[Federal Register Volume 59, Number 157 (Tuesday, August 16, 1994)]

[Unknown Section]

[Page 0]

From the Federal Register Online via the Government Printing Office 

[www.gpo.gov]

[FR Doc No: 94-1]

[[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 PM10 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-bycase 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 caseby-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 PM10 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 PM10 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.

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 \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 PM10 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 PM10 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 PM10 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.

---------------------------------------------------------------------------

 \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 PM10 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\

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

---------------------------------------------------------------------------

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.

---------------------------------------------------------------------------

 \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.

---------------------------------------------------------------------------

 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 costeffective control measures (e.g., controlling fugitive dust emissions 

at the stationary source) while phasing in the more expensive control 

measures, such as those involving the installation of new hardware.

 Section 189(c) provides that the quantitative milestones submitted 

by a State for an area also must be consistent with RFP for the area. 
Thus, EPA will determine an area's compliance with RFP in conjunction 

with determining its compliance with the quantitative milestone 

requirement. Because RFP is an annual emission reduction requirement 

and the quantitative milestones are to be achieved every 3 years, when 

a State demonstrates an area's compliance with the quantitative 

milestone requirement, it should also demonstrate that RFP has been 

achieved during each of the relevant 3 years. Thus, the discussion of 

quantitative milestones below refers to the ``RFP/milestone'' submittal 

dates, achievement dates and demonstration (or reporting) requirements.

C. Quantitative Milestones

1. Nature of Quantitative Milestones

 As mentioned above, PM-10 nonattainment SIP's are to contain 

quantitative milestones (see section 189(c)). These quantitative 

milestones should consist of elements which allow progress to be 

quantified or measured. Specifically, States should identify and submit 

quantitative milestones providing for the amount of emission reductions 

adequate to achieve the NAAQS by the applicable attainment date. The 

following are examples of measures which support and demonstrate how 

the overall quantitative milestones identified for an area may be met:

 a. Percent implementation of various control strategies (e.g., pave 

50 percent of culpable streets, replace 75 percent of residential wood 

heaters with natural gas heating units).

 b. Percent compliance with implemented control measures.

 c. Adherence to a compliance schedule.

2. RFP/Milestone Due Dates

 As mentioned above, PM-10 nonattainment SIP's are to contain 

quantitative milestones which are to be achieved every 3 years until 

the area is redesignated attainment. There is a gap in the law in that 

the text of section 189(c) does not articulate the starting point for 

counting the 3-year period. The EPA believes it is reasonable to begin 

counting the 3-year milestone deadline from the due date (and not the 

submittal date) for the applicable moderate area implementation plan 

revision (see section III.C.1.(f) of the General Preamble (57 FR 13539) 

for an explanation of why EPA believes it is appropriate to begin 

counting the 3-year milestone deadline from the SIP due date).

 The first ``RFP/milestone'' achievement date for those areas 

initially designated as nonattainment for PM-10 by operation of law 

when the Act was amended will be the moderate area attainment date of 

December 31, 1994, as stated in section III.C.1.f. of the General 

Preamble (57 FR 13539). The RFP/milestone achievement date would 

normally be November 15, 1994, 3 years after the SIP due date of 

November 15, 1991. The achievement date was delayed 46 days, however, 

because the de minimis timing differential between the attainment date 

and the literal first milestone date made it administratively 

impracticable and of trivial value to require separate milestones and 

attainment demonstrations for these areas. Thus, for these initial 

areas that demonstrate timely attainment, EPA's policy is to deem the 

emission reductions progress made between the SIP submittal due date 

and the attainment date as sufficient to satisfy the first milestone 

requirement (57 FR 13539).

 Thus the initial RFP/milestone will be met by showing that emission 

reductions scheduled to be made between the SIP due date and the 

attainment date for these moderate areas were actually achieved. Most 

of the emission reductions will result from implementation of RACM 

(including RACT) adopted as part of the moderate area SIP. The Act 
requires that RACM be implemented by December 10, 1993 in the initial 

PM-10 nonattainment areas (see section 189(a)).

 Subsequent RFP/milestones for these initial PM-10 nonattainment 

areas that are reclassified as serious will be due every 3 years after 

the original due date for the moderate area SIP.43 Therefore, the 

second RFP/milestone for the initial nonattainment areas that are 

reclassified as serious must be achieved by November 15, 1997. The 

third RFP/milestone achievement date will be November 15, 2000, etc. 

These RFP/milestones should be addressed by quantifying and comparing 

the annual incremental emission reductions which result from 

implementation of BACM/BACT (required within 4 years after the area is 

reclassified as serious) and from additional measures included in the 

final serious area SIP to those reductions which were identified in the 

SIP as quantitative milestones necessary to achieve the NAAQS by the 

applicable attainment date. The annual incremental emission reductions 

must be sufficient to assure attainment as expeditiously as practicable 

but not later than December 31, 2001. In some cases it may also be 

appropriate to require that the annual incremental emission reductions 

maintain at least linear progress toward attainment, as discussed 

earlier.

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 \4\3The plain terms of section 189(c) require that milestones be 

achieved ``every 3 years until the area is redesignated attainment'' 

and, therefore, do not contemplate any breaks in the milestones due 

to an area's reclassification. Further, reclassifying an area to 

serious does not obviate the State from controls and emission 

reductions required in the moderate area implementation plan (see 

section 189(b)(1)). A continuous series of control measures must be 

implemented in PM-10 nonattainment areas beginning with RACM 

(including RACT) and followed by contingency measures which are to 

be implemented if the moderate area fails to attain. Next, BACM 

(including BACT) must be implemented within 4 years after the area 

is reclassified as serious. Subsequently, it may be necessary to 

implement additional control measures beyond BACM/BACT to attain the 

NAAQS. Therefore, the structure of the Act requires a series of 

measures which can provide for RFP/milestones.

---------------------------------------------------------------------------

3. RFP/Milestone Report

 The State must demonstrate to EPA, within 90 days after the 

milestone achievement date, that the SIP measures are being implemented 

and the RFP/quantitative milestones have been met (see section 

189(c)(2)). The RFP/milestone report must be submitted from the 

Governor or Governor's designee to the Regional Administrator of the 

respective EPA Regional Office which serves the State where the 

affected area is located.

 The RFP/milestone report must contain technical support sufficient 

to document completion statistics for appropriate milestones. For 

example, the demonstration should graphically display RFP over the 

course of the relevant 3 years and indicate how the emission reductions 

achieved to date compare to those required or scheduled to meet RFP and 

the required milestones. The calculations (and any assumptions made) 

necessary to determine the emission reductions to date should also be 

submitted. The demonstration should also contain an evaluation of 

whether the PM-10 NAAQS will be attained by the projected attainment 

date in the SIP, i.e., answer the question ``Are the emission 
reductions to date sufficient to ensure timely attainment?''

 Within 90 days of its receipt, EPA must determine whether or not 

the State's demonstration is adequate and meets all the requirements 

discussed above. The EPA will notify the State of its determination by 

sending a letter to the appropriate Governor or Governor's designee.

4. Failure to Submit RFP/Milestone Report or Meet RFP/Milestones

 If a State fails to submit the RFP/milestone report within the 

required timeframes or if EPA determines that the State has not met any 

applicable RFP/milestone, EPA shall require the State, within 9 months 

after such failure or determination, to submit a plan revision that 

assures that the State will achieve the next milestone (or attain the 

PM-10 NAAQS, if there is no next milestone) by the applicable date (see 

section 189(c)(3)). For example, with respect to RFP, if the required 

annual emission reductions are not achieved for the relevant years 

according to the RFP schedule and the implementing milestone 

requirement, EPA will require the State to submit a SIP revision so 

that these deviations can be corrected and attainment assured by the 

applicable date. This would also necessitate implementation of 

appropriate contingency measures pursuant to section 172(c)(9).

 Note also that failure to meet RFP, if not expeditiously corrected, 

could also result in the application of sanctions as described in 

sections 110(m) and 179(b) of the amended Act (pursuant to a finding 

under section 179(a)(4)).

IX. Other Requirements

A. Executive Order 12866

 Under Executive Order 12866 (E.O. 12866) (58 FR 51,735 (October 4, 

1993)), the Agency must determine whether the regulatory action is 

``significant'' and therefore subject to the Office of Management and 

Budget (OMB) review and the requirements of E.O. 12866. The E.O. 12866 

defines ``significant regulatory action'' as one that is likely to 

result in a rule that may:

 1. Have an annual effect on the economy of $100 million or more or 

adversely affect in a material way the economy, a sector of the 

economy, productivity, competition, jobs, the environment, public 

health or safety, or state, local, or tribal government or communities;

 2. create a serious inconsistency or otherwise interfere with an 

action taken or planned by another agency;

 3. materially alter the budgetary impact of entitlements, grants, 

user fees, or loan programs or the rights and obligations of recipients 

thereof; or

 4. raise novel legal or policy issues arising out of legal 

mandates, the President's priorities, or the principles set forth in 

the Executive Order.

 Pursuant to the terms of E.O. 12866, OMB has notified EPA that this 

action is a ``significant regulatory action'' within the meaning of the 

Executive Order. For this reason, this action was submitted to OMB for 

review. Changes made in response to OMB suggestions or recommendations 

will be documented in the public record.

B. Regulatory Flexibility Act

 Whenever the Agency is required by section 553 of the 

Administrative Procedure Act (APA) or any other law to publish general 

notice of proposed rulemaking for any proposed rule, the Agency shall 
propose and make available for public comment an initial regulatory 

flexibility analysis. The regulatory flexibility requirements do not 

apply for this PM-10 serious area addendum to the General Preamble 

because it is not a regulatory action in the context of the APA or the 

Regulatory Flexibility Act.

 Dated: July 29, 1994.

Carol M. Browner,

Administrator.

[FR Doc. 94-19884 Filed 8-15-94; 8:45 am]

BILLING CODE 6560-50-P