PURPOSE: This rule reduces emissions of oxides of nitrogen (NOx) to ensure compliance with the federal NOx control plan to reduce the transport of air pollutants. This rule establishes emission levels for large stationary internal combustion engines. The evidence supporting the need for this rule, per section 536.016, RSMo, is the U.S. Environmental Protection Agency NOx State Implementation Plan (SIP) Call dated April 21, 2004.

1. (1) Applicability.

   1. (A) This rule applies to any large stationary internal combustion engine greater than one thousand three hundred (1,300) horsepower located in the counties of Bollinger, Butler, Cape Girardeau, Carter, Clark, Crawford, Dent, Dunklin, Franklin, Gasconade, Iron, Jefferson, Lewis, Lincoln, Madison, Marion, Mississippi, Montgomery, New Madrid, Oregon, Pemiscot, Perry, Pike, Ralls, Reynolds, Ripley, St. Charles, St. Francois, St. Louis, Ste. Genevieve, Scott, Shannon, Stoddard, Warren, Washington, and Wayne and the City of St. Louis that—

      1. 1. Emitted greater than one (1) ton per day of oxides

of nitrogen (NOx) on average during the period from May 1 through September 30 of 1995, 1996, or 1997; or

1. 2. Began operation after September 30, 1997.

2. (B) Exemptions.

   1. 1. Any stationary internal combustion (IC) engine that

meets the definition of emergency standby engine in section (2) of this rule, with allowance for up to one hundred (100) hours per calendar year for operation during routine maintenance checks (including readiness testing), is exempt from this rule.

1. 2. Any stationary IC engine that began operation after

September 30, 1997, and emits twenty-five (25) tons or less of NOx during the period from May 1 through September 30 is exempt from section (3) and subsection (5)(A) of this rule. The owner or operator of an exempt large stationary IC engine must demonstrate compliance with the twenty-five (25) ton exemption threshold using one (1) of the methods in subsection (5)(B) of this rule. This exemption will be based on the previous year NOx emissions during the period from May 1 through September 30. If the exemption limit is exceeded, for any reason, the engine will be required to meet the applicable requirements in subsections (3)(A), (3)(B), (3)(C), and (3)(D) of this rule each year thereafter.

1. (2) Definitions.

   1. (A) Compression ignition—A type of stationary internal combustion engine that is not a spark ignition engine.
   2. (B) Diesel engine—A compression-ignited two (2)- or four (4)-stroke engine in which liquid fuel is injected into the combustion chamber and ignited when the air charge has been compressed to a temperature sufficiently high for autoignition.
   3. (C) Dual fuel engine—Compression-ignited stationary internal combustion engine that is capable of burning liquid fuel and gaseous fuel simultaneously.
   4. (D) Emergency standby engine—An internal combustion engine used only when normal electrical power or natural gas service is interrupted or for the emergency pumping of water for either fire protection or flood relief. An emergency standby engine may not be operated to supplement a primary power source when the load capacity or rating of the primary power source has been either reached or exceeded.
   5. (E) Lean-burn engine—Any two (2)- or four (4)-stroke sparkignited engine with greater than four percent (4%) oxygen in the engine exhaust.
   6. (F) Rich-burn engine—A two (2)- or four (4)-stroke sparkignited engine where the oxygen content in the exhaust stream before any dilution is one percent (1%) or less measured on a dry basis.
   7. (G) Spark ignition (SI)—relating to either a gasoline-fueled engine or any other type of engine with a spark plug or other sparking device and with operating characteristics significantly similar to the theoretical Otto combustion cycle. Spark ignition engines usually use a throttle to regulate intake air flow to control power during normal operation. Dual-fuel engines in which a liquid fuel is used for compression ignition and gaseous fuel (typically natural gas) is used as a primary fuel at an annual average ratio of less than two (2) parts diesel fuel to one-hundred (100) parts total fuel on an energy equivalent basis are spark ignition engines.
   8. (H) Stationary internal combustion engine—Internal combustion engine of the reciprocating type that is either attached to a foundation at a facility or is designed to be capable of being carried or moved from one (1) location to another and remains at a single site at a building, structure, facility, or installation for more than twelve (12) consecutive months. Any engine(s) that replace(s) an engine at a site that is intended to perform the same or similar function as the engine replaced is included in calculating the consecutive time period. Nonroad engines and engines used solely for competition are not stationary IC engines.
   9. (I) Utilization rate—The amount of an engine’s capacity reported in horsepower-hours that is utilized.
   10. (J) Definitions of certain terms used in this rule, other than those specified in this rule, may be found in 10 CSR 10-6.020.

2. (3) General Provisions.

   1. (A) Emission Requirements.

      1. 1. For engines emitting more than one (1) ton per day

of NOx on average during the period from May 1 through September 30 in 1995, 1996, or 1997—

1. A. An owner or operator of a large stationary internal

combustion engine must use the following calculation to determine the allowable NOx emission rate for each applicable engine and not exceed this emission rate limit for any ozone season thereafter using: ER =(NOx act/UR) × 1.102 × 10-6 × 0.1 where, ER = the allowable emission rate for each engine in grams per horsepower-hour; NOx act= the highest actual NOx emissions, reported in tons per control period, for the period from May 1 through September 30 for one of the years 1995, 1996, or 1997 based on the best available emission information for each engine; and UR = the utilization rate in horsepower-hours during the same period as NOx act;

1. B. In lieu of subparagraph (3)(A)1.A. of this rule, an owner

or operator of a large stationary internal combustion engine may choose to establish a facility-wide NOx emissions cap. If the owner or operator commits to comply with this subparagraph rather than subparagraph (3)(A)1.A. of this rule, the owner or operator must submit the following to the director:

1. (I) The facility-wide NOx emissions from the year of

data that would be used in subparagraph (3)(A)1.A. of this rule on a per engine basis;

1. (II) The number of tons of NOx emission reductions

that would be required in subparagraph (3)(A)1.A. of this rule on a per engine basis;

1. (III) A detailed inventory of all engines being used to

comply with the NOx emission cap including the:

1. (a) Uncontrolled emission rate of all engines at the

facility;

1. (b) Controlled emission rate for all engines being

controlled under the NOx emissions cap;

1. (c) Capacity of each engine at the facility; and
2. (d) Utilization rate of each engine at the facility; and
3. (IV) The controlled NOx emissions from the facility

during the control period, May 1 through September 30.

1. 2. For engines that began operation after September

1997. An owner or operator of a large stationary internal combustion engine must not operate an engine to exceed the permitted NOx emission rate or the following NOx emission rate, whichever is more stringent:

1. A. For SI rich-burn engines, 3.0 grams per horsepower-

hour;

1. B. For SI lean-burn engines, 3.0 grams per horsepower-

hour;

1. C. For diesel engines, 2.3 grams per horsepower-hour; or
2. D. For dual fuel engines, 1.5 grams per horsepower-hour;
3. (B) Reduced Energy Consumption Option. To meet the requirements of subparagraph (3)(A)1.A. or paragraph (3)(A)2. of this rule, the owner or operator of a large stationary internal combustion engine may take into account, as a portion of the required NOx reductions, physical and quantifiable measures to increase energy efficiency, reduce energy demand, or increase use of renewable fuels for a particular engine.
4. (C) Monitoring Requirements. The owner or operator of a large stationary internal combustion engine must monitor for compliance in accordance with subsection (5)(A) of this rule.
5. (D) Excess Emissions During Start-Up, Shutdown, or Malfunction. If the owner or operator provides notice of excess emissions pursuant to state rule 10 CSR 10-6.050(3)(B), the director will determine whether the excess emissions are attributable to start-up, shutdown, or malfunction conditions, pursuant to rule 10 CSR 10-6.050(3)(C).

1. (4) Reporting and Record Keeping. The owner or operator of a large stationary internal combustion engine subject to this rule or to the exemption in paragraph (1)(B)2. of this rule must comply with the following requirements in this section of the rule:

   1. (A) Reporting Requirements.

      1. 1. Submit to the director the identification number and

type of each engine subject to this rule or to the exemption in paragraph (1)(B)2. of this rule, the name and address of the plant where the engine is located, and the name and telephone number of the person responsible for demonstrating compliance with this rule;

1. 2. Submit a report documenting for each engine the total

NOx emissions of the first full compliance period from May 1 through September 30 to the director by November 1 of that year; and

1. 3. If an engine is equipped with a continuous emission

monitoring system (CEMS), submit an excess emissions monitoring systems performance report, in accordance with the requirements of 40 CFR 60.7(c) and 60.13 as specified in 10 CSR 10-6.070(3)(A)1.; and

1. (B) Record-Keeping Requirements.

   1. 1. Maintain all records necessary to demonstrate

compliance with this rule for a period of five (5) years at the plant at which the subject engine is located which include the following:

1. A. Records for engines applying subsection (3)(B) of this

rule;

1. B. Records verifying an engine(s) is subject to paragraph

(3)(A)1. of this rule;

1. C. For engines subject to subparagraph (3)(A)1.B. of this

rule, records required by parts (3)(A)1.B.(I) through (3)(A)1.B.(IV) of this rule;

1. D. Records for engines subject to paragraphs (5)(A)1. and

(5)(A)2. of this rule; and

1. E. Records for engines subject to paragraphs (5)(B)1.

through (5)(B)4. of this rule.

1. 2. Make the records available to the director upon request.
2. 3. Maintain records of the following information for each

day of the control period the engine is operated:

1. A. The identification number of each applicable engine

and the name and address of the plant where the engine is located;

1. B. The calendar date of record;
2. C. The number of hours the engine is operated during

each day including start-ups, shutdowns, malfunctions, and the type and duration of maintenance and repair;

1. D. Where applicable, the date and results of any

inspection that affect emissions;

1. E. Where applicable, a summary of any corrective

maintenance taken that affect emissions;

1. F. Where applicable, the results of all compliance tests;

and

1. G. If an engine is equipped with a CEMS—

   1. (I) The identification of time periods during which

NOx standards are exceeded, the reason for the exceedance, and action taken to correct the exceedance and to prevent similar future exceedances; and

1. (II) The identification of the time periods for which

operating conditions and pollutant data were not obtained including reasons for not obtaining sufficient data and a description of the corrective actions taken.

1. (5) Test Methods.

   1. (A) The owner or operator of a large stationary internal combustion engine meeting the applicability requirements of subsection (1)(A) of this rule and not exempt under subsection (1)(B) of this rule, must not operate such equipment unless one

2. (1) of the following is met:

   1. 1. When a CEMS is installed which meets the requirements

of 40 CFR 60, Appendix B and F as specified in 10 CSR 10- 6.030(22)—The CEMS must be used to demonstrate compliance with the applicable emission limit and operated and maintained in accordance with the on-site CEMS requirements; or

1. 2. For an alternate monitoring method consisting of

a calculational and record keeping procedure based upon actual NOx emissions testing and correlations with operating parameters, the installation, implementation, and use of such an alternate monitoring method must be approved by the director and the U.S. Environmental Protection Agency (EPA); and incorporated into this rule and the state implementation plan (SIP) prior to implementation. The alternate monitoring method must be operated and maintained in accordance with the approved alternate monitoring plan. (B) One (1) of the following emissions measurement approaches must be used to provide a demonstration of compliance with the twenty-five (25)-ton exemption threshold for stationary IC engines under paragraph (1)(B)2. of this rule:

1. 1. Certificates of conformity for affected engines confirming

compliance with 40 CFR 90, 40 CFR 1048, or 40 CFR 1054 promulgated as of July 1, 2018, and hereby incorporated by reference in this rule, as published by the Office of the Federal Register. Copies can be obtained from the U.S. Publishing Office Bookstore, 710 N. Capitol Street NW, Washington, DC 20401 (This rule does not incorporate any subsequent amendments or additions); and operating the engine according to the manufacturer’s specifications;

1. 2. Stack tests as specified in 10 CSR 10-6.030(22);
2. 3. Engine manufacturer technical specification sheets for

affected engines; or

1. 4. Other methods, as approved by the director and the

EPA; and incorporated into this rule and the SIP prior to implementation. These may include fuel usage calculations, approved engineering calculations, other methods described in permits, or other EPA documentation.

AUTHORITY: section 643.050, RSMo 2016.* Original rule filed Feb. 14, 2005, effective Oct. 30, 2005. Amended: Filed Aug. 27, 2009, effective May 30, 2010. Amended: Filed March 13, 2013, effective Oct. 30, 2013. Amended: Filed June 27, 2018, effective March 30, 2019. Amended: Filed Aug. 9, 2019, effective May 30, 2020.

*Original authority: 643.050, RSMo 1965, amended 1972, 1992, 1993, 1995, 2011.