Draft: October 6, 2010 

1

 

Demonstration that the SO2 Milestones Provide Greater 

Reasonable Progress than BART 

A. Background 

In 1996 the Grand Canyon Visibility Transport Commission (GCVTC) submitted 

recommendations to EPA to improve visibility in the 16 Class I Areas on the Colorado Plateau. 

The GCVTC concluded that a broad-based approach that addressed multiple pollutants and 

source categories was necessary to reduce regional haze. The report recommended a series of 

strategies to address stationary sources, mobile sources, fire, pollution prevention, fugitive dust, 

and clean air corridors. 

On July 1, 1999 the Environmental Protection Agency (EPA) published regulations to address 

regional haze visibility impairment. The regulations required States to address Best Available 

Retrofit Technology (BART) requirements for regional haze visibility impairment, and allowed 

nine western states to develop plans that were based on the GCVTC recommendations for 

stationary sources in lieu of BART. 

In 2000, the Western Regional Air Partnership (WRAP) submitted an Annex to the GCVTC 

recommendations that provided more details regarding the regional SO2 milestones and backstop 

trading program that had been recommended in the GCVTC Report, and included a 

demonstration that the milestones achieved greater reasonable progress than would have been 

achieved by the application of BART in the region. The Annex was approved by EPA in 2003, 

but this approval was later vacated by the DC Circuit Court of Appeals in 2005 due to problems 

with the methodology that was required in the regional haze rule for demonstrating greater 

reasonable progress than BART.1 

On July 6, 2005 EPA revised the regional haze rule in response to the judicial challenges to the 

BART requirements. On October 13, 2006 EPA published additional revisions to address 

alternatives to source-specific BART determinations. 

Five western states (Arizona, New Mexico, Oregon, Utah, and Wyoming) and the City of 

Albuquerque had submitted State Implementation Plans (SIPs) in 2003 under 40 CFR §51.309. 

Three of those states (New Mexico, Utah, and Wyoming) and the City of Albuquerque plan to 

update their SIPs to include new milestones that are based on more recent emission inventories 

as well as the revised BART requirements in the regional haze rule. Arizona and Oregon are no 

longer participating in the program. This demonstration shows that the SO2 milestones will 

achieve greater reasonable progress than would have been achieved from the installation and 

operation of BART at all sources subject to BART in the participating states in accordance with 

the revised regional haze rule. 

1 Center for Energy and Economic Development v. EPA, February 18, 2005; American Corn Growers Association v. 

EPA, May 24, 2002. 
Draft: October 6, 2010 

2

B. RH Rule Requirements 

40 CFR 51.309(d)(4) states, “The milestones must be shown to provide for greater reasonable 

progress than would be achieved by application of BART pursuant to §51.308(e)(2).” 

40 CFR 51.308(e) 

...(2) A State may opt to implement or require participation in an emissions trading program or other 

alternative measure rather than to require sources subject to BART to install, operate, and maintain BART. 

Such an emissions trading program or other alternative measure must achieve greater reasonable progress 

than would be achieved through the installation and operation of BART. For all such emission trading 

programs or other alternative measures, the State must submit an implementation plan containing the 

following plan elements and include documentation for all required analyses: 

(i) A demonstration that the emissions trading program or other alternative measure will 

achieve greater reasonable progress than would have resulted from the installation and 

operation of BART at all sources subject to BART in the State and covered by the alternative 

program. This demonstration must be based on the following: 

(A) A list of all BART-eligible sources within the State. 

(B) A list of all BART-eligible sources and all BART source categories covered by the 

alternative program. The State is not required to include every BART source category or 

every BART-eligible source within a BART source category in an alternative program, 

but each BART-eligible source in the State must be subject to the requirements of the 

alternative program, have a federally enforceable emission limitation determined by the 

State and approved by EPA as meeting BART in accordance with section 302(c) or 

paragraph (e)(1) of this section, or otherwise addressed under paragraphs (e)(1) or 

(e)(4)of this section. 

(C) An analysis of the best system of continuous emission control technology available 

and associated emission reductions achievable for each source within the State subject to 

BART and covered by the alternative program. This analysis must be conducted by 

making a determination of BART for each source subject to BART and covered by the 

alternative program as provided for in paragraph (e)(1) of this section, unless the 

emissions trading program or other alternative measure has been designed to meet a 

requirement other than BART (such as the core requirement to have a long-term strategy 

to achieve the reasonable progress goals established by States). In this case, the State may 

determine the best system of continuous emission control technology and associated 

emission reductions for similar types of sources within a source category based on both 

source-specific and category-wide information, as appropriate. 

(D) An analysis of the projected emissions reductions achievable through the trading 

program or other alternative measure. 

(E) A determination under paragraph (e)(3) of this section or otherwise based on the clear 

weight of evidence that the trading program or other alternative measure achieves greater 

reasonable progress than would be achieved through the installation and operation of 

BART at the covered sources. 
Draft: October 6, 2010 

3

C. Identification of BART-Eligible Sources and Sources Subject to 

BART. 

Establishing BART emission limitations under 40 CFR 51.308(e)(1) is a three step process (70 

FR 39106): 

• States identify sources which meet the definition of BART eligible 

• States determine which BART eligible sources are “subject to BART” 

• For each source subject to BART the State identifies the appropriate control technology. 

 

1. BART-Eligible Sources. 

Pursuant to 40 CFR 51.308(e)(2)(i), States submitting §309 SIPs are required to list all BARTeligible sources covered by the alternative program. BART-eligible sources are identified as 

those sources that fall within one of 26 specific source categories, were built between 1962 and 

1977, and have potential emissions of at least 250 tons per year of any visibility impairing air 

pollutant (40 CFR 51.301). The BART-eligible sources identified by the three §309 States are 

shown in Table 1. 

2. Subject to BART Determination. 

Pursuant to 40 CFR 51.308(e)(2)(i)(B) and (e)(1)(ii), States are required to determine which 

BART-eligible sources are “subject to BART.” BART-eligible sources are subject to BART if 

they emit any air pollutant that may reasonably be anticipated to cause or contribute to any 

impairment of visibility in any mandatory Class I Federal area. §309 States have conducted 

individual source modeling to determine if a BART-eligible source causes or contributes to 

visibility impairment. 

Two of the §309 States (New Mexico and Utah) utilized the technical modeling services of the 

WRAP Regional Modeling Center (RMC). Modeling was performed according to the RMC 

modeling protocols (CALMET/CALPUFF Protocol for BART Exemption Screening Analysis 

for Class I Areas in the Western United States). For the WRAP BART exemption screening 

modeling, the RMC followed the EPA BART Guidelines (EPA, 2005) and the applicable 

CALMET/CALPUFF modeling guidance (e.g., IWAQM, 1998; FLAG, 2000; EPA, 2003c) 

including EPA’s March 16, 2006 memorandum: “Dispersion Coefficients for Regulatory Air 

Quality Modeling in CALPUFF” (Atkinson and Fox, 2006). 

The basic assumptions of the WRAP BART CALMET/CALPUFF modeling protocols are as 

follows. 

• Three years (2001, 2002 and 2003) were modeled. 

• Visibility impacts due to emissions of SO2, NOx and primary PM emissions were 

calculated. 

• Visibility was calculated using the original IMPROVE equation and “Annual Average 

Natural Conditions”. 

• The effective range of CALPUFF modeling was set at 300km from the sources. 
Draft: October 6, 2010 

4

• According to 40 CFR Part 51, Appendix Y (EPA BART Guidelines; EPA, 2005), 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.” 

• The threshold for visibility impact, for a single source, was a 0.5 deciview change or 

more to “contribute” to visibility impairment. This threshold is consistent with the EPA 

BART Guidelines (EPA 2005) that states, “As a general matter, any threshold that you 

use for determining whether a source ‘contributes’ to visibility impairment should not be 

higher than 0.5 deciviews.” This threshold is also consistent with long-standing visibility 

modeling practices. States have the discretion to set a lower threshold, but the three 

participating states have not determined that a lower threshold is needed or justified. 

The State of Wyoming performed modeling in-house that was also based on EPA BART 

Guidelines and the applicable CALMET/CALPUFF guidelines. The basic assumptions were the 

same as used in the RMC modeling with the following exception: meteorological data for 1995, 

1996, and 2001 that were prepared for a previous modeling analysis were used for the southwest 

Wyoming modeling domain. Wyoming’s BART Air Modeling Protocol, September 2006, is 

posted at http://deq.state.wy.us/aqd/BART.asp. 

Table 1. Subject to BART Status for §309 BART-Eligible Sources 

State Plant Name Unit BART 

Eligible 

Subject 

to BART 

Modeling 

Entity 

BART 

Category 

NM Amoco Empire Abo SRU Only Y N WRAP 15 

NM SWPS Cunningham Station (Xcel 

Energy) 

One Unit Y N WRAP 01 

NM Duke Energy Artesia Gas Plant SRU Only Y N WRAP 15 

NM Duke Energy Linam Ranch Gas Plant SRU Only Y N WRAP 15 

NM Dynegy Saunders SRU Only Y N WRAP 15 

NM Giant Refining San Juan Refinery Unit #1 FCCP ESP 

Stack 

Y N WRAP 11 

NM Giant Refining, Ciniza Refinery 4 B&W CO boiler Y N WRAP 11 

NM SWPS Maddox Station (Xcel Energy) One Unit Y N WRAP 01 

NM Marathon Indian Basin Gas Plant SRU Only Y N WRAP 15 

NM PNM, San Juan Units 1-4 Y Y WRAP 01 

NM Rio Grande Station One Unit Y N WRAP 01 

NM Western Gas Resources San Juan 

River Gas Plant 

SRU Only Y N WRAP 15 

UT PACIFICORP – Hunter Power Plant Units 1-2 Y Y WRAP 01 

UT PACIFICORP – Huntington Power 

Plant 

Units 1-2 Y Y WRAP 01 

WY BASIN ELECTRIC POWER COOP – 

LARAMIE RIVER 

Units 1-3 Y Y WY DEQ 01 

WY BLACK HILLS POWER & LIGHT = 

NEIL SIMPSON 1 

Unit 1 Y N WY DEQ 01 

WY Dyno Nobel (formerly Coastal 

Chemical) 

9 Units Y N WY DEQ 10 

WY FMC CORP – GREEN RIVER SODA 

ASH PLANT 

3 Units Y Y WY DEQ 22 
Draft: October 6, 2010 

5

WY FMC WYOMING CORP – 

GRANGER SODA ASH PLANT 

2 Units Y N WY DEQ 22 

WY GENERAL CHEMICAL – GREEN 

RIVER SODA ASH PLANT 

2 Units Y Y WY DEQ 22 

WY P4 PRODUCTION – ROCK 

SPRINGS COKING PLANT 

1 Unit Y N WY DEQ 22 

WY PACIFICORP – DAVE JOHNSTON Units 3-4 Y Y WY DEQ 01 

WY PACIFICORP – JIM BRIDGER Units 1-4 Y Y WY DEQ 01 

WY PACIFICORP – NAUGHTON Units 1-3 Y Y WY DEQ 01 

WY PACIFICORP –WYODAK Unit 1 (335 MW) Y Y WY DEQ 01 

WY SINCLAIR OIL CORP-SINCLAIR 

REFINERY 

16 units Y N WY DEQ 11 

WY SINCLAIR REFINERY – CASPER 1 unit Y N WY DEQ 11 

D. Baseline Inventory for 2018 

The Stationary Sources Joint Forum of the WRAP coordinated the development of a baseline 

inventory for 2018 that was used to update the SO2 milestones for the 3-state region. The 

inventory was estimated as described below. 

1. Electric Generating Units (EGU’s) 

The methodology for projecting existing EGU's into the future involves the following steps: 

a) the electricity production (MW's) for each individual unit at a plant was determined 

from the Energy Information Administration [EIA] (data available for 2002-05) 

b) the electricity generation design maximum capacity (MW's) was determined for each 

individual unit from EIA data 

c) an operating Capacity Factor was determined by dividing the year specific production 

by the design maximum capacity of the each individual plant unit 

d) all individual units were assumed to be operating at 85% capacity in 2018 (unless they 

were already operating above this level in 2002) 

e) the Growth Ratio necessary to achieve 85% capacity was determined by dividing 0.85 

by the Capacity Factor for each individual plant unit (averaged over four years) 

f) a Current Year Emission Factor (lb SO2/MM-Btu) was calculated for the latest year of 

available EIA data (2006), using the actual reported emissions (tons SO2) for each 

individual plant unit divided by the actual reported annual heat generation (MM Btu) 

g) the 2018 Emission Factor was assumed to be the same as the current emission factor, 

except for a few sources that had a new permitted emission rate. 

h) the 2018 Emission Rate (tons SO2) was calculated by multiplying current year 

emissions by the ratio of the 2018 to current year Emission Factors 

i) the Adjusted 2018 Emission Rate (tons SO2) was "grown" to 85% capacity by 

multiplying the 2018 Emission Rate by the Growth Ratio from Step 5 

(emissions from units already operating at or higher than the 85% capacity in the 

2002 data year, were not grown, but accepted at face value). 
Draft: October 6, 2010 

6

2. Permitted/Future EGU’s 

The PRP 18b inventory is documented in the ERG Final Technical Memorandum dated October 

16, 2009. The Memorandum projects the need for 61.99 billion kWh of future coal-fired 

electricity generation between 2002 and 2018. Of this total, 36.37 billion kWh will be met by 

increased utilization of existing plants, and the addition of new plants that are already under 

construction. The remaining 25.62 billion kWh will be met by new coal plants in the WRAP 

region. The §309 States estimate that 25% of that total will be constructed in the 3-state region, 

with an emission estimate of 2,600 tons SO2 by 2018. 

a) Growth estimates in 2008 SIPs. 

The previous SO2 milestones were finalized by the §309 States in the Spring of 2008 

and were adopted into the SIPs for Albuquerque, Utah, and Wyoming later that year. 

The milestones included a new source growth estimate of 20,000 tons SO2 for 

utilities. This new source growth estimate was drawn from the PRP18a inventory that 

relied on the 2007 EIA projections. As part of the technical demonstration for the 

SIPs, the §309 States identified projects that were under construction or had been 

permitted that would have consumed about 10,000 tons of the new source set-aside. 

b) Changes in Underlying Assumptions. 

During the last two years there have been significant changes in the EIA projections 

for future growth of coal-fired electricity generation. The PRP18b inventory that is 

documented in the ERG Final Technical Memorandum dated October 16, 2009 has 

scaled back the projections of growth of coal-fired utilities. EPA has indicated that 

this more recent information calls into question the estimates for future growth in 

coal-fired generation in the current milestones. In addition, the State of Arizona has 

elected to develop a SIP under Section 308 of the Regional Haze rule, further 

reducing the new source set-aside. 

c) Updated New Source Growth Estimates. 

The §309 States have reviewed the new Memorandum and have determined that the 

new source growth estimate should be reduced from 20,000 tons SO2 to 6,600 tons 

SO2. Of this total, approximately 4,000 tons SO2 can be attributed to new units in 

Wyoming that are currently operating, or have commenced construction (Wygen 

Units II and III, Dry Fork Station, and Two Elk Unit 1). This leaves a remaining 

estimate of new source growth that has not been attributed to a specific plant of 2,600 

tons SO2. 

This estimate is consistent with the 2009 ERG Final Technical Memorandum. As 

outlined in Table 3 of that Memorandum (summarized below) an additional 61.99 

billion kWh of coal-fired electricity generation will be needed between 2002 and 

2018. 
Draft: October 6, 2010 

7

Future Coal-Fired Electricity Generation (billion kWh) 

258.7 2002 Electricity Generation 

320.69 2018 Electricity Generation 

61.99 Needed Generation 

Future Coal-Fired Electricity Generation from existing sources, and those under 

construction (billion kWh) 

16.6 Unused capacity at existing 2002 Facilities 

5.34 Capacity at post-2002 facilities 

14.43 Estimated generation capacity of the 6 EGUs under construction 

36.37 Total 

25.62 New Source Growth needed in WRAP Region (billion kWh) 

As shown above, 36.37 billion kWh can be met by the combination of unused 

capacity from existing sources plus new sources that are in operation or under 

construction (including the three plants in Wyoming that are described above). This 

leaves a remaining 25.62 billion kWh that would be met by new coal plants in the 

region. 

The need for new source growth beyond what is already under construction is 

supported by estimates of future electricity demand in the region. For example, the 

Integrated Resource Plan submitted by PacifiCorp to the Utah Public Service 

Commission in May 2009 estimates a capacity deficit of 3,520 MW by 2018. The 

IRP meets that deficit through a combination of new natural gas-fired plants, 

renewable resources, and demand side management and does not include plans for 

new coal-fired generation. This is a change from the 2006 IRP (submitted in 2007), 

that included plans for new coal generation in Utah (340 MW) and Wyoming (527 

MW) by 2018. However, the 2008 IRP also increased the estimated front office 

transactions (power purchased on the open market), from 249 MW in the 2006 IRP to 

800 MW in the 2008 IRP for the year 2018. Because future demand exceeds existing 

capacity as shown in Table 3 of the ERG Final Technical Memorandum, it is 

reasonable to assume that new plants (including potential merchant plants built by 

other entities) will be needed to meet this demand for purchased power in 2018. 

Table 4 in the Final Technical Memorandum identifies 8,880 MW that are being 

permitted in the region. The Memorandum states, “However, if 39% of the new coalfired EGU plant capacity currently in the permitting process is brought on-line, then 

the 2008 coal-fired EIA projection for 2018 will be met.” (see page 7). Therefore, the 

estimate of future coal-fired EGUs in the 12-state region is 3,463 MW. 

Approximately 25% of the MWs listed in Table 4 as “being permitted” are located in 

Utah and Wyoming, therefore it is reasonable to estimate that 900 MWs (conservative 

emission estimate of 2,600 tons SO2) of future coal-fired EGUs be attributed to the 

§309 States. 
Draft: October 6, 2010 

8

3. Non-EGU's 

The Methodology for projecting emissions from "Other Industrial Sources" is described in E.H. 

Pechan's October 2006 Report, 2018 SO2 Emissions Evaluation for Non-Utility Sources- Final. 

The report is posted online at 

http://www.wrapair.org/forums/ssjf/documents/eictts/projections.html. 

a) The SO2 emissions for 19 Natural Gas Processing Plants were updated by Environ in 

April 2007, with additional research into future O&G Operations. The September 

2007 Final report with results of that update is posted at 

http://www.wrapair.org/forums/ssjf/documents/eictts/oilgas.html. 

b) The 2005 SO2 Milestone Report had some sources which were not picked up in the 

Pechan report. In those cases, the 2005 emissions were used as a placeholder for the 

2018 emission values. 

c) The projections do not specifically break out emissions from existing sources vs. new 

sources. For purposes of establishing a new source set-aside, 2006 emissions were 

assumed to be the baseline emissions for existing sources, and the projected increase 

in emissions between 2006 and 2018 is attributed to new source growth. 

There have been steady SO2 emission reductions from the non-utility sector since 1990. Several 

major sources were shut down, including two copper smelters (BHP San Manuel and Phelps 

Dodge Chino: 69,491 tons SO2 in 1990) and a steel mill (Geneva Steel: 8,473 tons SO2 in 

1990). Kennecott Utah Copper reduced SO2 emissions by 25,000 tons SO2 during the mid1990s. During this same time period, oil and gas production increased substantially in all three 

states requiring upgrades to processing plants and other facilities to address potential air quality 

problems. These upgrades have largely been completed, and it is anticipated that future 

emissions will reflect growing demand for natural gas in the Western US. As can be seen in 

Figure 1, emissions have leveled off in recent years and are likely to increase as the US emerges 

from a major recession in coming years. The 2006 EH Pechan report describes in detail the 

methodology that was used to project future emissions for each source category. 
Draft: October 6, 2010 

9

Nonutility SO2 Emission Trends 2000-2008

0

20000

40000

60000

80000

100000

120000

1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Nonutility

Figure 1. Non-utility Emission Trends 

Table 2 summarizes the projected 2018 Baseline SO2 emissions for the 3-State region. 

Table 2. 2018 Baseline 

Projected 2018 SO2

Emissions 

Baseline 

Utility 128,409 

Non-Utility 49,961 

New Source Growth Utility 6,600 

New Source Growth Non-Utility 5,686 

Total 2018 Baseline 190,656 
Draft: October 6, 2010 

10

E. Estimated Emission Reductions Due to BART 

The SO2 milestones and backstop trading program were designed primarily to achieve 

reasonable progress towards meeting the long-term visibility goal. As outlined in the regional 

haze rule, in cases where the an alternative program has been designed to meet requirements 

other than BART, States are not required to make BART determinations under 40 CFR 51.308(e) 

and may use simplifying assumptions in establishing a BART benchmark based on an analyisis 

of what BART is likely to be for similar types of sources within a source category. Emission 

estimates for 2018, assuming the application of BART for SO2 on all subject-to-BART sources 

in the three states, were prepared and are compiled in a spreadsheet named “8-11-

10_milestone.xls” (see technical support documentation). The 2018 estimates for these sources 

are estimates of actual emissions and therefore reflect greater emission reductions than would be 

enforceable in a case-by-case BART permit. The methodology that was used to estimate these 

emission reductions is described below. 

1. Utilities - Presumptive BART. 

All utilities that were determined to be subject to BART were assumed to be operating at the 

presumptive emission rate established in 40 CFR Part 51, Appendix Y (0.15 lb/MMBtu). Actual 

emissions at this presumptive emission rate were estimated for 2018. 

2. Other sources. 

The SO2 milestones were primarily designed to achieve reasonable progress for all sources of 

SO2 in the 3-state region and therefore the regional haze rule allows States to use simplifying 

assumptions in establishing the BART benchmark. EPA has not established presumptive 

emission rates for nonutilities, therefore another approach was needed to estimate emission 

reductions from four boilers located at 2 trona facilities in SW Wyoming. . Recent pollution 

control projects achieved a 63% reduction in SO2 from two of the boilers, and represent 

reasonably stringent controls, considering the age and purpose of the facility. Therefore, the 

emission rate achieved by these projects is used as the BART benchmark for the four boilers. 

I. General Chemical Soda Ash Partners, Green River Plant 

C Boiler 

Constructed in 1/74 

Fuel Analysis for coal: 262,800 tons/year; 534 x 10e6 BTU/hr site rated capacity 

Emission limit for SO2 1.2 lb/MMBtu; 640.8 lb/hr; 2806.7 TPY 

D Boiler 

Constructed in 1/75 

Fuel Analysis for coal: 388,000 tons/year; 880 x 10e6BTU/hr site rated capacity 

Emission limit for SO2 1.2 lb/MMBtu; 1056.0 lb/hr; 4625.3 TPY 
Draft: October 6, 2010 

11

II. FMC Wyoming Corporation Westvaco Facility 

NS-1A 

Constructed in 1975 

Modified 8/2007 (New chevron mist eliminators installed in venturi scrubber) 

Fuel Analysis coal: 380,888 tons/year; 887 x 10e6 BTU/hr site rated capacity 

Emission limit for SO2 0.54 lb/MMBtu; 

NS-1B 

Constructed in 1975 

Modified 7/2008 (New chevron mist eliminators installed in venturi scrubber) 

Fuel Analysis coal: 380,888 tons/year; 887 x 10e6 BTU/hr site rated capacity 

Emission limit for SO2 0.54 lb/MMBtu 

All four boilers were originally constructed in SW Wyoming for purposes of processing trona in 

the mid 1970’s. As process units, these four boilers are subject to greater load swings than would 

be experienced at electric generating units which typically come up to full operating levels and 

stay there. All four boilers were at one time operating under emission limits of 1.2 lb/MMBtu. 

All four boilers are roughly the same size with site rated capacities between 880 MMBtu/hr and 

887 MMBtu/hr except for the oldest boiler, C Boiler at General Chemical at Green River rated at 

534 MMBtu/hr. All four boilers burn primarily coal with oil and gas used as start up fuels. All 

four units have been participating in the SO2 Backstop Trading Program, reporting inventories 

annually as required by Wyoming Air Quality Standards and Regulations. 

Two of the four units, NS1A and NS1B operated by FMC, sought early SO2 reductions in 2007 

and 2008 respectively as participants in the 309 program. These two units reduced SO2

emissions by 55 percent or 5126 tons collectively from both units. New chevron mist 

eliminators were installed on venturi scrubbers to accomplish this reduction. Since that time, 

FMC has reviewed additional reductions resulting in a total reduction from the 2018 baseline of 

5827 tons or an additional 701 tons. Total reduction from the 1.2 lb/MMBtu emission rate is a 

63 percent removal rate. The State of Wyoming has reviewed these additional reductions and has 

determined that they represent reasonably stringent controls, considering the age and purpose of 

the facility. 

In a similar fashion, the State has reviewed potential SO2 reductions at the General Chemical 

facility at Green River and had concluded that a 63 percent removal rate is also appropriate for 

the two boilers located at that facility. As was mentioned above, these facilities are similar in 

age, and purpose. General Chemical boilers C and D are currently permitted at 7,432 tons of 

SO2 operating at 1.2 lb/MMBtu. The State would expect that reasonably stringent controls at 

this facility would result in a similar 63 percent reduction from the same starting point of 1.2 

lb/MMBtu. Reviewing reductions from the 2018 milestone baseline, the General Chemical 

boilers would be looking at reducing emissions by 2,669 tons. 

While the 2018 milestone baseline level is not the same for the two companies, the state has 

determined that equitable treatment of like facilities would require similar reductions from the 

two companies prior to the 309 program. Both companies would be reducing emissions from a 

starting point of 1.2 lb/MMBtu down to 0.45 lb/MMBtu. In the case of FMC, who made early 
Draft: October 6, 2010 

12

reductions in the program, an additional 701 ton reduction is expected to be achieved. In the 

case of General Chemical, 2,669 tons will be achieved. The total reduction from both facilities 

has been estimated at 3,370 tons. The State has determined that these are reasonably stringent 

controls and the resulting emissions would serve as an adequate BART benchmark. 

 

3. Summary. 

The estimated emission reductions due to the application of BART in the §309 States are 

summarized in Table 3. 

Table 3. Emission Reduction due to BART 

2018 baseline SO2 2018 SO2 with BART Emission Reduction 

due to BART 

Utilities 128,409 82,972 45,437 

Non-Utilities 49,961 46,661 3,370 

Total 48,807 

F. 2018 BART Benchmark 

2018 Baseline 190,656 

Estimated BART Reductions -48,807

Total 141,849 

G. Milestones Provide Greater Reasonable Progress than BART 

The Regional SO2 milestone of 141,849 equals the BART benchmark, but provides greater 

reasonable progress than BART for the reasons outlined below. 

1. Early Reductions. 

The GCVTC recommended that the market trading program "contain specific provisions to 

encourage and reward early emission reductions, including reductions achieved before 2000."2

 

The GCVTC committed to achieve a 13% reduction in SO2 emissions from stationary sources by 

the year 2000. The GCVTC also recognized that there was a good possibility that actual 

emission reductions would be greater than this 13% goal. A general plan was derived to give 

some early reductions credit to the region and some to the environment. The emission reductions 

 2 Recommendations for Improving Western Vistas at 33 (June 1996).
Draft: October 6, 2010 

13

 

that were greater than 13% were to be split, with 1⁄2 going to the environment (through the 

establishment of milestones) and the other 1⁄2 providing headroom.3

Sulfur dioxide emissions decreased by 25% in the 9-state GCVTC region between 1990 and 

2000, and SO2 emissions in the three §309 states 33% in that same time period. 

The regional milestones have been in effect since 2003 when the original five participating states 

submitted regional haze SIPs, as required by section 309 of the regional haze rule. The 2003 SIP 

was designed to provide flexibility so that sources could find the most cost-effective way to 

reduce SO2 emissions, including over-controlling some plants while opting for lower cost 

controls at other plants. The 2003 SIP was also designed to encourage early reductions by 

providing an extra allocation for sources that made reductions prior to the program trigger year. 

The 2003 SIP influenced the long term planning for sources in the region, and utilities began 

upgrading plants based on the provisions of the SIP years earlier than would have been required 

under a case-by-case BART determination in a §308 SIP. 

Emissions in the 3-state region decreased an additional 31% between 2000 and 2008.4

Figure 2 shows the emission reductions from 1990 baseline emissions in the §309 states that will 

have been achieved by 2018. This total 60% reduction from 1990 emissions is well on the way 

to the GCVTC goal of reducing SO2 emissions by 50% - 70% by the year 2040. 

Figure 3 shows the sulfate contribution to visibility at the long-term IMPROVE sites located on 

the Colorado Plateau. As can be seen from these graphs, there has been a steady decrease in the 

visibility impact due to sulfates. The trend is especially apparent on the 20% best days that are 

not affected by the variability of fire emissions in the region. 

3

 Id. at 34.

4 WRAP 2008 Regional Emissions and Milestone Report, March 31, 2010. 
Draft: October 6, 2010 

14 

§309 SO2 Backstop Cap and Trade Program - 

Emissions, Modeling EI, and Milestone Program Data 

(no tribal sources)

-

50,000

100,000150,000200,000250,000300,000350,000400,000

Tons per year

NM 140,177 79,011 37,918 31,068 31,012 UT 84,983 37,483 42,183 44,175 35,429 WY 133,204 122,373 120,991 113,465 96,809 3-State Total 358,364 238,867 201,092 188,708 200,722 155,940 163,250 141,84

1990 2000 2002 (Plan02d) 2006 Milestone Report 2008 Milestone 2013 Milestone 2018 (PRP18b) 2018 Miles

Figure 2. Emission Trends 
Draft: October 6, 2010 

15 

Figure 3. Sulfate Contribution to Light Extinction at Class I Areas on the Colorado Plateau.5 

Series – Aggregation: Best 20%, Worst 20%, Best 20% 2000-2004 Baseline, Worst 20% 2000-2004 Baseline, 

Metadata – Program: IRHR2, Poc: 1, Parameter: ammSO4_bext, Method: RHR Dataset. 

 

5

 Only those Class I areas on the Colorado Plateau with at least 15 years of data are included in this figure. 
Draft: October 6, 2010 

16 
Draft: October 6, 2010 

17 
Draft: October 6, 2010 

18 

 

2. Additional Sources Included. 

The backstop trading program includes all stationary sources with emissions greater than 100 

tons/year of SO2. The §309 States designed this program as part of an overall strategy to address 

all sources of visibility impairing pollutants, rather than focusing on a subset of stationary 

sources. 

 2006 

Number of Sources Emissions Percentage 

Subject to BART 10 121,542 62% 

Other Stationary Sources 63 73,038 38% 

The inclusion of all major SO2 sources in the program is necessary to create a viable trading 

program, and also serves a broader purpose to ensure that growth in emissions from sources that 

are not subject to BART does not undermine the progress that has been achieved. BART applied 

on a case-by-case basis would not affect these sources, and there would be no limitation on their 

future operations under their existing permit conditions. Because the milestones will cap these 

sources at actual emissions (which are less than current allowable emissions), the overall effect 

of their inclusion is to provide greater reasonable progress than would have been achieved if only 

sources that are subject to BART were included in the program. 

3. Cap on New Source Growth. 

When Congress established the visibility program in 1977 it declared as a national goal "the 

prevention of any future, and the remedying of any existing" anthropogenic visibility impairment 

in mandatory class I federal areas.6 BART is an emission limitation established at a specific 

source and is designed as a remedy to impairment at specific mandatory Class I areas. By 

contrast, the SO2 milestones developed by the §309 States serve the dual purpose of remedying 

existing impairment and preventing future impairment by requiring regional SO2 emissions 

reductions and capping emissions for stationary sources. Future impairment is prevented by 

capping emissions growth from sources not eligible under the BART requirements, from sources 

subject to BART that are expected to significantly increase utilization, and from entirely new 

sources in the region. 

The milestones include estimates for growth, but then lock these estimates in as an enforceable 

emission cap. The milestone approach is consistent with the statutory goal of preventing any 

future visibility impairment that results from man-made air pollution. The entire region is 

experiencing rapid growth which could erode the progress that has been achieved in the last two 

decades towards improving visibility. BART applied on a case-by-case basis would have no 

impact on future growth, and in the long run would not achieve the regional emission reductions 

that are guaranteed by the program. 

6

 CAA § 169A(a)(1).
Draft: October 6, 2010 

19 

 

4. Commission Strategies are a Total Package. 

The GCVTC recommendations were developed as a comprehensive strategy includes strategies 

to address mobile sources, prescribed fire, pollution prevention, and Clean Air Corridors. The 

stationary source strategies need to be viewed as part of this overall package. Visibility 

impairment in the west is caused by multiple sources and pollutants, and a narrow focus on 

stationary sources may not achieve the same results as a broad-based program. When viewed as 

part of the entire SIP, the milestones achieve much greater reasonable progress than BART. 

5. Mass Based Cap has Inherent Advantages over BART 

The baseline emission projections and assumed reductions due to the assumption of BART-level 

emission rates on all sources subject to BART are all based on actual emissions, using 2006 as 

the baseline. The use of actual emissions has an effect in several ways. If the BART process 

was applied on a case-by-case basis to individual sources, emission limitations would typically 

be established as an emission rate (lbs/hr or lbs/MMBtu) that would account for variations in the 

sulfur content of fuel and alternative operating scenarios. The difference between actual 

emissions and allowable emissions is particularly large when a source is permitted to burn two 

different fuel types, such as oil and natural gas, or when the source is part of a cyclical industry 

where production varies from year to year due to the changing demand for their product. A 

mass-based cap that is based on actual emissions is more stringent because it does not allow a 

source to consistently use this difference between current actual and allowable emissions. 

Another difference is that mass-based limits will include excess emissions that may occur due to 

malfunctions or during the start-up or shut-down of emission units. A good example of this 

difference is the requirement in the acid rain program that emissions must be assumed to be the 

highest value recorded from the past year during the time period that continuous emission 

monitors are not functioning on a stack. These higher emissions are calculated as part of the 

overall tons/year, and must be accounted for under the mass-based cap for the acid rain program. 

6. Tribal Setaside 

The GCVTC recommended a market based program to address stationary source emissions of 

SO2. The GCVTC recommended that the market based program include allocations to tribes that 

are of practical benefit.7

 This recognized the concern that "tribes, by and large, have not 

contributed to the visibility problem in the region" and that "[t]ribal economies are much less 

developed than those of states, and tribes must have the opportunity to progress to reach some 

degree of parity with states in this regard."8

 The tribes specifically recommended that if an 

emission trading strategy is adopted to achieve SO2 reductions from stationary sources that 

allocations be based on considerations of equity rather than historical emissions: 

7

 Recommendations for Improving Western Vistas (June 1996). at 35. 

8

Id. at 66-67. 
Draft: October 6, 2010 

20 

 

Credits should not be based on historical emissions, but should be based on equitable 

factors, including the need to preserve opportunities for economic development on tribal 

lands. In general, these lands are currently lacking in economic bases and have not 

contributed to the visibility problems.9

Accordingly, the backstop trading program contains a 2,500 allocation to tribes in the GCVTC 

region. Case-by-case BART permits would not provide this practical benefit to tribes that was 

an integral part of the GCVTC recommendations. 

7. Other Class I Areas Also Show Improvement in Visibility 

In addition to demonstrating successful SO2 emission reductions, §309 states have also relied on 

visibility modeling conducted by the WRAP to demonstrate improvement at Class I areas. The 

complete modeling demonstration showing deciview values was included as part of the visibility 

improvement section in each of the state §309 SIPs, but the SO2 portion of the demonstration has 

been included below as Table 4 to underscore the improvements associated with 309 SO2

reductions and further demonstrate why the 309 program is better than BART. 40 CFR 

51.309(g)(2)(i) allows states to build upon the strategies implemented in a 309 program and take 

full credit for visibility improvement achieved through these strategies when addressing 

additional Class I areas. This table demonstrates achievements in visibility in these additional 

Class I areas (off the Colorado Plateau) in and surrounding the three states participating in the 

309 program. For the most part, the table shows projected visibility improvement for 2018 with 

respect to SO2 on the worst days and no degradation on the best days. There is one Class I area 

in New Mexico off the Colorado Plateau that is not showing improvement on the worst days. 

The State of New Mexico has reviewed the emissions data related to impacts in the Gila 

Wilderness and has determined that the visibility degradation is largely due to increasing point 

source emissions from Mexico. 

9

Id. at 71.
Draft: October 6, 2010 

21 

Table 4. Visibility - Sulfate Extinction Only

20% Worst Visibility Days 

(Monthly Average, Mm-1) 

20% Best Visibility Days 

(Monthly Average, Mm-1) 

Class I Area Monitor 

(Class I Areas Represented) 2018 1

Base Case 

(Base 18b) 

2018 2

Preliminary 

Reasonable 

Progress Case 

(PRP18a) 

2018 1

Base Case 

(Base 18b) 

2018 2

Preliminary 

Reasonable 

Progress Case 

(PRP18a) 

Bridger, WY 

(Bridger WA and Fitzpatrick WA) 5.2 4.3 1.6 1.3 

North Absaroka, WY 

(North Absaroka WA and Washakie WA) 4.8 4.5 1.1 1.1 

Yellowstone, WY 

(Yellowstone NP, Grand Teton NP and Teton WA) 4.3 3.9 1.6 1.4 

Badlands, SD 17.8 16.0 3.5 3.1 

Wind Cave, SD 13.0 12.1 2.7 2.5 

Great Sand Dunes NM, CO 5.3 4.9 2.0 1.8 

Mount Zirkel, CO 

(Mt. Zirkel WA and Rawah WA) 4.6 4.1 1.4 1.3 

Rocky Mountain, CO 6.8 6.2 1.3 1.1 

Gates of the Mountains, MT 5.3 5.1 1.0 1.0 

UL Bend, MT 9.7 9.6 1.8 1.7 

Craters of the Moon, ID 5.8 5.5 1.5 1.5 

Sawtooth, ID 3.0 2.8 1.2 1.1 

Bandelier NM, NM 6.4 5.9 2.4 2.2 

Bosque del Apache NWRW, NM 7.0 6.6 2.7 2.5 

Gila W, NM 6.2 6.7 1.8 1.8 

Salt Creek NWRW, NM 14.4 14.0 3.3 3.1 

Wheeler Peak, NM 

(Pecos W and Wheeler Peak W) 4.7 4.4 1.1 1.0 

White Mountain W, NM 8.9 8.7 1.8 1.7 

Great Basin NP, NV 4.1 4.1 1.2 1.2 

Jarbidge W, NV 3.8 3.4 1.3 1.2 

Chiricahua, AZ 

(Chiricahua NM, Chiricahua W, Galiuro W) 7.4 7.4 2.2 2.1 

Ike’s Backbone, AZ 

(Mazatzal W, Pine Mountain W) 6.1 5.9 2.2 2.1 

Queen Valley, AZ 7.5 7.5 3.0 3.0 

Saguaro NM, AZ 7.1 6.8 2.6 2.5 

Saguaro West, AZ 7.3 7.1 3.2 3.1 

Sierra Ancha, AZ 6.0 5.8 2.2 2.1 

Superstition, AZ 6.7 6.5 2.7 2.6 

Guadalupe Mountains NP, TX 

(Carlsbad Caverns NP, NM and Guadalupe 

Mountains NP, TX) 

13.7 13.6 3.3 3.2 

1

 Represents 2018 Base Case growth plus all established controls as of Dec. 2004. No BART or SO2 Milestone assumptions were included. 2

 Represents 2018 Preliminary Reasonable Progress growth estimates and established SO2 limits. 
Draft: October 6, 2010 

22 

 

H. Comparison of Trading vs Command and Control BART 

Requirements 

During the development of the Annex, the WRAP conducted modeling to determine whether the 

distribution of emissions under the backstop trading program would differ substantially from the 

distribution of emissions assuming installation of BART or would disproportionately impact any 

Class I area due to a geographic concentration of emissions. The results of this modeling are 

included in Tables 2 and 3 of Attachment C to the Annex10.

 Attachment C, Section G concludes, 

“The results of this analysis showed that the maximum difference between the two scenarios at 

any of the Class I areas was only 0.1 deciviews.11” 

10 Voluntary Emissions Reduction Program for Major Industrial Sources of Sulfur Dioxide in Nine Western States 

and A Backstop Market Trading Program, an Annex to the Report of the Grand Canyon Visibiltiy Transport 

Commission (September 2000) at C-15 and 16. 

11 Id. at C-21.