Approval and Promulgation of Implementation Plans; Arizona Maricopa County PM-10 Nonattainment Area

ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[AZ 69-0012; FRL-5836-9]

Approval and Promulgation of Implementation Plans; Arizona--

Maricopa County PM-10 Nonattainment Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: EPA is proposing to approve in part and disapprove in part the

final Plan for Attainment of the 24-hour PM-10 Standard--Maricopa

County PM-10 Nonattainment Area, (May 1997) (plan or microscale plan)

submitted by the Arizona Department of Environmental Quality on May 7,

1997. The microscale plan evaluates attainment of the 24-hour

particulate matter (PM-10) national ambient air quality standard at

four monitoring locations in the Maricopa County (Phoenix), Arizona,

PM-10 nonattainment area. EPA is proposing to approve the attainment

and reasonable further progress (RFP) demonstrations for two of these

sites (Salt River and Maryvale) and disapprove them for two other sites

(West Chandler and Gilbert). EPA is also proposing to approve the

reasonably available control measure/best available control measure

(RACM/BACM) demonstrations in the

[[Page 31026]]

microscale plan for some significant source categories of PM-10, but

disapprove them for others.

DATES: Comments on this proposal must be received in writing by June

20, 1997.

ADDRESSES: Comments should be addressed to the contact listed below.

Copies of the State's submittals, the technical support document,

and other information are contained in the docket for this rulemaking.

A copy of this notice and the TSD are also available in the air

programs section of EPA Region 9's website, http://www.epa.gov/

region09. The docket is available for inspection during normal business

hours at the following locations:

U.S. Environmental Protection Agency, Region 9, Office of Air Planning,

Air Division, 17th Floor, 75 Hawthorne Street, San Francisco,

California 94105, (415) 744-1248.

Arizona Department of Environmental Quality, Office of Outreach and

Information, First Floor, 3033 N. Central Avenue, Phoenix, Arizona

85012, (602) 207-2217.

Maricopa County Environmental Services Department, Technical Services

Division, 1001 N. Central Avenue, Suite 201, Phoenix, Arizona 85004,

(602) 506-6010.

FOR FURTHER INFORMATION CONTACT: Frances Wicher, Office of Air Planning

(AIR-2), U.S. Environmental Protection Agency, Region 9, 75 Hawthorne

Street, San Francisco, California 94105. (415) 744-1248.

SUPPLEMENTARY INFORMATION:

I. Background

A. Clean Air Act Requirements

1. Designation and Classification

On the date of enactment of the 1990 Clean Air Act Amendments, PM-

10 areas meeting the conditions of section 107(d) of the Act, including

portions of Maricopa County (the Maricopa County PM-10 nonattainment

area), were designated nonattainment for the PM-10 national ambient air

quality standards (NAAQS) 1 by operation of law. Once an

area is designated nonattainment, section 188 of the Clean Air Act

(CAA) outlines the process for classification of the area and

establishes the area's attainment date. In accordance with section

188(a), at the time of designation, all PM-10 nonattainment areas were

initially classified as ``moderate'' by operation of law. 56 FR 11101

(March 15, 1991).

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\1\ There are two PM-10 NAAQS, a 24-hour standard and an annual

standard. 40 CFR 50.6.

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A moderate area could subsequently be reclassified as ``serious''

under CAA section 188(b)(1), if at any time, EPA determined that the

area could not practicably attain the PM-10 NAAQS by the applicable

attainment date for moderate areas, December 31, 1994. Moreover, a

moderate area was reclassified by operation of law if EPA determined

after the applicable attainment date that, based on actual air quality

data, the area was not in attainment after that date. CAA section

188(b)(2).

On May 10, 1996, EPA published a final reclassification of the

Maricopa County PM-10 nonattainment area as a serious PM-10

nonattainment area based on actual air quality data. 61 FR 21372.

Having been reclassified, the area is required to meet the serious area

requirements in the CAA, including a demonstration that the area will

attain the PM-10 NAAQS as expeditiously as practicable but no later

than December 31, 2001. CAA sections 188(c)(2) and 189(b). Pursuant to

section 189(b)(2), the State of Arizona must submit a serious area plan

addressing both PM-10 NAAQS for the area by December 10, 1997.

2. Moderate Area Planning Requirements

The air quality planning requirements for PM-10 nonattainment areas

are set out in subparts 1 and 4 of title I of the Clean Air Act. EPA

has issued a ``General Preamble'' 2 describing EPA's

preliminary views on how the Agency intends to review SIPs and SIP

revisions submitted under Title I of the Act, including those state

submittals containing moderate PM-10 nonattainment area SIP provisions.

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\2\ See ``State Implementation Plans; General Preamble for the

Implementation of Title I of the Clean Air Act Amendments of 1990,''

57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28, 1992).

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Those states containing initial moderate PM-10 nonattainment areas

were required to submit, among other things, the following provisions

by November 15, 1991:

(a) Provisions to assure that reasonably available control measures

(RACM) (including such reductions in emissions from existing sources in

the area as may be obtained through the adoption, at a minimum, of

reasonably available control technology (RACT)) shall be implemented no

later than December 10, 1993 (CAA sections 172(c)(1) and 189(a)(1)(C));

(b) Provisions to assure implementation of RACT on major stationary

sources of PM-10 precursors except where EPA has determined that such

sources do not contribute significantly to exceedances of the PM-10

standards (CAA section 189(e));

(c) Either a demonstration (including air quality modeling) that

the plan will provide for attainment as expeditiously as practicable

but no later than December 31, 1994 or a demonstration that attainment

by that date is impracticable (CAA sections 188(c)(1) and

189(a)(1)(B));

(d) For plan revisions demonstrating attainment, quantitative

milestones which are to be achieved every 3 years and which demonstrate

reasonable further progress (RFP) toward attainment by December 31,

1994 (CAA section 189(c)); 3 and

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\3\ As will be seen below, the moderate area PM-10 plan for the

Maricopa area did not demonstrate attainment by December 31, 1994,

but rather included the alternative demonstration that attainment by

that date is impracticable. Therefore, section 189(c) did not apply

to the State's moderate area plan.

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(e) For plan revisions demonstrating impracticability, such annual

incremental reductions in PM-10 emissions as are required by part D of

the Act or may reasonably be required by the Administrator for the

purpose of ensuring attainment of the PM-10 NAAQS by the applicable

attainment date (CAA sections 172(c)(2) and 171(1)).

Moderate area plans were also required to meet the generally

applicable SIP requirements for reasonable notice and public hearing

under section 110(l), necessary assurances that the implementing

agencies have adequate personnel, funding and authority under section

110(a)(2)(E)(i) and 40 CFR Sec. 51.280; and the description of

enforcement methods as required by 40 CFR Sec. 51.111, and EPA guidance

implementing these sections.

3. Serious Area Planning Requirements

EPA has issued an Addendum to the General Preamble (Addendum)

describing the Agency's preliminary views on how it intends to review

SIPs and SIP revisions containing serious area plan

provisions.4

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\4\ See ``State Implementation Plans for Serious PM-10

Nonattainment Areas, and Attainment Date Waivers for PM-10

Nonattainment Areas Generally; Addendum to the General Preamble for

the Implementation of Title I of the Clean Air Act Amendments of

1990,'' 59 FR 41998 (August 16, 1996).

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Moderate PM-10 areas that have been reclassified to serious, such

as the Maricopa area, in addition to meeting the moderate area

requirements outlined above, must submit a plan that includes

provisions addressing additional requirements. The additional serious

area requirements that are relevant to this proposed action include:

(a) Provisions to assure that the best available control measures

(BACM)

[[Page 31027]]

(including such reductions in emissions from existing sources in the

area as may be obtained through the adoption, at a minimum, of best

available control technology (BACT)) for the control of PM-10 shall be

implemented no later than 4 years after the area is reclassified (CAA

section 189(b)(1)(B));

(b) Provisions to assure implementation of BACT on major stationary

sources of PM-10 precursors except where EPA has determined that such

sources do not contribute significantly to exceedances of the PM-10

standards (CAA section 189(e));

(c) A demonstration (including air quality modeling) that the plan

will provide for attainment as expeditiously as practicable but no

later than December 31, 2001 (CAA sections 188(c)(2) and

189(b)(1)(A)(i)); 5 and

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\5\ Section 189(b)(1)(A)(ii) provides for an alternative

demonstration of impracticability similar to that available for

moderate areas. Since the State did not make such a demonstration,

this alternative requirement is not addressed in this notice.

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(d) For plan revisions demonstrating attainment, quantitative

milestones which are to be achieved every 3 years and which demonstrate

RFP toward attainment by December 31, 2001 (CAA section 189(c)).

As discussed above in connection with the moderate area plan

requirements, SIPs submitted to meet the CAA's serious area

requirements must conform to general requirements applicable to all

SIPs.

B. EPA Approval of Arizona's Moderate Area PM-10 Plan

On July 28, 1994, EPA proposed to approve the State's moderate area

PM-10 implementation plan revision for the Maricopa area. 59 FR 38402.

Among other elements in that plan, EPA proposed to approve the State's

RFP and RACM demonstrations as meeting the requirements of sections

171(1), 172(c)(1), 172(c)(2), and 189(a)(1)(C) of the CAA. Based on its

approval of the RACM demonstration, EPA also proposed to approve, as

meeting the requirements of section 189(a)(1)(B), the State's

demonstration that even with the implementation of all RACM by December

10, 1993, it was impracticable for the Maricopa area to attain the PM-

10 NAAQS by December 31, 1994.6

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\6\ The reader should refer to both the proposed approval, 59 FR

38402, and the final rule, 60 FR 18010 (April 10, 1995), for EPA's

interpretation of the certain moderate area PM-10 requirements of

the CAA and the Agency's application of these interpretations to the

State's moderate area PM-10 plan. Those notices should also be

consulted for the history of the State's PM-10 plan submittals and

EPA's actions concerning them.

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During the public comment period on the EPA's proposed action, the

Arizona Center for Law in the Public Interest (ACLPI) submitted lengthy

comments on many aspects of EPA's proposed approval of the State's

moderate area PM-10 plan. Among ACLPI's comments were claims that the

plan as submitted failed in numerous respects to meet the moderate area

requirements of the CAA for RACM, RFP and attainment demonstrations.

ACLPI further claimed that the State's impracticability and RACM

demonstrations were additionally deficient in that the State had failed

to address both the annual and 24-hour PM-10 standards as required by

the CAA and EPA guidance. In response to this comment, EPA concluded

that the State's demonstration that the Maricopa area could not

practicably attain the annual standard was sufficient to meet the

requirements of section 189(a)(1)(B) and therefore a separate analysis

was not necessary for the 24-hour standard.

On April 10, 1995, having considered ACLPI's comments, EPA

published a final rule in the Federal Register approving the State's

moderate area PM-10 SIP for the Maricopa area. 60 FR 18010. In its

final action, EPA approved, among other elements of the plan, the

State's RACM and RFP demonstrations, and the State's demonstration that

even with the implementation of all RACM by December 10, 1993, it was

not practicable for the Maricopa area to attain the PM-10 NAAQS by

December 31, 1994.

C. Ninth Circuit Litigation

On May 1, 1995, ACLPI filed, on behalf of two Phoenix residents, a

petition for review, Ober v. EPA, No. 95-70352, of EPA's approval of

Arizona's moderate area PM-10 plan for the Maricopa area in the United

States Court of Appeals for the Ninth Circuit. On May 14, 1996, the

court issued its opinion in the Ober case vacating EPA's approval of

the State's plan. 7

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\7\ The reader is referred to the text of the opinion for the

court's disposition of the range of issues raised by ACLPI in its

petition. 84 F.3d 304 (9th Cir. 1996). This notice addresses that

disposition only as it relates to the 24-hour standard. See also 61

FR 54972 (October 23, 1996) in which EPA preliminarily addresses the

court's opinion as it relates to the RACM, RFP and attainment

demonstrations for the annual standard.

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As it relates to this proposed rulemaking, the court found that the

State was required to address in its SIP the moderate area requirements

in the CAA regarding RFP, RACM and attainment or impracticability for

both the 24-hour and the annual PM-10 NAAQS. The court concluded that

because there are two separate NAAQS for PM-10, the CAA requires an

implementation plan to address each of them. In order to remedy the

failure of the State to address the required demonstrations for the 24-

hour standard, the court required EPA to in turn require the State to

submit those demonstrations. 84 F.3d at 311.

D. EPA's Response to the Ober Opinion

In the wake of the Ninth Circuit's Ober opinion, EPA considered how

to appropriately implement the court's directive in the context of the

State's then prevailing PM-10 planning efforts for the Maricopa area.

The Maricopa area was reclassified as a serious PM-10 nonattainment

area just days before the case was decided and, as noted above, the

State is now required to submit a new PM-10 plan meeting the serious

area requirements by December 10, 1997. Simply put, EPA had to

reconcile, with respect to both timing and content, the court's mandate

that the State submit a plan correcting its moderate area plan

deficiencies regarding the 24-hour standard concurrent with its

responsibility to submit a plan meeting the serious area requirements

for both NAAQS.

1. Timing

As an initial matter, EPA concluded that, given the substantial

overlap of the moderate and serious area planning requirements, it

would not be in the public interest to require the State to divert its

scarce resources into two independent planning exercises. At the same

time the Agency recognized that deferring submittal of a plan

addressing the moderate area plan deficiencies until the serious area

submittal deadline of December 10, 1997 would not constitute a timely

response to the court. Therefore EPA, in consultation with the Arizona

Department of Environmental Quality (ADEQ) and the Maricopa County

Environmental Services Department (MCESD), decided that the State would

incorporate the moderate area plan elements for the 24-hour standard

into the serious area plan, but would split that planning effort into

two related parts. Accordingly, EPA required submittal of a limited,

locally-targeted plan (microscale plan) meeting both the moderate and

serious area requirements for the 24-hour standard by May 9, 1997

(extended from an original deadline of April 18) and a full regional

plan meeting those requirements for both the 24-hour and annual

standards by December 10, 1997. Thus, the microscale and regional plans

taken together would satisfy both the moderate area requirements

mandated by the court and the serious area planning requirements for

both

[[Page 31028]]

standards. Therefore, until the regional plan is submitted and reviewed

by EPA, it is premature to conclude that the microscale plan fully

meets or does not meet the CAA requirements discussed below. The

subject of this proposed action is the microscale plan only.

The submittal deadlines and statutory requirements applicable to

the microscale plan are contained in letters dated September 18, 1996

and March 5, 1997 from Felicia Marcus, Regional Administrator, EPA

Region IX, to Russell Rhoades, Director, ADEQ (Marcus letter).

2. Content

As specified in EPA's September 18, 1996 letter to ADEQ, the

microscale plan was to address the 24-hour standard violations at five

specific monitors and meet the statutory attainment, RACM and RFP

requirements for moderate PM-10 areas and EPA guidance. In addition,

the microscale plan was to meet the statutory attainment, BACM and RFP

requirements for serious PM-10 areas and EPA guidance at 59 FR 41998.

Further, the plan was to contain the air quality modeling and emissions

inventory information necessary to support these attainment, RFP, RACM,

and BACM demonstrations and must meet the general SIP requirements

discussed above.

Having concluded that the hybrid moderate/serious plans described

above would effectuate the intent of the Ninth Circuit's mandate, EPA

then turned to the issue of how to define the moderate area

requirements applicable to the microscale plan after the moderate area

attainment deadline, December 31, 1994, has passed. The following

discussion addresses that issue and the interrelationship of those

requirements with the serious area requirements as they apply to that

plan.

(a) Attainment Demonstration. EPA believes that because the

Maricopa area was reclassified from a moderate to a serious

nonattainment area, the moderate area requirements (demonstration of

impracticability or attainment by no later than December 31, 1994) have

been superseded by the serious area attainment requirement (attainment

by no later than December 31, 2001) and are therefore now moot. Having

reviewed the CAA's moderate and serious area PM-10 attainment

provisions, EPA has concluded that when a moderate PM-10 area has been

reclassified after the moderate area attainment deadline has passed and

been replaced with a new deadline, the moderate area deadline no longer

has any logical, practical or legal significance.

Thus, under this interpretation, there would be no need for the

State's microscale plan, to the extent that it is intended to meet the

CAA's moderate area requirements, to demonstrate attainment. In other

words, such an attainment demonstration would only be required when the

State submits in late 1997 the complete serious area plan to comply

with the section 189(b)(1) attainment demonstration requirement. EPA

believes that its interpretation can be reconciled with the Ober

court's directive that EPA require the State to address the moderate

area attainment requirements for the 24-hour standard and that such an

interpretation is reasonable given the legal and factual context in

which that case was decided. EPA's reasoning is explained in detail at

61 FR 54972, 54974-54975 (October 23, 1996). Nevertheless, EPA has

chosen to comply with the court's remedies regarding the moderate area

attainment requirements. 8

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\8\ While EPA could have sought clarification from the Ninth

Circuit in order to apply its interpretation in the context of

compliance with the court's remedies in Ober, the Agency did not

believe that it would have been in the public interest to do so.

Such a review would necessarily have occurred without benefit of a

thorough briefing on the issue and in the absence of an

administrative record. The Agency does, however, reserve its right

to assert its interpretation in any challenge to EPA's

implementation of the court's remedies or in the context of other

reclassifications. Because EPA is not applying this interpretation

in this rulemaking, it does not constitute final agency action.

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Having determined that it must require the State to meet the CAA's

moderate attainment requirements for the 24-hour standard, EPA has

concluded that since the December 31, 1994 deadline has passed and the

Maricopa area has been reclassified, the only attainment deadline

currently applicable to the area is the serious area deadline, that is,

no later than December 31, 2001. Thus the attainment deadline for both

the moderate and serious area components of the State's microscale PM-

10 plan would be as expeditiously as practicable but no later than

December 31, 2001. Therefore, if the microscale plan demonstrates

attainment of the 24-hour standard at each monitor specified in EPA's

September 18, 1996 letter by no later than December 31, 2001, it will

be deemed to comply with sections 189(a)(1)(B) and (b)(1)(A) of the

CAA.

(b) RACM/BACM Demonstration. Sections 172(c)(1) and 189(a)(1)(C)

read together require that moderate area PM-10 SIPs include RACM and

RACT for existing sources of PM-10. These SIPs were to provide for

implementation of RACM/RACT no later than December 10, 1993. Since the

moderate area deadline for the implementation of RACM/RACT has passed,

EPA has concluded that the RACM/RACT required in the State's microscale

plan must be implemented as soon as possible. Delaney v. EPA, 898 F.2d

687, 691 (9th Cir. 1990).

The methodology for determining RACM/RACT is described in detail in

the General Preamble. 57 FR at 13540-13541. In summary, EPA suggests

starting to define RACM with the list of available control measures for

fugitive dust, residential wood combustion, and prescribed burning

contained in Appendices C1, C2, and C3 of the General Preamble and

adding to this list any additional control measures proposed and

documented in public comments. The state can then cull from the list

any measures for insignificant emission sources of PM-10 and any

measures that are unreasonable for technological or economic reasons.

The General Preamble does not define insignificant except to say that

it would be unreasonable to apply controls to sources that are

negligible (``de minimis'') contributors to ambient concentrations.

However, EPA's serious area plan guidance does define, for use in BACM

determinations, a ``significant contributor'' source category as one

that contributes 5 g/m \3\ or more of PM-10 to a location of

expected 24-hour exceedances. Addendum at 42011. For purposes of the

microscale plan only, EPA is proposing to use this same definition to

define significant in determining which source categories require the

application of RACM.

For any RACM that are rejected by the state, the plan must provide

a reasoned justification for the rejection. Once the final list of RACM

is defined, each RACM must be converted into a legally enforceable

vehicle such as a rule, permit, or other enforceable document. General

Preamble at 13541.

Under section 189(b)(2), for moderate areas that have been

reclassified as serious, the state must submit BACM 18 months after

reclassification, i.e., December 10, 1997 for the Maricopa area, and

must implement those measures four years after reclassification, i.e.,

by June 10, 2000 for the Maricopa area.

BACM is defined as the ``maximum degree of emission reduction of

PM-10 and PM-10 precursors from a [significant] source [category] which

is determined on a case-by-case basis, taking into account energy,

environmental, and economic impacts and other costs, to be achievable

for such sources through application of

[[Page 31029]]

production processes and available methods, systems, and techniques * *

*.'' Addendum at 42010. BACM/BACT must be determined and documented

consistent with the Addendum (59 FR at 42012-14) and must be applied to

each significant area-wide source category and individual stationary

source. Addendum at 42010, footnote 33. A ``significant'' source

category is defined as one that contributes 5 g/m \3\ or more

of PM-10 to a location of expected 24-hour violation. Addendum at

42011.

The state must document its selection of BACM by showing what

control measures applicable to each significant source category were

considered. See Addendum at 42014. BACM should go beyond existing RACM

controls and can include expanded use of RACM controls (e.g., paving

more miles of unpaved roads). Addendum at 42013. Additionally, BACM

should emphasize prevention pf PM-10 emissions where possible over

remediation. Addendum at 42013.

For the microscale plan, EPA required that Arizona submit RACM and

BACM demonstrations by May 9, 1997 as they relate to exceedances of the

24-hour standard at the five specified monitors. RACM and BACM were to

be identified, documented, and realistically evaluated for

effectiveness for contributing sources to each modeled exceedance.

Marcus letter. Evaluation of RACM/BACM in the microscale plan is

limited to controls for sources that are contributing significantly and

directly to the localized violations rather than to sources

contributing to background PM-10 levels. A full analysis of RACM/BACM

for sources that significantly contribute to PM-10 levels in the

Maricopa County PM-10 nonattainment area but are not directly

implicated in the localized exceedances is to be conducted as part of

the regional serious area plan, due December 10, 1997.

(c) RFP/Quantitative Milestones. Both PM-10 moderate and serious

area nonattainment SIPs demonstrating attainment must include

quantitative milestones to be achieved every three years until the area

is designated attainment and must demonstrate RFP toward attainment by

the applicable date. CAA section 189(c)(1). EPA has addressed these

requirements in several guidance documents. See the General Preamble at

13539, the Addendum at 42015-42017, and the memorandum from Sally

Shaver, EPA, to EPA Division Directors, ``Criteria for Granting 1-Year

Extensions of Moderate PM-10 Nonattainment Area Attainment Dates,

Making Attainment Determinations, and Reporting on Quantitative

Milestones,'' November 14, 1994 (Shaver memorandum). Of these guidance

documents, the most comprehensive is the Addendum which discusses both

the RFP annual incremental reduction requirement and the appropriate

interpretation of the milestone requirement as it relates to moderate

areas that have been reclassified to serious.

With respect to RFP, EPA determined that SIPs must indicate the

annual emission reductions that correspond to the compliance schedules

for the control measures in the plan. EPA then has considerable

discretion in reviewing the SIP to determine whether the annual

incremental emission reductions to be achieved are reasonable in light

of the statutory objective of timely attainment. Addendum at 42015.

With respect to the quantitative milestone requirement, for initial

moderate areas, EPA concluded that the SIP should initially address at

least two milestones and that the starting point for the first 3-year

period would be the SIP submittal due date, i.e. November 15, 1991. EPA

further concluded that since the time lag between that date and the

December 31, 1994 attainment deadline was de minimis, emission

reduction progress made between the submittal date and December 31,

1994 would satisfy the first milestone. The second milestone to be

addressed by these initial moderate area SIPs was November 15, 1997.

General Preamble at 131539, Addendum at 42016, and Shaver memorandum.

For moderate areas that are reclassified as serious, the third

milestone achievement date is November 15, 2000. Addendum at 42016. The

quantitative milestones should consist of elements that allow progress

to be quantified or measured, e.g., percent compliance with implemented

control measures. Addendum at 42016.

EPA will assess whether an area has achieved RFP in conjunction

with determining compliance with the quantitative milestone

requirement. Thus a state should address compliance with both

requirements in its RFP/milestone reports. The contents of these

reports is discussed in the General Preamble, its Addendum, and the

Shaver memorandum.

Since the Ober court found that Arizona had failed to submit a

moderate area SIP addressing the 24-hour PM-10 standard in 1991 and the

regional plan addressing both the moderate and serious area

requirements for both PM-10 NAAQS is now due on December 10, 1997, EPA

believes that it is reasonable to conclude, by applying the de minimis

reasoning above, that the November 15, 1997 milestone can be satisfied

by the December plan submittal. Therefore, the microscale plan need not

address the CAA section 189(c)(1) quantitative milestone requirement

and it is not discussed further in this notice.

II. Evaluation of the State's Submittal

The Plan for Attainment of the 24-hour PM-10 Standard--Maricopa

County PM-10 Nonattainment Area (May, 1997) (microscale plan) was

submitted to EPA by the Arizona Department of Environmental Quality

(ADEQ) in draft on March 28, 1997 and in final on May 9, 1997. EPA has

found both submittals complete pursuant to CAA section 110(k) and 40

CFR part 51, Appendix V. Letter, David P. Howekamp, EPA, to Russell F.

Rhoades, ADEQ, May 23, 1997.9

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\9\ ADEQ requested that EPA propose action on the draft plan in

parallel with the State's public comment period (see March 28, 1997

submittal letter); however, the final plan was submitted before EPA

could do so. Therefore, EPA's evaluation of the microscale plan, as

described in this notice, is based on the final plan and all

references in this notice are to that plan.

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EPA has evaluated the plan for compliance with the applicable

statutory, regulatory, and policy requirements described above. This

evaluation is summarized here, and the detailed analysis can be found

in the technical support document which is located in the docket for

this proposed rulemaking.

A. Air Quality Modeling

1. The Microscale Approach

CAA section 189(b)(1)(A)(i) requires serious area plans to include

air quality modeling as part of their attainment demonstrations. For

the microscale plan, base case air quality modeling was required for

exceedances at the (East) Chandler,10 West Chandler,

Gilbert, and Maryvale monitors. For the Salt River monitor, air quality

modeling was required for each unique emissions scenario leading to an

exceedance. In addition, all modeling inputs had to be fully documented

and the air quality

[[Page 31030]]

modeling protocols must conform to EPA guidance or be approved in

advance by EPA. Marcus letter.

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\10\ The East Chandler site was dropped from the microscale plan

because there was insufficient source activity information to

develop a useable inventory for modeling the exceedances at the

site. Plan, Appendix A, p. 3-1. From the information that is

available about the East Chandler site, it appears that exceedances

there have similar causes to those at the modeled West Chandler

site, that is, they are related to windblown dust during high winds

from a mix of urban and agricultural sources. See facsimiles, Randy

Sedlacek, ADEQ, to Frances Wicher, EPA, May 21, 1997 (found in the

docket). The Gilbert site also had similar source characteristics.

Plan, Appendix A, p. 4-7. Therefore, RACM/BACM implemented for the

West Chandler and Gilbert sites should also contribute to emission

reductions at the East Chandler site. Consequently there will be no

further reference to this site in this notice.

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Base case air quality modeling attempts to replicate observed PM-10

NAAQS exceedances using historical observations of air quality,

meteorology, and emissions. The modeling results indicate what sources

are contributing to the exceedances and what level of emissions

reductions are needed to eliminate these exceedances.

The modeling approach used in the microscale plan is significantly

different than default approaches in EPA guidelines and approaches used

in other areas. The main concept of the approach used in the microscale

plan is that if PM-10 exceedances are caused mainly by relatively

nearby sources, then an attainment demonstration can be based on

modeling over a relatively small (microscale) geographic domain, i.e.,

over sub-areas of the nonattainment area. The microscale approach is

more fully described in Microscale Monitoring and Modeling Protocol for

the Maricopa PM-10 Nonattainment Area, Harding Lawson Associates,

August 31, 1994.

Normally, attainment demonstrations should address attainment for

the entire nonattainment area; however, emission inventory development

and modeling for areas with substantial fugitive dust problems, such as

the Maricopa area, have proved difficult because of the marked

uncertainty and temporal and spatial variability of fugitive dust

emissions. Fugitive PM-10 has more localized effects than the other

criteria pollutants because it is emitted near ground level and has

relatively sharp spatial gradients as dust settles out with distance

from the source. These considerations suggest that effort should be

focused on intensive inventorying and modeling of small areas and short

episodes. The approach in the microscale plan can be viewed as an

extension of the microinventory method cited in early EPA guidance on

PM-10 (Receptor Model Technical Series, Volume I, Overview of Receptor

Model Application to Particulate Source Apportionment, EPA-450-4-81-

016a, July 1981, p. 27) but goes a step further in using that emission

inventory as input into a dispersion model to enable a more precise

apportionment of the various sources' effects.

Nevertheless, sources can have effects farther away than is implied

by the term ``microscale.'' The finer component of fugitive PM-10 can

settle out relatively slowly, and during high wind conditions, at least

some of the larger component can be carried long distances. These

effects create a regional component that is not captured in the

emissions of a small area near a monitor. This regional component can

be dealt with as part of a regional modeling exercise or as part of a

``background'' to be added to the microscale results. The latter

approach is taken in the microscale plan. The fact that the background

levels in the plan are relatively high relative compared to the total

concentrations indicates a limitation of the microscale approach. Plan,

pp. 24-26. On the other hand, since fugitive dust control measures

derived from the microscale analysis area to be applied over the entire

nonattainment area, the background will likely also be reduced because

it too is made up primarily of fugitive dust. Therefore, keeping the

background constant between uncontrolled and controlled scenarios, as

is done in the microscale plan, makes for a conservative microscale

attainment demonstration, partly compensating for shortcomings in the

microscale approach.

EPA guidance for ozone and carbon monoxide modeling (e.g.,

Guideline for the Regulatory Application of the Urban Airshed Model,

EPA-450/4-91-013, July 1991) describes the selection of pollution

episodes to model; there is no comparable guidance for PM-10, but the

reasoning would be the same. Basically, the day(s) chosen should be

representative of the meteorological conditions and emissions scenarios

that lead to NAAQS exceedances and have an adequate database for the

development of model inputs. In addition, a microscale approach must

ensure that the particular sites chosen for modeling are worst case or

representative of PM-10 exceedances in the area.

2. Evaluation of the Microscale Plan's Air Quality Modeling

While documentation in the plan is sparse in places, enough

information is provided to assess the adequacy of the approaches used.

The following summarizes EPA's evaluation of the microscale modeling.

The complete evaluation can be found in the TSD.

The rationale for the choice of monitoring sites to model with the

microscale approach is given in Appendix A to the plan. Past emission

inventory and modeling work for the Maricopa ara have identified

several fugitive dust source categories as being especially important

for PM-10 exceedances including urban lots, highway and other

construction activities, agricultural activities, and some industrial

sources. Study sites were chosen in areas of high emissions density:

South Phoenix for its mix of urban sources; 11 Salt River

for its proximity to industrial sources; West Chandler for its nearby

highway construction; and East Chandler for its mix of urban and

agricultural sources. The Gilbert and Maryvale sites were later added

because they recorded 24-hour exceedances during 1995. These sites are

characterized by nearby agricultural land and by park construction/

landscaping, respectively.

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\11\ The South Phoenix site was not included in the microscale

plan because it did not record any 24-hour PM-10 exceedances in

1995. EPA's criterion for determining which sites were to be

analyzed in the microscale plan was whether the site had recorded

exceedances of the 24-hour NAAQS during 1995.

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Together, all these sites present a representative cross-section of

the emission sources in the Maricopa area that are suspected of

contributing to PM-10 exceedances.

The microscale study took place throughout 1995. In addition to the

EPA's standard AP-42 emission methodologies and some other prior

special studies for particular source categories, the microscale study

included field surveys, aerial photography, examination of activity

logs, and interviews with source operators. This study resulted in a

substantially better emissions inventory data than is usually

available.

To help define the geographic domains to be included in the final

modeling, initial screening modeling was performed to determine the

distance beyond which sources have an insignificant impact at the

monitors. Concentrations observed at neighborhood scale monitors, and

information on the land uses that affect these, were used to develop

background concentrations for each portion of the modeling domain.

Background concentrations were then added to the results of the EPA-

recommended ISCST model to yield total predicted concentrations.

Episodes for modeling were chosen from among exceedance days that

occurred during the 1995 study. Because of the importance to the

microscale approach of an intensive emission inventory database, some

days had to be discarded for lack of adequate emission source activity

data.

The Sunday, April 9, 1995 high wind episode day was chosen for the

Gilbert, West Chandler, and Maryvale sites.12 For the Salt

River site, October 16, 1995

[[Page 31031]]

was selected since all the relevant sources were in operation, the

model validated well, and an October day was desirable since many of

the exceedances were in that month. Plan, Appendix A, pp. 7-18 to 7-19.

Multiple days could have been used and would have been desirable given

the seasonal shifts in the daily times of high concentration noted in

the plan. However, these varying concentrations were mainly dependent

on wind direction, and the chosen October 16, 1995 day exhibits fairly

high values in both morning and evening. Thus, the modeled phenomena

are similar enough to the other episodes that this single design day is

sufficient for the Salt River site.

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\12\ For the Gilbert and Maryvale sites, the April 9, 1995

exceedance was the only 24-hour exceedance recorded in 1995. The

West Chandler site recorded a second exceedance on July 30, 1995.

Plan, p. 15. This exceedance also appears to be related to a high

wind event. Plan, Appendix A, p. 3-4.

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Overall, the episodes modeled are representative of the conditions

under which exceedances of the 24-hour PM-10 NAAQS occur. Model

performance was generally good, especially for the Salt River site, and

well within what can be expected from the type of model used, a

Gaussian dispersion model.

The microscale plan's approach for demonstrating attainment within

each sub-area or modeling domain was proportional rollback. The basic

assumption in proportional rollback is that a given percentage

reduction in emissions yields the same percentage reduction in

concentration at the receptor. Every attainment demonstration for a

chemically-inert pollutant (that is, a pollutant that does not react in

the atmosphere) such as primary PM-10 is implicitly based on

proportional rollback, so the plan's approach is acceptable.

Air quality modeling should evaluate the effectiveness of controls

throughout the entire modeling domain. A control strategy sufficient

for attainment at the monitor or at the maximum modeled receptor might

not be sufficient at other receptor points within the domain where

source contributions could be different because of the varying

distances between the receptors and the sources. For the microscale

plan, this variation is probably not important for the Maryvale or Salt

River sub-areas, where a single source category at each site is so

dominant, but could be important for the Gilbert and West Chandler sub-

areas with their more equal mix of sources.13

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\13\ The microscale plan does not demonstrate attainment at the

Gilbert and West Chandler sites; therefore, this point is moot. When

additional controls are analyzed for these sites, an array of points

within each modeling domain should be evaluated. Evaluation of

controls at a single point will not be adequate for an attainment

demonstration.

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As the sub-areas are representative of the sources and conditions

that lead to exceedances, the air quality modeling in the microscale

plan is adequate for demonstrating attainment of the 24-hour PM-10

NAAQS for the Maryvale and Salt River sites within the context of the

microscale approach.

B. Evaluation of RACM/BACM

1. RACM/BACM Analysis

(a) Maryvale Site. The Maryvale PM-10 monitoring site is located

next to the Desert West Park which was under construction in early

1995. Plan, Appendix A, p. 4-2. The air quality modeling evaluation of

the Sunday, April 9, 1995 exceedance at the monitor showed that

windblown fugitive dust, all from the area cleared for the park (that

is, a disturbed cleared area), was the single largest contributor to

the exceedance. Plan, p. 18.

The microscale plan includes a list of potential control measures

for the disturbed cleared area category including wind fences, chemical

stabilizers, watering to maintain adequate soil moisture, and water to

maintain a crust. Plan, p. 22. This source category is also subject to

MCESD's Rule 310, Open Fugitive Dust Sources, which requires the

application of RACM to open sources of fugitive dust. RACM is defined

in the Rule 310 (section 221) and is detailed on the rule's dust

control plan checklist and handbook ``A Guide for Reducing Air

Pollution from Construction.'' See Plan, Appendix E, Letter, Joy Bell,

MCESD, to Joe Gibbs, ADEQ, May 6, 1997 (Bell letter).14

These measures include EPA's suggested RACM for this source

category.15 See General Preamble, Appendix C1.

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\14\ The Maricopa County Board of Supervisors adopted on May 14,

1997 a resolution committing to implement improvements to the

administration of the fugitive dust control program and to foster

interagency cooperation to address fugitive dust. The microscale

plan included the draft resolution, and ADEQ transmitted the adopted

resolution to EPA on May 27, 1997. See letter from Nancy Wrona,

ADEQ, to John Kennedy, EPA.

\15\ Background concentrations at each of the monitoring sites

were substantial (80 to 90 g/m3). Analysis of the causes of

the high background levels was not part of the microscale protocol.

It is possible, therefore, that there are other significant sources

contributing to the exceedances at the monitors that have not been

identified because they only contribute to the background.

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The microscale plan also identifies BACM enhancements, including

revising the dust control plan checklist to make permit holders aware

of the importance of preventing wind-blown dust even when areas are

inactive and the requirement to stabilize disturbed surfaces at all

times, and revising the handbook to encourage them to plan their

projects to minimize the amount of land disturbed at one time. Plan, p

27. These types of enhancements meet EPA's guidance for BACM by going

beyond existing RACM controls, expanding the use of RACM controls, and

emphasizing prevention over remediation.

(b) Salt River Site. The Salt River monitor is located on the

grounds of the City of Phoenix's Salt River Service Center Yard. The

site is surrounded by a number of industrial operations (including pre-

cast concrete manufacturing and sand and gravel operations), landfills

(the 19th Avenue Landfill superfund site and the 27th Avenue Landfill),

and other fugitive dust sources such as unpaved parking lots and roads.

Plan, Appendix A, pp. 6-3 and 6-4. The modeling showed that fugitive

dust from earth moving activities at 19th Avenue Landfill was the

single largest contributor to the modeled October 16, 1995 exceedance

and was the result of not watering to the depth of the cut during earth

moving operations. Plan, pp. 17 and 23. Fugitive dust from unpaved

parking lots, industrial haul roads and other unpaved roads also

contributed significantly to the exceedance. Plan, p. 17. See also

footnote 15 of this notice.

All these significant source categories are subject to the RACM

requirements in Rule 310. The microscale plan also includes a list of

controls for earth moving and unpaved parking lots,16 many

of which duplicate RACM required by Rule 310. Plan, p. 21. These

measures include EPA's suggested RACM for these source categories.

General Preamble, Appendix C1.

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\16\ The identified control measures for unpaved parking lots

are also applicable to unpaved roads.

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The microscale plan also identifies an enhancement to RACM for

earth moving operations. This enhancement requires watering to the

depth of the cut or other equivalent technique. Plan, p. 23. This type

of enhancement meets EPA's guidance for BACM by going beyond existing

RACM controls, expanding the use of RACM controls, and emphasizing

prevention over remediation. The microscale plan does not explicitly

identify BACM for unpaved parking lots, industrial haul roads, and

unpaved roads although clarifications to Rule 310 to make permit

holders aware of the importance of preventing wind-blown dust even when

areas are inactive and of the requirement to stabilize disturbed

surfaces at all times should improve control on these types of sources

when they are located at permitted facilities.

(c) Gilbert Site. The Gilbert monitoring site is located on the

grounds of the City of Gilbert's

[[Page 31032]]

wastewater treatment plant and has agriculture fields and aprons to its

north, paved and unpaved parking to the north and west, and a city park

to the south. Plan, Appendix A, pp. 4-5. The modeling showed that

windblown fugitive dust from agriculture aprons and unpaved parking

lots was the largest contributor to the Sunday, April 9, 1995

exceedance. Plan, p. 18. Fugitive dust from disturbed cleared areas was

also a significant contributor to the exceedance. Plan, p. 18. See also

footnote 15 of this notice. All these source categories are subject to

the RACM requirements in Rule 310.17 The RACM in Rule 310

include EPA's suggested RACM for these source category. General

Preamble, Appendix C1.

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\17\ Application of Rule 310 to agricultural sources including

fields and aprons is affected by the provision in section 102

(incorporating A.R.S. 49-504.4) that the rule ``shall not be

construed so as to prevent normal farm cultural practices.''

Therefore, applicability of the rule to such sources depends on what

dust-generating operation is occurring at the source. In other

words, Rule 310 applies to some operations on agricultural fields

and aprons and not to others.

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The BACM enhancement identified for these categories are

clarifications to the dust control requirements in Rule 310 and

improved enforcement of Rule 310. Plan, p. 23. These types of

enhancements meet EPA's guidance for BACM by going beyond existing RACM

controls, expanding the use of RACM controls, and emphasizing

prevention over remediation. The microscale plan also includes

development of a partnering process with the U.S. Natural Resources

Conservation Service (NRCS) to address fugitive dust from agricultural

sources (Plan, p. 36) and with the local jurisdictions in Maricopa

County to address unpaved parking (Plan, p 35); however, no potential

controls are identified for these sources, nor is there any analysis as

to why controls are not available.

(d) West Chandler Site. The West Chandler monitoring site is

located near the corner of Price and Frye Roads and is bordered on the

west by agriculture fields (which were idle on April 9, 1995) and the

right of way for Price Road/Freeway which was under construction in

early 1995. Plan, Appendix A, p. 4-4. The modeling showed that

windblown fugitive dust, mainly from agricultural fields and road

construction (disturbed cleared area), was the largest contributor to

the April 9, 1995 exceedance. Fugitive dust from vacant lands and

agricultural aprons was also a significant contributor. Plan, p. 19.

See also footnote 15 of this notice. All these source categories are

subject to the RACM requirements in Rule 310 (see footnote 17 of this

notice). These measures include EPA's suggested RACM for all these

source category except agricultural fields. General Preamble, Appendix

C1.

The BACM enhancements to RACM for these categories are similar to

those recommended for Gilbert and Maryvale. Plan, p. 28. These types of

enhancements meet EPA's guidance for BACM by going beyond existing RACM

controls, expanding the use of RACM controls, and emphasizing

prevention over remediation.

(e) PM-10 Precursors. CAA section 189(e) states that the control

requirements applicable under PM-10 plans for major stationary sources

of PM-10 are also applicable to major stationary sources of PM-10

precursors (such as NOX and SOX sources) except

where EPA determines that such sources do not contribute significantly

to PM-10 levels. General Preamble at 13541-13542. ``Significant'' is

not defined in the General Preamble, rather for moderate areas, the

determination was to be made on a case-by-case basis. General Preamble

at 13539. For serious areas, a ``significant'' source category is

defined as one that contributes 5 g/m3 or more of

PM-10 to a location of expected 24-hour violation. Addendum at 42001.

For this rulemaking only, EPA is proposing to apply the serious area

definition to both the RACT and BACT necessity determinations.

It is clear from the modeling that primary-emitted PM-10 (i.e.,

fugitive dust) is the only significant contributor to the 24-hour PM-10

exceedances at the four modeled sites. Based on this evidence, EPA is

proposing to determine under section 189(e) that sources of PM-10

precursors do not contribute significantly to PM-10 levels which exceed

the 24-hour standard at the Gilbert, West Chandler, Maryvale, and Salt

River monitors and therefore no RACM/BACM controls are necessary for

these sources. This proposed finding applies only to the microscale

plan and will need to be evaluated again for the full regional plan.

2. RACM/BACM Implementation

(a) MCESD Rules and Commitments. The primary conclusion of the air

quality modeling is that the 24-hour PM-10 exceedances at the four

evaluated sites are related solely to fugitive dust. The eight source

categories of fugitive dust that were identified as significant (that

is, had an impact of 5 g/m3 or more) at one or more

monitoring sites are regulated wholly or in part by MCESD's Rule 310

(Open Sources of Fugitive Dust). See footnote 17 of this notice. These

significant source categories are disturbed cleared area, earth moving,

unpaved parking lots, unpaved roads, industrial haul roads, vacant

land, agricultural fields, and agricultural aprons.

(i) Rule 310. Rule 310 was adopted by Maricopa County in 1988,

substantially revised in 1993, and revised again in 1994. The rule was

initially submitted to EPA in 1994 as part of the moderate area PM-10

plan for the Maricopa area, and EPA approved the rule on April 10, 1995

(60 FR 18010) in conjunction with its approval of the overall moderate

area plan. This plan's approval was subsequently vacated by the Ninth

Circuit in Ober. Although the court's opinion did not address the SIP

approvability of Rule 310, its disposition had the incidental effect of

also vacating EPA's approval of Rule 310.

In the 1994 proposed approval of the moderate area plan, EPA found

that Rule 310 met the CAA's enforceability requirements and proposed to

approve the rule except for a ``director's discretion''

provision.18 59 FR 38402 (July 28, 1994). Several comments

questioning the enforceability of Rule 310 were received on the

proposal but none changed EPA's conclusion that the rule was

enforceable. 60 FR 18018. Neither the rule nor EPA's finding that the

rule meets the SIP enforceability criteria has changed since that time.

Therefore EPA is reaffirming its previous finding that Rule 310 meets

the requirements of CAA sections 110(a)(2)(A) and 172(c)(6) for

enforceable emission limitations. As a result, EPA is proposing to

reapprove Rule 310 as an element of the Arizona SIP for the Maricopa

PM-10 nonattainment area.

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\18\ This provision was subsequently deleted from the rule.

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Implementation of Rule 310. Rule 310 requires the application of

reasonably available control measures to open sources of fugitive dust.

RACM is defined in the rule (section 221) and is detailed on the dust

control plan checklist and in the Rule 310 handbook ``A Guide for

Reducing Air Pollution from Construction.'' The microscale plan

includes revisions to the checklist and handbook to reflect BACM. Plan,

Appendix E, Bell letter. These revisions include making clear that the

dust control plan must be implemented throughout the life of the

project until all roads and disturbed areas are stabilized and that

watering is required to the depth of an earth moving cut.

Rule 310 also requires that an earth moving permit be obtained

prior to

[[Page 31033]]

engaging in any commercial, industrial or institutional earth moving or

dust generating operation that disturbs a total surface area of 0.10

acres or more.\19\ Rule 310, section 302 (dust generating operations--

permits required). A dust control plan must be submitted with the

permit application. Rule 310, section 303 (control plans). Earth moving

permits must be renewed every year. Rule 200 (Permit Requirements),

section 305.4. No permit is required for other fugitive dust sources

regulated by Rule 310 such as unpaved parking lots, unpaved roads,

vacant lots, agricultural fields, and agricultural aprons.

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\19\ Maricopa County's interpretation of the prohibition in

A.R.S. 49-504.4 that county air pollution control agencies cannot

``prevent [] normal farm cultural practices which cause dust'' has

effectively exempted agricultural sources from the permit

requirements of Rule 310. Plan, p. 31.

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To help permit applicants develop dust control plans, MCESD has

developed a general dust control plan or checklist that lists RACM by

category (e.g., earth moving, disturbed surface areas). Permit

applicants can simply check off the RACM they will use but must check

off at least one measure per category. Alternatively, applicants may

craft their own dust control plans provided they meet the requirements

of Rule 310. See Plan, p. 34 (revised dust control plan checklist).

Review of earth moving permit applications and dust control plans

as well as the inspection of permitted earth moving sites is done

primarily by the MCESD's Earthmoving/Burn Permit

Coordinator.20 Inspections are conducted for all projects

greater than 10 acres in size and smaller operations are inspected

based on several factors including the compliance history of the

contractor/developer or complaints. Some inspections are performed by

the Department's regional offices when time allows. Plan, Appendix B,

p. 2-5. MCESD inspectors also note earth moving operations when they

are out in the field and stop to check if the required permit is

posted. Plan, Appendix G, p. 18. Historically, stationary sources have

not been inspected for Rule 310 violations even when they have fugitive

dust sources subject to the rule.21 Plan, Appendix B, p. 2-

5.

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\20\ During the fall and winter this Coordinator is also

responsible for implementing the County's residential wood burning

restriction rule. Given the demonstrated contribution of earth

moving sources to Maricopa area PM-10 exceedances, MCESD may want to

re-evaluate splitting the Coordinator's time between the fugitive

dust and no burn programs.

\21\ MCESD is addressing the permitting process for stationary

sources subject to dust control plan requirements in a work flow

review and analysis of the Department's permitting process.

Recommendations from this review (such as revised permitting

procedures) will be implemented in July, 1997. Plan, Appendix E,

Bell letter. Improved permitting of these sources should result in

better inspections.

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MCESD only inspects sources that do not require permits (such as

vacant land and unpaved parking lots) on a complaint basis and has no

proactive inspection or compliance assurance program for these types of

sources. Plan, p. 12.

The microscale plan identifies a number of recommended changes to

improve implementation of Rule 310. MCESD has or will undertake a

number of internal program modifications to implement these

recommendations and will lead a regional program to foster interagency

cooperation to reduce particulate pollution.

Some of the internal program modifications the Department has

already made are revising a number of documents that support

implementation of Rule 310 including the dust control plan, the Rule

310 handbook, the guideline for earth moving inspection checklist, and

the standard operating procedures (SOP) for earth moving permit

application processing and site inspection. In addition, MCESD is

revising the SOP for air pollution inspection procedures.22

Plan, Appendix E, Bell letter. Other changes include updating staff

training on Rule 310 (target completion date: May 31, 1997), initiating

a weekend inspection program for Rule 310 sources (target date: May,

1997), and linking the earth moving permit, complaint, and enforcement

databases to improve access to information on permitted sources (target

completion date: February, 1998). Plan, Appendix E, Bell letter. A

complete description of MCESD's commitments can be found in the Plan,

Appendix E, Bell letter.

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\22\ EPA recently complete a review of permit files at MCESD.

One of the focuses of this file review was to evaluate the effect of

the SOPs on the completeness and quality of inspections. The review

showed that the SOPs have resulted in more thorough and higher

quality inspections. Memorandum, Colleen McKaughan to Doug McDaniel,

``File Review at Maricopa County Environmental Services Department

April 7-10, 1997'' May 19, 1997 (found in the docket).

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Regional Program. MCESD has also committed to a regional program to

foster interagency cooperation including designating a MCESD staff

person as a coordinator, holding Rule 310 workshops for cities and

contractors, creating material on Rule 310 for distributing to City/

County staff and contractors, continuing to conduct workshops in 1997

on studying and improving the current dust control program, expanding

public awareness programs for particulate pollution, and publicizing

MCESD's public complaint line number. The regional program will be

fully implemented in 1997. A complete description of MCESD's

commitments can be found in the Plan, Appendix E, Bell letter.

In total, MCESD's commitments clearly identify the actions required

and the deadlines for those actions and thus constitute enforceable

control measures under CAA sections 110(a)(2)(A) and 172(c)(6). EPA,

therefore, proposes to approve them as elements of the Arizona SIP.

Resources for Rule 310 Implementation. MCESD will continue to

implement Rule 310 through a program of reviewing and evaluating dust

control plans, inspection of sources with earthmoving permits, and

responding to complaints. The Earthmoving/Burn Permit Coordinator has

primary responsibility for reviewing dust control plans and inspections

and is aided in inspections by four dedicated stationary source

inspectors in the main office. In addition, MCESD has recently hired a

public involvement coordinator and an assistant to the Earthmoving/Burn

Permit Coordinator. Finally, the Department's Small Business Assistance

Program also assists in implementing Rule 310 through outreach and

compliance assistance. Plan, Appendix E, Bell letter.

Complaints are handled by the appropriate regional office. Each

regional office has one supervising inspector and two staff inspectors.

The regional offices also do earth moving inspections as time allows

during the summer months. These non-complaint inspections are limited

to permitted sites from 5 to 10 acres. Plan, Appendix B, pp. 2-4 and 2-

5.

In all, there are 1.75 full time equivalent (FTE) positions working

directly on Rule 310 implementation, plus the Department has 19

inspectors, aides, engineers, and supervisors available to perform

field observations and respond to complaints. Plan, Appendix E, Bell

letter. This level of staffing (when combined with the support from the

rest of the Department's inspection staff) is sufficient to ensure

implementation of Rule 310 at the level assumed and committed to in the

microscale plan, that is, a reasonable level of implementation on

permitted sources but minimal implementation on nonpermitted

sources.23

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\23\ The microscale plan only assumes emission reductions from

sources subject to permitting (e.g., earth moving, disturbed cleared

areas). No reductions are assumed for nonpermitted sources (e.g.,

vacant lots, unpaved parking). See Plan, pp. 37-40.

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[[Page 31034]]

(ii) Rules 311 and 316. Individual point sources (e.g., several

concrete manufacturers and sand and gravel operations) whose emissions

are accounted for within several of the source categories at the Salt

River site are also covered by MCESD's Rule 311 (Particulate Matter

from Process Industries) and Rule 316 (Nonmetallic Mineral Mining and

Processing). These rules were approved by EPA as RACT for PM-10 sources

as part of the approval of the moderate area plan. 60 FR 18009. While

not at issue in the litigation regarding that plan's approval, EPA's

approval of these rules was also incidently vacated by the Ober

decision. EPA, therefore, will be restoring its approval of these rules

in its final action on this proposal.

(b) City Resolutions. The microscale plan includes resolutions

adopted by the Cities of Phoenix, Tempe, Chandler, Glendale,

Scottsdale, and Mesa and the Town of Gilbert (collectively, city or the

cities). Plan, Appendix E, ``Resolutions Adopted by Various Cities and

Towns within Maricopa County'' (resolutions). The resolutions commit

each city to participate in a regional program led by MCESD to foster

interagency cooperation to reduce particulate pollution. This

participation requires the city to (1) designate a staff person to

coordinate the city's participation in the regional dust control

program, (2) participate in workshops (to be held by MCESD) to study

current dust control programs and to evaluate options for additional

efforts, (3) distribute MCESD information on dust control to grading

and certain building permit applicants, (4) ensure appropriate city

personnel receive training on Rule 310 requirements, and (5) distribute

information on particulate pollution to the public. The resolutions do

not commit the cities to adopt any additional dust control

requirements.

The cities will undertake these actions using current staffing and

funding. Plan, p. 35 and Appendix E, resolutions. Because these actions

are easily integrated into on-going city activities, these staffing and

funding levels are adequate to implement the commitments. MCESD has

complemented the cities' efforts by committing to designate a staff

person as the regional program coordinator, to hold workshops, develop

material for distribution, and provide training on Rule 310. Plan,

Appendix E, Bell letter.

The commitment to address fugitive dust is an important additional

step by the cities to help solve Maricopa's PM-10 problem in the long

term.24 The air quality modeling clearly shows that fugitive

dust from nonpermitted sources such as vacant lands, unpaved parking

lots, and unpaved roads are significant contributors to exceedances.

Given the size of the Maricopa PM-10 nonattainment area and MCESD's

limited resources, the cities and towns will need to take a more active

role in reducing fugitive dust from these nonpermitted sources.

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\24\ Many of the cities and towns in Maricopa County have

already committed to undertake other PM-10 control measures such as

paving unpaved roads. See MAG 1991 Particulate Plan.

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The cities' resolutions clearly identify the actions required and

the deadlines for those actions and thus constitute enforceable

commitments. As such, EPA proposes to approve them into the Arizona SIP

for the Maricopa PM-10 nonattainment area.

(c) Agricultural Sources. As discussed previously, the air quality

modeling demonstrated that control of fugitive dust from agricultural

fields and field aprons is necessary for attainment of the 24-hour PM-

10 standard at the Gilbert and West Chandler sites. Rule 310, while

nominally applicable to agricultural sources, is not in general

enforced against them. Plan, p. 31. See also footnote 17 of this

notice. The microscale plan contains no controls for these source

categories but does include an agreement by ADEQ, MCESD, and the

federal Natural Resources Conservation Services (NRCS) to develop a

protocol to address fugitive dust on agricultural land and refine

roles, objectives and schedule. Plan, p. 36 and Appendix E, ``Agreement

of ADEQ, U.S. NRCS, and MCESD'' (NRCS agreement).

EPA appreciates the agreement of the three agencies to develop a

protocol to address fugitive dust from agricultural sources and fully

supports this effort. However, given the impact of these sources on PM-

10 levels in the Maricopa area, it is important that the protocol and

the work that follows it are focused on getting appropriate RACM and

BACM measures in place by the applicable deadlines.

(d) Proposed Finding on RACM/BACM Implementation. There are eight

source categories of fugitive dust identified in the microscale plan as

significant at one or more monitoring sites: disturbed cleared area,

earth moving, unpaved parking lots, unpaved roads, industrial haul

roads, vacant land, agricultural field aprons, and agricultural

fields.25 Plan, pp. 17-19. These sources divide into three

categories. In the first category are sources subject to permitting:

disturbed cleared areas, earth moving, and industrial haul

roads.26 In the second category are sources that are not

subject to permitting (i.e., nonpermitted sources): unpaved parking

lots, unpaved roads, and vacant land. Finally, in the third category

are the two sources that are essentially unregulated by Rule 310:

agricultural fields and agricultural aprons.

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

\25\ As noted previously (footnote 15), there may be other

significant sources impacting the monitors that were not identified

in the microscale modeling because they formed part of the

background concentration.

\26\ Haul roads are considered permitted sources in the

microscale plan because, at the Salt River site where this category

was significant, the haul roads are located on permitted sources.

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

As discussed above, MCESD has an adequate implementation strategy

for dealing with permitted sources including review and approval of

dust control plans and proactive inspections and has sufficient

resources to carry out that strategy. The Department adopted Rule 310

in 1994 and is already implementing and improving the program. Plan,

pp. 7-13 and 32-33. The BACM improvements to the Rule 310 program and

the other commitments in the microscale plan will all be fully

implemented within one year of submittal of the final plan, with many

being implemented within one or two months. Plan, pp. 32-33. EPA,

therefore, is proposing to find that the microscale plan assures

implementation of RACM as soon as possible and BACM by December 10,

2000 as required by CAA sections 189(a)(1)(C) and 189(b)(1)(B) for the

significant source categories of: disturbed cleared areas, earth

moving, and industrial haul roads. EPA is proposing to approve the

RACM/BACM demonstrations for these source categories.

For nonpermitted sources, MCESD seeks compliance with Rule 310 only

when complaints are received. MCESD has adopted RACM controls for these

sources in Rule 310 and is committed along with the seven cities to

evaluate options to reduce particulate from vacant lands, unpaved

roads, and unpaved parking areas. Plan, Appendix E, Bell Letter. The

microscale plan, however, contains no commitments to assure RACM/BACM

will be implemented for these sources at a meaningful level nor any

analysis as to why RACM or BACM implementation on these sources is

infeasible. As a result, the microscale plan does not claim any credit

in the attainment demonstrations for these nonpermitted sources. Plan,

pp. 37-40. EPA, therefore, is proposing to find that the microscale

plan does not assure implementation of

[[Page 31035]]

either RACM or BACM as required by CAA sections 189(a)(1)(C) and

189(b)(1)(B) and to disapprove the RACM/BACM demonstrations for the

unpaved parking lots, unpaved roads, and vacant land source categories.

As discussed previously, there are currently no effective controls

on agricultural sources in the Maricopa area. The microscale plan

provides for the development of a partnership to identify appropriate

controls but does not contain any actual controls nor is there any

analysis as to why RACM/BACM implementation on these sources is

infeasible. EPA is, therefore, proposing to find that the microscale

plan does not assure implementation of either RACM or BACM as required

by CAA sections 189(a)(1)(C) and 189(b)(1)(B) and to disapprove the

RACM/BACM demonstrations for these sources.

These proposed findings are applicable only to the microscale plan

and thus, if finalized, will not constitute EPA's final decision as to

the State's full compliance with the requirements of CAA sections

189(a)(1)(C) and 189(b)(1)(B) for RACM and BACM for the eight source

categories. The State will need to re-evaluate appropriate RACM and

BACM for these sources in the full regional plan.

C. Evaluation of Attainment and RFP Demonstrations

1. Salt River Site

As discussed above, attainment of the 24-hour PM-10 standard at the

Salt River site requires additional controls for earth moving

activities, specifically watering to the depth of the cut or other

equivalent techniques, in addition to the existing control provided by

Rule 310. Plan, p. 37. These earth moving activities are subject to

permitting under Rule 310. MCESD will revise its dust control plan

checklist to clarify the earth moving requirement in May, 1997, and

will begin including the requirement in all new earth moving permits

and permit renewals by June 1, 1997. Plan, Appendix E, Bell letter.

Permit renewals are required annually, thus full implementation will

occur within one year of the submittal of the final plan. Plan, p. 38.

Attainment is predicted based on acceptable air quality modeling.

EPA will be restoring its approval of Rules 311 and 316. EPA is also

proposing to reapprove Rule 310 and to approve the additional controls

assumed in the attainment demonstration. Finally, EPA is also proposing

to find that MCESD has adequate resources, personnel, and authority to

assure implementation of the measures required for attainment at this

site. EPA is, therefore, proposing to approve the attainment

demonstration at the Salt River monitor pursuant to CAA sections

189(a)(1)(B) and 189(b)(1)(A).

Reasonable further progress is defined in CAA section 171(1) as

``such annual incremental reductions in emissions of the relevant air

pollutant as * * * may be reasonably be required by the Administrator

for the purposes of ensuring attainment of the applicable [NAAQS].''

Because attainment will occur within one year of final plan submittal,

the RFP and attainment demonstrations at this monitor are the same;

that is the annual increment needed for progress toward attainment is

the same as the emission reduction needed for attainment. Therefore,

EPA is proposing to approve the RFP demonstration at this monitor

pursuant to CAA section 189(c).

2. The Maryvale Site

Attainment of the 24-hour PM-10 standard at the Maryvale site

requires stabilization of disturbed cleared areas at all times. Plan,

p. 38. Disturbed cleared areas is a source category subject to

permitting under Rule 310. MCESD has revised its dust control plan

checklist for Rule 310 to clarify the requirement to stabilize all

disturbed areas at all times and will begin including the requirement

in all new earth moving permits and permit renewals by June 1, 1997.

Plan, Appendix E, Bell letter. Permit renewals are required annually,

thus full implementation and attainment will occur within one year of

the submittal of the final plan. Plan, p. 38.

Attainment is predicted based on acceptable air quality modeling.

EPA is proposing to reapprove Rule 310 and to approve the additional

controls assumed in the attainment demonstration. Finally, EPA is

proposing to find that MCESD has adequate resources, personnel, and

authority to assure implementation of the measures to the extent

required for attainment at this site. EPA is, therefore, proposing to

approve the attainment demonstration at the Maryvale monitor pursuant

to CAA sections 189(a)(1)(B) and 189(b)(1)(A).

Because attainment will occur within one year of final plan

submittal, the RFP and attainment demonstrations at this monitor are

essentially the same; that is the annual increment needed for progress

toward attainment is the same as the emission reductions needed for

attainment. Therefore, EPA is proposing to approve the RFP

demonstration at this monitor pursuant to CAA section 189(c).

3. The Gilbert Site

The microscale plan does not demonstrate attainment or RFP at the

Gilbert site because of uncontrolled fugitive dust emissions from

agricultural aprons and unpaved parking lots. Plan, p. 38. As noted

before, the microscale plan does include strategies to evaluate

controls on these sources but, at this time, does not assure

implementation of controls for them. EPA is, therefore, proposing to

disapprove the attainment and RFP demonstrations for this site.

4. The West Chandler Site

The microscale plan does not demonstrate attainment or RFP for the

West Chandler site because of uncontrolled fugitive dust emissions from

agricultural fields and aprons and vacant land. Plan, p. 39. As noted

before, the microscale plan does include strategies to evaluate

controls on these sources but, at this time, does not assure

implementation of controls for them. EPA is, therefore, proposing to

disapprove the attainment and RFP demonstrations for this site.

These proposed approvals and disapprovals are applicable only to

the microscale plan and thus, if finalized, will not constitute EPA's

final decision as to the State's full compliance with the requirements

of CAA sections 189(a)(1)(B), 189(b)(1)(A) and 189(c)(1) for attainment

and RFP demonstrations at the Salt River, Maryvale, Gilbert and West

Chandler monitoring sites. Because regional factors may influence

attainment at these sites, the State will need to re-evaluate modeling

at all four sites as part of the full regional plan.

D. General SIP Requirements

1. Section 110(l) Finding

CAA section 110(l) states that the ``Administrator shall not

approve a revision of a plan if the revision would interfere with any

applicable requirement concerning attainment and reasonable further

progress * * * or any other applicable requirement of this Act.''

Pursuant to section 110(l) of the Act, EPA proposes to find that

its proposed partial approval of the microscale plan does not interfere

with any other requirements of the Act applicable to the Maricopa PM-10

nonattainment area including the requirements for attainment and RFP.

In fact, the control measures and commitments in the plan are essential

elements in the demonstrations of attainment and RFP for the area for

the 24-hour PM-10

[[Page 31036]]

NAAQS and partially meet the statutory requirement for the adoption and

implementation of RACM and BACM.

2. Adequate Personnel, Funding, and Authority

Section 110(a)(2)(E)(i) of the Clean Air Act requires that

implementation plans provide necessary assurances that the state (or

the general purpose local government) will have adequate personnel,

funding and authority under state law. Requirements for legal authority

are further defined in 40 CFR part 51, subpart L (51.230-232) and for

resources in 40 CFR 51.280. States and responsible local agencies must

demonstrate that they have the legal authority to adopt and enforce

provisions of the SIP and to obtain information necessary to determine

compliance. SIPs must also describe the resources that are available or

will be available to the State and local agencies to carry out the

plan, both at the time of submittal and during the 5-year period

following submittal.

Adequate Personnel and Funding. For Rule 310, the microscale plan

reflects MCESD's current bifurcated implementation strategy of

proactive compliance and enforcement on permitted sources and reactive

enforcement on nonpermitted sources. This implementation strategy is

assumed in the attainment demonstrations in which emission reductions

are assumed only from permitted sources and not from nonpermitted

sources. Plan, pp. 37-40. MCESD's available resources (both personnel

and funding) for carrying out this bifurcated strategy for Rule 310 and

its other commitments are discussed above and are adequate. MCESD

expects to maintain this level of resource commitment over the next

five years of plan implementation. Plan, p. 33.

The cities' resources for implementing their respective commitments

are also discussed above and are adequate. Each agency is expected to

maintain this level of resource commitment over the next five years of

plan implementation. Plan, pp. 35 and 36.

Adequate Legal Authority. The primary implementing agency of the

controls in the microscale plan is the County of Maricopa through its

Environmental Services Department. A.R.S. 49-479 provides that the

board of supervisors ``shall adopt such rules as it determines are

necessary and feasible to control release into the atmosphere of air

contaminants. * * *'' A.R.S. 49-476.01 provides the County control

officer the authority to require sources to monitor, sample, or

otherwise quantify their emissions and the board of supervisors the

authority to adopt rules for source monitoring, sampling, etc. These

sections provide the County and MCESD with sufficient authority under

State law to adopt and enforce the proposed control measures and to

obtain the information necessary to determine compliance.

Legal authority for the cities to adopt and implement their

resolutions are described in the microscale plan on pp. 35-36 and

appears to be adequate.

These proposed findings regarding adequate authority and resources

are applicable only to the control strategy and commitments as

submitted in the microscale plan.

3. Description of Enforcement Methods

Section 110(a)(2)(C) requires SIPs to include a program to provide

for the enforcement of SIP measures. The implementing regulation for

this section is found at 40 CFR 51.111(a) and requires control

strategies to include a description of enforcement methods including

(1) procedures for monitoring compliance with each of the selected

control measures, (2) procedures for handling violations, and (3) the

designation of the agency responsible for enforcement.

Procedures for monitoring compliance (i.e., the inspection

strategy) with Rule 310 are discussed in the section on MCESD

commitments above. MCESD is the designated agency for enforcing Rule

310. See legal authority section above.

MCESD has developed an Air Enforcement Policy (April 4, 1997). A

summary of this strategy can be found in the microscale plan, Appendix

E, Bell letter. Currently, the Department issues Notices of Violations

(NOVs) whenever violations of rules are observed (Plan, p. 12) and will

continue to do so. Orders of abatement will be issued after NOVs when

compliance is not attainable within a reasonable time frame. Additional

enforcement actions may be initiated based on several factors including

actual or significant potential harm or willful noncompliance. The

additional actions include filing criminal or civil complaints.

Appropriate monetary penalties will be sought for criminal or civil

complaints and the Department encourages Environmental Community Action

Projects as part of settlements. Plan, Appendix E, Bell letter.

EPA has also encouraged MCESD to take more enforcement actions with

monetary penalties in order to make clear to the regulated community

that compliance with Rule 310 should be a priority and to develop a

system for tracking the number of NOVs and monetary penalties. See

letter, Frances Wicher, EPA, to Joe Gibbs, ADEQ, April 30, 1997 (found

in the Plan, Appendix D). In all, the Department's Air Enforcement

Policy is adequate to meet the requirements of 40 CFR 51.111(a) and CAA

section 110(a)(2)(C).

III. Summary of Proposed Action

A. Proposed Approvals and Disapprovals

For the reasons discussed above, EPA is proposing to approve:

(1) Under sections 172(c)(1), 189(a)(1)(C) and 189(b)(1)(B), the

provisions for implementing RACM and BACM for the significant source

categories of disturbed cleared areas, earth moving, and industrial

haul roads; and

(2) Under sections 189(a)(1)(B), 189(b)(1)(A), and 189(c), the

attainment and RFP demonstrations for the Maryvale and Salt River

sites.

For the reasons discussed above, EPA is proposing to disapprove:

(1) Under sections 172(c)(1), 189(a)(1)(C) and 189(b)(1)(B), the

provisions for implementing RACM and BACM for the significant source

categories of agricultural fields, agricultural aprons, vacant lands,

unpaved parking lots, and unpaved roads; and

(2) Under sections 189(a)(1)(B), 189(b)(1)(A), and 189(c)(1), the

attainment and RFP demonstrations at the West Chandler and Gilbert

sites.

Finally, EPA is proposing to find that the microscale plan (1)

provides the necessary assurances that the state and local agencies

have adequate personnel, funding and authority under state law to carry

out the submitted microscale plan, and (2) includes an adequate

enforcement program, as required by CAA sections 110(a)(2)(E)(i) and

110(a)(2)(C).

B. Consequences of the Proposed Disapprovals

As noted before, EPA required submittal of a microscale plan

meeting both the moderate and serious area requirements for the 24-hour

PM-10 standard by May 9, 1997 and a full regional plan meeting those

requirements for both the 24-hour and annual standards by December 10,

1997. The microscale and regional plans taken together would satisfy

both the moderate area requirements for the 24-hour standard mandated

by the Ninth Circuit in Ober and the serious area planning requirements

for both standards. The subject of this proposed action is the

microscale plan only; the full regional plan is not due until late

1997. It is, therefore, premature to

[[Page 31037]]

determine if the microscale plan, in and of itself, fully complies with

the Clean Air Act requirements for moderate and serious PM-10

nonattainment areas. Such a determination is not possible until the

regional plan is submitted and reviewed.

Because the microscale plan taken alone is not intended to fully

comply with the RACM/BACM implementation, reasonable further progress

and attainment demonstration requirements of the Clean Air Act, final

disapprovals of portions of the microscale plan would not trigger

sanctions under CAA section 179(a). CAA section 179(a) requires the

imposition of one of the sanctions in section 179(b) within 18 months

of a disapproval if EPA ``disapproves a [State] submission * * * based

on the submission's failure to meet one or more of the elements

required by [the CAA].'' Because the purpose of the microscale plan was

to, in effect, provide a down payment towards meeting certain

requirements of the Act, EPA is not, at this time, proposing to find

that the State has failed to meet any of the applicable elements

required by the CAA as contemplated by section 179(a).

EPA is subject to the terms of a consent decree approved by the

U.S. District Court for the District of Arizona on March 25, 1997. Ober

v. Browner, No. CIV 94-1318 PHX PGR. The consent decree obligates EPA

to propose a federal implementation plan (FIP) for PM-10 in the

Maricopa nonattainment area by March 20, 1998 and finalize that FIP by

July 18, 1998 27 if the Agency disapproves all or part of

the microscale plan. Therefore, if EPA finalizes the proposed

disapprovals described above, EPA will have an obligation to promulgate

a regional moderate area PM-10 FIP that addresses the statutory

requirements for attainment, RACM and RFP. Under the consent decree,

the scope of this FIP obligation is reduced to the extent that EPA

approves by July 18, 1998 SIP provisions meeting the statutory

requirements for RACM, RFP and attainment for moderate PM-10

nonattainment areas.

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

\27\ The FIP deadlines each advance 2 months if EPA fails to act

on the microscale plan by July 18, 1997.

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

EPA believes, as is expressed in CAA section 101(a), that air

pollution control is primarily the responsibility of states and local

jurisdictions. Therefore, the Agency will work with the State of

Arizona and the local agencies and jurisdictions responsible for PM-10

planning and control in Maricopa County to develop SIP provisions that

can reduce the scope of, or eliminate, any potential FIP. Considerable

work is already underway or planned in the area to address the PM-10

problem. As noted before, the full serious area regional PM-10 plan is

due December 10, 1997. In addition, the microscale plan contains two

initiatives, MCESD's regional program to address controls on

nonpermitted sources and the ADEQ/MCESD/NRCS agreement to address

fugitive dust from agricultural sources, that are targeted at

significant but currently uncontrolled sources of PM-10.

IV. Administrative Requirements

A. Executive Order 12866

This action has been classified as a Table 3 action for signature

by the Regional Administrator under the procedures published in the

Federal Register on January 19, 1989 (54 FR 2214-2225), as revised by a

July 10, 1995 memorandum from Mary Nichols, Assistant Administrator for

Air and Radiation. The Office of Management and Budget (OMB) has

exempted this regulatory action from E.O. 12866 review.

B. Regulatory Flexibility Act

Under the Regulatory Flexibility Act, 5 U.S.C. Sec. 600 et seq.,

EPA must prepare a regulatory flexibility analysis assessing the impact

of any proposed or final rule on small entities. 5 U.S.C. Secs. 603 and

604. Alternatively, EPA may certify that the rule will not have a

significant impact on a substantial number of small entities. Small

entities include small businesses, small not-for-profit enterprises,

and government entities with jurisdiction over populations of less than

50,000.

SIP approvals under sections 110 and 301, and subchapter I, part D

of the CAA do not create any new requirements but simply act on

requirements that the State is already imposing. Therefore, because the

Federal SIP approval does not impose any new requirements, I certify

that it does not have a significant impact on any small entities

affected. Moreover, due to the nature of the Federal-State relationship

under the CAA, preparation of a flexibility analysis would constitute

Federal inquiry into the economic reasonableness of State action. The

Clean Air Act forbids EPA to base its action concerning SIPs on such

grounds. Union Electric Co. v. U.S. EPA, 427 U.S. 246, 255-66 (1976);

42 U.S.C. Sec. 7410(a)(2).

C. Unfunded Mandates

Under section 202 of the Unfunded Mandates Reform Act of 1995

(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA

must prepare a budgetary impact statement to accompany any proposed or

final rule that includes a Federal mandate that may result in estimated

costs to State, local, or tribal governments in the aggregate; or to

private sector, of $100 million or more. Under section 205, EPA must

select the most cost-effective and least burdensome alternative that

achieves the objectives of the rule and is consistent with statutory

requirements. Section 203 requires EPA to establish a plan for

informing and advising any small governments that may be significantly

or uniquely impacted by the rule.

EPA has determined that the approval/disapproval action proposed

does not include a Federal mandate that may result in estimated costs

of $100 million or more to either State, local, or tribal governments

in the aggregate, or to the private sector. This Federal action

approves pre-existing requirements under State or local law, and

imposes no new Federal requirements. Accordingly, no additional costs

to State, local, or tribal governments, or to the private sector,

result from this action.

List of Subjects in 40 CFR Part 52

Environmental protection, Air pollution control, Particulate

matter, Incorporation by reference.

Authority: 42 U.S.C. 7401.

Dated: May 29, 1997.

Felicia Marcus,

Regional Administrator.

[FR Doc. 97-14848 Filed 6-5-97; 8:45 am]

BILLING CODE 6560-50-P