[Federal Register Volume 76, Number 236 (Thursday, December 8, 2011)]
[Proposed Rules]
[Pages 76646-76673]
[FR Doc No: 2011-31406]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R08-OAR-2011-0870; FRL-9501-4]

Approval and Promulgation of Implementation Plans; South Dakota;
Regional Haze State Implementation Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing to approve a revision to the South Dakota
State Implementation Plan (SIP) addressing regional haze submitted by
the State of South Dakota on January 21, 2011, as amended by a
submittal received on September 19, 2011. This SIP revision was
submitted to address the requirements of the Clean Air Act (CAA or Act)
and our rules that require states to prevent any future and remedy any
existing man-made impairment of visibility in mandatory Class I areas
caused by emissions of air pollutants from numerous sources located
over a wide geographic area (also referred to as the ``regional haze
program'').

DATES: Comments: Comments must be received on or before February 6,
2012.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R08-
OAR-2011-0870, by one of the following methods:
     http://www.regulations.gov. Follow the on-line
instructions for submitting comments.
     Email<EMAIL_ADDRESS>     Fax:<PHONE_NUMBER> (please alert the individual listed in
the FOR FURTHER INFORMATION CONTACT section if you are faxing
comments).
     Mail: Director, Air Program, Environmental Protection
Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop Street, Denver,
Colorado 80202-1129.
     Hand Delivery: Director, Air Program, Environmental
Protection Agency (EPA), Region 8, Mailcode 8P-AR, 1595 Wynkoop Street,
Denver, Colorado 80202-1129. Such deliveries are only accepted Monday
through Friday, 8 a.m. to 4:30 p.m., excluding Federal holidays.
Special arrangements should be made for deliveries of boxed
information.
    Instructions: Direct your comments to Docket ID No. EPA-R08-OAR-
2011-0870. EPA's policy is that all comments received will be included
in the public docket without change and may be made available online at
http://www.regulations.gov, including any personal information
provided, unless the comment includes information claimed to be
Confidential Business Information (CBI) or other information whose
disclosure is restricted by statute. Do not submit information that you
consider to be CBI or otherwise protected through http://www.regulations.gov or e-mail. The http://www.regulations.gov Web site
is an ``anonymous access'' system, which means EPA will not know your
identity or contact information unless you provide it in the body of
your comment. If you send an e-mail comment directly to EPA, without
going through http://www.regulations.gov, your e-mail address will be
automatically captured and included as part of the comment that is
placed in the public docket and made available on the Internet. If you
submit an electronic comment, EPA recommends that you include your name
and other contact information in the body of your comment and with any
disk or CD-ROM you submit. If EPA cannot read your comment due to
technical difficulties and cannot contact you for clarification, EPA
may not be able to consider your comment. Electronic files should avoid
the use of special characters, any form of encryption, and be free of
any defects or viruses. The Regional Office's official hours of
business are Monday through Friday, 8:30-4:30 p.m., excluding Federal
holidays.

FOR FURTHER INFORMATION CONTACT: Gail Fallon, EPA Region 8, at (303)
312-6281, or<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

Definitions

    For the purpose of this document, we are giving meaning to certain
words or initials as follows:
    (i) The words or initials Act or CAA mean or refer to the Clean Air
Act, unless the context indicates otherwise.
    (ii) The words EPA, we, us or our mean or refer to the United
States Environmental Protection Agency.
    (iii) The initials SIP mean or refer to State Implementation Plan.
    (iv) The initials NAAQS mean or refer to National Ambient Air
Quality Standards.
    (v) The words South Dakota and State mean the State of South
Dakota.

Table of Contents

I. Background
    A. Regional Haze
    B. Roles of Agencies in Addressing Regional Haze
II. Requirements for Regional Haze SIPs
    A. The CAA and the Regional Haze Rule
    B. Determination of Baseline, Natural and Current Visibility
Conditions

    C. Determination of Reasonable Progress Goals
    D. Best Available Retrofit Technology (BART)
    E. Long-Term Strategy (LTS)
    F. Coordinating Regional Haze and Reasonably Attributable
Visibility Impairment (RAVI)
    G. Monitoring Strategy and Other SIP Requirements
    H. Consultation With States and Federal Land Managers (FLMs)
III. Our Evaluation of South Dakota's Regional Haze SIP
    A. Affected Class I Areas
    B. Determination of Baseline, Natural and Current Visibility
Conditions
    1. Estimating Natural Visibility Conditions
    2. Estimating Baseline Visibility Conditions
    3. Natural Visibility Impairment
    4. Uniform Rate of Progress
    C. BART
    1. Identification of BART-Eligible Sources
    2. Identification of Sources Subject to BART
    a. Modeling Methodology
    b. Contribution Threshold
    c. Sources Identified by South Dakota as Subject to BART
    3. BART Determinations and Federally Enforceable Limits
    a. Otter Tail Power Company, Big Stone I
    b. South Dakota's BART Results and Summary
    D. Evaluation of South Dakota's Reasonable Progress Goals
    1. WRAP Visibility Modeling
    2. Reasonable Progress ``Four-Factor'' Analyses
    3. South Dakota's Conclusions From the Four-Factor Analysis
    4. Establishment of the Reasonable Progress Goals
    5. Reasonable Progress Consultation
    6. Our Conclusion on South Dakota's Reasonable Progress Goals
    E. LTS
    1. Emissions Inventories
    2. Sources of Visibility Impairment in South Dakota Class I
Areas
    3. Visibility Projection Modeling
    4. Consultation and Emissions Reductions for Other States' Class
I Areas
    5. Mandatory LTS Factors
    a. Reductions Due to Ongoing Air Pollution Programs
    b. Measures To Mitigate the Impacts of Construction Activities
    c. Emission Limitation and Schedules of Compliance
    d. Source Retirement and Replacement Schedules
    e. Agricultural and Forestry Smoke Management Techniques
    f. Enforceability of South Dakota's Measures
    g. Anticipated Net Effect on Visibility Due to Projected Changes
    6. Our Conclusion on South Dakota's LTS
    F. Coordination of RAVI and Regional Haze Requirements
    G. Monitoring Strategy and Other SIP Requirements
    H. FLM Coordination
    I. Periodic SIP Revisions and Five-Year Progress Reports
IV. Proposed Action
V. Statutory and Executive Order Reviews

I. Background

A. Regional Haze

    Regional haze is visibility impairment that is produced by a
multitude of sources and activities which are located across a broad
geographic area and emit particulate matter with a diameter less than
2.5 microns (PM2.5) (e.g., sulfates, nitrates, organic
carbon (OC), elemental carbon (EC) and soil dust) and its precursors
(e.g., sulfur dioxide (SO2), nitrogen oxides
(NOX), and in some cases, ammonia (NH3) and
volatile organic compounds (VOCs)). These precursors react in the
atmosphere to form PM2.5. PM2.5 impairs
visibility by scattering and absorbing light. Visibility impairment
reduces the clarity, color and visible distance that one can see.
PM2.5 also can cause serious health effects and mortality in
humans and contributes to environmental effects such as acid deposition
and eutrophication.
    Data from the ``Interagency Monitoring of Protected Visual
Environments'' (IMPROVE) monitoring network show that visibility
impairment caused by air pollution occurs virtually all the time at
most national park and wilderness areas. The average visual range \1\
in many Class I areas (i.e., national parks, memorial parks, wilderness
areas and international parks meeting certain size criteria) in the
western United States is 100-150 kilometers, or about one-half to two-
thirds of the visual range that would exist without anthropogenic air
pollution. 64 FR 35714, 35715 (July 1, 1999). In most of the eastern
Class I areas of the United States, the average visual range is less
than 30 kilometers, or about one-fifth of the visual range that would
exist under estimated natural conditions. Id.
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    \1\ Visual range is the greatest distance, in kilometers or
miles, at which a dark object can be viewed against the sky.
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    In section 169A of the 1977 Amendments to the CAA, Congress created
a program for protecting visibility in the nation's national parks and
wilderness areas. This section of the CAA establishes as a national
goal the ``prevention of any future, and the remedying of any existing,
impairment of visibility in mandatory Class I federal areas \2\ which
impairment results from man-made air pollution.'' CAA Sec.  169A(a)(1).
The terms ``impairment of visibility'' and ``visibility impairment''
are defined in the Act to include a reduction in visual range and
atmospheric discoloration. Id. section 169A(g)(6). In 1980, we
promulgated regulations to address visibility impairment in Class I
areas that is ``reasonably attributable'' to a single source or small
group of sources, i.e., ``RAVI.'' 45 FR 80084 (December 2, 1980). These
regulations represented the first phase in addressing visibility
impairment. We deferred action on regional haze that emanates from a
variety of sources until monitoring, modeling and scientific knowledge
about the relationships between pollutants and visibility impairment
had improved.
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    \2\ Areas designated as mandatory Class I Federal areas consist
of national parks exceeding 6000 acres, wilderness areas and
national memorial parks exceeding 5000 acres, and all international
parks that were in existence on August 7, 1977. See CAA section
162(a). In accordance with section 169A of the CAA, EPA, in
consultation with the Department of Interior, promulgated a list of
156 areas where visibility is identified as an important value. See
44 FR 69122, November 30, 1979. The extent of a mandatory Class I
area includes subsequent changes in boundaries, such as park
expansions. CAA section 162(a). Although states and tribes may
designate as Class I additional areas which they consider to have
visibility as an important value, the requirements of the visibility
program set forth in section 169A of the CAA apply only to
``mandatory Class I federal areas.'' Each mandatory Class I Federal
area is the responsibility of an FLM. See CAA section 302(i). When
we use the term ``Class I area'' in this action, we mean a
``mandatory Class I federal area.''
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    Congress added section 169B to the CAA in 1990 to address regional
haze issues, and we promulgated regulations addressing regional haze in
1999. 64 FR 35714 (July 1, 1999), codified at 40 CFR part 51, subpart
P. The Regional Haze Rule revised the existing visibility regulations
to integrate into them provisions addressing regional haze impairment
and establish a comprehensive visibility protection program for Class I
areas. The requirements for regional haze, found at 40 CFR 51.308 and
51.309, are included in our visibility protection regulations at 40 CFR
51.300-309. Some of the main regional haze requirements are summarized
in section II of this action. The requirement to submit a Regional Haze
SIP applies to all 50 states, the District of Columbia and the Virgin
Islands. States were required to submit a SIP addressing regional haze
visibility impairment no later than December 17, 2007.\3\ 40 CFR
51.308(b).
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    \3\ EPA's regional haze regulations require subsequent updates
to the regional haze SIPs. 40 CFR 51.308(g)-(i).
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    Few states submitted a Regional Haze SIP prior to the December 17,
2007 deadline, and on January 15, 2009, EPA found that 37 states,
including South Dakota and the District of Columbia, and the Virgin
Islands, had failed to submit SIPs addressing the regional

haze requirements. 74 FR 2392. Once EPA has found that a state has
failed to make a required submission, EPA is required to promulgate a
FIP within two years unless the state submits a SIP and the Agency
approves it within the two year period. CAA Sec.  110(c)(1).

B. Roles of Agencies in Addressing Regional Haze

    Successful implementation of the regional haze program will require
long-term regional coordination among states, tribal governments and
various Federal agencies. Pollution affecting the air quality in Class
I areas can be transported over long distances, even hundreds of
kilometers. Therefore, to effectively address the problem of visibility
impairment in Class I areas, states need to develop strategies in
coordination with one another, taking into account the effect of
emissions from one jurisdiction on the air quality in another.
    Because the pollutants that lead to regional haze can originate
from sources located across broad geographic areas, we have encouraged
the states and tribes across the United States to address visibility
impairment from a regional perspective. Five regional planning
organizations (RPOs) were formed to address regional haze and related
issues. The RPOs first evaluated technical information to better
understand how their states and tribes impact Class I areas across the
country, and then pursued the development of regional strategies to
reduce emissions of particulate matter (PM) and other pollutants
leading to regional haze.
    The Western Regional Air Program (WRAP) is a collaborative effort
of state governments, tribal governments and various Federal agencies
established to conduct data analyses, conduct pollutant transport
modeling and coordinate planning activities among the western states.
Member state governments include: Alaska, Arizona, California,
Colorado, Idaho, Montana, New Mexico, North Dakota, Oregon, South
Dakota, Utah, Washington and Wyoming. Tribal members include Campo Band
of Kumeyaay Indians, Confederated Salish and Kootenai Tribes, Cortina
Indian Rancheria, Hopi Tribe, Hualapai Nation of the Grand Canyon,
Native Village of Shungnak, Nez Perce Tribe, Northern Cheyenne Tribe,
Pueblo of Acoma, Pueblo of San Felipe and the Shoshone-Bannock Tribe of
Fort Hall.

II. Requirements for Regional Haze SIPs

    The following is a summary of the requirements of the Regional Haze
Rule. See 40 CFR 51.308 for further detail regarding the requirements
of the rule.

A. The CAA and the Regional Haze Rule

    Regional Haze SIPs must assure reasonable progress towards the
national goal of achieving natural visibility conditions in Class I
areas. Section 169A of the CAA and our implementing regulations require
states to establish long-term strategies for making reasonable progress
toward meeting this goal. Implementation plans must also give specific
attention to certain stationary sources that were in existence on
August 7, 1977, but were not in operation before August 7, 1962, and
require these sources, where appropriate, to install Best Available
Retrofit Technology (BART) controls for the purpose of eliminating or
reducing visibility impairment. The specific Regional Haze SIP
requirements are discussed in further detail below.

B. Determination of Baseline, Natural and Current Visibility Conditions

    The Regional Haze Rule establishes the deciview (dv) as the
principal metric for measuring visibility. See 70 FR 39104, 39118. This
visibility metric expresses uniform changes in the degree of haze in
terms of common increments across the entire range of visibility
conditions, from pristine to extremely hazy conditions. Visibility is
sometimes expressed in terms of the visual range, which is the greatest
distance in kilometers or miles at which a dark object can just be
distinguished against the sky. The deciview is a useful measure for
tracking progress in improving visibility, because each deciview change
is an equal incremental change in visibility perceived by the human
eye. Most people can detect a change in visibility of one deciview.\4\
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    \4\ The preamble to the Regional Haze Rule provides additional
details about the deciview. 64 FR 35714, 35725 (July 1, 1999).
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    The deciview is used in expressing reasonable progress goals (RPGs)
(which are interim visibility goals towards meeting the national
visibility goal), defining baseline, current and natural conditions,
and tracking changes in visibility. The Regional Haze SIPs must contain
measures that ensure ``reasonable progress'' toward the national goal
of preventing and remedying visibility impairment in Class I areas
caused by man-made air pollution by reducing anthropogenic emissions
that cause regional haze. The national goal is a return to natural
conditions, i.e., man-made sources of air pollution would no longer
impair visibility in Class I areas.
    To track changes in visibility over time at each of the 156 Class I
areas covered by the visibility program (40 CFR 81.401-437), and as
part of the process for determining reasonable progress, states must
calculate the degree of existing visibility impairment at each Class I
area at the time of each Regional Haze SIP submittal and periodically
review progress every five years midway through each 10-year
implementation period. To do this, the Regional Haze Rule requires
states to determine the degree of impairment (in deciviews) for the
average of the 20 percent least impaired (``best'') and the average of
the 20 percent most impaired (``worst'') visibility days over a
specified time period at each of their Class I areas. In addition,
states must also develop an estimate of natural visibility conditions
for the purpose of comparing progress toward the national goal. Natural
visibility is determined by estimating the natural concentrations of
pollutants that cause visibility impairment and then calculating total
light extinction based on those estimates. We have provided guidance to
states regarding how to calculate baseline, natural and current
visibility conditions.\5\
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    \5\ Guidance for Estimating Natural Visibility Conditions Under
the Regional Haze Rule, September 2003, EPA-454/B-03-005, available
at http://www.epa.gov/ttncaaa1/t1/memoranda/RegionalHaze _
envcurhr_gd.pdf, (hereinafter referred to as ``our 2003 Natural
Visibility Guidance''); and Guidance for Tracking Progress Under the
Regional Haze Rule, (September 2003, EPA-454/B-03-004, available at
http://www.epa.gov/ttncaaa1/t1/memoranda/rh_tpurhr_gd.pdf,
(hereinafter referred to as our ``2003 Tracking Progress
Guidance'').
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    For the first Regional Haze SIPs that were due by December 17,
2007, ``baseline visibility conditions'' were the starting points for
assessing ``current'' visibility impairment. Baseline visibility
conditions represent the degree of visibility impairment for the 20
percent least impaired days and 20 percent most impaired days for each
calendar year from 2000 to 2004. Using monitoring data for 2000 through
2004, states are required to calculate the average degree of visibility
impairment for each Class I area, based on the average of annual values
over the five-year period. The comparison of initial baseline
visibility conditions to natural visibility conditions indicates the
amount of improvement necessary to attain natural visibility, while the
future comparison of baseline conditions to the then current conditions
will indicate the amount of progress made. In general, the 2000-2004
baseline period is considered the time from which improvement in
visibility is measured.

C. Determination of Reasonable Progress Goals

    The vehicle for ensuring continuing progress towards achieving the
natural visibility goal is the submission of a series of Regional Haze
SIPs from the states that establish two reasonable progress goals
(i.e., two distinct goals, one for the ``best'' and one for the
``worst'' days) for every Class I area for each (approximately) 10-year
implementation period. See 40 CFR 51.308(d), (f). The Regional Haze
Rule does not mandate specific milestones or rates of progress, but
instead calls for states to establish goals that provide for
``reasonable progress'' toward achieving natural (i.e., ``background'')
visibility conditions. In setting reasonable progress goals, states
must provide for an improvement in visibility for the most impaired
days over the (approximately) 10-year period of the SIP, and ensure no
degradation in visibility for the least impaired days over the same
period. Id.
    In establishing reasonable progress goals, states are required to
consider the following factors established in section 169A of the CAA
and in our Regional Haze Rule at 40 CFR 51.308(d)(1)(i)(A): (1) The
costs of compliance; (2) the time necessary for compliance; (3) the
energy and non-air quality environmental impacts of compliance; and (4)
the remaining useful life of any potentially affected sources. States
must demonstrate in their SIPs how these factors are considered when
selecting the reasonable progress goals for the best and worst days for
each applicable Class I area. In setting the reasonable progress goals,
states must also consider the rate of progress needed to reach natural
visibility conditions by 2064 (referred to as the ``uniform rate of
progress'' or ``glidepath'') and the emission reduction measures needed
to achieve that rate of progress over the 10-year period of the SIP.
Uniform progress towards achievement of natural conditions by the year
2064 represents a rate of progress, which states are to use for
analytical comparison to the amount of progress they expect to achieve.
If a state establishes a reasonable progress goal that provides for a
slower rate of improvement in visibility than the rate that would be
needed to attain natural conditions by 2064, the state must
demonstrate, based on the reasonable progress factors, that the rate of
progress for the implementation plan to attain natural conditions by
2064 is not reasonable, and that the progress goal adopted by the state
is reasonable. In setting reasonable progress goals, each state with
one or more Class I areas (``Class I state'') must also consult with
potentially ``contributing states,'' i.e., other nearby states with
emission sources that may be affecting visibility impairment at the
state's Class I areas. 40 CFR 51.308(d)(1)(iv). In determining whether
a state's goals for visibility improvement provide for reasonable
progress toward natural visibility conditions, EPA is required to
evaluate the demonstrations developed by the state pursuant to
paragraphs 40 CFR 51.308(d)(1)(i) and (d)(1)(ii). 40 CFR
51.308(d)(1)(iii).

D. Best Available Retrofit Technology (BART)

    Section 169A of the CAA directs states to evaluate the use of
retrofit controls at certain larger, often uncontrolled, older
stationary sources with the potential to emit 250 tons or more per year
of any pollutant in order to address visibility impacts from these
sources. Specifically, section 169A(b)(2)(A) of the Act requires states
to revise their SIPs to contain such measures as may be necessary to
make reasonable progress towards the natural visibility goal, including
a requirement that certain categories of existing major stationary
sources \6\ built between 1962 and 1977 procure, install and operate
BART as determined by the state or by EPA in the case of a plan
promulgated under section 110(c) of the CAA. Under the Regional Haze
Rule, states are directed to conduct BART determinations for such
``BART-eligible'' sources that may be anticipated to cause or
contribute to any visibility impairment in a Class I area. Rather than
requiring source-specific BART controls, states also have the
flexibility to adopt an emissions trading program or other alternative
program as long as the alternative provides greater reasonable progress
towards improving visibility than BART.
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    \6\ The ``major stationary sources'' potentially subject to BART
are listed in CAA section 169A(g)(7).
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    On July 6, 2005, we published the Guidelines for BART
Determinations Under the Regional Haze Rule at appendix Y to 40 CFR
part 51 (``BART Guidelines'') to assist states 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. In making a BART determination for a fossil fuel-fired
electric generating plant with a total generating capacity in excess of
750 megawatts (MW), a state must use the approach set forth in the BART
Guidelines. A state is encouraged, but not required, to follow the BART
Guidelines in making BART determinations for other types of sources.
Regardless of source size or type, a state must meet the requirements
of the CAA and our regulations for selection of BART, and the state's
BART analysis and determination must be reasonable in light of the
overarching purpose of the regional haze program.
    The process of establishing BART emission limitations can be
logically broken down into three steps: First, states identify those
sources which meet the definition of ``BART-eligible source'' set forth
in 40 CFR 51.301 \7\; second, states determine which of such sources
``emits any air pollutant which may reasonably be anticipated to cause
or contribute to any impairment of visibility in any such area'' (a
source which fits this description is ``subject to BART''); and third,
for each source subject to BART, states then identify the best
available type and level of control for reducing emissions.
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    \7\ BART-eligible sources are those sources that have the
potential to emit 250 tons or more of a visibility-impairing air
pollutant, were not in operation prior to August 7, 1962, but were
in existence on August 7, 1977, and whose operations fall within one
or more of 26 specifically listed source categories. 40 CFR 51.301.
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    States must address all visibility-impairing pollutants emitted by
a source in the BART determination process. The most significant
visibility-impairing pollutants are SO2, NOX and
PM. We have stated that states should use their best judgment in
determining whether VOC or NH3 compounds impair visibility
in Class I areas.
    Under the BART Guidelines, states may select an exemption threshold
value for their BART modeling, below which a BART-eligible source would
not be expected to cause or contribute to visibility impairment in any
Class I area. The state must document this exemption threshold value in
the SIP and must state the basis for its selection of that value. Any
source with emissions that model above the threshold value would be
subject to a BART determination review. The BART Guidelines acknowledge
varying circumstances affecting different Class I areas. States should
consider the number of emission sources affecting the Class I areas at
issue and the magnitude of the individual sources' impacts. Any
exemption threshold set by the state should not be higher than 0.5
deciviews. 40 CFR part 51, appendix Y, section III.A.1.
    In their SIPs, states must identify ``BART-eligible sources'' and
``subject-to-BART sources'' and document their

BART control determination analyses. The term ``BART-eligible source''
used in the BART Guidelines means the collection of individual emission
units at a facility that together comprises the BART-eligible source.
In making BART determinations, section 169A(g)(2) of the CAA requires
that states consider the following factors: (1) The costs of
compliance; (2) the energy and non-air quality environmental impacts of
compliance; (3) any existing pollution control technology in use at the
source; (4) the remaining useful life of the source; and (5) the degree
of improvement in visibility which may reasonably be anticipated to
result from the use of such technology. See also 40 CFR
51.308(e)(1)(ii)(A).
    A Regional Haze SIP must include source-specific BART emission
limits and compliance schedules for each source subject to BART. Once a
state has made its BART determination, the BART controls must be
installed and in operation as expeditiously as practicable, but no
later than five years after the date of our approval of the Regional
Haze SIP. CAA section 169(g)(4) and 40 CFR 51.308(e)(1)(iv). In
addition to what is required by the Regional Haze Rule, general SIP
requirements mandate that the SIP must also include all regulatory
requirements related to monitoring, recordkeeping, and reporting for
the BART controls on the source. See CAA section 110(a). As noted
above, the Regional Haze Rule allows states to implement an alternative
program in lieu of BART so long as the alternative program can be
demonstrated to achieve greater reasonable progress toward the national
visibility goal than would BART.

E. Long Term Strategy (LTS)

    Consistent with the requirement in section 169A(b) of the CAA that
states include in their Regional Haze SIP a 10- to 15 year strategy for
making reasonable progress, section 51.308(d)(3) of the Regional Haze
Rule requires that states include a long term strategy (LTS) in their
Regional Haze SIPs. The LTS is the compilation of all control measures
a state will use during the implementation period of the specific SIP
submittal to meet applicable reasonable progress goals. The LTS must
include ``enforceable emissions limitations, compliance schedules, and
other measures as necessary to achieve the reasonable progress goals''
for all Class I areas within, or affected by emissions from, the state.
40 CFR 51.308(d)(3).
    When a state's emissions are reasonably anticipated to cause or
contribute to visibility impairment in a Class I area(s) located in
another state or states, the Regional Haze Rule requires the state to
consult with the other state(s) in order to develop coordinated
emissions management strategies. 40 CFR 51.308(d)(3)(i). Also, a state
with a Class I area impacted by emissions from another state must
consult with such contributing state, and must also demonstrate that it
has included in its SIP all measures necessary to obtain its share of
the emission reductions needed to meet the reasonable progress goals
for the Class I area. Id. at (d)(3)(ii). The RPOs have provided a forum
for significant interstate consultation, but additional consultations
between states may be required to sufficiently address interstate
visibility issues. This is especially true where two states belong to
different RPOs.
    States should consider all types of anthropogenic sources of
visibility impairment in developing their LTS, including stationary,
minor, mobile and area sources. At a minimum, states must describe how
each of the following seven factors listed below are taken into account
in developing their LTS: (1) Emission reductions due to ongoing air
pollution control programs, including measures to address reasonably
attributable visibility impairment (RAVI); (2) measures to mitigate the
impacts of construction activities; (3) emissions limitations and
schedules for compliance to achieve the reasonable progress goals; (4)
source retirement and replacement schedules; (5) smoke management
techniques for agricultural and forestry management purposes including
plans as currently exist within the state for these purposes; (6)
enforceability of emissions limitations and control measures; and (7)
the anticipated net effect on visibility due to projected changes in
point, area and mobile source emissions over the period addressed by
the LTS. 40 CFR 51.308(d)(3)(v).

F. Coordinating Regional Haze and Reasonably Attributable Visibility
Impairment (RAVI)

    As part of the Regional Haze Rule, we revised 40 CFR 51.306(c)
regarding the LTS for RAVI to require that the RAVI plan must provide
for a periodic review and SIP revision not less frequently than every
three years until the date of submission of the state's first plan
addressing regional haze visibility impairment, which was due December
17, 2007, in accordance with 40 CFR 51.308(b) and (c). On or before
this date, the state must revise its plan to provide for review and
revision of a coordinated LTS for addressing RAVI and regional haze,
and the state must submit the first such coordinated LTS with its first
Regional Haze SIP. Future coordinated LTS and periodic progress reports
evaluating progress towards reasonable progress goals, must be
submitted consistent with the schedule for SIP submission and periodic
progress reports set forth in 40 CFR 51.308(f) and 51.308(g),
respectively. The periodic review of a state's LTS must report on both
regional haze and RAVI and must be submitted to us as a SIP revision.

G. Monitoring Strategy and Other SIP Requirements

    Section 51.308(d)(4) of the Regional Haze Rule includes the
requirement for a monitoring strategy for measuring, characterizing and
reporting of regional haze visibility impairment that is representative
of all mandatory Class I Federal areas within the state. The strategy
must be coordinated with the monitoring strategy required in section
51.305 for RAVI. Compliance with this requirement may be met through
``participation'' in the IMPROVE network, i.e., review and use of
monitoring data from the network. The monitoring strategy is due with
the first Regional Haze SIP, and it must be reviewed every five years.
The monitoring strategy must also provide for additional monitoring
sites if the IMPROVE network is not sufficient to determine whether
reasonable progress goals will be met.
    Under section 51.308(d)(4), the SIP must also provide for the
following:
     Procedures for using monitoring data and other information
in a state with mandatory Class I areas to determine the contribution
of emissions from within the state to regional haze visibility
impairment at Class I areas both within and outside the state;
     Reporting of all visibility monitoring data to the
Administrator at least annually for each Class I area in the state, and
where possible, in electronic format;
     Developing a statewide inventory of emissions of
pollutants that are reasonably anticipated to cause or contribute to
visibility impairment in any Class I area. The inventory must include
emissions for a baseline year, emissions for the most recent year for
which data are available, and estimates of future projected emissions.
A state must also make a commitment to update the inventory
periodically; and
     Other elements, including reporting, recordkeeping and
other measures necessary to assess and report on visibility.
    The Regional Haze Rule requires control strategies to cover an
initial implementation period extending to the

year 2018, with a comprehensive reassessment and revision of those
strategies, as appropriate, every 10 years thereafter. Periodic SIP
revisions must meet the core requirements of section 51.308(d), with
the exception of BART. The requirement to evaluate sources for BART
applies only to the first Regional Haze SIP. Facilities subject to BART
must continue to comply with the BART provisions of section 51.308(e).
Periodic SIP revisions will assure that the statutory requirement of
reasonable progress will continue to be met.

H. Consultation With States and Federal Land Managers (FLMs)

    The Regional Haze Rule requires that states consult with Federal
land managers (FLMs) before adopting and submitting their SIPs. 40 CFR
51.308(i). States must provide FLMs an opportunity for consultation, in
person and at least 60 days prior to holding any public hearing on the
SIP. This consultation must include the opportunity for the FLMs to
discuss their assessment of impairment of visibility in any Class I
area and to offer recommendations on the development of the reasonable
progress goals and on the development and implementation of strategies
to address visibility impairment. Further, a state must include in its
SIP a description of how it addressed any comments provided by the
FLMs. Finally, a SIP must provide procedures for continuing
consultation between the state and FLMs regarding the state's
visibility protection program, including development and review of SIP
revisions, five-year progress reports, and the implementation of other
programs having the potential to contribute to impairment of visibility
in Class I areas.

III. Our Evaluation of South Dakota's Regional Haze SIP

    The State of South Dakota submitted a revision to its SIP to
address the requirements for regional haze on January 21, 2011. On
September 19, 2011, South Dakota submitted an amendment to the Regional
Haze SIP revision for approval into the South Dakota SIP. The amendment
incorporated changes made by the State to ensure approvability of the
SIP revision. The changes incorporated detailed monitoring,
recordkeeping, and reporting requirements for BART sources into state
regulation, Administrative Rules of South Dakota (ARSD) Chapter
74:36:21, including specifying that BART limits apply at all times and
clarified compliance test methods for particulate matter and continuous
emission monitoring system requirements for SO2 and
NOX. In addition, South Dakota revised the reasonable
progress analysis for the GCC Dacotah cement plant. The following is a
discussion of our evaluation of the revision.

A. Affected Class I Areas

    In accordance with 40 CFR 51.308(d), South Dakota identified two
Class I areas within its borders: Badlands National Park and Wind Cave
National Park. South Dakota is responsible for developing reasonable
progress goals for these two Class I areas. South Dakota emissions have
or may reasonably be expected to have impacts at Class I areas in other
states including: Boundary Waters Canoe Area Wilderness Area and
Voyageurs National Park in Minnesota; Medicine Lake National Wildlife
Refuge Wilderness Area and UL Bend National Wildlife Refuge Wilderness
Area in Montana; Bridger Wilderness Area, Fitzpatrick Wilderness Area,
Grand Teton National Park, Teton Wilderness Area, North Absaroka
Wilderness Area, Washakie Wilderness Area and Yellowstone National Park
in Wyoming; and Theodore Roosevelt National Park and Lostwood
Wilderness Area in North Dakota. South Dakota consulted with the
appropriate state air quality agency in each of these states through
their involvement with the WRAP and worked with other states that are
not members of WRAP (including Minnesota and Nebraska). Assessment of
South Dakota's contribution to haze in these Class I areas is based on
technical analyses developed by WRAP.

B. Determination of Baseline, Natural and Current Visibility Conditions

    As required by section 51.308(d)(2)(i) of the Regional Haze Rule
and in accordance with our 2003 Natural Visibility Guidance, South
Dakota calculated baseline/current and natural visibility conditions
for its Class I areas, Badlands and Wind Cave, on the most impaired and
least impaired days, as summarized below. The natural visibility
conditions, baseline visibility conditions and visibility impact
reductions needed to achieve the uniform rate of progress in 2018 for
both South Dakota Class I areas are presented in Table 1 and further
explained in this section. More detail is available in Section 3 of the
South Dakota SIP.\8\
---------------------------------------------------------------------------

    \8\ The visibility and uniform rate of progress calculations
presented in Table 1 and elsewhere in section III.B represent
corrections EPA made to minor math errors in the visibility results
South Dakota presented in the SIP and which the State agrees will be
corrected with the next routine revision of the SIP. Our corrections
are included in the docket in a spreadsheet entitled, EPA-R08-OAR-
2011-0870 South Dakota Regional Haze Proposal Section III.B
Visibility Conditions Corrections.

  Table 1--Visibility Impact Reductions Needed Based on Best and Worst Days Baselines, Natural Conditions and Uniform Rate of Progress (URP) Goals for
                                                               South Dakota Class I Areas
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                20% Worst days                                   20% Best days
                                                         -----------------------------------------------------------------------------------------------
                South Dakota Class I area                                                 2018 Reduction   2064 Natural                    2064 Natural
                                                             2000-2004     2018 URP Goal   needed (delta    conditions       2000-2004      conditions
                                                           Baseline (dv)       (dv)             dv)            (dv)        Baseline (dv)       (dv)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Badlands................................................           17.14           15.02            2.12            8.06            6.89            2.86
National Park...........................................
Wind Cave...............................................           15.84           13.94            1.90            7.71            5.14            1.88
National Park...........................................
--------------------------------------------------------------------------------------------------------------------------------------------------------

1. Estimating Natural Visibility Conditions
    Natural background visibility as defined in our 2003 Natural
Visibility Guidance is estimated by calculating the expected light
extinction using default estimates of natural concentrations of fine
particle components adjusted by site-specific estimates of humidity.
This calculation uses the IMPROVE equation, which is a formula for
estimating light extinction from the estimated natural concentrations
of fine particle components (or from components measured by the IMPROVE
monitors).

As documented in our 2003 Natural Visibility Guidance, EPA allows
states to use ``refined'' or alternative approaches to this guidance to
estimate the values that characterize the natural visibility conditions
of Class I areas. One alternative approach is to develop and justify
the use of alternative estimates of natural concentrations of fine
particle components. Another alternative is to use the ``new IMPROVE
equation'' that was adopted for use by the IMPROVE Steering Committee
in December 2005.\9\ The purpose of this refinement to the ``old
IMPROVE equation'' is to provide more accurate estimates of the various
factors that affect the calculation of light extinction.
---------------------------------------------------------------------------

    \9\ The IMPROVE program is a cooperative measurement effort
governed by a steering committee composed of representatives from
Federal agencies (including representatives from EPA and the FLMs)
and RPOs. The IMPROVE monitoring program was established in 1985 to
aid the creation of Federal and state implementation plans for the
protection of visibility in Class I areas. One of the objectives of
IMPROVE is to identify chemical species and emission sources
responsible for existing anthropogenic visibility impairment. The
IMPROVE program has also been a key participant in visibility-
related research, including the advancement of monitoring
instrumentation, analysis techniques, visibility modeling, policy
formulation and source attribution field studies.
---------------------------------------------------------------------------

    For Badlands and Wind Cave, South Dakota opted to use the revised
IMPROVE equation to calculate natural background conditions. This is an
acceptable approach under our 2003 Natural Visibility Guidance. EPA has
found the use of the revised IMPROVE equation appropriate for WRAP
states.\10\ For Badlands, the natural visibility background for the 20
percent worst days is 8.06 deciviews and for the 20 percent best days
is 2.86 deciviews. For Wind Cave, the natural visibility result for the
20 percent worst days is 7.71 deciviews and for the 20 percent best
days is 1.88 deciviews. We have reviewed South Dakota's estimates of
the natural visibility conditions and as the approach used by the State
was consistent with our 2003 Natural Visibility Guidance we are
proposing to find them acceptable.
---------------------------------------------------------------------------

    \10\ The science behind the revised IMPROVE equation is
summarized in a document entitled, Technical Support Document for
Technical Products Prepared by the Western Regional Air Partnership
(WRAP) in Support of Western Regional Haze Plans, February 28, 2011,
(hereinafter referred to as EPA WRAP Technical Support Document and
available in the docket) and in numerous published papers. See for
example: Hand, J.L., and Malm, W.C., 2006, Review of the IMPROVE
Equation for Estimating Ambient Light Extinction Coefficients--Final
Report. March 2006. Prepared for IMPROVE, Colorado State University,
Cooperative Institute for Research in the Atmosphere, Fort Collins,
Colorado, available at http://vista.cira.colostate.edu/improve/publications/GrayLit/016_IMPROVEeqReview/IMPROVEeqReview.htmand
Pitchford, Marc., 2006, Natural Haze Levels II: Application of the
New IMPROVE Algorithm to Natural Species Concentrations Estimates.
Final Report of the Natural Haze Levels II Committee to the RPO
Monitoring/Data Analysis Workgroup. September 2006, available at
http://vista.cira.colostate.edu/improve/Publications/GrayLit/029_NaturalCondII/naturalhazelevelsIIreport.ppt.
---------------------------------------------------------------------------

2. Estimating Baseline Visibility Conditions
    As required by section 51.308(d)(2)(i) of the Regional Haze Rule,
South Dakota calculated baseline visibility conditions for Badlands and
Wind Cave. The baseline condition calculation begins with the
calculation of light extinction using the IMPROVE equation. The IMPROVE
equation sums the light extinction \11\ resulting from individual
pollutants, such as sulfates and nitrates. As with the natural
visibility conditions calculation, South Dakota chose to use the
revised IMPROVE equation.
---------------------------------------------------------------------------

    \11\ The amount of light lost as it travels over one million
meters. The haze index, in units of dv, is calculated directly from
the total light extinction, bext expressed in inverse
megameters (Mm-1), as follows: HI = 10
ln(bext/10).
---------------------------------------------------------------------------

    The period for establishing baseline visibility conditions is 2000-
2004, and baseline conditions must be calculated using available
monitoring data. 40 CFR 51.308(d)(2). The South Dakota Regional Haze
SIP employed visibility monitoring data collected by IMPROVE monitors
located in both South Dakota Class I areas for the years 2000 through
2004 and the resulting baseline conditions represent an average for
2000-2004. South Dakota calculated the baseline conditions at Badlands
as 17.14 deciviews on the 20 percent worst days, and 6.89 deciviews on
the 20 percent best days. South Dakota calculated the baseline
conditions at Wind Cave as 15.84 deciviews on the 20 percent worst
days, and 5.14 deciviews on the 20 percent best days. We have reviewed
South Dakota's estimations of baseline visibility conditions and
propose to find these acceptable as the approach the State used was
consistent with our 2003 Natural Visibility Guidance.
3. Natural Visibility Impairment
    To address the requirements of 40 CFR 51.308(d)(2)(iv)(A), South
Dakota also calculated the number of deciviews by which baseline
conditions exceed natural visibility conditions at Badlands and Wind
Cave. For Badlands, baseline conditions exceed natural conditions by
9.08 deciviews (17.14-8.06) for the 20 percent worst days and 4.03
deciviews (6.89-2.86) for the 20 percent best days. For Wind Cave,
these figures are 8.13 (15.84-7.71) and 3.26 deciviews (5.14-1.88),
respectively.
4. Uniform Rate of Progress
    In setting the reasonable progress goals, South Dakota analyzed and
determined the uniform rate of progress needed to reach natural
visibility conditions by the year 2064. In so doing, South Dakota
compared the baseline visibility conditions in Badlands and Wind Cave
to the natural visibility conditions in Badlands and Wind Cave (as
described above) and determined the uniform rate of progress needed in
order to attain natural visibility conditions by 2064 in both Class I
areas. South Dakota constructed the uniform rate of progress consistent
with the requirements of the Regional Haze Rule by plotting a straight
graphical line from the baseline level of visibility impairment for
2000-2004 to the level of visibility conditions representing no
anthropogenic impairment in 2064 for Badlands and Wind Cave. The
uniform rates of progress are summarized in Table 2 and further
described below.
    Using a baseline visibility value at Badlands of 17.14 deciviews
and a ``refined'' natural visibility value of 8.06 deciviews for the 20
percent worst days, South Dakota calculated the uniform rate of
progress to be approximately 0.151 deciviews per year (deciviews/year
or dv/yr). This results in a total reduction of 9.08 deciviews to reach
the natural visibility condition of 8.06 deciviews in 2064. The uniform
rate of progress results in a visibility improvement of 2.18 deciviews
needed for the period covered by this SIP revision submittal (up to and
including 2018).
    Using a baseline visibility value at Wind Cave of 15.84 deciviews
and a ``refined'' natural visibility value of 7.71 deciviews for the 20
percent worst days, South Dakota calculated the uniform rate of
progress to be approximately 0.136 deciviews per year. This results in
a total reduction of 8.13 deciviews to reach the natural visibility
condition of 7.71 deciviews in 2064. The uniform rate of progress
results in a visibility improvement of 1.89 deciviews needed for the
period covered by this SIP revision submittal (up to and including
2018).

              Table 2--Summary of Uniform Rates of Progress
------------------------------------------------------------------------
          Class I area                 Badlands            Wind cave
------------------------------------------------------------------------
Baseline Conditions.............  17.14 dv..........  15.84 dv
Natural Visibility..............  8.06 dv...........  7.71 dv
Total Improvement by 2064.......  9.08 dv...........  8.13 dv
Needed Improvement for this SIP   2.18 dv...........  1.89 dv
 by 2018.
URP.............................  0.151 dv/year.....  0.136 dv/year
------------------------------------------------------------------------

    We propose to find that South Dakota has appropriately calculated
the uniform rates of progress.

C. BART

    BART is an element of South Dakota's LTS for the first
implementation period. As discussed in more detail in section II.D of
this preamble, the BART evaluation process consists of three
components: (1) An identification of all the BART-eligible sources; (2)
an assessment of whether those BART-eligible sources are in fact
subject to BART; and (3) a determination of any BART controls. South
Dakota addressed these steps as follows:
1. Identification of BART-Eligible Sources
    The first step of a BART evaluation is to identify all the BART-
eligible sources within the state's boundaries. The State identified
the BART-eligible sources in South Dakota by utilizing the approach set
out in the BART Guidelines (70 FR 39158); this approach provides three
criteria for identifying BART-eligible sources: (1) One or more
emission units at the facility fit within one of the 26 categories
listed in the BART Guidelines; (2) the emission unit(s) began operation
on or after August 7, 1962, and was in existence on August 7, 1977; and
(3) potential emissions of any visibility-impairing pollutant from
subject units are 250 tons or more per year. South Dakota initially
screened its emissions inventory and permitting database to identify
major facilities with emission units in one or more of the 26 BART
categories. Following this, South Dakota used its databases and records
to identify facilities in these source categories with potential
emissions of 250 tons per year or more for any visibility-impairing
pollutant from any units that were in existence on August 7, 1977 and
began operation on or after August 7, 1962.
    The BART Guidelines direct states to address SO2,
NOX and direct PM (including both coarse (PM10)
and fine (PM2.5) particulate matter emissions as visibility-
impairing pollutants and to exercise their ``best judgment to determine
whether VOC or NH3 emissions from a source are likely to
have an impact on visibility in an area.'' See 70 FR 39162. The
available inventory information indicates VOCs in South Dakota
overwhelmingly come from biogenic sources, and NH3 in South
Dakota is primarily due to area sources, such as livestock and
fertilizer application. Because these are not point sources, they are
not subject to BART. We have reviewed this information and propose to
find South Dakota's focus on SO2, NOX, and PM
acceptable.
    South Dakota identified BART-eligible sources in South Dakota as
shown in Table 3. This information is presented in Section 6 of South
Dakota's SIP.

                             Table 3--List of BART-Eligible Sources in South Dakota
----------------------------------------------------------------------------------------------------------------
       BART-eligible source                  Location           BART source category (SC)   Nearest class I area
----------------------------------------------------------------------------------------------------------------
1. Northern States Power Company    Sioux Falls, South Dakota.  SC 1--fossil fuel steam    N/A.\1\
 (Units 1, 2, and 3).                                            electric plants >250
                                                                 MMBtu/hr heat input.
2. Otter Tail Power Company, Big    Near Big Stone City, South  SC 1--fossil fuel steam    Boundary Waters
 Stone I (Unit 1).                   Dakota.                     electric plants >250      431 km.
                                                                 MMBtu/hr heat input.
3. Pete Lien and Sons, Inc........  Rapid City, South Dakota..  SC 12--lime plants.......  Wind Cave
                                                                                52 km.
----------------------------------------------------------------------------------------------------------------
\1\ South Dakota did not analyze the three units at Northern States Power for distance to Class I areas as they
  have been decommissioned.

2. Identification of Sources Subject to BART
    The second step of the BART evaluation is to identify those BART-
eligible sources that may reasonably be anticipated to cause or
contribute to any visibility impairment at any Class I area, i.e. those
sources that are subject to BART. The BART Guidelines allow states to
consider exempting some BART-eligible sources from further BART review
because they may not reasonably be anticipated to cause or contribute
to any visibility impairment in a Class I area.
a. Modeling Methodology
    The BART Guidelines provide that states may use the CALPUFF \12\
modeling system or another appropriate model to predict the visibility
impacts from a single source on a Class I area and to, therefore,
determine whether an individual source is anticipated to cause or
contribute to impairment of visibility in Class I areas, i.e., ``is
subject to BART.'' The BART Guidelines state that we find CALPUFF is
the best regulatory modeling application currently available for
predicting a single source's contribution to visibility impairment (70
FR 39162).
---------------------------------------------------------------------------

    \12\ Note that our reference to CALPUFF encompasses the entire
CALPUFF modeling system, which includes the CALMET, CALPUFF, and
CALPOST models and other pre and post processors. The different
versions of CALPUFF have corresponding versions of CALMET, CALPOST,
etc. which may not be compatible with previous versions (e.g., the
output from a newer version of CALMET may not be compatible with an
older version of CALPUFF). The different versions of the CALPUFF
modeling system are available from the model developer at http://www.src.com/verio/download/download.htm.
---------------------------------------------------------------------------

    The BART Guidelines also recommend that states develop a modeling
protocol for making individual source attributions, and suggest that
states may want to consult with us and their RPO to address any issues
prior to modeling. South Dakota relied on WRAP's CALPUFF modeling for
South Dakota BART sources as

recommended by the BART Guidelines.\13\ 40 CFR part 51, appendix Y,
section III.A.3.
---------------------------------------------------------------------------

    \13\ The WRAP modeling protocol is available at http://pah.cert.ucr.edu/aqm/308/bart/WRAP_RMC_BART_Protocol_Aug15_2006.pdf.
---------------------------------------------------------------------------

    To determine if each BART-eligible source has a significant impact
on visibility, South Dakota used WRAP's CALPUFF modeling results to
estimate daily visibility impacts above estimated natural conditions at
each Class I area within 300 km of any BART-eligible facility, based on
maximum actual 24-hour emissions over a three year period (2000-2002).
b. Contribution Threshold
    For states using modeling to determine the applicability of BART to
single sources, the BART Guidelines note that the first step is to set
a contribution threshold to assess whether the impact of a single
source is sufficient to cause or contribute to visibility impairment at
a Class I area. The BART Guidelines state that, ``[a] single source
that is responsible for a 1.0 deciview change or more should be
considered to `cause' visibility impairment.'' 70 FR 39104, 39161. The
BART Guidelines also state that ``the appropriate threshold for
determining whether a source contributes to visibility impairment may
reasonably differ across states,'' but, ``[a]s a general matter, any
threshold that you use for determining whether a source `contributes'
to visibility impairment should not be higher than 0.5 deciviews.'' Id.
Further, in setting a contribution threshold, states should ``consider
the number of emissions sources affecting the Class I areas at issue
and the magnitude of the individual sources' impacts.'' The Guidelines
affirm that states are free to use a lower threshold if they conclude
that the location of a large number of BART-eligible sources in
proximity to a Class I area justifies this approach.
    South Dakota used a contribution threshold of 0.5 deciviews for
determining which sources are subject to BART. The State's decision was
based on the following factors: (1) 0.5 deciviews equates to the 5%
extinction threshold for new sources under the Prevention of
Significant Deterioration (PSD) New Source Review rules, (2) 0.5
deciviews is consistent with the threshold selected by other states in
the west, which all selected 0.5 deciviews, and (3) 0.5 deciviews
represents the limit of perceptible change. Although we do not agree
that all of the factors considered by South Dakota's Department of
Environmental and Natural Resources are relevant in determining whether
a source can be considered to cause or contribute to visibility
impairment, we propose to approve the State's threshold of 0.5
deciviews. As the discussion below indicates, Big Stone I is the only
BART-eligible source in South Dakota in operation. Given that and the
fact that the modeling indicates that Big Stone I is reasonably
anticipated to have an impact over the 0.5 deciview threshold at
several Class I Areas, it is apparent that no BART-eligible sources
were exempted from review based on the 0.5 deciviews threshold that
could have had meaningful impact on visibility in one or more Class I
areas. We are proposing that 0.5 deciviews is a reasonable threshold
for South Dakota in determining whether its BART-eligible sources are
subject to BART.
c. Sources Identified by South Dakota as Subject to BART
    South Dakota determined that the three units at Northern States
Power were not subject to BART because the units have been
decommissioned and are no longer permitted to operate under the
facility's Title V air quality permit. Consistent with the BART
Guidelines, South Dakota requested that WRAP model each of its
remaining operating BART-eligible sources to assess the extent of their
contribution to visibility impairment at surrounding Class I areas.
    The WRAP modeling results demonstrated that Pete Lien and Sons,
Inc. did not cause or contribute to visibility impairment at any Class
I area. After reviewing the modeling inputs, South Dakota determined
that the vertical kiln should be modeled again due to several errors.
However, before additional modeling could be done, Pete Lien and Sons,
Inc. shut down and dismantled the kiln in 2009 per its Title V
permit.\14\
---------------------------------------------------------------------------

    \14\ Although Pete Lien and Sons' existing Title V air quality
permit still identifies the vertical kiln as a unit, permit
condition 1.1 specifies in the footnote of Table 1-1 that Pete Lien
and Sons is required to shutdown and dismantle the vertical kiln
before the initial startup of Unit 45. Pete Lien and Sons
fulfilled this commitment by notifying South Dakota on March 13,
2009, that the vertical kiln was shutdown and dismantled. See SIP
Section 6.1.2.
---------------------------------------------------------------------------

    The WRAP modeling results for Otter Tail Power Company's Big Stone
I are summarized in Table 4. The results show that Big Stone I's
emissions cause visibility impacts that exceed the 0.5 deciviews
threshold at the Badlands National Park in South Dakota, Theodore
Roosevelt National Park in North Dakota, and Boundary Waters Wilderness
and Voyageurs National Park in Minnesota.

                                Table 4--WRAP's Modeling Results for Big Stone I
----------------------------------------------------------------------------------------------------------------
                                                                             Minimum distance   98th percentile
                  Class I area                             State             to class I area   visibility impact
                                                                                (km)              (dv)\1\
----------------------------------------------------------------------------------------------------------------
Badlands.......................................  SD                                       470              0.683
Boundary Waters................................  MN                                       431              1.034
Bridger........................................  WY                                     1,041              0.001
Fitzpatrick....................................  WY                                     1,050              0.001
Grand Teton....................................  WY                                     1,112              0.001
Lostwood.......................................  ND                                       585              0.263
Medicine Lake..................................  MT                                       690              0.256
North Absaroka.................................  WY                                     1,013              0.011
Teton..........................................  WY                                     1,052              0.004
Theodore Roosevelt.............................  ND                                       555              0.687
UL Bend........................................  MT                                       902              0.089
Voyageurs......................................  MN                                       438              0.729
Washakie.......................................  WY                                     1,006              0.007
Wind Cave......................................  SD                                       572              0.263

Yellowstone....................................  WY                                     1,049              0.009
----------------------------------------------------------------------------------------------------------------
\1\ Modeling results represent the maximum 98th percentile impact over the modeled 3-year meteorological period
  2001-2003.

    South Dakota allowed Otter Tail Power Company to re-run the
modeling after the company identified several errors in actual emission
rates and stack parameters. After additional review, Otter Tail Power
Company developed a revised modeling protocol that both the State and
EPA approved. The modeling protocol is included in Appendix A of the
SIP. The results from Otter Tail's modeling are summarized in Table 5.
Otter Tail's modeling report is included in Appendix B of the SIP.

         Table 5--Otter Tail's Modeling Results for Big Stone I
------------------------------------------------------------------------
                                                               98th
                                                            percentile
                      Class I area                          visibility
                                                              impact
                                                              (dv)\1\
------------------------------------------------------------------------
Badlands................................................             0.5
Boundary Waters.........................................             1.1
Lostwood................................................             0.4
Theodore Roosevelt......................................             0.5
Voyageurs...............................................             0.7
Wind Cave...............................................             0.3
Isle Royale.............................................             0.7
------------------------------------------------------------------------
\1\ Modeling results represent the maximum 98th percentile impact over
  the modeled meteorological years 2002, 2006, and 2007.

    In reviewing Otter Tail's results, the State rounded to one
significant figure and determined that Big Stone I emissions cause
visibility impacts that exceed the 0.5 deciviews threshold at the same
Class I areas identified in the WRAP modeling in addition to Isle
Royale in Michigan. South Dakota relied on Otter Tail's modeling,
noting that it best represented the visibility impacts from Big Stone I
because the original WRAP modeling did not have the correct emission
rates and stack parameters and that the modeling protocol adjustments
improved the accuracy of the model over long distances.
3. BART Determinations and Federally Enforceable Limits
    The third step of a BART evaluation is to perform the BART
analysis. The BART Guidelines (70 FR 39164) describe the BART analysis
as consisting of the following five steps:
     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, and
     Step 5: Evaluate Visibility Impacts.
    In determining BART, the State must consider the five statutory
factors in section 169A of the CAA: (1) The costs of compliance; (2)
the energy and non-air quality environmental impacts of compliance; (3)
any existing pollution control technology in use at the source; (4) the
remaining useful life of the source; and (5) the degree of improvement
in visibility which may reasonably be anticipated to result from the
use of such technology. See also 40 CFR 51.308(e)(1)(ii)(A). The five-
factor analysis occurs during steps 4 and 5 of the process.
    South Dakota requested that Otter Tail Power Company complete a
BART analysis for Big Stone I and used this analysis as a basis for its
BART determination for this source for NOX, SO2
and PM. The Otter Tail BART analysis is included in Appendix C of the
SIP. Otter Tail generally followed the five steps contained in the BART
Guidelines and evaluated the five BART factors. In some instances,
South Dakota identified additional control technologies for evaluation
and also added an analysis of average cost effectiveness compared to
visibility benefit (dollar per deciview) for the various multi-
pollutant control options. We find that South Dakota, through its
reliance on Otter Tail's BART analysis, reasonably considered the five
BART factors and arrived at a reasonable BART determination for Big
Stone I. We propose to approve South Dakota's BART determination
summarized below.
a. Otter Tail Power Company, Big Stone I
Background
    Big Stone I is a steam electric generating plant located near Big
Stone City, South Dakota with one generating unit burning Powder River
Basin coal and a net electrical output of 475 MW. The Otter Tail Power
Company is the operating agent for the Big Stone Plant co-owners:
NorthWestern Energy, Montana-Dakota Utilities, Co., a division of MDU
Resources Group, and Otter Tail Power Company. The generating unit is a
Babcock cyclone boiler that started operating in 1975. The State
analyzed each pollutant and its effect on the visibility in Class I
areas. Since Big Stone I does not have a total generating capacity
greater than 750 MW, South Dakota was not required to follow the BART
Guidelines in determining BART, but it generally followed the approach
for determining BART set out in the Guidelines. A summary of the
State's analyses of existing controls and potential BART controls for
each pollutant is set forth below. The State's BART determination for
Big Stone I is provided in Section 6 of the SIP. The visibility and
cost impacts noted in the following assessment are derived from the
company's BART analysis provided in Appendix B of the SIP.\15\
---------------------------------------------------------------------------

    \15\ Otter Tail's costs rely on the CUECost model. While we are
satisfied with the State's control technology conclusions as further
described in this section, in general we do not recommend relying on
the CUECost model. According to the BART Guidelines, ``cost
estimates should be based on the OAQPS Control Cost Manual, where
possible'' ``[i]n order to maintain and improve consistency.'' 70 FR
39104, 39166. The OAQPS Control Cost Manual is now known as The EPA
Air Pollution Control Cost Manual, EPA/452/B-02-001, 6th Ed.,
January 2002.
---------------------------------------------------------------------------

Unit 1 Boiler
    SO2 BART Review: Unit 1 has no existing SO2 controls.
The baseline uncontrolled SO2 emissions that South Dakota
reported in the SIP are 18,000 tons per year.
    Step 1: Identify All Available Technologies.
    The State identified the following SO2 control options
as having potential application to Unit 1: Fuel switching, coal
cleaning, coal upgrading (K-Fuel), hydrated lime injection, semi-dry
flue gas desulfurization (FGD), wet FGD, Enviroscrub, electro catalytic
oxidation and the Airborne process.
    Step 2: Eliminate Technically Infeasible Options.
    The State eliminated the following options as technically
infeasible: Coal

cleaning, coal upgrading, hydrated lime injection, Enviroscrub, Electro
catalytic oxidation and the Airborne process. Fuel switching is a
viable method to reduce sulfur dioxide emissions by switching to a fuel
with lower sulfur content. The Big Stone facility's primary fuel source
is subbituminous coal obtained from the Powder River Basin in Wyoming.
Powder River Basin subbituminous coal has one of the lowest sulfur
contents available in the United States. As such, the State concluded
that Otter Tail Power Company has already implemented fuel switching.
    Step 3: Evaluate Control Effectiveness of Remaining Control
Technology.
    The State considered the control efficiencies listed in Table 6.

          Table 6--Summary of Big Stone I SO2 BART Analysis Control Technologies for Unit 1 Boiler \1\
----------------------------------------------------------------------------------------------------------------
                                                                                Emissions
             Control option                    Control        Emission rate   Emissions (tons/  reduction  (tons/
                                           efficiency  (%)     (lb/MMBtu)            yr)               yr)
----------------------------------------------------------------------------------------------------------------
Wet FGD 1......................                95             0.043               900            17,100
Wet FGD 2......................                83              0.15             3,130            14,870
Semi-Dry FGD 1.................                90              0.09             1,880            16,120
Semi-Dry FGD 2.................                83              0.15             3,130            14,870
----------------------------------------------------------------------------------------------------------------
\1\ South Dakota calculated emissions from a baseline of 18,000 tons per year of SO2. The baseline was derived
  from the highest average 24-hour average emission rate (4,832 pounds per hour) for calendar years 2001 through
  2003 and operations occurring 85% of the time or 7,746 hours per year.

    Step 4: Evaluate Impacts and Document Results.
    Factor 1: Costs of compliance.
    The State relied on Otter Tail's cost analysis for SO2
controls and this is summarized below in Table 7. The State deemed the
average cost effectiveness reasonable for the two remaining control
options, semi-dry and wet FGD.

                    Table 7--Summary of Big Stone I SO2 BART Cost Analysis for Unit 1 Boiler
----------------------------------------------------------------------------------------------------------------
                                           Total installed                        Emissions           Cost
             Control option                 capital cost      Total annual    reduction  (tons/   effectiveness
                                                (MM$)          cost  (MM$)           yr)             ($/ton)
----------------------------------------------------------------------------------------------------------------
Wet FGD 1......................            $171.8            $29.05            17,100            $1,699
Wet FGD 2......................             171.8             28.90            14,870             1,944
Semi-Dry FGD 1.................             141.3             23.57            16,120             1,462
Semi-Dry FGD 2.................             141.3             23.33            14,870             1,569
----------------------------------------------------------------------------------------------------------------

    Factor 2: Energy impacts.
    The State noted increased energy demand estimates provided by Otter
Tail of 9,500 kilowatts (2.0 percent of generation) for wet FGD and
3,325 kilowatts (0.7 percent of generation) for semi-dry FGD. The State
did not identify any energy requirements that would preclude the
selection of either of the two alternatives.
    Factor 3: Non-air quality environmental impacts.
    The State described the non-air quality environmental impacts of
the two control alternatives including the solid and aqueous waste
streams. The semi-dry FGD system would be installed upstream of the
existing baghouse. The baghouse would be used to collect the injected
lime and reacted sulfur dioxide emissions along with other existing
particulate matter emissions. Otter Tail did not identify how much
additional particulate matter would be collected by the baghouse due to
the use of the semi-dry FGD system. Otter Tail assumed the additional
material collected in the baghouse would be negligible compared to the
existing collection. Otter Tail estimated that the wet FGD system would
generate an additional 44,700 tons of gypsum solids which would need to
be properly disposed. The State did not identify any non-air quality
effects that would preclude the selection of either of the two
alternatives.
    Factor 4: Remaining useful life.
    The expected remaining useful life of the unit is greater than 30
years.
    Factor 5: Evaluate visibility impacts.
    Table 8 presents a comparison of the visibility impacts of the two
top control options, wet FGD and semi-dry FGD. The values are derived
from modeling conducted by Otter Tail. For the cases presented, Otter
Tail held the emission rates for NOX and PM constant but
varied the SO2 emissions rates in the model as noted. In
some cases, the modeling predicted that the semi-dry FGD would produce
a greater visibility benefit than the wet FGD. It is not clear why the
model predicted this result; it may relate to stack parameters. Based
on the visibility modeling, the State found that there would be no
discernible visibility benefit from selecting a wet FGD over a semi-dry
FGD.

               Table 8--Visibility Impact Comparison Between Wet and Semi-Dry FGD SO2 Controls \1\
                                          [98th Percentile--Deciviews]
----------------------------------------------------------------------------------------------------------------
     Option \2\        Control equipment      Class I area \4\         2002            2006            2007
----------------------------------------------------------------------------------------------------------------
3.........  OFA and Semi-dry FGD   Boundary Waters.....           0.319           0.534           0.620
                      (0.09 lb/MMBtu).
                                            Voyageurs...........           0.307           0.391           0.450
                                            Isle Royale.........           0.363           0.287           0.323
                                            Badlands............           0.219           0.172           0.230
                                            Theodore Roosevelt..           0.087           0.234           0.173
4.........  OFA and Wet FGD        Boundary Waters.....           0.350           0.521           0.611
                      (0.043 lb/MMBtu).

                                            Voyageurs...........           0.312           0.464           0.502
                                            Isle Royale.........           0.351           0.250           0.290
                                            Badlands............           0.225           0.191           0.234
                                            Theodore Roosevelt..           0.084           0.230           0.138
                     Comparison Review \3\  Boundary Waters.....           0.031          -0.013          -0.009
                      (incremental
                      visibility impact of
                      wet FGD (in Option
                      3) compared to semi-
                      dry FGD (in Option
                      4)).
                                            Voyageurs...........           0.005           0.073           0.052
                                            Isle Royale.........          -0.012          -0.037          -0.033
                                            Badlands............           0.006           0.019           0.004
                                            Theodore Roosevelt..          -0.003          -0.004          -0.035
5a........  SOFA and Semi-dry FGD  Boundary Waters.....           0.250           0.419           0.493
                      (0.09 lb/MMBtu).
                                            Voyageurs...........           0.249           0.306           0.354
                                            Isle Royale.........           0.285           0.226           0.256
                                            Badlands............           0.165           0.133           0.180
                                            Theodore Roosevelt..           0.069           0.186           0.141
5b........  SOFA and Wet FGD       Boundary Waters.....           0.274           0.407           0.478
                      (0.043 lb/MMBtu).
                                            Voyageurs...........           0.244           0.365           0.393
                                            Isle Royale.........           0.274           0.195           0.227
                                            Badlands............           0.174           0.147           0.182
                                            Theodore Roosevelt..           0.066           0.180           0.108
                     Comparison Review \3\  Boundary Waters.....           0.024          -0.012          -0.015
                      (incremental
                      visibility impact of
                      wet FGD (in Option
                      5a) compared to semi-
                      dry FGD (in Option
                      5b)).
                                            Voyageurs...........          -0.005           0.059           0.039
                                            Isle Royale.........          -0.011          -0.031          -0.029
                                            Badlands............           0.009           0.014           0.002
                                            Theodore Roosevelt..          -0.003          -0.006          -0.033
----------------------------------------------------------------------------------------------------------------
\1\ Otter Tail Power Company conducted visibility modeling for both wet and semi-dry FGD options using combined
  controls with constant emission rates for NOX and PM. Thus, the results shown include the noted SO2 and NOX
  control options and the existing fabric filter PM control option.
\2\ An explanation of each of the numbered control options and the corresponding emission rates is included in
  Section 6 of the SIP, Table 6-13, p. 94.
\3\ A negative number means the wet FGD had a lower visibility impact than the semi-dry FGD.
\4\ These are the Class I areas that exceed the 0.5 deciview threshold as listed in Table 5.

    Step 5: Select BART.
    South Dakota determined BART to be the second ranked control
option, semi-dry FGD at 90 percent control efficiency in Section
<IP_ADDRESS> of the SIP. Even though the top ranked control option, wet FGD
at 95 percent control efficiency, reduced the SO2 emissions
more than the second ranked option, the State determined that there is
no discernible difference between the two options when considering
visibility impacts. South Dakota specified BART limits of 505 lb/hour
and 0.09 lb/MMBtu (30-day rolling average) that apply at all times
including periods of startup, shutdown and malfunction. The estimated
cost of the semi-dry FGD system was $1,462 per ton ($/ton) of
SO2 removed, and the capital and annualized costs were
estimated to be $141,300,000 and $23,570,000 per year ($/year or $/yr),
respectively.
    We are proposing to approve the State's SO2 BART
determination for Big Stone I. The State's assessment of costs and
other impacts and its elimination of the wet FGD at 95% control
efficiency was reasonable based on the five-factor analysis. While the
average cost effectiveness values for both wet FGD and semi-dry FGD are
reasonable, the modeling predicted that the use of a wet FGD at 95%
efficiency rather than a semi-dry FGD at 90% efficiency would result in
minimal, if any, visibility benefit. Thus, it was reasonable for the
State to eliminate a wet FGD at 95% efficiency from consideration. The
installation of a semi-dry FGD at Big Stone I will result in a
reduction in annual SO2 emissions from the plant of
approximately 16,120 tons.\16\ The visibility benefit for the selected
BART controls for all pollutants combined is provided in the summary in
Table 12 in section III.C.3.b. below.
---------------------------------------------------------------------------

    \16\ The selected SO2 emission limit of 0.09 lb/MMBtu
(30-day rolling average) also happens to be well below the
presumptive limit for EGU's without existing controls and over the
750 MW generating capacity threshold described in the BART
Guidelines.
---------------------------------------------------------------------------

    NOX BART Review: Big Stone I is already equipped with overfire air
(OFA) for NOX control. South Dakota indicates in the SIP
that Unit 1 has baseline controlled NOX emissions of 18,000
tons per year with an emission rate of 0.65 lb/MMBtu.
    Step 1: Identify All Available Technologies.
    South Dakota identified the following control options as having
potential application as BART: Selective catalytic reduction (SCR),
oxygen enhanced combustion, catalytic absorption/oxidation, gas reburn,
Enviroscrub, electro-catalytic oxidation, NOXStar, Cascade
processes, selective non-catalytic reduction (SNCR), rich reagent
injection (RRI), flue gas recirculation (FGR), separated over-fire air
(SOFA), over-fire air (OFA), and low-NOX burners (LNB).

    Step 2: Eliminate Technically Infeasible Options.
    The State identified the following control options as technically
infeasible: Oxygen enhanced combustion, absorption/oxidation, gas
reburn, Enviroscrub, electro-catalytic oxidation, NOXStar,
Cascade processes, and LNB. The State noted that flue gas recirculation
is not known to reduce nitrogen oxide emissions any further when added
with an over-fire air system. Therefore, the State and Otter Tail Power
Company did not conduct any further review of flue-gas recirculation.
    Step 3: Evaluate Control Effectiveness of Remaining Control
Technology.
    The State considered the control efficiencies listed in Table 9.

          Table 9--Summary of Big Stone I NOX BART Analysis Control Technologies for Unit 1 Boiler \1\
----------------------------------------------------------------------------------------------------------------
                                                                                Emissions
             Control option                    Control       Emission  rate   Emissions (tons/  reduction  (tons/
                                           efficiency (%)      (lb/MMBtu)            yr)               yr)
----------------------------------------------------------------------------------------------------------------
SCR and SOFA............................                89              0.10             2,000            16,000
RRI, SNCR and SOFA......................                77              0.20             4,090            13,910
SNCR and SOFA...........................                60              0.35             7,220            10,780
SOFA....................................                42              0.50            10,360             7,640
OFA.....................................                25              0.65            13,490             4,510
----------------------------------------------------------------------------------------------------------------
\1\ South Dakota calculated emissions from a baseline of 18,000 tons per year of NOX. The baseline was derived
  from the highest average 24-hour average emission rate (4,855 pounds per hour) for calendar years 2001 through
  2003 and operations occurring 85% of the time or 7,746 hours per year.

    Step 4: Evaluate Impacts and Document Results.
    Factor 1: Costs of compliance.
    The State relied on Otter Tail's cost analysis for NOX
controls and this is summarized below in Table 10. The State deemed the
average cost effectiveness reasonable for all of the remaining control
options, SCR, SNCR, RRI, SOFA, and OFA, as provided by Otter Tail.

                    Table 10--Summary of Big Stone I NOX BART Cost Analysis for Unit 1 Boiler
----------------------------------------------------------------------------------------------------------------
                                          Total  installed                        Emissions       Average cost
             Control option                 capital cost      Total  Annual   reduction  (tons/   effectiveness
                                               (MM$)           cost (MM$)            yr)             ($/ton)
----------------------------------------------------------------------------------------------------------------
SCR and SOFA...........................              $81.9            $13.21            16,000              $825
RRI, SNCR and SOFA.....................               16.2             11.39            13,910               818
SNCR and SOFA..........................               11.9              3.99            10,780               197
SOFA...................................                4.8              0.65             7,640                85
OFA....................................                0                0.14             4,510                31
----------------------------------------------------------------------------------------------------------------

    Factor 2: Energy impacts.
    The State noted that all the energy impacts were less than one
percent of the plant's generating capacity and did not identify any
energy requirements that would preclude the selection of any of the
alternatives.
    Factor 3: Non-air quality environmental impacts.
    The State discussed that the OFA and SOFA systems would increase
the amount of unburned carbon in the flyash, which would increase the
amount of flyash that needs to be properly disposed. Otter Tail Power
Company considers this increase negligible compared to the existing
amount of flyash being properly disposed.
    The State noted that the SNCR and the SCR systems would generate a
small amount of unreacted ammonia or urea to be emitted. Even though
ammonia and urea are not considered regulated air pollutants, these
emissions are involved in the formation of ammonium sulfates and
ammonium nitrates, which contribute to the amount of visibility
impairment.
    The State did not identify any non-air quality environmental
impacts that would preclude the selection of any of the control
equipment alternatives.
    Factor 4: Remaining useful life.
    The expected remaining useful life of the unit is greater than 30
years.
    Factor 5: Evaluate visibility impacts.
    Table 12, below, presents the visibility impacts for the State's
selected BART controls for all pollutants. The values presented come
from Otter Tail's modeling. The State found that SCR + SOFA would
result in greater visibility improvement than the other options.
    Step 5: Select BART.
    South Dakota determined BART to be SCR + SOFA. South Dakota
specified BART limits of 561 lb/hour and 0.10 lb/MMBtu (30-day rolling
average) that apply at all times including periods of startup,
shutdown, and malfunction. The estimated cost of the SCR + SOFA
controls was $825 per ton ($/ton) of NOX removed, and the
capital and annualized costs were estimated to be $81,800,000, and
$13,210,000 per year ($/year or $/yr), respectively.
    We are proposing to approve the State's NOX BART
determination for Big Stone I. The State's assessment of costs and
other impacts was reasonable. The installation of SCR and SOFA at Big
Stone I will result in a reduction in annual NOX emissions
from the plant of approximately 16,000 tons. Table 12, below, provides
the visibility benefit for the selected BART controls for all
pollutants combined.
    PM BART Review: Big Stone I is already equipped with a pulse jet
fabric filter baghouse for PM which is considered the most efficient
control technology available. The baseline controlled PM emissions that
South Dakota reported in the SIP are 300 tons per year with an emission
rate of 0.015 lb/MMBtu. The State identified the following PM control
options as having potential application to the Big Stone I boiler:
Existing fabric filter baghouse, new fabric filter baghouse, compact
hybrid particulate collector (COHPAC), electrostatic precipitator, wet
scrubber,

and cyclones/multiclones. The State did not eliminate any of the
control technologies as technically infeasible for controlling PM
emissions from the boiler.
    South Dakota determined BART to be no additional controls. The
State reviewed the five BART factors generally, but noted no further
detailed analysis was required since Otter Tail has already installed
and is operating a fabric filter baghouse, which is the top particulate
control technology. South Dakota specified BART limits of 67.3 lb/hour
and 0.012 lb/MMBtu (30-day rolling average). The latter represents a
stringent level of control that is consistent with recent Best
Available Control Technology determinations for PSD permits.
    We are proposing to approve the State's PM BART determination for
Big Stone I. The State's assessment that no detailed analysis is
required since the most stringent control option is already in place is
consistent with the BART Guidelines. (40 CFR 51, appendix Y, IV.D.5.)
Furthermore, since South Dakota's proposed BART emission limits does
not explicitly exempt emissions during malfunctions, we interpret the
SIP to require compliance with the PM limits at all times (including
malfunctions).
b. South Dakota's BART Results and Summary
    We have summarized South Dakota's BART determinations in Table 11
below. We have summarized the visibility impacts at the appropriate
Class I areas for South Dakota's selected BART controls in Table 12
below. The substantial emissions reductions in SO2 and
NOX will result in a significant improvement in visibility
at several Class I areas. The visibility improvement from reducing both
pollutants at the most impacted area, Boundary Waters, is estimated to
be 0.9 deciviews and 54 fewer days above 0.5 deciviews.\17\
---------------------------------------------------------------------------

    \17\ The 0.9 deciviews estimated visibility benefit at Boundary
Waters is calculated by subtracting the 2007 impact of 0.17
deciviews in Table 12 from the baseline impact of 1.1 deciviews in
Table 5. Our calculations for 54 fewer days above 0.5 deciviews are
included in the docket.
---------------------------------------------------------------------------

    South Dakota's Regional Haze Rule, which we are proposing to
approve with the SIP, requires each source subject to BART to install
and operate BART no later than five years after we approve the Regional
Haze SIP. Administrative Rules of South Dakota (ARSD) Chapter 74:36:21.
Given the scope of the retrofits involved, five years represents a
schedule that is expeditious as practicable. This satisfies the
requirement under 40 CFR 51.308(e)(1)(iv), that ``each source subject
to BART be required to install and operate BART as expeditiously as
practicable, but in no event later than 5 years after approval of the
implementation plan revision.''
    As noted previously, to be approvable, the Regional Haze SIP must
include monitoring, recordkeeping, and reporting requirements to ensure
that the BART limits are enforceable. South Dakota has included these
requirements in ARSD Chapter 74:36:21. We have reviewed these
requirements and find them to be adequate as they relate to the BART
limits we are proposing to approve. In particular, for SO2
and NOX BART limits, the rule requires the use of continuous
emission monitoring systems (CEMS) to determine compliance, generally
in accordance with 40 CFR part 75. For the filterable PM BART limits,
the rule requires stack testing. Adequate recordkeeping and reporting
requirements are also specified.
    For the reasons discussed above, we propose to find that South
Dakota satisfied the BART requirements of 40 CFR 51.308(e).

                    Table 11--South Dakota BART Determinations for Big Stone I Unit 1 Boiler
----------------------------------------------------------------------------------------------------------------
                 Baseline     Baseline   BART  level                    Emissions
                emissions     level of   of  control                      after       Emission
  Pollutant       (tons/    control  (%       (%       Control device    controls    reduction    Emission limit
                  yr)\1\     reduction)   reduction)                    (tons/yr)    (tons/yr)
----------------------------------------------------------------------------------------------------------------
SO2..........       18,000            0           90  Semi-dry FGD...        1,880       16,120  505 lb/hr, and
                                                                                0.09 lb/MMBtu,
                                                                                30-day rolling
                                                                                average.
NOX..........       18,000           25           88  SOFA + SCR.....        2,000       16,000  561 lb/hr, and
                                                                                0.10 lb/MMBtu,
                                                                                30-day rolling
                                                                                average.
PM...........          300      95-99.9      95-99.9  Existing Fabric  ...........  ...........  67.3 lb/hr, and
                                                       Filter.                                    0.012 lb/
                                                                                MMBtu, 30-day
                                                                                rolling
                                                                                average.
----------------------------------------------------------------------------------------------------------------
\1\ South Dakota calculated baseline emissions for SO2 and NOX by identifying the highest average 24-hour
  average actual emission rate for the years 2001 through 2003 and adjusted this to 85% operations level or
  7,746 hours per year.

        Table 12--Visibility Impacts for South Dakota's BART Determinations for Big Stone I Unit 1 Boiler
                                          [98th Percentile--Deciviews]
----------------------------------------------------------------------------------------------------------------
          Control options                 Class I area            2002              2006              2007
----------------------------------------------------------------------------------------------------------------
SCR, SOFA, and Semi-Dry FGD \1\....  Boundary Waters......             0.097             0.136             0.170
                                     Voyageurs............             0.086             0.107             0.123
                                     Isle Royale..........             0.092             0.077             0.098
                                     Badlands.............             0.079             0.060             0.070
                                     Theodore Roosevelt...             0.036             0.070             0.064
----------------------------------------------------------------------------------------------------------------
\1\ The results reflect the visibility impacts after installation of controls with an SCR at a NOX emissions
  rate of 0.1 lb/MMBtu, a semi-dry FGD at an SO2 emissions rate of 0.15 lb/MMBtu, and the existing pulse jet
  fabric filter baghouse at a PM emissions rate of 0.015 lb/MMBtu. The selected BART emissions limits for SO2
  and PM are lower than the modeled values, therefore, the visibility impacts after BART controls are installed
  will be lower than those presented in this table. See Table 8 for a comparison of visibility impacts for wet
  and semi-dry FGD. See Table 5 for baseline visibility impacts.

D. Evaluation of South Dakota's Reasonable Progress Goals

    In order to establish reasonable progress goals for Badlands and
Wind Cave and to determine the controls needed for the LTS, South
Dakota followed the process established in the Regional Haze Rule.
First, South Dakota identified the anticipated visibility improvement
in 2018 in the two South Dakota Class I areas using the WRAP Community
Multi-Scale Air Quality (CMAQ) photochemical grid modeling results.
This modeling identified the extent of visibility improvement from the
baseline by pollutant for each Class I area. The modeling relied on
projected source emission inventories, which included enforceable
Federal and state regulations already in place and anticipated BART
controls.
    South Dakota then identified, with input from EPA, the sources and
source categories (other than BART sources) in South Dakota that are
major contributors to visibility impairment and considered whether
these sources should be controlled based on a consideration of the
factors identified in the CAA and EPA's regulations. See CAA 169A(g)(1)
and 40 CFR 51.308(d)(1)(i)(A). South Dakota also computed the baseline
visibility impacts for these sources using their 2002 actual emissions
and the CALPUFF modeling system. Next, based on this analysis, South
Dakota set the reasonable progress goals for each Class I area and
compared the reasonable progress goals for each area to the 2018
uniform rate of progress. The SIP includes South Dakota's analysis and
conclusion that reasonable progress will be made by 2018, including an
analysis of pollutant trends, emission reductions, and improvements
expected. The reasonable progress discussion and analyses are included
in Section 7 of the SIP. We are proposing to approve South Dakota's
submitted reasonable progress goals as described more fully below.
1. WRAP Visibility Modeling
    The primary tool WRAP relied upon for modeling regional haze
improvements by 2018, and for estimating South Dakota's Reasonable
Progress Goals, was the CMAQ model. The CMAQ model was used to estimate
2018 visibility conditions in South Dakota and all western Class I
areas, based on application of anticipated regional haze strategies in
the various states' regional haze plans, including assumed controls on
BART sources.\18\
---------------------------------------------------------------------------

    \18\ We provide a more detailed discussion on the WRAP modeling
in section IV.E.3 below and in the EPA WRAP Technical Support
Document available in the docket.
---------------------------------------------------------------------------

2. Reasonable Progress ``Four-Factor'' Analysis
    In determining the measures necessary to make reasonable progress,
states must take into account the following four factors and
demonstrate how they were taken into consideration in selecting
reasonable progress goals for a Class I area:
     Costs of Compliance,
     Time Necessary for Compliance,
     Energy and Non-Air Quality Environmental Impacts of
Compliance, and
     Remaining Useful Life of any Potentially Affected Sources.
    CAA 169A(g)(1) and 40 CFR 308(d)(1)(i)(A).
    As the purpose of the reasonable progress analysis is to evaluate
the potential of controlling certain sources or source categories for
addressing visibility from manmade sources, the four-factor analysis
conducted by South Dakota addresses only anthropogenic sources, on the
assumption that the focus should be on sources that can be
``controlled.'' In its evaluation of potential sources or source
categories for reasonable progress, South Dakota primarily considered
point sources. South Dakota determined that the key pollutants
contributing to visibility impairment at the two Class I areas are
SO2, organic carbon and NOX. South Dakota also
only considered controls for emissions of SO2 and
NOX (i.e., sulfate and nitrate) which are typically
associated with anthropogenic sources. South Dakota determined the
major source of organic carbon in the two Class I areas is natural
fire. By reviewing the WRAP modeling results, South Dakota determined
that PM emissions from point sources contribute only a minimal amount
to visibility impairment in the South Dakota Class I areas.
    Based on the WRAP CMAQ modeling, South Dakota's contribution of
ammonia sulfate, organic carbon mass, and ammonia nitrate
concentrations is approximately 1.5% for ammonia sulfate, minimal for
organic carbon mass, and 4% for ammonia nitrate. Therefore, South
Dakota concluded that minimal gain would be achieved from further
reduction in sulfur dioxide, organic carbon mass, and nitrogen oxide
emissions from point sources within South Dakota. More discussion on
sources of sulfate and nitrate emissions and the State's rationale for
focusing on point sources is included in Section 7 of the SIP. South
Dakota initially asserted that a four-factor analysis was not warranted
based on its belief that Badlands and Wind Cave would both achieve the
needed reductions to meet the uniform rate of progress for both Class I
areas despite the WRAP predictions. This belief was based on the
State's conclusion that the emission estimates included in the WRAP
modeling turned out to be too high. The emission estimates did not
include reductions reflecting the BART emission limits for Otter Tail
Power Company's BigStone I facility but did include anticipated
emissions from two proposed coal-fired power plants--Big Stone II and
NextGen. The Big Stone II facility will not be constructed and the
NextGen facility is on hold indefinitely.
    However, South Dakota did not remodel with revised emissions
estimates to demonstrate that the uniform rate of progress would be met
for Badlands and Wind Cave. EPA therefore requested that South Dakota
perform a four-factor analysis for three facilities, at a minimum: the
Black Hills Ben French power plant, the GCC Dacotah cement plant, and
the Pete Lien and Sons lime plant. South Dakota did perform a four-
factor analysis for Black Hills Ben French and GCC Dacotah based on the
WRAP's report, Supplementary Information for Four-Factor Analyses for
Selected Individual Facilities in South Dakota, May 19, 2009, authored
by EC/R (hereinafter referred to as the EC/R Report). The EC/R Report
is included in Appendix F of the SIP. The EC/R report did not address
the Pete Lien and Sons lime plant.
    During our review of South Dakota's four-factor analysis, we
analyzed actual emissions data from EPA's 2002 National Emissions
Inventory database. We started with the emissions inventory totals for
SO2 and NOX then divided the actual emissions (Q)
in tons per year from the sources by their distance (D) in kilometers
to the nearest Class I Federal area. A summary list of the largest
sources we reviewed in our Q/D analysis is included below in Table 13.

                               Table 13--EPA Q/D Analysis for South Dakota Sources
----------------------------------------------------------------------------------------------------------------
                                                             SO2 + NOX 2000-     Distance to     Q/D to closest
                          Source                              2004 average     nearest Class I    Class I area
                                                                 (tons)           area (km)         (tons/km)
----------------------------------------------------------------------------------------------------------------
Black Hills, Ben French Power Plant.......................             1,782                65             27.41
GCC Dacotah...............................................             4,465                66             67.66
John Morrell & Company....................................               648               410              1.58
Merillat Industries Inc...................................               135                58              2.33
Pete Lien and Sons, Inc...................................               276                59              4.68
----------------------------------------------------------------------------------------------------------------

    South Dakota did not undertake a reasonable progress analysis of
John Morrell & Company or Merillat Industries, Inc. Given the low Q/D
values associated with these two sources, we are proposing to find that
South Dakota's approach was reasonable.
    Although Pete Lien and Sons, Inc. also had a Q/D of less than 10,
the State did consider whether controls should be required for
reasonable progress. South Dakota opted, however, not to conduct a full
four-factor analysis on Pete Lien and Sons but did a general review of
the impacts of this facility. Pete Lien and Sons' SO2
emissions are less than 1 ton/year and so have a de minimus impact on
visibility in any Class I area. For NOX, the State has
determined that the plant is already required to use what is considered
Best Available Control Technology (BACT), and thus no further controls
are required. As further explanation, the 2002 NOX emissions
for Pete Lien and Sons were 272 tons/year. In May 2008, the company
included a BACT analysis for NOX in a PSD application for a
new preheater-type rotary lime kiln and ancillary equipment for this
facility. The BACT analysis found non-selective catalytic reduction and
selective catalytic reduction to be technically infeasible for several
reasons including temperatures and the location of injection nozzles.
South Dakota reviewed the application at the time and agreed with the
conclusion that BACT for a lime rotary kiln was considered good
combustion practices. South Dakota conducted a further review of EPA's
RACT/BACT/LAER Clearinghouse to determine if any new rotary lime kilns
had been permitted since Pete Lien and Sons' PSD application had been
submitted with more stringent post-combustion BACT controls. There were
three entries. One occurred in each of the states of Texas, Ohio, and
Wisconsin. The Texas source only involved carbon monoxide. In Ohio and
Wisconsin, the permitting authorities had concluded in the BACT
analyses for NOX that no control technologies were cost
effective and that good combustion practices were considered BACT. The
State concluded there were no new rotary lime kilns that had been
required to install post-combustion NOX controls for BACT.
As a result, the State concluded that such controls would not
constitute BART.
    South Dakota also evaluated Pete Lien and Sons' visibility impacts
at Badlands and Wind Cave by conducting a CALPUFF modeling analysis.
The modeling report is included in Appendix I of the SIP. A summary of
the modeling results is provided below in Table 14.

    Table 14--Summary of Baseline Visibility Impacts From Reasonable
                   Progress Source Pete Lien and Sons
                          [98th Percentile, dv]
------------------------------------------------------------------------
                  Year                       Badlands        Wind Cave
------------------------------------------------------------------------
2002....................................            0.05            0.06
2006....................................            0.06            0.05
2007....................................            0.07            0.05
------------------------------------------------------------------------

    We propose to approve South Dakota's less detailed analysis for
Pete Lien and conclusion that no controls are required. A Q/D value of
10 is generally viewed as a conservative threshold for identifying
facilities that may have significant source-specific impacts. We
consider a Q/D threshold of 10 to be reasonable for this planning
period based on the FLM's proposed FLAG Guidance amendments for initial
screening criteria, as well as statements in EPA's BART guidelines.\19\
For Pete Lien and Sons, the Q/D of 4.68 is well below this threshold;
the baseline visibility impacts analysis by South Dakota in Table 14
confirms that Pete Lien and Sons does not have significant source-
specific impacts.
---------------------------------------------------------------------------

    \19\ The relevant language in our BART Guidelines reads, ``Based
on our analyses, we believe that a state that has established 0.5 dv
as a contribution threshold could reasonably exempt from the BART
review process sources that emit less than 500 tons per year of
NOX or SO2 (or combined NOX and
SO2), as long as these sources are located more than 50
kilometers from any Class I area; and sources that emit less than
1000 tons per year of NOX or SO2 (or combined
NOX and SO2) that are located more than 100
kilometers from any Class I area.'' (See 40 CFR 51, appendix Y,
section III, How to Identify Sources ``Subject to BART.'') The
values described equate to a Q/D of 10.
---------------------------------------------------------------------------

    South Dakota undertook a more detailed analysis of the two sources
that exceeded a Q/D of 10, Black Hills Ben French and GCC Dacotah.
These sources are further described below in Table 15.

                   Table 15--South Dakota Sources for Reasonable Progress Four-Factor Analyses
----------------------------------------------------------------------------------------------------------------
                                                                                SO2 actual      NOX actual
                                                                                average         average
            Source                   Unit             Type           Capacity     emissions 2002  emissions 2002
                                                                                (tons/yr)       (tons/yr)
----------------------------------------------------------------------------------------------------------------
Black Hills, Ben French Power  Unit 1 Boiler..  EGU............  25 MWe.........             785             907
 Plant.
GCC Dacotah                    Wet Kiln 4.....  Cement Plant...  550 tons                     26             707
                                                                  clinker/day.
                               Wet Kiln 5.....  Cement Plant...  550 tons                    431             388
                                                                  clinker/day.
                               Wet Kiln 6 \1\.  Cement Plant...  2,250 tons                  885           2,267
                                                                  clinker/day.
----------------------------------------------------------------------------------------------------------------
\1\ South Dakota opted not to include Kiln 6 in its four-factor analysis as further described in the State's
  conclusions in section III.D.3 below.

Four-Factor Analysis
    The control options and costs that South Dakota considered were
derived, in part, from the EC/R report. EPA also requested South Dakota
consider SNCR at GCC Dacotah which was not included in the EC/R report.
For the Black Hills Ben French and GCC Dacotah reasonable progress
sources, SO2 and NOX are uncontrolled, although
the Black Hills Ben French facility uses low-sulfur coal (0.33 wt%) to
minimize formation of SO2 during combustion.
Cost of Compliance
    Tables 16 and 17 show the cost of compliance for the control
technologies evaluated for each of the reasonable progress sources.

                          Table 16--Control Option Costs for Reasonable Progress Source Black Hills, Ben French Power Plant \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
            Pollutant                Control option       2002     Control efficiency        Reductions                              Cost effectiveness
-------------------------------------------------------------------------------------------------------------  Capital     Annual       range ($/ton)
                                                                                cost       cost   ---------------------
                                                       (tons/yr)      %          %      (tons/yr)  (tons/yr)   ($1000)    ($1000)    High end   Low end
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX.............................  LNB................        907         30         75        272        680      1,250        195        717        287
                                 -----------------------------------------------------------------------------------------------------------------------
                                  LNB w/OFA..........        907         50         65        454        590      1,780        298        656        505
                                 -----------------------------------------------------------------------------------------------------------------------
                                  SNCR...............        907         30         75        272        680      1,290        770      2,831      1,132
                                 -----------------------------------------------------------------------------------------------------------------------
                                  SCR................        907         40         90        363        816      3,000        754      2,077        924
                                                                                -------------------------------------------
                                                                                4,250      1,068      2,942      1,309
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2.............................  Dry Sorbent                785         10         40         79        314      4,300      1,700     21,519      5,414
                                   Injection.
                                 -----------------------------------------------------------------------------------------------------------------------
                                  Spray Dryer                785  .........         90  .........        707     11,600      2,670  .........      3,777
                                   Absorber.
                                 -----------------------------------------------------------------------------------------------------------------------
                                  Wet FGD............        785  .........         90  .........        707     14,600      2,760  .........      3,904
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The cost analysis was based on a 30-year equipment life. Black Hills indicated the expected life of the Ben French power plant is 10 years. South
  Dakota conducted an additional analysis with a 10-year equipment life. The 10-year evaluation resulted in slightly higher average cost effectiveness
  values but did not change the outcome of the analysis. All controls are cost effective with the exception of the dry sorbent injection at the lowest
  end of the control efficiency range which would not reflect the true performance capability of the technology; we consider the high end of the range
  to be most appropriate.

                               Table 17--Control Option Costs for Reasonable Progress Source GCC Dacotah, Cement Plant \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
           Pollutant               Control option       2002     Control efficiency        Reductions                                Cost effectiveness
-----------------------------------------------------------------------------------------------------------  Capital   Annual cost      range ($/ton)
                                                                                cost       ($1000)  ---------------------
                                                     (tons/yr)      %          %      (tons/yr)  (tons/yr)   ($1000)                 High end   Low end
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Wet Kiln 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX............................  LNB (indirect)....        707         30         40        212        283        526          129        608        456
                                ------------------------------------------------------------------------------------------------------------------------
                                 LNB (direct)......        707  .........         40  .........        283      1,873          331  .........      1,170
                                ------------------------------------------------------------------------------------------------------------------------
                                 Biosolids                 707  .........         23  .........        163  .........  ...........        \2\        \2\
                                  Injection.
                                ------------------------------------------------------------------------------------------------------------------------
                                 CemStar...........        707         20         60        141        424      1,599          299      2,121        705
                                ------------------------------------------------------------------------------------------------------------------------
                                 Mid-Kiln..........        707         20         50        141        354      2,748         -315        \3\        \3\
                                ------------------------------------------------------------------------------------------------------------------------
                                 LoTOxTM...........        707         80         90        566        636  .........  ...........        \2\        \2\
                                ------------------------------------------------------------------------------------------------------------------------
                                 SCR...............        707  .........         80  .........        566     14,813        4,137  .........      7,309
                                ------------------------------------------------------------------------------------------------------------------------
                                 SNCR..............        707         30         40        212        283  .........      878 \3\      4,142      3,102
--------------------------------------------------------------------------------------------------------------------------------------------------------
SO2............................  Wet FGD...........         26         90         99         23         26      9,133        1,370     59,565     52,692
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Wet Kiln 5
--------------------------------------------------------------------------------------------------------------------------------------------------------
NOX............................  LNB (indirect)....        388         30         40        116        155        526          129      1,112        832
                                ------------------------------------------------------------------------------------------------------------------------