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Overview of Dispersion Modeling in Air Permitting Arizona Department of Environmental Quality

Overview of Dispersion Modeling in Air Permitting Arizona Department of Environmental Quality Air Quality Division Robert Arpino P.E. Main Topics Introduction ADEQ Air Jurisdiction Types of ADEQ Air Permits Uses of Dispersion Modeling Common Regulatory Air Models Modeling Review Process

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Overview of Dispersion Modeling in Air Permitting Arizona Department of Environmental Quality

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  1. Overview of Dispersion Modeling in Air Permitting Arizona Department of Environmental Quality Air Quality Division Robert Arpino P.E.

  2. Main Topics • Introduction • ADEQ Air Jurisdiction • Types of ADEQ Air Permits • Uses of Dispersion Modeling • Common Regulatory Air Models • Modeling Review Process • Tribal Air Program Jurisdiction • ADEQ Tribal Policy • Joint Agency Engagement • Air Modeling Resources/Contacts

  3. State of Arizona Facts • Total area of roughly 114,000 square miles • 15 counties • 2 Class I National Parks (Grand Canyon, Petrified Forest) • 10 Class I National Wilderness Areas • 21 Federally Recognized Native American Tribes • - covering 28% of the land base

  4. Map of Arizona Counties

  5. Overview of ADEQ Jurisdiction • Source categories under exclusive ADEQ jurisdiction • Metal ore smelters • Petroleum Refineries • Coal-fired electrical generating stations • Portland cement plants • Other sources under State asserted jurisdiction • -A.R.S. 49-402 • Maricopa, Pima, Pinal County permit programs • Cover sources within those jurisdictions • (except those listed above) • ADEQ covers remaining counties

  6. Types of ADEQ Air Permits • Class I Permits • All Prevention of Significant Deterioration (PSD) determinations • All New Source Review determinations • All other types of new major source permits (Title V permits) • Class II Permits • All new minor source and synthetic minor source permits • Synthetic minor sources are sources that have agreed to restrictions • to limit their potential to emit below major source thresholds • General Permits • Covers specific classes of sources

  7. ADEQ General Permits • Emission calculations and dispersion modeling are already performed • by ADEQ to verify protection of NAAQS • Production and throughput limits set based on emissions analysis • and dispersion modeling (where applicable) performed by ADEQ • Public hearing process has already been done once so each • source will not need to be public noticed again • Usually more restrictive than individual source permit but less • expensive and faster since the technical analysis has already been • performed by ADEQ

  8. List of ADEQ General Permit Source Classes • Crematories (Expires November 30, 2014) • Soil Vapor Extraction Units (Expires June 30, 2016) • Crushing and Screening (Expires April 23, 2017) • Hospitals (Expires November 14, 2014) • Hot Asphalt Plants (Expires April 23, 2017) • Dry Cleaners (Expires July 19, 2016) • Generators (Expires July 19, 2016) • Concrete Batch Plants (Expires June 08, 2015) • Boilers (Expires May 12, 2014)

  9. Purposes of Dispersion Modeling • Protection of NAAQS • Protection of PSD increment • Protection of Air Quality Related Values (AQRV) • such as Class I area visibility • Determine if air monitoring is required and the best • location for the monitors • Protection of Arizona Standards for HAPs • AAAC – Acute Ambient Air Concentrations • CAAC – Chronic Ambient Air Concentrations

  10. USES OF DISPERSION MODELING AT ADEQ Permit Modeling SIP Modeling

  11. State Implementation Plan (SIP) Modeling • Can be used along with monitoring data to determine the • attainment status of a region and if a (SIP) is required • Regional scale modeling over a large area • Large emission inventory • Demonstrate effectiveness of control measures • used to achieve attainment with NAAQS (e.g. PM-10)

  12. Permit Modeling • Modeling may be required when a source submits an • air permit application (AAC R18-2-407) • Modeling requirement may depend on: • - Magnitude of the potential emissions • - Location of the source near sensitive populations • - Level of emission control - proposed minor NSR rule • AAC R18-2-334 provides an option for a source • to forego modeling if Reasonably Available • Control Technology (RACT) is applied

  13. Common Regulatory Dispersion Models • AERSCREEN – A conservative screening model that • is relatively easy to run and can be used to determine • if refined modeling is necessary • AERMOD – The “workhorse” of permit modeling for • near field. Replaces ISC model • CALPUFF – A very comprehensive model which • requires very detailed meteorological and • geographical data sets. Very resource intensive!

  14. AERSCREEN • EPA-recommended screen model to determine if • refined modeling is needed • Can model a single source to obtain 1-hr worst-case • concentrations • Easy-to-use Gaussian dispersion model • Accounts for terrain and downwash effects using • AERMAP and BPIPPRM • Generates worst-case meteorology using MAKEMET • program which utilizes: • - ambient air temperature • - minimum wind speed, site-specific • - surface characteristics

  15. AERMOD Overview • EPA-preferred model for near field (<50 km) • Steady-state Gaussian plume model • Can handle simple and complex terrain • Incorporates advanced building downwash algorithms • Uses turbulence theory to estimate degree of dispersion

  16. AERMOD Overview (cont’d) • AERMOD can model a variety of source types: • Point sources – stacks • Area Sources – e.g. storage piles • Volume Sources – e.g. haul trucks • Line Sources • Flares

  17. AERMOD Subprograms • AERMET – Processes surface met data, upper air data, • and land use parameters to generate surface and profile • met data files ready for use by AERMOD • AERMAP – Processes terrain data to generate receptor • grid with elevations for each receptor • AERSURFACE – Analyzes USGS land coverage data • to provide surface characteristics such as albedo, • Bowen Ratio, and surface roughness for use in AERMET

  18. AERMOD Subprograms (cont’d) • BPIP PRIME – Building Profile Input Program with • Plume Rise Model Enhancements • Uses building height, width, stack height and location • to calculate downwash parameters for use in AERMOD • Improved building downwash calculations over the old • BPIP which was used with ISC3 model

  19. CALPUFF Overview • EPA-preferred long range model (50 km – 300 km) • Non-steady state Langrangian puff model • Requires complex data input e.g. MM5 Met data, • precipitation data, geographical data and is more • resource intensive than AERMOD • Can account for chemical transformations • Can perform visibility impact analysis (CALPOST)

  20. CALPUFF Overview (cont’d) • Main programs/subprograms: • CALMET – Meteorological pre-processor that processes • meteorological and geophysical data for CALPUFF • CALPUFF – Processes input source data and CALMET • data to calculate impacts • CALPOST – Post processing program that uses CALPUFF • results to average and report concentration, wet/dry deposition, • and visibility impacts

  21. CALPUFF Modeling System (simplified)

  22. Model Review Process at ADEQ • Modeling Protocol • Modeling Report

  23. Modeling Protocol • Document submitted to agency (in advance of performing the model) • describing the modeling approach and supporting methodologies used. • Strongly recommended to avoid having to rerun model! • Provide details of the pollutants considered, emission sources, • source types, facility layout, ambient air boundary • Describe model selection and version used. Important since • different versions can give different results • (e.g CALPUFF 5.8 versus CALPUFF 6.4) • Justify the use of any non-default settings • (e.g. Low-wind beta settings)

  24. Modeling Protocol (cont’d) • Describe regional climate/meteorology, topography • Discuss choice of met data set and ambient background • concentrations used in the model. Must justify that • choices are representative of site area per • EPA Guidelines (40 CFR 51 App. W Sec. 8.0) • Detailed discussion of building downwash, BPIPPRM • inputs, Good Engineering Practice stack height, • cavity zone impacts

  25. Modeling Protocol (cont’d) • Proposed receptor grid details (course/fine/discrete) and • extent of modeling domain • Provide details of terrain data sets and discuss any • effects that terrain may have on modeled results • Describe modeling approach proposed and any special • considerations, such as unit load analysis • PSD Sources – Significance, NAAQS, increment, visibility, • Class I area modeling, soil/vegetation impact etc.

  26. Modeling Protocol (cont’d) • Provide details of any model option or methodology used • (e.g. deposition option, OLM/PVMRM for NO2 etc. etc.) • Discussion of approach to model intermittent sources, fugitive • sources • Discussion of approach to model variable load sources (engines) • List of protocol elements and specific recommendations is • found in Appendix A of ADEQ Modeling Guidelines

  27. Modeling Report • Organizes and tabulates results, compares and • discusses results relative to a standard (e.g. NAAQS) and • also any specific issues or deviations from protocol. • Compare modeled impacts to appropriate standard • (NAAQS, increment, visibility, AAAC/CAAC) • Use of any “non-default” settings or deviations from protocol • Discussion of case-specific issues in results

  28. Modeling Report (cont’d) • Maps showing facility boundary, sources, roads, buildings, • sensitive areas, monitoring sites (if applicable) • Provide all input/out files, met data files, and any • post-processing files • If applicable, Class I Area analysis results such • as increment analysis, visibility, other air quality related • values (AQRVs)

  29. Modeling Report (cont’d) • Verify that emission rates used in model are consistent with • the permit application emission rates • Tabulate results in the correct form for specific pollutant • Confirm that the appropriate land managers were sent • copies of the modeling report

  30. Tribal Air Program Jurisdiction • Most Tribes in Arizona are under federal EPA jurisdiction • Some tribes in Arizona have EPA approved programs • - Gila River Indian Community • - Fort McDowell Yavapai Nation • - Navajo Nation • - Salt River Pima-Maricopa Indian Community • April 28, 2003 ADEQ established Tribal Policy basic principles • governing ADEQ relations with Tribal governments in Arizona

  31. ADEQ Tribal Policy • Establishes the following: • Recognizes that pollution is not restricted by political boundaries • Respects sovereignty of Tribal governments under federal law • Federal government has primary role for assisting Tribes • Supports strengthening Tribal capacity for management/regulation • ADEQ is committed to developing cooperative relationships • and mutual respect for environmental concerns

  32. ADEQ Tribal Policy (cont’d) • ADEQ assistance to develop environmental programs • Provide technical assistance • Share data (e.g. monitoring data, emissions etc. etc.) • -Reciprocity requested from Tribes • Conduct joint Tribal-State projects • Cooperatively resolve environmental issues • Will open training to Tribes whenever possible • ADEQ activities in Tribal land • Requires invitation from appropriate Tribal official

  33. ADEQ Tribal Policy (cont’d) • Intergovernmental Agreements/Memoranda of Understanding • ADEQ will enter when considered mutually appropriate • ADEQ will work with Arizona Tribes to • Increase EPA funding available for Tribes • Develop Tribal capacity for federal environmental programs • Notification of permit decisions that may affect Tribes • ADEQ will provide early notification • ADEQ requests reciprocity

  34. ADEQ Tribal Policy (cont’d) • ADEQ will not impose environmental fees/taxes on • Tribes or Tribal entities operating solely within reservation • Non-Tribal activities within reservation • Staff will relay Tribal issues/requests for technical • Assistance as quickly as possible • Staff must obtain approval from Division Director before • initiating contact with Tribes

  35. Joint Agency Engagement • NEPA – National Environmental Policy Act • Joint Engagement Case Study – Denison Mines

  36. NEPA – National Environmental Policy Act • Establishes a national environmental policy and requires • the federal government to consider environmental factors • and impacts in decision making • Applies to resources under federal jurisdiction that involve • federal funds and require federal permits • Three levels of NEPA analysis: • Categorical Exclusion • Environmental Assessment (EA) • Environmental Impact Statement (EIS)

  37. The NEPA Process

  38. NEPA (cont’d) • The agency with the greatest expertise and regulatory • authority becomes the Lead Agency for NEPA process • -Serves as single point of contact for public • -Coordinates all activity with local/state/federal agencies • -Usually federal agency – e.g. EPA, BLM, NPS etc. • Cooperating Agency – 40 CFR 1508.5 • State and/or Tribal agencies with jurisdiction/special • expertise may serve as a Cooperating Agency.

  39. NEPA (cont’d) • Cooperating Agency – means any Federal agency other than • the Lead Agency which has jurisdiction and/or special • expertise regarding a proposal/federal action significantly • affecting the quality of the human environment. • Cooperating agencies can provide specific information used • in assessing environmental impacts: • - Monitoring data for use as background concentration • - Emissions data for specific sources in the area • - Insight into specific local air quality issues and concerns • - Dispersion modeling related information

  40. NEPA (cont’d) • Council of Environmental Quality (CEQ) coordinates federal • environmental efforts and oversees the NEPA process • July 28, 1999 CEQ memo urges federal agencies to solicit • participation of State, Tribal, local gov’t as cooperating agencies

  41. NEPA (cont’d) • CEQ regulations/guidance do require agencies to • provide Tribes opportunities to comment at various • stages of the NEPA process • Federal agencies are required to provide early consultation • with Tribes in NEPA process - See 40 CFR 1501.2(d)(2)

  42. Joint Engagement Case Study • Denison Mines – Four underground Uranium mines located in • northern Arizona near Grand Canyon and Tribal Areas • Sensitive issues due to nearby lands • ADEQ legally obligated to issue permit if applicant has • met applicable requirements • ADEQ provided extensive notification to Tribes including • Navajo, Hopi, Hualapai, Havasupai and Paiute Tribes

  43. Joint Engagement Case Study • Denison Mines are minor sources subject to: • -40 CFR 63 Subpart ZZZZ - backup generators • -40 CFR 61 Subpart B – mine vent radon monitoring • -A.A.C. Title 18, Chapter 2, Articles 6, 8 – fugitive dust, smoke, opacity • Additional requirements above and beyond that legally required • -Dispersion modeling (AERMOD/CALPUFF) to assess • cumulative air impact on NAAQS, visibility, regional • haze analysis (Grand Canyon) • -Numerous public outreach meetings • -Extended public comment period beyond required period

  44. Joint Engagement Tribal Involvement • Participation requested and encouraged! • Your Tribal voice is important so please attend • meetings to express concerns/issues • ADEQ requests specific comments on the permit • application and associated analyses • To foster better communication, please identify the • appropriate Tribal officials to serve as “point of contact” • for air related issues

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