(a) Oxygen (O2 ) monitors. If the owner or operator installs an O2 monitor, the criteria in §117.8100(a) of this title (relating to Emission Monitoring System Requirements for Industrial, Commercial, and Institutional Sources) should be considered the appropriate guidance for the location and calibration of the monitor.
(b) Nitrogen oxides (NOX ) monitors. If the owner or operator installs a continuous emissions monitoring system (CEMS) or predictive emissions monitoring system (PEMS), the CEMS or PEMS must meet the requirements of §117.8100(a) or (b) of this title. If a PEMS is used, the PEMS must predict the pollution emissions in the units of the applicable emission limitations of this division.
(c) Monitor installation schedule. Installation of monitors must be performed in accordance with the schedule specified in §117.9210 of this title (relating to Compliance Schedule for Dallas-Fort Worth Eight-Hour Ozone Nonattainment Area Minor Sources).
(d) Testing requirements. The owner or operator of any unit subject to §117.2110 of this title (relating to Emission Specifications for Eight-Hour Attainment Demonstration) shall comply with the following testing requirements.
  (1) Each unit must be tested for NOX , carbon monoxide (CO), and O2 emissions.
  (2) One of the ammonia monitoring procedures specified in §117.8130 of this title (relating to Ammonia Monitoring) must be used to demonstrate compliance with the ammonia emission specification of §117.2110(h)(2) of this title for units that inject urea or ammonia into the exhaust stream for NOX control. This paragraph does not apply to stationary diesel engines equipped with selective catalytic reduction (SCR) systems that meet all of the following criteria.
    (A) The SCR system must use a reductant other than the engine's fuel.
    (B) The SCR system must operate with a diagnostic system that monitors reductant quality and tank levels.
    (C) The diagnostic system must alert owners or operators to the need to refill the reductant tank before it is empty or to replace the reductant if the reductant does not meet applicable concentration specifications.
    (D) If the SCR system uses input from an exhaust NOX sensor (or other sensor) to alert owners or operators when the reductant quality is inadequate, the reductant quality does not need to be monitored separately by the diagnostic system.
    (E) The reductant tank level must be monitored in accordance with the manufacturer's design to demonstrate compliance with this paragraph.
    (F) The method of alerting an owner or operator must be a visual or audible alarm.
  (3) For units not equipped with CEMS or PEMS, all testing must be conducted according to §117.8000 of this title (relating to Stack Testing Requirements). In lieu of the test methods specified in §117.8000 of this title, the owner or operator may use American Society for Testing and Materials (ASTM) D6522-00 to perform the NOX , CO, and O2 testing required by this subsection on natural gas-fired reciprocating engines. If the owner or operator elects to use ASTM D6522-00 for the testing requirements, the report must contain the information specified in §117.8010 of this title (relating to Compliance Stack Test Reports).
  (4) Test results must be reported in the units of the applicable emission specifications and averaging periods. If compliance testing is based on 40 Code of Federal Regulations Part 60, Appendix A reference methods, the report must contain the information specified in §117.8010 of this title.
  (5) For units equipped with CEMS or PEMS, the CEMS or PEMS must be installed and operational before testing under this subsection. Verification of operational status must, at a minimum, include completion of the initial monitor certification and the manufacturer's written requirements or recommendations for installation, operation, and calibration of the device.
  (6) Initial compliance with the emission specifications of §117.2110 of this title for units operating with CEMS or PEMS must be demonstrated after monitor certification testing using the NOX CEMS or PEMS.
  (7) For units not operating with CEMS or PEMS, the following apply.
    (A) Retesting as specified in paragraphs (1) - (4) of this subsection is required within 60 days after any modification that could reasonably be expected to increase the NOX emission rate.
    (B) Retesting as specified in paragraphs (1) - (4) of this subsection may be conducted at the discretion of the owner or operator after any modification that could reasonably be expected to decrease the NOX emission rate, including, but not limited to, installation of post-combustion controls, low-NOX burners, low excess air operation, staged combustion (for example, overfire air), flue gas recirculation, and fuel-lean and conventional (fuel-rich) reburn.
    (C) Stationary, reciprocating internal combustion engines not equipped with CEMS or PEMS must be periodically tested for NOX and CO emissions as specified in §117.8140(a) of this title (relating to Emission Monitoring for Engines).
  (8) Testing must be performed in accordance with the schedule specified in §117.9210 of this title.
  (9) All test reports must be submitted to the executive director for review and approval within 60 days after completion of the testing.
  (10) The owner or operator of an affected unit in the Dallas-Fort Worth eight-hour ozone nonattainment area must submit written notification of any CEMS or PEMS relative accuracy test audit (RATA) or testing required under this section to the appropriate regional office and any local air pollution control agency having jurisdiction at least 15 days in advance of the date of RATA or testing.
(e) Run time meters. The owner or operator of any stationary diesel engine claimed exempt using the exemption of §117.2103(5), (8), (9), or (10) of this title (relating to Exemptions) shall record the operating time with a non-resettable elapsed run time meter.

Source Note: The provisions of this §117.2135 adopted to be effective June 14, 2007, 32 TexReg 3206; amended to be effective May 2, 2013, 38 TexReg 2634; amended to be effective May 16, 2024, 49 TexReg 3347