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EPA Finalizes Reconsideration of New Source Mercury and Air Toxic Standards for Utilities


On April 24, 2013, EPA published a Final Rule regarding reconsideration of the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for coal- and oil-fired electric utility steam generating units referred to as the Mercury and Air Toxics Standards (MATS) and the New Source Performance Standards Rule, referred to as the Utility NSPS.  The MATS and Utility NSPS rulemakings were published in the Federal Register on February 16, 2012, after which EPA received 20 petitions for reconsideration of the MATS and four petitions for reconsideration of the Utility NSPS.  As reported in the first quarter 2013 Air Quality Letter, EPA published its proposed reconsideration of certain aspects of MATS and the Utility NSPS on November 30, 2012. 

Consistent with the November 30, 2012 proposal, EPA has finalized new source numerical limits for hydrogen chloride, filterable particulate matter (PM), sulfur dioxide, lead, and selenium emission for all new coal-fired electric generating units (EGUs).  EPA has also finalized reconsidered mercury limits for those units designated for coal in the greater than or equal to 8300 btu/lb subcategory.  EPA raised these limits for new sources as a result of information received regarding the variability of the best performing EGUs and to more accurately reflect the capabilities of emission control equipment for new EGUs.  The final reconsideration rule maintained the source trigger date for MATS as May 3, 2011 and new sources were to have complied with the revised MATS emissions standards by April 24, 2013 or upon startup, whichever is later.  The reconsideration does not affect MATS emissions standards for existing units.

The February 16, 2012 rule provided new sources with the option of monitoring for filterable PM through quarterly stack testing as well as continuous emissions monitoring systems (CEMS) or continuous parameter monitoring systems (CPMS).  However, the proposed reconsideration sought comment on whether to retain the quarterly stack testing compliance option for new EGUs.  In the final reconsideration, EPA did not retain the quarterly filterable PM performance testing option for new sources, stating that “new EGUs can be designed to incorporate PM CEMS or PM CPMS from the outset, without being impeded by retrofit location installation constraints that could impact existing EGUs.”  New sources will now utilize PM CEMS or PM CPMS to demonstrate compliance.  For PM CPMS, EPA finalized the approach to be used in setting an operating limit based on emissions testing and the requirement for emissions testing after an exceedance to verify or readjust the operating limit.  Further, EPA finalized a rebuttable presumption of violation when PM CPMS exceedances lead to more than four required emissions tests in a rolling 12-month period. 

EPA originally stated it would reconsider the requirements applicable during periods of startup and shutdown for MATS and the startup and shutdown provisions related to the PM standard in the Utility NSPS.  The April 24, 2013 final reconsideration did not address the issues related to startup and shutdown.  Instead, on June 25, 2013, EPA reopened the public comment period to solicit additional input on issues raised during the initial public comment period related to the requirements and definitions for periods of startup and shutdown.  Industry data and information regarding EGU’s startup and shutdown raised several significant issues regarding the definition of startup, the types of clean fuels used during startup, calculation of non-mercury emissions during startup and shutdown and use of a default diluent cap and a default electrical production rate, and compliance demonstration during startup and shutdown for EGUs that share a common stack.  EPA is soliciting comments concerning these issues as well as comments regarding an additional technical analysis conducted by EPA in response to comments concerning the end of startup.  Comments are due by August 26, 2013.

To view a complete PDF of the Second Quarter 2013 issue of the Air Quality Letter, click HERE.

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