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Proposed Rule

Requirements for Preparation, Adoption, and Submittal of State Implementation Plans (Guideline on Air Quality Models); Conference on Air Quality Modeling

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Environmental Protection Agency (EPA).


Proposed rule; conference.


We announce the Seventh Conference on Air Quality Modeling. Such a conference is required by Section 320 of the Clean Air Act (CAA) to be held every 3 years. The purpose of the Seventh Conference is to provide a forum for public review and comment on proposed revisions to the Guideline on Air Quality Models—“Guideline” published on April 21, 2000. The proposed revisions are based on our review and analyses of comments received at the Sixth Conference on Air Quality Modeling, held in August 1995.


The seventh conference will be held on June 28, 2000 from 9 a.m. to 5:30 p.m. and on June 29, 2000 from 8:30 a.m. to 5 p.m. Requests to speak at the conference should be submitted to the individual listed below by June 15, 2000. All written comments must be submitted by close of business August 21, 2000.


Conference: The conference will be held in the EPA Auditorium, 401 M Street, S.W., Washington, D.C.

Comments: Written statements or comments not presented at the conference should be submitted (in duplicate if possible) to: OAR Regulatory Docket (6102), Room M-1500, Waterside Mall, Attention: OAR Regulatory Docket A-99-05, U.S. Environmental Protection Agency, 401 M Street, S.W., Washington, D.C. 20460. We invite you to submit adverse or critical comments pertinent to the proposal to that docket. The docket is available for public inspection and copying between 8:00 a.m. and 5:30 p.m., Monday through Friday, at the address above. Please furnish duplicate comments to Tom Coulter, Air Quality Modeling Group (MD-14), U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. You may send electronic versions of comments pertinent to the proposal to: Alternatively, comments are acceptable in WordPerfect 6.1 (or higher), preferably zipped (e.g., WinZip) as an attachment to the e-mail message. You must include the docket identification (A-99-05) with all electronic submittals. You may file electronic comments on this proposal online at many Federal Depository Libraries.

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C. Thomas Coulter, Air Quality Modeling Group (MD-14), Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711; telephone (919) 541-0832.

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The Guideline (appendix W to 40 CFR part 51) is used by EPA, States, and industry to prepare and review new source permits and State Implementation Plan revisions. The Guideline serves as a means by which consistency is maintained in air quality analyses. We originally published the Guideline in April 1978 and it was incorporated by reference in the regulations for the Prevention of Significant Deterioration (PSD) of Air Quality in June 1978. We revised the Guideline in 1986, and updated it with supplement A in 1987, supplement B in July 1993, and supplement C in August 1995. We published the Guideline as appendix W to 40 CFR part 51 when we issued supplement B. We republished the Guideline in August 1996 (61 FR 41838) to adopt the CFR system for labeling paragraphs.

To support the process of developing and revising the Guideline during the period 1977-1988, we held the First, Second and Third Conferences on Air Quality Modeling as required by Section 320 of the Clean Air Act to help standardize modeling procedures. These modeling conferences provided us with comments on the Guideline and associated revisions, thereby helping us introduce improved modeling techniques into the regulatory process.

In October 1988, we held the Fourth Conference on Air Quality Modeling. Its purpose was to advise the public on new modeling techniques and to solicit comments to guide our consideration of any rulemaking needed to further revise the Guideline. The new models provided techniques for situations where specific procedures had not previously been available, and also improved several previously adopted techniques.

We held the Fifth Conference on Air Quality Modeling in March 1991, which served as a public hearing for the proposed supplement B revisions to the Guideline (op. cit.). Since the Fifth Conference and the adoption of supplement C, we believed it was time to consider a wide range of modeling issues in order to update our available modeling tools with state-of-the-science techniques. We thus held the sixth conference as an ideal forum for airing these issues and for the public to offer new ideas. We reviewed and analyzed the public feedback from the sixth conference, and placed a summary in the docket (II-G-01). This information served as a foundation for the proposed Guideline revision we announced on April 21, 2000 (65 FR 21506). Start Printed Page 31859

To review support documents and data for our proposal, and to prepare for the seventh conference, you may obtain technical materials from several sources. You may get copies of some materials from the docket (see ADDRESSES). We have uploaded many materials, for example essential codes, preprocessors, utilities, test cases, and user's manuals for the new modeling systems, to our website (​scram001;​ see 7th Conference).

Public Participation

The Seventh Conference on Air Quality Modeling will be open to the public; no admission fee is charged and there is no formal registration. The conference will begin the first morning with introductory remarks by the presiding EPA official. The conference will continue with prepared presentations on several key modeling systems: The development of an enhanced Gaussian dispersion model with boundary layer parameterization (AERMOD [1] ); the development of the CALPUFF modeling system by Earth Tech, Inc. under the auspice of the Interagency Workgroup on Air Quality Modeling (IWAQM [2] ); the development and testing of ISC-PRIME by the Electric Power Research Institute's building downwash program; and revisions to the Emissions and Dispersion Modeling System (EDMS) by the Federal Aviation Administration. There will also be presentations on several models for consideration as “alternative models” for case-by-case application.

The second morning, there will be critical reviews/discussions of the new modeling systems facilitated first by the American Meteorological Society's Committee on Meteorological Aspects of Air Pollution, and then by the Air & Waste Management Association's AB-3 Committee. We also plan to feature a special panel presentation on the next generation of air quality models that may be driven by output from four-dimensional prognostic models. This will be followed by statements from representatives of State and local air pollution control agencies and by appropriate Federal agencies. The conference will then be opened to statements and comments from the general public. As information develops, we will post an agenda for the conference on our website (​scram001;​ see 7th Conference).

For the new models and modeling techniques described on June 28th, EPA will be asking the public to address the following questions:

  • Has the scientific merit of the models presented been established?
  • Are the models' accuracy sufficiently documented?
  • Are the proposed regulatory uses of individual models for specific applications appropriate and reasonable?
  • Do significant implementation issues remain or is additional guidance needed?
  • Are there serious resource constraints imposed by modeling systems presented?
  • What additional analyses or information are needed?

Those wishing to speak at the conference, whether to volunteer a presentation on a special topic or to offer general comment on any of the modeling techniques scheduled for presentation, should contact us at the address given in the FOR FURTHER INFORMATION CONTACT section no later than June 15, 2000. Such persons should identify the organization (if any) on whose behalf they are speaking and the length of presentation. If a presentation of general comments is projected to be longer than 10 minutes, the presenter should also state why a longer period is needed. Persons failing to submit a written notice but desiring to speak at the conference should notify the presiding officer immediately before the conference and they will be scheduled on a time-available basis.

The conference will be conducted informally and chaired by an EPA official. There will be no sworn testimony or cross examination. A verbatim transcript of the conference proceedings will be produced and placed in the docket. Speakers should bring extra copies of their presentation for inclusion in the docket and for the convenience of the reporter. Speakers will be permitted to enter into the record any additional written comments that are not presented orally. Additional written statements or comments should be sent to the OAR Regulatory Docket (see ADDRESSES section). A transcript of the proceedings and a copy of all written comments will be maintained in Docket A-99-05 which will remain open until August 21, 2000 for the purpose of receiving additional comments.

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Dated: May 9, 2000.

Bob Perciasepe,

Assistant Administrator for Air and Radiation.

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1.  AMS/EPA Regulatory MODel; AERMOD is being developed by AERMIC: AMS/EPA Regulatory Model Improvement Committee.

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2.  IWAQM was formed in 1991 to provide a focus for development of technically sound regional air quality models for regulatory assessments of pollutant source impacts on federal Class I areas. IWAQM is an interagency collaboration that includes efforts by EPA, U.S. Forest Service, National Park Service, and Fish and Wildlife Service.

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[FR Doc. 00-12390 Filed 5-18-00; 8:45 am]