Federal Register/Vol. 65, No. 72/Thursday, April 13, 2000/Proposed Rules

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Part 52

[AZ092-002; FRL-6575-3]

Approval and Promulgation of

Implementation Plans; ArizonaMaricopa County PM-10

Nonattainment Area; Serious Area Plan

for Attainment of the Annual PM-10

Standard

AGENCY: Environmental Protection

Agency (EPA).

ACTION: Proposed rule.

SUMMARY: EPA proposes to approve

provisions of the Revised MAG 1999

Serious Area Particulate Plan for PM-10

for the Maricopa County (Phoenix)

Nonattainment Area, February 2000,

and the control measures on which it

relies, that address the annual PM-10

national ambient air quality standard.

We also propose to grant Arizona's

request to extend the Clean Air Act

deadline for attaining the annual PM-10

standard in the Phoenix area from 2001

to 2006. Finally, we propose to approve

two particulate matter rules adopted by

the Maricopa County Environmental

Services Department and Maricopa

County's Residential Woodburning

Restrictions Ordinance.

DATES: Comments on this proposal must

be received in writing by June 12, 2000.

Comments should be addressed to the

contact listed below.

ADDRESSES: Comments may be mailed

to: Frances Wicher, Office of Air

Planning (AIR-2), EPA Region 9, 75

Hawthorne Street, San Francisco, CA

94105-3901.

A copy of docket No. AZ-MA-00-

001, containing the technical support

document (TSD) and other material

relevant to EPA's proposed action, is

available for public inspection at EPA's

Region 9 office during normal business

hours.

A copy of the docket is also available

for inspection at: Arizona Department of

Environmental Quality, Library, 3033 N.

Central Avenue, Phoenix, Arizona

85012, (602) 207-2217. Maricopa

Association of Governments, 302 North

1st Street, Phoenix, Arizona 85003,

(602) 254-6300.

Electronic Availability

This document and the Technical

Support Document (TSD) are also

available as electronic files on EPA's

Region 9 Web Page at http://

www.epa.gov/regiono9/air.

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)

744-1238, email:

wicher.frances@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

Summary of Today's Proposals

Summary of the MAG Plan

PM-10 Air Quality in the Phoenix

Metropolitan Area

A. The Maricopa Nonattainment Area and its

PM-10 Air Quality

B. PM-10 Air Quality Planning in the

Phoenix Metropolitan Area

C. Clean Air Act Sanctions on the Phoenix

Area

The Clean Air Act's Planning Requirements

for Serious PM-10 Areas and EPA's

Guidance on Meeting these Requirements

A. Implementation of Best Available Control

Measures

B. Implementation of Reasonably Available

Control Measures

C. Extension of the Attainment Date beyond

2001

1. Apply for an attainment date extension

2. Demonstrate that attainment by 2001 is

impracticable

3. Complied with all requirements and

commitments in its implementation plan

4. Demonstrate the inclusion of the most

stringent measures

5. Demonstrate attainment by the most

expeditious alternative date practicable

D. Separating Our Rulemaking Actions on the

Annual and 24-hour Standards

Discussion of the MAG Plan's Compliance

with Clean Air Act Requirements

A. Completeness of the SIP Submittals

B. Adequacy of the Transportation

Conformity Budgets

C. Emission Inventory

D. Adequate Monitoring Network

E. Contribution to PM-10 Exceedances of

Major Sources of PM-10 Precursors

F. Implementation of Reasonably Available

and Best Available Control Measures

1. Determination of significant sources

2. Identification of potential BACM

3. Implementation of RACM and BACM

and inclusion of MSM for each

significant source category

a. Technology controls for on-road motor

vehicle exhaust

b. Transportation control measures (TCMs)

for on-road motor vehicle exhaust and

paved road dust

c. Nonroad engines

d. Paved road dust

e. Unpaved parking lots

I. Disturbed vacant lands

g. Unpaved roads

h. Construction sites and activities

i. Agricultural sources

j. Residential wood combustion

k. Secondary ammonium nitrate

1. MCESD's commitments to improve

compliance and enforcement of its

fugitive dust rules

G. Attainment Date Extension

1. Apply for an extension

2. Demonstrate the impracticability of

attainment by December 31, 2001

3. Complied with the commitments and

requirements in the SIP

4. Include the most stringent measures

5. Demonstrate expeditious attainment

a. Air quality modeling b. Control

measures relied on for attainment

6. Other factors that EPA may consider

a. Nature and extent of nonattainment

b. Types and number of sources or other

emitting activities

c. Population exposure to concentrations

above the standard

d. Presence and concentration of

potentially toxic substances in the

particulate

e. Technological and economic feasibility

of controls

7. Conclusion on the extension request

H. Reasonable Further Progress (RFP) and

Quantitative Milestones

1. Reasonable further progress

2. Quantitative milestones

I. General SIP Requirements

Proposed Action on Maricopa County Rules

A. Rule 310

B. Rule 310.01

C. Residential Woodburning Restriction

Ordinance

D. CAA Section 110(1) Finding

Administrative Requirements

Summary of Today's Proposals

We are proposing to approve the

serious area air quality plan for

attainment of the annual PM-10

standard in the Phoenix, Arizona,

metropolitan area.1 Our proposed

actions are based on our initial

determination that this plan complies

with the Clean Air Act's requirements

for attainment of the annual PM-10

standard in serious PM-10

nonattainment areas.

Specifically, we propose to approve

the following elements of the plan as

they apply to the annual PM-10

standard:

* the base year emissions inventory of

PM-10 sources,

* the demonstration that the plan

provides for implementation of

reasonably available control measures

(RACM) and best available control

measures (BACM),

* the demonstration that attainment

of the PM-10 annual standard by the

Clean Air Act deadline of December 31,

2001 is impracticable,

* the demonstration that attainment

of the PM-10 annual standard will

occur by the most expeditious

alternative date practicable, in this case,

December 31, 2006,

'There are two separate national ambient air

quality standards (NAAQS) for PM-10, an annual

standard of 50 pg/m 3 and a 24-hour standard of 150

pg/m 3.

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* the demonstration that the plan provides for reasonable further progress

and quantitative milestones,

* the demonstration that the plan

includes to our satisfaction the most

stringent measures found in the

implementation plan of another state or

are achieved in practice in another state,

and can feasibly be implemented in the

area.

* the demonstration that major

sources of PM-10 precursors such as

nitrogen oxides and sulfur dioxide do

not contribute significantly to violations

of the annual PM-10 standard, and

* the transportation conformity

budget.

We are also proposing to grant

Arizona's request to extend the

attainment date for the annual PM-10

standard from December 31, 2001 to

December 31, 2006.

Finally, we are proposing to approve

Maricopa County's fugitive dust rules,

Rules 310 and 301.01, and its residential

woodburning restriction ordinance.

This preamble describes our proposed

actions on the Phoenix area plan and

provides a summary of our evaluation of

the plan. Our detailed evaluation of the

plan can be found in the technical

support document ("EPA TSD") that

accompanies this proposal. A copy of

the EPA TSD can be downloaded from

our website or obtained by calling or

writing the contact person listed above.

Summary of the MAG Plan

We are evaluating and proposing

action on the Revised Maricopa

Association of Governments 1999

Serious Area Particulate Plan for PM-10

for the Maricopa County Nonattainment

Area, February 2000 ("MAG plan").

This plan was developed by the

Maricopa Association of Governments

(MAG), the lead air quality planning

agency in Maricopa County, with the

assistance of the Maricopa County

Environmental Services Department

(MCESD), the Arizona Department of

Environmental Quality (ADEQ), and the

cities and towns in the Maricopa County

nonattainment area. ADEQ submitted

the final plan as a revision to the

Arizona State Implementation Plan (SIP)

on February 16, 2000.

We are also evaluating and proposing

action on the December 11, 1997

submittal of Serious Area Committed

Particulate Control Measures for PM-10

for the Maricopa County Nonattainment

Area and Support Technical Analysis,

MAG, December 1997. This submittal

contains additional control measures

that are relied on in the MAG plan. We

consider the measures in this submittal

to be part of the MAG plan and have

evaluated them as such.

Finally, we are also evaluating and

proposing to act on the most recent

revisions to MCESD's Rule 310, Fugitive

Dust Sources (adopted February 16,

2000) and Rule 310.01, Fugitive Dust

from Open Areas, Vacant Lots, Unpaved

Parking Lots, and Unpaved Roadways

(adopted February 16, 2000). We are

also proposing to approve the revised

Maricopa County Residential

Woodburning Restrictions Ordinance

(adopted November 17, 1999).

As submitted, the revised MAG plan

consists of the main plan document,

four volumes of technical appendices,

and four volumes of commitments from

various agencies to implement PM-10

controls. The plan contains a 1994

regional PM-10 emissions inventory

and uses the urban airshed model/

limited chemistry version (UAM/LC) to

model air quality in 1995 as a base year

and in 2006 as the attainment year. The

plan includes a BACM analysis and a

demonstration that attainment by 2001

is impracticable. It also includes the

State's request for a five year extension

of the attainment date, a demonstration

that the plan provides for the most

stringent measures found in other areas'

plans or used in practice, and a

demonstration of attainment by

December 31, 2006. The plan shows that

the principal sources contributing to

PM-10 exceedances in the Phoenix area

are fugitive dust sources, such as

construction sites, vacant lots, paved

and unpaved roads, and various other

dust sources. The principal controls

relied on for attainment are controls on

these fugitive dust sources.

The MAG plan addresses both the

annual and 24-hour PM-10 standards.

We are not at this time proposing any

actions regarding the plan's compliance

with the statutory requirements relating

to the 24-hour standard. As we explain

in more detail later, the annual PM-10

standard is a separate air quality

standard from the 24-hour one;

therefore, we can and must separately

evaluate a plan's compliance with the

statutory requirements for each

standard. We do not need to do these

reviews concurrently.

The MAG plan also contains

contingency measures as required by

CAA section 172(c)(9). We are not

proposing action on these contingency

measures at this time. Contingency

measures are a distinct provision of the

Clean Air Act that we may act on

separately from the attainment

requirements.

PM-10 Air Quality in the Phoenix

Metropolitan Area

A. The Maricopa Nonattainment Area

and its PM-1 0 Air Quality

The Maricopa County (Phoenix) PM10 nonattainment area is located in the

eastern portion of Maricopa County and

encompasses the cities of Phoenix,

Mesa, Scottsdale, Tempe, Chandler,

Glendale as well as 17 other

jurisdictions and considerable

unincorporated County lands.2 40 CFR

81.303. The area is home to almost 3

million people.

The area violates both the annual and

24-hour PM-10 standards. In 1990, the

area was designated nonattainment for

PM-10 and classified as moderate. In

1996, because of continuing violations

of both PM-10 standards, the area was

reclassified to serious. 61 FR 21372

(May 10, 1996).

As noted before, the principal

contributors to elevated PM-10 levels in

the Phoenix area are fugitive dust

sources such as construction sites,

unpaved roads, vacant lots and paved

road dust. Also contributing to the PM10 problem, but to a much lesser degree

than fugitive dust, are internal and

external combustion sources including

directly-emitted PM-10 from

automobiles, trucks, construction

equipment, bus, residential

woodburning and industrial,

commercial, and residential use of

natural gas and fuel oil. See MAG plan,

3-5.

B. PM-I 0 Air Quality Planning in the

Phoenix Metropolitan Area

The MAG plan is the latest in a series

of air quality plans addressing the PM10 problem in Phoenix. These previous

plans are:

* 1991 MAG Moderate Area Plan.

Arizona submitted this plan in 1991 and

revisions to it in 1993 and 1994. The

1991 plan contained a demonstration

that attainment was impracticable by

the CAA's deadline for moderate areas,

December 31, 1994. We initially

approved this plan in 1995 (60 FR

18010 (April 10, 1995)); however, the

9th Circuit Court of Appeals vacated our

approval in 1996, finding among other

things that the plan did not address the

24-hour PM-10 standard. Oberv. EPA,

84 F.3d 304 (9th Cir. 1996). In 1998, we

disapproved the 1991 plan's reasonably

available control measure (RACM)

demonstration for the annual standard

because the plan failed to provide for

the implementation of RACM on

2 The Maricopa nonattainment area also includes

the town of Apache Junction in Pinal County.

Apache Junction is covered by a separate air quality

plan and will be addressed in a later action.

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number of significant sources of PM-10,

including unpaved roads. The failure to

provide for the implementation of

RACM also meant that the plan could

no longer conclusively demonstrate the

impracticability of attainment of the

annual standard by December 31, 1994,

so we also disapproved the

impracticability demonstration. 63 FR

15919, 15925 (April 1, 1998).

* Microscale Plan. Arizona submitted

this plan in 1997 as a response to the

9th Circuit's findings in Ober. The plan

addressed the CAA's serious area PM10 requirements for attaining the 24-

hour standard around four

representative air quality monitors (that

is, at four localized or "microscale"

sites) in the Phoenix area. It found that

24-hour exceedances in the Phoenix

area are mainly caused by fugitive dust

from construction, agriculture, unpaved

roads and parking lots, and disturbed

vacant land. We approved the plan in

part but also disapproved it in part

because it did not provide for the

implementation of RACM or BACM on

agricultural sources, unpaved roads,

unpaved parking lots, and disturbed

vacant lots and did not demonstrate

attainment at two of the four sites. 62 FR

41856 (August 4, 1997).

* 1998 Moderate Area Federal

Implementation Plan (FIP). We

promulgated this plan on August 3,

1998. It provided for the

implementation of RACM on the

significant sources-unpaved roads,

unpaved parking lots, disturbed vacant

lots, and agricultural sources-left

unaddressed by the 1991 MAG

moderate area plan and the Microscale

plan.3 The FIP demonstrated that the

implementation of RACM was

insufficient for attainment of the 24-

hour and annual standards by Phoenix

area's attainment deadline of December

31, 2001. 4 63 FR 41326 (August 3,

1998).

A more detailed history of PM-10

planning in the Phoenix area can be

found in the EPA TSD.

3 The FIP's requirements for unpaved roads,

unpaved parking lots and disturbed vacant lots are

codified at 40 CFR 52.128. We withdrew the FIP's

agricultural requirements, formerly codified at 40

CFR 5 2.127, when we approved similar State

requirement in 1999. 64 FR 34726 (June 29, 1999). 4 At the time we promulgated the FIP in 1998, the

moderate PM-10 area deadline of December 31,

1994 had passed and we had reclassified the

Phoenix area to serious. As a result the only

statutory attainment deadline then applicable to the

Phoenix area, and thus the deadline applicable to

our moderate area FIP, was the serious area

deadline, i.e., as expeditiously as practicable but

not later than December 31, 2001. See 63 FR 15919,

15926.

C. Clean Air Act Sanctions on the

Phoenix Area

Our 1998 disapprovals of parts of the

1991 MAG moderate area plan started

sanction clocks under CAA section

179(a). Under section 179(a), once we

disapprove a SIP provision because it

fails to meet a CAA requirement, a State

has 18 months to correct the deficiency

that resulted in the disapproval before

the first of two sanctions goes into

place. If the state still has not corrected

the deficiency within 24 months of the

disapproval, the second sanction goes

into place.

The two CAA sanctions are a

limitation on certain highway approvals

and funding and an increase in the

offset ratio to 2 to 1 for any major new

stationary source or major modification.

See CAA section 179(b). Our sanctions

regulations provide that the first

sanction to be imposed is the offset ratio

unless we have established at the time

of the disapproval that the highway

sanction will be first. 40 CFR 52.31(d).

On August 3, 1998, we published our

disapprovals of the RACM and

attainment demonstrations for the

annual standard in the 1991 MAG

moderate area plan. 63 FR 41326. When

these disapprovals became effective 30

days later on September 2, 1998, the

sanction clocks started. The first of

these sanction clocks expired on March

2, 2000 and the 2:1 offset sanction is

now in place in the Phoenix area. The

second sanction clock for the highway

funding limitations is set to expire on

September 2, 2000.

Under section 179(a) and our

sanctions regulations at 40 CFR

52.31(d)(1), we must approve a SIP

revision that corrects the deficiencies to

permanently end the sanctions clocks

and lift any imposed sanctions.

However, we may temporarily stay the

clocks and any imposed sanctions if we

propose to approve a SIP revision that

corrects the deficiencies and have

issued an interim final determination

that the State has corrected the

deficiencies. 40 CFR 52.31(d)(2)(i).

In a rule being published concurrently

with this proposal, we are issuing an

interim final determination that, based

our proposed findings here, Arizona has

more than likely corrected the

deficiencies that resulted in our August

1998 disapprovals.

The Clean Air Act's Planning

Requirements for Serious PM-10 Areas

and EPA's Guidance on Meeting these

Requirements

The Phoenix area is a PM-10

nonattainment area that has been

reclassified to serious because it failed

to attain by the moderate area

attainment date of December 31, 1994.

Such an area must submit, within 18

months of the reclassification, revisions

to its implementation plan that address

the CAA requirements for serious PM10 nonattainment areas. CAA section

189(b)(2). These requirements are:

(a) assurances that best available

control measures (BACM) 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)); 5

(b) assurances that best available

control technology (BACT) on major

stationary sources of PM-10 precursors

shall be implemented no later than 4

years after the area is reclassified 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, or, where the State

is seeking an extension of the

attainment date under section 188(e), a

demonstration that attainment by

December 31, 2001 is impracticable

(CAA sections 188(c)(2) and

189(b)(1)(A));

(d) quantitative milestones which are

to be achieved every 3 years and which

demonstrate reasonable further progress

(RFP) toward attainment by the

applicable attainment date (CAA

sections 172(c)(2) and 189(c)); and

(e) a comprehensive, accurate, current

inventory of actual emissions from all

sources of PM-10. (CAA sections

1 72(c)(3)).

Serious area PM-10 plans must also

meet the general requirements

applicable to all SIPs including

reasonable notice and public hearing

under section 110(1), necessary

assurances that the implementing

agencies have adequate personnel,

funding and authority under section

110(a)(2)(E)(i) and 40 CFR 51.280; and

the description of enforcement methods

as required by 40 CFR 51.111.

Except for the requirements for the

implementation of RACM and BACM

and for extension requests, we will

discuss our policies for each of these

requirements when we discuss our

evaluation of that section of the MAG

plan later in this preamble.

5 When a moderate area is reclassified to serious,

the requirement to implement RACM in section

189(a)(1)(C) remains and is augmented by the

requirement to implement BACM. Thus, a serious

area PM-10 plan must, in addition to BACM,

provide for the implementation of RACM as

expeditiously as practicable to the extent that the

RACM requirement has not been satisfied in the

area's moderate area plan.

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We have issued a General Preamble,

57 FR 13498 (April 16, 1992) and 57 FR

18070 (April 28, 1992), and Addendum

to the General Preamble ("Addendum"),

59 FR 41998 (August 16, 1994),

describing our preliminary views on

how we intend to review SIPs submitted

to meet the Clean Air Act's

requirements for PM-10 plans. We have

also issued other guidance documents

related to PM-10 plans or provisions of

these plans. These other guidance

documents will be cited as appropriate.

A. Implementation of Best Available

Control Measures

Under section 189(b)(2), serious area

PM-10 plans must provide assurances

that BACM will be implemented in the

area no later than four years after the

area is reclassified as serious. For

Phoenix, the BACM implementation

deadline is June 10, 2000.

The Act does not define what

constitutes BACM. We consider BACM

to be a particular level of control, in this

case the best, on a source or source

category. More specifically, we have

defined BACM to be, among other

things, the maximum degree of emission

reductions achievable from a source or

source category which is determined on

a case-by-case basis, considering energy,

economic and environmental impacts.

Addendum at 42010. We also consider

BACM as going beyond existing RACMlevel controls, such as expanding the

use of RACM controls (e.g., paving more

miles of unpaved roads). Addendum at

42013. Additionally, we believe that

BACM should emphasize prevention

rather than remediation (e.g., preventing

track out at construction sites rather

than simply requiring clean up of

tracked-out dirt). Addendum at 42013.

A serious area plan must provide for

the implementation of BACM on each

significant (i.e., non-de minimis) source

category. Addendum at 42011. In

guidance, we have established a

presumption that a "significant" source

category is one that contributes 1 gLg/m 3

or more of PM-10 to a location of an

annual standard violation. Addendum

at 42011. However, whether the

threshold should be lower than this in

any particular area depends upon the

specific facts of that area's

nonattainment problem. Specifically, in

areas that are demonstrating attainment

by December 31, 2001, it depends on

whether requiring the application of

BACM on source categories below a

proposed de minimis level would

meaningfully expedite attainment. In

areas that are claiming the

impracticability of attainment by

December 31, 2001, it depends upon

whether requiring the application of

BACM on source categories below a

proposed de minimis level would make

the difference between attainment and

nonattainment by the serious area

deadline of December 31, 2001. 6

We have outlined in our guidance a

multi-step process for identifying

BACM. Addendum at 42010-42014. The

steps are:

1. develop a detailed emission

inventory of PM-10 sources and source

categories,

2. model to evaluate the impact on

PM-10 concentrations over the

standards of the various sources and

source categories to determine which

are significant,

3. identify potential BACM for

significant source categories including

their technological feasibility, costs, and

energy and environmental impacts if

needed to determine BACM, and

4. provide for the implementation of

the BACM or provide a reasoned

justification for rejecting any potential

BACM.

B. Implementation of Reasonably

Available Control Measures

When a moderate area is reclassified

to serious, the requirement to

implement RACM in section

189(a)(1)(C) remains. Thus, a serious

area PM-10 plan must also provide for

the implementation of RACM as

expeditiously as practicable to the

extent that the RACM requirement has

not been satisfied in the area's moderate

area plan.

However, we do not normally conduct

a separate evaluation to determine if a

serious area plan's measures also meet

the RACM requirements as interpreted

by us in the General Preamble at 13540.

This is because in our serious area

guidance (Addendum at 42010), we

interpret the BACM requirement, as

generally subsuming the RACM

requirement (i.e. if we determine that

the measures are indeed the "best

available," we have necessarily

concluded that they are "reasonably

available"). Therefore, a separate

analysis to determine if the measures

represent a RACM level of control is not

necessary. Consequently, our proposed

approval of the MAG plan's provisions

6 This principle is best illustrated by an example:

In Area A, attainment of the annual standard by

December 31, 2001 requires that total PM-10

emissions in the area be reduced to 200 tons per

day (tpd). After application of BACM to all source

categories above the proposed de minimis level,

total emissions in the area are reduced to 220 tpd.

BACM on the proposed de minimis source

categories would reduce total emissions a further 5

tons to 215 tpd. Since application of BACM to the

proposed de minimis source categories still leaves

emissions above the attainment level of 200 tpd, the

proposed de minimis level is appropriate.

relating to the implementation of BACM

is also a proposed finding that the plan

provides for the implementation of

RACM.

C. Extension of the Attainment Date

Beyond 2001

Section 188(e) of the Act allows us to

extend the attainment date for a serious

area for up to five years beyond 2001 if

attainment by 2001 is impracticable.

However, before we may grant an

extension of the attainment date, the

State must first:

1. apply to us for an extension of the

PM-10 attainment date beyond 2001,

2. demonstrate that attainment by

2001 is impracticable,

3. have complied with all

requirements and commitments

applying to the area in its

implementation plan,

4. demonstrate to our satisfaction that

its serious area plan includes the most

stringent measures that are included in

the implementation plan of any state

and/or are achieved in practice in any

state and are feasible for the area, and

5. submit a demonstration of

attainment by the most expeditious

alternative date practicable.

In determining whether to grant an

extension and the appropriate length of

the attainment date extension, we may

consider:

1. the nature and extent of the

nonattainment problem,

2. the types and number of sources or

other emitting activities in the area

(including the influence of

uncontrollable natural sources and

international transport),

3. the population exposed to

concentrations in excess of the standard,

4. the presence and concentration of

potentially toxic substances in the mix

of particulate emissions in the area, and

5. the technological and economic

feasibility of various control measures.

We may grant only one extension for

an area and that extension cannot be for

more than 5 years after 2001; that is, the

extended attainment date can be no later

than December 31, 2006. CAA section

188(e).

To date, we have not issued any

policy or regulation interpreting the

attainment date extension requirements

for urban areas like Phoenix. Therefore,

before reviewing Arizona's request for

an extension, we will first discuss how

we propose to interpret section 188(e).

The following is our preliminary

interpretation of the section 188(e)

requirements and we request comment

on it. We emphasize that this is our

preliminary view and it is subject to

modification as we gain more

experience reviewing on extension

requests from other areas.

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We have listed above the five

requirements a State must meet before

we can consider granting an attainment

date extension. We discuss each

requirement in order:

1. Apply for an Attainment Date

Extension

The State must apply in writing to

EPA for an extension of the attainment

deadline. The request should

accompany the SIP submittal containing

the most expeditious alternative

attainment demonstration. The public

must be provided reasonable notice and

a public hearing on the request before it

is submitted.

Extension requests are not SIP

submittals per se and are therefore not

subject to the requirements of the Clean

Air Act and our regulations for public

notice and hearing on SIP revisions.

However, because they can greatly affect

the content and ultimate approvability

of a serious area PM-10 plan, we believe

a state must give the public an

opportunity, consistent with the

requirements for SIP revisions, to

comment on an extension request prior

to submitting it to us.

2. Demonstrate That Attainment by 2001

is Impracticable

In order to demonstrate

impracticability, the plan must show

that the implementation of BACM (as

determined by our guidance) on

significant source categories will not

bring the area into attainment by

December 31, 2001. BACM is the

required level of control for serious

areas that must be in place before the

2001 attainment date; therefore, we

believe that it is reasonable to interpret

the Act to require that a state provide for

at least the implementation of BACM on

significant source categories before it

can claim impracticability of attainment

by 2001. This interpretation parallels

our interpretation of the impracticability

option for moderate PM-10

nonattainment areas in section

189(a)(1)(B). In moderate areas, RACM

was required before a moderate area

plan could show impracticability of

attainment by 1994, the moderate area

attainment deadline. General Preamble

at 13544.

The statutory provision for

demonstrating impracticability requires

that the demonstration be based on air

quality modeling. See section

189(b)(1)(A).

3. Complied With all Requirements and

Commitments in its Implementation

Plan

We interpret this criterion to mean

that the State has implemented the

control measures in the SIP revisions it

has submitted to us to address the CAA

requirements in sections 172 and 189

for PM-10 nonattainment areas.

We read this provision not to require

the area to have a fully approved SIP

that meets the CAA's requirements for

moderate areas. We base this reading on

the plain language of section 188(e)

which requires the state to comply with

all requirements and commitments

pertaining to that area in the

implementation plan but does not

require that the state comply with all

requirements pertaining to the area in

the Act. For the same reason we also

read this provision not to bar an

extension if all or part of an area's

moderate area plan is disapproved or

has been promulgated as a FIP.

4. Demonstrate the Inclusion of the Most

Stringent Measures

The fourth extension criterion

requires the State to "demonstrate to the

satisfaction of the Administrator that the

plan for the area includes the most

stringent measures that are included in

the implementation plan of any State, or

are achieved in practice in any State,

and can feasiblely be implemented in

the area." CAA section 188(e).

The requirement for most stringent

measures (MSM) is similar to the

requirement for BACM. We define

BACM to be, among other things, the

maximum degree of emission reduction

achievable from a source or source

category which is determined on a case

by case basis considering energy,

economic and environmental impacts.

Addendum at 42010. The Act

establishes the deadline for

implementing BACM as four years after

an area's reclassification to serious.

CAA section 189(b)(1)(A).

We proposed to define a "most

stringent measure" in a similar manner:

the maximum degree of emission

reduction that has been required or

achieved from a source or source

category in other SIPs or in practice in

other states and can feasiblely be

implemented in the area. The Act does

not specify an implementation deadline

for MSM. Because the clear intent of

section 188(e) is to minimize the length

of any attainment date extension, we

propose that the implementation of

MSM should be as expeditiously as

practicable.

Given this similarity between the

BACM implementation and MSM

requirements, we believe that

determining MSM should follow a

process similar to determining BACM,

but with one additional step, to compare

the potentially most stringent measure

against the measures already adopted in

the area:

1. develop a detailed emission

inventory of PM-10 sources and source

categories,

2. model to evaluate the impact on

PM-10 concentrations over the

standards of the various source

categories to determine which are

significant for the purposes of adopting

MSM,

3. identify the potentially most

stringent measures in other

implementation plans or used in

practice in other States for each

significant source category and, for each

measure, determine their technological

and economic feasibility for the area,

4. compare the potentially most

stringent measures for each significant

source category against the measures, if

any, already adopted for that source

category, and

5. provide for the adoption and

expeditious implementation of any

MSM that is more stringent than

existing measures or, in lieu of

adoption, provide a reasoned

justification for rejecting the potential

MSM, i.e., why such measures cannot

be feasiblely implemented in the area.

The level of control resulting from a

most stringent measure depends on how

well other areas have chosen to control

their sources. If a source category has

not been well controlled in other areas

then MSM may in fact result in a rather

low level of control. This contrasts with

BACM which is determined

independently of what other areas have

done and depends only on what is the

best level of control feasible for an area.

Because BACM is the best level of

control feasible for an area, it would be

easy for the MSM requirement to result

in no more controls and no more

emission reductions in an area than

result from the implementation of

BACM. Given the strategy in the

nonattainment provisions of the Act to

offset longer attainment time frames

with more stringent control

requirements, we need to interpret the

MSM provision to assure that it results

in additional controls beyond the set of

measures adopted as BACM. The

primary ways to do this are (1) to

require that more sources and source

categories be subject to MSM analysis

than to BACM analysis, that is, by

lowering the threshold for what is

considered a de minimis source

category and (2) to require reanalysis of

any measures garnered from other areas

that were rejected during the BACM

analysis because they could not be

implemented by the BACMimplementation deadline to see if they

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are now feasible for the area given the

longer attainment date.

De Minimis Thresholds. What

constitutes a de minimis source category

for BACM is dependent upon the

specific facts of the nonattainment

problem under consideration. In

particular, it depends upon whether

requiring the application of BACM for

such sources would make the difference

between attainment and nonattainment

by the serious area deadline. We

propose to use a similar approach for

judging what constitutes a de minimis

source category for MSM but instead of

the attainment/nonattainment test, we

propose to use a test of whether MSM

controls on the de minimis sources

would result in more expeditious

attainment.

We would not review an MSM

analysis in a plan if the plan did not

demonstrate expeditious attainment

since one prerequisite for granting an

extension is that the plan demonstrate

attainment. Therefore, any de minimis

standard for MSM that relied on the

difference between attainment and

nonattainment would be meaningless

because no additional controls are

needed for attainment beyond those

already in the plan. Our responsibility

under section 188(e), however, is to

grant the shortest practicable extension

of the attainment date by assuring the

plan provides for attainment as

expeditiously as practicable. Thus, one

means of determining an appropriate de

minimis level is to determine if

applying MSM to the proposed de

minimis source categories would

meaningfully expedite attainment. If it

did, then the de minimis level is too

high, and if it did not, then the de

minimis level is appropriate. 7

Technological Feasibility. In the MSM

analysis, a state must evaluate the

application of controls from elsewhere

to sources in its own area. In many

cases, these sources are already subject

to local control measures. In these

situations, part of determining if a

control is technologically feasible is

determining if the new control can be

integrated with the existing controls

without reducing or delaying the

emission reductions from the existing

control. If it cannot, then we would not,

in general, consider the measure to be

technologically feasible for the area.

7 In extension areas, the applicable control

requirement after the December 31, 2001 attainment

date is the MSM and expeditious attainment

requirements of section 188(e). Thus, for measures

implemented after December 31, 2001, a state need

only show that the measure meets at minimum the

MSM level of control and, combined with all other

measures, is sufficient for expeditious attainment.

A state has no obligation to show that the measure

meets a BACM-level of control.

Economic Feasibility. Because cost is

rarely used to justify rejection of a

measure in the MAG plan, we will not

attempt to establish a general guide for

evaluating when a measure is

economically infeasible but instead will

address the issue on a case-by-case basis

as needed.

We propose to use the following

approach in evaluating the selection of

the most stringent among multiple

measures, i.e., evaluating the

determination of when one is more

stringent than another:

1. The determination will be made on

a source category basis. When only a

single measure is applicable to a source

category then we will compare the

measures directly. However, in many

cases multiple measures apply to a

single source category (e.g., unpaved

roads which in the MAG plan are

controlled both by Rule 310.01 and

through City and County commitments).

In these cases, we will evaluate the

impact of the overall control strategy on

emissions in the source category against

the impact of the overall control strategy

on the source category in other areas

and will not compare individual

measures within the source category.

2. We will review all the elements of

a rule that apply to a specific type of

source as an inseparable measure. A

rule's applicability and emission

limitations (as they apply to a single

type of source) together define its

stringency. They are not separable

elements that can be compared in

isolation to another rule.

3. Because stringency is based on an

emissions level, we will not use a

measure's implementation mechanisms

(e.g., rule versus commitment), funding

level, compliance schedule, resources

available for enforcement, or other

similar items as criteria for judging

relative stringency. (We do consider

these items when judging whether the

plan provides for implementation of

MSM.)

Finally, we address how we view the

"to the satisfaction of the

Administrator" qualifier on the

requirement that the State demonstrate

that its plan includes the most stringent

measures. The presence and wording of

this qualifier indicate that Congress

granted us considerable discretion in

determining whether a plan in fact

includes MSM. Under the terms of

section 188(e), we believe that we can

still accept an MSM demonstration even

if it falls short of having every MSM

possible. To intuit the limits of this

discretion, we again look to the overall

intent of section 188(e), that we grant as

short an extension as practicable. In

concrete terms, this means that when

judging the overall adequacy of the

MSM demonstration, we will give more

weight to a failure to include MSM for

source categories that contribute the

most to the PM-10 problem in Phoenix

and to the failure to include measures

that could provide for more expeditious

attainment and less weight to a failure

to include MSM for source categories

that contribute little to the PM-10

problem and/or would not expedite

attainment.

5. Demonstrate Attainment by the Most

Expeditious Alternative Date Practicable

Section 189(b)(1)(A) requires that a

serious area plan demonstrate

attainment, using air quality modeling,

by the most expeditious date practicable

after December 31, 2001. This

demonstration is the final criterion that

must be met before we may grant an

extension request.

Our determination of whether the

plan provides for attainment by the

most expeditious date practicable will

depend on whether the plan provides

for implementation of BACM by the

BACM implementation deadline and

MSM as expeditiously as practicable.

Please see section 4 of the EPA TSD

for an additional discussion of our

proposed interpretation of the extension

requirements.

D. Separating Our Rulemaking Actions

on the Annual and 24-hour Standards

As we discussed above, there are two

PM-10 NAAQS, an annual standard of

50 gg/m 3 and a 24-hour standard of 150

gLg/m 3- In this proposed action, we are

evaluating the MAG plan only for its

compliance with the Clean Air Act's

requirements for attaining the annual

PM-10 standard. We are not, at this

time, evaluating the plan for its

compliance with the Act's requirements

for the 24-hour PM-10 standard. Under

section 110(k)(2), we have until

February 25, 2001-one year after the

completeness finding-to act on the

balance of the plan that was submitted

on February 16, 2000.

The two PM-10 standards are

independent and must be addressed

independently by states in their SIPs.

This independence was highlighted by

the Ninth Circuit Court of Appeals in

Oberv. EPA, 84 F.3d 304 (9th Cir. 1996).

In Ober, the Court was reviewing our

approval of the MAG moderate area

plan:

The general provisions of the Clean Air Act

repeatedly emphasize that implementation

plans must provide for attainment of the

NAAQS as expeditiously as practicable. For

PM-10, the EPA promulgated two separate

NAAQS-the annual standard and the 24-hour

standard-which differ in the following

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respects. First, the 24-hour standard offers

protection against dangerous short-term

exposures to high PM-10 levels, a protection

that is distinct from the protection against

chronic degradation in lung function

provided by the annual standard. Second, the sources of PM-10 violation differ for the

annual and the 24-hour: violations of the 24-

hour standard are generally caused by

localized sources such as construction

projects, whereas violations of the annual

standard tend to be caused by more diverse,

dispersed sources. Third, control measures differ in effectiveness for the 24-hour

standard and the annual standard.

These differences emphasize the

importance of viewing PM- O's two NAAQS

individually and of requiring independent

treatment of them in an implementation

plan ..... Such independent treatment

furthers the Clean Air Act's goals of

protecting health and achieve clean air.

Ober at 309 (emphasis added).

If a state must treat each PM-10

NAAQS independently in the

implementation plan, then we also must

treat each PM-10 NAAQS

independently when reviewing the

plan's compliance with the Clean Air

Act. Therefore, it is necessary for us to

review the MAG plan's compliance

against the CAA requirements as they

apply to the annual standard and again

review them against the CAA

requirements as they apply to the 24-

hour standard. There is no mandate that

we conduct these reviews concurrently

even if Arizona submitted a single

document to meet the requirements for

both standards since, effectively, we

must treat it as if it contained two

separate plans.

We have chosen not to act at this time

on the 24-hour provisions of the revised

MAG plan because the State is still

working on quantifying emission

reductions from the best management

practice measures (BMPs) intended to

reduce fugitive dust from agricultural

sources. Attainment of the 24-hour

standard in the Phoenix area, unlike the

annual standard, depends in part on

emission reductions from these BMPs.

Once Arizona quantifies the reductions,

it will revise the 24-hour attainment

demonstrations and resubmit them to

us. We expect these changes later this

year. We do not believe it is an efficient

use of our resources to act now on the

24-hour provisions currently in the

MAG plan knowing that they will be

substantially revised prior to our

statutory deadline to act on them.

Discussion of the MAG Plan's

Compliance with the Clean Air Act's

Requirements

The following sections present a

condensed discussion of our evaluation

of the MAG plan's compliance with the

applicable CAA requirements for

attainment of the annual PM-10

standard. Our complete evaluation is

found in the EPA TSD for this proposal.

We urge anyone wishing to comment on

this proposal to first review the TSD

before preparing comments. A copy of

the TSD can be downloaded from our

website or obtained by calling or writing

the contact person listed above.

A. Completeness of the SIP Submittals

The first step we take after receiving

a SIP submittal is to determine if it is

complete. CAA section 110(k)(1)(B)

requires that we review all SIPs and SIP

revisions for completeness within 60

days of receipt of the submittal. The

completeness review allows us to

quickly determine if a state has

submitted a SIP revision, including all

needed supporting material, on which

we can take action. We make

completeness determinations using

criteria we have established in 40 CFR

part 51, appendix V.

We found ADEQ's February 16, 2000

submittal (received on February 23,

2000) of the final revised MAG serious

area PM-10 plan complete. We notified

the State of our completeness

determination on February 25, 2000. See

Letter, David P. Howekamp, EPA, to

Jacqueline Schafer, ADEQ.

If we do not make a completeness

determination, a submittal becomes

complete by default 6 months after we

receive it. See 100(k)(1)(B). We did not

review the 1997 submittal of control

measures for completeness and it

became complete by default on June 15,

1998.

We found Arizona's submittals

containing MCESD's Rule 310 and

310.01 and the revised Maricopa County

residential woodburning ordinance

complete on March 31, 2000.

B. Adequacy of the Transportation

Conformity Budgets

Section 176(c) of the Clean Air Act

requires that federally funded or

approved transportation plans,

programs, and projects in nonattainment

areas "conform" to the area's air quality

implementation plans. Conformity

ensures that federal transportation

actions do not worsen an area's air

quality or interfere with its meeting the

air quality standards. We have issued a

conformity rule that establishes the

criteria and procedures for determining

whether or not transportation plans,

programs, and project conform. See 40

CFR part 93, subpart A.

One of the primary tests for

conformity is to show transportation

plans and improvement programs will

not cause motor vehicle emissions

higher than the levels needed to make

progress toward and meet the air quality

standards. The motor vehicle emissions

levels needed to make progress toward

and meet the air quality standards are

set in an area's attainment and/or

reasonable further progress (RFP) plans

and are known as the "emissions budget

for motor vehicles." Emissions budgets

are established for specific years and

specific pollutants. See 40 CFR

93.118(a).

Before an emissions budget in a

submitted SIP revision may be used in

a conformity determination, we must

first determine that it is adequate. The

criteria by which we determine

adequacy of submitted emission budgets

are outlined in our conformity rule in 40

CFR 93.118(e)(4).

The MAG plan establishes a mobile

source emissions budget of 59.7 mtpd.

This regional budget is applicable for

both the annual and 24-hour PM-10

standards. The on-road mobile portion

of the budget, which includes emissions

from reentrained road dust, vehicle

exhaust, and travel on unpaved roads, is

58.6 mtpd. The road construction

portion of the budget is 1.1 mtpd. MAG

plan, p. 8-13.

On March 30, 2000, we have found

adequate for transportation conformity

purposes this motor vehicle emission

budget. As a result of our adequacy

finding, MAG and the Federal Highway

Administration are required to use this

budget in future conformity analyses.

C. Emission Inventory

CAA section 172(c)(3) requires all

nonattainment area plans to contain a

comprehensive, accurate, and current

inventory. Our policies require that the

inventory be fully documented.

The MAG plan describes annual and

average annual day emissions for 1994

from point, area, nonroad, on-road, and

nonanthropogenic sources in the

Maricopa County portion of the 2,880

square mile nonattainment area. The

inventory includes emissions of PM-10,

PM-2.5, ammonia (NH3), nitrogen

oxides (NOx), and sulfur oxides (SOx).

The inventory shows that the

dominant sources of emissions in the

Phoenix area are paved road dust (39.1

percent), unpaved roads, (21.6 percent)

and construction-related fugitive dust

(20.1 percent). Much lower but still

important contributors are directlyemitted PM-10 from non-road engines

(7.0 percent) and on-road motor vehicles

(3.3 percent), all stationary area sources,

e.g., woodburning (6.1 percent) and

stationary point sources (2.7 percent).

MAG plan, Table 3-1.

Generally the inventories are very

well documented with the

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documentation exceeding our guidance

requirements.

Current: The base year, 1994, is a

reasonably current year, considering the

length of time needed to develop an

inventory, perform the modeling,

develop and adopt control measures,

and hold public hearings on such a large

and technically-complex plan like the

MAG plan.

Comprehensive: The MAG plan

inventories are fairly complete,

considering a few emission factors are

unknown for some of the smaller

sources of PM-10. The inventories did

not include emissions of volatile organic

compounds (VOC) which is a precursor

of secondary PM-10 because the plan

found there is a negligible impact on

ambient measurements of PM-10 from

VOC aerosol. We concur with this

finding and that VOC sources need not

be inventoried for the PM-10 plan.

Accurate: In developing the

inventory, MAG and MCESD closely

followed our guidance relative to the

use of emission factors, activity

estimates, and growth and control

factors, and the other source specific

emission estimation methodologies

(continuous emission monitoring,

annual stack tests, and mass balance

methods). Source specific methods were

used to the maximum extent possible as

they are inherently more accurate than

emission factors. The relative accuracy

of each estimate underwent the

prescribed quality assurance procedures

to eliminate all possible errors. The

inventory is thus as accurate as

inventories can be.

Because we find that the inventory is

current, comprehensive, and accurate,

we propose to approve it under CAA

section 172(c)(3).

D. Adequate Monitoring Network

CAA section 110(a)(2)(B)(i) requires

States to establish and operate air

monitoring networks to compile data on

ambient air quality for all criteria

pollutants. Our regulations in 40 CFR

part 58 establishes specific regulatory

requirements for operating air quality

surveillance networks to measure

ambient concentrations of PM-10,

including measurement method

requirements, network design, quality

assurance procedures, and in the case of

large urban areas, the minimum number

of monitoring sites designated as

National Air Monitoring Stations

(NAMS).

The MAG plan does not specifically

address the adequacy of the PM-10

monitoring network in the Phoenix area.

There is no requirement that it does. We

are reviewing the adequacy of the

monitoring network here because the

plan relies on ambient data to

characterize the extent and severity of

the PM-10 problem in the Phoenix area

and we need to assure that the

monitoring network is adequate for this

purpose.

In 1995, the base year for the air

quality modeling, there were 18

monitoring sites collecting data in the

Phoenix area, all of which were

operated in accordance with our

regulations. Most of these PM-10

monitoring sites were neighborhood

scale sites with an objective of assessing

population exposure. Given the

widespread nature of the emission

sources in the Phoenix area, we believe

this focus was appropriate and that the

network was adequate to characterize

the extent and severity of the PM-10

problem in 1995.

E. Contribution to PM-IO Exceedances

of Major Sources of PM-I 0 Precursors

Under CAA section 189(e), a state

must apply the control requirements

applicable to major stationary sources of

PM-10 to major stationary sources of

PM-10 precursors, unless we determine

such sources do not contribute

significantly to PM-10 levels in excess

of the NAAQS in the area. For the

serious area plan, a "major source " is

one that emits or has the potential to

emit over 70 English tons per year (tpy)

of sulfur oxides (SOx), nitrogen oxides

(NOx), or ammonium.

PM-10 precursors react in the

atmosphere to form "secondary"

particulate, secondary because it is not

directly emitted from the source. The

MAG plan does not provide specific

information on the impact of major

precursor sources on Phoenix PM-10

levels; however, it does provide

sufficient information on the

contribution of total secondary

particulates to PM-10 levels and the

emissions from major precursor sources

to estimate the impact.

All major stationary sources of PM-10

precursors are estimated to contribute

just 0.24 gg/m3 to the annual levels of

PM-10. See EPA TSD section, "BACT

for Major Stationary Sources of PM-10

Precursors." This contribution is less

than 0.5 percent of the annual PM-10

levels over the standard in the Phoenix

area and less than 0.5 percent of the

annual standard of 50 gg/m 3.

We believe that this small

contribution is insignificant for the

Phoenix area. PM-10 levels above the

annual standard in Phoenix are almost

exclusively caused by a few large source

categories of fugitive dust, and it is

BACM-level controls on these sources

that are the key to expeditious

attainment of the annual standard in the

Phoenix area and not controls on small

contributors such as major sources of

PM-10 precursors.

We, therefore, propose to determine

that major sources of PM-10 precursors

do not contribute significantly to PM-10

levels in excess of the PM-10 NAAQS

in the Phoenix area. As a result, Arizona

is not required to apply BACT to major

sources of PM-10 precursors in the

Phoenix area.

F. Implementation of Reasonably

Available and Best Available Control

Measures

CAA section 189(b)(1)(B) requires that

a serious area PM-10 plan provide for

the implementation of BACM within

four years of reclassification to serious.

For Phoenix, this deadline is June 10,

2000. BACM must be applied to each

significant area-wide source category.

Addendum at 42011. As discussed

above, we have established a four-step

process for evaluating BACM in serious

area PM-10 plans.

1. Determination of Significant Sources

The first step in the BACM analysis is

to develop a detailed emission

inventory of PM-10 sources and source

categories that can be used in modeling

to determine their impact on ambient air

quality. Addendum at 42012.

The MAG plan uses three modeling

studies of PM-10 sources in the Phoenix

area to identify significant source

categories. One of these studies

evaluated significant sources using

chemical mass balance (CMB) modeling

performed on monitoring samples

collected at 6 sites in 1989-1990. The

two other studies evaluated significant

sources using dispersion modeling of

sources around 6 monitoring sites using

data from 1992 through 1995.8

From these evaluations, the MAG

plan identified 8 significant source

categories and 12 insignificant source

categories. MAG plan, p. 9-6.

The final list of significant source

categories did not distinguish between

those categories that are significant for

the 24-hour standard and those

significant for the annual standard;

although previous studies have shown

that some source categories are

significant only for one or the other

standard. Because the MAG plan did not

distinguish significant source categories

between the two standards, we will treat

each of the listed significant source

8

These studies are "The 1989-90 Phoenix PM10 Study," Desert Research Institute, April 1991;

"Particulate Control Measure Feasibility Study,"

Sierra Research, January 1997; and "Plan for

Attainment of the 24-hoar PM-10 Standard,

Maricopa County PM-10 Nonattainment Area,"

ADEQ, May 1997.

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categories as significant for the annual

standard.

For the annual standard, the MAG

plan demonstrates that its selection of

significant source categories is

appropriate by showing that control on

the de minimis source categories would

not make the difference between

attainment and nonattainment of the

annual standard by 2001. According to

the plan, total emissions in the area

need to be reduced to 130 mtpd to attain

the annual standard by 2001. After

application of BACM, total emissions

are reduced to 152 mtpd. MAG plan, p.

9-11. The 12 de minimis sources

categories contribute in total 10.3 mtpd.

MAG plan, Table 9-a. Totally

eliminating these source categories

would reduce total regional emissions to

142 mtpd, still 12 mtpd above the

regional emissions level needed for

attainment. MAG plan, pp. 9-10

through 9-12.

The 8 significant source categories

are:

1. Paved road travel.

2. Unpaved road travel (includes

unpaved parking lots).

3. Industrial paved road travel (paved

and unpaved).

4. Construction site preparation

(includes disturbed vacant lots that are

not undergoing construction).

5. Agricultural tilling (includes all

agricultural sources).

6. Residential wood combustion.

7. On-road and non-road motor

vehicle exhaust.

8. Secondary ammonium nitrate.

MAG Plan, Table 9-1.

The 12 de minimis source categories

are:

1. Stationary point sources.

2. Fuel combustion (excluding

residential wood combustion).

3. Waste/open burning.

4. Agricultural harvesting.

5. Cattle feedlots.

6. Structural/vehicle fires.

7. Charbroiling/frying meat.

8. Marine vessel exhaust.

9. Airport ground support exhaust.

10. Railroad locomotive exhaust.

11. Windblown from fluvial channels.

12. Wild fires.

MAG plan, Table 9-a. The plan notes

that several de minimis source

categories are already subject to control

or will be controlled in the future. MAG

plan, p. 9-12.

We propose to find that the MAG plan

has not excluded any source categories

that should be considered significant

from its list of significant source

categories. The plan presents acceptable

modeling to evaluate the impact of

various PM-10 sources and source

categories on PM-10 levels and to

derive a comprehensive and

conservative list of significant source

categories.

Our proposal here does not mean that

we believe all the source categories

identified as significant in the MAG

plan needed to be considered significant

for the purpose of evaluating BACM. We

believe that the MAG plan is

conservative in its selection of

significant source categories, that is, it

may have included more source

categories in its significant source list

than are strictly needed. Thus our use

of negative wording in our proposed

finding: no significant source categories

were excluded as opposed to only the

significant categories were included. In

our 1998 FIP, we derived a narrower list

of significant sources based on more

recent modeling than was used to

develop the list in the MAG plan. See

63 FR 15920, 15932 (Table 2 and text).

2. Identification of Potential BACM

In preparing the list of candidate

BACM, MAG reviewed our guidance

documents on BACM, other EPA

documents on PM-10 control, as well as

PM-10 plans from other serious PM-10

areas in the West. It also evaluated

controls proposed during public

comment. MAG plan, pp. 9-24 through

9-29.

The MAG plan appropriately screened

the list of candidate BACM to eliminate

measures that did not apply to

significant source categories in the area,

were technologically infeasible for the

area because they would not reduce

PM-10 emissions, or duplicated other

measures on the list. The MAG plan also

provides cost effectiveness estimates for

each of the candidate BACM. MAG

plan, pp. 9-30 through 9-39.

We propose to find that the MAG plan

identified and evaluated potential

BACM for the Maricopa area consistent

with our guidance. As we will discuss

below in our evaluations of the

implementation of BACM for each

significant source category, we do not

believe that the MAG plan left out any

candidate BACM. We note that

additional evaluation of control

measures was done as part of the most

stringent measure analysis. MAG plan,

pp 10-25 & 10-26. Overall, the MAG

plan presents one of the most

comprehensive lists of potential BACM

ever produced.

3. Implementation of RACM and BACM

and Inclusion of MSM for Each

Significant Source Category

In the following sections, we review

the results of the MAG plan's BACM

analysis. To present these results, we

have grouped the emission generating

activities that comprise the MAG plan's

significant categories slightly differently

from the plan, e.g., we have addressed

separately construction activities and

disturbed vacant lands which are both

included in the MAG plan's significant

category of construction site

preparation. 9 We have done this to

make our evaluations of the plan's

provisions for the implementation of

BACM and inclusion of MSM clearer

and thus, we believe, more

understandable. However, despite the

method of presentation, we have

addressed the MAG plan's provisions

for implementing RACM and BACM for

each of the plan's significant source

categories.

Also, because of the substantial

overlap in the source categories and

controls evaluated for BACM and those

evaluated for MSM, we present our

evaluation of the MAG plan's provisions

for including MSM alongside our

evaluation of the provisions for

implementing RACM and BACM for

each significant source category.

Finally, controls on a number of

significant source categories are found

in MCESD's fugitive dust rules, Rule

310 and Rule 310.01. MCESD has made

extensive commitments to improve

compliance and enforcement of these

rules to assure that they achieve the

emission reductions necessary for

expeditious attainment. These

commitments are an important

component of our finding that the MAG

plan provides for implementation of

RACM and BACM and inclusion of

MSM. We discuss them at the end of

this section.

a. Technology controls for on-road

motor vehicle exhaust. This category

includes tailpipe and tire wear

emissions of primary PM-10 from onroad motor vehicles. On-road motor

vehicles include both gasoline and

diesel-powered passenger cars, light,

medium, and heavy duty trucks, buses,

and motorcycles.10

9

MAG plan uses this grouping despite the fact

that disturbed vacant lands include lands that are

disturbed for reasons other than construction

activity. 10 We will treat gasoline-and diesel-powered

vehicles together here to preserve to the extent

practicable the significant source groupings in the

MAG plan; however, we believe they are in fact

distinct categories. Almost 95 percent of diesel PM10 emissions come from heavy-duty diesel trucks

while 75 percent of gasoline PM-10 comes from the

family car, that is, light duty cars and trucks (which

include sports utility vehicles). See Table ORM-1

in the EPA TSD section "Implementation of BACM

and Inclusion of MSM for On-Road Motor Exhaust

(Technology Standards)." There is almost no

overlap in the controls for the family car and those

for heavy duty diesel trucks, key evidence that they

are in fact distinct source categories. See Table

ORM-4 in the EPA TSD.

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The suggested technology-based

measures for controlling emissions from

on-road motor vehicle exhaust fall into

one of five categories: new emission

standards, inspection and maintenance

programs, fuels, programs to encourage

alternative fueled vehicle usage, and

programs to accelerate fleet turnover. In

total, the MAG plan considers 22

technology-based control measures. See

MAG plan, Table 5-2. We believe this

list is complete and propose to find that

the MAG plan evaluates a

comprehensive set of potential

technology-based controls for on-road

motor vehicle exhaust emissions

including the potentially most stringent

measures from other states.

For gasoline vehicles, Arizona has

implemented one of the nation's best

and most comprehensive enhanced I/M

programs including expanding the

program to areas surrounding Phoenix;

has adopted its own Clean Burning

Gasoline program which mandates the

use of either Phase II federal

reformulated gasoline or California

reformulated gasoline; offers generous

tax credits and deductions for

conversion of vehicles to alternative

fuels; and mandates federal, state,

county, and municipal governments to

convert their fleets to alternative fuels.

MAG plan, pp. 7-2 through 7-24.

Arizona has instituted a heavy duty

diesel I/M program, will require pre1988 HDDV registered in the Phoenix

nonattainment area to meet 1988 federal

emission standards starting in 2004, has

established a voluntary vehicle repair

and retrofit program to encourage

retrofitting and overhaul of heavy duty

diesel engines to reduce emissions, and

has limited diesel sulfur content to 500

parts per million (ppm). MAG plan,

Chapter 7.

The California Air Resources Board's

diesel fuel standards (CARB diesel) is

one of the few identified motor vehicle

controls not adopted by the State. The

plan identifies this measure as a

potential MSM. MAG plan, Table 10-7.

The MAG plan claims that the measure

is unreasonable on a cost basis. MAG

plan, p. 9-46. We make no judgement

on this claim given the great uncertainty

regarding the potential cost of

implementing CARB diesel in the

Phoenix area. We do note that the State

has already adopted half of the CARB

diesel standards, the 500 ppm sulfur

limit.l

Under our proposed policy for MSM

in extension requests, we believe that

11 The other CARB diesel standard is a limit on the aromatic hydrocarbon content of no more than

10 percent by volume. CARB, Fact Sheet on California Diesel Fuel, March 1997.

we can find that the MAG plan provides

for the inclusion of MSM to our

satisfaction absent the adoption and

implementation of CARB diesel

because, based on information in the

MAG plan, the on-road engine

category's contribution to

nonattainment in the Phoenix area is

relatively low compared to other PM-10

dust sources and implementation of

CARB diesel would not advance the

attainment date.

According to the MAG plan, the onroad motor vehicle category contributes

just 1.3 percent of the pre-control

inventory in 2006, compared to

construction dust at 43.8 percent, paved

road dust at 20.4 percent, unpaved road

dust at 13.1 percent, and windblown

dust at 8.7 percent. MAG plan, Table 8-

3. Adoption of CARB diesel would

generate a total reduction of 0.8 mtpd in

2006. MAG plan, p. 10-37. It takes a 4

mtpd reduction to advance the annual

standard attainment date one year (the

minimum needed because it is an

annual standard), so reductions from

implementation of this measure are

insufficient to advance the attainment

date. See section on RFP and

Quantitative Milestones.

As noted before, Arizona has in place

one of the nation's most comprehensive

programs to address on-road motor

vehicle emissions. With the additional

measures in the MAG plan (including a

more stringent diesel I/M program and

measures both encouraging and

requiring diesel fleet turnover) the

overall mobile source program is

strengthened and goes beyond the

existing program. Both strengthening

and expanding existing programs are

key criteria for demonstrating the

implementation of BACM. See

Addendum at 42013. Where the MAG

plan has rejected potential BACM, it

provides a reasoned and acceptable

justification for the rejection.

The MAG plan identified just a few

measures from other areas as being more

stringent than existing programs. These

measures have either been adopted or

we have concluded that the measures

need not be included to assure the

inclusion of MSM.

All the adopted BACM and MSM are

already implemented, except for one.

The requirement that pre-1988 heavy

duty diesel vehicles registered in the

nonattainment area meet 1988 federal

emission standards will not be

implemented until January 1, 2004 in

order to provide sufficient lead time for

modification or replacement of the noncomplying heavy duty diesel vehicles.

We, therefore, propose to find that the

combination of on-road motor vehicle

technology controls and TCMs

(described in the next section) in the

MAG plan provides for the

implementation of RACM and BACM

and the inclusion of MSM for on-road

motor vehicle exhaust.

b. Transportation control measures

(TCMs) for on-road motor vehicle

exhaust and paved road dust. TCMs can

reduce PM-10 emissions in both the onroad motor vehicle exhaust and paved

road dust source categories by reducing

vehicle miles traveled (VMT) and

vehicle trips. They can also reduce

vehicle exhaust emissions through

relieving congestion. Our serious area

PM-10 guidance requires that plans

identifying on-road motor vehicles as a

significant sources must also evaluate

the TCMs listed in section 108(f) of the

CAA. Addendum at 42013.

In our review, we have primarily

assessed the MAG plan's provisions for

implementing RACM and BACM and

including MSM through TCMs based on

the measures' effectiveness in

controlling directly-emitted PM-10 from

vehicle exhaust. We have not assessed

the plan based on the TCMs' potential

benefit in controlling PM-10 precursors

such as NOx and SOx because (1) from

available ambient measurements,

neither nitrates nor sulfates are

important to overall PM-10

concentrations in the Phoenix area (See

EPA TSD section, "BACT for Major

Stationary Sources of PM-10

Precursors" which shows that total

secondary particulates accounted for

less than 4 gg/m 3 in 1995) and (2)

Arizona has already targeted mobile

source NOx and SOx through an

aggressive set of mobile source controls

which we believe cover the

implementation of RACM and BACM

and inclusion of MSM requirements for

tailpipe NOx and SOx. See discussion

immediately above on technology

controls for on-road motor exhaust.

In total, the MAG plan identifies 19

TCMs for consideration including the

CAA section 108(f) measures. The plan

does not identify any potentially more

stringent TCMs from other areas. See

EPA TSD section "Implementation of

BACM and MSM for On-Road Motor

Vehicle Exhaust and Paved Road Dust

(TCMs)." We believe that this list is

complete and propose to find that the

MAG plan evaluates a comprehensive

set of potential TCMs for on-road motor

vehicle exhaust emissions and the

potentially most stringent measures

from other States.

Arizona has a long history of adopting

and then enhancing programs to reduce

emissions from on-road motor vehicles

by reducing vehicle miles traveled,

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vehicle trips, and/or congestion.12 The

area has an employer trip reduction

ordinance which applies to employers

of 50 or more, a public outreach

program to encourage people to reduce

driving, programs to improve bicycling

and pedestrian travel, and an extensive

program to synchronize traffic lights. In

most instances, these programs were

adopted and implemented as part of

carbon monoxide and ozone control

programs, but they also reduce PM-10.

With the additional measures in the

MAG plan (including additional traffic

light synchronization, transit

improvements, and bicycle and

pedestrian facility improvements), the

overall TCM program is strengthened

and goes beyond the existing program.

See EPA TSD, Table TCM-3 in section

"Implementation of BACM and MSM

for On-Road Motor Vehicle Exhaust and

Paved Road Dust (TCMs)." Both

strengthening and expanding existing

programs are key criteria for

demonstrating the implementation of

BACM. See Addendum at 42013. Where

the MAG plan has rejected potential

BACM, it provides a reasoned

justification for the rejection.

All the adopted TCM BACM are

already implemented or have on-going

implementation schedules because they

are part of a on-going capital

improvement program (e.g., signal

synchronization).

We propose to find that the

combination of on-road motor vehicle

technology controls (described in the

previous section) and TCMs in the MAG

plan provides for the implementation of

RACM and BACM and inclusion of

MSM for on-road motor vehicle exhaust.

We also propose to find that the

combination of TCMs and paved road

dust measures (described in the paved

road section later in this preamble)

provides for the implementation of

RACM and BACM and the inclusion of

MSM for paved road dust.

c. Nonroad engines. The non-road

engine category covers a diverse

collection of engines, equipment and

vehicles fueled by gasoline, diesel,

electric, natural gas, and other

alternative fuels, including outdoor

power equipment, recreational

equipment, farm equipment,

construction equipment, lawn and

garden equipment, and marine vessels.

The suggested measures for

controlling emissions from nonroad

engines fall into one of four categories:

new emission standards, programs to

accelerate fleet turnover, programs

12 These plans include the MAG moderate and

serious area carbon monoxide plans and MAG

moderate area ozone plan.

affecting usage, or fuels. In total, the

MAG plan evaluates 8 measures in

addition to clean fuels measures for

reducing PM-10 emissions from

nonroad engines. We believe that this

list is complete and propose to find that

the MAG plan evaluates a

comprehensive set of potential measures

for nonroad engines including the

potentially most stringent measures

from other States.

We have adopted national emission

standards for a broad range of nonroad

engines. These standards apply to

nonroad engines sold in Arizona and are

the base, RACM-level, program for

controlling emissions from nonroad

engines. The CAA preempts all states,

except for California, from setting

independent nonroad emission

standards. CAA section 209(e). Other

states, however, may adopt regulations

identical to California's regulations,

provided they notify us and give

appropriate lead time, 2 years, for

implementation. Section 209(e)(2)(B).

Arizona has committed to adopt

California's non-road standards that are

more stringent than the federal

standards. MAG plan, p. 7-42. In

addition, the State has established and

is currently running a voluntary

retirement program for gasoline

powered lawn and garden equipment

which is run by Maricopa County and

a program to encourage the use of

temporary electrical power rather than

portable generators at construction sites.

See MAG plan, pp. 7-41 and 7-43.

With the addition of these measures,

the overall nonroad engine program is

strengthened and goes beyond the

existing federal program. See EPA TSD

section "Implementation of BACM and

Inclusion of MSM for Nonroad

Engines." Both strengthening and

expanding existing programs are key

criteria for demonstrating the

implementation of BACM. See

Addendum at 42013. Where the MAG

plan has rejected potential BACM, it

provides a reasoned justification for the

rejection.

The MAG plan identifies CARB diesel

as a potential MSM for non-road engines

but does not adopt it. MAG plan, Table

10-7. Under our proposed policy for

MSM in extension requests, we believe

that we can find that the MAG plan

provides for the inclusion of MSM to

our satisfaction absent the adoption of

CARB diesel because, based on

information in the MAG plan, the nonroad engine category's contribution to

nonattainment in the Phoenix area is

relatively low compared to other PM-10

dust sources and implementation of

CARB diesel would not advance the

attainment date.

The nonroad motor vehicle category

contributes 4.8 percent of the precontrol inventory in 2006, compared to

construction dust at 43.8 percent, paved

road dust at 20.4 percent, unpaved road

dust at 13.1 percent, and windblown

dust at 8.7 percent. MAG plan, Table 8-

3. Adoption of CARB diesel would

generate a total reduction of 0.8 mtpd in

2006. MAG plan, p. 10-37. It takes a 4

mtpd reduction to advance the annual

standard attainment date one year (the

minimum needed because it is an

annual standard), so reductions from

implementation of this measure are

insufficient to advance the attainment

date. See section on RFP and

Quantitative Milestones.

We, therefore, propose to find that

MAG plan provides for the

implementation of RACM and BACM

and inclusion of MSM for on-road motor

vehicle exhaust.

d. Paved road dust. Paved road dust

is the largest source of PM-10 in the

Maricopa area. It is fugitive dust that is

deposited on a paved roadway and then

is re-entrained into the air by the action

of tires grinding on the roadway. Dust

is deposited on the roadway from being

blown onto the road from disturbed

areas; tracked onto the road from

unpaved shoulders, unpaved roads, or

other unpaved access points; stirred up

from unpaved shoulders by wind

currents created from traffic movement;

spilled onto the road by haul trucks; and

carried onto the road by water runoff or

erosion.

The suggested measures for

controlling emissions from paved road

dust fall into one of three categories:

reductions in vehicle trips (VT) and

vehicle miles traveled (VMT),

preventing deposition of material onto a

roadway and cleaning material off the

roadway. We have already discussed

measures for reducing VT and VMT in

the section on TCMs above.

The MAG plan lists several potential

BACM for paved road dust. It also lists

a number of potentially MSM from other

areas. We believe these lists are

complete and propose to find that the

MAG plan evaluates a comprehensive

set of potential controls for paved road

dust including the potentially MSM

from other States.

Prior to the MAG plan, the cities and

towns in the Phoenix area and Maricopa

County implemented a number of

measures addressing paved road dust.

See MAG plan, Table 10-5. With the

additional measures in the MAG plan

(described below), the overall control

program to reduce paved road dust is

both strengthened and expanded

beyond the existing program. See EPA

TSD section "Implementation of BACM

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and Inclusion of MSM for Paved Road

Dust." Both strengthening and

expanding existing programs are key

criteria for demonstrating the

implementation of BACM. See

Addendum at 42013.

For the potential MSM, the MAG plan

shows that these measures are either

adopted or are not in fact more stringent

than existing Phoenix area programs.

With the exception of the MSM for

PM-10-efficient street sweepers

described below, all the adopted BACM

for paved roads are already

implemented or have on-going

implementation schedules because they

are part of a on-going capital

improvement program (e.g., curbing).

For the reasons discussed below, we

propose to find that the MAG plan

provides for the implementation of the

PM-10 efficient street sweeper measures

as expeditiously as practicable,

consistent with our proposed MSM

policy.

We, therefore, propose to find that the

MAG plan provides for the

implementation of RACM and BACM

and for the inclusion of MSM for paved

road dust.

Preventing deposition of material onto

a roadway. Measures aimed at

preventing track out on a paved road

include treating unpaved access points,

preventing track out from construction/

industrial sites, treating shoulders on

paved roads, controlling emissions

during material transport (e.g., truck

covers, freeboard requirements), and

preventing erosion onto paved roads.

The MAG plan includes each of these

measures:

Unpaved access points: In the MAG

moderate area plan, local jurisdictions

focused on requiring new connections

to public paved streets to be paved.

MAG plan, p. 9-74. In the serious area

plan, the focus has shifted to addressing

existing unpaved access points in

addition to preventing new unpaved

access points while maintaining the

previous programs. Most public entities

committed to stabilize unpaved access

points when a connecting road is built,

improved or reconstructed. See, for

example, Glendale Commitment,

"Reduce Particulate Emissions from

Unpaved Shoulders and Unpaved

Access Points on Paved Roads." Some

cities have made explicit commitments

for stabilizing existing access points

without this prerequisite, such as

Gilbert and Mesa. We also anticipate

that routine city/town/County road

paving and stabilization projects will

result in controlling a number of

existing unpaved access points. These

projects combined with increased

enforcement of track-out restrictions

and additional PM-10 efficient street

sweeping efforts should reduce paved

road emissions attributable to unpaved

access points.

The only potential MSM that the

MAG plan identifies for unpaved access

points are track out control

requirements for construction sites. See

MAG plan, Table 10-7. We discuss

these measures in the next section.

Track out. Rule 310, sections 308.2(c)

and 308.3 address dirt track out from

construction/industrial sites: All work

sites that are five acres or larger and all

work sites where 100 cubic yards of

bulk materials are hauled on-site or offsite each day must control and prevent

track out by installing a track out

control device. All work sites must also

clean up spillage or track out

immediately when it extends a

cumulative distance of 50 linear feet or

more; where track out extends less than

50 feet, it must be cleaned up at the end

of the work day.

The MAG plan identifies, as a

potentially more stringent measure for

track out, South Coast (Los Angeles

area) Air Quality Management District's

Rule 403. MAG plan, Table 10-7. The

plan concludes that the two rules are

reasonably similar in several respects,

and where differences exist, the relative

impacts on control roughly balance

against each other. MSM Study, p. C4.13 We agree. Both rules emphasize

prevention and rapid removal of track

out. See EPA TSD section

"Implementation of BACM and

Inclusion of MSM for Paved Roads

Dust," Note 2.

Unpaved Road Shoulders. As with

unpaved access points, the MAG plan

demonstrates a shift to dealing with

existing unpaved shoulders from only

preventing new ones. MAG plan, Table

9-11. Maricopa County has committed

to treat 100 miles of shoulders along

existing paved arterial and collector

roadways with high volume truck traffic

by 2003, in addition to its annual capital

improvement projects for paving or

treating unpaved shoulders. Maricopa

County commitment, 1999 revised

measure 5. Other jurisdictions have also

made commitments to treat shoulders.

A.R.S. 9-500.04(3) and 49-474.01(4),

adopted by the State legislature in 1998,

require the cities, towns and County of

Maricopa to develop and implement

plans to stabilize targeted unpaved

roads and alleys and to stabilize

unpaved shoulders on targeted arterials

beginning January 1, 2000. Although

13The "MSM Study" is the "Most Stringent PM10 Control Measure Analysis," Sierra Research,

May 13, 1998 found in Appendix C, Exhibit 4 of

the MAG plan.

this legislation does not specify how

many shoulder miles to be controlled,

we believe that the local jurisdictions'

efforts to meet this new legislation will

result in the control of unpaved

shoulders where it is most needed.

Material Transport. Requirements for

the control of PM-10 emissions during

material transport are found in Rule

310, sections 308.1 and 308.2. When

hauling material off-site onto paved

public roadways, sources are required

to: (1) load trucks such that the

freeboard is not less than three inches;

(2) prevent spillage; (3) cover trucks

with a tarp or suitable enclosure; and (4)

clean or cover the interior cargo

compartment before leaving a site with

an empty truck.

The MAG plan identifies

requirements for bulk material transport

in Imperial County Regulation VIII as a

potential MSM. MAG plan, Table 10-7.

The plan concludes that MCESD's rule

is equally stringent. We agree because

Rule 3 10's requirements for bulk

material transport/hauling are

essentially the same as Imperial

County's requirements.

Cleaning material off the roadway.

Measures for cleaning material off

roadway are track out, erosion, and spill

removal requirements and road

sweeping.

The MAG plan includes each of these

measures:

Material spillage, erosion, or

accumulation. Rule 310, section 308.2

and 308.3 address rapid clean up of

track out from construction/industrial

sites. Rule 310.01, section 306 requires

property owners/operators to remediate

erosion-caused deposits of bulk

materials onto paved surfaces. Erosioncaused deposits are to be removed

within 24 hours of their identification or

prior to resumption of traffic on the

pavement.

The MAG plan identifies South

Coast's Rule 1186 and Mojave Desert's

Rule 403 as potential MSMs for material

spillage, erosion, and accumulation onto

roadways. MAG plan, Table 10-7. In

both cases, the plan concludes that

MCESD's rules are more stringent. We

agree. MCESD's rules require the clean

up of more incidences of spillage, etc.

than does South Coast's rule. See EPA

TSD, "Implementation of BACM and

Inclusion of MSM for Paved Roads,"

Note 5.

Street sweeping. Most cities/towns

and the County have on-going street

sweeping programs with variable

sweeping frequencies. With some

exceptions, public entities

implementing this measure have not

explicitly committed to increase their

existing sweeping frequencies. Phoenix,

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for example, approved a program in

1996 to increase the frequency of

residential street sweeping to match the

uncontained trash pick-up schedule.

Phoenix commitment, measure 97-DC5. However, sweeping frequency is

appropriately evaluated in combination

with other paved road measures,

because the emission-reducing potential

of increased sweeping frequency is

closely associated with other factors.

These factors include whether the

sweepers currently in use are PM-10

efficient (such that the act of sweeping

does not cause increased emissions) and

whether the public entity has identified

roads that tend to experience higher silt

loadings where more frequent sweeping

is likely to make an appreciable

difference in PM-10 emissions. Because

sweeping frequency is among the

criteria included in MAG's PM-10

efficient street sweeper solicitation (see

below), we believe this measure is

largely incorporated into MAG's new

program.

The MAG plan identifies as a MSM

the PM-10 efficient street sweeping

provisions in South Coast Rule 1186.

MAG plan, Table 10-7. However, the

plan's analysis pre-dates MAG's

commitment for the purchase and

distribution of PM-10 efficient street

sweepers and is no longer current.

The MAG plan includes commitments

by MAG, cities, towns and the County

for the purchase and use of PM-10

efficient street sweepers. This

commitment involves the allocation of

$3.8 million in Congestion Mitigation

Air Quality (CMAQ) funds for the FY

2000-2004 Transportation Improvement

Program (TIP) to purchase PM-10

certified street sweepers for the local

jurisdictions to use. MAG has

recommended an additional $1.9

million CMAQ funds be allocated to

purchase PM-10 certified street

sweepers in the FY 2001-2005 TIP. See

MAG commitment, "PM-10 Efficient

Street Sweepers."

The funds allocated by MAG for this

program should be sufficient to replace

approximately two-thirds of the 72

existing city/town/County street

sweepers. 14 Each fiscal year in which

CMAQ funds are allocated for street

sweepers, MAG will solicit requests for

funding from cities, towns and the

County in the PM-10 nonattainment

area. Funding requests must identify by

facility type (i.e. freeway, arterial/

collector, local) the number of

centerline miles to be swept with the

PM-10 certified units, expected

frequency of sweeping, and average

14 Some street sweepers may be additions to, as

opposed to replacements of, existing equipment.

daily traffic (if available). MAG will use

this information to estimate the

emissions reduction associated with

each sweeper request and rank the

requests in priority order of

effectiveness for consideration in the

allocation of CMAQ funds. See MAG

commitment, "PM-10 Efficient Street

Sweepers."

In evaluating this program, we

considered not only the number of PM10 efficient street sweepers to be

purchased and distributed, but whether

the program incorporates use factors

that influence emissions reductions.

The greatest emissions reduction benefit

for this mitigative measure will be

achieved if the sweepers are used on a

frequent basis on roads with high silt

loadings or significant visible

accumulations. Each public entity has a

monetary incentive to compete for the

PM-10 efficient street sweepers, as the

program is funded by MAG with a low

cost share (5.7 percent) requirement.

Also, the new street sweepers will either

replace existing city-owned street

sweeping equipment or contracted out

services, or be added to existing street

sweeper equipment/services. MAG's

selection process includes PM-10

emissions reduction potential, based on

the types of roads each jurisdiction is

targeting for sweeping and how

frequently they will be swept. This data

will assist MAG in distributing the

street sweepers to local jurisdictions in

a way that maximizes the regional air

quality benefits of the program. Plus,

when the cities/towns/County are

awarded PM-10 efficient street

sweepers, their submittals will

incorporate use factors that maximize

emission reductions from this measure.

We believe that implementation of the

PM-10 efficient street sweeper program

is as expeditious as practicable. The

funding necessary to purchase this

equipment is available only over the

course of several fiscal years and the

purchase of the PM-10 efficient street

sweepers can only proceed at the rate

these funds become available.

South Coast's Rule 1186 requires any

government or government agency

which contracts to acquire street

sweeping equipment or services for

routine street sweeping on public roads

that it owns and/or maintains, where

the contract date or purchase or lease

date is January 1, 2000 or later, to

acquire or use only certified street

sweeping equipment. The rule

establishes street sweeper testing and

certification procedures. Unlike

Maricopa's strategy, Rule 1186 requires

that PM-10 efficient street sweepers be

used whenever street sweeping is

contracted out as of January 2000, and

it requires public agencies to replace

their existing street sweeping equipment

with PM-10 efficient equipment by

attrition.

MAG's PM-10 efficient street sweeper

program is being funded over the next

4 to 5 fiscal years, which may result in

a greater number of street sweepers

distributed in a shorter time frame than

could be expected using South Coast's

natural attrition approach. While it is

possible that some cities/towns in

Maricopa may continue to contract out

for street sweeping services where PM10 efficient sweepers may not be used,

most do not contract for street sweeping.

Furthermore, due to the fact that public

entities will be competing for PM-10

efficient street sweepers funded by

CMAQ dollars with only a low cost

share requirement, we believe that the

already limited reliance on contracted

out services in Maricopa County will

lessen as new PM-10 efficient

equipment becomes available and that

contractors will switch to PM-10

efficient equipment to meet new

demand. In addition, MAG's program

ensures that the cities/town/County

develop plans for how the street

sweepers will be used to maximize their

emissions reduction potential. We,

therefore, believe that overall the

Maricopa program is equivalent to

South Coast's Rule 1186.

e. Unpaved parking lots. This category

includes emissions from re-entrained

road dust from vehicle traffic in

unpaved parking lots and windblown

dust entrained from the disturbed

surface of unpaved parking lots.

There are two principle ways to

control emissions from unpaved parking

lots: prohibit unpaved parking lots or

treat the lot. MAG plan identified both:

a prohibition on unpaved haul roads

and parking or staging areas and surface

treatment to reduce dust from unpaved

driveways and parking lots. MAG plan,

Table 5-2. The MAG plan identified one

potentially more stringent measure from

South Coast which controls fugitive

dust from parking areas on construction

sites. MSM Study, p. C-9 and 10. It did

not identify any potential MSM for nonconstruction site unpaved parking lots.

We believe this list is complete and

propose to find that the MAG plan

evaluates a comprehensive set of

potential BACM and MSM for unpaved

parking lots.

Most local jurisdictions in Maricopa

County identified ordinances that

require paving of new parking lots. In

addition, MCESD Rule 310.01 requires

owners/operators of an unpaved parking

lot larger than 5,000 square feet to pave,

apply dust suppressants, or apply

gravel, according to the applicable rule

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standards/test methods. Section 303.

Applicable standards include a 20

percent opacity standard, and an 8

percent silt content standard and/or a

0.33 oz/square foot silt loading

standard. Section 303.2. MCESD Rule

310 applies the same stabilization

requirements to parking lots on

permitted facilities. Rule 310, section

302.1. Finally, many cities/towns have

treated their own parking lots or

required treatment of private lots below

MCESD's thresholds.

In determining whether the MAG plan

provides for the implementation of

BACM for unpaved parking lots, we are

also specifically considering whether

the plan provides for the

implementation of RACM for these

sources. 15 In our FIP, we promulgated a

RACM fugitive dust rule applicable to

unpaved parking lots in the Phoenix

PM-10 nonattainment area and thus it

provides a starting point for determining

whether the MAG plan measures for

unpaved parking lots meet RACM. It is

not necessary for the MAG plan

measures to be identical to the FIP rule

in order to meet the CAA's RACM

requirement, but only that they provide

for the implementation of RACM.16

However, if the submitted measures for

a particular source are identical to the

FIP rule, we can determine without

further analysis that the MAG plan has

provided for RACM for that source.

MCESD requirements for unpaved

parking lots found in Rule 310.01,

section 303 are the same in terms of

source coverage and applicable

standards/test methods for unpaved

15 While a serious area PM-10 plan must provide

for both the implementation of RACM and BACM,

in determining whether such a plan provides for

BACM implementation, we do not normally

conduct a separate evaluation to determine if the

measures also meet the RACM requirements of the

CAA as interpreted by EPA in its General Preamble.

See 57 FR 13540. This is because in our serious area

guidance (Addendum at 42010), we interpret the

BACM requirement, as generally subsuming the

RACM requirement (i.e. if we determine that the

measures are indeed the "best available," we have

necessarily concluded that they are "reasonably

available"). See Addendum at 42012-42014.

Therefore, a separate analysis to determine if the

measures also represent a RACM level of control is

not necessary. However, in this particular case, we

are proposing to withdraw the FIP rule in

conjunction with our proposed approval of the

MAG plan. In order to do this, we must determine

under CAA section 110(1), that, among other things,

withdrawing the FIP rule does not interfere with the

RACM requirements in the CAA.

16 The State may submit one or more control

measures that collectively achieve a RACM level of

control for a particular source, regardless of

whether they apply the same strategy as our FIP

rule. Furthermore, EPA's guidance indicates that a

RACM evaluation includes considering "the impact

of the reasonableness of the measures on the

municipal or other governmental entity that must

bear the responsibility for their implementation."

General Preamble at 13541.

parking lots as the FIP rule, with the

only difference being that Rule 310.01

applies county-wide while the FIP rule

applies strictly to sources located in the

PM-10 nonattainment area. Rule 310.01

requirements are effective upon

adoption and were adopted on February

2000, such that the timeframe for

controls is equivalent to the FIP rule

and is also as expeditious as practicable.

In light of the fact that Rule 310.01

requirements are the same as the FIP

rule requirements and MCESD's

commitments to improve compliance

and enforcement of Rule 310.01, we

propose that the MAG plan provides for

the implementation of RACM. Given

additional MAG plan city/town

commitments that collectively increase

the stringency of control on unpaved

parking lots, we propose that the MAG

plan also provides for the

implementation of BACM.

South Coast Rule 403 requires sources

to apply dust suppressants to stabilize at

least 80 percent of unstabilized surface

area. Sources must comply with a 0

percent opacity property line limit. The

MAG plan deems the respective

requirements roughly equivalent to Rule

310. We believe that the addition of a

silt loading/content standard for

unpaved parking lots for sources

covered under Rule 310 increases the

rule's stringency to be at least

equivalent to that of South Coast Rule

403. We, therefore, propose to find that

the MAG plan correctly concluded that

there are no more stringent measures in

other State plans or used in practice

elsewhere that are applicable to the

Phoenix area.

f. Disturbed vacant lands. This

category includes windblown fugitive

dust emissions from disturbed surfaces

of vacant lands. On vacant land, fugitive

dust emissions are caused by virtually

any activity which disturbs an

otherwise naturally stable parcel of

land, including earth-moving activities,

material dumping, weed abatement, and

vehicle traffic. 63 FR 15919, 15937

(April 1, 1998).

The MAG plan includes three

suggested measures for controlling

fugitive dust from vacant disturbed

lands. The plan also identified controls

on weed abatement operations and offroad racing as potential most stringent

measures. We believe this list is

complete and propose to find that the

MAG plan evaluates a comprehensive

set of potential BACM and MSM for

disturbed vacant lands.

The MAG plan includes two MCESD

rules that address BACM for vacant lots.

Rule 310 requirements apply to vacant

lots located at permitted facilities

(including construction sites) and Rule

310.01 requirements apply to

nonpermitted sources.1 7 Rule 310 and

Rule 310.01 requirements apply to both

publicly and privately owned lots. Rule

310, section 302.3 and Rule 310.01,

section 301 and 302.

In determining whether the MAG plan

provides for the implementation of

BACM for disturbed vacant land, we are

also specifically considering whether

the Plan provides for the

implementation of RACM for these

sources. See Footnote 15. In our FIP, we

promulgated a RACM fugitive dust rule

applicable to disturbed vacant land in

the Phoenix PM-10 nonattainment area

and thus it provides a starting point for

determining whether the MAG plan

measures for disturbed vacant lands

meet RACM. It is not necessary for the

MAG plan measures to be identical to

the FIP rule in order to meet the CAA's

RACM requirement, but only that they

provide for implementation of RACM.

See footnote 16. However, if the

submitted measures for a particular

source are identical to the FIP rule, we

can determine without further analysis

that the MAG plan has provided for

RACM for that source.

Rule 310.01 requirements for vacant

lots and open areas are virtually

identical to the Phoenix FIP rule's

requirements for these sources. Rule

310.01, however, is more broadly

applicable. It covers vacant lots and

open areas located anywhere in

Maricopa County, in contrast to the

Phoenix FIP rule, which only applies to

lots in the Maricopa County portion of

PM-10 nonattainment area (located in

the eastern third of the County). Rule

310.01, sections 301 and 302. Unlike the

FIP rule, Rule 310.01 also applies to

partially developed residential,

industrial, institutional, governmental,

or commercial lots in Maricopa County,

and any tract of land in the Maricopa

County portion of the nonattainment

area adjoining agricultural property.

Rule 310.01, section 211.

Rule 310 requirements for vacant lots

and open areas on permitted sources are

more stringent than those in Rule

310.01, in that Rule 310 requires

stabilization of all inactive disturbed

surface areas on permitted facilities,

regardless of their size. Rule 310,

section 302.3. Rule 310 also contains

requirements for weed abatement that

closely resembles the Phoenix FIP rule's

weed abatement requirements, except

17Permitted sources include any facility

permitted by MCESD and are not limited solely to

those facilities with earthmoving permits. Rule 310,

section 102.

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that Rule 3 10's threshold for coverage is

more stringent.18

Vacant lots and open areas subject to

Rule 310 and Rule 310.01 are required

to meet the same surface stabilization

standards/test methods as required in

the Phoenix FIP rule.

In addition to requirements in Rule

310 and Rule 310.01, the MAG plan

contains commitments made by several

cities and towns to address vacant

disturbed lots. For example, seven

jurisdictions require or will require

stabilization of disturbed vacant lots

after 15 days of inactivity (as compared

to Rule 310.01's 60-day compliance

period); two (2) prohibit dumping of

materials on vacant land; and two (2)

will stabilize all city-owned vacant lots.

Because Rules 310 and 310.01

requirements are at least as stringent as

the FIP rule requirements and MCESD

has committed to improve compliance

and enforcement of these rules, we

propose that the MAG plan provides for

the implementation of RACM on

disturbed vacant land. Because these

rules increase the number of lots subject

to control thus collectively increasing

the stringency of control on vacant

disturbed lands, we propose that the

MAG plan also provides for the

implementation of BACM.

For its MSM comparison, the MAG

plan identifies measures in Clark

County (Las Vegas, Nevada) Rule 41 and

South Coast Rule 403. See MSM Study,

pp. C-11 and C-16,17. The plan

concludes that neither measure is more

stringent than the Maricopa measures

because Rule 310 and 310.01 contain

similar, equally, or more stringent

requirements. We agree that the

MCESD's rules are equally or more

stringent.

We, therefore, propose to find that the

MAG plan correctly concluded that

there are no more stringent measures in

other State plans or used in practice

elsewhere that are applicable to the

Phoenix area.

g. Unpaved roads. This category

includes re-entrained dust from vehicle

travel on unpaved roads. There are three

classes of unpaved roads in the

Maricopa nonattainment area: public

roads, private roads that are publicly

maintained (also referred to as

minimally-maintained or courtesy

grade), and private roads that are

privately maintained.

18 Rule 310 requires any earthmoving operation

that disturbs 0.1 acre or more to have a dust control

plan, including weed abatement by discing or

blading, whereas the Phoenix FIP rule weed

abatement requirements only apply to disturbances

equal to or greater than 0.5 acres. Rule 310, section

303.

The MAG plan includes three

suggested measures for controlling

fugitive dust from unpaved roads:

Surface treatment to reduce dust from

unpaved roads and alleys, traffic

reduction/speed control plans for

unpaved roads; and prohibition of

unpaved haul roads. MAG plan, Table

5-2. The MAG plan did not identify any

other State's measures that are more

stringent than the ones already in the

plan. We believe this list is complete

and propose to find that the MAG plan

evaluates a comprehensive set of

potential BACM and MSM for unpaved

roads.

In determining whether the MAG plan

provides for the implementation of

BACM for unpaved roads, we are also

considering whether the Plan provides

for the implementation of RACM for

these sources. See Footnote 15. In our

FIP, we promulgated a RACM fugitive

dust rule applicable to unpaved roads in

the Phoenix PM-10 nonattainment area

and thus it provides a starting point for

determining whether the MAG plan

measures for unpaved roads meet

RACM. It is not necessary for the MAG

plan measures to be identical to the FIP

rule in order to meet the CAA's RACM

requirement, but only that they provide

for implementation of RACM. See

footnote 16. However, if the submitted

measures for a particular source are

identical to the FIP rule, we can

determine without further analysis that

the MAG plan has provided for RACM

for that source.

As discussed below, we propose to

find that the MAG plan provides for the

implementation of RACM and BACM

and the inclusion of MSM for unpaved

roads.

Surface treatment to reduce dust from

unpaved roads and alleys. The principle

control for public unpaved roads and

alleys is Rule 310.01, section 304, which

requires all publicly-owned unpaved

roads and alleys with 250 vehicles per

day or more to be stabilized by June 10,

2000 and those with 150 vehicles per

day or more to be stabilized by June 10,

2004.

Several cities have commitments that

go beyond the requirements of Rule

310.01 for publicly-owned unpaved

roads. For example, the City of Phoenix

committed to, and recently

accomplished, paving all 80 miles of its

publicly-owned unpaved roads

regardless of the level of vehicle travel.

Phoenix Commitment, Measure 98-DC7. Other cities, such as Tempe and

Gilbert, have very few remaining miles

of public unpaved roads/alleys. See

Tempe Commitments, Measure 98-DC7 and Gilbert Commitments, Measure

98-DC-7.

For private roads, Rule 310, section

308.6, requires that easements, rights-ofway, and access roads for utilities

(electricity, natural gas, oil, water, and

gas transmission) that receive 150 or

more VPD must be paved, chemically

stabilized, or graveled in compliance

with the rule's standards.

Private unpaved roads are scattered

throughout Maricopa County, within

both County and city jurisdictions. A

survey performed for us of unpaved

roads in Maricopa County determined

that the great majority of identified

unpaved road mileage consists of

privately-owned roads that receive

minimal maintenance by the Maricopa

County Department of Transportation

(MCDOT).19

MAG and MCDOT have committed to

pave County minimal maintenance

roads within the nonattainment area

that currently exceed 150 ADT and meet

criteria to become public highways,

using $22 million from Congestion

Management/Air Quality and MCDOT

funds.20 MAG Commitment; Maricopa

County Commitment, 1999 Revised

Measure 17. This program will pave an

estimated 60 miles of unpaved

roadways in fiscal years 2001-2003

which is approximately 20 percent of

the privately-owned, publiclymaintained County-jurisdiction roads

and 40 percent of vehicle miles traveled

on these roads. Maricopa County has

also committed to continue to evaluate

other roads for funding when traffic

levels increase above 150 vehicle trips

per day. Maricopa County Commitment,

1999 Revised Measure 17. We interpret

this commitment to apply to any private

roads within County jurisdiction,

whether they currently receive minimal

maintenance or not.

As the County evaluates roads for

paving, it may make exceptions to its

commitment to pave roads with vehicle

trips that exceed 150 ADT. The County's

evaluation process takes into account

whether a road meets the proper criteria

to become a public highway and

whether estimated costs of paving are

excessive (greater than $500,000 per

mile).21 When MCDOT identifies a road

that meets these criteria (i.e. the road

can be declared a public highway and

19 Pacific Environmental Services, "Survey for

Fugitive Dust Emission Sources," April 15, 1999.

20 Congestion Management/Air Quality (CMAQ)

funds are federal transportation funds awarded to

certain nonattainment areas for congestion

management or air quality-transportation projects

such as paving unpaved roads. 21 A private road begins to bear other than local

traffic through extensions of other nearby public

roads or the construction of an indirect source that

attracts external drivers using the road as a short

cut. See Maricopa County Commitments, 1999

Revised Measure 17.

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costs are not excessive), it will

recommend that the Board of

Supervisors open and declare the road

a public highway.

Because BACM implementation

properly takes costs into account, we

believe that MCDOT's criteria for

selecting private roads to pave are

suitable in the context of a strategy to

implement BACM and will result in

control of the great majority of high

traffic unpaved roads. Although

available information on private roads

in city jurisdictions is limited, our

existing information suggests that a

typical privately owned unpaved road

has low ADT.22 As a result, we believe

that the vast majority of private unpaved

roads do not need to be controlled in

order for us to determine that the MAG

plan provides for the implementation of

BACM for unpaved roads for the annual

standard.

Traffic reduction/speed control plans

for unpaved roads. Some jurisdictions

committed to evaluate this measure.

Two jurisdictions committed to posting

15 mph speed limit signs on private and

public unpaved roads and access ways;

one jurisdiction has posted 15 mph

speed limits in all alleys. See MAG

plan, Table 10-9. Also, under Rule 310,

owners/operators of unpaved haul roads

and utility roads who comply with the

rule by limiting vehicle trips to 20 per

day, must also limit vehicle speeds to 15

mph. While speed limit controls are

only being implemented to a limited

extent, we believe the plan measures to

pave or otherwise stabilize unpaved

roads in the Phoenix PM-10

nonattainment area establish the critical

commitments for the implementation of

RACM and BACM. This is because road

stabilization ensures emission

reductions whereas speed limits may or

may not be observed.

Prohibition of unpaved haul roads.

Rule 310 requires that unpaved haul

roads meet both a 20 percent opacity

standard and a silt content or silt

loading standard. Rule 310, section

302.2. We propose to find that this

requirement is sufficient for the

implementation of BACM for these

roads. We believe requiring compliance

with both of these standards ensures

that the BACM applied will have a

stabilizing effect.

Evaluation of unpaved road measures

in other areas found none that are more

stringent than the measures for unpaved

22 Among the over 100 segments of unpaved

privately-owned and maintained roads that were

identified in the PES survey, the contractor

estimated, using aerial photographs, that only 6 of

these have ADTs that exceed 150. Tube counts,

which are more accurate than other methods to

estimate ADT, were not conducted on these roads.

roads in the MAG plan. MAG plan,

Table 10-7. We agree and propose to

find that there are no other more

stringent measures for unpaved roads

than are already included in the MAG

plan.

Please see the TSD section

"Implementation of BACM and

Inclusion of MSM for Unpaved Roads"

for a more detailed discussion of our

proposed findings.

h. Constmuction sites and activities.

Sources of fugitive dust emissions at

construction site sources include land

clearing, earthmoving, excavating,

construction, demolition, material

handling, bulk material storage and/or

transporting operations, material track

out or spillage onto paved roads (which

we have addressed in the paved road

section), and vehicle use and movement

on site (e.g., the operation of any

equipment on unpaved surfaces,

unpaved roads and unpaved parking

areas). Windblown emissions from

disturbed areas on construction sites are

also a source of PM-10. Construction

operations, which are mostly various

forms of earthmoving, represent some

90 percent of the emissions in this

source category.

The suggested measures in the MAG

plan are actually various means of

improving compliance with controls as

opposed to new controls for

construction sites. The controls for

construction sites are found in MCESD's

fugitive dust rule, Rule 310, revised on

February 16, 2000.

Rule 310's requirements, effective on

February 16, 2000, apply to any source

required to obtain a permit under

Maricopa County rules, which includes

earthmoving operations of 0.10 acre or

more and sources subject to Title V

permits, 23 Non-Title V permits, or

General Permits. In addition to rule

requirements for fugitive dust sources

located at any permitted source, Rule

310 requires that a Dust Control Plan

(DCP) be submitted for any earthmoving

operations of 0.10 acre or more, and that

the DCP be approved prior to

commencing any dust generating

operation. The rule's definition of a dust

generating operation includes any

activity capable of generating fugitive

dust including land clearing,

earthmoving, weed abatement by

discing or blading, excavating,

construction, demolition, material

handling, storage and/or transporting

operations, vehicle use and movement,

the operation of any outdoor equipment

or unpaved parking lots. For other

23 Title V permits are operating permits required

by Title V of the Clean Air Act for major stationary

sources and certain other stationary sources.

permitted sources, Rule 310 requires

that a Dust Control Plan (DCP) be

submitted and approved prior to

commencing any routine dust

generating activity, defined as any dust

generating operation which occurs more

than 4 times per year or lasts 30

cumulative days or more per year.

24

Specific Rule 310 requirements

include:

* a 20 percent opacity requirement

for any dust generating operation

* wind event control measures

* implementation of control measures

before, after and while conducting any

dust generating operation, including

weekends, after work hours and

holidays

* required control measures and

standards for:

* unpaved parking lots

* unpaved haul/access roads

* disturbed open areas and vacant

lots

* bulk material hauling

* bulk material spillage, carry-out,

erosion and track out

* open storage piles

* weed abatement by blading or

discing a requirement in dust control

plans for at least one primary and one

contingency control measure for all

fugitive dust sources; the contingency

measure is to be immediately

implemented if the primary control

measure proves ineffective

In order to comply with the rule's 20

percent opacity standard and dust

control plan requirements for

implementing primary and/or

contingency control measures for

earthmoving activities, 25 sources need

to apply one or more controls, which in

most cases includes applying water or

another dust suppressant before and

during operations. Inactive disturbed

surfaces must be stabilized to meet at

least one of the rule's stabilization

standards (e.g. visible crusting, 10

percent rock cover, etc.). Unpaved roads

and unpaved parking lots must also be

stabilized to meet both a 20 percent

opacity standard and a silt content/

loading standard.26 Test methods

associated with stabilization and

24 This is in addition to the requirement to submit

a DCP for any earthmoving operation that disturbs

0.10 acre or more even if the operation is subject

to Title V or other permitting requirements.

25Earthmoving operations include cutting and

filling, grading, leveling, excavating, trenching,

loading or unloading of bulk materials,

demolishing, blasting, drilling, adding to or

removing bulk materials from open storage piles,

back filling, soil mulching, landfill operations, or

weed abatement by discing or blading.

26 Unpaved roads must meet a 6 percent silt

content standard or, alternatively, a 0.33 oz/ft2 silt

loading standard, while unpaved parking lots must

meet an 8 percent silt content standard or,

alternatively, a 0.33 oz/ft2silt loading standard.

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opacity standards are contained in

Appendix C, which was submitted with

Rule 310.

The February 2000 revisions to Rule

310 that have increased the rule's

stringency include the addition of

specific work practice standards, the

addition of stabilization standards and

test methods for unpaved surfaces, and

modifications to the opacity test method

(adding an alternative opacity test

method for unpaved roads and unpaved

parking lots and modifying the opacity

test method for other sources). We

believe that the new and/or revised

standards/test methods provide for a

greater degree of control than under the

previous SIP-approved version of Rule

310.

In addition to these Rule 310

revisions, MCESD has made three

enforceable commitments to further

strengthen requirements for

construction sites that must be met by

July 2001. These commitments, which

all are part of Revised Measure 6 in

Maricopa County's commitments, are to:

1. Research and develop a standard(s)

and test method(s) for earthmoving

sources, considering our field research,

that are enforceable and meet BACM

requirements on stringency and source

coverage.

Currently, activities on construction

sites must meet an opacity standard of

20 percent. If research on the standards

and test methods find problems with the

existing opacity standard's

enforceability, feasibility, or stringency

for some or all earthmoving operations,

MCESD will revise the rule to modify

the existing opacity test method to

address the problems as warranted or

adopt a new standard(s) and test

method(s) to deal with any problems

that cannot be addressed by modifying

the opacity test method;

2. Research, develop and incorporate

additional requirements for dust

suppression practices/equipment for

construction activities into dust control

plans and/or Rule 310;

3. Revise the sample daily

recordkeeping logs for new and renewed

Rule 310 permits to be consistent with

rule revisions and to provide sufficient

detail documenting the implementation

of dust control measures required by

Rule 310 and the dust control plan.

Distribute sample log sheets with issued

permits and conduct outreach to

sources.

The first enforceable commitment

addresses our concern that the existing

opacity standard and test method for

earthmoving operations may not always

be sufficient to control construction site

dust to BACM levels. MCESD has

already revised the opacity test method

to deal partially with this concern (see

Rule 310, Appendix C), but we believe

that additional standards/test methods

are needed to fully assure that sources

are effectively controlled. We have

already sponsored a field study to

address this issue and are considering

additional field work in Summer, 2000.

We believe that additional time is

needed for Maricopa County to

investigate options in coordination with

us, and then revise the rule. Therefore,

a commitment is the appropriate

method of addressing this issue.

The second enforceable commitment

addresses our concern that dust control

plans (DCPs) lack specific criteria for

dust suppressant application. For

example, a source engaged in grading or

cut-and-fill earthmoving for a multi-acre

project may choose to comply with Rule

310 by applying water. However,

neither the rule nor DCPs establishes

minimum criteria for the number of

water trucks/water application systems

and water truck capacity for any given

size construction site or a ratio of

earthmoving equipment to water trucks.

The rule also does not contain a prewetting requirement, although research

may show this to be necessary to

successfully control dust on certain soil

types.

Establishing criteria for dust control is

complicated by variations in soils,

meteorological conditions, equipment

size/use, project phase, and level of

activity. All these factors can impact the

amount of water (or other controls)

needed to control fugitive dust on a

particular site on a particular day,

making it difficult to establish criteria

that apply to all sites at all times. This

explains why more time is needed for

MCESD to develop criteria to address a

multitude of circumstances.

The third enforceable commitment

addresses our concern that while Rule

310 currently contains an acceptable

recordkeeping requirement, a more

specific recordkeeping requirement

would help improve compliance.

Currently neither the rule nor DCPs

specify what information should be

included in a daily log. MCESD has

committed to revising and distributing

to permitted sources daily

recordkeeping log sheets to provide

sufficient detail documenting the

implementation of dust control

measures.

Based on our evaluation of revised

Rule 310 and the additional

commitments made by MCESD, we

propose to find that the rule and

commitments together include a

comprehensive set of BACM level

controls for construction sites. The rule

is comprehensive in scope in that each

dust source is subject to a set of

requirements under Rule 310 (e.g.

storage piles, dirt trackout, haul truck

loads, disturbed areas, earthmoving

operations). In addition, the Rule 310

requirements are sufficiently stringent

to provide for the implementation of

RACM and BACM, with the exception

of certain aspects of the rule that are

addressed in the commitments made by

MCESD. Thus, between the submitted

rule requirements and commitments, we

propose to find that the MAG Plan

meets the CAA's RACM and BACM

requirements for construction sites.

The MAG plan identifies potentially

more stringent construction site fugitive

dust measures either in or under

consideration for inclusion in others

SIP. See MSM Study, Table 1-2 and

Table 3-1.

Most of the potential MSMs are

provisions in South Coast fugitive dust

rule, Rule 403. The MAG plan indicates

that each of the South Coast and

MCESD's rules are more stringent than

the other in certain respects. MAG plan,

p. 10-35. The MAG plan acknowledges

that Rule 403 contains more stringent

control measure requirements than

those imposed by Rule 310. For

example, Rule 403 requires that water

be applied to soil not more than 15

minutes prior to moving the soil and

requires open storage piles to be

watered twice per hour or covered.

However, the MAG plan indicates that

Rule 3 10's 20 percent opacity limit is

generally more restrictive than Rule

403's property line standard because a

20 percent opacity fugitive dust plume

typically disperses to zero visibility

within 50 feet downwind of a source.

MSM Study, p. C-12. The MAG plan

concludes that, on balance, Rule 310 is

equally stringent compared to Rule

403's construction site requirements.

We agree with this conclusion with the

caveat that we believe Rule 310 and/or

dust control plans require additional

control measures for dust suppression.

This caveat is addressed in the MAG

plan's commitment to research, develop

and incorporate additional requirements

for dust suppression practices/

equipment for construction activities

into dust control plans and/or Rule 310.

The MAG plan does not discuss any

construction site measures from other

areas as potentially more stringent

measures. Based on our work with the

Las Vegas area, we have identified

requirements in Clark County Health

District permits that are potentially

more stringent than Maricopa County's

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measures. 27 These requirements include

stand tanks on projects that are 10 acres

or more in size, an additional, separate

water truck when using a trencher or

when screening, a separate water truck

or pull during landscaping, maintaining

all stockpiles in a moist condition, etc.

We propose to find that Rule 310's

existing provisions and Maricopa

County's second enforceable

commitment to research, develop and

incorporate additional requirements for

dust suppression practices/equipment

into Rule 310 and/or DCPs are

consistent with Clark County's

requirements.

We have also identified a requirement

in Imperial County Regulation VIII that

is potentially more stringent than

Maricopa County's measures. Imperial

County Regulation VIII requires that

water be applied 15 minutes prior to

handling or transferring bulk material,

chemical/physical stabilization, or

sheltering/enclosure of the operation

and transfer line. We propose to find

that Maricopa County's second

enforceable commitment to research,

develop and incorporate additional

requirements for dust suppression

practices/equipment into Rule 310 and/

or DCPs is consistent with Imperial

County's requirements.

For these reasons, we propose to find

that the MAG plan provides for the

inclusion of the MSM applicable to the

Phoenix area for construction sites and

activities.

i. Agricultural sources. The

agriculture source category covers all

dust generating activities and sources on

farms and ranches in the Maricopa

nonattainment area. These activities and

sources include land planning, tilling,

harvesting, fallow fields, prepared

fields, field aprons, and unpaved roads.

Maricopa County is rapidly

urbanizing with agricultural land being

converted into other uses at a rate of

approximately 6,000 acres per year.

Cathy Arthur, MAG, December, 1997.

Despite the conversion of agricultural

lands to other uses, agricultural sources

are expected to continue to contribute to

PM-10 emissions for the foreseeable

future, especially in relation to the PM10 24-hour standard.

The MAG plan identifies a number of

potential BACM for agricultural sources.

MAG plan, pp. 5-66 thru 5-72 and pp.

6-12 through 6-13.

In 1998, Arizona passed legislation

establishing an Agricultural Best

Management Practices (BMP) committee

for the purpose of adopting by rule by

27 These requirements are not in Clark County's

fugitive dust rule, but rather are required practices

in dust control permits.

June 10, 2000, an agricultural general

permit specifying BMPs for regulated

agricultural activities to reduce PM-10

emissions in the Maricopa PM-10

nonattainment area. The Committee also

is required to adopt and implement an

education program by June 10, 2000,

and affected agricultural sources are

required to implement at least one BMP

by December 31, 2001. A.R.S. 49-

457.A-H, M. On June 29, 1999, we

approved this legislation as a SIP

revision meeting the requirement for the

implementation of RACM in

189(a)(1)(C) and at the same time

withdrew our commitment to adopt

RACM controls for agricultural that we

included in the 1998 PM-10 FIP. 64 FR

34726.

The MAG plan relies on the State's

commitment in A.R.S. 49-457 to adopt

and implement BMPs to meet the

requirement to provide for the

implementation of BACM for

agricultural sources. MAG plan, p. 7-

156 and Letter from ADEQ to EPA,

September, 1998, submitting the

commitment as a SIP revision. The plan

also relies on the statutory commitment

to meet the MSM requirement in CAA

section 188(e). MAG plan, p.10-25.

Arizona's statutory BMP commitment

is similar to the commitment we made

in our 1998 PM-10 FIP. 63 FR 41326

(August 3, 1998). As part of the RACM

demonstration in the FIP, we

promulgated a commitment, codified at

40 CFR 52.127, to ensure that RACM for

agricultural sources will be

expeditiously adopted and

implemented. For agricultural sources,

the State is using a similar strategy to

address the RACM, BACM and MSM

requirements.

We propose to find that the State's

commitment to adopt and implement

agricultural BMPs adequately addresses

requirement to implement BACM and

include MSM. The potential BACM

explicitly identified in the MAG plan

will be considered during the BMP

development process.

We have, beginning with the

proposed rulemaking for our 1998 PM10 FIP and culminating in Ninth Circuit

litigation on both the FIP and our SIP

approval, explained at length our

reasoning that a commitment to

implement PM-10 controls beginning in

June 2000 for agricultural fields and

aprons in the Phoenix PM-10

nonattainment area rather than the

immediate implementation of fullydeveloped regulations for those sources

meets the RACM requirement in CAA

section 189(a)(1)C). See 63 FR 15920,

15935-15936 (April 1, 1998); 63 FR

41332-41334; 63 FR 71817. See also

Brief for Respondents in Ober v.

Browner, No. 98-71158, at 43-59 (9th

Cir., filed Oct. 2, 1998) (petition for

review challenging EPA's FIP

commitment to adopt and implement

RACM for agricultural sources), and

Brief for Respondents in Ober v.

Browner, No. 99-71107, at 16-40 (9th

Cir., filed Aug. 26, 1999) (petition for

review challenging EPA's approval of

the State's commitment to adopt and

implement agricultural BMPs as

meeting the RACM requirement of the

CAA).

In the context of this proposed action,

our reasoning in short is that a legally

binding commitment-embodied in the

State statute establishing a committee

that is required to adopt a general

permit specifying BMPs and identifying

specific deadlines for their

implementation-meets the statutory

requirement in CAA section 189(b)(1)(C)

since it is a "provision to assure that

best available control measures" are

implemented by a fixed deadline. While

in preparing the FIP, we reviewed

measures adopted by the South Coast

for the control of PM-10 emissions from

agricultural sources, we concluded that

agricultural sources in the United States

vary by factors such as regional climate,

soil type, growing season, crop type,

water availability, and relation to urban

centers, therefore, each PM-10

agricultural strategy is uniquely based

on local circumstances. As a result, we

could not, without further analysis,

conclude that the South Coast controls

should be immediately implemented in

the Maricopa area.

Furthermore, we determined that the

goal of attaining the PM-10 standards in

Maricopa County with respect to

agricultural sources would be best

served by engaging all interested

stakeholders in a joint comprehensive

process on the appropriate mix of

agricultural controls to implement in

Maricopa County. We stated our belief

that this process, despite the additional

time needed to work through it, will

ultimately result in the best and most

cost-effective controls on agricultural

sources in the County.

While A.R.S. 49-457 does not use the

term "best available control measure,"

its definition of BMPs is consistent with

the criteria in EPA's guidance. "Best

management practices" are defined in

A.R.S. 49-457.N.3 as "techniques

verified by scientific research, that on a

case by case basis are practical,

economically feasible and effective in

reducing PM-10 particulate emissions

from a regulated agricultural activity."

The broad definition of BMPs in the

Arizona statute authorizes the BMP

committee to adopt measures that will

comply with our definition of BACM.

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Moreover, as noted above, the statute

provides for BMP implementation that

begins with an education program by

June 10, 2000 and culminates in full

implementation of the BMPs by

December 31, 2001.28

Similarly, we have concluded that the

definition of BMPs in the Arizona

statute is broad enough to authorize the

BMP committee to adopt measures that

meet the level of control in the

requirement to include MSM in CAA

section 188(e) as we propose to interpret

it in this proposed action. In reviewing

measures in other SIPs and/or that have

been adopted elsewhere, MAG

determined that cessation of high wind

tilling and soil erosion control plans

were the most stringent measures

available that had potential application

for agricultural sources in Maricopa

County. MAG plan p. 10-47. These

measures are included in South Coast

Rule 403 which requires PM-10

controls for all fugitive dust sources,

including agricultural sources. In

December 1998, South Coast adopted a

set of conservation practices for

agricultural sources to use to reduce

fugitive dust. These practices were

developed in consultation with affected

stakeholder groups. See Guide to

Agricultural PM-10 Dust Control

Practices. The BMP task force will

consider these measures during the

development of the BMPs. MAG plan p.

10-47. After the BMPs and supporting

technical documents are submitted to

EPA, we will review them to determine

if their level of control is as stringent as

the South Coast rule or adequately

justifies why such level would not be

feasible in the Maricopa area. As discussed elsewhere in this TSD,

we propose to interpret section 188(e) to

require implementation of MSM as

expeditiously as practicable. For the

reasons stated above, in our FIP, and in

our approval of the State legislation as

meeting the RACM requirements of the

CAA, we conclude that the

implementation schedule in the State

statute meets that test. Finally, we

conclude that the commitment in the

State legislation meets the requirement

that "the plan include[s] the most

stringent measures * * *" Emphasis

added.

j. Residential wood combustion. The

residential wood combustion (RWC)

category includes emissions from the

burning of solid fuel in residential

28 Of course, once adopted and submitted to EPA

as a SIP revision, the individual BMPs will have to

be evaluated to determine if they comply in their

specifics with the BACM requirement. Here we

need only determine that the Arizona statute

provides sufficient authority to assure that BACM

will be implemented by June 10, 2000.

fireplaces and woodstoves as well as

barbecues and firepits.

Measures to control PM-10 from

residential woodburning include public

education program, woodburning

curtailment programs, retrofit

requirements and restrictions or bans on

the installation of woodburning stoves

and/or fireplace. In total the MAG plan

list 11 potential BACM and 10 potential

MSM. MAG plan Tables 5-2 and 1-7.

We believe this list is complete and

propose to find that the MAG plan

evaluates a comprehensive set of

residential woodburning measures.

MCESD Rule 318, Approval of

Residential Woodburning Devices,

establishes standards for the approval of

residential woodburning devices that

can be used during restricted-burn

periods. Maricopa County's Residential

Woodburning Restriction Ordinance

provides that restricted-burn periods are

declared by the Control Officer when

the Control Officer determines that air

pollution levels could exceed the CO

standard and/or the PM standard (150

gg/m 3). We approved Rule 318 and an

earlier version of the ordinance (revised

April 21, 1999) as providing for the

implementation of RACM. See 64 FR

60678 (November 8, 1999).

MCESD revised the ordinance on

November 17, 1999 to allow the Control

Officer to declare restricted-burn

periods when the particulate matter

pollution levels could exceed the

"particulate matter no-burn standard" of

120 gg/m 3. In addition, A.R.S. section

9-500.16 and A.R.S. section 11-875

(1998) require cities and the County to

adopt by December 31, 1998, an

ordinance that prohibits the installation

or construction of a fireplace or wood

stove unless it is a fireplace with a

permanently installed gas or electric log

insert, a fireplace or wood stove that

meets EPA's Phase II wood stove

requirements, or a fireplace with a wood

stove insert that meets EPA's Phase II

stove requirements. Most jurisdictions

have adopted or have committed to or

indicated that State law requires them to

adopt the required ordinance. See MAG

Plan, pp. 7-55 to 7-64.

With these additional controls, the

overall residential woodburning

restriction program is strengthened and

goes beyond the existing RACM-level

program. Both strengthening and

expanding existing programs are key

criteria for demonstrating the

implementation of BACM. See

Addendum at 42013. Where the MAG

plan has rejected potential BACM, it

provides a reasoned justification for the

rejection.

The MAG plan identified a number of

potential MSM for residential wood

combustion. Except for the adoption of

a lower threshold for calling no burn

episodes, the plan does not provide for

the adoption of any of these measures

but provides reasoned and acceptable

justifications for their rejection.

Therefore, we propose to find that the

MAG plan provides for the inclusion of

MSM.

k. Secondary ammonium nitrate.

Secondary ammonium nitrate is formed

by a chemical reaction in the

atmosphere between oxides of nitrogen

(NOx) and ammonia (NH3). Ninety

percent of NOx comes from motor

vehicle exhaust (both on and off road)

and 99.9 percent of NH 3 comes from

animal wastes. See MAG plan, Table 3-

1.

Two potential BACM were identified

for ammonia nitrate control: Reduce

emissions of ammonia and nitrates from

agricultural operations and require

animal waste management plans for

farms/ranches with more than 50

animals. The first measure involves

tilling in of manure used as fertilizer

within 48 hours of application. MAG

plan, Table 6-1, measure 97-AG-3. The

second measure would focus on

reducing ammonia emissions from

livestock waste during the winter

months when conditions are most

conducive to ammonium nitrate

formation. MAG plan, Appendix B,

Exhibit 5, p. 5-70. For MSM, no

measures were found that required

animal waste management plans for

farms or ranches and no other measures

were identified. See MAG plan, Table

10-7. A large number of measures that

could reduce NO, emissions were

identified and have been evaluated for

on-road motor vehicles and nonroad

engines. We believe these list of

measures is complete and propose to

find that the MAG plan evaluates a

comprehensive set of potential controls

for ammonium nitrate.

Data from earlier studies indicate that

ammonia emissions would need to be

reduced by 80 percent to have an

appreciable impact on ambient

concentrations of ammonium nitrate.

MAG plan, Appendix B, Exhibit 5, p. C1. Essentially all ammonia emissions in

the inventory are from livestock and not

from the application of manure to

agricultural fields. As result, controls on

the application of manure are very

unlikely to have any impact on PM-10

levels the Phoenix area and therefore are

not technologically feasible. 29 The

estimated reduction in ammonia from

29 We consider a measure technologically feasible

for an area only if it has the potential to reduce

emissions in manner that reduces ambient

concentrations in the area.

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implementing waste management plans

is 30 percent, far short of the 80 percent

needed to show impact on PM-10 levels

(MAG plan, Appendix B, Exhibit 5, p.

5-72), so we also believe that this

measure is currently not technologically

feasible.

Other than the on-road vehicle and

nonroad engine categories, we do not

believe that there are any other sources

of NO, that should be called significant

in terms of contributing to ammonium

nitrate levels.

Because the MAG plan includes an

extensive number of measures for

controlling NO, sources and no measure

are identified for the control of

ammonia as technologically feasible, we

propose to find that the MAG plan

provides for the implementation of

RACM and BACM and for the inclusion

of MSM for secondary ammonium

nitrates.

1. MCESD's commitments to improve

compliance and enforcement of its

fugitive dust rules. MCESD has

committed to expanding and improving

the compliance and enforcement

program for its fugitive dust rules. These

commitments are found in Maricopa

County, 1999 Revised Measure 6,

adopted December 15, 1999. A narrative

description of the commitments and

other program changes are found in

Appendix IV, Exhibit 3 to the MAG

plan's modeling TSD. MCESD has also

committed to continuing to improve

Rule 310 and Rule 310.01. These

commitments are described in section

F.3.g. "Construction Sites and

Activities."

These improvements include

increased public outreach and

education, increased funding and

staffing, increased inspection frequency,

revised enforcement policies, and

commitments to program evaluations

and improvements. They address many

of the program areas that are key to

improving compliance and we believe

form a solid program for increasing the

effectiveness of the County's fugitive

dust program.

Staffing. By the end of January, 2000,

the inspection staff will increase to eight

inspectors, 1 supervisor, 1 aide and 2

enforcement officers. By April, 2000, the

County Attorney's office will hire an

attorney to expedite civil litigation and

to assist with prosecuting Class One

Misdemeanor cases. A coordinator will

be added to the Small Business

Environmental Assistance Program to

assist smaller builders and construction

companies and to help develop and

implement education programs. In total,

resources devoted to the fugitive dust

program will be 15 positions, a 25

percent increase over previous levels.

This level of staffing is in contrast to the

less than 1 staff position devoted to the

program in 1996.

After reaching the committed staffing

level, MCESD will review the program

in March 2000 to evaluate its

effectiveness and the potential need to

add more staff.

Organization. A new enforcement

section has been created under the

direct supervision of the MCESD

Director/Air Pollution Control Officer

(APCO). This position streamlines

enforcement by reducing senior

management review and approval of

enforcement actions and allows

enforcement officers to submit directly

to the APCO's desk all enforcement

actions requiring APCO approval.

In addition, inspectors will be located

in two new regional offices to provide

quicker response times to dust-related

complaints and allow more time in the

field.

Funding. Revenue for fugitive dust

program is estimated at $1.12 million

from annual earth moving permit fees,

a $772,000 increase over the previous

level that is due to the permit fee

increases adopted in 1998.

Inspection program. MCESD will

develop by April, 2000 inspection

priorities for vacant lots and unpaved

parking lots that consider lot size and

number of sources, with larger lots

being inspected first and smaller lots in

succeeding years. A number of cities

have municipal programs to address

these sources; therefore, the Department

will initially direct its inspections to

cities lacking such programs. It will also

track the city plans that are required by

State statute to stabilize target unpaved

roads, alleys and unpaved shoulders.

MCESD has also increased inspection

rates and improved procedures for

permitted sources such as construction

sites including:

* Proactively inspecting sites larger

than 10 acres, 3 to 6 times per year and

inspect smaller sites once within 30

days of project start date.

* Scheduling weekend inspections

randomly once per month.

* Providing a shortened complaint

response time with a goal of 8 hours for

high priority complaints and

maintaining the current goal of 24 hours

for others.

* Revising standard operating

procedures and checklists for fugitive

dust inspections to be consistent with

the revised rules.

* Revising inspection standard

operating procedures to have inspectors

check for records and inspect fugitive

dust sources at permitted stationary

sources.

Enforcement program. By April 2000,

MCESD will revise it fugitive dust

enforcement policy to

* include guidelines for initiating

various enforcement actions

* include guidelines for reinspecting

define timely and appropriate action by

laying out guidelines for which type of

violation is appropriate for specific

enforcement actions and for the time

frames for escalating enforcement

actions when appropriate

* identify priority violations

* include guidelines for when to seek

penalties reflecting the economic benefit

of noncompliance, if feasible

* include guidelines for seeking and

determining higher penalties for repeat

violators

* guidelines for inspectors to handle

predetermined citation categories form

observation to justice court Enforcement

action options include issuing an Order

of Abatement, filing a Misdemeanor

Complaint in Justice court, or asking the

County Attorney to seek a civil penalty

in Superior Court.

Inspectors will handle certain

predetermined citation category

violations and will be responsible for

case development from observance of a

violation to filing of the actual citation

in the justice court. Having the

inspectors handle routine cases will

enable the enforcement officers to work

on resolving cases involving more

serious and complicated violations.

Public outreach/education. Public

outreach and education consists of staff

training, educating the regulated parties,

developing good working relationships

with other involved parties such as the

cities, and making the program more

understandable. Increased education of

both inspectors and the regulated

industry increases compliance.

Among the public outreach and

education efforts will be:

* Inspector training on case

development.

* Inspector training on revised test

methods.

* City staff training on preparing

inspection reports and notices of

violation.

* On-going training at the local

community college.

* Making information available on

MCESD website.

* Distribution of information through

city building departments and other

sources.

Program evaluation and tracking.

MCESD will track the number of

inspections, number and type of

enforcement actions, amount of

penalties assessed, and amount of

penalties collected. It will also conduct

mid-year reviews of the program in

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September, 2000 and again in March

2001 to evaluate progress and future

needs.

G. Attainment Date Extension

1. Apply for an Extension

We interpret this requirement to mean

that the State must apply in writing for

an extension and that the extension

request must accompany the SIP

submittal containing the demonstration

that the area will attain by the most

expeditious alternative date practicable.

The public must be provided reasonable

notice and a public hearing on the

request before it is submitted.

MAG, as the lead air quality planning

agency for the Phoenix metropolitan

area, formally requested an extension of

the PM-10 nonattainment deadline to

December 31, 2006 based on

documentation in Chapter 10 of the

MAG plan and Appendix C, Exhibit 5 of

the MAG plan. MAG plan, p. 10-2. This

extension request is an integral part of

the MAG plan and was subject to public

hearing along with the rest of the plan.

2. Demonstrate the Impracticability of

Attainment by December 31, 2001

In order to demonstrate

impracticability, the plan must show

that the implementation of BACM (as

determined by our guidance) on

significant sources categories will not

bring the area into attainment by

December 31, 2001.

To demonstrate the impracticability of

attainment by 2001, the MAG plan

derived from the air quality modeling a

change in PM-10 concentrations per

change in emissions using the modeled

concentration for the year 2006 and

observed concentration for the year

1995 at Greenwood monitor and the

overall change in emissions between the

two years. MAG plan, p. 8-10. Using

this information, the plan estimates that

the annual concentration in 2001 will be

52.21 gLg/m 3 after implementation of

BACM. Because the projected 2001

annual concentration is still above the

50 gLg/m 3 annual NAAQS, the MAG plan

concluded that it was impracticable to

attain by 2001.30 MAG plan, p. 8-10.

Based on our analysis of control

measures in the MAG plan as described

in the preceding sections, we propose to

find that the MAG plan provides for

implementation of BACM as required by

CAA section 189(b)(1)(C). Based on the

modeling analysis in the plan, we also

propose to find that the MAG plan also

30

1n addition the MAG plan shows that

implementation of controls on the de minimis

source categories would not produce enough

emission reductions to show attainment in 2001.

MAG plan, p. 9-11.

demonstrates that attainment by 2001 is

impracticable with the implementation

of BACM.

3. Complied With Commitments and

Requirements in the SIP

We interpret this criterion to mean

that the State has implemented the

control measures in prior SIP revisions

it has submitted to address the CAA

requirements in sections 172 and 189

for PM-10 nonattainment areas. It does

not include measures being approved in

this action.

The two SIP revisions that Arizona

has submitted to address PM-10 are the

1991 MAG moderate area plan and the

1997 microscale plan.

The 1991 MAG plan includes a broad

range of measures to address PM-10

including controls for constructions

sites, paved road, unpaved roads,

unpaved parking areas, vacant lots, and

woodburning. The plan also included

reasonably available control technology

for stationary sources and a wide range

of transportation control measures. The

implementation of the measures in this

plan are described in the MAG plan at

pp. 10-10 to 10-25. The principal

controls in this plan were Rule 310 and

the County woodburning ordinances.

The plan also contained a large number

of commitments from the local

jurisdictions to various measures. Most

of the measures represented "business

as usual" actions by the jurisdictions to

do infrastructure (e.g., road)

improvements, to implement existing

building codes or take actions already

underway for the carbon monoxide

plan. MAG plan, pp. 10-13 through 10-

24.

The 1997 Microscale plan focused on

fugitive dust sources such as

construction sites, vacant lots, unpaved

roads, unpaved parking lots, and

agriculture. The principal controls in

this plan were improvements to the

implementation of Rule 310 and

coordination with the cities to improve

fugitive dust control. Implementation of

the measures in the Microscale plan are

discussed in Maricopa County

commitments, 1998 Revised Measure 6.

From available information in the

MAG plan, we believe that the

commitments and requirements in these

plans have been met. We, therefore,

propose to find that the State has

complied with the requirements and

commitments in its implementation

plan.

4. Include the Most Stringent Measures

The MAG plan excluded no source

categories of directly-emitted PM-10

from its MSM analysis instead simply

started its evaluation of MSM by

identifying candidate measures for any

source category of PM-10 present in the

Phoenix area. MAG plan, p. 10-25. To

identify candidate MSM, MAG's

contractor Sierra Research interviewed

people knowledgeable about PM-10

controls, reviewed the documents used

to develop the candidate list of BACM

and obtained copies of current air

quality control measures from most

other States including both SIP and nonSIP measures. MSM Study, p. 1-2.

After a comprehensive list of

candidate MSM was developed, each

measure was screened against the

corresponding Maricopa measure to

identify those with more restrictive

emission limitations, more extensive list

of affected sources, fewer exemptions,

and/or one or more substantive

regulatory provisions not found in the

Maricopa measure. The remaining MSM

were grouped by source category and

were either included in the plan or a

reasoned justification for rejecting the

measure was provided. MSM study,

Table 3-1 and MAG plan, p. 10-46.

We propose to find that the MAG plan

demonstrate to our satisfaction that it

includes the most stringent measures

that are included in the implementation

plan of any State, or are achieved in

practice in any State, and can be

feasibly be implemented in the Phoenix

area.

We have discussed identification and

adoption of MSM and the rejection of

any MSM for each category deemed

significant for BACM earlier in this

preamble. The MAG plan identifies

three MSMs for categories considered de

minimis in the BACM analysis. These

categories are cattle feed lots,

incinerators, and charbroilers.

Cattle feed lots: MCESD Rule 310.01

requires that owners/operators of

commercial feedlots and/or livestock

areas apply dust suppressants, apply

gravel, or install shrubs and/or trees

within 50 to 100 feet of animal pens.

The MAG plan identifies South Coast

Rule 1186 requirements for livestock

operations as a potentially more

stringent requirements than Rule

310.01. However, the two rules control

different sources at commercial

feedlots/livestock areas. South Coast

Rule 1186 requires controlling unpaved

roads and hay grinding at dairy and

horse farms but does not address

fugitive dust emissions from disturbed

open areas. MCESD Rule 310.01

controls fugitive dust emissions from

disturbed open areas at dairies and

cattle lots, but not unpaved roads and

hay grinding.

In the Maricopa County PM-10

nonattainment area, there is only one

cattle feedlot and less than half the

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number of dairies compared to those

subject to South Coast Rule 1186.

Similar to South Coast, unpaved roads

at dairies are low travel (10 to 20 ADT)

and represent a very small source of

emissions in the Phoenix area and

controls on them would not advance the

attainment date. We, therefore, believe

we can find that the MAG plan provides

for the implementation of MSM to our

satisfaction without Rule 1186

provisions for unpaved roads at cattle

feed lots. In Maricopa County, hay

grinding activities occur primarily at

feed mills (as opposed to dairies) which

are permitted sources and thus already

subject to control requirements.

Incinerators: The MAG plan identifies

Clark County's Rule 26 as having a more

stringent opacity limit than MCESD's

Rule 313. Clark County limits opacity

from existing incinerators to 5 percent

while Maricopa's limit is 20 percent.

MAG plan, Table 10-7. Incinerators are

a very small source in the Phoenix

nonattainment area. In 1994 there were

32 incinerators that together emitted

2.56 metric tons per year (7.1 kg per

day). 1994 Regional PM-10 Inventory,

p. 4-17. Because incinerators are so

small a source and controls on them

would not advance the attainment date,

we propose to find that the MAG plan

provide for the inclusion of MSM to our

satisfaction without including Clark

County's opacity limit for incinerators.

Charbroiling: Emissions from

charbroiling and frying meat are

estimated to 0.6 mtpd or 227 mtpy. 1994

Regional PM-10 Inventory, p. 4-25.

This is 0.4 percent of the daily directlyemitted PM-10 inventory in 1994 and

0.4 percent of the annual inventory in

1994. MCESD has committed to develop

a new rule to require existing and new

chain-driven and underfired

charbroilers, typically found in

restaurants specializing in grilled meat

products, to be equipped with emission

control equipment. South Coast is

developing a new rule to deal with

underfired charbroilers and MCESD will

wait until South Coast completes its

rulemaking to adopt this measure.

MCESD is projecting adoption of its rule

in Spring, 2001. Maricopa County

commitments, Revised Measure 23. We

propose to find that implementation of

this rule is expeditious. Waiting on

South Coast to complete its rulemaking,

which will establish control

requirements for underfired

charbroilers, is appropriate given that

the South Coast rule when adopted will

set the standard for control on these

types of charbroilers.

5. Demonstrate Expeditious Attainment

For the reasons discussed below, we

propose to find that the MAG plan

demonstrates attainment by the earliest

date practicable after December 31, 2001

as required by section 189(b)(1)(A)(ii) of

the CAA. We also propose to find that

the attainment demonstration relies on

control measures that either are

approved or are being proposed for

approval and meet our SIP

enforceability criteria; that the

emissions estimates assigned these

measures in the attainment

demonstration are reasonable; and the

measures are being implemented on a

schedule that is as expeditious as

practicable and will result in attainment

by the earliest practicable date. See

discussion below.

a. Air quality modeling. A modeled

attainment demonstration for the PM-10

annual standard should first estimate

the temporal and spatial distribution of

PM-10 and PM-10 precursor emissions

that result from the adopted control

measures by the attainment date. It

should then simulate the ambient air

concentration of these emissions in an

air quality model and show that all

locations within the nonattainment area

have annual average PM-10

concentrations below the level of the

annual PM-10 standard of 50 gg/m3.

See "Guidelines on Air Quality

Models," 40 CFR part 51 appendix W,

section 7.2.2. and "PM-10 SIP

Development Guideline," EPA-450/2-

86-001, June 1987.

To provide context for our evaluation

of the air quality modeling in the MAG

plan, we will first briefly describe the

steps in developing a modeled

attainment demonstration and how the

MAG plan performed each step.

Step 1. A modeling base case is

developed to replicate PM-10

concentrations for specific recent days

by simulating the emissions and

meteorology that occurred for those

days, by hour and by location

throughout the area being modeled (that

is, the model domain). For some input

parameters, alternative plausible values

are tried in a diagnostic process to

ensure that the model is performing in

a physically reasonable way. PM-10

concentrations from the model output

are compared to monitored values to

evaluate the performance of the model.

The base case for the MAG plan

consisted of the application of the urban

airshed model with the limited

chemistry module (UAM/LC) to each of

65 days during 1995. The results from

modeling each of these days are then

averaged together to get the modeled

annual PM-10 concentration. 1995 was

used as the base year because an

intensive inventory and monitoring

study was performed during it; the 65

days coincided with the available PM10 24-hour average monitoring data,

which are collected once every 6 days.

During 1995 the peak monitored annual

PM-10 concentration was 60.01 gg/m 3

at the Greenwood monitor while the

model predicted a peak concentration of

75.91 gg/m3 at a location away from the

Greenwood monitor. MAG TSD, Chapter

111.31

Step 2. After the base case model is

developed, emissions are projected into

the future. Projections are based on

particular facilities's expansion plans,

business and socioeconomic

projections, and projections of the effect

of changing technology and of the

control measures that are already in

place. The model simulation is repeated

with these future emissions but with the

same meteorological inputs as before.

This simulation shows how a day

meteorologically conducive to high PM10 concentrations will look in the future

if no new controls are implemented.

The resulting modeled concentrations

can be used to derive an estimate of the

additional emission reductions needed

to attain the air quality standard.

For the MAG plan, emissions are

projected to 2006 (which MAG found to

be the earliest practicable attainment

year). Before additional controls, the

2006 future peak PM-10 annual average

was simulated to be 86.72 gLg/m 3 -

Because this was above the NAAQS of

50 gg/m 3, the modeling showed that

additional control measures were

needed. MAG plan, p. 8-6.

Step 3. The effect of control measures

on ambient concentrations are

simulated by changing the model

emission inputs for future years to

reflect higher implementation rates or

larger emission reductions from

additional controls. Additional

measures are tried if PM-10

concentrations are still above the

standards.

Attainment is demonstrated when

sufficient emission reductions are in

place so that modeled concentrations in

every grid square are below the

standard.

MAG showed that with additional

controls, the peak annual PM-10

concentration in 2006 is 49.70 gg/m 3,

which is below the annual PM-10

NAAQS of 50 49.70 jig/m 3, thus

31 The MAG TSD is the "Revised Technical

Support Document for Regional PM-10 Modeling in

Support of the Revised MAG 1999 Serious Area

Particulate Plan for PM-10 for the Maricopa County

Nonattainment Area," MAG, February 2000 found

in Appendix A, Exhibit 7 of the MAG plan.

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demonstrating attainment. MAG plan, p.

8-12.

In evaluating the air quality modeling

in the MAG plan, we reviewed the

choice of models; the selection of

episodes to model, the selection of the

modeling domain and grid resolution,

the methods of preparing wind,

temperature, and mixing height fields

data; the selected initial and boundary

conditions values; the modeling

emission inventories; the procedures for

and results of quality assurance,

diagnostic testing and sensitivity

testing; and selected modeling

performance goals and model results vis

a vis these goals. We have found them

all generally acceptable. See our

detailed evaluation in EPA TSD section

"Demonstrate Attainment by the Most

Expeditious Alternative Date Practicable

after December 31, 2001."

The modeling performed for the MAG

plan is as sophisticated as any that has

been performed for a PM-10 SIP. While

there are several problems associated

with the model's performance for

secondary particulates and several other

shortcomings of the modeling and its

documentation, the dominance of the

contribution of primary particulates

from fugitive dust to PM-10

concentrations in the Phoenix area

obviates these concerns. At worst the

MAG plan's modeling is akin to

modified rollback, an approach that is

acceptable under EPA modeling

guidance for PM-10. We therefore

propose to approve the modeling for the

annual NAAQS because it provides a

credible demonstration that the credited

control measures will provide for

attainment of the annual standard by

2006.

b. Control measures relied on for

attainment. For demonstrating

attainment, the MAG plan relies on

reductions in directly-emitted PM-10

from 12 measures. MAG plan, Table 8-

2. We have listed each measure; the

rule, commitment or state statute

through which it is implemented, and

its emission reductions in Table 1-1.

TABLE 1-1.-CONTROL MEASURES RELIED ON IN THE ATTAINMENT DEMONSTRATION

Emission re- Measure Implementation mechanism duction

(mtpd)

Strengthening and Better Enforcement of Fugitive Dust Rules Rule 310 and Maricopa County Commitments, 1999 Revised 60.6

(Construction sites). Measure 6.

Unpaved roads and alleys ........................................................... Rules 310 and 310.01, Maricopa County Commitments, 199 12.2

Revised Measures 6 & 17, City/Town Commitments for Unpaved Roads and Alleys.

Unpaved parking lots ................................................................... Rules 310 and 310.01 and Maricopa County Commitments, 3.7

1999 Revised Measure.

Vacant disturbed lots ................................................................... Rules 310 and 310.01 and Maricopa County Commitments, 1.8

1999 Revised Measure 6.

01 PM-1 0 efficient street sweepers (MAG) ..... MAG Commitment, "PM-10 Efficient Street Sweepers" City/ 1.1

Town/County Commitments for Street Sweeping.

Curbing, paving, or stabilizing shoulders on paved roads .......... City/Town/County Commitments for Stabilizing Shoulders ........ 1

Curbing paving or stabilizing unpaved access points ................. City/Town/County Commitments for Stabilizing Unpaved Ac- 0.4

cess Points.

PM-10 episode thresholds .......................................................... Maricopa County Residential Woodburning Restriction Ordi- 0.07

nance.

Restaurant charbroiler controls (Maricopa County commitment) Maricopa County Commitment, 1999 Revised Measure 23 ...... 0.07

Cleaner Burning Gasoline ............................................................ ADEQ Regulations (already SIP approved) ............................... 0.03

Pre-1988 Heavy-Duty Diesel Vehicle Standards ....................... A.R.S. 49-542 F.7 . ..................................................................... 0.02

Coordinate traffic signals ............................................................. City/Town/County Commitments for synchronizing traffic lights. 0.01

We have evaluated each of these

measure to ensure that it meets our SIP

enforceability criteria. These criteria

ensure that the measure's compliance

requirements'applicability, performance

standards, compliance schedule, and

monitoring methods-are clear.

We have also evaluated the emission

reductions credited to each measure to

ensure they are reasonable. In

particular, we looked at the reduction

estimates for Rules 310 and 310.01.

The MAG plan assumes an

incremental increase in rule

effectiveness for these rules from 66

percent in 1998 to 80 percent in 2006.

MAG TSD, Appendix IV, Exhibit 1,

Committed Measure 1. Rule

effectiveness (RE) accounts for emission

reductions lost because of

noncompliance, control equipment

downtime, failure to apply adequate

controls, or failure to use control

equipment properly. One hundred

percent rule effectiveness is the ability

of a regulatory program to achieve all

the emission reductions that could be

achieved by full compliance with the

applicable regulations at all sources at

all times.

We have established policies on

applying rule effectiveness factors for

both base year and projected year

inventories of volatile organic

compounds (VOC), a precursor to ozone.

See General Preamble at 13503 and

"Rule Effectiveness Guidance:

Integration of Inventory, Compliance,

and Assessment Applications." USEPA,

OAQPS, EPA-452/R-94-001, January

1994, (RE Guidance). In general, we

encourage states to derive local

category-specific RE factors. If there are

no such local RE factors, we require the

use of an 80 percent effectiveness

default value in VOC inventories.

General Preamble at 13503.

We have not established any explicit

guidance for applying RE to particulate

matter sources. We know, however, that

PM sources like VOC sources are not in

full compliance with applicable rules at

all times; therefore, some RE factor

needs to be applied. For this

rulemaking, we have applied the

existing Agency RE guidance for VOC

sources to emission reduction estimates

for Rule 310 and Rule 310.01.

The items that influence compliance

with a rule and thus the appropriate RE

factor are the clarity of the rule, its

compliance requirements and the

complexity of the controls required by

the rule; the source's actions; and the

implementing agency's actions. See RE

Guidance, pp. Table 1-1 and Appendix

C.

Under our guidance, a state is allowed

and required to use a 80 percent RE

factor absent evidence to the contrary.

General Preamble at 13503. In this case,

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the evidence that we have is that

compliance for Rule 310 was below this

level as of early 1998. MAG, with

concurrence of MCESD, assumed a 30

percent compliance rate for the Rule 310

in the 1995 base year modeling.

Inspections by MCESD in early 1998

indicated that the compliance rate with

the rule was 66 percent. MAG TSD,

Appendix II, Exhibit 6, "Documentation

on Assumption of Rule 310 Control

Efficiency and Compliance Rate."

Over the last few years, MCESD has

made substantial changes to its fugitive

dust control program, many designed to

improve compliance. MCESD has also

committed to a number of additional

changes which we have described

earlier. We believe that an 80 percent

rule effectiveness in 2006 is appropriate

given these changes and MCESD's

commitments to improve compliance

with Rules 310 and 310.01. These

improvements cover rule and test

method revisions, increased public

outreach and education, increased

funding and staffing, increased

inspection frequency, revised

enforcement policies, and commitments

to program evaluations and

improvements. They address many of

the program areas that are key to

improving compliance.

In our TSD (in the section "Extension

Request-Demonstrate Attainment by the

Most Expeditious Alternative Date

Practicable after December 31, 2001"),

we have compared the MCESD's fugitive

dust program in 1996 to the program

that will be in place by 2006 based on

MCESD's commitments in the MAG

plan and its actions to date. This

comparison clearly shows the scope of

improvements to the MCESD's fugitive

dust program and supports our

proposed finding that an 80 percent RE

in 2006 for Rule 310 and Rule 310.01 is

appropriate.32

Finally, we have looked at the

implementation schedule for each

measure to assure that the MAG plan

provides for expeditious

implementation. Except for paving of

some unpaved roads, adoption of the

charbroiler rule, heavy duty diesel

standards, and the purchase and

deployment of the PM-10 efficient

street sweepers, all the measures relied

on in the attainment demonstration are

currently in effect.

However, attainment of the PM-10

annual standard in the Phoenix area

depends on a high level of compliance

with MCESD's fugitive dust rules. The

32 The cities and towns in Maricopa County are

also increasing their efforts to address fugitive dust

sources, such as unpaved parking lots and

disturbed vacant lots. These efforts also support an

overall 80 percent rule effectiveness.

MAG plan assumes this level increases

from 66 percent in 1998 to 80 percent

in 2006. MAG TSD, Appendix IV,

Exhibit 1, Committed Measure 1. This

level of compliance depends in turn on

education of the regulated community

and increased enforcement modifying

source behavior. Both of these take time

to effect, therefore, we believe that it is

reasonable to allow a period of time to

achieve a high level of compliance with

these rules. We thus believe that the

emission reductions are being achieved

as expeditiously as practicable.

6. Other Factors That EPA may Consider

CAA section 188(e) list five additional

factors that we may consider in deciding

whether to grant an extension and the

length of that extension.

The MAG plan provides information

addressing each of the factors in Chapter

10 of the plan. We have already

proposed to determine that the MAG

plan provides for the implementation of

RACM and BACM, includes the MSM,

and attainment of the annual PM-10

standard by the earliest practicable date

of December 31, 2006. In the next

section, we will also propose to find

that the plan provides for reasonable

further progress. Nothing in the

additional information presented on the

five factors suggest that granting an

extension of the attainment date for the

Phoenix area to 2006 is inappropriate.

a. Nature and extent of

nonattainment. Over the past 5 years,

violations of the annual standard have

occurred routinely at three sites (MAG

plan, Table 10-11):

1. Greenwood, an urban site heavily

impacted by transportation sources,

2. Chandler, an urban fringe site

heavily impacted by fugitive dust

sources such as construction and

agriculture, and

3. Salt River, a site heavily impacted

by industrial sources.

Areas similar to the first two sites can

be found throughout the Phoenix

nonattainment area, so we would expect

that there are similarly elevated PM-10

levels throughout the Phoenix area;

therefore, controls need to be uniformly

implemented throughout the

nonattainment area, a task that generally

requires longer to achieve than

implementing controls in few localized

areas.

b. Types and numbers of sources or

other emitting activities. Primary

contributors to elevated PM-10 levels

are fugitive dust sources including

paved road dust, unpaved roads,

construction activities, disturbed vacant

lands, unpaved parking lots, and

agricultural sources. MAG plan, p. 10-

51. These sources are ubiquitous in the

nonattainment area and collectively

number in the thousands. (For example,

MCESD issued 2500 construction

permits in 1999; we mailed 50,000

letters to owners of vacant lots in the

nonattainment area; there are 12,000

miles of roadway in the nonattainment

area.)

c. Population exposure to

concentrations above the standard. The

MAG plan estimates population

exposure to elevated levels of PM-10

(both annual and 24-hr) to be from

78,000 to 163,000 (1995 figure), p. 10-

13. This population exposure is

calculated using estimates of disturbed

land versus population in subareas of

the nonattainment area. According to

this calculation, 84 percent of

Maricopa's population lives in areas

where 10 percent or less of the land is

open. MAG plan, Table 10-13. This

exposure number does not seem to

include populations exposed to dust

from paved and unpaved roads and

therefore may underestimate overall

population exposure. However, the plan

does provide for implementation of

RACM, BACM, and MSM on disturbed

land (including construction) and paved

and unpaved roads with much of the

emission reductions being achieved in

the first few years, all these factors will

reduce population exposure as quickly

as practicable.

d. Presence and concentration of

potentially toxic substances in the

particulate. The primary source of

airborne cancer risk in the Maricopa

area is internal combustion engine

exhaust from both on- and non-road

engines. This risk is from all pollutants

emitted from these sources (gaseous and

particulate). MAG plan, p. 10-61. The

MAG plan concludes that the cancer

risk in the Phoenix area is comparable

to that in California cities, p. 10-61. The

MAG plan and other Arizona programs

(e.g., cleaner burning gasoline, national

emission standards for non-road

engines) target emissions from on- and

non-road engines.

Almost all of the PM-10 emission

reductions in the out years of the MAG

plan (2003 and later) are and need to be

from fugitive dust sources in order to

show attainment of the annual PM-10

standard and not fron on- and non-road

engines; therefore, extending the

attainment date does not affect the

degree of public exposure to the major

source of toxic risk because shortening

the extension would not accelerate

controls on the major source of toxic

risk, on- and nonroad engines.

e. Technological and economic

feasibility of controls. Fugitive dust

sources dominate the emission

inventory in the Maricopa

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nonattainment area. Controls for these

sources are well known (paving, wetting

surfaces, etc.) and have been adopted;

however, the number of sources and

nature of sources make education and

outreach necessary to assure full

compliance with those controls. In

addition, costs for paving roads,

purchasing street sweepers, and other

capital improvements necessary to

reduce PM-10 emissions are high and

necessary funds are only available over

a number of years. These factors

generally support a longer time frame

for attainment.

7. Conclusion on Extension Request

Based on our review of the MAG plan

and our proposed determination that it

meets the requirements necessary for

granting an extension of the attainment

date under CAA section 188(e), we are

proposing to grant a five-year extension

of the serious attainment date for the

Phoenix PM-10 serious nonattainment

area from December 31, 2001 to

December 31, 2006.

H. Reasonable Further Progress (RFP)

and Quantitative Milestones

We propose to find that the MAG plan

provides for RFP and meets the

quantitative milestone requirements of

the Act.

1. Reasonable Further Progress

The MAG plan provides for annual

progress so that emissions levels in each

year from 1995 to 2006 that are at or

below the level needed to maintain

linear progress toward attainment. It

demonstrates that regional PM-10

emission levels will drop from 191

mtpd in 1995 to 130 mtpd in 2006 with

two-thirds of the reduction occurring

before 2001. MAG plan, Figure 8-4.

Total regional emissions decrease

annually at a rate of approximately 6.5

mtpd per year from 1995 through 2001

and 4.4 mtpd per year from 2002 to

2006. The assumptions that underlie the

RFP demonstration regarding control

measures' implementation and

effectiveness are reasonable.

The plan does not provide emission

reduction information for each year

between the base modeling year of 1995

and the attainment year of 2006. We do

not believe that this level of detail is

necessary or meaningful. The principal

control measures in the plan (such as

improving compliance with the fugitive

dust rules, progressive paving of

unpaved roads, and annual replacement

of part of the street sweeper fleet with

PM-10 efficient units) produce year to

year incremental increases in emission

reductions sufficient to meet the

statutory requirement for RFP. See MAG

plan, Figure 8-4 and EPA TSD, Figure

RFP-1. Therefore, we propose to find

that the MAG plan provides for "such

annual incremental reductions in

emissions of the relevant air pollutant as

are required by this part [part D of title

I] or may reasonably be required by the

Administrator for the purpose of

ensuring attainment of the applicable

national ambient air quality standard by

the applicable date" as required by

section 172(c)(2) of the Act.

2. Quantitative Milestones

Our guidance provides for a

quantitative milestone for the year 2000.

Addendum at 42016. Based on the

statutory requirement for milestones

every three years, the years 2003 and

2006 are the next two milestones for

areas with an attainment date extension

under section 188(e). The MAG plan

provides milestones for 2003 and 2006

but substitutes 2001 for 2000. We

believe this minor deviation from our

guidance is appropriate and acceptable

for the following reasons.

First, we set the milestone schedule in

our serious PM-10 area guidance

assuming the area involved was one of

the initial moderate areas and its

moderate area plan demonstrates

attainment by December 31, 1994.

General Preamble at 13539 and

Addendum at 42016. Although the

Phoenix area was one of the initial

moderate nonattainment areas, its

moderate area plan did not demonstrate

attainment. 33 As a result, our guidance

on the appropriate milestone years is

not strictly applicable to the MAG

serious area plan.

We also believe that the statutory

purpose for including milestones in

PM-10 plans is best served in the

Phoenix area by having the milestone

year be 2001 rather than 2000. Under

the Act, states are to submit a

demonstration 90 days after a milestone

date that the state has implemented all

measures in its approved plan and has

met the milestone. See CAA section

189(c)(2). If a state fails to submit a

report or we determine that the area has

not met a milestone, then the state must

submit a plan revision that assures that

the next milestone will be met. See CAA

section 189(c)(3).

It is clear from the statutory

requirements, that the milestone

requirement functions as a mid-course

33 The moderate area plan submitted by the State

in 1991 and revised in 1993 and 1994 demonstrated

the impracticability of attainment by December 31,

1994. While we have subsequently disapproved this

impracticability demonstration because the plan

did not include RACM, we confirmed that

attainment was impracticable in our 1998 FIP. 63

FR 41340.

evaluation of the PM-10 plan and an

opportunity to make corrections to the

plan to assure that there is no delay in

attainment due to failures to implement

or achieve needed reductions. As such,

the milestones should be keyed, to the

extent possible, to major

implementation deadlines in a manner

that allows for a realistic and

comprehensive look at the effectiveness

of the implemented measures.

The BACM implementation deadline

for Phoenix is June 10, 2000. A

December 31, 2000 milestone allows for

the evaluation of only a half-year of

implementation, which is little time to

see if implementation is going to

achieve the expected emission

reductions. Setting the milestone one

year later on December 31, 2001 as the

MAG plan does, provides for a full year

of implementation allowing for a more

realistic assessment of the effectiveness

of BACM yet still leaving ample time to

make any corrections needed to assure

timely attainment. Therefore, we believe

that strict adherence to the 2000

milestone date in our guidance would

be less beneficial to attainment in the

Phoenix area than setting the date at

2001.

The next milestone in the MAG plan

after the 2001 one is in 2003. MAG plan,

Figure 8-4. This second milestone is

only 2 years after the first, instead of 3

years arguably required by the Act.

However, we believe that the 3-year

milestone increment in CAA section

189(c) is the maximum allowable time

between milestones and nothing in the

section prohibits states from setting

milestones dates that are closer together.

The assumptions regarding control

measures' implementation and

effectiveness that underlie the

quantitative milestones are reasonable

and consistent with the RFP

demonstration.

For these reasons, we propose to find

that the MAG plan meets the

quantitative milestone requirement in

CAA section 189(c)(1).

L General SIP Requirements

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

Act requires that implementation plan

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 (section 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

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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.

We propose to find that the

implementing agencies for the MAG

plan have adequate resources for

implementing their respective

commitments. We also propose to find

that the MAG plan adequately describes

the resources that are available or will

be available to the State and local

agencies to carry out the Plan, both now

and over the next 5 years. See

discussion of the individual

commitments and control measures in

the TSD.

All agencies and jurisdictions appear

to have adequate authority under

Arizona state law to implement their

respected commitments and, where

applicable, to obtain information

necessary to determine compliance. We,

therefore, propose to find that these

agencies/jurisdictions have

demonstrated that they have adequate

legal authority to implement the MAG

plan.

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.

The principle control measures in the

plan are MCESD's Rules 310 and 310.01.

Procedures for monitoring compliance

(i.e., the inspection strategy) with these

rules are described in Maricopa

County's commitments. See Maricopa

County commitment, 1999 Revised

Measure 6.

Based on the review of MCESD's

enforcement procedures, we propose to

find that the MAG plan adequately

provides for the enforcement of the

principle measures relied on for

attainment and that the plan includes an

adequate description of enforcement

methods as required by our regulations.

Section 110(a)(2)(E)(iii) requires SIPs

to include necessary assurances that

where a State has relied on a local or

regional government, agency or

instrumentality for the implementation

of any plan provision, the State has

responsibility for ensuring adequate

implementation of the such plan

provision.

We have previously found that

Arizona law includes the necessary

assurances that where a State has relied

on a local or regional government,

agency or instrumentality for the

implementation of any plan provision,

the State has responsibility for ensuring

adequate implementation of the such

plan provision. 60 FR 18010, 18019

(April 10, 1995).

Proposed Actions on Maricopa County

Rules

A. Rule 310

Rule 310 establishes requirements for

fugitive dust sources on facilities that

have or are required to have air quality

permits from MCESD. These facilities

include construction sites, stationary

sources, and any other facility or

operation that is required to have a

permit under MCESD rules. The rule

requires earthmoving activities that

disturb 0.10 acre or more to apply for

and get approval of a Dust Control Plan

(DCP) and requires other permitted

sources to obtain a DCP prior to

commencing any routine dust

generating activity. We have described

many of the Rule's specific

requirements earlier in this preamble.

The current SIP approved version of

Rule 310 is the version adopted on

September 9, 1994. We approved this

version of Rule 310 into the SIP on

August 4, 1997 as part of the Microscale

plan. 62 FR 41856

MCESD adopted a revised version of

Rule 310 and Appendix C to MCESD

rules on February 16, 2000 and Arizona

submitted both as a revision to the

Arizona SIP on March 2, 2000.

Appendix C contains the test methods

relied on in Rule 310.

The revised Rule 310 is considerably

different from the current SIP-approved

version. The greatest change has been to

split the old rule into two new rules: the

revised Rule 310 that addresses

permitted facilities and a new Rule

310.01 that addresses nonpermitted

sources. We evaluate Rule 310.01 in the

next section. MCESD also revised Rule

310 to strengthen it compared to the

current SIP-approved version. These

rule improvements include:

* Improved enforceability of control

measures and dust control permits

(DCPs),

* Improvements to existing test

methods (in Appendix C),

* New performance standards and

test methods,

* Clearer definitions,

* More specific work practice

requirements

MCESD has also committed to

continue to strengthen and improve

Rule 310 through research on test

methods, dust control methods, and

revised recordkeeping requirements. See

discussion in section F.3.g.,

"Construction Sites and Activities."

We believe that the revised Rule 310

is a considerable improvement over the

SIP-approved version and, combined

with MCESD commitments to continue

to improve the Rule and to improve

enforcement and compliance with it,

provides for implementation of RACM

and BACM and the inclusion of the

MSM on the sources subject to it. We,

therefore, propose to approve Rule 310

and Appendix C as adopted on February

16, 2000 and submitted on March 2,

2000, into the Arizona SIP.

We have described in more detail the

improvements and other revisions to

Rule 310 in section 6 of our TSD.

B. Rule 310.01

Rule 310.01 establishes requirements

for fugitive dust emitted from

nonpermitted sources, including

unpaved public roads, unpaved parking

lots, open areas and vacant lots, erosioncaused deposits of bulk materials onto

paved surfaces, and commercial feedlots

and/or commercial livestock areas.

The provision of Rule 310.01 are

currently in the SIP as sections of

former Rule 310. We approved this

version of Rule 310 into the SIP on

August 4, 1997 as part of the microscale

plan. 62 FR 41856.

MCESD adopted Rule 310.01 on

February 16, 2000 and Arizona

submitted it as a revision to the Arizona

SIP on March 2, 2000. As with Rule 310,

Rule 310.01 relies on the test methods

in Appendix C.

Rule 310.01's provisions are

strengthened compared to the similar

provisions in the SIP. These rule

improvements and other rule changes

include:

* The revised rule requires that

unpaved roads and unpaved parking

lots comply with both: (1) a 20 percent

opacity standard; and (2) a silt content

or a silt loading standard.

* A new opacity test method has been

added to Appendix C to determine

compliance with the rule's 20 percent

opacity standard for unpaved haul/

access roads and unpaved parking lots

which is better tailored to these sources.

* Test methods for determining

compliance with the new silt content/

loading standards has been added to

Appendix C.

* Owners/operators of disturbed

vacant lots and open areas must

maintain a visible crust or meet at least

one other applicable stabilization

standard, according to new test methods

included in the rule and Appendix C.

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* Specific control measures for

commercial feedlots and/or commercial

livestock areas have been added,

including: application of dust

suppressants or gravel, or installation of

shrubs and/or trees within 50 to 100 feet

of animal pens.

* The revised rule specifies that

unpaved roads with vehicular traffic of

250 or more must be stabilized by June

10, 2000 and unpaved roads with

vehicular traffic of 150 or more must be

stabilized by June 10, 2004.

* The revised rule specifies that

requirements to prevent vehicle

trespassing (section 301) apply to vacant

lots and open areas that are 0.10 acre or

larger and have a cumulative of 500

square feet or more that are driven over

and/or used by motor vehicles and/or

off-road vehicles.

* The revised rule specifies that

requirements to stabilize disturbed

vacant lots and open areas (section 302)

apply to lots/areas with 0.5 acre or more

of disturbed surface.

We believe that Rule 310.01 is a

considerable improvement over the SIPapproved version and, combined with

MCESD's commitments to continue to

improve the Rule and enforcement and

compliance with it and the

commitments by the County and local

jurisdictions to address unpaved roads,

unpaved parking lots, and vacant lots,

provides for implementation of RACM

and BACM and the inclusion of the

MSM on the sources subject to it. We,

therefore, propose to approve Rule

310.01 as adopted on February 16, 2000

and submitted on March 2, 2000, into

the Arizona SIP.

We have described in more detail the

strengthenings and other revisions to

Rule 310.01 in section 6 of our TSD.

C. Residential Woodburning Restriction

Ordinance

Combined with MCESD Rule 318

"Approval of Residential Woodburning

Devices" (adopted April 21, 1999;

approved November 8, 1999 (64 FR

60678)), Maricopa County's Residential

Woodburning Restriction Ordinance

implements a mandatory woodburning

curtailment program. The curtailment

program restricts the types of

woodburning devices that can be used

during periods of high PM-10

concentrations. The ordinance allows

the Control Officer to declare restrictedburn periods when the particulate

matter pollution levels could exceed the

"particulate matter no-burn standard."

The SIP-approved ordinance provides

that restricted-burn periods are declared

by the Control Officer when the Control

Officer determines that air pollution

levels could exceed the 24-hour PM

standard at 150 gLg/m 3. The revised

ordinance allows the Control Officer to

declare restricted-burn periods when

the particulate matter pollution levels

could exceed the "particulate matter noburn standard" of 120 gg/m 3. The lower

of the particulate matter no burn

standard to 120 gLg/m 3 is the only

change made to the ordinance as it is

currently approved in the SIP.

Because approving this revision will

strengthen the SIP and when combined

with the MAG plan's other provision for

residential woodburning will provide

for the implementation of BACM and

the inclusion of the MSM, we are

proposing to approve it into the SIP. See

section F.3.j. "Residential Wood

Combustion."

D. CAA Section 110(1) Finding

CAA section 110(1) prohibits us from

approving a revision to the applicable

implementation plan if that revision

would interfere with any applicable

requirement concerning attainment and

reasonable further progress (RFP) or any

other applicable requirement of the Act.

We interpret section 110(1) to mean that

we cannot approve a plan revision if

that revision would mean that the plan

would no longer provide for attainment

or RFP as these are required by the CAA

for that plan or if the revision would

mean that the plan would no longer

meet another requirement of the Act

that applies to the plan. For a further

discussion of this interpretation, see 61

FR 51599, 51608 (October 3, 1996).

We are proposing to revise the

Arizona SIP to incorporate the revised

Rule 310, Rule 310.01 and the Maricopa

County Residential Woodburning

Ordinance in replacement of the

previous version of Rule 310 approved

in August, 1997 and of the ordinance

approved in November, 1999. In

addition to the effect on attainment and

RFP, the "other applicable requirement

of the Act" that we must be concerned

with for this proposal is the Act's

requirements for implementation of

RACM and BACM and the inclusion of

the MSM.

We are proposing to approve the

expeditious attainment and RFP

demonstrations in the MAG plan. These

demonstrations are in part dependent

on approval of the revised Rule 310,

Rule 310.01, and the woodburning

ordinance.

We are also proposing to find that the

MAG plan provides for the

implementation of RACM and BACM

and the inclusion of the MSM for

construction sites, unpaved roads,

unpaved parking lots, and disturbed

vacant lands. Again, these findings are

in large part dependent on approval of

the revised Rule 310 and Rule 310.01.

We, therefore, propose to find that

approval of the revised Rule 310 and

Rule 310.01 will not interfere with

plan's compliance with the Clean Air

Act's requirements for attainment, RFP,

implementation of RACM and BACM,

and inclusion of the MSM as they apply

to construction sites, unpaved roads,

unpaved parking lots, and disturbed

vacant lands.

Finally, we are proposing to find that

the MAG plan provides for the

implementation of BACM and for the

inclusion of MSM for residential

woodburning. These proposed findings

are made in part based on the revised

ordinance. Therefore, we propose to

find that our approving the ordinance

will not interfere with the plan's

compliance with the Act's requirements

for the implementation of BACM and

the inclusion of MSM as they apply to

residential woodburning.

We have previously found that the

Arizona SIP provided for the

implementation of RACM for residential

woodburning. 64 FR 60678 (November

8, 1999). The State has now

strengthened its residential

woodburning program, in part with the

revised ordinance; therefore, we

propose that approval of the revised

ordinance will not interfere with the

Arizona SIP's compliance with the

requirement for the implementation of

RACM as it applies to residential

woodburning.

Administrative Requirements

Under Executive Order 12866 (58 FR

51735, October 4, 1993), this proposed

action is not a "significant regulatory

action" and therefore is not subject to

review by the Office of Management and

Budget. This proposed action merely

approves state law as meeting federal

requirements and imposes no additional

requirements beyond those imposed by

state law. Accordingly, the

Administrator certifies that this

proposed rule will not have a significant

economic impact on a substantial

number of small entities under the

Regulatory Flexibility Act (5 U.S.C. 601

et seq.).

Because this rule proposes to approve

pre-existing requirements under state

law and does not impose any additional

enforceable duty beyond that required

by state law, it does not contain any

unfunded mandate or significantly or

uniquely affect small governments, as

described in the Unfunded Mandates

Reform Act of 1995 (Pub. L. 104-4).

For the same reason, this proposed

rule also does not significantly or

uniquely affect the communities of

tribal governments, as specified by

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Executive Order 13084 (63 FR 27655,

May 10, 1998). This proposed rule will

not have substantial direct effects on the

States, on the relationship between the

national government and the States, or

on the distribution of power and

responsibilities among the various

levels of government, as specified in

Executive Order 13132 (64 FR 43255,

August 10, 1999), because it merely

approves a state rule implementing a

federal standard, and does not alter the

relationship or the distribution of power

and responsibilities established in the

Clean Air Act.

This proposed rule also is not subject

to Executive Order 13045 (62 FR 19885,

April 23, 1997), because it is not

economically significant.

In reviewing SIP submissions, our

role is to approve state choices,

provided that they meet the criteria of

the Clean Air Act. In this context, in the

absence of a prior existing requirement

for the State to use voluntary consensus

standards (VCS), we have no authority

to disapprove a SIP submission for

failure to use VCS. It would thus be

inconsistent with applicable law for us,

when reviewing a SIP submission, to

use VCS in place of a SIP submission

that otherwise satisfies the provisions of

the Clean Air Act. Thus, the

requirements of section 12(d) of the

National Technology Transfer and

Advancement Act of 1995 (15 U.S.C.

272) do not apply.

As required by section 3 of Executive

Order 12988 (61 FR 4729, February 7,

1996), in issuing this proposed rule, we

have taken the necessary steps to

eliminate drafting errors and ambiguity,

minimize potential litigation, and

provide a clear legal standard for

affected conduct.

We have complied with Executive

Order 12630 (53 FR 8859, March 15,

1988) by examining the takings

implications of the rule in accordance

with the "Attorney General's

Supplemental Guidelines for the

Evaluation of Risk and Avoidance of

Unanticipated Takings" issued under

the executive order.

This proposed rule does not impose

an information collection burden under

the provisions of the Paperwork

Reduction Act of 1995 (44 U.S.C. 3501

et seq.).

List of Subjects in 40 CFR Part 52

Environmental protection, Air

pollution control, Intergovernmental

relations, Particulate matter, Reporting

and recordkeeping requirements.

Authority: 42 U.S.C. 7401 et seq.

Dated: April 3, 2000.

Laura Yoshii,

Acting Regional Administrator, Region IX.

[FR Doc. 00-8833 Filed 4-12-00; 8:45 am]

BILLING CODE 6560-50-U

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