Source: http://www.govpulse.us/entries/2006/10/13/06-8630/regional-haze-regulations-revisions-to-provisions-governing-alternative-to-source-specific-best-avai
Timestamp: 2015-07-06 16:00:41
Document Index: 269004844

Matched Legal Cases: ['§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', 'art 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51', '§ 51']

govpulse | Regional Haze Regulations; Revisions to Provisions Governing Alternative to Source-Specific Best Available Retrofit Technology (BART) Determinations
How This Preamble Is Structured
Overview of Changes to §§ 51.308(e)(2) and 51.309 of the Regional Haze Rule
II. Revisions to Regional Haze Rule § 51.308(e)(2) Governing Alternatives to Source-by-Source BART
A. Establishing a BART Benchmark and Demonstrating Greater Reasonable Progress Than BART
Framework for Demonstrating That an Alternative Program Provides for Greater Reasonable Progress
Sources Subject to BART
The BART Determination
(1) Types of Models
(2) State Discretion to Consider Cumulative Visibility Impacts
Role of BART Guidelines for EGUs in DeterminationsProposal
Minimum Universe of Sources Covered
Comparison of BART and Alternative Scenarios
B. Comments Relating to the Final Determination That CAIR Makes Greater Reasonable Progress Than BART in the July 6, 2005 BART Guideline Rule
C. Minimum Elements of Cap and Trade Programs
III. Revisions to Regional Haze Rule § 51.309
Support for the WRAP Program
The WRAP Program as a Reasonable Progress Measure
Geographic Enhancements
Other Comments and Responses
The EPA has established a docket for this action under Docket ID No. EPA-HQ-OAR-2002-0076. All documents in the docket are listed on the www.regulations.gov Web site. Although listed in the index, some information is not publicly available, i.e., confidential business information (CBI) or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically through www.regulations.gov or in hard copy at the OAR Docket, EPA/DC, EPA West, Room B102, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air and Radiation Docket and Information Center is (202) 566-1742. NOTE: The EPA Docket Center suffered damage due to flooding during the last week of June 2006. The Docket Center is continuing to operate. However, during the cleanup, there will be temporary changes to Docket Center telephone numbers, addresses, and hours of operation for people who wish to visit the Public Reading Room to view documents. Consult EPA's Federal Register notice at 71 FR 38147 (July 5, 2006) or the EPA Web site at www.epa.gov/epahome/dockets.htm for current information on docket status, locations and telephone numbers.
Kathy Kaufman, EPA, Air Quality Planning Division, Geographic Strategies Group, C504-02, 919-541-0102 or by e-mail at kaufman.kathy@epa.gov, or Todd Hawes, EPA, Air Quality Planning Division, Geographic Strategies Group, C504-02, 919-541-5591 or by e-mail at hawes.todd@epa.gov.
Regulated Entities. This final rule will affect the following: State and local permitting authorities and Indian Tribes containing major stationary sources of pollution affecting visibility in federally-protected scenic areas.
This list is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this action. This list gives examples of the types of entities EPA is now aware could potentially be regulated by this action. Other types of entities not listed could also be affected. To determine whether your facility, company, business, organization, etc., is regulated by this action, you should examine the applicability criteria in section II of this preamble. If you have any questions regarding the applicability of this action to a particular entity, consult the people listed in the preceding section.
B. Comments Relating to the Final Determination That CAIR Makes Greater Reasonable Progress Than BART in the July 6, 2005 BART Guidelines Rule
I. Overview and Background ↑
This rulemaking provides the following changes to the regional haze regulations:
(1) Revised regulatory text in section 51.308(e)(2)(i) in response to the Center for Energy and Economic Development (CEED) v. EPA court's remand, to remove the requirement that the determination of the BART “benchmark” be based on cumulative visibility analyses and to clarify the process for making such determinations;
(2) New regulatory text in § 51.308(e)(2)(vi), to provide minimum elements for cap and trade programs adopted in lieu of BART; and
(3) Revised regulatory text in § 51.309, to reconcile the optional framework for certain western States and Tribes to implement the recommendations of the Grand Canyon Visibility Transport Commission (GCVTC) with the CEED v. EPA decision.
How This Preamble Is Structured ↑
Section I provides background on the BART requirements of the CAA as codified in the Regional Haze Rule, on the decision in American Corn Growers in which the DC Circuit vacated and remanded parts of the rule addressing the BART requirements, on the June 2005 BART rule, and on the EPA's approval of the WRAP Annex and thesubsequent litigation. Section II discusses specific issues relating to the revisions to § 51.308(e)(2) of the Regional Haze Rule governing alternatives to source-by-source BART. Section III discusses specific issues relating to the revisions to § 51.309 of the Regional Haze Rule pertaining to the optional emissions trading program for certain western States and Tribes. Section IV provides a discussion of how this rulemaking complies with the requirements of Statutory and Executive Order Reviews.
The Regional Haze Rule and BART Guidelines ↑
In 1999, we published the Regional Haze Rule to address visibility impairment produced by a multitude of sources and activities which emit fine particles and their precursors and which are located across a broad geographic area (64 FR 35714). The Regional Haze Rule requires States to submit State implementation plans (SIPs) to address regional haze visibility impairment in 156 federally-protected parks and wilderness areas, such as the Grand Canyon and Yosemite. These 156 scenic areas are called “mandatory Class I Federal areas” in the CAA
but are referred to simply as “Class I areas” in today's rulemaking. The 1999 rule was issued to fulfill a long-standing EPA commitment to address regional haze under the authority and requirements of sections 169A and 169B of the CAA.
As required by the CAA, we included in the final Regional Haze Rule a requirement for BART for certain large stationary sources that were put in place between 1962 and 1977. We discussed these requirements in detail in the preamble to the final rule (64 FR 35737-35743). The regulatory requirements for BART were codified at section 51.308(e) and in definitions that appear in section 51.301.
In the preamble to the Regional Haze Rule, we committed to issuing further guidelines to clarify the requirements of the BART provision. These guidelines were issued on July 6, 2005 in a final rule entitled “Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations' (“the BART Rule”) (70 FR 39104). The purpose of the BART guidelines is to assist States as they identify which of their BART-eligible sources should undergo a BART analysis (i.e., which are “sources subject to BART”) and select appropriate controls (“the BART determination”).
We explained in the preamble to the 1999 Regional Haze Rule that the BART requirements in section 169A(b)(2)(A) of the CAA demonstrate Congress' intent to focus attention directly on the problem of pollution from a specific set of existing sources (64 FR 35737). The CAA requires that any of these existing sources “which, as determined by the State, emits any air pollutant which may reasonably be anticipated to cause or contribute to any impairment of visibility [in any Class I area],” shall install the best available retrofit technology for controlling emissions.
In determining BART, the CAA requires the State to consider several factors that are set forth in section 169A(g)(2) of the CAA, including the degree of improvement in visibility which may reasonably result from the use of such technology.
Because the problem of regional haze is caused in large part by the long-range transport of emissions from multiple sources, and for certain technical and other reasons explained in that rulemaking, we had adopted in the 1999 rule an approach that required States to look at the contribution of all BART sources to the problem of regional haze in determining both applicability and the appropriate level of control for BART. Specifically, we had concluded that if a source potentially subject to BART is located in an area from which pollutants may be transported to a Class I area, that source “may reasonably be anticipated to cause or contribute” to visibility impairment in the Class I area. We had also concluded that in weighing the factors set forth in the statute for determining BART, the States should consider the collective impact of BART sources on visibility. In particular, in considering the degree of visibility improvement that could reasonably be anticipated to result from the use of such technology, we stated that the State should consider the degree of improvement in visibility that would result from the cumulative impact of applying controls to all sources subject to BART. We concluded that the States should use this analysis to determine the appropriate BART emission limitations for specific sources.
The 1999 Regional Haze Rule also included provisions in section 51.309 based on the strategies developed by the GCVTC. Certain western States and Tribes were eligible to submit implementation plans under section 51.309 as an alternative method of achieving reasonable progress for those Class I areas covered by the GCVTC's analysis—i.e., the 16 Class I areas on the Colorado Plateau. In order for States and Tribes to be able to utilize this section, however, the rule provided that EPA must receive an “Annex” to the GCVTC's final recommendations. The purpose of the Annex was to provide the specific provisions needed to translate the GCVTC's general recommendations for stationary source sulfur dioxide (SO 2) reductions into an enforceable regulatory program. The rule provided that such an Annex, meeting certain requirements, be submitted to EPA no later than October 1, 2000. See section 51.309(d)(4) and (f) (2000).
American Corn Growers v. EPA ↑
In American Corn Growers, industry petitioners challenged EPA's interpretation of the BART determination process and raised other challenges to the rule. The court in American Corn Growers concluded that the BART provisions in the 1999 Regional Haze Rule were inconsistent with the provisions in the CAA “giving the states broad authority over BART determinations.” 291 F.3d at 8. Specifically, with respect to the test for determining whether a source is subject to BART, the court held that the method EPA had prescribed for determining which eligible sources are subject to BART illegally constrained the authority Congress had conferred on the States. Id. The court did not decide whether the general collective contribution approach to determining BART applicability was necessarily inconsistent with the CAA. Id. at 9. Rather, the court stated that
“[i]f the [Regional Haze Rule] contained some kind of a mechanism by which a state could exempt a BART-eligible source on the basis of an individualized contribution determination, then perhaps the plain meaning of the Act would not be violated. But the [Regional Haze Rule] contains no such mechanism.”
The court in American Corn Growers also found that our interpretation of the CAA requiring the States to consider the degree of improvement in visibility that would result from the cumulative impact of applying controls in determining BART was inconsistent with the language of the CAA. 291 F.3d at 8. Based on its review of the statute, the court concluded that the five statutory factors in section 169A(g)(2) “were meant to be considered together by the states.” Id. at 6.
The final rule promulgated on July 6, 2005 responded to the American Corn Growers court's decision on the BART provisions by amending the Regional Haze Rule at § 51.308 and by finalizingchanges to the BART guidelines at part 51, appendix Y (70 FR 39104). These changes eliminate the previous constraint on State discretion and provide States with appropriate techniques and methods for determining which BART-eligible sources “may reasonably be anticipated to cause or contribute to any impairment of visibility in any mandatory Class I Federal area.” In addition, the revised regulations list the visibility improvement factor with the other statutory BART determination factors in section 51.308(e)(1)(A), so that States will be required to consider all five factors, including visibility impacts, on an individual source basis when making each individual source BART determination, rather than considering the cumulative impacts of all BART sources on visibility (“group BART”).
The Annex Rule ↑
In a rule dated June 5, 2003, EPA approved the WRAP's Annex to the GCVTC report (68 FR 33764). In this action, referred to as the “Annex rule,” EPA approved the quantitative SO 2 emission reduction milestones and the detailed provisions of the backstop market trading program developed by the WRAP as meeting the requirements of section 51.309(f), and therefore codified the Annex provisions in section 51.309(h). Subsequently, five States and one local agency submitted SIPs developed to comply with all of section 51.309, including the Annex provisions at section 51.309(h). In accordance with section 51.309(c) these SIPs were submitted prior to December 31, 2003.
Center for Energy and Economic Development v. EPA ↑
The EPA's approval of the Annex rule was challenged by CEED on, among other grounds, that the CAA prohibits EPA from allowing States to adopt alternative measures, such as a trading program, in lieu of BART. The court, in CEED v. EPA, affirmed our interpretation of section 169A(b)(2) of the CAA as allowing for alternatives to BART where those alternatives are demonstrated to make greater progress than BART. CEED v. EPA, 398 F.3d at 659-660. The court, however, took issue with the methodology that EPA had required the States to use in that demonstration, pursuant to certain provisions of the Regional Haze Rule. As noted above, § 51.308(e)(2) of the 1999 Regional Haze Rule required that visibility improvements under source-specific BART—the benchmark for comparison to the alternative program—must be estimated based on the application of BART controls to all sources subject to BART. This section was incorporated into the WRAP Annex rule by reference at § 51.309(f). The court held that EPA could not require this type of “group BART” approach, which was vacated in American Corn Growers in a source-specific BART context, even in an alternative trading program in which State participation was wholly optional.
The BART guidelines as proposed in May 2004 contained a section offering guidance to States choosing to address their BART-eligible sources under the alternative strategy provided for in § 51.308(e)(2). This guidance included a broad overview of the steps in developing an emissions trading program and criteria for demonstrating that such a trading program would achieve greater progress towards eliminating visibility impairment than would BART. In light of the D.C. Circuit's decision in CEED v. EPA in 2005, we did not include the overview of emissions trading programs in the final BART guidelines. We did note, however, that our authority to address BART through alternative means was upheld in CEED v. EPA and that we remained committed to providing States with that flexibility. Today's revisions to the Regional Haze Rule, which responds to the holding in CEED v. EPA, provide the flexibility that States need to implement alternatives to BART.
Overview of Changes to §§ 51.308(e)(2) and 51.309 of the Regional Haze Rule ↑
The EPA continues to support State efforts to develop trading programs and other alternative strategies to fulfill the goals of the CAA. We believe such strategies have the potential to achieve greater progress towards the national visibility goals than more traditional approaches to regulation, and to do so in the most cost-effective manner practicable. In August 2005, we proposed amendments to the Regional Haze Rule to enable States to continue to develop and implement such programs (70 FR 44154, August 1,2005). Today's rule finalizes these amendments, including changes in response to comments on the proposal.
First, we are amending the generally applicable provisions at § 51.308(e)(2), which prescribe the type of analysis used to determine emissions reductions achievable from source-by-source BART, for purposes of comparing to the alternative program. These amendments reconcile the methodology for determining whether an alternative program is approvable with the court's decision in CEED v. EPA. Today's rule also establishes the minimum elements of an acceptable cap and trade program and provides for consistent application of the BART guidelines for electric generating units (EGUs) between source-by-source programs and alternative cap and trade programs.
Second, we are amending section 51.309 to enable certain western States and Tribes to continue to utilize the strategies contained in the GCVTC report as an optional means to satisfy reasonable progress requirements for certain Class I areas, for the first long-term planning period. These changes provide States and Tribes with an opportunity to revise and resubmit the backstop SO 2 emissions trading program absent any requirement to assess visibility on a cumulative basis when determining the emissions reductions achievable by source-by-source BART.
II. Revisions to Regional Haze Rule § 51.308(e)(2) Governing Alternatives to Source-by-Source BART ↑
In this section of the preamble, we discuss changes or clarifications to the provisions proposed in August, 2005. Where relevant, we also respond to significant comments received during the comment periods on our earlier BART proposals. For each provision that we are changing or clarifying, where relevant, we provide discussion of comments received on the proposal(s), changes or clarifications we are finalizing, and the reasons for these changes or clarifications.
A. Establishing a BART Benchmark and Demonstrating Greater Reasonable Progress Than BART ↑
The Regional Haze Rule provides States with the authority to implement an emissions trading program or other alternative measures in lieu of meeting the requirements for source-by-source BART. Under this provision of the Regional Haze Rule, States have the flexibility to design programs to reduce emissions from stationary sources in a more cost-effective manner so long as they can demonstrate that the alternative approach will achieve greater reasonable progress towards improving visibility than would have been achieved by implementation of the BART requirements.
As described in the preamble to the August proposal, the 1999 Regional Haze Rule had specified a methodology for comparing an alternative trading or other type program against source-by-source BART. These regulations were challenged following a rulemaking by EPA to revise the Regional Haze Rule to incorporate an optional emissions trading program for certain Western States and Tribes (the Annex rule). Thecourt in CEED v. EPA, granted petitioner's challenge to the Annex rule because EPA's regional haze regulations had required the States submitting the Annex to consider “the impact of all emissions reductions to estimate visibility progress” in establishing a BART benchmark against which to compare their BART alternative program. In the August proposal, we proposed to revise the method for comparing an alternative trading or other type program against source-by-source BART. Specifically, we proposed to amend the regional haze regulations to provide that States estimate the emission reductions that could be achieved by BART in the same manner as in making source-by-source BART determinations.
Today's final rule revises section 51.308(e)(2) to make clear that the emissions reductions that could be achieved through implementation of the BART provisions at section 51.308(e)(1) serve as the benchmark against which States can compare an alternative program. In short, to demonstrate that a trading program or other alternative program makes greater reasonable progress than BART, the State can develop an estimate of BART emissions reductions using the same approach that it would use to establish source-by-source BART emissions limitations under the BART guidelines. As discussed in more detail below, today's rule also makes clear that where a trading program or other similar alternative program has been designed primarily to meet a Federal or State requirement other than BART, the State can use a more simplified approach to demonstrating that the alternative program will make greater reasonable progress than BART. Such an approach may be appropriate where the State believes the alternative program is clearly superior to BART and a detailed BART analysis is not necessary to assure that the alternative program will result in greater reasonable progress than BART.
Framework for Demonstrating That an Alternative Program Provides for Greater Reasonable Progress ↑
The development of a BART benchmark using the approach for source-by-source BART determinations will require States to identify those existing sources which are BART-eligible, to determine which of those sources are subject to BART, and to then determine the level of control that would be BART for these sources. Once the State has established a BART benchmark, it can then compare the benchmark against the alternative program it has developed. This approach could entail separate visibility analyses in as many as three distinct stages: (1) Determining which BART-eligible sources are subject to BART; (2) determining what BART is for each source subject to BART; and (3) determining the overall visibility improvement anticipated from the application of BART to all sources subject to BART. The following sections discuss the comments received on the visibility analyses in the first two steps, as well as comments on additional issues for determining which sources are subject to BART and the determination of BART for such sources.
Sources Subject to BART ↑
Proposal. In the proposal, we noted that the BART guidelines finalized on July 6, 2005 provide States with guidance on how to determine which BART-eligible sources are reasonably anticipated to cause or contribute to visibility. The Guidelines explain that States may consider all BART-eligible sources to meet this threshold and therefore subject all these sources to review, or, alternatively, that States may determine which BART-eligible sources are subject to BART using the methods for modeling source specific impacts on visibility discussed in the guidance. We noted that by considering all BART-eligible sources to be subject to BART in the context of setting the BART benchmark, States could ease their administrative burden and maximize the number of BART-eligible sources included in the benchmark analysis. Where a State takes this approach, the opportunity for assessing source-by-source visibility impact would still remain at the next step of setting the benchmark—the BART determination analysis.
Comments. Several commenters stated that allowing States to consider all BART-eligible sources to be “subject to BART” (i.e., subject to a BART determination analysis) is contrary to the CAA as interpreted by the D.C. Circuit in American Corn Growers. Two commenters have indicated that they plan to challenge this provision of the BART guidelines in a petition for review before the D.C. Circuit and are opposed to it in the context of BART alternative programs as well. One of these commenters also stated that it is unclear from the preamble discussion where in the proposed revisions to the regulations this option is authorized.
Final Rule. We are reiterating here, as we pointed out in the proposal, that the language in section 169A(b)(2) of the CAA establishing the threshold for BART review provides a State with the discretion to consider all BART-eligible sources to be subject to BART and to make BART determinations for all its BART-eligible sources. In other words, as noted in the BART guidelines, once a State has identified its BART-eligible sources, it must decide whether (1) to make BART determinations for all of them, or (2) to consider exempting some of them from BART because they may not reasonably be anticipated to cause or contribute to any visibility impairment in any Class I area. As explained in the 1999 Regional Haze Rule, given the nature of regional haze, it would be reasonable for a State to determine that where the State as a whole contributes to visibility impairment at a Class I area, any large stationary source in the State that emits SO 2 or other visibility-impairing pollutants would emit air pollutants that would “reasonably be anticipated to cause or contribute to any impairment of visibility in [any Class I area].” CAA Section 169A(b)(2).
This approach is authorized by the regulations through the cross reference to § 51.308(e)(1) in § 51.308(e)(2). By providing that the BART-benchmark should be established by conducting BART determinations in accordance with § 51.308(e)(1), we provide the State with the same options as are available in those provisions for determining source-by-source BART. In the context of subject-to-BART determinations, this includes either considering all BART-eligible sources to be subject to BART or, using the methods described in the BART guidelines or other reasonable approaches, to exempt sources which the State determines are not reasonably anticipated to cause or contribute to any visibility impairment.
The BART Determination ↑
Proposal. The CAA identifies five factors that States are to consider in making BART determinations. One of these factors is “the degree of improvement in visibility which may reasonably be anticipated to result fromthe use of [BART].” Today's rulemaking, in large part, is focused on how States should handle consideration of this factor in establishing a BART benchmark.
In the proposal, we stated that one way to handle the visibility improvement element of the BART determination for all BART sources covered by the program would be to conduct individualized assessments of the visibility improvement expected from each BART source under various control scenarios, as described in the BART guidelines. We noted that such an approach could impose significant resource burdens on the States and solicited recommendations on more streamlined approaches for estimating BART sources' individual impacts that might be appropriate in the context of assessing alternative programs. One area of consideration that we identified is the type of model used. We requested comment on whether regional scale models might be used to consolidate individual source impact analyses into one or a few model runs, and whether this would significantly ease the burden on States.
In the proposal, we also made clear our belief that in determining whether an alternative program provides for greater reasonable progress than would source-by-source BART, States have the discretion to employ a cumulative visibility analysis for purposes of estimating the potential visibility impacts of BART. Based on our analysis of American Corn Growers and CEED, we stated that although EPA may not require States to use a cumulative visibility approach to estimating the improvement achievable from BART, States are not barred from using such an approach if they so choose.
Finally, in the proposal preamble, we discussed the situation where emissions reductions at BART-eligible sources are required by CAA requirements other than BART (or to fulfill requirements of a State law or regulation not required by the CAA). We noted that in such cases, a State may wish to evaluate whether the emissions reductions from the program would result in greater reasonable progress towards the national visibility goal than would the installation of BART. We noted that EPA had made such a determination with respect to the Clean Air Interstate Rule (CAIR) for EGUs in States which participate in the CAIR cap and trade program.
We noted that such a situation affects the type of analysis that is permissible to show that the alternative program makes greater reasonable progress than BART. Specifically, where a requirement other than BART determines the level of emissions reductions required from BART-eligible sources (along with other sources), a most-stringent case BART may be used as the BART benchmark. (This most-stringent case BART is essentially a form of “group BART,” because is assumes that every BART-eligible source will apply controls). The reason for this is that if it is shown that implementation of another requirement results in greater progress than would the most stringent BART for all the BART-eligible sources, then it can safely be said that this most-stringent-BART benchmark is not the determinative factor in establishing the emission reductions requirement. Therefore, there can be no concern that the group-BART analysis would lead States to adopt an unduly stringent alternative approach.
(1) Types of Models ↑
Comments. The comments submitted supported EPA's proposal that States could use the approach in the Guidelines in making individualized visibility assessments for BART determinations. In response to our request for recommendations for more streamlined approaches to assessing source specific visibility impacts, we received several comments supporting regulations that would allow for this.
One commenter pointed out that streamlined approaches, such as the use of photochemical grid models, would significantly ease the burden on States and Tribes. The commenter also pointed out that § 51.308(e)(1), cross-referenced as the guiding provision for BART determinations in proposed § 51.308(e)(2)(i)(C), does not explicitly recognize streamlined approaches for determining BART. Thus, the commenter believes, EPA should “take care to ensure that a streamlined approach for the purpose of determining [the BART benchmark] is clear, permissible, and not legally unsound in the final rule.”
Another commenter said that a streamlined approach “is an appropriate option that should be explicitly recognized and more fully developed in the final rule.” According to the commenter, either the CMAQ or CAMx regional photochemical models would be suitable for streamlined visibility assessments for BART determinations, but also stated that none of the models is capable of consistently producing unbiased results for all chemical constituents responsible for haze. One State commenter said that States in EPA Region 5 are using the CALPUFF model and it would prefer to continue doing so. The State would not object to allowing other models to be used so long as they are optional.
Another commenter submitted comments detailing the reasons it believes CALPUFF is superior to photochemical grid models for purposes of source-by-source BART analysis. In brief, commenter explained that with grid models, the concentration of pollutants from a point source is automatically diluted evenly across the grid in which the source is located. This dilution effect can be partially redressed by employing smaller grid sizes or by using a hybrid model which employs Lagrangian methods (as used in CALPUFF) close to the source and switches to a grid method farther downstream. However, both of these methods are resource intensive. The commenter therefore believed that CALPUFF, which can use meteorological data bases developed for CMAQ and CAMx, should be the preferred option.
Final Rule. Section 308(e)(1)(ii)(B) requires that, for fossil fuel-fired power plants with a total generating capacity of greater than 750MW, BART determinations be made pursuant to the BART guidelines. With respect to the type of air quality model used for the BART determination, the guidelines instruct States to use CALPUFF or another appropriate dispersion model to determine the visibility improvement expected at a Class I area from the BART control technology being evaluated (70 FR 39170).
We maintain that CALPUFF is the best model currently available for predicting visibility impacts from single sources. The use of regional scale photochemical grid models may have merit, but to date, such models have not been evaluated for single source applications (70 FR 39123). As the science and structure of regional photochemical grid models are improved and demonstrated to successfully predict impacts from single sources (e.g. plume in gri