40 CFR § 63.1303 - Monitoring requirements.
Owners and operators of affected sources shall comply with each applicable monitoring provision in this section.
(a) Monitoring requirements for storage vessel carbon adsorption systems. Each owner or operator using a carbon adsorption system to meet the requirements of § 63.1294(a) shall monitor the concentration level of the HAP or the organic compounds in the exhaust vent stream (or outlet stream exhaust) from the carbon adsorption system at the frequency specified in paragraph (a)(1) or (2) of this section.
(1) The concentration level of HAP or organic compounds shall be monitored during each unloading event, or once per month during an unloading event if multiple unloading events occur in a month.
(2) As an alternative to monthly monitoring, the owner or operator can set the monitoring frequency at an interval no greater than 20 percent of the carbon replacement interval, which is established using a design analysis described below in paragraphs (a)(1)(i) through (iii) of this section.
(i) The design analysis shall consider the vent stream composition, constituent concentration, flow rate, relative humidity, and temperature.
(ii) The design analysis shall establish the outlet organic concentration level, the capacity of the carbon bed, and the working capacity of activated carbon used for the carbon bed, and
(iii) The design analysis shall establish the carbon replacement interval based on the total carbon working capacity of the carbon adsorption system and the schedule for filling the storage vessel.
(b) Each owner or operator using a carbon adsorption system to meet the requirements of § 63.1294(a) shall monitor the concentration level of total organic compounds in the exhaust vent stream (or outlet stream exhaust) from the carbon adsorption system using 40 CFR part 60, Appendix A, Method 25A, reported as propane. The measurement shall be conducted over at least one 5-minute interval during which the storage vessel is being filled.