Commenters ( 0214, 0215, 0238, 0254) said EPA fails to make clear how the proposed default values for SO 2 and NO x relate to visibility impairment. Visibility is both Class I area and source specific, which is the reason Congress gave the states the lead role and discretion in the BART program to determine which sources need to install or upgrade controls. Through the use of presumptions and default values, however, EPA's prescriptive process, as proposed, would make the installation of maximum controls more likely without regard to visibility benefits. Instead, as required by statute and rules, EPA should give the states maximum flexibility to use the five statutory factors in their BART determinations. Commenters ( 0228, 0247) said sources must be allowed to assess the visibility improvements of a variety of control options. Commenter 0308 said states should be allowed to exempt BART eligible sources from BART requirements if these sources do not impact or have very little impact on visibility in a Class I area.

Commenter 28 342 said even if a presumption were appropriate under the visibility protection program ( and it is not), EPA cannot adopt one now because the Agency has not satisfied the conditions for creating a presumption. Federal presumptions can be promulgated only when the Agency has established ( based on generic application of law to fact) that the presumption is valid.

Response: 222 See the preamble.

Comment: Commenters ( 0208, 0270) said EPA's default and presumptive control levels for SO 2 and NO x are inconsistent with the BART control efficiencies proposed by the WRAP and should be removed from the proposed guidelines. In no event, however, should BART force plants in the West to reduce emissions to levels greater than achievable using dry scrubbing technology for SO 2 and advanced low NO x combustion technology for NO x. As EPA has pointed out in its discussion of Clear Skies and CAIR, wet scrubbers and SCR are inappropriate for the arid West. In fact, the statute itself makes the NSPS a ceiling for BART. Commenter 0270 said the proposed presumptive BART emission limitations are inconsistent with the Regional Haze Rule for the GCVTC states ( WRAP Annex and SIPs under 40 CFR 51.309), the Administration's proposed legislation for the power generation sector, the CSA, and the proposed IAQR.

Response: See the preamble and TSDs for discussion of specific SO2 and NOx limits. In addition, we do not believe the BART presumptive limits are inconsistent with other EPA rules or with the proposed Clear Skies legislation. The preamble contains a discussion of the relationship between BART and the final CAIR rule ( which was proposed as the IAQR).

Comment: Commenters ( 0184) said limits should not be set for those pollutants for which a facility has no known control.

Response: We agree.

Comment: Commenter 0246 said EPA should clarify that greater reasonable progress need not be demonstrated by achieving emission reductions greater than those that would occur by applying the presumptive control levels proposed by EPA to all BART eligible sources. Such an approach would undermine the fundamental role of the states in determining BART or what constitutes greater reasonable progress than BART. The WRAP, states, tribes and stakeholders conducted a thorough analysis and balancing of the BART factors to arrive at the WRAP milestones   all of this was conducted without imposing presumptive control levels during the analysis and discussion.

If EPA does utilize the presumptive emission limits, commenter 0197 said , if a source agrees to 95% control or the range of 0.1 0.15 lb/ MMBTU for SO 2, they should be automatically exempt from the BART process. The same goes for the 0.2 lb/ MMBtu for NOx.

Response: Reasonable progress toward visibility goals are to be assessed in the regional haze State implementation plan ( SIP) under the regional haze rule. In addition, the CAA requires BART determinations on specific sources in regional haze SIPs. These are separate processes that the 223 State must conduct and evaluate taking into account regional visibility conditions; BART may be just one component of a regional haze SIP. In addition, the WRAP milestones were developed under a separate process from source specific BART; the relationship between the WRAP milestones under section 309 of the regional haze rule with reasonable progress is different from the relationship of source specific BART under section 308 of the regional haze rule.

In regard to commenter 197, see the preamble for discussion of BART determinations for sources meeting the presumptive limits.

Comment: Commenter 0268 questioned the legal authority of EPA to impose presumptive limits for sources between 250 MW and 750 MW in size because the visibility provisions of the Act only specify evaluation by the states of units with a capacity in excess of 750 MW. Commenter 0184 said the statute requires state to take a case by case approach for non EGU sources. Discussion of such emission limits should be explicitly limited to those large EGU facilities for which EPA has the statutory authority to define BART and to set such limits. Commenter 0237 said the presumptive BART level for utility boilers would impose hardship on industrial sources because there are many practical differences in the way industrial boilers and electrical generating units are operated, including short term swings in demand, that make such BART controls unreasonable. Therefore, EPA must underscore in its final guideline that these control levels are not presumptive BART for industrial boilers.

Five commenters said EPA should consider the type of emission unit ( e. g., coal type, boiler type, and/ or emission controls) when making BART determinations ( 0195, 0198, 0214, 0238). Commenters ( 0214, 0238) added that states and sources should be focusing on the incremental costs and benefits from the installation of additional controls or the upgrading of existing controls in the BART determination.

Response: We agree that presumptive limits do not apply to industrial boilers. States have discretion to assess the BART factors and apply appropriate limits to these and other non EGU sources. See the preamble for discussion of our legal authority to set presumptive limits for certain EGUs. We agree that coal type, boiler type and/ or emission controls should be considered, and the preamble discusses how the presumptive limits have considered them.

Comment: Two commenters supported the use of optional presumptive limits as a choice for source owners/ operators to avoid a BART analysis ( 0210, 0256). This approach would limit the resources expended for many determinations, but would allow states to consider all of the statutory factors where appropriate.

Response: We believe States have the discretion they need to assess the BART factors. See the preamble. 224 Comment: Six commenters said EPA needed to address the averaging period associated with the presumptive limits ( 0195, 0227, 0228, 0268, 0306, 0323). Some commenters suggested annual average limits ( 0195, 0268) while others said they should be no less than a 30 day or monthly average ( 0228). Other commenters asked EPA to specify an averaging time similar to the averaging time of visibility impact assessments, e. g., 24 hour average ( 0227, 0306).

Response: We agree, and have specified a 30 day rolling average in the final Guidelines.

Comment: One commenter said EPA should establish emission limits for PM because of the magnitude of emissions and the availability of proven controls ( 0255).

Response: We agree that controls are readily available to address PM emissions, and we encourage States to strongly consider those controls and set limits appropriate to each source subject to BART.

Comment: Seven commenters made other general comments regarding presumptive emission limits ( 0195, 0214, 0232, 0238, 0255, 0299, 0306).

Commenters ( 0195, 0214, 0238) said exceptions should be made for startups, shutdowns and malfunctions of control equipment.

Response: States have discretion to appropriately address startup, shutdowns and malfunctions of control equipment in Title V permits.

Comment: Commenters ( 0214, 0238) said EPA should make it clear that if any source is willing to achieve 95% control or somewhere along the scale of 0.1 to 0.15 lb/ MMBTU, it should automatically be exempt from the requirement to perform a BART analysis for SO 2. The same should also be true regarding a BART NO x analysis for sources willing to achieve the 0.2 lb/ MMBTU NO x x presumption for EGUs. Such presumptions would streamline the BART process for those sources willing to reach these control levels. Commenter 0255 said EPA should set a high threshold for sources to justify being exempted because the current suite of best available technologies can readily meet and go beyond the mandated limits. EPA should encourage the states to consider these factors as well.

Response: See the preamble. 225 Comment: Commenter 0232 said there should be a provision to revisit appropriate BART control levels at a date certain. While it is appropriate to provide clarity and certainty to industry for the installation of retrofit controls, it is also important to provide for application of new controls with increased control efficiency due to technology improvements in order to meet the express requirements of the Act to prevent any future and remedy any current impairment of visibility in Class I areas.

Response: Under the CAA, BART is specifically an element of the first regional haze SIP.

Comment: Commenter 0255 noted that EPA did not address emission of SO 3 from power plants. This has become an increase area of concern for power companies as states have set emission standards for SO 3 in the operating permits for power plants. A number of control technologies have been developed to address this pollutant and are able to achieve a high level of removal.

Response: States have discretion to address pollutants under BART to the extent that they are visibility impairing.

Comment: Commenter 0299 said the BART presumptive level of control proposed for EGUs boilers for SO 2 emissions and for NO x emissions should be made consistent with other clean air programs. Specifically, the presumptive level of controls for EGU boilers should be consistent with the requirements adopted in the CAIR, and consistent with the requirements contained in the federal NO x SIP Call.

Response: See the preamble for a discussion of the relationship of BART requirements and CAIR requirements. In addition, BART is consistent with the NOx SIP Call; for EGUs required to install SCR under the NOx SIP Call, the BART presumption is simply that those sources should run the SCRs year round.

Comment: Commenter 0306 said BART should be no more stringent than a current BACT assessment for an existing facility. EPA should define presumptive BART in a manner consistent with recent NSR enforcement actions. Presumptive BART should not be more stringent than requirements in recent agreements ( or proposed agreements) that settled NSR violations.

Response: BART is determined under a separate process from specific NSR settlement agreements. 226 <IP_ADDRESS> NOx Limits for Utility Boilers Comment: Eighteen commenters on the 2001 notice supported presumptive limits for NOx set at 90 to 95% ( 28 245, 28 247, 28 248, 28 255, 28 260, 28 262, 28 302, 28 325, 28 334, 28 338, 28 350, 28 352, 28 358, 28 362, 28 390, 28 399, 28 433, 28 7016). Commenter 28 302 said the combination of low NOx burner ( LNB) technology and SCR controls can routinely reduce NOx emissions by over 90% and other commenters cited research documenting the performance of controls ( 28 325, 28 390) and EPA's own experience and data ( 28 28 352, 28 362, 28 7016).

Response: EPA is finalizing presumptive Nox limits for some boiler types based on using SCRs with 90% reduction efficiency. See preamble.

Comment: Commenter 28 256 said if a presumptive norm approach is used, then the presumptive norms should be explicitly stated in the rulemaking and should be no higher than 1.5 lb/ MWh for NOx..

Response: EPA has explicitly stated its presumptive Nox limits for coal fired EGUs in the rulemaking. The presumptive Nox limits EPA is finalizing vary by unit type and coal type. For tangentially fired boilers burning sub bituminous coal, EPA is finalizing a presumptive Nox limit of 0.15 lb/ mmbtu as this commenter suggests. For other boiler and coal types, EPA's final presumptive Nox limits are higher than 0.15 lb/ mmbtu. See preamble for discussion of the rationale EPA used for setting presumptive Nox limits.

Comment: Two commenters supported the proposed NOx limit of 0.2 as a reasonable level of control ( 0231, 0302). Commenter 0232 supported the setting the presumptive control levels of NOx at 90%. Three commenters said the proposed levels are too stringent ( 0171, 0207, 0227). Commenter 0171 described recent plant retrofits using low NOx burners and low NOx concentric firing systems that could not practically achieve the 0.2 lb/ MMBTU limit. Commenter 0207 said the presumptive limit is counter to available evidence and unreasonable, especially for T fired units equipped with low NOx burners. EPA's experience in the Acid Rain program is consistent with a higher emission rate and should be reflected in setting the BART levels. The commenter concluded that the experience of some of its members with low NOx burners, the background information for development of Group 1, Phase II NOx limits, and, most likely, the voluminous NOx emission data reported to EPA from all Phase I and Phase II units, all demonstrate that a presumptive 0.2 lb/ MMBTU NOx emission limit for utility boilers is a very unreasonable, representation of BART for such units. Commenter 0227 was concerned that the NOx 227 presumptive control level EPA proposed is higher than the level current technology can provide. EPA should review currently proposed NOx retrofits and consider lowering it presumptive level of 0.2 lbs/ MMBTU.

Three commenters said the proposed NOx levels are too lenient ( 0167, 0255, 0271). Commenter 0167 urged EPA to require electric generating units in the West to meet rigorous NOx pollution control standards. Commenter 0255 said the current suite of best available NOx technologies, post combustion as well as combustion controls, can achieve significantly lower emission rates than the proposed 0.2 lb/ MMBtu. In 2002 ozone season, the air pollution control industry had 100 units achieving a NOx emission rate of less than 0.2 lb/ MMBtu. Commenter 0271 recommended the presumptive control level of 0.15 lbs. of NOx per MMBTU. This level of control has been demonstrated in the NOx budget program in the eastern United States.

Response: In response to comments, EPA has revised its proposed Nox presumptive limit and has set final presumptive limits based on a thorough unit by unit analysis of BART eligible EGUs and what each unit would be capable of achieving with current combustion control technology. EPA's final presumptive Nox limits for coal fired EGUs are established by unit type and coal type to more accurately reflect the capability of each BART eligible EGU. See preamble for further discussion.

Comment: Six commenters said that the presumption is overly broad ( 0189, 0206, 0217, 0246, 0303, 0323). Other commenters ( 0206, 0303) said EPA should not establish a prescribed method of level of control because variations between small and large facilities, e. g., between coal, oil, and gas fired units, and the age of the units make application of such a presumption overbroad. Commenters ( 0217, 0246) also said they disagreed with the presumptive NOx limit at 0.27 lb/ MMBTU because of the many differences in coal fired boilers. Commenter 0323 said EPA should consider a range of emission rates that reflect recent advances in technology, particularly with respect to tangentially fired boilers at EGUs.

Three commenters said EPA's characterization of the capabilities of control technology is inaccurate. Commenters ( 0217, 0268) provided results of a survey showing the effect of adding advance combustion controls to existing units that currently do not have the most advanced controls. Expected NOx emissions rates ranged from 0.17 to 0.49 lbs/ MMBTU. The average emissions rate achievable, weighted by heat input, was 0.27 lbs/ MMBtu, well in excess of the presumed limit of 0.2 lbs/ MMBTU. In contrast, commenter 0255 described the effectiveness of SNCR as a candidate to meet or better the proposed emission rates.

Response: See preamble. EPA's analysis for the final BART rulemaking did include analysis of advanced combustion controls. 228 Comment: Thirteen commenters said it is important to consider the type of coal or other fuel in setting a presumptive control level ( 0186, 0188, 0213, 0214, 0217, 0224, 0238, 0254, 0255, 0275, 0306, 0319, 0321).

Response: See preamble.

Comment: Commenters ( 0186, 0275) said the 0.2 lb/ MMBTU presumptive level of NOx control should not apply to gas fired power plant boilers because combustion controls on gas fired units can achieve a much better ( i. e., lower) level of performance.

Response: The presumptive limits EPA is setting only apply to coal fired EGUs that are BART eligible. See preamble.

Comment: Some commenters have argued that SCR technology is not feasible for application on lignite fired boilers. These commenters indicated that SCR had not been demonstrated to effectively control NOx emissions from lignite fired boilers. They also cited experience from an SCR pilot test on a slipstream from a boiler firing lignite which showed a problem with the blinding of the SCR catalyst. This catalyst fouling was believed to be caused by sulfates of calcium and sodium present in the flue gas generated from the firing of lignite.

Other commenters ( 0188, 0214, 0238, 0319, 0321) said that the 0.2lb/ MMBTU level of control has not been demonstrated using SCR technology on lignite fired EGUs and cited current research supporting this claim ( 0188, 0321). Commenter 0238 added that over fired air will not reduce NOx emissions from cyclones to that level. Commenter 0321 said the proposed emission limit is not appropriate for lignite fired cyclone units either. Commenter 0306 said EPA should reexamine the presumptive BART for cyclone boilers firing North Dakota lignite.

Response:

EPA assumed the use of SCR in setting presumptive Nox limits for coal fired cyclone units. See preamble. Based on the investigations conducted by the Agency, there is considerable experience in the industry to show that use of SCR on lignite fired boilers is technically feasible. A slipstream 18 Impacts of Texas Lignite Coal on SCR Catalyst Life and Performance: Field Data from TXU's Martin Lake Plant," EPRI Website, www. epri. com, accessed on December 11, 2003 ( docket no. OAR 2003 0053 1944)

19 Email from J. Staudt to S. Khan, Lignite Installation List, July 5, 2004 ( docket no. OAR 2003 0053 1946)

20 Email from J. Staudt to S. Khan, Response to Comments  IAQR, July 2, 2004 ( docket no. OAR 2003 0053 1945)

21 Email from J. Staudt to S. Khan, SCR on ND Lignite, August 20, 2004 ( docket no. OAR 2003 0053 1947)

229 SCR test conducted by EPRI at the 750 MW Martin Lake Plant in Texas has shown acceptable results from Texas Lignite. 18 Furthermore, one technology supplier reports that SCR has been successfully used on lignite and brown coal boilers in Europe. 19 The SCR catalyst suppliers have also indicated that they will offer performance guarantees for SCR applications on lignite fired boilers in the U. S. 20 These suppliers believe that the overall SCR experience from facilities firing different types of coals is applicable to the lignite fired facilities. Therefore, the Agency believes that application of the SCR technology on lignite boilers in the U. S. is technically feasible.

The EPA also notes that the commenters have not provided any details of the pilot test that has been mentioned with regards to the blinding of a catalyst from North Dakota lignite generated flue gases. Without this information, this part of the comment cannot be addressed properly. The EPA's own investigations show that the main reason for this problem was ash build up on the catalyst, which is a problem commonly experienced in pilot test facilities. 21 In the full scale installations, this concern is addressed during the SCR design stage. The methods used to avoid this problem include duct design to promote ash fallout prior to the SCR, catalyst reactor design to avoid ash build up, and on line cleaning methods ( sootblowers and sonic horns).

Comment: Commenter 0217 said coal rank also accounts for differences in NOx levels. For example, subbituminous coal from the Powder River Basin has been shown to yield lower NOx in some units than other coals. However, this is not always true. In addition, unit operators must balance oxygen levels to attain proper NOx levels while still maintaining appropriate carbon monoxide ( CO) levels. A unit with a stringent CO emission limit may not allow a plant operator to achieve the lowest NOx level possible with existing controls.

Response: In response to comments, EPA revised its proposed approach for setting presumptive Nox limits and is finalizing presumptive limits based on unit and coal type. If a particular unit is unable to meet the presumptive limits, the State may consider several factors in determining whether the 230 source must meet the presumptive limit. Limitations such as the one this commenter suggests could be one of the factors States consider.

Comment: Commenter 0213 said that cyclone boilers that burn bituminous coal may require a higher presumptive emission rate even after OFA retrofits. Commenter 0254 said pre NSPS boilers firing bituminous coal cannot meet the presumptive limit with the prescribed control systems ( combustion controls or low NOx burners). Commenter 0224 described different levels of performance between Western plants ( which could meet the limit) and Eastern plants ( which could not meet the limit). The commenter said any presumptive performance limits must reflect different types of coal and boiler configurations. Commenter 0255 said the emission rate achieved from a particular unit depends on several factors, including coal type and boiler configuration. The commenter described several examples of high performing units.

Response: EPA used SCR in setting presumptive Nox limits for coal fired cyclone units. See preamble. Also see preamble for discussion of how EPA set presumptive limits by unit and coal type.

Comment: The proposed presumptive NOx emission level is not consistent with the Bush Administration's publicly announced policy of " no SCR in the West" under the CSA. EPA should conclude that application of combustion based controls would constitute BART for NOx emissions in the West, irrespective of the resulting emission level.

Response: EPA has used combustion controls for setting presumptive BART Nox limits except for one boiler type ( cyclones). See preamble for discussion of why EPA used SCR on cyclone units.

Comment: Seven commenters said that the boiler configuration should be considered ( 0195, 0210, 0217, 0224, 0241, 0256, 0270). Commenters ( 0210) said, if retained, the NOx presumption should be modified to address the appropriate control levels for all boiler types. EPA's identified presumptive level, 0.2 lbs/ MMBTU, is not reasonable for most boiler types because it cannot be achieved without using combustion controls ( 0241, 0256, 0270). EPA could establish more reasonable levels by reviewing the emissions data readily available from the Acid Rain program ( 0210). Commenter 0195 said NOx control on cyclone type boilers represent unique circumstances that make it virtually improbable to control on a long term basis below 0.4 lb/ MMBTU.

Response: 231 See preamble. EPA reviewed data available from the Acid Rain program as well as the NOx SIP Call to determine presumptive Nox limits. EPA used SCR in setting presumptive limits for cyclone units. See preamble for further discussion.

Comment: Commenter 0270 said it is well known that wall fired boilers can't achieve the same level of NOx controls as tangentially fired boilers with these types of control technologies. The commenter does not believe that a limit of 0.2 lbs/ MMBTU can be achieved on wall fired units via retrofit installation of advance combustion controls.

Response: In response to comments, EPA revised its approach for setting presumptive Nox limits for coal fired EGUs. See preamble.

Comment: Commenter 0195 supported the definitions for Combustion controls as defined in 40 CFR 76.2 Acid Rain Nitrogen Oxides Emission Reduction Program in order to provide consistency across EPA programs.

Response: EPA's analysis assumed current combustion control technology means low Nox burners, over fire air, and coal reburning. See preamble. This is very similar to the definition of combustion controls in 40 CFR 76.2.

Comment: Commenters supported the presumption that BART can be achieved without the use of post combustion controls ( 0199). However some types of units or units burning some types of fuel cannot meet the presumptive limits without installing controls ( 0199, 0217, 0244, 0252, 0253). Commenters described several examples.

Response: In response to comments, EPA has revised its proposed approach for setting presumptive NOx limits and is finalizing an approach for setting presumptive NOx limits that reflects differences in boiler type and coal type. See preamble. The presumptive NOx limits EPA is finalizing do not assume that all BART eligible units can meet the presumptive NOx limits. See preamble. EPA's analysis shows that most units that cannot meet the final presumptive NOx limits could meet the presumptive limits using advanced combustion controls. Furthermore, the State may consider the appropriate BART factors in deciding what NOx limits a particular BART eligible unit must meet. 232 Comment: Commenters ( 0206, 0303) said the costs associated with SCR operations at coal fired power plants are not insignificant. Annual operation, rather than only during ozone season, would significantly reduce catalyst life, requiring more frequent replacement.

Response: EPA estimated the costs of operating SCRs installed at existing BART eligible coal fired EGUs an additional seven months each year, i. e., year round operation as opposed to operation during the five month ozone season only. The average cost of operating existing SCRs year round is approximately $ 170/ ton. EPA considers $ 170/ ton to be highly cost effective reductions and therefore is requiring units with existing SCRs to operate year round to comply with BART. See excel spreadsheet in the docket entitled " Estimated cost of operating existing SCRs and SNCRs on coal fired BART eligible EGUs year round as opposed to during ozone season only."

Comment: Commenters agreed that low NOx burners should be the presumptive technology because they are cost effective and the incremental cost of adding SCR or SNCR would be substantially less cost effective ( 0224).

Response: See preamble for a discussion of why EPA used SCR for cyclone units. EPA used current combustion controls for all other boiler types in setting presumptive limits.

Comment: Commenter 0255 said post combustion controls ( e. g. SCR and SNCR) as well as advanced ( or second generation) low NOx burners are significantly more efficient and are currently the best available control technologies for NOx. The majority of the low NOx burners currently on coal fired units were installed to meet the compliance deadline for the start of Phase I and II of the Acid Rain Program in 1995 and 2000, respectively. Units that installed their low NOx burners for Phase I of the Acid Rain Program will have had their air pollution control equipment in place for almost 20 years by the time the BART rule is implemented in 2013. Even the units that installed low NOx burners by 2000 will have had their equipment in place for over 10 years by 2013. Exemptions for existing low NOx burner equipment that is not meeting the 0.2 lb/ MMBtu emission rate should not be given as technology performance has significantly improved since 1995 and will continue to improve out to 2013. For these reasons, EPA should remove the provision that permits sources with first generation low NOx burners presumptive NOx emission rate and mandate that BART eligible sources meet the 0.2 lb/ MMBTU or lower emission rate. Commenter 0255 also provided information showing that good performance of SCR on lignite burning units.

Response: 233 EPA's analysis assumed units that installed combustion controls ( low NOx burners and/ or over fire air) prior to 1997 would have to replace their existing combustion controls with current combustion control technology. See preamble and Technical Support Documents referenced in the preamble for further discussion. Combustion controls installed in 1997 or later were considered current combustion control technology and therefore were not replaced. EPA chose 1997 as the cutoff because EPA believes it is reasonable to assume that the generation of combustion controls developed for the Acid Rain program NOx requirements became widely operational by 1997. EPA considered a later cutoff date but chose 1997 in order to be conservative and minimize the number of units that may have to replace existing combustion controls.

Comment: Some commenters approved of including year round SCR operation for removal of NOx ( 0179, 0221, 0232, 0234, 0271). Commenters ( 0232, 0234) would limit this application to sources already operating SCR. Commenter 0221 described how the technology has advanced, is cost effective, and will meet levels of 0.15 lb/ MMBTU ( NOx SIP call) to 0.125 ( IAQR/ CAIR) at costs estimated by EPA to be less than $ 2,000/ ton. The commenter said that SCR represents the best available technology for removal of NOx. Commenter 0232 said a greater control efficiency is possible for these sources.

Response: EPA agrees and is establishing year round operation of SCR or SNCR as BART for units with existing SCR or SNCR. See preamble.

Comment: Commenter 0267 said the NOx level should be lowered to require application of post combustion controls. At a minimum, application of post combustion controls for NOx should not be ruled out as BART. Commenter 0280 agreed and said the presumptive NOx level of 0.2 lbs/ MMBTU should be considered as the maximum, not minimum, allowable emission. States should require the lowest emission rate that can be achieved using all available and applicable control technologies as in BACT. The economic feasibility should be the limiting criteria.

Response: EPA has used SCR in setting presumptive limits for cyclone units. See preamble. For all other unit types, EPA has used current combustion control technology for setting presumptive NOx limits. EPA used cost effectiveness as a guide in determining whether to use SCR or current combustion control technology in setting presumptive limits. See preamble.

Comment: Commenter 0256 said if EPA does retain the presumptions, at a minimum, the presumptions should not apply to units that already are controlled with, for SO2, scrubbers, and, 234 for NOx, combustion controls that were added after enactment of Title IV of the Act. Units with combustion controls that were added after enactment of Title IV should be deemed to already have the best combustion controls available, and thus should not be subject to the presumption. Again, the state should be allowed to analyze BART for those units applying the statutory factors in light of the relatively recent NOx controls that were retrofit at the unit.

Response: EPA's analysis assumed units that installed combustion controls ( low NOx burners and/ or over fire air) prior to 1997 would have to replace their existing combustion controls with current combustion control technology. See preamble and Technical Support Documents referenced in the preamble for further discussion. Combustion controls installed in 1997 or later were considered current combustion control technology and therefore were not replaced. EPA chose 1997 as the cutoff because EPA believes it is reasonable to assume that the generation of combustion controls developed for the Acid Rain program NOx requirements became widely operational by 1997. EPA considered a later cutoff date but chose 1997 in order to be conservative and minimize the number of units that may have to replace existing combustion controls.

Comment: Commenter 0221 said that because power plants account for about one quarter of the nitrogen oxide emissions nationally, and because the Agency also has and will have considerable " experience in evaluating NOx control options for utility boilers," a presumptive control level for NOx should be presumed as " best available" at the outset of the required top down BART analysis for both controlled and uncontrolled power plants. In order to provide support for such a presumption, EPA should undertake a similar analysis of NOx removal technologies as was done by ORD for sulfur dioxide.

Response: EPA has completed a similar analysis of NOx removal technologies. See Technical Support Document entitled " Methodology for Developing BART NOx Presumptive Limits," footnotes 1 and 2.

Comment: Commenter 0255 provided data on 100 coal fired units and the majority are very high performing. The incentive to control emissions under the NOx SIP Call will become stronger over time, assuming electric demand continues to grow, as sources utilize their banked emissions. As the bank of emission credits is reduced, additional NOx reductions will be required. Some sources will be required to install control technologies while those with controls will have an incentive to operate their control technologies at their highest efficiency so they can sell the emission credits that they offset.

Response: 235 EPA's analysis included all BART eligible coal fired EGUs that EPA could identify ( 491 total coal fired EGUs). See preamble and Technical Support Documents referenced in the preamble for further discussion. EPA used its analysis in setting presumptive NOx limits for coal fired units greater than 200 MW at plants in excess of 750 MW. In setting presumptive limits, it was necessary to consider all BART eligible coal fired EGUs. The list of 100 coal fired units the commenter references is not as inclusive as the population of units EPA used in setting presumptive NOx limits. See preamble for further discussion.

Comment: Commenter 0314 expects continuing technological improvement in the future and that a specific presumptive BART level set by rule, will make it difficult for a state to establish a lower level. As proposed for SO2, the commenter suggested a range for NOx that will account for the variability in the boilers as well as technology improvements in the future. A range of 0.13 to 0.17 lb/ MMBTU was suggested.

Response: EPA acknowledges the likelihood of future improvements in NOx control technology. EPA considered both current and advanced combustion control technology in setting presumptive NOx limits for coal fired EGUs and, in response to comments, revised its proposed approach for setting presumptive limits and is finalizing an approach that recognizes the differences in boiler type and coal type in setting presumptive limits. States have flexibility to impose limits more stringent than the presumptive limits EPA is finalizing should the State determine that EPA's presumptive limits no longer reflect current combustion control technology, or if the State determines a more stringent limit is required at a particular source.

Comment: Additionally, cost effective emission reductions from the industrial sector are feasible but have not been adequately considered in the BART rule considering the quantity of visibility impairing emissions. For industrial sources, setting an appropriate level of reduction with some flexibility such as providing the option of meeting an emission rate limit or percent reduction is one way to assure significant emission reductions.

Response: We agree and believe we have done this.

Comment: Commenters ( 0189) said that EPA should make clear ( a) that add on NOx controls should not be part of BART for non EGUs because of the costs of the these controls and ( b) that its presumptive control level of .2 lbs/ MMBTU does not apply to non EGUs because they are unable to meet these levels without the use of add on controls. 236 Response: See the preamble.

Comment: BART determinations should be made by individual states on a case by case basis, consistent with state discretion.

Response: We agree. See the preamble.

Comment: Commenters ( 0214, 0238) added that EPA should give the states maximum flexibility to use the five statutory factors in their BART NOx determinations.

Response: See the preamble. We believe these limits are reasonable and that States have discretion to make different determinations, if warranted based on the BART factors.

Comment: Commenter 0321 added that NOx emissions from lignite unite appear to have less impact on visibility in that region of the country.

Response: If States find that specific plants in specific locations have minimial effect on visibility impairment, they have discretion as to the appropriate BART determination.

Comment: Commenters ( 0319, 0321) supported a recommendation for a NOx limit of approximately 0.4 lb/ MMBTU, or evaluated on a case by case basis.

Response: See the preamble.

Comment: Commenter 0252 analyzed data for eastern units and western units with different configurations and for units burning different types of coal. The commenter concluded that EPA should not set a presumptive level of control, since it should be determined on a case by case basis.

Response: 237 See the preamble and technical support document.

Comment: Some commenters were concerned that the proposed rule would require some plants to install SCR to meet the NOx control level proposed ( 0171, 0206, 0217). Commenter 0171 said the implementation of the regional haze rule, including any potential retrofit of SCR technology, must consider the site specific data of the Class I area, the use of current emission controls on potential sources, and the degree of visibility improvements. Commenters ( 0217, 0246) added that individual EGU differences need to be accounted for by states in making their BART determination. Also, the guidelines indicate that if a state finds that a source's visibility contribution warrants the installation of SCR, it may be allowed. However, the guidelines need to also provide for instances where the visibility condition warrant a lesser control level than what would be achieved by advanced combustion control. There is reference to this concept in the preamble that is not reflected in the guidelines.

Response: See the preamble. We agree that States have the discretion whether to require SCR and that States have discretion to determine whether visibility conditions particular control levels.

Comment: One commenter ( 0270) cited studies showing the nitrates contribute only a few percent to total light extinction except in Class I areas downwind of Southern California. Accordingly, NOx emissions from stationary sources are unlikely to lead to any perceptible changes in visibility. Therefore, it is unlikely that NOx emission sources in the West will be good candidates of application of BART.

Response: See the preamble for reference to studies discussing nitrate concentrations in the West, as well as additional studies in the docket.

Comment: Commenter 0241 said states should undertake a full BART analysis, as required by the Act, to determine the appropriate NOx control level that should be established as BART for EGUs. If a presumption is retained, EPA should change the presumption from a lb/ MMBtu emission limitation to a statement indicating that combustion controls installed after enactment of Title IV of the Act should be presumed to satisfy the BART requirement for NOx. States could then evaluate on a boiler specific basis the emission limitation that could be met using combustion controls. Any other approach is simply not justified by the data and would be arbitrary and capricious.

Response:

The presumptive emission limits are based on combustion controls, as the preamble discusses.

Comment: 238 Commenter 0271 said the presumptive level of control must be applied to all units at a " powerplant having a total generating capacity in excess of 750 megawatts" even those units less than 750 megawatts. This conforms to the specific wording of the Clean Air Act ( Sec. 169A( b)( 2)( A)) for controls on these smaller than 750 megawatt units.

Response: We agree that the presumptive limits should not just apply to 750 MW units. See the preamble.

Comment: Eight commenters made general comments on the proposed NOx levels ( 0181, 0186, 0215, 0225, 0241, 0268, 0275, 0314). Commenter 0181 said EPA should remove the presumptive NOx control levels from the final BART guidelines and instead replace it with a site specific cost analysis. Once again, the presumptive NOx emission control approach inappropriately ignores the need for a visibility impact evaluation which is required in Step 5 of the proposed case by case BART engineering analysis. Commenter 0268 such a presumptive limit infringes on a state's authority to establish BART on a case by case basis considering not only visibility improvement, but other factors as well. Commenter 0186 said EPA's proposal for no post combustion NOx controls on power plants should apply equally across all source categories; otherwise, there should be no presumptive control technology prohibition for any source category.

Response: See the preamble. States have discretion to exercise judgment in considering visibility and the other BART factors.

Comment: Commenter 0215 said if an EGU is achieving the default/ presumption for NOx, it should not be required to do a BART determination for that pollutant. Such presumptions would streamline the BART process for those sources willing to reach these control levels.

Response: We agree that a streamlined BART process is warranted for such sources.

Comment: Commenter 0225 said for sources located within 50 km of a Class I area, the source could be required to perform an evaluation of control technologies that compare their cost effectiveness. A number of the large power companies have completed these types of evaluations and have a good understanding of the cost of the various control scenarios for their units. States may want to request cost effectiveness evaluations from sources to determine if a source can cost effectively reduce their emissions. Because a larger number of sources outside of the NOx SIP Call region have not been required to install many advanced NOx controls, cost effective reductions can be achieved.

Response: States have discretion under the Guidelines to require such an analysis. 239 Comment: Commenter 0241 said, for the same reasons identified above with respect to the presumptive SO2 control level for EGUs, the commenter objects to EPA' s proposal to establish a presumptive NOx control level for EGUs.

Response: See the preamble.

Comment: Commenter 0275 supported EPA's proposed finding that add on NOx controls would be too costly to be considered BART for EGUs, in most cases. Even more so, this would hold true for non EGU boilers, " smaller boilers are generally less cost effective to control." However, this finding cannot be made unless a demonstration is made that visibility impairments do not remain. That is, NOx add on controls for EGUs and non EGUs may be appropriate if modeling indicates that 2018 visibility goals will otherwise not be met.

Response: 2018 visibility goals are to be assessed in the regional haze State implementation plan ( SIP) under the regional haze rule. In addition, the CAA requires BART determinations on specific sources.

Comment: Four commenters discussed the averaging period for the emission limits ( 0207, 0214, 0238, 0314). Commenters said the averaging period is unclear and should be annual vs. a short term limit ( 0207, 0214, 0238). Commenter 0314 suggested a 30 day rolling average.

Response: We agree and have specified a 30 day averaging period in the Guidelines.

Comment: Commenter 0241 said if EPA intends to retain a presumption regarding NOx controls in the final Guidelines, EPA should specify only that EGUs should be equipped with combustion controls to limit NO x emissions without identifying a presumed NO x emission rate. Commenters ( 0244, 0252) agreed that EPA should not set a presumptive level of control, since it should be determined on a case by case basis. However, if a limit must be set as guidance for the states it should be higher than 0.20 lb/ MMBTU, in order to avoid forcing the use of post combustion controls ( e. g. SCR and SNCR.).

Response: See the preamble.

10.0 BART and Trading Programs 240 Note: Numerous comments were received on the portion of the proposed BART guidelines which would have provided guidance for trading programs developed in lieu of BART. The final BART guidelines do not contain such a section. Instead, issues related to trading programs or other alternative programs in lieu of BART will be addressed in a separate rulemaking, in order to respond to the recent decision of the D. C. Circuit in Center for Energy and Economic Development v. EPA, No. 03 1222,( D. C. Cir. Feb. 18, 2005). Comments relevant to trading programs in general will be addressed in that rule making. This section of the document responds to comments regarding the criteria for evaluating whether an alternative program makes greater reasonable progress than BART, and on the fundamental legal and policy issues raised by the substitution for BART of emission trading programs, particularly as related to the CAIR.

10.1 Whether a Trading Program Can be Better than BART Comment: Nine commenters supported use of market based trading programs ( 0187, 0199, 0207, 0209, 0211, 0216, 0236, 0237, 0275) and cited their many benefits in terms of emission reductions, efficient use of states' staffing and enforcement resources, incentives for early reductions, incentives for development of new, better technologies, etc. Some commenters specifically supported the CAIR, Clear Skies Initiative, implementation of 8 hour ozone and fine PM controls, clean fuels and engines, and MACT in their ability to satisfy the BART requirements ( 0199, 0209, 0211, 0237, 0275). Commenter 0237 said EPA should not require States to require BART reductions if they are able to demonstrate that federal measures, including CAIR, meet the regional haze reasonable progress milestone of a 10% deciview visibility improvement on the 20% most impaired days by 2018. EPA has the authority to avoid the effort and cost on the part of states and affected sources for BART determinations where they are not needed to achieve the 2018 goals and there is no requirement to impose additional controls as a result of that analysis.

Similarly, Commenters ( 0186, 0275) said EPA should allow states to consider the entire mix of federal controls being implemented ( e. g., cleaner fuels and engines, interstate transport controls, the 8 hour ozone and PM2.5 standards) to determine if additional local controls are need to meet national visibility goals in 2018 and beyond. In cases where emission reductions from federal controls alone will be sufficient to achieve the 2018 visibility improvement goals, EPA should regard the BART obligation as satisfied for all sources. Commenter 0310 discussed the progress that the electric utility industry has already made in achieving massive reductions in SO 2 and NO x emissions.

Commenters ( 0169, 0299) said states should be free to implement an emissions trading program or other alternative measure instead of requiring BART and endorsed the options that states could include non BART eligible sources in a trading program, and have the flexibility to implement an emissions trading program in conjunction with other states. Commenter 0277 approved of the option of allowing non BART sources to participate in a trading program. Commenter 0271 said the flexibility of a trading program could be an available control option to all visibility impairing sources in 2012 and to BART sources to meet additional control requirements beyond BART levels. 241 Response: The EPA also supports the use of market based trading programs as cost effective means to meet air quality objectives, where appropriate, as evidenced by our determination that CAIR may substitute for BART for EGUs in CAIR affected States. We also believe it is appropriate and desirable to include non BART sources in such trading programs, in order to increase market viability. However, for the following reasons, it premature to make any judgements as to what is needed to make reasonable progress.

The Regional Haze Rule, at 40 CFR 51.308( d)( 1), provides the process for States to follow in setting reasonable progress goals. In summary, this process entails: ( a) determining the uniform rate of progress needed to reach natural background conditions in 60 years, ( b) determining the emission reductions needed to achieve the rate for the first 10 year strategy period, ( c) considering certain statutory factors relative to potentially affected sources ( the factors are the costs of compliance, time necessary for compliance, energy and non air environmental impacts, and remaining useful life). After conducting this analysis, the State sets the reasonable progress goals for each Class I area. If a reasonable progress goal is set at a point representing less than the uniform rate of progress to natural background conditions, the state must explain why the slower rate of progress is reasonable. Conversely, if the State determines that a faster rate of progress is reasonable, the State should adopt goals reflecting that rate. See 64 FR 35714, 35732 ( July 1, 1999).

After determining the reasonable progress goals for each Class I area, the State then incorporates the measures needed to achieve those goals in its long term strategy. See 40 CFR 51.308( d)( 3)( v). Long term strategies must also requires states to consider all anthropogenic sources of visibility impairment, including major and minor stationary sources, mobile, and area sources, smoke management techniques for agricultural and forestry management. 40 CFR 51.308( d)( 3)( iv).

Thus, the process of setting reasonable progress goals and appropriate long term strategies involves the examination of all source categories, includes the application of statutory factors to determine reasonableness, and is not terminated by a finding that reductions from any particular source category are sufficient to achieve the uniform rate to natural conditions.

Therefore, the proper question is not whether federal programs " achieve" the reasonable progress goals, but rather what should those goals be, in light of CAIR and other new and ongoing measures; and what additional measures, if any, are needed to achieve those goals.

Comment: Sixteen commenters said other proposed rules such as the Clean Skies Initiative and the CAIR provide no guarantee that air quality in the parks will improve and EPA should not allow these other programs to substitute for BART requirements for power plants ( 0148, 0153, 0154, 0159, 0162, 0163, 0164, 0203, 0203, 0204, 0221, 0232, 0260, 0284, 0292, 0318). Commenters ( 0203, 0204, 0221, 0232) added that the overdue effort to improve air quality in public lands must 242 be harmonized with continuing attempts to reduce the interstate transport of fine particle and ozone pollution. A fully protective federal approach that targets park specific pollution sources and interstate transport of air pollution will help ensure that the RHRs reasonable progress goals are met during the planning period.

Response: Although no predictions of the future can be guaranteed, the EPA believes that the demonstration, based on emissions projections and air quality modeling, that CAIR makes greater reasonable progress than BART, is very robust. We have sought to harmonize the interstate transport requirements of the CAIR with the visibility provisions of the CAA through the determination that CAIR may be considered a BART substitute for EGUs in CAIR affected States, while maintaining park specific protections through the reasonably attributable BART provisions.

Comment: Commenter 0237 was concerned that by promulgating its interpretations for BART, EPA will argue that they have now been codified for BACT and LAER. The commenter asked EPA to clarify its intent so that there will be a final record of review if the commenter believes that EPA's final determinations on the various definitions are necessary.

Response: It is not clear what " interpretations" applicable to BART the commenter believes might be extended to the BACT and LAER context. Although there may be similarities between the programs, there are of course also differences in terms of the statutory provisions involved and the respective purposes of the programs. Therefore it is not possible to say in the abstract whether or not an interpretation under BART will necessarily apply under BACT or LAER.

10.2 Criteria for Demonstrating that an alternative program makes greater reasonable progress than BART 10.2.1 Criteria in General Comment: One commenter ( A200028 335) noted that EPA proposes to require that any state emission trading program achieve greater visibility improvement than would be achieved via source specific BART. However, in considering greater visibility improvement that sourcespecific BART itself achieves, it will be important to keep in mind that there will surely be exceptions on a case by case basis from the presumptions that are established pursuant to the BART guidelines.

Response: The requirement to achieve greater reasonable progress than BART is a separate issue from how emission reductions and visibility improvements achievable by BART are estimated. The latter issue is where the role of presumptive control requirements enter into the 243 trading context. This issue will be addressed in the forthcoming rulemaking on BART trading programs.

Comment:

Three commenters ( A200028 266, A200028 278, A200028 312) asked what the criteria are for " greater reasonable progress" on the 20% worst visibility days and on the 20% best visibility days?

Response: As proposed in the BART guidelines and finalized as 40 CFR 51.308( e)( 3), the criteria for greater reasonable progress than BART are ( 1) no degradation at any Class I area, and ( 2) greater overall improvement based on average improvement at all affected Class I areas As we explained in the final BART preamble, we believe that each prong of the test should ideally be based on an examination of both the worst 20% and best 20% of days.

Comment: Seven commenters ( A200028 239, A200028 247, A200028 249, A200028 266, A200028 289, A200028 352, A200028 362) asserted that the visibility results from any cap andtrade program should be better than under BART. It is not enough to simply reduce tons of emissions nationwide, as the locations of the emissions reductions are critical to improving visibility in specific parks and wilderness areas. Seven commenters said the rule must ensure that the required reductions will result in improved visibility in all affected national parks and wilderness areas ( 0147, 0148, 0159, 0162, 0163, 0164, 0292).

Other commenters said that reasonable progress is a goal and that natural conditions preclude achieving that goal ( 0207). " Better than BART" should be evaluated in the context of reasonable progress. Commenter 0217 said the proposed approach to demonstrate reasonable progress would undermine the fundamental role of the states in determining BART or what constitutes greater reasonable progress than BART.

Commenter 0259 said the proposed guidelines should not limit state and tribal ability to consider all of the reasonable progress factors in the Act in demonstrating greater reasonable progress. The guidelines should not limit a demonstration of greater reasonable progress to only visibility impacts. Other reasonable factors include greater environmental certainty ( through the use of a cap), reduced overall compliance cost ( through the use of an emissions trading mechanism), and consensus effort on the part of stakeholders.

Response: The EPA agrees that visibility improvement is obviously a critical factor in deciding whether a program makes greater reasonable progress towards the national visibility goal than would BART. If an alternative program results in a different geographic distribution of emission reductions than would BART, it may not be possible to predict greater reasonable progress based solely on the fact that the alternative produces greater emissions reductions. Therefore, in such 244 circumstances, the " better than BART" test requires a demonstration based on visibility modeling. In the forthcoming rule proposal on BART trading programs, we will seek comment on how other factors might be considered.

Comment: Three commenters asked under what conditions will a dispersion modeling analysis be required ( i. e., how different must the spatial distribution in emission reductions be)?

Response: We believe it is not necessary for EPA to define in the rule the degree of difference in the geographic distribution of emissions necessary to trigger application of the two prong test. For our CAIR analysis, we explained in the SNPR that the fact that CAIR would produce greater emissions reductions than BART in most States, but less reductions than BART in a few States, was sufficient reason to employ the two pronged visibility test. 69 FR 32704. For other programs developed by States, a State would have the ability to make a reasonable decision as to whether there was a sufficient basis to make the demonstration that an alternative program would be better than BART based on modeling of the emissions distributions alone, or whether the State should proceed with the two pronged visibility test. The State's discretion is subject as always to the condition that it must be reasonably exercised, and must be supported by adequate documentation of the analyses.

Comment: Four commenters said the guidance should only require that the trading program achieve " equivalent" progress, rather than greater progress, compared to BART. ( A200028 272, A200028 275, A200028 333, A200028 7001). They say requiring greater progress would be by definition overstepping the Congressional mandate and that there is no justification for such a position. Other commenters said the requirement to achieve greater emissions reductions provides a strong disincentive to the implementation of a trading program, and, therefore, is not appropriate.

Response: The EPA's interpretation of CAA 169A( b)( 2) as allowing for an alternative to BART where the alternative makes greater reasonable progress was upheld by the Ninth Circuit in Central Arizona Water Conservation District v. EPA, 990 F. 2d 1531 ( 9th Cir. , Mar. 25 1993). In that case the court held that: " Congress's use of the term ` including' in § 7491( b)( 2) prior to its listing BART as a method of attaining ` reasonable progress' supports EPA's position that it has the discretion to adopt implementation plan provisions other than those provided by BART analyses in situations where the agency reasonably concludes that more ` reasonable progress' will thereby be attained." Id. at 1543 ( emphasis supplied).

This interpretation was more recently upheld by the D. C. Circuit in CEED v. EPA, where the court stated that the petitioner had " shown neither that Congress's language precluded non BART alternatives where BART wasn't ` necessary to make reasonable progress,' nor that EPA's reading is otherwise unreasonable. CEED v. EPA, Slip. Op. at 13 ( D. C. Cir., Feb. 18 2005). As 245 in Central Arizona Water, in CEED our determination that BART was not necessary to make reasonable progress was premised on the determination that the alternative program made greater reasonable progress than BART. In this case the program at issue   a backstop emission trading program for certain western States and Tribes in the Western Regional Air Partnership   was invalidated on other grounds. ( Specifically, because the program was constrained by an invalid methodology for determining the emissions reductions achievable from BART. Id. at 14). Nothing in the court's decision in CEED suggests that a " greater reasonable progress" test as a criteria for an alternative to BART program would be " overstepping the Congressional mandate." In fact, the court noted that " Congress's addition of § 169B . . . clarified that the focus of the Clean Air Act was to achieve ` actual progress and improvement in visibility' . . . not to anoint BART the mandatory vehicle of choice." Id at 13, citations omitted. Comment: Two commenters discussed visibility impairment under existing conditions. Commenter 0255 described differences between the Acid Rain program and the BART guidance. The BART guidance focuses on emissions from individual combustion sources that are significantly contributing to local visibility problems in national parks and wilderness areas. Because EPA has identified 50 km as a sensitive corridor around these Class I areas, sources within this 50 km area should not have the option to opt out if they are found to be BART eligible.

Response: Any localized impacts from BART eligible sources such as the commenter raises can be addressed by BART for reasonably attributable visibility impairment if necessary.

10.2.2 Averages as a Measure of Improvement Comment: One commenter ( A200028 258) stated that to ensure that trading budgets result in greater reasonable progress, dispersion modeling must be required. Further, it is not acceptable to allow averaging of the difference between improvements due to BART and due to the emissions trading program among Class I areas to show an overall improvement.

Five commenters opposed using averages as a measure of improvement ( 0179, 0221, 0227, 0267, 0305). Commenter 0179 said it is inappropriate to justify the use of any trading program, or other BART provision, based on " averaging" of improvements in visibility over Class 1 areas. To satisfy the legal requirements of the BART, trading programs should be allowed only if it can be shown that they will reduce pollution and improve visibility more than a source bysource clean up would and visibility is shown to improve at each and every Class 1 area. Commenters ( 0221, 0227, 0292) said averaging is contrary to the Act because section 169A and the RHR are designed to reduce and eventually eliminate visibility impairment in each Class I area. Commenter 0221 added that visibility improvement is not a commodity that can be " traded" among states or Class I areas because they each have a different required rate of visibility progress and different emission reduction requirements to meet a specific visibility progress rate. Commenter 0267 was concerned that trading would allow sources near Class I areas to purchase 246 allowances rather than install emission controls, and that visibility improvement at all Class I areas would not be achieved.

Commenter 0267 said the CAIR should satisfy the requirements laid out at 40 CFR 51.308( e)( 2) to demonstrate it is better than BART. Showing that visibility is at worst, unchanged under CAIR does not represent reasonable progress. The commenter asked how EPA can use an average visibility improvement calculation based on 44 sites to conclude that CAIR is " better than BART", because the RHR required improvement at all Class I areas.

Response: As we explained in the CAIR NFR preamble, we disagree with comments that CAA § 169A( b)( 2)' s requirement of BART for sources reasonably anticipated to contribute to impairment at any Class I area means that an alternative to the BART program must be shown to create improvement at each and every Class I Area. Even if a BART alternative is deemed to satisfy BART for regional haze purposes, based on average overall improvement as opposed to improvement at each and every Class I Area, CAA § 169A( b)( 2)' s trigger for BART based on impairment at any Class I area remains in effect, because a source may become subject to BART based on " reasonably attributable visibility impairment" at any area. See 40 CFR § 51.302.

In addition, within a regional haze context, not every measure taken is required to achieve a visibility improvement at every class I area. BART is one component of long term strategies to make reasonable progress, but it is not the only component. The requirement that the alternative achieves greater progress based on the average improvement at all Class I areas assures that, by definition, the alternative will achieve greater progress overall. Though there may be cases where BART could produce greater improvement at one or more class I areas, the no degradation prong assures that the alternative will not result in worsened conditions anywhere than would otherwise exist, and the possibility of BART for reasonably attributable visibility protects against any potential " hot spots." Taken together, the EPA believes these factors make a compelling case that the proposed test properly defines " greater reasonable progress." The EPA anticipates that regional haze implementation plans will also contain measures addressing other sources as necessary to make progress at every mandatory federal Class I area.

With respect to the number of Class I areas used in the demonstration, in updated analysis in the CAIR NFR, we analyzed the results for 81 IMPROVE sites representing 116 Class I areas.

10.2.3 Visibility Impairment Hot Spots & Reasonably Attributable Visibility Impairment Comment: Three commenters provided general comments on hot spots ( 0201, 0304, 0323). Commenters ( 0201, 0304) said the need to include geographic enhancements within any national trading program should be strongly emphasized to ensure that no visibility " hot spots" are created as a product of trading. Commenter 0323 said the guidance should cite the WRAP approach as an example of implementing the " geographic enhancement" provisions of the regional haze rule. 247 Response: Regional haze rule § 308( e)( 4) as finalized does provide States with the option of utilizing geographic enhancements.

Comment: Two commenters discussed how FLMs should certify impairment ( 0201, 0246). Commenter 0201 said for sources subject to the IAQR/ CAIR, the RPOs should work with the FLMs to establish criteria for future certifications which recognize that the IAQR/ CAIR's overall regional emissions reductions will achieve more visibility improvement across a broad geographic area than implementation of BART alone. Such criteria would address pollutant trends measured at Class I areas, limits on distance from a given class I area for certification of BART eligible sources, and recognition of existing, or commitments to future, emissions controls. Should the IAQR/ CAIR be finalized, the RPOs should encourage the FLMs and affected sources to communicate regularly during implementation of the rule regarding Class I area monitoring data so that planned emissions reductions would ensure reasonable geographic distribution of the benefits and thereby avoid the likelihood of any future source specific certifications under 40 CFR 51.302. The FLMs and states should retain the authority to " certify" impairment at specific class I areas which may be " reasonably attributable" to sources subject to the IAQR/ CAIR.

Commenter 0246 said there is a need for guidance about the specific kinds of circumstances that would cause an FLM to identify a " hot spot" leading to certification of impairment. The current criteria ( Class I areas in which sulfates are not decreasing may result in scrutiny of sources within 200 kilometers controlled at less than 85% capture rate) may not provide adequate guidance. Another alternative that is the continuing discussions between stakeholders and the FLMs under the WRAP would determine how new data and information can be used to inform regulatory intervention in the section 309 backstop market program.

Response: Today's action does not affect the ability of FLMs or States to certify reasonably attributable visibility impairment. We believe regulatory certainty may be improved by agreements with FLMs regarding the circumstances under which RAVI may be certified, coupled if necessary with " geographic enhancements" to the trading program to accommodate sources subject to RAVI BART. We therefore encourage cooperation and communication between States, Tribes, and RPOs on these issues. However, providing additional guidance on these issues is beyond the scope of this rule.

Comment: Two commenters discussed the role of BART for reasonably attributable visibility impairment ( 0217, 0246). Commenter 0217 had concerns about the role of BART for reasonably attributable visibility impairment ( RAVI) until the final milestone is achieved under a trading program in 2018. Even if the role of this regulatory tool is likely to be limited, the regulated community thinks it creates significant uncertainty. The commenter urged the states, FLMs and stakeholders to further define the limited circumstances ( e. g., to address " hot spot" concerns) when this regulatory mechanism could come into play, and to be mindful of the central role of the states in making attribution determinations and in fashioning BART remedies. Commenter 0246 248 urged the states, tribes, FLMs and other stakeholders to continue to explore ways in which uncertainty from the potential use of this program can be minimized and creative remedies might be fashioned under the " geographic enhancement" program.

Response:

See previous response. EPA encourages cooperation and communication between States, Tribes, and RPOs on defining RAVI; However, providing additional guidance on these issues is beyond the scope of this rule.

Comment: Five commenters disagreed with the creation of " reasonably attributable BART" as exceeding EPA's authority ( 28 357, 28 305, 28 36, 28 364, 28 395). There is only one CAA BART process and EPA's efforts to create two are arbitrary and unfair ( 28 395). Commenter 28 357 added that, in event EPA persists with the concept of two BARTs, the Guidelines should permit states to integrate them in a manner that clearly distinguishes the applicability of both programs and eliminates the potential " double jeopardy" and resulting uncertainty facing regulated sources. In effect, where a determination is made that a cap and trade program like 309 would achieve that greater reasonable progress, the BART issue for all eligible participating sources of SO x would be resolved. A second alternative is to clearly and specifically reconcile and limit the role of BART for RAVI until all BART tolls for affected sources in the applicable region.

Commenter 28 395 said the original BART guidelines and EPA's proposed new guidelines should be integrated. From a statutory perspective, the visibility protection program of the Clean Air Act does not refer to either type of visibility impairment. The statute merely refers to " visibility impairment". Similarly, the Act does not refer to one BART for reasonably attributable visibility impairment and another BART for contributors to regional haze. The visibility protection program merely refers to " BART". While the focus of the original 1980 visibility protection rules on plume blight was a useful device at the time, the need for any distinction between types of visibility impairments has been eliminated now that EPA is implementing the entire visibility protection program. EPA should revise the BART guidelines for large fossil fuel fired stream electric generating units so that there is one BART for emissions that impair visibility in MCIF Areas.

Commenter 0252 said greater " reasonable progress" ensures that there will be visibility improvements in all Class I areas; therefore there is no reason to retain reasonably attributable BART. EPA should provide greater regulatory certainty by clarifying that once a source has complied with the regional haze/ BART rule, either through source specific BART or through a cap and trade program such as CAIR, it has complied with reasonably attributable BART.

Commenter 0323 agreed with EPA that any " market" approach to address the regional haze BART requirement does not necessarily address all " reasonably attributable" impairment. 249 Commenter 0304 said, until they are in compliance with the final emissions budgets ( through reductions or the purchase of allowances,) sources subject to the IAQR should be subject to visibility protection regulations regarding " reasonably attributable" visibility impairment.

Response: The EPA established in the 1999 regional haze rule that the requirement to install and operate BART is applicable in the regional haze context under CAA 169B as well as under the 1980 " reasonably attributable" regulations at 40 CFR 51.302. Comments or challenges to this interpretation were ripe at that time. As noted in the CAIR NFR preamble, the EPA continues to maintain that BART based on reasonably attributable visibility impairment ( RAVI) must be retained in order to protect against the possibility of localized degradation, even though current modeling does not predict such " hot spots." Integration of " RAVI" BART into a trading program may be accomplished through geographic enhancements.

Comment: Four commenters discussed the process for determining whether reasonably attributable visibility impairment ( 0224, , 0246, 0252, 0323). Commenter 0246 said it is the primary responsibility and role of the states and tribes to determine reasonable attribution and BART under the RAVI program. Commenter 0224 said guidance ( e. g. how to weight BART factors, such as cost effectiveness), or presumptive numerical BART emission limits that apply for regional haze should apply in the same manner to " reasonably attributable" visibility impairment. Applying technology ( or performance) presumptions to regional haze without applying the same presumptions to " reasonably attributable" visibility impairment would be applying statutory factors inconsistently and therefore would be contrary to the statute.

Response: The 1980 regulations lay out the process for addressing reasonably attributable BART. See 40 CFR 51.302( c). Other than making a minor change to the BART determination process for sources found to have a reasonably attributable contribution to visibility impairment, we are not revising these regulations.

10.3 Determination that CAIR is " Better than BART"

Comment Commenter 0267 was concerned with emissions " leakage" issues for CAIR border areas and how that will affect nearby Class I areas. A demonstration of the distribution of emissions needs to be made to ensure it is not different than the source by source BART approach to ensure that the trading program achieves better visibility improvement. If the distribution is different under the two approaches, a modeling study for each Class I area is necessary for both the worst and best 20% days. Also, reductions seen in emissions under Title IV have been in proportion to the size of the emission sources, so Class I areas that are remote from individual " large" sources, and/ or at the edges of the CAIR trading region, may not make enough reasonable progress without enhanced control of nearby sources. Since the reasonable progress goals have not been determined for the Class I areas it is not known how the projected improvement in visibility under CAIR compares to what will be necessary. States may need to get additional 250 reductions from some EGUs above and beyond CAIR on a case by case basis to achieve reasonable progress at some Class I areas.

Response: The EPA has determined that the CAIR will achieve greater reasonable progress than BART for EGUs and therefore may be treated by States as a substitute for BART for affected EGUs. This does constitute a finding that CAIR fully satisfies the reasonable progress requirement for each Class I area. The EPA agrees that States may need to get more emission reductions than provided by CAIR in order to meet reasonable progress goals at some Class I areas. States have the discretion to determine from what sources to obtain those reductions, and are not required to treat CAIR as having satisfied BART for EGUs.

Comment: Commenter 0221 said EPA's proposal to categorically exclude sources from BART, without opportunity for the states to evaluate the adequacy of the reductions in light of the BART requirement, to consider their overall visibility protection needs, or to effectuate the core requirements and purposes of the visibility protection program, tramples over section 169A, the relative roles and responsibilities of federal and state governments embodied in section 110 of the Act, and the court's affirmance of state prerogatives in American Corn Growers.

Response: EPA's determination that CAIR may substitute for BART for affected EGUs does not infringe on State prerogatives because States are not compelled to accept this determination.

10.3.1. Applicable Sources Comment: Seventeen commenters discussed how sources subject to CAIR and BART should be treated ( 0169, 0189, 0201, 0207, 0208, 0223, 0230, 0252, 0253, 0271, 0272, 0277, 0279, 0299, 0304, 0308, 0310, 0317). Some commenters opposed exempting sources subject to the CAIR from the BART rule ( 0169, 0310, 0317). Commenter 0275 said this exemption would be unfair to sources that have already taken steps to reduce regional haze, such as through the production of clean fuels. Commenter 0310 said an overlapping regulatory scheme would impose unnecessary and contradictory requirements on this industry that is already heavily regulated, that has already achieved significant emissions reductions, and that provides a necessary and significant contribution to the Texas and national economies. Accordingly, the commenter concurs with EPA's recommendation that BART requirements must not be made applicable to entities subject to the CAIR.

Response:

We agree that the overall advantages provided by integrating BART requirements with CAIR and thereby allowing BART for EGUs to be satisfied in the most cost effective way possible outweighs any inequity ( if it exists) towards sources that have already reduced emissions. 251 Such sources will continue to enjoy the benefits of lower emissions, such as lower costs to comply with emission allowance requirements.

Comment: Commenter 0189 said visibility improvement requirements following 2018 should be determined on the basis of visibility impact and cost effectiveness as the primary factors, with other secondary factors such as state of development of control technology and administrative costs also considered. Sources should not be exempted from control or review simply because they were controlled under CAIR or BART. However, commenter 0253 said affected states should be required to look initially to non EGU sources for any additional emissions reductions that might be required by statute or regulation.

Response: The regional haze rule requires a comprehensive SIP revision in 2018 to establish a new long term strategy. Although all BART requirements will of necessity have been satisfied at that time, we cannot prejudge what requirements may be deemed appropriate for the next 10 year planning period.

Comments: Several commenters addressed the role that CAIR opt in requirements should play relative to BART. Commenters ( 0189, 0201, 0207, 0223, 0308) said EPA must provide that CAIR compliance equals BART compliance for non EGU sources that " opt in" to CAIR coverage. This rule of per se compliance should apply just as much to opt in sources that comply through emissions allowance trading as to opt in sources that install controls. Other commenters ( 0207, 0208) said that EPA should take necessary steps to assure power plant owners that the requirements of the CAIR meet the Acts's BART obligations, as well as the reasonable further progress criteria of the RHR. Commenter 0230 said appropriate " opt in" provisions are needed. Alternatively, commenter 0272 said an effective control of SO 2 and NO x emissions from non EGU sources could be achieved by introducing an approach similar to BART in CAIR for non EGU sources. " BART for CAIR" would only be applied on major non EGU sources and the limiting criteria for the stringency of control would be cost effectiveness, existing controls and probably other criteria determined by EPA in a corresponding guideline.

Response: Our determination that CAIR is " better than BART" was based on emission projections and air quality modeling for EGUs only. For an opt in source to use CAIR to satisfy BART, a supplementary demonstration would be required.

Comment: Commenter 0208 provided additional comments on the need to properly design the " western CAIR" and why this is the best way to implement the BART trading program in the west. However, commenters ( 0223, 0230, 0304) urged EPA to encourage states to participate in national trading program, rather than regional trading programs. Commenter 0252 urged EPA to make CAIR a nationwide program. A nationwide program would reduce unnecessary burden on 252 states to develop an interstate trading program in coordination with EPA. Furthermore, it would provide a more robust market for all states, especially those in the west.

Response: As explained in the CAIR RTC, The EPA agrees there could be some advantages to an expanded geographic scope for CAIR, but such an expansion would also raise numerous technical and legal challenges which could delay promulgation and implementation of the rule. Therefore the EPA determined that it was appropriate to focus in the CAIR on obtaining the health and welfare benefits related to implementation of PM2.5 and Ozone standards. This does not foreclose the possibility of expanding a CAIR like approach to the West at a later date.

10.3.2 Specific Comments Regarding Whether CAIR Satisfies BART Comment: Thirty eight commenters said that the CAIR can or should satisfy BART requirements ( 0181, 0185, 0187, 0188, 0189, 0195, 0198, 0201, 0206, 0207, 0210, 0213, 0214, 0215, 0216, 0223, 0224, 0228, 0230, 0236, 0238, 0242, 0245, 0250, 0252, 0253, 0254, 0256, 0265, 0276, 0294, 0300, 0303, 0304, 0308, 0310, 0319, 0323) for several reasons, including the following: ° CAIR reductions should satisfy a state's obligation to satisfy BART under the RHR, including the reasonable progress requirements ( 0181, 0185, 0189, 0224, 0245, 0250, 0252, 0253, 0254, 0256, 0308, 0300, 0310). ° The emission reductions required under the CAIR will result in cost effective emission reductions ( 0181, 0210, 0213, 0228, 0308, 0319, 0294). ° The CAIR emissions reductions are scheduled to take effect in the 2010 2015 time frame, which coincides with the schedule for BART implementation ( 0181). ° Allowing the CAIR to replace BART avoids subjecting sources to overlapping regulatory requirements and provides regulatory certainty ( 0187, 0216, 0236, 0250, 0252, 0253, 0300, 0310, 0319). ° Since the purpose of BART is visibility improvement, there is no reason to impose BART in states where visibility improvement goals can be met without it ( 0189, 0253). ° Greater participation in the trading program will result in greater opportunities for trading and cost savings ( 0250, 0319).

Commenter 0201 said that until sources are in compliance with the final emissions budgets ( through reductions or the purchase of allowances) the sources subject to the IAQR/ CAIR should be subject to visibility protection regulations regarding " reasonably attributable" visibility impairment.

Response: As explained in the preamble, EPA has determined that CAIR makes greater reasonable progress than BART and may substitute for BART for EGUs in CAIR affected States. 253 Except for the intimation that it can be determined at this time whether CAIR satisfies all reasonable progress goals, the EPA agrees with the commenters.

Comment: Fourteen commenters said CAIR cannot or should not satisfy BART requirements for several reasons, including the following ( 0147, 0150, 0151, 0165, 0203, 0204, 0221, 0227, 0235, 0255, 0267, 0280, 0305, 0317): ° IAQR does not protect the all 156 Class I areas defined in the 1977 CAA amendments and will not produce mandated reductions in the first 10 years ( 0147, 0150, 0151, 0203, 0204, 0221, 0227, 0317). ° CAIR needs significant strengthening to adequately protect polluted communities ( 0203, 0204) ° The goals of the programs are different, resulting in a different spectrum of controls under CAIR than would occur under BART ( 0267, 0280) ° Adoption of CAIR appears to preclude application of source by source BART to EGUs, and all Class I areas may not experience visibility benefits from a trading program equal to, or greater than, the benefits realized from source by source BART ( 0267). ° The proposal is inconsistent with the Act ( 0203, 0204, 0221, 0227). ° Due to the availability of control technologies to cost effectively reduce SO 2 and NO x emissions from coal fired boilers, BART eligible sources should not be allowed to opt out of the program without meeting the mandated emissions limits ( 0255).

Commenter 0221 added that several arguments describing why the " better than BART" provision violates the Act. For example, EPA has not found superior visibility improvement resulting from application of CAIR compared to source by source BART controls in each and every Class I area that may be impacted by BART eligible sources in the CAIR region. EPA's attempt to use average emissions over selected areas is not sufficient. Commenters ( 0221, 0235) added that instead of implementing the Act, EPA is attempting to amend it. Commenter 0221 also described serious policy flaws in the proposal such ignoring the need to virtually eliminate SO 2 emissions in order to reach the national visibility goal.

Response: The policy of allowing another program to substitute for BART is not an illegal substitution of the Agency's judgment for that of Congress, but rather is based on a reasonable interpretation of the ambiguous language of CAA § 169A( b)( 2). This section provides that EPA must require SIPs to contain certain measures " as may be necessary to make reasonable progress toward meeting the national goal . . . including   " among other things, a requirement that BARTeligible sources install BART. See 42 USC 7491( b)( 2). The EPA has interpreted this as meaning that BART is required only " as may be necessary to make reasonable progress." A logical corollary is that if an alternative strategy covering a given source or source sector makes greater progress than BART, then BART is not necessary for that source or sources. 254 In Central Arizona Water Conservation District v. EPA, 990 F. 2d 1531, ( 1993), the Ninth Circuit applied the two step Chevron test ( Chevron, U. S. A., Inc. v. NRDC, 467 U. S. 837, 842 45 ( 1984) and found that the statutory language was ambiguous and that EPA's interpretation was reasonable. 990 F. 2d at 1543. The court therefore agreed that the statute provided EPA with " discretion to adopt implementation plan provisions other than those provided by BART analyses in situations where the agency reasonably concludes that more ` reasonable progress' will thereby be attained." Id. In that case, the BART alternative in question applied to a single facility.

In, Center for Energy and Economic Development v. EPA, No. 03 1222, ( D. C. Cir. Feb. 18, 2005) (" CEED"), the D. C. Circuit similarly applied the two step Chevron test and also found that the statutory language was ambiguous and that EPA's interpretation was reasonable. CEED, slip op. at 12 13. In CEED , the BART alternative at issue ( the WRAP Annex) applied not just to one facility but to all BART eligible sources ( as well as other sources) in participating States. Therefore, the CEED decision clarified that EPA's interpretation of § 169A( b)( 2) allowing a BART alternative is reasonable not only in a source specific context but also in the context of larger programmatic BART alternatives. ( The court vacated the Annex on other grounds, holding that EPA did not rationally exercise its discretion with respect to the particular methodology required of States to demonstrate that the Annex would result in greater progress than BART. CEED, slip op. at 14).

The CAIR cap and trade program for EGUs represents an intermediate case between the single source BART alternative in Central Arizona Water and the all BART sources alternative in CEED . A BART alternative program can only achieve emission reductions at sources included in the program and so cannot achieve greater reasonable progress than BART with respect to BART eligible sources which are not covered by the program. Therefore, the relevant question for CAIR is whether it achieves greater reasonable progress from EGUs than would BART for EGUs. If it can be shown that CAIR does so, then under EPA's interpretation of § 169A( b)( 2), upheld in both these cases, BART for EGUs is not " necessary to make reasonable progress." Because this finding would be applicable only to EGUs, it would not frustrate Congress's intent in identifying 26 source categories for BART applicability. ( Note that as explained in the NFR, a State which chooses to meet its CAIR emission reduction requirements partially or wholly from non EGU sources could consider BART satisfied for any BART eligible non EGUs affected, but the State would have to conduct a better than BART analysis covering this alternative means of meeting its CAIR requirements).

The EPA believes the analysis presented in the CAIR preamble and TSD convincingly demonstrate that CAIR achieves greater reasonable progress, with respect to SO 2 and NO x emissions from EGUs, than would source specific BART for EGUs in the CAIR region.

Moreover, the EPA does not believe that it is a prerequisite of BART alternative programs that the emission reductions be developed explicitly for visibility purposes in the first place. As long as the end result is greater visibility improvement than BART, it is of no consequence that the emission reductions were initially developed to serve other air quality purposes. As the D. C. Circuit stated in CEED, " Congress's addition of § 169B . . . clarified that 255 the focus of the Clean Air Act was to achieve ` actual progress and improvement in visibility,' . . . not to anoint BART the mandatory vehicle of choice." CEED, slip. op. at 13. As long as visibility is actually improved more than it would be under BART, it should not matter whether the emission reductions were developed explicitly for visibility, as under BART, or for some other purpose, as under CAIR.

Comment: Nine commenters provided additional comments regarding whether CAIR satisfies BART ( 0186, 0231, 0234, 0237, 0267, 0275, 0280, 0285, 0304). Some commenters pointed out instances where complying with CAIR may not satisfy BART. Commenters ( 0186, 0237, 0275) said there can be scenarios where the " highly cost effective" metric for CAIR controls may not rise to the level of BART, which must also consider a number of other factors, including improvements in visibility. Commenter 0231 said if trading is allowed, how can a state be sure that the impacts on the Class I area by any source are addressed? A source close to and significantly impacting a Class I area could elect to buy allowances from another source hundreds of miles away that has no impact whatsoever. The Class I area impacts therefore would not be addressed.

Response: While the highly cost effective criterion used in CAIR might not result in BARTequivalent controls on individual units, in the aggregate the CAIR results in millions of tons more emissions reductions than BART and has been shown to make greater progress based on visibility projections.

Comment: Commenter 0267 said CAIR, as proposed, is not better than BART but it could be made better than BART by lowering the emission caps for SO 2 and NO x. Commenter 0280 said unless the stringency of CAIR is increased, BART should apply to all affected sources, including EGUs. Visibility improvement should be a certainty and not subject to a market decision on where emission reduction investments are placed. However, there is a link between CAIR and visibility improvement and emission reductions as a result of installing BART control should count toward meeting the emissions budget established in CAIR. Commenter 0267was concerned that unless the CAIR emission caps are lowered to levels consistent with moderate costs per ton, that they will be better than BART.

Response: Our analysis has demonstrated that the emission reductions required by CAIR are in fact " better than BART" according to the criteria we previously proposed and have now finalized at regional haze rule 308( e)( 3).

Comment: Commenter 0285 asked EPA to clarify whether CAIR would satisfy the BART requirements for SO 2 and NO x only or for all four pollutants? Also, at plants where CAIR applies, would a BART evaluation be required of activities other than the boilers themselves? 256 Response:

Our determination that CAIR is better than BART applies only to SO2 and Nox. If an EGU covered by CAIR for SO2 and NOx does not qualify as a BART eligible source based on potential to emit 250 tons of any other visibility impairing pollutant, then it would not be subject to BART and would not have go through a BART determination. For units in all other BARTcategories the BART guidelines should be followed to determine which units are subject to BART.

Comment: Four commenters provided other comments on the CAIR ( 0214, 0228, 0242, 0267). Commenter 0214 said if EPA chooses not to determine that CAIR satisfies BART, the agency should specify in the final guidelines that, in their individual source assessments, Eastern sources should be able to model for visibility impairment assuming that the CAIR is in effect.

Response: EPA has made the determination that CAIR satisfies BART so the comment is not relevant.

Comment: Commenter 0228 asked EPA to clarify the final guidelines by specifying that surplus reductions resulting from measures adopted to meet requirements of the Act as of the baseline date of a state's regional haze SIP means the date of the emission inventories upon which the regional haze SIPs rely, which the BART Guidelines specify is the 2002 base year emission inventory ( which would not include the additional emission reductions to be obtained through the CAIR rule) . Also, EPA should clarify that states which fully implement the CAIR trading program and for which EPA has approved a SIP revision implementing the CAIR reductions, be relieved from the technical and analytical requirements to demonstrate " greater reasonable progress" or greater visibility improvement than would be achieved through the installation and operation of sourcespecific BART as it applies to EGUs. Commenter 0242 said emission reductions that will be finalized in CAIR are " surplus to those reductions resulting from measures adopted to meet the requirements of the CAA as of the baseline of the SIP" because the baseline of the regional haze SIP is the year of the base emissions inventory ( 2002). Therefore, since CAIR will be finalized after that date, CAIR emission reductions were not required prior to the regional haze baseline date.

Response: EPA has stated at several places within the CAIR rulemaking that 2002 is the base year for regional haze emissions inventory and that CAIR reductions are therefore surplus to base year requirements. We also agree that States that opt to utilize CAIR as a BART substitute may rely on our technical determination rather than being required to submit their own demonstration. The State option to utilize CAIR is provided by regional haze rule section 308( e)( 4).