Section 65.65 - Monitoring(a) An owner or operator of a Group 2A process vent maintaining a TRE index value greater than 1.0 without a recovery device shall monitor based on the approved plan as specified in § 65.63(d) .(b) As required in § 65.63(a) and (c) , an owner or operator of a Group 2A process vent maintaining a TRE index value greater than 1.0 with a recovery device or a Group 1 process vent shall comply with § 65.142(b) .