### Federal Register / Vol. 59, No. 157 / Tuesday, August 16, 1994 / Proposed Rules

A review ofthe environmental effect ofthe proposed measurement rule changes concludes that the proposed change will not have a significant effect

on the quality ofthe human environment. An environmental impact
statement is not required under the National Environmental Policy Act of 1969.

Finally, theAdministrator ofthe Panama Canal Commission certifies that these proposed regulations meet the applicable standards provided in sections 2(a) and 2(b)(2) ofExecutive Order No. 12778.

List ofSubjects in 35Part 103

Advance reservations, Booking system, Order oftransit, Panama Canal, Vessels.

Accordingly, for the reasons set forth above, it is proposed that 35 CFR part 103 be amended as follows:

PART 103-GENERAL PROVISIONS GOVERNING VESSELS

1. The authority citation for part 103 isrevised to read as follows:

Authority:22 U.S.C. 3791, E.O. 12215, 45 FR 36043, 3CFR, 1981 Comp., p. 257.

2. Paragraph (e) of § 103.8 is revised
to read as follows: § 103.8 Preference in thetransitschedule; order of transitingvessels.

(e) Booking Fees. (1) For vessels measured in accordance with § 135.13(a) ofthis chapter, the fee for booking shall be $0.26 per PC/UMS Net Ton. (2) For vessels subject to the transitional reliefmeasures of § 135.31 of this chapter and measured in accordance with § 135.13(b) ofthis chapter, the fee forbooking shallbe $0.23 per Panama Canal Gross Ton as specified on the last certificate issued by the Panama Canal Commission between March 23, 1976 and September 30, 1994, inclusive.

(3) The minimum booking fee for any vesselis $1,500.

(Existingcollections ofinformation are approved under Office ofManagement and Budget (OMB) control number 3207-0001. Modifications are being submitted to OMB for approval.)

Dated: August 10, 1994. Gilberto Guaidia F., Administrator, PanamaCanalCommission.
IFR Doc.94-20049 Filed 8-15-94; 8:45 amI

BILLING CODE 3640-04-P 

### ENVIRONMENTAL PROTECTION
ENVIRONMENTAL PROTECTION
AGENCY

40 CFR Part 52
[FRL-6052-2]

State Implementation Plans forSerious PM-10 Nonattainment Areas, and Attainment Date Waivers for PM-10 Nonattainment Areas Generally; Addendum tothe General Preamble for the Implementation of Title Iof the Clean AirActAmendments of 1990

AGENCY: Environmental Protection Agency (EPA). ACTION: Addendum to General Preamble for future proposed rulemakings.

SUMMARY: This addendum to the General Preamble for the Implementation ofTitle I ofthe Clean Air Act Amendments of 1990 principally describes EPA's preliminary views on how the Agency should interpret various provisions oftitle I with regard to requirements for PM-10 (particles with an aerodynamic diameter less than orequal 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

areasthat have been designated nonattainment for PM-10, waivers of certain requirements applicable to PM10 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 amatter oflaw.

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 ofAirQuality 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. A92-23. 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 ofContents

1.

Introduction i. Designations and Classifications

A. Designations B.Classifications C. Reclassifications D.Appendix KandWaivers Ill. International Border Areas

A.Statutory Requirement B.Policy IV.Serious Area SIPRequirements V. Waivers forCertain PM-10 Nonattainment

Areas A. Historical Perspectives B.Waiver Provisions C.Application ofWaiver 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 ofBACM for Area Sources F.Selection ofBest 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 1CFR 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, a" well as policy and guidance on waivers of certain other requirements applicablr
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-la are classified

as moderate areas (see section 188(a) of the Clean AirAct (Act)).' Subsequently.

'The 1990 Amendments to the Clean Air Act made significant changes to the air quality planning requirements forareas that do not meet (or that significantly contribute toambient airquality in a nearbyarea that does not meet)the PM-10 national ambient airquality 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. etseq. 

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in accordance with section 188(b) ofthe Act, "The Administrator may reclassify

as a serious PM-10 nonattainment area * * *any area that the Administrator 

### determines cannotpracticably 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 toreclassify 5 moderate areasthat were initially designated asnonattainrnent forPM-10
upon enactment ofthe 1990 Amendments (see 58FR 3334).The EPA is considering reclassifying additional

areas from moderate to serious.

Thisguidance document isbeing published asan addendum to the General Preamble forthe Implementation ofTitleI ofthe Clean Air ActAmendments 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 oftitle Iwith regard to requirements for PM-10 serious area SIP's. Although the guidance includes various statements that States musttake certain actions, these statements are made pursuant toEPA's preliminary interpretations, and thus donot bind the States and the public asa matter oflaw. Of course, the use ofprescriptive language is appropriate in those instances where thepolicy is simply reiterating statutory mandates which provide that Statesmust take certain actions.

Possible approaches to implementing the provisions in section 179B applicable tointernational border areas, general SIP requirements of section 172(c), the specific requirements in subpart 4 ofpart D oftitleI in serious PM-10 nonattainment areas, the issues involved and themeans ofresolving those issues are discussed in the following sections. The topics discussed include SIPrequirements such as provisions to assure that best available control measures (BACM)are implemented; waivers forareas impacted bynonanthropogenic sources; treatment ofinternational border areas; requirements for quantitative milestones, reasonable further progress (RFP) and contingency measures.

2A supplemental notice was published at 57FR 18070, April28. 1992, which provides certain appendices tothe April 16, 1992 General Preamble. Subsequent references in this notice to the General Preamble areinclusive ofboth documents. 

### II. Designations and Classifications
A. Designations

Section 107(d) ofthe Act provides generally forthe designation ofareas of each State asattainment, nonattainment

orunclassifiable for each pollutant for whichthere is a national ambient air quality standard (NAAQS), Certain areas meetingthe qualifications ofsection 107(d)(4)(B) ofthe Act were designated nonattainment forPM-10 by operation oflaw upon enactment ofthe 1990 Amendments (initial PM-10 nonattainment areas). AFederal Register notice announcing all ofthe

areas designated nonattainment forPM10 at enactment andclassified as moderate was published onMarch 15, 1991 (56 FR 11101). A follow-up notice 

### correcting some ofthese area designations was published August 8, 1991 (56FR 37654). The nonattainment

areas were formally codified in40 CFR part 81, effective January 6, 1992 (56FR 56694, November 6, 1991). All those

areas ofthe country notdesignated nonattainment forPM-10 at enactment

were designated unclassifiable (see section 107(d)(4)(B)(iii) ofthe Act).

B. Classifications

Once an area is designated nonattainment, section 188 ofthe Act outlines theprocess for classification of the area and establishes the area's attainment date. In accordance with section 188(a), all PM-Ia nonattainment

areas areinitially classified asmoderate * by operation oflaw upon their designation asnonattainment.
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 atany time the Administrator determines the

area cannot practicably attain the NAAQS by the statutory attainment date for moderate areas. 3 

### Second, under section 188(b)(2)a moderate area isreclassified asserious by operation oflaw afterthe statutory attainment date has passedifthe Administrator finds that the area has not attained the NAAQS. The EPA must publish a Federal Register notice identifying theareas that have failed to attain and werereclassified, within 6

3The EPA's interpretation ofthe reclassification provisions in section 188(b)(I) is discussed in detail in section lIl.C.i(b) ofthe General Preamble (57FR at 13537-38). 

### months following the attainment date (see section 188(b)(2)(B)). !
2. Reclassification ofInitialPM-10 Nonattainment Areas

Section 188(b)(1)(A) provides an accelerated schedule by which EPA is to reclassify appropriate initialPM-10 nonattainment areas. The EPAproposed

on November 21, 1991 (56 FR 58656) to reclassify 14 ofthe 70 initial moderate

areas as serious. The 14 areasEPA proposed to reclassify were identified largely based on the magnitude and frequency ofambient PM-10 measurements above the 24-hour NAAQS of150 micrograms per cubic meter (gg/m 3

### )during calendar years 1988-1990. The EPA took final action

onJanuary 8, 1993 (58 FR 3334)to reclassify 5 ofthe 14 areas. The final decision to reclassify the 5 areas was based on the criteria utilized in the proposal, comments received in responseto theproposal and onEPA's preliminary review ofthe SIP's forthe

areas.

In'the future, EPA anticipates that, generally, any decision toreclassify an initial PM-IO nonattainment areabefore the attainment datewillbe based on specific facts or circumstances demonstrating that the NAAQS cannot practicably be attained inthe areaby December 31, 1994 (the statutory attainment date specified in section 188(c)(1) for initialPM-10 nonattainment areas).
3. Reclassification ofFuture PM-10 Nonattainment Areas

Section 188(b)(1)(B) provides a timeframe within whichEPA is to reclassify appropriate areas designated nonattainment forPM-10 subsequent to enactment ofthe 1990 Amendments. Appropriate areas are tobe reclassified

as serious within 18 months after the required date forthe State's submission ofa moderate area PM-10 SIP.4 The 

### statute requires that these moderate area PM-10 SIP'sbe submitted within 18 months afterthe area is designated nonattainment (see section 189(a)(2)(B)). Takingthese provisions together, the statute thus requires that EPA reclassify appropriate PM-l0 moderate areas -designatednonattainment after 1990 as serious within 3 years ofsuch designation.

Because the moderate area SIP's are due before thisreclassification deadline, EPA anticipates that any determination that such areas shouldbe reclassified will bebased upon facts contained in

4This directive does not restrict EPA's general authority, but simply specifiesthat itisto be exercised, as appropriate, in accordance with certain dates. 

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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 whicha SIP has not been submitted whenever itbecomes apparent (e.g.,because ofan extensive delay in submitting the SIP)that an area cannot practicably attain the standards • by theapplicable attainment date.The EPA may also determine that an area cannot practicably attain the standards by the applicable date when the State submitsan 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 notbelieve that generally reclassifying moderate areas as seriousrewards areas which delay development and implementation of PM-10 control measures. Rather, EPA believes its policy creates an incentive forthe timely submittal andeffective implementation ofmoderate area SIP requirements and facilitates the PM-10 attainment objective. Forexample, if an
area that fails to submit a timely moderate area SIPisreclassified, 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 Statehad failed to submit a PM-10 SIP and the area could be subject to sanctions under sections 110(m) and 179 forits delay. As provided under section 179(a) ofthe Act, States containing areas for which EPA has made such determinations haveup to 18 months from EPA's determination to submit acomplete plan orplan revision before EPA isrequired to impose either thehighway funding sanction or the requirement to provide two-to-one new
source offsetsdescribed in section 179(b). Ifthe deficiency has notbeen corrected 6 months after the first sanction applies, then the second sanction must apply. 5

### The EPA's determination alsotriggers a requirement forEPA to impose a Federal implementation plan under section 110(c)(1) ofthe Act. In conjunction with the possible imposition ofsanctions, EPA may issue

a determination to reclassify the area to serious.
D.AppendixKandWaivers

Appendix K to40 CFR part 50 provides guidance on the interpretation ofambient air quality data to determine the air quality statusof an area.

See 58 FR51270 (October 1. 1993). Appendix Kand accompanying guidance (both preceding the 1990 Amendments to the Act) provide in part that measured exceedances ofthe PM10 NAAQS which are believed to be influenced by uncontrollable events caused by natural sources ofparticulate
matter or by events that are not expected
to recur at a given location are flagged and excluded from decisions as to whether ornot 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.

The savings provision ofsection 193 ofthe amended Act provides, among other things, that regulations and guidance promulgated orissued by the Administrator prior to enactment ofthe 1990 Amendments are to remain in effect according to their terms except to the extent that they are inconsistent with any provision ofthe amended Act.' Section 188(f) ofthe amended Act provides EPAwith the discretionary authority to waive a specific date of attainment for a PM-l0 nonattainment

area where it is determined that nonanthropogenic sources contribute significantly to the violation of the standard inthe area, and to waive certain nonattainment area SIP requirements where he Administrator determines that anthropogenic sources ofPM-10 do not contribute significantly
to the violation ofthe standard in the

area. These provisions take as a fundamental premise that areas experiencing violations ofthe NAAQS due to nonanthropogenic sources are to be designated as nonattainment. Ifareas

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 beread as having no legal effect

or significance. However, thiswould violate canons ofstatutory construction; which direct that statutory language not be treated as mere surplusage.

Consequently, although appendix K
appears to be preserved inpart 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 beregarded as nolonger

6See section 2.4 ofappendix K of40 CFR part 50 and "The Guideline on the Identification and Use ofAir Quality DataAffected by Exceptional Events." EPA-450/4-86-007. July 1986. 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 bediscounted or deweighted in
any manner, but mustbe fully considered in determining whether violations ofthe NAAQS have occurred and whether designation as nonattainment is warranted Future determinations relevant to exceptional
events should therefore focus on the remaining type ofexceptional event identified under section 2.4 of40 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 of40 CFR part 50,appendix K, In addition, guidance on the interpretation ofair quality data believed tobe influenced by special events and conditions will be addressed in a separate publication that will replace the 1986 Exceptional Events Guideline.

111. International Border Areas

A. StatutoryRequirement

Section 818 of the 1990 Amendments added a new section, 179B, to subpart 1,part D oftitle 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 orrevision demonstrate attainment and maintenance ofthe PM10 NAAQS by the applicable attainment date, and (2) the State demonstrates to* EPA's satisfaction thatthe SIPwould be adequate to attain and maintain the PM10 NAAQS by the attainment date but for emissions emanating from outside' the U.S. In addition, section 179B(d) provides thatif 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 notbe subject to the reclassification provisions ofsection 188(b)(2). Section 188(b)(2) provides that any moderate PM-10 nonattainment area that EPA determines is not inattainment after the applicable attainment date shall be reclassified to serious by operation oflaw. Therefore, the statute provides that areas-that could attain but for emissions emanating from outside the U.S. must not be reclassified 

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as serious after failing to attain by the applicable date. 7



### B. Policy

Assuming that a plan or revision meets allapplicable requirements, the State must show that an area is eligible tohave its SIP approved and notbe 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 ofemissions emanating from outside the U.S. The EPA will consider the information presented by the State forindividual nonattainment areas on a case-by-case basis in determining whether an area may qualify for
treatment under section 179B. Five examples ofsuch information are listed below in increasing order of sophistication (the State may use one or
more ofthese types ofinformation or other techniques, depending on their feasibility and applicability, to evaluate the impact ofemissions emanating from outside the U.S. onthe nonattainment
area; the first three examples do not require the State to obtain information from a foreign country): 1.Place several ambient PM-1a 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 PM7As noted, section 179B(d) statesthat areas demonstrating attainment ofthe standards, but for emissions emanating from outside the U.S., shall not be subject tosection 188(b)(2] (reclassification for failure toattain). By analogy to this provision and applying canons ofstatutory construction, EPA will not reclassify before the applicable attainment date areas which can demonstrate attainment ofthe standards, but for emissions emanatingfrom outside the U.S.(see section 188(b)(1)). First, section 179B evinces a generalcongressional intent not to penalize areas where emissions emanating from outside thecountry arethe but-for cause ofthe 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 ofthe statute.Specifically, if EPA proceeded to reclassify,before theapplicable attainment date, thoseareas qualifying for treatment under section 179B, an area would neverbe subject to the provision in section 179B(d) which prohibits EPA from reclassifying such areasafter 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

erroneousreference to carbon monoxide instead of PM-b, and that this section contains other clear

errors (see,e.g., section 179B(c) reference to section 186(b)(9), which does not exist).

8See 40CFR part 58 forguidance on locating PM-10 monitors and "On-site Meteorological Program Guidance forRegulatory Modeling Applications," EPA-450/4-87-013, June 1987 for guidance on locating meteorological stations. 

### 10 concentrations with a change in the predominant wind direction.

2. 

### Comprehensively inventory PM-10 emissions within the U.S. inthe vicinity ofthe nonattainment area and demonstrate that the impact ofthose

sources onthe nonattainment area after application ofreasonably available controls does not cause the NAAQS to be exceeded. This analysis must include

an influx ofbackground PM-10 inthe

area. Background PM-10 levels could be based, for example, onconcentrations measured in a similar nearby area not influenced by emissions from outside the U.S.

3.Analyze'ambient sample filters for specific types ofparticles emanating from across the border (although not required, characteristics ofemissions from foreign sources may be helpful).

4. Inventory the sources onboth sides ofthe border and compare the magnitude ofPM-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 onthe nonattainment

area ofsources located within the U.S. and of foreign sources ofPM-1a emissions (this approach combines information collected from the international emission iniventory, meteorological stations, ambient monitoring network, and analysis of filters).

Inaddition 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 SIPmust continue to meet all applicable moderate area SIP requirements in order to qualify forthe special SIP approval under section 179B. Among other things, the SIP must provide for the implementation of reasonably available cohtrol measures (RACM), including reasonably available control technology (RACT) (see 57 

### FR 13540). In international border areas, 

### RACM/RACT mustbe 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 thedegree 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 theplan or plan revision ofa moderate PM-la 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 areasby not making them responsible forcontrol of emissions emanating from a foreign country over whichthey have no jurisdiction. Moreover, by excluding the

area fromreclassification, Congress also elected to avoid subjecting such areas to the more stringent control measures applicable in serious PM-lO areas. In addition, as set forth insection 179B(a)(2), the second condition which mustbemet before EPA may approve a moderate area plan showing attainment butfor 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 doingso, States containing such an area
were also required,because of contributions to PM-10 violations causedby foreign emissions, to shoulder

more ofa regulatory andeconomic burden than States not similarly affected (i.e., by implementing measures which gowell beyond those which the SIP demonstrates would otherwise be adequate to timely attain and maintain the PM-10NAAQS) such a requirement would unfairly penalize States containing international border areas and effectively undermine the purpose ofsection 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 ofthe Act, EPA does encourage affected States to reduce emissions beyond the minimum necessary to satisfy the "but for" test in orderto reduce the PM-10 concentrations to which their populations are exposed.

The SIP for an international border

area must also include contingency

measures asrequired under section 172(c)(9) ofthe Act. Under section 179B(a)(1), such SIP's mustmeet "all the requirements applicable to itunder the Act" except that they may demonstrate timely attainment by discounting emissions emanating from outside theU.S. Contingency measures
are additional measures included inthe SIP thatcan be undertaken to reduce emissions ifthe area fails to make RFP

orto attain the primary NAAQS by the ___ I I I I|11

. I ] II r 

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applicable attainment date. In international border areas, EPA willnot require the contingency measures for PM-10 tobe implemented afterthe area fails to attainifEPA determines thatthe

area wouldhave attained the NAAQS, but foremissions emanating from outside the U.S. However, the EPA will require contingency measures to be implemented ifit determines that the

area failed to makeRFP inachieving the required reductions inPM-10 emissions from sources within the U.S., or ifthe

area does not, in fact, obtain the emissionreductions thatwere necessary to demonstrate timely attainment ofthe NAAQS, but for emissions emanating from outside the U.S.
IV. Serious Area SIPRequirements

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 willbring about attainment of the PM-10 NAAQS. The first SIP revision was due Novemberi15, 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 willbe due within 18 months after the area is redesignated (see section 189(a)(2)). This SIP revision must, among other things,provide for implementation ofRACM on sources in the area (seesections 189(a)(1)(C) and 172(cj(1)). All available technologically andeconomically feasible control

measures would be considered RACM. and therefore reasonable for adoption, forareas 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



### IfEPA determines that a moderate

area cannot practicably attainthe NAAQS by the applicable attainment date (ordetermines the area has failed to attain) and reclassifies the area as a serious nonattainment area under section 188(b), a second SIP revision for

9Note that ifit can be shown that measures are unreasonable because emissions from the sources affected are insignificant or de minimis, such
measures maybeexcluded from considerationas they would not represent RACM forthat area (see 57 FR 13540). Moreover, in international border
areas, measures which go beyond thosewhich 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 theywould not advance theattainment date (althoughStates may elect'to implement such measures in order to reduce the public's exposure to PM-O)(see discussion under International Border Areas ofthis guidance document). 

### the area isrequired under section 189(b). This revision must, among other things,include provisions to assure that BACM (including BACT) willbe implemented inthe area (seesection 189(b)(1)(B)). In addition, a demonstration (including air quality modeling) mustbe submitted showing that the plan will attain the NAAQS eitherby the applicable attainment date
or, ifan extension is granted under section 188(e), bythe most expeditious alternative date practicable (seesection 189(b)(1)(A)).

The SIPrevisions to require the implementation ofBACM mustbe submitted toEPA within 18 months after an area isreclassified asserious (see section 189(b)(2)). The BACM areto be implemented no laterthan 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 ofthisdocument.

The serious area attainment demonstration required under section 189(b)(1)(A) mustbe submitted to EPA within 4 years after an area is reclassified based on a determination by EPA thatthe areacannot practicably attain the NAAQS bythe statutory deadline for moderate areas. Itis due within 18 months after an area is reclassified for actually having failed to attain the NAAQS bythe moderate area attainment date (see section 189(b)(2)).

The new attainment date for initial PM-10 nonattainment areasthat are reclassified asserious is tobe as expeditious as practicable butnot 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 ofthe tenth calendar year beginning afterthe area's designation as nonattainment (see section 188(c)(2)).

Ifthe State demonstrates to the satisfaction ofEPA that attainment by the statutory deadline for serious areas (asset forth in section 188(c) ofthe Act) is impracticable, the State must demonstrate thatthe SIP provides for attainment bythe mostexpeditious alternative date practicable. The State may apply to EPA fora single extension ofthe serious area attainment date, under section 188(e) ofthe Act, notto 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 stringentmeasures that areincluded in the implementation plan ofany State or are achieved in practice in any State, andcan feasibly be implemented inthe area. The EPA intendsto issue guidance inthe future.

as appropriate, on'applying for an extension ofthe serious area attainment date.

Ifa serious area fails to attain by the applicable attainment date (whichmay be an extended attainment date), another SIP revision is required within 12 months thatprovides forattainment and until thenfor annual reductions in PM-10 orPM-10 precursor emissions within the area ofnotless than 5 percent ofthe amount ofsuch emissions

as reported in the most recent emission inventory for the area (see section 189(d)).



### Inaddition to the specific PM-10 SIP requirements contained in subpart 4 of partD, titleI,States containing serious

areas must meet all ofthe applicable general SIP requirements set forth in section 110(a)(2) and the nonattainment

area SIP requirements set forth in subpart I ofpart D,title I,to the extent that these provisions are not otherwise subsumed by, or integrally related to. the more specific PM-10 requirements.' 0 

### The general SIP requirements applicable to all nonattainment areas are discussed in the General Preamble at 57 FR 13556- 13557.



### 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 guidelines II(see section VI.D. below).

b. Submission ofa SIP, under section 189(b)(1)(A). that includes a demonstration that the plan provides for attainment bythe applicable attainment date (December 31, 2001 forthe areas initially designated nonattainment for PM-10 by operation oflawunder section 107(d)(4) and no later than the end ofthe tenth year beginning after the area's redesignation forareas subsequently redesignated nonattainment)} or ademonstration that attainment by the above date is not practicable and thatthe plan provides for attainment by the most expeditious alternative date practicable.12

"'See 57 FR 13538 (April 16, 1992). I"PM-1OEmission Inventory Requirements." EPA-450/2-93-XX. U.S. Environmental Protection Agency. Research Triangle Park. NC. 1993.

12Subsequent to adoptingrequirements forBACM shortly after the nonattainment area isreclassified

as serious, it may be necessary forthe State to adopt additional control measures in order to demonstrate that the SIP provides for attainment ofthePM-10 NAAQS inaccordance with section 189tb)(t)(A)(il. Ifthe State demonstrates, in accordance with section 189(b)(i)(A)(ii), that attainment bythe applicable serious areaattainment date is impracticable and seeksanextension ofthe 

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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 ofPM-10 precursors under section 189(e), include any stationary source or group ofstationary sources located within a contiguous area and under

common control that emitp, orhas the potential to emit, at least 70 tons per year ofPM-10.

e. Contingency measures t3 (see section VII. below).

f.Quantitative milestones, (applicable
to both moderate and serious area SIP's under section 189(c)), which are to be achieved every 3years 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 ofthe PM-10 NAAQS and annual reductions ofnot less than 5 percent ofinventoried PM-10 and PM10 precursor emissions within the area, under section 189(d), ifthe serious area fails to attain the standards.

h. As applicable, RACT-level, BACTlevel, and new source review control of PM-10 precursors from major stationary

sources ofprecursors 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 SIPDevelopment 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

attainment date pursuant to section 188(e), the Stale must demonstrate to the best of its ability that the plan forthe 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.

'-Contingency measuresareotheravailable control measures, inadditionto those inthe control strategy to attain the NAAQS, that can be implemented ifEPA determinesthe area fails to make reasonable further progressor to attainthe NAAQS by tleapplicable attainment (late Isee section 172(c)(9)). 

### Office ofAir Quality Planning and * Standards to the Directors ofEPA Regional Air Divisions on March 4, 1991.14 That supplementary policy is 

### not applicable to serious area SIP demonstrations.
V. Waivers for Certain PM-10 Nonattainment Areas

A. Historical Perspectives 

### The EPA inthe past focused much of its air pollution control efforts on industrial point source emissions and other traditional sources ofair pollution.' 5

### Forinstance, EPA's 1977 guidance on SIP development gave priority to control ofurban fugitive dust after control oftraditional 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 forsignificant population exposures and attendant health effects

was much greater in urban areas; and (3)

scarce resources atthe Federal, State, and local agency levels could bemost effectively brought to bear on the more pronounced problems found inurban areas.t 6 

### Accordingly, EPA's policy was to require greater emphasis on control of emissions inurban 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 ofmajor industrial sources, with little attention given to natural or nonindustrial en-issions. This policy of giving a lower priority to controlling natural or nonindustrial emissions in rural areas became known as the "Rural Fugitive Dust Policy." '7

'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. rhe 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 1076, andwas coined as acatch-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 theterm has expanded to include such sources as prescribed agricultural and silvicultural burning, open burning, and residential wood combustion. '"Guidance on SIP Development and New Source Review in Areas Impacted by Fugitive Dust," Edward F. Tuerk, Acting Assistant Administrator for Air andWaste Management, to Regional Administrators.

-7See,e.g., "Model Letter Regarding State Designation ofAttainment 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). The EPA's policy focus shifted away from the type and location ofthe emission sources (i.e., traditional or nontraditional sources, urban or rural locations) to the size ofthe particles emitted when the indicator for the NAAQS was changed in 1987 from total suspended particulate matter to PM-10. While revisions to therural fugitive dust policy were being considered, the policy

was continued during the initial phases ofimplementing the PM-10 NAAQS on

an interimbasis.'8 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)).

B. WaiverProvisions

The Act,,as amended in November 1990, was designed toassure that attainment and maintenance ofthe PM10 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 ofthe SIP for PM-10 nonattainment areas, ifnecessary, to

ensure attainment ofthe PM-10 NAAQS

as expeditiously as practicable. Among other planning requirements, the SIP revisions must first provide for the implementation ofRACM on PM-10

sources. IfRACM 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 ofPM-10 emissions from "nonanthropogenic sources," '9 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) ofthe 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.

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 ofPM-10 do not contribute significantly to the violation of the

'5See 52 FR 24716 (July 1, 1987).
19

The legislativehistory ofthe 1990 Amendments indicates that Congress intended that theterm "tonanthropogenic" sources of PM-1 refer to activitieswhere the human role in the cause ofsuch ,emissions is highly attenuated [see H.R. Rep. No. 490, 101st Cong., 2d Sess. 265 (1990)). 

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standard in the area. Second, the Administrator may waive aspecific date for attainment ofthe standard where EPA determines that nonanthropogenic

sources ofPM-10contribute significantly to the violation ofthe standard in the area.

Section 188(f) contains two different legal tests. The first test applies to a waiver ofthe serious area requirements andrequiresthat EPA determine that anthropogenic sources do not contribute significantly before EPAgrants such a waiver. The second testapplies to a waiver ofan area's attainment dateand requires that EPA determine that nonanthropogenic sources contribute significantly before waivingthe attainment date.The firsttest ismore stringent thanthe second.
C.Applicationofthe WaiverProvisions

Several questions must be answered before the waiver provisions canbe applied. Each ofthese questions is discussed inthe subsections thatfollow

1.What types ofsources should be considered anthropogenic and nonanthropogenic?

The legislative history ofthe 1990 Amendments indicates thatCongress intended that the term "nonanthropogenic" sources ofPM-10 refer to activities where the human role in-thecause ofsuch emissions is highly attenuated (seeH.R. Rep. No. 490 at 265). Naturally occurring events such as wildfires, volcanic eruptions, unusually high pollen counts, andhigh winds which generate dust from undisturbed land are examples ofnonanthropogenic

sources that EPAbelieves meet the intent ofCongress.

Anthropogenic sources ofPM-10 emissions are thoseresulting from human activities. Some ofthe traditional and nontraditional anthropogenic sources generally considered in PM-10 SIP's are commercial, institutional, and residential fuel combustion; fossil fuelfired electric power plants; industrial -processes; vehicular traffic onpaved and unpaved roads; construction activities; agricultural activities; and other sources offugitive dust which are directly traceable tohuman activities and which are reasonably foreseeable incidents ofsuch.activities. 2 0 

### 2.What criteria should be used in determining when nonanthropogenic

sources contribute significantly and when anthropogenic sources donot contribute significantly toviolation of the NAAQS in the area?

2"PM-lO SIPDevelopment Guideline," EPA450/2-86-001. U.S. Environmental Protection Agency. Research Triangle Park, NC. 1987. p. 5-5. Table 5.1. The Act does not define the term "contribute significantly" as it is used in section 188(f), nor doesthe legislative history provide any useful guidance.2 1

Where a statute is silent or ambiguous with respect to the meaning ofa statutory term, a reasonable agency interpretation oftheterm must be given deference by a reviewing court (see ChevronU.S.A., Inc.v. Natural ResourcesDefense 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 ofpollution which exceed the NAAQS.

as well as to consider for this purpose. criteria utilized in other statutory contexts. In light ofthe different legal
tests set forth in section 188(f), the EPA believes that different indicators of significance are needed to serve the statutory purpose ofencouraging protection ofpublic 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 ofthebasis for selecting these criteria, are setforth below.

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 willbe 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 orto 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 forthe 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

2t

It

should be noted that the term "contribute significantly" (or variations ofthat 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)), thenew source review (NSR) program, and in specific provisions ofthe statute, such as sections 110(a(2)(D){i)l) and 126(a)(i)B). An agency is permitted, but not required. to give a similar meaning tosimilar terms which appear in differentparts ofa statute. Thus. although EPA is not bound to adopt the interpretation given the term "contribute significantly" in otherparts of the statute, it is likewise not precluded from according this use of similar language some interpretive weight. area's practicable abilities. These principles are-discussed below in connection with each ofthe two waiver
tests.

In selecting an appropriate "significance" contribution from

• anthropogenic sources (forthe purposes ofdeciding whether serious area requirements should bewaived), EPA has elected to rely on the test of significance that is applied under new

source permitting programs. Under the

new sourcereview (NSR) permit
program, the EPA requires State permitting programs to consider new major sources ormajor modifications as causing orcontributing to a violation of the PM-10 NAAQS when the source would add, at a minimum, over 5 pg/m 3

to the 24-hour average orover I g/in3

to the annual average PM-IO concentrations inan area that does not

or would notmeet the PM-I NAAQS (see 40 CFR 51.165(b)). Given that the
purpose ofnew source permitting
programs is alsoto 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) ofthe Act. It should also be noted that, in determining "significance" for purposes ofsection 188(f)the plain
terms ofthat provision and its underlying purpose dictate that EPA consider the impact ofthe anthropogenic sources as awhole. Consequently, where emissions from all anthropogenic sources as awhole contribute less than orequal to 5 pg/rn

to 24-hour average design concentrations and less than orequal to 1pg/m3 to annual mean design concentrations in anonattainment area. after allRACM havebeen implemented,22 EPA will generally regard such contributions as insignificant for purposes ofwaiving requirements applicable to serious PM10 nonattainment areas pursuant to section 188(f).

Generally, ifan area meeting thistest has not yetbeen reclassified as serious and the area would qualify under this
test for a waiver ofcertain serious area requirements as deemed appropriate by EPA (seediscussion below), then EPA will notrequire reclassification, since that action would have no practical

2 Implementation ofRACM (including RACT)is required in all moderate PM-10 nonattainment

areas and that requirement is not waived under the provisions ofsection 188(f). Therefore, the issue is whether anthropogenic sources stillcontribute significantly to violationsofthe NAAQS inan area, after implementing RACM. 

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effect. Generally, ifthe contribution of anthropogenic emissions to the 24-hour design concentration exceeds 5 pg/m 3,



### or ifthe contribution to the annual design concentration exceeds 1 gg/m 3,



### even afterthe application ofall 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 ofunique circumstances, anthropogenic sources donot contribute significantly to violations ofthePM-IO NAAQS in the area.

The EPAwill consider nonanthropogenic sources to contribute significantly (andhence grant an attainment date waiver) only if,after the application ofRACM to nonanthropogenic sources, their contribution to the 24-hour average design concentration exceeds 1511 g/

m3,

### or their contribution tothe annual

mean design concentration exceeds 50

gg/m 3. Because the basic purpose of title Iis to protect public health and welfare through attainment and maintenance ofthe NAAQS, EPA believes that before itmaygenerally presume a serious area's nonanthropogenic emissions contribution to be significant, that contribution should by itselfprevent the

area from attaining the NAAQS after reasonable stepshave been taken to reduce or minimize their impacts. Areas which do notmeet the above criteria, and other situations for which the general presumption is rebutted, willbe reviewed on acase-by case basis (see question 4 below).

Information derived from chemical and optical analyses ofambient filter catches, area emission inventories, and dispersionmodeling to determine maximum source impacts can be used to evaluate the impact ofanthropogenic andnonanthropogenic sources. Analysis offilters collected with a network of monitors over along period (1ormore 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 ofwaiving the attainment date for a moderate area is to relieve it ofthe serious area requirements. Therefore, special considerations apply to the determination ofwhether nonanthropogenic sources contribute significantly to violation ofthe 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'amoderate area met the less stringent attainment date waiver test and the attainment date for the areawas actually waived, the area would neverbe reclassified. 2 3 The result would bethat 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 awaiver of such requirements. In such an event, the

more stringent test for determining whether towaive serious area' requirements would be rendered meaningless. Moderate areas would qualify for the attainment date waiver, be effectively relieved ofall serious area requirements and never have to meet the required test for such waiver.

To avoid this absurd result and only grant a waiver ofthe serious area requirements consistent with the legal standard set out inthe Act,EPA has construed section 188(0 inthe following

manner. A moderate area may only qualify for an attainment date waiver if it also qualifies for a waiver ofthe serious arearequirements. Therefore, EPA must determine that anthropogenic

sources in the area do not contribute significantly to the violation ofthe PM10 NAAQS, and the serious area requirements should be waived before EPA can grant an attainment date waiver for a moderate area. Ifsuch a determination is made, then the attainment date may be waived and the

area would notbe reclassified. These special considerations would notbe 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 ofcourse have the effect of relieving the area ofthe serious area requirements. An area already reclassified as serious could qualify for

an attainment date waiver solely by

23IfEPA waives a specific attainment date fora moderate area consistent with its authority under section 188(f), theattainment date for thearea 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 orthat the

area fails to meet. However, since section 188(f) authorizes waiving only theattainment date, the moderate area would still be subject to all the remaining moderate area SIPrequirements. Therefore, themoderate area SIP submitted to meet the applicable requirements ofsubparts 1and 4 must, amongother requirements, continue to provide for implementation ofRACM. 

### showingthat nonanthropogenic emissions contribute significantly to the nonattainment problem.

As part ofitspolicy, EPA willrequire that areas receiving waivers berevisited periodically to reevaluate source contributions, to ensure that source emissions growth isreasonably controlled, and to determine whether additional controls toreduce the public's exposure to highconcentrations of PM-10 are available (see also the discussion under question 5).

4. What happens ifan area cannot meet the general criteria described above?

Ifevidence ina given nonattainment

area suggests that nonanthropogenic emissions may contribute significantly to violations but are notgreater than 150 gg/m 3

### and/or anthropogenic source contributions are relatively smallbut not lessthan 5pg/m3, then EPA will review the situation on a case-by-case basis taking into account relevant information such as the relative contribution of nonanthropogenic emissions/anthropogenic emissions and the effects ofapplying additional controls tobothtypes of sources.

For moderate areas, ifpreliminary data (emission inventory, filteranalysis, etc.) persuasively indicate that anthropogenic emissions may be insignificant andthat nonanthropogenic emissions may be significant in an area, but such data are not decisive,then EPA will consider granting a temporary or conditional waiver ofthe moderate area attainment date for nomore than 3 years to allow furtherevaluation ofthe situation.'Prior to granting atemporary waiver, EPA and the State must agree on
a protocol for evaluating the impacts of anthropogenic and nonanthropogenic emissions. The protocol must includea schedule with interim milestonesby which the Statewill complete'its analyses. The schedule should consider the need forthe area to adopt and implement BACM so as to meet the applicable serious area attainment date (asexpeditiously 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. Ifthe evaluation conclusively demonstrates that nonanthropogenic emissions are significant, then a waiver ofthe serious area attainment date may be ranted.

Ifit is shown forany moderate nonattainment areathat, although nonanthropogenic emissions may be significant, the application ofcontrols

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appreciably reduce PM-10 concentrations in the area, then the area would not begranted a waiver ofthe 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 ofthe serious area attainment date ifit can d6monstrate 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 violatiors inan area that hasbeen 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. 2 4
"However, the phrase waive a specific date" does not require that the attainment date be waived indefinitely (see.footnote 23 on the effect ofwaiving the moderate area attainment date), nor does it lessen the State's obligation to striveto expeditiously attain the

14

In cases where it is feasible to implement

measures that will reduce future emissions from nonanthropogenic sources (i.e.. planting indigenous .,,,getationorestablishing wind breaks), EPA has thl- authority under section 188(e) to extend the attainment date for a serious area for up to 5 years bjyond 2001 if it is possible that the NAAQS could be attained in the future. Such measures should be considered by States before seeking waivers ofthe attainment date. 

### NAAQS at some time inthe future through available means. While EPA does not expect States to exhaust their

resources to meet standards that maybe unattainable, it does expect them to continue efforts to minimize exposures to unhealthy air.

Eventhough 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 ofanthropogenic 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 ofthe PM-10 NAAQS inthe area. Since emissions from anthropogenic sources increase with population growth and the location ofnew sources to the area, the contribution ofanthropogenic sources to violations can become significant over time. Therefore, the need forreinstating

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 ofanonattainment area's emissions inventory to assure that the requirements ofpart D are met.The EPA plans to use thisauthority to periodically review the waiver status of
areas, as described above. A specific attainment date and applicable requirements should bereinstated ifit is determined that nonanthropogenic

sources no longer contribute significantly or anthropogenic sources begin contributing significantly to violations in thearea. 6. What requirements applicable to serious nonattainment areas under subpart 4 ofpart D should be Waived?

The individual subpart 4 requirements (see section IV. above) wilI be waived only after considering all relevant circumstances on a case-bycase 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. WaiverPolicyDescription

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 inFigure 1. It is important to note that this diagram is provided for illustrative purposes only and should notbe 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 forthe initial nonattainment areas) after implementing RACM (including RACT) forcontributing anthropogenic and nonanthropogenic,sources?

Ifthe moderate area SIP demonstrates that the area can attain with RACM (including RACT) by the attainment date, then the answer to thisquestion is "yes" and the waiver provisions are not applicable.

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Ifan area cannot attain-by the statutory deadlinethen questions 2 and 3 onthe waiver policy diagram mustbe addressed, and several cases may exist.

2. Do anthropogenic sources ofPM-10

asa whole contribute significantly to violations in the area?

3.Do nonanthropogenic sources of PM-10 as a whole contribute significantly to violations inthe area?

Case #1

Ifanthropogenic sources no longer contribute significantly toviolations in the area after the implementation of RACM, thenby default, nonanthropogenic sources must contribute significantly.2 5

### 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 ifit also qualifies for a waiver ofthe 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.

Case #2

Ifanthropogenic sources still contribute significantly to violations in the area afterthe implementation of RACM (i.e., contribute over 5gg/m3 to PM-10concentrations), then the area wouldbe 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 ofBACM in section VI and footnote 33).

Subsequently, the area may qualify for

a waiver ofthe serious area attainment date ifit is demonstrated that nonanthropogenic source contributions (i.e., contributions greater than 150 pig/ m3) would prevent the area from attaining the NAAQS.

25It 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 ofthe statute requires that the emission reductions attributable to RACM (includingRACT) should be considered beforie evaluating thesignificance of anthropogenic contributions. Case #3

Ifanthropogenic sources contribute significantly to violations, but, nonanthropogenic sources contribute less than 150 jig/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 ofserious 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?

Ifthe State can demonstrate that it is possible to attain the NAAQS by the statutory deadline for serious areas through the implementation ofBACM, 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 ofup to 5 years ofthe attainment date? 26

To answer this question, the State
must determine ifan extension oftime 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 ofthe 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 ifemissions within the area are reduced annually by
not less than 5 percent? 2 7

To answer this question, the State
must determine ifthe implementation of additional control measures, annually, would eventually bring the area into attainment. Sufficient additional control

measures would need to be implemented to achieve atleast 5 percent annual reductions in the inventory ofPM-10 emissions from anthropogenic sources.

IfEPA believes that it is practicable for an area, where both anthropogenic and nonanthropogenic sources

2Tho EPAmay grant a single extension of the attainment date for serious areas ofno more than 5years under the conditions ofsection 188(e) ofthe Act. Guidance on demonstrating that a State qualifies for an attainment date extension will be issued in the future.

21

Ifan area fails to attain the NAAQS by the end oftheextension period, then the State must plan
to achieve annual reductions of not less than 5 percent of PM-10 andPM-10 precursor emissions within the area, as reported in the most recent inventory (see section 189(d)). 

### contribute to violations, to 

### attain the NAAQS at any time inthe 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 pointthat it is no longer technologically or econiomically feasible to reduce those emissions further, and the area still cannot attain the NAAQS, then EPA may consider waiving the serious area attainment date and appropriate serious area requirements.

VI. Best Available Control Measures

A. Requirement for BACM There are two circumstances, as discussed earlier, under which a moderate PM-10 nonattainment area may be reclassified as serious. First, an

area may be reclassified whenever EPA determines that the PM-10 NAAQS
cannot practicably be attained by the statutory attainment date.28 Such a determination may be made before the attainment date ifa review ofthe SIP for

an area shows that RACM, including RACT, will notpracticably bring the

area into attainment or ifdelays 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 oflaw upon a determination by EPA that the area has failed to attain the NAAQS on schedule (see section 188(b)).

Section 189(b) establishes additional control requirements for PM-10 nonattainment areas that are reclassified

as serious by EPA. Under section 189(b)(1)(B), States must submit SIP revisions which provide for implementation ofthe BACM for PM-10

- emissions in such areas. These SIP revisions mustbe 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 inmoderate PM-10

2The statutory attainment date for the initial group ofareas designated nonattainment by operation of law upon:enactment ofthe 1990 Amendments, under section 107(d)(4), isDecember 31,1994. 

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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 inthe area as may be obtained through the adoption, at a minimum, ofreasonably available control technology * * *." Thus, moderate PM-10 nonattainment area RACM plans, which are submitted to
meet the requirements ofsection 189(a)(1)(C), must include provisions ensuring the adoption ofRACT (see 57 FR 13540, column 1).

For moderate PM-1 areas reclassified as serious, the nonattainment control requirements (i.e., RACM) are carried over and elevated to a higher level ofstringency (i.e., BACM). So, by analogy, just as RACM includes RACT, inthe same way, BACM includes BACT.2 9 Thus,just as moderate PM-10 SIP revisions when implementing RACM under section 189(a)(1)(C) must provide for the adoption ofRACT, similarly, PM-10 SIP revisions under section 189(b)(1)(B), implementing BACM in seriousPM-10 nonattainment areas, must include provisions ensuring the adoption of BACT. Thispoint was explicitly addressed in the House Committee Report: "Serious areas must include in their submission provisions to require that the best available control measures forthe control ofPM-10 emissions are implemented no later than 4 years after the area is classified orreclassified as serious. Such provisions must include the application ofthe best available control technology to existing stationary sources" (H.R. Rep. No. 490, 101st Cong., 2nd Sess. 266-67 (1990)).

Although section 189(b)(1)(B) requires BACM (includingBACT) to be .implementedin seriousPM-10 nonattainment areas, the Act does not define either BACM orBACT for PM10 nonattainment purposes. Where a statute is silent or ambiguous with respect to the meaning ofastatutory term, the agency is authorized to adopt

an interpretation reasonably accommodated to the purpose ofthe statutory provisi.ons.3 0 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 termshave been historically interpreted in other sections

or titles ofthe Act, the ordinary " grai natical usage associated with the

9Even without the RACM analogy, thebest available technological control measures by their plain terms are a subset ofthe universe ofbest available control measures.

- Chevron, U.S.A., Inc. v. NatumlResources Defense Council,Inc.,467 U.S. 837. 843-44 (1984). word "best," and the overall structure and purpose oftitle I ofthe statute.

B. EPA'sHistorical Interpretation of ControlTechnology Terminology

The Act-uses several terms to refer to different levels ofemission control technology required forexisting ornew

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 apprbpriate for BACM for serious PM10 nonattainment areas.:

The term "reasonably available" was applied to control measures and control technology required to be implemented
at existing sources innoijattainment

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 ofmeeting by the application of technology that is reasonably available considering technological and economic feasibility. 3 1Control measures were determined to be reasonable after considering their energy and environmental impacts and their annualized capital and operating costs. InEPA's view, the cost ofusing a control measure is considered reasonable ifthose same costs are borne by other comparable facilities. Since Congress, in the 1990 Amendmehts, did
not modify EPA's interpretations ofthe RACM and RACT in the earlier 1977 Amendments, it can be presumed to have given some endorsement to EPA's definition ofthe term,

Congress defined the term "best available control technology" in section 169(3) ofthe 1977 Amendments for use in implementing the requirement to prevent significant deterioration (PSD) ofair quality under part C,title I, ofthat Act. This definition was modified by section 403(d) ofthe 1990 Amendments. The BACT is currently defined forthe PSD program asan emission limitation based on the "maximum degree of reduction ofeach pollutant * * * emitted from orwhich results from any major emitting facility, which the permitting authority, on a case-by-case basis, taking into account energy,

31

See, forexample, 44FR 53761-53762 (September 17, 1979) and footnote 3 ofthat notice. Note that EPA's emissions trading policy statement (51 FR 43814 (December 4, 1986)) has clarified that RACTrequirements maybe satisfied byachieving
"PACTequivalent" emissions reductions in the aggregate fromthe full setofexisting stationary

sources subject to thoserequirements (see also EPA'sproposed economic incentives rule, 58FR 11110, 11123 (February 23, 1993)). environmental, and economic impacts and other.costs, determines is achievable for such facility through' application ofproduction processes and available methods, systems, and techniques * * * forcontrol ofeach such pollutant." Thus, BACT is to be determined forthe PSD program on a ease-by-case basistaking into account the energy, environmental, and economic impacts and other costs. Section 169(3) also requires.that BACT be atleast as stringent as any corresponding new source performance standard (NSPS) ornational emission standard for hazardous air pollutants (NESHAP).

Under the PSD program, BACT applies through preconstruction permits issuedto major new and major modified facilities in areas where the air quality isbetter than the NAAQS (section 165(a)(4) ofthe Act, 42 U.S.C. 7475(a)(4)). In broad overview, BACT is determined by identifying the technologically feasible control
measures, from the universe ofavailable control techniques, which yield the maximum degree ofemission reduction,, after considering the energy, environmental and economic impacts of the technology, and other costs. This
may include consideration ofthe annualized capital and operating costs for the facility. The costs of control for

a mnajor new facility ormajor modification ofan existing facility shouldbe considered as a portion of the overall costs ofthenew facility.

The term LAER refers to the level of control required forissuing 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) ofthe Act, 42 U.S.C. 7503(a)(2)). In broad terms, LAER is defined at section 171(3) ofthe Act as the more stringent emission rate based'

on either the most stringent State emission limit orthe most stringent emission limit achieved in practice by such class or category of source. Like BACT, the LAER level ofcontrol must be at least as stringent as the NSPS applicable to the source, Unlike RACT and BACT, the LAER requirement does
notconsider energy orcost factors. In general, the costs of achieving LAER in

a nonattainment area mustbe considered as a portion ofthe overall
cost ofinvesting 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 inPM-10 serious nonattainment-areas, Congress likely considered how the term hasbeen 

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interpreted in other sections and titles ofthe Act. Several other factors (discussedbelow) support such a conclusion.
C.BACM forSeriousPM-1O Nonattainment Areas
Aplain-English interpretation ofthe term "best" implies a generallyhigher standard ofperformance than one that may be considered "reasonable." In addition, the structural scheme throughout titleI ofthe Actisto require the implementation ofincreasingly stringent control measures in areas with

more serious pollutionproblems, while providing such areas alonger timeto attain the applicable standards. This structural schemereflects a basic underlying premise oftitleI.The premise is (1)That more stringent control measures are needed incases when the current control requirements willbe insufficient to bring a particular

area into attainment; and (2) 

### that the

more serious the air quality problem, the more reasonable it isto require States to implement control measures of greater stringency despite the greater burdens such measures arelikely to

cause. TheAct attempts tobalance 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 authorityto extend the attainment date fora serious PM-10 nonattainment areabeyond the specified statutory date, provided certain conditions aremet. One ofthose conditions is that the State must demonstrate to EPA's satisfaction that "the plan forthat area includes the most stringent measures that are included in the implementation plan ofany State or
are achieved in practice in any State, and can feasibly beimplemented inthe area." Thus, underthis section, the Act provides such areas an opportunity to receive additional time to attain the NAAQS. The consequence ofreceiving additional time, however,isthat the State must demonstrate that itsPM-10 implementation plan contains the "most stringent measures" that can feasiblybe implemented in the relevant area from among those which are eitherincluded in any otherSIP or havebeen achieved in practice by any other State.

Similarly, the Actrequires the application ofcontrol 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 andis therefore reclassified asserious. Accordingly, for the reasons stated above, EPAbelieves it isreasonable to conclude that Congress intended a greater level of stringency to apply in areas that are required to implement "best available" controls than in thoserequired only to implement controls that are "reasonably available."

As noted earlier, an array ofdifferent control measures is applicable under various title I NAAQS-related programs. A key factor, among others, in determining the level ofcontrol appropriate fora given area from among the different emission control measures and technologies referred to throughout title Iis the severity ofthe air pollution problem in that area. In addition to the general categorization ofareas as "attainment," "nonattainment," and "unclassifiable," the Actcharacterizes the severity ofan 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-1O nonattainment areas under the nonattainment NSR program; for existing sources, RACM (including RACT) applies inmoderate PM-10 nonattainment areas, while BACM (including BACT)applies in serious PM-1O nonattainment areas. In each
case, the more serious the pollution problem, the more stringent the control slandard required.

It is apparent that inrequiring the application ofBACM 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 ofRACM required forexisting sources in moderate PM-10 nonattainment areas, butnot as stringent as the application of LAER required fornew ormodified

sources inmoderate and serious nonattainment areas (orthe degree of control required to secure an extension under section 188(e)).

1. Definition

Inview ofthe preceding discussion, EPA believes that, as a starting point in interpreting BACM for PM-tO 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 similarterms, EPA believes it is 

### reasonable to accord some interpretive weight tothis use ofsimilar language.
- 

### 1 2 

### Therefore, EPA's interpretation of BACM for serious PM-10 nonattainment

areas will generally be similarto the definition ofBACT forthe PSD program. The BACM is the maximum degree of emissionsreduction ofPM-10 and PM10 precursors from a source (exceptas provided in subsection C. 3)which is determined on a case-by-case basis, takinginto account energy, environmental, and economic impacts and othercosts, to be achievable for such sourcethrough application of production processes and available methods, systems, and techniques for control ofeach such pollutant. ForPM10, BACM must beapplied to existing

- source categories innonattainment areas that cannot practicably attain (or fail to attain) withinthe moderate area timeframe andare reclassified as
serious. 3 3



### Asnoted above, EPA willinterpret PSD BACTand PM-10 BACM as generally similarbecause, despite the similarity interminology, certain key differences exist between control

measures applicable inthe PSD and PM-10 serious nonattainment area programs. The BACTunder the PSD program applies only inareas already meetingthe NAAQS, while PM-10 BACM applies in areas which are seriously violating the NAAQS. This difference in policy goals, arguably, suggeststhat the PM-10 BACM control standard should be more stringent than that for PSD BACT. Onthe other hand. theburden ofinstalling efficient controls during construction ofa new
source orsource modification is generally less onerous thanretrofitting

an existing PM-10 source with similar controls. Ifone compares bothprograms interms ofthesefactors, the differing regulatory andeconomic burdens and the different policy purposes tendto offset each other. Nevertheless, EPA

3 2Under accepted principles ofstatutory interpretation, similar terms in a statute generally suggesta similar meaning, andan agency is permitted, but notrequired, to give a similar meaning to similar terms which appear.in different parts ofa statute.

33

The term "source categories" forwhich BACM will berequired, refers tocategories ofarea-wide

sources or large individual stationary sources of PM-10 orPM-10 precursor emissions that maybe regulated undera specific rule, generic emission limit, orstandard ofperformance, or a specific control program inaSIP. Forexample, the SIP may regulate emissions from unpaved roads, 

### * construction activities, residential wood combustion, asphalt concrete batch plants, etc., as
source categories. Notethat, in some instances, an entire source category may consist ofone large individual stationary source that isregulated separately under theSIP such as a single iron and steel manufacturing facility and the various processes therein. 

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believes that the differences in policy goals-i.e., preventing further pollution under thePSD program and reducing existing pollution under the PM-10 nonattainment program--counsel against adopting the interpretation and implementation ofPSD BACTin its entirety forPM-10 nonattainment
purposes. Rather, EPA considers it reasonable to use the approach adopted inthe PSDBACT program as defined in section 169(3) ofthe Act as an analogue for determining appropriate PM-10 nonattainment control measures in serious areasi 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 ortreatment 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 beboth economically and environmentally beneficial over the long
term.
3. De Minimis Source Categories

The BACM are required for all categories ofsources in serious areas unless the State adequately demonstrates that a particular source category does not'contribute

. significantly to nonattainment ofthe NAAQS. While EPA regards the BACM standard applicable inPM-1 serious

areas asa more stringent control standard which calls for a greater degree, ofemissions control forthe source categories to which it applies, EPA also believes that ithas theauthority to limit the applicability ofBACM 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 forthe implementation of BACM, Congress has not used the word "all" in conjunction withBACM. Congress has also not stated anywhere in the relevant law or legislative history that BACM mustbe 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 AlabamaPowerCo. v. Costle,3 4 that ithas 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 forinvoking the de minimis exemption authority would be satisfied in circumstances where a State demonstrates conclusively that, because ofthe small contribution ofthe source category's emissions to the nonattainment problem, the imposition ofadditional controls, such as BACM,

on a particular source category in the

areawould not contribute significantly
tothe Act's purpose ofachieving attainment ofthe 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 ofthe NAAQS, requiring application ofBACM would produce an insignificant regulatory benefit.

The EPAwill, in general, rely on the criteria applied under new source permitting programs (40 CFR 51.165(b)) ,todetermine when asource 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

As discussed abovd, amoderate PM10 nonattainment area may be reclassified as seriousbased on evidence that the area cannot practicably attain the NAAQS by ihe statutory attainient date or evidence that it has failed to attainby that date. The evidence, whether modeled or measured, will generally indicate the standard (24-hour or annual), the day, and the location ofthe predicted or monitored violation. Therefore, under thispolicy, a source category (see footnote 33) will be presumed to

3 4The inherent authority ofadministrative 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 theground that "the burdens of regulation yield a gain oftrivial or no value" (AlabamaPowerCo. v. Costle,636 F.2d 323, 360-61 (D.C. Cir. 1979)).

35See "Interpretation of'Significant Contribution,"' memorandum from Richard G. Rhoads toAlexandra Smith, Decdmber 16, 1980, 'OAQPSPolicy and Guidance Notebook, PN 165- 80-12-10-007. contribute significantly to a violation of the 24-hour NAAQS ifits PM-10 impact
atthe location ofthe expected violation would exceed 5 jig/M3

. Likewise, a

source category will be presumed to contribute significantly to a violation of the annual NAAQS ifits PM-10 impact
at the time and location ofthe expected violation would exceed I jg/m 3

. Procedures foridentifying source categories that continue to significantly affect the air quality ofa serious area (even after RACM (includingRACT) 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 andpurpose of title I ofthe amended Act, the standard suggested by the word "best," and the differences in the statute between the requirements forBACM as compared to those for RACM, lead EPAto believe that, unlike RACM, BACM are to be established generally independent ofan analysis of the attainment needs ofthe serious area.

As noted earlier in this section, the overall structural scheme throughout title I ofthe Act is torequire the implementation ofincreasingly 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 ofthe NAAQS. As described above, the fact that the-Act requires the application ofcontrol measures that are "reasonable" in moderate PM-10 areas and control measures that are "best" whenever it is determined that a moderate area cannot "practicably" attain oractually 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 ofanalyzing RACM according to what is reasonable in light ofthe overall attainment needs ofthe area. Moreover, when comparing the terms "reasonable" and "best" as applied to control measures, the word "best" strongly implies that there should be agreateremphasis onthe merits ofthe.measure ortechnology alone and less flexibility in considering other factors. 42011.

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Additionally, forPM-10 areas reclassified as serious before the moderate area attainment date, States have up to4 years, under section 189(b)(2), in which to submit their serious areaattainment demonstration. However, under section 189(b)(2), States have only 18months after reclassification from moderate to serious
to submit theirplans requiring the use ofBACM forthose same areas. Thus, for such areas, Congress provided a difference ofas much as21/ years between the required date for submitting BACM plans andthe date by which to submit a new attainment demonstration satisfying the requirements of section 189(b)(1)(A). 

### This pronounced difference in timing forthe serious area submittals described above is to becontrasted with the timing forsubmittal ofsimilar provisions for moderate areas. Under section 189(a)(2), both the RACM plans andthe attainment demonstration formoderate PM-10 areas must asa general matter be submitted at the same time. The fact that the Actrequires BACMto be adopted andimplemented by an appreciable timebefore the attainment demonstration isrequired, forareas that

are reclassified before the moderate area attainment date,suggests that Congress intended that BACM determinations be basedmore on the feasibility of implementing the measures rather than

on an analysis ofthe attainment needs ofthe area.38 

### Therefore, the steps described below for making a BACM determination areintended tobe carried out independently from the analysis to determine the emission reductions that would be necessary to attain the NAAQS by the statutory deadline. Ifthe attainment demonstration forthe area subsequently shows that BACMwill bring the area into attainment before the statutory deadline, then the plan provides forexpeditious attainment of the NAAQS. However, ifthe BACM are not adequate to provide for attainment ofthe standards, then the State must submit additional measures with the attainment demonstration that will result in attainmentofthe standard by the statutory deadline or apply for an extension ofthe attainment date by demonstrating that the specific

36TheEPA believes this interpretation ofthe Act isreasonable, even if,as toareas which are classified in the futureasserious PM-lO nonattainment areas because theareas have failed to attain,the date BACM plans mustbe submitted andthe date the serious areaattainment demonstration isdue should happen to coincide. There is no rational basis forinterpreting BACM differently depending mersly on when an area happens to be reclassified. 

### conditions ofsections 108(e)and 189(b)(IHA)(ii) have been met.

D. Procedures forDetermining Best AvailableControlMeasures

1. Inventory Sources ofPM-la and PM10 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 ofsources to violations over relatively broad geggraphical 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 gg/m 3

for a 24-hour average and less than 1jtg/

m 3annual mean concentration. The starting point for making aBACM determination would beto reevaluate the emission inventory submitted with the moderate area SIP. Section 172(c)(3) ofthe Actcalls for all nonattainment

areas to submit-comprehensive, accurate, and current emissions inventories andprovides for such periodic revisions as may be necessary to assure thatthe nonattainment planning requirements are met. Ifthere 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

ormodified sources constructed) or if the inventory is not adequate to support the more rigorous analysis required for serious area SIP demonstrations, it should berevised. All anthropogenic

sources of PM-10 emissions and PM-10
precursors (ifapplicable) 37 and nonanthropogenic sources in a nonattainment areamust be included in the emission inventory.

Because ofits importance in identifying anthropogenic and nonanthropogenic sources and the applicability ofBACM requirements, the breakdown of sources to consider when compiling an emissions inventory are as follows:

37Ambient filteranalysis and inventory information may havebeen presented in certain moderate areaSIP to indicate the insignificance of secondary particles (see 57 FR 13541-42). 

### a. Major point sources (i.e., sources with the potential to emit at least 70
tons peryear ofPM-10 (or PM-l0 precursors) as required in sections 189(b)(3) and 189(e) ofthe 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 stepin determining BACM for an area is to identify those

source categories having a greater than de minimis impact on PM-10 concentrations. The potential maximum impact ofvarious source categories may have been determined withreceptor or dispersion modeling performed forthe attainment demonstration submitted with the moderate area SIP..In addition, the impact ofsome source categories
may be apparent from analysis of ambient sampling filters from days when the standards are exceeded. If modeling was notperformed during development ofthe 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 ofthe control measures discussed in the BACMguidance 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.

Energy and environmental impacts of the control measures and the cost of control should be considered in determining BACM. Ingeneral, forthe

reasons stated above, the test of economic and technological feasibility will be higher for source categories in serious areas than for source categories inmoderate areasbecause ofthe greater

33See "Technical Information Document for Residential WoodCombustion Best Available Control Measures," EPA-450/2-92-002, September 1992; "Prescribed Burning Background and Technical Information Document for BestAvailable Control Measures," EPA-450/2--92-003, September 1992: and, "Fugitive Dust Background Document and Technical Information Document forBest Available Control Measures." EPA-45012-92-04.. September 1992, 

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need foremission reductions to attain the NAAQS. As noted earlier,this interpretation is consistent with the overall statutory scheme which requires that as an area's airquality worsens

. 

### increasingly stringent control measures

are tobe adopted in conjunction with the area receiving more time to attain the NAAQS. Thus, measures that were not considered reasonable toimplement by the moderate area attainment date may be BACM forserious areas because ofthe additional time available for implementing them 39

### and because of thehigher degree of stringency implied bythe statutory scheme and the term "best." Therefore, BACM could include, though itisnot limited to,expanded use of some ofthe same types ofcontrol

measures as those included as RACM in the moderate area SIP.

Itdoes not currently appearthat mobile sources, as distinct from the surfaces onwhich they travel, contribute significantly tothe PM-10 air quality problem in a sufficient number ofareas towarrant issuing national guidance onbest available transportation controlmeasures for PM10 under section 190 ofthe Act. However, inthose areas where mobile

sources do contribute significantly to PM-10 violations, the Statemust, 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 othercosts.

The technological feasibility of reducing emissions from area sources depends onthe abilityto alter the characteristics that affect emissions from the sources. Those characteristics have to do with the size or extent ofthe
sources, their physical characteristics and the operating procedures. Reducing emissions offugitive dust from construction activities,for example, could require the most effective combination ofreducing the size ofthe

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 ofmaterials handled), and/orchanging the operating practices (i.e.,lower vehicle speeds, less surface area exposed to thewind, treating or paving travel surfaces).

39The statutory attainment date for initial moderate PM-10 nonattainment areas reclassified

as serious will be December 31, 2001. Forareas designated nonattainment subsequent to enactment of the 1990Amendments that become serious, the attainment date will be before the endofthe tenth yearbeginning afterthe area's designation as nonattainment (see section 188(c)). 

### The technological feasibility of applying an emission reduction method to aparticular point source should considerthe source's process and operating procedures, rawmaterials. 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 ofimplementing process changes that reduce emissions and the selection ofadd-on emission control equipment. Theoperation and longevity ofcontrol equipment can be significantly influenced by theraw materials used andthe process towhich itis applied.The feasibility of modifying processes or applying control equipment is also influenced bythe physical layout ofthe particular plant. The space available inwhich to implement such changesmay limit the choices andwill also affect the costsof control.

4.

### Evaluate Costs ofControl

Economic feasibility considers the cost ofreducing emissions from a particular source category andcosts incurred by similar sources that have implemented emissionreductions. As with RACTdeterminations andBACT/ LAER analyses in otherstatutory contexts, EPA believes that for PM-10 BACM purposes, itisreasonable for similar sources tobear similarcosts of emission reduction.As such,when identifying BACM consideration of economic feasibility should notrely on claims regarding the ability ofa particular source to "afford" toreduce emissions to the level ofsimilar sources. Otherwise, less efficient sources might be rewarded fortheir inefficiency by being allowed tobear lower emission reduction costs. Instead, economic feasibility forPM-10 BACM purposes should focus upon evidence that the control technology inquestion has previously beenimplemented at other

sources in a similar source category without unreasonable economic impacts.

Where the economic feasibility ofa
measure (e.g., road paving) depends on public funding, EPA will consider past funding ofsimilar activities aswell as availability offunding sources to determine whether a good faitheffort is being made to expeditiously implement the available control measures. In other words, if20 miles ofunpaved roads are typically paved each year, then the BACM fugitive dust program should includq paving more than 20miles per year ofexisting roads and should offer evidence ofambitious effortsto increase funding and increase the priority foruse ofexisting funds.

The capital costs,annualized costs, and cost effectiveness ofan emission reduction technology shouldbe 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 abovecosts shouldbe determined for alltechnologically-feasible emission reduction options.
E. Selectionof BACM forAreaSources Once the significant PM-I area
source categories havebeen identified, the State should select area source control measures from the candidate BACM listedin thetechnical information documents for fugitive dust. residential wood combustion (RWC), prescribed burning, or any other technical information documents issued byEPA (see footnote 38). Thisguidance isbased on EPA's analysis ofavailable control alternatives for the identified

source categories. Whilethe guidance is intended tobe comprehensive, itis by

no means exhaustive. Consequently, the Stateis encouraged to considerother

sources ofinformation andis not precluded from selecting other measures and demonstrating to thepublic and EPA that they constitute BACM. Further, any control measure that a commenter indicates during the public commentperiod is available fora given

area should be reviewed by the planning agency. The agency should determine whether the affected categories of

sources are significantand, if so. whether the available measure is achievable inthe area considering energy, environmental, and economic impacts and other costs.

As stated earlier, EPA considers

measures that prevent PM-I emissions

over the long term to be preferable to short-term curtailment measures. Therefore, when selecting BACM for

area sources, a State shouldfirst consider pollution preventive measures and measures thatprovide forlong-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 oralternative fuels. Such programs would complement and reduce dependance on wood-burning curtailment programs adopted asRACM forthe 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, ata 42013

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minimum, to provide interim health protection.

Once the list ofavailable 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 ofthe sources in a category ifit is determined that 100 percent implementation ofthe measure is infeasible. This would mean, for example, that an area should consider the feasibility ofpaving 75 percent of the unpaved roadways even though paving all ofthe roads may be infeasible. Alternatively, the State should consider whether measures which cannot feasibly be implemented in theirentirety 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 ofmeasures atthe initial implementation date to a progressively tighter or more ambitious program at later dates.

The following example is presented to illustrate how a gnoderate area program ofRACM 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 oftheir intersections with paved roads.

3. Treat 10 miles ofthe most heavilytraveled, unpaved county roads with chemical dust suppressants once per month.

4. Pave 4 miles ofunpaved 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 ofcity 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: 4 0
1. Pave 10 miles ofthe mostheavilytraveled, unpaved county roads.

2. Treat 10 miles ofunpaved county roads with chemical dust suppressants

once per month.

3. Pave 25 unpaved county roads within 500 feet oftheir intersections with paved roads.

4. Chemically treat orpave both shoulders of30 miles ofState 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 oflea-ving land fallow.

9. Plant crops and windbreaks.across the prevailing wind direction on highly erodible lands.

In summary, the State must document its selection ofBACM 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-1 0 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 ofBACT forPointSources
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 ofemission reduction ofeach 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 ofpreceding discussions of BACT and its statutory bases, it is EPA's policy that BACT be determined using theanalytical 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 sh6uld, at a minimum, consider a

4oAdoption ofthese typos ofmeasures may require coordination with other local governmental entities such as the Departments of Agriculture, Transportation, and/or the Interior. representative range ofavailable 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 ofa particular control system

as BACT must bejustified by a comparison ofthe candidate control systems considering energy, environmental, and economic impacts, and other costs, and be supported by the record.

In addition, ifthe 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 ofthe 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 ofparticulate matter including PM-10 are discussed in "Control Techniques forParticulate 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 ofgeneral particulate
matter control systems such as mechanical collectors, electrostatic precipitators, fabric filters, and wet scrubbers are discussed inVolume I. The collection efficiency ofeach system is discussed as a function ofparticle size. Information is also presented regarding energy and environmental considerations and procedures for estimating costs ofparticulate 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 pastBACT 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 I 

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nonattainment area has failed to make RFPtoward attainment or to attain the primary NAAQS by theapplicable statutory deadline. Following the Administrator's finding,the measures
areto "take effect without further action by the State, orthe Administrator." The EPA interprets this requirement tobe 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 ofpermits, etc., would probably be needed before a

measure couldbe implemented effectively. However, States must show that their contingency measures can be implemented with minimal further action on their partand with no additional rulemaking actions such as public hearings or legislative review. After EPA determines that amoderate PM-lu nonattainment areahas failed to attain the PM-10 NAAQS, EPA generally expects all actions needed to effect full implementation ofthe

measures to occur within 60 days after EPA notifies the State ofthe area's failure. The State should ensure that the

measures are fully implemented as expeditiously as practicable afterthey take effect.

-

The purpose ofcontingency measures is to ensure that additional measures beyond or inaddition to the required "core" control measures (i.e. RACM for moderate areas and BACM forserious areas) immediately take effect when the

area failsto make RFP or to attain the PM-10 NAAQS in order toprovide interim public health and welfare protection. The protection is considered "interim" because the statute often provides for amore formal SIPrevision in order to correct, forexample, the ' failure ofan area to attain the PM-10 NAAQS (e.g.. section 189(b)-serious

area plan required upon finding of failure ofmoderate area to attain the PM-10 NAAQS under 188(b)(2)-and 189(d) (planrevisions required upon failure ofserious area to attain the PM10 NAAQS)). Thus, EPA hasnoted previously that contingency measures should consist ofother available control

measures not contained in the applicable core control strategy (57 FR 13543). In designing its contingency


### measures, the State should alsotake into consideration the potential nature and
extent ofany attainment shortfall forthe

area.The magnitude ofthe effectiveness ofthe 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 ofRFP (see discussion below).

Oncemoderate 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 ofcontingency

measures. Accordingly, for those moderate areas reclassified as serious, if all orpart ofthe 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 Statesmust ensure that serious

areas have adequate contingency

measures considering, among other things; new information about the potential attainment shortfall forthe newly reclassified serious area. The States must submit contingency

measures for serious areas or otherwise demonstrate thatadequate measures are in place within 3 years of reclassification. 4'

VIII. Quantitative Milestones and Reasonable FurtherProgress

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 theamended Act).

1'The Clean Air Act does not prescribe when States containing serious PM-10 nonattainment

areas shall submit section 172(c)(9) contingency

measures (orotherwise demonstrate that adequate contingency measures are already in place). However, section 172(b) of the Act directs the Administrator to establish aschedule for submittal of the plan items in section 172(c) at the time the Administrator designates an area as nonattainrhent. Such schedule is to include adate or dates "extending no later than 3years from the date of the nonattainment designation" (see section 172(b)). By analogy, EPA concludes it isreasonable to establishthat the formal deadline forthe submittal of section 172(c)(9) contingency measures (ora demonstration that adequate contingency measures
are in place) by Statescontaining serious PM-1e nonattainment areas Is no later than 3 years from the date ofthe serious area reclassification (see Chevron. U.S.A., Inc. v. NRDC, 467 U.S. 837.842- 45 (1984)l. 

### Section 171(1) of.the Act defines RFPas "such annual incremental reductions in emissions ofthe relevant airpollutant as

are required bythispart (partD) ormay reasonably be required by the Administrator forthe purpose of ensuring attainment ofthe applicable national ambient airquality standard by the applicable date." A discussion of these requirements follows.

B.ReasonableFurther Progress 

### Historically, forsome pollutants, RFP hasbeen met by showing annual incremental emission reductions sufficient generally tomaintain at least linear progress toward attainment bythe specified deadline. Requiring linear progress reductions inemissions to maintain RFP may be appropriate in four situations:

1.When pollutants are emitted by

numerous and diverse sources.

2.Where the relationship bet veen any individual source and theoverall 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 metby showing annual incremental emission reductions. sufficient generally to maintain linear progress towards attainment. Total PM10emissions should not remain constant or increase from 1year to the next in such an area.

Requiring linear progressreductions in emissions to maintain RFP is less appropriate:

1.Where there are a limited number ofsources.

2.Where therelationships between * individual sources and air quality are relatively well defined.

3.Where theemission control systems utilized (e.g., at majorpoint sources) will result in swift and dramatic emission reductions.

For example, in those areas where the PM-iO nonattainment problem is attributed to a few stationary sources, RFP should bemetby "adherence to an ambitious compliance schedule" .t2 

### which is likely to periodically yield significant emission reductions. Adherence to "an ambitious compliance schedule" does notnecessarily mean that it would be unreasonable to achieve

42 U.S. EPA. OfficeofAir Quality Planningand Standards, "Guidance Document for Correction of Part D SIP's for Nonattahnment Areas," Research Triangle Park, NC. January 27, 1984, page 25. 

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annual incremental emission reductions

or generally linear progress, however.

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 inthe schedule. In reviewing the SIP, EPA will determine whether the annual incremental emission reductions to be achieved are reasonable in light ofthe 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 ofnew 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 ofthe relevant 3 years. Thus, the discussion ofquantitative milestones below refers to the "RFP/ milestone" submittal dates, achievement dates and demonstration (orreporting) requirements.

C. Quantitative Milestones

1. Nature ofQuantitative Milestones

Asmentioned 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 tobe quantified ormeasured. Specifically, States should identify and submit quantitative milestones providing for the amount ofemission reductions adequate to achieve the NAAQS by the applicable attainment (late. 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 ofculpable 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 quantithtive milestones which are to be achieved every 3 years until the area is redesignated attainment. There is a gap inthe law in that the text ofsection 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 IlI.C.1.(f) ofthe General Preamble (57FR 13539) for an explanation ofwhy 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 oflaw when the Act was amended will be the moderate

area attainment date ofDecember 31, 1994, as stated in section III.C.l.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 ofNovember 15, 1991. The achievement date was delayed 46 (lays, however, because the de minimis timing differential between the attainment date and the literal first milestone date made it administratively impracticable and oftrivial 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 altainment (late 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 ofthe emission reductiGns will result from implementation ofRACM (including RACT) adopted as part ofthe moderate

area SIP. The Act requires that RACM be implemented by December 10, 1993 in the initial PM-10 nonattainment areas (. ;ee section 189(a)).

Subsequent RFP/milestones for these initial PM--10 nonattaininent areas that

are reclassified as serious will be due every 33ears after the original due date for the moderate area SiP.43Therefore, 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 ofBACM/ BACT (required within 4 years after the

areais 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.

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 ofthe 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 ofthe relevant 3 years and indicate how the emission reductions achieved to date compare to those required or scheduled
to meet RFP and the required

' 3 The plain terms ofsection 189(c) require that milestones beachieved "every 3 years until the area is redesignated attainment" and, therefore, donot rontemplate 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

a,eaimplementation plan (see section 189(b)(1)). A c.ontinuous series of control measures must be implemented in PM-10 nonattainment areas laginning with RACM (including RACT) and fillowed by contingency measures which are to be implemented ifthe 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/BAf:T to attain thq NAAQS. Tlierefore, the siructure ofthe A t requires a series of measures wbich can provide for RcP/nilcstones. m, I I 

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milestones. The calculations (and any assumptions made) necessary to determine the emission reductions to date should also be submitted. The denonstration should also contain an evaluation ofwhether 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 ofits receipt, EPA
.must determine whether ornot 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 letterto the appropriate Governor or Governor's designee.

4. Failure to Submit RFP/Milestone Report orMeet RFP/Milestones

If a State fails to submit the RFP/ milestone report within the required timeframes or ifEPA determines that the State has not met any applicable RFP/milestone, EPA shall require the State, within 9 months after such failure

ordetermination, to submit a plan revision that assures that the State will achieve the next milestone (orattain the PM-10 NAAQS, ifthere is nonext milestone) by the applicable date (see section 189(c)(3)). For example, with respect to RFP, ifthe 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 ofsanctions as described in sections 110(m) and 179(b) ofthe amended Act (pursuantto a finding under section 179(a)(4)).

IX. Other Requirements

A. Executive Order12866

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 ofE.O. 12866. The E.O. 12866 defines "significant regulatory action" as one that is likely
to result in arule that may:

1. Have an annual effect on the
economy of$100 million ormore or adversely affect in a material way the economy, a sector ofthe 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

orplanned by another agency;

3. materially alter the budgetary impact ofentitl6ments, grants, user fees,

orloan programs or the rights and obligations ofrecipients thereof; or

4. raise novel legal or policy issues ,arising out oflegal mandates, the President's priorities, or the principles
setforth in the Executive Order.

Pursuant to the terms ofE.O. 12866, OMB has notified EPA that this action is a "significant regulatory action" within the meaning ofthe Executive Order. For this reason, this action was submitted to OMB forreview. Changes made inresponse to OMB suggestions or recommendations will be documented in the public record.

B.RegulatoryFlexibility Act
Whenever the Agency is required by section 553 ofthe Administrative Procedure Act (APA) orany other law
to publish general notice ofproposed rulemaking for anyproposed rule, the Agency shall propose and make available for public comment an initial regulatory flexibility analysis. The regulatory flexibility requirements do
not apply forthis PM-10 serious area addendum to the General Preamble because itis not a regulatory action in the context ofthe APA orthe Regulatory Flexibility Act.

Dated: July 29, 1994. Carol M. Browner, Administrator. [FR Doc. 94-19884 Filed 8-15-94; 8:45 am]

BILLING CODE 656040-P

FEDERAL COMMUNICATIONS

COMMISSION

47 CFR Part 73 [MM Docket No.94-74; RM-84761

Radio Broadcasting Service; Elma, WA
AGENCY: Federal Communications Commission. ACTION: Proposed rule; Correction.

SUMMARY: This document contains a correction to the Notice of Proposed RuleMaking(MM Docket No. 94-74: RM-8476), which was published Monday, July 25, 1994 (59 FR 37737). The Noticeproposed the allotment of Channel 271A at Elma, Washington, as the'community's first local aural transmission service. EFFECTIVE DATE: August 16, 1994.
FOR FURTHER INFORMATION CONTACT: 

### Sharon P. McDonald, Mass Media Bureau, (202) 634-6530.
SUPPLEMENTARY INFORMATION: 

### Need for Correction.

As published,the Noticereflected the wrong rulemaking number which needs tobe corrected. Correction ofPublication.

, Accordingly, the publication onJuly 25, 1994 ofthe Public Notice regulations 

### (MM Docket No. 94-74) which were the subject ofFRDoc. 94-17992, is corrected as follows:

Onpage 37737, in the third column,. under 47 CFR Part 73, the rulemaking number is corrected to read "RM-8503" in lieu "RM-8476." Federal Communications Commission. William F. Caton, ActingSecretary. [FR Doc. 94-19989 Filed 8-15-94; 8:45 aml

BILLING CODE -6712-01-M



### DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 20

RIN 1018-AA24 

### Migratory Bird Hunting: Proposed Migratory Bird Hunting Regulations on Certain Federal Indian Reservations and Ceded Landsforthe 1994-95 Season

AGENCY: Fish and Wildlife Service, Interior. 

### ACTION: Proposed rule.

SUMMARY: Thisrule proposes special 

### migratorybird hunting regulations that wouldbe established for certain tribes

onFederal Indian reservations, offreservation trust lands and ceded lands forthe 1994-95 migratory bird hunting

season. DATES: The comment period forthese proposed regulations will end August 31, 1994. 

### ADDRESSES: Address Comments to: Director (FWS/MBMO), U.S. Fish and Wildlife Service, 634 ARLSQ, 1849 C St., NW, Washington, DC 20240. Comments received, ifany, on these proposed special hunting regulations and tribalproposals willbe available for ptblic inspection during normal business hours inRoom 634-Arlington Square Building, 4401 N. Fairfax Drive. Arlington, VA. FOR FURTHER INFORMATION CONTACT: Dr. 

### Keith A. Morehouse, Office 6fMigratory BirdManagement, U.S. Fish and42017

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