Air Pollutants and Monitoring - Criteria Pollutants
State Implementation Plan (SIP) for Sulfur Dioxide (SO2)
On April 12, 2012, U.S. Environmental Protection Agency (EPA) sent a letter to all states outlining next steps with regard to implementation of the 1-hour SO2 standard.
In the letter, EPA states that they plan to:
- Move forward with the current designations process as soon as possible. Areas that have a violating monitor will be classified "nonattaintment." All other areas will be classified "unclassifiable."
- Initiate stakeholder outreach in the near future to ask for input on monitoring, modeling, and implementation issues, particularly for unclassifiable areas.
- No longer expect Infrastructure SIP submittals (due June 2013) to contain modeling demonstrations showing attainment of the standard in unclassifiable areas.
On October 3, 2011, the EPA published its proposed guidance on its plan for implementing the new 1-hour SO2 National Ambient Air Quality Standard (standard). See EPA's website for more information. On December 2, 2011, DHEC submitted a comment letter to EPA on the proposed guidance.
EPA has chosen to use a hybrid modeling and monitoring approach to show compliance with the 1-hour SO2 standard.
States with areas designated nonattainment in 2012 would need to submit State Implementation Plans (SIPs) to EPA by early 2014 outlining actions that will be taken to meet the standards as expeditiously as possible, but no later than August 2017.
For all other areas, even those designated unclassifiable, states would need to submit to EPA "maintenance" or infrastructure SIPs by June 2013, three years following the promulgation of the new SO2 standard. However, unlike previous infrastructure SIPs, EPA established a new "implementation approach that would look to robust CAA section 110(a)(1) SIPs, which have sometimes been previously referred to as "maintenance" or "infrastructure" SIPs but for the new SO2 NAAQS would serve as substantive "attainment" SIPs" (75 FR 35553). EPA expects these SIPs would:
- Demonstrate, through refined air quality modeling, that all sources contributing to monitored and modeled violations of the new standard, or that have the potential to cause or contribute to a violation, will be sufficiently controlled to ensure timely attainment and maintenance of the SO2 standard;
- Account for SO2 reductions that would result from compliance with national and regional regulations, including emissions controls for electric utilities and industrial boilers; and
- Include as necessary, enforceable emissions limitations, timetables for compliance, and appropriate testing/reporting to assure compliance.
EPA believes that these areas designated unclassifiable should plan to demonstrate attainment and maintenance of the standard as expeditiously as possible, but no later than August 2017, the same date that nonattainment areas must meet the standard.
For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.