94-19884. State Implementation Plans for Serious PM-10 Nonattainment Areas, and Attainment Date Waivers for PM-10 Nonattainment Areas Generally; Addendum to the General Preamble for the Implementation of Title I of the Clean Air Act Amendments of ...  

  • [Federal Register Volume 59, Number 157 (Tuesday, August 16, 1994)]
    [Unknown Section]
    [Page 0]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 94-19884]
    
    
    [[Page Unknown]]
    
    [Federal Register: August 16, 1994]
    
    
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    ENVIRONMENTAL PROTECTION AGENCY
    
    40 CFR Part 52
    
    [FRL-5052-2]
    
     
    
    State Implementation Plans for Serious PM-10 Nonattainment Areas, 
    and Attainment Date Waivers for PM-10 Nonattainment Areas Generally; 
    Addendum to the General Preamble for the Implementation of Title I of 
    the Clean Air Act Amendments of 1990
    
    AGENCY: Environmental Protection Agency (EPA).
    
    ACTION: Addendum to General Preamble for future proposed rulemakings.
    
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    SUMMARY: This addendum to the General Preamble for the Implementation 
    of Title I of the Clean Air Act Amendments of 1990 principally 
    describes EPA's preliminary views on how the Agency should interpret 
    various provisions of title I with regard to requirements for PM-10 
    (particles with an aerodynamic diameter less than or equal to a nominal 
    10 micrometers) serious nonattainment area State implementation plans 
    (SIP's). This document also addresses policy and guidance on attainment 
    date waivers potentially applicable to all areas that have been 
    designated nonattainment for PM-10, waivers of certain requirements 
    applicable to PM-10 serious nonattainment areas, and requirements for 
    international border areas in PM-10 nonattainment areas. Although the 
    guidance includes various statements that States must take certain 
    actions, these statements are made pursuant to EPA's preliminary 
    interpretations, and thus do not bind States and the public as a matter 
    of law. This addendum is an advance notice of how EPA generally intends 
    to take action on SIP submissions and to interpret various PM-10 
    related title I provisions.
    
    FOR FURTHER INFORMATION CONTACT: Charlene E. Spells, Air Quality 
    Management Division, Mail Drop 15, Office of Air Quality Planning and 
    Standards, U.S. EPA, Research Triangle Park, North Carolina 27711, 
    (919) 541-5255.
    
    ADDRESSES: References cited herein are available from the Public Docket 
    No. A-92-23. The docket is located at the Air and Radiation Docket and 
    Information Center, Room M-1500, Waterside Mall, Mail Code 6102, 401 M 
    Street SW., Washington, DC 20460. The docket may be inspected from 8:30 
    a.m. to 12 noon and from 1:30 p.m. to 3:30 p.m. on weekdays, except for 
    legal holidays. A reasonable fee may be charged for copying.
    
    Supplementary Information:
    
    Table of Contents
    
    I. Introduction
    II. Designations and Classifications
        A. Designations
        B. Classifications
        C. Reclassifications
        D. Appendix K and Waivers
    III. International Border Areas
        A. Statutory Requirement
        B. Policy
    IV. Serious Area SIP Requirements
    V. Waivers for Certain PM-10 Nonattainment Areas
        A. Historical Perspectives
        B. Waiver Provisions
        C. Application of Waiver Provisions
        D. Waiver Policy Description
    VI. Best Available Control Measures (BACM)
        A. Requirement for BACM
        B. EPA's Historical Interpretation of Control Technology 
    Terminology
        C. BACM for Serious PM-10 Nonattainment Areas
        D. Procedures for Determining BACM
        E. Selection of BACM for Area Sources
        F. Selection of Best Available Control Technology (BACT) for 
    Point Sources
    VII. Contingency Measures
    VIII. Quantitative Milestones and Reasonable Further Progress
        A. General Discussion
        B. Reasonable Further Progress
        C. Quantitative Milestones
    IX. Other Requirements
        A. Executive Order 12866
        B. Regulatory Flexibility Act
    
        In accordance with 1 CFR 5.9(c), this document is published in the 
    proposed rules category.
    
    I. Introduction
    
        Issues are discussed in this document regarding policy and guidance 
    that will be applicable to areas that have been designated 
    nonattainment for PM-10 and reclassified as serious areas. This 
    document also discusses issues regarding policy and guidance on 
    attainment date waivers potentially applicable to all areas that have 
    been designated nonattainment for PM-10, as well as policy and guidance 
    on waivers of certain other requirements applicable to PM-10 serious 
    nonattainment areas, and requirements for international border areas in 
    PM-10 nonattainment areas.
        Initially, all areas designated as nonattainment for PM-10 are 
    classified as moderate areas (see section 188(a) of the Clean Air Act 
    (Act)).\1\ Subsequently, in accordance with section 188(b) of the Act, 
    ``The Administrator may reclassify as a serious PM-10 nonattainment 
    area * * * any area that the Administrator determines cannot 
    practicably attain the national ambient air quality standard for PM-10 
    by the attainment date (as prescribed in subsection (c)) for moderate 
    areas'' or any area that fails to timely attain. The EPA took final 
    action on January 8, 1993 to reclassify 5 moderate areas that were 
    initially designated as nonattainment for PM-10 upon enactment of the 
    1990 Amendments (see 58 FR 3334). The EPA is considering reclassifying 
    additional areas from moderate to serious.
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        \1\The 1990 Amendments to the Clean Air Act made significant 
    changes to the air quality planning requirements for areas that do 
    not meet (or that significantly contribute to ambient air quality in 
    a nearby area that does not meet) the PM-10 national ambient air 
    quality standards (see Pub. L. No. 101-549, 104 Stat. 2399). 
    References herein are to the Clean Air Act, as amended, 42 U.S.C. 
    7401, et seq.
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        This guidance document is being published as an addendum to the 
    General Preamble for the Implementation of Title I of the Clean Air Act 
    Amendments of 1990 (General Preamble) published April 16, 1992 (57 FR 
    13498).\2\ Among other things, this PM-10 nonattainment area guidance 
    document describes EPA's preliminary views on how EPA should interpret 
    various provisions of title I with regard to requirements for PM-10 
    serious area SIP's. Although the guidance includes various statements 
    that States must take certain actions, these statements are made 
    pursuant to EPA's preliminary interpretations, and thus do not bind the 
    States and the public as a matter of law. Of course, the use of 
    prescriptive language is appropriate in those instances where the 
    policy is simply reiterating statutory mandates which provide that 
    States must take certain actions.
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        \2\A supplemental notice was published at 57 FR 18070, April 28, 
    1992, which provides certain appendices to the April 16, 1992 
    General Preamble. Subsequent references in this notice to the 
    General Preamble are inclusive of both documents.
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        Possible approaches to implementing the provisions in section 179B 
    applicable to international border areas, general SIP requirements of 
    section 172(c), the specific requirements in subpart 4 of part D of 
    title I in serious PM-10 nonattainment areas, the issues involved and 
    the means of resolving those issues are discussed in the following 
    sections. The topics discussed include SIP requirements such as 
    provisions to assure that best available control measures (BACM) are 
    implemented; waivers for areas impacted by nonanthropogenic sources; 
    treatment of international border areas; requirements for quantitative 
    milestones, reasonable further progress (RFP) and contingency measures.
    
    II. Designations and Classifications
    
    A. Designations
    
        Section 107(d) of the Act provides generally for the designation of 
    areas of each State as attainment, nonattainment or unclassifiable for 
    each pollutant for which there is a national ambient air quality 
    standard (NAAQS). Certain areas meeting the qualifications of section 
    107(d)(4)(B) of the Act were designated nonattainment for PM-10 by 
    operation of law upon enactment of the 1990 Amendments (initial PM-10 
    nonattainment areas). A Federal Register notice announcing all of the 
    areas designated nonattainment for PM-10 at enactment and classified as 
    moderate was published on March 15, 1991 (56 FR 11101). A follow-up 
    notice correcting some of these area designations was published August 
    8, 1991 (56 FR 37654). The nonattainment areas were formally codified 
    in 40 CFR part 81, effective January 6, 1992 (56 FR 56694, November 6, 
    1991). All those areas of the country not designated nonattainment for 
    PM-10 at enactment were designated unclassifiable (see section 
    107(d)(4)(B)(iii) of the Act).
    
    B. Classifications
    
        Once an area is designated nonattainment, section 188 of the Act 
    outlines the process for classification of the area and establishes the 
    area's attainment date. In accordance with section 188(a), all PM-10 
    nonattainment areas are initially classified as moderate by operation 
    of law upon their designation as nonattainment.
    
    C. Reclassifications
    
    1. General Conditions
        A moderate area can subsequently be reclassified as a serious 
    nonattainment area under two general conditions. First, EPA has general 
    discretion under section 188(b)(1) to reclassify a moderate area as a 
    serious area at any time the Administrator determines the area cannot 
    practicably attain the NAAQS by the statutory attainment date for 
    moderate areas.\3\
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        \3\The EPA's interpretation of the reclassification provisions 
    in section 188(b)(1) is discussed in detail in section III.C.1(b) of 
    the General Preamble (57 FR at 13537-38).
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        Second, under section 188(b)(2) a moderate area is reclassified as 
    serious by operation of law after the statutory attainment date has 
    passed if the Administrator finds that the area has not attained the 
    NAAQS. The EPA must publish a Federal Register notice identifying the 
    areas that have failed to attain and were reclassified, within 6 months 
    following the attainment date (see section 188(b)(2)(B)).
    2. Reclassification of Initial PM-10 Nonattainment Areas
        Section 188(b)(1)(A) provides an accelerated schedule by which EPA 
    is to reclassify appropriate initial PM-10 nonattainment areas. The EPA 
    proposed on November 21, 1991 (56 FR 58656) to reclassify 14 of the 70 
    initial moderate areas as serious. The 14 areas EPA proposed to 
    reclassify were identified largely based on the magnitude and frequency 
    of ambient PM-10 measurements above the 24-hour NAAQS of 150 micrograms 
    per cubic meter (g/m3) during calendar years 1988-1990. 
    The EPA took final action on January 8, 1993 (58 FR 3334) to reclassify 
    5 of the 14 areas. The final decision to reclassify the 5 areas was 
    based on the criteria utilized in the proposal, comments received in 
    response to the proposal and on EPA's preliminary review of the SIP's 
    for the areas.
        In the future, EPA anticipates that, generally, any decision to 
    reclassify an initial PM-10 nonattainment area before the attainment 
    date will be based on specific facts or circumstances demonstrating 
    that the NAAQS cannot practicably be attained in the area by December 
    31, 1994 (the statutory attainment date specified in section 188(c)(1) 
    for initial PM-10 nonattainment areas).
    3. Reclassification of Future PM-10 Nonattainment Areas
        Section 188(b)(1)(B) provides a timeframe within which EPA is to 
    reclassify appropriate areas designated nonattainment for PM-10 
    subsequent to enactment of the 1990 Amendments. Appropriate areas are 
    to be reclassified as serious within 18 months after the required date 
    for the State's submission of a moderate area PM-10 SIP.\4\ The statute 
    requires that these moderate area PM-10 SIP's be submitted within 18 
    months after the area is designated nonattainment (see section 
    189(a)(2)(B)). Taking these provisions together, the statute thus 
    requires that EPA reclassify appropriate PM-10 moderate areas 
    designated nonattainment after 1990 as serious within 3 years of such 
    designation.
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        \4\This directive does not restrict EPA's general authority, but 
    simply specifies that it is to be exercised, as appropriate, in 
    accordance with certain dates.
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        Because the moderate area SIP's are due before this 
    reclassification deadline, EPA anticipates that any determination that 
    such areas should be reclassified will be based upon facts contained in 
    the moderate area SIP demonstrating that the NAAQS cannot practicably 
    be attained by the statutory deadline. The EPA may also consider 
    reclassifying moderate areas for which a SIP has not been submitted 
    whenever it becomes apparent (e.g., because of an extensive delay in 
    submitting the SIP) that an area cannot practicably attain the 
    standards by the applicable attainment date. The EPA may also determine 
    that an area cannot practicably attain the standards by the applicable 
    date when the State submits an incomplete or otherwise inadequate SIP 
    for the area (i.e., a SIP which would not assure timely attainment) and 
    the State does not act expeditiously to correct such deficiencies.
        The EPA does not believe that generally reclassifying moderate 
    areas as serious rewards areas which delay development and 
    implementation of PM-10 control measures. Rather, EPA believes its 
    policy creates an incentive for the timely submittal and effective 
    implementation of moderate area SIP requirements and facilitates the 
    PM-10 attainment objective. For example, if an area that fails to 
    submit a timely moderate area SIP is reclassified, this does not 
    obviate the requirement that the area submit and implement the moderate 
    area SIP requirements. Accordingly, in addition to reclassifying such 
    areas, EPA would also determine that the State had failed to submit a 
    PM-10 SIP and the area could be subject to sanctions under sections 
    110(m) and 179 for its delay. As provided under section 179(a) of the 
    Act, States containing areas for which EPA has made such determinations 
    have up to 18 months from EPA's determination to submit a complete plan 
    or plan revision before EPA is required to impose either the highway 
    funding sanction or the requirement to provide two-to-one new source 
    offsets described in section 179(b). If the deficiency has not been 
    corrected 6 months after the first sanction applies, then the second 
    sanction must apply.\5\ The EPA's determination also triggers a 
    requirement for EPA to impose a Federal implementation plan under 
    section 110(c)(1) of the Act. In conjunction with the possible 
    imposition of sanctions, EPA may issue a determination to reclassify 
    the area to serious.
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        \5\See 58 FR 51270 (October 1, 1993).
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    D. Appendix K and Waivers
    
        Appendix K to 40 CFR part 50 provides guidance on the 
    interpretation of ambient air quality data to determine the air quality 
    status of an area. Appendix K and accompanying guidance (both preceding 
    the 1990 Amendments to the Act) provide in part that measured 
    exceedances of the PM-10 NAAQS which are believed to be influenced by 
    uncontrollable events caused by natural sources of particulate matter 
    or by events that are not expected to recur at a given location are 
    flagged and excluded from decisions as to whether or not the area 
    should be designated nonattainment.\6\ Therefore, if it is established 
    that exceedances are caused by natural sources, a State may be 
    permitted to avoid designating the area as nonattainment, even though 
    the exceedances are expected to recur.
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        \6\See section 2.4 of appendix K of 40 CFR part 50 and ``The 
    Guideline on the Identification and Use of Air Quality Data Affected 
    by Exceptional Events,'' EPA-450/4-86-007, July 1986.
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        The savings provision of section 193 of the amended Act provides, 
    among other things, that regulations and guidance promulgated or issued 
    by the Administrator prior to enactment of the 1990 Amendments are to 
    remain in effect according to their terms except to the extent that 
    they are inconsistent with any provision of the amended Act. Section 
    188(f) of the amended Act provides EPA with the discretionary authority 
    to waive a specific date of attainment for a PM-10 nonattainment area 
    where it is determined that nonanthropogenic sources contribute 
    significantly to the violation of the standard in the area, and to 
    waive certain nonattainment area SIP requirements where the 
    Administrator determines that anthropogenic sources of PM-10 do not 
    contribute significantly to the violation of the standard in the area. 
    These provisions take as a fundamental premise that areas experiencing 
    violations of the NAAQS due to nonanthropogenic sources are to be 
    designated as nonattainment. If areas were permitted to avoid being 
    designated as nonattainment because their violations are caused in 
    whole or part by uncontrollable natural events, then this statutory 
    provision would have to be read as having no legal effect or 
    significance. However, this would violate canons of statutory 
    construction, which direct that statutory language not be treated as 
    mere surplusage.
        Consequently, although appendix K appears to be preserved in part 
    by section 193, the provision permitting the treatment of 
    ``uncontrollable events caused by natural sources'' as exceptional 
    events, and therefore excludable from nonattainment decisions, is 
    inconsistent with the provisions of section 188(f) and should therefore 
    be regarded as no longer having legal effect. Similarly, any EPA 
    guidance permitting such exclusion of these events is inconsistent with 
    the amended Act. For this reason, exceedances which are attributable to 
    uncontrollable nonanthropogenic events may not be discounted or 
    deweighted in any manner, but must be fully considered in determining 
    whether violations of the NAAQS have occurred and whether designation 
    as nonattainment is warranted. Future determinations relevant to 
    exceptional events should therefore focus on the remaining type of 
    exceptional event identified under section 2.4 of 40 CFR part 50, 
    appendix K, namely whether the events--anthropogenic or 
    nonanthropogenic--are likely to recur at the same location.
        The EPA plans to make perfunctory modifications to section 2.4 of 
    40 CFR part 50, appendix K. In addition, guidance on the interpretation 
    of air quality data believed to be influenced by special events and 
    conditions will be addressed in a separate publication that will 
    replace the 1986 Exceptional Events Guideline.
    
    III. International Border Areas
    
    A. Statutory Requirement
    
        Section 818 of the 1990 Amendments added a new section, 179B, to 
    subpart 1, part D of title I. Section 179B applies to areas that could 
    attain the relevant NAAQS by the statutory attainment date but for 
    emissions emanating from outside the United States (U.S.). For PM-10 
    nonattainment areas, section 179B(a) provides that EPA must approve the 
    moderate area SIP if (1) the SIP meets all the applicable requirements 
    under the Act other than a requirement that such plan or revision 
    demonstrate attainment and maintenance of the PM-10 NAAQS by the 
    applicable attainment date, and (2) the State demonstrates to EPA's 
    satisfaction that the SIP would be adequate to attain and maintain the 
    PM-10 NAAQS by the attainment date but for emissions emanating from 
    outside the U.S. In addition, section 179B(d) provides that if a State 
    demonstrates that an area would have timely attained the PM-10 NAAQS 
    but for emissions emanating from outside the U.S., the area must not be 
    subject to the reclassification provisions of section 188(b)(2). 
    Section 188(b)(2) provides that any moderate PM-10 nonattainment area 
    that EPA determines is not in attainment after the applicable 
    attainment date shall be reclassified to serious by operation of law. 
    Therefore, the statute provides that areas that could attain but for 
    emissions emanating from outside the U.S. must not be reclassified as 
    serious after failing to attain by the applicable date.\7\
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        \7\As noted, section 179B(d) states that areas demonstrating 
    attainment of the standards, but for emissions emanating from 
    outside the U.S., shall not be subject to section 188(b)(2) 
    (reclassification for failure to attain). By analogy to this 
    provision and applying canons of statutory construction, EPA will 
    not reclassify before the applicable attainment date areas which can 
    demonstrate attainment of the standards, but for emissions emanating 
    from outside the U.S. (see section 188(b)(1)). First, section 179B 
    evinces a general congressional intent not to penalize areas where 
    emissions emanating from outside the country are the but-for cause 
    of the PM-10 nonattainment problems. Further, if EPA were to 
    reclassify such areas before the applicable attainment date, EPA, in 
    effect, would be reading section 179B(d) out of the statute. 
    Specifically, if EPA proceeded to reclassify, before the applicable 
    attainment date, those areas qualifying for treatment under section 
    179B, an area would never be subject to the provision in section 
    179B(d) which prohibits EPA from reclassifying such areas after the 
    applicable attainment date. Canons of statutory construction counsel 
    against interpreting the law such that language is rendered mere 
    surplusage. Finally, note that section 179B(d) contains a clearly 
    erroneous reference to carbon monoxide instead of PM-10, and that 
    this section contains other clear errors (see, e.g., section 179B(c) 
    reference to section 186(b)(9), which does not exist).
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    B. Policy
    
        Assuming that a plan or revision meets all applicable requirements, 
    the State must show that an area is eligible to have its SIP approved 
    and not be reclassified as serious under section 179B by evaluating the 
    impact of emissions emanating from outside the U.S. and demonstrating 
    that the SIP would bring about attainment but for those emissions. 
    Several types of information may be used to evaluate the impact of 
    emissions emanating from outside the U.S. The EPA will consider the 
    information presented by the State for individual nonattainment areas 
    on a case-by-case basis in determining whether an area may qualify for 
    treatment under section 179B. Five examples of such information are 
    listed below in increasing order of sophistication (the State may use 
    one or more of these types of information or other techniques, 
    depending on their feasibility and applicability, to evaluate the 
    impact of emissions emanating from outside the U.S. on the 
    nonattainment area; the first three examples do not require the State 
    to obtain information from a foreign country):
        1. Place several ambient PM-10 monitors and a meteorological 
    station, measuring wind speed and direction, in the U.S. nonattainment 
    area near the international border.\8\ Evaluate and quantify any 
    changes in monitored PM-10 concentrations with a change in the 
    predominant wind direction.
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        \8\See 40 CFR part 58 for guidance on locating PM-10 monitors 
    and ``On-site Meteorological Program Guidance for Regulatory 
    Modeling Applications,'' EPA-450/4-87-013, June 1987 for guidance on 
    locating meteorological stations.
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        2. Comprehensively inventory PM-10 emissions within the U.S. in the 
    vicinity of the nonattainment area and demonstrate that the impact of 
    those sources on the nonattainment area after application of reasonably 
    available controls does not cause the NAAQS to be exceeded. This 
    analysis must include an influx of background PM-10 in the area. 
    Background PM-10 levels could be based, for example, on concentrations 
    measured in a similar nearby area not influenced by emissions from 
    outside the U.S.
        3. Analyze ambient sample filters for specific types of particles 
    emanating from across the border (although not required, 
    characteristics of emissions from foreign sources may be helpful).
        4. Inventory the sources on both sides of the border and compare 
    the magnitude of PM-10 emissions originating within the U.S. to those 
    emanating from outside the U.S.
        5. Perform air dispersion and/or receptor modeling to quantify the 
    relative impacts on the nonattainment area of sources located within 
    the U.S. and of foreign sources of PM-10 emissions (this approach 
    combines information collected from the international emission 
    inventory, meteorological stations, ambient monitoring network, and 
    analysis of filters).
        In addition to demonstrating that the SIP for the area would be 
    adequate to timely attain and maintain the NAAQS but for emissions 
    emanating outside the U.S., the SIP must continue to meet all 
    applicable moderate area SIP requirements in order to qualify for the 
    special SIP approval under section 179B. Among other things, the SIP 
    must provide for the implementation of reasonably available control 
    measures (RACM), including reasonably available control technology 
    (RACT) (see 57 FR 13540). In international border areas, RACM/RACT must 
    be implemented to the extent necessary to demonstrate attainment by the 
    applicable attainment date if emissions emanating from outside the U.S. 
    were not included in the analysis. The EPA believes that this 
    interpretation of the degree of RACM the State is required to implement 
    in moderate PM-10 areas affected by emissions emanating from outside 
    the U.S. is consistent with the purpose of section 179B. By directing 
    EPA, under section 179B, to approve the plan or plan revision of a 
    moderate PM-10 area which shows it would attain the NAAQS but for 
    foreign emissions and by excluding such an area from reclassification 
    to serious, Congress clearly wanted to avoid penalizing States 
    containing such areas by not making them responsible for control of 
    emissions emanating from a foreign country over which they have no 
    jurisdiction. Moreover, by excluding the area from reclassification, 
    Congress also elected to avoid subjecting such areas to the more 
    stringent control measures applicable in serious PM-10 areas. In 
    addition, as set forth in section 179B(a)(2), the second condition 
    which must be met before EPA may approve a moderate area plan showing 
    attainment but for foreign emissions, by its plain terms, requires the 
    State to establish only that the plan submitted would be ``adequate'' 
    to timely attain and maintain the NAAQS, but for emissions from outside 
    the U.S. Nothing in section 179B relieves the State from meeting all 
    its applicable moderate area PM-10 SIP requirements, including the 
    requirement to implement RACM. Nonetheless, if, in doing so, States 
    containing such an area were also required, because of contributions to 
    PM-10 violations caused by foreign emissions, to shoulder more of a 
    regulatory and economic burden than States not similarly affected 
    (i.e., by implementing measures which go well beyond those which the 
    SIP demonstrates would otherwise be adequate to timely attain and 
    maintain the PM-10 NAAQS) such a requirement would unfairly penalize 
    States containing international border areas and effectively undermine 
    the purpose of section 179B. Indeed, to the extent an affected State 
    can satisfactorily demonstrate that implementation of such measures 
    clearly would not advance the attainment date, EPA could conclude they 
    are unreasonable and hence do not constitute RACM. Notwithstanding the 
    above, in light of the overall health and clean air objectives of the 
    Act, EPA does encourage affected States to reduce emissions beyond the 
    minimum necessary to satisfy the ``but for'' test in order to reduce 
    the PM-10 concentrations to which their populations are exposed.
        The SIP for an international border area must also include 
    contingency measures as required under section 172(c)(9) of the Act. 
    Under section 179B(a)(1), such SIP's must meet ``all the requirements 
    applicable to it under the Act'' except that they may demonstrate 
    timely attainment by discounting emissions emanating from outside the 
    U.S. Contingency measures are additional measures included in the SIP 
    that can be undertaken to reduce emissions if the area fails to make 
    RFP or to attain the primary NAAQS by the applicable attainment date. 
    In international border areas, EPA will not require the contingency 
    measures for PM-10 to be implemented after the area fails to attain if 
    EPA determines that the area would have attained the NAAQS, but for 
    emissions emanating from outside the U.S. However, the EPA will require 
    contingency measures to be implemented if it determines that the area 
    failed to make RFP in achieving the required reductions in PM-10 
    emissions from sources within the U.S., or if the area does not, in 
    fact, obtain the emission reductions that were necessary to demonstrate 
    timely attainment of the NAAQS, but for emissions emanating from 
    outside the U.S.
    
    IV. Serious Area SIP Requirements
    
        The Act requires States to submit several SIP revisions, as 
    necessary, providing for implementation of increasingly stringent 
    control measures and demonstrating when those control measures will 
    bring about attainment of the PM-10 NAAQS. The first SIP revision was 
    due November 15, 1991 for the initial moderate PM-10 nonattainment 
    areas. For areas redesignated nonattainment for PM-10 in the future 
    under section 107(d)(3), the first SIP revision will be due within 18 
    months after the area is redesignated (see section 189(a)(2)). This SIP 
    revision must, among other things, provide for implementation of RACM 
    on sources in the area (see sections 189(a)(1)(C) and 172(c)(1)). All 
    available technologically and economically feasible control measures 
    would be considered RACM, and therefore reasonable for adoption, for 
    areas that cannot attain the NAAQS by the applicable attainment date 
    (December 31, 1994 for initial moderate PM-10 nonattainment areas) (see 
    57 FR 13544).9
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        \9\Note that if it can be shown that measures are unreasonable 
    because emissions from the sources affected are insignificant or de 
    minimis, such measures may be excluded from consideration as they 
    would not represent RACM for that area (see 57 FR 13540). Moreover, 
    in international border areas, measures which go beyond those which 
    the SIP demonstrates would be adequate to attain and maintain the 
    standard, but for emissions emanating from outside the U.S., would 
    not be considered ``reasonably'' available--and therefore would not 
    be required by RACM--since they would not advance the attainment 
    date (although States may elect to implement such measures in order 
    to reduce the public's exposure to PM-10) (see discussion under 
    International Border Areas of this guidance document).
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        If EPA determines that a moderate area cannot practicably attain 
    the NAAQS by the applicable attainment date (or determines the area has 
    failed to attain) and reclassifies the area as a serious nonattainment 
    area under section 188(b), a second SIP revision for the area is 
    required under section 189(b). This revision must, among other things, 
    include provisions to assure that BACM (including BACT) will be 
    implemented in the area (see section 189(b)(1)(B)). In addition, a 
    demonstration (including air quality modeling) must be submitted 
    showing that the plan will attain the NAAQS either by the applicable 
    attainment date or, if an extension is granted under section 188(e), by 
    the most expeditious alternative date practicable (see section 
    189(b)(1)(A)).
        The SIP revisions to require the implementation of BACM must be 
    submitted to EPA within 18 months after an area is reclassified as 
    serious (see section 189(b)(2)). The BACM are to be implemented no 
    later than 4 years after an area is reclassified (see section 
    189(b)(1)(B)). The EPA's policies regarding the requirement to 
    implement BACM in serious areas are discussed in section VI of this 
    document.
        The serious area attainment demonstration required under section 
    189(b)(1)(A) must be submitted to EPA within 4 years after an area is 
    reclassified based on a determination by EPA that the area cannot 
    practicably attain the NAAQS by the statutory deadline for moderate 
    areas. It is due within 18 months after an area is reclassified for 
    actually having failed to attain the NAAQS by the moderate area 
    attainment date (see section 189(b)(2)).
        The new attainment date for initial PM-10 nonattainment areas that 
    are reclassified as serious is to be as expeditious as practicable but 
    not later than December 31, 2001. For areas that are designated 
    nonattainment for PM-10 in the future and subsequently become serious, 
    the attainment date is to be as expeditious as practicable but no later 
    than the end of the tenth calendar year beginning after the area's 
    designation as nonattainment (see section 188(c)(2)).
        If the State demonstrates to the satisfaction of EPA that 
    attainment by the statutory deadline for serious areas (as set forth in 
    section 188(c) of the Act) is impracticable, the State must demonstrate 
    that the SIP provides for attainment by the most expeditious 
    alternative date practicable. The State may apply to EPA for a single 
    extension of the serious area attainment date, under section 188(e) of 
    the Act, not to exceed 5 years beyond the serious area attainment date. 
    A State requesting an extension under section 188(e) for an area must, 
    among other things, demonstrate that the plan for the area includes the 
    most stringent measures that are included in the implementation plan of 
    any State or are achieved in practice in any State, and can feasibly be 
    implemented in the area. The EPA intends to issue guidance in the 
    future, as appropriate, on applying for an extension of the serious 
    area attainment date.
        If a serious area fails to attain by the applicable attainment date 
    (which may be an extended attainment date), another SIP revision is 
    required within 12 months that provides for attainment and until then 
    for annual reductions in PM-10 or PM-10 precursor emissions within the 
    area of not less than 5 percent of the amount of such emissions as 
    reported in the most recent emission inventory for the area (see 
    section 189(d)).
        In addition to the specific PM-10 SIP requirements contained in 
    subpart 4 of part D, title I, States containing serious areas must meet 
    all of the applicable general SIP requirements set forth in section 
    110(a)(2) and the nonattainment area SIP requirements set forth in 
    subpart 1 of part D, title I, to the extent that these provisions are 
    not otherwise subsumed by, or integrally related to, the more specific 
    PM-10 requirements.10 The general SIP requirements applicable to 
    all nonattainment areas are discussed in the General Preamble at 57 FR 
    13556-13557.
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        \1\0See 57 FR 13538 (April 16, 1992).
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        The requirements specifically applicable to serious areas under 
    subpart 4 are found primarily in section 189. Those requirements 
    include:
        a. Current actual and allowable emissions inventories that meet EPA 
    guidelines11 (see section VI.D. below).
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        \1\1``PM-10 Emission Inventory Requirements,'' EPA-450/2-93-XX, 
    U.S. Environmental Protection Agency, Research Triangle Park, NC, 
    1993.
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        b. Submission of a SIP, under section 189(b)(1)(A), that includes a 
    demonstration that the plan provides for attainment by the applicable 
    attainment date (December 31, 2001 for the areas initially designated 
    nonattainment for PM-10 by operation of law under section 107(d)(4) and 
    no later than the end of the tenth year beginning after the area's 
    redesignation for areas subsequently redesignated nonattainment), or a 
    demonstration that attainment by the above date is not practicable and 
    that the plan provides for attainment by the most expeditious 
    alternative date practicable.12
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        \1\2Subsequent to adopting requirements for BACM shortly after 
    the nonattainment area is reclassified as serious, it may be 
    necessary for the State to adopt additional control measures in 
    order to demonstrate that the SIP provides for attainment of the PM-
    10 NAAQS in accordance with section 189(b)(1)(A)(i). If the State 
    demonstrates, in accordance with section 189(b)(1)(A)(ii), that 
    attainment by the applicable serious area attainment date is 
    impracticable and seeks an extension of the attainment date pursuant 
    to section 188(e), the State must demonstrate to the best of its 
    ability that the plan for the area includes the most stringent 
    measures that are included in the implementation plan of any State 
    or are achieved in practice in any State, and can be feasibly 
    implemented in the area.
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        c. Provisions, under section 189(b)(1)(B), to assure that BACM 
    (including BACT) will be implemented no later than 4 years after the 
    area is reclassified as serious.
        d. A requirement, under section 189(b)(3), that the terms ``major 
    source'' and ``major stationary source,'' used in implementing a new 
    source permitting program under section 173 and control of PM-10 
    precursors under section 189(e), include any stationary source or group 
    of stationary sources located within a contiguous area and under common 
    control that emits, or has the potential to emit, at least 70 tons per 
    year of PM-10.
        e. Contingency measures13 (see section VII. below).
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        \1\3Contingency measures are other available control measures, 
    in addition to those in the control strategy to attain the NAAQS, 
    that can be implemented if EPA determines the area fails to make 
    reasonable further progress or to attain the NAAQS by the applicable 
    attainment date [see section 172(c)(9)).
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        f. Quantitative milestones, (applicable to both moderate and 
    serious area SIP's under section 189(c)), which are to be achieved 
    every 3 years until the area is redesignated attainment, and which 
    demonstrate RFP toward attainment by the applicable date. The provision 
    includes a requirement for periodic reports demonstrating whether the 
    milestones have been met (see section VIII. below).
        g. Plan revisions which provide for attainment of the PM-10 NAAQS 
    and annual reductions of not less than 5 percent of inventoried PM-10 
    and PM-10 precursor emissions within the area, under section 189(d), if 
    the serious area fails to attain the standards.
        h. As applicable, RACT-level, BACT-level, and new source review 
    control of PM-10 precursors from major stationary sources of precursors 
    in the airshed (applicable to both moderate and serious area SIP's 
    under section 189(e)).
        The demonstration required under section 189(b)(1)(A) should follow 
    the existing modeling guidelines addressing PM-10 (e.g., ``PM-10 SIP 
    Development Guideline'' (June 1987); ``Guideline on Air Quality 
    Models'' (Revised); memorandum from Joseph Tikvart and Robert Bauman 
    dated July 5, 1990) and any applicable regulatory requirements. A 
    supplementary attainment demonstration policy applicable to initial 
    moderate PM-10 nonattainment areas facing special circumstances was 
    issued in a memorandum from EPA's Office of Air Quality Planning and 
    Standards to the Directors of EPA Regional Air Divisions on March 4, 
    1991.14 That supplementary policy is not applicable to serious 
    area SIP demonstrations.
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        \1\4``PM-10 SIP Attainment Demonstration Policy for Initial 
    Moderate Nonattainment Areas,'' memorandum from John Calcagni and 
    William Laxton to Director, Air Division, EPA Regions I-X, March 4, 
    1991.
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    V. Waivers for Certain PM-10 Nonattainment Areas
    
    A. Historical Perspectives
    
        The EPA in the past focused much of its air pollution control 
    efforts on industrial point source emissions and other traditional 
    sources of air pollution.15 For instance, EPA's 1977 guidance on 
    SIP development gave priority to control of urban fugitive dust after 
    control of traditional sources, but in preference to rural fugitive 
    dust, on the grounds that (1) urban soil was believed to be 
    contaminated and, therefore, potentially more harmful than the native 
    soils in rural areas; (2) the potential for significant population 
    exposures and attendant health effects was much greater in urban areas; 
    and (3) scarce resources at the Federal, State, and local agency levels 
    could be most effectively brought to bear on the more pronounced 
    problems found in urban areas.16 Accordingly, EPA's policy was to 
    require greater emphasis on control of emissions in urban areas, 
    including control of fugitive dust from all major sources. In contrast, 
    control requirements for rural areas were far less ambitious, focussing 
    on the control of major industrial sources, with little attention given 
    to natural or nonindustrial emissions. This policy of giving a lower 
    priority to controlling natural or nonindustrial emissions in rural 
    areas became known as the ``Rural Fugitive Dust Policy.''17
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        \1\5The EPA distinguished between ``traditional'' and 
    ``nontraditional'' sources. The term ``nontraditional source'' first 
    appeared in official print in 1976 in EPA's ``National Assessment of 
    the Urban Particulate Problem,'' EPA-450/3-76-024, July 1976, and 
    was coined as a catch-all to refer to those sources not 
    traditionally considered in air pollution control strategies, 
    including construction and demolition, tailpipe emissions, tire 
    wear, and various sources of fugitive dust. Since then, the use of 
    the term has expanded to include such sources as prescribed 
    agricultural and silvicultural burning, open burning, and 
    residential wood combustion.
        \1\6''Guidance on SIP Development and New Source Review in Areas 
    Impacted by Fugitive Dust,'' Edward F. Tuerk, Acting Assistant 
    Administrator for Air and Waste Management, to Regional 
    Administrators.
        \1\7See, e.g., ``Model Letter Regarding State Designation of 
    Attainment Status,'' David H. Hawkins, Assistant Administrator for 
    Air and Waste Management, to Regional Administrators, October 7, 
    1977; see also, ``Fugitive Dust Policy: SIP's and New Source 
    Review'' (August 1984).
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        The EPA's policy focus shifted away from the type and location of 
    the emission sources (i.e., traditional or nontraditional sources, 
    urban or rural locations) to the size of the particles emitted when the 
    indicator for the NAAQS was changed in 1987 from total suspended 
    particulate matter to PM-10. While revisions to the rural fugitive dust 
    policy were being considered, the policy was continued during the 
    initial phases of implementing the PM-10 NAAQS on an interim 
    basis.18 However, EPA believes that the 1990 Amendments provide a 
    statutory alternative that wholly supplants the rural fugitive dust 
    policy (see sections 107(d)(4)(B) and 188(f) of the amended Act; 56 FR 
    37659 (August 8, 1991)).
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        \1\8See 52 FR 24716 (July 1, 1987).
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    B. Waiver Provisions
    
        The Act, as amended in November 1990, was designed to assure that 
    attainment and maintenance of the PM-10 standards, which were 
    promulgated in 1987 (52 FR 24634, July 1, 1987), be as expeditious as 
    practicable. Thus, the Act requires States to submit several revisions 
    of the SIP for PM-10 nonattainment areas, if necessary, to ensure 
    attainment of the PM-10 NAAQS as expeditiously as practicable. Among 
    other planning requirements, the SIP revisions must first provide for 
    the implementation of RACM on PM-10 sources. If RACM is not adequate to 
    attain the NAAQS, subsequent revisions must provide for implementation 
    of additional, more stringent control measures until the NAAQS are 
    attained.
        Congress recognized that there may be areas where the NAAQS may 
    never be attained because of PM-10 emissions from ``nonanthropogenic 
    sources,''19 and that the imposition in such areas of certain 
    State planning requirements, as described in the previous section, may 
    not be justified. Therefore, under section 188(f) of the Act, Congress 
    provided a means for EPA to waive a specific date for attainment and 
    certain control and planning requirements when certain conditions are 
    met in the nonattainment area.
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        \1\9The legislative history of the 1990 Amendments indicates 
    that Congress intended that the term ``nonanthropogenic'' sources of 
    PM-10 refer to activities where the human role in the cause of such 
    emissions is highly attenuated [see H.R. Rep. No. 490, 101st Cong., 
    2d Sess. 265 (1990)).
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        Section 188(f) provides two types of waivers. First, the 
    Administrator may, on a case-by-case basis, waive any requirement under 
    subpart 4 applicable to any serious nonattainment area where EPA 
    determines that anthropogenic sources of PM-10 do not contribute 
    significantly to the violation of the standard in the area. Second, the 
    Administrator may waive a specific date for attainment of the standard 
    where EPA determines that nonanthropogenic sources of PM-10 contribute 
    significantly to the violation of the standard in the area.
        Section 188(f) contains two different legal tests. The first test 
    applies to a waiver of the serious area requirements and requires that 
    EPA determine that anthropogenic sources do not contribute 
    significantly before EPA grants such a waiver. The second test applies 
    to a waiver of an area's attainment date and requires that EPA 
    determine that nonanthropogenic sources contribute significantly before 
    waiving the attainment date. The first test is more stringent than the 
    second.
    
    C. Application of the Waiver Provisions
    
        Several questions must be answered before the waiver provisions can 
    be applied. Each of these questions is discussed in the subsections 
    that follow.
        1. What types of sources should be considered anthropogenic and 
    nonanthropogenic?
        The legislative history of the 1990 Amendments indicates that 
    Congress intended that the term ``nonanthropogenic'' sources of PM-10 
    refer to activities where the human role in the cause of such emissions 
    is highly attenuated (see H.R. Rep. No. 490 at 265). Naturally 
    occurring events such as wildfires, volcanic eruptions, unusually high 
    pollen counts, and high winds which generate dust from undisturbed land 
    are examples of nonanthropogenic sources that EPA believes meet the 
    intent of Congress.
        Anthropogenic sources of PM-10 emissions are those resulting from 
    human activities. Some of the traditional and nontraditional 
    anthropogenic sources generally considered in PM-10 SIP's are 
    commercial, institutional, and residential fuel combustion; fossil 
    fuel-fired electric power plants; industrial processes; vehicular 
    traffic on paved and unpaved roads; construction activities; 
    agricultural activities; and other sources of fugitive dust which are 
    directly traceable to human activities and which are reasonably 
    foreseeable incidents of such activities.20
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        \2\0``PM-10 SIP Development Guideline,'' EPA-450/2-86-001, U.S. 
    Environmental Protection Agency, Research Triangle Park, NC, 1987, 
    p. 5-5, Table 5.1.
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        2. What criteria should be used in determining when 
    nonanthropogenic sources contribute significantly and when 
    anthropogenic sources do not contribute significantly to violation of 
    the NAAQS in the area?
        The Act does not define the term ``contribute significantly'' as it 
    is used in section 188(f), nor does the legislative history provide any 
    useful guidance.21 Where a statute is silent or ambiguous with 
    respect to the meaning of a statutory term, a reasonable agency 
    interpretation of the term must be given deference by a reviewing court 
    (see Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc., 
    467 U.S. 837, 842-845 (1984)). The EPA thus believes it has the 
    authority to select reasonable criteria by which to determine when 
    nonanthropogenic/anthropogenic sources in an area do/do not 
    ``contribute significantly'' to levels of pollution which exceed the 
    NAAQS, as well as to consider for this purpose, criteria utilized in 
    other statutory contexts. In light of the different legal tests set 
    forth in section 188(f), the EPA believes that different indicators of 
    significance are needed to serve the statutory purpose of encouraging 
    protection of public health and welfare while avoiding unreasonable 
    control actions. The criteria which EPA believes provide a reasonable 
    approach to making such a determination, as well as a discussion of the 
    basis for selecting these criteria, are set forth below.
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        \2\1It should be noted that the term ``contribute 
    significantly'' (or variations of that term) has been interpreted 
    differently throughout the Act, e.g., in the ozone/carbon monoxide 
    programs (see section 107(d)(4)(A)(iv) and (v)), the new source 
    review (NSR) program, and in specific provisions of the statute, 
    such as sections 110(a)(2)(D)(i)(I) and 126(a)(1)(B). An agency is 
    permitted, but not required, to give a similar meaning to similar 
    terms which appear in different parts of a statute. Thus, although 
    EPA is not bound to adopt the interpretation given the term 
    ``contribute significantly'' in other parts of the statute, it is 
    likewise not precluded from according this use of similar language 
    some interpretive weight.
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        Generally, where a nonattainment area's anthropogenic sources 
    contribute very little to violations, it is likely that controlling 
    those emissions to the extent feasible for the area will be 
    insufficient to attain the NAAQS. In such cases, it would be 
    unreasonable to require the area to implement more stringent and more 
    expensive controls on anthropogenic sources since they would contribute 
    little to attainment or to reducing the public's exposure to unhealthy 
    air quality. In similar fashion, where nonanthropogenic emission 
    contributions are great, even after the area has taken reasonable steps 
    to reduce them, at some point it may not be feasible for the area to 
    reduce nonanthropogenic (or anthropogenic) emissions sufficiently to 
    effect any real change in ambient concentrations. Consequently, it 
    would be unreasonable to require the area to continue to pursue control 
    measures that are beyond the area's practicable abilities. These 
    principles are discussed below in connection with each of the two 
    waiver tests.
        In selecting an appropriate ``significance'' contribution from 
    anthropogenic sources (for the purposes of deciding whether serious 
    area requirements should be waived), EPA has elected to rely on the 
    test of significance that is applied under new source permitting 
    programs. Under the new source review (NSR) permit program, the EPA 
    requires State permitting programs to consider new major sources or 
    major modifications as causing or contributing to a violation of the 
    PM-10 NAAQS when the source would add, at a minimum, over 5 g/
    m\3\ to the 24-hour average or over 1 g/m\3\ to the annual 
    average PM-10 concentrations in an area that does not or would not meet 
    the PM-10 NAAQS (see 40 CFR 51.165(b)). Given that the purpose of new 
    source permitting programs is also to protect air quality in both 
    attainment and nonattainment areas, EPA generally believes that the 
    test of significant contribution to violations under that program 
    should also be applicable when determining significant contributions of 
    anthropogenic sources under section 188(f) of the Act. It should also 
    be noted that, in determining ``significance'' for purposes of section 
    188(f), the plain terms of that provision and its underlying purpose 
    dictate that EPA consider the impact of the anthropogenic sources as a 
    whole. Consequently, where emissions from all anthropogenic sources as 
    a whole contribute less than or equal to 5 g/m\3\ to 24-hour 
    average design concentrations and less than or equal to 1 g/
    m\3\ to annual mean design concentrations in a nonattainment area, 
    after all RACM have been implemented,22 EPA will generally regard 
    such contributions as insignificant for purposes of waiving 
    requirements applicable to serious PM-10 nonattainment areas pursuant 
    to section 188(f).
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        \2\2Implementation of RACM (including RACT) is required in all 
    moderate PM-10 nonattainment areas and that requirement is not 
    waived under the provisions of section 188(f). Therefore, the issue 
    is whether anthropogenic sources still contribute significantly to 
    violations of the NAAQS in an area, after implementing RACM.
    ---------------------------------------------------------------------------
    
        Generally, if an area meeting this test has not yet been 
    reclassified as serious and the area would qualify under this test for 
    a waiver of certain serious area requirements as deemed appropriate by 
    EPA (see discussion below), then EPA will not require reclassification, 
    since that action would have no practical effect. Generally, if the 
    contribution of anthropogenic emissions to the 24-hour design 
    concentration exceeds 5 g/m\3\, or if the contribution to the 
    annual design concentration exceeds 1 g/m\3\, even after the 
    application of all RACM, then the area should be reclassified as 
    serious, and serious area requirements, including BACM, should be 
    implemented. The EPA will consider exercising its authority to waive 
    serious area requirements on a case-by-case basis where the 
    anthropogenic source contribution exceeds these levels, and it can be 
    persuasively demonstrated that because of unique circumstances, 
    anthropogenic sources do not contribute significantly to violations of 
    the PM-10 NAAQS in the area.
        The EPA will consider nonanthropogenic sources to contribute 
    significantly (and hence grant an attainment date waiver) only if, 
    after the application of RACM to nonanthropogenic sources, their 
    contribution to the 24-hour average design concentration exceeds 150 
    g/m\3\, or their contribution to the annual mean design 
    concentration exceeds 50 g/m\3\. Because the basic purpose of 
    title I is to protect public health and welfare through attainment and 
    maintenance of the NAAQS, EPA believes that before it may generally 
    presume a serious area's nonanthropogenic emissions contribution to be 
    significant, that contribution should by itself prevent the area from 
    attaining the NAAQS after reasonable steps have been taken to reduce or 
    minimize their impacts. Areas which do not meet the above criteria, and 
    other situations for which the general presumption is rebutted, will be 
    reviewed on a case-by case basis (see question 4 below).
        Information derived from chemical and optical analyses of ambient 
    filter catches, area emission inventories, and dispersion modeling to 
    determine maximum source impacts can be used to evaluate the impact of 
    anthropogenic and nonanthropogenic sources. Analysis of filters 
    collected with a network of monitors over a long period (1 or more 
    years) should reveal the portions of normal area PM-10 concentrations 
    attributable to background, nonanthropogenic, and anthropogenic 
    sources, respectively.
        3. Under what conditions will the attainment date for a moderate 
    area be waived?
        The effect of waiving the attainment date for a moderate area is to 
    relieve it of the serious area requirements. Therefore, special 
    considerations apply to the determination of whether nonanthropogenic 
    sources contribute significantly to violation of the PM-10 NAAQS in a 
    moderate area and whether such area therefore qualifies for an 
    attainment date waiver.
        The significant disparity between the legal tests set out in 
    section 188(f), as discussed above, may lead to an absurd result. In 
    particular, if a moderate area met the less stringent attainment date 
    waiver test and the attainment date for the area was actually waived, 
    the area would never be reclassified.\23\ The result would be that a 
    moderate area would be effectively relieved from the serious area 
    requirements without having met the more stringent test that Congress 
    expressly required be met as a prerequisite to a waiver of such 
    requirements. In such an event, the more stringent test for determining 
    whether to waive serious area requirements would be rendered 
    meaningless. Moderate areas would qualify for the attainment date 
    waiver, be effectively relieved of all serious area requirements and 
    never have to meet the required test for such waiver.
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        \23\If EPA waives a specific attainment date for a moderate area 
    consistent with its authority under section 188(f), the attainment 
    date for the area will be vacated. Therefore, the moderate area 
    would not be subject to reclassification under section 188(b) 
    because there simply would be no attainment date that the area 
    cannot practicably meet or that the area fails to meet. However, 
    since section 188(f) authorizes waiving only the attainment date, 
    the moderate area would still be subject to all the remaining 
    moderate area SIP requirements. Therefore, the moderate area SIP 
    submitted to meet the applicable requirements of subparts 1 and 4 
    must, among other requirements, continue to provide for 
    implementation of RACM.
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        To avoid this absurd result and only grant a waiver of the serious 
    area requirements consistent with the legal standard set out in the 
    Act, EPA has construed section 188(f) in the following manner. A 
    moderate area may only qualify for an attainment date waiver if it also 
    qualifies for a waiver of the serious area requirements. Therefore, EPA 
    must determine that anthropogenic sources in the area do not contribute 
    significantly to the violation of the PM-10 NAAQS, and the serious area 
    requirements should be waived before EPA can grant an attainment date 
    waiver for a moderate area. If such a determination is made, then the 
    attainment date may be waived and the area would not be reclassified. 
    These special considerations would not be relevant where EPA is 
    determining whether to waive the attainment date for a serious area 
    since waiving the date in such circumstances would not as a matter of 
    course have the effect of relieving the area of the serious area 
    requirements. An area already reclassified as serious could qualify for 
    an attainment date waiver solely by showing that nonanthropogenic 
    emissions contribute significantly to the nonattainment problem.
        As part of its policy, EPA will require that areas receiving 
    waivers be revisited periodically to reevaluate source contributions, 
    to ensure that source emissions growth is reasonably controlled, and to 
    determine whether additional controls to reduce the public's exposure 
    to high concentrations of PM-10 are available (see also the discussion 
    under question 5).
        4. What happens if an area cannot meet the general criteria 
    described above?
        If evidence in a given nonattainment area suggests that 
    nonanthropogenic emissions may contribute significantly to violations 
    but are not greater than 150 g/m3 and/or anthropogenic 
    source contributions are relatively small but not less than 5 
    g/m3, then EPA will review the situation on a case-by-
    case basis taking into account relevant information such as the 
    relative contribution of nonanthropogenic emissions/anthropogenic 
    emissions and the effects of applying additional controls to both types 
    of sources.
        For moderate areas, if preliminary data (emission inventory, filter 
    analysis, etc.) persuasively indicate that anthropogenic emissions may 
    be insignificant and that nonanthropogenic emissions may be significant 
    in an area, but such data are not decisive, then EPA will consider 
    granting a temporary or conditional waiver of the moderate area 
    attainment date for no more than 3 years to allow further evaluation of 
    the situation. Prior to granting a temporary waiver, EPA and the State 
    must agree on a protocol for evaluating the impacts of anthropogenic 
    and nonanthropogenic emissions. The protocol must include a schedule 
    with interim milestones by which the State will complete its analyses. 
    The schedule should consider the need for the area to adopt and 
    implement BACM so as to meet the applicable serious area attainment 
    date (as expeditiously as practicable and, for those areas designated 
    nonattainment under section 107(d)(4)(B), no later than December 31, 
    2001) in the event the evaluation demonstrates that nonanthropogenic 
    emissions do not contribute significantly to violations in the area. If 
    the evaluation conclusively demonstrates that nonanthropogenic 
    emissions are significant, then a waiver of the serious area attainment 
    date may be granted.
        If it is shown for any moderate nonattainment area that, although 
    nonanthropogenic emissions may be significant, the application of 
    controls on anthropogenic sources would appreciably reduce PM-10 
    concentrations in the area, then the area would not be granted a waiver 
    of the moderate area attainment date, but would be reclassified as 
    serious. The area would then be required to implement BACM on non-de 
    minimis anthropogenic source categories (see discussion in section VI). 
    However, subsequent to such reclassification, the area may later apply 
    for a waiver of the serious area attainment date if it can demonstrate 
    that even after implementing BACM (and after considering the extended 
    attainment and post-attainment provisions of sections 188 and 189 of 
    the Act), nonanthropogenic emissions will prevent the area from 
    attaining the NAAQS.
        5. For what period may a specific attainment date be waived?
        When nonanthropogenic sources have been determined to contribute 
    significantly to violations in an area that has been reclassified to 
    serious, in accordance with the above criteria, those sources may 
    permanently prevent the area from attaining the standards. Therefore, 
    the attainment date for such areas could be waived indefinitely.24 
    ``However, the phrase waive a specific date'' does not require that the 
    attainment date be waived indefinitely (see footnote 23 on the effect 
    of waiving the moderate area attainment date), nor does it lessen the 
    State's obligation to strive to expeditiously attain the NAAQS at some 
    time in the future through available means. While EPA does not expect 
    States to exhaust their resources to meet standards that may be 
    unattainable, it does expect them to continue efforts to minimize 
    exposures to unhealthy air.
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        \2\4In cases where it is feasible to implement measures that 
    will reduce future emissions from nonanthropogenic sources (i.e., 
    planting indigenous vegetation or establishing wind breaks), EPA has 
    the authority under section 188(e) to extend the attainment date for 
    a serious area for up to 5 years beyond 2001 if it is possible that 
    the NAAQS could be attained in the future. Such measures should be 
    considered by States before seeking waivers of the attainment date.
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        Even though a specific attainment date and serious area 
    requirements may be waived indefinitely for an area where, 
    respectively, nonanthropogenic sources contribute significantly to 
    violations and anthropogenic sources do not, the State should review 
    the status of anthropogenic and nonanthropogenic source contributions 
    in the area every 3 years. Such a review would entail determining 
    whether nonanthropogenic sources still contribute significantly and 
    anthropogenic sources do not contribute significantly to violation of 
    the PM-10 NAAQS in the area. Since emissions from anthropogenic sources 
    increase with population growth and the location of new sources to the 
    area, the contribution of anthropogenic sources to violations can 
    become significant over time. Therefore, the need for reinstating a 
    specific attainment date and/or previously waived serious area 
    requirements should be reconsidered periodically.
        The EPA has the authority under section 172(c)(3) to require 
    periodic updates of a nonattainment area's emissions inventory to 
    assure that the requirements of part D are met. The EPA plans to use 
    this authority to periodically review the waiver status of areas, as 
    described above. A specific attainment date and applicable requirements 
    should be reinstated if it is determined that nonanthropogenic sources 
    no longer contribute significantly or anthropogenic sources begin 
    contributing significantly to violations in the area.
        6. What requirements applicable to serious nonattainment areas 
    under subpart 4 of part D should be waived?
        The individual subpart 4 requirements (see section IV. above) will 
    be waived only after considering all relevant circumstances on a case-
    by-case basis for serious areas where anthropogenic sources do not 
    contribute significantly and where RACM have been implemented. 
    Currently, the section 189(b)(3) requirement to modify the definitions 
    of ``major source'' and ``major stationary source'' is the only serious 
    area requirement that will not be waived.
    
    D. Waiver Policy Description
    
        Consistent with the discussion above, the EPA intends to implement 
    its authority to grant waivers under section 188(f) in a manner 
    described by the diagram presented in Figure 1. It is important to note 
    that this diagram is provided for illustrative purposes only and should 
    not be interpreted contrary to the policy as it is described in this 
    notice. The figure presents six decision questions. A SIP submitted for 
    a moderate nonattainment area seeking a waiver is expected to address 
    the first three questions:
        1. Can the area attain the NAAQS by the applicable statutory 
    attainment date (December 31, 1994 for the initial nonattainment areas) 
    after implementing RACM (including RACT) for contributing anthropogenic 
    and nonanthropogenic sources?
        If the moderate area SIP demonstrates that the area can attain with 
    RACM (including RACT) by the attainment date, then the answer to this 
    question is ``yes'' and the waiver provisions are not applicable.
    
    BILLING CODE 6560-50-P
    
    TP16AU94.002
    
    
    BILLING CODE 6560-50-C
        If an area cannot attain by the statutory deadline, then questions 
    2 and 3 on the waiver policy diagram must be addressed, and several 
    cases may exist.
        2. Do anthropogenic sources of PM-10 as a whole contribute 
    significantly to violations in the area?
        3. Do nonanthropogenic sources of PM-10 as a whole contribute 
    significantly to violations in the area?
    Case #1
        If anthropogenic sources no longer contribute significantly to 
    violations in the area after the implementation of RACM, then by 
    default, nonanthropogenic sources must contribute significantly.25 
    In this case, the moderate area attainment date may be waived. The 
    practical effect of waiving the attainment date for a moderate area is 
    to relieve it from reclassification as serious and, therefore, to 
    relieve it from certain serious area requirements. Therefore, a 
    moderate area may only qualify for an attainment date waiver if it also 
    qualifies for a waiver of the serious area requirements (see section 
    V.C., question 3). The State should reevaluate the impact of 
    anthropogenic sources on the area periodically to determine whether or 
    not they contribute significantly to violations.
    ---------------------------------------------------------------------------
    
        \2\5It is likely that Congress intended all areas--even those 
    eligible for waivers--to implement whatever measures were reasonably 
    available. Therefore, EPA believes the best reading of the statute 
    requires that the emission reductions attributable to RACM 
    (including RACT) should be considered before evaluating the 
    significance of anthropogenic contributions.
    ---------------------------------------------------------------------------
    
    Case #2
        If anthropogenic sources still contribute significantly to 
    violations in the area after the implementation of RACM (i.e., 
    contribute over 5 g/m3 to PM-10 concentrations), then the area 
    would be reclassified as serious. Consequently, the serious area 
    requirements discussed in section IV, above, would have to be 
    implemented in the area. These requirements include, among other 
    things, the application of BACM (including BACT) on source categories 
    that are still contributing significantly to violations (see the 
    discussion of BACM in section VI and footnote 33).
        Subsequently, the area may qualify for a waiver of the serious area 
    attainment date if it is demonstrated that nonanthropogenic source 
    contributions (i.e., contributions greater than 150 g/m3) 
    would prevent the area from attaining the NAAQS.
    Case #3
        If anthropogenic sources contribute significantly to violations, 
    but, nonanthropogenic sources contribute less than 150 g/m3, 
    then waivers will be granted on a case-by-case basis as discussed above 
    in subsection C., question 4. The eligibility for and timing of serious 
    area attainment date waivers would depend upon the answers to the last 
    three questions on the waiver policy diagram.
        4. Can the serious area attain by the statutory deadline after 
    implementing the serious area control strategy (i.e., BACM, (including 
    BACT)), for significant anthropogenic sources?
        If the State can demonstrate that it is possible to attain the 
    NAAQS by the statutory deadline for serious areas through the 
    implementation of BACM, then a waiver is not appropriate. If attainment 
    by the deadline is not possible, then question 5 must be addressed.
        5. Can the area attain with an extension of up to 5 years of the 
    attainment date?26
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        \2\6The EPA may grant a single extension of the attainment date 
    for serious areas of no more than 5 years under the conditions of 
    section 188(e) of the Act. Guidance on demonstrating that a State 
    qualifies for an attainment date extension will be issued in the 
    future.
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        To answer this question, the State must determine if an extension 
    of time will make it technologically and economically feasible to 
    implement additional control measures that will bring the area into 
    attainment. Again, if it is possible to attain the NAAQS, then a waiver 
    is not appropriate. If attainment is not possible even with the maximum 
    extension of the attainment date allowed under section 188(e), then 
    question 6 must be addressed.
        6. Can the area attain at any time after the extension deadline if 
    emissions within the area are reduced annually by not less than 5 
    percent?27
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        \2\7If an area fails to attain the NAAQS by the end of the 
    extension period, then the State must plan to achieve annual 
    reductions of not less than 5 percent of PM-10 and PM-10 precursor 
    emissions within the area, as reported in the most recent inventory 
    (see section 189(d)).
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        To answer this question, the State must determine if the 
    implementation of additional control measures, annually, would 
    eventually bring the area into attainment. Sufficient additional 
    control measures would need to be implemented to achieve at least 5 
    percent annual reductions in the inventory of PM-10 emissions from 
    anthropogenic sources.
        If EPA believes that it is practicable for an area, where both 
    anthropogenic and nonanthropogenic sources contribute to violations, to 
    attain the NAAQS at any time in the future, a specific attainment date 
    would not be waived. Rather, as discussed previously, the State would 
    be expected to follow the provisions in sections 188 and 189 for 
    attainment date extensions and continued emission reductions until the 
    NAAQS are attained. However, if emissions from anthropogenic sources 
    are reduced to the point that it is no longer technologically or 
    economically feasible to reduce those emissions further, and the area 
    still cannot attain the NAAQS, then EPA may consider waiving the 
    serious area attainment date and appropriate serious area requirements.
    
    VI. Best Available Control Measures
    
        A. Requirement for BACM
        There are two circumstances, as discussed earlier, under which a 
    moderate PM-10 nonattainment area may be reclassified as serious. 
    First, an area may be reclassified whenever EPA determines that the PM-
    10 NAAQS cannot practicably be attained by the statutory attainment 
    date.28 Such a determination may be made before the attainment 
    date if a review of the SIP for an area shows that RACM, including 
    RACT, will not practicably bring the area into attainment or if delays 
    in adopting, submitting, and implementing SIP requirements form a basis 
    for EPA to conclude that an area cannot practicably attain the NAAQS by 
    the statutory attainment date. The second circumstance is when the area 
    is reclassified by operation of law upon a determination by EPA that 
    the area has failed to attain the NAAQS on schedule (see section 
    188(b)).
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        \2\8The statutory attainment date for the initial group of areas 
    designated nonattainment by operation of law upon enactment of the 
    1990 Amendments, under section 107(d)(4), is December 31, 1994.
    ---------------------------------------------------------------------------
    
        Section 189(b) establishes additional control requirements for PM-
    10 nonattainment areas that are reclassified as serious by EPA. Under 
    section 189(b)(1)(B), States must submit SIP revisions which provide 
    for implementation of the BACM for PM-10 emissions in such areas. These 
    SIP revisions must be submitted to EPA within 18 months after an area 
    is reclassified and must assure that the measures are implemented no 
    later than 4 years after the area is reclassified as serious (see 
    section 189(b) (1) and (2)).
        The EPA believes the requirement to implement BACM in serious PM-10 
    nonattainment areas should, in one respect, be interpreted similarly to 
    the comparable requirement to implement RACM in moderate PM-10 
    nonattainment areas. Section 172(c)(1), which applies to all 
    nonattainment areas, states that part D RACM shall include ``such 
    reductions in emissions from existing sources in the area as may be 
    obtained through the adoption, at a minimum, of reasonably available 
    control technology * * *.'' Thus, moderate PM-10 nonattainment area 
    RACM plans, which are submitted to meet the requirements of section 
    189(a)(1)(C), must include provisions ensuring the adoption of RACT 
    (see 57 FR 13540, column 1).
        For moderate PM-10 areas reclassified as serious, the nonattainment 
    control requirements (i.e., RACM) are carried over and elevated to a 
    higher level of stringency (i.e., BACM). So, by analogy, just as RACM 
    includes RACT, in the same way, BACM includes BACT.29 Thus, just 
    as moderate PM-10 SIP revisions when implementing RACM under section 
    189(a)(1)(C) must provide for the adoption of RACT, similarly, PM-10 
    SIP revisions under section 189(b)(1)(B), implementing BACM in serious 
    PM-10 nonattainment areas, must include provisions ensuring the 
    adoption of BACT. This point was explicitly addressed in the House 
    Committee Report: ``Serious areas must include in their submission 
    provisions to require that the best available control measures for the 
    control of PM-10 emissions are implemented no later than 4 years after 
    the area is classified or reclassified as serious. Such provisions must 
    include the application of the best available control technology to 
    existing stationary sources'' (H.R. Rep. No. 490, 101st Cong., 2nd 
    Sess. 266-67 (1990)).
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        \2\9Even without the RACM analogy, the best available 
    technological control measures by their plain terms are a subset of 
    the universe of best available control measures.
    ---------------------------------------------------------------------------
    
        Although section 189(b)(1)(B) requires BACM (including BACT) to be 
    implemented in serious PM-10 nonattainment areas, the Act does not 
    define either BACM or BACT for PM-10 nonattainment purposes. Where a 
    statute is silent or ambiguous with respect to the meaning of a 
    statutory term, the agency is authorized to adopt an interpretation 
    reasonably accommodated to the purpose of the statutory 
    provisions.30 In considering how to interpret the provisions 
    requiring BACM (including BACT) for serious PM-10 nonattainment areas, 
    EPA has looked at several factors: The way in which similar terms have 
    been historically interpreted in other sections or titles of the Act, 
    the ordinary grammatical usage associated with the word ``best,'' and 
    the overall structure and purpose of title I of the statute.
    ---------------------------------------------------------------------------
    
        \3\0Chevron, U.S.A., Inc. v. Natural Resources Defense Council, 
    Inc., 467 U.S. 837, 843-44 (1984).
    ---------------------------------------------------------------------------
    
    B. EPA's Historical Interpretation of Control Technology Terminology
    
        The Act uses several terms to refer to different levels of emission 
    control technology required for existing or new sources: ``reasonable 
    (RACT),'' ``best (BACT),'' and lowest achievable emission rate (LAER). 
    It is helpful to consider EPA's past and current interpretation and 
    implementation of these various control levels in determining the 
    control level appropriate for BACM for serious PM-10 nonattainment 
    areas.
        The term ``reasonably available'' was applied to control measures 
    and control technology required to be implemented at existing sources 
    in nonattainment areas by the 1977 Clean Air Act Amendments (1977 
    Amendments) (42 U.S.C. 7502(c)(1)). At that time, EPA defined RACT as 
    the lowest emission limitation that a particular source is capable of 
    meeting by the application of technology that is reasonably available 
    considering technological and economic feasibility.31 Control 
    measures were determined to be reasonable after considering their 
    energy and environmental impacts and their annualized capital and 
    operating costs. In EPA's view, the cost of using a control measure is 
    considered reasonable if those same costs are borne by other comparable 
    facilities. Since Congress, in the 1990 Amendments, did not modify 
    EPA's interpretations of the RACM and RACT in the earlier 1977 
    Amendments, it can be presumed to have given some endorsement to EPA's 
    definition of the term.
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        \3\1See, for example, 44 FR 53761-53762 (September 17, 1979) and 
    footnote 3 of that notice. Note that EPA's emissions trading policy 
    statement (51 FR 43814 (December 4, 1986)) has clarified that RACT 
    requirements may be satisfied by achieving ``RACT equivalent'' 
    emissions reductions in the aggregate from the full set of existing 
    stationary sources subject to those requirements (see also EPA's 
    proposed economic incentives rule, 58 FR 11110, 11123 (February 23, 
    1993)).
    ---------------------------------------------------------------------------
    
        Congress defined the term ``best available control technology'' in 
    section 169(3) of the 1977 Amendments for use in implementing the 
    requirement to prevent significant deterioration (PSD) of air quality 
    under part C, title I, of that Act. This definition was modified by 
    section 403(d) of the 1990 Amendments. The BACT is currently defined 
    for the PSD program as an emission limitation based on the ``maximum 
    degree of reduction of each pollutant * * * emitted from or which 
    results from any major emitting facility, which the permitting 
    authority, on a case-by-case basis, taking into account energy, 
    environmental, and economic impacts and other costs, determines is 
    achievable for such facility through application of production 
    processes and available methods, systems, and techniques * * * for 
    control of each such pollutant.'' Thus, BACT is to be determined for 
    the PSD program on a case-by-case basis taking into account the energy, 
    environmental, and economic impacts and other costs. Section 169(3) 
    also requires that BACT be at least as stringent as any corresponding 
    new source performance standard (NSPS) or national emission standard 
    for hazardous air pollutants (NESHAP).
        Under the PSD program, BACT applies through preconstruction permits 
    issued to major new and major modified facilities in areas where the 
    air quality is better than the NAAQS (section 165(a)(4) of the Act, 42 
    U.S.C. 7475(a)(4)). In broad overview, BACT is determined by 
    identifying the technologically feasible control measures, from the 
    universe of available control techniques, which yield the maximum 
    degree of emission reduction, after considering the energy, 
    environmental and economic impacts of the technology, and other costs. 
    This may include consideration of the annualized capital and operating 
    costs for the facility. The costs of control for a major new facility 
    or major modification of an existing facility should be considered as a 
    portion of the overall costs of the new facility.
        The term LAER refers to the level of control required for issuing a 
    preconstruction permit to major new or major modified facilities in 
    areas where the air quality is worse than the NAAQS (i.e., 
    nonattainment areas) (section 173(a)(2) of the Act, 42 U.S.C. 
    7503(a)(2)). In broad terms, LAER is defined at section 171(3) of the 
    Act as the more stringent emission rate based on either the most 
    stringent State emission limit or the most stringent emission limit 
    achieved in practice by such class or category of source. Like BACT, 
    the LAER level of control must be at least as stringent as the NSPS 
    applicable to the source. Unlike RACT and BACT, the LAER requirement 
    does not consider energy or cost factors. In general, the costs of 
    achieving LAER in a nonattainment area must be considered as a portion 
    of the overall cost of investing in a major new or major modified 
    facility, as they are with BACT in attainment areas. The EPA believes 
    that it is reasonable to conclude that in selecting the term ``best'' 
    to apply to control measures in PM-10 serious nonattainment areas, 
    Congress likely considered how the term has been interpreted in other 
    sections and titles of the Act. Several other factors (discussed below) 
    support such a conclusion.
    
    C. BACM for Serious PM-10 Nonattainment Areas
    
        A plain-English interpretation of the term ``best'' implies a 
    generally higher standard of performance than one that may be 
    considered ``reasonable.'' In addition, the structural scheme 
    throughout title I of the Act is to require the implementation of 
    increasingly stringent control measures in areas with more serious 
    pollution problems, while providing such areas a longer time to attain 
    the applicable standards. This structural scheme reflects a basic 
    underlying premise of title I. The premise is (1) That more stringent 
    control measures are needed in cases when the current control 
    requirements will be insufficient to bring a particular area into 
    attainment; and (2) that the more serious the air quality problem, the 
    more reasonable it is to require States to implement control measures 
    of greater stringency despite the greater burdens such measures are 
    likely to cause. The Act attempts to balance the greater burden imposed 
    in those areas where more stringent controls are required by affording 
    the State additional time to implement them.
         For example, under section 188(e), EPA is given authority to 
    extend the attainment date for a serious PM-10 nonattainment area 
    beyond the specified statutory date, provided certain conditions are 
    met. One of those conditions is that the State must demonstrate to 
    EPA's satisfaction that ``the plan for that area includes the most 
    stringent measures that are included in the implementation plan of any 
    State or are achieved in practice in any State, and can feasibly be 
    implemented in the area.'' Thus, under this section, the Act provides 
    such areas an opportunity to receive additional time to attain the 
    NAAQS. The consequence of receiving additional time, however, is that 
    the State must demonstrate that its PM-10 implementation plan contains 
    the ``most stringent measures'' that can feasibly be implemented in the 
    relevant area from among those which are either included in any other 
    SIP or have been achieved in practice by any other State.
        Similarly, the Act requires the application of control measures 
    that are ``reasonable'' in moderate PM-10 nonattainment areas (RACM) 
    and control measures that are ``best'' (BACM) whenever a moderate area 
    cannot ``practicably'' attain or fails to attain the NAAQS and is 
    therefore reclassified as serious. Accordingly, for the reasons stated 
    above, EPA believes it is reasonable to conclude that Congress intended 
    a greater level of stringency to apply in areas that are required to 
    implement ``best available'' controls than in those required only to 
    implement controls that are ``reasonably available.''
        As noted earlier, an array of different control measures is 
    applicable under various title I NAAQS-related programs. A key factor, 
    among others, in determining the level of control appropriate for a 
    given area from among the different emission control measures and 
    technologies referred to throughout title I is the severity of the air 
    pollution problem in that area. In addition to the general 
    categorization of areas as ``attainment,'' ``nonattainment,'' and 
    ``unclassifiable,'' the Act characterizes the severity of an area's air 
    pollution problem by classifying the area, for example, as 
    ``marginal,'' ``moderate,'' ``serious,'' and so on. As discussed above, 
    the different control measures are required to be implemented as 
    follows: For new (or modified) sources, BACT applies in PM-10 
    unclassifiable and attainment areas under the PSD program, while LAER 
    applies in moderate and serious PM-10 nonattainment areas under the 
    nonattainment NSR program; for existing sources, RACM (including RACT) 
    applies in moderate PM-10 nonattainment areas, while BACM (including 
    BACT) applies in serious PM-10 nonattainment areas. In each case, the 
    more serious the pollution problem, the more stringent the control 
    standard required.
        It is apparent that in requiring the application of BACM to 
    existing sources in serious PM-10 areas, Congress implied that these 
    sources should be subject to a more stringent level of control than the 
    application of RACM required for existing sources in moderate PM-10 
    nonattainment areas, but not as stringent as the application of LAER 
    required for new or modified sources in moderate and serious 
    nonattainment areas (or the degree of control required to secure an 
    extension under section 188(e)).
    1. Definition
        In view of the preceding discussion, EPA believes that, as a 
    starting point in interpreting BACM for PM-10 nonattainment purposes, 
    it is reasonable to consider the term BACT as applied in the PSD 
    program under section 169(3) as an analogue. Because PSD BACT and PM-10 
    BACM (which includes BACT) are similar terms, EPA believes it is 
    reasonable to accord some interpretive weight to this use of similar 
    language.32
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        \3\2Under accepted principles of statutory interpretation, 
    similar terms in a statute generally suggest a similar meaning, and 
    an agency is permitted, but not required, to give a similar meaning 
    to similar terms which appear in different parts of a statute.
    ---------------------------------------------------------------------------
    
        Therefore, EPA's interpretation of BACM for serious PM-10 
    nonattainment areas will generally be similar to the definition of BACT 
    for the PSD program. The BACM is the maximum degree of emissions 
    reduction of PM-10 and PM-10 precursors from a source (except as 
    provided in subsection C. 3) which is determined on a case-by-case 
    basis, taking into account energy, environmental, and economic impacts 
    and other costs, to be achievable for such source through application 
    of production processes and available methods, systems, and techniques 
    for control of each such pollutant. For PM-10, BACM must be applied to 
    existing source categories in nonattainment areas that cannot 
    practicably attain (or fail to attain) within the moderate area 
    timeframe and are reclassified as serious.33
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        \3\3The term ``source categories'' for which BACM will be 
    required, refers to categories of area-wide sources or large 
    individual stationary sources of PM-10 or PM-10 precursor emissions 
    that may be regulated under a specific rule, generic emission limit, 
    or standard of performance, or a specific control program in a SIP. 
    For example, the SIP may regulate emissions from unpaved roads, 
    construction activities, residential wood combustion, asphalt 
    concrete batch plants, etc., as source categories. Note that, in 
    some instances, an entire source category may consist of one large 
    individual stationary source that is regulated separately under the 
    SIP such as a single iron and steel manufacturing facility and the 
    various processes therein.
    ---------------------------------------------------------------------------
    
        As noted above, EPA will interpret PSD BACT and PM-10 BACM as 
    generally similar because, despite the similarity in terminology, 
    certain key differences exist between control measures applicable in 
    the PSD and PM-10 serious nonattainment area programs. The BACT under 
    the PSD program applies only in areas already meeting the NAAQS, while 
    PM-10 BACM applies in areas which are seriously violating the NAAQS. 
    This difference in policy goals, arguably, suggests that the PM-10 BACM 
    control standard should be more stringent than that for PSD BACT. On 
    the other hand, the burden of installing efficient controls during 
    construction of a new source or source modification is generally less 
    onerous than retrofitting an existing PM-10 source with similar 
    controls. If one compares both programs in terms of these factors, the 
    differing regulatory and economic burdens and the different policy 
    purposes tend to offset each other. Nevertheless, EPA believes that the 
    differences in policy goals--i.e., preventing further pollution under 
    the PSD program and reducing existing pollution under the PM-10 
    nonattainment program--counsel against adopting the interpretation and 
    implementation of PSD BACT in its entirety for PM-10 nonattainment 
    purposes. Rather, EPA considers it reasonable to use the approach 
    adopted in the PSD BACT program as defined in section 169(3) of the Act 
    as an analogue for determining appropriate PM-10 nonattainment control 
    measures in serious areas, while at the same time retaining the 
    discretion to depart from that approach on a case-by-case basis as 
    particular circumstances warrant.
    2. Preventive Measures
        The EPA considers measures that prevent PM-10 emissions over the 
    long term (e.g., requiring gas logs in new fireplaces) to be preferable 
    to those measures that will only temporarily reduce emissions (e.g., 
    curtailment of wood stove use during air pollution episodes or 
    treatment of fugitive dust sources with water). This is because such 
    preventive measures are inherently more effective and involve 
    significantly fewer resources for surveillance, enforcement, and 
    administration. Moreover, increasing emphasis on prevention over 
    mitigation is more likely to be both economically and environmentally 
    beneficial over the long term.
    3. De Minimis Source Categories
        The BACM are required for all categories of sources in serious 
    areas unless the State adequately demonstrates that a particular source 
    category does not contribute significantly to nonattainment of the 
    NAAQS. While EPA regards the BACM standard applicable in PM-10 serious 
    areas as a more stringent control standard which calls for a greater 
    degree of emissions control for the source categories to which it 
    applies, EPA also believes that it has the authority to limit the 
    applicability of BACM to those source categories which ``contribute 
    significantly'' to violations of the NAAQS. The Act leaves unresolved 
    the question of whether BACM is intended to be an all-inclusive 
    requirement applicable to every PM-10 serious area source category. It 
    should be noted that in section 189(b)(1)(B), which contains the 
    requirement that serious area PM-10 SIP's provide for the 
    implementation of BACM, Congress has not used the word ``all'' in 
    conjunction with BACM. Congress has also not stated anywhere in the 
    relevant law or legislative history that BACM must be applied to all 
    serious area source categories. Even if the statute on its face were 
    interpreted to require States to impose BACM on all source categories 
    in serious PM-10 areas, the Agency believes, based on the decision in 
    Alabama Power Co. v. Costle,34 that it has the authority to exempt 
    from regulation those source categories in the area which contribute 
    only negligibly to ambient concentrations which exceed the NAAQS. The 
    EPA believes the court's test for invoking the de minimis exemption 
    authority would be satisfied in circumstances where a State 
    demonstrates conclusively that, because of the small contribution of 
    the source category's emissions to the nonattainment problem, the 
    imposition of additional controls, such as BACM, on a particular source 
    category in the area would not contribute significantly to the Act's 
    purpose of achieving attainment of the NAAQS ``as expeditiously as 
    practicable.'' The EPA will have to determine from the record that, 
    with respect to particular serious area PM-10 source categories which 
    contribute to emissions in excess of the NAAQS, requiring application 
    of BACM would produce an insignificant regulatory benefit.
    ---------------------------------------------------------------------------
    
        \3\4The inherent authority of administrative agencies to exempt 
    de minimis situations from a statutory command has been upheld in 
    contexts where an agency is invoking a de minimis exemption as ``a 
    tool to be used in implementing the legislative design'' on the 
    ground that ``the burdens of regulation yield a gain of trivial or 
    no value'' (Alabama Power Co. v. Costle, 636 F.2d 323, 360-61 (D.C. 
    Cir. 1979)).
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        The EPA will, in general, rely on the criteria applied under new 
    source permitting programs (40 CFR 51.165(b)) to determine when a 
    source category contributes significantly to violations of the NAAQS in 
    a PM-10 serious nonattainment area. The criteria will also be applied 
    spatially and temporally in the same way it is under new source 
    permitting programs.\35\
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        \35\See ``Interpretation of `Significant Contribution,''' 
    memorandum from Richard G. Rhoads to Alexandra Smith, December 16, 
    1980, OAQPS Policy and Guidance Notebook, PN 165-80-12-16-007.
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        As discussed above, a moderate PM-10 nonattainment area may be 
    reclassified as serious based on evidence that the area cannot 
    practicably attain the NAAQS by the statutory attainment date or 
    evidence that it has failed to attain by that date. The evidence, 
    whether modeled or measured, will generally indicate the standard (24-
    hour or annual), the day, and the location of the predicted or 
    monitored violation. Therefore, under this policy, a source category 
    (see footnote 33) will be presumed to contribute significantly to a 
    violation of the 24-hour NAAQS if its PM-10 impact at the location of 
    the expected violation would exceed 5 g/m\3\. Likewise, a 
    source category will be presumed to contribute significantly to a 
    violation of the annual NAAQS if its PM-10 impact at the time and 
    location of the expected violation would exceed 1 g/m\3\.
        Procedures for identifying source categories that continue to 
    significantly affect the air quality of a serious area (even after RACM 
    (including RACT) are implemented) and procedures for identifying the 
    appropriate mix of control measures applicable to those source 
    categories are discussed below in subsection E.
    4. BACM Analysis Independent of Attainment Analysis
        The overall structure and purpose of title I of the amended Act, 
    the standard suggested by the word ``best,'' and the differences in the 
    statute between the requirements for BACM as compared to those for 
    RACM, lead EPA to believe that, unlike RACM, BACM are to be established 
    generally independent of an analysis of the attainment needs of the 
    serious area.
        As noted earlier in this section, the overall structural scheme 
    throughout title I of the Act is to require the implementation of 
    increasingly stringent control measures in areas with more serious 
    pollution problems, while providing such areas additional time to 
    attain the applicable standards. These tougher measures are deemed 
    necessary in cases where it appears that less stringent controls will 
    be insufficient to reduce emissions in an area to the level of the 
    NAAQS. As described above, the fact that the Act requires the 
    application of control measures that are ``reasonable'' in moderate PM-
    10 areas and control measures that are ``best'' whenever it is 
    determined that a moderate area cannot ``practicably'' attain or 
    actually fails to attain the NAAQS and is therefore reclassified as 
    serious, strongly suggests that BACM is intended to be a more stringent 
    standard than RACM. Thus, it is reasonable to interpret the statute as 
    requiring a different analysis for determining BACM from the practice 
    of analyzing RACM according to what is reasonable in light of the 
    overall attainment needs of the area. Moreover, when comparing the 
    terms ``reasonable'' and ``best'' as applied to control measures, the 
    word ``best'' strongly implies that there should be a greater emphasis 
    on the merits of the measure or technology alone and less flexibility 
    in considering other factors.
        Additionally, for PM-10 areas reclassified as serious before the 
    moderate area attainment date, States have up to 4 years, under section 
    189(b)(2), in which to submit their serious area attainment 
    demonstration. However, under section 189(b)(2), States have only 18 
    months after reclassification from moderate to serious to submit their 
    plans requiring the use of BACM for those same areas. Thus, for such 
    areas, Congress provided a difference of as much as 2\1/2\ years 
    between the required date for submitting BACM plans and the date by 
    which to submit a new attainment demonstration satisfying the 
    requirements of section 189(b)(1)(A). This pronounced difference in 
    timing for the serious area submittals described above is to be 
    contrasted with the timing for submittal of similar provisions for 
    moderate areas. Under section 189(a)(2), both the RACM plans and the 
    attainment demonstration for moderate PM-10 areas must as a general 
    matter be submitted at the same time. The fact that the Act requires 
    BACM to be adopted and implemented by an appreciable time before the 
    attainment demonstration is required, for areas that are reclassified 
    before the moderate area attainment date, suggests that Congress 
    intended that BACM determinations be based more on the feasibility of 
    implementing the measures rather than on an analysis of the attainment 
    needs of the area.\36\ Therefore, the steps described below for making 
    a BACM determination are intended to be carried out independently from 
    the analysis to determine the emission reductions that would be 
    necessary to attain the NAAQS by the statutory deadline. If the 
    attainment demonstration for the area subsequently shows that BACM will 
    bring the area into attainment before the statutory deadline, then the 
    plan provides for expeditious attainment of the NAAQS. However, if the 
    BACM are not adequate to provide for attainment of the standards, then 
    the State must submit additional measures with the attainment 
    demonstration that will result in attainment of the standard by the 
    statutory deadline or apply for an extension of the attainment date by 
    demonstrating that the specific conditions of sections 108(e) and 
    189(b)(1)(A)(ii) have been met.
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        \36\The EPA believes this interpretation of the Act is 
    reasonable, even if, as to areas which are classified in the future 
    as serious PM-10 nonattainment areas because the areas have failed 
    to attain, the date BACM plans must be submitted and the date the 
    serious area attainment demonstration is due should happen to 
    coincide. There is no rational basis for interpreting BACM 
    differently depending merely on when an area happens to be 
    reclassified.
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    D. Procedures for Determining Best Available Control Measures
    
    1. Inventory Sources of PM-10 and PM-10 Precursors
        The BACM (including BACT) applicable in a nonattainment area must 
    be determined on a case-by-case basis since the nature and extent of a 
    nonattainment problem may vary within the area and from one area to 
    another. Nonattainment problems range from reasonably well-defined 
    areas of violation caused by a specific source or group of sources to 
    violations over relatively broad geographical areas due predominantly 
    to large numbers of small sources widely-distributed over the area. The 
    BACM are required for all source categories for which the State cannot 
    conclusively demonstrate that their impact is de minimis. As stated 
    above, the EPA will generally presume the contribution to nonattainment 
    of any source category to be de minimis if the source category causes a 
    PM-10 impact in the area of less than 5 g/m\3\ for a 24-hour 
    average and less than 1 g/m\3\ annual mean concentration. The 
    starting point for making a BACM determination would be to reevaluate 
    the emission inventory submitted with the moderate area SIP. Section 
    172(c)(3) of the Act calls for all nonattainment areas to submit 
    comprehensive, accurate, and current emissions inventories and provides 
    for such periodic revisions as may be necessary to assure that the 
    nonattainment planning requirements are met. If there have been any 
    significant changes in PM-10 sources in the area since the inventory 
    was first compiled (i.e., sources permanently shut down or new or 
    modified sources constructed) or if the inventory is not adequate to 
    support the more rigorous analysis required for serious area SIP 
    demonstrations, it should be revised. All anthropogenic sources of PM-
    10 emissions and PM-10 precursors (if applicable)\37\ and 
    nonanthropogenic sources in a nonattainment area must be included in 
    the emission inventory.
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        \37\Ambient filter analysis and inventory information may have 
    been presented in certain moderate area SIP to indicate the 
    insignificance of secondary particles (see 57 FR 13541-42).
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        Because of its importance in identifying anthropogenic and 
    nonanthropogenic sources and the applicability of BACM requirements, 
    the breakdown of sources to consider when compiling an emissions 
    inventory are as follows:
        a. Major point sources (i.e., sources with the potential to emit at 
    least 70 tons per year of PM-10 (or PM-10 precursors) as required in 
    sections 189(b)(3) and 189(e) of the Act).
        b. Minor point source categories.
        c. Area source categories such as fugitive dust from anthropogenic 
    sources (e.g., construction activities, paved and unpaved roads, 
    agricultural activities, etc.), residential wood combustion, prescribed 
    burning, and commercial/institutional fuel combustion.
        d. Nonanthropogenic sources.
    2. Evaluate Source Category Impact
        The second step in determining BACM for an area is to identify 
    those source categories having a greater than de minimis impact on PM-
    10 concentrations. The potential maximum impact of various source 
    categories may have been determined with receptor or dispersion 
    modeling performed for the attainment demonstration submitted with the 
    moderate area SIP. In addition, the impact of some source categories 
    may be apparent from analysis of ambient sampling filters from days 
    when the standards are exceeded. If modeling was not performed during 
    development of the moderate area SIP, receptor modeling, screening 
    modeling or, preferably, refined dispersion modeling will generally be 
    necessary at this time to identify key source categories.
    3. Evaluate Alternative Control Techniques
        In developing a fully adequate BACM SIP, the State is expected to 
    evaluate the technological and economic feasibility of the control 
    measures discussed in the BACM guidance documents\38\ and other 
    relevant materials for all source categories impacting the 
    nonattainment area except those with a de minimis impact considering 
    emission reductions achieved with RACM.
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        \38\See ``Technical Information Document for Residential Wood 
    Combustion Best Available Control Measures,'' EPA-450/2-92-002, 
    September 1992; ``Prescribed Burning Background and Technical 
    Information Document for Best Available Control Measures,'' EPA-450/
    2-92-003, September 1992; and, ``Fugitive Dust Background Document 
    and Technical Information Document for Best Available Control 
    Measures,'' EPA-450/2-92-004, September 1992.
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        Energy and environmental impacts of the control measures and the 
    cost of control should be considered in determining BACM. In general, 
    for the reasons stated above, the test of economic and technological 
    feasibility will be higher for source categories in serious areas than 
    for source categories in moderate areas because of the greater need for 
    emission reductions to attain the NAAQS. As noted earlier, this 
    interpretation is consistent with the overall statutory scheme which 
    requires that as an area's air quality worsens, increasingly stringent 
    control measures are to be adopted in conjunction with the area 
    receiving more time to attain the NAAQS. Thus, measures that were not 
    considered reasonable to implement by the moderate area attainment date 
    may be BACM for serious areas because of the additional time available 
    for implementing them\39\ and because of the higher degree of 
    stringency implied by the statutory scheme and the term ``best.'' 
    Therefore, BACM could include, though it is not limited to, expanded 
    use of some of the same types of control measures as those included as 
    RACM in the moderate area SIP.
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        \39\The statutory attainment date for initial moderate PM-10 
    nonattainment areas reclassified as serious will be December 31, 
    2001. For areas designated nonattainment subsequent to enactment of 
    the 1990 Amendments that become serious, the attainment date will be 
    before the end of the tenth year beginning after the area's 
    designation as nonattainment (see section 188(c)).
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        It does not currently appear that mobile sources, as distinct from 
    the surfaces on which they travel, contribute significantly to the PM-
    10 air quality problem in a sufficient number of areas to warrant 
    issuing national guidance on best available transportation control 
    measures for PM-10 under section 190 of the Act. However, in those 
    areas where mobile sources do contribute significantly to PM-10 
    violations, the State must, at a minimum, address the transportation 
    control measures listed in section 108(f) to determine whether such 
    measures are achievable in the area considering energy, environmental 
    and economic impacts and other costs.
        The technological feasibility of reducing emissions from area 
    sources depends on the ability to alter the characteristics that affect 
    emissions from the sources. Those characteristics have to do with the 
    size or extent of the sources, their physical characteristics and the 
    operating procedures. Reducing emissions of fugitive dust from 
    construction activities, for example, could require the most effective 
    combination of reducing the size of the sources (i.e., acres cleared at 
    one time or vehicle miles traveled on unpaved surfaces), changing the 
    physical characteristics (i.e., silt loading on travel surfaces or 
    moisture content of materials handled), and/or changing the operating 
    practices (i.e., lower vehicle speeds, less surface area exposed to the 
    wind, treating or paving travel surfaces).
        The technological feasibility of applying an emission reduction 
    method to a particular point source should consider the source's 
    process and operating procedures, raw materials, physical plant layout, 
    energy requirements, and any collateral environmental impacts (e.g., 
    water pollution and waste disposal). The process, operating procedures, 
    and raw materials used by a source can affect the feasibility of 
    implementing process changes that reduce emissions and the selection of 
    add-on emission control equipment. The operation and longevity of 
    control equipment can be significantly influenced by the raw materials 
    used and the process to which it is applied. The feasibility of 
    modifying processes or applying control equipment is also influenced by 
    the physical layout of the particular plant. The space available in 
    which to implement such changes may limit the choices and will also 
    affect the costs of control.
    4. Evaluate Costs of Control
        Economic feasibility considers the cost of reducing emissions from 
    a particular source category and costs incurred by similar sources that 
    have implemented emission reductions. As with RACT determinations and 
    BACT/LAER analyses in other statutory contexts, EPA believes that for 
    PM-10 BACM purposes, it is reasonable for similar sources to bear 
    similar costs of emission reduction. As such, when identifying BACM, 
    consideration of economic feasibility should not rely on claims 
    regarding the ability of a particular source to ``afford'' to reduce 
    emissions to the level of similar sources. Otherwise, less efficient 
    sources might be rewarded for their inefficiency by being allowed to 
    bear lower emission reduction costs. Instead, economic feasibility for 
    PM-10 BACM purposes should focus upon evidence that the control 
    technology in question has previously been implemented at other sources 
    in a similar source category without unreasonable economic impacts.
        Where the economic feasibility of a measure (e.g., road paving) 
    depends on public funding, EPA will consider past funding of similar 
    activities as well as availability of funding sources to determine 
    whether a good faith effort is being made to expeditiously implement 
    the available control measures. In other words, if 20 miles of unpaved 
    roads are typically paved each year, then the BACM fugitive dust 
    program should include paving more than 20 miles per year of existing 
    roads and should offer evidence of ambitious efforts to increase 
    funding and increase the priority for use of existing funds.
        The capital costs, annualized costs, and cost effectiveness of an 
    emission reduction technology should be considered in determining its 
    economic feasibility. The ``OAQPS Control Cost Manual, Fourth 
    Edition,'' EPA-450/3-90-006, January 1990, describes procedures for 
    determining these costs. The above costs should be determined for all 
    technologically-feasible emission reduction options.
    
    E. Selection of BACM for Area Sources
    
        Once the significant PM-10 area source categories have been 
    identified, the State should select area source control measures from 
    the candidate BACM listed in the technical information documents for 
    fugitive dust, residential wood combustion (RWC), prescribed burning, 
    or any other technical information documents issued by EPA (see 
    footnote 38). This guidance is based on EPA's analysis of available 
    control alternatives for the identified source categories. While the 
    guidance is intended to be comprehensive, it is by no means exhaustive. 
    Consequently, the State is encouraged to consider other sources of 
    information and is not precluded from selecting other measures and 
    demonstrating to the public and EPA that they constitute BACM. Further, 
    any control measure that a commenter indicates during the public 
    comment period is available for a given area should be reviewed by the 
    planning agency. The agency should determine whether the affected 
    categories of sources are significant and, if so, whether the available 
    measure is achievable in the area considering energy, environmental, 
    and economic impacts and other costs.
        As stated earlier, EPA considers measures that prevent PM-10 
    emissions over the long term to be preferable to short-term curtailment 
    measures. Therefore, when selecting BACM for area sources, a State 
    should first consider pollution preventive measures and measures that 
    provide for long-term sustained progress toward attainment in 
    preference to quick, temporary control. For example, a State should 
    consider requiring the replacement, over time, of old wood stoves with 
    cleaner-burning wood stoves or alternative fuels. Such programs would 
    complement and reduce dependance on wood-burning curtailment programs 
    adopted as RACM for the moderate area SIP. However, EPA recognizes that 
    such long-term measures may entail significant lead time and that 
    temporary measures like wood-burning curtailments may need to be 
    continued in serious areas, at a minimum, to provide interim health 
    protection.
        Once the list of available measures for an area source has been 
    identified, the State must evaluate the technological and economic 
    feasibility of implementing the controls. The State may refer to the 
    technical information documents for procedures to determine 
    feasibility.
        When evaluating economic feasibility, States should not restrict 
    their analysis to simple acceptance/rejection decisions based on 
    whether full application of a measure to all sources in a particular 
    category is feasible. Rather, a State should consider implementing a 
    control measure on a more limited basis, e.g., for a percentage of the 
    sources in a category if it is determined that 100 percent 
    implementation of the measure is infeasible. This would mean, for 
    example, that an area should consider the feasibility of paving 75 
    percent of the unpaved roadways even though paving all of the roads may 
    be infeasible. Alternatively, the State should consider whether 
    measures which cannot feasibly be implemented in their entirety prior 
    to the statutory deadline for BACM implementation could be completed 
    over an extended period. In that event, BACM might itself be defined to 
    change over time from a more limited set of measures at the initial 
    implementation date to a progressively tighter or more ambitious 
    program at later dates.
        The following example is presented to illustrate how a moderate 
    area program of RACM for fugitive dust control may be complemented with 
    additional BACM after the area is reclassified as serious. Assume that 
    the following control measures were adopted as RACM:
        1. Reduce the speed limit on unpaved county roads to 25 miles per 
    hour.
        2. Treat all unpaved county roads, monthly, with chemical dust 
    suppressants within 500 feet of their intersections with paved roads.
        3. Treat 10 miles of the most heavily-traveled, unpaved county 
    roads with chemical dust suppressants once per month.
        4. Pave 4 miles of unpaved city streets.
        5. Treat unpaved parking lots in the city with chemical dust 
    suppressants once per month.
        6. Clean anti-skid materials from 50 miles of city streets within 
    48 hours after snow melt begins.
        The same area, after being reclassified as serious, may adopt the 
    following BACM examples to complement the RACM program:\40\
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        \40\Adoption of these types of measures may require coordination 
    with other local governmental entities such as the Departments of 
    Agriculture, Transportation, and/or the Interior.
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        1. Pave 10 miles of the most heavily-traveled, unpaved county 
    roads.
        2. Treat 10 miles of unpaved county roads with chemical dust 
    suppressants once per month.
        3. Pave 25 unpaved county roads within 500 feet of their 
    intersections with paved roads.
        4. Chemically treat or pave both shoulders of 30 miles of State 
    highways within the county.
        5. Pave all parking lots within the city.
        6. Revise the specifications for winter anti-skid materials to 
    require cleaner, less friable materials, and reduce the quantity used 
    per lane-mile.
        7. Require crop rotations on highly erodible lands.
        8. Retire highly erodible sections of farmland and plant indigenous 
    vegetation as a cover instead of leaving land fallow.
        9. Plant crops and windbreaks across the prevailing wind direction 
    on highly erodible lands.
        In summary, the State must document its selection of BACM by 
    showing what control measures applicable to each source category (not 
    shown to be de minimis) were considered. The control measures selected 
    should preferably be measures that will prevent PM-10 emissions rather 
    than temporarily reduce them. The documentation should compare the 
    control efficiency of technologically-feasible measures, their energy 
    and environmental impacts and the costs of implementation.
    
    F. Selection of BACT for Point Sources
    
        The reviewing authority determines BACT on a case-by-case basis. As 
    described above, EPA would expect the reviewing authority to select an 
    emissions limitation that reflects the maximum degree of emission 
    reduction of each pollutant subject to regulation (PM-10 and/or PM-10 
    precursors), taking into account energy, environmental, and economic 
    impacts and other costs, that it determines is achievable for such 
    facility.
        In light of preceding discussions of BACT and its statutory bases, 
    it is EPA's policy that BACT be determined using the analytical 
    methodology established in the reviewing authority's current PSD 
    program to the extent that it is consistent with guidance contained in 
    this notice. The analytical methodology used should, at a minimum, 
    consider a representative range of available controls (including the 
    most stringent, those capable of meeting standards of performance under 
    40 CFR part 60 or 61, and those identified by commenters during the 
    public comment period). Selection of a particular control system as 
    BACT must be justified by a comparison of the candidate control systems 
    considering energy, environmental, and economic impacts, and other 
    costs, and be supported by the record.
        In addition, if the reviewing authority determines that there is no 
    economically-reasonable or technologically-feasible way to accurately 
    measure the emissions, and hence to impose an enforceable emissions 
    standard, it may require the source to use design, alternative 
    equipment, work practice, or operational standards to reduce emissions 
    of the pollutant to the maximum extent feasible (see, by analogy, 40 
    CFR 52.21(b)(12); 40 CFR 51.166(b)(12)).
        Alternative approaches to reducing emissions of particulate matter 
    including PM-10 are discussed in ``Control Techniques for Particulate 
    Emissions From Stationary Sources'' - Volume I (EPA-450/3-81/005a) and 
    Volume II (EPA-450/3-81-005b), September 1982. The design, operation, 
    and maintenance of general particulate matter control systems such as 
    mechanical collectors, electrostatic precipitators, fabric filters, and 
    wet scrubbers are discussed in Volume I. The collection efficiency of 
    each system is discussed as a function of particle size. Information is 
    also presented regarding energy and environmental considerations and 
    procedures for estimating costs of particulate matter control 
    equipment. The emission characteristics and control technologies 
    applicable to specific source categories are discussed in Volume II. 
    Secondary environmental impacts are also discussed.
        The BACT/LAER Clearinghouse, the EPA Control Technology Center, and 
    past BACT analyses for new and modified major sources under the PSD 
    program may be used to assist in identifying available control options 
    and maximum achievable emission reductions. The EPA will continue to 
    evaluate the need for additional guidance and will produce additional 
    materials as appropriate.
    
    VII. Contingency Measures
    
        Section 172(c)(9) requires that SIP's provide for the 
    implementation of specific measures to be undertaken if the 
    Administrator finds that the nonattainment area has failed to make RFP 
    toward attainment or to attain the primary NAAQS by the applicable 
    statutory deadline. Following the Administrator's finding, the measures 
    are to ``take effect without further action by the State, or the 
    Administrator.'' The EPA interprets this requirement to be that no 
    further rulemaking actions by the State or EPA would be needed to 
    implement the contingency measures (see generally 57 FR 13512 and 
    13543-544). The EPA recognizes that certain actions, such as the 
    notification of sources, modification of permits, etc., would probably 
    be needed before a measure could be implemented effectively. However, 
    States must show that their contingency measures can be implemented 
    with minimal further action on their part and with no additional 
    rulemaking actions such as public hearings or legislative review. After 
    EPA determines that a moderate PM-10 nonattainment area has failed to 
    attain the PM-10 NAAQS, EPA generally expects all actions needed to 
    effect full implementation of the measures to occur within 60 days 
    after EPA notifies the State of the area's failure. The State should 
    ensure that the measures are fully implemented as expeditiously as 
    practicable after they take effect.
        The purpose of contingency measures is to ensure that additional 
    measures beyond or in addition to the required ``core'' control 
    measures (i.e. RACM for moderate areas and BACM for serious areas) 
    immediately take effect when the area fails to make RFP or to attain 
    the PM-10 NAAQS in order to provide interim public health and welfare 
    protection. The protection is considered ``interim'' because the 
    statute often provides for a more formal SIP revision in order to 
    correct, for example, the failure of an area to attain the PM-10 NAAQS 
    (e.g., section 189(b)--serious area plan required upon finding of 
    failure of moderate area to attain the PM-10 NAAQS under 188(b)(2)--and 
    189(d) (plan revisions required upon failure of serious area to attain 
    the PM-10 NAAQS)). Thus, EPA has noted previously that contingency 
    measures should consist of other available control measures not 
    contained in the applicable core control strategy (57 FR 13543). In 
    designing its contingency measures, the State should also take into 
    consideration the potential nature and extent of any attainment 
    shortfall for the area. The magnitude of the effectiveness of the 
    measures should be calculated to achieve the appropriate percentage of 
    the actual emission reductions required by the SIP control strategy to 
    bring about attainment. The EPA has recommended that contingency 
    measures provide the emission reductions equivalent to 1 year's average 
    increment of RFP (see discussion below).
        Once moderate areas are subsequently reclassified as serious, the 
    affected States must ensure that adequate contingency measures, as 
    described above, are in place for such areas. This is explicitly 
    required under the statute. Section 189(b)(1) requires areas 
    reclassified as serious to submit ``an implementation plan.'' Under 
    section 172(c), in turn, ``plan provisions'' required under part D must 
    provide for the implementation of contingency measures. Accordingly, 
    for those moderate areas reclassified as serious, if all or part of the 
    moderate area plan contingency measures become part of the required 
    serious area control measures (i.e., BACM), then additional contingency 
    measures must be submitted whether or not the previously submitted 
    contingency measures had already been implemented. Further, the 
    affected States must ensure that serious areas have adequate 
    contingency measures considering, among other things, new information 
    about the potential attainment shortfall for the newly reclassified 
    serious area. The States must submit contingency measures for serious 
    areas or otherwise demonstrate that adequate measures are in place 
    within 3 years of reclassification.41
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        \4\1The Clean Air Act does not prescribe when States containing 
    serious PM-10 nonattainment areas shall submit section 172(c)(9) 
    contingency measures (or otherwise demonstrate that adequate 
    contingency measures are already in place). However, section 172(b) 
    of the Act directs the Administrator to establish a schedule for 
    submittal of the plan items in section 172(c) at the time the 
    Administrator designates an area as nonattainment. Such schedule is 
    to include a date or dates ``extending no later than 3 years from 
    the date of the nonattainment designation'' (see section 172(b)). By 
    analogy, EPA concludes it is reasonable to establish that the formal 
    deadline for the submittal of section 172(c)(9) contingency measures 
    (or a demonstration that adequate contingency measures are in place) 
    by States containing serious PM-10 nonattainment areas is no later 
    than 3 years from the date of the serious area reclassification (see 
    Chevron, U.S.A., Inc. v. NRDC, 467 U.S. 837, 842-45 (1984)).
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    VIII. Quantitative Milestones and Reasonable Further Progress
    
    A. General Discussion
    
        The PM-10 nonattainment area SIP's must include quantitative 
    milestones which are to be achieved every 3 years until the area is 
    redesignated attainment and which demonstrate RFP toward attainment by 
    the applicable date (see section 189(c) of the amended Act). Section 
    171(1) of the Act defines RFP as ``such annual incremental reductions 
    in emissions of the relevant air pollutant as are required by this part 
    (part D) or may reasonably be required by the Administrator for the 
    purpose of ensuring attainment of the applicable national ambient air 
    quality standard by the applicable date.'' A discussion of these 
    requirements follows.
    
    B. Reasonable Further Progress
    
        Historically, for some pollutants, RFP has been met by showing 
    annual incremental emission reductions sufficient generally to maintain 
    at least linear progress toward attainment by the specified deadline. 
    Requiring linear progress reductions in emissions to maintain RFP may 
    be appropriate in four situations:
        1. When pollutants are emitted by numerous and diverse sources.
        2. Where the relationship between any individual source and the 
    overall air quality is not explicitly quantified.
        3. Where a chemical transformation is involved.
        4. Where the emission reductions necessary to attain the standard 
    are inventory-wide.
        For example, in those areas where the nonattainment problem is 
    attributed to area type sources (e.g., fugitive dust, residential wood 
    combustion, etc.), RFP should be met by showing annual incremental 
    emission reductions sufficient generally to maintain linear progress 
    towards attainment. Total PM-10 emissions should not remain constant or 
    increase from 1 year to the next in such an area.
        Requiring linear progress reductions in emissions to maintain RFP 
    is less appropriate:
        1. Where there are a limited number of sources.
        2. Where the relationships between individual sources and air 
    quality are relatively well defined.
        3. Where the emission control systems utilized (e.g., at major 
    point sources) will result in swift and dramatic emission reductions.
        For example, in those areas where the PM-10 nonattainment problem 
    is attributed to a few stationary sources, RFP should be met by 
    ``adherence to an ambitious compliance schedule''42 which is 
    likely to periodically yield significant emission reductions. Adherence 
    to ``an ambitious compliance schedule'' does not necessarily mean that 
    it would be unreasonable to achieve annual incremental emission 
    reductions or generally linear progress, however.
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        \4\2U.S. EPA, Office of Air Quality Planning and Standards, 
    ``Guidance Document for Correction of Part D SIP's for Nonattainment 
    Areas,'' Research Triangle Park, NC, January 27, 1984, page 25.
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        The SIP's for PM-10 nonattainment areas must include detailed 
    schedules for compliance with emission regulations in the areas and 
    accurately indicate the corresponding annual emission reductions to be 
    realized from each milestone in the schedule. In reviewing the SIP, EPA 
    will determine whether the annual incremental emission reductions to be 
    achieved are reasonable in light of the statutory objective to ensure 
    timely attainment of the PM-10 NAAQS. Additionally, EPA believes that 
    it is appropriate to require early implementation of the most cost-
    effective control measures (e.g., controlling fugitive dust emissions 
    at the stationary source) while phasing in the more expensive control 
    measures, such as those involving the installation of new hardware.
        Section 189(c) provides that the quantitative milestones submitted 
    by a State for an area also must be consistent with RFP for the area. 
    Thus, EPA will determine an area's compliance with RFP in conjunction 
    with determining its compliance with the quantitative milestone 
    requirement. Because RFP is an annual emission reduction requirement 
    and the quantitative milestones are to be achieved every 3 years, when 
    a State demonstrates an area's compliance with the quantitative 
    milestone requirement, it should also demonstrate that RFP has been 
    achieved during each of the relevant 3 years. Thus, the discussion of 
    quantitative milestones below refers to the ``RFP/milestone'' submittal 
    dates, achievement dates and demonstration (or reporting) requirements.
    
    C. Quantitative Milestones
    
    1. Nature of Quantitative Milestones
        As mentioned above, PM-10 nonattainment SIP's are to contain 
    quantitative milestones (see section 189(c)). These quantitative 
    milestones should consist of elements which allow progress to be 
    quantified or measured. Specifically, States should identify and submit 
    quantitative milestones providing for the amount of emission reductions 
    adequate to achieve the NAAQS by the applicable attainment date. The 
    following are examples of measures which support and demonstrate how 
    the overall quantitative milestones identified for an area may be met:
        a. Percent implementation of various control strategies (e.g., pave 
    50 percent of culpable streets, replace 75 percent of residential wood 
    heaters with natural gas heating units).
        b. Percent compliance with implemented control measures.
        c. Adherence to a compliance schedule.
    2. RFP/Milestone Due Dates
        As mentioned above, PM-10 nonattainment SIP's are to contain 
    quantitative milestones which are to be achieved every 3 years until 
    the area is redesignated attainment. There is a gap in the law in that 
    the text of section 189(c) does not articulate the starting point for 
    counting the 3-year period. The EPA believes it is reasonable to begin 
    counting the 3-year milestone deadline from the due date (and not the 
    submittal date) for the applicable moderate area implementation plan 
    revision (see section III.C.1.(f) of the General Preamble (57 FR 13539) 
    for an explanation of why EPA believes it is appropriate to begin 
    counting the 3-year milestone deadline from the SIP due date).
        The first ``RFP/milestone'' achievement date for those areas 
    initially designated as nonattainment for PM-10 by operation of law 
    when the Act was amended will be the moderate area attainment date of 
    December 31, 1994, as stated in section III.C.1.f. of the General 
    Preamble (57 FR 13539). The RFP/milestone achievement date would 
    normally be November 15, 1994, 3 years after the SIP due date of 
    November 15, 1991. The achievement date was delayed 46 days, however, 
    because the de minimis timing differential between the attainment date 
    and the literal first milestone date made it administratively 
    impracticable and of trivial value to require separate milestones and 
    attainment demonstrations for these areas. Thus, for these initial 
    areas that demonstrate timely attainment, EPA's policy is to deem the 
    emission reductions progress made between the SIP submittal due date 
    and the attainment date as sufficient to satisfy the first milestone 
    requirement (57 FR 13539).
        Thus the initial RFP/milestone will be met by showing that emission 
    reductions scheduled to be made between the SIP due date and the 
    attainment date for these moderate areas were actually achieved. Most 
    of the emission reductions will result from implementation of RACM 
    (including RACT) adopted as part of the moderate area SIP. The Act 
    requires that RACM be implemented by December 10, 1993 in the initial 
    PM-10 nonattainment areas (see section 189(a)).
        Subsequent RFP/milestones for these initial PM-10 nonattainment 
    areas that are reclassified as serious will be due every 3 years after 
    the original due date for the moderate area SIP.43 Therefore, the 
    second RFP/milestone for the initial nonattainment areas that are 
    reclassified as serious must be achieved by November 15, 1997. The 
    third RFP/milestone achievement date will be November 15, 2000, etc. 
    These RFP/milestones should be addressed by quantifying and comparing 
    the annual incremental emission reductions which result from 
    implementation of BACM/BACT (required within 4 years after the area is 
    reclassified as serious) and from additional measures included in the 
    final serious area SIP to those reductions which were identified in the 
    SIP as quantitative milestones necessary to achieve the NAAQS by the 
    applicable attainment date. The annual incremental emission reductions 
    must be sufficient to assure attainment as expeditiously as practicable 
    but not later than December 31, 2001. In some cases it may also be 
    appropriate to require that the annual incremental emission reductions 
    maintain at least linear progress toward attainment, as discussed 
    earlier.
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        \4\3The plain terms of section 189(c) require that milestones be 
    achieved ``every 3 years until the area is redesignated attainment'' 
    and, therefore, do not contemplate any breaks in the milestones due 
    to an area's reclassification. Further, reclassifying an area to 
    serious does not obviate the State from controls and emission 
    reductions required in the moderate area implementation plan (see 
    section 189(b)(1)). A continuous series of control measures must be 
    implemented in PM-10 nonattainment areas beginning with RACM 
    (including RACT) and followed by contingency measures which are to 
    be implemented if the moderate area fails to attain. Next, BACM 
    (including BACT) must be implemented within 4 years after the area 
    is reclassified as serious. Subsequently, it may be necessary to 
    implement additional control measures beyond BACM/BACT to attain the 
    NAAQS. Therefore, the structure of the Act requires a series of 
    measures which can provide for RFP/milestones.
    ---------------------------------------------------------------------------
    
    3. RFP/Milestone Report
        The State must demonstrate to EPA, within 90 days after the 
    milestone achievement date, that the SIP measures are being implemented 
    and the RFP/quantitative milestones have been met (see section 
    189(c)(2)). The RFP/milestone report must be submitted from the 
    Governor or Governor's designee to the Regional Administrator of the 
    respective EPA Regional Office which serves the State where the 
    affected area is located.
        The RFP/milestone report must contain technical support sufficient 
    to document completion statistics for appropriate milestones. For 
    example, the demonstration should graphically display RFP over the 
    course of the relevant 3 years and indicate how the emission reductions 
    achieved to date compare to those required or scheduled to meet RFP and 
    the required milestones. The calculations (and any assumptions made) 
    necessary to determine the emission reductions to date should also be 
    submitted. The demonstration should also contain an evaluation of 
    whether the PM-10 NAAQS will be attained by the projected attainment 
    date in the SIP, i.e., answer the question ``Are the emission 
    reductions to date sufficient to ensure timely attainment?''
        Within 90 days of its receipt, EPA must determine whether or not 
    the State's demonstration is adequate and meets all the requirements 
    discussed above. The EPA will notify the State of its determination by 
    sending a letter to the appropriate Governor or Governor's designee.
    4. Failure to Submit RFP/Milestone Report or Meet RFP/Milestones
        If a State fails to submit the RFP/milestone report within the 
    required timeframes or if EPA determines that the State has not met any 
    applicable RFP/milestone, EPA shall require the State, within 9 months 
    after such failure or determination, to submit a plan revision that 
    assures that the State will achieve the next milestone (or attain the 
    PM-10 NAAQS, if there is no next milestone) by the applicable date (see 
    section 189(c)(3)). For example, with respect to RFP, if the required 
    annual emission reductions are not achieved for the relevant years 
    according to the RFP schedule and the implementing milestone 
    requirement, EPA will require the State to submit a SIP revision so 
    that these deviations can be corrected and attainment assured by the 
    applicable date. This would also necessitate implementation of 
    appropriate contingency measures pursuant to section 172(c)(9).
        Note also that failure to meet RFP, if not expeditiously corrected, 
    could also result in the application of sanctions as described in 
    sections 110(m) and 179(b) of the amended Act (pursuant to a finding 
    under section 179(a)(4)).
    
    IX. Other Requirements
    
    A. Executive Order 12866
    
        Under Executive Order 12866 (E.O. 12866) (58 FR 51,735 (October 4, 
    1993)), the Agency must determine whether the regulatory action is 
    ``significant'' and therefore subject to the Office of Management and 
    Budget (OMB) review and the requirements of E.O. 12866. The E.O. 12866 
    defines ``significant regulatory action'' as one that is likely to 
    result in a rule that may:
        1. Have an annual effect on the economy of $100 million or more or 
    adversely affect in a material way the economy, a sector of the 
    economy, productivity, competition, jobs, the environment, public 
    health or safety, or state, local, or tribal government or communities;
        2. create a serious inconsistency or otherwise interfere with an 
    action taken or planned by another agency;
        3. materially alter the budgetary impact of entitlements, grants, 
    user fees, or loan programs or the rights and obligations of recipients 
    thereof; or
        4. raise novel legal or policy issues arising out of legal 
    mandates, the President's priorities, or the principles set forth in 
    the Executive Order.
        Pursuant to the terms of E.O. 12866, OMB has notified EPA that this 
    action is a ``significant regulatory action'' within the meaning of the 
    Executive Order. For this reason, this action was submitted to OMB for 
    review. Changes made in response to OMB suggestions or recommendations 
    will be documented in the public record.
    
    B. Regulatory Flexibility Act
    
        Whenever the Agency is required by section 553 of the 
    Administrative Procedure Act (APA) or any other law to publish general 
    notice of proposed rulemaking for any proposed rule, the Agency shall 
    propose and make available for public comment an initial regulatory 
    flexibility analysis. The regulatory flexibility requirements do not 
    apply for this PM-10 serious area addendum to the General Preamble 
    because it is not a regulatory action in the context of the APA or the 
    Regulatory Flexibility Act.
    
        Dated: July 29, 1994.
    Carol M. Browner,
    Administrator.
    [FR Doc. 94-19884 Filed 8-15-94; 8:45 am]
    BILLING CODE 6560-50-P