federally enforceable. Therefore, instead of completing the remaining
steps of a five-factor BART analysis, we have evaluated the appropriate
level of emissions to ensure that the fabric filter achieves an
appropriate degree of control.
c. Proposed BART Determination for PM10
    EPA is proposing a filterable PM10 BART emission limit
of 0.03 lb/MMBtu based on the use of the existing fabric filter
baghouse currently in operation, which is the most stringent control
for particulate matter. We note that Mercury and Air Toxics (MATS) Rule
establishes an emission standard of 0.03 lb/MMBtu filterable PM (as a
surrogate for toxic non-mercury metals) as representing Maximum
Achievable Control Technology (MACT) for coal-fired EGUs.\67\ This
standard derives from the average emission limitation achieved by the
best performing 12 percent of existing coal-fired EGUs, as based upon
test data used in developing the MATS Rule.\68\ The BART Guidelines
provide that, ``unless there are new technologies subsequent to the
MACT standards which would lead to cost-effective increases in the
level of control, you may rely on the MACT standards for purposes of
BART.'' \69\ Therefore, we propose to find that 0.03 lb/MMBtu
filterable PM10 is an appropriate limit for BART at Sundt
Unit 4.
---------------------------------------------------------------------------

    \67\ 77 FR 9304, 9450, 9458 (February 16, 2012) (codified at 40
CFR 60.42Da(a), 60.50Da(b)(1)).
    \68\ See Memorandum from Jeffrey Cole (RTI International) to
Bill Maxwell (EPA) regarding ``National Emission Standards for
Hazardous Air Pollutants (NESHAP) Maximum Achievable Control
Technology (MACT) Floor Analysis for Coal- and Oil-fired Electric
Utility Steam Generating Units for Final Rule'' (December 16, 2011).
    \69\ 40 CFR Part 51, Appendix Y, Section IV.C.
---------------------------------------------------------------------------

4. Better Than BART Alternative
    We are proposing a switch to natural gas on Sundt Unit 4 as a
better-than-BART alternative to the emissions controls previously
proposed in this section for a coal-fired unit. Unit 4 was originally
constructed as a natural gas-fired boiler, and has used natural gas as
a primary fuel for significant periods of time since 2009. While a
change in fuel supply to natural gas instead of coal is an inherently
less polluting option, the BART Guidelines do not require the
consideration of fuel supply changes as a control option.\70\ As a
result, the option of burning only natural gas is not considered in our
BART analysis. However, TEP has submitted to EPA an alternative to BART
based on the elimination of coal as a fuel source for Sundt Unit 4 by
December 31, 2017. As part of this submittal, TEP compared the
potential emission reductions and visibility benefit between a natural
gas fuel change and certain combinations of NOX and
SO2 controls.\71\
---------------------------------------------------------------------------

    \70\ 40 CFR Part 51, Appendix Y, Section IV.D.1.5, ``STEP 1: How
do I identify all available retrofit emission control techniques?''
    \71\ Letter dated November 1, 2013.
---------------------------------------------------------------------------

    EPA has evaluated this alternative proposal pursuant to the
``better-than-BART'' provisions of the RHR. In particular, the RHR
allows for implementation of ``an emissions trading program or other
alternative measure'' in lieu of BART if the alternative measure
achieves greater reasonable progress than would be achieved through the
installation and operation of BART.\72\ The rule further states that
``[i]f the distribution of emissions is not substantially different
than under BART, and the alternative measure results in greater
emissions reductions, than the alternative measures may be deemed to
achieve greater reasonable progress''.\73\ Because the emissions
reductions under EPA's BART proposal for Sundt Unit 4 and the
reductions from TEP's proposed alternative would occur at the same
facility, the distribution of emissions under BART and the alternative
are not substantially different. Therefore, if the alternative emission
control strategy results in greater emissions reductions than our BART
proposal, EPA may deem the alternative emission control strategy to
achieve greater reasonable progress. A comparison of annual emission
estimates between the BART determination and alternative to BART is
summarized in Table 16. BART determination annual emissions are based
upon the annual average emission factors and annual capacity factor
used in our BART analysis, consistent with coal usage. For the
alternative to BART, annual emissions are based on a combination of
historical natural gas usage data as indicated in TEP's submittal, as
well as standard emission factors for natural gas combustion. A more
detailed discussion of emission estimates from these two scenarios is
included in our TSD.
---------------------------------------------------------------------------

    \72\ 40 CFR 51.308(e)(2).
    \73\ 40 CFR 51.308(e)(3).

                   Table 16--Sundt 4: Comparison of BART Determination and Alternative to BART
----------------------------------------------------------------------------------------------------------------
                                                                               Natural gas fuel
            Parameters                    Units          BART determination         switch          Difference
----------------------------------------------------------------------------------------------------------------
Heat Duty........................  MMBtu/hr...........  1,371..............  1,828..............
Capacity Factor..................  ...................  0.49...............  0.37...............
NOX..............................  Ctrl Tech..........  SNCR+LNB+OFA.......  LNB+OFA............
                                   lb/MMBtu \1\.......  0.31...............  0.22...............
                                   tpy................  917................  652................             265
Particulate Matter...............  Ctrl Tech..........  Fabric Filter......  None...............
                                   lb/MMBtu \1\.......  0.03...............  0.01...............
                                   tpy................  88.................  30.................              59
SO2..............................  Ctrl Tech..........  Dry Sorbent          None...............
                                                         Injection.
                                   lb/MMBtu\1\........  0.22...............  0.00064............
                                   tpy................  644................  1.9................             642
----------------------------------------------------------------------------------------------------------------
\1\ Annual average emission factors.

    As seen in Table 16, a change to natural gas usage achieves greater
emission reductions than each of the individual BART determinations for
NOX, SO2, and particulate matter, as well as in
the aggregate. Although visibility modeling is not required to support
a better-than-BART determination in this instance, EPA conducted
modeling to verify the visibility benefits of the proposed alternative,
as compared with EPA's BART determination. This modeling is described
in the TSD and the results are summarized in Table 17.

 Table 17--Sundt 4: Visibility Impact and Improvement From Combined SO2 and NOX BART, and From Better-Than-BART
                                                   Alternative
----------------------------------------------------------------------------------------------------------------
                                                                            Visibility   Visibility improvement
                                                                              impact   -------------------------
                        Class I Area                            Distance  -------------   SNCR DSI
                                                                  (km)                      70%      Natural gas
                                                                            Base case     (ctrl15)     (ctrl13)
----------------------------------------------------------------------------------------------------------------
Chiricahua NM...............................................          144         0.43         0.09         0.19
Chiricahua WA...............................................          141         0.51         0.16         0.25
Galiuro WA..................................................           64         1.10         0.24         0.47
Gila WA.....................................................          232         0.17         0.06         0.10
Mazatzal WA.................................................          203         0.19         0.08         0.12
Mount Baldy WA..............................................          232         0.15         0.06         0.09
Pine Mountain WA............................................          247         0.15         0.06         0.09
Saguaro NP..................................................           17         3.40         0.49         1.06
Sierra Ancha WA.............................................          178         0.19         0.08         0.12
Superstition WA.............................................          137         0.32         0.11         0.19
Cumulative (sum)............................................  ...........          6.6          1.4          2.7
Maximum.....................................................  ...........         3.40         0.49         1.06
 CIAs >= 0.5 dv....................................  ...........            3            0            1
Million $/dv (cumul. dv)....................................  ...........  ...........         $2.8  ...........
Million $/dv (max. dv)......................................  ...........  ...........         $8.3  ...........
----------------------------------------------------------------------------------------------------------------

    Since Sundt is only 17 km from the eastern unit of Saguaro, its
emitted NOX may not be fully converted to NO2 by
the time it reaches there, as is assumed in the CALPUFF model. It thus
may not be fully available to form visibility-degrading particulate
nitrate. EPA explored this issue in CALPUFF sensitivity simulations
described in the TSD. For EPA's proposed BART of SNCR plus DSI, the
visibility improvement remains above 0.3 dv even when unrealistically
low 10 percent NO-to-NO2 conversion is assumed (i.e., no
additional conversion of NO to NO2 once the plume leaves the
stack). The improvement from switching to natural gas remains above 0.7
dv at Saguaro. These results show that the FIP's proposed BART
determination remains reasonable despite any concern over the NO
conversion rate; the visibility improvement from BART remains
substantial. The finding that natural gas provides better visibility
improvement than the proposed BART determination also remains sound
regardless of the NO conversion assumed.
    Based on this information, we consider a natural gas fuel switch to
result in greater emission reductions and achieve greater reasonable
progress than the proposed BART determinations. Under this scenario, we
are proposing a NOX emission limit of 0.25 lb/MMBtu based on
a 30-day BOD rolling average. As discussed previously in the
NOX BART determination, this represents about a 17 percent
increase from the annual average emission rate of 0.22 lb/MMBtu, which
we consider to provide sufficient margin for a limit that will apply at
all times, including periods of startup and shutdown. In addition, we
are proposing particulate matter and SO2 emission limits
consistent with natural gas use, as well as monitoring, reporting, and
recordkeeping requirements.

B. Chemical Lime Nelson Plant Kilns 1 and 2

    Summary: EPA is proposing to find that Chemical Lime Nelson is
subject to BART. EPA is proposing BART emission limits for
NOX, SO2 and PM10 for Kilns 1 and 2 at
the Nelson Plant as listed in Table 18 and described in this section.

                      Table 18--Nelson Lime Plant: Summary of Proposed BART Determinations
----------------------------------------------------------------------------------------------------------------
                                                                                Control technology*
               Source                       Pollutant        Emission Limit (lb/ton feed)  (for  reference only)
----------------------------------------------------------------------------------------------------------------
Kiln 1.............................  NOX...................                          3.80  Selective Non-
                                                                                Catalytic Reduction
                                                                                (SNCR).
                                     SO2...................                          9.32  Lower sulfur fuel.
                                     PM10..................                          0.12  Fabric filter
                                                                                baghouse (existing).
Kiln 2.............................  NOX...................                          2.61  Selective Non-
                                                                                Catalytic Reduction
                                                                                (SNCR).
                                     SO2...................                          9.73  Lower sulfur fuel.
                                     PM10..................                          0.12  Fabric filter
                                                                                baghouse (existing).
----------------------------------------------------------------------------------------------------------------
* The facility is not required to install the listed technology to meet the BART limit.

    Affected Class I Areas: Nine Class I areas are within 300 km of the
Nelson Lime Plant. Their nearest borders range from 24 km to 289 km
away, with the Grand Canyon the closest and other areas more than 100
km away. The highest baseline visibility impact from the Nelson Plant
is 1.79 dv at Grand Canyon NP followed by 0.31 at Sycamore Canyon WA
and 0.28 at Zion NP. The cumulative sum of visibility impacts over all
the Class I areas is 3.34 dv.
    Facility Overview: The Nelson Plant processes limestone and
manufactures lime near Peach Springs in Yavapai County, Arizona. The
limestone processing plant consists of a quarry mining operation, a
limestone crushing and screening operation, a limestone kiln feed
system, a solid fuel handling system, two rotary lime kilns, front and
back lime handling systems, a lime hydrator, diesel electric
generators, fuel storage tanks, and other support operations and
equipment. The lime manufacturing equipment consists of two lime rotary
kilns (Kiln 1 and Kiln 2) and auxiliary equipment necessary for
receiving crushed limestone, processing it through the lime kilns, and
processing the lime kiln product. The lime kilns are used to convert
crushed limestone (CaCO3) into quicklime (CaO).
    We primarily relied on four sources of information for our proposed
BART analyses and determinations. An initial BART analysis performed by
our contractor \74\ is available in the docket in the form of a final
contractor's report and associated modeling spreadsheets. We also
incorporated elements of a five-factor BART analysis \75\ provided by
Lhoist North America (LNA) of Arizona, owner of the Nelson Plant, that
includes control cost estimates and visibility modeling. Another key
document in our analysis is the Nelson Lime Plant's Title V Operating
Permit.\76\
---------------------------------------------------------------------------

    \74\ Technical Analysis for Arizona and Hawaii Regional Haze
FIPs: Task 7: Five-Factor BART Analysis for Chemical Lime Company
Nelson, TEP Sundt (Irvington), and Catalyst Paper (Snowflake)
Plants, Contract No. EP-D-07-102, Work Assignment 5-12; Prepared for
EPA Region 9 by University of North Carolina at Chapel Hill, ICF
International, and Andover Technology Partners; October 9, 2012.
    \75\ BART Five Factor Analysis, Lhoist North America Nelson Lime
Plant; Prepared by Trinity Consultants in Conjunction with Lhoist
North America of Arizona, Inc.; Project<PHONE_NUMBER>; August 2013.
(Public version dated September 27, 2013).
    \76\ Title V Operating Permit and Technical Support Document for
the Nelson Lime Plant, Permit  42782, Issued August 8, 2011
by the Arizona Department of Environmental Quality.
---------------------------------------------------------------------------

    Baseline Emissions Calculations: LNA's approach to establishing
baseline emissions was to first establish baseline emission factors in
lb/ton lime based on CEMS testing performed from March to June 2013.
Annual average baseline emissions were calculated by multiplying these
lb/ton emission factors by the highest annual lime production rate
observed over a period from 2001 to 2012. Maximum daily emissions were
calculated by multiplying lb/ton emission factors by the maximum daily
lime production rate observed during the March to June 2013 testing
period. As explained in further detail in our TSD, we consider LNA's
general approach appropriate, but also note that it represents a
conservatively high estimate of baseline emissions, and potentially
overstates the anticipated emission reductions and visibility benefit
from the evaluated control options. Nonetheless, given the lack of
measured annual emissions data, we concur with LNA's use of a
conservatively high baseline emissions estimate and we have
incorporated this estimate into our analysis. The baseline daily and
annual emission rates and associated production levels are shown in
Table 19.

                           Table 19--Nelson Lime Plant: Summary of Maximum Daily and Annual Baseline Emissions for NOX and SO2
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Lime production                              NOX                                    SO2
                                    --------------------------------------------------------------------------------------------------------------------
                                      Max daily    Max annual      Year       Emission       Maximum emissions       Emission       Maximum emissions
                Kiln                     \2\     --------------------------  factor \1\ --------------------------  factor \1\ -------------------------
                                    -------------                          -------------                          -------------
                                                     (tpy)                    (lb/ton      (lb/day)      (tpy)       (lb/ton      (lb/day)      (tpy)
                                        (tpd)                                  lime)                                  lime)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Kiln 1.............................          866  \3\ 258,508         2010         7.59        6,573          981        12.15       10,522        1,570
Kiln 2.............................        1,246  \4\ 378,296         2012         5.21        6,492          985        12.69       15,812        2,400
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Maximum emission factors observed during March, May and June 2013 CEMS testing.
\2\ Maximum daily rates occurring during the March 2013 CEMS testing.
\3\ 2010.
\4\ 2012.

1. Proposed Subject to BART
    As part of our July 30, 2013 final rulemaking on the Arizona RH
SIP, we approved ADEQ's finding that Chemical Lime Nelson Plant (Nelson
Lime Plant) Kilns 1 and 2 were BART-eligible, but disapproved ADEQ's
determination that the Nelson Lime Plant was not subject to BART.\77\
In light of this disapproval, we have conducted our own evaluation of
whether Nelson Lime Plant is subject to BART, relying primarily on
emissions

data and modeling results provided by the facility's owner, LNA.\78\
---------------------------------------------------------------------------

    \77\ 78 FR 46175 (codified at 40 CFR 52.145(g)(1)(i)).
    \78\ BART Five Factor Analysis, Lhoist North America Nelson Lime
Plant; Prepared by Trinity Consultants in Conjunction with Lhoist
North America of Arizona, Inc.; Project<PHONE_NUMBER>; August 13, 2013
(Public version dated September 27, 2013).
---------------------------------------------------------------------------

    As explained in the TSD, the baseline emissions estimates and the
corresponding modeling results provided by LNA are conservative (i.e.,
tending to overestimate rather than underestimate the impacts, in this
case). Nonetheless, we consider these results to be appropriate for
purposes of a subject-to-BART determination, as well as for the five-
factor BART analysis. LNA's modeling results indicate that the 98th
percentile impact for each of the 3 years modeled is well over 0.5 dv
at Grand Canyon National Park.\79\ Therefore, we propose to determine
that Nelson Lime Plant (Kilns 1 and 2) is subject to BART.
---------------------------------------------------------------------------

    \79\ Id., Table 4-7. We note that the visibility modeling
performed by LNA used only the annual average Class I area
background concentrations, rather than the best 20 percent days
background concentrations. The use of annual average generally
results in lower visibility impacts than the best 20 percent days.
Therefore, had LNA used the best 20 percent days, the baseline
impacts would likely have been even greater.
---------------------------------------------------------------------------

 2. Proposed BART for NOX
    For our NOX BART analysis, we identified all available
control technologies, eliminated options that are not technically
feasible, and evaluated the control effectiveness of the remaining
control options. We then evaluated each control in terms of a five-
factor BART analysis and made a determination for BART.
a. Control Technology Availability, Technical Feasibility and
Effectiveness
    EPA proposes to find that SNCR is the only technically feasible
control option to control NOX emissions with a control
efficiency of 50 percent. In order to determine a reasonable
performance standard for controlling NOX emissions, we
considered four available retrofit control technologies for
NOX on Kilns 1 and 2. These control technologies are a LNB,
mixing air technology (MAT), SCR, and SNCR. After evaluating each of
these technologies to eliminate technically infeasible options, we
determined that SNCR is the only remaining technically feasible control
option.
    Low-NOX Burners: LNB are designed to reduce flame
turbulence, delay fuel/air mixing, and establish fuel-rich zones for
initial combustion. LNA indicated that it experimented with the
installation of bluff body LNB on the Nelson Lime Plant kilns in
2001.\80\ These LNB wore out in about six months, negatively affected
production, caused brick damage, and resulted in unscheduled shutdowns
of the kilns. We recognize that the staged combustion principle of LNB
can present operational difficulties and potential product quality
issues for lime production that are not exhibited in the cement
industry. At this time we consider LNB to be technically infeasible for
the Nelson Plant kilns, since we do not have any information to suggest
otherwise at this time. The technical feasibility of LNB will be re-
evaluated for lime kilns in subsequent reasonable progress planning
periods.
---------------------------------------------------------------------------

    \80\ Described on page 5-2, ``BART Five Factor Analysis, Lhoist
North America Nelson Lime Plant'' (Public version dated September
27, 2013).
---------------------------------------------------------------------------

    Mixing Air Technology: MAT is the practice of injecting a high
pressure air stream into the middle of a kiln to help mix the air
flowing through the kiln. While the theory behind MAT suggests that the
technology is effective at reducing NOX emissions, it is not
clear whether this control technology is effective on lime kilns. We
propose to eliminate MAT as not technically feasible for retrofit on
Kiln 1 and Kiln 2.
    Selective Catalytic Reduction: This process uses ammonia in the
presence of a catalyst to selectively reduce NOX emissions
from exhaust gases. In SCR, ammonia, usually diluted with air or steam,
is injected through a grid system into hot flue gases that are then
passed through a catalyst bed to carry out NOX reduction
reactions. The catalyst is not consumed in the process but allows the
reactions to occur at a lower temperature. However, SCR is subject to
catalyst poisoning in high dust kiln exhausts. Therefore, SCR would
have to be placed after the particulate control systems. According to
LNA, given the operating temperature range for Kiln 1 and Kiln 2 at the
Nelson Lime Plant, the SCR catalyst would need to be located prior to
the kiln baghouses, which would result in poisoning or covering of the
catalyst. In addition, there are no SCR systems currently operating on
lime kilns. We propose to eliminate SCR as not technically feasible for
retrofit on Kiln 1 and Kiln 2.
    Selective Non-Catalytic Reduction: SNCR is a technically feasible
option for reducing NOX emissions from the Nelson Lime Plant
kilns as shown in Table 20. This control technique relies on the
reduction of NOX in exhaust gases by injection of ammonia or
urea, without using any catalyst. This approach avoids the problems
related to catalyst fouling and poisoning attributed to SCR, but
requires injection of the reagents in the kiln at a temperature between
1600[emsp14][deg]F to 2000[emsp14][deg]F. Because no catalyst is used
to increase the reaction rate, the temperature window is critical for
conducting this reaction. LNA has not conducted any detailed design
work for an SNCR system for the Nelson Plant kilns, but anticipates
that a 50 percent reduction is achievable based on LNA's experience
with operating a urea-injection system at another LNA lime plant.

                   Table 20--Nelson Lime Plant: SNCR Control Efficiency for Baseline Emissions
----------------------------------------------------------------------------------------------------------------
                                      Control        Emission          Maximum emission rate         Emissions
                                    efficiency        factor     --------------------------------     removed
         Control option          --------------------------------                                ---------------
                                        (%)        (lb/ton lime)     (lb/day)          (tpy)           (tpy)
----------------------------------------------------------------------------------------------------------------
Kiln 1:
    Baseline....................  ..............            7.59           6,573             981
    SNCR........................              50            3.80           3,286             491             491
Kiln 2:
    1Baseline...................  ..............            5.21           6,492             985
    SNCR........................              50            2.61           3,246             493             493
----------------------------------------------------------------------------------------------------------------

b. BART Analysis for NOX
    EPA conducted a five-factor BART analysis of SNCR to evaluate its
cost-effectiveness and visibility benefit. This analysis indicates that
SNCR is cost-effective and results in visibility improvement.
    Cost of Compliance: The following table provides LNA's estimated
cost for installation and operation of SNCR. Capital cost estimates
developed by LNA relied primarily on vendor cost estimates and LNA's
experience at other lime plants, with the remainder of the capital
costs calculated using the cost methodology contained in EPA's Control
Cost Manual. LNA has asserted a confidential business information (CBI)
claim regarding certain annual operating costs such as reagent usage
and auxiliary power costs. As a result, we have prepared our own
independent estimate of annual operating costs based upon a combination
of publicly available data and certain general assumptions as described
in the Contractor's Report.\81\ Table 21 is a summary of the estimated
cost for installation and operation of SNCR.
---------------------------------------------------------------------------

    \81\ Our estimate of annual operating costs is in the
spreadsheet ``Nelson Control Costs 2013-10-21.xlsx'' in the docket.

                                                  Table 21--Nelson Lime Plant: Estimated Cost for SNCR
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Capital cost     Annualized        Annual       Total annual      Emission          Cost-
                                                         ----------------  capital cost   operating cost       cost          reduction     effectiveness
                          Kiln                                           -------------------------------------------------------------------------------
                                                                ($)             ($)             ($)           ($/yr)           (tpy)          ($/ton)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Kiln 1..................................................        $450,000         $42,477        $358,459        $400,936             491            $817
Kiln 2..................................................         450,000          42,477         354,981         397,458             493             807
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: SNCR systems
require electricity to operate the blowers and pumps, which will likely
involve fuel combustion that will generate emissions. Overall, while
the generation of the required electricity will result in emissions,
the emissions should be low compared to the reduction in NOX
that would be gained by operating an SNCR system. The operation of SNCR
systems on Kiln 1 and Kiln 2 would require that either urea or ammonia
be stored on site. The storage of the chemicals does not result in a
direct non-air quality impact. However, the potential for the urea or
ammonia that would be stored to leak or otherwise be released from the
storage vessels means there is the potential for both air and non-air
quality related impacts. The storage of these chemicals does not
significantly impact the BART determination.
    Pollution Control Equipment in Use at the Source: The presence of
existing pollution control technology at each source is reflected in
our BART analysis in two ways: first, in the consideration of available
control technologies, and second, in the development of baseline
emission rates for use in cost calculations and visibility modeling.
Air pollution control equipment in use at the Nelson Lime Plant
includes a number of baghouses, two multi-cyclone dust collectors, and
a Ducon wet scrubber to control particulate matter emissions. The
facility does not currently have control equipment for NOX
and SO2. The kilns are allowed to burn coal, petroleum coke,
fuel oil, or any combination of these fuels.
    Remaining Useful Life of the Source: Since we are not aware of any
enforceable shutdown date for the Nelson Lime Plant, we have used a 20-
year amortization period, as noted in the EPA Cost Control Manual, as
the remaining useful life of the kilns.
    Degree of Visibility Improvement: LNA performed a visibility
analysis \82\ to assess the visibility improvement associated with
SNCR. LNA performed dispersion modeling using the CALPUFF modeling
system, which consists of the CALPUFF dispersion model, the CALMET
meteorological data processor, and the CALPOST post-processing program.
The specific program versions that were relied upon in the analysis
match the program versions relied upon by EPA's contractor, the
University of North Carolina at Chapel Hill and ICF International (UNC/
ICF), in the BART analyses that they prepared for select sources,
including the Nelson Plant. Most of the same data and parameter
settings relied upon in the analysis are the same data and parameter
settings that were relied upon in the contractor's report. Compared to
the UNC work, LNA used updated higher base case SO2 and NOx
emissions, lower PM emissions, and lower stack exit velocities. LNA's
analysis included tables of visibility impacts and the improvement from
controls, including results for the individual model years 2001, 2002,
and 2003, and it used visibility method ``8a'' and focused on the
highest value from among the three years' 98th percentiles. In order to
put all the facilities on the same footing, EPA post-processed the
modeling files provided by LNA using the approach followed for the
other facilities.
---------------------------------------------------------------------------

    \82\ BART Five Factor Analysis, Lhoist North America Nelson Lime
Plant, Trinity Consultants, August 2013.
---------------------------------------------------------------------------

    Table 22 represents the 98th percentile by the 22nd high over the
2001-2003 period using visibility method ``8b.'' Using the EPA
procedure, the maximum impact still occurs at the Grand Canyon, at 1.8
dv. The 98th percentile impacts at other Class I areas are about 0.3 dv
or below, and the cumulative impact is 3.3 dv. The maximum visibility
improvement due to SNCR is 0.58 dv, and cumulative improvement is 0.85
dv. There is little improvement at areas other than the Grand Canyon.
These improvements yield a visibility cost-effectiveness of $1.4
million/dv using the maximum, and $0.9 million/dv using the cumulative
improvement. These visibility improvements support the choice of SNCR
as BART for NOX.

                Table 22--Nelson Lime Plant: Visibility Impact and Improvement From NOX Controls
----------------------------------------------------------------------------------------------------------------
                                                                                Visibility      Visibility
                                                                                impact        improvement
                          Class I area                             Distance (km) -------------------------------
                                                                                Base case      SNCR (ctr1)
----------------------------------------------------------------------------------------------------------------
Bryce Canyon NP.................................................             235            0.20            0.06
Grand Canyon NP.................................................              24            1.79            0.58
Joshua Tree NP..................................................             238            0.23            0.02
Mazatzal WA.....................................................             206            0.15            0.01
Pine Mountain WA................................................             199            0.15            0.02
Sierra Ancha WA.................................................             289            0.11            0.01
Superstition WA.................................................             288            0.13            0.01
Sycamore Canyon WA..............................................             132            0.31            0.07
Zion NP.........................................................             183            0.28            0.08
Cumulative (sum)................................................  ..............            3.34            0.85
Maximum.........................................................  ..............            1.79            0.58
 CIAs >= 0.5 dv........................................  ..............            1               1
Million $/dv (cumul. dv)........................................  ..............  ..............           $0.9
Million $/dv (max. dv)..........................................  ..............  ..............           $1.4
----------------------------------------------------------------------------------------------------------------

c. Proposed BART Determination for NOX
    We propose to find that BART for NOX for Kilns 1 and 2
is SNCR, and are proposing a BART emission limit for Kiln 1 of 3.80 lb/
ton lime and for Kiln 2 of 2.61 lb/ton lime on a 30-day rolling basis,
as demonstrated through the use of a CEMS. We consider SNCR to be a
very cost-effective control option for Kilns 1 and 2, at $817/ton and
$807/ton, respectively. In addition, we consider the anticipated
visibility benefit from SNCR, 0.58 dv at Grand Canyon National Park and
0.85 cumulatively at all Class I areas within 300 km, to be
substantial. In considering the other factors, we do not consider their
impact substantial relative to the cost and visibility factors. We note
that the remaining useful life of the source is reflected in the
evaluation of cost of compliance through the use of a 20-year
amortization period in control cost calculations. Since there is no
existing NOX control technology in use on the kilns,
baseline emissions reflect uncontrolled NOX emissions. In
examining energy and non-air quality impacts, while we note certain
impacts associated with SNCR, we do not consider these impacts
sufficient to warrant its elimination as a control option.
    We propose to require compliance with this requirement within three
years after the effective date of the final rule. A 2006 Institute of
Clean Air Companies (ICAC) study indicated that the installation time
for a typical SNCR retrofit, from bid to startup-up, is 10-13
months.\83\ In relation to other industrial sources, such as fossil
fuel boilers, there are a limited number of examples of SNCR
installation on lime kilns. Given this relative lack of information
regarding SNCR installation schedules on lime kilns, we consider three
years to be an appropriate length of time to design, install, and test
an ammonia injection system for a lime kiln. In addition, we are also
proposing regulatory text that includes monitoring, reporting, and
recordkeeping requirements associated with this emission limit. As part
of the proposed monitoring requirements, we are including a requirement
to monitor rates of ammonia injection in order to ensure proper
operation of the SNCR in a manner that minimizes ammonia emissions.
---------------------------------------------------------------------------

    \83\ See ``Typical Installation Timelines for NOX
Emissions Control Technologies on Industrial Sources,'' Institute of
Clean Air Companies, December 4, 2006.
---------------------------------------------------------------------------

3. Proposed BART for SO2
    For our BART analysis, we identify all available control
technologies, eliminate options that are not technically feasible, and
evaluate the control effectiveness of the remaining control options. We
then evaluate each control in terms of a five-factor BART analysis and
make a determination for BART.
a. Control Technology Analysis for SO2
    EPA proposes to find that DSI and switching to lower sulfur fuel
are technically feasible controls, while wet or semi-dry scrubbing is
not technically feasible.
    Wet or Semi-Dry Scrubbing: We do not consider wet or dry scrubbing
to be a feasible technology to control SO2 emissions for
this source. Wet scrubbing involves passing flue gas downstream from
the main particulate matter control device through a sprayed aqueous
suspension of lime or limestone that is contained in a scrubbing
device. The SO2 reacts with the scrubbing reagent to form
lime sludge that is collected. The sludge usually is dewatered and
disposed of at an offsite landfill. However, LNA has concluded, and we
agree, that there is not sufficient water available for this type of
system. According to LNA, two ground water wells supply about 106
gallons per minute (gpm) to the Nelson Plant, which currently uses
about 80 gpm. Therefore, only 26 gpm of water is available for a
scrubbing system that, even for a semi-dry scrubbing system that has
lower water requirements than wet scrubbing, would require about 117
gpm. Moreover, a 1998 hydrologic report indicates that the prospects
for developing additional wells, even low-yield wells, on the Nelson
property are poor.\84\ After reviewing the hydrologic report and the
vendor estimate of water requirements for a semi-dry scrubber, we agree
with this assessment.
---------------------------------------------------------------------------

    \84\ See ``Results of Hydrogeologic Investigations for
Development of Additional Water Supply, Chemical Lime Company,
Nelson Plant, Yavapai County, AZ,'' July 8, 1998.
---------------------------------------------------------------------------

    Dry Sorbent Injection: DSI involves the injection of powdered
absorbent directly into the flue gas exhaust stream. The sorbent reacts
with SO2 in the exhaust to form solid particles that are
then removed by a particulate matter control device downstream of the
sorbent injection. DSI is a simple system that generally requires a
sorbent storage tank, feeding mechanism, transfer line and blower, and
an injection device. DSI is generally considered technically feasible
for the cement industry, although the level of control effectiveness
may vary based upon site-specific conditions. We consider this option
technically feasible for lime kilns. LNA has not included information
in its analysis indicating

that DSI would be infeasible for the Nelson Plant kilns.
    Lower Sulfur Fuel: The lower sulfur fuel option described by LNA
involves changing the proportion of coal and petroleum coke used as a
fuel blend. LNA currently uses a blend of 27 percent coal and 73
percent petroleum coke, on a mass basis, as the fuel for the kilns.
Since coke has about four to five times more sulfur than coal, it is
possible to decrease the sulfur in the fuel blend by increasing the
proportion of coal. However, an increase in coal in the fuel blend will
also increase the ash content of the fuel blend. Ash in the fuel can
disrupt operations due to the buildup of ash rings in the kilns. A fuel
blend with an ash content of about 6.5 percent or less must be used in
order to avoid these operational challenges.
    As noted in fuel usage and purchase records, the Nelson Plant
currently operates on a coal and petroleum coke mixture. As a result,
we consider adjusting the coal/coke ratio in the fuel mixture to be a
technically feasible option. We note, however, that since the BART
Guidelines do not require fuel supply changes to be considered as a
control option, we have typically not considered changes in fuel in
BART analyses.\85\ However, because LNA included lower sulfur fuel in
its analysis, we have retained it as a control option.
---------------------------------------------------------------------------

    \85\ 40 CFR Part 51, Appendix Y, Section IV.D.1.5, ``STEP 1: How
do I identify all available retrofit emission control techniques?''
---------------------------------------------------------------------------

b. BART Analysis for SO2
    EPA conducted a five-factor BART analysis of the two technically
feasible control options, DSI and lower sulfur fuel, to evaluate the
cost-effectiveness and visibility benefit of each option along with any
effect on the other factors.
    Cost of Compliance: Our consideration of the cost of compliance
focuses primarily on the cost-effectiveness of each control option as
measured in cost per ton and incremental cost per ton. We estimate the
SO2 emissions rates for DSI and lower sulfur fuel as shown
in Table 23, and the cost-effectiveness of these options as shown in
Table 24. DSI has a control efficiency of 40 percent that results in
about 1,588 tpy of SO2 removed from both kilns. Lower sulfur
fuel has a control efficiency of 23.3 percent that results in about 925
tpy of SO2 removed from both kilns. Based on the total
annual costs of controlling SO2 emissions at both kilns, DSI
would cost an average of about $4,200 per ton removed and lower sulfur
fuel about $860 per ton removed. Since there is no existing
SO2 control technology in use in the plant, baseline
emissions reflect uncontrolled SO2 emissions.
    While we consider it appropriate to use 40 percent control
efficiency \86\ for DSI, we are inviting comment on the control
effectiveness of 23.3 percent for a lower sulfur fuel blend based on
the ratio of coal (1.15 percent sulfur) to petroleum coke (5.64 percent
sulfur). LNA estimates that the maximum coal-to-coke ratio to maintain
overall fuel ash content below 6.5 percent is a 50 percent coal to 50
percent coke fuel mixture. A 50/50 mix corresponds to a fuel sulfur
reduction of 1.13 percentage points, which represents a 23.3 percent
reduction from the current fuel mixture. Based on a review of coal and
coke properties along with historical fuel usage at the Nelson Plant,
we agree with the use of a 50/50 coal-to-coke ratio and 23.3 percent
control effectiveness. However, LNA cites operational issues with fuel
ash content above 6.5 percent. Since ash is a contaminant that can
adversely affect lime product quality, we are seeking comment regarding
the extent to which it is appropriate to use fuel ash content of 6.5
percent as the upper bound for determining fuel mixture ratio. We may
finalize a different fuel mixture ratio based upon the comments we
receive.
---------------------------------------------------------------------------

    \86\ While the control efficiency for DSI is much higher for
cement kilns, LNA conducted onsite testing of DSI on the lime kilns
at the Nelson Plant that demonstrated it is appropriate to use 40
percent control efficiency. The docket includes a comparison of
LNA's tests of DSI to the analysis in our contractor's report.
---------------------------------------------------------------------------

    In estimating the costs of compliance, LNA relied on a vendor quote
for purchased equipment provided by Noltech dated May 22, 2013, with
the remainder of the capital costs calculated using the cost
methodology contained in EPA's Control Cost Manual.\87\ While these
capital costs are higher than those estimated by our contractor, we
consider the use of the Noltech vendor quote for the Nelson Plant
reasonable, and have incorporated it into our evaluation of the costs
of compliance. With regard to annual operating & maintenance costs, LNA
has asserted a confidential business information (CBI) claim regarding
certain annual operating costs such as reagent usage. As a result, we
have prepared our own independent estimate of annual operating costs
based upon a combination of publicly available data and certain
assumptions as described in the contractor's report. Detailed cost
calculations can be found in the docket.\88\
---------------------------------------------------------------------------

    \87\ Vendor quote included as an attachment to BART Five Factor
Analysis, Lhoist North America Nelson Lime Plant; (Public version
dated September 27, 2013).
    \88\ See spreadsheet ``Nelson Control Costs 2013-10-24.xlsx'' in
the docket.

                       Table 23--Nelson Lime Plant: SO2 Control Option Emission Estimates
----------------------------------------------------------------------------------------------------------------
                                                   Control      Emission     Maximum emission rate
             SO2 control technology               efficiency  factor (lb/ --------------------------   Removed
                                                     (%)       ton lime)      lb/day        Tpy         (tpy)
----------------------------------------------------------------------------------------------------------------
Kiln 1:
    Baseline...................................  ...........        12.15       10,526        1,571  ...........
    Lower Sulfur Fuel Blend....................        23.30         9.32        8,073        1,205          366
    Dry Sorbent Injection......................           40         7.29        6,316          943          628
Kiln 2:
    Baseline...................................  ...........        12.69       15,808        2,400  ...........
    Lower Sulfur Fuel Blend....................        23.30         9.73       12,125        1,841          559
    Dry Sorbent Injection......................           40         7.61        9,485        1,440          960
----------------------------------------------------------------------------------------------------------------

                                           Table 24--Nelson Lime Plant: SO2 Control Option Cost-Effectiveness
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Capital       Annual       Annual       Total       Emission    Cost-effectiveness  ($/
                                                                   cost        direct      indirect   annual cost   reduction             ton)
                    SO2 control technology                    -------------    costs        costs    ---------------------------------------------------
                                                                           --------------------------
                                                                   ($)         ($/yr)       ($/yr)       ($/yr)       (tpy)       Average    Incremental
--------------------------------------------------------------------------------------------------------------------------------------------------------
Kiln 1:
    Lower Sulfur Fuel Blend..................................  ...........  ...........  ...........     $313,096          366         $856  ...........
    Dry Sorbent Injection....................................   $2,497,559     $371,174   $2,621,832    2,621,832          628        4,174       $8,803
Kiln 2:
    Lower Sulfur Fuel Blend..................................  ...........  ...........  ...........      458,179          559          819  ...........
    Dry Sorbent Injection....................................    2,497,559      371,174    3,895,774    3,895,774          960        4,058        8,576
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Pollution Control Equipment in use at the Source: The presence of
existing pollution control technology at the Nelson Plant is reflected
in the BART analysis in two ways: first, in the consideration of
available control technologies, and second, in the development of
baseline emission rates for use in cost calculations and visibility
modeling. In the case of SO2, the kilns at the Nelson Plant
do not operate with any existing control technology. This is reflected
in the baseline emission rates, which represent uncontrolled
SO2 emissions.
    Energy and non-air quality environmental impacts: Regarding the
first option, DSI systems require electricity for operation. The
generation of the electricity needed to operate a DSI system will
likely involve fuel combustion that will generate emissions. Emissions
also are associated with the transport, handling, and storage of
sorbent. Overall, while the use of DSI will cause emissions from select
activities, the emissions should be low compared to the reduction in
SO2 that would be gained by operating a DSI system.
Regarding the second option, using a lower sulfur fuel blend means LNA
will obtain more of the energy for lime production from coal and less
of the energy from coke. Since the heating value of coke is slightly
higher than the heating value of coal, it is likely that LNA will burn
more total mass of fuel as a result of substituting some coal for coke.
While burning a lower sulfur fuel blend will likely result in a
reduction in SO2 emissions, it will involve the overall use
of greater quantities of coal, which may result in a collateral
increase of other pollutants such as NOX and CO.
    Remaining Useful Life of the Source: We are considering the
``remaining useful life'' of the kilns as one element of the overall
cost analysis as allowed by the BART Guidelines. In the absence of any
enforceable closure date, we have used a 20-year amortization period
described in the EPA Cost Control Manual as the remaining useful life
for the control options considered for the Nelson Plant kilns. Since
there is no capital costs associated with using a lower sulfur fuel
blend, the remaining useful life of the kilns is not a factor in the
evaluation of this technology.
    Degree of Visibility Improvement: As was the case for
NOX, EPA post-processed LNA's modeling results for
SO2 controls. The greatest improvement from DSI is 0.2 dv,
occurring at the Grand Canyon, with improvements at other areas a third
or less than this. The cumulative improvement is 0.6 dv. The maximum
and cumulative improvements from switching to lower sulfur fuel are
roughly half of these amounts. While visibility improvement by itself
could support either DSI or lower sulfur fuel as BART, lower sulfur
fuel is favored by its much lower average cost-effectiveness at $819-
856/ton compared to over $4000 for DSI. Baseline and control option
emission rates used in SO2 control scenario modeling are
summarized in Table 25 with the modeling results in Table 26.\89\
---------------------------------------------------------------------------

    \89\ These results are from EPA's post-processing of LNA's
modeling. See the TSD for a discussion of the differences between
EPA's results and the results reported by LNA in their BART
analysis.

                          Table 25--Nelson Lime Plant: SO2 Control Model Emission Rates
----------------------------------------------------------------------------------------------------------------
                                                   Control      Emission     Maximum 24-hr model emission rate
                                                  efficiency     factor   --------------------------------------
             SO2 control technology             --------------------------
                                                      %       lb/ton lime     lb/day       lb/hr         g/s
----------------------------------------------------------------------------------------------------------------
Kiln 1:
    Baseline...................................  ...........        12.15       10,526          439           55
    Lower Sulfur Fuel Blend....................        23.30         9.32        8,073          336           42
    Dry Sorbent Injection (SBC)................           40         7.29        6,315          263           33
Kiln 2:
    Baseline...................................  ...........        12.69       15,808          659           83
    Lower Sulfur Fuel Blend....................        23.30         9.73       12,125          505           64
    Dry Sorbent Injection (SBC)................           40         7.61        9,489          395           50
----------------------------------------------------------------------------------------------------------------

                   Table 26--Nelson Lime Plant: SO2 Control Option Visibility Modeling Results
----------------------------------------------------------------------------------------------------------------
                                                                          Visibility    Visibility  improvement
                                                              Distance      impact    --------------------------
                       Class I area                             (km)    --------------                Low-S fuel
                                                                           Base case    DSI (ctr2)      (ctr3)
----------------------------------------------------------------------------------------------------------------
Bryce Canyon NP...........................................          235          0.20          0.03         0.02

Grand Canyon NP...........................................           24          1.79          0.21         0.10
Joshua Tree NP............................................          238          0.23          0.07         0.04
Mazatzal WA...............................................          206          0.15          0.04         0.02
Pine Mountain WA..........................................          199          0.15          0.04         0.02
Sierra Ancha WA...........................................          289          0.11          0.04         0.02
Superstition WA...........................................          288          0.13          0.04         0.02
Sycamore Canyon WA........................................          132          0.31          0.06         0.04
Zion NP...................................................          183          0.28          0.04         0.02
Cumulative (sum)..........................................  ...........          3.34          0.57         0.29
Maximum...................................................  ...........          1.79          0.21         0.10
 CIAs >= 0.5 dv..................................  ...........          1             0               0
Million $/dv (cumul. dv)..................................  ...........  ............        $11.5          $2.6
Million $/dv (max. dv)....................................  ...........  ............        $30.7          $8.1
----------------------------------------------------------------------------------------------------------------

c. Proposed BART Determination for SO2
    We propose to find that BART for SO2 is the use of a
lower sulfur fuel blend with an emission limit of 9.32 lb/ton for Kiln
1 and 9.73 lb/ton for Kiln 2 \90\ on a rolling 30-day basis. In
evaluating the costs of compliance, we note that we consider DSI and
lower sulfur fuel to both be cost-effective control options, with
average cost-effectiveness values of approximately $800/ton and $4,000/
ton, respectively. In evaluating anticipated visibility benefit, while
DSI is anticipated to achieve the greatest visibility improvement (0.21
dv at Grand Canyon), this amount of visibility improvement is not
large, nor is the benefit anticipated for the next most stringent
control option, lower sulfur fuel (0.10 dv at Grand Canyon). In
considering the other factors, there is no significant effect on the
outcome of the cost and visibility analyses. The lack of existing
control technology is reflected in the baseline in the form of
uncontrolled SO2 emissions. In examining energy and non-air
quality impacts, we note that there may be certain collateral increases
in emissions, but that these increases are outweighed by the emission
reductions achieved by implementing the control technology and do not
warrant their elimination. The remaining useful life of the source is
reflected in the evaluation of the cost of compliance. We consider both
DSI and use of lower sulfur fuel to be cost-effective, but note that
the most stringent option, DSI, is considerably less cost-effective
than the use of lower sulfur fuel, with an incremental cost-
effectiveness, relative to lower sulfur fuel, of approximately $9,000/
ton. As a result, although DSI is the most stringent control option,
the visibility benefit it achieves is not large, and is achieved at a
very high incremental cost relative to the next most stringent control
option. Based on this information, we propose to find that BART for
SO2 is the use of a lower sulfur fuel blend.
---------------------------------------------------------------------------

    \90\ The differing emission limits are due to the different
baseline performance of the two kilns.
---------------------------------------------------------------------------

4. Proposed BART for PM10
    For our BART analysis, we identified fabric filter baghouses, the
existing control technology for PM10 on Kilns 1 and 2, as
the most stringent control available for this type of source.
a. Control Technology Analysis for PM10
    The Nelson Plant, as a major source of hazardous air pollutants
(HAPs), is subject to the Maximum Achievable Control Technology (MACT)
Standard for Lime Manufacturing Plants, and is required to meet an
emission limit of 0.12 lbs PM/TSF (ton of stone feed).\91\ The BART
Guidelines provide that unless there are new technologies subsequent to
the MACT standards that would lead to cost-effective increases in the
level of control, one may rely on the MACT standards for purposes of
BART.\92\ Based on information developed as part of the Lime MACT, we
estimate that existing fabric filter upgrades would result in annual
costs of $94,500.\93\ As noted in LNA's BART analysis, baseline PM
emissions for the two kilns, based on PM filterable stack test data and
annual lime production, are approximately 8 tpy and 15 tpy.\94\ This
would result in an average cost-effectiveness of about $6,300 to
$12,000/ton.
---------------------------------------------------------------------------

    \91\ 40 CFR Part 63, Subpart AAAAA, Table 1, Item 1 for existing
lime kilns with no wet scrubber prior to 2005.
    \92\ 40 CFR Part 51, Appendix Y, Section IV.C.
    \93\ Annual costs as described in the Economic Impact Analysis
for the Lime Manufacturing MACT Standard (EPA-452/R-03-013), Table
3-2, Model Kiln F. Adjusted from 1997 to 2013 dollars using the
consumer price index, available at ftp://ftp.bls.gov/pub/special.requests/cpi/cpiai.txt.
    \94\ As described in the LNA Nelson BART Analysis, Table 4-5.
---------------------------------------------------------------------------

b. BART Analysis for PM10
    The BART Guidelines provide that, in instances where a source
already has the most stringent controls available (including all
possible improvements), it is not necessary to complete each step of
the BART analysis. Further, as long as the most stringent controls
available are made federally enforceable for the purpose of
implementing BART for that source, one may skip the remainder of the
analysis, including the visibility analysis.\95\
---------------------------------------------------------------------------

    \95\ 40 CFR Part 51, Appendix Y, Section IV.D.9.
---------------------------------------------------------------------------

c. Proposed BART Determination for PM10
    We propose a BART emission limit of 0.12 lb/TSF to control
PM10 at Kilns 1 and 2 based on the use of the existing
fabric filter baghouses and commensurate with the MACT standard that
applies to this source. We seek comment on any cost-effective upgrades
or improvements that may result in a lower emission limit. We propose
to require compliance with this requirement within 6 months after the
effective date of the final rule. We also propose regulatory text that
includes monitoring, reporting, and recordkeeping requirements
associated with this emission limit that is found at the end of this
notice.

 C. Hayden Smelter

    Summary: EPA proposes to find that the ASARCO Hayden Smelter is
subject to BART for NOX in addition to SO2 as

determined by the State. ASARCO must capture and control SO2
emissions from the converter units that are subject to BART. In the
current method of operation, thousands of tons of SO2 from
these units are vented to the atmosphere with no pollution control. One
method to control SO2 emissions from the converter units is
to install and operate a second double contact acid plant with a
control efficiency of about 99.8 percent on a 30-day rolling average.
We estimate the annual cost of constructing and operating a second acid
plant to control SO2 emissions is about $872 per ton of
SO2 removed. While we consider the cost of a new acid plant
to be reasonable, we are proposing a performance standard as BART
rather than prescribing a particular method of control. For
NOX, we propose to set an annual emission limit of 40 tpy
from the BART-eligible units, based on our proposed determination that
no NOX controls are needed for BART at the Hayden Smelter.
Finally, we are proposing an emission limit and associated compliance
requirements for PM10.
    Affected Class I Areas: Twelve Class I areas are within 300 km of
the Hayden Smelter. Their nearest borders range from 48 km to 239 km
away. Galiuro WA and Superstition WA are the closest, followed by
Saguaro NP and Sierra Ancha WA. The highest baseline 98th percentile
visibility impact is 1.7 dv at Superstition, with impacts at Galiuro
slightly lower. Baseline visibility impacts at each of the twelve areas
exceed 0.5 dv. The cumulative sum of visibility impacts over all the
Class I areas is 12.1 dv.
    Facility Overview: ASARCO Hayden Smelter is a batch-process copper
smelter in Gila County, Arizona. We previously approved ADEQ's
determination that converters 1, 3, 4 and 5 and Anode Furnaces 1 and 2
at the facility are BART-eligible.\96\ We also approved ADEQ's
determination that these units are subject to BART for SO2
and that BART for PM10 at ASARCO Hayden is no additional
controls. However, we disapproved ADEQ's determination that existing
controls constitute BART for SO2 and that the units are not
subject to BART for NOX. In light of these disapprovals and
our FIP duty for regional haze in Arizona, we are required to
promulgate a FIP to address BART for SO2 and NOX.
---------------------------------------------------------------------------

    \96\ 78 FR 46412 (July 30, 2013). Please refer to the TSD for a
description of these units.
---------------------------------------------------------------------------

    Baseline Emissions Calculations: Since neither ASARCO nor ADEQ
identified baseline emissions for the Hayden Smelter, we calculated
baseline emissions for SO2 and NOX. For
SO2, we used as the baseline the average of the two highest
emitting years from the last five years that ASARCO reported to ADEQ.
For NOX, we estimated emission rates based on the rated
natural gas capacity of the burners in the four subject-to-BART
converters and the two anode furnaces.\97\ As indicated in Table 27,
the majority of the source's SO2 emissions (20,341 tpy of a
total of 22,621 tpy) are process emissions from the converters. These
process SO2 emissions are collected through a secondary
capture system, but are emitted uncontrolled through an annular stack
that bypasses the existing double contact acid plant. While our BART
analysis focuses on these uncontrolled SO2 emissions from
the converters, we also evaluated improved control of the
SO2 emissions from the existing acid plant and from the
anode furnaces as well as controlling NOX emissions from all
the BART units.
---------------------------------------------------------------------------

    \97\ ASARCO Hayden Title V permit.

                                Table 27--Hayden Smelter: BART Baseline Emissions
                                                 [Tons per year]
----------------------------------------------------------------------------------------------------------------
                                                              Converters
                                              -----------------------------------------
                                                 Existing      Annular                     Anode
                                                acid plant      stack                     furnaces      Total
                                                 (primary    (secondary    Uncaptured
                                                 capture)     capture)
----------------------------------------------------------------------------------------------------------------
SO2..........................................        1,034     20,341         1,209              37       22,621
                                              ------------------------------------------------------------------
NOX..........................................                     31                             19           50
----------------------------------------------------------------------------------------------------------------

    Modeling Overview: EPA is relying on modeled baseline and post-
control impacts of the ASARCO Hayden Smelter using stack parameters
provided by ASARCO in response to a 2013 EPA information request.\98\
We also modeled using stack parameters based on a 2012 stack test.\99\
Stack exit temperatures were comparable for these two models, but the
exit velocities from the 2012 stack test were far lower than those
provided by ASARCO in 2013. The 2012 stack test parameters resulted in
visibility impacts and control benefits about 10 percent higher than
the model using the 2013 parameters. We are conservatively using the
2013 ASARCO parameters to evaluate controls, since using the 2012
parameters would yield even greater visibility improvements. For both
sets of modeling runs, EPA used emission rates that were developed
using information provided by ASARCO.
---------------------------------------------------------------------------

    \98\ Letter from Jack Garrity, ASARCO to Thomas Webb, EPA, July
11, 2013; attached Memorandum from Ralph Morris and Lynsey Parker,
ENVIRON, to Eric Hiser, Jorden, Bischoff and Hiser, PLC, March 4,
2013.
    \99\ ASARCO Hayden CEMS Test Report, Energy and Environmental
Measurement Corporation, Test date: September, 2012.
---------------------------------------------------------------------------

 1. BART Analysis and Determination for SO2 From Converters
a. Control Technology Availability, Technical Feasibility and
Effectiveness
    EPA identified two available technology options to control the
20,341 tons of SO2 emissions from the annular stack that are
captured by a secondary collection system, but are released
uncontrolled through the annular stack. These options are to construct
and operate a second double contact acid plant or install a wet
scrubber on the annular portion of the existing stack. In addition, we
found that ASARCO could add a tail stack scrubber to the existing acid
plant to address the remaining emissions that are not converted and
removed as sulfuric acid by the acid plant. Regarding technical
feasibility, we note that ASARCO Hayden currently uses a double contact
acid plant to control SO2 emissions captured by the primary
capture system. Wet scrubbing also is commonly used in many industries
to control SO2. Thus, we find

that the double contact acid plant and wet scrubbing are technically
feasible. In terms of control effectiveness, ASARCO indicated in a
letter \100\ to EPA that its double contact acid plant is capable of
recovering 99.8 percent of the SO2 vented to it.\101\ In the
same letter, ASARCO noted that the expected control effectiveness of
wet scrubbing is 85 percent. We used these removal efficiencies in our
five-factor analyses. These analyses are explained in the TSD and
summarized below.
---------------------------------------------------------------------------

    \100\ Letter from Jack Garrity, ASARCO to Thomas Webb, EPA, July
11, 2013.
    \101\ Ibid.
---------------------------------------------------------------------------

b. Option 1: Double Contact Acid Plant for Secondary Capture
    Cost of Compliance: EPA determined the cost-effectiveness of a new
double contact acid plant is $872 per ton of SO2 removed as
shown in Table 28. As explained in the TSD, we conservatively estimated
the cost of construction of a double contact acid plant to be
$81,621,297. The annualized capital costs are based on a 20-year
lifespan and a seven percent interest rate. We applied a control
efficiency of 99.8 percent, which the existing acid plant is currently
achieving with limited cesium catalyst. The emission reduction was
applied to the secondary capture system baseline emissions. This cost
analysis does not include the offsetting value of any sulfuric acid
produced and sold. It does assume full catalyst replacement every other
year and air preheating with natural gas for 8,760 hours per year.

                                           Table 28--Hayden Smelter Option 1: Second Double Contact Acid Plant
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Annualized         Annual        Total annual       Tons SO2         Control         $/ton SO2
                   Capital cost                       capital cost    variable cost         cost           reduced         efficiency        removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
$81,621,297.......................................      $7,704,573      $10,006,010      $17,710,483           20,341            99.8%             $872
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: Controlling
secondary capture with a sulfuric acid plant at the Hayden Smelter
would require energy to heat inlet air from approximately
177[emsp14][deg]F to 735[emsp14][deg]F. This would require a heat input
of approximately 114 MMBtu/hour and could require 1,200 MMscf of
natural gas per year, resulting in up to 30 tpy of NOX
emissions.\102\ This assumes 100 percent of the needed heat results
from natural gas combustion. Non-air quality impacts from a second acid
plant are not expected to be significant given that ASARCO already has
the capacity to handle and store the much larger quantities of sulfuric
acid produced by the primary acid plant.
---------------------------------------------------------------------------

    \102\ This is based on the AP 42 factor for low-NOX
burners.
---------------------------------------------------------------------------

    Pollution Control Equipment in Use at the Source: As noted above
and further described in the TSD, a portion of the emissions from the
converters are controlled by a gas cleaning plant to remove particulate
matter and a double contact sulfuric acid plant that converts
SO2 to sulfuric acid. We considered these controls as part
of our analysis of available control technologies and in developing
baseline emission rates for use in cost calculations and visibility
modeling.
    Remaining Useful Life of the Source: The BART-eligible converters
have each been in place for about 40 years or longer. ASARCO has not
indicated that any of the converters would need to be replaced during
the 20-year capital cost recovery period.
    Degree of Visibility Improvement: Controlling SO2
emissions through a second double contact acid plant at a 98.8 percent
efficiency results in visibility improvement in 12 Class I areas in
Arizona and New Mexico as indicated in Table 29. Based on air quality
modeling, visibility improvement from controlling SO2 by
constructing a new acid plant to control converter emissions from the
secondary capture system is 1.5 dv at Superstition, and nearly the same
at Galiuro. Eleven of the Class I areas improve by at least 0.5 dv. The
cumulative improvement is 10.3 dv. The large visibility improvement at
many Class I Areas supports the choice of a new acid plant as BART for
SO2.

  Table 29--Hayden Smelter Option 1: Visibility Impact and Improvement
                            From SO2 Controls
------------------------------------------------------------------------
                                                             Visibility
                                               Visibility    improvement
          Class I area             Distance    impact base    new acid
                                     (km)     case  (base)      plant
                                                               (ctrl2)
------------------------------------------------------------------------
Chiricahua NM..................          170          1.05          0.89
Chiricahua WA..................          174          1.01          0.87
Galiuro WA.....................           48          1.73          1.45
Gila WA........................          186          0.69          0.60
Mazatzal WA....................          121          0.88          0.75
Mount Baldy WA.................          151          0.66          0.56
Petrified Forest NP............          215          0.70          0.61
Pine Mountain WA...............          168          0.67          0.57
Saguaro NP.....................           82          1.38          1.18
Sierra Ancha WA................           84          1.09          0.93
Superstition WA................           50          1.74          1.47
Sycamore Canyon WA.............          239          0.51          0.44
Cumulative (sum)...............  ...........         12.10         10.32
Maximum........................  ...........          1.74          1.47
 CIAs >= 0.5 dv.......  ...........         12            11
Million $/dv (cumul. dv).......  ...........  ............         $1.7
Million $/dv (max. dv).........  ...........  ............        $12.1
------------------------------------------------------------------------

c. Option 2: Wet Scrubber on Existing Stack for Secondary Capture
    Cost of Compliance: EPA determined that the annual cost of using a
wet scrubber to control SO2 emissions from the secondary
capture system is $972 per ton of SO2 removed as displayed
in Table 30. We calculated the costs of constructing and operating a
wet scrubber based on information provided in ASARCO's letter \103\
from which we used the highest operating cost estimates to demonstrate
cost-effectiveness. We also included a sludge hauling fee of $60 per
ton and assumed one ton of SO2 controlled would result in
five tons of sludge. According to ASARCO, these costs do not include
the cost of a booster fan or a modified stack that may be needed,
thereby somewhat increasing the cost over what is shown here. Although
the calculation includes the cost of hauling sludge off site, it does
not include the cost of treating or landfilling the sludge.
---------------------------------------------------------------------------

    \103\ Letter from Jack Garrity, ASARCO to Thomas Webb, EPA (July
11, 2013).

                                            Table 30--Hayden Smelter Option 2: Wet Scrubber on Existing Stack
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Annualized    Annual variable    Total annual       Tons SO2         Control         $/ton SO2
                   Capital cost                       capital cost         cost             cost           reduced         efficiency        removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
$28,000,000.......................................      $2,643,002      $14,186,965      $16,829,967           17,290              85%             $972
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: Operation of a
wet scrubber would likely require operation of a booster fan and a gas
re-heater to force emissions through the 305 meter stack. The addition
of a wet scrubber could result in a detached visible plume as water
vapor emitted from the scrubber condenses. Addition of a scrubber would
result in sludge which would have to be shipped off site to be treated
or landfilled. Because of metals in the sludge, it may need to be
treated as hazardous waste.
    Pollution Control Equipment in Use at the Source: This is the same
as for Option 1.
    Remaining Useful Life of the Source: This is the same as for Option
1.
    Degree of Visibility Improvement: We did not conduct visibility
modeling for this option. Because a scrubber is less efficient at
removing SO2 than a second acid plant, the emission rates
would be higher and there would be less visibility improvement from a
scrubber compared to an acid plant. Given that scrubbers are less cost-
effective than a second acid plant, we deemed it unnecessary to model
impacts.
d. Option 3: Wet Scrubber on Acid Tail Stack for Primary Capture
    Cost of Compliance: EPA determined the annual cost of using a wet
scrubber to control SO2 emissions from the existing acid
plant tail stack is $13,564 per ton of SO2 removed as
displayed in Table 31. We calculated the costs of constructing and
operating a wet scrubber based on information provided by ASARCO.\104\
In this case, we used the low-end estimate of operating costs because
we are demonstrating that this option is not cost-effective. We also
included a sludge hauling fee of $60 per ton and assumed one ton of
SO2 controlled would result in five tons of sludge. Again,
these costs did not include the cost of a booster fan or a modified
stack that may be needed. Although the calculation included the cost of
hauling sludge off site, it did not include the cost of treating or
disposing the sludge, which may be classified as hazardous waste
depending on the metals content. In addition, we note that some of the
SO2 that passes through the acid plant is emitted by the
flash furnace that is not BART-eligible.
---------------------------------------------------------------------------

    \104\ Ibid.

                                           Table 31--Hayden Smelter Option 3: Wet Scrubber on Acid Tail Stack
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Annualized    Annual variable    Total annual       Control          Tons SO2        $/ton SO2
                   Capital cost                       capital cost         cost             cost          efficiency        reduced          removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
$28,000,000.......................................      $2,643,002       $9,274,521      $11,917,523              85%              879          $13,564
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: This is the same
as for Option 2.
    Pollution Control Equipment in Use at the Source: This is the same
as for Options 1 and 2.
    Remaining Useful Life of the Source: This is the same as for
Options 1 and 2.
    Degree of Visibility Improvement: We did not conduct visibility
modeling for a tail stack scrubber because of the high control cost per
ton of SO2. However, because the scrubber would remove much
less SO2 than options 1 or 2 (second acid plant and wet
scrubber on the secondary capture, respectively), the expected
visibility improvement is far less than for options 1 and 2.
e. Proposed BART Determination for SO2 From Converters
    Based on the results of our BART analysis, we propose that BART for
SO2 from the converters is a level of control consistent
with what ASARCO could achieve through the installation of a new double
contact acid plant. This would control about 20,341 tpy of
SO2 emissions from the converter units at a cost of about
$872 per ton of SO2 removed, which we consider highly cost-
effective. The expected visibility benefits of this option are
substantial with a greater than 0.5 dv improvement in eleven Class I
areas with a maximum benefit of 1.47 dv at Superstition WA. We propose
to find that the energy and non-air quality environmental effects of
this option are not sufficient to warrant elimination of this option.
    Regarding the other options, a wet scrubber for the secondary
capture (Option 2) is less effective at a similar annual cost but with
greater non-air environmental impacts. Therefore, we do not propose to
require this as BART. Adding a scrubber to the existing acid tail stack
for the primary capture (Option 3) would result in a relatively small
amount of additional emissions reductions at a relatively high cost
($13,564 per ton of SO2 removed) and with potentially
significant non-air environmental impacts. Therefore, we propose that
the addition of a scrubber

to the existing acid plant is not required as BART.
    The specifics of our BART proposal for SO2 from the
converters are as follows:
     An SO2 control efficiency of 99.8 percent, 30-
day rolling average, on all SO2 captured by the primary and
secondary control systems. The control efficiency may be averaged
between the two capture systems on a mass basis, if needed. (For every
30-day period the total mass of SO2 exiting the two control
systems must be no greater than 0.0019 percent of the SO2
entering the control systems.)
     Compliance with the SO2 BART limit may be
verified either through the use of SO2 CEMS before and after
controls in each system or by using post-control CEMS and acid
production rates. A limit of 2.49 lbs SO2 emissions per tons
of sulfuric acid production is equivalent to 99.8 percent control.
     Operation and maintenance of primary and secondary capture
systems meeting the requirements of 40 CFR part 63, subpart QQQ.
    We propose to require that these requirements be met within 3 years
of promulgation of the final rule, consistent with the requirement of
the CAA and the RHR that BART be installed ``as expeditiously as
practicable.''
2. BART Analysis and Determination for SO2 From Anode
Furnaces
a. BART Analysis for SO2 From Anode Furnaces
    We identified the same two control technologies for the anode
furnaces: a new double contact acid plant and a wet scrubber. In
addition, we considered whether emissions from the anode furnaces might
be vented to the existing acid plant.
    Cost of Compliance: Based on our calculations, we estimated that
the cost to control 37 tpy of SO2 from the anode furnaces by
construction of a new acid plant is over $28,000 per ton, not including
the cost of inlet preheating,\105\ as shown in Table 32. The estimated
cost of installing and operating a wet scrubber is even more expensive
at over $80,000 per ton\106\ as shown in Table 33.
---------------------------------------------------------------------------

    \105\ See the TSD for further discussion of this issue.
    \106\ See the TSD, Section III.D.4.

                                             Table 32--Hayden Smelter: New Acid Plant for the Anode Furnaces
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Annualized         Annual        Total annual       Tons SO2         Control         $/ton SO2
                   Capital cost                       capital cost    variable cost         cost           reduced         efficiency        removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
$8,583,190........................................        $810,192         $261,827       $1,071,920               37            99.8%          $28,616
--------------------------------------------------------------------------------------------------------------------------------------------------------

                                            Table 33--Hayden Smelter: New Wet Scrubber for the Anode Furnaces
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Annualized         Annual        Total annual       Tons SO2         Control         $/ton SO2
                   Capital cost                       capital cost    variable cost         cost           reduced         efficiency        removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
$7,000,000........................................        $660,750       $2,009,570       $2,670,320               32              85%          $83,708
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: This is the same
as for the converters.
    Pollution Control Equipment in Use at the Source: The anode
furnaces currently have no SO2 controls in place.
    Remaining Useful Life of the Source: ASARCO has not indicated that
any of the anode furnaces would need to be replaced during the 20-year
capital cost recovery period.
    Degree of Visibility Improvement: We did not conduct visibility
modeling for the anode furnace emissions. However, since the emissions
from these units are a small fraction of those from the converters, the
expected visibility improvement would be far less than for any of the
controls considered for the converters.
b. Proposed BART Determination for SO2 From Anode Furnaces
    Given the high cost of control, and the small potential for
visibility improvement, we propose that controlling the 37 tpy of
SO2 emissions from the anode furnaces is not warranted as
BART. Furthermore, while redirecting the anode furnace emissions to the
existing acid plant might be technically feasible and cost-effective,
the emission reductions and visibility benefit, although not
calculated, would be much smaller than the calculated benefits from
controlling additional emissions from the converters.
    In order to ensure that emissions from anode furnaces do not
increase substantially in the future, we are proposing to establish a
work practice standard for these units. While BART determinations are
generally promulgated in the form of numeric emission limitations, the
RHR allows for use of equipment requirements or work practice standards
in lieu of a numeric limit where ``technological or economic
limitations on the applicability of measurement methodology to a
particular source would make the imposition of an emission standard
infeasible.''\107\ In this case, we find that a numerical emission
limitation for the anode furnaces would be infeasible because of the
relatively small amount of emissions from these units, compared with
the converters. Therefore, we are proposing to establish a work
practice standard in the form of a requirement that the anode furnaces
be charged with blister copper or higher purity copper. Because blister
copper is generally 98 to 99 percent pure copper, this requirement will
ensure that sulfur emission from the anode furnaces are minimized.
---------------------------------------------------------------------------

    \107\ 40 CFR 51.308(e)(1)(iii). See also 40 CFR 51.100(z)
(defining ``emission limitation'' and ``emission standard'' to
include ``any requirements which . . . prescribe equipment . . . for
a source to assure continuous emission reduction.''
---------------------------------------------------------------------------

 3. Subject-to-BART, BART Analysis and BART Determination for
NOX
a. Proposed Subject-to-BART Finding for NOX
    As explained in our final rule on the Arizona RH SIP, 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 potential to
emit for that pollutant is below a specified de minimis level.\108\
Neither the Hayden Smelter's current Title V permit nor the Arizona RH
SIP contains any physical or operational limitations that would limit
the PTE of the BART-eligible

source below the NOX de minimis threshold of 40 tpy.
Therefore, because the Hayden Smelter is subject to BART and has a PTE
of more than 40 tons per year of NOX, we have analyzed
potential NOX BART controls for the source.
---------------------------------------------------------------------------

    \108\ 40 CFR 51.308(e)(1)(ii)(C).
---------------------------------------------------------------------------

b. BART Analysis for NOX
    The Hayden Smelter's NOX emissions result from the
combustion of natural gas to heat process equipment. LNB are an
available, feasible and effective technical option for such process
heaters, with an estimated control efficiency of 50 percent.\109\
---------------------------------------------------------------------------

    \109\ AirControlNet, Version 4.1, documentation report by E.H.
Pechan and Associates, Inc. for U.S. EPA, Office of Air Quality,
Planning, and Standards, May 2006, section III, page 445.
---------------------------------------------------------------------------

    Cost of Compliance: According to the Documentation Report
accompanying AirControlNet, the cost to retrofit process heaters with
LNB is $2,200 per ton.\110\
---------------------------------------------------------------------------

    \110\ Id.
---------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: No significant
energy and non-air environmental impacts are expected to result from
use of LNB.
    Pollution Control Equipment in Use at the Source: No NOX
controls are currently employed at either the converters or the anode
furnaces.
    Remaining Useful Life of the Source: ASARCO has not indicated that
any of the units would need to be replaced during the 20-year capital
cost recovery period.
    Degree of Visibility Improvement: The maximum modeled 98th
percentile visibility impact resulting from baseline NOX
emissions from the Hayden Smelter is no higher than 0.01 dv\111\ at any
of the Class I areas. Thus, the maximum visibility benefit of controls
is less than 0.01 dv.
---------------------------------------------------------------------------

    \111\ Summary of WRAP RMC BART Modeling for Arizona, Draft
Number 5, May 25, 2007. Also, ASARCO response letter, July 11, 2013,
ENVIRON memo attachment, March 4, 2012, (``H-09 2013-03-04 ENVIRON
report-Asarco-Hayden-BART.pdf''.
---------------------------------------------------------------------------

c. Proposed BART Determination for NOX
    Given the small potential for visibility improvement, we propose
that controlling these NOX emissions is not warranted for
purposes of BART. However, in order to ensure that NOX
emissions do not increase in the future, we propose to set a 12-month
rolling limit of 40 tons of NOX from the subject-to-BART
units, which is equivalent to the de minimis level of emissions set out
in the RHR.\112\ This emission limit is slightly lower than the annual
50 tpy baseline emissions noted above. Nonetheless, we consider it to
be a reasonable limit because the 50 tpy estimate assumes that all of
the converters are all operating simultaneously, which is not how they
typically operate. Therefore, we expect actual emissions to be well
below 40 tpy, which is consistent with ASARCO's own estimate.\113\
---------------------------------------------------------------------------

    \112\ 40 CFR 51.308(e)(1)(ii)(C).
    \113\ Letter from Krishna Parameswaran, ASARCO, to Gregory Nudd,
EPA dated March 6, 2013, page 15.
---------------------------------------------------------------------------

4. Summary of EPA's Proposed BART Determinations
    We propose that BART for SO2 from the converters is a
control efficiency of 99.8 percent, 30-day rolling average, on all
SO2 captured by the primary and secondary control systems.
We propose to require compliance with this requirement within three
years of promulgation of a final rule. We also are proposing
monitoring, recordkeeping and reporting as well as operation and
maintenance requirements, to ensure the enforceability of our proposed
BART determination. We propose a work practice standard consistent with
current practices for the anode furnaces. We also propose to set a 12-
month rolling limit of 40 tons of NOX from the subject-to-
BART units.
    We are seeking comment on all aspects of this proposal. In
particular, we are seeking comment on the following elements of our
BART analysis and determination for SO2 from the converters:
     The cost of controls;
     the collection efficiency for the primary collection
system;
     the collection efficiency for the secondary collection
system;
     the control efficiency to be applied to the primary and
secondary collections systems;
     the compliance methodology; and
     the compliance schedule.

If we receive additional information concerning these or other elements
of our analysis, we may finalize a BART determination that differs in
some respects from this proposal.

D. Miami Smelter

    Summary: EPA proposes to find that the Miami Smelter is subject to
BART for NOX in addition to SO2 and
PM10, as determined by the State. For SO2 from
the converters, we propose to require construction of a secondary
capture system consistent with the requirements of MACT QQQ and an
SO2 control efficiency of 99.7 percent, 30-day rolling
average, on all SO2 captured by the primary and secondary
capture systems. For SO2 emissions from the electric
furnace, we propose to prohibit active aeration of the electric
furnace. For NOX, we propose to find that controlling
emissions from the converters and anode furnaces is cost-effective, but
would not result in sufficient visibility improvement to warrant the
cost. Therefore, we are proposing an annual emission limit of 40 tpy
NOX emissions from the BART-eligible units at the Miami
Smelter, which is consistent with current emissions from these units.
We previously approved Arizona's determination that BART for
PM10 at the Miami Smelter is the NESHAP for Primary Copper
Smelting. Please refer to the Long Term Strategy in Section VII below,
regarding our proposal to ensure the enforceability of this
determination.
    Affected Class I Areas: Twelve Class I areas are within 300 km of
the Miami Smelter with the nearest borders ranging from 55 km to 260 km
away. The set of areas differs from the ones near the Hayden Smelter
only in that Bosque Del Apache WA is included, and Sycamore Canyon WA
is not. The baseline visibility impacts are 0.70 dv or less at all
Class I areas except at Superstition where the visibility impact is 3.6
dv. The cumulative sum of visibility impacts at all areas within 300 km
is 8.2 dv.
    Facility Overview: The Miami Smelter is a batch-process copper
smelter in Gila County, Arizona. We previously approved ADEQ's
determination that Hoboken Converters 2, 3, 4 and 5 and the Electric
Furnace at the facility are BART-eligible.\114\ We also approved ADEQ's
determination that these units are subject to BART for SO2
and that BART for PM10 at the Miami Smelter is the Maximum
Achievable Control Technology (MACT) Subpart QQQ under the National
Emission Standards for Hazardous Air Pollutants (NESHAP) for primary
copper smelting. However, we disapproved ADEQ's determination that
existing controls constitute BART for SO2 and that the units
are not subject to BART for NOX. In light of these
disapprovals and our FIP duty for Regional Haze in Arizona, we are
required to promulgate a FIP to address BART for both SO2
and NOX.
---------------------------------------------------------------------------

    \114\ 78 FR 46412 (July 30, 2013). See also the TSD for a
description of these units.
---------------------------------------------------------------------------

    Baseline Emissions: Because neither FMMI nor ADEQ identified
baseline emissions for the Miami Smelter, we selected emissions from
2010 as the baseline. We chose 2010 because ADEQ provided the most
detailed emissions information from this year in its RH SIP and because
FMMI used 2010 as a basis for calculating uncaptured emissions of
SO2 for 2011 and 2012. FMMI reports

emissions of SO2 to ADEQ by stack, and performs a mass-
balance equation to determine uncaptured emissions. SO2
emissions in tons per year are presented in Table 34 as reported by
FMMI to ADEQ for the acid plant duct, acid plant bypass duct, and the
vent fume duct.\115\ Because each of these stacks vents emissions from
both BART and non-BART emission units, EPA apportioned the emissions to
BART and non-BART units for purposes of our analysis. The BART-eligible
emissions from the acid plant were based on FMMI and ADEQ's estimate
that 35 percent of SO2 sent to the acid plant is emitted by
the converters and 65 percent of SO2 is emitted by the
primary smelter (often called by a proprietary name, the IsaSmelt
furnace) and electric furnace. Because it is not possible to
differentiate which converter emissions are from the one converter that
is not BART-eligible, we are treating all converter emissions as
subject to BART. Subject-to-BART emissions from the vent fume duct were
set at seven tons per year based on our estimate of the share of
emissions originating from the electric furnace. Please refer to the
TSD for an explanation for how the subject-to-BART uncaptured emissions
are determined.
---------------------------------------------------------------------------

    \115\ The vent fume duct is the stack for a wet scrubber used to
control emissions collected by the IsaSmelt secondary collection
system, other collection systems associated with conveyors that are
not BART-eligible, and emissions collected by the BART-eligible
electric furnace secondary collection system.

                        Table 34--Miami Smelter: BART Baseline Emissions for SO2 in 2010
                                                 [Tons per year]
----------------------------------------------------------------------------------------------------------------
                                                    Acid plant      Acid plant
                                                       duct           bypass      Vent fume duct    Uncaptured
----------------------------------------------------------------------------------------------------------------
Total SO2 Emissions.............................           1,415              93             331           8,472
Subject-to-BART SO2 Emissions...................             495              33               7     3,231-8,078
----------------------------------------------------------------------------------------------------------------

    FMMI also reports potentially BART-eligible NOX
emissions from the acid plant duct and from ``natural gas combustion''
to ADEQ as depicted in Table 35. FMMI estimates that 15 percent of
NOX emitted from the acid plant duct originates from the
BART-eligible converters. While ``natural gas emissions'' includes
emissions from the converter burners, it is not possible to separate
the BART-eligible emissions from ineligible emissions. Thus, we are
assuming that all these emissions are BART-eligible.

    Table 35--Miami Smelter: BART Baseline Emissions for NOX in 2010
                             [Tons per year]
------------------------------------------------------------------------
                                            Acid plant      Natural gas
                                               duct         combustion
------------------------------------------------------------------------
Total NOx Emissions.....................             154              15
Subject-to-BART NOX Emissions...........              23              15
------------------------------------------------------------------------

    Modeling Overview: Using the CALPUFF model, EPA estimated the
visibility impacts of the Miami Smelter in its current (i.e., baseline)
configuration, and with two different control options for
SO2 emissions. Model inputs were developed using work by the
WRAP and updated stack and other information from FMMI. EPA made two
different emissions calculations, incorporating high and low estimates
of the amount of emissions that are not captured by the existing
systems. Most of the discussion below focuses on modeling performed
using the high estimate as shown in Table 37.
    An additional complication for this facility is that most of the
emissions occur via a ``roofline,'' a long rectangular hole in the roof
of the building containing the converters. Modeling the roofline as if
it were a stack may be problematic, especially for nearby Class I
areas. Modeling the roofline as a buoyant line source is a better
characterization of the source. EPA performed sensitivity simulations,
described in the TSD, and found that impacts do vary depending on
whether it is modeled as a stack or a line source. Which modeling
scenario resulted in higher impacts depended on the particular Class I
area. EPA therefore modeled the main emissions from FMMI as a buoyant
line source, despite the considerably longer model run times.
1. BART Analysis for SO2 From Converters
a. Control Technology Availability, Technical Feasibility and
Effectiveness
    We identified two available and feasible technologies to control
SO2 emissions from the converters: a double contact acid
plant and wet scrubbing. FMMI already uses these two technologies in
series to control SO2 emissions currently captured from the
converters. Based on SO2 acid plant emissions and sulfuric
acid production data provided to EPA by FMMI, we calculated that the
existing acid plant and tail gas scrubber system is controlling at
least 99.7 percent of the SO2 ducted to the acid plant,\116\
which we consider effective. Because FMMI already uses both of the two
available control technologies to control SO2 emissions
currently captured from the converters and achieves a high degree of
control of these emissions, we did not further evaluate additional
controls or upgrades to the existing controls as BART. Rather, we
evaluated ways to improve the capture efficiency of the existing system
so that additional emissions may be collected and controlled.
---------------------------------------------------------------------------

    \116\ Letter from Derek Cooke, FMMI, to Thomas Webb, EPA,
Appendices A and C, January 25, 2013.
---------------------------------------------------------------------------

    In order to analyze options for improved capture, we requested
information from FMMI regarding potential design improvements, upgrades
to existing equipment or new equipment that could increase the degree
of capture of SO2 emissions from the converters.\117\ In
response, FMMI reported that it planned to improve the

converter mouth covers, reconfigure the roofline capture system and
route the captured emissions to the existing acid plant.\118\
Accordingly, we performed a five-factor BART analysis for these
improvements, which we refer to collectively as a ``secondary capture
system.''
---------------------------------------------------------------------------

    \117\ Letter from Thomas Webb, EPA, to Derek Cooke, FMMI (June
27, 2013).
    \118\ Letter from Derek Cooke, FMMI to Thomas Webb, EPA, Item 2
(July 12, 2013). FMMI indicated that ``[t]hese proposed changes are
in anticipation of measures that may be adopted by ADEQ as necessary
to demonstrate compliance'' with the 2012 SO2 NAAQS.''
Regardless of their regulatory purpose of the changes, FMMI's
proposal indicates that these changes are technically feasible.
---------------------------------------------------------------------------

b. Secondary Capture System
    The purpose of the secondary capture system is to improve capture
and control of SO2 emissions from the converters that can
then be directed to the existing double contact acid plant.
    Cost of Compliance: FMMI claimed as confidential business
information (CBI) the cost information for improvements in
SO2 capture, so we relied on other information to estimate
the cost of controls. In particular, we considered cost estimates
supplied by ASARCO for the Hayden Smelter, a similar facility, for a
series of upgrades to its capture systems.\119\ We estimated cost-
effectiveness using a capital cost of $47,850,000, and annualized those
costs assuming a 20-year lifespan and a 7 percent interest rate with an
operation and maintenance cost of 50 percent of the capital cost. We
applied a control efficiency of 99.7 percent, which the existing acid
plant and tail stack scrubber system currently achieves using very
limited cesium catalyst. The emission reduction was applied to 85
percent of the currently uncaptured SO2 emissions from the
converters.\120\ Based on these calculations, we estimate the cost-
effectiveness of installing and operating a secondary capture system
would be $990 to $2,474 per ton of SO2 removed, as shown in
Table 36. This range reflects the uncertainty in the quantity of
SO2 emissions that are currently not captured.
---------------------------------------------------------------------------

    \119\ See the TSD, Section III.D.4.
    \120\ Review of New Source Performance Standards for Primary
Copper Smelters, OAQPS, EPA 450/3-83-018a, March 1984. According to
Section <IP_ADDRESS>, the overall collection efficiency of secondary
fixed hoods is approximately 90 percent.

                                        Table 36--Miami Smelter: Cost of Secondary Capture of SO2 From Converters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Annualized         Annual        Total annual       Tons SO2         Control         $/ton SO2
                   Capital cost                       capital cost    variable cost         cost           reduced         efficiency        removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
$47,850,000.......................................      $4,516,701       $2,258,351       $6,775,052      2,379-6,845            99.7%       $990-2,474
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: We do not
anticipate significant energy or other non-air quality environmental
impacts resulting from capturing and ducting additional emissions to
the existing SO2 control system given that FMMI already has
the capacity to handle and store the much larger quantities of sulfuric
acid produced by emissions captured from the IsaSmelt and converter
primary capture systems.
    Pollution Control Equipment in Use at the Source: SO2
emissions collected from the converters are ducted to the four-pass,
double contact acid plant. There is a wet scrubber (the tailstack
scrubber) located after the acid plant outlet, to which emissions may
be vented during periods of elevated SO2
concentrations.\121\
---------------------------------------------------------------------------

    \121\ Letter from Derek Cooke, FMMI to Thomas Webb, EPA, Item 2
(July 12, 2013).
---------------------------------------------------------------------------

    Remaining Useful Life: The BART-eligible converters have each been
in place for about 40 years. FMMI has not indicated that any of them
would be replaced during the 20-year capital cost recovery period.
    Degree of Visibility Improvement: As shown in Table 37, installing
a secondary capture system to collect and direct SO2
emissions from the converters to the acid plant, the maximum 98th
percentile baseline improvement ranges from a low of 0.41 dv to a high
of 1.06 dv at Superstition WA. The cumulative improvement ranges from
1.7 to 4.3 dv. These are large visibility improvements that support
using the existing acid plant with a new secondary capture system as
BART for SO2. The high and low visibility impacts and
improvements in Table 37 correspond to the range of emissions that are
not captured. The range is 3,231 (low) to 8,078 (high) tpy. For the low
emission estimate, the maximum improvement from the secondary capture
system is 0.41 dv, and the cumulative improvement is 1.7 dv. These are
considerably less than for the high emission estimate, which has a
maximum improvement of 1.06 dv and cumulative improvement of 4.3 dv,
but is still substantial.

            Table 37--Miami Smelter: Visibility Impact and Improvement From Secondary Capture System
----------------------------------------------------------------------------------------------------------------
                                                             Impact      Improvement     Impact      Improvement
                                                         -------------- from control -------------- from control
                                               Distance                --------------              -------------
                Class I area                     (km)       High base     Converter     Low base      Converter
                                                              case       85% capture      case       85% capture
                                                            (basehi)      (opt1hi)      (baselo)      (opt1lo)
----------------------------------------------------------------------------------------------------------------
Bosque del Apache WA.......................          235          0.15          0.12          0.07          0.05
Chiricahua NM..............................          113          0.36          0.27          0.16          0.10
Chiricahua WA..............................          125          0.35          0.27          0.16          0.10
Galiuro WA.................................           99          0.56          0.40          0.28          0.17
Gila WA....................................           55          0.34          0.26          0.16          0.10
Mazatzal WA................................          220          0.64          0.44          0.32          0.17
Mount Baldy WA.............................           95          0.27          0.20          0.13          0.08
Petrified Forest NP........................          197          0.33          0.25          0.16          0.10
Pine Mountain WA...........................          260          0.43          0.32          0.20          0.12
Saguaro NP.................................          143          0.45          0.34          0.21          0.13
Sierra Ancha WA............................          158          0.70          0.40          0.42          0.17
Superstition WA............................          163          3.61          1.06          2.86          0.41

Cumulative (sum)...........................  ...........          8.2           4.3           5.1           1.7
Maximum....................................  ...........          3.61          1.06          2.86          0.41
 CIAs >= 0.5 dv...................  ...........          4             1             1             0
Million $/dv (cumul. dv)...................  ...........  ............         $1.6   ............         $4.0
Million $/dv (max. dv).....................  ...........  ............         $6.4   ............        $16.7
----------------------------------------------------------------------------------------------------------------

c. Proposed BART Determination for SO2 From Converters
    Based on the results of our BART analysis, we propose that BART for
SO2 from the converters is construction of a secondary
capture system (i.e., construction of hooding and ventilation systems
to capture escaped SO2 emissions) and ducting the emissions
to existing controls. We have determined that these improvements are
feasible and cost-effective, will result in significant visibility
improvements, and should not result in significant adverse impacts. As
noted above, the RHR allows for use of equipment requirements or work
practice standards in lieu of a numeric limit where ``technological or
economic limitations on the applicability of measurement methodology to
a particular source would make the imposition of an emission standard
infeasible.'' \122\ In this instance, we propose to find that
technological limitations on the source's ability to measure accurately
uncaptured SO2 emissions make numeric capture efficiency
infeasible. Therefore, we are proposing to prescribe specific equipment
for capture of SO2 emissions, in addition to numeric control
efficiency and related compliance requirements. Specifically, we are
proposing the following as BART for SO2 from the converters:
---------------------------------------------------------------------------

    \122\ 40 CFR 51.308(e)(1)(iii). See also 40 CFR
51.100(z)(defining ``emission limitation'' and ``emission standard''
to include ``any requirements which . . . prescribe equipment . . .
for a source to assure continuous emission reduction.''
---------------------------------------------------------------------------

     Construction of a secondary capture system consistent with
the requirements of MACT QQQ as a work practice standard.
     An SO2 control efficiency of 99.7 percent, 30-
day rolling average, on all SO2 captured by the primary and
secondary capture systems.
     Compliance with the SO2 BART limit may be
verified either through the use of SO2 CEMS before and after
controls or by using post-control CEMS and acid production rates. A
limit of 4.06 lbs SO2 emissions per tons of sulfuric acid
production is equivalent to 99.7 percent control.
d. Alternative Control Efficiency
    We are also seeking comment on whether FMMI should be expected to
meet a 99.8 percent control efficiency, 30-day rolling average, on all
SO2 captured by the primary and secondary capture systems.
ASARCO Hayden has demonstrated that a control efficiency of 99.8
percent is achievable in practice at a batch copper smelter. FMMI could
increase control efficiency by increasing its use of cesium promoted
catalyst in the acid plant, increasing the volume of gas exiting the
acid plant that is further controlled by the tail stack scrubber, and/
or using sodium rather than magnesium in the scrubbing liquor. If we
received comments establishing that a control efficiency greater than
99.7 percent is achievable at FMMI, we may finalize a control
efficiency of up to 99.8 percent.
 2. BART Analysis for SO2 From Electric Furnace
a. Control Technology Availability, Technical Feasibility and
Effectiveness
    EPA identified two possible technologies to control SO2
emissions from the electric furnace: Double contact acid plant and wet
scrubbing. FMMI has indicated to EPA that emissions from the electric
furnace are already controlled by the existing double contact acid
plant and tail stack scrubber.\123\ In addition, a secondary capture
system ducts gases not captured by the primary capture system to the
vent fume scrubber, which has a control efficiency of 80 percent.
Because FMMI already uses both of the two available control
technologies to control SO2 emissions currently captured
from the furnace, we did not evaluate the addition of new controls, nor
did we evaluate upgrades to the acid plant system, which already
achieves a high degree of control. The one improvement to controls that
we identified was upgrading the scrubber, which currently uses
magnesium oxide, to use sodium hydroxide, which could increase the
control efficiency from 80 percent to 98 percent.
---------------------------------------------------------------------------

    \123\ ADEQ Class 1 Permit Number 53592, Application for a
Significant Permit Revision, July, 2013.
---------------------------------------------------------------------------

b. Existing Double Contact Acid Plant and Wet Scrubbing
    Cost of Compliance: We estimated the emissions from the electric
furnace by multiplying the relevant AP 42 emission factors for copper
smelters \124\ by the 2010 concentrate throughput provided by FMMI.
This results in uncontrolled emissions of SO2 from the
electric furnace of 379 tons per year. Because the scrubber is a
secondary control device, however, this would likely result in an
emissions decrease of no more than 5 to 10 tons per year. Replacing
magnesium oxide with sodium hydroxide would cost at least $2,000,000
per year, resulting in control costs of $200,000-$400,000 per ton of
SO2 removed, as shown in Table 38.
---------------------------------------------------------------------------

    \124\ AP 42, Chapter 12.3, Primary Copper Smelters, Table 12.3-3
(cleaning furnace) and Table 12.3-11 (converter slag return).

                                              Table 38--Miami Smelter: Cost of Upgrading Vent Fume Scrubber
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                 Annualized         Annual        Total annual       Tons SO2         Control
                Capital cost                    capital cost    variable cost         cost           reduced         efficiency      $/ton SO2 removed
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   $2,000,000       $2,000,000             5-10              98%      $200,000-$400,000
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Energy and Non-Air Quality Environmental Impacts: We do not
anticipate significant energy or non-air quality environmental impacts
resulting from capturing and ducting additional emissions to the
existing SO2 control system. Non-air quality impacts from
venting additional captured emissions to the existing scrubber are not
expected to be significant given that FMMI is already controlling much
larger quantities of SO2 in the existing scrubber and
managing the wastewater and sludge that result.
    Pollution Control Equipment in Use at the Source: SO2
emissions collected from the electric furnace are ducted to the four-
pass, double contact acid plant. There is a wet scrubber (the tailstack
scrubber) located after the acid plant outlet, to which emissions may
be vented ``if needed.'' In addition, gases collected from the
secondary collection system are ducted to the vent fume scrubber, which
is another wet scrubber. The vent fume scrubber also controls secondary
emissions from the IsaSmelt and emissions collected from other
equipment.
    Remaining Useful Life: FMMI has not indicated any plans to remove
the electric furnace from service.
    Degree of Visibility Improvement: Our modeling results did not
demonstrate even modest visibility improvements at any Class I areas
from this option. Improvements were 0.004 dv or less at each Class I
area, and only 0.008 dv for the cumulative sum over all areas. These
are negligible visibility improvements over the baseline levels, as
expected from the small emission reductions associated with this
option.
c. BART Determination for Electric Furnace
    Based on the high cost of compliance to upgrade the vent fume
scrubber and low potential for visibility improvement, we are proposing
that existing controls represent BART for SO2 emissions from
the electric furnace. While we would prefer to set a numeric emission
limit in order to ensure that SO2 emissions from the
electric furnace do not increase in the future, such a limit is
impracticable because emissions from the electric furnace are
commingled with emissions from non-BART eligible units in the vent fume
stack. Therefore, consistent with 40 CFR 51.308(e)(1), we propose a
work practice standard prohibiting active aeration of the electric
furnace.
3. BART Analysis for NOX From Process Heaters
    NOX emissions from the FMMI smelter result from the
combustion of natural gas to heat process equipment. According to the
Documentation Report accompanying AirControlNet, the cost to retrofit
process heaters with low NOX burners, which can reduce
NOX emissions by 50 percent, is $2,200 per ton.\125\
Although this is not necessarily cost-prohibitive, there is relatively
little potential for visibility improvement from installation of any
NOX controls at FMMI. In particular, the maximum modeled
98th percentile visibility impact resulting from baseline
NOX emissions from FMMI is 0.11 dv.\126\ In addition, the