2011-249. 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.

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:

• http://www.regulations.gov. Follow the on-line instructions for submitting comments.
• E-mail: [e-mail].
• 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 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.

Docket: All documents in the docket are listed in the http://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 http://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 [phone], [e-mail], 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 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).

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]

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.

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.

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 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.

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.

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]

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 http://www.epa.gov/​ttncaaa1/​t1/​memoranda/​rh_​envcurhr_​gd.pdf),, (hereinafter referred to as “EPA's 2003 Natural Visibility Guidance”), and Guidance for Tracking Progress Under the Regional Haze Rule (EPA-454/B-03-004 September 2003 located at http://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.

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, NO_X, and PM. EPA has indicated that states should use their best judgment in determining 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.

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% 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: http://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, NO_X, 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.

NO_X emissions in Idaho come mostly from mobile sources, both from on-road and off-road mobile sources, which contribute 46% of total statewide NO_X emissions. The second largest source category of NO_X emissions is area source emissions from combustion to heat buildings. Area source emissions account for 19% of statewide NO_X emissions. Idaho projects that 2018 total statewide emissions of NO_X 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 NO_X 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 NO_X 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%.

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 NO_X 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 μg/m³ of sulfate, for example, is more effective in scattering light than 1 μg/m³ 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, PM_2.5, 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 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]

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.

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 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

NO_X—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 NO_X and SO₂ can be achieved respectively through use of low NO_X burners with overfire air and spray dry gas desulfurization. BART will result in a 65% reduction in SO₂ emissions and 80% reduction in NO_X 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 0.5 dv from 127 days to 51 days. Considering the incremental cost of wet FGD over spray dry FGD of $6940/ton, the waste water treatment limitations, and achieving a reduction of only 8 more days with impact greater than 0.5 dv over a three year period, Idaho concluded that wet FGD is not warranted.

Idaho has determined that spray dry FGD is the appropriate control technology for SO₂ and established 104 lb/hr as BART based on cost effectiveness and improvement in visibility. EPA agrees with Idaho's BART determination for SO₂.

2. NO_X BART Evaluation

Idaho identified potential control options for oxides of nitrogen (NO_X) for the Riley boiler as: low NO_X burners (LNB) with a 50% control efficiency, low NO_X burners with overfire air (LNB/OFA) with a 65% control efficiency, ultra low NO_X burners (ULNB) which was determined to be infeasible, selective catalytic reduction (SCR) with a 90% control efficiency, and selective non-catalytic (SNCR) determined to be infeasible. Idaho evaluated the technical feasibility of each control option. Idaho found that ULNB is not technologically feasible as the fire box at the Riley boiler is not large enough to accommodate the flame management system necessary for this type of control. Idaho also concluded that SNCR is also not technologically feasible as the boiler exhaust path does not have enough residence time for reliable control. Idaho accordingly identified three technically feasible control options: LNB, LNB/OFA, and SCR.

Idaho determined the cost effectiveness and incremental cost effectiveness for the three technically feasible control options. See Table 35 of appendix F of the SIP submittal. Idaho concluded that LNB/OFA provides a reasonable cost effectiveness of $1270/ton and incremental cost effectiveness of $2430/ton over low-NO_X burners. SCR would provide a 90% reduction in NO_X emissions at a cost effectiveness of $3768 and incremental cost of $10,245/ton over LNB/OFA. LNB/OFA would reduce the number of days with impacts greater than 0.5 dv over a three year period from 127 days to 56 days. SCR would reduce the number of days with impact greater than 0.5 dv over a three year period from 127 days to 40 days. Considering the incremental cost of SCR over LNB/OFA of $10,245/ton and achieving an incremental reduction of 16 days with impact greater than 0.5 dv over a three year period, Idaho concluded SCR is not warranted and that LNB/OFA represents BART. In addition, as described below in section F(d), TASCO argued that it could not afford to install an SCR. In view of this and Idaho's conclusion that the incremental cost of $10,245/ton for reducing the number of days with an impact greater than 0.5 dv by 16 over a three year period EPA is proposing to approve Idaho's determination of BART for NO_X TASCO.

3. PM BART Evaluation

The TASCO Nampa Riley boiler has a baghouse to control particulate matter. In its PM BART evaluation Idaho considered other alternative control technologies including: An enhanced baghouse with a control efficiency of 99%, wet electrostatic precipitator with a control efficiency of 99%, and dry electrostatic precipitator with a control efficiency of 99%. Idaho compared these technologies to the control efficiency of the current baghouse. The existing baghouse with a control efficiency of 99% emits 0.036 lbs/MMbtu (350 MMbtu/hour boiler with a limit of 0.036 lbs/MMbtu the emissions are 12.6 lbs/hour).

Idaho determined that the existing baghouse is the best BART control technology since it will not incur additional cost and has control efficiency comparable to the identified alternate control technologies. The existing baghouse has the added environmental benefits of not requiring additional water or electricity. The benefit of adding an additional baghouse is so small the benefits are outweighed by the costs. In conclusion, the best BART alternative for particulate is the existing baghouse.

Idaho determined that the current baghouse and an emission limitation of 12.4 lbs/hr is BART. EPA agrees with this determination.

4. TASCO Affordability

TASCO appealed to Idaho that the company could not afford the identified BART (Spray Dry FGD and LNB/OFA) and remain viable. At Idaho's request, EPA conducted an evaluation and analysis of TASCO's financial status and health. Based on this evaluation, EPA determined TASCO could afford implementation of the identified BART. EPA also concluded that TASCO could not reasonably afford the more costly control options of Wet FGD for SO₂ control and SCR for NO_X control. See Idaho Regional Haze Plan 10/8/10, appendix F, page F-317: Executive Summary excerpt from: An Affordability Analysis of The Amalgamated Sugar Company LLC's Affordability Claim with respect to the Best Available Retrofit Technology (BART) for the Riley Boiler at the Nampa, Idaho facility, February 12, 2010.

Based on EPA's review and evaluation we propose to approve the BART determination for TASCO.

G. Monsanto/P4 BART Analysis

Monsanto/P4 Production is a thermal process elemental phosphorus production facility. Idaho identified two BART units at the facility: The #5 Rotary Kiln and the #9 Furnace Exhaust and carbon monoxide Flare. Phosphate ore is processed in a high temperature electric arc furnace in a reducing atmosphere produced by the introduction of coke. Carbon monoxide gas from the arc furnace is used as fuel for the #5 Rotary Kiln. Excess carbon monoxide is flared to the atmosphere.

Idaho concluded, as discussed below, that the following emissions limit is BART for #5 Rotary Kiln:

SO₂—143 lb/hr

Idaho determined, as discussed below, that there are no technically feasible NO_X control options for the #9 Furnace Exhaust and CO Flare.

1. #5 Rotary Kiln, SO₂ Evaluation

Idaho conducted a thorough SO₂ BART evaluation for the #5 Rotary Kiln. The #5 Rotary Kiln heats phosphate ore to remove volatile impurities and harden ore nodules for further handling and introduction into the electric arc furnace. Carbon monoxide from the furnace off gases is the primary fuel with coal and natural gas as backup. Existing federally enforceable process and air pollution controls for the kiln are included in the facility's current Tier I (title V) operating permit No. T1-2009.0121, issued July 24, 2009. These requirements consist of:

• A limit on the sulfur content of the coal to no more than 1% by weight.
• A dust knockout chamber, spray tower, four parallel Hydro-Sonic^© scrubbers, and four parallel cyclonic separators. The tandem nozzle fixed-throat free-jet scrubbers are required for control of PM/PM10 and polonium-210 emissions (a radionuclide) found in the phosphate ore.

The initial SO₂ control device is a settling chamber where large particles are removed. The exhaust flow is then routed to a concrete tower where it passes through water sprays to remove soluble gases and particulate matter. The exhaust flow is then routed to four parallel Hydro-Sonic^© scrubbers for removal of submicron particles and entrained particle-laden water. The exhaust gases exit the scrubbers and pass through cyclonic separators and fans prior to exiting to the atmosphere through four stacks.

A lime concentrated dual alkali (LCDA) scrubber to control SO₂ emissions from the kiln was installed by Monsanto/P4 in 2005. The LCDA scrubbing process uses the existing Hydro-Sonic^© scrubbers to absorb SO₂ with a solution of sodium salts comprised of sodium sulfite and bisulfite, the active absorbent species. Some sodium sulfate will also be produced. The spent solution of sodium sulfite/bisulfite/sulfate is continuously withdrawn to a dual-reactor system, where it is treated with hydrated lime. The lime regenerates the scrubbing solution and precipitates calcium sulfite/sulfate solids. The solids are removed from the system through thickening and filtration, and the regenerated solution is returned to the scrubber as feed material.

Additional SO₂ controls would be add-on (or retrofit) control to the existing control technology. Idaho analyzed the technically feasible retrofit control technologies for SO₂ emissions from the #5 Rotary Kiln. These alternative controls included: Wet FGD with lime and amine scrubbing.

Idaho evaluated the control efficiencies of these feasible technologies and found that both are capable of 97% control. As determined by Idaho, the costs of these controls are $466/ton for wet FGD and $881/ton for amine scrubbing. See appendix F, Table 5.1.1 (page 338) of the Idaho Regional Haze SIP. The energy impacts were evaluated and both options require more energy, but not disproportionate amounts. Neither of the available options constitute significant adverse non-air environmental effects. The #5 Rotary Kiln is expected to remain in operation for the life of the P4 facility.

Idaho selected wet-FGD with lime as the most suitable control technology based on the fact that control efficiency is comparable to amine scrubbing, has a lower cost, and is a proven mature technology. Idaho determined that 143 lb/hr is BART for the #5 Rotary Kiln. EPA agrees with this determination.

2. #5 Rotary Kiln NO_X BART Evaluation

Idaho searched EPA's RACT/BACT/LAER clearinghouse (RBLC) for potential NO_X control options. The available options include: Combustion control, LNB, and SNCR.

Idaho determined that NO_X combustion controls are technically infeasible due to the temperatures required for sintering the phosphate ore and the change in temperature resulting from combustion control. Thermal NO_X is formed at approximately 1300 °C (2372 °F) and above. The minimum temperature at which sintering of the phosphate ore occurs is 1400 °C to 1459 °C (2552 °F to 2658 °F). Therefore, it is not feasible to lower the temperature in the kiln to minimize or prevent the formation of thermal NO_X and still sinter the ore.

Likewise, LNB was eliminated because the temperature required for a low NO_X burner is too low to sinter the phosphate ore and form the required nodules. Sintering of the ore takes place at 1400 °C to 1459 °C, and low NO_X burners must be controlled to operate at temperatures well below 1300 °C (2372 °F), the temperature at which thermal NO_X is formed.

SNCR was eliminated because the kiln off gas temperature at the exit of the kiln and prior to the existing Hydro-Sonic^© particulate control is too low for operation of SNCR.

EPA agrees that there are no technically feasible NO_X control options for the #5 Rotary Kiln. The current emission limitation is 3750.7 ton/yr.

3. #5 Rotary Kiln Particulate Matter BART Evaluation

As described above, the #5 Rotary Kiln emissions are currently controlled with Hydro-Sonic^© high energy venture scrubbers to control particulate matter. The Tier I operating permit includes a federally enforceable limit of 89.4 tons of PM/year.

Idaho conducted a brief evaluation of alternative PM control technologies but concluded, and EPA agrees, that there are no other technically feasible alternative control technologies with greater control efficiency than the existing Hydro-Sonic^© high energy venturi scrubbers. Thus, the existing PM emission limit of 98.4 t/yr constitutes BART for this source.

4. BART for the #9 Furnace CO Flare Evaluation

Ore nodules from the #5 Rotary Kiln are combined with coke and quartzite and heated in the #9 electric arc furnace. The resulting thermal process releases elemental phosphorus (as a gas), carbon monoxide and entrained particulate matter. The furnace off gas is cooled to liquefy and collect the elemental phosphorus and the remaining gases are ducted to the #5 Rotary Kiln as fuel. Excess furnace off gas is treated in a thermal oxidizer and flared to the atmosphere. The source of concern is the furnace flare, since most of the furnace gases fuel the #5 Rotary kiln and are controlled by technology applied to that source.

A review of the RBLC Clearinghouse revealed there are no available control technologies for particulate matter, SO₂, or NO_X for the #9 Furnace CO Flare. The RBLC Clearinghouse flare control options are exclusively for organic fuels and are not applicable for carbon monoxide fueled flares.

EPA agrees with Idaho's conclusion because there are no known retrofit control technologies that are technically feasible for the Monsanto/P4 #9 Furnace Exhaust and CO Flare. EPA is proposing to approve the BART determination for Monsanto/P4.

The Monsanto/P4 BART emission limits are contained in federally enforceable Tier I and Tier II operating permits. The BART requirements are contained in the Tier II operating permit, T2-2009.0109, issued November 17, 2009.

H. Improvement in Visibility From BART at TASCO, Nampa and Monsanto/P4

Table 10-14 of the SIP submittal presents the visibility improvement at several Class I areas in Idaho and surrounding states from implementation of BART at TASCO Nampa and Monsanto/P4. The metric used to measure improvement is the number of days (or reduction in number of days) with a deciview impact larger than 0.5 dv from each BART facility over a three year period.

The greatest improvement from BART controls at Monsanto/P4 is seen in the Teton Wilderness Area in Wyoming. Idaho estimated a reduction in the number of days with visibility impairment greater than 0.5 dv from Monsanto/P4 of 50 days over a three year period. Table 10-15 of the SIP submittal presents the visibility improvement at several other Class I areas in Idaho and surrounding states from implementation of BART at the Monsanto/P4 facility in Soda Springs.

The greatest improvement from BART controls at TASCO Nampa is seen in the Eagle Cap Wilderness Area in Oregon, with a reduction in days with greater than 0.5 dv of 127 days over a three year period.

Idaho included in the SIP submittal, federally enforceable Tier I and Tier II operating permits for TASCO Nampa and Monsanto/P4 which contain the necessary emission limitations representing BART and schedules for compliance.

IV. EPA's Analysis of Whether Regional Haze SIP Submittal Meets Interstate Transport Requirements

In its October 25, 2010, transmittal letter, Idaho also indicated that it intends the Regional Haze SIP submittal also to be a SIP submission for purposes of the visibility requirements of section 110(a)(2)(D)(i) with respect to the 1997 8-hour ozone and 1997 PM2.5 NAAQS. In the submission, Idaho stated that: “Idaho's Regional Haze SIP also satisfies the Clean Air Act Interstate Transport requirements of section 110(a)(2)(D)(ii). Chapters 2 and 13 and the associated appendix for chapter 2 describe Idaho's consultation with other states through the WRAP. Chapter 9 identifies Idaho's contribution and future visibility improvements at mandatory Class I Federal Areas impacted by Idaho's emissions.” In its SIP transmittal letter, the state referred to section 110(a)(2)(D)(ii), but from the context it is clear that the state intended this reference to be to section 110(a)(2)(D)(i), and more particularly to section 110(a)(2)(D)(i)(II).

Section 110(a)(2)(D)(i)(II) of the Act requires SIP revisions to “contain” adequate provisions * * * prohibiting * * * any source or other types of emission activity within the State from emitting any air pollutant in amounts which will * * * interfere with measures required to be included in the applicable implementation plan for any other State * * * to protect visibility.” EPA is proposing to find that the SIP submitted by Idaho to address regional haze contains adequate provisions to meet the “good neighbor” provisions of section 110(a)(2)(D)(i)(II) with respect to visibility.

As an initial matter, EPA notes that section 110(a)(2)(D)(i)(II) does not explicitly specify how EPA should ascertain whether a state's SIP contains adequate provisions to prevent emissions from sources in that state from interfering with measures required in another state to protect visibility. Thus, the statute is ambiguous on its face, and EPA must interpret that provision.

Our 2006 Guidance recommended that a state could meet the visibility prong of the transport requirements for section 110(a)(2)(D)(i)(II) by submission of the regional haze SIP, due in December 2007. EPA's reasoning was that the development of the regional haze SIPs was intended to occur in a collaborative environment among the states, and that through this process states would coordinate on emissions controls to protect visibility on an interstate basis. In fact, in developing their respective reasonable progress goals, WRAP states consulted with each other through the WRAP's work groups. As a result of this process, the common understanding was that each state would take action to achieve the emissions reductions relied upon by other states in their reasonable progress demonstrations under the RHR. This interpretation is consistent with the requirement in the regional haze rule that a state participating in a regional planning process must include “all measures needed to achieve its apportionment of emission reduction obligations agreed upon through that process.” 40 CFR 51.308(d)(3)(ii).

We believe that with approval of the portions of the Idaho RH SIP that we are proposing to take action on today, Idaho's SIP will also contain adequate provisions to prevent interstate transport that would interfere with the measures required in other states to protect visibility. Chapter 13 of the Idaho SIP submittal explains the consultation process followed by Idaho and its neighboring states to meet the requirements in the regional haze rule to address the interstate transport of visibility impairing pollutants and the outcome of that process. Section 13.2.3 indicates that Idaho and neighboring states agreed that “no major contributions were identified that supported developing new interstate strategies, mitigation measures, or emissions reductions obligations,” and that each state could achieve its share of emission reductions through the implementation of BART and other existing measures in state regional haze plans. The state agreed that future consultation would address any new strategies or measures needed. The measures addressing BART in the Idaho SIP submittal accordingly would appear to be adequate to prevent emissions from source in Idaho from interfering with the measures required to be in the regional haze SIPs of its neighbors.

This conclusion is consistent with the analysis conducted by the WRAP, an analysis that provides an appropriate means for further evaluating whether emissions from sources in a state are interfering with the visibility programs of other states, as contemplated in section 110(a)(2)(D)(i)(II). As described below, EPA's evaluation shows that the BART measures of the Regional Haze SIP submittal, that we are proposing to approve today, are generally consistent with the emissions reductions assumptions of the WRAP modeling from Idaho sources. Accordingly, EPA is proposing to approve Idaho's SIP as ensuring that emissions from Idaho do not interfere with the reasonable progress goals of other states.

In developing their visibility projections using photochemical grid modeling, the WRAP states assumed a certain level of emissions from sources within Idaho. The visibility projection modeling was in turn used by the states to establish their own reasonable progress goals. We have reviewed the WRAP photochemical modeling emissions projections used in the demonstration of reasonable progress towards natural visibility conditions and compared them to the emissions limits that will result from the imposition of BART on sources in Idaho. We have concluded that with the emissions reductions achieved by these measures, the emissions from Idaho sources in the projected inventory for 2018 (which included both reductions and increases) will be below that assumed in the WRAP analysis. In addition, EPA notes that these projections also included estimated emissions from a new coal fired power plant to be located in Jerome, Idaho. The Governor of Idaho subsequently issued a ban on the construction of new coal fired power plants that is still in effect. Thus, EPA anticipates that the actual emissions in 2018 may be significantly less than the emissions used in modeling 2018 conditions because the Jerome, Idaho facility will likely not be constructed during the time period covered by the Regional Haze SIP.

As a result of the foregoing determination, EPA is proposing to find that the Idaho Regional Haze SIP submission contains the emission reductions needed to achieve Idaho's share of emission reductions agreed upon through the regional planning process. As reflected in its Regional Haze SIP submittal, Idaho committed to achieve these emission reductions to address impacts on visibility on Class I areas in surrounding states. The portions of the Idaho Regional Haze SIP that we are proposing to approve ensure that emissions from Idaho will not interfere with the reasonable progress goals for neighboring state's Class I areas. EPA is accordingly proposing to find that these emission reductions also meet the requirements of section 110(a)(2)(D)(i)(II) of the Act with respect to the visibility prong for the 1997 8-hour ozone and 1997 PM2.5 NAAQS.

V. What action is EPA proposing?

EPA is proposing to approve portions of the Idaho Regional Haze plan, submitted on October 25, 2010, as meeting the requirements set forth in section 169A of the Act and in 40 CFR 51.308(e) regarding BART. EPA is also proposing to approve the Idaho submittal as meeting the requirements of 51.308(d)(2) and (4)(v) regarding the calculation of baseline and natural conditions for Craters of the Moon National Monument, Sawtooth Wilderness Area, and Selway-bitterroot Wilderness, and the statewide inventory of emissions of pollutants that are reasonably anticipated to cause or contribute to visibility impairment in any mandatory Class I Federal Area. In addition, EPA is proposing to find that the BART measures in the Idaho Regional Haze plan meet the requirements of section 110(a)(D)(ii)(II) of the CAA with respect to the 1997 8-hour ozone and 1997 PM2.5 NAAQS.

VI. Scope of Action

Idaho has not demonstrated authority to implement and enforce IDAPA chapter 58 within “Indian Country” as defined in 18 U.S.C. 1151.^[11] Therefore, EPA proposes that this SIP approval not extend to “Indian Country” in Idaho. See CAA sections 110(a)(2)(A) (SIP shall include enforceable emission limits), 110(a)(2)(E)(i) (State must have adequate authority under State law to carry out SIP), and 172(c)(6) (nonattainment SIPs shall include enforceable emission limits). This is consistent with EPA's previous approval of Idaho's prevention of significant deterioration (PSD) program, in which EPA specifically disapproved the program for sources within Indian Reservations in Idaho because the State had not shown it had authority to regulate such sources. See 40 CFR 52.683(b). It is also consistent with EPA's approval of Idaho's title V air operating permits program. See 61 FR 64622, 64623 (December 6, 1996) (interim approval does not extend to Indian Country); 66 FR 50574, 50575 (October 4, 2001) (full approval does not extend to Indian Country).

VII. Statutory and Executive Order Reviews

Under the Clean Air Act, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable Federal regulations. 42 U.S.C. 7410(k); 40 CFR 52.02(a). Thus, in reviewing SIP submissions, EPA's role is to approve state choices, provided that they meet the criteria of the Clean Air Act. Accordingly, this proposed action merely approves state law as meeting Federal requirements and does not impose additional requirements beyond those imposed by state law. For that reason, this proposed action:

• Is not a “significant regulatory action” subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
• Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
• Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
• Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
• Does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
• Is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
• Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
• Is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the Clean Air Act; and
• Does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

In addition, this rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), because the SIP is not approved to apply in Indian country located in the state, and EPA notes that it will not impose substantial direct costs on tribal governments or preempt tribal law.

List of Subjects in 40 CFR Part 52

• Environmental protection
• Air pollution control
• Intergovernmental relations
• Nitrogen dioxide
• Particulate matter
• Reporting and recordkeeping requirements
• Sulfur oxides, visibility, and Volatile organic compounds

Dated: December 22, 2010.

Dennis J. McLerran,

Regional Administrator, Region 10.

Footnotes

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.”

2.  See 64 FR at 35715.

3.  Id.

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).

5.  Wildearth Guardians v. Jackson, Case No. 4:09-CV-02453-CW (N.D. Calif.)

6.  The preamble to the RHR provides additional details about the deciview. 64 FR 35714, 35725 (July 1, 1999).

7.  The set of “major stationary sources” potentially subject to BART is listed in CAA section 169A(g)(7).

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.

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

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.

11.  “Indian country” is defined under 18 U.S.C. 1151 as: (1) All land within the limits of any Indian reservation under the jurisdiction of the United States Government, notwithstanding the issuance of any patent, and including rights-of-way running through the reservation, (2) all dependent Indian communities within the borders of the United States, whether within the original or subsequently acquired territory thereof, and whether within or without the limits of a State, and (3) all Indian allotments, the Indian titles to which have not been extinguished, including rights-of-way running through the same. Under this definition, EPA treats as reservations trust lands validly set aside for the use of a Tribe even if the trust lands have not been formally designated as a reservation. In Idaho, Indian country includes, but is not limited to, the Coeur d'Alene Reservation, the Duck Valley Reservation, the Reservation of the Kootenai Tribe, the Fort Hall Indian Reservation, and the Nez Perce Reservation as described in the 1863 Nez Perce Treaty.