Response to EPA’s Comments of May 29, 2008

1. Comment: WRAP needs to justify using 0.5 deciviews as a threshold for determining whether sources are subject to BART.

Response: EPA’s BART guidelines state that “As a general matter, any threshold that you use for determining whether a source ‘cont ributes’ to visibility impairment should not be higher than 0.5 deciviews.” The guideline s give states the disc retion to establish a lower threshold “if they concl ude that the location of a la rge number of BART-eligible

sources within the State and in proximity to a Class I area ju stify this approach. When developing the modeling protocols for the visibility analysis, th e four participating states

established the threshold at 0.5 deciviews b ecause it is consistent with EPA guidelines,and is consistent with long-standing visibility modeling practices. Significant BARTeligible sources that are in proximity to Cl ass I areas in the west have been addressed through the reasonably attr ibutable visibility impairment pr ocess, and there is not a large concentration of BART-eligible sources that are in proximity to a Class I area. In addition, the backstop trading program will in clude all sources with emissions over 100 tons/year and will therefore still include sour ces that may not be subject to BART. The guidelines do not require states to establish a lower threshold, and the four participating

states do not believe that a lower threshold is needed or justified.

Language has been added to the Better Than BART demonstration to explain that the 0.5

deciview threshold is consiste nt with EPA’s BART guidelines.

2. Comment: When estimating BART emi ssion reductions WRAP excluded some nonutility sources that it characterizes as potential ly subject to BART and this not consistent with regulatory requirements.

Response: The analysis excluded a small numb er of non-utility sources that in aggregate represent 1% of the regional milestone. EP A has not established a presumptive control

level for these sources and there is little bene fit to doing a case-by-ca se analysis because the results would have a negligible impact on the regional milestone. These sources will

still be included in th e backstop trading program.

3. Comment: When establishing milestones, WRAP used presumptive levels in some cases and source specific information in ot hers. A consistent approach is needed.

Response: The WRAP addressed this issue in the Better Than BA RT demonstration in response to earlier comments from EPA (see the end of Section D, page 7). An alternate analysis was conducted that assumed that all EGUs that were subject to BART (including

units that are smaller than 750 MWs or are al ready operating at greate r than 50% control) would be operating at the presumptive SO 2 emission rate of 0.15 lb/MMBtu. The

estimated SO 2 emission reductions using this simple r approach were 91,872 tons. This is comparable to the estimated reduction of 91,760 that was calculated using the more detailed method. The participating states chose to use the more detailed method because

it was based on the best information that was available rather than relying on theResponse to EPA’s Comments of May 29, 2008 Page 2

presumptive level for all sources. However, the alternate analysis is us eful to show that a simpler consistent approach achieves the same result.

4. Comment: The alternative program must include all BART-eligible sources not just sources that are subject to BART.

Response: As recognized in EPA’s comment s, the alternative pr ogram applies to all

sources with actual emissions greater than 100 tons/year SO 2 and is likely to include all BART-eligible sources. However, to address the possibility that th ere may be an unusual

source that would not be included based on ac tual emissions, each of the participating states will either include langua ge in their backstop trading ru le to ensure that all BARTeligible sources that are BART-eligible due to SO 2 emissions are subject to the backstop trading program, or will include an analysis in their SIP that demonstrates that all BARTeligible sources meet the 100-ton SO 2 threshold.

5. Comment: The alternative program does not directly address the distribution of

emissions. At a minimum the SIP should in clude a determination, supported by a clear weight of evidence that Section 309 achieves greater reasonable progress than would be achieved through the installation and operation of BART.

Response: The WRAP conducted modeling th at compared command and control BART to a trading program during the development of the Annex. A new Section H has been

added to the end of the Better Than BART dem onstration to reference the results of that analysis that was submitted to EPA in 2000.