Standards of Performance for Electric Utility Steam Generating Units for Which Construction Is Commenced After September 18, 1978; Standards of Performance for Industrial-Commercial-Institutional Steam Generating Units; and Standards of Performance for Small Industrial-Commercial-Institutional Steam Generating Units

Pursuant to section 111(b)(1)(B) of the Clean Air Act (CAA), EPA has reviewed the emission standards for nitrogen oxides (NO<INF>X</INF>), sulfur dioxide (SO<INF>2</INF>), and particulate matter (PM) contained in the new source performance standards (NSPS) for electric utility steam generating units and industrial-commercial- institutional steam generating units. EPA proposed amendments to 40 CFR part 60, subparts Da, Db, and Dc, on February 28, 2005. This action reflects EPA's responses to issues raised by commenters, and promulgates the amended standards of performance. The final rule amendments revise the existing standards for PM emissions by reducing the numerical emission limits for both utility and industrial-commercial-institutional steam generating units and revise the existing standards for NO<INF>X</INF> emissions by reducing the numerical emission limits for utility steam generating units. The amendments also revise the standards for SO<INF>2</INF> emissions for both electric utility and industrial-commercial-institutional steam generating units. The numerical standard for electric utility steam generating units has been reduced, and the maximum percent reduction requirement has been increased. A numerical standard has been added for units presently subject to the NSPS and new industrial-commercial- institutional steam generating units, and the maximum percent reduction requirement for new units has been increased. Both utility and industrial steam generating units can either meet a numerical limit or demonstrate a percent reduction. Several technical clarifications and compliance alternatives have been added to the existing provisions of the current rules.