(a) Testing procedures. You must conduct each performance test according to the requirements in paragraphs (b) through (o) of this section and according to the methods specified in table 4 to this subpart.
(b) Periods when performance tests must be conducted. You must conduct each performance test based on representative performance (i.e., performance based on representative operating conditions as defined in § 63.2292) of the affected source for the period being tested. Representative conditions exclude periods of startup and shutdown. You may not conduct performance tests during periods of malfunction. You must describe representative operating conditions in your performance test report for the process and control systems and explain why they are representative. You must record the process information that is necessary to document operating conditions during the test and include in such record an explanation to support that such conditions are representative. Upon request, you shall make available to the Administrator such records as may be necessary to determine the conditions of performance tests.
(c) Number and duration of test runs. You must conduct three separate test runs for each performance test required in this section as specified in § 63.7(e)(3). Each test run must last at least 1 hour except as specified in paragraphs (c)(1) and (2) of this section.
(1) Testing of a temporary total enclosure (TTE) conducted using EPA Methods 204A through 204F of appendix M of part 51 of this chapter, which require three separate test runs of at least 3 hours each; and testing of an enclosure conducted using the alternative tracer gas method in appendix A to this subpart, which requires a minimum of three separate runs of at least 20 minutes each.
(2) Test runs longer than 1 hour may be required to meet minimum sample volume requirements specified in table 4 to this subpart.
(d) Location of sampling sites. (1) Sampling sites must be located at the inlet (if emission reduction testing or documentation of inlet methanol or formaldehyde concentration is required) and outlet of the control device (defined in § 63.2292) and prior to any releases to the atmosphere. For control sequences with wet control devices (defined in § 63.2292) followed by control devices (defined in § 63.2292), sampling sites may be located at the inlet and outlet of the control sequence and prior to any releases to the atmosphere.
(2) Sampling sites for process units meeting compliance options without a control device must be located prior to any releases to the atmosphere. Facilities demonstrating compliance with a production-based compliance option for a process unit equipped with a wet control device must locate sampling sites prior to the wet control device.
(3) Sampling sites must be located at the outlet of the control device (defined in § 63.2292), if a control device is used, and prior to any releases to the atmosphere to demonstrate compliance with the compliance options in table 1C, 1D, or 1E to this subpart and for compliance with the dioxin and furan limits in § 63.2240(d)(2) and (3).
(e) Collection of monitoring data. You must collect operating parameter monitoring system or continuous emissions monitoring system (CEMS) data at least every 15 minutes during the entire performance test and determine the parameter or concentration value for the operating requirement during the performance test using the methods specified in paragraphs (k) through (o) of this section.
(f) Collection of production data. To comply with any of the production-based compliance options in table 1A to this subpart, or compliance options in terms of mass per unit production in table 1C, 1D, or 1E to this subpart, you must measure and record the process unit throughput during each performance test.
(g) Nondetect data. (1) Except as specified in paragraphs (g)(2) and (3) of this section, all nondetect data (defined in § 63.2292) must be treated as one-half of the method detection limit when determining total HAP, formaldehyde, methanol, or total hydrocarbon (THC) emission rates.
(2) When showing compliance with the production-based compliance options in table 1A to this subpart, you may treat emissions of an individual HAP as zero if all three of the performance test runs result in a nondetect measurement, and the method detection limit is less than or equal to 1 parts per million by volume, dry basis (ppmvd). Otherwise, nondetect data for individual HAP must be treated as one-half of the method detection limit.
(3) Nondetect data must be treated as the method detection limit when showing compliance with § 63.2240(d)(3) or (4) and the compliance options in table 1C, 1D, or 1E to this subpart. When determining 2,3,7,8-Tetrachlorodibenzo-p-dioxin toxicity equivalency (TEQ), the value of zero may be used for nondetect results.
(h) Calculation of percent reduction across a control system. When determining the control system efficiency for any control system when complying with any of the compliance options based on percent reduction across a control system in table 1B to this subpart, as part of the performance test, you must calculate the percent reduction using the following equation:
Equation 1 to Paragraph (h)
Where:
PR = Percent reduction, percent.
CE = Capture efficiency, percent (determined for reconstituted wood product presses and board coolers as required in table 4 to this subpart).
ERin = Emission rate of total HAP (calculated as the sum of the emission rates of acetaldehyde, acrolein, formaldehyde, methanol, phenol, and propionaldehyde), THC, formaldehyde, or methanol in the inlet vent stream of the control device, pounds per hour.
ERout = Emission rate of total HAP (calculated as the sum of the emission rates of acetaldehyde, acrolein, formaldehyde, methanol, phenol, and propionaldehyde), THC, formaldehyde, or methanol in the outlet vent stream of the control device, pounds per hour.
(i) Calculation of mass per unit production. To comply with any of the production-based compliance options in table 1A to this subpart, or compliance options in terms of mass per unit production in table 1C, 1D, or 1E to this subpart, you must calculate your mass per unit production emissions for each performance test run using the following equation:
Equation 2 to Paragraph (i)
Where:
MP = Mass per unit production, pounds per oven dried ton OR pounds per thousand square feet on a specified thickness basis (see paragraph (j) of this section if you need to convert from one thickness basis to another).
ERHAP = Emission rate of total HAP (calculated as the sum of the emission rates of acetaldehyde, acrolein, formaldehyde, methanol, phenol, and propionaldehyde) or other pollutant in table 1C, 1D, or 1E to this subpart being measured in the stack, pounds per hour.
P = Process unit production rate (throughput), oven dried tons per hour OR thousand square feet per hour on a specified thickness basis;
CE = Capture efficiency, percent (determined for reconstituted wood product presses and board coolers as required in table 4 to this subpart).
(j) Thickness basis conversion. Use the following equation to convert from one thickness basis to another:
Equation 3 to Paragraph (j)
Where:
MSFA = Thousand square feet on an A-inch basis.
MSFB = Thousand square feet on a B-inch basis.
A = Old thickness you are converting from, inches.
B = New thickness you are converting to, inches.
(k) Establishing thermal oxidizer operating requirements. If you operate a thermal oxidizer, you must establish your thermal oxidizer operating parameters according to paragraphs (k)(1) through (3) of this section.
(1) During the performance test to meet a compliance option in table 1B or 1C to this subpart (or a PAH limit in table 1D or 1E to this subpart), you must continuously monitor the firebox temperature during each of the required 1-hour test runs. For regenerative thermal oxidizers, you may measure the temperature in multiple locations (e.g., one location per burner) in the combustion chamber and calculate the average of the temperature measurements prior to reducing the temperature data to 15-minute averages for purposes of establishing your minimum firebox temperature. The minimum firebox temperature must then be established as the average of the three minimum 15-minute firebox temperatures monitored during the three test runs demonstrating compliance with the applicable standards. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(2) You may establish a different minimum firebox temperature for your thermal oxidizer by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (k)(1) of this section that demonstrates compliance with the applicable compliance options of this subpart.
(3) If your thermal oxidizer is a combustion unit that accepts process exhaust into the flame zone, then you are exempt from the performance testing and monitoring requirements specified in paragraphs (k)(1) and (2) of this section. To demonstrate initial compliance, you must submit documentation with your Notification of Compliance Status showing that process exhausts controlled by the combustion unit enter into the flame zone.
(l) Establishing catalytic oxidizer operating requirements. If you operate a catalytic oxidizer, you must establish your catalytic oxidizer operating parameters according to paragraphs (l)(1) and (2) of this section.
(1) During the performance test to meet a compliance option in table 1B or 1C to this subpart (or a PAH limit in table 1D or 1E to this subpart), you must continuously monitor during the required 1-hour test runs either the temperature at the inlet to each catalyst bed or the temperature in the combustion chamber. For regenerative catalytic oxidizers, you must calculate the average of the temperature measurements from each catalyst bed inlet or within the combustion chamber prior to reducing the temperature data to 15-minute averages for purposes of establishing your minimum catalytic oxidizer temperature. The minimum catalytic oxidizer temperature must then be established as the average of the three minimum 15-minute temperatures monitored during the three test runs demonstrating compliance with the applicable standards. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(2) You may establish a different minimum catalytic oxidizer temperature by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in this paragraph (l) that demonstrates compliance with the applicable compliance options of this subpart.
(m) Establishing biofilter operating requirements. If you operate a biofilter, you must establish your biofilter operating requirements according to paragraphs (m)(1) through (3) of this section.
(1) During the performance test to meet a compliance option in tables 1B through 1E to this subpart, you must continuously monitor the biofilter bed temperature during each of the required 1-hour test runs. To monitor biofilter bed temperature, you may use multiple thermocouples in representative locations throughout the biofilter bed and calculate the average biofilter bed temperature across these thermocouples prior to reducing the temperature data to 15-minute averages for purposes of establishing biofilter bed temperature limits. The biofilter bed temperature range must be established as the temperature values 10 percent below the minimum and 10 percent (not to exceed 8 °F) above the maximum 15-minute biofilter bed temperatures monitored during the three test runs demonstrating compliance with the applicable standards. You may base your biofilter bed temperature range on values recorded during previous performance tests provided that the data used to establish the temperature ranges have been obtained using the test methods required in this subpart. If you use data from previous performance tests, you must certify that the biofilter and associated process unit(s) have not been modified subsequent to the date of the performance tests. Replacement of the biofilter media with the same type of material is not considered a modification of the biofilter for purposes of this section.
(2) For a new biofilter installation, you will be allowed up to 180 days following the compliance date or 180 days following initial startup of the biofilter to complete the requirements in paragraph (m)(1) of this section.
(3) You may expand your biofilter bed temperature operating range by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (m)(1) of this section that demonstrates compliance with the applicable compliance options of this subpart.
(n) Establishing operating requirements for process units meeting compliance options without a control device. If you operate a process unit that meets a compliance option in table 1A, 1C, 1D, or 1E to this subpart without the use of a control device, you must establish your process unit operating parameters according to paragraphs (n)(1) and (2) of this section.
(1) During the performance test, you must identify and document the process unit controlling parameter(s) that affect HAP emissions during the three-run performance test. The controlling parameters you identify must coincide with the representative operating conditions you describe according to paragraph (b) of this section. For each parameter, you must specify appropriate monitoring methods, monitoring frequencies, and for continuously monitored parameters, averaging times not to exceed 24 hours. The operating limit for each controlling parameter must then be established as the minimum, maximum, range, or average (as appropriate depending on the parameter) recorded during the performance test. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(2) You may establish different controlling parameter limits for your process unit by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (n)(1) of this section that demonstrates compliance with the compliance options in table 1A, 1C, 1D, or 1E to this subpart for an uncontrolled process unit.
(o) Establishing operating requirements using THC CEMS. If you choose to meet the operating requirements by monitoring THC concentration instead of monitoring control device or process operating parameters, you must establish your THC concentration operating requirement according to paragraphs (o)(1) and (2) of this section.
(1) During the performance test, you must continuously monitor THC concentration using your CEMS during each of the required 1-hour test runs. The maximum THC concentration must then be established as the average of the three maximum 15-minute THC concentrations monitored during the three test runs demonstrating compliance with the applicable standards. Multiple three-run performance tests may be conducted to establish a range of THC concentration values under different operating conditions.
(2) You may establish a different maximum THC concentration by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (o)(1) of this section that demonstrates compliance with the compliance options in tables 1A and 1B to this subpart.
(p) Establishing wet electrostatic precipitator operating requirements. If you use a wet electrostatic precipitator to meet a compliance option in table 1D or 1E to this subpart, you must establish your wet electrostatic precipitator operating requirements according to paragraphs (p)(1) through (3) of this section except as specified in paragraph (p)(4) of this section if you are using a COMS.
(1) During the PM or Hg performance test, you must continuously monitor the total secondary electric power during each of the required test runs. The minimum total secondary electric power must then be established as the average of the three minimum 15-minute total secondary electric power values monitored during the three test runs demonstrating compliance with the applicable emission limits in this subpart.
(2) During the PM, Hg, or HCl performance test, you must continuously monitor the liquid flow rate to the wet electrostatic precipitator during each of the required test runs. The minimum liquid flow rate must then be established as the average of the three minimum 15-minute liquid flow rate values monitored during the three test runs demonstrating compliance with the applicable emission limits in this subpart.
(3) You may establish a different minimum total secondary power or liquid flow rate limits for your wet electrostatic precipitator by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraphs (p)(1) and (2) of this section that demonstrates compliance with the applicable emission limits in this subpart. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(4) For a WESP followed by a control device with a dry exhaust for which you choose to use a COMS instead of WESP parameter monitoring, you must follow the procedures in paragraph (t) of this section for establishing the opacity operating limit.
(q) Establishing dry electrostatic precipitator operating requirements. If you use a dry electrostatic precipitator to meet a compliance option in table 1D or 1E to this subpart, you must establish your dry electrostatic precipitator operating requirements according to paragraphs (q)(1) and (2) of this section.
(1) During the PM or Hg performance test, you must continuously monitor the total secondary electric power during each of the required test runs. The minimum total secondary electric power must then be established as the average of the three minimum 15-minute total secondary electric power values monitored during the three test runs demonstrating compliance with the emission limits in this subpart.
(2) You may establish a different minimum total secondary power limits for your dry electrostatic precipitator by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (q)(1) of this section that demonstrates compliance with the applicable emission limits in this subpart. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(r) Establishing wet scrubber operating requirements. If you use a wet scrubber to meet a compliance option in table 1D or 1E to this subpart, you must establish your wet scrubber operating requirements according to paragraphs (r)(1) through (4) of this section.
(1) During the performance test, you must continuously monitor the scrubber liquid flow rate during each of the required test runs. The minimum liquid flow rate must then be established as the average of the three minimum 15-minute liquid flow rate values monitored during the three test runs demonstrating compliance with the compliance options in table 1D or 1E to this subpart.
(2) For a wet PM scrubber, during the PM performance test, you must continuously monitor pressure drop across the scrubber during each of the required test runs. The minimum pressure drop must then be established as the average of the three minimum 15-minute pressure drop values monitored during the three test runs demonstrating compliance with the PM limit.
(3) For wet acid gas scrubber, during the HCl performance test, you must continuously monitor the scrubber effluent pH during each of the required test runs. The minimum effluent pH must then be established as the average of the three minimum 15-minute pH values monitored during the three test runs demonstrating compliance with the HCl limit.
(4) You may establish different minimum liquid flow rate, pressure drop, or pH values for your wet scrubber by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraphs (r)(1) through (3) of this section that demonstrates compliance with the applicable emission limits in this subpart. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(s) Establishing electrified filter bed operating requirements. If you use an electrified filter bed to meet a compliance option in table 1D or 1E to this subpart, you must establish your electrified filter bed operating requirements according to paragraphs (s)(1) through (3) of this section.
(1) During the PM or Hg performance test, you must continuously monitor the bed voltage and ionizer voltage during each of the required test runs. The minimum bed voltage limit and ionizer voltage limit must then be established as the average of the three minimum 15-minute bed voltage values and ionizer voltage values monitored during the three test runs demonstrating compliance.
(2) During the PM or Hg performance test, you must continuously monitor the pressure drop across the electrified filter bed during each of the required test runs. The pressure drop range limits must then be established as the average of the three minimum and three maximum 15-minute pressure drop values monitored during the three test runs demonstrating compliance with the applicable emission limits in this subpart.
(3) You may establish different bed voltage and ionizer voltage limits or pressure drop range limits for your electrified filter bed by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (s)(1) and (2) of this section that demonstrates compliance with the applicable emission limits in this subpart. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
(t) Establishing operating requirements using opacity measured with a COMS. If you use a mechanical collector (or other dry control device not listed elsewhere in table 2 to the subpart) or WESP followed by a control device with a dry exhaust (for which you choose to use a COMS) to meet a compliance option in table 1D or 1E to this subpart, you must establish your operating requirements according to paragraphs (t)(1) and (2) of this section.
(1) During the PM performance test, you must continuously monitor opacity during each of the required test runs. The maximum opacity limit must then be established as either 10 percent opacity, or the highest hourly average computed from the 6-minute opacity values monitored during the three test runs demonstrating compliance with the PM limit.
(2) You may establish different opacity limits by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (t)(1) of this section that demonstrates compliance with the applicable emission limits in this subpart. Multiple three-run performance tests may be conducted to establish a range of opacity values under different operating conditions.
(u) Establishing operating requirements based on pressure drop with opacity observations. If you use a mechanical collector (or other dry control device not listed elsewhere in table 2 to this subpart) to meet a compliance option in table 1D or 1E to this subpart, and you choose to use a combination of pressure drop and opacity observations instead of a COMS to demonstrate continuous compliance, you must establish your operating requirements according to paragraphs (u)(1) through (3) of this section.
(1) During the PM performance test, you must continuously monitor pressure drop across the mechanical collector (or other dry control device) during each of the required test runs. The minimum pressure drop limit must then be established as the average of the three minimum 15-minute pressure drop values monitored during the three test runs demonstrating compliance with the PM limit.
(2) During the PM performance test, you must conduct opacity observations of the control device outlet emissions to the atmosphere using EPA Method 9 of appendix A-4 to part 60 of this chapter. You must establish the maximum opacity operating limit as the average of the 6-minute opacity observations during the three test runs demonstrating compliance with the PM limit, or 10 percent opacity, whichever is greater.
(3) You may establish a different pressure drop limit or opacity observation limit by submitting the notification specified in § 63.2280(g) and conducting a repeat performance test as specified in paragraph (u)(1) or (2) of this section that demonstrates compliance with the applicable emission limits in this subpart. Multiple three-run performance tests may be conducted to establish a range of parameter values under different operating conditions.
[91 FR 41437, July 6, 2026]