[Federal Register Volume 77, Number 181 (Tuesday, September 18, 2012)]
[Rules and Regulations]
[Pages 57863-57919]
[FR Doc No: 2012-20918]

Vol. 77

Tuesday,

No. 181

September 18, 2012

Part III

Environmental Protection Agency

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40 CFR Part 52

Approval and Promulgation of Implementation Plans; State of Montana;
State Implementation Plan and Regional Haze Federal Implementation
Plan; Final Rules

Federal Register / Vol. 77 , No. 181 / Tuesday, September 18, 2012 /
Rules and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2011-0851, FRL 9719-9]

Approval and Promulgation of Implementation Plans; State of
Montana; State Implementation Plan and Regional Haze Federal
Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: The Environmental Protection Agency (EPA) is promulgating a
Federal Implementation Plan (FIP) to address regional haze in the State
of Montana. EPA developed this FIP in response to the State's decision
in 2006 to not submit a regional haze State Implementation Plan (SIP)
revision. The FIP satisfies requirements of the Clean Air Act (CAA or
``the Act'') that require states, or EPA in promulgating a FIP, to
assure reasonable progress towards the national goal of preventing any
future and remedying any existing man-made impairment of visibility in
mandatory Class I areas. In addition, EPA is approving one of the
revisions to the Montana SIP submitted by the State of Montana through
the Montana Department of Environmental Quality on February 17, 2012,
specifically, the revision to the Montana Visibility Plan that includes
amendments to the ``Smoke Management'' section, which adds a reference
to Best Available Control Technology (BACT) as the visibility control
measure for open burning as currently administered through the State's
air quality permit program. This change was made to meet the
requirements of the Regional Haze Rule. EPA will act on the remaining
February 17, 2012 revisions in the State's submittal in a future
action.

DATES: This final rule is effective October 18, 2012.

ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-R08-OAR-2011-0851. All documents in the docket are listed on
the www.regulations.gov Web site. Although listed in the index, some
information is not publicly available, e.g., Confidential Business
Information (CBI) or other information whose disclosure is restricted
by statute. Certain other material, such as copyrighted material, is
not placed on the Internet and will be publicly available only in hard
copy form. Publicly available docket materials are available either
electronically through www.regulations.gov, or in hard copy at the Air
Program, Environmental Protection Agency (EPA), Region 8, 1595 Wynkoop
Street, Denver, Colorado 80202-1129. EPA requests that if at all
possible, you contact the individual listed in the FOR FURTHER
INFORMATION CONTACT section to view the hard copy of the docket. You
may view the hard copy of the docket Monday through Friday, 8 a.m. to 4
p.m., excluding Federal holidays.

FOR FURTHER INFORMATION CONTACT: Scott Jackson, Air Program, Mailcode
8P-AR, Environmental Protection Agency, Region 8, 1595 Wynkoop Street,
Denver, Colorado 80202-1129,<PHONE_NUMBER>, or<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Definitions

    For the purpose of this document, we are giving meaning to certain
words or initials as follows:
     The words or initials Act or CAA mean or refer to the
Clean Air Act, unless the context indicates otherwise.
     The initials A/F mean or refer to air-to-fuel.
     The initials ALM mean or refer to Ammonia Limiting Method
     The initials ARM mean or refer to Administrative Rule of
Montana.
     The initials ARP mean or refer to the acid rain program.
     The initials ARS mean or refer to Air Resources
Specialists.
     The initials ASOFA mean or refer to advanced separated
overfire air.
     The initials BACT mean or refer to Best Available Control
Technology.
     The initials BART mean or refer to Best Available Retrofit
Technology.
     The initials CAA mean or refer to the Clean Air Act.
     The initials CAM mean or refer to compliance assurance
monitoring.
     The initials CAMD mean or refer to EPA Clean Air Markets
Division.
     The initials CAMx mean or refer to Comprehensive Air
Quality Model.
     The initials CBI mean or refer to confidential business
information.
     The initials CCM mean or refer to EPA Control Cost Manual.
     The initials CCOFA mean or refer to close-coupled overfire
air system.
     The initials CDS mean or refer to circulating dry
scrubber.
     The initials CGA mean or refer to gas cylinder audit.
     The initials CELP mean or refer to Colstrip Energy Limited
Partnership.
     The initials CEMS mean or refer to continuous emissions
monitoring systems.
     The initials CEPCI mean or refer to Chemical Engineering
Plant Cost Index.
     The initials CFAC mean or refer to Columbia Falls Aluminum
Company.
     The initials CFB mean or refer to circulating fluidized
bed.
     The initials CKD mean or refer to cement kiln dust.
     The initials CMAQ mean or refer to Community Multi-Scale
Air Quality modeling system.
     The initials CPMS mean or refer to continuous parametric
monitoring system.
     The initials CO mean or refer to carbon monoxide.
     The initials CPI mean or refer to Consumer Price Index.
     The initials CRF mean or refer to Capital Recovery Factor.
     The initials CSAPR mean or refer to Cross-State Air
Pollution Rule.
     The initials DAA mean or refer to Dry Absorbent Addition.
     The initials DPCS mean or refer to digital process control
system.
     The initials D-R mean or refer to Dresser-Rand.
     The initials DSI mean or refer to dry sorbent injection.
     The initials EC mean or refer to elemental carbon.
     The initials EGU mean or refer to Electric Generating
Units.
     The words EPA, we, us or our mean or refer to the United
States Environmental Protection Agency.
     The initials ESP mean or refer to electrostatic
precipitator.
     The initials FCCU mean or refer to fluid catalytic
cracking unit.
     The initials FGD mean or refer to flue gas
desulfurization.
     The initials FGR mean or refer to flue gas recirculation.
     The initials FIP mean or refer to Federal Implementation
Plan.
     The initials FLMs mean or refer to Federal Land Managers.
     The initials HAR mean or refer to hydrated ash
reinjection.
     The initials HDSCR mean or refer to high-dust selective
catalytic reduction.
     The initials HC mean or refer to hydrocarbons.
     The initials gr/scf mean or refer to grains per standard
cubic foot.
     The initials IMPROVE mean or refer to Interagency
Monitoring of Protected Visual Environments monitoring network.
     The initials IPM mean or refer to Integrated Planning
Model.
     The initials IWAQM refer to Interagency Workgroup on Air
Quality Modeling.
     The initials LDSCR mean or refer to low-dust selective
catalytic reduction.
     The initials LEA mean or refer to low excess air.
     The initials LNBs mean or refer to low NOX
burners.

     The initials LSD mean or refer to lime spray drying.
     The initials LSFO mean or refer to limestone forced
oxidation.
     The initials LTS mean or refer to Long-Term Strategy.
     The initials MACT mean or refer to maximum achievable
control technology.
     The initials MATB mean or refer to Montanan's Against
Toxic Burning.
     The initials MDEQ mean or refer to Montana's Department of
Environmental Quality.
     The initials MDF mean or refer to medium density
fiberboard.
     The initials MISO mean or refer to Midwest Independent
Transmission System Operator.
     The initials MDU mean or refer to Montana-Dakota Utilities
Company.
     The initials MEL mean magnesium-enhanced lime.
     The initials MKF mean or refer to mid-kiln firing of solid
fuel.
     The words Montana and State mean the State of Montana.
     The initials MSCC mean or refer to Montana Sulphur and
Chemical Company.
     The initials NAAQS mean or refer to National Ambient Air
Quality Standards.
     The initials NC mean or refer to North Carolina.
     The initials ND mean or refer to North Dakota.
     The initials NEI mean or refer to National Emission
Inventory.
     The initials NESHAP mean or refer to National Emission
Standards for Hazardous Air Pollutants.
     The initials NH3 mean or refer to ammonia.
     The initials NOX mean or refer to nitrogen
oxides.
     The initials NP mean or refer to National Park.
     The initials NPS mean or refer to National Parks Service.
     The initials NSCR mean or refer to non-selective catalytic
reduction.
     The initials NSPS mean or refer to New Source Performance
Standards.
     The initials NWR mean or refer to National Wildlife
Reserve.
     The initials OMB mean or refer to the Office of Management
and Budget.
     The initials OC mean or refer to organic carbon.
     The initials OFA mean or refer to overfire air.
     The initials PC mean or refer to pulverized coal.
     The initials PH/PC mean or refer to preheater/precalciner.
     The initials PM mean or refer to particulate matter.
     The initials PM2.5 mean or refer to particulate matter
with an aerodynamic diameter of less than 2.5 micrometers (fine
particulate matter).
     The initials PM10 mean or refer to particulate matter with
an aerodynamic diameter of less than 10 micrometers (coarse particulate
matter).
     The initials PMCD mean or refer to particulate matter
control device.
     The initials ppb mean or refer to parts per billion.
     The initials ppm mean or refer to parts per million.
     The initials PRB mean or refer to Powder River Basin.
     The initials PSAT mean or refer to Particulate Matter
Source Apportionment Technology.
     The initials PSD mean or refer to Prevention of
Significant Deterioration.
     The fraction Q/D means quantity of emissions over
distance.
     The initials RAA mean or refer to relative accuracy audit.
     The initials RATA mean or refer to relative accuracy test
audit.
     The initials RAVI mean or refer to Reasonably Attributable
Visibility Impairment.
     The initials RICE mean or refer to Reciprocating Internal
Combustion Engines.
     The initials RMC mean or refer to Regional Modeling
Center.
     The initials ROFA mean or refer to rotating opposed fire
air.
     The initials RP mean or refer to Reasonable Progress.
     The initials RPG or RPGs mean or refer to Reasonable
Progress Goal(s).
     The initials RPOs mean or refer to regional planning
organizations.
     The initials RRI mean or refer to rich reagent injection.
     The initials RSCR mean or refer to regenerative selective
catalytic reduction.
     The initials SCOT mean or refer to Shell Claus Off-Gas
Treatment.
     The initials SCR mean or refer to selective catalytic
reduction.
     The initials SDA mean or refer to spray dryer absorbers.
     The initials SIP mean or refer to State Implementation
Plan.
     The initials SMOKE mean or refer to Sparse Matrix Operator
Kernel Emissions.
     The initials SNCR mean or refer to selective non-catalytic
reduction.
     The initials SO2 mean or refer to sulfur dioxide.
     The initials SOFA mean or refer to separated overfire air.
     The initials SRU mean or refer to sulfur recovery unit.
     The initials TAC mean or refer to Texas Administrative
Code.
     The initials TESCR mean or refer to tail-end selective
catalytic reduction.
     The initials TCEQ mean or refer to Texas Commission on
Environmental Quality.
     The initials tpy mean tons per year.
     The initials TSD mean or refer to Technical Support
Document.
     The initials URP mean or refer to Uniform Rate of
Progress.
     The initials USFWS mean or refer to U.S. Fish and Wildlife
Service.
     The initials VOC mean or refer to volatile organic
compounds.
     The initials WA mean or refer to Wilderness Area.
     The initials WEG mean or refer to WildEarth Guardians.
     The initials WEP mean or refer to Weighted Emissions
Potential.
     The initials WETA mean or refer to Western Environmental
Trade Association.
     The initials WRAP mean or refer to the Western Regional
Air Partnership.
     The initials YELP mean or refer to Yellowstone Energy
Limited Partnership.

Table of Contents

I. Background
II. Basis for Our Final Action
III. Final Action
IV. Issues Raised by Commenters and EPA's Responses
    A. Comments on Modeling
    B. General Comments on BART
    C. Comments on Cement Kilns
    D. Comments on Ash Grove
    E. Comments on Holcim
    F. Comments on CFAC
    G. Comments on Colstrip Units 1 and 2
    H. Comments on Corette
    I. Comments on Reasonable Progress and Long Term Strategy
    J. Comments on Colstrip 3 and 4
    K. Comments on Devon Energy
    L. Comments on Montana Dakota Utilities
    M. Comments on Montana Sulphur and Chemical Company
    N. Comments on Health, Ecosystem Benefits, Other Pollutants, and
Coal Ash
    O. General Comments Supporting Our Proposal or for Stricter
Controls
    P. General Comments That The Proposal Is Too Stringent
    Q. Comments on Visibility Improvement and Other Causes of Haze
    R. Comments on Cost, Economic Impact, Jobs and Price to
Consumers
    S. Comments About Other Forms of Energy
    T. Other Miscellaneous Comments
V. Changes From Proposed Rule and Reasons for the Changes
    A. Emission Limits for Corette
    B. Changes to 40 CFR 52.1396(c)(2)--Emission Limitations for
Cement Kilns:
    C. Change to 40 CFR 52.1396(d)--Compliance date:
    D. Change to 40 CFR 52.1396(e)(3)--CEMS for cement kilns:
    E. Change to 40 CFR 52.1396(e)(4)(ii)--Compliance determination
methods for SO2 and NOX at cement kilns:
    F. Change to 40 CFR 52.1396(f)(1) and (f)(2)--Compliance
determinations for

PM BART limits at EGUs and cement kilns:
    G. Change to 40 CFR 52.1396(f)(2)--Compliance determinations for
cement kiln PM BART limits:
    H. Change to 40 CFR 52.1396(h)(6)--Recordkeeping requirements
for cement kilns:
    I. Change to 40 CFR 52.1396(i)--Reporting:
    J. Change to 40 CFR 52.1396(i)(1) and (i)(2)--Reporting for CEMS
for SO2 and NOX:
    K. Changes to 40 CFR 52.1396 for Devon Energy, Blaine County
1 Compressor Station
VI. Statutory and Executive Order Reviews

I. Background

    We signed our notice of proposed rulemaking on March 20, 2012, and
it was published in the Federal Register on April 20, 2012. In that
notice, we proposed a FIP to address regional haze in the State of
Montana for the first implementation period (through 2018) including
determinations of Best Available Retrofit Technology (BART) for
specific sources subject to that requirement. 77 FR 23988. Montana did
not submit a SIP, knowing that as a consequence EPA would be required
to propose and finalize a FIP. A detailed explanation of the CAA's
visibility requirements and the Regional Haze Rule as it applies to
Montana was provided in the notice of proposed rulemaking and will not
be restated here. In that notice, we also proposed to approve a
revision to the Montana SIP submitted by the State of Montana through
the Montana Department of Environmental Quality on February 17, 2012.
The State's submittal contained revisions to the Montana Visibility
Plan that included amendments to the ``Smoke Management'' section,
which adds a reference to Best Available Control Technology (BACT) as
the visibility control measure for open burning as currently
administered through the State's air quality permit program. EPA's
rationale for proposing approval of the revisions to the Montana
Visibility Plan that included amendments to the ``Smoke Management''
section was described in detail in the proposal and will not be
restated here. We note that in the future, Montana retains the option
of submitting a SIP meeting the requirements of the Regional Haze Rule,
to replace the FIP.

II. Basis for Our Final Action

    We have fully considered all significant comments on our proposal,
and, except as noted in section V, below, have concluded that no other
changes from our proposal are warranted. Our action is based on an
evaluation of Montana's Visibility SIP submittal and our FIP against
the regional haze requirements at 40 CFR 51.300--51.309 and CAA
sections 169A and 169B. All general SIP requirements contained in CAA
section 110, other provisions of the CAA, and our regulations
applicable to this action were also evaluated. The purpose of this
action is to ensure compliance with these requirements. Our authority
for action on Montana's Visibility SIP submittal is based on CAA
section 110(k). Our authority to promulgate our FIP is based on CAA
section 110(c).

III. Final Action

    With this final action we are approving Montana's submittal
containing revisions to the ``Smoke Management'' section of Montana's
Visibility Plan that was submitted by the State through the Montana DEQ
on February 17, 2012. The SIP includes amendments to the ``Smoke
Management'' section, which adds a reference to BACT as the visibility
control measure for open burning as currently administered through the
State's air quality permit program as meeting the requirement of 40 CFR
308(d)(3)(v) to consider smoke management techniques for agricultural
and forestry management purposes including plans as they currently
exist within the state for these purposes. We are promulgating a FIP
for the remaining parts of the regional haze requirements. Table 1
shows the control technologies, associated cost, and emission
reductions for each source that is subject to the FIP.

                Table 1--Control Technologies, Cost, Emissions Reductions and Cost-Effectiveness
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                                                                                Annual NOX/SO2
                                                  Total capital       Total         emissions          Cost
            Source              Technology \1\      cost ($)       annualized       reductions     effectiveness
                                                                    cost ($)          (tpy)           ($/ton)
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Ash Grove Cement.............  LNB + SNCR......       1,191,632       2,238,893  1,088 NOX......           2,058
Holcim, Inc..................  SNCR............       1,312,800         650,399  556 NOX........           1,170
Colstrip Unit 1..............  SOFA + SNCR.....      13,380,673       3,278,964  2,097 NOX......           1,564
Colstrip Unit 2..............  Lime Injection +      28,000,000       4,093,200  4,486 SO2......             912
                                Additional
                                Scrubber Vessel.
Colstrip Unit 2..............  SOFA + SNCR.....      13,380,673       3,256,127  2,072 NOX......           1,571
Colstrip Unit 2..............  Lime Injection +      28,000,000       4,093,200  4,129 SO2......             991
                                Additional
                                Scrubber Vessel.
Devon Energy, Blaine County    NSCR............              --         105,000  335 NOX........             282
 1 Compressor
 Station, Engine 1.
Devon Energy, Blaine County    NSCR............              --         105,000  335 NOX........             282
 1 Compressor
 Station, Engine 2.
                              ----------------------------------------------------------------------------------
    Cumulative Total Annual    ................  ..............      13,727,583
     Cost.
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-- Total Capital Cost was not calculated.
\1\ The technology listed is the technology evaluated as BART, but sources can choose to use another technology
  or combination of technologies to meet established emission limits. Also where additional control technologies
  are not required, existing controls may still be necessary to meet established emission limits.

IV. Issues Raised by Commenters and EPA's Responses

    This action addresses comments on the Montana Regional Haze FIP.
The publication of EPA's proposed rule on April 20, 2012 resulted in a
60-day public comment period that ended on June 19, 2012. We held four
public hearings for this proposal. Two hearings were held in Helena,
Montana on Tuesday, May 1, 2012 and two hearings were held in Billings,
Montana on

Wednesday, May 2, 2012. During the public comment period we received
numerous written comments from individual citizens, members of various
organizations, and also from Ash Grove Cement (Ash Grove), Columbia
Falls Aluminum Corporation (CFAC), EarthJustice, the U.S. Fish and
Wildlife Service (USFWS), Holcim Inc. (Holcim), Montana Dakota
Utilities (MDU), Montana Sulphur and Chemical Company, the National
Parks Service (NPS), the owners of Colstrip Units 1-4, the State of
Montana, and WildEarth Guardians (WEG). We have reviewed the comments
and provided our responses below. Transcripts from the public hearings
and full copies of the comment letters are available in the docket for
review.

A. Comments on Modeling

    Comment: PPL and others stated that the proposed BART at Colstrip 1
and 2 for both NOX and SO2 would result in no
reasonably anticipated visibility benefit, even assuming that EPA's
emissions reduction estimates and modeling are correct. In one specific
comment, the commenter stated:

    A projected 0.066 dv is not a visibility improvement that `may
reasonably be anticipated to result from the use' of additional
scrubber vessels at Colstrip Units 1 and 2. 42 U.S.C. 7491(g)(2).
Such an insignificant projected visibility change is beyond the
modeling capability of the CALPUFF model version EPA used and is far
below the threshold for human perceptibility.

    Response: We disagree that any controls required by our action must
demonstrate a perceptible visibility improvement. In a situation where
the installation of BART may not result in a perceptible improvement in
visibility, the visibility benefit may still be significant. The
Regional Haze Rule states:

even though the visibility improvement from an individual source may
not be perceptible, it should still be considered in setting BART
because the contribution to haze may be significant relative to
other source contributions in the Class I area. Failing to consider
less-than-perceptible contributions to visibility impairment would
ignore the CAA's intent to have BART requirements apply to sources
that contribute to, as well as cause, such impairment.

70 FR 39129.
    Visibility impacts below the thresholds of perceptibility cannot be
ignored because regional haze is produced by a multitude of sources and
activities which are located across a broad geographic area. As stated
in our proposal, with respect to Colstrip 1 and 2, we weighed the
relatively low costs for lime injection with the additional scrubber
vessel against the anticipated visibility impacts and determined that
the cost was justified by the visibility improvement. Similarly, we
weighed the relatively low cost of separated overfire air (SOFA) +
selective noncatalytic reduction (SNCR) against the anticipated
visibility benefit and determined that the cost was justified by the
visibility benefit.
    We respond to the modeling capabilities of CALPUFF in a response to
a later comment.
    Comment: A commenter asserted that EPA's modeling assumes constant
levels of ammonia and failed to consider monitoring data showing that
ammonia levels are lower during the winter months.
    Response: EPA recognizes that there can be seasonal variability in
ambient ammonia concentrations and that it is preferable to use ambient
ammonia measurements when such data are available rather than using
default background ammonia concentrations. Ammonia monitoring data is
not available in Montana, however, ammonia monitoring data is available
in western North Dakota at the Beulah monitoring site. Theodore
Roosevelt NP, located in western North Dakota, is impacted by Montana
BART sources and EPA determined that it would be more appropriate to
use the North Dakota ammonia monitoring data instead of using CALPUFF
default ammonia concentrations. Therefore EPA used monthly average
measured ammonia concentrations shown in Table 2 that were measured by
North Dakota at their Beulah monitoring site.\1\ The monthly average
ammonia concentrations values were derived from data collected during
years 2001-2002 and the ambient data were filtered to eliminate data
from wind directions associated with sources causing a local bias.
North Dakota concluded in its regional haze modeling analysis that
these monthly average ammonia values are generally representative of
background ammonia concentrations in western North Dakota. As a result,
we did not assume a constant level of ammonia as asserted by the
commenter, and we did represent seasonal variability in ammonia
concentrations.
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    \1\ Protocol for BART-Related Visibility Impairment Modeling
Analyses in North Dakota (Final), North Dakota Department of Health,
Division of Air Quality, 1200 Missouri Avenue Bismarck, ND (Nov
2005), p 32-33.
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    Additionally, EPA used the POSTUTIL \2\ program with the Ammonia
Limiting Method (ALM) to post-process the CALPUFF output to correct the
assumption of constant ammonia availability in the model. The CALPUFF
model represents multiple plumes that can overlap. The default model
approach assumes that background ammonia is fully available to form
nitrate in each plume. The ALM method corrects this assumption by
partitioning the ammonia between overlapping plumes. Therefore, EPA has
fully accounted for non-constant ammonia levels by using monthly
measured background ammonia and by using the ALM in the analysis of
CALPUFF model results.
---------------------------------------------------------------------------

    \2\ POSTUTIL is a part of the suite of programs associated with
the CALPUFF modeling system and is used to repartition ammonia in
overlapping puffs. The model is available at: http://www.src.com/calpuff/calpuff1.htm.

           Table 2--Monthly Ammonia Background Concentrations
------------------------------------------------------------------------
                                                                 Value
                            Month                                (ppb)
------------------------------------------------------------------------
Jan..........................................................       1.22
Feb..........................................................       1.23
Mar..........................................................       1.60
Apr..........................................................       1.94
May..........................................................       2.29
Jun..........................................................       1.63
------------------------------------------------------------------------
Jul..........................................................       1.65
Aug..........................................................       1.69
Sep..........................................................       0.98
Oct..........................................................       1.04
Nov..........................................................       1.37
Dec..........................................................       1.06
------------------------------------------------------------------------

    Comment: A commenter stated that EPA failed to acknowledge
uncertainty in the CALPUFF model at short distances, and the commenter
further argues that model uncertainty increases at distances greater
than 200 km and has a tendency to over predict impacts at greater
distances.
    Response: The Interagency Workgroup on Air Quality Modeling (IWAQM)
Phase 2 report (EPA, 1998) \3\ reviewed model performance evaluations
of CALPUFF as a function of distance from the source and concluded
that:
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    \3\ Interagency Workgroup on Air Quality Modeling (IWAQM) Phase
2 Report and Recommendations for Long-Range Transport Impacts. EPA-
454/R-98-019. U.S. Environmental Protection Agency. Research
Triangle Park, NC (``IWAQM Phase II Report'') (1998), p 18.

    Based on the tracer comparison results presented in Section 4.6,
it appears that CALPUFF provides reasonable correspondence with
observations for transport distances of over 100 km. Most of these
comparisons involved concentration values averaged over 5 to 12
hours. The CAPTEX comparisons, which involved comparisons at
receptors that were 300 km to 1000 km from the release, suggest that
CALPUFF can overestimate surface concentrations by a factor of 3 to
4. Use of

the puff splitting option in CALPUFF might have improved these
comparisons, but there are serious conceptual concerns with the use
of puff dispersion for very long-range transport (300 km and
beyond). As the puffs enlarge due to dispersion, it becomes
problematic to characterize the transport by a single wind vector,
as significant wind direction shear may well exist over the puff
dimensions. With the above thoughts in mind, IWAQM recommends use of
CALPUFF for transport distances of order 200 km and less. Use of
CALPUFF for characterizing transport beyond 200 to 300 km should be
---------------------------------------------------------------------------
done cautiously with an awareness of the likely problems involved.

    Therefore, we modeled Class I areas within 300 km of each BART
sources but did not model impacts at distances exceeding 300 km.
    EPA has acknowledged that there is uncertainty in the CALPUFF model
predicted visibility impacts. However, the CALPUFF model can both
underpredict and overpredict visibility impacts. For example, in a
presentation for the 2010 annual Community Modeling and Analysis System
conference, Anderson et al. (2010) \4\ found that the CALPUFF model
frequently predicted lower nitrate concentrations compared to the CAMx
photochemical grid model which has a much more rigorous treatment of
photochemical reactions. EPA recognized the uncertainty in the CALPUFF
modeling results when EPA made the decision, in the final BART
Guidelines, to recommend that the model be used to estimate the 98th
percentile visibility impairment rather than the highest daily impact
value. While recognizing the limitations of the CALPUFF model in the
BART Guidelines Preamble, EPA concluded that, for the specific purposes
of the Regional Haze Rule's BART provisions, CALPUFF is sufficiently
reliable to inform the decision making process. The Preamble states:
---------------------------------------------------------------------------

    \4\ Anderson, B., K. Baker, R. Morris, C. Emery, A. Hawkins, E.
Snyder ``Proof-of-Concept Evaluation of Use of Photochemical Grid
Model Source Apportionment Techniques for Prevention of Significant
Deterioration of Air Quality Analysis Requirements'' Presentation
for Community Modeling and Analysis System (CMAS) 2010 Annual
Conference, (October 11-15, 2010) can be found at http://www.cmascenter.org/conference/2010/agenda.cfm.

    Because of the scale of the predicted impacts from these
sources, CALPUFF is an appropriate or a reasonable application to
determine whether such a facility can reasonably be anticipated to
cause or contribute to any impairment of visibility. In other words,
to find that a source with a predicted maximum impact greater than 2
or 3 deciviews meets the contribution threshold adopted by the
States does not require the degree of certainty in the results of
the model that might be required for other regulatory purposes. In
the unlikely case that a State were to find that a 750 MW power
plant's predicted contribution to visibility impairment is within a
very narrow range between exemption from or being subject to BART,
the State can work with EPA and the FLM to evaluate the CALPUFF
results in combination with information derived from other
appropriate techniques for estimating visibility impacts to inform
the BART applicability determination. Similarly for other types of
BART eligible sources, States can work with the EPA and FLM to
determine appropriate methods for assessing a single source's
---------------------------------------------------------------------------
impacts on visibility.

77 FR 39123.
    Therefore, given that the IWAQM guidance provides for the use of
the CALPUFF model at receptor distances of up to 200 to 300 km, and
given that EPA has already addressed uncertainty in the CALPUFF model,
we believe it is reasonable to use CALPUFF to evaluate visibility
impacts up to 300 km.
    Comment: A commenter stated that the CALPUFF model cannot
accurately predict visibility changes at the levels EPA predicted for
Holcim using indirect firing alone (0.125 deciview) or even for the
additional improvement from the combination of SNCR + indirect firing
as compared to SNCR alone. The commenter believes that the EPA
predicted visibility improvement of 0.424 deciview for the combination
of SNCR + indirect firing is within the uncertainty range of the
CALPUFF model and cannot reliably predict visibility improvements.
    Response: We disagree. EPA has previously addressed the issue of
uncertainty in the CALPUFF model. EPA recognized the uncertainty in the
CALPUFF modeling results when EPA made the decision in the final BART
Guideline to recommend that the model be used to estimate the 98th
percentile visibility impairment rather than the highest daily impact
value. While recognizing the limitations of the CALPUFF model in the
Preamble, EPA concluded that, for the specific purposes of the Regional
Haze Rule's BART provisions, CALPUFF is sufficiently reliable to inform
the decision making process. 70 FR 39123. We continue to maintain that
it is appropriate to use CALPUFF for BART modeling for Holcim and other
Montana BART sources.
    Comment: Some commenters stated that we should have modeled impacts
to additional Class I areas. Some commenters stated that EPA should
have modeled visibility impacts on Class I areas at a distance of up to
500 km from the BART source and some commenters specified certain Class
I areas that they thought should be included in the modeling for a
particular source.
    Some commenters stated that the Western Regional Air Partnership
(WRAP) subject to BART modeling indicated impacts from BART sources to
additional Class I areas that we did not assess. One commenter stated
that when assessing the impacts from the Big Stone I facility in the
South Dakota SIP, EPA evaluated visibility as far away as Badlands
National Park (NP), 470 km, Theodore Roosevelt NP, 555 km, and Boundary
Waters Wilderness Area (WA) and Voyageurs NP, 431 and 438 km,
respectively, and the commenter stated that, EPA should evaluate
visibility impacts at more distant Class I areas for the Montana FIP.
    Response: We modeled all Class I areas within 300 km of the BART
source. As discussed in a response to a previous comment, the IWAQM
Phase 2 report concluded that CALPUFF can overestimate surface
concentrations at distances of 300 to 1,000 km by a factor of 3 to 4.
Therefore, IWAQM recommends use of CALPUFF for transport distances of
approximately 200 km or less. Use of CALPUFF for characterizing
transport beyond 200 to 300 km should be done cautiously with an
awareness of the likely problems involved. Therefore, we modeled Class
I areas within 300 km of each BART source. We did not model impacts at
distances exceeding 300 km.
    In the case of the Big Stone I facility in South Dakota, there were
no Class I areas within a distance of 300 km of the source. Therefore,
the State and the facility agreed in their modeling protocol to
evaluate visibility impacts at more distant sources by using a non-
regulatory option in CALPUFF called ``puff splitting''. As discussed in
the IWAQM Guidance,\5\ the use of the puff splitting option in CALPUFF
might improve model performance at long distances, but there are also
serious conceptual concerns with the use puff splitting to represent
puff dispersion for very long-range transport at distances of more than
300 km. EPA concurred with South Dakota on this approach for Big Stone
I because there were no Class I areas within 300 km of the source, and
EPA approved the South Dakota SIP using these modeling results. In the
case of Montana, there are several Class I areas less than 300 km from
each BART source, and EPA based its analysis on CALPUFF visibility
model results for these areas.
---------------------------------------------------------------------------

    \5\ IWAQM Phase 2 report, p. 27.
---------------------------------------------------------------------------

    EPA did not use the non-regulatory puff splitting option in CALPUFF
to model more distant sources because of

the greater uncertainty in model results at distances of more than 300
km, as we have explained in previous responses.
    While WRAP performed CALPUFF modeling at Class I areas more distant
than 300 km from Colstrip, WRAP also recognized the larger uncertainty
in the model results for distances greater than 300 km. and included
the following caveat in their modeling protocol:

    Relevant guidance suggests that the CALPUFF model is generally
applicable at distances from 50 km to 300 km downwind and may be
used for distance less than 50 km when complex flows exist on a case
by case basis. [citation omitted] Class I areas in the west
generally are located in complex terrain resulting in complex flows.
Consequently, the BART screening modeling conducted by the RMC will
include results for potential BART eligible sources that reside
within 50 km of a Class I area. The WRAP RMC BART screening modeling
may also apply CALPUFF to downwind distances greater than 300 km.
When providing results to the States, the downwind distance between
the BART source and the Class I area will be included, and a
recommendation from the RMC as to the utility of applying the
results for Class I areas less than 50 km and greater than 300 km
from the source. The individual States will need to make their own
regulatory assessment of the applicability of the model results at
those distances less than 50 km and greater than 300 km.\6\
---------------------------------------------------------------------------

    \6\ CALMET/CALPUFF Protocol for BART Exemption Screening
Analysis for Class I areas in the Western United States Available at
http://pah.cert.ucr.edu/aqm/308/bart/WRAP_RMC_BART_Protocol_Aug15_2006.pdf.

    It also should be noted that WRAP found smaller visibility impacts
at the distances of more than 300 km compared to Class I areas at
distances of less than 300 km.\7\ The BART Guidelines explain that if
the highest modeled effects are observed at the nearest Class I area,
it may not be necessary to model other Class I areas. The BART
Guidelines state:
---------------------------------------------------------------------------

    \7\ Summary of WRAP RMC BART Modeling for Montana, Draft
5 May 30, 2007. More information can be found at http://pah.cert.ucr.edu/aqm/308/bart.shtml.

    One important element of the protocol is in establishing the
receptors that will be used in the model. The receptors that you use
should be located in the nearest Class I area with sufficient
density to identify the likely visibility effects of the source. For
other Class I areas in relatively close proximity to a BART-eligible
source, you may model a few strategic receptors to determine whether
effects at those areas may be greater than at the nearest Class I
area. For example, you might choose to locate receptors at these
areas at the closest point to the source, at the highest and lowest
elevation in the Class I area, at the IMPROVE monitor, and at the
approximate expected plume release height. If the highest modeled
effects are observed at the nearest Class I area, you may choose not
to analyze the other Class I areas any further as additional
---------------------------------------------------------------------------
analyses might be unwarranted.

70 FR 39170.
    Comment: Commenters stated that EPA should have added the
visibility impacts at each Class I area to assess cumulative visibility
impacts.
    Response: Contrary to the commenter's assertion, we did assess
cumulative visibility impacts. In our analysis of visibility impacts,
we considered the visibility improvement at all Class I areas within
300 km of the subject BART unit. For example, in our analysis of BART
control options for Corette, we considered the visibility improvement
at all Class I areas within 300 km (Gates of the Mountains WA, North
Absaroka WA, Red Rock Lakes WA, Teton WA, UL Bend WA, Washakie WA, and
Yellowstone NP). 77 FR 24042 and 77 FR 24046. In our proposal, for each
of the BART sources we assessed the visibility improvement at each
Class I area within 300 km of the source associated with the controls
under consideration, as well as the number of days with a greater than
0.5 deciview impact at each of these Class I areas. Therefore, our
proposed rule did not ignore the visibility improvement that would be
achieved at areas other than the most impacted Class I area, and we
disagree with the assertions that we did not consider the impacts at
multiple Class I areas. We did, however, in the proposed rule focus on
the visibility benefits at those Class I areas with the most meaningful
visibility impacts in determining whether NOX or
SO2 controls should be determined to be BART. We took a
similar approach for all the Montana BART units. We did not ignore the
visibility benefits at the other Class I areas but did not consider the
benefits sufficient to warrant a change in our determination as to the
appropriate level of control.
    Comment: USFWS stated that for the three SO2 control
alternatives, EPA made judgments on cost per deciview based on only the
most impacted Class I area, Washakie WA and that USFWS continued to
believe that it is appropriate to consider both the degree of
visibility improvement in a given Class I area as well as the
cumulative effects of improving visibility across all of the Class I
areas affected. USFWS stated that it does not make sense to use the
same metric to evaluate the effects of reducing emissions from a BART
source that impacts only one Class I area as for a BART source that
impacts multiple Class I areas and that it does not make sense to
evaluate impacts at one Class I area, while ignoring others that are
similarly significantly impaired. USFWS stated that if emissions from
Corette are reduced, the benefits will be spread well beyond only the
most impacted Class I area, and this must be accounted for. USFWS
stated that, in the context of the multiple Class I areas that are
affected by Corette, the Lime Spray Dryer (LSD) SO2 control
alternative, the cumulative Class I area impact is $12.7 million per
deciview of visibility improvement and costs $4,981 per ton of
SO2 removed USFWS stated that LSD should be considered as
being a viable candidate for BART for Corette. USFWS made similar
comments regarding NOX controls for Corette.
    Response: We disagree. In our analysis of visibility impacts, we
considered the visibility improvement at all Class I areas within 300
km of the subject BART unit. As explained in the response to the
previous comment, in our analysis of BART control options for Corette,
we considered the visibility improvement at all Class I areas within
300 km. In our proposal, for each of the BART sources we assessed the
visibility improvement at each Class I area within 300 km of the source
associated with the controls under consideration, as well as the number
of days with a greater than 0.5 deciview impact at each of these Class
I areas. Therefore, our proposed rule did not ignore the visibility
improvement that would be achieved at areas other than the most
impacted Class I area, and we disagree with the assertions that we did
not consider the impacts at multiple Class I areas. We did, however, in
the proposed rule focus on the visibility benefits at those Class I
areas with the most meaningful visibility impacts in determining
whether NOX or SO2 controls should be determined
to be BART. We did not ignore the visibility benefits at the other
Class I areas but did not consider the benefits sufficient to warrant a
change in our determination as to the appropriate level of control. As
we explained in other responses, we did not use the $/deciview ratio as
a basis for our decision.
    Comment: EarthJustice's consultant Air Resources Specialists (ARS)
performed additional analysis on possible visibility benefits of SCR at
Colstrip Units 1 and 2 combined with the benefits of BART controls on
SO2 emissions. The commenter stated that the ARS analysis
``demonstrates that EPA's analysis of visibility benefits of selective
catalytic reduction (SCR) controls is incomplete and inadequate.'' The
commenter also stated, ``the evidence demonstrates that with SCR and
SO2 controls, the visibility impairment at UL Bend WA and
Theodore Roosevelt NP attributable to

Colstrip would be virtually eliminated, the very goal of the CAA haze
requirements.''
    The commenter also stated that when SCR + SOFA is coupled with a
dry scrubber/baghouse, it is likely that Corette would no longer have
any noticeable impact on haze in any Class I area, and this result
complies with the Congressional directive to eliminate haze in Class I
areas.
    Response: We disagree that our analysis was incomplete or
inadequate. We analyzed visibility benefits for both SO2 and
NOX emissions reductions following procedures established in
the BART Guidelines, and we proposed emissions reductions consistent
with the five factor analysis. The Regional Haze Rule has a goal that
anthropogenic visibility impairment be eliminated by 2064; however, it
does not require that all anthropogenic contributions to visibility
impacts be fully eliminated in the near term, nor is that the goal of
the BART element of the Regional Haze program. 40 CFR 51.308
(e)(1)(ii)(A) requires that EPA consider the cost of compliance; the
energy and nonair quality environmental impacts; any pollution control
equipment in use at the source; the remaining useful life of the
source; and the degree of improvement which may be reasonably
anticipated to result from the use of such technology. Visibility
improvement is only one of the five factors that are required to be
considered. Our proposed BART controls achieve significant reductions
in contributions to visibility impairment while also considering other
components of the five factor analysis.
    Comment: EarthJustice stated that, ``ARS concluded that the
incremental benefit of SCR compared to SNCR at Colstrip Units 1 and 2
is larger when viewed in combination with the SO2 emission
controls at either emission rate.''
    Response: ARS estimated the relative improvement in SCR compared to
SNCR for the case with baseline SO2 emissions and for the
case with our proposed BART SO2 emissions. The ARS analysis
showed that the incremental improvement in SCR compared to SNCR was
almost identical for the 98% worst days regardless of the level of
SO2 emissions used. For example, in EPA's analysis the
incremental improvement of SCR over SNCR for Theodore Roosevelt NP was
0.27, 0.23, and 0.28 deciview, respectively, for 2006, 2007 and 2008.
The ARS analysis found incremental improvements of 0.28, 0.26, and 0.28
deciview, respectively, for 2006, 2007 and 2008. Moreover, ARS did not
perform additional CALPUFF simulations for this analysis, but only
combined estimates of extinction contributions from different CALPUFF
simulations.
    Comment: EarthJustice stated that that we aggregated Colstrip Units
1 and 2 for assessing visibility benefits of SNCR, but arbitrarily kept
our assessment of benefits of SCR segregated by unit.
    Response: We disagree. Modeling was performed in the same manner
for SCR as for SNCR. The modeling protocol, results, and final report
were available in the docket. Our evaluation of the visibility benefits
was made in consideration of all of the modeling results, which
includes a visibility improvement assessment for application of SCR at
Colstrip Units 1 and 2 individually, as well as an assessment of the
total visibility benefit from application of SCR at both units
collectively.
    Comment: A commenter stated that we failed to examine the
collective visibility benefit of SCR in combination with SO2
upgrades at Colstrip Units 1 and 2.
    Response: We examined the individual benefits of NOX and
SO2 controls to be able to assess the difference between
pollutant-specific control options. Our evaluation of the visibility
benefits was made in consideration of all of the modeling results.
    Comment: EarthJustice stated that their contractor (ARS) performed
AERMOD simulations to evaluate the impacts of Colstrip SO2
emissions relative to the 1-hour average SO2 National
Ambient Air Quality Standard (NAAQS) and reported modeled violations of
the SO2 NAAQS.
    Response: EPA will address compliance with the 1-hour average
SO2 NAAQS separately from Regional Haze requirements. It is
beyond the scope of this rulemaking. It will be addressed by EPA at a
later date.
    Comment: Holcim commented that EPA discarded all prior modeling and
developed a new modeling analysis in 2011. Holcim stated that EPA did
not explain why it used a new modeling analysis and that EPA's BART
conclusions are therefore based on modeling that is not transparent and
not available for review.
    Response: We disagree. As we explained in our proposal, we used
CALPUFF modeling to evaluate emissions control scenarios that were
consistent with the application of control scenarios for the Montana
sources that were subject to BART. We did this because we were unable
to obtain the modeling files from some of the sources and we wanted
each source to be modeled consistently. The modeling protocol, final
report, and all related files were available for review in the docket.
    Comment: The Western Environmental Trade Organization (WETA)
commented that the EPA recently approved the SIP for regional haze
developed by the State of North Dakota. WETA explained that the North
Dakota plan relied on extensive modeling that demonstrated emissions
control technology installations at certain facilities would result in
insignificant improvement in visibility. WETA requested that the EPA
develop a visibility plan for Montana that offers the same flexibility
and cost-effective standards included in North Dakota's plan.
    Response: WETA did not explain what flexibility it was seeking;
therefore, we are not able to evaluate whether such flexibility could
be accommodated. To the extent that WETA is stating that our proposed
requirements are not cost-effective, we disagree. To the extent that
WETA is stating that we are being inconsistent with decisions we made
for regional haze in North Dakota, we disagree. We have responded to
more specific comments on the cost-effectiveness of controls elsewhere.
    Comment: The commenter stated that EPA's proposed BART
determinations for Colstrip Units 1& 2 are erroneous because EPA's
modeling failed to include actual air quality measurements, including
visual quality measurements, in its inputs to its regional haze model.
The commenter further stated that real air quality data for Class I
areas is critical to determining what the degree of visibility
improvement may be in a given Class I area.
    Response: EPA used ambient monitoring data to evaluate the CMAQ and
CAMx grid model simulations that were used for modeling the uniform
rate of progress toward natural visibility conditions. However, the
commenter appears to be referring specifically to the CALPUFF model
simulations used to evaluate visibility impacts of BART sources. The
BART Guidelines require that visibility impacts from BART sources be
evaluated in comparison to natural visibility conditions. The
procedures used to estimate natural visibility conditions are described
in the ``Guidance for Estimating Natural Visibility Conditions Under
the Regional Haze Rule.'' \8\ It would be

inappropriate to use ambient monitoring data for current degraded
visibility conditions in the evaluation of BART source visibility
impacts. EPA previously considered and responded to the comment that
current visibility conditions should be used in BART source evaluations
in 40 CFR part 51, appendix Y, promulgated at 70 FR 39104. EPA
considered the approach of assessing a BART-eligible source's impacts
on visibility by using current or near-term future conditions, and EPA
determined that BART visibility impacts should be evaluated in
comparison to natural background visibility. In the final rulemaking
EPA wrote:
---------------------------------------------------------------------------

    \8\ Guidance for Estimating Natural Visibility Conditions Under
the Regional Haze Rule, U.S. Environmental Protection Agency,
September 2003. Can be found at: http://www.epa.gov/ttncaaa1/t1/memoranda/rh_envcurhr_gd.pdf.

    Using existing conditions as the baseline for single source
visibility impact determinations would create the following paradox:
The dirtier the existing air, the less likely it would be that any
control is required. This is true because of the nonlinear nature of
visibility impairment. In other words, as a Class I area becomes
more polluted, any individual source's contribution to changes in
impairment becomes geometrically less. Therefore the more polluted
the Class I area would become, the less control would seem to be
needed from an individual source. We agree that this kind of
calculation would essentially raise the ``cause or contribute''
applicability threshold to a level that would never allow enough
emission control to significantly improve visibility. Such a reading
would render the visibility provisions meaningless, as EPA and the
States would be prevented from assuring ``reasonable progress'' and
fulfilling the statutorily-defined goals of the visibility program.
Conversely, measuring improvement against clean conditions would
---------------------------------------------------------------------------
ensure reasonable progress toward those clean conditions.

70 FR 39124.
    Therefore, EPA correctly used estimates of natural visibility
conditions in our evaluation of BART source visibility impacts, and we
disagree with the comment that we failed to appropriately use air
quality data at Class I areas.
    Comment: EarthJustice stated that they do not agree with EPA's
approach to use the fifth factor in determining the degree of
visibility improvement from emissions control technologies where EPA
adds an additional incremental benefit factor with an apparent but
unstated threshold for improvement sufficiency that is contrary to the
purpose and direction of the CAA.
    Response: We disagree that we only evaluated visibility benefit on
an incremental basis and that we used a threshold for improvement
sufficiency. In the proposed FIP, we included tables showing the
visibility improvement for control options as compared to baseline
conditions. Incremental improvement can be easily calculated from the
data in the tables, however, we did not calculate this separately for
each option. In addition, our modeling protocol, modeling report and
tables of results were included in the docket.
    Comment: Commenters stated that we used incorrect baselines for
modeling impacts from sources at Corette and Colstrip.
    Response: We explain our rationale for the chosen baseline periods
in responses to other comments.

B. General Comments on BART

    Comments: Montana Department of Environmental Quality (MDEQ) stated
that EPA should have used a dollar-per-deciview ($/deciview) metric
rather than the $/ton metric to evaluate BART and reasonable progress.
MDEQ argued that the use of deciviews is consistent with the Regional
Haze Rule, which expresses Reasonable Progress Goals (RPGs), baseline
visibility, current visibility conditions and natural conditions in
deciviews. MDEQ also referenced both the BART Guidance and the
Reasonable Progress Guidance to support this argument.
    The NPS stated that one of the options suggested by the BART
Guidelines to evaluate cost-effectiveness is cost/deciview and that the
NPS believes that visibility improvement must be a critical factor in
any program designed to improve visibility. The NPS stated that
compared to the typical control cost analysis in which estimates fall
into the range of $2,000-$10,000 per ton of pollutant removed, spending
millions of dollars per deciview to improve visibility may appear
extraordinarily expensive, but that the NPS compilation of BART
analyses across the United States reveals that the average cost per
deciview proposed by either a state or a BART source is $14-$18
million, with a maximum of $51 million per deciview proposed by South
Dakota at the Big Stone I power plant. The NPS noted that even though
it has no Class I areas, Nebraska Department of Environmental Quality
has chosen $40 million/deciview as a cost criterion, which is also
above the national average. The NPS compared its estimates for annual
cost of adding SOFA + SCR to EPA's estimates for visibility impacts and
stated that the cost-effectiveness of adding SOFA + SCR to improve
visibility at the five Class I areas modeled by EPA is less than $10
million/deciview and significantly less than the $14-$18 million/
deciview national average of BART proposals and determinations.
    Response: For BART, the BART Guidelines require that cost
effectiveness be calculated in terms of annualized dollars per ton of
pollutant removed, or $/ton. 70 FR 39167. MDEQ and the NPS are correct
in that the BART Guidelines allows for the $/deciview ratio as an
additional cost effectiveness metric that can be employed along with $/
ton for use in a BART evaluation. However, the use of this metric
further implies that additional thresholds or notions of acceptability,
separate from the $/ton metric, would need to be developed for BART
determinations. We have not used this metric for BART purposes because
(1) It is unnecessary in judging the cost effectiveness of BART, (2) it
complicates the BART analysis, and (3) it is difficult to judge. The $/
deciview metric has not been widely used and is not well-understood as
a comparative tool. In our experience, $/deciview values tend to be
very large because the metric is based on impacts at one Class I area
on one day and does not take into account the number of affected Class
I areas or the number of days of improvement that result from
controlling emissions. In addition, the use of the $/deciview suggests
a level of precision in the CALPUFF model that may not be warranted. As
a result, the $/deciview can be misleading. We conclude that it is
sufficient to analyze the cost effectiveness of potential BART controls
using $/ton, in conjunction with an assessment of the modeled
visibility benefits of the BART control. Within the context of
reasonable progress, the Guidance for Setting Reasonable Progress Goals
Under the Regional Haze Program, states that ``[y]ou should evaluate
both average and incremental costs.'' \9\ This is consistent with the
approach under BART. As commenters note, the guidance then stated that
``simple cost effectiveness estimates based on a dollar-per-ton
calculation may not be as meaningful as a dollar-per-deciview
calculation, especially if the strategies reduce different groups of
pollutants.'' However, the guidance makes this statement on the basis
that ``different pollutants differently impact visibility impairment.''
That is, for example, a one ton reduction in SO2 would have
a greater visibility benefit than a one ton reduction of coarse mass.
As only SO2 and NOX controls were evaluated for
the reasonable progress point sources, the use of the $/deciview is not
particularly

relevant or informative. In addition, we did not use the $/deciview
metric for our evaluation of reasonable progress controls for largely
the same reasons as stated above for BART controls.
---------------------------------------------------------------------------

    \9\ Guidance for Setting Reasonable Progress Goals Under the
Regional Haze Program, U.S. Environmental Protection Agency, June 1,
2007, p.5-2.
---------------------------------------------------------------------------

    Comment: The NPS stated that we used inconsistent criteria in
selecting BART controls.
    Response: We disagree. As explained later, pursuant to 40 CFR
51.308(e)(1)(ii)(A) we considered the following five factors in our
analysis: The cost of compliance; the energy and nonair quality
environmental impacts; any pollution control equipment in use at the
source; the remaining useful life of the source; and the degree of
improvement which may be reasonably anticipated to result from the use
of such technology. The Regional Haze Rule defines BART as the best
system of continuous emission control technology available and
associated emission reductions achievable, as determined through an
analysis of these five factors. The NPS is correct in that the BART
Guidelines allows for the $/deciview ratio as an additional cost
effectiveness metric that can be employed along with $/ton for use in a
BART evaluation of the five statutory factors. 70 FR 39126 to 70 FR
39127. While the Regional Haze Rule may not prevent us from
establishing a bright line for some of the factors such as cost-
effectiveness and visibility, we are not required to do so, and have
not done so for this action as the cost and visibility factors are both
weighed in making control decisions. Also, while the BART Guidelines
allows for the $/deciview ratio as an additional cost effectiveness
metric that can be employed along with $/ton for use in a BART
evaluation, we have not used this metric in our evaluation. As
explained in our determinations for each source, the cost effectiveness
of controls on a dollar per ton basis and the visibility benefit of
those controls were the two factors that had the most influence over
our decision.
    Comment: MDEQ stated that in the North Dakota Regional Haze SIP/
FIP, coal-fired utilities with much greater estimated visibility impact
were required to install controls similar to those required at Colstrip
1 and 2.
    Response: We disagree that certain BART determinations from the
North Dakota Regional Haze SIP/FIP are appropriate comparisons to our
BART determinations in this FIP. Our determination on the
NOX BART determinations at Milton R. Young Station Units 1
and 2 and Leland Olds Station Unit 2\10\ is explained in our final
action for regional haze for North Dakota. 77 FR 20893. Our BART
determinations were made on a source- specific basis in consideration
of the five statutory factors.
---------------------------------------------------------------------------

    \10\ We presume these units are the ``coal-fired utilities'' to
which MDEQ is referring.
---------------------------------------------------------------------------

    Comment: MDEQ stated that we ``accept, discard or include new cost
information without reason or justification.'' MDEQ supported this
claim by arguing that we used Integrated Planning Model (IPM) data in
one instance, but used costs provided by sources and an outside
consultant instead of IPM data for the North Dakota Regional Haze SIP/
FIP.
    Response: The BART Guidelines provide some flexibility in how to
calculate and consider costs. 70 FR 39127. Generally, we followed a
reasonable and supported approach. We have responded to specific
comments regarding our cost analysis in other responses.
    Comment: MDEQ stated that the averaging times and compliance
demonstrations for Colstrip 1 & 2, Corette and Devon Energy are not
practically enforceable, and therefore counter to the BART Guidelines.
MDEQ stated that the 30-day rolling average particulate matter (PM)
emission limits for Colstrip 1, Colstrip 2 and Corette, and the
NOX limit for Devon are not enforceable with an annual stack
test.
    Response: We disagree with some aspects of this comment and have
made changes in the final FIP to clarify requirements in response to
other aspects of this comment. In the proposed FIP, we concluded that
annual stack tests, along with emissions monitoring in accordance with
the applicable Compliance Assurance Monitoring (CAM) plan are
sufficient to determine compliance with BART PM limits. 77 FR 24099
(April 20, 2012). In its comments, MDEQ provides no evidence to the
contrary aside from the general statements about practical
enforceability described in the comment above. With regard to the Devon
Energy Reasonable Progress determination, we have revised the
monitoring, recordkeeping and reporting requirements in the final FIP.
We have also clarified in a correction notice that the PM limits listed
at 40 CFR 52.1396 are not based on a 30-day average. 77 FR 29270.
    Comment: MDEQ noted that Cross-State Air Pollution Regulation
(CSAPR) trading programs were recently determined by EPA to be an
alternative to source-by-source BART determinations. 77 FR 33642 (April
20, 2012). MDEQ argued that, because CSAPR is a health-based standard,
``EPA in the East is advocating the position that Montana has taken for
our own state: Realize the benefits (including visibility) from health-
based standards and make compliance with those standards the
demonstration for BART.''
    Response: Emissions trading programs and other alternative programs
can be used in place of source specific BART controls ``as long as the
alternative provides greater reasonable progress towards improving
visibility than BART.'' 77 FR 33644. Because Montana is not within the
geographic areas covered by CSAPR, and because the State did not submit
an emissions trading program or alternative program that was subject
to, let alone satisfied, the ``greater reasonable progress'' test, EPA
does not agree that compliance with other standards may replace a BART
demonstration for sources subject to BART in Montana.
    Comment: A commenter claimed that our elimination of best emission
controls based on incremental benefit is not legally supportable and
that EPA's analyses do not satisfy the purpose or the regulatory
requirements for BART determinations. The commenter stated that we
applied additional filters with unstated thresholds or standards in our
consideration of BART and that those filters eliminate or significantly
diminish the weight and importance of the required five factors. The
commenter stated that EPA used an incremental benefit test and reached
a subjective conclusion.
    Response: We disagree that our determinations are not legally
supportable. Pursuant to 40 CFR 51.308(e)(1)(ii)(A) we considered the
following five factors in our analysis: The cost of compliance; the
energy and nonair quality environmental impacts; any pollution control
equipment in use at the source; the remaining useful life of the
source; and the degree of improvement which may be reasonably
anticipated to result from the use of such technology. The Regional
Haze Rule defines BART as the best system of continuous emission
control technology available and associated emission reductions
achievable, as determined through an evaluation of the five statutory
factors. 70 FR 39126 to 70 FR 39127. While the Regional Haze Rule may
allow us to establish a bright line for some of the factors such as
cost-effectiveness and visibility, we are not required to do so, and
have not done so for this action.
    Comment: MDEQ commented that EPA makes a case for ordering the
installation of control equipment for measurable emissions reductions
absent a visibility improvement goal to achieve reasonable progress as
measured in deciviews. MDEQ stated that one of the

factors to consider when determining BART is any existing pollution
control technology in use at the source and that EPA may be
interpreting this provision to mean BART requires the installation of
any new pollution control technology that is useful for reducing
emissions generally. MDEQ stated that the statute and the Regional Haze
Rule are both clear that a BART determination focuses on existing
pollution controls and that the suitability of additional controls for
co-beneficial purposes that may be tangentially related to the National
Goal is not part of the analysis. MDEQ stated that overall purpose of
any SIP, including Montana's, is the control of emissions to comply
with the NAAQS as set forth in 42 U.S. Code (USC) Section7410 and that
the purpose of the Regional Haze Rule is to control emissions that
cause or contribute to visibility impairment in Class I Federal areas.
MDEQ stated that, ``Montana is adamant on this point because it forms
the basis for its reluctant renunciation of authority over Montana's
BART program.'' MDEQ stated that, ``the consideration of a co-benefit
strategy is not without merit, but the imposition of BART is set forth
very clearly in statute and rule. MDEQ stated that the determination of
BART has everything to do with visibility impairment and improvement,
not the attainment or maintenance of the NAAQS.'' MDEQ suggested that,
``EPA limit the BART criteria to that set forth in the rule at 40 CFR
51.308(e) and refuse to propose new controls that are not calculated to
fulfill BART criteria.''
    Response: We disagree that we have misinterpreted the BART
provision to consider any existing pollution control technology at the
source. We point out that considering existing pollution control
technology in use at the source does not preclude the consideration of
new technology. As listed in the BART Guidelines, Step 1 of the ``Five
Basic Steps of a Case-by-Case BART Analysis'' is ``Identify All
Available Retrofit Technologies.'' 70 FR 39164. A footnote to the word
``All'' in this step of the BART Guidelines reads as follows; ``In
identifying `all' options, you must identify the most stringent option
and a reasonable set of options for analysis that reflects a
comprehensive list of available technologies. It is not necessary to
list all permutations of available control levels that exist for a
given technology--the list is complete if it includes the maximum level
of control each technology is capable of achieving.'' 70 FR 39164. Our
analysis for each Montana source subject to BART included each of the
``Five Basic Steps of a Case-by-Case BART Analysis,'' as well as a
complete five-factor analysis which included consideration of ``any
existing pollution control technology in use at the source.'' Existing
pollution control technology was considered when identifying available
control options, when establishing a baseline for determining
visibility impacts or for determining annual emission reductions for
available control options. Existing pollution control technology also
was considered in establishing emission limits. With regard to MDEQ's
comment that we interpreted this provision to mean BART requires the
installation of any new pollution control technology that is useful for
reducing emissions generally, we point out that in many cases our BART
determinations did not require additional pollution control technology
to be installed for BART.
    We also disagree that we have interpreted BART to require the
installation of any new pollution control technology that is useful for
reducing emissions generally, that we used criteria other that those
listed at 40 CFR 51.308(e)(1)(ii)(A), or that we proposed new controls
that are not calculated to fulfill BART criteria. As stated in other
responses, pursuant to 40 CFR 51.308(e)(1)(ii)(A) we considered the
five factors in our analysis.. The Regional Haze Rule defines BART as
the best system of continuous emission control technology available and
associated emission reductions achievable, as determined through an
evaluation of the five statutory factors. 70 FR 39126 to 70 FR 39127.
As stated in another response, at no point in the proposed FIP did we
discuss public health impacts as a consideration in our analyses, as
they were not. As stated elsewhere, we agree that the Regional Haze
Rule is not a health-based standard, and that we are not authorized to
consider public health impacts in promulgating our FIP for purposes of
this action.
    Comment: The NPS commented that EPA determined that the incremental
visibility improvement from a control option must exceed 0.5 deciview
at a given Class I area if costs exceed $5,000/ton in order to qualify
as BART and stated that the NPS disagrees with this approach. The NPS
stated that while the BART Guidelines do recommend estimation of
incremental costs, it makes no mention of an incremental visibility
improvement test. The NPS explained that if applied linearly, EPA's
cost estimate of $3,235/ton for SCR would correspond to a visibility
improvement of 0.32 deciview, not 0.5 deciview to justify SCR. The NPS
stated that EPA concluded the benefit of SCR at Theodore Roosevelt NP
is 0.4 deciview and that therefore, by EPA criteria SCR is BART for
each Units 1 and 2.
    Response: We disagree. We have not determined that the incremental
visibility improvement from a control option must exceed 0.5 deciview
at a given Class I area if costs exceed $5,000/ton in order to qualify
as BART. As stated in other responses, while the Regional Haze Rule may
allow us to establish a bright line for some of the factors such as
cost-effectiveness and visibility, we are not required to do so, and
have not done so for this action.

C. Comments on Cement Kilns

    Comment: A commenter stated that we must not exempt cement kilns
from BART for PM. The commenter described baseline visibility impacts
from Ash Grove and Holcim and stated that the high degree of visibility
impairment warrants analysis of whether PM emission limits should be
lower to reflect BART.
    Response: We disagree that we have exempted cement kilns from BART
for PM. In our proposal, Table 35 shows that Ash Grove's greatest
baseline visibility impact is 4.446 deciviews at Gates of the Mountains
WA and Table 49 shows that Holcim's greatest baseline visibility impact
is .980 deciview at Gates of the Mountains WA. 77 FR 24011 and 77 FR
24017. While we agree with the commenter that the baseline impacts are
significant, the PM contribution to this overall baseline impact is
small. In our proposal, Table 38 shows that for Ash Grove, coarse PM
only contributes 0.84% and fine PM only contributes 4.77% to the
overall baseline visibility impact of 4.446 deciviews. 77 FR 24013.
Table 64 shows that for Holcim, coarse PM only contributes 5.79% and
fine PM only contributes 12.61% to the overall baseline visibility
impact of .980 deciview. 77 FR 24022. By contrast, our BART
determination for Ash Grove for NOX is anticipated to
achieve a visibility improvement of 1.248 deciviews and our BART
determination for Holcim is anticipated to achieve a visibility
improvement of 0.424 deciview. Any visibility improvement that could be
achieved with improvements to the existing PM controls would be
negligible. BART for PM was based on using the existing control
equipment and the emission limit established in each facility's Title V
permit. The PM BART limits for Ash Grove and Holcim were listed in our
proposal at 77 FR 24098 and are

codified by our final action at 40 CFR 52.1396.

D. Comments on Ash Grove

    Comment: Ash Grove stated that they did not object to EPA's
conclusion that BART should be based on the installation of low
NOX burner (LNB) and SNCR. However, the company stated that
they objected to the assumptions made about what SNCR can achieve. Ash
Grove stated that they explained in the prior correspondence that the
company did not believe that it is appropriate to assume that the
Montana City kiln can achieve 50% control effectiveness. Ash Grove
stated that, as the data in Table 10 of the preamble clearly showed,
only one of the three kilns at Ash Grove's Midlothian plant is able to
achieve 50% control effectiveness while the other two kilns had an
average control efficiency of 37.7% and 40.5%.
    Ash Grove also believes that no other credible evidence is provided
for our conclusion as to SNCR NOX control efficiency. Ash
Grove stated that we referenced studies from other industry sectors and
a marketing brochure from Cadence stating that ``control efficiency of
up to 50% can be achieved on long wet kilns'' and that this quote
states the upper end of what might be achievable. Ash Grove indicated
that the brochure does not state that 50% control efficiency can be
achieved on all long wet kilns, that Cadence's experience with SNCR on
long wet kilns is what is shown in Table 10, Ash Grove indicated that
Cadence was Ash Grove's partner in developing the Midlothian SNCR,
which, according to Ash Grove, are the only long wet kilns in the
United States with any track record of SNCR use. Ash Grove indicated
that even after years of optimization on the Midlothian kilns, the data
show that it has not been possible to bring all three kilns up to a 50%
control efficiency and that the Midlothian NOX reduction
data reflect not only the benefits of SNCR, but also the mid-kiln
firing of tires, use of a mid-kiln fan and other technologies that are
not available to the Montana City kiln, but that were implemented
concurrent with the SNCR installation/optimization at Midlothian to
reduce NOX emissions. Ash Grove explained that in
considering the Midlothian data, one needs to account for the direct
control efficiency these technologies provide, in addition to the
synergistic effects of using more than one control device/technique at
a time at Midlothian and that these benefits would not be available at
Montana City and should not be assumed.
    Ash Grove summarized that they continued to believe that a SNCR
system at Montana City cannot be assumed to reach greater than 35%
control efficiency and that EPA has produced no credible evidence in
the record for supporting a different conclusion. Ash Grove stated that
they recognized that their initial BART submittal listed 50% control as
achievable for the combination of a low NOX burner and SNCR
at the Montana City kiln but since then they have realized they cannot
get to that level on all three kilns at Midlothian. Ash Grove stated
that they are willing to not contest the 8.0 lb/ton clinker limit, and
they anticipate that compliance could require additional control
technologies/strategies; therefore, they need the maximum time
allowable to find ways to consistently maintain NOX at or
below that level.
    Response: We disagree that SNCR cannot achieve a 50% control
effectiveness at Ash Grove. The data from Ash Grove's Midlothian, Texas
kilns in Table 10 of the proposed FIP, 77 FR 24003, show the SNCR
control effectiveness achieved. The data were not intended to imply
that this is the upper bound of what might be achieved. Ash Grove did
not submit any information demonstrating that this was the maximum
reduction that could have been achieved. It was not necessary to
achieve greater reductions from the Midlothian Texas kilns to comply
with the required emission limit. In Texas, SNCR was used at Midlothian
to comply with the emission limit established at Texas Administrative
Code (TAC) 117.3110(a)(1)(B) of 4.0 lb/ton clinker. TAC 117.3110(b)
allowed an owner or operator of a long wet kiln to comply with the 4.0
lbs/ton clinker emission limit on the basis of a weighted average for
multiple cement kilns. Thus, it was not necessary for each individual
kiln to achieve the maximum percentage reduction possible; one or more
kilns could emit more than 4.0 lbs/ton clinker as long as the weighted
average complied with the emission limit.
    Ash Grove has not submitted any data to demonstrate that SNCR was
optimized in an attempt to achieve the greatest control efficiency
possible. For the Midlothian kilns, from June-August 2009, the emission
rate from kiln 1 was 3.7 lbs/ton clinker and the emission rate from
kiln 2 was 4.8 lbs/ton clinker and from June through August 2010, the
emission rate from kiln 1 was 2.6 lbs./ton clinker, the emission rate
from kiln 2 was 4.8 lbs/ton clinker, and the emission rate from kiln 3
was 4.4 lbs/ton clinker. These emission rates are significantly higher
than the emission rates from June to August 2008 (an average of 1.8
lbs/ton clinker for kiln 1, 2.7 lbs/ton clinker for kiln 2, and 2.7
lbs/ton clinker for kiln 3). An increase in NOX emissions
over time would not be expected if the SNCR were being optimized.
    With regard to Ash Grove's claim that we need to account for the
direct control efficiency of other technologies that are not available
to the Montana City Kiln, the tire-derived fuel system was already
being used at Midlothian in 2006 and is already accounted for in the
2006 baseline to which the 2008 post-SNCR emissions are compared.\11\
Thus, no further adjustment is necessary. Ash Grove has not provided
data to demonstrate that a synergistic effect has occurred between mid-
kiln firing of tires and SNCR at Midlothian.
---------------------------------------------------------------------------

    \11\ Letter from Molly Cagle to Chance Goodwin, Initial Control
Strategy Development for DFW Ozone Nonattainment Area, July 30,
2010, p. 1.
---------------------------------------------------------------------------

    Ash Grove has not submitted data to support their claim that only
35% reduction can be achieved with SNCR at the Montana City kiln. All
of the Midlothian kilns were able to achieve greater than 35% reduction
with SNCR and there is no information to demonstrate that SNCR was
optimized to its maximum potential. The BART Guidelines state, ``In
assessing the capability of the control alternative, latitude exists to
consider special circumstances pertinent to the specific source under
review, or regarding the prior application of the control alternative.
However, you should explain the basis for choosing the alternate level
(or range) of control in the BART analysis. Without a showing of
differences between the source and other sources that have achieved
more stringent emissions limits, you should conclude that the level
being achieved by those other sources is representative of the
achievable level for the source being analyzed.'' 70 FR 39166. Ash
Grove has not demonstrated the differences between their Montana City
kiln and the Midlothian kilns.
    With regard to Ash Grove's statement that we have not produced
credible evidence in the record for supporting a greater than 35%
control effectiveness for SNCR, we provided a detailed explanation in
our proposed FIP at 77 FR 24003. Ash Grove has used SNCR at its
Midlothian kilns where it was shown to achieve the reductions ranging
from 37.7% to 62.5% and these are within the range of control
effectiveness demonstrated at other kilns. Considering that control
effectiveness is greater when initial NOX concentrations are
greater, and that the baseline NOX emissions of the Montana
City kiln are

significantly greater than the Midlothian kilns, the Montana City kiln
would be expected to achieve even greater control effectiveness when
compared to the Midlothian kilns. 77 FR 24003 and 77 FR 24004.
    Ash Grove's comment that they are willing to not contest the 8.0
lb/ton clinker limit is noted. With regard to Ash Grove's comment that
they anticipate that compliance could require additional control
technologies/strategies and that therefore they need the maximum time
allowable to find ways to consistently maintain NOX at or
below that level, we disagree that additional control technologies/
strategies are necessary; however, the final FIP does not require
specific control technologies/strategies to be used. The final FIP
allows for the maximum time available to comply with the 8.0 lb/ton
clinker limit.
    Comment: Ash Grove stated that the company supported the
conclusions as to what constitutes BART for SO2. Ash Grove
noted that in the preamble we stated that there is so little
improvement in visibility associated with implementing add-on
SO2 controls that there is no basis for requiring such
controls under BART. Ash Grove stated that Clean Air Act Section
169A(g)(2) clearly states that ``the degree of improvement in
visibility which may reasonably be anticipated to result'' must be used
in evaluating potential BART controls. Ash Grove concluded that given
the nominal improvement in visibility predicted from add-on controls,
there is no basis under BART for requiring the addition of such
controls. Ash Grove stated that the BART program has a very narrow
statutory focus in that it exclusively addresses visibility improvement
and that absent a material increase in visibility, the company believes
that we would have been arbitrary and capricious if we had required
add-on controls for SO2 utilizing our BART authority. Ash
Grove stated that the company supported our ultimate conclusion.
    Response: The comment is noted. The final FIP makes no changes to
the conclusions regarding SO2 controls for Ash Grove.
    Comment: Ash Grove stated that the company supported our conclusion
that existing PM controls (an electrostatic precipitator (ESP))
constitute BART and that ESPs are well-accepted controls for wet kilns.
Ash Grove stated that their compliance with the filterable particulate
standard in the process weight rule applicable to the kiln is an
appropriate limit for ensuring that the ESP is properly operating and
that annual compliance demonstrations will ensure ongoing compliance.
Ash Grove stated that they believe that this approach is particularly
appropriate where the contribution of PM emissions to visibility
impairment is nominal.
    Response: The comment is noted. The final FIP makes no changes to
the conclusions regarding PM controls for Ash Grove.
    Comment: Ash Grove requests clarification on whether they must
comply with BART limits for SO2 and PM within five years of
the effective date of the rule, as specified in the proposed regulatory
text at 40 CFR 52.1396(d), or within 180 days for SO2 and 30
days for PM, as suggested by the preamble to the proposed rule. If the
intent is to require compliance sooner than five years from the
effective date, then Ash Grove requests that the rule be renoticed, and
that if EPA will not allow five years from the effective date, then Ash
Grove requests that the BART compliance date for these pollutants be
30/180 days after the effective date, or the Portland cement National
Emission Standards for Hazardous Air Pollutants (NESHAP) compliance
date, whichever is later, in order to coordinate with the
implementation of EPA's Portland cement NESHAP and New Source
Performance Standard (NSPS) requirements, including installation and
certification of continuous emission monitoring systems (CEMS). Ash
Grove stated that the monitoring that EPA is imposing as part of the
concurrent Portland cement Maximum Achievable Control Technology (MACT)
rulemaking is very complicated and must be able to work in concert with
what EPA imposes under this BART rulemaking. Ash Grove also stated that
critical components of Ash Grove's envisioned monitoring scheme, such
as installation of clinker weigh belts or the development of slurry
conversion mechanisms, cannot be implemented within the 180 day period
after the effective date.
    Response: We agree with aspects of this comment, but disagree with
others. We agree that there is an omission in the proposed 40 CFR
52.1396(d). We failed to specify, in the rule language itself, the
compliance deadline for SO2 of 180 days after the effective
date of the FIP, and the compliance deadline for PM of 30 days after
the effective date of the FIP. These deadlines were mentioned in the
rule preamble. We have corrected the rule language at 40 CFR 52.1396(d)
to specify these deadlines. For both SO2 and NOX,
we further clarify that the 180-day deadline is applicable only where
installation of additional controls is not necessary to comply with the
BART limit; otherwise the compliance deadline is five years after the
effective date of our rule.
    We disagree that the compliance deadline should be 30/180 days
after the FIP effective date, or the Portland cement NESHAP compliance
date, whichever is later. With regard to ``whichever is later,'' EPA
does not have the option of specifying an open-ended compliance
deadline for BART. In our FIP proposal at 77 FR 23993, we explained
that ``Once EPA has made its BART determination, the BART controls must
be installed and in operation as expeditiously as practicable, but no
later than five years after the date of the final FIP. CAA section
169(g)(4) and 40 CFR 51.308(e)(1)(iv).'' Ash Grove's comment does not
dispute this explanation.
    Further, Ash Grove has not presented any specific reason for us to
wait on the Portland cement MACT rulemaking before imposing PM and
SO2 monitoring requirements for purposes of BART. First in
regard to SO2 monitoring, the proposed amendments to the
Portland cement MACT and NSPS rules do not include any changes to the
SO2 CEMS monitoring requirements. In the proposed
amendments, EPA is proposing to correct the emission rate calculation
formula for SO2 in NSPS Subpart F, at 40 CFR 60.64(c), but
since we are making the same correction in our final FIP rule (see our
response below to the comment on NOX and SO2
emission rate calculation), this is not a valid reason to wait until
the Portland cement MACT and NSPS amendments are finalized before
imposing SO2 monitoring in the FIP.
    Further, the proposed amended Portland cement MACT and NSPS rules
require a SO2 CEMS only if the kiln is subject to an
SO2 limit under NSPS. Ash Grove has not indicated that their
kiln in Montana is subject to an SO2 limit under NSPS, and
even if it is, the proposed amended Portland cement MACT and NSPS rules
will not impose any different requirements for an SO2 CEMS
than those in existing NSPS rules at 40 CFR 60.63(f), which are cross-
referenced by our proposed regulatory text at 40 CFR 52.1396(e)(3). Ash
Grove has also not presented any specific reason, such as vendor
unavailability or site-specific complications, why it should take more
than 180 days to replace and certify their SO2 CEMS. We have
already stated in our FIP proposal that 180 days would allow time for
monitoring systems to be certified if necessary. We are clarifying that
CEMS will have to be certified for BART purposes independent of NSPS
requirements.
    Second, in regard to PM monitoring, the proposed amendments to the

Portland cement MACT and NSPS rules require a PM continuous parametric
monitoring system (CPMS), whereas the existing Portland cement MACT and
NSPS rules require a PM CEMS. Since our FIP proposal does not require
PM CPMS nor PM CEMS, the proposed amendments to the Portland cement
MACT and NSPS rules do not affect the FIP and are not a valid reason to
extend the 30-day compliance deadline for PM in the FIP.
    With regard to Ash Grove's statement that critical components of
the monitoring scheme, such as installation of clinker weigh belts or
the development of slurry conversion mechanisms, cannot be implemented
within the 180 day period after the effective date of the FIP, Ash
Grove has not presented any specific reason why it should take longer
than 180 days. With regard to Ash Grove's statement that the clinker
monitoring must work in concert with the MACT rulemaking, our proposed
regulatory text at 40 CFR 52.1396(e)(4)(ii) cross-references 40 CFR
60.63(b) for clinker production monitoring requirements. The proposed
amendments to the Portland cement MACT and NSPS rules do not change the
requirements in the existing section 60.63(b) for determining the
amount of clinker produced. Only minor language clarifications are
proposed, and there is no change to actual requirements.
    We note that Ash Grove has no issue with the proposed PM BART
emission limit. However, in preparing responses to Ash Grove's comments
on other aspects of our proposed FIP, we identified a typographical
error in our emission limit table for cement kilns. We made a
correction to the emission limit table for cement kilns at
52.1396(c)(2), to clarify that the PM emission limit for Ash Grove is
in lb/hr, not lb/ton clinker. Only the PM emission limit for Holcim is
in lb/ton clinker. Similarly, we have clarified 40 CFR 52.1396(f)(2) to
indicate that the emission rate of particulate matter shall be reported
in lb/hr for Ash Grove, and in lb/ton clinker for Holcim. Ash Grove is
not required to monitor clinker production for purposes of
demonstrating compliance with the PM BART limit. We have also included
in 40 CFR 52.1396(f)(2) the equation for calculating lb/ton clinker for
PM at Holcim, rather than cross-reference 40 CFR 52.1396(e)(4)(ii),
which pertains to SO2 and NOX, not PM.
    Comment: Ash Grove does not object to the requirement in our
proposed regulatory text at 40 CFR 52.1396(e)(3) to maintain, calibrate
and operate SO2 and NOX CEMS on the cement kiln
stack. Ash Grove requests, to be consistent with other requirements to
which they are subject, that the language be revised and proposed
creating an exception during CEMS breakdown, repairs, calibration
checks, and zero and span adjustments.
    Response: We agree it is appropriate to address the language for
consistency purposes. Rather than use the language proposed by Ash
Grove, we are incorporating language from 40 CFR 60.63(g), which says,

    You must operate the monitoring system and collect data at all
required intervals at all times the affected source is operating,
except for periods of monitoring systems malfunctions, repairs
associated with monitoring system malfunctions, and required
monitoring system quality assurance or quality control activities
(including, as applicable, calibration checks and required zero and
span adjustments).

    We have revised the regulatory text at 40 CFR 52.1396(e)(3)
accordingly. 40 CFR 60.63(g).
    Comment: Ash Grove also believes it is critical that the facility
have adequate time to install, shake down and calibrate the necessary
CEMS equipment. The facility currently lacks a flow meter and does not
have certified CEMS. As a result, Ash Grove anticipates that it must
replace its CEMS system, including the data acquisition and handling
system (DAHS) as part of Portland cement MACT implementation. Ash Grove
stated that this effort cannot be completed until the Portland cement
MACT requirements are finalized, as Ash Grove understands that the
NESHAP monitoring provisions are in flux. Therefore, Ash Grove believes
that the BART CEMS requirements must be implemented at the same time
that the Portland cement MACT CEMS requirements are implemented and not
before.
    Response: We disagree. See our response on compliance deadlines
above. EPA does not have the option of specifying an open-ended
compliance deadline for BART. Further, Ash Grove has not presented any
specific reason, such as vendor unavailability or site-specific
complications, why it should take longer than 180 days to install a
flow meter and replace the CEMS system with a certified system. This
comment has not resulted in any change to our proposal.
    Comment: Ash Grove supports the approach whereby the CEMS data are
utilized to demonstrate compliance with the NOX and
SO2 BART limits. However, Ash Grove believes there is a
material error in the formula used in the proposed regulatory text at
40 CFR 52.1396(e)(4)(ii). The formula expresses the concentrations of
SO2 and NOX in grains per standard cubic foot
(gr/scf). Ash Grove noted that a CEMS would not normally generate
SO2 or NOX concentrations in gr/scf, but in parts
per million (ppm), consistent with the requirements of 40 CFR 60,
Appendix B, Performance Specification 2. Ash Grove recognizes that this
formula was likely intended to match Equation 3 in the 2010 revised
Subpart F NSPS. While Ash Grove appreciates the effort to maintain
consistency between the requirements, Ash Grove believes that Equation
3 in the Subpart F NSPS is in error and will be corrected in the
upcoming public notice addressing Subpart F. Ash Grove provided a
suggested formula to replace the formula stated in the proposed
regulatory text.
    Response: We agree for the reasons stated by Ash Grove that the
formula for calculating the emissions should express SO2 and
NOX concentrations in ppm, not in gr/scf. We have corrected
40 CFR 52.1396(e)(4)(ii) accordingly; however, rather than use the
language proposed by Ash Grove, we have used the formula and associated
language found in the proposed amendments to the Portland cement NSPS.
77 FR 42397.
    Comment: Ash Grove noted that the proposed regulatory text at 40
CFR 52.1396(f) would require that Ash Grove perform EPA Method 5, 5B,
5D or 17, 40 CFR Part 60, Appendix A, to demonstrate compliance with
the PM limit and that the test consist of three runs with each run at
least 120 minutes long and each run collecting a minimum sample of 60
dry standard cubic feet. Ash Grove supports the approach of identifying
the specific source test methods in the rule. However, Ash Grove does
not support specifying the duration of each test run and the minimum
sample size. Ash grove stated that this BART FIP is being implemented
with the intent that it will control emissions for many years to come.
Ash Grove stated that placing this type of detailed data into the rule,
rather than letting the test duration and sample size be determined
based on the test method as it exists at the time of the test, invites
future confusion and trouble. Therefore, Ash Grove suggested that EPA
specify the test methods but delete the other language relating to the
test duration and sample size.
    Response: We disagree. The test method does not determine the test
duration and sample size, but cross-references other rules in this
regard. EPA Method 5 states in subsection 8.2.4, ``Select a total
sampling time greater than or equal to the minimum total sampling time
specified in the test

procedures for the specific industry, such that (1) the sampling time
per point is not less than 2 minutes (or some greater time interval as
specified by the Administrator), and (2) the sample volume taken
(corrected to standard conditions) will exceed the required minimum
total gas sample volume.'' Methods 5B and 5D cross-reference Method 5
for sampling time and sampling volume. Method 17 does not cross-
reference Method 5 for sampling time and sampling volume, but does not
specify anything different. We consider three test runs, with each run
at least 120 minutes long, and each run collecting a minimum sample of
60 dry standard cubic feet, to be appropriate and necessary for
purposes of the Montana Regional Haze FIP. We note that this has been
specified in PM stack testing requirements in other regional haze FIPs.
(See, for example, Proposed Final FIP by EPA Region 9 for the Four
Corners Power Plant, 76 FR 52387, August 22, 2011.) This comment has
not resulted in any change to our proposal.
    Comment: Ash Grove stated that the proposed regulatory text at 40
CFR 52.1396(h)(6) would require that they maintain, among other things,
records required by Part 75. Ash Grove is not subject to part 75 as
that applies only to electrical generating units. Ash Grove believes
that this reference to Part 75 was just a ``catch-all'' and not
intended to impose any obligations under Part 75 upon cement kilns
otherwise not subject to Part 75. However, due to the potential for
misunderstanding and the lack of relevance of the Acid Rain provisions
to cement kilns, Ash Grove requested that the reference to Part 75 be
deleted.
    Response: We agree. Since the proposed monitoring requirements for
cement kilns, at sections 52.1396(e)(3) and (4), and at section
52.1396(f)(2), do not cross-reference Part 75, there are no applicable
Part 75 recordkeeping requirements under our FIP proposal. Therefore,
the reference to Part 75 on recordkeeping, at 40 CFR 52.1396(h)(6), is
not necessary and has been removed.
    Comment: Ash Grove stated that the proposed regulatory text at 40
CFR 52.1396(i) would require that Ash Grove submit quarterly excess
emission reports and CEMS performance reports. Ash Grove currently is
subject to similar reporting requirements under the Title V and NESHAP
programs. However, in both of those programs the reports are submitted
semi-annually, not quarterly. Ash Grove sees no purpose gained by
submitting the reports quarterly and the additional administrative
burden is significant. Therefore, Ash Grove requested that EPA revise
this reporting requirement to make it consistent with the similar
reports submitted under Title V and NESHAP programs, i.e., semiannual
reports.
    Response: We agree. We used provisions in NSPS Subparts A and F
applicable to cement kilns as a model for the CEMS-related reporting
requirements for cement kilns in our FIP proposal. The general
provisions of NSPS Subpart A, at 40 CFR 60.7(c), require semiannual
excess emission reports and monitoring systems performance reports,
except when more frequent reporting is specifically required by an
applicable subpart, or if the Administrator, on a case-by-case basis,
determines that more frequent reporting is necessary to accurately
assess the compliance status of the source. NSPS Subpart F for cement
kilns does not specify more frequent reporting. Therefore, we have
revised the required reporting frequency to semiannual in 40 CFR
52.1396(i)(1) and (i)(2) for cement kilns. The required reporting
frequency for EGUs remains quarterly.
    Comment: Ash Grove requested that EPA revise its proposed
regulatory text at 40 CFR 52.1396(i)(2)(ii) requiring the company to
submit Relative Accuracy Audits (RAAs) and Cylinder Gas Audits (CGAs).
Ash Grove does not object to the idea of submitting Relative Accuracy
Test Audits (RATAs) as those are documented in a highly formalized test
report prepared by a third party testing contractor. However, the RAAs
and CGAs are not documented in the same type of formal third party
report. Ash Grove believes that it is adequate to certify that the
audits have been performed as part of the semiannual reports.
    Response: We disagree. Our proposed regulatory text at 40 CFR
52.1396(e)(3) states that the CEMS shall be used to determine
compliance with the emission limitations in section 52.1396(c), for
each unit, in combination with data on actual clinker production. For
cement kilns, 40 CFR section 52.1396(i)(2)(ii) requires submittal of
results of any CEMS performance tests required by 40 CFR part 60,
appendix F, Procedure 1, which is titled ``Quality Assurance
Requirements for Gas Continuous Emission Monitoring Systems Used for
Compliance Determination.'' Under Section 7 of Procedure 1 (Reporting
Requirements), it is not adequate to merely certify that the RAAs and
CGAs have been performed. Section 7 requires submittal of a Data
Assessment Report for each quarterly audit, which must include
``Assessment of CEMS data accuracy and date of assessment, as
determined by a RATA, RAA or CGA described in Section 5, including * *
*, the A [accuracy] for the RAA or CGA, the RM [reference method]
results, the cylinder gases certified values, the CEMS responses, and
the calculations results as defined in Section 6.'' This information
must be included in the semiannual reports referenced in our response
to the previous comment above. We consider this information appropriate
and necessary. This comment has not resulted in any change to our FIP
proposal.
    Comment: Ash Grove requested that EPA drop the requirement proposed
in 40 CFR 52.1396(k)(2) to provide semiannual progress reports on
construction of SO2 and NOX control equipment.
Ash Grove does not object to filing notification of commencement of
construction as this obligation is consistent with what Ash Grove is
used to under the NSPS and state new source review program. However,
semiannual construction progress reports are not something that Ash
Grove is typically set up to generate and there seems to be little
gained from such reports. Therefore, Ash Grove requested that this
requirement be dropped from the rule.
    Response: We disagree. We consider construction progress reports
necessary as part of ensuring that BART sources meet their five-year
compliance deadlines. Since installation of substantial equipment may
be involved, there could be unforeseen construction delays that we
would want to be aware of well before the five-year deadline. We do not
consider this reporting a burdensome requirement, as our FIP proposal
does not specify any particular level of detail for these progress
reports. This comment has not resulted in any change to our FIP
proposal.
    Comment: Ash Grove noted that the BART limits are identified as
applying at all times, including startup, shutdown and malfunction.
Although the preamble states that the proposed limits allow ``for a
sufficient margin of compliance,'' Ash Grove argued that these limits
do not take into account the impact of sudden and unforeseen effects
attributable to malfunctions. As compliance with all three limits
(i.e., SO2, PM and NOX) could be affected by a
malfunction, Ash Grove believes that it is appropriate for EPA to
provide the same affirmative defense in the event of a malfunction as
is provided in the Portland cement MACT rules. Specifically, Ash Grove
requested that EPA incorporate the same affirmative defense provided in
40 C.F.R. 63.1344 to address malfunctions.
    Response: EPA disagrees with this comment. As stated in our
proposal, to determine the BART NOX limit for Ash

Grove, we first applied the efficiency of the selected controls, LNB +
SNCR at 58%, to the 99th percentile 30-day rolling average
NOX emission rate at this facility for May 26, 2006 through
September 8, 2008, resulting in a figure of 7.82 lb/ton clinker. 77 FR
at 24007 n.45. We then set the BART limit above this, at 8.0 lb/ton
clinker. Ash Grove provides no data to show that, at this facility,
this limit cannot be achieved due to malfunctions, or that our use of
the 99th percentile 30-day rolling-average NOX emission rate
in combination with the additional margin (from 7.82 to 8.0 lb/ton
clinker) provides an insufficient margin of compliance.
    For SO2, we did not select any additional controls for
BART. We based the BART SO2 limit on the 99th percentile 30-
day rolling average SO2 emission rate at this facility for
May 26, 2006 through September 8, 2008, 11.02 lb/ton clinker, and set
the BART limit at 11.5 lb/ton clinker. 77 FR at 24013 n.73. Ash Grove
provides no data to show that, at this facility, this limit cannot be
achieved due to malfunctions, or that our use of the 99th percentile
30-day rolling average SO2 emission rate at this facility in
combination with the additional margin (from 11.02 to 11.5 lb/ton
clinker) provides an insufficient margin of compliance.
    We also did not select any additional controls for PM. Ash Grove
currently has an electrostatic precipitator for PM control and is
subject to a process weight-based PM10 emission rate set out
in Montana's approved SIP and Ash Grove's title V operation permit. We
set the BART limit, based on use of the current control technology, at
the existing emission rate. Ash Grove has not provided any data to show
that it is not able to meet the existing limit due to malfunctions. As
a result, we continue to maintain that the NOX,
SO2, and PM BART limits for Ash Grove provide for a
sufficient margin of compliance, including taking into account
malfunctions.
    With respect to the Portland cement MACT standard, we note that the
MACT standard applies across the entire source category, while the BART
limits imposed in this FIP reflect application of the five statutory
BART factors to a particular facility, Ash Grove. Ash Grove does not
explain why, in this circumstance, the existence of the affirmative
defense in the MACT standard necessarily implies an affirmative defense
is required for the BART limits, which as discussed above, for
NOX and SO2 are based in part on actual emissions
from Ash Grove, and for PM are based on an existing limit for Ash
Grove. We therefore disagree that the affirmative defense provided for
in 40 CFR section 63.1344 should be also provided for in this FIP.
    Comment: The opening sentence of the proposed regulatory text at 40
CFR 52.1396(i) states ``All reports under this section, with the
exception of 40 CFR 53.1395(n) and (o) shall be submitted * * *'' Ash
Grove believes that this cross-reference is in error, as Ash Grove is
not aware of there being a 40 CFR 53.1395(n) or (o). Ash Grove believes
this was intended to cite to 40 CFR 52.1396(n) and (o).
    Response: We agree this was an error. We have corrected the
language to cite to section 52.1396(n) and (o), instead of section
53.1395(n) and (o).

E. Comments on Holcim

    Comment: Montanans Against Toxic Burning (MATB) applauded our
proposed retrofit of the Holcim kiln to include LNB and SNCR.
    Response: We acknowledge MATB's support.
    Comment: MATB believes that we should reanalyze the fuel-switching
option for the Holcim cement kiln. Specifically, they stated that
petroleum coke inputs should be reduced, which they believe would lead
to significant reductions in SO2 emissions. They also stated
that our analysis may be skewed by what MATB describes as Holcim's
``low-ball'' estimates of its sulfur emissions. MATB believes that a
review of Holcim's past monitoring data could lead to a different
conclusion.
    Response: We disagree that it is necessary to reanalyze fuel
switching options for Holcim. In our analysis, we used annual
SO2 emissions as reported to the National Emissions
Inventory and we have no reason to believe that these were
underestimated. The annual emissions (50.2 tpy) are so minimal that
fuel switching options resulting in increased annual cost would not be
considered cost-effective on a dollar per ton basis. In addition, the
visibility improvement from fuel switching is very low at 0.015
deciview for fuel switching option 1 and 0.024 deciview for fuel
switching option 2.
    Comment: MATB commented that a ``real-time hourly'' standard for
NOX and SO2, rather than the 30-day rolling
averages based on clinker production proposed, is needed to assure
compliance with protective limits. MATB explained that with the 30-day
rolling averages, spikes due to malfunction or improper operation will
``disappear'' in the averaging process.
    Response: We assume that by ``real-time hourly'' standard, the
commenter means an emission limit in pounds per hour. We disagree that
we should establish an hourly standard rather than a 30-day rolling
average limit based on clinker production. As we explained in our
proposal (77 FR 24007), we chose an output-based standard because it
avoids rewarding a source for becoming less efficient, i.e., requiring
more feed to produce a unit of product. An output-based standard
promotes the most efficient production process. With regard to 30-day
versus hourly averaging time, EPA's BART guideline calls for BART
emission limits to be expressed as 30-day rolling averages for
electrical generating units. 70 FR 39172. We believe this is
appropriate for other BART units as well. The proposed limit allows for
a sufficient margin of compliance for a 30-day rolling average limit
that would apply at all times, including startup, shutdown, and
malfunction. 77 FR 24018.
    Comment: MATB believes that more oversight, transparency, and
accountability are needed when it comes to reporting and record
keeping.
    Response: We are confident that the information used to make our
decision is accurate. With regard to reporting and recordkeeping
requirements under the FIP, the commenter has not explained what
oversight, transparency and accountability is lacking and what more is
needed in this regard. That said, section 114 of the CAA allows EPA and
the State to ask for monitoring data and reports as necessary. These
documents are available to the public unless the information is claimed
to be confidential business information.
    Comment: MATB commented that the efficiency of Holcim's ESP is
incorrect as stated in EPA's analysis, and does not operate during most
malfunctions. These malfunctions can last 24 hours or more.
Additionally, MATB stated that EPA's analysis fails to consider PM
during periods of startup, shutdown and malfunction and considering the
frequent upsets with the Trident kiln, that cause its ESP to be turned
off, an additional control measure at Holcim is essential. MATB
encouraged us to analyze the addition of a fabric filter.
    Response: We disagree that it is necessary to evaluate the
installation of a fabric filter at Holcim. In our proposal, we
explained that PM emissions from Holcim did not significantly
contribute to visibility impairment. We used actual emission rates to
model the visibility impact from Holcim. Because the baseline
visibility impact from PM was low, improvements to the existing PM
control device would not be significant.
    Comment: The commenter stated that an annual three-hour stack test
is

inadequate to monitor PM emission limit compliance.
    Response: We disagree. The proposed requirements for demonstrating
compliance with PM emission limits include more than just an annual
three-hour stack test. ``In addition to annual stack tests, owner/
operator shall monitor particulate emissions for compliance with the
BART emission limits in accordance with the applicable Compliance
Assurance Monitoring (CAM) plan developed and approved in accordance
with 40 CFR part 64.'' 77 FR 24099. The requirements include the
following:
     40 CFR 64.3(a) requires that a monitoring parameter be
selected by the owner/operator as an indicator of emission control
performance for the control device.
     40 CFR 64.3(b) requires that an indicator range for that
parameter be selected ``such that operation within the range provides a
reasonable assurance of ongoing compliance with emission limitations or
standards for the anticipated range of operating conditions.''
     40 CFR 64.7(d) requires the owner/operator, upon detecting
an excursion or exceedance of the CAM indicator range, to restore
operation of the emitting unit and emission control device to its
normal or usual manner of operation as expeditiously as practicable, in
accordance with good air pollution control practices for minimizing
emissions.
     40 CFR 64.8 says the Administrator or permitting authority
may require the owner/operator, in the event of repeated excursions or
exceedances of the CAM indicator range, to develop and implement a
Quality Improvement Plan, to correct any control device performance
problems.
    Further, 40 CFR 52.11396(l) states, ``At all times, owner/operator
shall maintain each unit, including associated air pollution control
equipment, in a manner consistent with good air pollution control
practices for minimizing emissions'' This applies to all sources in the
FIP.
    Comment: MATB explained that there are inconsistencies in EPA's
proposed NOX and SO2 emissions limits, and there
appears to be a mistake on Table 53 dealing with fuel-switching
options.
    Response: These inconsistencies were corrected in the FR notice
dated May 17, 2012. 77 FR 29270.
    Comment: Holcim commented that that the output-based standards we
proposed reward a source for operating inefficiently. Holcim indicated
that our proposed FIP is unfairly stringent with respect to Holcim as
compared to Ash Grove. They stated that the kiln types and capacities
of the two plants are substantially equal, but that Holcim's emissions
profiles are notably different. Holcim stated that they use proper kiln
design and best combustion practices to control NOX
emissions at their plant, and that Ash Grove has NOX
emissions that are 42% higher than NOX emissions from the
Holcim plant. Holcim further stated that our proposed FIP rewards Ash
Grove with a NOX BART emission limit that is 60% higher than
Holcim's proposed NOX BART emission limit. Holcim pointed
out that their kiln has substantially lower current NOX
emission rates, lower current visibility impacts, and a lower
subsequent visibility improvement, yet our FIP requires substantially
tighter emission limits for NOX and SO2.
    Holcim commented that, based on EPA's analysis, the proposed
NOX limit would require Holcim to invest a total of $5.6
million in SNCR and indirect firing, which would result in an
improvement in visibility at Gates of the Mountains WA that is
significantly less than the 1.0 deciview perceptibility threshold and
that our proposed FIP would require only a $1.19 million capital
investment from Ash Grove, even though Ash Grove's impact on Gates of
the Mountains WA is more than double the impact from Holcim. Holcim
also stated that we estimated that Ash Grove's NOX emissions
caused degradation in visibility of greater than 0.5 deciview at Gates
of the Mountains WA on approximately 33% of the days in the baseline
period while Holcim impacted Gates of the Mountains WA at greater than
0.5 deciview only on approximately 4% of the days during the baseline
period. Holcim stated that EPA's approach would reward Ash Grove's
higher emissions and inefficient operation by creating an economic
disadvantage for Holcim in a highly competitive market.
    Response: We disagree. Our explanation in the proposed FIP
regarding the output-based standard was provided to explain the
difference between a standard expressed in quantity of pollutant per
amount of feed and quantity of pollutant per amount of product
produced. As explained in our proposal, an output-based standard avoids
rewarding a source for becoming less efficient, i.e., requiring more
feed to produce a unit of product. 77 FR 24007. Our explanation did not
imply that both sources should have exactly the same emission rate. The
NOX standards for both Holcim and Ash Grove were determined
by applying the control efficiency of the selected technologies to the
current emission rates at each facility. This is the most appropriate
method to determine emission limits for these two sources. As explained
in other responses, we are not requiring Holcim to convert to indirect
firing in the final FIP, so the information comparing capital
investment is no longer relevant. In the final FIP, we have determined
the emission rate for Ash Grove by applying the control effectiveness
of LNB + SNCR (58%) to the current emission rate and as explained in
other responses we have revised the emission rate for Holcim by
applying the control effectiveness of SNCR (50%) to the current
emission rate. In both cases, we have determined the emission rate
based on the control effectiveness of the control technology that was
chosen based on the five statutory BART factors listed at CAA section
169A(g)(2) and 40 CFR 51.308(e)(1)(ii)(A). The five statutory factors
include the costs of compliance and visibility improvement; therefore,
these factors were evaluated and considered in the selection of
controls. Applying the control effectiveness of the technology that was
identified based on the five statutory factors to the current emission
rates for each source is a logical method for determining emission
rates. This same methodology was used for determining the emission
rates for both sources.
    We note that in the final FIP, Ash Grove will reduce an estimated
1,088 tons per year of NOX using LNB+SNCR at a total annual
cost of $2,238,893, but Holcim will only reduce an estimated 556 tons
per year of NOX at a total annual cost of $650,399. Ash
Grove will be reducing 946 tons per year of NOX through the
operation of SNCR, but Holcim will only be reducing 556 tons per year
through the operation of SNCR.\12\ We provide this information to
demonstrate that overall, more emissions will be reduced by Ash Grove
and to also illuminate the fact that annual cost will be greater for
Ash Grove. The cost of reagent is proportional to the amount of
pollutant removed; therefore, annual reagent cost will be significantly
greater for Ash Grove.
---------------------------------------------------------------------------

    \12\ See Table 11, FR 77 24004, and Table 22, 77 FR 24007 for
Ash Grove. Holcim's baseline NOX emissions are 1,112 tpy.
Revised emissions reduction for SNCR only for Holcim is 556 tpy and
cost is $1,170/ton.
---------------------------------------------------------------------------

    We are not requiring additional controls for SO2 for
either Holcim or Ash Grove and the SO2 limits for each
facility were determined based on current emission rates. This
determination was based on an evaluation of the five statutory factors
and the SO2 emission rates were determined in the same
manner for both

facilities. There is no necessity for additional SO2 control
at either facility; the current controls were considered to be BART.
    As for Holcim's comment that the proposed FIP rewards Ash Grove's
higher emissions and inefficient operation by creating an economic
disadvantage for Holcim in a highly competitive market, the BART
Guidelines do allow for the consideration of unusual circumstances that
justify taking into consideration the conditions of the plant and the
economic effects of requiring the use of a given control technology.
The BART Guidelines state:

    [t]hese effects would include effects on product prices, the
market share, and profitability of the source. Where there are such
unusual circumstances that are judged to affect plant operations,
you may take into consideration the conditions of the plant and the
economic effects of requiring the use of a control technology. Where
these effects are judged to have a severe impact on plant operations
you may consider them in the selection process, but you may wish to
provide an economic analysis that demonstrates, in sufficient detail
for public review, the specific economic effects, parameters, and
reasoning.

70 FR 39171. Holcim did not provide information for us to consider in
such an analysis.
    The BART Guidelines also state, ``[a]ny analysis may also consider
whether other competing plants in the same industry have been required
to install BART controls if this information is available.'' 70 FR
39171. In this case, Ash Grove is required to install BART controls. We
have considered each plant individually, and based on the BART analyses
both Holcim and Ash Grove plants are required to install BART controls.
    Comment: Holcim argued that the Texas kilns cited by EPA in the FIP
are not representative and two of the three kilns did not achieve 50%
NOX reduction. Holcim cited several site-specific factors
that impact SNCR performance that they state EPA did not adequately
consider, including turbulent mixing, heat transfer, spray droplet
size, spray drop evaporation, devolatilization and others. Holcim also
argued that the carbon monoxide (CO) levels at the Trident kiln are
much lower than the CO levels at the Texas kilns, which will adversely
impact NOX reductions and ammonia slip at the Trident kiln
relative to the Texas kilns. Holcim additionally argued that EPA did
not adequately consider NOX emissions variability in setting
the limit because of the limited time frame considered for the data
from the Texas kilns.
    Response: We disagree. EPA has assumed that 50% reduction is
possible with SNCR; however, this does not rule out the possibility
that Holcim may determine that other means, such as mid-kiln firing,
may be better than SNCR alone in terms of cost or other factors for
achieving 50% NOX reduction. In any event, 50%
NOX reduction is achievable with SNCR and this is supported
by the data cited in the proposed FIP. We address this in more detail
in a response to Ash Grove.
    Holcim also noted that SNCR performance depends upon a wide range
of site-specific factors. They list rate-limiting processes, including
turbulent mixing, heat transfer, spray droplet size, spray drop
evaporation, devolatilization and others. As detailed in a contractor's
report in the docket, we have considered these factors and none of them
causes us to change our decision. In brief, spray droplet size is a
factor the SNCR system designer can control and tailor to the needs of
the system. Turbulent mixing may or may not be within the SNCR system
designer's ability to control, but in any case our selection of SNCR
does not depend on optimal turbulent mixing.
    With respect to CO concentration, if the CO at the Trident kiln is
much lower than at the Texas kilns referred to in the comments, as
Holcim describes, this simply means that the SNCR reagent should be
introduced at a point in the process where the gas temperature is
higher than the injection point used at the Texas kilns where the CO
levels are higher. This may in fact improve SNCR performance.
    With regard to NOX emission variability raised by
Holcim, first, the data used by EPA in Table 10 of the proposed FIP
cover a three month period which should be adequate time to address
normal operating changes that would impact NOX. Second, SNCR
can be used to mitigate variability in NOX emissions. This
is confirmed by the data on the Midlothian kilns that is in the
proposed FIP and as described in response to comments from Ash Grove.