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    \159\ FMMI BART Report, Appendix A (BART-Eligible Baseline
Emissions Calculations), Table A-1 (BART Baseline Emissions).
    \160\ Id. note 4.
    \161\ 40 CFR part 51, appendix Y, section IV.D.4.d.2.
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    Comment: FMMI stated that EPA's reliance on cost data from the
Hayden Smelter underestimates the costs of additional controls because
the Peirce-Smith Converters used at the Hayden Smelter are
fundamentally different from the Hoboken Converters used by FMMI. FMMI
asserted that this and other differences in the operational
configuration of the two facilities means that the types of controls
available and their respective costs are not transferrable between
facilities. FMMI noted that it had prepared its own five-factor
analysis, which FMMI stated relies upon the most up-to-date cost
estimates that FMMI has received from Hatch Engineering, which designed
the smelter project including the upgraded roofline capture system and
the new aisle scrubber. FMMI asserted that this cost data presented in
the FMMI BART Report is the best and most accurate cost information
that is available to FMMI and EPA at this time and that EPA should rely
upon this cost data in any BART analyses it conducts for the Miami
Smelter.

    Response: In order to avoid potential disclosure of cost data for
the Miami Smelter claimed as CBI by FMMI, we based our cost analysis
for the construction of secondary hooding, wet scrubbers and similar,
though not identical, equipment on non-confidential data provided by
ASARCO for the Hayden Smelter. FMMI included additional non-
confidential cost information in the BART Report it submitted with its
comments. In addition, following the close of the comment period, FMMI
withdrew its CBI claim from its prior submittals, including Appendix B
to the BART Report.\162\ We have reviewed the BART Report and found
that it contains a number of incorrect or unsupported assumptions that
improperly inflate the $/ton estimates for the various control options
presented. First, it assumes capture of emissions at the roofline
rather than in the converter aisle itself. This design does not attempt
to capture or control emissions until after mixing with ambient air
inside the building, resulting in very high volumes of very low-
concentration gases that are more costly to control. Second, the cost
estimates include costs of control for non-BART units.\163\ Third, the
cost estimates are not supported by sufficient documentation, such as
vendor quotes.\164\ Finally, the cost estimates include costs not
permitted by the CCM (e.g. owner's costs).\165\ Therefore, we do not
consider the cost estimates provided in FMMI's BART Report to
accurately reflect the cost of potential BART controls.
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    \162\ Letter from Jay Spehar, FMMI, to Geoffrey Glass, EPA (May
7, 2014).
    \163\ See, e.g., BART Report page 3-15 (``Annual scrubbing
reagent costs were calculated from total estimated SO2
design reductions (i.e., inclusive of emission units that are not
BART-eligible).''
    \164\ See 70 FR 39166 ``The basis for equipment cost estimates
also should be documented, either with data supplied by an equipment
vendor (i.e., budget estimates or bids) or by a referenced source.''
    \165\ BART Report page 3-15 (``Owner's costs were likewise
factored as a percentage of the total direct plus indirect cost. A
value of 6.7 percent was applied for this analysis.'')
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    Nonetheless, in order to further evaluate the cost-effectiveness of
SO2 controls for the converters, we have conducted a
supplemental cost analysis based on the cost information provided by
FMMI. In this analysis, we have employed the cost estimates provided by
FMMI, but revised the calculations to reflect the present level of
uncaptured emissions from the converter aisle based on the mass-balance
approach described above.\166\ According to the supplemental analysis,
the cost-effectiveness of the control options evaluated by FMMI falls
in the range of $2,386 to $5,478 per ton of SO2. The upper
end of this range is higher than we have previously found reasonable
for purposes of BART. However, for the reasons described in the
preceding paragraph, this estimate significantly overstates the costs
of controlling the BART-eligible emissions. Accordingly, we do not
agree that we should employ these costs in our BART analysis.
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    \166\ Memo regarding BART Cost Using FMMI Data, June 11, 2014.
---------------------------------------------------------------------------

    Comment: FMMI asserted that neither the 99.7 percent control
efficiency nor the 99.8 percent alternative control efficiency proposed
by EPA could be feasibly measured at FMMI for three reasons. First,
differences in precision between the acid plant inlet (percent) and
tailstack (ppm) CEMS ``mean that the two CEMS cannot be compared with
an acceptable degree of accuracy . . .'' Second, ``the measurement of
acid plant inlet and tail stack gas concentrations to determine control
efficiencies contains an underlying assumption that there is a constant
amount of time that it takes gases to pass through the acid plant.''
Third, an expected 2 percent measurement drift in the acid plant inlet
CEMS exceeds the measured concentration of the tailstack CEMS
measurement span.
    Response: We disagree that it is technically infeasible to measure
the required 99.7 percent control efficiency. We recognize that the
acid plant inlet CEMS will have a much greater span than the tailstack
CEMS. However, as explained in response to similar comments on the
Hayden Smelter, because the emission limit is a percent control on a
cumulative mass basis, the measurement of the inlet CEMS can vary
appreciably without affecting compliance status.
    In addition, the compliance method in the proposed regulatory text
makes no assumptions about residence time in any control device because
it does not rely on instantaneous control efficiencies. Instead, it
compares uncontrolled and controlled total masses over a 30-day period.
Since the control efficiency data provided by FMMI were based on annual
data, however, we have modified the final determination to be a rolling
365-day average rather than a rolling 30-day average.
    Finally, in response to a request from FMMI,\167\ we have added an
additional option for measuring SO2 levels in the secondary
stream. In particular, if FMMI chooses to control the secondary stream
using an alkali scrubber, then it may calculate the pounds of
SO2 entering the scrubber based on the amount of alkali
added to the scrubber liquor, rather than installing an inlet CEMS.
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    \167\ Phone call between FMMI and EPA, May 21, 2014.
---------------------------------------------------------------------------

    Comment: FMMI requested clarification concerning EPA's proposal to
calculate control for a combination of controlled and uncontrolled
emissions. FMMI noted that EPA's calculated control efficiency of 99.69
percent excluded the bypass stack.
    Response: We calculated the acid plant's control efficiency based
on annual SO2 emissions from the acid plant tailstack and
annual production of sulfuric acid.\168\ This is a level of control
that FMMI has demonstrated achieving in practice when emissions are
ducted to the acid plant. Emissions from the bypass stack consist of
uncontrolled emissions released during startup, shutdown, and
malfunction events.\169\ Because BART emission limits apply at all
times, including periods of startup, shutdown, and malfunction, the
control efficiency requirement in the FIP includes uncontrolled
emissions from the bypass stack. FMMI reported annual average
SO2 emissions from the bypass stack of only 65 tpy in 2011
to 2012, and projected zero SO2 emissions from the bypass
stack following its planned control upgrades.\170\ Therefore, any
emissions from the bypass stack will be de minimis and will not impair
FMMI's ability to meet the 99.7 percent control efficiency requirement
on a rolling 365-day basis.
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    \168\ See appendices C and J to FMMI's Jan. 2013 letter. See
also, Memorandum from J. Nikkari, Hatch to C. West, FMMI (November
14, 2013) (Hatch Memo), section 3.4 (calculating 99.69 percent
control efficiency for existing acid plant and tail stack scrubber
system).
    \169\ Letter from Derek Cooke, FMMI, to Thomas Webb, EPA
(January 25, 2013) at 7.
    \170\ ADEQ Significant Permit Revision Application, ADEQ Class I
Permit Number 53592, Smelter Expansion & Enhanced Controls; (July
2013) (FMMI Permit Application), Tables A-2 and A-b.
---------------------------------------------------------------------------

    Comment: FMMI stated that its own five-factor analysis demonstrates
that existing controls meet BART, additional controls are not
justified, and EPA's contrary finding is based on a technically flawed
BART analysis.
    Response: We do not agree with this comment. As described above,
FMMI's five-factor analysis relies on unrealistically low estimates of
uncontrolled emissions and unrealistically high estimates of control
costs, resulting in improperly inflated $/ton estimates. Based on these
unrealistically high $/ton values, the FMMI BART Report improperly
concludes that no additional controls are cost-effective. Because of
the flaws

underlying these cost analyses, we do not agree with this conclusion.
    Comment: FMMI stated that EPA should consider FMMI's planned
pollution controls as a better-than-BART alternative. FMMI asserted
that EPA is aware that FMMI is in the process of obtaining a permit
revision to install significant new controls to ensure the smelter does
not cause or contribute to a violation of the 1-hour SO2
NAAQS. ADEQ also noted that FMMI is currently working with ADEQ to
revise its permit to accommodate a facility expansion, and is
evaluating controls necessary to comply with the 1-hour SO2
NAAQS.
    Response: EPA is willing to consider FMMI's planned pollution
controls for 1-hour SO2 NAAQS compliance as a potential
``better-than-BART'' alternative under 40 CFR 51.308(e)(2). However,
FMMI's current proposal does not meet the requirements for a better-
than-BART alternative. First, in order to qualify as a better-than-BART
alternative, FMMI's proposed alternative would have to achieve more
emissions reductions than BART.\171\ FMMI estimates that its proposed
control upgrades will result in an emission reduction of 6,054 tpy of
SO2 (future PTE minus past two-year actual).\172\ The bulk
of this reduction would come from smelter ``fugitives'' that FMMI
estimates would be reduced from 4,836 tpy of SO2 (actual
from 2011-2012) to 288 tpy (potential). However, this is inconsistent
with FMMI's BART analysis, which estimated actual baseline
SO2 emission from 2011 to 2012 as 1,033 tpy.\173\ In order
to make a better-than-BART demonstration, FMMI should use a consistent
estimate of baseline emissions, rather than using different estimates
of baseline emissions for its BART and better-than-BART analyses.
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    \171\ See 40 CFR 51.308(e)(2)(i)(E) and (3).
    \172\ ADEQ Significant Permit Revision Application, ADEQ Class I
Permit Number 53592, Smelter Expansion & Enhanced Controls; (July
2013) (FMMI Permit Application), Table A-4.
    \173\ FMMI BART Analysis Table A-1.
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    Second, FMMI's proposal would have to include a schedule for
implementation, enforceable emission limitations, and monitoring,
recordkeeping and reporting requirements.\174\ FMMI's proposal, as set
forth in its permit application and the draft permit developed by
ADEQ,\175\ does not include all of these elements. Therefore, it does
not meet the requirements for a better-than-BART alternative. If ADEQ
wishes to submit a better-than-BART alternative as a SIP revision, we
will work with FMMI and ADEQ to develop such a revision.
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    \174\ See 40 CFR 51.308(e)(2)(iii).
    \175\ ADEQ Air Quality Class I Permit  53592 (As
Amended by Significant Revision No. 58409) Freeport McMoRan Inc.
Miami Smelter (Draft, April 22, 2014).
---------------------------------------------------------------------------

    Comment: NPS supports EPA's proposed requirements to control
SO2 emissions from the Miami Smelter.
    Response: We acknowledge NPS's support.
    Comment: In response to EPA's request for comment on whether a
control efficiency more stringent than 99.7 percent is warranted,
Earthjustice asserted that a better control efficiency is achievable,
and as a result Earthjustice does not support EPA's proposed control
efficiency requirement. Earthjustice indicated that the proposed
control efficiency requirement appears to be the stated (and
unverified) level of control currently achieved at the Miami Smelter.
However, the BART Guidelines require EPA to base its analysis on the
most stringent control efficiency achievable. Noting that the proposed
level is lower than that proposed for the Hayden Smelter, Earthjustice
stated that the control efficiency of the Miami Smelter's acid plant
should be 99.93 percent or greater for the same reasons that
Earthjustice put forward for the Hayden Smelter.
    Response: We disagree with this comment for the reasons described
in response to a similar comment regarding the Hayden Smelter. In
particular, the examples of higher control efficiencies cited by the
commenter are not directly comparable to the Miami Smelter because they
are different types of operation.
3. BART Analysis and Determination for NOX
    Comment: AMA, FMMI, and NMA said that the proposed NOX
limits for the Miami Smelter exceed EPA's authority. The commenters
asserted that because NOX emissions from the BART-eligible
sources at FMMI are below the exception threshold, the RHR provides
that they may be excluded from BART analysis. The commenters indicated
that they disagree with EPA's position that ``all visibility impairing
pollutants will be subject-to-BART once a source is subject-to-BART for
any pollutant unless the pollutant in question is emitted at a level
below the exception threshold.'' NMA asserted that this was
inconsistent with EPA's prior acknowledgment that ``it is reasonable to
read [42 U.S.C 7491(b)(2)(a)] as requiring a BART determination only
for those emissions from a source which are first determined to
contribute to visibility impairment in a Class I area.'' \176\ FMMI
added that nothing in the CAA grants EPA authority to establish
emissions caps to ensure that facilities remain at or below the
exception threshold. Even if EPA's position were justified, baseline
NOX emissions from the smelter, which FMMI has submitted to
EPA, indicate that the BART-eligible equipment only emits 21.7 tpy,
which the commenters indicated is far below the BART exception
threshold of 40 tpy. For these reasons, the commenters opposed EPA's
proposal for NOX at the Miami Smelter.
---------------------------------------------------------------------------

    \176\ Regional Haze Regulations and Guidelines for Best
Available Retrofit Technology (BART) Determinations, 70 Fed. Reg.
39,104, 39,116 (July 6, 2005) (emphasis added).
---------------------------------------------------------------------------

    FMMI and NMA also stated that EPA's partial disapproval of the
Arizona RH SIP does not affirmatively demonstrate that the smelter is
subject-to-BART for NOX, and EPA's proposal to subject FMMI
to a BART analysis for NOX is legally deficient. According
to AMA, if the source has been determined to be subject to BART for a
particular pollutant, EPA has the following two options: (1) Impose
BART controls based on the outcome of the five-factor analysis or (2)
determine that a source is de minimis and exempt it from a BART
analysis. AMA said that the NOX emissions cap is arbitrary
and capricious and should not be included in the final rule.
    Response: We acknowledge that we inadvertently omitted from our
proposal a complete explanation of the basis for our proposed
determination that the Miami Smelter is subject to BART for
NOX. However, we do not consider this omission prejudicial
because, as noted by FMMI, the rationale for this proposed
determination is the same as the rationale for our disapproval of
ADEQ's determination that the Miami Smelter was not subject to BART for
NOX.\177\ FMMI commented extensively on this element of the
SIP action and included these comments as an attachment to its FIP
comments. EPA responded to these comments in the context of our SIP
action.\178\ As explained in our final action on the SIP:
---------------------------------------------------------------------------

    \177\ See 79 FR 9347 (referring to disapproval of not-subject-
to-BART finding in the Arizona RH SIP); 77 FR 75721 (proposed
disapproval of not-subject-to-BART finding in the 2011 RH SIP); 78
FR 29301 (proposed disapproval of not-subject-to-BART finding in the
RH SIP Supplement).
    \178\ See 78 FR 46156 (responses to FMMI comments regarding
proposal on 2011 RH SIP) and 46170-71 (responses to FMMI comments
regarding proposal on RH SIP Supplement).

    Once a source is determined to be subject to BART, the RHR
allows for the exemption of a specific pollutant from a BART
analysis only if the PTE for that pollutant is below a specified de
minimis level. Although a small

pollutant-specific baseline visibility impact may be informative in
determining what control option may be BART, a BART analysis is
still required for any pollutant with a PTE that exceeds the de
minimis threshold at an otherwise subject-to-BART source.\179\
---------------------------------------------------------------------------

    \179\ 78 FR 46156 (citing 40 CFR 51.308(e)(1)(ii)(C)).

    The preamble to the 2005 revisions to the RHR and BART Guidelines
cited by FMMI does not conflict with this interpretation. When EPA
revised the RHR, we proposed to interpret CAA section 169A(b)(2)(A) to
require a BART analysis for all visibility-impairing pollutants emitted
by a source, regardless of amount. However, in the final rule, we
explained that there were two reasonable interpretations of the
---------------------------------------------------------------------------
statutory text:

    Section 169A(b)(2)(A) of the Act can be read to require the
States to make a determination as to the appropriate level of BART
controls, if any, for emissions of any visibility impairing
pollutant from a source. Given the overall context of this
provision, however, and that the purpose of the BART provision is to
eliminate or reduce visibility impairment, it is reasonable to read
the statute as requiring a BART determination only for those
emissions from a source which are first determined to contribute to
visibility impairment in a Class I area.\180\
---------------------------------------------------------------------------

    \180\ 70 FR 39115-16.

    FMMI cites the emphasized language, but omits the surrounding
discussion, which explains that section 169A(b)(2)(A) could reasonably
be read either to require a BART analysis for emissions of any
visibility impairing pollutant from a source or to require an analysis
only for emissions first determined to contribute to visibility
impairment. The preamble does not state which of these two
interpretations EPA was adopting. However, in the RHR, EPA retained the
requirement that States make a BART determination for each ``BART-
eligible source in the State that emits any air pollutant'' which may
cause or contribute to any impairment of visibility in any Class I
area.\181\ The only revision made to allow for exemption of specific
pollutants from a BART analysis was the addition of the de minimis
exemption in 40 CFR 51.308(e)(ii)(C). EPA's decision to include this
particular exemption, but no other, in the regulatory text makes it
clear that individual pollutants may be exempted only where emissions
of those pollutants are below the de minimis threshold. Under the
commenters' theory that sources are subject-to-BART on a pollutant-by-
pollutant basis, a source with an impact at a Class I area was 0.4 dv
for SO2 and 0.4 dv for NOX would not be subject
to BART at all, even though it clearly contributes to visibility
impairment. EPA recognized the absurdity of this situation, and
therefore chose to use the de minimis exceptions as the only means by
which a state can avoid conducting a BART analysis for a given
pollutant after the source as a whole has been deemed subject to BART.
---------------------------------------------------------------------------

    \181\ 40 CFR 51.308(e)(ii) (emphasis added).
---------------------------------------------------------------------------

    Moreover, the de minimis threshold is not based on historical
emissions, as suggested by FMMI, but on the source's PTE.\182\ PTE is
defined as ``the maximum capacity of a stationary source to emit a
pollutant under its physical and operational design.'' \183\ Physical
or operational limitations on emissions capacity (e.g., restrictions on
hours of operation) may be taken into account, but only if those
limitations are federally enforceable.\184\ For the Miami Smelter, the
WRAP estimated an annual NOX emission rate of 156 tpy for
the units constituting the BART-eligible source.\185\ FMMI has not
identified enforceable physical or operational limitations that would
limit potential emissions from these units to less than 40 tpy. While
FMMI cites to various documents that it asserts demonstrate that the
Miami Smelter's NOX emissions are below the de minimis
threshold, these documents consist of historical records of emissions,
fuel usage, and material throughput.\186\ They do not establish the
maximum capacity of the BART-eligible source to emit NOX and
therefore do not demonstrate that potential NOX emissions
are less than 40 tpy. Likewise, the fact that EPA has estimated that
the historic baseline emissions from the BART-eligible units are 38 tpy
does not establish that potential emissions are less than 38 tpy.
Unlike subject-to-BART determinations, which are made based on a
source's PTE, emission rates for cost calculations in BART analyses are
generally ``based upon actual emissions from a baseline period.'' \187\
The PTE for the BART-eligible units at the Miami Smelters remains above
40 tpy, and the source is therefore subject-to-BART for NOX.
---------------------------------------------------------------------------

    \182\ 40 CFR 51.308(e)(1)(ii)(C).
    \183\ 40 CFR 51.301.
    \184\ Id.
    \185\ Summary of WRAP RMC BART Modeling for Arizona,
Draft5, May 25, 2007.
    \186\ FMMI Comment Letter at 13, n.1.
    \187\ BART Guidelines, 40 CFR part 51, appendix Y, section
IV.D.4.d.1.
---------------------------------------------------------------------------

    Based on our five-factor BART analysis for NOX emissions
from the Miami Smelter, we proposed to determine that no additional
controls are needed for purposes of BART. FMMI supports this
conclusion, but argues that there is no need for an emission limitation
to implement this determination. We do not agree. Regional haze
implementation plans must contain ``emission limitations representing
BART'' for all subject-to-BART sources.\188\ In particular, either the
State or EPA must establish an enforceable emission limit for each
subject emission unit at the source and for each pollutant subject to
review that is emitted from the source.\189\ This requirement applies
even where BART is determined to be consistent with existing controls.
Otherwise, emissions could increase to a level where additional
controls would be warranted for BART, but no mechanism would exist to
require such controls. Contrary to FMMI's suggestion, additional BART
controls could not be required by EPA in the next regional haze plan
for Arizona, as BART is only required in the first regional haze plan
and cannot be deferred to future planning periods.\190\ Thus, an
emission limit for NOX is needed to comply with 40 CFR
51.308(e).
---------------------------------------------------------------------------

    \188\ 40 CFR 51.308(e).
    \189\ BART Guidelines, section V.
    \190\ See 40 CFR 51.308(f) (requiring subsequent regional haze
plans to ``evaluate and reassess all of the elements required in
paragraph (d)'', i.e., RP and LTS requirements, but not BART).
---------------------------------------------------------------------------

    Comment: Earthjustice stated that EPA's NOX emissions
analyses and BART determinations are fatally deficient because the
estimate of BART-eligible NOX emissions is based on the
combustion of natural gas alone, with no consideration of the formation
of thermal NOX in the converters and the electric furnace.
    Response: We do not agree with this comment for the reasons
provided in response to similar comments regarding the Hayden Smelter.
4. Comments on Enforceable Emission Limits for PM10
    Comment: FMMI asserted that ``EPA's current reliance on the NESHAP
standards to ensure enforceability demonstrates that the Agency's
criticism of Arizona's SIP as lacking `emissions limits and compliance
requirements' was misplaced.''
    Response: We do not agree that our proposal to rely on the NESHAP
provisions to ensure the enforceability of BART for PM10 at
the Miami Smelter is inconsistent with our finding that the Arizona RH
SIP lacked enforceable emission limits to implement BART. As explained
in our actions on the Arizona RH SIP, ADEQ sought to rely on the NSPS
requirements to ensure the enforceability of its SO2 BART
determinations for both the Hayden and Miami Smelters.\191\ However,
under the

State's interpretation, as set out in the two smelters' Title V
permits, the NSPS requirements do not apply to all of the BART sources'
emissions.\192\ The permits also contain ``permit shields'' that limit
the independent enforceability of the NSPS requirements, except to the
extent that they are specifically listed in the facilities' Title V
permits.\193\ Therefore, NSPS provisions in the copper smelters'
permits do not apply to all subject-to-BART emissions at the smelters
and do not satisfy the requirements of the Act or the RHR. By contrast,
the Miami Smelter's Title V Permit does not restrict the applicability
of the NESHAP requirements to the acid plant.\194\ Nonetheless, in
order to ensure that the requisite emission limits and enforceability
requirements are included in the applicable implementation plan, we are
incorporating the applicable NESHAP requirements by reference as part
of the final FIP for the Miami Smelter.
---------------------------------------------------------------------------

    \191\ See 70 FR 46159.
    \192\ In particular, the Title V permit for the Miami Smelter
makes the 0.065 percent NSPS limit applicable to emissions from the
acid plant, but not the remainder of the facility's emissions. ADEQ
Title V Permit 53592 for Miami Smelter (2012), Attachment B section
IV.C.1.a.
    \193\ Id. section IV.C.4.
    \194\ See, e.g., id; section I.C (40 CFR Part 63 Subpart QQQ
General Requirements), VI.A (Smelter Fugitives, Particulate Matter
and Opacity).
---------------------------------------------------------------------------

5. Other Comments
    Comment: FMMI requested that EPA extend its proposed compliance
deadline for the Miami Smelter until at least 2018. FMMI noted that
``entities in many regulated industries anticipate undertaking
significant engineering and construction projects in the near term to
comply with regulations promulgated to implement new 1-hour NAAQs'' and
that ``the high volume of this work could lead to a shortage of skilled
laborers to complete the necessary construction to install pollution
control equipment.'' Accordingly, FMMI asked that EPA extend the
proposed compliance deadline to 2018. AMA also asserted that EPA should
extend the compliance deadline in the rule for the Miami Smelter.
    Response: We partially agree with this comment. Following the close
of the public comment period, FMMI submitted the construction schedule
for its planned SO2 control upgrades. The schedule indicates
that FMMI will conclude construction of the roofline capture system and
aisle scrubber by March 2017.\195\ FMMI also indicated that a shakedown
period is necessary to ensure that the capture system and scrubber can
meet the requirements of the FIP.\196\ Based on the additional
information provided by FMMI, we agree that additional time beyond the
proposed compliance deadline of three years from promulgation (i.e.,
roughly July 2017) is needed. However, because the averaging period for
the BART limit for SO2 has been increased from 30 days to
365 days, we do not agree that a full additional year is needed to
comply with the requirements of the FIP. Therefore, we are extending
the BART compliance deadline to January 1, 2018.
---------------------------------------------------------------------------

    \195\ Miami Project Execution, schedule provided to EPA by FMMI,
at a May 13, 2014 teleconference.
    \196\ Phone call between FMMI and EPA (May 28, 2014).
---------------------------------------------------------------------------

VII. Responses to Comments on EPA's Proposed Reasonable Progress
Determinations

A. Comments on Phoenix Cement Clarkdale Plant

    Comment: NPS expressed support for EPA's proposal to require
emission limits for RP equivalent to SNCR to reduce NOX at
the Clarkdale Plant.
    Response: We acknowledge NPS's support for the proposed RP
determination. The final rule contains two compliance options: a 2.12
lb/ton emission limit calculated on a rolling 30-kiln-operating-day
basis, and an 810 tpy limit calculated on a rolling 12-month basis.
Both emission limits reflect the degree of emission reduction
achievable with the installation and use of SNCR.
    Comment: Earthjustice argued that SNCR can reach higher control
efficiencies for NOX than the 50 percent control efficiency
assumed by EPA in the proposal. Earthjustice requested that EPA look
more closely at the capabilities of SNCR and the specific performance
of the control technology on other kilns, specifically those referenced
by Earthjustice. Earthjustice asserted that such an examination would
ensure that the final control efficiency selected to represent SNCR
would be consistent with the actual performance of this technology at
Kiln 4.
    Response: We partially agree with this comment. Although the
commenter notes that SNCR is capable of achieving 80 to 90 percent
control in certain site-specific instances, these results typically
represent the highest end of the range of SNCR performance. In
addition, while such levels of control are attainable on a short-term
basis, they are not necessarily consistently sustainable over longer
periods, such as on a 30-day or annual basis. We note that the reports
provided by Earthjustice assumed much lower control efficiencies (35 to
50 percent) for purposes of calculating cost-effectiveness, which is
calculated on an annual average basis. Our use of 50 percent for the
SNCR control efficiency in the BART analysis is not intended to
indicate the maximum effectiveness of SNCR. Information submitted by
the commenter, as well as information that we included in our proposed
rulemaking, does indicate that SNCR technology is capable of achieving
greater than 50 percent control efficiency at preheater/precalciner
kilns under certain conditions. It is possible that a site-specific
optimization program at Kiln 4 could identify operating parameters and
conditions that could result in an SNCR control efficiency greater than
50 percent. As noted in our proposed rulemaking, the optimization
report from the CalPortland Mohave plant indicates a range of SNCR
efficiency between 30 and 60 percent for a preheater/precalciner kiln
(the same type as Kiln 4 at the Clarkdale Plant). However, site-
specific information is not available for the Clarkdale Plant. In the
absence of information indicating the extent to which the design and
operating conditions at higher performing kilns are similar to, or
replicable at, the Clarkdale Plant, we do not consider it appropriate
to base our analysis on the higher control efficiency values. In
developing the SNCR control efficiency used in our analysis, we
examined the most stringent level of control attributed to SNCR at
other similar facilities (as a retrofit on preheater/precalciner kilns)
in other regulatory actions. These results are summarized in our
proposed rule, and indicate that a 50 percent control efficiency is the
most stringent SNCR control efficiency that has been applied to a
preheater/precalciner kiln in other actions. Accordingly, we have used
a 50 percent control efficiency as the basis for cost and emission
calculations for the Clarkdale Plant.
    However, in response to concerns raised by Earthjustice and in
order to ensure that performance of the SNCR system installed at the
Clarkdale Plant is optimized, we are including in the final rule a
series of control technology demonstration requirements.\197\ In
particular, PCC is required to prepare and submit to EPA: (1) A design
report describing the design of the ammonia injection system to be
installed as part of the SNCR system; (2) data collected during a
baseline period; (3) an optimization protocol; (4) data collected

during an optimization period; (5) an optimization report establishing
optimized operating parameters; and (6) a demonstration report
including data collected during a demonstration period. While this type
of control technology demonstration is not typically required as part
of a regional haze plan, we consider it to be appropriate here, given
the significant variability in control efficiencies achievable with
SNCR at cement kilns. Based upon the data collected, EPA may revise the
lb/ton emission limit in a future notice and comment rulemaking action.
---------------------------------------------------------------------------

    \197\ These requirements apply only if PCC chooses to comply
with 2.12 lb/ton rolling 30-kiln operating day limit for
NOX, rather than the 810 tpy 12-month rolling limit.
---------------------------------------------------------------------------

    Comment: PCC said that it supports the alternative of a cap on
NOX emissions for Kiln 4 of 810 tpy on a rolling 12-month
basis, effective December 31, 2018. However, PCC conditioned its
support on the final FIP expressly providing PCC with the option to
select either the cap or the output-based emission limit by the
deadline of December 31, 2018. Otherwise, PCC opposed a cap on
NOX emissions for Kiln 4 on the grounds that EPA is not
authorized by law to impose a mass cap in lieu of an emission limit.
PCC also requested that the FIP provide PCC with the option to switch
compliance scenarios after December 31, 2018, pursuant to either an
alternative compliance scenario provision in the FIP or a similar
provision in the facility's Title V permit. PCC stated that this
approach would best address the continuing fiscal impacts on the SRPMIC
that will result from the FIP.
    Response: As explained in an earlier response, we disagree that the
RHR precludes EPA from establishing a source-specific annual emission
cap for the purpose of achieving emission reductions to ensure
reasonable progress. In the final rule, we are including provisions for
both mass cap and an output-based emission limit, and are providing PCC
with a deadline of June 30, 2018, to decide on the emission limit with
which it will demonstrate compliance by December 31, 2018.
    Comment: PCC and ADEQ asserted that EPA's assessment of baseline
visibility impacts attributable to PCC is based on inappropriate
assumptions. In particular, PCC commented that EPA's CALPUFF modeling
is based on a NOX emission rate calculated using the maximum
rated capacity of PCC's Schenck feeder, a backup feeder that is never
used unless the primary feeder is down for repair or maintenance.
Therefore, the NOX emission rate used in the modeling is not
representative of actual or reasonably foreseeable conditions. EPA
should re-propose the FIP using a more realistic NOX
emission rate in the modeling, or else revise the model outputs
accordingly in the final FIP.
    PCC also stated that EPA's CALPUFF modeling is based on a
NOX emissions factor that was different from that used in
EPA's cost analysis. In the cost analysis, EPA used ``[a]nnual baseline
emissions . . . calculated using the average of the lb/ton
NOX emissions factors . . . observed over a 2005 to 2010
timeframe.'' For the CALPUFF modeling, EPA used the highest
NOX emissions factor (3.69 lbs/ton) that corresponds to the
year 2008. PCC asserted that EPA should re-propose the FIP to harmonize
the two approaches or revise the model outputs accordingly in the final
FIP.
    Response: We disagree that the NOX emission rate used in
the modeling is unrealistic and unrepresentative of actual or
reasonably foreseeable conditions. With regard to the emissions factors
used for calculating the costs of compliance, we have determined costs
of compliance on an annual average basis, with costs and emissions
calculated on an annualized basis (e.g., dollars/year, tons emitted/
year, tons removed/year), as recommended in the BART Guidelines.\198\
With regard to visibility modeling, while visibility improvement is not
listed in the CAA or RHR as a required factor for evaluating individual
RP sources, we consider it to be relevant and have therefore considered
it as a supplemental factor in our RP analyses. In general, we have
used the same modeling approach for RP sources as for BART sources, as
we consider this to be a reasonable means of assessing visibility
benefits from potential controls at specific sources. In particular,
since the visibility modeling examines improvement on certain days,
emission rates used in visibility modeling correspond to daily emission
rates. As described in the BART Guidelines, pre-control (baseline)
model emission rates for BART sources use the 24-hour average actual
emission rate from the highest emitting day over a specified baseline
period.\199\ For cement kilns, actual emission data are either not
recorded on a daily basis, or are not publicly available. As noted in
the TSD for the proposed rulemaking, baseline emissions for the
Clarkdale Plant were developed primarily from information contained in
annual emission inventories reported to ADEQ. Since these reports
provide only total annual emissions and annual average emissions
factors (lb/ton clinker), it is not possible to identify the highest
emitting day based on this information. As a result, the single highest
annual average emission factor (lb/ton clinker) was used in combination
with short-term production capacity (ton clinker/day) in order to
estimate a short-term emission rate (lb/day) that is representative of
the highest emitting day. As noted in the model emission spreadsheet
included in the docket for the proposed rule,\200\ the maximum 24-hour
average NOX emission rate used for the baseline is 645 lb/
hour, or about 7.75 tons/day. A summary of calculated daily
NOX emissions for the Clarkdale Plant is now included in the
docket for this final rulemaking. As seen in these emission data, there
were 12 days between 2005 and 2010 in which daily emissions were higher
than the modeled baseline emission rate, ranging from 7.77 tons/day to
11.91 tons/day. Since the Clarkdale Plant has emitted at rates greater
than those modeled in the baseline scenario, we disagree that the
baseline NOX emission rate we selected is unrepresentative
of actual or reasonably foreseeable conditions.
---------------------------------------------------------------------------

    \198\ See Guidance for Setting Reasonable Progress Goals Under
the Regional Haze Program (June 1, 2007) (``RP Guidance'') section
5.1 (recommending use of BART Guidelines and CCM for calculating
costs of compliance for stationary sources); BART Guidelines, 70 FR
at 39166-68 (Impact analysis part 1: How do I estimate the costs of
control?).
    \199\ 70 FR 39170.
    \200\ D-06c-AZRPsourcesall-
Task92012-09-30.xlsx.
---------------------------------------------------------------------------

    Regarding the use of the Schenk feeder's capacity in emission
calculations rather than the primary feeder's capacity, we note that
the primary feeder's capacity is specified as simply ``NA'' in the
Clarkdale Plant's Title V permit. Furthermore, this information was not
provided by ADEQ or PCC in their comments or any other communication
with EPA over the last 18 months.\201\ In addition, while PCC has
stated that use of the primary feeder's capacity, combined with other
revisions to emission calculations, could result in 25 percent lower
NOX emissions, it has not provided supporting data to
justify this claim, such as the primary feeder's capacity. The modeled
baseline emission rate is within the range of actual emissions reported
for the Clarkdale Plant, as noted in the previous paragraph. Thus, we
consider that 645 lb/hour is a

representative characterization of the facility's baseline emission
rate.
---------------------------------------------------------------------------

    \201\ See, e.g. Summary of Communications and Consultation
between EPA, Phoenix Cement Company (PCC), and Salt River Pima
Maricopa Indian Community (SRPMIC) Regarding Potential Reasonable
Progress (RP) Controls for Phoenix Cement Clarkdale Plant (January
27, 2014); Revision to the Regional Haze SIP for the State of
Arizona with Technical Support Document (May 3, 2013); Attachments
to the 2013 Arizona Regional Haze SIP revision (May 3, 2013).
---------------------------------------------------------------------------

    Comment: According to PCC, EPA post-processed its CALPUFF
dispersion modeling results using IMPROVE Method 8b to compute
extinction and delta deciview impacts attributable to the Clarkdale
Plant's NOX emissions. PCC said that EPA should re-propose
the FIP to solicit comments on the applicability of Method 8b for the
RHR, or propose its understanding of how best to assess source-specific
visibility impacts in a separate notice and comment rulemaking, before
it uses Method 8b in the regional haze context. In the alternative, EPA
could issue a separate notice-and-comment rulemaking to explain the
Agency's understanding of how best to assess source-specific visibility
impacts using Method 8b before EPA uses Method 8b to impose legal
obligations on the regulated community.
    Response: The details of our visibility analyses are in the TSD and
the public has had ample opportunity to comment on these analyses
through the notice and comment process on our proposal. With regard to
use of Method 8b in particular, the ``8'' in ``8b'' refers to ``method
8'' in CALPOST, a post-processor for the CALPUFF model, and indicates
that CALPOST uses the revised IMPROVE equation for calculating
visibility impact from pollutant concentrations (as opposed to ``method
6'' which specifies the original IMPROVE equation). The ``b'' refers to
natural conditions on the 20 percent best days (as opposed to ``a'' for
annual average natural conditions). As explained in our TSD, ``Method 8
is currently preferred by the [FLMs]'' and use of ``b'' (best 20
percent) is ``consistent with initial EPA recommendations for BART
[and] current [FLM] guidance for assessing visibility impacts at Class
I areas.'' \202\ The commenter has not asserted or provided any
evidence that EPA's reliance on method 8b is unreasonable or that use
of another method is preferable in this instance. Therefore, we do not
agree that any further notice and comment process is needed to evaluate
our assessment of source-specific visibility impacts.
---------------------------------------------------------------------------

    \202\ TSD at 13-14.
---------------------------------------------------------------------------

    Comment: PCC noted that CALPUFF ``is nominally for great distances
and, therefore, assumes the NO component of NOX emissions is
fully converted to NO2 that is then `available to form
visibility-degrading particulate nitrate.' '' However, PCC is ``only
10.5 km'' from Sycamore Canyon Wilderness Area (SCWA), the nearest and
most affected Class I area. PCC stated that EPA's sensitivity analysis
is arbitrary and does not appear to support EPA's proposal to impose an
SNCR-based standard on the Clarkdale Plant, given the significant
reductions in SNCR-related visibility benefits in the SCWA that would
result from lower NO-NO2 conversion rates. PCC stated that
EPA should re-propose the FIP using photochemical modeling to determine
appropriate estimates of NO-to-NO2 and NO2-to-
NO3 conversions, the nitrogen species' effects on visibility
in the SCWA, and the improvement in visibility that would result from
the use of SNCR at the Clarkdale Plant.
    Response: NO is converted to NO2 and
NO3- by oxidants such as ozone. This conversion
takes some time, since the plume from the facility does not instantly
mix into the ambient air containing oxidants. We agree with the PCC
that NO emitted by the Clarkdale Plant may not fully convert to
NO2 by the time it reaches the nearby SCWA, and therefore
may not fully form visibility-impairing nitrate
(NO3-). However, we disagree CALPUFF can only be
used to model great distances, that our sensitivity analysis is
arbitrary, or photochemical modeling is necessary in this instance. PCC
stated that CALPUFF ``is nominally for great distances.'' It is true
that we promulgated CALPUFF with distances greater than 50 km in
mind.\203\ However, we also approved it for situations with complex
wind situations, and specifically recommended CALPUFF for regional haze
analyses. EPA's Guideline on Air Quality Models states that CALPUFF
(Section A.3) may be applied when assessment is needed of reasonably
attributable haze impairment or atmospheric deposition due to one or a
small group of sources.\204\ Further, the BART Guidelines provide that
in situations where one is assessing visibility impacts for source-
receptor distances less than 50 km, one should use expert modeling
judgment in determining visibility impacts, giving consideration to
both CALPUFF and other EPA-approved methods.\205\ In this instance, we
consider CALPUFF to be the most appropriate EPA-approved method, but
have also conducted additional analyses to account for the limitations
of CALPUFF at distances less than 50 km.
---------------------------------------------------------------------------

    \203\ ``Revision to the Guideline on Air Quality Models:
Adoption of a Preferred Long Range Transport Model and Other
Revisions'', 68 FR 18440, April 15, 2003.
    \204\ 40 CFR Appendix W, Guideline on Air Quality Models section
7.2.1.e. at the time of promulgation, 68 FR 18440, April 15, 2003;
later moved to section 6.2.1.e, 70 FR 68218, November 9, 2005.
    \205\ 40 CFR part 51, appendix Y, IV.D.5. or 70 FR 39170.
---------------------------------------------------------------------------

    In particular, we acknowledge that CALPUFF's assumption that NO is
totally converted to NO2 and NO3\-\ might not be
warranted for all circumstances. NO is converted to NO2 and
NO3\-\ by oxidants such as ozone. This conversion takes some
time, since the plume from the facility does not instantly mix into the
ambient air containing oxidants. The Clarkdale Plant is only 6.5 miles
from the SCWA. We explored this issue in our proposal in the form of a
sensitivity analysis described in the TSD \206\ and an associated
spreadsheet.\207\ We scaled the nitrate portion of the visibility
impact of the Clarkdale Plant on SCWA to reflect NO-to-NO2
conversion rates ranging from 10 percent to 100 percent. We used 10
percent as an absolute lower bound because typically 10 percent of
emitted NOX (the sum of NO and NO2) is already in
the form of NO2, but we consider 25 percent a more
reasonable assumption, since there is time for some conversion during
the plume's travel to SCWA. We disagree that this analysis is
``arbitrary'' as asserted by PCC, because it covers the full range of
possible conversion rates, as shown in Table 7.
---------------------------------------------------------------------------

    \206\ TSD section IV.C.3, p.109.
    \207\ Docket spreadsheet
PhoenixCementvisNO2conv.xlsx.

 Table 7--Sycamore Canyon Visibility Benefit From SNCR on Clarkdale Cement Plant as a Function of NO Conversion
                                                       208
----------------------------------------------------------------------------------------------------------------
                                                                       NO to NO2 Conversion
                                                ----------------------------------------------------------------
                                                     10%          25%          50%          75%          100%
----------------------------------------------------------------------------------------------------------------
Base Visibility Impact (dv)....................         1.17         1.94         3.13         4.19         5.14
Visibility Impact with SNCR (dv)...............         0.92         1.42         2.07         2.68         3.30

Improvement (dv)...............................         0.25         0.52         1.06         1.51         1.85
----------------------------------------------------------------------------------------------------------------

    We also disagree that we must use photochemical modeling for this
visibility assessment. The range of NO conversion rates assumed in our
sensitivity analysis already spans whatever rate would be derived using
a photochemical model. As noted in our proposed rule, considering that
SNCR is very cost-effective in this instance, we consider a benefit of
0.25 dv at a single Class I area to be sufficient to warrant SNCR as a
control for RP. Given that SNCR is warranted for any conversion rate,
photochemical modeling would not alter our decision. Even if we were to
perform such modeling, it would be strongly dependent on the background
concentration of ozone and other oxidants in the local area for which
no ozone measurements are available. The two ozone monitors nearest to
the Clarkdale Plant are both about 28 miles away at Prescott to the
southwest and in the opposite direction at Flagstaff.\209\ One might
also use modeled ozone, derived from photochemical modeling of
NOX and VOC sources over a large area, but such an estimate
would have its own uncertainties. For example, the results may not be
sufficiently precise at the 6.5-mile scale in question to provide an
accurate ozone background. Therefore, we do not agree that
photochemical modeling is preferable to CALPUFF or required in this
instance.
---------------------------------------------------------------------------

    \208\ Id.
    \209\ See EPA's Air Quality System Database at http://www.epa.gov/ttn/airs/airsaqs/.
---------------------------------------------------------------------------

    Comment: PCC stated that EPA's conclusion that SNCR should be
considered the basis of an RHR standard for the Clarkdale Plant is
without reference to a decision-making threshold. EPA stated that ``the
benefit of SNCR remained substantial even for the lowest (NO-
NO2) conversion assumption.'' However, PCC stated that EPA
does not state or justify what visibility benefit is ``substantial''
enough to warrant imposition of RHR control technology-based standards
on a BART-ineligible source. In PCC's case, PCC stated that EPA does
not explain or justify how low the improvement in visibility would have
had to go before EPA would have decided the visibility benefits are not
``substantial'' enough to impose a standard based on SNCR. Absent this,
PCC believes EPA's decision to impose on PCC a standard based on SNCR
is arbitrary. PCC stated EPA should re-propose the FIP to provide such
explanation and justification for public comment, or provide them in
the final FIP.
    Response: We do not agree with this comment. The RHR does not
require the development of specific thresholds for any of the RP
factors. If 100 percent NO-NO2 conversion is assumed, SNCR
is expected to reduce Kiln 4's visibility impact at SCWA from 5.14 dv
to 3.30 dv, resulting in a benefit of 1.85 dv, which is quite
large.\210\ Assuming only 10 percent conversion, SNCR is expected to
reduce the Clarkdale Plant's visibility impact at SCWA from 1.17 dv to
0.92 dv, a benefit of 0.25 dv, which would still contribute to improved
visibility.\211\ Given that the four RP factors establish SNCR as a
reasonable control for the Clarkdale Plant, we consider this visibility
benefit sufficient to support installation of controls during this
planning period. Indeed, because SNCR would reduce the facility's
impact from more than 1 dv to less than 1 dv, the Clarkdale Plant would
no longer cause visibility impairment at SCWA, but would instead only
contribute to such impairment.\212\
---------------------------------------------------------------------------

    \210\ Id.
    \211\ Id.
    \212\ See 70 FR 39120 (``States should consider a 1.0 deciview
change or more from an individual source to `cause' visibility
impairment, and a change of 0.5 deciviews to `contribute' to
impairment.'').
---------------------------------------------------------------------------

    Comment: PCC asserted that EPA used the wrong cost for ammonium
hydroxide. PCC argued that the correct cost is $1,180/ton, not $1,000/
ton, based on information PCC provided to EPA on December 20, 2013. PCC
stated that EPA also used a 15 percent contingency on costs without
reference to a promulgated rule for that percentage and without
offering a reasoned justification of the use of that percentage
generally or in PCC's case. PCC concluded that EPA should re-propose
the FIP to include legally applicable inputs, explain why its inputs
are not arbitrary, or revise its cost analysis accordingly in the final
FIP. PCC added that EPA's analysis relied on EPA's CCM, which has no
legal force because it has never been subjected to a notice and comment
rulemaking. Therefore, PCC concluded that EPA should re-propose the FIP
to eliminate its reliance on the CCM in PCC's case, or else adjust its
determination for PCC in the final FIP to exclude all assumptions based
on the CCM or justify such assumptions on their merits so that they are
not arbitrary.
    Response: We disagree with these comments. EPA's RP Guidance
specifically recommends use of the CCM in evaluating the cost of
controls for potentially affected RP sources.\213\ While the CCM itself
has not been subject to notice and comment rulemaking, our use of the
CCM in this rulemaking has been subject to public notice and comment,
and PCC has had ample opportunity to dispute all assumptions in our
analysis.\214\ In this instance, PCC provided its own SNCR cost
estimate that also relied on information from the CCM for certain line
items (such as direct and indirect installation costs), as well as
internal cost estimates for other line items (SNCR purchased-equipment
cost).\215\ In our proposed rule, we accepted the majority of PCC's
cost analysis and included all of the line items provided by PCC. In
specific instances, where we found a particular line item cost to be
excessive or unjustified, we revised the value provided by PCC in order
to ensure a fair and meaningful comparison of costs between the
Clarkdale Plant and other facilities. In no case did we entirely
eliminate or disregard the cost of a line item provided by PCC.
---------------------------------------------------------------------------

    \213\ RP Guidance section 5.1.
    \214\ In addition to the public comment period on our proposed
FIP, EPA previously provided PCC with two opportunities to review
and provide feedback on our analysis for the Clarkdale Plant. See
email from Colleen McKaughan, EPA, to Verle Martz, PCC (November 6,
2012); email from Charlotte Withey to George Tsiolis (December 11,
2013).
    \215\ F-42--2013-03-06 Comments from Phoenix Cement Co.pdf.
---------------------------------------------------------------------------

    In the case of reagent cost, PCC used a reagent cost of $0.59/lb
(i.e., $1,180/ton), citing the cost-effectiveness analysis performed
for the BACT analysis of the Drake Cement Plant's PSD construction
permit in 2005. Based

on the information provided by PCC, this estimate does not appear to
have been updated or adjusted from its original 2005 estimate, nor has
PCC explained why the estimate provided for a different plant is
appropriate for the Clarkdale Plant. As noted in the proposed rule, we
used a reagent cost of $1,000/ton, based on recent historical prices
(about $500/ton) and increased it by a factor of two in order to
account for potential fluctuations in ammonia prices over the 20-year
useful life of the control equipment. Absent additional details from
PCC indicating a more recent or site-specific justification for an
ammonia cost of $1,180/ton, we consider our estimate of $1000/ton to be
a reasonable and sufficiently conservative estimate for the price of
ammonia.
    In the case of cost contingency, we consider the 40 percent
contingency suggested by PCC, without additional site-specific
information to support it, to be excessive. The CCM uses contingency
values ranging from five to 15 percent, depending upon the control
device in question and the precise nature of the factors requiring
contingency. We have used the upper end of this estimate in our cost
calculation. In no instance does the CCM provide for a generic
contingency value as high as 40 percent. We recognize, however, that
retrofit installations may pose additional cost estimate uncertainty
(i.e., cost contingency). Consequently, we have incorporated estimates
of such additional costs at other facilities affected by our regional
haze FIP actions.\216\ In these instances, however, affected facilities
provided greater detail regarding the additional costs, which we
incorporated either as additional specific line items or as larger
purchased equipment costs. We do not consider it appropriate to include
these additional retrofit costs in a generic contingency value.
Therefore, we are retaining the 15 percent contingency value.
---------------------------------------------------------------------------

    \216\ AEPCO Final Comments to AZ FIPSIPCBI
included.pdf, C-37 Letter from Erik Bakken, TEP, to Greg Nudd, EPA,
re TEP Sundt Modeling & Cost Information.
---------------------------------------------------------------------------

    Comment: PCC said that reliance on the EPA's CCM for the 20-year
useful life presumption for amortization is inappropriate because the
CCM was never subject to notice and comment rulemaking. PCC stated that
the EPA should re-propose the FIP to eliminate its reliance on the CCM
in PCC's case, or adjust its determination for PCC in the final FIP to
exclude all presumptions based on the CCM, or justify such presumptions
on their merits so that they are not arbitrary.
    Response: We do not agree with this comment. EPA's RP Guidance
recommends use of the CCM in considering the remaining useful life of
potentially affected RP sources, and explains that ``the methods for
calculating annualized costs in EPA's [CCM] require the use of a
specified time period for amortization that varies based upon the type
of control.'' \217\ The CCM, in turn, provides that ``[a]n economic
lifetime of 20 years is assumed for the SNCR system.'' \218\ As noted
in the previous response, while the CCM itself has not been subject to
notice-and-comment rulemaking, our use of the CCM in this particular
rulemaking has been subject to public notice and comment. PCC has had
ample opportunity to dispute all assumptions in our analysis, including
the 20-year amortization period. However, PCC has provided no evidence
that our use of an equipment lifetime of 20 years is inappropriate in
this instance. On the contrary, PCC submitted a four-factor analysis
dated March 28, 2013, which states that Kiln 4 has a remaining useful
life of roughly 50 years. Thus, there is no evidence in the record to
suggest that an amortization period of less than 20 years is
appropriate for capital costs of SNCR at Kiln 4.
---------------------------------------------------------------------------

    \217\ RP Guidance section 5.4.
    \218\ CCM section 4.2, chapter 1, section 1.4.2, page 1-37.
---------------------------------------------------------------------------

    Comment: Earthjustice disagreed with EPA's calculation of baseline
emissions for Kiln 4, noting that the baseline value of 1,620 tpy
employed by EPA is higher than actual annual emissions from 2005
through 2010. Earthjustice asserted that using baseline emissions that
are higher than any of the baseline years is bad policy and bad
precedent, and urged EPA to use the maximum of the actual observed
emissions from the baseline period, which is 1,513 tpy in 2005.
    Response: We disagree that the baseline emission rate should be
adjusted in the manner suggested by Earthjustice. The challenges
associated with accurately characterizing the baseline emissions for a
source that exhibited such significant variation in cement production,
annual emissions, and emission factors over the baseline period are
documented in our proposed rule. We acknowledged in our proposed rule
that our method marginally overstates the annual baseline emission
rate. However, we do not consider the method proposed by Earthjustice,
which involves using the maximum actual baseline value observed, to be
a more accurate characterization of baseline emissions. We acknowledge
that Earthjustice's method would result in a marginally lower annual
emission limit,\219\ but Earthjustice's method would also result in a
higher lb/ton NOX emission limit.\220\ We do not consider
the use of the maximum observed emission factor (lb/ton), which is the
result of low levels of kiln production, as a realistic depiction of
anticipated annual emissions from the source. Moreover, an adjustment
of the baseline by this amount would not alter our determination that
SNCR constitutes the appropriate RP control for Kiln 4.\221\
---------------------------------------------------------------------------

    \219\ As a result of using a 1,513 tpy NOX baseline
emission rate instead of 1,620 tpy as described in the proposed
rule.
    \220\ As a result of using a 3.69 lb/ton baseline emission
factor instead of a 3.25 lb/ton emission factor as described in the
proposed rule.
    \221\ Use of a 1,513 tpy baseline emission rate would result in
an SNCR cost-effectiveness of $1,215/ton, rather than $1,162/ton in
the proposed rule.
---------------------------------------------------------------------------

    Comment: PCC noted an inconsistency between the proposed compliance
date in the preamble applicable to the Clarkdale Plant, ``by December
31, 2018,'' and the compliance date in the proposed regulations, ``no
later than (three years after date of publication of the final rule in
the Federal Register).'' PCC stated that it needs the maximum
flexibility that EPA can provide, and requested that the compliance
date in the final rule be stated as ``no later than December 31,
2018.'' Similarly, ADEQ asserted that, given the difficulty of
retrofitting Kiln 4 with SNCR, more than three years is necessary to
demonstrate compliance. By contrast, Earthjustice commented that the
proposed compliance time frame of 4.5 years to install SNCR on the kiln
is too long, asserting that the proposed compliance deadline has no
basis, and should be shortened to one year.
    Response: EPA acknowledges that there is a discrepancy between the
preamble and the regulatory language in the proposed FIP regarding the
compliance date for the Clarkdale Plant. Unlike BART controls, which
must be installed as expeditiously as practicable, RP controls are not
subject to any particular compliance deadlines under the CAA and RHR,
other than the overarching requirement to achieve reasonable progress
during each planning period. PCC has indicated that it needs until
December 31, 2018, to comply with any requirements of the FIP, which is
also the end of the first planning period. While it may be technically
feasible for the Plant to install SNCR before this date, we

consider it appropriate in this instance to provide the facility until
December 31, 2018. We have amended the regulatory text to require
compliance with the NOX emission limit and other
NOX-related requirements no later than December 31, 2018.
    Comment: Earthjustice did not support revising the 30-day average
emission limit in order to accommodate startup and shutdown events at
the Clarkdale Plant. Earthjustice concluded that the proposed upward
revision is not warranted. In contrast, PCC commented that the method
EPA used to derive the 2.12 lb/ton emission limit is ``not unreasonable
for being based on empirical data.''
    Response: Under the CAA and EPA's implementing regulations,
``emission limitation'' is defined as a requirement which limits the
quantity, rate, or concentration of emissions of air pollutants ``on a
continuous basis.'' \222\ Thus, the emission limits established in the
FIP apply at all times, including periods of startup, shutdown, and
malfunction. Malfunctions are, by definition, unforeseeable, and cannot
be accounted for in setting emission limits. By contrast, startup and
shutdown are part of normal operations, and must be included when
establishing emission limits. As discussed in our proposed rule, the 30
percent upward revision from the annual emission rate to the 30-day lb/
ton limit was based on an examination of daily emissions (lbs) and
production (tons clinker) data over a multi-year period for cement
kilns (operating without SNCR) in which we identified the highest
rolling 30-day emission rate and the highest annual average emission
rate, and examined the difference between these values. A similar
approach was used to develop the rolling 30-day emission limits for TEP
Sundt Unit 4, and a copy of the emission data is included in the
docket.\223\ Unlike the emission data for Sundt Unit 4, which are
publicly available from EPA's CAMD, the data we examined for the cement
kilns contain daily production information that is considered CBI and
we are generally prohibited from making it available for public review.
The method we applied in developing the 30-day emission limit for the
cement plants, however, is the same as the method documented for Sundt
Unit 4 that is available for public review. While alternative methods
might exist to account for these emissions, we did not receive any
comments describing any alternative or more refined approaches to
address this issue. Accordingly, we are finalizing the emission limit
of 2.12 lb/ton as proposed.
---------------------------------------------------------------------------

    \222\ 42 U.S.C. 7602(k), 40 CFR 51.100(z).
    \223\ See spreadsheet labeled ``E-45--TEP Sundt4 2001-12
Emission Calcs 2014-01-24.''
---------------------------------------------------------------------------

    Comment: Earthjustice opposed setting an annual NOX
emission cap for the Clarkdale Plant's Kiln 4. According to
Earthjustice, the cap is inexplicable because there is just the single
kiln at the facility, and a cap is not needed. Earthjustice pointed out
that EPA acknowledges that the facility can meet the cap without
further controls. Earthjustice would support a combination of a unit-
specific mass-based emission limit (e.g., ton/year or ton/day) and an
output-based limit (e.g., lb/ton clinker) in some situations.
Nevertheless, Earthjustice opposed the NOX cap for Kiln 4
and urged EPA not to adopt the cap in the final rule.
    Response: We disagree with this comment. The RHR does not preclude
the establishment of an annual emission limit \224\ for the purpose of
achieving emissions reductions for reasonable progress. As proposed, an
annual NOX emission limit of 810 tpy represents a 50 percent
reduction, consistent with the use of SNCR, relative to baseline
emissions. In addition, we note that while the RHR does require the
consideration of specific control technologies and emission reduction
systems in BART and RP analyses, the emission limits established
pursuant to the RHR do not specifically require the application of a
specific control method or technology.\225\ Although the emission limit
itself is based on the reductions achievable from a considered control
option, the source is not required to install a specific technology to
demonstrate compliance with the limit, and may pursue other means of
meeting the limit. In this instance, PCC may elect to comply with the
810 tpy NOX limit by installing SNCR, or may elect to limit
cement production to about half of pre-2008 production levels.
---------------------------------------------------------------------------

    \224\ Although the term ``cap'' was used to describe the limit
on Kiln 4, the commenter is correct to note that only Kiln 4 is
subject to the ``cap.'' The ``cap'', therefore, essentially
functions as an emission limit for a single emission unit.
    \225\ We note, for example, that per 40 CFR 51.301
(Definitions), BART represents an emission limit, not necessarily a
requirement to install a specific control technology.
---------------------------------------------------------------------------

    Comment: Earthjustice noted that EPA considered two BART controls
options, SCR and SNCR, but that EPA rejected SCR as technically
infeasible. Earthjustice disagreed with this decision, and provided
information asserting that while SCR systems have proven impractical
due to operational reasons at several European kilns, that is not the
same as technical infeasibility. Earthjustice asserted that SCRs can
work in cement kilns, but require additional maintenance that may
impact the cost of the controls. However, because EPA did not do any
cost analysis, Earthjustice asserted that it is impossible to state
with certainty that SCR is not cost-effective, which Earthjustice
alleged is what is implied from EPA's discussion. Thus, Earthjustice
stated that EPA should not have conflated technical infeasibility and
economic infeasibility when it rejected SCR.
    Response: We agree that SCR is technically feasible. We clarify
that although SCR was not further considered after Step 2 (Eliminate
Technically Infeasible Options) of the RP analysis, we consider SCR a
technically feasible control option. While we explicitly eliminated
other control options (e.g., mixing air technologies) in Step 2 as
technically infeasible, we elected not to consider further SCR due to a
lack of information that would allow us to evaluate its effectiveness
and cost of controls on cement kilns. In particular, we note that SCR
has not been commercially applied to a cement plant of any type in the
United States, and there is little information available about its use
on cement kilns in other countries.\226\ Thus, we lack sufficient
information to conduct a four-factor analysis for SCR on cement kilns.
---------------------------------------------------------------------------

    \226\ See TSD at 92-93.
---------------------------------------------------------------------------

B. Comments on CalPortland Cement Rillito Plant

    Comment: CPC asserted that the four-factor analysis for the Rillito
Plant must be done within the context of the RPGs. In the current
litigation over EPA's FIP governing three subject-to-BART power plants
in Arizona, CPC noted that the petitioners argued that EPA erred by
disapproving Arizona's BART determinations without considering whether
the Arizona RH SIP demonstrated reasonable progress. According to CPC,
EPA asserted in response:

    Given that there is no statute or regulation plainly requiring
EPA to consider source-specific BART determinations in the context
of a state's overall ``reasonable progress,'' the State must
demonstrate that EPA's approach was an unreasonable interpretation
of EPA's own regulations.

    Whether EPA is correct with respect to BART determinations, CPC
asserted that 40 CFR 51.308(d)(l) and (d)(l)(A) plainly require EPA to
consider source-specific reasonable progress factors in the context of
establishing RPGs. CPC concluded that EPA should not, and cannot, take
a position in this matter

that is patently inconsistent with its position currently pending
before the Ninth Circuit Court of Appeals.
    Response: We do not agree that our action here is in any way
inconsistent with our Phase 1 action or our brief defending that
action. Furthermore, while we agree that the RHR requires consideration
of the RP factors in the context of setting RPGs, we do not agree that
our proposed FIP failed to comply with this requirement. The RPGs are
analytical benchmarks that reflect the visibility improvement at each
Class I area that is estimated to occur by the end of the planning
period on the 20 percent best and worst days after all reasonable
control measures, including both RP determinations and BART
determinations, have been implemented. In our proposed FIP, we proposed
RPGs for Arizona's Class I areas that reflect the combination of
control measures included in the approved portions of the Arizona RH
SIP (Phases 1 and 2), the partial Arizona RH FIP (Phase 1), and the
proposed partial Arizona RH FIP (Phase 3) that we are finalizing today
with some modifications.\227\ In addition, as explained elsewhere in
this notice, we are now quantifying (in deciviews) the RPGs for each
Class I area.
---------------------------------------------------------------------------

    \227\ 79 FR 9363.
---------------------------------------------------------------------------

    Comment: CPC stated that the estimated cost per dv improvement for
Kilns 1-3 in Table 43 of the proposal notice does not reflect the cost
for all three kilns. According to CPC, the Table 43 figures improperly
compare the annual cost of SNCR at one kiln with the cumulative
visibility improvement from requiring SNCR at all three kilns. CPC
asserted that, based on EPA's estimates, the corrected values would be
$4.5 million/dv (cumulative improvement) and $14.3 million/dv (maximum
improvement). CPC also stated there are several errors in the proposed
FIP's visibility modeling for Kilns 1-3.
    Response: We agree that Table 43 reflects the annual cost of SNCR
for one kiln, compared to the cumulative visibility improvement from
requiring SNCR at all three kilns. However, this error had no impact on
our proposed determination that no controls should be required for
Kilns 1-3 at this time. Making the change suggested by CPC would
further support this determination by increasing the $/dv value for
SNCR at Kilns 1-3. Likewise, making the alterations in the modeling as
suggested by CPC would not alter our determination that no controls are
reasonable for Kilns 1-3 in this planning period.
    Comment: CPC stated that the proposed FIP underestimates ammonia
costs (citing Exhibit 1 submitted with the comments). CPC stated that
its total annual cost estimate, which differs from the proposed FIP's
only due to vendor quotes and site-specific information for ammonia
costs, is $1,348,084.
    Response: As part of its comments, CPC provided an ammonia vendor
quote of $1,336/ton (compared to our ammonia cost of $1000/ton in our
proposed rule). We have revised the ammonia costs in our cost estimate
based upon the vendor quote provided by CPC. This change, together with
other revisions described below, results in a cost-effectiveness of
$1,850/ton, which we consider to be very cost-effective.
    Comment: Earthjustice and NPS indicated that they do not agree with
EPA's assessment of the control efficiency of SNCR for Kilns 1-3, which
they believe is higher than 30 percent. In Earthjustice's opinion, EPA
randomly chose a 25 percent control efficiency for SNCR without
explanation, despite the Agency's acknowledgement that the technology
is capable of reducing NOX by as much as 40 percent.
    With respect to two other control options, Mid Kiln Firing (MKF)
and Mixing Air Technology (MAT), Earthjustice noted similar concerns in
that EPA simply accepted the 20 percent reduction from CPC's observed
range of 11 to 55 percent NOX reduction, again without
support or justification. Better support must be provided, or EPA
should select a higher control efficiency for these control strategies.
    NPS agreed with EPA that it is not reasonable to require controls
at the kilns that will not operate again, but noted that it does not
agree with how EPA conducted the analysis to arrive at the decision not
to require controls, particularly with regard to control efficiency
assumptions, and emphasized that before the kilns begin operating, they
should be reevaluated.
    Response: As noted in the proposed rule, and as pointed out by the
commenters, we relied upon information provided by CPC to estimate the
control efficiencies of various control options being analyzed for
Kilns 1-3, specifically LNB, SNCR, and MKF. The information provided by
CPC indicated a range of performances for each option. However, the
site-specific information available for Kilns 1-3 was insufficient to
allow us to determine that the maximum control efficiency values within
the performance ranges were achievable at the kilns. Consequently, we
reasonably chose to use control efficiency values that fell within the
middle of the respective performance ranges. While the commenters
advocate for control efficiency values at the high end of the
performance ranges, they have provided no new site-specific information
to demonstrate that more stringent levels of control are achievable.
Finally, we note that Kilns 1-3 are long-dry kilns, whereas Kiln 4 is a
preheater/precalciner kiln. Given that more information is available
regarding the control efficiency of SNCR on preheater/precalciner
kilns, we were able to estimate a higher control efficiency for SNCR at
Kiln 4 (50 percent) than we were able to at Kilns 1-3.
    Comment: Earthjustice disagreed with EPA's decision to require no
further controls for Rillito Kilns 1-3. EPA justified its determination
based on the fact that the kilns have not operated over the last five
years, and the relatively high cost of controls. Earthjustice argued
that EPA's justification is inadequate because the kilns are not
required to be permanently removed and an enforceable commitment from
the company should be put in place if these units are to be exempt from
RP controls. By contrast, CPC agreed with EPA that controls are not
appropriate on Kilns 1-3 at this time.
    Response: As noted in our proposed rule, we do not consider it
reasonable to require RP controls on Kilns 1-3 given the relatively
high cost of the control options and the fact that these kilns last
operated in 2008, and have therefore not generated any emissions for
the last five years. With regard to an enforceable shutdown date, we do
not consider it appropriate to require the shutdown of these units. As
noted in our proposed rule, if Kilns 1-3 resume production, they should
be re-evaluated for RP controls by ADEQ during the next regional haze
planning period.
    Comment: Earthjustice disagreed with EPA's rejection of SCR as a
technically feasible control technology for Kiln 4. Earthjustice argued
that the technology can be used on kilns, but it may require additional
maintenance, which includes more frequent catalyst changes.
Earthjustice stated that this can have an effect on the cost of
controls, but because EPA did not conduct a cost analysis, the
conclusion cannot be drawn that SCR is definitely not cost-effective.
Infeasibility due to cost should not have been equated with technical
infeasibility, if that is what EPA has done.
    Response: We agree that SCR is technically feasible. As noted in
our responses regarding to comments concerning PCC's Clarkdale Plant,
we

wish to clarify that although SCR was not considered after Step 2 of
the RP analysis, we consider SCR to be a technically feasible control
option. While we explicitly eliminated other control options (such as
Mixing Air Technologies) in Step 2 as being technically infeasible, we
elected to not further consider SCR further due to a lack of
information that would allow us to evaluate its effectiveness and cost
on cement plants. In particular, we note that SCR has not been
commercially applied to a cement plant of any type in the United States
and there is little information available about its use on cement kilns
in other countries.\228\ Thus, we lack sufficient information to
conduct a four-factor analysis for SCR on cement kilns.
---------------------------------------------------------------------------

    \228\ See TSD at 92-93.
---------------------------------------------------------------------------

    Comment: Earthjustice argued that EPA has not provided adequate
support for the proposed 50 percent NOX reduction at Kiln 4
using SNCR. Earthjustice acknowledged the existence of Table IV.B-7 in
the TSD showing SNCR NOX control efficiencies from different
sources, but indicated that it could not tell based on the cited
sources in that table that the test results would limit the control
efficiency to 50 percent for Kiln 4 as well. Earthjustice indicated
that SNCR performance is site-specific and can be optimized.
Earthjustice said that the injection of ammonia or urea into an exhaust
gas stream under certain conditions can reduce NOX emissions
significantly, but that the temperature range is important because at
temperatures beyond a certain range, the reagent can oxidize to create
NO, thereby increasing NOX emissions. On the other hand, if
the temperature is below a certain temperature range, the reaction rate
is too slow for completion and the source might emit unreacted agent.
    Reemphasizing the fact that the control efficiency of SNCR is
variable and dependent on installation-specific variables, Earthjustice
argued that it is possible to achieve NOX reductions of 90
percent at cement kilns. Therefore, Earthjustice urged EPA to
reconsider the 50 percent level of control and consider raising the
control efficiency for Kiln 4 at Rillito. By contrast, NPS indicated
that it agreed with EPA's estimate of 50 percent control efficiency for
SNCR and believed this level of control is supported by estimates of 50
percent at similar kilns.
    Response: We disagree that a 50 percent control efficiency estimate
for SNCR is too low for the reasons provided in response to similar
comments regarding PCC's Clarkdale Plant. In addition, in our proposed
rule, we solicited comment regarding SNCR control efficiency on Kiln 4,
and stated that if we receive additional information or data providing
more site-specific information that justifies a different control
efficiency at the Rillito Plant, we would revise our analysis
accordingly. As noted later in our responses, CPC provided information
regarding the design and operation of Kiln 4, and stated that only a 35
percent control efficiency was achievable. As described in greater
detail below, we agree that 35 percent reflects an appropriate estimate
of the degree of control achievable with SNCR at Kiln 4, and have
revised our cost analysis to reflect a 35 percent control efficiency at
Kiln 4.
    However, in response to concerns raised by Earthjustice and in
order to ensure that performance of the SNCR system installed at Kiln 4
is optimized, we are including in the final rule a series of control
technology demonstration requirements. In particular, CPC is required
to prepare and submit to EPA: (1) A design report describing the design
of the ammonia injection system to be installed as part of the SNCR
system; (2) data collected during a baseline period; (3) an
optimization protocol; (4) data collected during an optimization
period; (5) an optimization report establishing optimized operating
parameters; and (6) a demonstration report including data collected
during a demonstration period. While this type of control technology
demonstration is not typically required as part of a regional haze
plan, we consider it to be appropriate here, given the significant
variability in control efficiencies achievable with SNCR at cement
kilns. Based upon the data collected, EPA may revise the lb/ton
emission limit in a future notice and comment rulemaking action.
    Comment: CPC stated that the proposed FIP's estimate of 50 percent
control of NOX emissions using SNCR on Kiln 4 is inaccurate
because it is based on feasibility studies at four other cement plants
and data collection from an optimization protocol at CPC's Mojave
cement plant. CPC asserted that for each of the four plants, the TSD
incorrectly characterized them in Table IV.B-9 as ``a preheater/
precalciner operating with existing combustion controls.'' According to
the commenter, the Holcim Trident and Ash Grove Montana plants are
long-wet kilns, which have fundamentally different combustion
characteristics and emission profiles.
    CPC added that, while initially estimating 30 percent control
effectiveness for SNCR at Kiln 4, it had refined its analysis and
determined that 35 percent control efficiency may be achievable, based
on the data observed at Mojave and CPC's engineering judgment that
accounts for the site-specific differences between the two kilns.
    CPC stated that a critical difference between Kiln 4 and Mojave is
that potential ammonia injection points at Kiln 4 are not within the
optimum temperature range of 1,600[emsp14][deg]F to
l,900[emsp14][deg]F. Moreover, CPC continued, because potential
injection points at Kiln 4 are below the optimum temperature range,
NOX reduction reactions will be much slower, leading to less
reduction of NOX emissions. Another critical difference,
according to CPC, is Kiln 4's unique modified loop calciner, which, due
to its design, is less efficient at mixing exhaust gases and reagent
than a cyclonic precalciner, such as the one at Mojave. CPC asserted
that the inferior mixing in Kiln 4's modified loop calciner will impede
the ability of the SNCR reactions to reduce NOX
concentrations. In addition, CPC stated that fuel combustion is less
efficient in a modified loop calciner, which leads to significantly
higher carbon monoxide (CO) and lower oxygen concentrations in Kiln 4's
exhaust when compared to Mojave. Kiln 4 CO emissions are approximately
ten times higher than at Mojave. CPC concluded that, collectively,
these factors will reduce the potential NOX control
efficiency to no more than 35 percent for Kiln 4.
    Response: In its ``Reasonable Progress Analysis for CalPortland
Company Rillito Cement Plant Kilns'' dated May 2013, CPC estimated a 30
percent NOX control efficiency, based in part on an SNCR
optimization report for CPC's Mojave Plant in California. Emission data
from this report, which CPC submitted to EPA on August 30, 2013,
indicated a range of SNCR control efficiency of 30 to 60 percent at the
Mojave Plant, depending upon operating parameters. Based on this
information, and given the range of SNCR performance indicated from the
first six months of Mojave Plant optimization protocol collection, we
stated that the use of a 50 percent control efficiency for SNCR was
appropriate for Kiln 4. We also noted that, if we received additional
information or data providing more site-specific information that
justified a different control efficiency at the Rillito Plant, we would
revise our analysis accordingly.
    As part of its comments on the proposed FIP, CPC submitted to EPA a

document entitled ``Evaluation of EPA's Reasonable Progress Analysis
for Kiln 4 at CalPortland Company's Rillito Cement Plant dated March
2014,'' which, among other things, provided further information on the
NOX control efficiency that is assumed for applying SNCR to
Kiln 4. This evaluation provided differences between Kiln 4 at the
Rillito Plant and the cement kiln at the Mojave Plant that could lead
to a lower NOX control efficiency when applying SNCR to Kiln
4.
    CPC stated that because of these differences, the SNCR
NOX control efficiencies obtained for the cement kiln at the
Mojave Plant cannot be applied to Kiln 4 at Rillito. In addition to the
differences cited above, CPC also stated in its March 2014 report that
the emission data from the Mojave Plant are highly variable (due to the
operational variability that is part of the optimization), and CPC has
not determined what control efficiency or emission rate is appropriate
to use as the basis for an emission limit for the Mojave Plant. Based
on considered engineering judgment, CPC proposed that a 35 percent
NOX control efficiency would be an appropriate estimate for
Kiln 4. Because we agree with the analysis in CPC's report, we are
revising our analysis based on a 35 percent NOX control
efficiency for SNCR at Kiln 4. In addition, as explained above, we are
including in the final rule a series of control technology
demonstration requirements to ensure that performance of the SNCR
system installed at Kiln 4 is optimized.
    In our proposed rule, we proposed a 50 percent NOX
control efficiency using SNCR, with a corresponding emission limit of
2.05 lb/ton of clinker produced and a cost-effectiveness of $1,047/ton.
A 35 percent control efficiency would result in a NOX
emission limit of 2.67 lb/ton of clinker produced and a cost-
effectiveness of $1,850/ton. We consider $1,850/ton to be very cost-
effective.
    Comment: CPC stated that EPA should revise the proposed rolling 30-
day emission limit for Kiln 4 to reflect more recent emissions data and
35 percent control efficiency for SNCR. CPC stated that the TSD for the
proposed rule references an annual design value of 2.05 lb
NOX/ton clinker based on a pre-control emission rate
estimate of 4.10 lb/ton, which omits data for 2011 and 2012. According
to CPC, a six-year average based on the 2007 to 2012 time period yields
a pre-control emission rate of 4.62 lb/ton. Over the 2009 to 2012 time
period, the annual average emission rate has been 5.15 lb/ton.
    CPC also stated that emission limits must account for changes in
production rates that are a function of market forces beyond the
company's control. CPC said that, to be achievable, any emission limit
imposed must account for the inherently higher emission rates that
occur during periods of reduced production. CPC stated that if an
emission limit is based on 50 percent control efficiency and that level
of control is not achievable, then the company will be at risk of an
enforcement action, third party claim, and/or plant shutdown for
failing to meet an unachievable standard.
    Response: As noted above, we agree that 35 percent reflects an
appropriate estimate of the degree of control achievable with SNCR at
Kiln 4. Accordingly we are revising the 30-day rolling average for the
NOX emission limit at Kiln 4 from 2.05 lb/ton of clinker to
2.67 lb/ton of clinker. In addition, as explained above, we are
including in the final rule a series of control technology
demonstration requirements to ensure that performance of the SNCR
system installed at Kiln 4 is optimized. If the data collected pursuant
to these control demonstration requirements indicate that a different
control efficiency is appropriate for this kiln, EPA may revise the lb/
ton limit in a future notice-and-comment rulemaking action.
    We do not agree that the lb/ton emission limit should be based
solely on periods of reduced production. Such an approach does not
ensure that the facility would achieve fully effective emission control
during periods of full production, which exhibit lower lb/ton values.
Conversely, a lb/ton limit based solely upon periods of full production
would result in a low lb/ton value that may not be achievable during
periods of reduced production. Although our baseline period did not
include the most recent two years of data, it did incorporate emission
data from periods of both full operation and reduced operation. As a
result, we consider it to be a reasonable representation of baseline
emissions. Therefore, we are not revising this value.
    Comment: CPC stated that because Kiln 4 does not cause or
contribute to visibility impairment, a source specific four-factor
reasonable progress analysis was not necessary or appropriate. The
commenter asserted that EPA, in its final partial approval/disapproval
of the Arizona RH SIP, stated ``We are approving Arizona's BART
threshold of 0.5 dv and its determination that West Phoenix Power Plant
and the Rillito Cement Plant are not subject to BART.'' Thus, the
commenter argued that if a facility was not required to undergo a five-
factor BART analysis, it follows that the facility should not be
required to undergo a similarly burdensome reasonable progress analysis
either.
    Response: We disagree that exemption from BART automatically
exempts a facility from control for purposes of reasonable progress
under the RHR. In this instance, EPA approved Arizona's determination
to exempt Kiln 4 at the Rillito Plant from BART, but disapproved the
State's reasonable progress analysis for point sources of
NOX. As part of our own analysis of point sources of
NOX, we identified the Rillito Plant as a potentially
affected source because it had a Q/D value of 726, more than 70 times
the threshold value of 10.\229\ Furthermore, our modeling indicates
that the plant causes visibility impairment at Saguaro National Park,
where it has a baseline impact of 1.26 dv from all four kilns.\230\
Therefore, we determined that a source-specific four-factor analysis
was appropriate.
---------------------------------------------------------------------------

    \229\ See 79 FR 9352.
    \230\ TSD page 98, table IV.B-12
---------------------------------------------------------------------------

    Comment: Earthjustice was not supportive of revising the 30-day
average emission limit in order to accommodate startup and shutdown
events. Earthjustice indicated that there is insufficient evidence in
the record documenting the analysis referenced in the TSD \231\ where
EPA indicates it looked at emission factors over 2008 to 2011 for other
preheater/precalciner kilns. Further, Earthjustice also questioned
whether the data that EPA examined was with or without SNCR. In
Earthjustice's opinion, if the data represented uncontrolled emissions,
the variability would not remain the same after the installation of
SNCR. According to Earthjustice, proper controls have the effect of
reducing variability. Therefore, Earthjustice did not believe that the
proposed 30 percent upward revision to the 30-day average was warranted
or sufficiently documented in the record.
---------------------------------------------------------------------------

    \231\ The commenter cited the last paragraph on page 99 of EPA's
TSD (EPA-R09-OR-2013-0588-0009).
---------------------------------------------------------------------------

    Response: As noted in our response to a similar comment for PCC's
Clarkdale Plant, under the CAA and EPA's implementing regulations, an
``emission limitation'' is defined as a requirement which limits the
quantity, rate, or concentration of emissions of air pollutants on a
continuous basis.\232\ Thus, the emission limits established in the FIP
apply at all times, including periods of startup, shutdown, and

malfunction. Malfunctions are, by definition, unforeseeable, and cannot
be accounted for in setting emission limitations. By contrast, startup
and shutdown are part of normal operations and emissions occurring
during startup and shutdown must be accounted for when establishing
emission limits.
---------------------------------------------------------------------------

    \232\ 42 U.S.C. 7602(k), 40 CFR 51.100(z).
---------------------------------------------------------------------------

    As discussed in our proposed rule, the 30 percent upward revision
was based upon an examination of daily emissions (lbs) and production
(tons clinker) data over a multi-year period for cement kilns
(operating without SNCR) in which we identified the highest rolling 30-
day emission rate and the highest annual average emission rate, and
examined the difference between these values. A similar approach was
used to develop the rolling 30-day emission limits for TEP Sundt Unit
4, and a copy of the emission data was included in the docket.\233\
Unlike the emission data for Sundt Unit 4, which is publicly available
from EPA's CAMD Acid Rain database, the data set we examined for the
cement kilns contains daily production data that is considered CBI,
which we are prohibited from making available for public review. The
methodology we applied in developing the 30-day emission rate for the
cement plants, however, is the same as the methodology documented for
Sundt Unit 4, which is available for public review. While there might
be alternative methods to account for these emissions than the approach
we adopted, we did not receive any comments describing any alternative
or more refined approaches for addressing this issue. Accordingly, we
have retained this methodology in establishing the emission limit in
the final rule.
---------------------------------------------------------------------------

    \233\ See spreadsheet labeled ``E-45--TEP Sundt4 2001-12
Emission Calcs 2014-01-24''.xlsx''.
---------------------------------------------------------------------------

    Comment: ADEQ said that, given the difficulty of retrofitting Kiln
4 with SNCR, more time is necessary to demonstrate compliance. ADEQ
said that the three-year compliance time frame is not sufficient. By
contrast, Earthjustice asserted that the compliance deadline should be
shortened to one year.
    Response: As noted in a response to a similar comment on PCC's
Clarkdale Plant, unlike BART controls, which must be installed as
expeditiously as practicable, RP controls are not subject to any
particular compliance deadlines under the CAA and RHR, other than the
overarching requirement to achieve reasonable progress during each
planning period. CPC has indicated that it needs until the end of the
first planning period that ends on December 31, 2018, to comply with
any requirements of the FIP. While it may be technically feasible for
the plant to install SNCR before that date, we consider it within our
discretion and reasonable in this instance to provide the facility
until December 31, 2018.
    Comment: Earthjustice responded to EPA's request for comments on
whether a NOX emission cap should be set for the Rillito
Plant. Earthjustice did not understand how EPA arrived at the proposed
cap level and argued that the level is not commensurate with actual
emissions data. The proposed level of 2,082 tpy would allow minimal to
no control of NOX at the plant, assuming that Kilns 1-3 do
not operate. Therefore, Earthjustice asserted that it is unreasonable
to propose a cap without a guarantee that the older kilns will
permanently cease operation because this could mean no control at all
for Kiln 4. Earthjustice suggested that the combination of a unit-
specific mass-based emission limit (e.g., ton/year or ton/day) and
process-based limits (e.g., lb/ton clinker) might be reasonable in some
situations, but Earthjustice indicated that it is does not support the
proposed cap.
    CPC also expressed opposition to the annual emission cap. CPC
stated that the proposed alternative NOX emissions cap would
require the permanent shutdown of Kilns 1-3, as installing SNCR on Kiln
4 would not be sufficient to meet the cap if the other kilns were
operating. CPC noted that when Kilns 1-3 operate at full capacity,
NOX emissions from them exceed 1,900 tpy, so an annual cap
of 2,082 tpy would require Kiln 4 to reduce emissions to around 150
tpy, which is more than a 90 percent reduction from current emission
levels. CPC asserted that, because 90 percent control efficiency is not
possible with SNCR, the only way it could meet this annual limit would
be to permanently shut down at least two, and perhaps all three, of its
smaller kilns.
    Response: As noted in a response to a similar comment regarding
PCC's Clarkdale Plant, the RHR does not preclude the establishment of
an annual emission cap for the purposes of achieving emission
reductions for reasonable progress. However, considering the issues
raised by commenters, and the multi-unit nature of the proposed annual
emission cap, we are not including the option of an annual emission cap
for the Rillito Plant in the final rule.
    Comment: CPC stated that the visibility modeling for Kiln 4
contains some errors and unsupported assumptions, leading to an
overestimate of the visibility benefit due to SNCR, including assuming
50 percent control and inaccurately assuming constant background
ammonia levels. CPC asserted that because modeling results are highly
sensitive to the estimated ammonia value, the assumption of 1 ppb for
winter greatly overestimates NOX effects on regional haze.
CPC stated that EPA used monthly background ammonia concentrations in
the visibility modeling for the recently adopted Wyoming RH FIP and
should do the same here given the available and representative
monitoring data from the Chiricahua monitoring station, located less
than 200 km from the Rillito Plant.
    CPC also asserted that EPA's visibility modeling for Kiln 4
contains the following errors:
    (1) The stack parameters in the worksheet labeled ``Stack
Parameters'' are the parameters for Kiln 6 that was proposed for
construction at the Rillito Cement Plant to replace Kilns I-4, but has
not been constructed.
    (2) EPA's contractor assumed a geometric mean diameter for coarse
particulate matter of 0.48 microns in its CALPUFF modeling. Because
coarse particles are larger than 2.5 microns in diameter, CPC's
technical consultant, AECOM, assumed a geometric mean diameter of 6
microns.
    (3) EPA's subcontractor used non-default minimum turbulence
velocities sigma-v (SVMIN) and sigma-w (SWMIN) for each stability class
over land and over water of 0.5 meter/second (m/s). According to
comments in the subcontractor's CALPUFF modeling files, using the
default values produced an error message. The only way to bypass the
error and run the model to completion was to set SVMIN and SWMIN to 0.5
m/s. AECOM used the default values without encountering errors from
CALPUFF.
    Finally, CPC stated that AECOM reran the visibility modeling
analysis using corrected and supportable inputs, demonstrating that the
maximum visibility benefit from installing SNCR on Kiln 4 would be 0.15
dv, approximately seven times less than the human eye can detect.
Citing the DC Circuit's decision in American Corn Growers, CPC stated
that a source should not be required to spend millions of dollars for
imperceptible visibility improvements.
    Response: We partially agree with this comment. As explained above,
we agree with CPC's assertion that a control efficiency of 35 percent
is more appropriate for SNCR at Kiln 4 than our proposed efficiency of
50 percent. However, we do not agree that our use of the IQAQM default
for background

ammonia of 1.0 ppb was improper. As explained in our response to
comments from TEP on the BART determination for Sundt Unit 4, given the
uncertainty and variability in ammonia values measured in Arizona, we
consider the 1.0 ppb IWAQM default to be the most appropriate value to
use here.\234\
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    \234\ Memorandum in docket, ``Full Technical Response to
Modeling Comments for June 2014 Final Arizona Regional Haze FIP
(Phase III),'' Colleen McKaughan and Scott Bohning, EPA, June 16,
2014.
---------------------------------------------------------------------------

    We agree that we used the incorrect stack parameters. However,
because these parameters have varying impacts on visibility benefits,
this error had little effect overall. In particular, the lower stack
height and smaller stack diameter tend to increase baseline visibility
impacts and the visibility improvements due to controls, whereas the
higher stack exit velocity and higher exit temperature tend to decrease
visibility impacts and control benefits.
    Similarly, the changes related to particle diameters have little
effect on the modeling results because PM contributes only a few
percent to the modeled visibility impacts. The changes related to
default minimum turbulence velocities would tend to increase slightly
atmospheric mixing and thus to reduce slightly pollution impacts and
the benefit of controls. Overall, the effect of the changes to the
modeling input parameter is much smaller than the change in SNCR
control efficiency, and does not affect our control determination.
    While CPC's comment cites the results of AECOM's modeling using
variable ammonia background, AECOM also conducted modeling using
constant 1.0 ppb ammonia background. As explained above, we consider
use of constant 1.0 ppb ammonia background to be the most appropriate
approach and we agree with CPC's other corrections to our contractor's
modeling. Therefore, we accept the results of CPC's modeling using 1.0
ppb ammonia background as a generally reasonable estimate of visibility
benefits expected from SNCR on Kiln 4. These results indicate that the
benefit of SNCR at Kiln 4 would be somewhat less than EPA's modeling
showed. In particular, EPA's modeling showed a benefit of 0.24 dv at
Saguaro National Park, the area with the highest impact from Kiln 4,
and a cumulative benefit over the 12 nearby Class I areas of 0.78 dv.
By contrast, CPC's modeling showed a benefit of 0.18 dv at Saguaro
National Park and a cumulative improvement of 0.59 dv.
    Despite these decreased visibility benefits, EPA still considers
SNCR to be reasonable for Kiln 4 for several reasons. First, as
explained above, even with the revisions suggested by CPC in its
comments, SNCR remains highly cost-effective at $1,850/ton. Second,
even though the visibility benefits from SNCR at Kiln 4 at the Rillito
Plant are lower than those expected to result from controls on other
sources addressed in this FIP, they are not negligible, and together
with controls on other sources now and in the future will achieve
progress in improving visibility at multiple Class I areas. In
particular, we note that, according to CPC's modeling, 12 different
Class I areas will be improved, including Galiuro WA, for which the
expected improvement is 0.16 dv, only slightly less than expected
improvement of 0.18 dv at Saguaro National Park. Third, due to the
close proximity of the Rillito Plant to the western unit of Saguaro
National Park, there is significant uncertainty regarding the benefits
of controls. In particular, EPA's modeling indicated that the benefit
of SNCR at the western unit of Saguaro National Park (0.30 dv) is
greater than the benefit at the eastern unit (0.24 dv), if 100 percent
conversion of NO to NO2 is assumed. EPA also conducted a
sensitivity analysis to address the possibility that NOX
emitted from the Rillito Plant is not 100 percent in the form of
NO2. The results of this analysis are shown in Table 8.

     Table 8--Visibility Benefit at Western Saguaro NP From SNCR on Rillito Cement Plant as a Function of NO
                                                   Conversion
----------------------------------------------------------------------------------------------------------------
                                                                       Conversion Rate
            NO to NO2 Conversion            --------------------------------------------------------------------
                                                  10%           25%           50%           75%          100%
----------------------------------------------------------------------------------------------------------------
Improvement (deciviews)....................         0.03          0.05          0.15          0.22          0.30
----------------------------------------------------------------------------------------------------------------

While we do not know for certain which of these scenarios is most
realistic, it is worth noting that there also will be some benefit to
the western unit of Saguaro, which is not directly reflected in the
modeling provided by CPC.
    Finally, we disagree with CPC's suggestion that human
perceptibility of visibility improvement is a criterion for imposing
controls for purposes of selecting source-specific controls for
reasonable progress under the CAA and the RHR. No one control will be
sufficient to achieve the visibility goals of the RHR. The effect of
reasonable controls on the many contributing sources will cumulatively
enable progress toward those goals.
    Comment: CPC asserted that the reasonable progress analysis for
Kiln 4 is inconsistent with EPA's analyses of other sources. CPC
included a table comparing the proposed FIP's cost and visibility
results for TEP Sundt Units 1-3 and CPC Rillito's Kiln 4, and concluded
that for about the same annual cost, emission controls at Sundt would
have a much greater beneficial impact on visibility at Saguaro National
Park. CPC stated that the only factor that could explain this
differential treatment is the ``cost/ton reduced'' metric, which the
FIP estimates is higher for TEP Sundt than Rillito, thus demonstrating
the limitations of the cost/ton reduced metric. CPC further stated that
the FIP should not rely on this metric, which provides no insight on
whether controls are cost-effective for achieving RPGs by improving
visibility, the sole potential justification for establishing controls.
With respect to TEP Sundt Units 1-3, CPC stated that EPA concluded
``the cost-effectiveness of ULNB is relatively high in light of the
anticipated visibility benefit'' and argued that because the costs are
similar and the visibility benefits are even smaller, the same
conclusion must be reached for Kiln 4.
    Concerning the reasonable progress analysis for El Paso's
facilities and Pima County's Ina Road sewage plant, CPC included a
table comparing the four-factor analyses for those facilities and Kiln
4. CPC asserted that there is no explanation or justification to
support the proposed decision to require controls on Kiln 4, but not on
these other sources. CPC noted that the cost of compliance is higher
for Kiln 4 than the other sources, the time needed to comply is longer,
energy and non-air quality impacts are equivalent, and the remaining
useful life is assumed to be identical. CPC asserted that because the
four factors set forth in 40 CFR

51.308(d)(l) cannot justify this differential treatment, the proposed
FIP justifies the decision to not require controls on these other
sources based on a factor that is not listed in 40 CFR 51.308(d)(l),
and stated that CPC should, and must, be treated equally, and no
controls should be imposed during this first planning period.
    Response: We do not agree with this comment. The CAA and RHR
provide considerable discretion in how the four RP factors are weighed.
Moreover, while the CAA and RHR explicitly require consideration of
visibility improvement in BART analyses, they do not require
consideration of such benefits for individual RP sources. Therefore,
while we have taken visibility benefits into account as a supplementary
factor, we have not weighed them as heavily for RP as we have for BART.
Rather, we have placed more emphasis on cost, which is one of the
enumerated statutory factors for RP analyses.\235\ Accordingly, we do
not agree with CPC's suggestion that we should consider $/dv as more
important than $/ton in evaluating potential RP controls. Even with
CPC's suggested modifications, the cost-effectiveness of SNCR at Kiln 4
($1,850/ton) is two to four times less than the cost-effectiveness of
controls at Sundt Units 1-3 ($4,400-$8,300/ton).\236\ Accordingly, we
do not agree that we are treating these units inconsistently.
---------------------------------------------------------------------------

    \235\ Our cost analyses also incorporate consideration of two
other statutory factors: Remaining useful life and energy and non-
air environmental impacts.
    \236\ See 79 FR 9358.
---------------------------------------------------------------------------

    With regard to El Paso's Compressor Station and Pima County's Ina
Road sewage plant, we agree with the commenter that controls on these
units would be more cost-effective than SNCR at Kiln 4, and that the
results for the other three statutory factors are similar. However, we
note that El Paso Natural Gas Company (EPNG) has asserted that EPA has
underestimated the costs of compliance and time necessary for
compliance.\237\ Furthermore, as explained in our proposal, natural-gas
engines similar to those at these facilities are dispersed throughout
the State and it is not practical for EPA to control these sources. By
contrast, the Rillito Plant is a single discrete facility for which
SNCR is a cost-effective and otherwise reasonable control option. We
also note that, while we do not have visibility modeling to gauge the
impacts of the other facilities cited by CPC, the Q/D value for the
Rillito Plant (a rough gauge of potential for visibility impairment) is
more than ten times the Q/D value for any of the other sources. Under
these circumstances, we consider it reasonable to require SNCR at the
Rillito Plant and not to require additional controls at the compressor
stations or the sewage treatment plant. We strongly encourage the State
to consider development of a statewide rule to regulate natural-gas
engines in the next planning period.
---------------------------------------------------------------------------

    \237\ EPNG Comment Letter at 1-2.
---------------------------------------------------------------------------

    Comment: Arizona Rock Products Association expressed support for
and incorporated by reference the comments of CPC and PCC.
    Response: We have responded to CPC's and PCC's comments above.

C. Comments on Other Reasonable Progress NOX Point Sources

    Comment: NPS argued that SCR should be BART for APS Cholla Unit 1.
NPS provided more details on the cost analysis for Cholla Unit 1,
indicating that the calculated average and incremental cost-
effectiveness values for SCR of $5,313/ton and $6,307/ton,
respectively, are erroneously high. NPS noted that EPA's calculation
methodology relied heavily upon IPM, and suggested several revisions
and corrections to EPA's calculation that would have the effect of
reducing the control costs. After applying the corrections, NPS
concluded that an average cost-effectiveness of $5,263/ton is obtained
which NPS considers to be reasonable. In addition, NPS provided its own
set of cost calculations, relying primarily upon the cost equations
contained in EPA's CCM. NPS estimated that the average cost-
effectiveness of SCR is $4,353/ton, which is less than the values
established by several states and EPA.
    NPS also made similar comments about TEP Springerville Units 1 and
2. NPS asserted that EPA's estimates of SCR cost-effectiveness of
$6,829/ton for Unit 1 and $6,085/ton for Unit 2 are erroneously high,
and therefore the incremental cost-effectiveness of SCR over SNCR of
$8,606/ton and $7,416/ton, respectively, are also too high. After
applying the corrections discussed by NPS, average cost-effectiveness
of $5,700 to $6,400/ton is obtained, which NPS considers to be
reasonable. In addition, NPS provided its own cost calculations for
Springerville Units 1 and 2, relying primarily upon the cost equations
contained in EPA's CCM. NPS estimated that the average cost-
effectiveness of SCR is $5,688 to $6,377/ton, which is less than the
values established by several states and EPA for EGUs. Detailed
calculations and analysis for Cholla Unit 1 and Springerville Units 1
and 2 are documented in Appendix C and E of NPS's submittal.
    Response: We disagree with NPS's assertion that our calculations,
based on IPM methodology, are overestimates. The revisions indicated by
NPS consist primarily of lower urea/ammonia and catalyst costs. NPS
made similar assertions regarding ammonia and catalyst costs in our
analysis for TEP Sundt Unit 4. As described in our responses to those
comments, we consider the values we used for ammonia and catalyst costs
appropriate.
    Regarding NPS's cost calculations that use the cost equations from
the CCM (as opposed to using the information contained in IPM), we note
that nothing in the RHR requires use of the CCM for calculating the
cost of compliance for RP sources. Moreover, while EPA's RP Guidance
recommends use of the CCM, it also allows for divergence from the CCM,
provided that any difference from the CCM is documented.\238\ In this
and other RH rulemakings, we have not required strict adherence to the
study level cost equations contained in the CCM, and have developed
cost calculations based on a number of supplemental sources including
certain site-specific data provided by the facility, vendor quotes, and
information from other EPA rulemakings. As noted in our proposed rule
and TSD,\239\ IPM has been used by EPA in multiple regulatory actions,
and we consider it an appropriate source of supplemental information.
---------------------------------------------------------------------------

    \238\ See RP Guidance, section 5.1, note 23.
    \239\ TSD for the Proposed Phase 3 FIP, January 27, 2013, Page
19 of 233.
---------------------------------------------------------------------------

    Regarding the use of cost-effectiveness thresholds, we note that
the examples cited by NPS consist of BART determinations and not RP
determinations.\240\ Given the differences between the BART factors and
RP factors and the nature of the applicability criteria that would
trigger BART and RP analyses,\241\ we do not necessarily consider the
cost-effectiveness and visibility benefit values from BART
determinations to be directly comparable to RP analyses. Furthermore,
the cost-effectiveness values that NPS finds reasonable are, in fact,
higher than EPA has required for

any BART source during this planning period.\242\ While it may be
necessary to require controls at this cost level for RP sources in
future planning periods, we do not agree that this level of cost-
effectiveness is reasonable at this time, given the significant
emission reductions already achieved by BART and RP determinations
during this planning period (see Table 12).
---------------------------------------------------------------------------

    \240\ We also note that while NPS refers to ``BART for Cholla
Unit 1'', Cholla Unit 1 is, in fact, not BART-eligible and therefore
not subject to BART. See 78 FR 46145.
    \241\ I.e., BART has very specific applicability criteria, and
is a ``one-time'' analysis that is only performed on affected
sources during the first planning period. The procedure for
identifying candidate sources for RP controls is not as specific,
may have more or less expansive criteria than BART, and can be
potentially performed each planning period.
    \242\ See, e.g. BART EGU FIP Summary.
---------------------------------------------------------------------------

    Comment: ADEQ expressed support for EPA's determination that it is
not practical to control compressor stations due to their dispersed
locations. Similarly, the owner of Williams and Flagstaff Compressor
Stations (EPNG) said that it agreed with EPA's determination that it is
not reasonable to require further controls at these two facilities.
Even though EPNG supported EPA's decision, EPNG did not agree that the
control technology, cost of compliance, and time to comply used by EPA
in its analysis are appropriate.
    Response: We acknowledge ADEQ's and EPNG's support on this issue.
We note that our finding of impracticability with regard to the
regulation of engines (including those found at compressor stations)
only applies to regulation by EPA in this planning period. It does not
apply to potential regulation by the State in future planning periods.
Given the availability of cost-effective controls for these sources and
the potential for significant emission reductions from a statewide rule
applicable to such sources, we strongly encourage ADEQ to develop such
a rule during the next planning period. We acknowledge the comments
made by EPNG regarding our control technology analyses for the natural
gas turbines, but have not revised our analysis at this time because it
would not alter our determination not to control compressor stations at
this time.
    Comment: TEP, the owner of the Sundt and Springerville facilities,
agreed with EPA's conclusion that additional controls are not required
on Springerville Units 1 and 2 or Sundt Units 1-3 at this time. ADEQ
similarly expressed support for the EPA's decision not to require low-
NOX burners for Sundt Units 1-3 because they are not cost-
effective. TEP added that the same result would have been achieved if
EPA had approved ADEQ's identical determination.
    Response: We acknowledge TEP's support on this issue. We agree
that, with regard to TEP Sundt Unit 1-3, our determinations are
identical to those made by ADEQ. However, we note that, unlike ADEQ,
EPA conducted a four-factor RP analysis for these units, as well as
visibility modeling to evaluate potential visibility benefits, before
concluding that no additional controls are reasonable at this time.
    Comment: The owner of Tucson Compressor Station (EPNG) indicated
that that the facility is no longer operating and should therefore be
removed from the FIP.
    Response: We appreciate the clarification. Our proposed FIP did not
require any controls for this facility, so no revisions are needed.

D. Comments on Area Sources of NOX and SO2

    Comment: Earthjustice argued that area sources should also be
required to install reasonable progress controls. Earthjustice referred
to an NPCA Report \243\ that shows how Visibility Restoration Plans can
help ensure that Class I areas achieve the glide path by 2064. The
report indicated that Arizona's area sources are the largest
contributors to visibility impairment at the Grand Canyon. Earthjustice
noted that EPA looked at reasonable progress controls for area sources,
but classified its analysis as ``limited in scope.'' Earthjustice
explained that EPA identified the area source categories contributing
the most to visibility impairment, but performed only a brief analysis
because the inventories that were analyzed did not contain sufficient
data (e.g., on the number, age, and design of the actual area sources).
In Earthjustice's opinion, in order to conduct a thorough reasonable
progress analysis in this case where there was limited information
available, EPA should have obtained the data necessary to conduct a
proper analysis. Further, Earthjustice said that the justification for
no further controls based on no other regional haze SIP or FIP
requiring controls on such sources primarily to ensure reasonable
progress is not sufficient, because no other state had RPGs as poor as
Arizona's.
---------------------------------------------------------------------------

    \243\ National Parks Conservation Association, On an Approach
for Improving Visibility in Class I Areas Using Visibility
Restoration Plans (VRPs) with an Example VRP for the Grand Canyon
National Park (2014). Exhibit 17 in Earthjustice's comments.
Hereafter ``NPCA Report''.
---------------------------------------------------------------------------

    Earthjustice highlighted the Visibility Restoration Plan that was
submitted with the Earthjustice's public comments as a tool to help EPA
in identifying other sources that impact visibility, and should be
evaluated for reasonable progress controls. According to Earthjustice,
the Visibility Restoration Plan could also be a helpful tool to the
Agency by illustrating how a long-term strategy based on existing data
can be developed to restore visibility by 2064. In Earthjustice's
opinion, if the plan is adopted, this would assist states and EPA to
implement the goals of the haze program's reasonable progress mandate.
    Response: We do not agree that additional area source controls are
reasonable for this planning period. According to our analysis,
Arizona's area sources are typically the smallest contributor to
anthropogenic nitrate and sulfate pollution at Arizona's Class I areas,
including the Grand Canyon, where Arizona area sources contribute only
2.9 percent of the nitrate pollution and only 0.4 percent of the
sulfate pollution.\244\ EPA's analysis is based on source apportionment
modeling conducted by the WRAP. As we note in the proposal, EPA has
carefully evaluated that work and has determined it to be of sufficient
quality to use in making policy decisions.
---------------------------------------------------------------------------

    \244\ See 79 FR 9362, Tables 53 and 54.
---------------------------------------------------------------------------

    The NPCA Report suggests that the contribution of Arizona's area
sources to haze at the Grand Canyon may be greater than indicated by
our analysis. However, as acknowledged in the NPCA Report's Visibility