Technical Support Document 

for USEPA's Review of 

the California Regional Haze Plan's Modeling 

for the Best Available Retrofit Technology (BART) Evaluation 

Prepared by USEPA Region 9 

March 3, 2011
Table of Contents 

Description Page 

List of Tables and Figures 3 

List of Commonly Used Acronyms 4 

Overview of BART modeling requirements 5 

A. Overview of the California Regional Haze Plan's 

 Best Available Retrofit Technology Modeling Approach 5 

B. Model Selection and Applicability 6 

C. CALMET 6 

D. Emissions Input 7 

E. Calpuff/Calmet Model Settings 8 

F. Model Evaluation 9 

G. Calculation of Visibility Impact 9 

H. Results of Subject-to-BART Modeling 12 

I. South Coast Air Quality Management District - 

 RECLAIM Sources Visibility Impact Analysis. 14 

J. Conclusion 18 

 

2 
List of Tables and Figures 

Number Title Page 

 

Tables 

Table 1: Results of Subject to BART Analysis in California 13 

Table 2: Valero Visibility Impact Calculated with 3 Years of Meteorological Data 13 

Table 3: Subject-to BART Sources in the RECLAIM Program 15 

Table 4: Visibility Impairment from RECLAIM Sources 18 

Figures 

Figure 1: Class I areas and subject-to-BART sources for which initial visibility 7 

impairment analysis has been conducted. 

Figure 2: South Coast AQMP PM2.5 Modeling Domain 16 

 

3 
List of Commonly Used Acronyms and Abbreviations 

AQPM Air Quality Management Plan 

BART Best Available Retrofit Technology 

CAA Clean Air Act 

CARB California Air Resources Board 

CFR Code of Federal Regulations 

CRHP California Regional Haze Plan 

DV (dv) Deciview 

EPA U.S. Environmental Protection Agency 

FDDA four-dimensional-data-assimilation 

FLAG Federal Land Managers' Air Quality Related Values Work Group

FLM Federal Land Manager 

FR Federal Register 

FS U.S. Forest Service 

FWS U.S. Fish and Wildlife Service 

IMPROVE Interagency Monitoring of Protected Visual Environments 

IWAQM Interagency Workgroup on Air Quality Modeling 

MATES –III Multiple Air Toxics Exposure Study III 

MM5 Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model 

NAAQS National Ambient Air Quality Standards 

NCEP National Centers for Environmental Prediction's 

NOx Oxides of Nitrogen 

NPS National Park Service 

NSR New Source Review 

PM Particulate Matter 

PSD Prevention of Significant Deterioration 

RECLAIM REgional CLean Air Incentives Market 

SCAQMD South Coast Air Quality Management District 

SO2 Sulfur Dioxide 

TPY (tpy) Tons Per Year 

TSD Technical Support Document 

WRAP Western Regional Air Partnership 

 

4 
Overview of BART modeling requirements 

The Clean Air Act establishes the national goal of eliminating man-made visibility impairment 

from all Class I areas. As a part of the plan for achieving this goal Section 169A(b)(2)(A) of the 

act requires certain major stationary sources in existence between 1962 and 1977 to be reviewed 

for BART. Pursuant to federal regulations, states have the option of exempting a BART-eligible 

source from the BART requirements based on dispersion modeling demonstrating that the source 

cannot reasonably be anticipated to cause or contribute to visibility impairment in a Class I area. 

According to 40 CFR Part 51, Appendix Y, a BART eligible source is considered to “contribute” 

to visibility impairment in a Class I area if the modeled 98th percentile change in deciviews is 

equal to or greater than the “contribution threshold.” Any BART-eligible source determined to 

cause or contribute to visibility impairment in any Class I area is subject to BART. The EPA 

BART Guidelines recommend a contribution threshold of 0.5 change in deciview be used, 

although States have the option to establish alternative thresholds. The state of California has 

opted to use a contribution threshold of 0.5 change in deciview. 

To determine whether a source exceeds the BART contribution threshold, EPA recommends use 

of the CALMET/CALPUFF modeling system; the main components of this modeling system are 

CALMET (a diagnostic three-dimensional meteorological model), CALPUFF (an air quality 

dispersion model), and CALPOST (a post-processing package). 

A. Overview of the California Regional Haze Plan BART Modeling Approach 

To conduct the modeling, California followed the EPA BART guidelines1

 (U.S. EPA, 2005) and 

the applicable CALMET/CALPUFF modeling guidance ( IWAQM, 1998; FLAG, 20002

; EPA, 

2003c) in effect at the time the analysis was conducted3

. This included EPA’s March 16, 2006, 

memorandum “Dispersion Coefficients for Regulatory Air Quality Modeling in CALPUFF” 

(Atkinson and Fox, 2006). This memo was written by the EPA Office of Air Quality and 

Planning Standards (OAQPS) Model Clearinghouse Director in response to questions from EPA 

Region 4 on what constitutes the regulatory version of CALPUFF and recommended CALPUFF 

options for BART modeling in their region. 

 

1

 59 FR 39104, 39170 (July 6, 2005) 

2

 U.S. Forest Service, National Park Service, and U.S. Fish and Wildlife Service. 2010. Federal land managers‘ air 

quality related values work group (FLAG): phase I report—revised (2010). Natural Resource Report 

NPS/NRPC/NRR—2010/232. National Park Service, Denver, Colorado. 3

 California Regional Haze Plan, page C-2, Results of CALMET/CALPUFF BART Modeling for Class I Federal 

Area Individual Source Attribution Visibility Impairment 

5 
The memo’s modeling recommendations are followed in the protocol for conducting the 

modeling4

, except as noted below. Using the procedures in the modeling protocol, CARB 

conducted initial subject-to-BART screening analysis modeling to determine which sources 

contribute significantly to visibility impairment at Class I areas. CARB then provided the 

modeling results to the affected districts, and the districts used those results, in conjunction other 

information, to determine whether or not the individual BART-eligible source will be subject to 

BART control requirements. CARB modeled background visibility conditions corresponding to 

the annual average visibility. EPA guidance allows States to select the characterization of 

background conditions for their BART modeling. CARB also provided modeling results showing 

the highest 24 average change in visibility and the 8th highest (98th percentile) predicted change. 

B. Model Selection and Applicability 

Relevant guidance (IWAQM, 19985

; FLAG 20006; EPA, 20037) states that the CALPUFF 

model is generally applicable at distances from 50 km to at least 200-300 km downwind of a 

source. Given the large number of Class I areas in the West, most BART-eligible stationary 

sources modeled by CARB were located within 300 km of at least one Class I area. 

The CRHP modeling was conducted by CARB using CALPUFF: version 5.754, level 060202, 

CALMET: version 5.724, level 060414, and CALPOST: version 5.6393, level 060202 

C. CALMET 

CALMET is a diagnostic meteorological model. For the CRHP, the initial guess wind fields 

were based on 12-km resolution MM5 meteorological fields for 2000 and 2002 and 36-km MM5 

data for 2001 (i.e., in CALMET IPROG is set to 14). The MM5 files for 2000 were generated by 

ARB staff and the MM5 files for 2001 and 2002 were provided by Western Regional Air 

Partnership (WRAP). Because the MM5 data for the year 2000 were generated specifically for 

applications in California, CARB believes that the data for this year may be more reliable and 

more representative of the meteorological conditions of California. 

CALMET Modeling Domain8

The modeling domain is shown in Figure 1. Also shown are locations of receptors to be 

placed in Class I areas. It is based on a Lambert Conformal Conic projection. The domain 

covers all Class I areas in California and the locations of California’s BART-eligible 

sources that are required to do detailed modeling and analysis. The domain also includes 

 

4

 CRHP, Appendix 1. Modeling Protocol: CALMET/CALPUFF BART Protocol for Class I Federal Area Individual 

Source Attribution Visibility Impairment Modeling Analysis. 

5 Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report and Recommendations for 

Modeling Long Range Transport Impacts (EPA-454/R-98-019) 

6 http://www.nature.nps.gov/air/Pubs/pdf/flag/FlagFinal.pdf 7 EPA. 2003. “Revisions to the Guideline on Air Quality Models: Adoption of a Preferred Long Range Transport 

Model and Other Resources”; Final Rule. Fed. Reg./Vol. 68, No. 72/Tuesday April 15, 2003/Rules and Regulations. 

40 CFR51.

8

 CRHP, page C-8. 

6 
Class I areas in nearby states that are potentially impacted by California BART-eligible 

sources. The modeling domain is extended by 50-km beyond all sources and Class I areas 

to capture potential recirculation of pollutants. The CALMET domain is 1332 km x 1332 

km in the longitudinal and meridional directions, respectively, with 4-kilometer grid 

resolution. This modeling domain will be used to generate a unified meteorological data 

set so that it can be used in CALPUFF modeling for all BART-eligible sources. 

Figure 1. Class I areas and subject-to-BART sources for which initial visibility impairment 

analysis has been conducted.9

D. Emissions Input 

According to the EPA BART Guidelines: “The emissions estimates used in the models are 

intended to reflect steady-state operating conditions during periods of high capacity utilization. 

We do not generally recommend that emissions reflecting periods of start-up, shutdown, and 

malfunction be used, as such emission rates could produce higher than normal effects than 

would be typical of most facilities. We recommend that States use the 24 hour average actual 

 

9

 CRHP, page C-8. 

7 
emission rate from the highest emitting day of the meteorological period modeled, unless this 

rate reflects periods start-up, shutdown, or malfunction.” (EPA, 2005)10. 

The WRAP contractor Eastern Research Group, Incorporated (ERG) prepared a short list of all 

facilities in California permitted under Title V of the Clean Air Act that fall into the 26 BART 

categories. 

CARB excluded VOC emissions from the BART –eligibility evaluation, based its analysis that 

secondary organic aerosols formed from anthropogenic VOC emissions are not significant 

contributors to haze on worst days in California 11

While NOx, SOx, and PM emissions must be evaluated for BART-eligibility, the 

Regional Haze Rule gives states the discretion to excuse facilities solely exceeding the 

threshold for VOC or ammonia provided that those pollutants do not contribute to 

impaired visibility at Class 1 Areas. In California, ammonia emissions from area, mobile, 

and natural sources exceed those from stationary sources. Also, since secondary organic 

aerosols formed from anthropogenic VOC emissions are not significant contributors to 

haze on worst days in California, the State chose not to include sources that exceed the 

threshold for VOCs. When worst days in California are driven by organic aerosols, they 

appear to be the result of seasonally high biogenic emissions from plants or from wildfire 

events. 

California’s BART-eligible list includes only BART-era units with total emissions of NOx, SOx, 

or PM above the BART threshold, listed below, at a single facility. 

1. a PTE <15 TPY for PM emissions, or 

2. a PTE <40 TPY of SOx emissions, or 

3. a PTE <40 TPY of NOx emissions. 

Those emission units at a single facility that cumulatively emit only the pollutant(s) falling below 

these de minimus thresholds were listed but excluded from further review. The emission 

specifications for the major units for each of the subject –to BART sources are listed in 

APPENDIX C, BART Cal-Puff Modeling. 

E. Calpuff/Calmet Model Settings 

The CALMET and CALPUFF model settings used by CARB are listed in the CALMET 

Parameter Summary12 and CALPUFF Parameter Summary13. The settings complied with 

EPA’s recommendations for regulatory application of the CALPUFF modeling system in effect 

at the time of the analysis. The exception is for the IPROG parameter. The EPA default 

 

10 EPA. 2005. “Regional Haze Regulations and Guidelines for Best Available Technology (BART) Determinations”. 

Fed. Reg./Vol. 70, No. 128/Wed. July 6, 2005, Rules and Regulations, pp. 39104-39172. 40 CFR Part 51, FRL7925-9, RIN AJ31. 

11 CRHP, page 5-3 

12 CRHP, page C-34 

13 CRHP, page C-39 

8 
assumes no MM5 data will be used (IPROG=0). In the CARB BART screening analysis, MM5 

data were used as an initial-guess field (IPROG=14). In Section 6.1.1.10., CALMET Upper Air 

Stations14, CARB discusses the basis for choosing this option. 

The initial analysis will not consider upper air observational data for mainly two reasons. 

The first reason is that a substantial amount of data are missing, and there exists no rigorous 

method to fill in missing data. Filling in missing data arbitrarily will likely alter the 

meteorological field generated by the CALMET model. The other reason is that, since the 

output of the MM5 mesoscale meteorological model provides an adequate coverage of upper 

air meteorology, neglecting upper air observational data will have an insignificant effect on 

the CALMET meteorological field. Future analyses may consider upper air observational 

data. 

F. Model Evaluation 

Calpuff has been evaluated nationally by EPA and is considered appropriate for long range 

transport applications. No site specific performance evaluations were performed. 

G. Calculation of Visibility Impact 

Under the BART guidelines, the measure of the visibility improvement to be used in 

comparisons between various control scenarios is the 98th percentile of impacts are expressed as 

24-hour averages of delta deciviews relative to natural background, as estimated using the 

CALPUFF air quality modeling system. The meaning of this is described next, followed by 

particulars of the application of CALPUFF to the BART determination for the CRHP. 

Under the RHR, visibility is measured in deciviews. Visibility is traditionally described in terms 

of visual range in kilometers or miles. However, the visual range scale does not correspond to 

how people perceive visibility: a given increase in visual range is perceived differently 

depending on how good the original visibility was (that is, it is not on a linear scale). The 

deciview scale is designed to address this problem. It is linear with respect to perceived visual 

changes over its entire range, analogous to the decibel scale for sound: a given change in 

deciviews will be perceived as the same amount of visibility change, whatever the original 

visibility was. The defining equation is: deciviews = 10*ln(bext / 10), where ln is the natural 

logarithm, and extinction bext is the fraction of light scattered out of a viewing path. Extinction 

increases with the amount of pollution (bext is in units of 1/Mm, “inverse megameters”). Lower 

deciview values represent better visibility, more pristine atmospheres, and greater visual range, 

while increasing deciview values represent increasingly poor visibility. An increase of 1 

deciview corresponds to about a 10% increase in extinction. (Deciviews are related to the more 

traditional visual range according to dv = 10*ln(391 / visual range)). An eligible BART source 

with a predicted impact of 0.5 dv or more of impairment in a Class I area“contributes” to 

visibility impairment and is subject to BART. 70 FR 39104, 39121 (July 6, 2005). 

 

14 CRHP, page C-33. 

9 
10 

 

Under the BART guidelines, deciviews are estimated using the CALPUFF air quality model. 

CALPUFF predicts 24-hour average pollutant concentrations based on source emissions and how 

they disperse in the atmosphere. The CALPUFF modeling includes source emissions of the 

following visibility-impairing pollutants: SO2, SO4, NOx, secondary organic aerosol (SOA), fine 

particulate matter (PMF), coarse particulate matter (PMC), and elemental carbon (EC). 

CALPUFF incorporates a semi-empirical chemical module that simulates the conversion of SO2 

to particulate sulfate and NOx to particulate nitrate, at a rate dependent on meteorological 

conditions and background ozone concentration. These concentrations are converted to 

deciviews by the CALPOST post-processor in two steps. First, the IMPROVE15equation is used 

to estimate extinction bext from the predicted concentrations of various pollutants: 

bext = 3 * f(RH) * [sulfate] + 3 * f(RH) * [nitrate] + 4 * [organic mass] 

+ 10 * [elemental carbon] + 1 * [fine soil] + 0.6 * [coarse mass] + 10 

The 10 is for Rayleigh scattering, which is due to the interaction of light with molecules of air 

itself with no pollutants. The f(RH) is a water growth factor for sulfate and nitrate; its value 

depends on relative humidity (RH), ranging from 1 at low humidity to 18 at 98% humidity. In 

the second CALPOST step this extinction is converted to deciviews, using the above defining 

equation for deciviews. Finally, the delta deciviews (dv) represents the impact on visibility in 

deciviews of the source being evaluated, and is also provided by CALPUFF. It is the change, or 

“delta”, between deciviews with and without the source. Under the BART guidelines, delta 

deciviews is the difference between deciviews including the impact of the source and natural 

background, and deciviews of the natural background alone. Each modeled day and location in 

the Class I area will have an associated delta deciview. For each day, the model finds the 

maximum visibility impact of all locations (receptors) in the Class I area. From among these 

daily values, the BART guidelines recommend use of the 98th percentile, roughly equivalent to 

the 8th highest day, for comparing the base case and the effects of various controls. The 98th 

percentile is recommended rather than the maximum value to avoid undue influence from 

unusual meteorological conditions (BART guidelines p. 39121). 

15 Interagency Monitoring of Protected Visual Environments (IMPROVE) is a network of monitors in various Class 

I Areas, established to assess visibility impairment and its causes. The IMPROVE equation is used to converted 

monitored concentrations into extinction, a measure of visibility. See: http://vista.cira.colostate.edu/improve/
The California Regional Haze Plan uses the Haze Algorithm II (revised IMPROVE equation) for 

estimating the deciview values used in this plan16. 

The Haze Algorithm for calculating Light Extinction (bext) weights the Species Mass 

(ug/m3) measured at the IMPROVE monitors using particle size, humidity, and elevation 

as follows: 

bSulfate = 2.2 x fS(RH) x [small SO4] + 4.8 x fL(RH) x [large SO4] 

bNitrate = 2.4 x fS(RH) x [small NO3] + 5.1 x fL(RH) x [large NO3] 

bOrganic Material Carbon = 2.8 x [Small OM] + 6.1 x [Large OM] 

bElemental Carbon = 10 x [EC] 

bFine Soil = 1 x [Fine Soil] 

bSea Salt = 1.7 x fSS(RH) [Sea salt] 

bCoarse Mass = 0.6 x [CM] 

bRayleigh = (Site Specific factor, related to elevation, ranging from 7+ to 

11+ in California) 

bNitric Oxide gas= 0.33 x [NO2 (ppb)] (not measured at most IMPROVE monitors). 

The sum of the weighted extinction values gives the total daily extinction 

(Total bext) for each day of measurement: 

Total bext = bSulfate + bNitrate + bEC +bOMC + bSoil + bCM + bSS + 

bRayleigh + bNO2 

The revised IMPROVE equation has five changes: 1) greater completeness though the inclusion 

of sea salt, which can be important for coastal sites; 2) increased organic carbon mass estimate, 

based on more recent data for remote areas; 3) Rayleigh scattering using site-specific elevation 

and temperature, a refinement over the older network-wide constant; 4) separate estimates for 

small and large particles of visibility impacts and humidity-dependent particle size growth rates, 

which could affect estimates at the low and high ends; and 5) greater completeness though the 

inclusion of NO2 (Pitchford, 2006)17. 

The new equation shows broader scatter overall, but less bias in matching visibility 

measurements under high and low visibility conditions. That is, though it has a somewhat worse 

fit considering all the data, it has a better fit under visibility conditions most relevant to regional 

haze planning, the best and worst 20% of days. The looser overall fit can cause a slightly 

different set of days to be the ones chosen as the 20% worst, but the chemical species 

composition for such days is little changed (IMPROVE technical subcommittee for algorithm 

review, 2001, pp. 11-12), and so this makes little difference for assessing the contribution of 

 

16 CRHP, Appendix A., page A-1. 

17 Pitchford, Marc, 2006, "New IMPROVE algorithm for estimating light extinction approved for use", The 

IMPROVE Newsletter, Volume 14, Number 4, Air Resource Specialists, Inc.; web page: 

http://vista.cira.colostate.edu/improve/Publications/news_letters.htm 

direct link: http://vista.cira.colostate.edu/improve/Publications/NewsLetters/IMPNews4thQtr2005.pdf 

11 
12 

 

emission sources to current conditions, and for projecting the effect of emission controls. The 

split between small and large particles was the main factor in reducing the biases. Another effect of 

choosing a revised equation with broader scatter of nephelometer measurements (typically resolved 

to ~5-minute average data) versus IMPROVE particle sampling (24-hour averages every 3rd-day) is 

that a typical viewer at a Class I area would be more likely to notice a difference between the 

visibility condition from the observed nephelometer value and the calculated IMPROVE value, 

although not critical to the regional haze planning process specified in the RHR. 

The organic carbon (OC) measured by the IMPROVE network does not include all organic matter 

(OM); based on 1970s urban data, a scaling factor of 1.4 is embedded in the old equation to account 

for the full mass. Based on recent data more relevant to relatively remote Class I areas, the revised 

IMPROVE equation embeds an OM/OC factor of 1.8. In practice, for the worst days the biggest 

effect of switching to the revised IMPROVE equation is the increased organic carbon mass, because 

the worst days are dominated by organic carbon from fires, rather than the sulfates and nitrates that 

come more from anthropogenic sources. 

 

Review Comment: The revised IMPROVE equation has less bias, is more refined, accounts for more 

pollutants, incorporates more recent data, and is based on considerations of relevance for the 

calculations needed for assessing progress under the RHR. EPA believes it is appropriate for the 

State of California to use the revised IMPROVE equation. 

H. Results of Subject-to-BART Modeling 

California identified a list of sources to be evaluated by ARB and the air districts.18 The list also 

summarizes which BART-eligible units needed subject-to-BART visibility modeling and why 

the others did not. Only one modeled facility, the Valero Refining Company (Valero) operates a 

refinery in Benicia, in Solano County, had a visibility impact greater than the 0.5 deciview 

threshold. 19

18 CRHP, page 5-8, Table 5-2: List of BART-eligible Sources (Emission Units). 

19 CRHP, page C-7. 
Table 1: Results of Subject to BART Analysis in California 

BART Eligible Source Analysis Results 

the 98th percentile daily (24-hour) average 

deciview (dv) 

Tesoro Refinery Martinez 0.069 dv 

Rhodia Sulfuric Acid Plant Martinez 0.092 dv 

Shell Refinery Martinez 0.169 dv 

Searles Industrial 0.208 dv 

Valero Refinery Benicia 

without proposed emission controls 

with proposed emissions controls 

0.758 dv 

0.291 dv 

Conoco Phillips Refinery Rodeo 0.366 dv 

Chevron Richmond refinery 0.393 dv 

Coolwater Reliant Dagget 0.489 dv 

The visibility impact of the Valero source for the year 2000 was 0.758 deciviews at Point Reyes 

National Seashore. Two emission reduction strategies were proposed for the Valero facility for 

evaluation of their visibility impact. The maximum 24-hour emissions for normal operations 

were provided by the Bay Area Air Quality Management District. 20 The results of the visibility 

impact with one of the reduction strategies are shown in Table 2: Valero Visibility Impact 

Calculated with Three Year’s Worth of Meteorological Data (with emission reduction strategy 

g1), and are below the 0.5 deciview threshold for each of the three years that were modeled. 

Table 2: Valero Visibility Impact Calculated with Three Year’s Worth of Meteorological Data 

(with emission reduction strategy g1) 

Modeling Year 8th Highest Visibility Impact (in deciview) 

2000 0.225 

2001 0.291 

2002 0.259 

Review Comment (summary of EPA comments on CRH BART Modeling): CARB conducted 

initial subject-to-BART screening analysis modeling for California to determine which sources 

contribute significantly to visibility impairment in Class I areas. The overall approach followed 

EPA guidance and modeling procedures in effect at the time of the analysis and is therefore 

 

20 CRHP, page C-13. One emission reduction strategy (g1) was to reduce SO2, NOx and PM10 emissions from the 

coker, crude preheat F-101, reduced preheat F-102, and FCCU regenerator R702 that would be routed to a new main 

stack, and NOx control on units that would be routed to the p30 west stack and the p31 stack. 

13 
acceptable for use in the current regional haze plan. In the South Coast Air Basis, the South 

Coast Air Quality Management District provided supplemental BART–exemption modeling 

conducted by the district. A description and evaluation of this additional modeling analysis is 

discussed below. 

I. South Coast Air Quality Management District RECLAIM Sources Visibility Impact Analysis. 

1. Modeling Approach for South Coast subject-to- BART Sources in the REgional CLean Air 

Incentives Market (RECLAIM) program. 

The visibility impact analysis for the subject-to- BART sources in the South Coast Basin 

RECLAIM21 program was conducted in a separate analysis from the CARB CRPH subject to 

BART analysis.22 The eight subject-to BART sources in the RECLAIM program, listed in Table 

3 below, contribute approximately 50% of the total RECLAIM program NOx emissions of 27 

tons per day, and 65% of the total RECLAIM SOx program emissions of 12 tons per day. 

 

21 CRHP, Page 5-22. The RECLAIM Program in the South Coast Air Quality Management District is designed to 

generally substitute a cap-and-trade market mechanism for a command-and-control regulatory structure in the 

pursuit of NOx and SOx emissions reductions from major facilities within the District. The intent of the program is 

to reduce emissions of these pollutants at a faster rate than could be achieved by traditional methods and at lower 

overall cost. 

The RECLAIM Program was originally adopted in 1993, and requires three stages of emission reduction by 2011. In 

the first stage, which extended to 2000, facilities were required to compute emissions using historical activity rates 

and emission factors representing best available retrofit technology (BARCT) in 1993. Facilities were further 

required to meet facility-wide emission targets based on these 1993 BARCT factors by 2000. In the second phase of 

emission reductions, affected facilities were required to reduce NOx and SOx emissions between 2000 and 2003 by 

a uniform percentage calculated by the District. RECLAIM rules require that this reduction be sufficient to bring the 

aggregate of affected facility emissions to attainment targets specified in the 1991 Air Quality Management Plan. 

In 2005, the District conducted a study to determine whether reductions under these first two phases were equivalent 

or greater than those that would have been achieved by the application of BARCT rules to all affected facilities. This 

study concluded that BARCT limits were more restrictive in 2005 than in 1993, and recommended amendments to 

the RECLAIM program to achieve these new lower levels. The RECLAIM rules were amended in 2005 and 

regulated facilities now must further reduce emissions by 2011 to achieve facility-wide emission levels equivalent to 

those represented by 2005 BARCT limits. As a result of the scope of the RECLAIM Program in covering all 

facilities emitting four or more tons per year of NOx or SOX, and the diligence with which SCAQMD staff have 

analyzed and compared the benefits of this program to the universal application of BARCT to all stationary sources, 

the RECLAIM Program can be deemed equivalent in terms of emission reduction to the application of a universal 

BARCT regulation or the equivalent BART limitation under U.S. EPA’s visibility protection program. 

22Transmittal letter dated June 9, 2010 from James N. Goldstene, Executive Officer, California Air Resources 

Board, to Jared Blumenfeld Regional Administrator USEPA Region IX with attachments. RECLAIM Sources 

Visibility Impact Analysis. 

14 
Table 3: Subject-to BART Sources in the RECLAIM Program

BP Refinery (Carson) 

California Portland Cement 

Chevron refinery (El Segundo) 

Conoco refinery (Carson) 

Conoco refinery (Wilmington) 

Exxon Refinery (Torrance) 

Tesoro refinery (Wilmington) 

Ultramar refinery 

To determine the potential visibility impact from the emissions NOx and SOx from the subject-to 

–BART sources in the RECLAIM program on the nearby Class I areas of San Gabriel 

Wilderness, San Gorgonio Wilderness, Joshua Tree National Park, Cucamonga Wilderness, and 

San Jacinto Wilderness, SCAQMD modeled the combined impact of the emission from all 

sources in the RECLAIM program. 

2. 2007 South Coast PM2.5 Air Quality Management Plan Modeling. 

The modeling analysis that the SCAQMD conducted for the subject-to-BART for RECLAIM 

sources used a CAMx simulation, consistent with the particulate modeling used for the South 

Coast 2007 PM2.5 Air Quality Management Plan.23 The particulate modeling is discussed in 

detail in the AQMP, and briefly below: 

In the Final 2007 AQMP, CAMx annual average PM2.5 modeling simulations were 

generated for 2005, 2014 and 2020 baseline emissions and 2014 and 2020 controlled 

emissions scenarios. The 2005 CAMx simulation was conducted using baseline monthly 

temperature and humidity corrected emissions, for a weekday, Saturday and Sunday 

activity profile. Seasonal boundary conditions were extracted from the Western Regional 

Air Partnership (WRAP) regional modeling simulations (initialized from global air 

quality model output) in support of the Regional Haze Rule demonstrations. The 

simulations were driven by MM5 meteorological fields; five day-simulations with a one 

day “ramp-up” period using NCEP model initialization. 

CAMx simulations used the same region (5 km squared grid, 280 easting and 3650 

northing, 65 by 40 grid cells) as that used for the 2003 UAMAERO-LT analyses. The 

vertical structure was increased to 11 layers (compared with the 5-layer analysis of 

UAMAERO-LT), but less than the 19 layers used for the MM5 simulations in an effort to 

conserve computational resources. MM5 was used to generate the meteorological profile 

for each day in 2005. The MM5 simulations were generated for the larger SCOS97 

modeling domain employing a 5 km square grid and fit to the smaller PM2.5 grid. 

 

23 Final 2007 Air Quality Management Plan, June 2007, South Coast Air Quality Management District, Appendix 

V: Modeling And Attainment Demonstrations, V-1-6, V-1-7. 

15 
Figure 1: South Coast AQMP PM2.5 Modeling Domain24

The MM5 simulations were initialized from NCEP analyses and run for 5-day increments 

without the four-dimensional-data-assimilation (FDDA) option. Speciated PM2.5 data 

measured from the District’s Multiple Air Toxic Evaluation Program (MATES-III) 

during 2005 provided the characterization for evaluation and validation of the CAMx 

annual and episodic demonstrations. 

The model performance for the CAMx simulation was evaluated against t Wilderness he 2005 

annual IMPROVE data the Class I areas of San Gabriel Wilderness, San Gorgonio Wilderness, 

and Joshua Tree National Park.25 The 2005 CAMx simulation tended to under-predict 

IMPROVE observations, especially for ammonium nitrate. 

3. Visibility Impairment Test 

The visibility analysis assessed the impact of removing all RECLAIM emissions. The eight 

subject - to - BART sources contribute 56% of the total RECLAIM NOx emissions and 65% of 

the total RECLAM SOx emissions, so this represents a conservative estimate of impact of the 

emission from the eight subject - to - BART sources. The RECLAIM inventory (for all 

 

24 Final 2007 Air Quality Management Plan, June 2007, South Coast Air Quality Management District, Appendix 

V: Modeling And Attainment Demonstrations, V - 2- 16. 

25 Transmittal letter dated June 9, 2010 from James N. Goldstene, Executive Officer, California Air Resources 

Board, to Jared Blumenfeld Regional Administrator USEPA Region IX with attachments. RECLAIM Sources 

Visibility Impact Analysis. page D-4. 

16 
17 

 

REACLAIM sources) represents 19% of the total SOx and 3% of the total NOx modeling 

inventory in the basin. 

 SCAQMD determined the visibility impairment from all RECLAIM sources. 

The revised IMPROVE visibility equations were used to determine the deciview for each 

grid in the modeling domain. Three sets of runs were generated (six total: CAMx with 

and without RECLAIM source contribution) using the IMPROVE monitoring site 

specific functional humidity estimates. The grid level difference in deciview visibility 

between model runs was determined for the entire Basin and later sorted for the principal 

Class I areas within the modeling domain. The analysis was conducted for the simulated 

annual and worst 20 percent visibility days in the year.26

The revised IMPROVE equation is discussed in Section G. Calculation of Visibility Impact, 

above. 

Review Comment: The revised IMPROVE equation has less bias, is more refined, accounts for more 

pollutants, incorporates more recent data, and is based on considerations of relevance for the 

calculations needed for assessing progress under the RHR. EPA believes it is appropriate for the 

SCAQMD to use the revised IMPROVE equation in its analysis of the South Coast Basin. 

4. Visibility Impact on the Class I Areas near to the South Coast Basin; San Gabriel Wilderness, 

San Gorgonio Wilderness, Joshua Tree National Park, Cucamonga Wilderness, and San Jacinto 

Wilderness. 

The grid level difference in visibility was determined for the Class I areas for the annual and 

20% worst visibility days in the year. The visibility impairment from all RECLAIM sources is 

shown in Table 4: Visibility Impairment from RECLAIM Sources, below, which summarizes the 

results of the RECLAIM Sources Visibility Analysis27. The maximum impairment from all 

RECLAIM sources is 0.244 deciviews at San Gabriel Wilderness. The impact from the subjectto- BART sources in the RECLAIM program would be expected to be lower. 

26 Transmittal letter dated June 9, 2010 from James N. Goldstene, Executive Officer, California Air Resources 

Board, to Jared Blumenfeld Regional Administrator USEPA Region IX with attachments. RECLAIM Sources 

Visibility Impact Analysis. page D-1. 

27 Transmittal letter dated June 9, 2010 from James N. Goldstene, Executive Officer, California Air Resources 

Board, to Jared Blumenfeld Regional Administrator USEPA Region IX with attachments. RECLAIM Sources 

Visibility Impact Analysis. Tables 3, 4, 5, 6, and 7, pages D-6 through D-9. 
Table 4: Visibility Impairment from RECLAIM Sources 

Class I Area 

 

Maximum Deciview 

Reduction 

Annual 

Maximum Deciview 

Reduction 

Worst 20% 

San Gabriel Wilderness 0.094 0.244 

San Gorgonio Wilderness 0.035 0.053 

Joshua Tree National Park28 0.026 0.012 

Cucamonga Wilderness 0.113 0.11 

San Jacinto Wilderness 0.026 0.18 

Review Comment (summary of EPA comments on the South Coast AQMD BART Modeling): The 

South Coast AQMD conducted initial subject-to-BART screening analysis modeling for the South 

Coast Air Basin to determine which sources contribute significantly to visibility impairment in 

Class I areas. The overall approach is acceptable for use in the current regional haze plan for 

the subject - to - BART sources in the RECLAIM program in the South Coast Basin. 

J. Conclusion. 

California evaluated its BART eligible sources for areas outside of the South Coast Air Basin 

using CALPUFF/CALMET. SCAQMD supplemented this analysis with an analysis of subjectto - BART sources in the RECLAIM program using modeling based on the particulate modeling 

that was the basis for the PM2.5 attainment demonstration in the 2007 Air Quality Management 

Plan. 

Review Comment (summary of EPA comments on CRHP BART Modeling): The technical work of 

CARB and the SCAQMD in support of the CRHP was consistent with the best practices and science 

at the time it was performed. It is appropriate for the State of California to use it as the basis for 

complying with the requirements of the Regional Haze Rule.

 

 

28 RECLAIM Source Visibility Impact, page D-9, Table 7 presents results for the Deciview Analysis Joshua Tree 

Wilderness and is erroneously labeled Deciview Analysis for San Jacinto Wilderness. The correct Deciview 

Analysis for San Jacinto Wilderness is presented in Table 6. Telephone conversation between Joe Cassmasi, 

SCAQMD, and C. Bohnenkamp, USEPA, March 3, 2011. 

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