Transcript Arpino_ITEPModeling_101.ppt

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
Tribal Air Program Jurisdiction
ADEQ Tribal Policy
Joint Agency Engagement
Air Modeling Resources/Contacts
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
Map of Arizona Counties
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
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
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
List of ADEQ General Permit Source Classes
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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)
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
USES OF DISPERSION MODELING AT ADEQ
Permit Modeling
SIP Modeling
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)
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
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!
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
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
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
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
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
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)
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
CALPUFF Modeling System (simplified)
Model Review Process at ADEQ
Modeling Protocol
Modeling Report
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)
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
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.
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
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
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)
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
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
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
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
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
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
Joint Agency Engagement
NEPA – National Environmental Policy Act
Joint Engagement Case Study – Denison Mines
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)
The NEPA Process
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.
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
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
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)
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
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
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
Effective Comments on Permits
Comments should:
• Be specific and describe the exact nature of the problem
• Avoid generic descriptions
• Provide supporting documentation for the comment when possible
• Identify the rule/requirement that applies to the problem
• Suggest changes to draft permit or propose alternative approach
Comments have resulted in additional requirements such as:
• Dust control plans
• Radiation surveys
• Ambient Monitoring
Effective Comment Example
Generic Comment Example (bad):
“The dispersion modeling is not accurate or valid because it wasn’t
performed correctly and the assumptions are not right.”
Specific Comment Example (good):
“The dispersion modeling is not valid because it utilizes meteorological
data from site XYZ, located in town ABC, some 40 miles
northwest of the proposed site. The area around the selected met data
station has markedly different terrain characteristics from the proposed
site location and is therefore not spatially and temporally
representative of the local climate characteristics of the proposed
site in accordance with EPA guidelines on air quality models.
(See Sec. 8.3 of 40 CFR Appendix W Part 51).
Effective Comment Example 1 (cont’d)
“Additionally, the complex terrain of the proposed site is characterized by
BigTall mountain range to the east, and Bumpy Mountain Range
to the southeast which will cause wind channeling effects etc. etc. ……”
“Therefore, due to the significant terrain and elevation differences
between the met data site and the proposed site for the source,
the agency should require installation of an on-site met data tower
to collect at least 1-year of on-site data to be used in the
dispersion modeling or should require the source to install ambient
monitors after construction of the site to ensure compliance with
the NAAQS for NO2 and PM-10.”
Modeling Resources
ADEQ Dispersion Modeling Guidelines for Air Quality Permits
http://www.azdeq.gov/environ/air/download/modeling.pdf
40 CFR Appendix W – Guideline on Air Quality Models
EPA Support Center for Regulatory Air Models (SCRAM)
( http://www.epa.gov/scram001/ )
ADEQ Modeling Resources Webpage – Coming soon!
ADEQ Modeling Contacts
Feng Mao Ph.D., P.E. (Lead Modeler)
Phone: 602-771-4529
Email: [email protected]
Robert Arpino P.E.
Phone: 602-771-4896
Email: [email protected]