[Federal Register Volume 78, Number 25 (Wednesday, February 6, 2013)]
[Rules and Regulations]
[Pages 8705-8744]
[FR Doc No: 2013-01473]

Vol. 78

Wednesday,

No. 25

February 6, 2013

Part II

Environmental Protection Agency

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40 CFR Part 52

 Approval and Promulgation of Air Quality Implementation Plans; States
of Minnesota and Michigan; Regional Haze State Implementation Plan;
Federal Implementation Plan for Regional Haze; Final Rule

Federal Register / Vol. 78 , No. 25 / Wednesday, February 6, 2013 /
Rules and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R05-OAR-2010-0954; EPA-R05-OAR-2010-0037; FRL-9773-1]

Approval and Promulgation of Air Quality Implementation Plans;
States of Minnesota and Michigan; Regional Haze State Implementation
Plan; Federal Implementation Plan for Regional Haze

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is finalizing a Federal Implementation Plan (FIP) to
implement emission limits that represent Best Available Retrofit
Technology (BART) for certain taconite ore processing facilities in
Minnesota and Michigan. The Clean Air Act (CAA or the ``Act'') and the
regional haze rule require implementation plans to contain BART
emission limits for sources subject to BART in order to meet the
national goal of preventing any future and remedying any existing
impairment of visibility in mandatory class I Federal areas arising
from manmade air pollution.

DATES: This final rule is effective on March 8, 2013.

ADDRESSES: EPA has established a docket for this action under Docket ID
Nos. EPA-R05-OAR-2010-0954 and EPA-RO5-OAR-2010-0037. All documents are
listed on the www.regulations.gov Web site. Although listed in the
index, some information is not publicly available, i.e., 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 Environmental Protection Agency, Region 5, Air and
Radiation Division, 77 West Jackson Boulevard, Chicago, Illinois 60604.
This facility is open from 8:30 a.m. to 4:30 p.m., Monday through
Friday, excluding Federal holidays. We recommend that you telephone
Steven Rosenthal, Environmental Engineer, at<PHONE_NUMBER> before
visiting the Region 5 office.

FOR FURTHER INFORMATION CONTACT: Steven Rosenthal, Environmental
Engineer, Attainment Planning & Maintenance Section, Air Programs
Branch (AR-18J), U.S. Environmental Protection Agency, Region 5, 77
West Jackson Boulevard, Chicago, Illinois 60604,<PHONE_NUMBER>,
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION: Throughout this document, wherever ``we,''
``us,'' or ``our,'' is used, we mean the United States Environmental
Protection Agency (EPA).

Table of Contents

I. Background Information
    A. EPA's Regional Haze Rule and Best Available Retrofit
Technology
    B. EPA's Legal Authority To Promulgate a FIP
    C. Minnesota and Michigan's Regional Haze SIP Submittals
    D. EPA's Regional Haze FIP and Related Actions
II. Comments and Responses
III. What action is EPA taking?
    A. NOX Limits
    B. SO2 Limits
    C. CEMS
    D. Visibility Benefits and Cost Effectiveness
    E. Proposed Disapproval of the States' BART Determinations for
Taconite Facilities
IV. Statutory and Executive Order Reviews

I. Background Information

A. EPA's Regional Haze Rule and Best Available Retrofit Technology

    The regional haze rule required states to submit State
Implementation Plans (SIPs) to implement the rule's requirements by no
later than December 17, 2007. Neither Minnesota nor Michigan submitted
regional haze SIPs by the required date. The Act requires EPA to
promulgate a FIP within two years after EPA finds that a state has
failed to make a required SIP submission unless the state corrects the
deficiency and EPA subsequently approves the SIP. On January 15, 2009,
EPA formally found that both Minnesota and Michigan had failed to
timely submit SIPs addressing the regional haze requirements. This
finding triggered EPA's duty to either promulgate a regional haze FIP
for Minnesota and Michigan or approve subsequently submitted regional
haze SIPs.
    Minnesota subsequently submitted to EPA a regional haze SIP on
December 30, 2009, a draft supplement to the SIP on January 5, 2012,
and a final supplement to the SIP on May 8, 2012. Michigan submitted to
EPA a regional haze SIP on November 5, 2010. In previous rulemakings,
EPA approved in part the states' regional haze SIPs for addressing most
regional haze requirements. However, EPA deferred action on the states'
BART determinations for taconite facilities in order to further
evaluate the sufficiency of those determinations. On August 15, 2012,
EPA proposed to disapprove in part the states' regional haze SIPs with
regards to their BART determinations for taconite facilities, while
simultaneously proposing to promulgate a FIP. In response to comments
received related to the sufficiency of EPA's reasoning for proposing
disapproval of the Michigan and Minnesota BART determinations, EPA is
issuing a separate supplemental notice of proposed rulemaking to
solicit additional comments on that issue. Nonetheless, despite the
fact that EPA has not finalized its disapproval of the states' BART
determinations, EPA has the continuing authority and obligation to
promulgate a FIP based on its earlier finding that Minnesota and
Michigan had failed to timely submit regional haze SIPs. EPA's duty to
promulgate a FIP ends only when it has fully approved a state
submission. EPA has determined that the FIP satisfies the requirements
of the Act and the regional haze rule.
    As described in greater detail in the proposal to this rulemaking
(77 FR 49308, August 15, 2012), section 169A of the 1977 Amendments to
the CAA created a program for protecting visibility in the nation's
national parks and wilderness areas. On December 2, 1980, EPA
promulgated regulations to address visibility impairment in Class I
areas that is ``reasonably attributable'' to a single source or small
group of sources (45 FR 80084, December 2, 1980). In 1990, Congress
added section 169B to the Act to address regional haze issues.
Accordingly, EPA promulgated a rule to address regional haze on July 1,
1999 (64 FR 35714), which is codified at 40 CFR part 51, subpart P
(``the regional haze rule''). On July 6, 2005, EPA published guidelines
to assist states, or EPA when implementing a FIP, in determining which
of their sources should be subject to the BART requirements and in
determining appropriate emission limits for each applicable source (70
FR 39104), codified at 40 CFR part 51, appendix Y (``BART
Guidelines'').
    Among other things, section 169A of the Act and 40 CFR 51.308 of
the regional haze rule require that states, or EPA when implementing a
FIP, assure reasonable progress toward the national goal of achieving
natural visibility conditions in Class I areas by submitting an
implementation plan that contains emission limits representing BART for
certain BART-eligible sources. 40 CFR 51.308(d) and (e). Pursuant to 40
CFR 51.308(e), BART must be determined based upon an analysis of the
best

system of continuous emission control technology available and
associated emission reductions achievable for each BART-eligible source
that is subject to BART. In this analysis, the state, or EPA when
implementing a FIP, must take into consideration the technology
available, the costs of compliance, the energy and air quality
environmental impacts of compliance, any pollution control equipment in
use at the source, the remaining useful life of the source, and the
degree of visibility improvement reasonably anticipated to result from
the use of such technology. CAA section 169A(g)(2); 40 CFR
51.308(e)(1)(ii)(A).
    The process of establishing BART emission limits consists of three
steps. First, states or EPA identify those sources that meet the
definition of ``BART-eligible source'' set forth at 40 CFR 51.301.
Second, states or EPA determine whether such sources ``emit any air
pollutant which may reasonably be anticipated to cause or contribute to
any impairment of visibility in any such area,'' and is therefore
``subject to BART.'' Third, for each source subject to BART, states or
EPA then identify the appropriate type and level of control for
reducing emissions by conducting a five-step analysis: step 1: identify
all available retrofit control technologies; step 2: eliminate
technically infeasible options; step 3: evaluate control effectiveness
of remaining control technologies; step 4: evaluate impacts and
document the results; step 5: evaluate visibility impacts. See BART
Guidelines.
    The regional haze rule required all states to submit an
implementation plan for regional haze meeting the requirements of 40
CFR 51.308(d) and (e) by no later than December 17, 2007. 40 CFR
51.308(b). Neither Minnesota nor Michigan submitted regional haze SIPs
to EPA by the required date.

B. EPA's Legal Authority To Promulgate a FIP

    Section 110 of the Act requires states to develop implementation
plans with enforceable emission limitations and other control measures
to meet the applicable requirements of the Act. A state submits its
SIPs and SIP revisions to EPA for approval. Congress crafted the Act to
provide for states to take the lead in developing SIPs, but balanced
that decision by requiring EPA to review the plans to determine whether
a SIP meets the requirements of the Act. EPA is required to determine
whether the state's submittal meets the requirements of the Act based
on information and data available at the time of EPA's review. See
Sierra Club v. EPA, 671 F.3d 955 (9th Cir. 2012).
    Pursuant to section 110(c)(1)(A) of the Act, if EPA finds that a
state has failed to make a required SIP submittal or if EPA finds that
a state's required submittal is incomplete, then EPA is required to
promulgate a FIP to fill this regulatory gap. Section 110(c)(1)(A) of
the Act requires EPA to promulgate a FIP within two years of its
finding that a state failed to make a required SIP submission. Further,
EPA has a continuing duty to promulgate a FIP even where EPA fails to
promulgate a FIP within the required two-year period. EPA's duty to
promulgate a FIP continues unless the state corrects the deficiency,
and EPA approves the plan or revision before EPA promulgates the
FIP.\1\
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    \1\ It should be noted that in addition to the requirements of
section 110(c)(1)(A) of the Act, section 110(c)(1)(B) of the Act
requires EPA to promulgate a FIP where EPA has specifically
disapproved a state's SIP submittal. Correspondingly, EPA has a
continuing duty to promulgate the FIP unless a state corrects the
deficiency and EPA approves the plan or revision before EPA
promulgates the FIP. Many of the commenters to the proposed FIP
assumed that the statutory basis for EPA's authority in promulgating
this FIP is section 110(c)(1)(B) of the Act. We acknowledge that the
proposed FIP, in identifying potential inadequacies in the Minnesota
and Michigan regional haze SIPs, may have given the impression that
the authority for promulgating the FIP was a specific determination
by EPA that the States' SIPs failed to meet the requirements of the
Act and the regional haze rule. However, as clarified in this
section, the authority for the promulgation of the FIP arises from
section 110(c)(1)(A) of the Act.
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    In this rulemaking action, EPA has the authority to promulgate a
FIP addressing the BART determinations of certain taconite facilities
in Minnesota and Michigan based upon the failure of both Minnesota and
Michigan to timely submit regional haze SIPs. As discussed above, the
regional haze rule required all states to submit a regional haze
implementation plan by December 17, 2007. 40 CFR 51.308(b). Neither
Minnesota nor Michigan submitted regional haze SIPs to EPA by the
required date. Therefore, on January 15, 2009, EPA found that Michigan
and Minnesota, as well as certain other states, had failed to submit
SIPs addressing the regional haze requirements (74 FR 2392). Based upon
that finding, pursuant to section 110(c)(1)(A) of the Act, EPA was
under a continuing duty to promulgate FIPs for Minnesota and Michigan
to address the regional haze requirements of the Act and the regional
haze rule. This FIP is promulgated pursuant to the requirements of
section 110(c)(1)(A) of the Act.

C. Minnesota and Michigan's Regional Haze SIP Submittals

    Minnesota subsequently submitted to EPA a regional haze SIP on
December 30, 2009, a draft supplement to the SIP on January 5, 2012,
and a final supplement to the SIP on May 8, 2012. Michigan submitted to
EPA a regional haze SIP on November 5, 2010. In general, with regard to
the subject-to-BART taconite facilities identified in the respective
plans, each State identified Good Combustion Practices (GCP) as the
primary control method representing BART for NOX.
    On January 25, 2012, EPA proposed approval of the Minnesota
regional haze plan in which EPA, among other things, proposed to
approve BART for the subject-to-BART taconite facilities (77 FR 3681).
However, prior to EPA's final action on Minnesota's regional haze plan
on June 12, 2012, EPA learned through public comment that Minnesota and
Michigan had each failed to thoroughly analyze all feasible BART
control technologies for the taconite facilities, and that the
SO2 and NOX emission limits set forth in each
State's SIP might not reflect BART. Therefore, in light of the
uncertainty pertaining to the States' BART determinations for taconite
facilities, EPA deferred action on emission limits that Minnesota
intended to represent BART for taconite facilities in the final rule
approving the Minnesota regional haze SIP (77 FR 34801, June 12, 2012).
Correspondingly, EPA proposed approval of certain provisions of the
Michigan regional haze SIP, while deferring any action on those
provisions of the SIP that addressed the requirement for BART for the
one taconite plant in Michigan to which BART applies (77 FR 46912,
August 6, 2012). Pursuant to section 110(k)(3) of the Act, EPA may
approve a SIP revision in part when only a portion of a SIP revision
meets all applicable requirements of the Act.

D. EPA's Regional Haze FIP and Related Actions

    EPA proposed a FIP on August 15, 2012 (77 FR 49308) pursuant to
section 110(c)(1)(A) of the Act, based on EPA's finding that Minnesota
and Michigan failed to timely submit a regional haze SIP, and EPA's
continuing duty to promulgate a FIP to address such failure. At the
same time, EPA proposed disapproval of the BART determinations for the
subject-to-BART taconite facilities made by Minnesota and Michigan for
failing to meet the requirements of the Act and the regional haze rule.
However, in regards to the proposed disapproval, several

commenters raised concerns that EPA did not provide adequate notice of
its rationale for disapproving the States' BART determinations.
    Therefore, EPA is taking two separate but related actions. In this
rulemaking action, EPA is finalizing the FIP for BART for the subject
taconite plants in Michigan and Minnesota. Secondly, in a separate
action, EPA is issuing and seeks comment on a supplemental notice of
proposed rulemaking elaborating upon the Agency's rationale for
proposing partial disapproval of the Minnesota and Michigan SIPs as
they pertain to the requirement for BART for taconite plants. The full
basis for the partial disapproval is set forth in the separate action.

II. Comments and Responses

    On August 15, 2012, EPA published a Federal Register Notice
entitled ``Approval and Promulgation of Implementation Plans; States of
Minnesota and Michigan; Regional Haze Federal Implementation Plan'' (77
FR 49308). In this notice, the EPA requested comment on EPA's proposed
BART determinations and FIP for taconite ore processing facilities
located in Minnesota and Michigan. Public comments were accepted at
both a public hearing held in St. Paul, Minnesota, on August 29, 2012,
and in writing until September 28, 2012.
    EPA received comments from Cliffs Natural Resources Inc.,
ArcelorMittal Minorca Mine Inc., the United States National Park
Service (NPS), the Michigan Department of Environmental Quality (MDEQ),
the United States Forest Service, the National Parks Conservation
Association (NPCA), the Fond du Lac Band of Lake Superior Chippewa, the
Leech Lake Band of Ojibwe, the National Tribal Air Association, the Red
Cliff Band of Lake Superior Chippewas, U.S. Steel Corporation, and more
than 1,000 private citizens.

A. General Comments in Support of the Proposed Rule

    Commenter: National Parks Conservation Association.
    Comment: NPCA supports finalization and implementation of the
proposed controls, which will significantly benefit the air quality in
the parks, wilderness areas, and communities surrounding these plants.
    Commenter: 1,244 private citizens provided similar comments.
    Comment: As a resident of the upper Midwest and a national parks
supporter, I want to see natural air quality restored to Voyageurs and
Isle Royale National Parks and Boundary Waters Canoe Area Wilderness
just as Congress intended. That's why I support EPA's proposal to
reduce haze-causing pollution from taconite plants. These large
industrial polluters should clean up their air pollution under the
Regional Haze Rule.
    Reducing haze pollution in our parks will bring healthier air to
surrounding communities as well as more visitors who support our local
economies. That's why I want EPA to require the most effective methods
for reducing air pollution from taconite plants in Michigan and
Minnesota. In addition to the emission reductions outlined in EPA's
proposed plan, I encourage EPA to evaluate pollution controls that
would lead to cleaner air.
    Commenter: Fond du Lac Band of Lake Superior Chippewa.
    Comment: The Band strongly supports the FIP proposed by Region 5,
particularly with regard to Region 5's determination that low
NOX burners are BART for taconite facilities. This option is
technically feasible as these burners have already been installed on
Minntac's grate-kiln furnaces and are being installed on Essar's
straight-grate kiln furnaces. Low NOX burners have been
shown to be affordable with control costs at roughly $500 per ton,
which is well within the range of costs deemed affordable for BART by
states and EPA. Low NOX burners are a wise choice because
they prevent NOX from ever being formed. This is a key
concept in pollution prevention. Collection and disposal of pollutants
can lead to secondary environmental problems, as well as increased
energy consumption. The Band contends that installation of these
burners is an equity issue. It would be unfair to allow other
facilities to operate indefinitely without having to install low
NOX burners.
    Commenter: Red Cliff Band of Lake Superior Chippewa.
    Comment: Red Cliff supports EPA's proposed requirement for low
NOX burners for all subject taconite furnaces in Michigan
and Minnesota.
    Commenter: Leech Lake Band of Ojibwe.
    Comment: Low NOX burners have been installed
voluntarily, previous to this action, by two taconite facilities with
different furnace systems commonly utilized in the taconite industry.
These system installs have shown substantial reductions, up to 60 to 70
percent, can be achieved with a minimal cost of $500 per ton or less.
The Band also agrees that taking a preemptive approach by preventing
the formation of NOX makes sense versus an after-production
control technology that is less effective and more costly, both
economically and environmentally.
    Commenter: National Tribal Air Association.
    Comment: The Association agrees that using low NOX
burners as BART for both straight and grate-kilns is a good approach.
Not only is the cost to remove NOX inexpensive, but these
burners can reduce NOX by up to 70 percent. Therefore,
placing a limit on NOX of 1.20 pounds per million British
Thermal Units on a 30-day rolling average for facility lines is very
reasonable.
    Commenter: National Park Service.
    Comment: NPS agrees with EPA's conclusions that control of
emissions from taconite plants in Minnesota and Michigan can be
expected to yield significant benefits in reducing visibility
impairment in the Class I area in the two states; and that technically
feasible controls are available at a reasonable cost for taconite
plants that can be expected to provide a visibility benefit that makes
those controls warranted.
    Commenter: U.S. Forest Service.
    Comment: The Forest Service supports the proposed FIP to require
BART for the taconite plants in Minnesota and Michigan. According to
technical analyses by the State of Minnesota and others, the highest
contributors to haze in the Boundary Waters from all sources in the
U.S. are the taconite industry and power plants. We support the
emission controls that the taconite plants would be required to install
under the proposed FIP. The FIP demonstrates that these controls are
technically feasible and available for the taconite industry to reduce
emissions and are already being used by some within the industry. The
implementation of the Minnesota regional haze plan is nearly five years
past due. Considerable effort and resources have been spent over the
past ten years developing the technical information necessary to
complete implementation. Much of the technical work was done by states,
Tribes, and FLMs working together through multi-state regional planning
organizations. The Forest Service has monitored visibility in the
Boundary Waters since 1985. The results of this technical work and
monitoring support the requirement for BART to reduce impacts to the
Boundary Waters.
    Response: EPA acknowledges these commenters' support of the
Agency's efforts in developing a FIP for the taconite industry and
agrees.

B. Comments Concerning the Adequacy of the Public Comment Period

    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs stated that EPA provided inadequate opportunity to

comment on the proposed FIP. Cliffs alleged that 45 days was not a
reasonable time period to complete the task of preparing an appropriate
response to the proposed FIP given the highly technical concerns
surrounding EPA's BART determinations for the taconite industry.
    Response: EPA disagrees that the Agency did not provide an adequate
opportunity for public comment. Section 307(h) of the CAA requires EPA
to provide ``a reasonable period for public participation of at least
30 days'' when promulgating a FIP. Here, EPA chose to provide a
significantly longer 45-day public comment period in light of the many
technical issues surrounding EPA's proposed BART determinations for the
taconite industry. EPA believes that 45 days was a reasonable amount of
time for Cliffs and others to comment on EPA's proposed FIP.\2\ Cliffs'
assertion that it should have been granted an extension to conduct a
new BART analysis is without merit. Cliffs had several years to conduct
a thorough BART analysis, and its failure to timely do so does not bear
upon the reasonableness of the length of EPA's comment period. Indeed,
the fact that Cliffs was able to prepare an extensive 61-page comment
document within the allotted time supports EPA's contention that 45
days was a reasonable period for third parties to comment on the
proposed FIP.
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    \2\ In fact, Cliffs received a signed copy of the proposed FIP
on July 17, 2012, nearly a full month before the formal start of the
comment period. Thus, Cliffs had effectively 75 days to prepare its
comments.
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C. Comments Questioning EPA's Authority To Issue a Federal
Implementation Plan

    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs stated that EPA has not met the threshold
requirements for issuing a FIP. EPA's proposed FIP did not provide a
critique of Minnesota and Michigan's BART determinations for the
taconite industry or explain why those determinations were inadequate.
As a result, Cliffs argued that EPA does not have the legal authority
to issue a FIP.
    Response: EPA believes that it has a strong basis for proposing
disapproval of Minnesota and Michigan's BART determinations for the
taconite industry. Nonetheless, EPA agrees that the proposed rule did
not provide a sufficiently detailed critique of the state
determinations' inadequacies. As a result, EPA has chosen to issue a
supplemental notice of proposed rulemaking providing additional
rationale for the Agency's proposed disapproval. Contrary to Cliffs'
assertion, however, EPA was not required to make a finding that
Minnesota and Michigan's BART determinations were deficient before
issuing a FIP. Section 110(c)(1)(A) of the CAA provides that EPA
``shall promulgate a [FIP] within 2 years after the Administrator finds
that a State has failed to make a required submission * * * unless the
State corrects the deficiency, and the Administrator approves the plan
or plan revision, before the Administrator promulgates such Federal
Implementation plan.''
    Pursuant to the regional haze rule, states were required to submit
regional haze SIPs no later than December 17, 2007 (64 FR 35714, July
1, 1999). Neither Minnesota nor Michigan made the required submission
by this date. Consequently, EPA issued a finding on January 15, 2009
that Minnesota and Michigan, as well as certain other states, had
failed to submit SIPs addressing the regional haze requirement (74 FR
2392). This finding triggered EPA's statutory duty to either approve a
subsequent state SIP submission or issue a FIP. While it is true that
Minnesota and Michigan subsequently submitted regional haze SIPs to
EPA, the Agency has not approved either of these plans with respect to
the states' BART determinations for the taconite industry. On the
contrary, EPA has proposed to disapprove the states' BART
determinations for failure to meet the minimum requirements of the CAA.
Thus, EPA had both the authority and the continuing obligation to issue
a FIP for the taconite industry in Minnesota and Michigan based on the
Agency's January 15, 2009 finding of the states' failure to submit.
    Commenter: Michigan Department of Environmental Quality (MDEQ).
    Comment: MDEQ commented that Section 110(c)(1) of the Act
authorizes EPA to promulgate a FIP within two years after making a
finding that a state's SIP submittal does not satisfy the CAA. However,
the CAA does not allow EPA to propose a FIP and simultaneously propose
disapproval of the state's SIP.
    Response: MDEQ's interpretation of section 110(c)(1) is incorrect.
Once EPA has made a finding of a state's failure to submit, EPA's
authority and continuing obligation to issue a FIP does not end until
the state has corrected the deficiency and EPA has approved a
subsequently submitted SIP. Nowhere in the CAA is there language that
limits EPA's authority to simultaneously propose a FIP and propose
disapproval of a state's SIP where there has been a prior finding of a
failure to submit.
    Commenter: Cliffs Natural Resources, ArcelorMittal Minorca Mine,
and Michigan Department of Environmental Quality (MDEQ).
    Comment: Cliffs and MDEQ stated that EPA failed to afford the
Minnesota and Michigan SIP proposals the requisite deference. Under the
visibility program, states have the primary responsibility for
establishing standards, including BART. Thus, Cliffs and MDEQ argued
that EPA can disapprove a SIP only where it fails to meet minimum CAA
requirements.
    Response: While Congress intended states to take the lead in
developing regional haze SIPs, it balanced that decision by requiring
EPA to review state plans to determine whether they meet the
requirements of the CAA. EPA's review is not limited to a ministerial
type of automatic approval of a state's decisions. Rather, EPA must
consider not only whether the state considered the appropriate factors,
but whether the state acted reasonably in doing so. In undertaking such
a review, EPA does not ``usurp'' the state's authority, but ensures
that such authority is reasonably exercised.
    Here, EPA firmly maintains that neither state's regional haze SIP
met the minimum requirements of the CAA. Among other things, EPA takes
issue with the states' assertions that low NOX burners are
not technically feasible control options for indurating furnaces and
that good combustion practices represent BART. Nonetheless, EPA
acknowledges that its August 15, 2012 proposed action (77 FR 49308) did
not provide a sufficiently detailed analysis of the deficiencies of the
states' BART determinations for the taconite industry. Therefore, EPA
is publishing a supplemental notice of proposed rulemaking that further
addresses the Agency's rational for proposing disapproval of the
states' choices regarding taconite BART.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that Minnesota and Michigan engaged in
extensive and proper rulemaking efforts. Cliffs then proceeded to
provide a detailed history of each state's SIP-development process.
    Response: EPA agrees that Minnesota and Michigan spent considerable
time and effort preparing their regional haze SIPs. As stated
previously, EPA intends to publish a supplemental notice of proposed
rulemaking that further addresses the Agency's rationale for proposing
disapproval of Minnesota and Michigan's BART determinations for
taconite facilities. EPA reiterates, however, that the Agency had the

authority and continuing obligation to promulgate a FIP for the
taconite industry based on the Agency's earlier finding that Minnesota
and Michigan had failed to submit regional haze SIPs in a timely manner
(74 FR 2392, January 15, 2009).

D. Comments Supporting EPA's Authority To Issue a Federal
Implementation Plan

    Commenter: National Parks Conservation Association.
    Comment: At a public hearing on the proposed FIP, representatives
for one taconite owner asserted that EPA lacked authority to issue the
proposed FIP. The company's assertion has no merit. In fact, EPA has an
obligation to develop a FIP under the CAA. The CAA provides states with
initial responsibility for identifying sources and determining BART for
purposes of regional haze. It is equally clear, however, that EPA
retains authority to approve or disapprove the states' determinations
and issue a FIP if necessary to correct state plan deficiencies.
    EPA is not only well within its authority to promulgate the
proposed FIP; it is required to do so because the state plans do not
meet the requirements of the CAA. While commenters disagree with some
of EPA's proposed BART determinations in the taconite FIP, the record
plainly supports EPA's finding that neither the Minnesota nor the
Michigan proposal met minimum CAA requirements. The National Park
Service, the National Forest Service, and other commenters all
submitted detailed technical reviews establishing the many deficiencies
in the BART analysis and conclusions of Minnesota and Michigan's plans.
    Response: EPA agrees with the commenter that EPA has the authority
and obligation to issue a FIP.

E. Comments Concerning the Use of New Information To Evaluate Minnesota
and Michigan's BART Determinations

    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA cannot use new information
regarding the technical feasibility of low NOX burners as a
control option for indurating furnaces to undermine the states' BART
determinations. Cliffs argued that EPA is seeking to reject Minnesota
and Michigan's BART determinations based on information that was not
available to either state at the time of their SIP submissions to EPA
for approval. To support its position, Cliffs pointed to EPA's BART
Guidelines, which state that new technologies need only be considered
by a state if they become available before the close of a state's
public comment period. Cliffs alleged that low NOX burners
were not an ``available'' technology because testing at Minntac and
Essar had either not yet commenced or was still ongoing at the time
Minnesota and Michigan's periods for public comment had ended.
    Commenter: Michigan Department of Environmental Quality (MDEQ).
    Comment: MDEQ commented that there was not enough information
available prior to the close of Michigan's public comment period on
June 23, 2010 to indicate that low NOX burners had been
successfully utilized on indurating furnaces. MDEQ also argued that
EPA's proposal to find that low NOX burners represent BART
for NOX at Tilden was impermissibly based on information
generated after the close of Michigan's public comment period.
    Response: EPA disagrees with Cliffs and MDEQ's comments for several
reasons. First, EPA again reiterates that the Agency had the authority
and responsibility to promulgate a FIP for the taconite industry based
on the Agency's earlier finding that Minnesota and Michigan had failed
to submit regional haze SIPs in a timely manner (74 FR 2392, January
15, 2009). Thus, EPA was entitled to rely on whatever information was
available regarding the technical feasibility of low NOX
burners at the time the Agency performed its BART analysis, including
results from the testing at Minntac and Essar.
    Nonetheless, even if EPA's authority to promulgate a FIP had been
based solely on final disapproval of the states' BART determinations,
the information regarding the technical feasibility of low
NOX burners was not ``new'' as Cliffs suggests. As the BART
Guidelines make clear, technical feasibility encompasses two distinct
concepts, ``availability'' and ``applicability.'' 40 CFR part 51,
appendix Y. A technology is considered ``available'' if the source
owner may obtain it through commercial channels, while it is considered
``applicable'' if it can reasonably be installed and operated on the
source type under consideration. As Cliffs pointed out, only
technologies that are ``available'' at the close of a state's public
comment period need be considered as control options by the state.
    However, Cliffs' argument that low NOX burners were not
an ``available'' technology at the time Minnesota and Michigan's
periods for public comment had ended is incorrect. Testing at Minntac
and Essar had nothing to do with the ``availability'' of low
NOX burners. Rather, the testing at those facilities
concerned the ``applicability'' of low NOX burners to the
source type in question--indurating furnaces. There can be no dispute
that low NOX burners were ``available'' at the time that
Minnesota and Michigan developed their regional haze SIPs because this
technology has been obtainable through commercial channels as an option
for the control of nitrogen oxide emissions for many years. Therefore,
Minnesota and Michigan were required to consider low NOX
burners in their BART analyses, which both states did, albeit
dismissively.
    Consequently, the sole question presented to the states was one of
``applicability''--whether low NOX burners could be
successfully installed on indurating furnaces. In regards to this
question, the BART Guidelines make clear that ``a commercially
available control option will be presumed applicable if it has been
used on the same or a similar source type.'' 40 CFR part 51, appendix
Y. However, in contrast to the question of ``availability,'' the
Guidelines make no mention of a cut-off date after which states may
reject information regarding a technology's ``applicability.'' Even so,
contrary to Cliffs' assertions, both states were aware that low
NOX burners had been successfully installed on two lines at
U.S. Steel's Minntac facility prior to the end of their respective
periods for public comment.\3\ In a June 23, 2010 letter to the
Michigan Department of Natural Resources and Environment regarding the
state's draft regional haze SIP, EPA commented that ``a low-
NOX main burner firing solid fuels'' had been installed at
Minntac and that ``work done by other companies had demonstrated that
burner designs that lower flame temperature can reduce NOX
formation in taconite furnaces.'' \4\ Similarly, in a February 10, 2012
letter to the Minnesota Pollution Control Agency responding to the
state's draft regional haze SIP supplement for taconite facilities, EPA
explained in detail that ``U.S. Steel has demonstrated the development
and use of low NOX main burners that achieve 70 percent
NOX reduction on its indurating

lines.'' \5\ In addition to these comments, both states received
comments regarding the technical feasibility of low NOX
burners from the Forest Service as well. Therefore, both Michigan and
Minnesota were aware that low NOX burners had been
successfully applied to indurating furnaces, and Cliffs' arguments that
the results of these studies somehow constitute ``new'' information are
without merit.
---------------------------------------------------------------------------

    \3\ The comment period for Michigan's regional haze SIP closed
on June 23, 2010. The comment period for the Minnesota's regional
haze SIP supplement regarding BART at taconite facilities closed on
February 3, 2010, but EPA was granted an extension to submit
comments. EPA's comments were submitted on February 10, 2010, and
were received and considered by MPCA.
    \4\ See Michigan Regional Haze plan: EPA Letter to Michigan
Department of Environmental Quality Regarding BART, May 24, 2012
(Docket  EPA-R05-OAR-2010-0954-0008).
    \5\ See MI Haze FIP, EPA 6-23-10 comments to MDEQ on MI Haze
submittal (Docket  EPA-R05-OAR-2010-0954-0037).
---------------------------------------------------------------------------

    Finally, even if information regarding the technical feasibility of
installing low NOX burners to indurating furnaces was not
available to Minnesota or Michigan, EPA nonetheless had a duty to
consider any new information that subsequently arose when reviewing the
states' SIPs. The Ninth Circuit recently held that ``if new information
indicates to EPA that an existing SIP or SIP awaiting approval is
inaccurate or not current, then, viewing air quality and scope of
emissions with public interest in mind, EPA should properly evaluate
the new information and may not simply ignore it without reasoned
explanation of its choice.'' Sierra Club v. EPA, 671 F.3d 955, 967 (9th
Cir. 2012). Thus, EPA is required, at a minimum, to take new
information into account during the SIP approval process and, if
necessary, alter its final decision accordingly.
    Commenter: Fond du Lac Band of Lake Superior Chippewa.
    Comment: At the public hearing held in Saint Paul, Minnesota, on
August 29, 2012, some commenters voiced the opinion that low
NOX burners should not be considered as BART because the
technology was brought forward after the comment period on the
Minnesota regional haze SIP supplement had closed. This is incorrect.
Low NOX burners were in use and under consideration both
before and during the comment period of December 19, 2011 to February
3, 2012. Discussions concerning the installation of low NOX
burners at Minntac began in 2008, and the burners themselves were
installed in 2010, several months before the regional haze SIP
supplement was proposed. U.S. Steel's report to MPCA on the performance
to-date of their low NOX burners at Minntac was submitted in
December of 2011, around the time that Minnesota's SIP supplement went
on public notice. Additionally, Essar Steel committed to the use of low
NOX burners in its new plant near Nashwauk in 2010. The
record indicates that discussions took place between MPCA and the
taconite facilities around the time that the SIP supplement public
comment period was open. Because of the timing of U.S. Steel's reports
and the fact that no other economically-feasible technology offered
more than 15 percent control of NOX, those discussions
almost certainly included the possibility of requiring low
NOX burners on taconite furnaces.
    In light of the emerging use of low NOX burners, the
U.S. Steel report, and the discussions indicated in the record, there
is no basis for the claim that low NOX burners were only
brought forward after the comment period. Low NOX burner
technology was not a surprise and there is no procedural unfairness in
the EPA considering it. Furthermore, to the extent that low
NOX burners can somehow be construed as new information,
there is precedent for considering new information while promulgating
regulations. For example, on July 20, 2012, EPA informed petitioners
that it would reconsider its Mercury and Toxics Standards based on the
availability of new technical information.
    Commenter: National Parks Conservation Association.
    Comment: During the public hearing on this matter, a taconite
company asserted that EPA's FIP was based on ``new information'' that
is ``outside the record'' and that the company's ``due process'' rights
were somehow jeopardized by EPA's proposal. As a legal matter, the
company's argument has no merit. Likewise, as a practical matter, the
company's complaints are unavailing.
    Response: EPA agrees with these commenters that it was appropriate
for EPA to rely on whatever information was available regarding the
technical feasibility of low NOX burners at the time the
Agency performed its BART analysis. For a more detailed discussion of
this issue, see EPA's previous response to comments from Cliffs,
ArcelorMittal, and MDEQ.

F. Comments Concerning EPA's Best Available Retrofit Technology
Analysis

    Commenter: National Parks Service.
    Comment: NPS agrees with EPA and with Michigan and Minnesota on the
BART-eligibility determinations with respect to the taconite facilities
and the states' determination that BART for direct PM is satisfied by
the taconite MACT rule.
    Response: EPA acknowledges NPS's support.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs objected to EPA's reference to conversations with
industry competitors and their vendors in determining the feasibility
of controls for Cliffs' indurating furnaces. Cliffs asserted that EPA
ignored information provided by Cliffs and its process engineering
firms.
    Response: EPA spent significant time with all affected sources and
thoroughly considered all information. EPA acknowledges that it relied
heavily upon documented information from Cliffs' competitors in the
taconite industry because these companies have experience with low
NOX burner technology and provided data from actual
experience with such technology. It would have been inappropriate for
EPA to have ignored substantive information based upon actual
experience.
1. Comments Asserting That EPA's BART Analysis Did Not Assess all
Available Technologies
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs claimed that EPA's BART determinations were
arbitrary because they ignored good combustion practices (GCP) as a
BART alternative. Cliffs stated at the MPCA March Citizens Board
meeting that ``GCP is already required under other federal regulations,
including the taconite MACT rule.''
    Response: Cliffs' support of GCP as BART lacks merit because GCP is
neither defined by the Minnesota Pollution Control Agency, nor is it
typically considered a NOX reduction technique. For example,
the January 30, 2009 ``NOX Reduction Analysis'' done by
Hatch for U.S. Steel's Minntac Iron Ore Pelletizing Operation did not
list GCP as a potential NOX reduction technology for an
indurating furnace.\6\ Similarly, the 2008 BACT analysis for JEA--
Greenland Energy Center Units 1 and 2 did not list GCP as a potential
NOX control.\7\ In fact, these analyses state that GCP tends
to increase NOX emissions. This is because measures taken to
minimize the formation of NOX during combustion inhibit
complete combustion, which increases emissions of carbon monoxide.
Conversely, GCP aims to reduce carbon monoxide emissions. According to
the September 2010 ``We Energies Biomass Energy Project Revised Control
Technology Review for Carbon Monoxide Emissions for the Biomass-Fired
Boiler,'' there is an inverse relationship between NOX
emissions and carbon monoxide emissions, which means that improving

combustion efficiency can increase NOX emissions.\8\
---------------------------------------------------------------------------

    \6\ Docket  EPA-R05-OAR-2010-0037-0039.
    \7\ Docket  EPA-R05-OAR-2010-0037-0070.
    \8\ Docket  EPA-R05-OAR-2010-0037-0069.
---------------------------------------------------------------------------

    Concerning the GCP requirement in the taconite MACT rule, GCP for
the MACT is not the same as GCP for NOX. GCP for MACT is
aimed at reducing emissions of products of incomplete combustion (PIC).
To minimize PICs, the operating conditions targeted are generally the
opposite from those targeted for reducing NOX. As explained
in the taconite MACT rule (68 FR 61883, October 30, 2003), ``The basic
method used in reducing NOX emissions is a reduction in
combustion temperature, which is the opposite strategy needed for
minimizing PIC (i.e., increasing combustion temperature).'' In
conclusion, GCP would be expected to increase NOX emissions,
not decrease them.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA is required to consider ``any
existing pollution control technology at the source.'' Cliffs argued
that EPA failed to adequately consider or consistently apply this
threshold factor to the BART determinations in its proposed rule.
    Response: To the extent that Cliffs is referring to its use of GCP
as an existing pollution control technology, neither the operational
practices that comprise GCP nor their impact on reducing emissions has
been documented by Cliffs. As described in detail in the response to
the previous comment, EPA does not consider Cliffs' use of GCP to
constitute ``existing control technology'' on these furnaces.
    Commenter: National Parks Conservation Association.
    Comment: NPCA commented that EPA failed to consider fuel-blend
alternatives, including greater or exclusive use of natural gas at
grate-kiln furnaces, as part of the Agency's BART analysis for
SO2 and NOX. Fuel-blend alternatives are a
technically feasible control option because indurating furnaces can
successfully be operated on alternative fuels, namely fuel blends that
consist primarily of natural gas. Contrary to the taconite plant
owners' assertions, consideration of alternative fuels is required for
BART where changing to cleaner fuel would not necessitate significant
changes at any existing facility. There is no legal rationale for
excluding this viable pollution control. Additionally, the assertion
that alternative fuel costs are uncertain has no merit. There is simply
no factual support for price uncertainty being a basis to reject
consideration of natural gas as an alternative to coal. Even if
significant uncertainty existed, it can be dealt with appropriately in
the BART analysis. Finally, the assertion that moving towards a more
natural gas-based fuel blend would mean higher NOX emissions
in exchange for lower SO2 emissions is a red herring. The
existence of such potential secondary impacts is not a reason to
discard a BART option prior to analysis. It is a reason to perform the
analysis itself.
    Response: Alternative fuels were not considered for the following
reasons. The straight-grate furnaces at ArcelorMittal, Hibbing
Taconite, and Northshore Mining already burn natural gas. Similarly,
U.S. Steel's Keetac and Minntac facilities already burn a fuel mix of
natural gas and low-sulfur coal. While fuel-blend alternatives could
have been considered for the grate-kiln furnaces at United Taconite and
Tilden, EPA proposed to require the most stringent control technology,
flue-gas desulfurization (FGD), at these facilities. As the BART
Guidelines make clear, where EPA or the states choose the most
stringent control option as BART, other control options need not be
considered. Therefore, EPA was not required to consider fuel-blend
alternatives as part of the Agency's BART analysis. However, EPA notes
that subsequent to the proposal, Tilden agreed to convert to natural
gas, while United Taconite will be substantially reducing its emissions
through the use of natural gas and low-sulfur coal.
    Commenter: National Parks Conservation Association.
    Comment: EPA's NOX BART determinations conclude that
significant reductions could be achieved cost-effectively by the
installation of low NOX burners at all taconite kilns. While
NPCA concurred with this conclusion, it commented that EPA failed to
fully consider the use of regenerative selective catalytic reduction
(RSCR). For instance, although RSCR was noted as an available
technology in Keetac's BART analysis, EPA's FIP made no note of it. For
Tilden, on the other hand, EPA noted this option, but only to point out
that the company found it to be infeasible. In fact, this technology
appears to be feasible for indurating furnaces. At a minimum, a more
thorough evaluation by EPA is necessary. In this case, EPA has not
shown that circumstances preclude the application of RSCR to the units
in question via evaluation of gas characteristics or demonstration of
technical challenges. It has offered no evidence that RSCR is
technically infeasible. A fuller evaluation of this technology is
warranted as part of a BART determination.
    Response: EPA did evaluate post-combustion NOX-control
options when it reviewed Minnesota's regional haze plan and agreed with
the state's determination that post-combustion control of
NOX emissions from taconite facilities are not BART. For the
proposed and now final rule, EPA evaluated new data on the use of low
NOX burners at taconite facilities and, after a five-factor
BART analysis, determined that low NOX burners are BART for
these facilities. The BART analyses are fully described in section V of
the proposed rule (77 FR 49308). EPA also considered RSCR and related
selective catalytic reduction technologies at some of the subject
taconite units. EPA concluded in its BART analyses that RSCR and other
post-combustion controls do not represent BART for the subject taconite
units because, after the installation of low NOX burners,
the incremental costs of installing further post-combustion controls
are unreasonably high. Therefore, this final rule requires that
taconite indurating furnaces meet NOX emission limits
consistent with low NOX burner technology.
    Commenter: National Parks Conservation Association.
    Comment: EPA's analysis for SO2 provides evidence that
dry FGD is feasible for taconite facilities, and the Agency requires
the use of this technology at the three highest emitting lines (at
United Taconite and Tilden). We support these determinations. However,
EPA fails to fully analyze the use of dry FGD on the lower-emitting
units, instead concluding, without support, that it would not be
``economically reasonable.'' NPCA asks that EPA analyze whether dry
FGD, clearly a feasible technology, could provide cost effective
reductions at additional units.
    Response: EPA's BART analysis demonstrated that dry FGD is feasible
for the highest emitting lines when those lines are uncontrolled, but
determined that the same technology has unreasonably high incremental
costs for units with lower uncontrolled emissions. EPA notes, however,
that while FGD was originally proposed as BART for the units at United
Taconite and Tilden, those facilities have since agreed to operational
limits on the types of fuels that may be burned As a result, FGD is no
longer being required as BART. Additional discussion of this issue can
be found in section III of the preamble.
    Commenter: National Parks Service.
    Comment: It appears that low temperature oxidation is technically
and economically feasible for the entire

industry. In addition, tail-end SCR with natural gas reheat has been
found technically feasible and borderline economically feasible based
on a BACT analysis from several years ago when natural gas prices were
much higher. Another form of SCR, RSCR looks promising, but as a new
technology, would require trials.
    While we would normally prefer to see all of the technically
feasible control options evaluated, given the time constraints and the
success of the low NOX burner technology, it is likely that
low NOX burners will reduce NOX so much that
addition of the other technologies would become too expensive for this
phase of the regional haze program. We therefore agree that low
NOX burners at 1.2 lbs NOX/MMBTU represent BART
for the taconite industry. By setting such a uniform limit, EPA is
establishing a ``level playing field'' that is achievable by all of the
taconite plants and will provide substantial (almost 16,000 TPY)
NOX reductions.
    Response: EPA agrees with the commenter that post-combustion
control technologies would likely be expensive for additional pollution
reduction. EPA maintains that low NOX burners are the
appropriate control technology for the indurating furnaces at the
taconite facilities. Thus, EPA is finalizing its determination that low
NOX burners represent BART.
    Commenter: National Parks Service.
    Comment: EPA proposes to determine that BART for SO2 for
straight-grate kilns is existing controls because these furnaces do not
burn coal. While true, they burn fuel oil, which can have a high
potential for emitting SO2 depending on the fuel's sulfur
content. Although the BART Guidelines do not mandate fuel switching,
they encourage evaluation of lower sulfur content fuels. For example,
limiting fuel sulfur was an option considered by EPA for oil-fired EGUs
in a separate BART rule. We suggest that Minnesota consider use of
lower sulfur fuels in future reasonable progress analyses.
    Response: EPA's data indicate that the taconite facilities with
straight-grate furnaces use natural gas as the primary fuel with fuel
oil as a back-up fuel only. Given the limited use of fuel oil, emission
reductions from using lower sulfur fuel would be limited. Nonetheless,
EPA agrees with the commenter that the state should consider the
impacts of using a lower sulfur fuel in its future reasonable progress
analyses and is requiring that the taconite facilities keep records of
any future use of fuel oil.
    Commenter: National Parks Service.
    Comment: NPS concurred with EPA's statement that ``[the Agency
does] not agree that the MPCA and Minntac have adequately documented
the infeasibility of all SO2 controls described.'' This
observation is especially pertinent with respect to the technical
feasibility of spray drying absorption (SDA). According to the taconite
industry consultant, SDA is not technically feasible because ``the high
moisture content of the exhaust would lead to saturation of the
baghouse filter cake and plugging of the filters and dust collection
system.'' On the contrary, SDA requires moisture because a slurry of
lime and water is injected into the spray dryer where the slurry reacts
with SO2 to form a dry sulfate power that is then collected
in the baghouse. As long as the moisture content of the gas stream is
not excessive and the temperature is not too low, SDA becomes a
preferred and highly effective SO2 control option. It is
expected that retrofitting the facilities with SDA would eliminate the
need for the existing Venturi rod scrubbers used to control PM on most
of the taconite furnaces, thus reducing water consumption, gas stream
moisture content, and PM emissions due to the higher efficiency of the
baghouse.
    Response: In the proposed rule, EPA stated that while the state's
documentation for determining the technical feasibility of all
SO2 controls was inadequate, EPA did agree with Michigan's
conclusion that additional SO2 controls, including SDA, were
not cost effective and therefore not BART. EPA has not changed its
position on this issue in the final rule.
2. Comments Asserting That EPA's Baseline NOX Emissions Are
Arbitrary
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA's baseline NOX
assumptions are arbitrary. EPA failed to even consider the actual
emissions from each taconite furnace, let alone use them as the
starting point for calculating furnace-specific baseline emissions.
    Response: EPA disagrees. In the case-by-case BART analysis for each
subject taconite facility, EPA clearly listed the baseline actual
annual emissions for each taconite furnace (see, e.g., Table V-B.24 for
Hibbing Taconite (77 FR 49321)). In the initial stages of the BART
development process, there was a significant lack of emissions data for
the taconite facilities, as acknowledged by MPCA. However, additional
monitoring and emission reporting from the taconite facilities enabled
EPA to determine baseline NOX emissions for each facility.

G. Comments Concerning EPA's Analysis of Low NOX Burner
Technology as NOX BART

1. Comments Supporting EPA's Determination That Low NOX
Burners Are Technically Feasible
    Commenter: National Parks Conservation Association.
    Comment: NPCA commented that EPA's documentation of low
NOX burners demonstrated that significant, cost-effective
emission reductions are afforded by their use on both straight-grate
and grate-kiln furnaces. Despite this record, a taconite company raised
several concerns about EPA's determination during the public hearing.
The concerns were that a given control technology will not transfer
between indurating furnaces of the same type, low NOX
burners will impact processing (product quality, fuel use, etc.), and
there has been insufficient time to study various aspects or impacts of
this technology.
    These concerns are either misplaced or incorrect. As to the first
point, low NOX burners have been successfully applied to a
wide variety of units, including power plants, refineries, chemical
companies, and other industrial settings, which burn a wide variety of
fuels, including gas and coal. There may be individual differences
between the burners at different taconite units. As is always the case,
customization to the particular unit will be required. However, the
differences among taconite furnaces of the same type are not
significant enough to conclude that this clearly robust technology
could not be applied to one as well as the others. Indeed, technology
transfer would be impossible without such basic assumptions.
    As to the impact of low NOX burners on operational
parameters, EPA's FIP includes information addressing the points of
product quality and fuel use. Minntac's experience demonstrates no
impact to pellet quality, and after some adjustment, no increase in
fuel use.
    Finally, far from having had insufficient time to analyze these
controls, the taconite facilities have had years in which to contact
vendors, do engineering studies and modeling, and perform testing. The
regional haze process has been delayed by many years at this point.
    Response: EPA agrees with the commenter that low NOX
burners can be used to control NOX emissions from both
straight-grate and grate-kiln indurating furnaces used in the taconite
processing industry. EPA also agrees with the commenter that based on
data from taconite facilities where low NOX

burners are either in use or planned product, quality should not be
compromised.
    Commenter: National Park Service.
    Comment: NPS commented that it agreed with EPA's proposal that BART
for NOX for the taconite industry is low NOX
burners achieving a 70 percent reduction from both straight-grate and
grate-kiln furnaces. The proposal for grate-kiln lines is supported by
research sponsored by U.S. Steel. The proposal for straight-grate kilns
is supported by Essar's testing, which demonstrated a 95 percent
reduction in NOX emissions for its new kiln.
    Response: As the commenter points out, EPA has determined that low
NOX burners represent BART. However, EPA is setting an
emission limit for each indurating furnace, not a 70 percent control
requirement.
2. Comments Asserting That Low NOX Burners Are Not
Technically Feasibility on Straight-Grate Kilns
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA made an unsupported presumption
that the low NOX burner technology tested in a \1/4\-scale
pilot test by Essar for a new source could be translated to all
straight-grate furnaces.
    Response: As indicated in test reports, NOX emissions
from taconite facilities are generated primarily by the burner. As
burner design is the main factor contributing to NOX
emissions, EPA carefully reviewed results of emission tests of low
NOX burners for the different taconite furnace types and
concluded that low NOX burners are technically feasible for
straight-grate and grate-kiln furnaces.
    Supporting the feasibility of low NOX burners on
straight-grate kilns is a September 19, 2011 summary of findings
presented to the Minnesota Pollution Control Board entitled ``Results
of Testing at \1/4\-Scale of LE Low NOX Burner Prototype for
Straight-Grate Pelletizing Furnaces'' by Fives North American
Combustion, Inc. (Fives) for Essar.\9\ After successful bench-scale
testing of Fives' low NOX LE burners that achieved
NOX reductions greater than 70 percent in a straight-grate
pelletizing furnace, Essar and Fives proceeded with a joint $2 million
investment in a test rig to simulate a straight-grate pelletizing
furnace. In the \1/4\-scale test rig, the cross-sectional area scaling
was very representative of actual furnace geometry, as were the energy
inputs and flows. This testing demonstrated an emission rate of 0.25
lbs NOX/MMBTU, which is well below the proposed limit of 1.2
lbs NOX/MMBTU. Fives concluded that NOX emissions
in the actual straight-grate furnace should be consistent with those
measured in the \1/4\-scale test conditions. The feasibility of low
NOX burners on straight-grate kilns was also confirmed
during a June 20, 2012 call between EPA and a national low
NOX burner manufacturer, Fives North America.
Representatives from the manufacturing company were highly confident of
the technical feasibility and application of their technology in
straight-grate taconite furnaces. EPA agrees with this assessment.
---------------------------------------------------------------------------

    \9\ Docket  EPA-R05-OAR-2010-0037-0039.
---------------------------------------------------------------------------

    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA failed to conduct an
independent, case-by-case feasibility analysis as required by the Step
2 of the BART Guidelines. Minnesota and Michigan previously conducted
an extensive case-by-case BART analysis, eliminating low NOX
burners as technically infeasible for every taconite indurating
furnace. Cliffs asserted that EPA has adopted a ``one-size-fits-all''
approach that is arbitrary and capricious. According to Cliffs, a
proper feasibility analysis demonstrates that the technologies selected
by EPA are infeasible for Cliffs' indurating furnaces because low
NOX burners are not technically feasible for straight-grate
furnaces and grate-kiln furnaces. Cliffs asserted that the Fives burner
designed for Essar cannot be used without source-specific engineering
and retrofit design. Cliffs claimed that U.S. Steel spent two years
modifying the prototype low NOX burners installed on Lines 6
and 7 at its Minntac facility in an attempt to reach desired emission
rates while combusting solid fuel, such as coal and biomass, but were
ultimately unsuccessful. ArcelorMittal asserted that a proper
feasibility analysis demonstrated that the technologies selected by EPA
are infeasible for Minorca's indurating furnace. The commenters
submitted information describing indurating furnaces, including the
different types of furnaces, and explained what they believe are the
differences between furnace types.
    Response: EPA believes that its finding that low NOX
burners are technically feasible for both straight-grate and grate-kiln
furnaces is supported by test results on various kiln configurations.
Taconite furnaces are all based on one of two technologies. Straight-
grate kilns are based on a Dravo-Lurgi design system, while grate-kiln
furnaces are based on an Allis-Chalmers design system. EPA understands
that each specific taconite furnace has unique operating requirements
and specialized equipment. However, all furnaces share the same
fundamental design style, either grate-kiln or straight-grate.
    In assessing control technologies for a source category, EPA's BART
Guidelines state that ``control alternatives can include not only
existing controls for the source category in question but also take
into account technology transfer of controls that have been applied to
similar source categories and gas streams.'' 40 CFR part 51, appendix
Y. The Guidelines go on to explain that ``[c]ontrol technologies are
technically feasible if either (1) they have been installed and
operated successfully for the type of source under review under similar
conditions, or (2) the technology could be applied to the source under
review.'' Id.
    EPA has concluded that there is a clear case for technology
transfer of low NOX burner technology from grate-kiln
furnaces to straight-grate furnaces. First, low NOX burner
technology has been clearly and successfully demonstrated and applied
across various industries for decades. Second, EPA does not consider
taconite furnaces to be particularly unique given their similar
fundamental designs. In the case of taconite applications, the Fives'
testing of a low NOX burner prototype on a straight-grate
furnace test rig provides reasonable assurance that full-scale
applications, given the appropriate time for engineering and shakedown,
will be both feasible and effective. In addition, U.S. Steel has
already installed and is successfully operating multi-fuel low
NOX burners on two unique grate-kiln indurating furnaces at
their Minntac facility. Prior to the proposed rule, U.S. Steel had
already submitted permit applications to install low NOX
burner technologies on two additional furnaces at Minntac as well. U.S
Steel has not indicated any issues with technical feasibility that will
prevent the company from applying low NOX burners at either
its Keetac facility or the remaining furnaces at Minntac. In response
to questions from EPA concerning the installation at Minntac, U.S.
Steel described the modifications it made allowing for the successful
use of low NOX burners when burning either coal or natural
gas.\10\ In EPA's view, this information obtained directly from U.S.
Steel rebuts Cliffs' claim that the

prototype low NOX burner tests were unsuccessful.
---------------------------------------------------------------------------

    \10\ Email from U.S. Steel to EPA dated September 19, 2012
(Docket  EPA-R05-OAR-2010-0037-0071).
---------------------------------------------------------------------------

    Nor is EPA persuaded by Cliffs and ArcelorMittal's arguments that
the taconite furnaces at their facilities are unique to the extent that
low NOX burner technology cannot be applied. While EPA
understands that a complete engineering analysis will be required to
design furnace-specific low NOX burners and that a shakedown
period will be required to understand and optimize operations, EPA does
not believe that the uniqueness of each individual taconite furnace
proves technical infeasibility. The compliance times being finalized
for each facility in this action account for engineering and shakedown
time.
    Over the years, the taconite industry has demonstrated that it can
re-engineer furnaces to adapt to market changes (such as fuel prices),
process changes (to accommodate variation in the type of ore being
mined), and new technologies (such as heat recuperation systems).\11\
It is clear that depending on the needs and priorities of each company,
changes to the furnaces have and can be made.
---------------------------------------------------------------------------

    \11\ For example, during the Society of Mining Engineers' Annual
Meeting in New Orleans, Louisiana from March 2-6, 1986, a
presentation was given titled ``Design and Performance of the
National Steel Pellet Plant High Temperature Heat Recuperation
System'' (Docket  EPA-R05-OAR-2010-0037-0077). The
presentation discussed a high temperature heat recuperation system
that was installed at the National Steel Pellet Company facility in
Keewatin, Minnesota. The system was similar to those installed at
Cliffs' Empire facility and U.S. Steel's Minntac facility.
---------------------------------------------------------------------------

    With respect to ArcelorMittal's comment that a proper feasibility
analysis would demonstrate that the technologies selected by EPA are
infeasible for Minorca's indurating furnace, EPA relies on a September
27, 2012 report submitted by the commenter and authored by Fives North
American titled ``Retrofitting Low NOX Burners on the
ArcelorMittal Minorca Straight-Grate Pelletizing Furnaces.'' \12\ After
review, EPA concludes that this report supports the Agency's conclusion
that low NOX burners are feasible at the Minorca facility.
EPA therefore disagrees with ArcelorMittal's assertion that such
technology is infeasible. Fives North American was engaged to perform
an engineering study and recommend best options for retrofitting low
NOX burners at the pelletizing furnace at the Minorca plant
in order to achieve NOX emission rates below 1.2 lbs
NOX/MMBtu under expected operating conditions. Fives
expressed confidence that the company's experience in manufacturing low
NOX burners, coupled with the successful results of the \1/
4\-scale test at Essar, provided sufficient assurance that the
technology could be applied at Minorca while preserving pellet quality
and energy efficiency.
---------------------------------------------------------------------------

    \12\ Docket  EPA-R05-OAR-2010-0037-0037.
---------------------------------------------------------------------------

3. Comments Concerning EPA's Cost Analysis for Low NOX
Burners
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA presumed that low NOX
burners will cost $500/ton at every Cliffs facility despite the fact
that none of these facilities identified low NOX burners as
technically feasible. EPA's $500/ton across-the-board cost estimate for
NOX control was neither explained in the proposed rule nor
supported by the record.
    Response: EPA did not presume that low NOX burners will
cost $500/ton at every Cliffs facility. EPA's proposed rule stated that
``[b]ased on the range of cost-effectiveness values provided, a
conservative value of $500/ton will be used as the cost-effectiveness
value for low NOX burners'' (77 FR 49308, 49312). Data made
available by U.S. Steel indicate the cost-effectiveness of low
NOX burners on Minntac's Line 6 indurating furnace was $441/
ton of NOX reduced with burning a 60 percent coal/40 percent
natural gas fuel mix and $221/ton of NOX reduced when
burning 100 percent natural gas. Barr Engineering and Essar Steel
Minnesota have estimated a cost-effectiveness of $370/ton of
NOX reduced for low NOX burner technology on a
planned straight-grate natural gas-fired furnace.\13\ This furnace is
being designed to meet a much more stringent emission limit of 0.25 lbs
NOX/MMBtu, compared to EPA's proposed limit of 1.2 lbs
NOX/MMBtu. Thus, EPA's value of $500/ton represents a high-
end estimate of expected cost-effectiveness of the selected
NOX BART controls and is based on itemized costs and annual
NOX emissions reductions.
---------------------------------------------------------------------------

    \13\ Essar and Barr Presentation for Society for Mining,
Metallurgy and Exploration, Duluth, Minnesota, April 2012 (Docket
 EPA-R05-OAR-2010-0037-0039).
---------------------------------------------------------------------------

4. Comments Concerning the Effectiveness of Low NOX Burners
    Commenter: U.S. Steel.
    Comment: U.S. Steel commented that, based upon its experience, the
appropriate emission factor when burning solid fuels is 1.5 lbs
NOX/MMBtu, as opposed to the proposed NOX limit
of 1.2 lbs NOX/MMBtu. U.S. Steel supplemented its comment on
October 15, 2012 with data that support a limit of 1.2 lbs
NOX/MMBtu while burning natural gas and 1.5 lbs
NOX/MMBtu while burning solid fuels. U.S. Steel proposed
that it be subject to the solid fuel limit, unless it utilizes 100
percent natural gas as a fuel for 30 consecutive days. The natural gas
limit would then apply and it would remain subject to that limit until
such time that solid fuels were utilized.
    Response: Based on a review of the data submitted by U.S. Steel,
EPA agrees to revise the NOX limits in the final rule to 1.2
lbs NOX/MMBtu while an indurating furnace is burning 100
percent natural gas and 1.5 lbs NOX/MMBtu when fuels other
than natural gas are being used. This revision primarily affects U.S.
Steel Keetac, U.S. Steel Minntac, and United Taconite.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA made an unsupported presumption
that an emission limit of 1.2 lbs NOX/MMBtu is equivalent to
a 70 percent NOX reduction at every Cliffs facility and that
all taconite furnaces emit NOX at an uncontrolled baseline
rate of 4.0 lbs NOX/mmBTU in disregard of furnace
variability.
    Response: The NOX emission limit that EPA proposed was
1.2 lbs NOX/MMBtu on a 30-day rolling average. This emission
limit was not based on a percent reduction requirement, but rather was
based on a demonstration by U.S. Steel that low NOX burners
installed at the Minntac facility could achieve this emission limit.
This limit is further supported for straight-grate kilns by successful
testing of a low NOX burner prototype at a 1/4-scale test
rig at Essar. It is standard industry practice to perform pilot tests,
in which the results of a smaller unit are scaled up to a full
production unit. Furthermore, in this case the company was extremely
confident that, based upon the results with the 1/4-scale test rig, a
limit much lower than 1.2 lbs NOX/MMBtu could be achieved on
the full production unit. However, based on additional test data of
operational low NOX burners submitted by U.S. Steel for
Lines 6 and 7 at Minntac, EPA is revising its proposed limit of 1.2 lbs
NOX/MMBtu on a 30-day rolling average. In the final rule,
taconite indurating furnaces are subject to a limit of 1.2 lbs
NOX/MMBtu when only natural gas is burned and 1.5 lbs
NOX/MMBtu when fuels other than natural gas are used. Both
of these limits are based on a 30-day rolling average.

H. Comments Concerning Non-Air Quality Impacts of Low NOX
Burners

1. Effect on Pellet Quality
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.

    Comment: Cliffs commented that pellet quality cannot be maintained
after the installation of low NOX burner technology.
    Response: EPA disagrees. Based on data supplied by U.S. Steel, EPA
has concluded that there will be no pellet quality challenges resulting
from the installation and operation of low NOX burner
technology. In an email sent by U.S. Steel to EPA on September 19,
2012, U.S. Steel indicated that pellet quality specifications have not
changed since the installation of low NOX burners, with zero
off-spec shipments to date.\14\ There have been no adverse pellet
quality issues related to the installation and operation of the low
NOX burners.
---------------------------------------------------------------------------

    \14\ Docket  EPA-R05-OAR-2010-0037-0071.
---------------------------------------------------------------------------

    U.S. Steel is required to maintain four pellet quality parameters,
after tumble, compressions, reducibility, and low temperature
disintegration (LTD), to meet customer specifications. U.S. Steel
supplied EPA with data confirming that pellet quality parameters were
acceptable after the installation of the Line 6 low NOX
burner (Table 1). U.S. Steel also included more recent quality
parameter data to show that quality continues to remain acceptable.
U.S. Steel noted that while compressions have decreased, this has been
observed on all process lines, including those without low
NOX burners, thus indicating an issue with the feed material
and not the burners. As also shown, U.S. Steel saw an improvement in
reducibility for their pellets after the installation, which U.S. Steel
attributes to improved heat distribution in the kiln from the low
NOX burner.

                 Table 1--Line 6 Pellet Quality Before and After the Low NOX Burner Installation
                                    (Higher values represent better quality)
----------------------------------------------------------------------------------------------------------------
                                                   After tumble     Compression    Reducibility         LTD
----------------------------------------------------------------------------------------------------------------
Before (11/1/10-4/3/11).........................            96.0             416            1.15           87.30
After (4/20/11-10/31/11)........................            96.0             417            1.22           85.58
1/1/12-9/1/12...................................            96.2             410            1.22           86.11
----------------------------------------------------------------------------------------------------------------

2. Fuel Penalty and Energy Penalty
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that a fuel penalty and an energy penalty
will result from the operation of low NOX burner technology
at its facilities. Additional fans will be required to increase primary
air flow through the furnaces because the cooler air that is injected
into the burner to control peak flame temperature must be heated. EPA
made an unsupported presumption that low NOX burners will
cause no fuel or energy penalties or other emissions increases at any
of the facilities.
    Response: EPA disagrees. The installation and use of low
NOX burners is not generally considered to result in an
energy penalty because one burner is merely being replaced by another.
EPA recognizes that there is an increase in electricity needed for the
operation of low NOX burner fans to assist in movement of
air through the system or to heat cooler air that is injected into the
burner. These costs can in most cases simply be factored into the cost
impacts analysis as they were in this case for both NOX and
SO2 controls.
    EPA believes that a low NOX burner installation that is
properly engineered and optimized for a given process will not result
in a fuel or energy penalty. EPA's conclusion is based on the U.S.
Steel Minntac Line 6 Low NOX Main Burner & Facility
NOX Management Final Report (December 1, 2011),\15\ which
documented that low NOX burners did not cause fuel penalties
or other emission impacts. In addition, EPA consulted with a burner
manufacturer and reviewed information provided by U.S. Steel regarding
potential fuel impacts potentially associated with the operation of low
NOX burners at a taconite facility.\16\ In this
correspondence, U.S. Steel Minntac stated that there was a temporary
10.5 percent fuel increase after initial installation of the low
NOX burner on Line 7. However, during the shakedown period,
the fuel increase was alleviated by process optimization (there was a
learning curve due to the fact that this was the first low
NOX burner installed on an iron ore processing line) and
balancing the process airflow. The waste gas fan on Line 7 was running
at maximum before the burner installation and with the addition of
combustion air, the process efficiency decreased and safety issues were
created. To alleviate this condition, the waste gas fan airflow
capacity was increased in February 2011 on Line 7 to balance the
airflow out of the process. In April 2011, the Line 6 low
NOX burner was installed at U.S. Steel's Minntac facility.
After applying what was learned during the shakedown period on Line 7,
no increase in process fuel occurred after the installation. U.S. Steel
clearly states in its September 19, 2012 email to EPA, ``The end result
is there is no increase in process fuel due to the installation of the
Line 7 low NOX burner.'' \17\
---------------------------------------------------------------------------

    \15\ Docket  EPA-R05-OAR-2010-0037-0039.
    \16\ U.S. Steel email to EPA dated September 19, 2012 (Docket
 EPA-R05-OAR-2010-0037-0071).
    \17\ Docket  EPA-R05-OAR-2010-0037-0071.
---------------------------------------------------------------------------

    In summary, based on available data, EPA believes that with process
optimization, proper balancing of process air flows, and proper
engineering, Cliffs and ArcelorMittal will be able to achieve similar
fuel usage to U.S. Steel and will not incur either a fuel or energy
penalty. EPA understands that each company will require a shakedown
period similar to that experienced at U.S. Steel and has set the
compliance schedules each facility accordingly.
3. Increases in the Emission of Other Pollutants
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that emissions of other pollutants will
increase due to the installation of low NOX burner
technology.
    Response: EPA has determined that there will be no increases in
collateral pollutants due to the installation of low NOX
burner technology. In making this determination, EPA relied on the
information supplied by MPCA, U.S. Steel, Coen Company, Inc., and
Hatch, as described below.
    In a letter dated November 3, 2009 from Coen Company, Inc., Coen
stated:

    As we have indicated, the kiln burner that we proposed to supply
for the above referenced project will not produce more CO as
compared with what is being produced by the existing burner. The
reason is: carbon monoxide (CO) is formed from lack of fast mixing
of NO and oxidant (O2) and chemical kinetics of the
reaction that is highly dependent on temperature and O2
concentration. The Coen multi-fuel burner is being designed for
higher stoichiometric air (1.00) as compared with the existing
burner which has a stoichiometric air of about 0.3 only. Hence, the
Coen burner design

promotes a higher amount of premixing of O2 (oxidant)
with fuel to reduce CO production. The flame temperature in both
cases is high enough so the oxidation of CO is not kinetically
limited. So the new burner design is not kinetically-limited for CO
oxidation and the increased premixing in the primary zone will
reduce CO emissions.\18\
---------------------------------------------------------------------------

    \18\ Docket  EPA-R05-OAR-2010-0037-0071.
---------------------------------------------------------------------------

    Similarly, in a letter dated November 6, 2009 from Hatch to U.S.
Steel, Hatch stated: ``Since USS Minntac plans to continue using their
current fuels, fuel mixes, and fuel firing rates in conjunction with
the low NOX burners, with the exception of NOX,
Hatch does not anticipate any change in the emissions of applicable
pollutants. Substantial reduction of NOX emissions is also
anticipated.''\19\
---------------------------------------------------------------------------

    \19\ Docket  EPA-R05-OAR-2010-0037-0071.
---------------------------------------------------------------------------

    Finally, in a letter to U.S. Steel dated November 20, 2009, Owen
Seltz, Engineer, Metallic Mining Section, Industrial Division, MPCA,
stated:

    Generally, when a reduction in NOX emissions from
fuel combustion is proposed, the pollutant of concern for potential
increase is carbon monoxide (CO). However, due to the design of the
proposed low NOX main burner, CO emissions are not
anticipated to increase. Furthermore, as explained in the
manufacturers' letters dated November 3, 2009, and November 6, 2009
and submitted to the MPCA in Minntac's November 12, 2009 letter, due
to the design and operation of the proposed burner, CO emissions are
expected to decrease.\20\

    \20\ Docket  EPA-R05-OAR-2010-0037-0071.
---------------------------------------------------------------------------

    Based on these assurances, EPA is confident that there will be no
increases in other pollutants as a result of the installation of low
NOX burner technology as Cliffs claims.

I. Comments Concerning Sulfur Dioxide (SO2) BART Emission
Limits

    Commenter: National Parks Conservation Association.
    Comment: NPCA commented that the proposed limits for six of the
units (at Northshore, ArcelorMittal, and Hibbing) specifically do not
apply when burning fuel oil. This loophole undermines the purpose of a
BART analysis and contradicts the CAA requirement for BART to be met on
a continuous basis. The final determination must include a limit that
encompasses the burning of fuel oil at these facilities.
    Response: Northshore, ArcelorMittal, and Hibbing are straight-grate
indurating furnaces and do not burn coal. The primary fuel at these
facilities is natural gas. As a result, these facilities have
inherently low SO2 emissions. Fuel oil is used only as a
backup fuel. Due to its limited use, there was insufficient test data
to set a corresponding SO2 emission limit for periods when
fuel oil is being burned. EPA set the SO2 emission limits
based on available data. For the straight-grate facilities, data was
only available for periods in which the furnaces were combusting
natural gas. In order to address this issue, EPA has added a regulatory
requirement for affected sources to track their use of fuel oil and the
resulting SO2 emissions. This information will be used as
the basis for any restrictions that will need to be added, e.g. sulfur
content, on the use of fuel oil. These requirements are contained in
Sec. Sec.  52.1183(k)(4) and 52.1235(b)(2)(7).
    Commenter: Michigan Department of Environmental Quality (MDEQ).
    Comment: MDEQ commented that it had based its acceptance of
Tilden's BART submittal for SO2 on the lack of visibility
impairment due to SO2 emissions.
    Response: In the final rule, EPA is no longer requiring add-on
controls at the Tilden facility because Tilden has agreed to switch
fuels to natural gas within one year of the effective date of this
rule.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA should use the methods proposed
by Minnesota to set emission limits, citing the limits the state set
for the Hibbing Taconite and ArcelorMittal facilities. Cliffs contended
that EPA's proposed SO2 emission limits are unsupported and
arbitrary. Cliffs objected to the limits set by EPA because they appear
to be based on results from a single stack test, which represents a
snapshot in time. Further, the limits ignore a significant amount of
available data and bypass the statistical analysis conducted by MPCA.
    Response: In the Agency's review of Minnesota's regional haze SIP
supplement, EPA concluded that the limits for taconite facilities
proposed by Minnesota do not accurately represent the current level of
controls at the facilities. For ArcelorMittal and Hibbing Taconite,
Minnesota appears to have set the limit in pounds of SO2 per
long ton (LT) of pellets produced based on a 30-day rolling average,
using the Upper Predictive Limit (UPL) approach for normally
distributed data. Minnesota did not demonstrate an accurate method to
track or record LT of pellets produced. Therefore, the limits proposed
by Minnesota are unenforceable. EPA also concluded that the annual
testing requirement proposed by the state is insufficient to determine
compliance with a limit based on a 30-day rolling average. In this
action, EPA is finalizing SO2 limits for taconite facilities
in terms of lbs SO2/hr based on a 30-day rolling average,
which can be easily and accurately measured using the continuous
emissions monitoring system (CEMS) required by this rule.
    EPA does agree that the UPL approach is an appropriate method for
setting the SO2 limits. However, the available
SO2 emissions data for the taconite sources generally do not
follow a normal, logarithmic, or gamma distribution. For this reason,
the UPL should be determined using a nonparametric method, as set forth
below. EPA used available stack test and CEMS data from 1990 to the
present to recalculate the SO2 limits for ArcelorMittal and
Hibbing, based on the appropriate UPL equation for nonparametric data,
in terms of lbs SO2/hr on a 30-day rolling average as
follows:

UPL = xm and m = (n + 1)*(1 - a)

Where:

xm = value of the mth data point, when the data is sorted smallest
to largest
m = the rank of the ordered data point, when data is sorted smallest
to largest
n = number of data points
a = 95th percentile or 0.95

    If m is not a whole number, a linear interpolation is calculated
from the following equation:
[GRAPHIC] [TIFF OMITTED] TR06FE13.001

Where:
mi = the integer portion of m, i.e., m truncated at zero decimal
places, and
md = the decimal portion of m

    In this final rule, EPA is setting a limit of 38.16 lbs
SO2/hr for indurating furnace EU026 at ArcelorMittal. This
limit must be measured on a 30-day rolling average and does not apply
when the subject unit is burning fuel oil. For Hibbing, EPA is
finalizing an aggregate limit of 247.8 lbs SO2/hr based on a
limit of 82.60 lbs SO2/hr for each of the three affected
lines: EU020, EU021, and

EU022. This limit is also measured on a 30-day rolling average and does
not apply when the subject unit is burning fuel oil.
    Because of limited stack test data for Hibbing and ArcelorMittal,
these sources may, within 20 months of the effective date of this rule,
calculate a revised SO2 limit based on one year of hourly
CEMS data, reported in lbs SO2/hr, and submit such limit,
calculations, and CEMS data to EPA. This limit shall be set in terms of
lbs SO2/hr, based on the non-parametric UPL equations set
forth above, with compliance to be determined on a 30-day rolling
average.
    Commenter: Cliffs Natural Resources.
    Comment: Cliffs submitted alternate SO2 limits for
Hibbing based on the UPL equation for normally distributed data.
    Response: While EPA agrees that the UPL approach is the appropriate
method for setting the SO2 limits, EPA disagrees with the
alternate SO2 limits submitted by the Cliffs for the Hibbing
facility. Cliffs did not specify whether its suggested limit was daily,
instantaneous, or on a 30-day rolling average. But in any case, the
limit submitted by Cliffs for Hibbing appears to be calculated using
the UPL equation for normally distributed data, a p-value of 0.01
(which would represent a 99.5 percent confidence interval) and m = 1.
This is incorrect. According to the UPL method, m represents the number
of future runs (i.e., the number of future data points). As the data
sets being used in the analyses are one-hour CEMS averages, the value
of m should be 720 (30 days times 24 hours) if the limit being set is a
30-day rolling average. Even if compliance is based on the average
value of an annual performance test rather than a 30-day rolling
average, Minnesota's annual performance testing requires 30 hourly data
points, which would result in a value of 30 for m. Cliffs also appears
to have combined all stacks for each line and averaged all test runs
for each set of test data to arrive at one data point for each set of
test data, resulting in only 10 data points rather than 720 to
calculate the UPL.
    In addition, although the raw test data provided SO2
emissions levels in terms of lbs SO2/hr, Cliffs calculated
the UPL in terms of lbs SO2/LT pellets and then converted
the SO2 limit back into lbs SO2/hr by using the
maximum design capacity of each line rather than the actual production
data collected during testing.
    Thus, EPA disagrees with this methodology. The alternate emission
limit proposed by Cliffs is significantly higher than the limit that
would result from the correct application of the UPL equation for
normally distributed data. Further, some of the available data for the
Hibbing facility are normally distributed, while other data are not. As
noted previously, the available SO2 emissions data for the
taconite industry in general do not follow a normal, logarithmic, or
gamma distribution. For this reason, EPA is using the nonparametric UPL
equation to calculate the SO2 emission limits.
    Commenter: Cliffs Natural Resources.
    Comment: Cliffs objected to the proposed 80 percent SO2
reduction requirement for Northshore, noting that an SO2
emission limit was also set for the facility. Cliffs contended that EPA
failed to cite any justification for the requirement and failed to
explain why an 80 percent reduction in SO2 emissions should
be required for Northshore when a similar reduction was not required
for any other facility. Cliffs asserted that Northshore's
SO2 emissions have a de minimis impact on visibility, so
imposing multiple layers of control requirements would be arbitrary and
unnecessary.
    Response: Northshore is subject to BART based on the visibility
impacts that were described in the proposal rule. The document entitled
``Northshore Mining Company Analysis of Best Available Retrofit
Technology (BART)'' submitted to MPCA on behalf of Northshore Mining
states that ``WWESPs are currently in place on the furnace exhausts and
are believed to remove 80 to 95 percent of the SO2 in the
exhaust.'' \21\ Thus, 80 percent is on the low end of the removal
efficiency range estimated by Northshore, not an arbitrary number
selected by EPA. Further, in a CAA section 114 request to Cliffs and
Northshore Mining, EPA requested copies of all stack tests conducted on
any emissions unit for any reason, including all test runs, even if a
full test series was not completed. In its response to EPA, Cliffs did
not provide any SO2 test data for the subject-to-BART
furnaces at Northshore. Without this emissions data, EPA believes using
Northshore Mining's prior estimate of 80 to 95 percent control
efficiency on its furnace exhausts EPA to impose an 80 percent
emissions reduction requirement on stacks SV101, SV102, SV103, SV104,
SV105, SV111, SV112, SV113, SV114, and SV115 was appropriate.
---------------------------------------------------------------------------

    \21\ Docket  EPA-R05-OAR-2010-0037-0034 (p. 24).
---------------------------------------------------------------------------

    Subsequent to the public comment period, Cliffs provided EPA with
limited SO2 emissions data for Northshore and proposed an
aggregate limit of 39.0 lbs SO2/hr based on a limit of 19.5
lbs SO2/hr per line. Cliffs' proposed limit is slightly
higher than the limit EPA calculated using the new data and the UPL
equation for nonparametric data. However, EPA believes it is reasonable
to set an aggregate limit of 39.0 lbs SO2/hr, measured on a
30-day rolling average, and to require the source to recalculate this
limit when CEMS data are available.
    As stated previously, this limit does not apply when the facility
is burning fuel oil. In order to address this issue, EPA has added a
regulatory requirement for affected sources to track their use of fuel
oil and the resulting SO2 emissions. This information will
be used as the basis for any restrictions that will need to be added,
e.g. sulfur content, on the use of fuel oil. These requirements are
contained in sections 52.1183(k)(4) and 52.1235(b)(2)(7).
    In summary, this final rule establishes an aggregate SO2
emission limit of 39.0 lbs SO2/hour, measured on a 30-day
rolling average, for Furnace 11 and Furnace 12 at Northshore. Within 20
months of the effective date of this rule, the owner or operator must
calculate a revised SO2 limit based on one year of hourly
CEMS emissions data reported in lbs SO2/hr and submit such
limit, calculations, and data to EPA. This limit shall be set in terms
of lbs SO2/hr, based on the non-parametric UPL equations
previously set forth by EPA, with compliance to be determined on a 30-
day rolling average. EPA agrees with the commenter that an 80 percent
reduction requirement is no longer needed because it is redundant in
light of the final lbs SO2/hr emission limit. Consequently,
this final rule does not require an additional 80 percent emissions
reduction requirement at Northshore.
    Commenter: National Park Service and Cliffs Natural Resources.
    Comment: NPS supported EPA's proposal to require FGD as BART for
SO2 at the United Taconite and Tilden facilities, agreeing
with EPA's cost-effectiveness calculations.
    Cliffs, on the other hand, disagreed with EPA's cost-effectiveness
calculations for the United Taconite and Tilden facilities. Subsequent
to the public comment period, Cliffs proposed switching fuels as an
alternative to installing FGD scrubbers. Cliffs proposed a combined
limit of 529 lbs SO2/hr for Lines 1 and 2 at the United
Taconite facility, with compliance to be determined on a 30-day rolling
average, beginning in 54 months. To meet this limit, the United
Taconite furnaces will burn low-sulfur fuels, including increased use
of natural gas. For Tilden, Cliffs proposed switching operation to

100 percent natural gas within 12 months with an emissions limit to be
set after a year of CEMS data become available.
    Response: Subsequent to the proposed rule, Cliffs has agreed to a
federally enforceable aggregate emission limit of 529 lbs
SO2/hr, based on a 30-day rolling average, at United
Taconite, based on the use of low-sulfur fuels. Cliffs has also agreed
to convert to the use of 100 percent natural gas at Tilden. Because
Tilden will now be restricted to the use of 100 percent natural gas,
requiring the installation of SO2 controls is no longer
economically feasible or necessary. Similarly, in light of the
reduction in SO2 emissions that will result from the use of
low-sulfur fuels at United Taconite, the cost effectiveness of
additional controls has increased to $12,021 per ton for Line 1 and
$7,680 per ton for Line 2. Thus, EPA believes that the installation of
such controls is no longer economically feasible. In addition to the
emission limit proposed by Cliffs, to ensure the use of low-sulfur
fuels and SO2 reductions resulting from the use of low-
sulfur fuels at United Taconite, EPA is also requiring that the
facility burn either natural gas or a blend of natural gas and coal.
EPA is also establishing a limitation on the coal to be used by
requiring the coal have a sulfur content no greater than 0.60 percent
sulfur by weight based on a monthly block average. The requirement for
a sampling and calculation methodology for determining this value is
contained within the monitoring plan as required in section
52.1235(e)(8)(x). In summary, EPA is no longer requiring FGD at United
Taconite and Tilden as BART for SO2 in this final rule.
    Commenter: U.S. Steel.
    Comment: U.S. Steel proposed several alternate lbs SO2/
hr limits for its Minntac facility. These limits were calculated by
applying a 99 percent confidence interval utilizing three years of CEMS
data. U.S. Steel also proposed alternate limits for producing flux
versus acid pellets due to scrubber inefficiencies during acid pellet
production.
    U.S. Steel proposed, as its first choice, an aggregate limit of 498
lbs SO2/hr, on a 30-day rolling average, when all five lines
are producing flux pellets; an aggregate limit of 630 lbs
SO2/hr, on a 30-day rolling average, when Lines 3-5 are
producing acid pellets and Lines 6 and 7 are producing flux pellets;
and an aggregate limit of 800 lbs SO2/hr, on a 30-day
rolling average, when all five lines are producing acid pellets. U.S.
steel also proposed partially aggregated limits and line-by-line limits
for acid pellets and flux pellets. Finally, U.S. Steel proposed that
the limit for acid pellets be in effect during acid production and for
30 days thereafter due to the 30-day rolling average.
    Response: EPA compared the limits proposed by U.S. Steel to the
limit EPA calculated with the non-parametric UPL method and found them
to be comparable. EPA also agrees with the need for a higher limit for
acid pellet production.
    Therefore, in this final rule, the SO2 emission limits
for U.S. Steel's Minntac facility are 498 lbs SO2/hr on
Lines 3-7 when all lines are producing flux pellets; 630 lbs
SO2/hr when Lines 3-5 are producing acid pellets and Lines 6
and 7 are producing flux pellets; and 800 lbs SO2/hr on
Lines 3-7 when all lines are producing acid pellets. All limits are
calculated on a 30-day rolling average.
    However, EPA does not agree that the limit for acid pellets should
apply during acid production and for 30 days thereafter and thus has
not made this change in the final rule. The emission limit for a given
30-day rolling average period will be calculated using a weighted
average as follows:
[GRAPHIC] [TIFF OMITTED] TR06FE13.002

Where:
L30 = the limit for a given 30-day averaging period
nf = the number of days in the 30-day period that the facility is
producing flux pellets on Lines 3-7
naf = the number of days in the 30-day period that the facility is
producing acid pellets on Lines 3-5 and flux pellets on Lines 6 and
7
na = the number of days in the 30-day period that the facility is
producing acid pellets on Lines 3-7

    Commenter: U.S. Steel and Cliffs Natural Resources.
    Comment: Cliffs and U.S. Steel commented that it is inappropriate
to use a seven percent oxygen correction for emission limits that are
not concentration based.
    Response: EPA agrees with the commenters that the use of a seven
percent oxygen correction is not necessary when the subject-to-BART
facilities elect to comply with an emission limit measured in pounds of
pollutant per million British thermal units or pounds of pollutant per
hour.
    Commenter: U.S. Steel.
    Comment: U.S. Steel requested that the pH and SO2
removal efficiency limits for its Keetac facility be deleted because
they are redundant with the lbs SO2/hr limit.
    Response: EPA agrees with U.S. Steel and has deleted the pH and
SO2 removal efficiency limits from the final rule.
    Commenter: Leech Lake Band of Ojibwe.
    Comment: At United Taconite and Tilden, limiting SO2 to
5 parts per million by volume or requiring the facilities to meet a 95
percent reduction requirement, on a 30-day rolling average, using dry
FGD is achievable and cost-effective.
    Commenter: Red Cliff Band of Lake Superior Chippewas.
    Comment: The Red Cliff Band supported EPA's proposed requirement
for additional SO2 controls in select facilities.
    Commenter: National Tribal Air Association.
    Comment: The Association agreed with using existing SO2
controls for those taconite facilities where it would be cost
prohibitive to convert to a different technology that would only
achieve nominal SO2 reductions. However, in the case of the
United Taconite and Tilden facilities, the Association found it
relatively inexpensive to use dry FGD to limit SO2 to 5
parts per million by volume or to meet a 95 percent reduction
requirement on a 30-day rolling average.
    Commenter: National Park Service.
    Comment: NPS supported EPA's proposal to require FGD as BART for
SO2 at the United Taconite and Tilden facilities, agreeing
with EPA's cost effectiveness calculations and compliance schedule.
    Response: EPA agrees with the commenters that under current
operating conditions, FGD is a cost-effective control option for the
grate-kiln furnaces at United Taconite and Tilden and represents BART.
However, subsequent to the public comment period, Cliffs proposed
switching fuels as an alternative to installing FGD scrubbers. Cliffs
has since agreed to federally enforceable limits on the types of fuels
that may be burned at these facilities. In this final rule, the United
Taconite furnaces must burn a combination of natural gas and low-sulfur
coal and Tilden will now burn 100 percent natural gas. Given these
changes, EPA has determined that requiring the installation of
SO2 controls is no longer economically feasible or
necessary.

J. Comments Concerning the Visibility Analysis and Visibility Impacts

    Commenter: Fond du Lac Band of Lake Superior Chippewa.
    Comment: Tables V-C.l0 to V-C.l5 of the FIP demonstrate the changes
in visibility that could be expected from the use of low NOX
burners. While these are only predictions, the expected improvements in
visibility in the

Boundary Waters Canoe and Wilderness Area, Voyageurs National Park, and
Isle Royale National Park strongly support the use of this technology
at the subject-to-BART taconite plants.
    Response: EPA agrees that the BART emission limits have the
potential to result in significant improvement in visibility at the
affected Class I areas.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA did not conduct a proper
analysis of visibility impacts.
    Response: EPA disagrees. EPA's visibility estimates provide ample
evidence that the visibility impacts of each subject-to-BART taconite
facility are substantial enough to warrant the selected BART controls.
EPA's responses to the individual criticisms raised by the commenters
on our visibility analysis are discussed in further detail below.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that the proposed rule directly
contravened the instructions given to EPA in American Corn Growers v.
EPA. In particular, Cliffs asserted that EPA's method is a
``bifurcated'' approach to visibility that was rejected in that
decision. In Cliffs' view, the American Corn Growers court rejected a
bifurcated approach in which visibility impacts are treated differently
than the other four BART factors. Cliffs noted that for each taconite
source, EPA separated its analysis into two distinct sections. Section
V.B. of the proposed rule analyzed the first four factors, while EPA
separately analyzed visibility improvement in Section V.C. for
whichever technology emerged from the four-factor analysis in Section
V.B. Thus, in Cliffs' view, the real-world visibility impacts were, at
most, a secondary consideration that could not have influenced the
evaluation of BART alternatives.
    Response: EPA disagrees. The ``bifurcation'' referred to in the
American Corn Growers decision related to EPA's use of a regional,
multi-source, group approach to determining the degree of visibility
improvement, while analyzing the other four statutory factors on a
source-specific basis. The American Corn Growers court held that the
visibility analysis must not be treated differently and must be a
source-specific analysis. Since that decision, EPA and states have
consistently conducted the visibility prong of the five-factor analysis
on a source-specific basis. In this instance, although EPA presented
its visibility analysis in a separate section of the proposed rule, the
Agency conducted the analysis on a source-specific basis consistent
with the holding in American Corn Growers.
    EPA also disagrees that visibility was a secondary consideration in
its analysis. EPA's analysis shows that based on the all of the BART
factors, including visibility, the selected controls are warranted. If
highly reasonable and cost-effective controls had been available but
visibility benefits were slight, EPA would have rejected those
controls. Section V.B. of the proposed rule demonstrated that
reasonable and cost-effective controls were available. Section V.C.
then showed that the visibility benefits to be obtained by requiring
controls at each source were significant. Site-specific visibility
improvement estimates for each source, derived from regional modeling
conducted by the state of Minnesota on a variety of sources in the
area, demonstrated that the significant reductions EPA proposed will
produce significant visibility improvement in affected Class I areas.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that the approach EPA used in the
proposed rule to estimate visibility impacts was arbitrary because it
was not site-specific. Rather than extrapolating results from other
facilities, EPA should have conducted modeling for the specific sources
being regulated. The BART Guidelines instruct EPA to conduct modeling
using CALPUFF or other appropriate dispersion models for each source
and highlight the importance of source-specific features, such as stack
flow rate and release height. EPA's use of ``visibility impact ratios''
derived from other sources is not consistent with EPA's own guidelines
and provides results that are too unreliable for the purpose of a BART
visibility analysis. In using the visibility impact ratio approach, EPA
is holding itself to a lower standard than it would expect from a state
air quality agency conducting a similar BART review.
    Response: EPA's proposed rule acknowledged that there is greater
uncertainty associated with the visibility impact ratio approach.
Nonetheless, EPA finds this approach to be consistent the BART
Guidelines allowance for ``appropriate'' models and believes the
approach provides adequate indication of the visibility benefits of the
evaluated controls.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that EPA's visibility analysis was
inconsistent with the statutory obligation to consider the degree of
visibility improvement that is ``reasonably anticipated.'' In Cliffs'
view, the use of ``possible'' impacts from an approach extrapolated
from other facilities does not satisfy this statutory requirement to
consider ``reasonably anticipated'' visibility impacts. In support of
this view, Cliffs noted that EPA extrapolated visibility results from
facilities other than taconite plants, such as an electric generating
unit. Moreover, Cliffs found EPA's use of sources in the ``general
area'' as unacceptable for the visibility analysis given that wind
conditions would affect the taconite facilities differently than the
facilities EPA relied upon. Additionally, the commenter noted
differences in stack conditions between the taconite facilities being
regulated and the sources that EPA relied upon.
    Response: EPA's proposed rule acknowledged the uncertainty
associated with the visibility impact ratio approach, but noted that
despite the uncertainties, the Agency was confident that the
information was adequate to assess potential visibility improvements
due to emissions reductions at the specific facilities. While the
results obtained from this approach are not expected to be as precise
as source-specific CALPUFF modeling, they are based on visibility
improvements derived from existing regional scale modeling that was
conducted on sources in and around the northern Minnesota area. Given
the geographic proximity of the taconite facilities to those that were
modeled, EPA believes that the ratio approach provided adequate
assurance of the visibility improvements that can be expected from the
proposed emission reductions.
    The results EPA obtained from its analysis are presented in terms
of deciview (DV) change and change in the number of days above the 0.5
DV threshold. In the proposed rule's summary of the impacts at Boundary
Waters, Voyageurs, and Isle Royale, these values ranged from 1.3 to 7.1
DVs of improvement with between 17 and 93 fewer days above the 0.5 DV
threshold. Therefore, even if the ratio approach was over-estimating
visibility improvements by a factor of two or three, the expected
benefits would still be significant.
    For example, Cliffs submitted CALPUFF modeling that showed the
visibility improvements expected from the proposed rule for two of the
seven facilities--United Taconite and Tilden. This modeling was only
performed at the most impacted of the four affected Class I areas. EPA
also notes that these were the only facilities for which new

scrubbers were proposed as BART for SO2.
    The results of the Cliffs' modeling for United Taconite and Tilden
are presented below. The first delta DV value is the subtraction of the
two 98th percentile impacts (base minus FIP).

                Table 2--United Taconite Predicted Visibility Results for the Most Impacted Areas
----------------------------------------------------------------------------------------------------------------
                                                                     Boundary
                                                     Boundary       waters 98th   Voyageurs days  Voyageurs 98th
                  Scenario/year                     Waters days     percentile      over 0.5 DV     percentile
                                                    over 0.5 DV      delta DV                        delta DV
----------------------------------------------------------------------------------------------------------------
Difference/2002.................................              36           0.594              17           0.454
Difference/2003.................................              39           0.579              14           0.649
Difference/2004.................................              33           0.545              17           0.439
----------------------------------------------------------------------------------------------------------------

                    Table 3--Tilden Predicted Visibility Results for the Most Impacted Areas
----------------------------------------------------------------------------------------------------------------
                                                                     Isle 98th                      Seney 98th
                  Scenario/year                   Isle Days over    percentile      Seney days      percentile
                                                      0.5 DV         delta DV       over 0.5 DV      delta DV
----------------------------------------------------------------------------------------------------------------
Difference/2002.................................               2           0.099               3           0.146
Difference/2003.................................               8           0.160               3           0.099
Difference/2004.................................               2           0.112               2           0.125
----------------------------------------------------------------------------------------------------------------

    The baseline emissions associated with the runs above totaled
approximately 3,344 tons per year of SO2 and 3,129 tons per
year of NOX for United Taconite, and approximately 1,563
tons per year of SO2 and 2928 tons per year of
NOX for Tilden. The post-control emissions totaled
approximately 233 tons per year of SO2 and 2,435 tons per
year of NOX for United Taconite, and approximately 174 tons
per year of SO2 and 2,414 tons per year of NOX
for Tilden. The United Taconite emissions were based on CEMS data
collected under a 100-percent coal-firing scenario, while Tilden
emissions were based on stack test information collected under a
primarily coal-firing scenario.
    EPA believes that Cliffs' modeled baseline emission rates are low
based on previous BART modeling and figures from the proposed rule.
Expected post-control emissions reductions also appear to be
underestimated. The proposed rule identified baseline emissions of
approximately 5,330 tons per year for NOX and 4,043 tons per
year for SO2 for United Taconite, and approximately 1,153
tons per year of SO2 and 4,613 tons per year of
NOX for Tilden. The BART Guidelines recommend that sources
use the highest 24-hour average actual emission rate, for the most
recent three or five year period of meteorological data, to
characterize the maximum potential benefit. By using a low baseline
emission rate, Cliffs' modeling underestimates the emissions reductions
that will be achieved by the installation of BART controls and the
resulting visibility improvements. However, even though the overall
SO2 and NOX reductions modeled by Cliffs were
over 50 percent lower than the reductions projected in the proposed
rule,\22\ the results still showed significant visibility improvement
at the Boundary Waters. Consequently, EPA believes that Cliffs'
modeling provides further evidence that the visibility improvements
predicted by the ratio approach are reasonable.
---------------------------------------------------------------------------

    \22\ This 50 percent discrepancy applies to United Taconite.
---------------------------------------------------------------------------

    Using the CALPUFF model input and meteorological data files
submitted by Cliffs, EPA, with substantial assistance from the National
Park Service, re-ran the baseline and control-case scenarios for United
Taconite and Tilden with data from the proposed rule. For United
Taconite, the baseline emissions of SO2 and NOX
reflect the emissions presented in the proposed rule. The United
Taconite control emissions for NOX were based on a 1.2 lbs
NOX/MMBtu emission limit and heat inputs of 200 MMBtu/hr for
line 1 and 260 MMBtu/hr for line 2. The United Taconite control
emissions for SO2 were based on an approximate 94-percent
reduction from the base case.\23\ For Tilden, the baseline emissions
for both visibility pollutants were also based on those contained in
the proposed rule. The Tilden control emissions for NOX were
based on a conversion to 100 percent natural gas, with an 80 percent
reduction from the baseline for SO2 and a 65 percent
reduction for NOX. The results of this modeling are shown
below, but only for the most impacted Class I area.
---------------------------------------------------------------------------

    \23\ EPA notes that the control emissions for SO2 at
United Taconite differ between those modeled and those that will be
achieved based on the final rule because EPA is no longer requiring
FGD as a result of the switch to low-sulfur fuels at the facility.
This change will result in higher controlled emissions and would be
expected to lower the visibility improvements demonstrated in the
model slightly.

 Table 4--EPA Modeling--United Taconite Predicted Visibility Results for
                         the Most Impacted Area
------------------------------------------------------------------------
                                                               Boundary
                                                  Boundary   Waters 98th
                 Scenario/year                  Waters days   percentile
                                                over 0.5 DV    delta DV
------------------------------------------------------------------------
Difference/2002...............................           80        1.316
Difference/2003...............................           71        1.223
Difference/2004...............................           62        1.358
------------------------------------------------------------------------

 Table 5--EPA Modeling--Tilden Predicted Visibility Results for the Most
                              Impacted Area
------------------------------------------------------------------------
                                                              Seney 98th
                 Scenario/year                   Seney days   percentile
                                                over 0.5 DV    delta DV
------------------------------------------------------------------------
Difference/2002...............................            0        0.320
Difference/2003...............................            0        0.206
Difference/2004...............................            1        0.165
------------------------------------------------------------------------

    Again, EPA's CALPUFF modeling shows significant visibility
improvement can be expected due to the installation of BART controls at
United Taconite and Tilden. EPA believes that these results lend
additional support to the accuracy of the visibility analysis that was
performed for all facilities in the proposed rule. EPA stands by the
results of its ratio approach and believes that it produced reasonable
results for the sources examined.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.

    Comment: Cliffs commented that the proposed rule failed to properly
integrate the visibility analysis with cost considerations and that EPA
should have identified the costs of controls relative to the visibility
improvement using a $/DV metric. In support of this view, Cliffs
provided data showing that the costs per DV improvement are very high
at two of its facilities: $65 million per DV at United Taconite and
$140 million per DV at Tilden. Finally, Cliffs noted that FLMs have
cited a threshold of $20 million per DV in correspondence with states,
and that any figure beyond this threshold constitutes excessively high
costs for the degree of visibility improvement achieved.
    Response: EPA disagrees that a cost per DV analysis was required.
The BART Guidelines do not require EPA or the states to conduct such an
analysis when evaluating the visibility improvement factor. While the
BART Guidelines suggest cost per DV as a possible parameter for
consideration, its use is entirely discretionary. There are numerous
examples of BART analyses conducted by states and EPA that have not
calculated this metric.
    Moreover, EPA believes that Cliffs' comment underestimates the
visibility impacts from the two facilities that were modeled, leading
to erroneous cost per DV figures. As was explained in detail in the
response to the previous comment, Cliffs substantially underestimated
the baseline emission rates at United Taconite and Tilden, which in
turn resulted in emissions reduction estimates that are also too low.
The BART Guidelines recommend that the highest 24-hour average actual
emission rate, for the most recent three or five-year period of
meteorological data, be used to calculate the maximum potential
benefit. Overall, the emissions reductions predicted by Cliffs'
modeling analysis were less than 50 percent of the emissions reductions
projected by EPA for United Taconite.
    Finally, Cliffs' reference to the $20 million per DV threshold is
misleading. The FLMs recommend that cost per DV be calculated
cumulatively to include improvements at all affected Class I areas.
Cliffs' analysis, on the other hand, only included visibility
improvement at a single Class I area, thereby inflating its total cost
per DV figures.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs commented that NOX-related visibility
improvements should be discounted because nitrate visibility impacts
peak in the winter and winter-time visitation at the affected Class I
areas is significantly less than during other times of the year. Cliffs
noted that the BART Guidelines allow for consideration as to whether
impacts occur ``during the tourist season.''
    Response: EPA agrees that nitrate impacts are more dominant in the
winter. Nonetheless, daily nitrate impacts from April through October
are not trivial. EPA also agrees that the BART Guidelines allow states
to consider the timing of impacts in addition to other factors related
to visibility impairment. However, states are not required to do so,
and to our knowledge, neither Michigan nor Minnesota did so in their
visibility analyses. EPA is not required to substitute a source's
desired exercise of discretion for that of the states. Furthermore,
when promulgating a FIP, EPA stands in the shoes of the state. In that
capacity, EPA is not required to consider the seasonality of impacts
and has chosen not to do so here. Taking into account visitation
contradicts the goal of the regional haze rule of improving visibility
on the 20 percent best and worst days. Indeed, EPA believes that the
experiences of visitors who come to Class I areas during periods other
than the peak visitation season are important and should not be
discounted.
    Commenter: Cliffs Natural Resources and ArcelorMittal Minorca Mine.
    Comment: Cliffs cited a number of other flaws in EPA's overall
approach to visibility that it believed led to unreliable or overstated
impacts from the taconite facilities. First, Cliffs asserted that EPA
used natural visibility conditions that were ``too clear, excluding
conditions such as fires, which had the effect of overstating the
impacts of the facilities modeled relative to natural conditions.
Second, Cliffs asserted that the chemistry in the current EPA-approved
version of CALPUFF, as well as regional photochemical models such as
CAMx, overestimates the impact of NOX emissions on
visibility impairment. Cliffs argued that this is especially true for
winter nitrate haze due to the models' static predictions of ammonia