© 2004 Zephyr Environmental Corporation Air Quality Impacts Analysis Presented to: American Public Power Association APPA New Generation Meeting: Anticipating new permitting issues, IGCC Technology Options, Atmospheric Modeling, and Anticipating the Public’s Reaction Presented by: William B. Jones Project Manager Zephyr Environmental Corporation June 28, 2006

© 2004 Zephyr Environmental Corporation What is modeling and why do it? Types of models Typical modeling analyses Recent modeling activity Outline of Presentation

© 2004 Zephyr Environmental Corporation Running computer programs to predict air pollutant levels Dates back to 1930’s, looked at smoke from chimneys Different applications –Complex terrain –Long-range transport –Photochemical What is Modeling?

© 2004 Zephyr Environmental Corporation Relative to monitoring, it is –Cheaper –Faster –More extensive Useful regulatory tool –Developing control strategies –Permitting of new/modified industrial facilities Why do Modeling?

© 2004 Zephyr Environmental Corporation Screening –SCREEN3 –AERSCREEN (any day now) Refined –ISC3 –AERMOD –CALPUFF Types of Models

© 2004 Zephyr Environmental Corporation Quick and dirty Required inputs are limited –Meteorological data –Source data –Terrain data Cursory structure downwash analysis Conservative (high) results Features of Screening Models

© 2004 Zephyr Environmental Corporation Required inputs can be substantial –Preprocessed meteorological data –Preprocessed terrain data Detailed structure downwash analysis Features of Refined Models

© 2004 Zephyr Environmental Corporation Will become EPA’s official preferred model for most near-field industrial applications on December 9, 2006 Improvements over ISC3 –Dispersion within Planetary Boundary Layer –Characterization of meteorological conditions –Terrain depiction AERMODAERMOD

© 2004 Zephyr Environmental Corporation Straight line trajectory for plume Spatially constant meteorological conditions No “memory” of previous hour’s emissions AERMOD is a steady-state model

© 2004 Zephyr Environmental Corporation Most industrial applications When your situation involves –Pollutant concentrations within tens of km of source –Flat or complex terrain (but maybe not “complicated” terrain) Most NAAQS/PSD Increment analyses When should you use AERMOD?

© 2004 Zephyr Environmental Corporation The input/output files may look the same as ISC… But it is much more labor-intensive than ISC –AERMET –AERMAP Computer runtimes can measure in days Issues with AERMOD

© 2004 Zephyr Environmental Corporation Non-Steady-State model (Puff model) CALPUFFCALPUFF

© 2004 Zephyr Environmental Corporation ISC vs. CALPUFF animation here CALPUFFCALPUFF

© 2004 Zephyr Environmental Corporation Non-Steady-State model (Puff model) Source input requirements are more detailed than AERMOD Terrain input requirements are more detailed than AERMOD Meteorological data input requirements are quite substantial –MM5 can be run for anywhere in the world CALPUFFCALPUFF

© 2004 Zephyr Environmental Corporation Most long-range transport applications (i.e., greater than 50 km) Class I impact/visibility assessments Nearfield analyses involving significant terrain variations When should you use CALPUFF?

© 2004 Zephyr Environmental Corporation Class II –Significance –NAAQS –PSD Increment Class I Typical Modeling Analyses

© 2004 Zephyr Environmental Corporation Consider only project in question (emissions increases and decreases) Compare against U.S. EPA significance levels –If below, analysis is finished –If above, proceed with more comprehensive NAAQS/PSD Increment analysis Class II Analyses: Significance Modeling

© 2004 Zephyr Environmental Corporation Comprehensive assessment of overall air quality Include all sources at your facility Include offsite sources Include representative ambient background pollutant concentrations Class II Analyses: NAAQS Modeling

© 2004 Zephyr Environmental Corporation Include PSD Increment consuming and expanding sources at your facility Include PSD Increment consuming and expanding offsite sources No ambient background pollutant concentrations are included Class II Analyses: PSD Increment Modeling

© 2004 Zephyr Environmental Corporation Class I Areas

© 2004 Zephyr Environmental Corporation Areas within 300 km of Class I Area

© 2004 Zephyr Environmental Corporation Class I PSD Increments Air Quality Related Values (AQRV’s) –Visibility –Acid deposition (sulfate and nitrate) Class I Analysis

© 2004 Zephyr Environmental Corporation 1993: Interagency Workgroup on Air Quality Modeling (IWAQM) formed, recommended CALPUFF 2000: Federal Land Manager’s Air Quality Related Values Workgroup (FLAG) was written to develop a more consistent approach for the FLMs to evaluate air pollution effects on their resources History of Class I Analyses

© 2004 Zephyr Environmental Corporation History has shown it’s easier to define what is not a problem vs. what is a problem Each case is different—for each facility, and each FLM History of Class I Analyses

© 2004 Zephyr Environmental Corporation Run CALPUFF with 3 years of met data Calculate 24-hr b ext (visibility index) Compare b ext against natural conditions –If < 5%, FLM doesn’t object –If between 5% and 10%, FLM may object –If > 10%, FLM likely to object Current (typical) approach to assessment of visibility impairment

© 2004 Zephyr Environmental Corporation John Vimont (NPS) spoke at Guideline on Air Quality Models Conference in Denver this past April Outlined proposed changes to visibility analysis methodology –Different way of accounting for relative humidity –Different way of comparing b ext (98 th percentile, or 8 th high per year) But FLAG guidance may be changing!

© 2004 Zephyr Environmental Corporation Plum Point Energy Station: Osceola, Arkansas Comanche Generating Station: Pueblo, Colorado Duke Energy: Cliffside, NC Sandy Creek: McClennan County, TX City Public Service: San Antonio, TX Examples of analyses required of recent coal-fired facilities

© 2004 Zephyr Environmental Corporation Plum Point Energy Station, Osceola, AR Permit issued August 20, 2003

© 2004 Zephyr Environmental Corporation Ran CALPUFF, initially found light extinctions > 5% Developed water content adjustment to modify natural light extinction calculation Plum Point Energy Station, Osceola, AR Class I Visibility Analysis Re-ran CALPUFF, did not find light extinctions > 5%

© 2004 Zephyr Environmental Corporation Comanche Generating Station, Pueblo, CO Permit issued July 5, 2005

© 2004 Zephyr Environmental Corporation IntermissionIntermission Quick Class I Area Tour

Weminuche Wilderness, 1999

© 2004 Zephyr Environmental Corporation Weminuche Wilderness, 1999 (Continental Divide)

© 2004 Zephyr Environmental Corporation Weminuche Wilderness, 1999 (Neighbor near campsite)

© 2004 Zephyr Environmental Corporation Great Sand Dunes NP, 2002 “The Summit”

© 2004 Zephyr Environmental Corporation Black Canyon of the Gunnison River NP (2002)

© 2004 Zephyr Environmental Corporation Visibility –Found change in light extinction to be less than 5% at all Class I areas, so acceptable Acid Deposition –Sulfur deposition less than kg/ha/yr (Deposition Analysis Threshold, or DAT) (western US value), so acceptable Class I PSD Increment –PM10 impacts less than Class I significance level of 0.3 ug/m3 Comanche Generating Station, Pueblo, CO Class I Analyses Performed

© 2004 Zephyr Environmental Corporation U.S. Forest Service has established threshold of concern for acid deposition in Class I areas Considered three high altitude lakes in Class II areas Change in ANC resulting from PM10 and H2SO4 emissions evaluated Percent change found to be below threshold of 10% Comanche Generating Station, Pueblo, CO Additional Analysis: Acid Neutralizing Change

© 2004 Zephyr Environmental Corporation Duke Energy, Cliffside, NC Permit Application submitted December 16, 2005

© 2004 Zephyr Environmental Corporation Visibility –NPS required speciation of PM10 emissions by light scattering properties (soils, elemental carbon, and organic aerosols) Acid Deposition –Used DAT of 0.01 kg/ha/yr (eastern US value) Class I PSD Increment –PM10 and NOx impacts less than Class I Significance Levels Duke Energy, Cliffside, NC Permit Application submitted December 16, 2005

© 2004 Zephyr Environmental Corporation Closest Class I area is Wichita Mountains Wilderness (Oklahoma), ~ 370 km away Did not have to examine any impacts on Class I areas Sandy Creek, McClennan County, TX Updated application submitted March 10, 2005

© 2004 Zephyr Environmental Corporation Closest Class I area is Big Bend National Park (Texas), ~ 440 km away TCEQ did not require any Class I analysis CPS assessed visibility and acid deposition at Big Bend and six other Class I areas (out to 870 km) Results –Light extinction found to be < 5% at all Class I areas –Sulfur and Nitrogen deposition found to be < DAT at all Class I areas City Public Service, San Antonio, TX Permit issued January 2006

© 2004 Zephyr Environmental Corporation Model selected based on –Type of analysis being conducted –Characteristics of region being modeled Class II (NAAQS and PSD Increment) analyses will typically use AERMOD –More complicated than ISC was Class I analyses will typically use CALPUFF –Reach of FLM is increasing –Requirements of analysis are very fluid SummarySummary

© 2004 Zephyr Environmental Corporation EPA’s SCRAM Website: IWAQM: FLAG: www2.nature.nps.gov/air/Permits/flag/index.cfm CALPUFF: src.com/calpuff/calpuff1.htm PM2.5: (John Seitz (OAQPS) 10/23/97 memo on using PM10 as surrogate for PM2.5 in PSD analyses) Useful Modeling Links

© 2004 Zephyr Environmental Corporation Hopefully you’ve found this a “model” presentation Hopefully you’ve found this a “model” presentation Bill Jones