§ 63.364 Monitoring requirements.

(a) General requirements. (1) If you own or operate an affected source subject to an emission standard in § 63.362, you must comply with the monitoring requirements in § 63.8, according to the applicability in table 6 to this subpart, and in this section.

(2) If you own or operate an affected source at a facility where EtO use is less than 100 lb/yr that is subject to an emission standard in § 63.362, you may monitor the parameters specified in paragraphs (b), (c), (d), (e), (g), and (i) of this section. All monitoring equipment shall be installed such that representative measurements of emissions or process parameters from the source are obtained. For monitoring equipment purchased from a vendor, verification of the operational status of the monitoring equipment shall include completion of the manufacturer's written specifications or recommendations for installation, operation, and calibration of the system.

(3) If you own or operate an affected source that is subject to an emission standard in § 63.362 and that is required to monitor using EtO CEMS, you must comply with paragraphs (f), (g), and (i) of this section.

(4) If you comply with the management practice for Group 2 room air emissions at area sources, you must comply with paragraph (h) of this section.

(5) You must keep the written procedures required by § 63.8(d)(2) on record for the life of the affected source or until the affected source is no longer subject to the provisions of this part, to be made available for inspection, upon request, by the Administrator. If the performance evaluation plan is revised, you must keep previous (i.e., superseded) versions of the performance evaluation plan on record to be made available for inspection, upon request, by the Administrator, for a period of 5 years after each revision to the plan. The program of corrective action should be included in the plan required under § 63.8(d)(2).

(b) Acid-water scrubbers. If you are demonstrating continuous compliance through periodic performance testing on an acid-water scrubber(s), you must:

(1) Ethylene glycol concentration. Sample the scrubber liquor from the acid-water scrubber(s) and analyze and record at least once per week the ethylene glycol concentration of the scrubber liquor using the test methods and procedures in § 63.365(e)(1). Monitoring is required during a week only if the scrubber unit has been operated. You must maintain the weekly ethylene glycol concentration below the operating limit established during the most recent performance test;

(2) Scrubber liquor tank level. Measure and record at least once per day the level of the scrubber liquor in the recirculation tank(s). You must install, maintain, and use a liquid level indicator to measure the scrubber liquor tank level (i.e., a marker on the tank wall, a dipstick, a magnetic indicator, etc.). Monitoring is required during a day only if the scrubber unit has been operated. You must maintain the daily scrubber liquor height in each recirculation tank below the applicable operating limit established during the most recent performance test; or

(3) pH. Monitor and record at least every 15 minutes the scrubber liquor pH. Monitoring is required when the scrubber is operating. A data acquisition system for the pH monitor shall compute and record each 3-hour average scrubber liquor pH value, rolled hourly. This must be done by first averaging the scrubber liquor pH readings obtained over a clock hour, i.e., beginning and ending on the hour. All data collected during the operating hour must be used, even if the scrubber unit is not operating for a complete hour. Then, the average of the previous 3 operating hours must be calculated to determine the 3-hour rolling average scrubber liquor pH. You must maintain the 3-hour rolling average scrubber liquor pH below the applicable operating limit established during the most recent performance test. You must ensure the pH monitoring system meets the following requirements:

(i) The pH sensor must be installed in a position that provides a representative measurement of scrubber liquor pH;

(ii) The sample must be properly mixed and representative of the fluid to be measured; and

(iii) A performance evaluation (including a two-point calibration with one of the two buffer solutions having a pH within 1 of the pH of the operating limit) of the pH monitoring system must be conducted in accordance with your monitoring plan at the time of each performance test but no less frequently than quarterly.

(c) Oxidizers. If you are demonstrating continuous compliance through periodic performance testing on a catalytic oxidizer or thermal oxidizer, the requirements in paragraphs (c)(1) and (2) of this section apply:

(1) For thermal oxidizers, you must monitor and record at least every 15 minutes the temperature in or immediately downstream of the firebox using the temperature monitor described in paragraph (c)(4) of this section. Monitoring is required when the thermal oxidizer is operating. A data acquisition system for the temperature monitor shall compute and record each 3-hour average temperature value, rolled hourly. This must be done by first averaging the temperature readings over a clock hour, i.e., beginning and ending on the hour. All data collected during the operating hour must be used, even if the thermal oxidizer is not operating for a complete hour. Then, the average of the previous 3 operating hours must be calculated to determine the 3-hour rolling average temperature in or immediately downstream of the firebox. You must maintain the 3-hour rolling average temperature above the operating limit established during the most recent performance test.