1. BART Update Regional Modelers Workshop March 8-10, 2005

4. Regional Haze Timeline • July 1999 - Regional haze rule finalized • May 2002 - Rule vacated in part, sustained in part • Court objected to inclusion of individual sources based on collective assessment of visibility impacts from all sources • April 2004 - Deadline for Reproposal • April 2005 - Deadline for final action • SIPs due 3 years after designation of PM2.5 attainment and nonattainment areasand in no event later than December 17, 2007

5. Background - What is BART? • CAA: certain large existing sources must establish controls (BART) • BART-Eligible Sources • Major stationary source • 26 categories (same as PSD) • Placed into operation: 1962-1977 • Potential to emit 250 tons of any pollutant reasonably anticipated to contribute to regional haze in any Class I area • Sources which are reasonably anticipated to contribute to regional haze in any Class I area <CALPUFF> • Estimated total number of facilities affected is less than 1000 nationwide, including 302 EGUs.

6. Background - How is BART determined? • For each source, State must consider 5 factors: • Control technology available • Controls already in place at the source • Cost of compliance • Remaining useful life • Energy and nonair environmental impacts • Degree of visibility improvement from use of such technology <CALPUFF>

7. BART Provisions (proposed) • Control Levels for SO2 and NOx from EGUs, • States must require these control levels at >750 MW plants, unless analysis of other BART factors dictate otherwise. • We presume that States should require these control levels at >200 MW units, unless analysis of other BART factors dictates otherwise. • Proposed limits: • SO2 - 95% or 0.1 lb/MMBtu, NOx – 0.2 lb/MMBtu • Note: NOx differences exist for boiler type and coal type (evaluating in final rule) • Regional Haze rule allows trading as alternative to source-by-source BART

8. One major issue with 1999 RH rule – determining visibility impacts • Approach did not account for impacts on haze of individual source controls • Court vacated and remanded cumulative approach and directed us to revise RH rule to allow States to exempt an individual source from BART based on its visibility impacts <CALPUFF> • Revise BART Guidelines to provide methodology for individual source exemptions

9. How would modeling be used to Respond to the Remand? • Source by source analysis – 2 parts • States use CALPUFF (or other approved model) modeling to: • Exempt individual sources or determine they are subject to BART • Compare 24-hour results to a deciview threshold • Show “degree of improvement in visibility” based on controls once they are subject to BART – evaluated as one of five factors in control technology determination • Visibility Metric for modeling: deciview • We acknowledge CALPUFF has flaws – we are addressing in final rule. • Alternatives to CALPUFF (non-modeling)