SUBTITLE B: AIR POLLUTION
CHAPTER I: POLLUTION CONTROL BOARD
SUBCHAPTER c: EMISSION STANDARDS AND LIMITATIONS FOR STATIONARY SOURCES
PART 217 NITROGEN OXIDES EMISSIONS
SECTION 217.394 TESTING AND MONITORING
Section 217.394 Testing and Monitoring
a) Before July 1, 2025, an owner or operator must conduct an initial performance test under subsection (d)(1) or (d)(2) of this Section as follows:
1) By January 1, 2008, for affected engines listed in Appendix G. Performance tests must be conducted on units listed in Appendix G, even if the unit is included in an emissions averaging plan under Section 217.388(a)(2).
2) By the applicable compliance date set forth in Section 217.392, or within the first 876 hours of operation per calendar year, whichever is later:
A) For affected units not listed in Appendix G that operate more than 876 hours per calendar year; and
B) For units that are not affected units that are included in an emissions averaging plan and operate more than 876 hours per calendar year.
3) Once within the five-year period after the applicable compliance date as set forth in Section 217.392 or once within the five-year period following the date the unit commenced operation:
A) For affected units that operate fewer than 876 hours per calendar year; and
B) For units that are not affected units that are included in an emissions averaging plan and that operate fewer than 876 hours per calendar year.
b) On and after July 1, 2025, an owner or operator of a reciprocating internal combustion engine or turbine, including those that are part of an emissions averaging plan, must either conduct performance testing or install and operate a CEMS in compliance with the requirements in this Section, as applicable, unless the engine or turbine operates as a low usage unit under Section 217.388(a)(3)(B). An owner or operator must conduct an initial performance test under subsection (d)(1) or (d)(2) of this Section. Performance testing of NOx emissions for engines and turbines for which construction or modification occurs after July 1, 2025, must be conducted within 60 days after achieving maximum operating rate but no later than 180 days after initial startup of the new or modified engine or turbine, in accordance with this Section. If performance testing was already conducted by an owner or operator under subsection (d) within five years before July 1, 2025, the owner or operator is not required to conduct an additional initial performance test.
c) An owner or operator of an engine or turbine must conduct subsequent performance tests under subsection (c)(1), (c)(2), and (c)(3) of this Section as follows:
1) Affected engines listed in Appendix G and all units included in an emissions averaging plan must conduct a performance test at the owner or operator's own expense once every five years. Testing must be performed in the calendar year by May 1 or within 60 days after starting operation, whichever is later;
2) If the monitored data shows that the unit is not in compliance with the applicable emissions concentration or emissions averaging plan, the owner or operator must report the deviation to the Agency in writing within 30 days and conduct a performance test under subsection (d) of this Section within 90 days of the determination of noncompliance; and
3) When, in the opinion of the Agency or USEPA, it is necessary to conduct testing to demonstrate compliance with Section 217.388, the owner or operator of a unit must, at his or her own expense, conduct the test in accordance with the applicable test methods and procedures specified in this Section within 90 days after receipt of a notice to test from the Agency or USEPA.
d) Testing Procedures:
1) For an engine: The owner or operator must conduct a performance test using Method 7 or 7E of 40 CFR 60, appendix A-4, as incorporated by reference in Section 217.104. Each compliance test must consist of three separate runs, each lasting a minimum of 60 minutes. NOx emissions must be measured while the affected unit is operating at peak load. If the unit combusts more than one type of fuel (gaseous or liquid), including backup fuels, a separate performance test is required for each fuel.
2) For a turbine: The owner or operator must conduct a performance test using the applicable procedures and methods in 40 CFR 60.4400, as incorporated by reference in Section 217.104.
e) Monitoring: Except for those years in which a performance test is conducted under subsection (a), (b), or (c) of this Section, the owner or operator of an affected unit or a unit included in an emissions averaging plan must monitor NOx concentrations annually, once between January 1 and May 1 or within the first 876 hours of operation per calendar year, whichever is later. If annual operation is less than 876 hours per calendar year, each affected unit must be monitored at least once every five years. Monitoring must be performed as follows:
1) A portable NOx monitor utilizing method ASTM D6522-20, as incorporated by reference in Section 217.104, or a method approved by the Agency must be used. If the engine or turbine combusts both liquid and gaseous fuels as primary or backup fuels, separate monitoring is required for each fuel.
2) NOx and O2 concentrations measurements must be taken three times for a duration of at least 20 minutes. Monitoring must be done at highest achievable load considering the ambient conditions during operation. The concentrations from the three monitoring runs must be averaged to determine whether the affected unit is in compliance with the applicable emissions concentration or emissions averaging plan, as specified in Section 217.388.
f) Instead of complying with the requirements of subsections (a), (b), (c), (d) and (e) of this Section, an owner or operator may install and operate a CEMS on an affected unit that meets the applicable requirements of 40 CFR 60, subpart A and appendix B, or 40 CFR 75, incorporated by reference in Section 217.104, and complies with the quality assurance procedures specified in 40 CFR 60, appendix F or 40 CFR 75, as incorporated by reference in Section 217.104, or an alternate procedure as approved by the Agency or USEPA in a federally enforceable permit. Until July 1, 2025, the CEMS must be used to demonstrate compliance with the applicable emissions concentration or emissions averaging plan only on an ozone season and annual basis. On and after July 1, 2025, the CEMS must be used to demonstrate compliance with the applicable emissions concentration or emissions averaging plan only on a 30-day rolling average basis.
g) The testing and monitoring requirements of this Section do not apply to affected units in compliance with the requirements of the low usage limitations under Section 217.388(a)(3), unless the units are included in an emissions averaging plan. Despite the above circumstances, when, in the opinion of the Agency or USEPA, it is necessary to conduct testing to demonstrate compliance with Section 217.388, the owner or operator of a unit must, at his or her own expense, conduct the test in accordance with the applicable test methods and procedures specified in this Section within 90 days after receipt of a notice to test from the Agency or USEPA.
h) For an owner or operator of a turbine monitoring in accordance with 40 CFR 75, Appendix E, for the purposes of demonstrating compliance with Section 217.388(a)(1)(E), rather than using substitution data procedures according to 40 CFR 75, Subpart D, the owner or operator of a unit may calculate emissions during periods of operation that are below the minimum operating load tested or above the maximum operating load tested as follows:
1) For periods of operation below the minimum operating load tested, the owner or operator must use the concentration measured at the minimum operating load tested in accordance with 40 CFR Part 75, Appendix E.
2) For periods of operation above the maximum operating load tested, the owner or operator must use the concentration measured at the maximum operating load tested in accordance with 40 CFR Part 75, Appendix E.
(Source: Amended at 49 Ill. Reg. 6355, effective April 23, 2025)