Urgent – SO2 Implementation Update

U.S. EPA has recently provided state air quality regulatory agencies with an update of the sulfur dioxide (SO₂) 1-hour National Ambient Air Quality Standard (NAAQS) designation process.  The significant news is that U.S. EPA will no longer require that air dispersion modeling for individual facilities be included in the June 2013 Maintenance State Implementation Plan (SIP) submittal from states.  In its originally recommended form, the dispersion modeling requirement (as articulated in the preamble to the final rule) would have likely resulted in new emission limits for specific emission units at major facilities and would have placed a significant burden on states to complete a very complicated modeling effort.  Now that the dispersion modeling requirement has been removed, the June 2013 Maintenance SIPs will be consistent with plans for previous NAAQS efforts and will likely focus on existing monitoring data only. U.S. EPA has also stated in their update that approval and/or comments on the initial state recommendations will be released soon.

While the dispersion modeling requirement has been tabled relative to the June 2013 deadline, U.S. EPA did not entirely close the door on SO₂ dispersion modeling.  They now intend on coordinating a series of stakeholder workgroup meetings in the near future to solicit comments on the most appropriate way to implement the SO₂ NAAQS and to arrive at designations, particularly for currently unclassifiable areas within which no ambient monitoring data is currently available.  We strongly encourage impacted industries to be involved in the stakeholder meetings.  ALL4 will provide periodic updates related to meeting dates and venues.  More information about U.S. EPA’s SO₂ NAAQS Implementation can be found here.