New draft guidelines have been released by the U.S. Environmental Protection Agency, addressing 1-hour SO2 National Ambient Air Quality Standards (NAAQS) in relation to State Improvement Plans. On Sept. 21, 2011, draft guidance submissions
became available for public review and comment.
The new draft guidance would supplement earlier EPA guidance for implementation of the 1-hour primary SO2 NAAQS adopted by the agency on June 2, 2010 (the 1-hour standard is 75 parts per billion, based on the three-year average of the 99th percentile of 1-hour daily maximum concentrations). From its preface, it may be inferred that the draft guidance provides a preview of the EPA’s thinking on a projected rulemaking to codify key concepts for implementation of the short-term SO2 NAAQS.
The new draft guidance addresses two types of SIPs:
- SIPs created to maintain those areas that have reached attainment standards
- SIPs aimed at restoring non-attainment areas to attainment standards
Although the Draft Guidance addresses the development of both maintenance SIPs under Section 110(a) of the Clean Air Act (CAA) and SIPs for restoring nonattainment areas to attainment with the new SO2 standard, the main emphasis of the guidance is on maintenance SIPs. This is because EPA anticipates that most areas of the country will initially be designated as “unclassifiable.” That unclassifiable designations are expected to predominate derives from the approach EPA has identified for designations under the short-term SO2 standard which requires dispersion modeling to determine compliance status of more significant SO2 sources and such modeling is not anticipated to be available in time for the June 2012 deadline for initial designations.
To learn more about the specifics behind the proposed elements included in the draft guidance, see this article on our web site.
If you have questions about this or related issues, please contact the Environmental Law Department at Bingham McHale.Go to blog homepage >>