Approval and Promulgation of Implementation Plans; State of Idaho; Regional Haze State Implementation Plan and Interstate Transport Plan, 1579-1591 [2011-249]

Agencies

• ENVIRONMENTAL PROTECTION AGENCY

[Federal Register Volume 76, Number 7 (Tuesday, January 11, 2011)]
[Proposed Rules]
[Pages 1579-1591]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-249]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[EPA-R10-OAR-2010-1072, FRL-9250-2]


Approval and Promulgation of Implementation Plans; State of 
Idaho; Regional Haze State Implementation Plan and Interstate Transport 
Plan

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing to approve a State Implementation Plan (SIP) 
revision submitted by the State of Idaho on October 25, 2010, as 
meeting the requirements of Clean Air Act (CAA) section 
110(a)(2)(D)(i)(II) as it applies to visibility for the 1997 8-hour 
ozone and 1997 particulate matter (PM2.5) National Ambient Air Quality 
Standards (NAAQS). EPA is also proposing to approve a portion of the 
revision as meeting certain requirements of the regional haze program, 
including the requirements for best available retrofit technology 
(BART).

DATES: Written comments must be received at the address below on or 
before February 10, 2011.

ADDRESSES: Submit your comments, identified by Docket ID No. EPA-R10-
OAR-2010-1072 by one of the following methods:
     https://www.regulations.gov. Follow the on-line 
instructions for submitting comments.
     E-mail: R10-Public_Comments@epa.gov.
     Mail: Steve Body, EPA Region 10, Suite 900, Office of Air, 
Waste and Toxics, 1200 Sixth Avenue, Seattle, WA 98101.
     Hand Delivery: EPA Region 10, 1200 Sixth Avenue, Suite 
900, Seattle, WA 98101.
    Attention: Steve Body, Office of Air, Waste and Toxics, AWT-107. 
Such deliveries are only accepted during normal hours of operation, and 
special arrangements should be made for deliveries of boxed 
information.
    Instructions: Direct your comments to Docket ID No. EPA-R10-OAR-
2010-1072. EPA's policy is that all comments received will be included 
in the public docket without change and may be made available online at 
https://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 https://www.regulations.gov or e-mail. The https://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 https://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.
    Docket: All documents in the docket are listed in the https://www.regulations.gov index. Although listed in the index, some 
information is not publicly available (e.g., CBI or other information 
whose disclosure is restricted by statute). Certain other material, 
such as copyrighted material, will be publicly available only in hard 
copy form. Publicly available docket materials are available either 
electronically at https://www.regulations.gov or in hard copy at the 
Office of Air, Waste and Toxics, EPA Region 10, 1200 Sixth Avenue, 
Seattle, WA 98101. EPA requests that if at all possible, you contact 
the individual listed below to view a hard copy of the docket.

FOR FURTHER INFORMATION CONTACT: Steve Body at telephone number (206) 
553-0782, body.steve@epa.gov, or the above EPA, Region 10 address.

SUPPLEMENTARY INFORMATION: Throughout this document whenever ``we,'' 
``us,'' or ``our'' is used, we mean the EPA. Information is organized 
as follows:

Table of Contents

I. Background for EPA's Proposed Action
    A. Definition of Regional Haze
    B. Regional Haze Rules and Regulations
    C. Roles of Agencies in Addressing Regional Haze
    D. Interstate Transport for Visibility
II. Requirements for the Regional Haze SIP
    A. The CAA and the Regional Haze Rule
    B. Determination of Baseline, Natural, and Current Visibility 
Conditions
    C. Consultation with States and Federal Land Managers
    D. Best Available Retrofit Technology
III. EPA's Analysis of the Idaho Regional Haze SIP
    A. Affected Class I Areas
    B. Baseline and Natural Conditions
    C. Idaho Emissions Inventories
    D. Sources of Visibility Impairment in Idaho Class I Areas
    E. Best Available Retrofit Technology
    F. TASCO BART Analysis
    G. Monsanto/P4 BART Analysis
    H. Improvement in Visibility from BART at TASCO, Nampa and 
Monsanto/P4
IV. EPA's Analysis of Whether Regional Haze SIP Submittal Meets 
Interstate Transport Requirements
V. What action is EPA proposing?
VI. Scope of Action
VII. Statutory and Executive Order Reviews

I. Background for EPA's Proposed Action

    In the CAA Amendments of 1977, Congress established a program to 
protect and improve visibility in the national parks and wilderness 
areas. See

[[Page 1580]]

CAA section 169(A). Congress amended the visibility provisions in the 
CAA in 1990 to focus attention on the problem of regional haze. See CAA 
section 169(B). EPA promulgated regulations in 1999 to implement 
sections 169A and 169B of the Act. These regulations require states to 
develop and implement plans to ensure reasonable progress toward 
improving visibility in mandatory Class I Federal areas \1\ (Class I 
areas). 64 FR 35714 (July 1, 1999); see also 70 FR 39104 (July 6, 2005) 
and 71 FR 60612 (October 13, 2006).
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    \1\ Areas designated as mandatory Class I Federal areas consist 
of national parks exceeding 6,000 acres, wilderness areas and 
national memorial parks exceeding 5,000 acres, and all international 
parks that were in existence on August 7, 1977. 42 U.S.C. 7472(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. 44 FR 69122 
(November 30, 1979). The extent of a mandatory Class I area includes 
subsequent changes in boundaries, such as park expansions. 42 U.S.C. 
7472(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 a ``Federal Land Manager.'' 42 U.S.C. 7602(i). 
When we use the term ``Class I area'' in this action, we mean a 
``mandatory Class I Federal area.''
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    In this action, EPA is proposing to approve certain provisions of 
Idaho's Regional Haze SIP submission addressing the requirements for 
best available retrofit technology (BART), the calculation of baseline 
and natural visibility conditions, and the statewide inventory of 
visibility-impairing pollutants. EPA is also proposing to approve the 
provisions of Idaho's SIP submittal addressing BART as meeting Idaho's 
obligations under section 110(a)(2)(D)(i)(I) of the Act for visibility. 
EPA is not taking action today on those provisions of the Regional Haze 
SIP submittal related to reasonable progress goals and the long term 
strategy.

A. Definition of Regional Haze

    Regional haze is impairment of visual range or colorization caused 
by emission of air pollution produced by numerous sources and 
activities, located across a broad regional area. The sources include 
but are not limited to, major and minor stationary sources, mobile 
sources, and area sources including non-anthropogenic sources. 
Visibility impairment is primarily caused by fine particulate matter 
(PM2.5) or secondary aerosol formed in the atmosphere from precursor 
gasses (e.g., sulfur dioxide, nitrogen oxides, and in some cases, 
ammonia and volatile organic compounds). Atmospheric fine particulate 
reduces clarity, color, and visual range of visual scenes. Visibility 
reducing fine particulate is primarily composed of sulfate, nitrate, 
organic carbon compounds, elemental carbon, and soil dust, and impairs 
visibility by scattering and absorbing light. Fine particulate can also 
cause serious health effects and mortality in humans, and contributes 
to environmental effects such as acid deposition and eutrophication.\2\
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    \2\ See 64 FR at 35715.
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    Data from the existing visibility monitoring network, 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 parks and 
wilderness areas. Average visual range in many Class I areas in the 
Western United States is 100-150 kilometers, or about one-half to two-
thirds the visual range that would exist without manmade air 
pollution.\3\ Visibility impairment also varies day-to-day and by 
season depending on variation in meteorology and emission rates.
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    \3\ Id.
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B. Regional Haze Rules and Regulations

    In section 169A of the 1977 CAA Amendments, 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 Class I areas which impairment results from 
manmade air pollution.'' CAA section 169A(a)(1). On December 2, 1980, 
EPA promulgated regulations to address visibility impairment in Class I 
areas that is ``reasonably attributable'' to a single source or small 
group of sources, i.e., ``reasonably attributable visibility 
impairment''. 45 FR 80084. These regulations represented the first 
phase in addressing visibility impairment. EPA 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 were improved.
    Congress added section 169B to the CAA in 1990 to address regional 
haze issues. EPA promulgated a rule to address regional haze on July 1, 
1999 (64 FR 35713) (the RHR). The RHR revised the existing visibility 
regulations to integrate into the regulation provisions addressing 
regional haze impairment and established 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 EPA's 
visibility protection regulations at 40 CFR 51.300-309. Some of the 
main elements of the regional haze requirements are summarized in 
section III of this rulemaking. The requirement to submit a regional 
haze SIP applies to all 50 states, the District of Columbia and the 
Virgin Islands.\4\ 40 CFR 51.308(b) requires states to submit the first 
implementation plan addressing regional haze visibility impairment no 
later than December 17, 2007.
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    \4\ Albuquerque/Bernalillo County in New Mexico must also submit 
a regional haze SIP to completely satisfy the requirements of 
section 110(a)(2)(D) of the CAA for the entire State of New Mexico 
under the New Mexico Air Quality Control Act (section 74-2-4).
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C. 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. As noted above, 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 impairment can 
originate from across state lines, EPA has encouraged the States and 
Tribes to address visibility impairment from a regional perspective. 
Five regional planning organizations (RPOs) were created nationally to 
address regional haze and related issues. One of the main objectives of 
the RPOs is to develop and analyze data and conduct pollutant transport 
modeling to assist the States or Tribes in developing their regional 
haze plans.
    The Western Regional Air Partnership (WRAP), one of the five RPOs 
nationally, is a voluntary partnership of State, Tribal, Federal, and 
local air agencies dealing with air quality in the West. WRAP member 
States include: Alaska, Arizona, California, Colorado, Idaho, Montana, 
New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and 
Wyoming. WRAP Tribal members include Campo Band of Kumeyaay Indians, 
Confederated Salish and Kootenai Tribes, Cortina Indian Rancheria, Hopi 
Tribe, Hualapai Nation

[[Page 1581]]

of the Grand Canyon, Native Village of Shungnak, Nez Perce Tribe, 
Northern Cheyenne Tribe, Pueblo of Acoma, Pueblo of San Felipe, and 
Shoshone-Bannock Tribes of Fort Hall.

D. Interstate Transport for Visibility

    On July 18, 1997, EPA promulgated new NAAQS for 8-hour ozone and 
for PM2.5. 62 FR 38652. Section 110(a)(1) of the CAA requires states to 
submit a plan to address certain requirements for a new or revised 
NAAQS within three years after promulgation of such standards, or 
within such shorter time as EPA may prescribe. Section 110(a)(2) of the 
CAA lists the elements that such new plan submissions must address, as 
applicable, including section 110(a)(2)(D)(i), which pertains to the 
interstate transport of certain emissions.
    On April 25, 2005, EPA published a ``Finding of Failure to Submit 
SIPs for Interstate Transport for the 8-hour Ozone and PM2.5 NAAQS.'' 
70 FR 21147. This included a finding that Idaho and other states had 
failed to submit SIPs to address interstate transport of emissions 
affecting visibility and started a 2-year clock for the promulgation of 
a Federal Implementation Plan (FIP) by EPA, unless the state made a 
submission to meet the requirements of section 110(a)(2)(D)(i) and EPA 
approves such submission. Id.
    On August 15, 2006, EPA issued guidance on this topic entitled 
``Guidance for State Implementation Plan (SIP) Submissions to Meet 
Current Outstanding Obligations Under section 110(a)(2)(D)(i) for the 
8-Hour Ozone and PM2.5 National Ambient Air Quality Standards'' (2006 
Guidance). We developed the 2006 Guidance to make recommendations to 
states for making submissions to meet the requirements of section 
110(a)(2)(D)(i) for the 1997 8-hour ozone standards and the 1997 PM2.5 
standards.
    As identified in the 2006 Guidance, the ``good neighbor'' 
provisions in section 110(a)(2)(D)(i) of the CAA require each state to 
have a SIP that prohibits emissions that adversely affect other states 
in ways contemplated in the statute. Section 110(a)(2)(D)(i) contains 
four distinct requirements related to the impacts of interstate 
transport. The SIP must prevent sources in the state from emitting 
pollutants in amounts which will: (1) Contribute significantly to 
nonattainment of the NAAQS in other states; (2) interfere with 
maintenance of the NAAQS in other states; (3) interfere with provisions 
to prevent significant deterioration of air quality in other states; or 
(4) interfere with efforts to protect visibility in other states.
    With respect to establishing that emissions from sources in the 
state would not interfere with measures in other states to protect 
visibility, the 2006 Guidance recommended that states make a submission 
indicating that it was premature, at that time, to determine whether 
there would be any interference with measures in the applicable SIP for 
another state designed to ``protect visibility'' until the submission 
and approval of regional haze SIPs. Regional haze SIPs were required to 
be submitted by December 17, 2007. See 74 FR 2392. At this later point 
in time, however, EPA believes it is now necessary to evaluate such 
110(a)(2)(D)(i) submissions from a state to ensure that the existing 
SIP, or the SIP as modified by the submission, contains adequate 
provisions to prevent interference with the visibility programs of 
other states, such as for consistency with the assumptions for controls 
relied upon by other states in establishing reasonable progress goals 
to address regional haze.
    The regional haze program, as reflected in the RHR, recognizes the 
importance of addressing the long-range transport of pollutants for 
visibility and encourages states to work together to develop plans to 
address haze. The regulations explicitly require each state to address 
its ``share'' of the emission reductions needed to meet the reasonable 
progress goals for neighboring Class I areas. States working together 
through a regional planning process, are required to address an agreed 
upon share of their contribution to visibility impairment in the Class 
I areas of their neighbors. 40 CFR 51.308(d)(3)(ii). Given these 
requirements, we anticipate that regional haze SIPs will contain 
measures that will achieve these emissions reductions, and that these 
measures will meet the requirements of section 110(a)(2)(D)(i).
    As a result of the regional planning efforts in the West, all 
states in the WRAP region contributed information to a Technical 
Support System (TSS) which provides an analysis of the causes of haze, 
and the levels of contribution from all sources within each state to 
the visibility degradation of each Class I area. The WRAP States 
consulted in the development of reasonable progress goals, using the 
products of this technical consultation process to co-develop their 
reasonable progress goals for the Western Class I areas. The modeling 
done by the WRAP relied on assumptions regarding emissions over the 
relevant planning period and embedded in these assumptions were 
anticipated emissions reductions in each of the States in the WRAP, 
including reductions from BART and other measures to be adopted as part 
of the State's long term strategy for addressing regional haze. The 
reasonable progress goals in the draft and final regional haze SIPs 
that have now been prepared by States in the West accordingly are 
based, in part, on the emissions reductions from nearby States that 
were agreed on through the WRAP process.
    Idaho submitted a Regional Haze SIP on October 25, 2010, to address 
the requirements of the RHR and the good neighbor provisions of section 
110(a)(2)(D)(i) regarding visibility for the 1997 8-hour ozone NAAQS 
and the 1997 PM2.5 NAAQS. EPA has reviewed the submittal and concluded 
at this time to propose to take action on only certain elements of 
Idaho's Regional Haze SIP. EPA is required at this time, to propose to 
take action either to approve Idaho's SIP submittal, or otherwise to 
take action to meet the requirements of section 110(a)(2)(D)(i)(II) 
regarding visibility.\5\ EPA is proposing to find that certain elements 
of Idaho's Regional Haze SIP submittal meet these requirements. In 
particular, as explained in section IV of this action, EPA is proposing 
to find that the BART measures in Idaho's Regional Haze SIP submittal, 
which EPA is proposing to approve in this action, will also mean that 
the Idaho SIP meets the requirements of section 110(a)(2)(D)(i)(II) 
regarding visibility for the 1997 8-hour ozone and 1997 PM2.5 NAAQS.
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    \5\ Wildearth Guardians v. Jackson, Case No. 4:09-CV-02453-CW 
(N.D. Calif.)
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II. Requirements for Regional Haze SIPs

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 EPA's 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 BART controls for 
the purpose of eliminating or reducing visibility impairment. The 
specific regional haze SIP requirements are discussed in further detail 
below.

[[Page 1582]]

B. Determination of Baseline, Natural, and Current Visibility 
Conditions

    The RHR establishes the deciview (dv) as the principal metric for 
measuring visibility. This visibility metric expresses uniform changes 
in haziness in terms of common increments across the entire range of 
visibility conditions, from pristine to extremely hazy conditions. 
Visibility is determined by measuring the visual range (or deciview), 
which is the greatest distance, in kilometers or miles, at which a dark 
object can be viewed 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 at one 
deciview.\6\
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    \6\ The preamble to the RHR 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 (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 manmade air pollution by reducing anthropogenic emissions that cause 
regional haze. The national goal is a return to natural conditions, 
i.e., manmade 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 RHR requires states to determine 
the degree of impairment (in deciviews) for the average of the 20% 
least impaired (``best'') and 20% 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. EPA has 
provided guidance to states regarding how to calculate baseline, 
natural and current visibility conditions in documents titled, EPA's 
Guidance for Estimating Natural Visibility Conditions Under the 
Regional Haze Rule, September 2003, (EPA-454/B-03-005 located at https://www.epa.gov/ttncaaa1/t1/memoranda/rh_envcurhr_gd.pdf), (hereinafter 
referred to as ``EPA's 2003Natural Visibility Guidance''), and Guidance 
for Tracking Progress Under the Regional Haze Rule (EPA-454/B-03-004 
September 2003 located at https://www.epa.gov/ttncaaa1/t1/memoranda/rh_tpurhr_gd.pdf), (hereinafter referred to as ``EPA's 2003 Tracking 
Progress Guidance'').
    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% 
least impaired days and 20% 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 time period is considered the time from which improvement in 
visibility is measured.

C. Consultation With States and Federal Land Managers

    The RHR 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 visibility impairment 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.

D. Best Available Retrofit Technology

    Section 169A of the CAA directs states to evaluate the use of 
retrofit controls at certain larger, often uncontrolled, older 
stationary sources in order to address visibility impacts from these 
sources. Specifically, section 169A(b)(2)(A) of the CAA 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 \7\ built between 1962 and 1977 procure, install, and operate 
the ``Best Available Retrofit Technology'' as determined by the state. 
States are directed to conduct BART determinations for such 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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    \7\ The set of ``major stationary sources'' potentially subject 
to BART is listed in CAA section 169A(g)(7).
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    On July 6, 2005, EPA published the Guidelines for BART 
Determinations Under the Regional Haze Rule at appendix Y to 40 CFR 
Part 51 (hereinafter referred to as the ``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. In making a BART applicability determination 
for a fossil fuel-fired electric generating plant with a total 
generating capacity in excess of 750 megawatts, 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.
    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. EPA has indicated that states should use their best judgment in 
determining

[[Page 1583]]

whether VOC or NH3 compounds impair visibility in Class I 
areas.
    The RPOs provided air quality modeling to the states to help them 
in determining whether potential BART sources can be reasonably 
expected to cause or contribute to visibility impairment in a Class I 
area. 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. Generally, an exemption threshold set by 
the state should not be higher than 0.5 deciview.
    In their SIPs, states must identify potential BART sources, 
described as ``BART-eligible sources'' in the RHR, 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. States are free to determine 
the weight and significance to be assigned to each factor.
    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 EPA approves the regional haze 
SIP. CAA section 169(g)(4). 40 CFR 51.308(e)(1)(iv). In addition to 
what is required by the RHR, 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. States have the flexibility to choose the type of control 
measures they will use to meet the requirements of BART.

III. EPA's Analysis of Idaho Regional Haze SIP

A. Affected Class I Areas

    There are five mandatory Class I areas, or portions of such areas, 
within Idaho. Craters of the Moon National Monument, Sawtooth 
Wilderness Area, and Selway-Bitterroot Wilderness Area lie completely 
within Idaho State borders. Hells Canyon Wilderness Area is a shared 
Class I area with Oregon, and Yellowstone National Park is a shared 
Class I area with Wyoming. See 40 CFR 81.410. Oregon and Wyoming 
respectively will address reasonable progress goals, monitoring, and 
other core requirements for these Class I areas. Idaho consulted with 
Oregon and Wyoming to determine Idaho's contribution to regional haze 
in those Class I areas and to determine appropriate measures for 
Idaho's long-term strategy. See chapter 13, section 13.2 of the Idaho 
Regional Haze SIP submittal. See also the WRAP Technical Support 
Document \8\ (WRAP TSD) supporting this action.
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    \8\ EPA evaluated the technical work products of the WRAP used 
by Idaho in support of this Regional Haze SIP submittal. The results 
of that evaluation are included in the document ``WRAP Technical 
Support Document'' or WRAP TSD.
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    The Idaho SIP submittal addresses the three Class I areas that are 
completely within the State border and, as appropriate, Class I areas 
with shared jurisdiction with Oregon and Wyoming and Class I areas in 
neighboring states.

B. Baseline and Natural Conditions

    Idaho, using data from the IMPROVE monitoring network and analyzed 
by WRAP, established baseline and natural visibility conditions as well 
as the uniform rate of progress (URP) to achieve natural visibility 
conditions in 2064 for all Idaho Class I areas within its borders. 
While Idaho is responsible for establishing baseline and natural 
conditions for three Class I areas, the SIP also included these values 
for Hells Canyon Wilderness Area and Yellowstone National Park, as 
determined by WRAP and established by Oregon and Wyoming.
    Baseline visibility was calculated from monitoring data collected 
by IMPROVE monitors for the most-impaired (20% worst) days and the 
least-impaired (20% best) days. Idaho used the WRAP derived natural 
visibility conditions. In general, WRAP based their estimates on EPA 
guidance, Guidance for Estimating Natural Visibility Conditions Under 
the Regional Haze Program (EPA-45/B-03-0005 September 2003) but 
incorporated refinements which EPA believes provides results more 
appropriate for western states than the general EPA default approach. 
See section 2.E of the WRAP TSD.
    Craters of the Moon National Monument: An IMPROVE monitor is 
located in Craters of the Moon National Monument. Based on baseline 
2000 to 2004 data, the average 20% worst days visibility is 14 dv and 
the average 20% best days visibility is 4.3 dv. Natural visibility for 
the average 20% worst days is 7.53 dv.
    Hells Canyon Wilderness Area: Hells Canyon Wilderness Area has an 
IMPROVE monitor located within the Wilderness Area at Oxbow Dam. Based 
on baseline 2000 to 2004 data, Oregon determined the average 20% worst 
days visibility is 18.55 dv and the average 20% best days visibility is 
5.52 dv. Natural visibility for the average 20% worst days is 8.32 dv.
    Sawtooth Wilderness Area: Sawtooth Wilderness Area has an IMPROVE 
monitor located within the Wilderness Area. Based on baseline 2000 to 
2004 data, the average 20% worst days visibility is 13.78 dv and the 
average 20% best days visibility is 3.99 dv. Natural visibility for the 
average 20% worst days is 6.42 dv.
    Selway-Bitterroot Wilderness Area: Selway-Bitterroot Wilderness 
Area visibility is represented by an IMPROVE monitor located 20 km east 
of the Wilderness Area in Sula, Montana. This site also represents 
visibility in the Anaconda-Pintler Wilderness Area. Based on baseline 
2000 to 2004 data, the average 20% worst days visibility is 13.41 dv 
and the average 20% best days visibility is 2.58 dv for both areas. 
Natural visibility for the Selway-Bitteroot and the Anaconda-Pintler 
Wilderness Areas average 20% worst days is 7.43 dv.
    Yellowstone National Park: Yellowstone National Park has an IMPROVE 
monitor located within the park. Based on baseline 2000 to 2004 data 
Wyoming determined the average 20% worst days visibility is 11.76 dv 
and the average 20% best days visibility is 2.58 dv. Natural visibility 
for the average 20% worst days is 6.24 dv.
    Based on our evaluation of the State's baseline and natural 
conditions analysis, EPA is proposing to find that Idaho has 
appropriately determined baseline visibility for the average 20% worst 
and 20% best days and natural visibility conditions for the average 20%

[[Page 1584]]

worst days in each Class I area within the state. See the WRAP TSD 
supporting this action (section 2.D and 2.E).

C. Idaho Emission Inventories

    There are three main categories of air pollution emission sources: 
Point sources, area sources, and mobile sources. Point sources are 
larger stationary sources that emit pollutants through a stack or duct. 
Area sources are large numbers of small sources that are widely 
distributed across an area, such as residential heating units or re-
entrained dust from unpaved roads or windblown dust form agricultural 
fields. Mobile sources are sources such as motor vehicles, locomotives 
and aircraft.
    The RHR requires a statewide emission inventory of pollutants that 
are reasonably anticipated to cause or contribute to visibility 
impairment in any mandatory Class I area. 40 CFR 51.308(d)(4)(v). The 
WRAP, with data supplied by the states, compiled emission inventories 
for all major source categories in Idaho for the 2002 baseline year and 
estimated emission inventories for 2018. Emission estimates for 2018 
were generated from anticipated population growth, growth in industrial 
activity, and emission reductions from implementation of control 
measures, e.g., implementation of BART limitations, and motor vehicle 
tailpipe emissions. Appendix D of the Idaho Regional Haze SIP discusses 
how emission estimates were determined and contains the emission 
inventory. Detailed estimates of the emissions, used in the modeling 
conducted by the WRAP and Idaho, can be found at the WRAP Web site: 
https://vista.cira.colostate.edu/TSS/Results/Emissions.aspx.
    There are a number of emission inventory source categories 
identified in the Idaho SIP: point, area, on-road mobile, off-road 
mobile, anthropogenic fire (prescribed forest fire, agricultural field 
burning, and residential wood combustion), natural fire, road dust, 
fugitive dust and windblown dust. The 2002 baseline and 2018 projected 
emissions, as well as the net changes of emissions between these two 
years, are presented in Tables 8-1 through 8-8 in the SIP submittal for 
SO2, NOX, Volatile Organic Carbon (VOC), Organic 
Carbon (OC), Elemental Carbon (EC), fine particulate (PM2.5), coarse 
particulate (PM coarse) and ammonia. The methods that WRAP used to 
develop these emission inventories are described in more detail in the 
WRAP TSD. As explained in the WRAP TSD, emissions were calculated using 
best available data and approved EPA methods. See WRAP TSD section 12.
    SO2 emissions in Idaho come mostly from coal combustion 
at industrial boilers and from other industrial activities. 
SO2 emissions estimates for point sources came either from 
source test data (where available) or calculations based on fuel type 
and quantity burned. These industrial point sources contribute 45% of 
total statewide SO2 emissions. The second largest 
contributor to SO2 emissions in Idaho is fire: 31% from 
natural fire and 2% from anthropogenic fire.
    Idaho projects a 45% statewide reduction in point source 
SO2 emissions by 2018 due to implementation of BART emission 
limitations. Idaho also projects total 2018 statewide SO2 
emissions to be reduced by 33.9% below 2002 levels as a result of BART 
and additional reductions from mobile sources and anthropogenic fire 
emissions. According to the State's analysis, overall point source 
emissions, the largest source category in 2002, are projected to be 
reduced by 46.7%. Area source emissions (8% of statewide SO2 
emissions) are projected to increase 7.9% between 2002 and 2018 due to 
population growth. Idaho projects SO2 emissions associated 
with natural fire, the second largest source category in 2002, to 
remain unchanged and would become the largest source category in 2018.
    NOX emissions in Idaho come mostly from mobile sources, 
both from on-road and off-road mobile sources, which contribute 46% of 
total statewide NOX emissions. The second largest source 
category of NOX emissions is area source emissions from 
combustion to heat buildings. Area source emissions account for 19% of 
statewide NOX emissions. Idaho projects that 2018 total 
statewide emissions of NOX will be 20.6% lower than 2002 
levels. Idaho also projects on-road and off-road mobile source 
emissions to be reduced by 72.4% and 38.3% respectively by 2018, due to 
new Federal motor vehicle emission standards and fleet turnover. Idaho 
projects area source NOX emissions to increase by 38.8% to 
become the largest source category in 2018 due to population growth and 
new industrial sources. Idaho projects natural fire emissions to remain 
unchanged and become the second largest NOX source category 
in 2018.
    Volatile organic compounds (VOC) in Idaho come mostly from area 
sources such as industrial solvent use, paints, pharmaceuticals, and 
refrigerants, which contribute 46% of total VOC emissions. The second 
largest source category in VOC emissions is non-anthropogenic fire 
which contributes 25% of total VOC emissions, while the second largest 
source category of anthropogenic VOC is mobile sources. Idaho projects 
2018 statewide VOC emissions to increase by 19.2% over 2002 levels even 
though on-road mobile, off-road mobile and anthropogenic VOC emissions 
are projected to decrease 61.7%, 32.2% and 52.3% respectively. This 
increase in VOC emissions is due to a projected 64.2% increase in area 
source VOC emissions primarily due to population growth and increased 
business activity.
    Organic carbon in Idaho comes from natural fire, anthropogenic fire 
and mobile sources. Natural fire is the largest source category, which 
contributes 82% of organic carbon emissions. The second largest source 
category is anthropogenic fire which contributes 15% of the total 
organic carbon emissions. Idaho projects 2018 statewide organic carbon 
emissions to decrease 7.6% from 2002 emission levels due to reductions 
in on-road mobile, off-road mobile, and anthropogenic fire of 10.8%, 
43.1% and 51.6% respectively.
    Elemental carbon is associated with incomplete combustion. The 
largest source category is natural fire, which contributes 72% of total 
elemental carbon emissions. The second largest source category is off-
road mobile sources (diesel) which contributes 14% of total elemental 
carbon emissions. Idaho projects 2018 statewide elemental carbon 
emissions to decrease by 50.7% from 2002 emission levels. These 
projected reductions are the result of anticipated emission reductions 
in on-road mobile and off-road mobile emissions of 73.8% and 64.3% 
respectively.
    Fine particulate, particles with an aerodynamic diameter of less 
than 2.5 micrometers, is emitted from a variety of area sources. Point 
sources account for only 2% of statewide fine particulate. Wind blown 
dust is the largest source category contributing 26% of total fine 
particulate. Wood stoves and small manufacturing and industrial sources 
contribute 24% of total fine particulate. Natural fire, anthropogenic 
fire, road dust and other fugitive dust sources also emit approximately 
equal amounts of fine particulate. Idaho projects that 2018 fine 
particulate emissions will increase by 12.1% over 2002 emission levels 
due to population and industrial growth. Emissions increases are 
projected from point, area, road dust, fugitive dust at 26.8%, 33.6%, 
32.0%, and 30.1% respectively. Fine particulate emissions associated 
with anthropogenic fire are expected to decrease by 53.6%.

[[Page 1585]]

    Coarse particulate is particulate with an aerodynamic diameter 
between 2.5 and 10 micrometers. It is composed of larger particles in 
wind blown dust, natural fire and other particulate from industrial 
grinding sources. The largest source category is wind blown dust which 
contributes 40% of total coarse particulate emissions. The second 
largest source is natural fire which contributes 22% of coarse 
particulate emissions. Idaho projects that 2018 emissions of coarse 
particulate to increase by 11.9% over 2002 emission levels. Idaho 
projects course particulate emissions from most categories to increase, 
with the exception of anthropogenic fire which will decrease by 51.7%.
    Ammonia does not directly impair visibility but can be a precursor 
to the formation of particulate in the atmosphere through chemical 
reaction with SO2 and NOX to form a ``secondary 
aerosol.'' Area sources are the primary source category contributing to 
ammonia emissions and account for 85% of total ammonia emissions. The 
second largest source category is natural fire which contributes 10% of 
ammonia emissions. Idaho projects ammonia emissions in 2018 to increase 
by 1.3% over 2002 emission levels with increasing emissions in all 
categories with the exception of anthropogenic fire which Idaho 
projects to decrease by 53.4%.

D. Sources of Visibility Impairment in Idaho Class I Areas

    Each pollutant species has its own visibility impairing property; 1 
[mu]g/m\3\ of sulfate, for example, is more effective in scattering 
light than 1 [mu]g/m\3\ of organic carbon and therefore impairs 
visibility more than organic carbon. Following the approach recommended 
by the WRAP and as explain more fully below, Idaho used a two step 
process to identify the contribution of each source or source category 
to existing visibility impairment. First, ambient pollutant 
concentration by species (sulfate, nitrate, organic carbon, fine 
particulate, etc.) was determined from the IMPROVE sampler in each 
Class I area. These concentrations were then converted into deciview 
values to distribute existing impairment among the measured pollutant 
species. This calculation used the ``improved IMPROVE equation'' (See 
section 2.C of the WRAP TSD) to calculate extinction from each 
pollutant specie concentration. Extinction, in inverse megameters, was 
then converted to deciview using the equation defining deciview. 
Second, the Comprehensive Air Quality Model with Extensions (CAMx) and 
PM Source Apportionment Technology (PSAT) models were used to determine 
which sources and source categories contributed to the ambient 
concentration of each pollutant species. Thus, impairment was 
distributed by source and source category.
    After considering the available models, the WRAP and Western States 
selected two source apportionment analysis tools. The first source 
apportionment tool was the Comprehensive Air Quality Model with 
Extensions (CAMx) in conjunction with PM Source Apportionment 
Technology (PSAT). This model uses emission source characterization, 
meteorology and atmospheric chemistry for aerosol formation to predict 
pollutant concentrations in the Class I area. The predicted results are 
compared to measured concentrations to assess accuracy of model output. 
CAMx PSAT modeling was used to determine source contribution to ambient 
sulfate and nitrate concentrations. The WRAP used state-of-the-science 
source apportionment tools within a widely used photochemical model. 
EPA has reviewed the PSAT analysis and considers the modeling, 
methodology, and analysis acceptable. See section 6.A of the WRAP TSD.
    The second tool was the Weighted Emissions Potential (WEP) model, 
used primarily as a screening tool to decide which geographic source 
regions have the potential to contribute to haze at specific Class I 
areas. WEP does not account for atmospheric chemistry (secondary 
aerosol formation) or removal processes, and thus is used for 
estimating inert particulate concentrations. The model uses back 
trajectory wind flow calculations and resident time of an air parcel to 
determine source and source category and location for ambient organic 
carbon, elemental carbon, PM2.5, and coarse PM 
concentrations. These modeling tools were the state-of-the-science and 
EPA has determined that these tools were appropriately used by WRAP for 
regional haze planning. Description of these tools and our evaluation 
of them are described in more detail in section 6 of the WRAP TSD.
    Figure 7-1 in the Idaho Regional Haze SIP submittal presents the 
light extinction for the base year at each Class I area by visibility 
impairing pollutant species for the average of the 20% worst days. The 
visibility impairing pollutant species identified are: Fine particulate 
(i.e. sea salt, fine soil, elemental carbon, organic carbon, ammonium 
sulfate and ammonium nitrate) and coarse material. In addition the SIP 
submission identifies in Figures 7.2 through Figure 7.52, light 
extinction by pollutant species for the average of the 20% worst and 
average of the 20% best days for each of the Class I areas.
    Figure 7-1 of the SIP indicates that on the 20% worst days organic 
carbon is the primary pollutant impairing visibility in the Sawtooth 
and Selway-Bitterroot Wilderness Areas. In Craters of the Moon National 
Monument the primary pollutant impairing visibility on the 20% worst 
days is ammonium nitrate.
    Idaho also analyzed the monthly variation of light extinction and 
pollutant specie concentrations for the 20% worst days. See Idaho SIP 
Figures 7-6 and 7-7, Figures 7-24 through 7-27, Figures 7-35 through 7-
38. Each Class I area shows a distinct monthly and seasonal variation 
in impairment. For example, the 20% worst days in Craters of the Moon 
National Monument occur during the winter months of December through 
February. The 20% worst days in the Sawtooth and Selway-Bitterroot 
Wilderness Areas occur from April through November. This variation in 
impairment is due to monthly and seasonal variation in meteorology and 
emission rates.
    To determine potential impacts of emission sources in Idaho on 
Class I areas in other states, Idaho considered the WRAP analysis of 
interstate impacts. Ambient air sulfate and nitrate concentrations for 
the 20% worst and best days for baseline (2002-2004) and 2018 at each 
western Class I area is distributed among all states in the WRAP using 
PSAT modeling. The SIP submittal provides an analysis of the Class I 
areas in nearby states. See chapter 9.3 of the Idaho Regional Haze SIP 
submission. These Class I areas are:
Shared Class I Areas With Oregon and Wyoming
     Hells Canyon Wilderness Area
     Yellowstone National Park
Class I Areas Outside Idaho
     Glacier National Park in Montana: Idaho is ranked 3rd 
behind Montana and Washington in contribution of visibility impairing 
pollutants on the 20% worst days
     Cabinet Mountain Wilderness Area in Montana: Idaho is 
ranked 3rd behind Oregon and Washington in contribution to visibility 
impairing pollutants on the 20% worst days
     Bob Marshall Wilderness Area in Montana: Idaho is ranked 
3rd behind Montana and Washington in contribution to visibility 
impairing pollutants on the 20% worst days
     Gates of the Mountain Wilderness in Montana: Idaho is 
``ranked 3rd'' behind Montana and Washington in

[[Page 1586]]

contribution to visibility impairing pollutants on the 20% worst days
     North Absaroka Wilderness in Wyoming: Idaho is ranked 2nd 
behind Wyoming in contribution to visibility impairing pollutants on 
the 20% worst days
     Bridger Wilderness in Wyoming: Idaho is ranked 2nd behind 
Wyoming in contribution to visibility impairing pollutants on the 20% 
worst days
     Eagle Cap Wilderness Area Oregon: Idaho is ranked 3rd 
behind Oregon and Washington in contribution to visibility impairing 
pollutant on the 20% worst days
     Jarbidge Wilderness Area in Nevada: Idaho is ranked 1st in 
contribution of sulfate and nitrate to the Jarbidge Wilderness area.
    EPA is proposing to find that Idaho has appropriately identified 
the primary pollutants impacting its Class I areas. EPA is also 
proposing to find that the SIP contains an appropriate analysis of the 
impacts of emissions from Idaho on nearby Class I areas.

E. Best Available Retrofit Technology

    The first phase of a BART evaluation is to identify all the BART-
eligible sources within the State's boundaries. Table 10-1 in the SIP 
submission presents the list of all BART-eligible sources located in 
Idaho. These sources are: The Amalgamated Sugar Company (TASCO) in Twin 
Falls, TASCO in Nampa, TASCO in Paul, NU West/Agrium in Soda Springs, 
the J.R. Simplot Don Plant in Pocatello, the Monsanto/P4 Production LLC 
facility at Soda Springs, and the Potlatch Pulp & Paper mill in 
Lewiston Idaho.
    The second phase of the BART determination process is to identify 
those BART-eligible sources that may reasonably be anticipated to cause 
or contribute to any impairment of visibility at any Class I area and 
are, therefore, subject to BART. As explained above, EPA has issued 
guidelines that provide states with guidance for addressing the BART 
requirements. 40 CFR Part 51 appendix Y; see also 70 FR 39,104 (July 6, 
2005). The BART Guidelines describe how states may consider exempting 
some BART-eligible sources from further BART review based on dispersion 
modeling showing that the sources contribute below a certain threshold 
amount. Idaho conducted dispersion modeling for the BART-eligible 
sources to determine the visibility impacts of these sources on Class I 
areas with the exception of the Monsanto/P4 Production LLC facility 
which was categorized as subject to BART without analysis.\9\
---------------------------------------------------------------------------

    \9\ Monsanto agreed to forego exemption modeling and to move 
directly to a BART determination.
---------------------------------------------------------------------------

    The BART Guidelines require States 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. Generally, 
States may not establish a contribution threshold that exceeds 0.5 dv 
impact. 70 FR at 39,161. Idaho established a contribution threshold of 
0.5 dv through negotiated rulemaking with industry, FLMs, and the 
public. In its SIP submittal, Idaho notes that the 0.5 dv threshold is 
also consistent with the threshold used by all other states in the 
WRAP. Any source with an impact of greater than 0.5 dv in any Class I 
area, including Class I areas in other states, would be subject to a 
BART analysis and BART emission limitations.
    The explanation given by Idaho for adopting a 0.5 dv threshold for 
determining whether a BART source may be reasonably anticipated to 
cause or contribute to any visibility impairment in a Class I area is 
not adequate to justify the selection of such a threshold. Although a 
number of stakeholders may have agreed that a 0.5 dv threshold is 
appropriate, and other states in the Region may have adopted such a 
threshold, such agreement does not provide sufficient basis concluding 
that such a threshold was appropriate in the case of Idaho. Based on 
EPA's review of the BART-eligible sources in Idaho, however, EPA is 
proposing to find that a 0.5 dv threshold is appropriate, given the 
specific facts in Idaho.
    In the BART Guidelines, EPA recommended that States ``consider the 
number of BART sources affecting the Class I areas at issue and the 
magnitude of the individual sources' impacts. In general, a larger 
number of BART sources causing impacts in a Class I area may warrant a 
lower contribution threshold.'' 70 FR 39104, 39161 July 6, 2005. In 
developing its regional haze SIP, Idaho modeled the impacts of six of 
the seven BART-eligible sources on Class I areas within a 300 km 
radius. (See Table 10-3 through Table 10-8 of the SIP submittal). As 
noted above, the State and Monsanto/P4 Production mutually agreed that 
Monsanto/P4 was subject to BART. Of these BART-eligible sources, only 
TASCO, Nampa exceeded the 0.5 dv threshold, based on consideration of 
the 22nd highest impact during 2003-2005.\10\ For the remaining five 
BART-eligible sources, the modeling showed maximum impacts below 0.4 
dv. These sources are generally widely distributed across the State, 
and only TASCO Twin Falls and TASCO Paul showed modeled impacts 
affecting the same Class I area. Given the relatively limited impact on 
visibility from these sources, Idaho could have reasonably concluded 
that a 0.5 dv threshold was appropriate for capturing those BART-
eligible sources with significant impacts on visibility in Class I 
areas. For these reasons, EPA is proposing to approve the 0.5 dv 
threshold adopted by Idaho in its Regional Haze SIP.
---------------------------------------------------------------------------

    \10\ The 22nd highest impact during 2003-2004 corresponds to the 
98th percentile of modeling results, an approach to applicability 
that EPA concluded was appropriate in the BART Guidelines. 70 FR at 
39,123.
---------------------------------------------------------------------------

    To determine those sources subject to BART, Idaho used the CALPUFF 
model. The dispersion modeling was conducted in accord with the BART 
Modeling Protocol7. This Protocol was jointly developed by the states 
of Idaho, Washington, Oregon and EPA and has undergone public review. 
The Protocol was used by all three states in determining which BART-
eligible sources are subject to BART. See appendix F of the SIP 
submission for details of the modeling protocol, its application and 
results. As noted above, Idaho determined through modeling that one, of 
the six modeled BART-eligible sources in Idaho, was subject to BART: 
The TASCO facility in Nampa. In addition, the Monsanto/P4 Production 
LLC facility in Soda Springs was determined to be subject to BART based 
on agreement by the source and the State.

F. TASCO BART Analysis

    TASCO Nampa is a sugar beet processing facility that operates a 350 
million BTU per hour, coal-fired boiler known as the Riley boiler. The 
Riley boiler emits sulfur dioxide, oxides of nitrogen and particulate 
matter. It is anticipated to operate into the foreseeable future, thus 
expected life of the source is not a factor in the BART determination.
    The first step in a BART analysis is the identification of all 
available retrofit control options. Available retrofit control options 
are those air pollution control technologies with a practical potential 
for application to the emission unit. 40 CFR part 51, appendix Y 
provides guidance on identifying available options that includes review 
of EPA's Clean Air Technology Center RACT/BACT/LAER clearinghouse, 
state and local Best Available Control Technology Guidelines, and a 
number of other documents. See 40 CFR part 51

[[Page 1587]]

appendix Y(IV)(D)(1). Generally EPA does not expect states to consider 
control technologies that have not already been demonstrated in 
practice to be technically feasible.
    Idaho identified the pollutants of concern for the BART 
determination at the Riley boiler to be sulfur dioxide, oxides of 
nitrogen and particulate matter. BART controls for each pollutant will 
be discussed below. Following an evaluation of available controls, 
described below, Idaho determined that the following emission limits 
represent BART for the Riley Boiler:

SO2--104 lb/hr
NOX--31 lb/hr
PM--12.4 lb/hr

The Idaho Regional Haze SIP submittal includes the federally 
enforceable Tier II operating permit for TASCO, Nampa, (permit No. T2-
2009.0109) that contains these emission limits. See letter and 
attachments dated September 7, 2010, from Mike Simon, Stationary Source 
Manager, Idaho Air Quality Division, to Kent Quinney, Plant Manager, 
The Amalgamated Sugar Company, LLC-Nampa Factory. The BART emission 
limits in the Tier II operating permit are slightly higher than those 
limits in the SIP submittal to allow for slight variation in test 
method results.
    The emission limits for NOX and SO2 can be 
achieved respectively through use of low NOX burners with 
overfire air and spray dry gas desulfurization. BART will result in a 
65% reduction in SO2 emissions and 80% reduction in 
NOX emissions. Idaho found that the bag house currently in 
place at the facility will result in compliance with the PM BART 
limitation.
1. TASCO SO2 BART Evaluation
    The TASCO Riley boiler currently burns low-sulfur coal limited to 
1% sulfur by weight. The alternative control options considered for 
SO2 include: low-sulfur coal limited to 0.6% sulfur by 
weight that would provide an additional 15% control efficiency, wet 
flue gas desulfurization (Wet FGD) with a 95% control efficiency, spray 
dryer flue gas desulfurization (Spray Dry FGD) with an 80% control 
efficiency, dry lime flue gas desulfurization (Dry Lime FGD) with a 55% 
control efficiency, dry Trona flue gas desulfurization (Dry Trona FGD) 
with a 65% control efficiency. Idaho found that all these technologies 
are technically feasible, but, as explained below, that wet FGD and 
spray dry FGD were the best options for further evaluation.
    With a removal efficiency of 95% or greater, wet FGD systems offer 
one of the highest SO2 removal efficiencies of the available 
control technologies. However, the installation of wet FGD at TASCO 
Nampa would require significant modification of the facility that would 
increase the cost of this option. As explained in the SIP submittal, 
wet FGD results in a saturated exhaust stream. The resulting 
condensation that would form in the stack would likely have a very low 
pH that would require installation of a stack liner to protect the 
integrity of the stack. Idaho concluded that installation of a stack 
liner would cost $2,000,000. Cost effectiveness of wet FGD was 
accordingly estimated at $3353/ton, with an incremental cost of $6940/
ton as compared to the next most efficient control technology, spray 
dry FGD.
    Spray dry FGD typically has an estimated control efficiency of 80-
90% depending on exit flue gas temperature as it approaches the 
adiabatic saturation temperature. Idaho used 80% control efficiency in 
this evaluation. Cost effectiveness of spray dry FGD is $2163/ton and 
the incremental cost over the next most efficient control technology, 
dry Trona FGD is $360/ton.
    Idaho also evaluated the energy and non-air related environmental 
impacts of the SO2 control options. Waste-water treatment 
from wet FGD is a major concern to Idaho and would need to be treated 
onsite. The SIP submittal explains that it would be difficult and 
expensive to expand the TASCO on-site treatment facility due to limited 
available land and the City of Nampa water treatment system might not 
be able to handle the increased water volume. See State of Idaho 
Department of Environmental Quality, Regional Haze Plan, 10/8/10, 
appendix F,
    Table 32 of appendix F of the SIP submittal provides the estimated 
visibility impact of the five control options. Wet FGD would reduce the 
number of days with greater than 0.5 dv impact over a three year period 
from 127 days to 43 days. Spray dry FGD would reduce the number of days 
with greater than