MODEL CLEARINGHOUSE: FY-94 SUMMARY REPORT NOVEMBER 1994 Source Receptor Analysis Branch Technical Support Division Office of Air Quality Planning and Standards U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711 TABLE OF CONTENTS MODEL CLEARINGHOUSE: FY-94 SUMMARY REPORT PAGE 1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . 1 2.0 FY-94 CLEARINGHOUSE ACTIVITIES . . . . . . . . . . . . . . . 2 2.1 Background and Responsibilities . . . . . . . . . . . . 2 2.2 Summary of Regional Office Requests and Clearinghouse Responses . . . . . . . . . . . . . . . . . . . . . . . 4 2.3 Recurring Coordination . . . . . . . . . . . . . . . . 4 2.4 Support Center for Regulatory Air Models Bulletin Board System (SCRAM BBS) . . . . . . . . . . . . . . . 5 3.0 SIGNIFICANT ISSUES FROM REGIONAL OFFICE REFERRALS AND CLEARINGHOUSE RESPONSES . . . . . . . . . . . . . . . . . . 7 3.1 Building Wake Effects on Volume Sources . . . . . . . . 7 3.2 Technical Comparison: Model Performance Evaluation Protocol . . . . . . . . . . . . . . . . . . . . . . . . 8 3.3 Wind Tunnel Modeling: Stable Plume Impaction on Elevated Terrain During Stable Stratification . . . . . 9 3.4 Wind Tunnel Modeling: Equivalent Building Dimensions for Input to the Industrial Source Complex (ISC2) Model . . . . . . . . . . . . . . . . . . . . . 10 3.5 Modeling Highest versus Second-Highest Episode Day for CO Attainment Demonstration . . . . . . . . . . . . 11 3.6 Methodology to Identify "Nearby" Background Sources for Inclusion in Modeling Emission Inventory for a Prevention of Significant Deterioration (PSD) Compliance Demonstration . . . . . . . . . . . . . . . 13 3.7 Wind Tunnel Modeling for a Mixed-Mode Dispersion Modeling Analysis . . . . . . . . . . . . . . . . . . . 14 Appendix A FY-94 MODEL CLEARINGHOUSE MEMORANDA . . . . . . . . . A-1 Appendix B MODEL CLEARINGHOUSE CONTACTS . . . . . . . . . . . . B-1 Appendix C SUMMARY OF THE EPA MODEL CLEARINGHOUSE . . . . . . . C-1 1.0 INTRODUCTION This report summarizes major activities of the Model Clearinghouse from September 1, 1993 to August 31, 1994. The report is divided into two parts. First, the FY-94 activities of the Clearinghouse are summarized. The second section summarizes Clearinghouse responses to major categorical modeling problems occurring during FY-94; within each of these there were several issues/questions of a similar nature. Appendix A provides a list of Model Clearinghouse memoranda covering the period October 1, 1993 to September 30, 1994. Appendix B contains a list of EPA Model Clearinghouse contact personnel. Appendix C provides a brief summary of the EPA Model Clearinghouse responsibility, structure and operational procedures. 2.0 FY-94 CLEARINGHOUSE ACTIVITIES 2.1 Background and Responsibilities The Model Clearinghouse was established on November 20, 1980. The Regional Offices were notified of its general purposes, procedures and limitations on that date. A detailed operational plan describing the functions, structure, procedures, and schedule for implementation was issued on February 25, 1981. Initially the operation of the Model Clearinghouse was limited to the review of proposed deviations from modeling guidance for the regulatory modeling of iron/steel facilities, smelters, and power plants. As such, the reviews were usually limited to sulfur dioxide (SO2), total suspended particulates (TSP), and lead (Pb). On a gradual basis the limitation to these facilities was relaxed to the point where the Clearinghouse, by the mid- 1980's, was accepting referrals for all point sources of stable pollutants. Beginning in 1986, the Clearinghouse began accepting referrals for mobile source problems involving carbon monoxide (CO). During FY-88, the Model Clearinghouse was expanded to cover ozone (O3) and nitrogen dioxide (NO2). A revised Model Clearinghouse operational plan* was issued to reflect that the Model Clearinghouse purview includes all criteria pollutants. During FY-92, the Clearinghouse operation was further expanded to include noncriteria (toxic) pollutants. The Model Clearinghouse Operational Plan states that the primary purposes of the Model Clearinghouse are to provide: 1. A mechanism whereby the proposed acceptance by a Regional Office of a nonguideline model or alternative technique can be reviewed for ______________________ *Model Clearinghouse: Operational Plan, Revised, Source Receptor Analysis Branch, Office of Air Quality Planning and Standards, May 1988 national consistency before final approval by the Regional Administrator. Such reviews promote the use of equivalent acceptance criteria by all Regions. 2. A mechanism whereby the in-depth technical evaluation and/or performance evaluation of a proposed technique can be reviewed by those EPA personnel who are most familiar with the types of techniques to be employed. 3. A communication outlet for EPA's experience with the use of nonguideline models, data bases or other deviations from current guidance. The Clearinghouse maintains a high level of expertise on the applicability of various models and classes of models and allowed deviations from accepted procedures in specified circumstances. This information is communicated on a periodic basis to EPA personnel involved in regulatory model applications. The Clearinghouse is formally located in the Source Receptor Analysis Branch (SRAB) of the Office of Air Quality Planning and Standards (OAQPS). However, the Air Quality Management Division (AQMD) also participates in Clearinghouse matters involving State implementation plan (SIP) attainment strategies and other regulatory functions. The primary responsibility for managing the Clearinghouse and ensuring that all of its functions are carried out is performed by a person full-time within SRAB. A Clearinghouse support person in SRAB maintains the Clearinghouse's electronic communications interface through the computerized data base and bulletin board systems described below. The responsibility for responding to requests for review of modeling issues is assigned, on a pollutant/program basis to SRAB experts. In addition, AQMD supports the Clearinghouse with staff who are also knowledgeable in modeling policy. These individuals are responsible for screening SIP submittals and related documents, referring modeling issues to SRAB through the Clearinghouse, and documenting the final (and any significant interim) decision on disposition of the issues. A current list of OAQPS and Regional Office Model Clearinghouse contacts is provided in Appendix B. The FY-94 activities for the Model Clearinghouse included: 1. Responding to Regional Office requests for review of nonguideline models proposed for use. 2. Reviewing draft and formally submitted Federal Register actions. 3. Documenting Clearinghouse decisions and discussions. 4. Summarizing Clearinghouse activities at various meetings. 5. Issuing, internally, a summary report for activities of FY-93. 6. Inputting FY-94 Clearinghouse records into a computerized data base. 7. Providing for Regional Office direct access to the computerized data base by modem. 8. Disseminating Clearinghouse memoranda and reports to the public through a bulletin board system. 2.2 Summary of Regional Office Requests and Clearinghouse Responses There were a total of 12 regulatory modeling problems referred to the Clearinghouse which required a written response and another 51 referrals in which the issues were discussed orally. In addition, there were numerous other inquiries to the Clearinghouse regarding procedures, technical considerations, and policies which were readily resolved or referred elsewhere. Requests for assistance, either written or by telephone, came from all of the Regional Offices. 2.3 Recurring Coordination During FY-94, the Clearinghouse conducted or participated in a number of activities that can be categorized as coordination and information exchanges with the Regional Offices. One of the first activities was to prepare and distribute to the Regional Offices in October 1993, a Clearinghouse report; this report served to inform Clearinghouse users about the issues and responses which occurred in FY-93. The report included summaries of generic issues which occurred during the fiscal year. During FY-94, the Clearinghouse continued its policy of sending copies of its written responses (along with incoming requests) to all the Regional Offices. In this way, the Regional Offices are made aware, in a timely fashion, of decisions that may affect their modeling activities. Also, in order for the Regions to be assured that their records are complete, the Clearinghouse attaches to each response, an updated list of all Clearinghouse memoranda issued during the fiscal year. The complete list for FY-94 is provided as Appendix A. During FY-94, the Clearinghouse continued inputting records of Regional Office referrals to the Model Clearinghouse Information Storage and Retrieval System (MCHISRS). During FY-94, the Clearinghouse added approximately 63 entries to the approximately 1186 FY-81 to FY-93 referrals into MCHISRS. The Regional Offices can access by modem the MCHISRS in a search and retrieve mode for any national precedents that might affect their position on a current specific modeling issue. The Model Clearinghouse has a policy whereby an advance opinion of the Regions is sought on particularly sensitive issues with national implications. During FY-94, one such case arose. This involved the use of wind tunnel modeling to determine equivalent building dimensions for input to the Industrial Source Complex (ISC2) model. The resolution of this issue is documented under "Current Year Memos" on the Support Center for Regulatory Air Models Bulletin Board System (SCRAM BBS). Additional information on the Clearinghouse response on this issue is provided in Sections 3.4. 2.4 Support Center for Regulatory Air Models Bulletin Board System (SCRAM BBS) During FY-91, EPA began disseminating Agency memoranda and reports generated by the Clearinghouse to the public through the SCRAM BBS. Three types of information are included: 1) selected historical memoranda on generic/recurring issues that have been generated by the Clearinghouse in the FY-81 through FY-94 time frame; 2) the most recent, i.e., FY-89 through FY-94 Clearinghouse memoranda; and 3) the FY-89 through FY-93 Model Clearinghouse annual reports. Information on the SCRAM BBS is not intended to be a complete set of information relative to any subject. Rather, it serves as a means to communicate to regulatory model users significant decisions involving the interpretation of current modeling guidance and experience with the use of nonguideline models, data bases and other deviations from the current guidance. The SCRAM BBS cautions users to consult the Guideline on Air Quality Models (Revised) and contact the appropriate State or Regional Office before using the information for individual/regulatory applications. As new Clearinghouse information becomes available, it is placed on the bulletin board in one of the three categories mentioned above. However, in regard to the current year Model Clearinghouse memoranda, a one to two month delay occurs before the information is placed on the bulletin board. 3.0 SIGNIFICANT ISSUES FROM REGIONAL OFFICE REFERRALS AND CLEARINGHOUSE RESPONSES. During FY-94, the Clearinghouse responded to a number of queries/referrals which had common themes or common consistency/technical issues. The more significant issues and their resolution are described below. 3.1 Building Wake Effects on Volume Sources In November, 1993, The Clearinghouse reviewed a referral from Region X requesting concurrence on a procedure that considers building wake effects on emissions from volume sources. The Region was assisting the Fort Hall Reservation in developing a PM10 Implementation Plan. Several operations at one corporation were best characterized as volume sources for dispersion modeling purposes. Some of these volume sources were very near large building where wake effects could influence the dispersion of PM10 emissions. The Region noted that current Agency guidance is incomplete regarding the treatment of building wake effects on the dispersion of volume source emissions. The user is typically referred to Table 1-6 of Volume II of the ISC2 User's Guide to derive initial lateral and vertical dimensions (i.e., sigma y0, sigma z0) for volume sources. The recommendations for sigma y0 presented in Table 1-6 do not provide a means for estimating building effects on the initial lateral dispersion. Also, while Table 1-6 does provide a building-height estimator for initial vertical dispersion (sigma z0) for sources located on or adjacent to a building, there is no definition of "adjacent". The Region noted that Agency guidance is clear concerning the evaluation of building wake effects for point sources located near a building. However, these building wake effects are not considered for volume sources. The Region suggested that the area of building wake effects currently defined by the Agency for point sources should also be revised to address these wake effects on all affected sources consistently. Therefore, the Region recommended the following criteria for the facility located on the Fort Hall Reservation. 1. "Adjacent" as applied to Table 1-6 of Volume II would be defined as any source located within the wind direction dependent area of building wake influence (defined in Section 1.1.5.3 of Volume II). For volume sources, if 50 percent or more of the volume source is determined to be adjacent to a building, the entire source will be modeled as an adjacent source. 2. The Region provided additional criteria for specifying initial plume dimensions for the "adjacent" volume sources. This information was intented to supplement the criteria contained in Table 1-6 of Volume II. In response, the Clearinghouse concurred with the Region's recommended approach for modeling the source under review only. It was noted that the criteria seemed most appropriate for volume sources comparable to the size of the downwashing building. Usage of these criteria for volume sources much smaller than the building may not be appropriate. However, for the source under review, it appeared this scenario did not occur. It was noted these criteria could not be recommended for generic use since an extensive peer and public technical review had not been done. 3.2 Technical Comparison: Model Performance Evaluation Protocol Region VI verbally requested Clearinghouse review of a revised draft Technical Comparison Document (TCD) for a model performance evaluation. The revised draft contained responses to the Region's and Clearinghouse comments on a previous draft TCD. The Clearinghouse noted that the responses to the comments on the previous draft appeared to be adequately addressed in the revised draft. However, it was noted that several additional changes were proposed in the revised draft for which the Clearinghouse provided additional comments. The Clearinghouse noted that the previous TCD contained a comparison of a new model with an EPA reference model. The revised draft contained a comparison of the new model with the reference model plus two alternative EPA models. Also, it was noted that alternative operational modes of the new model would be applied in the performance evaluation. The Clearinghouse recommended that the two alternative EPA models be dropped from contention in the evaluation as neither one represented an EPA recommended model for the modeling scenario. Also, it was commented that only one operational mode of the new model be used in the evaluation. The Regional Office transmitted the Clearinghouse and Regional Office comments to the source. In response, the source agreed to remove one of the alternative models in the evaluation. However, the source requested that the other alternative model be retained because of some noted characteristics of the source and ambient concentrations for which the alternative model might be viable. Also, the source agreed to use one operational mode of the new model in the evaluation. The Clearinghouse and Regional Office agreed to include one additional model in the evaluation because of the information provided by the source. All other aspects of the model evaluation protocol were found acceptable. 3.3 Wind Tunnel Modeling: Stable Plume Impaction on Elevated Terrain During Stable Stratification Region IV requested Clearinghouse review and comment on a protocol for wind tunnel modeling of plume impaction on elevated terrain under stable stratification. Preliminary modeling indicated predicted exceedances of the SO2 NAAQS on elevated terrain under stable atmospheric conditions. Thus, the applicant proposed a wind tunnel study to assess the plume impact on complex terrain under the stable conditions. The Clearinghouse reviewed the protocol, however, it was noted that a complete technical review of the wind tunnel methodology was not done. The Clearinghouse reviewed and generally agreed with the Region's draft comments on the protocol. Several additional comments were also provided as described next. The Clearinghouse noted that a more complete description was needed for applying the wind tunnel concentration estimates for the SO2 National Ambient Air Quality Standards (NAAQS) compliance demonstration. Also, there was no mention of developing concentration estimates from the wind tunnel for other meteorological conditions for the compliance demonstration. It was unclear whether a refined modeling analysis was contemplated for this study. If so, there was no description of how the complex terrain modeling would be done (i.e., intermediate terrain, terrain above plume height, etc.) Aside from several comments from the Clearinghouse and Region IV concerning procedural issues, the primary focus of concern was the technical aspects of the wind tunnel study. There were several technical issues raised concerning the capability and uncertainty of the wind tunnel to simulate plume impaction under stable conditions. Of primary concern was the difficulty to configure the wind tunnel to simulate the stable atmosphere such that a reasonable representation of plume dispersion and impaction could be obtained. It was noted several technical issues had to be overcome before any confidence in the tunnel simulation could be obtained. Thus, it was concluded that until further research is conducted, a wind tunnel study of plume impaction under stable stratification would likely not be acceptable. 3.4 Wind Tunnel Modeling: Equivalent Building Dimensions for Input to the Industrial Source Complex (ISC) Model Two additional Clearinghouse responses to the Regional Offices also were concerned with wind tunnel modeling demonstrations. These addressed the concept of deriving direction-specific "equivalent building dimensions" for input to the Industrial Source Complex (ISC2) model downwash algorithm. The premise being that for complex building structures or sites and using standard techniques to develop the building input parameters for ISC2, the downwash effects may be overestimated, thus potentially resulting in unrealistically high ground-level concentration predictions. In these tunnel studies, the wind tunnel is used to first derive direction-specific downwind concentration profiles with actual site structures in place. The structures are then removed and a simplified solid structure is placed in the tunnel. The simplified solid structure dimensions that most closely match the concentration profiles with all site structures in place - according to prescribed criteria - are selected for input to the ISC2 model. The acceptance of this concept was initially discussed in an April, 1994 conference call with the Regional Modeling Contacts. After further discussions, it was concluded that these wind tunnel demonstrations were considered source characterization studies which generally had been under the purview of the Regional Offices. Thus, it was concluded that these studies did not constitute an application of an alternative modeling technical subject to the requirements of Section 3.2 of the Guideline on Air Quality Models. Most of the concerns of the Regional Offices dealt with the technical review of the wind tunnel protocols. It was recognized that more technical information on wind tunnel modeling techniques was needed to adequately review these protocols. Subsequently, a list of technical issues was developed with input from the Regional Offices and State agencies concerning the protocol review. These issues were discussed in meeting with industry, EPA Regional Office, State and Office of Air Quality Planning and Standards staff. Based on this meeting and subsequent discussions within the Agency, information concerning these issues was provided in a July 25, 1994 memorandum to Region IV. In the memorandum, it was noted that it was premature to issue generic guidance on how to conduct wind tunnel studies for equivalent building dimensions determination. Much of the information provided on the technical issues was based on recent experience and continued to evolve. It was anticipated that as more experience is gained throught the review and application of these wind tunnel protocols and demonstrations, more specific guidance could be provided. 3.5 Modeling Highest versus Second-Highest Episode Day for CO Attainment Demonstration In a February 1994 memorandum to John Seitz, Director, Office of Air Quality Planning and Standards, Region VIII requested a written opinion on the Region's position that the highest monitored episode day was appropriate for the Denver area CO SIP attainment demonstration. Background The Denver area was classified as a moderate nonattainment area for CO. The Urban Airshed Model (UAM) was selected for the SIP CO attainment demonstration. Also, in an Regional Office-approved modeling protocol, the State and local agency agreed to model the three highest monitored episode days for the attainment demonstration. Because of time and resource constraints, only the two highest episode days were to be modeled. The UAM modeling for the highest day indicated a 28% regional reduction in CO emissions would be needed to show attainment by the 1995 attainment date for a moderate area. For the second highest day a much less costly two percent reduction would be needed. The local air quality agency contested that there was an inconsistency in the EPA guidance for UAM episode selection for the attainment demonstration and guidance for determining a monitored "design day" concentration. The former does not allow any exceedances on the modeled episode days while the latter allows one monitored exceedance. Since the attainment status was based on the second highest monitored exceedance, the local agency contested that showing attainment was necessary only on the second highest episode day. Also, the local agency asserted that the highest episode day contained anomalous meteorological conditions and should not be considered in determine control requirements for attainment. The local agency's main concern was the high potential for costly overcontrol due to EPA's inflexibility on episode day modeling. The Region outlined their position in a Technical Support Document. In it, the Region believed that the requirement to model both episode days was consistent with national guidance for UAM demonstrations for CO. Also, The Region's review of meteorological and monitored CO data indicated that more severe meteorological conditions existed than the conditions represented in the two episode days such that the meteorological conditions for the two episode days could not be considered anomalous. The Region also conducted saturation monitoring which showed evidence that the existing monitors may not be located at the point for maximum CO concentrations. This further supported the position that the episode days were not anomalous. Another analysis conducted by the Region compared emissions rollback with UAM modeling results at a monitoring site. This indicated that the UAM modeling may underestimate the control requirements for achieving the CO standard at that monitoring site. Finally, the Region showed that the downward trend in CO maximum measured concentrations has leveled off over the last five years. Thus, it seemed evident that attainment of the CO standards was not likely by December, 1995 and that additional emission reductions would be necessary to achieve attainment by 2000. The Clearinghouse responded to the Region's request in a memorandum which indicated support for the Region's position on the CO attainment demonstration to not allow any modeled exceedances for any of the episode days. The episode selection was in accordance with the 1992 Guideline for Regulatory Application of the Urban Airshed Model for Areawide Carbon Monoxide. Also it was noted that a large number of the highest episode days would need to be modeled to ensure the highest and second-highest days were included. Thus, eliminating the highest day when only two days were being modeled can not be justified. In a separate memorandum to Region VIII from John Seitz, Director, OAQPS, the Region's position was also supported. In this memorandum, it was noted that the Region's Technical Support Document further supported a consistent application of regulatory modeling guidance, advocated by the Region, to ensure timely attainment of the CO ambient standards. 3.6 Methodology to Identify "Nearby" Background Sources for Inclusion in Modeling Emission Inventory for a Prevention of Significant Deterioration (PSD) Compliance Demonstration. In March 1994, Region II requested Clearinghouse review and concurrence on a methodology to more objectively determine the "nearby" sources to be included in the modeling inventory for a Prevention of Significant Deterioration (PSD) NAAQS compliance demonstration. The Region supported, with some modifications, the New York Department of Environmental Conservation (NYSDEC)'s submittal which included the methodology proposed by the applicant. The Clearinghouse responded that, with some clarifications and suggestions incorporated, it concurred with the Region's position that the methodology appeared to be acceptable. The primary reason for its acceptability was that once the objective technique is applied, professional judgement would be used to ensure proper selection of the sources to be included in the modeling. Also, the Clearinghouse noted that while this technique may be useful in future applications for setting a single source emission limit, other techniques may also be considered. It was noted the recommended method for implementing the guidance for selecting nearby sources in the modeling is to make the final selection on a case-by-base basis using acceptable techniques and professional judgement. 3.7 Wind Tunnel Modeling for a Mixed-Mode Modeling Analysis In June 1994, Region VII requested Clearinghouse review/concurrence on a wind tunnel protocol for a mixed-mode (i.e., directionally-dependent urban/rural classification) dispersion modeling analysis. The Region provided comments on the protocol and also noted that it intended to advise the State that a field study was necessary to supplement the companies' wind tunnel study. The Clearinghouse agreed with the Region's position that a field study was needed to confirm the performance of any alternative modeling techniques developed from the wind tunnel demonstration for other than near neutral conditions. Also it was noted that if a "mixed model" dispersion modeling analysis was planned for compliance demonstration, this would likely be considered an alternative modeling technique. Consequently, a model performance evaluation would also be needed. APPENDIX A FY-94 MODEL CLEARINGHOUSE MEMORANDA A-1 APPENDIX B MODEL CLEARINGHOUSE CONTACTS B-1 OAQPS CONTACTS Division Name Number Responsibility Emissions, Monitoring Dennis Doll 919-541-5693 Clearinghouse and Analysis Contact Division Dennis Doll 919-541-5693 SO2, PM, Pb, NO2 Modeling Ellen Baldridge 919-541-5684 O3 Modeling Tom Braverman 919-541-5383 CO Modeling Tom Coulter 919-541-0832 Receptor Modeling Joe Touma 919-541-5381 Toxics Modeling Air Quality Gary Blais 919-541-3223 SO2, PM-10, Strategies and Pb SIPs Standards Division Doug Grano 919-541-3292 O3, NO2 SIP's Dan DeRoeck 919-541-5593 PSD/NSR for all criteria pollutants Carla Oldham 919-541-3347 CO SIP's B-2 REGIONAL MODELING CONTACTS Region Regional Contact Telephone No. I Brian Hennesey 617-565-3223 Matt Cairns 617-565-4992 Ian Cohen 617-565-4982 Robert Judge 617-565-3233 II Robert Kelly 212-264-2551 Annamaria Colecchia 212-264-4939 Bill Barrett 212-264-2335 Henry Feingersh 212-264-7669 III Todd Ellsworth 215-597-2906 Al Cimorelli 215-597-6563 Larry Budney 215-597-7661 Tom Casey 215-597-2746 Ruth Knapp 215-597-8375 IV Brenda Johnson 404-347-3555 ext. 4187 Doug Deakin 404-347-3555 ext. 4188 Jackie Lewis 404-347-3555 ext. 4188 V Randy Robinson 312-353-6713 Pamela Blakely 312-886-4447 Sheila Breen 312-886-6053 Mary Onischak 312-353-5954 John Summerhays 312-886-6067 VI Quang Nguyen 214-665-7238 VII Richard Daye 913-551-7619 Royan Teter 913-551-7609 VIII Kevin Golden 303-293-0955 Shawn McCaffrey 303-293-0958 IX Carol Bohnenkamp 415-744-1298 Scott Bohning 415-744-1293 X Rob Wilson 206-553-1531 Bill Ryan 206-553-8561 B-3 CO CONTACTS Region Regional Contact Telephone No. I Donald Cooke 617-565-3227 II Henry Feingersh 212-264-7669 III Larry Budney 215-597-0545 IV Yasmin Yorker 404-257-2864 V Randy Robinson 312-353-6713 VI Quang Nguyen 214-655-7238 VII Royan Teter 913-551-7609 VIII Kevin Golden 303-293-0955 IX Carol Bohnenkamp 415-744-1298 X Bill Ryan 206-553-8561 OZONE MODELING CONTACTS Region Regional Contact Telephone No. I Ian Cohen 617-565-3229 II Robert Kelly 212-264-2551 III Todd Ellsworth 215-597-2906 IV Brenda Johnson 404-347-2864 V Ed Doty 312-886-6030 VI Quang Nguyen 214-655-7238 VII Royan Teter 913-551-7609 VIII Kevin Golden 303-293-0955 IX Carol Bohnenkamp 415-744-1298 X Rob Wilson/Dave Bray 206-553-1531 RECEPTOR MODEL CONTACTS Region Regional Contact Telephone No. I Brian Hennesey 617-565-3223 II Marlon Gonzales 212-264-2517 III Tom Casey 215-597-2906 IV Brenda Johnson 404-347-2864 V John Summerhays 312-886-6067 VI Quang Nguyen 214-655-7238 VII Richard Daye 913-551-7619 VIII Dale Wells 303-293-0957 IX Barbara Bates 415-744-1239 X Rob Wilson 206-553-1531 B-4 APPENDIX C SUMMARY OF THE EPA MODEL CLEARINGHOUSE C-1 EPA Model Clearinghouse Summary The Model Clearinghouse is the single EPA focal point for reviewing the use of modeling techniques in specific regulatory applications. The Clearinghouse also serves to compile and periodically report for Regional Office benefit Agency decisions concerning deviations from the requirements of the Guideline on Air Quality Models (Revised) (Guideline). Need for the Model Clearinghouse The Guideline states that when a recommended model or data base is not used, the Regional Administrator may approve the use of other techniques that are demonstrated to be more appropriate. However, there is also a need to provide for a mechanism that promotes fairness and consistency in modeling decisions among the various Regional Offices and the States. The Model Clearinghouse promotes this fairness and uniformity and also serves as a focal point for technical review of "nonguideline" techniques proposed for use/approval by a Regional Administrator. Functions of the Model Clearinghouse The major function of the Clearinghouse is to review specific proposed actions which involve interpretation of modeling guidance, deviations from strict interpretation of such guidance and the use of options in the guidance, e.g., Regional Office acceptance of nonguideline models and data bases. This is handled in two ways: (1) the Clearinghouse, on request from the Regional Office, will review the Region's position on proposed (specific case) use of a nonguideline model for technical soundness and national consistency, and (2) the Clearinghouse will screen Federal Register regulatory packages for adherence to modeling policy and make recommendations for resolution of any issues identified. A secondary function of the Model Clearinghouse is to communicate to regulatory model users in EPA significant decisions involving the interpretation of modeling guidance. This is accomplished through an annual "Clearinghouse Report" which itemizes the significant decisions that have been made and the circumstances involved. This report serves to improve consistency in future decisions and as a source of technical information for the Regional Offices. In addition to the annual report the Clearinghouse informs users on a contemporary basis of significant decisions through copies of written decisions and briefings at various meetings and workshops; the public has access to Agency memoranda and reports through an EPA electronic bulletin board system. Structure of the Clearinghouse The Clearinghouse is formally located in the Source Receptor Analysis Branch (SRAB) of the Office of Air Quality Planning and Standards. However, the Air Quality Management Division (AQMD) also participates in Clearinghouse matters involving State Implementation Plan attainment strategies and other regulatory functions. The primary responsibility for managing the Clearinghouse and ensuring that all of its functions are carried out is performed by a person full-time within SRAB. The responsibility for responding to requests for review of modeling issues is assigned, on a pollutant/program basis to four SRAB individuals. In addition, AQMD supports the Clearinghouse with staff who are also knowledgeable in modeling policy. These individuals are responsible for screening SIP submittals and related documents, referring modeling issues to SRAB through the Clearinghouse and documenting the final (and any significant interim) decision on disposition of the issues. Communication Chain The Model Clearinghouse functions within the organizational structure of EPA. As such the Clearinghouse serves the EPA Regional Offices. It coordinates with and communicates decisions to the Regional Offices. Any coordination with State and local agencies and individual sources on Clearinghouse activities is a function of the EPA Regional Offices. C-2