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May 28, 2014
Opacity procedure issued for new sources

Beginning November 12, 2014, owners and operators (O/O) of facilities subject to the Clean Air Act’s Section 111 New Source Performance Standards (NSPS) must comply with EPA’s recently issued quality assurance and quality control (QA/QC) rule for continuous opacity monitoring systems (COMS). 

According to the Agency, the rule’s requirements—referred to as Procedure 3—are modeled after manufacturers’ maintenance recommendations.  The EPA therefore believes that most, if not all, O/Os are already following procedures similar to those specified in Procedure 3.

Procedure 3 establishes requirements for daily instrument zero and upscale drift checks, daily status indicator checks, quarterly performance audits, and annual zero alignments and requires source O/Os to have a corrective action plan in place for malfunctioning COMS.  In addition, Performance Specification 1 (the initial certification for COMS) provides requirements for the design, performance, and installation of a COMS and data computation procedures for evaluating the acceptability of a COMS.

Changes to proposal

In February 2012, the EPA issued Procedure 3 as a direct final rule accompanied by a proposal.  Because of adverse comments on the proposal, the direct final rule was withdrawn.  In the current action, the Agency addresses several of the comments that resulted in the withdrawal.  Specifically:

  • The EPA clarified that Procedure 3 applies to COMS used to demonstrate continuous compliance with opacity standards in NSPSs only.
  • In response to requests for more time to train operators, the EPA replaced the 60-day compliance deadline with 180 days of lead time.
  • The temporal definitions for daily, quarterly, and annual audits were revised because some units do not operate 24 hours a day, 7 days a week.
  • The EPA agreed with commenters who pointed out that a fault status indicator warning may mean that opacity readings are nearing the limit and that the data are not necessarily invalid.  Therefore, language that indicated the data would be considered invalid has been removed.

COMS must be detached

Several commenters also requested that the Agency delete the requirement to remove the COMS to conduct zero alignment audits, claiming that removing the COMS from the stack exposes it to potential damage and presents a safety hazard.  The EPA responded that it believes that the zero alignment audit needs to be done off-stack annually unless a source O/O chooses the alternative that allows the installation of an external zero device that allows COMS removal from the stack every 3 years.  

Also, based on conversations with manufacturers, the EPA says it believes that the risk of damage when removing the COMS from the stack is minimal.  Therefore, the requirement to remove the COMS to conduct zero alignment audits was finalized as proposed.

The final Procedure 3 rule was published in the May 16, 2014, FR.

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