a similar manner; and
4. the EPA or delegated agency,based on documents submitted by facility:
a. determines that the margin of compliance for the identical units tested is significant and
can be maintained on an ongoing basis; or
b. determines based on a review of sufficient emission data that,though the margin of
compliance is not substantial,other factors allow for the determination that the
variability of emissions for identical tested units is low enough for confidence that the
untested unit(s)will be in compliance.These factors may include,but are not limited
to,the following:
i. historical records at the tested unit showing consistent/invariant loads;
ii. fuel characteristics yielding low variability and therefore assurance that the
emissions will be consistent and below allowable levels; and
iii. statistical analysis of a robust emissions data set demonstrates sufficiently low
variability to convey assurance that the margin of compliance,though small,is
reliable.
In reviewing performance testing waiver requests for identical emission sources,DAQ must first
ensure that the criteria outlined above from the US EPA's Clean Air Act National Stack Testing Guidance
are met fully and continuously. Beyond this,DAQ may specify additional requirements on facilities to
ensure all emission units are tested over time on a regular schedule and to ensure continuous compliance
with the applicable emission standard(s)for all units.
To support the request for testing one engine as representative of COMPOI through COMP04,
PNG-Wadesboro provided information on the manufacturer,model number,rated capacity, and operating
specifications for all four engines, as well as analyses of historical emissions data,load$,and run times for
the subject engines.Based on the information provided,the four engines appear to be identical and are
being operated and maintained in the same manner with uniform fuel characteristics. The emissions data
reported for this facility since 2014 demonstrates a significant margin of compliance(greater than 50%)
for all regulated pollutants.
Therefore,DAQ approves the requested waiver of performance testing for identical units at the
PNG-Wadesboro site on an ongoing basis,provided that the following conditions are met:
1. Engines COMP02 through COMP04 are all tested in 2022 since none of these engines have
been tested since 2016;
2. After the 2022 testing is completed,at least half of the subject engines are tested once every
three years with all engines being tested at least once every six years;
3. All engines continue to be limited in annual hours of operation such that no individual
engine exceeds 8760 operating hours in a three-year period;
4. All new performance test results continue to meet the waiver criteria outlined above from
the US EPA's Clean Air Act National Stack Testing Guidance;
5. A justification and supporting data for continuation of this waiver(including hours of
operation for all engines since the last test)should be included in each performance test
report that is intended to provide representative emission results for multiple identical
engines on the same site; and
6. All future protocol submittals for representative testing of identical units include references
to this approval letter and to the most recent justification and supporting data for
continuation of this waiver.
If future test data does not support requirements to maintain classification of the engines as
identical,PNG-Wadesboro may be required to perform additional testing.DAQ will review the facility's

Piedmont Natural Gas-Wadesboro Compressor Station
February 14,2022
Page 3
continual adherence to the criteria for performance test waivers for identical emission units by reviewing
the justification and supporting data that is submitted with each future performance test report.
This performance test waiver does not exempt the facility from complying with its permit, other
applicable requirements of 40 CFR 60 Subpart JJJJ, and other state or federal air quality regulations.
In addition to the mailing of this letter,an electronic copy(e-copy)is being provided for your
records. If you have any questions regarding this waiver approval,please contact Taylor Fort of my staff at
919-707-8431 or [e-mail].
Sincerely,
XA di,
Stephen G. Hall
Chief,Technical Services Section
Division of Air Quality,NC DEQ
cc: Kristen Belisario,Piedmont Natural Gas(e-copy)
Heather Carter,FRO Air Quality Supervisor(hardcopy and e-copy)
Gary Saunders, SSCB Supervisor(e-copy)
IBEAM Documents—0400056