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October 31, 2014 

Submitted via www.regulations.gov and electronic mail 

Attention Docket ID No. EPA-R09-OAR-2014-0647 

Thomas Webb 

EPA Region 9 

Air Division (AIR-2) 

75 Hawthorne Street 

San Francisco, CA 94105 

Re: Arizona Regional Haze – Apache BART Alternative 

Dear Mr. Webb: 

 On behalf of National Parks Conservation Association and Sierra Club (collectively, the 

“Conservation Organizations”); Earthjustice respectfully submits the following comments 

regarding the Environmental Protection Agency’s (EPA) proposed Best Available Retrofit 

Technology (BART) alternative for the Apache Generating Station. Apache BART Alternative 

Proposed Rule, 79 Fed. Reg. 56,322 (Sept. 19, 2014). 

The Conservation Organizations appreciate EPA’s extensive work on the Arizona 

regional haze plan and its commitment to improving visibility at the many renowned national 

parks and wilderness areas in Arizona and neighboring states. Unfortunately, the proposed 

BART alternative is not on par with EPA’s earlier BART determination for Apache and will 

result in greater air pollution and worse visibility at some Class I areas. Because the Apache 

BART alternative does not make greater reasonable progress than BART, Arizona’s iconic Class 

I areas would not receive the full protections they are due under the regional haze program if 

EPA issues a final rule approving the proposal. Fortunately, if EPA makes some relatively minor 

modifications to improve the alternative in the final rule, it appears that the Apache BART 

alternative might be better than BART. Accordingly, the Conservation Organizations urge EPA 

to consider amending the proposal so that it fully complies with the regional haze program. 

 

BACKGROUND 

I. The Clean Air Act’s Regional Haze Program 

Americans have long valued our nation’s diverse and stunning natural scenery. John 

Copeland Nagle, The Scenic Protections of the Clean Air Act, 87 N.D. L. Rev. 571, 576 (2011). 

In what has been lauded as “America’s best idea,” Congress first set aside national parks in the 

19th century to preserve and celebrate some of the nation’s most spectacular scenery. Id. With 

the nation’s rapid industrialization, however, these remarkable scenic views have become 
Arizona Regional Haze – Apache BART Alternative 2

increasingly marred by air pollution. See id. at 573. Today, air pollution is “perhaps the greatest 

threat to national parks,” and pollution all too often degrades visibility in these iconic scenic 

areas. Id. 

To reduce this threat to national parks and other treasured public lands, Congress 

amended the Clean Air Act in 1977. 42 U.S.C. § 7491. Congress determined that national parks, 

wilderness areas, and other “Class I” federal areas should enjoy the highest level of air quality, 

and it set a national goal of eliminating all human-caused visibility impairment at these areas. Id. 

§ 7491(a)(1). After concluding that EPA and the states had not made adequate progress toward 

reducing visibility impairment caused by numerous sources located across a large geographic 

area (i.e., regional haze), Congress again amended the Clean Air Act in 1990 to spur regional 

haze reductions. Id. § 7492. The Act delegates implementation of the regional haze program to 

EPA. Id. §§ 7491, 7492. 

EPA set a goal of achieving natural visibility conditions at every Class I area by 2064, 

and the agency directed states to make incremental, reasonable progress toward that goal. 40 

C.F.R. § 51.308(d)(1)(i)(B), (d)(1)(ii). States and EPA are to make reasonable progress toward 

the 2064 natural visibility goal by issuing regional haze plans that improve visibility at a pace 

sufficient to eliminate human-caused visibility impairment at each Class I area by 2064. See id.

This steady, incremental rate of visibility improvement to the 2064 goal is referred to as the 2064 

“glide path” or the “uniform rate of progress.” See Arizona Phase 2 Proposed Rule, 77 Fed. Reg. 

75,704, 75,714 (Dec. 21, 2012) (“The [glide path or uniform rate of progress] is represented as a 

straight line drawn between a given Class I area’s 2004 baseline value and 2064 natural 

condition . . . .”). 

 One of the primary mechanisms to achieve the overarching reasonable progress mandate 

is the requirement that certain sources install Best Available Retrofit Technology (BART) 

pollution controls. 42 U.S.C. § 7491(b)(2)(A); 40 C.F.R. § 51.308(e). A source is “BARTeligible” if it is within one of 26 source categories, it was built between 1962 and 1977, and it 

has the potential to emit more than 250 tons per year of any air pollutant. 42 U.S.C. § 

7491(b)(2)(A), (g)(7); 40 C.F.R. § 51.301. BART is defined as “an emission limitation based on 

the degree of reduction achievable through the application of the best system of continuous 

emission reduction.” 40 C.F.R. § 51.301 (emphasis added). States and EPA must consider five 

factors when making BART determinations: (1) the costs of compliance, (2) the energy and nonair quality environmental impacts, (3) existing pollution controls in use at the source, (4) the 

source’s remaining useful life, and (5) the reasonably anticipated visibility improvements. 42 

U.S.C. § 7491(g)(2); 40 C.F.R. § 51.308(e)(1)(ii)(A). BART is an essential component of the 

regional haze program because Congress largely grandfathered the antiquated sources subject to 

BART into many of the Clean Air Act’s requirements. See 2005 Regional Haze Rule, 70 Fed. 

Reg. 39,104, 39,111 (July 6, 2005). Consequently, many of these older sources have insufficient 

pollution controls. BART compels these disproportionately-polluting sources to install up-to-date 

and cost-effective pollution controls. 

States and EPA may implement a BART alternative in lieu of BART if the alternative 

“achieve[s] greater reasonable progress than would be achieved through the installation and 

operation of BART” controls.” 40 C.F.R. § 51.308(e)(2). The regional haze regulations provide a 
Arizona Regional Haze – Apache BART Alternative 3

two-part test to determine whether a BART alternative is better than BART. First, if the 

“distribution of emissions is not substantially different than under BART,” the alternative is 

better than BART if it results in greater emissions reductions. Id. § 51.308(e)(3). Second, if the 

“distribution of emissions is significantly different,” States or EPA must conduct dispersion 

modeling demonstrating that “(i) Visibility does not decline in any Class I area, and (ii) There is 

an overall improvement in visibility, determined by comparing the average differences between 

BART and the alternative over all affected Class I areas.” Id. This modeling is based on the 

difference between BART and the BART alternative on the worst and best 20% days. Id. If there 

are technical limitations precluding application of the two-part test or there is strong confidence 

the alternative will lead to visibility benefits, a State or EPA may conclude that an alternative is 

better than BART if the “clear weight of evidence” shows the alternative achieves greater 

reasonable progress than BART. Id. § 51.308(e)(2)(i)(E); BART Alternative Final Rule, 71 Fed. 

Reg. 60,612, 60,622 (Oct. 13, 2006); BART Alternative Proposed Rule, 70 Fed. Reg. 44,154, 

44,158 (Aug. 1, 2005). 

II. The Arizona Regional Haze Plan’s Benefits 

Arizona is home to a wealth of iconic national parks and wilderness areas, such as Grand 

Canyon, Saguaro, and Petrified Forest National Parks. Pollution from Arizona sources obscures 

the scenic views in at least thirty Class I areas in Arizona and nearby states. Arizona Phase 2 

Proposed Rule, 77 Fed. Reg. at 75,713. Air pollution from Apache Generating Station impairs 

visibility at nine of these Class I areas, including Saguaro National Park, Chiricahua National 

Monument, and seven wilderness areas. Apache BART Alternative Proposed Rule, 79 Fed. Reg. 

at 56,328. These national parks and wilderness areas preserve the region’s most inspiring 

landscapes, rare geological formations, and diverse flora and fauna. Each of these Class I areas is 

entitled to the highest level of air quality under the Clean Air Act. See, e.g., 42 U.S.C. §§ 

7470(2), 7475(a)(5), (d)(2), 7491, 7492. 

In addition to improving visibility, the regional haze plan for Arizona will yield 

significant public health, economic, and other environmental benefits if properly implemented. 

The same pollutants that mar scenic views at national parks and wilderness areas also cause 

significant public health impacts. Nitrogen oxides (NOx) are a precursor to ground level ozone, 

which is associated with respiratory diseases, asthma attacks, and decreased lung function. In 

addition, NOx reacts with ammonia, moisture, and other compounds to form particulates that can 

cause and worsen respiratory diseases, aggravate heart disease, and lead to premature death.1

Similarly, sulfur dioxide (SO2) increases asthma symptoms, leads to increased hospital visits, 

and can form particulates that aggravate respiratory and heart diseases and cause premature 

death.2

 Particulate matter (PM) can penetrate deep into the lungs and cause a host of health 

problems, such as aggravated asthma and heart attacks.3

 The emissions reductions required by 

                                                     

1

 EPA, Health – Nitrogen Dioxide, http://www.epa.gov/air/nitrogenoxides/health.html (last visited 

Oct. 30, 2014) (Ex. 1). 

2

 EPA, Health – Sulfur Dioxide, http://www.epa.gov/air/sulfurdioxide/health.html (last visited Oct. 

30, 2014) (Ex. 1). 

3

 EPA, Health – Particulate Matter, http://www.epa.gov/air/particlepollution/health.html (last 

visited Oct. 30, 2014) (Ex. 1). 
Arizona Regional Haze – Apache BART Alternative 4

the Arizona regional haze plan will reduce the serious public health toll imposed on Arizonans 

by the state’s power plants, copper smelters, and other sources of pollution.4

 The regional haze plan for Arizona will also provide substantial economic benefits. EPA 

values the regional haze program’s health benefits nationally at $8.4 to $9.8 billion annually.5

Requiring sources to invest in modern pollution controls is a job-creating mechanism in itself, as 

each installation creates short-term construction jobs, as well as permanent operations and 

management positions.6 As EPA has explained, installing BART controls “will require well-paid, 

skilled labor which can potentially be drawn from the local area and support local growth.” 

Montana Final Rule, 77 Fed. Reg. 57,864, 57,909 (Sept. 18, 2012). Moreover, the regional haze 

program protects national parks and wilderness areas, which are of great natural and cultural 

value, in addition to serving as engines for sustainable local capital. A recent National Park 

Service study found that national parks attract nearly 300 million visitors every year, and this 

tourism supports nearly $27 billion in private-sector spending and generates $10 in economic 

activity for every federal dollar invested.7

Arizona’s renowned national parks and wilderness areas are important components of the 

state’s economy. Two of the Class I areas most impacted by Apache are Saguaro National Park 

and Chiricahua National Monument. Apache BART Alternative Proposed Rule, 77 Fed. Reg. at 

56,328. In 2012, more than 675,000 people visited these two Class I areas, and this tourism 

supported more than 550 jobs and resulted in more than $39 million in visitor spending.8

 Studies 

show that national park visitors prioritize enjoying beautiful scenery when visiting national parks 

and will visit parks less during hazy conditions.9 The haze plan for Arizona and Apache will 

                                                     

4

 Dr. George Thurston, Professor of Environmental Medicine at New York University School of 

Medicine, prepared an expert report on the significant public health benefits that would result from 

installing SCR at Navajo Generating Station (NGS) under the haze program. Dr. George D. Thurston, 

Written Report Regarding the Proposed Navajo Generating Plant EPA Rulemaking (Dec. 12, 2013) (Ex. 

2). As just one example of the haze program’s public health benefits, Dr. Thurston concluded that 

installing SCR at NGS would save between 2 to 5 lives every year, with total public health-based 

economic benefits of between $14 million and $34 million annually. Id. at 21. 

5

 EPA, Fact Sheet – Final Amendments to the RHR and BART Guidelines (Ex. 3), available at

http://www.epa.gov/visibility/fs_2005_6_15.html. 

6

 Ceres, New Jobs – Cleaner Air: Employment Effects Under Planned Changes to the EPA’s Air 

Pollution Rules 1–3 (2011) (Ex. 4), available at http://www.ceres.org/resources/reports/new-jobs-cleanerair. 

7

 Catherine C. Thomas et al., Nat’l Park Serv., 2012 National Park Visitor Spending Effects, at 

page v (2014) (Ex. 5), available at http://www.nature.nps.gov/socialscience/economics.cfm; see also

Daniel J. Stynes, Mich. State Univ., Economic Benefits to Local Communities from National Park 

Visitation and Payroll, 2010, at page v (2011) (Ex. 6), available at

http://nature.nps.gov/socialscience/docs/NPSSystemEstimates2010.pdf; Jared Hardner & Bruce 

McKenney, Hardner & Gullison, The U.S. National Park System, An Economic Asset at Risk 5 (2006) 

(Ex. 7), available at http://www.npca.org/assets/pdf/NPCA_Economic_Significance_Report.pdf. 

8

 Thomas et al., 2012 National Park Visitor Spending Effects, supra note 7, at 19, 25 (Ex. 5). 

9

 Abt Assocs. Inc., Out of Sight: The Science and Economics of Visibility Impairment, at ES-7 

(2000) (Ex. 8), available at http://www.abtassociates.com/reports/ES-clear.pdf. 
Arizona Regional Haze – Apache BART Alternative 5

noticeably improve visibility at Arizona’s national parks and wilderness areas, and thereby 

increase revenue to the parks and surrounding communities. 

The regional haze plan for Arizona will also provide important environmental benefits. In 

addition to impairing visibility, NOx, SO2, and PM pollution harms plants and animals, soil 

health, and entire ecosystems. NOx and SO2 are the primary causes of acid rain, which acidifies 

lakes and streams and can damage certain types of trees and soils. Acid rain also accelerates the 

decay of building materials and paints, including irreplaceable buildings and statues that are part 

of our nation’s cultural heritage.10 In addition, nitrogen deposition, caused by wet and dry 

deposition of nitrates derived from NOx emissions, causes well-known adverse impacts on 

ecological systems. At times, nitrogen deposition exceeds “critical loads” beyond the tolerance 

of various ecosystems.11 NOx is also a precursor to ozone, and ground-level ozone impacts 

plants and ecosystems by interfering with plants’ ability to produce food and increasing their 

susceptibility to disease and insects.12 Ozone also contributes to wildfires and bark beetle 

outbreaks in the West by depressing plant water levels and growth.13

DISCUSSION 

Apache Generating Station is a 560 megawatt facility located in Cochise, in southeast 

Arizona. Three of Apache’s seven electric generating units (EGUs) are subject to BART (Units 

1, 2, and 3). Units 2 and 3 are coal-fired EGUs, and Unit 1 primarily burns pipeline-quality 

natural gas. Apache Units 1, 2, and 3 cause a 31.66 deciview (dv) cumulative visibility impact at 

9 Class I areas.14 These substantial visibility impacts include a 7.59 dv impact at Chiricahua 

National Monument, a 5.22 dv impact at Saguaro National Park, and a 5.25 dv impact at Galiuro 

Wilderness.15 The Clean Air Task Force estimates that air pollution from Apache also causes 2 

deaths, 4 heart attacks, and 43 asthma attacks annually.16

 On December 5, 2012, EPA issued a federal haze plan for Arizona that requires Apache 

to install Selective Catalytic Reduction (SCR) pollution controls on Units 2 and 3. Arizona Phase 

1 Final Rule, 77 Fed. Reg. 72,512 (Dec. 5, 2012). EPA set a 0.07 lb/MMBtu 30-day rolling 

                                                     

10 EPA, Effects of Acid Rain, http://www.epa.gov/acidrain/effects/index.html (last visited Oct. 30, 

2014) (Ex. 9). 

11 See, e.g., William D. Bowman et al., Nitrogen critical loads for alpine vegetation and soils in 

Rocky Mountain National Park, 103 J. Envtl. Mgmt. 165, 165–70 (2012) (Ex. 10); Nat’l Park Serv., 

Nitrogen Deposition: Issues and Effects in Rocky Mountain National Park (2005) (Ex. 11), available at

http://www.nps.gov/romo/parkmgmt/upload/ROMO_N_Fact_Final.pdf. 

12 EPA, Ground-level Ozone – Ecosystem Effects, 

http://www.epa.gov/airquality/ozonepollution/ecosystem.html (last visited Oct. 30, 2014) (Ex. 9). 

13 Nathanael Massey, As Colo. firefighters gain upper hand, scientist says pollution fueled forest 

vulnerability, ClimateWire, July 2, 2012 (Ex. 12). 

14 ADEQ RH SIP at App. D, pages 49–50. 

15 Id.

16 Clean Air Task Force, Death and Disease From Power Plants, 

http://www.catf.us/fossil/problems/power_plants/ (last visited Oct. 30, 2014) (Ex. 13). 
Arizona Regional Haze – Apache BART Alternative 6

average NOx emission limit averaged across both units. Id. at 72,515. Installing SCR at Apache 

would reduce the power plant’s NOx pollution by approximately 5,000 tons per year. Id. at 

72,537–38. This substantial pollution reduction would significantly improve visibility at over 

nine Class I areas, including a 1.0 deciview (dv) or greater visibility improvement at Saguaro 

National Park, Galiuro Wilderness, and Chiricahua National Monument and Wilderness. See 

Arizona Phase 1 Proposed Rule, 77 Fed. Reg. 42,834, 42,858 (July 20, 2012). Installing SCR at 

Apache would also significantly reduce the power plant’s public health impacts on those who 

live, work, and recreate near the plant. 

 On May 29, 2013, Arizona Electric Power Cooperative (AEPCO)—which owns and 

operates Apache—submitted a BART alternative proposal to EPA. Apache BART Alternative 

Proposed Rule, 79 Fed. Reg. at 56,324. Under the proposal, rather than installing SCR, AEPCO 

would switch Unit 2 to gas and install Selective Non-Catalytic Reduction (SNCR) pollution 

controls on Unit 3. Id. at 56,324–25. SNCR controls are far less effective at reducing NOx 

pollution than SCR. Accordingly, the proposed NOx emission limit for the SNCR controls on 

Unit 3 is 0.23 lbs/MMBtu on a 30-day rolling average. Id. at 56,325. 

On June 6, 2013, EPA granted AEPCO’s petition for reconsideration of EPA’s initial 

BART determination for Apache. Id. In the current rulemaking, EPA has proposed to approve 

the Apache BART alternative and withdraw its earlier federal plan requiring Apache to install 

SCR on Units 2 and 3. 

I. The Proposed Apache BART Alternative Is Not Better Than BART. 

As discussed above, the regional haze regulations provide a two-part test to determine 

whether a BART alternative is better than BART. See supra at 2–3; 40 C.F.R. § 51.308(e)(2), 

(e)(3). The Apache BART alternative is not better than BART because it does not pass either 

prong of the two-part test. The Apache BART alternative fails the first prong of the two-part test 

because it would result in greater pollution than BART, as established in EPA’s December 2012 

BART determination for Apache. The alternative also fails the second prong of the two-part test 

because EPA has not adequately shown that the Apache BART alternative will result in greater 

visibility improvements than BART. Moreover, EPA’s modeling shows that visibility at two 

Class I areas would be worse under the alternative. Because the Apache BART alternative fails 

the two-part test, EPA cannot approve the alternative without modification. 

A. The alternative would result in more annual tons of pollution than BART. 

The first prong of the two-part test considers whether a BART alternative would result in 

greater emissions reductions than BART. 40 C.F.R. § 51.308(e)(3) (“If the distribution of 

emissions is not substantially different than under BART, and the alternative measure results in 

greater emission reductions, then the alternative measure may be deemed to achieve greater 

reasonable progress.”). It is undisputed that the Apache BART alternative would result in greater 

overall emissions than EPA’s initial BART determination. The record shows that while the 

alternative will result in fewer SO2 and PM emissions than BART, these pollution reductions are 

offset by the increase in NOx pollution. Apache BART Alternative Proposed Rule, 79 Fed. Reg. 

at 56,327. Specifically, the Apache BART alternative would result in 1,183 tons per year (tpy) 
Arizona Regional Haze – Apache BART Alternative 7

more NOx pollution, 957 tpy less SO2 pollution, and 141 tpy less PM pollution. Id. In sum, the 

Apache BART alternative would result in 85 tpy of increased overall pollution compared to 

EPA’s earlier BART determination. The Apache BART alternative thus fails to pass the first 

prong of the two-part test. As discussed below, the Conservation Organizations do not believe 

that this test should apply because of the unequal impact of NOx, SO2, and PM emissions on 

visibility. However, if this test were applied, the Conservation Organizations would encourage 

EPA to close the relatively small emissions gap between the alternative and BART by improving 

the alternative. 

There appears to be considerable confusion over whether the “distribution of emissions” 

under the Apache BART alternative and BART are different, and thus whether the first prong of 

the two-part test applies. Arizona claimed that the first prong does not apply because “a 

significant change in the distribution of emissions occurs when comparing AEPCO’s alternative 

control measure to EPA determined BART.”17 EPA implicitly accepted this view, as it did not 

discuss the first prong of the two-part test and instead applied a “modified version” of the second 

prong when evaluating Arizona’s “weight-of-evidence demonstration.” Apache BART 

Alternative Proposed Rule, 79 Fed. Reg. at 56,328. However, when evaluating similar singlesource BART alternatives elsewhere, EPA has concluded that the first prong of the two-part test 

does apply. Specifically, for Sundt Unit 4 in Tucson and the Tesoro refinery in Washington, EPA 

found that the “distribution of emissions” is the same as long as the geographic location of the 

emissions does not change significantly (i.e., when a BART alternative and BART apply to the 

same facility). See Arizona Phase 3 Proposed Rule, 79 Fed. Reg. 9318, 9334 (Feb. 18, 2014) 

(“Because the emissions reductions under EPA’s BART proposal for Sundt Unit 4 and the 

reductions from TEP’s proposed alternative would occur at the same facility, the distribution of 

emissions under BART and the alternative are not substantially different. Therefore, if the 

alternative . . . results in greater emissions reductions than our BART proposal, [it is better than 

BART].”); Washington Proposed Rule, 78 Fed. Reg. 79,344, 79,354 (Dec. 30, 2013) (“Because 

in this case, the emission sources covered by BART and the BART Alternative are within the 

same facility and the distribution of emissions is not substantially different, applying the [first 

prong of the two-part test] would meet regulatory requirements.”). 

 The Conservation Organizations urge EPA to clarify that the distribution of emissions is 

different under a single-source BART alternative—and thus the first prong of the two-part test 

does not apply—when the alternative results in greater emissions of any visibility-impairing 

pollutant. In other words, even if a BART alternative applies to the same facility as the 

underlying BART determination, the distribution of emissions is not the same if NOx, SO2, PM, 

and other visibility-impairing pollutants will be emitted in different amounts or different 

proportions. As EPA has recognized, for each source and Class I area, some pollutants will 

impact visibility differently than other pollutants. Thus, reductions in different pollutants are not 

fungible, and a ton of NOx reductions is not necessarily equivalent to a ton of SO2 reductions for 

visibility purposes. Notably, EPA has recognized this fact even when it mistakenly concluded 

that the first prong of the two-part test applies. For example, when EPA analyzed the singlesource BART alternative for Sundt Unit 4, after concluding that the alternative passed the first 

prong of the test EPA proceeded to analyze the alternative’s visibility benefits. Arizona Phase 3 

                                                     

17 ADEQ Apache BART Alternative TSD at 2 (Doc. No. B-3) (hereinafter “ADEQ TSD”). 
Arizona Regional Haze – Apache BART Alternative 8

Proposed Rule, 79 Fed. Reg. at 9335. EPA explained: “Although visibility modeling is not 

required to support a better-than-BART determination [because the alternative would result in 

less pollution], EPA conducted modeling to verify the visibility benefits of the proposed 

alternative, as compared with EPA’s BART determination.” Id. Similarly, EPA acknowledged 

that visibility modeling is “appropriate” when a single-source BART alternative results in greater 

overall pollution reductions than BART in its analysis of the Tesoro refinery. Washington 

Proposed Rule, 78 Fed. Reg. at 79,354–55. 

 In sum, regardless of whether the first prong of the two-part test applies, the Apache 

BART alternative is not better than BART with regard to total emissions because the alternative 

would result in greater annual tons of pollution than EPA’s initial BART determination. Had 

EPA used the same approach it used for similar single-source BART alternatives in Arizona and 

Washington and concluded that the first prong applies, the Apache BART alternative would not 

be better than BART. And had EPA instead properly analyzed the alternative under the second 

prong of the two-part test, the alternative is still not better than BART because EPA has not 

shown that it would result in greater visibility benefits. 

 

B. EPA has not adequately shown that the alternative would result in greater 

visibility benefits than BART. 

The second prong of the two-part test considers whether a BART alternative would result 

in greater visibility benefits than BART. 40 C.F.R. § 51.308(e)(3) (“If the distribution of 

emissions is significantly different, the State must conduct dispersion modeling to determine 

differences in visibility between BART and the trading program for each impacted Class I area, 

for the worst and best 20 percent of days.”). A BART alternative results in greater visibility 

benefits than BART if: “(i) Visibility does not decline in any Class I area, and (ii) There is an 

overall improvement in visibility, determined by comparing the average differences between 

BART and the alternative over all affected Class I areas.” Id. EPA’s modeling is flawed and the 

Apache BART alternative does not pass the second prong of the two-part test for several reasons. 

First, the modeling does not accurately reflect emissions under the Apache BART 

alternative and BART. The modeling underlying the Apache BART alternative and summarized 

in Table 5 of EPA’s proposal is based on AEPCO’s initial BART alternative proposal from May 

2013.18 However, the emissions projections under both BART and the BART alternative have 

been significantly revised since that initial proposal.19 Yet, neither Arizona nor EPA ever 

updated the modeling to reflect the changed emissions projections. As a result, the modeling 

EPA used to support its approval of the Apache BART alternative does not accurately reflect the 

                                                     

18 Compare Apache BART Alternative Proposed Rule, 79 Fed. Reg. at 56,328, with AEPCO 

Supplemental Petition for Reconsideration at 6 (May 29, 2013) (Doc. No. C-2) (EPA Table 5 and May 

2013 AEPCO petition contain same modeling results for Apache BART alternative and BART). 

19 Compare AEPCO Supplemental Petition for Reconsideration at 4–5 (AEPCO’s initial BART 

alternative proposal projected that BART would result in 2,535 tpy of SO2 emissions and the alternative 

would result in 1,247 tpy of SO2 emissions), with Apache BART Alternative Proposed Rule, 79 Fed. Reg. 

at 56,326–27 & ADEQ TSD at 13 (final BART alternative proposal projected that BART would result in 

2,013 tpy of SO2 emissions and the alternative would result in 1,056 tpy of SO2 emissions). 
Arizona Regional Haze – Apache BART Alternative 9

visibility benefits of the alternative compared to BART. EPA and the public thus do not know 

how the Apache BART alternative’s visibility benefits compare to BART. 

Second, the modeling reflects an emission rate for Unit 2 (0.225 lbs/MMBtu) that is 

lower than the permitted emission limit for the unit (0.23 lbs/MMBtu).20 As a result, EPA’s 

modeling overestimates the Apache BART alternative’s visibility benefits relative to BART. 

When the Conservation Organizations raised this issue during the State permitting process, 21

AEPCO conducted supplemental modeling reflecting the 0.23 lbs/MMBtu emission limit. The 

Conservation Organizations appreciate AEPCO’s efforts to address this concern. However, 

EPA’s actions must be based on accurate modeling assumptions—which it is not—and EPA 

would have to verify the accuracy of AEPCO’s supplemental modeling before relying on it as a 

basis for approving the Apache BART alternative. 

Third, EPA’s modeling shows that visibility at two Class I areas—the Gila and Mt. Baldy 

Wilderness Areas—will be worse under the BART alternative compared to BART. Apache 

BART Alternative Proposed Rule, 79 Fed. Reg. at 56,328. EPA should update its modeling to 

correct the flaws discussed above and confirm whether the BART alternative will in fact result in 

worse visibility improvements at these two Class I areas. If the updated modeling confirms the 

alternative will result in worse visibility at the Gila and Mt. Baldy Wilderness Areas, EPA could 

likely amend the BART alternative in the final rule to provide greater emissions reductions and 

greater visibility benefits, as discussed below. These measures may improve the BART 

alternative’s performance enough to “close the gap” at the Gila and Mt. Baldy Wilderness Areas 

and result in a BART alternative that improves visibility at every Class I area compared to 

BART. When achievable measures exist to ensure that a BART alternative will result in better 

visibility at all Class I areas—rather than at just some Class I areas—EPA should require these 

measures to ensure that the alternative truly makes greater reasonable progress. See 40 C.F.R. § 

51.308(e)(2). EPA’s failure to consider measures to improve visibility at every Class I area 

impacted by Apache is contrary to the intent of the regional haze regulations. 

Finally, EPA’s modeling is flawed because it only considered visibility impacts at Class I 

areas within 300 kilometers (km) of Apache. Apache BART Alternative Proposed Rule, 79 Fed. 

Reg. at 56,328. CALPUFF models, however, have shown that sources can cause visibility 

impairment at Class I areas located 500 km or farther from the source. See, e.g., South Dakota 

Proposed Rule, 76 Fed. Reg. 76,646, 76,654 (Dec. 8, 2011) (Big Stone I in South Dakota causes 

a 0.687 dv visibility impact at Theodore Roosevelt National Park in North Dakota, which is 

located 555 km from Big Stone I). EPA’s recent assessment of CALPUFF shows that the model 

is more accurate at farther distances than previously assumed.22 Consequently, it is appropriate to 

consider Apache’s visibility impacts at a radius of 500 km. This extended radius is necessary to 

capture Apache’s full contribution to visibility impairment. 

                                                     

20 See ADEQ TSD at 11. 

21 See Letter from Nathan Miller, Nat’l Parks Conservation Ass’n, to Trevor Baggiore, Ariz. Dep’t 

of Envtl. Quality, at 4 (Mar. 21, 2014) (Ex. 14). 

22 See EPA, Documentation of the Evaluation of CALPUFF and Other Long Range Transport 

Models Using Tracer Field Experiment Data (2012), available at 

http://www.epa.gov/ttn/scram/reports/EPA-454_R-12-003.pdf. 
Arizona Regional Haze – Apache BART Alternative 1 0

Many of the flaws in EPA’s modeling and analysis reflect the flaws in Arizona’s Apache 

BART alternative analysis, where the State incorrectly determined that the standard two-part test 

does not apply. See Apache BART Alternative Proposed Rule, 79 Fed. Reg. at 56,327–28. 

However, EPA has the final say on whether Arizona’s regional haze analysis complies with the 

law. See 42 U.S.C. § 7410(c)(1), (k)(3), (l). When EPA adopts elements of a state’s flawed 

analysis, EPA must remedy any deficiencies in the analysis to ensure full compliance with the 

Clean Air Act. See, e.g., Arizona Phase 1 Proposed Rule, 77 Fed. Reg. at 42,852–65 (replacing 

Arizona’s flawed BART analyses for Apache, Cholla, and Coronado with a federal haze plan). 

Because Arizona’s analysis for the Apache BART alternative was flawed, EPA is obligated to 

correct those deficiencies.23

II. EPA Should Improve The Apache BART Alternative In The Final Rule. 

As discussed above, the proposed Apache BART alternative is not better than BART 

because it would result in more pollution than BART and EPA has not adequately shown that it 

would improve visibility relative to BART. However, it appears that the alternative is close to 

being better than BART and it possibly could be a permissible BART alternative if it achieved 

relatively marginal additional emissions reductions. Based on EPA’s existing (but flawed) 

modeling, the alternative would improve visibility at all Class I areas if it achieved an additional 

0.025 dv improvement at the Gila Wilderness and an additional 0.003 dv improvement at Mt. 

Baldy Wilderness (based on the 98 percentile impacts). See Apache BART Alternative Proposed 

Rule, 79 Fed. Reg. at 56,328. As a result, relatively minor adjustments would likely improve the 

Apache BART alternative’s performance so that it would be better than BART. 

 The Apache BART alternative could likely be improved to achieve additional emissions 

reductions in several ways. For example, EPA could consider revising the alternative to require 

AEPCO to install SNCR at Unit 2 and switch Unit 3 to gas, rather than switching Unit 2 to gas 

and installing SNCR at Unit 3. Unit 2’s baseline NOx emissions are significantly higher than 

Unit 3’s baseline NOx emissions. See Arizona Phase 1 Proposed Rule, 77 Fed. Reg. at 42,845 

(Unit 2’s baseline emission rate is 0.47 lb/MMBtu and Unit 3’s baseline emission rate is 0.43 

lb/MMBtu). Consequently, installing SNCR at Unit 2, rather than Unit 3, would achieve greater 

NOx reductions at a given control efficiency. In its final Phase 1 rule, EPA recognized this fact 

                                                     

23 Arizona concluded that the Apache BART alternative is better than BART based on a “weight-ofevidence demonstration.” Apache BART Alternative Proposed Rule, 77 Fed. Reg. at 56,328. However, 

the “clear weight of evidence” alternative to the two-part test is generally appropriate only when a state 

cannot conduct the two-part test, or when the state has significant confidence that the BART alternative 

will have greater visibility benefits than BART. See BART Alternative Final Rule, 71 Fed. Reg. at 60,622 

(“clear weight of evidence” alternative may be warranted “when there is confidence that the difference in 

visibility impacts between BART and the alternative scenarios are expected to be large enough”); BART 

Alternative Proposed Rule, 70 Fed. Reg. at 44,158 (“clear weight of evidence” alternative may be 

appropriate when a state “is unable to perform a sufficiently robust assessment of the programs using the 

two pronged visibility test due to technical or data limitations”). Arizona’s weight of evidence approach 

was inappropriate here because the state had sufficient data to conduct the two-part test. Moreover, 

Arizona should not have used the weight of evidence test because the State could not have had confidence 

that the alternative would result in superior visibility benefits, as the alternative results in greater overall 

pollution and worse visibility at some Class I areas. 
Arizona Regional Haze – Apache BART Alternative 1 1

when it found that SNCR with a 25% control efficiency at Apache would result in a 0.19 

lb/MMBtu emission rate for Unit 2 and a 0.23 lb/MMBtu emission rate for Unit 3. See Arizona 

Phase 1 Final Rule, 77 Fed. Reg. at 72,536. As EPA’s earlier analysis shows, installing SNCR at 

Unit 2 instead of Unit 3 would significantly improve the performance of the Apache BART 

alternative. In addition, EPA could consider capacity limitations or other operational limits that 

would codify realistic operating scenarios. These improvements to the Apache BART alternative 

may well result in the alternative achieving greater pollution reductions and greater visibility 

benefits than BART, while still allowing AEPCO to install SNCR on one unit and switch the 

other unit to gas. EPA would need to demonstrate the visibility benefits resulting from these 

improvements, but it appears these options could remedy the Conservation Organizations’ 

concerns. As a result, the Conservation Organizations strongly urge EPA to assess whether an 

Apache BART alternative that installs SNCR on Unit 2 and switches Unit 3 to gas would be 

better than BART, or if capacity limits would also sufficiently improve the alternative. If so, 

AEPCO, its customers, the public, and the many iconic national parks and wilderness areas in 

Arizona and neighboring states would all benefit. In order to approve the Apache BART 

alternative, EPA must provide a definitive demonstration that the alternative passes the two-part 

BART test. If an improved alternative still would not pass this test, EPA should disapprove the 

alternative and reinstate its initial BART determination. 

CONCLUSION 

The Conservation Organizations support EPA’s efforts to reduce the large levels of air 

pollution currently emitted by the Apache Generating Station. However, EPA must ensure that 

any finalized alternative meets the threshold requirements of a BART alternative and is better 

than BART. The proposed BART alternative does not deliver the full visibility benefits at all 

impacted Class I areas in comparison to EPA’s earlier BART determination for Apache and will 

not result in greater reasonable progress. Fortunately, if EPA revises the alternative in its final 

rule, the Apache BART alternative may in fact be better than BART. EPA should thus amend the 

proposal so that it fully complies with the regional haze program. If an improved Apache BART 

alternative would still not pass the two-part better than BART test, EPA should disapprove the 

alternative and reinstate its earlier BART determination for Apache. 

A strong haze plan for Arizona that complies with the regional haze program is critically 

important to improve visibility at the many national parks and wilderness areas in Arizona and 

nearby states. Moreover, a strong regional haze plan will protect public health and benefit 

tourism and local economies by ensuring that people from around the world will continue to 

travel to Arizona to explore and enjoy the region’s many treasured landscapes. 

Sincerely, 

Michael Hiatt 

Earthjustice 

633 17th Street, Suite 1600 
Arizona Regional Haze – Apache BART Alternative 1 2

Denver, CO 80202 

(303) 996-9617 

mhiatt@earthjustice.org 

On behalf of National Parks Conservation Association and Sierra Club 

cc: Kevin Dahl, Stephanie Kodish, Nathan Miller – National Parks Conservation 

Association

 Sandy Bahr, Nellis Kennedy-Howard, Gloria Smith – Sierra Club