[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.
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    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.
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    \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.
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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.
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    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.
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    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).
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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)).
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    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.
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    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.
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    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.
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    \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.
---------------------------------------------------------------------------

    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.
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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