Federal Register/Vol. 66, No. 191/Tuesday, October 2, 2001/Proposed Rules

ENVIRONMENTAL PROTECTION

AGENCY

40 CFR Part 52

[AZ092-002; FRL-7067-5]

Approval and Promulgation of

Implementation Plans; ArizonaMaricopa County PM-10

Nonattainment Area; Serious Area Plan

for Attainment of the 24-Hour PM-10

Standard and Contingency Measures

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-1 0

for the Maricopa County (Phoenix)

Nonattainment Area, February 2000,

including the revisions submitted in

June 2001 that address attainment of the

24-hour 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

24-hour PM-10 standard in the Phoenix

area from 2001 to 2006. Finally, we

propose to find that the plan provides

for the implementation of contingency

measures for both the 24-hour and

annual PM-10 standards and to make

several revisions to our previous

proposal on the MAG plan's provisions

for the annual standard and our

proposed policy on attainment date

extensions for serious PM-10

nonattainment areas.

DATES: Comments on this proposal must

be received in writing by November 1,

2001. Comments should be addressed to

the contact listed below.

ADDRESSES: Comments should 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 EPA technical

support document (EPA TSD) and other

material relevant to this 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/region 09/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)

744-1248, email:

wicher.frances@epa.gov.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Summary of Today's Proposals

II. Background to Today's Proposals

A. PM-10 Air Quality in the Phoenix Area

B. Description of the MAG Plan's

Provisions for Attaining the 24-Hour

PM-10 Standard

C. Previous Actions on the Phoenix Serious

Area PM-10 Plan

1. Annual Standard Proposal

2. Microscale Plan Partial Approval/Partial

Disapproval

3. Arizona's Agricultural BMP General

Permit Rule Approval

III. The CAA's Planning Requirements for

Serious PM-10 Nonattainment Areas

IV. The MAG Plan's Compliance with the

CAA's Requirements for Serious PM-10

Nonattainment Areas

A. Completeness of the SIP Submittals

B. Adequacy of the Transportation

Conformity Budget

C. Emissions 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. Steps 1 and 2: Determination of

significant sources

2. Step 3: Identification of potential BACM

3. Step 4: 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 and

Quantitative Milestones

1. Reasonable further progress

2. Quantitative milestones

I. Contingency Measures

J. General SIP Requirements

V. CAA Requirements for BACM and

Attainment Date Extension and EPA's

Guidance on Meeting these

Requirements

A. Implementation of Best Available

Control Measures

B. 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

VI. Administrative Requirements

I. Summary of Today's Proposals

First, we propose to approve the

provisions in the Revised MAG 1999

Serious Area Particulate Plan for PM-I 0

for the Maricopa County Nonattainment

Area, February 2000, ("MAG plan")

including revisions to that plan

submitted in Maricopa County PM-I 0

Serious Area State Implementation Plan

Revision, Agricultural Best Management

Practices, June 2001, (collectively, "the

Maricopa County serious area plan" or

"the plan") that address attainment of

the 24-hour PM-10 standard.' Our

proposed actions are based on our

initial determination that the Maricopa

County serious area plan complies with

the Clean Air Act's (CAA) requirements

for serious PM-10 nonattainment area

plans.

Specifically, we propose to approve

the following elements of the plan as

they pertain to the 24-hour standard:

* The demonstration that the plan

provides for implementation of

reasonably available control measures

(RACM) and best available control

measures (BACM),

1 There are two separate national ambient air

quality standards for PM-10, an annual standardd

of 50 pg/m 3 and a 24-hour standard of 150 ig/m3.

We proposed approval of the MAG plan's annual

standard provisions on April 13, 2000 at 65 FR

19964.

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* The demonstration that attainment

by the CAA deadline of December 31,

2001 is impracticable,

* The demonstration that attainment

will occur by the most expeditious

alternative date practicable, in this case,

December 31, 2006,

* The demonstration that the plan

provides for reasonable further progress

and quantitative milestones,

* The demonstration that major

sources of PM-10 precursors such as

nitrogen oxides and sulfur dioxide do

not contribute significantly to air quality

standard violations, and

* The transportation conformity

budget.

Second, we are proposing to grant

Arizona's request to extend the

attainment date for the 24-hour PM-10

standard from December 31, 2001 to

December 31, 2006. We make this

proposal based on our determination

that the State has met the CAA's criteria

for granting such extensions.

Third, we propose to find that the

plan provides for the implementation of

contingency measures for both the 24-

hour and annual standards as required

by the CAA.

Finally, we make several revisions to

our April 13, 2000 proposed approval of

the annual standard provisions in the

Maricopa County serious area plan.

These revisions involve:

* Clarifications to our proposed

policy on granting attainment date

extensions under CAA section 188(e),

* Changes to Maricopa County

Environmental Services Department's

(MCESD) commitments to further

improve its fugitive dust rule, Rule 310,

* Changes to several other control

measures, and

* Evaluation of the plan's compliance

with the BACM requirement and most

stringent measure requirement in CAA

section 188(e) for the agriculture source

category based on the State's

Agricultural Best Management Practices

General Permit Rule.2

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 that accompanies

this proposal. See "Technical Support

Document, Notice of Proposed

Rulemaking on the Serious Area PM-10

State Implementation Plan for the

Maricopa County PM-10 Nonattainment

Area Provisions for Attaining the 24-

Hour Standard and Contingency

Measures," September 14, 2001 (EPA

2

Except for these limited number of revisions, we

are not reopening the comment period and are not

soliciting comments on our April 13, 2000 proposal.

TSD). The EPA TSD is an integral part

of this proposal and should be reviewed

prior to making comments. A copy of

the EPA TSD can be downloaded from

our website or obtained by calling or

writing the contact person listed above.

II. Background to Today's Proposals

A. PM-1 0 Air Quality in the Phoenix

Area

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. 3 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 and required to

submit a serious area plan by December

10, 1997. 61 FR 21372 (May 10, 1996).

The principal contributors to elevated

PM-10 levels in the Phoenix area are

fugitive dust sources such as

construction sites, unpaved roads,

vacant lots, agricultural sources, and

paved road dust. Also contributing to

the PM-10 problem, but to a much

lesser degree than fugitive dust, are

internal and external combustion

sources including directly-emitted PM10 from automobiles, trucks,

construction equipment, buses,

residential woodburning and industrial,

commercial, and residential use of

natural gas and fuel oil. See MAG plan,

p. 3-5.

There is a long and complex history

to PM-10 air quality planning in the

Phoenix area. A summary of this history

can be found in the annual standard

proposal at 65 FR 19964, 19965. A more

detailed history can be found in section

1 of the EPA TSD.

B. Description of the MAG Plan's

Provisions for Attaining the 24-Hour

PM-JO Standard

Arizona has made several submittals

to address the CAA requirements for

serious PM-10 nonattainment area

plans for the Phoenix area. The

provisions for attainming the 24-hour

PM-10 standard are found mainly in

three of these submittals: the 1997

3 The Maaricopa 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.

Microscale plan,4 the 2000 MAG plan,

and the 2001 Best Management

Practices (BMP) submittal.5 The latter

two documents are the subject of this

proposal and are described in more

detail below. We have already acted on

the Microscale plan, see 62 FR 41856

(August 4, 1997). We describe this plan

and explain its relationship to today's

proposal in the next section.

The first submittal is the Revised

Maricopa Association of Governments

1999 Serious Area Particulate Plan for

PM-1 0 for the Maricopa County

Nonattainment Area, February 2000.

This plan was developed by the

Maricopa Association of Governments

(MAG), the lead air quality planning

agency in Maricopa County. The

Arizona Department of Environmental

Quality (ADEQ) submitted this plan as

a revision to the Arizona State

Implementation Plan (SIP) on February

16, 2000. We refer to this plan in this

document as the MAG plan or the

revised MAG plan; however, we

occasionally use these terms to refer to

the set of documents that collectively

comprise the Maricopa County serious

area PM-10 plan.

The second document is the Maricopa

County PM-IO Serious Area State

Implementation Plan Revision,

Agricultural Best Management

Practices, (BMP) June 2001, submitted

in draft on April 26, 2001 and final on

June 13, 2001. This SIP revision was

developed by ADEQ. We refer to this

submittal as the BMP TSD.

The MAG plan contains a 1994

inventory and uses the urban airshed

model/limited chemistry version (UAM/

LC) to model regional air quality in 1995

as a base year and in 2006 as the

attainment year for both the annual and

24-hour standards. The MAG plan,

however, relies primarily on air quality

modeling performed in the Microscale

plan to evaluate localized 24-hour

exceedances.

The MAG plan, as revised by the BMP

TSD, includes a BACM analysis and a

demonstration that attainment by 2001

is impracticable for both the 24-hour

and annual PM-10 standards. It also

4 The 1997 Microscale plan is the Plan for

Attainment of the 24-hour PM-10 StandardMaricopa County PM-10 Nonattainment Area,

Arizona Department of Environmental Quality,

May, 1997.

5 The other submittals contain rules and other

control measures relied on to provide for RACM,

BACM, reasonable further progress an attainment.

These submittals include the commitments by local

jurisdictions to PM-10 control measures submitted

in December 1997, revised MCESD Rules 310 and

310.01 submitted in March 2000, Maricopa

County's Residential Wood Burning Ordinance

submitted in January 2000, and the Agricultural

Best Management Practices (BMP) General Permit

Rule submitted in July 2000.

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includes, again for both PM-10

standards, the State's request for a fiveyear extension of the attainment date, a

demonstration that the plan includes for

the most stringent measures found in

other states' plans, and a demonstration

of attainment by December 31, 2006.

The BMP TSD updates the MAG plan

to reflect the State's adoption of the

Agricultural General Permit rule to

control PM-10 from agricultural sources

in Maricopa County. It includes a

background document which provides

the BACM demonstration for

agricultural sources for both standards,

a revised demonstration of attainment

and reasonable further progress (RFP)

for the 24-hour standard at two

monitoring sites, and revisions to the

contingency measure provisions for

both standards. It also includes

documentation quantifying emission

reductions from the Agricultural

General Permit rule and documentation

related to implementing this rule.

C. Previous Actions on the Phoenix

Serious Area PM-IO Plan

We have taken three actions related to

the Phoenix Serious Area PM-10 plan:

the proposed approval of the MAG

plan's provisions for the annual

standard, the partial approval/ partial

disapproval of the 1997 Microscale

plan, and the approval of Arizona's

Agricultural BMP General Permit rule.

With today's proposal, we have now

proposed action on all elements of the

Maricopa County serious area PM-10

plan.

1. Annual Standard Proposal

On April 13, 2000, we proposed to

approve the MAG plan's provisions for

attainment of the annual PM-10

standard. See 65 FR 19964.6

Specifically, we proposed to approve for

the annual standard the provisions for

implementation of RACM and BACM,

the demonstration that attainment by

2001 is impracticable, the

demonstration that attainment will

occur by the most expeditious

alternative date, the RFP demonstration,

the quantitative milestones, and the

conformity budget. We also proposed to

grant an extension of the attainment

date from 2001 to 2006 based on our

proposed determination that Arizona

6 In the annual standard propsoal and in the EPA

TSD for today's proposal, we discuss the legal basis

for separating the proposed approvals for the 24-

hour and annual standards and the practical

reasons we chose to do so. See 65 FR 19964, 19969

and section 3 of the EPA TSD. We intent, however,

to finalize actions on both standards in a single

rulemaking in early 2002.

had met the CAA criteria for granting

such an extension.

In April 2000 preamble, we also

proposed to approve the base year

regional emissions inventory required

by CAA section 172(c)(3), MCESD's

Rules 310 and 310.01, Maricopa

County's Residential Woodburning

Ordinance, and the commitments by the

cities, towns, and County of Maricopa,

ADEQ, MAG, and other State and local

agencies to implement various PM-10

control measures. These proposals were

applicable to both the annual and 24-

hour PM-10 standards and thus are not

being repeated today.

2. Microscale Plan Partial Approval/

Partial Disapproval

The attainment demonstration for the

24-hour standard in the Maricopa

County serious area plan has both a

local modeling component and a

regional modeling component. Portions

of the local or microscale component are

found in the Microscale plan, the 2000

MAG plan, and the BMP TSD. The

regional component is contained

completely within the 2000 MAG plan.

Most of the technical evaluation for

the microscale component is contained

in the Microscale plan which was

submitted to us in May 1997. It

evaluates exceedances of the 24-hour

PM-10 standard at four Phoenix area

monitoring sites: Salt River, Maryvale,

Gilbert, and West Chandler.

This evaluation involved developing

local, day-specific inventories and

dispersion modeling to determine

source contributions to exceedances at

each site. The evaluation showed that

the primary contributors to 24-hour

exceedances in the Phoenix area are

local fugitive dust sources such as

construction sites, agricultural fields

and aprons, vacant lots, unpaved roads

and parking lots, and earthmoving

operations. The Microscale plan also

described the type of controls necessary

to show attainment at each site although

the plan only assured the

implementation of such controls on

construction-related sources.

We approved the Microscale plan in

part and disapproved it in part on

August 4, 1997 (62 FR 41856). We

approved the attainment and RFP

demonstrations for the Salt River and

Maryvale sites because the plan

demonstrated expeditious attainment at

these sites; however, we disapproved

these demonstrations for the West

Chandler and Gilbert sites because the

plan did not demonstrate attainment at

them. Because attainment

demonstrations at the Salt River and

Maryvale sites were already approved,

ADEQ limited its subsequent microscale

work to developing approvable

demonstrations for the Gilbert and West

Chandler sites. Our proposal today is

also limited to these two sites.

To evaluate the provisions for the 24-

hour PM-10 standard in the MAG plan,

we are relying to a large extent on our

previous evaluation of the Microscale

plan. Except for the findings related to

the implementation of BACM, we have

not reevaluated the 24-hour standard

provisions that we have already found

adequate or approved as part of our

actions on the Microscale plan.

More information on the Microscale

plan can be found in section 1 of the

EPA TSD and our proposed and final

rulemakings on it. 62 FR 31025 (June 6,

1997) and 62 FR 41856 (August 4, 1997).

3. Arizona's Agricultural BMP General

Permit Rule Approval

The analysis done for the Microscale

plan revealed for the first time how

significant a contribution agricultural

sources make to exceedances of the 24-

hour PM-10 standard in the Phoenix

area. See Microscale plan, pp. 18-19. In

order to develop adequate controls for

this source, Arizona passed legislation

in 1997 establishing an Agricultural

Best Management Practices (BMP)

Committee and directing the Committee

to adopt by rule by June 10, 2000, an

agricultural general permit specifying

best management practices for reducing

PM-10 from agricultural activities. The

legislation also required that

implementation of the agricultural

controls begin by June 10, 2000 with an

education program and full compliance

with the rule be achieved by December

31, 2001. See Arizona Revised Statutes

(A.R.S.) 49-457.

In September 1998, the State

submitted the legislation. On June 29,

1999, we approved it as meeting the

RACM requirements of the CAA. 7 64 FR

34726.

While we approved the legislation as

RACM, it was the State's intent that it

also serve as BACM and MSM for

agricultural sources in the serious area

7 In 1998, we promulgated a moderate area PM10 federal implementation plan (FIP) for the

Phoenix area. 63 FR 41326 (August 3, 1998). One

of the measures in this FIP was our commitment to

adopt RCM for agricultural sources, RACM being

the primary control requirement for moderate PM10 nonattainment areas. Arizona submitted the

BMP legislation in 1998 as, among other things, a

substitute for our FIP RACM commitment. Before

we could withdraw our FIP RACM commitment

and replace it with the State's legislation, we had

to first find that the legislation was at least RACM,

hence our initial determination that it was at least

RCM. For further information on this legislation

and its relationship to the history of PM-10

planning in the Phoenix area, see the

"Implementation of BACM and Inclusion of MSM

for Agricultural Sources" section in the EPA TSD.

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PM-10 plan. Therefore, in our annual

standard proposal, we evaluated and

proposed to find that the legislation met

the CAA BACM and MSM requirements

for the agricultural source category. 65

FR 19964, 19981.

After a series of meetings during 1999

and 2000, the Agricultural BMP

Committee adopted the agricultural

general permit rule and associated

definitions, effective May 12, 2000, at

Arizona Administrative Code (AAC)

R18-2-610, "Definitions for R18-2-

611," and 611, "Agricultural PM-10

General Permit; Maricopa PM10

Nonattainment Area" (collectively,

general permit rule). The State

submitted the general permit rule in

July 2000 and its analysis quantifying

the emission reductions expected from

the rule and the demonstration that the

rule meets the CAA's RACM, BACM and

MSM requirements in the June 2001

BMP TSD. We proposed to approve the

rule as meeting the CAA requirement for

RACM on June 29, 2001 and signed the

final approval on September 10, 2001.

See 66 FR 34598.

We are today withdrawing our

proposed finding in the annual standard

proposal that the State legislation

provides for the implementation of

BACM and MSM for agricultural

sources for the annual standard. 66 FR

19964, 19981. In its place we are

proposing to find that the General

Permit rule provides for the

implementation of BACM and MSM for

agricultural sources for the annual

standard. This proposal is based on our

analysis, summarized later, of the rule

and the State's demonstrations in the

BMP TSD and is in addition to our

proposed finding that the rule provides

for the implementation of BACM and

MSM for the 24-hour standard.

III. The CAA's Planning Requirements

for Serious PM-10 Nonattainment

Areas

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 the BACM,

including best available control

technology (BACT) for stationary

sources, 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)); 8

(b) assurances that 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 and

that the plan provides for attainment by

the most expeditious alternative date

practicable (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

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 section

172(c)(3)).

Serious area plan must also provide

for the implementation of contingency

measures if the area fails to make RFP

or attain by its attainment deadline.

These contingency measures are to take

effect without further action by the State

or the Administrator. CAA section

172(c)(9).

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.

We have issued a General Preamble 9

and Addendum to the General

Preamble-o describing our preliminary

8 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.

9 "State Implementation Plans; General Preamble

for the Implementation of Title I of the Clean Air

Act Amendments of 1990," 57 FR 13498 (April 16,

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

10 "State Implementation Plans for Serious PM10 Nonattainment Areas, and Attainment Date

views on how the Agency intends to

review SIPs submitted to meet the

CAA's requirements for PM-10 plans.

The General Preamble mainly addresses

the requirements for moderate areas and

the Addendum, the requirements for

serious areas.

IV. The MAG Plan's Compliance with

the CAA's Requirements for Serious

PM-10 Nonattainment Area

The following sections present a

condensed discussion of our evaluation

of the MAG plan's compliance with the

applicable CAA requirements for

attaining the 24-hour PM-10 standard.

Our complete evaluation is found in the

EPA TSD for this proposal. We strongly

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

CAA section 110(k)(1)(B) requires us

to determine if a SIP submittal is

complete within 60 days of its receipt.

This completeness review allows us to

quickly determine if the submittal

includes all the necessary items and

information we need to take action on

it. We make completeness

determinations using criteria we have

established in 40 CFR part 51, appendix

V.

We found ADEQ's February 16, 2000

submittal of the final revised MAG

serious area PM-10 plan complete on

February 25, 2000. See letter, David P.

Howekamp, EPA, to Jacqueline Schafer,

ADEQ.

We also found ADEQ's June 13, 2001

submittal of the BMP TSD complete on

August 10, 2001. See letter, Jack

Broadbent, EPA, to Jacqueline Schafer,

ADEQ.

B. Adequacy of the Transportation

Conformity Budgets

CAA Section 176(c) 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

Waivers for PM-10 Nonattainment Areas, and

Attainment Date Waivers for PM-10 Nonattainment

Areas Generally; Addendum to the General

Preamble for the Implementation of Title I of the

Clean Air Act Amendments of 1990," 59 FR 41998

(August 16, 1994)

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whether or not transportation plans,

programs, and projects conform to a SIP.

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 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 can 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). A finding of adequacy

does not approve an emissions budget,

it simply allows states to begin to use

the budget in conformity determinations

pending our action on the overall SIP.

The MAG plan establishes a mobile

source emissions budget of 59.7 mtpd.

This regional budget is applicable to

both the annual and 24-hour PM-10

standards. The on-road mobile source

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 dust portion of the budget

is 1.1 mtpd. MAG plan, p. 8-13.

On March 30, 2000, we found

adequate for transportation conformity

purposes this motor vehicle emissions

budget. Our adequacy finding is

documented in section II of the EPA

TSD for the annual standard. As a result

of our adequacy finding, MAG and the

Federal Highway Administration are

now required to use this budget in all

conformity analyses.

As discussed later in this preamble,

we are proposing to approve both the

attainment and reasonable further

progress demonstrations for the 24-hour

standard in the Maricopa County

serious area PM-10 plan. The 59.7 mtpd

budget is consistent with these

demonstrations. We, therefore, propose

to approve it as the motor vehicle

emissions budget for the 24-hour PM-10

standard under CAA section 176(c).

C. Emissions Inventory

CAA section 172(c)(3) requires that

nonattainment area plans include a

comprehensive, accurate, and current

inventory of actual emissions from all

sources in the nonattainment area. To

meet this requirement Arizona

submitted a 1994 base year inventory as

part of the MAG plan. See MAG plan,

Appendix A, Exhibit 6. We proposed to

approve this inventory as meeting the

requirements of section 172(c)(3) in our

proposal on the annual standard

provisions. See 65 FR 19964, 19970.

In the Phoenix nonattainment area,

both regional and microscale modeling

inventories are needed to accurately

reflect the sources that are contributing

to 24-hour PM-10 ambient levels. The

regional modeling inventories were

derived from the 1994 base year

inventory and are the same for the

annual and 24-hour standards. We

proposed to find these regional

modeling inventories to be acceptable as

part of annual standard provisions. See

65 FR 19964, 19985-19986.

ADEQ developed microscale and

subregional inventories for 1995 (the

modeling base year) for the West

Chandler and Gilbert microscale sites.

See Microscale plan, Appendix A,

Chapter 4 and MAG plan, Appendix C,

Exhibit 3, Chapter 3. In the 1997

Microscale plan, ADEQ also developed

1995 inventories for the two other

microscale sites, Maryvale and Salt

River. See Microscale plan, Appendix

A, Chapters 4 and 6. We evaluated the

1995 inventories for all four sites as part

of our action on the overall Microscale

plan. See 62 FR 31025, 31030 (June 6,

1997). These microscale inventories are

specialized modeling inventory and is

not intended to satisfy the CAA section

172(c)(3) requirement."

We discuss emissions inventories in

this preamble and in the EPA TSD in

order to present a complete technical

review of the Maricopa County serious

area plan's provisions for attainment of

the 24-hour standard. Emissions

inventories play a fundamental role in

air quality modeling, and CAA section

189(b)(1)(A) requires attainment

demonstrations in PM-10 serious area

plan to be based on modeling. We

cannot find this modeling, or the

attainment demonstrations that are

derived from it, approvable without first

finding that the underlying emissions

inventories are adequate. We are not,

however, proposing any actions today

on the inventories relied on in the

Maricopa County serious area plan for

demonstrating attainment of the 24-hour

standard because, as discussed above,

we have already either proposed to

approve them or found them to be

acceptable.

11 The microscale inventories include only

sources within a small area surrounding each

monitor rather than all sources within the entire

nonattainment area as requirement in CAA section

172(c)(3).

D. Adequate Monitoring Network

We discuss the adequacy of the

monitoring network in this preamble

solely to support our finding that the

plan appropriately evaluates the PM-10

problem in the Phoenix area. Reliable

ambient data is necessary to validate the

base year air quality modeling which in

turn is necessary to assure sound

attainment demonstrations.

The CAA requires states to establish

and operate air monitoring networks to

compile data on ambient air quality for

all criteria pollutants. Section

110(a)(2)(B)(i). Our regulations in 40

CFR 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).

Ambient networks, however, do not

need to meet all our regulations to be

found adequate to support air quality

modeling. A good spatial distribution of

sites, correct siting, and quality-assured

and quality-controlled data are the most

important factors we consider when

evaluating the monitoring network for

air quality modeling. Nonattainment

area plans developed under title I, part

D of the Clean Air Act are not, in

general, required to address how the

area's air quality network meets our

monitoring regulations. These plans are

submitted too infrequently to serve as

the vehicle for assuring that monitoring

networks remain current.

The base year for the MAG plan is

1995. In 1995, there were 16 monitoring

sites operated by either MCESD or

ADEQ that collected PM-10 data in the

Phoenix area, three designated as

NAMS, five designated as state/local

monitoring stations, and eight

designated as special purpose monitors.

All of the sites were operated in

accordance with our regulations in

1995. Figure 3-2 in the MAG plan lists

the names of the sites and their

locations in the Phoenix area as of April

1999. Most of these PM-10 monitoring

sites were sited as neighborhood scale

with an objective of assessing

population exposure. Given the nature

of the emission sources in the Phoenix

area, which are mostly local fugitive

dust sources, we believe this is an

appropriate focus of the network.

The 24-hour attainment

demonstration in the MAG plan relies,

in part, on showing attainment at four

specific monitoring sites. These sites

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were chosen to evaluate the type and

mix of sources thought to be

contributing to elevated 24-hour PM-10

levels: Salt River for its proximity to

industrial sources; West Chandler for its

nearby highway construction; Maryvale

for its residential area coupled with

land disturbing activities due to the

construction of a park, and Gilbert for

its proximity to agricultural land. In

1995 these sites recorded the highest

and most frequent exceedances of the

24-hour PM-10 standard. They are also

representative of similar areas in the

Phoenix area that may not have

monitoring sites.

Based on our evaluation, we have

concluded that the monitoring network

operated by the MCESD and ADEQ in

1995 was adequate to support the air

quality modeling in the MAG plan. The

network utilized EPA reference or

equivalent method monitors and both

agencies have EPA-approved quality

assurance plans in place.

E. Contribution to PM-IO Exceedances

of Major Sources of PM-I 0 Precursors

CAA section 189(e) requires a state to

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.

We estimate that major stationary

sources contribute at most 0.61 gLg/m3 to

24-hour PM-10 levels in the Phoenix

area. See EPA TSD section, "BACT for

Major Stationary Sources of PM-10

Precursors." We estimated this

contribution by assuming that the major

stationary sources' contribution to

secondary levels is proportional to their

presence in the inventory. We believe

that this assumption is reasonable given

the very small presence of major

stationary sources in the precursor

inventory and the small contribution

total secondaries make to PM-10 levels

in Phoenix. Moreover, secondary

particulate takes hours to form in

ambient air from its precursors. By the

time secondary particluate is formed,

the precursors are well mixed in the

ambient air, so localized,

disproportionate impacts by major

sources of PM-10 precursors are very

unlikely.

This contribution is well below our

proposed 5 gg/m 3 significance level.12

However, independent of this fact, we

believe that so small a contributionless than 0.4 percent of the 24-hour PM10 standard of 150 gg/m3-is truly

insignificant by any measure for the

Phoenix area. PM-10 levels above the

24-hour standard in Phoenix are almost

exclusively caused by a few large source

categories of fugitive dust. It is controls

on these sources that are the key to

expeditious attainment and not controls

on trivial contributors such as major

stationary sources of PM-10 precursors.

Based on their negligible impact on

ambient PM-10 levels, we propose to

determine that major sources of PM-10

precursors do not contribute

significantly to PM-10 levels which

exceed the 24-hour standard in the

Phoenix area; therefore, pursuant to

CAA section 189(e), BACT need not be

applied to major sources of PM-10

precursors.

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. Under our applicable guidance,

BACM must be applied to each

significant area-wide source category.

Addendum at 42011. As discussed in

section V of this preamble, we have

established a four-step process for

evaluating BACM in serious area PM-10

plans.

1. Steps 1 and 2: Determination of

Significant Sources

The first step in the BACM analysis is

to develop a detailed emissions

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

second step is use this inventory in air

quality modeling to evaluate the impact

on PM-10 concentrations over the

standards of the various sources and

12The MAG plan demonstrates that the 5pg/m 3 is

the appropriate level for determining which

categories are significant for the BACM requirement

for the 24-hour standard; therefore, we believe that

it is an appropriate level for us to adopt here.

source categories to determine which

are significant.

The development of the detailed

emissions inventories is discussed in a

preceding section. 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 1995.13

From these evaluations, the MAG

plan identifies 8 significant source

categories and 12 insignificant source

categories. MAG plan, p. 9-6.

The final list of significant source

categories in the MAG plan does not

distinguish between those categories

that are significant for the 24-hour

standard and those that are 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 does not distinguish

significant source categories between

the two standards, we treat each of the

listed significant source categories as

significant for the 24-hour standard.

For the 24-hour standard, the MAG

plan demonstrates that its selection of

significant source categories is

appropriate by showing that controls on

the de minimis source categories would

not result in attainment of the 24-hour

standard by 2001. For a detailed

description of this demonstration, see

MAG plan, pp. 9-12 to 9-15 and the

EPA TSD section "BACM AnalysisStep 2, Model to Identify Significant

Sources."14

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

"Particulate Control Measure Feasibility Study,"

Sierra Research, January 1997; and the Microscale

plan.

14 In this de minimus demonstration, certain

source categories vacant land, unpaved roads,

agricultural sources, and unpaved parking-were

assumed to be uncontrolled at the end of 2001. See

MAG plan, Tables 9-b and 9-c. These categories

will in fact be subject to BACM by then. By not

including controls on these categories in the de

minimis demonstration, the gap between

nonattainment and attainment of the 24-hour

standard in 2001 is much larger than it should be

and thus, the de minimis determination for the 24-

hour standard is suspect.

To check if the selected de minimis categories are

truly de minimis under the correct control

assumptions, we redid the determination

incorporating the appropriate level of control for

each source category. We concluded from this

reanalysis that the MAG plan's selected de minimis

threshold is in fact appropriate and the identified

Continued

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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 (e.g., stationary point sources,

waste/open burning, agricultural

harvesting, charbroiling) 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.

2. Step 3: 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

nonattainment areas in the western

United States. MAG also evaluated

controls proposed during public

comment. MAG plan, pp. 9-24 through

9-29; MAG Plan, Appendix D, Exhibit

1, "Response to Public Comments,

de minimis categories are indeed de minimis and

are appropriately excluded from the BACM

analysis. See EPA TSD, section "BACM AnalysisStep 2, Model to Identify Significant Sources."

January 31, 2000 Public Hearing"; and

BMP TSD, pp. 9 through 27.

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 plan also

provides cost effectiveness estimates for

each of the candidate BACM. MAG

plan, pp. 9-30 through 9-39; and BMP

TSD, pp. 9 through 27.

We propose to find that the Maricopa

County serious area PM-10 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 plan left out any

candidate BACM. Overall, the plan

presents one of the most comprehensive

lists of potential BACM ever produced.

3. Step 4: Implementation of RACM and

BACM and inclusion of MSM for Each

Significant Source Category

In the following sections, we review

the results of the Maricopa County

serious area 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. 15 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.

Controls on a number of significant

source categories are in MCESD's

fugitive dust rules, Rule 310 and Rule

15 MAG plan uses this grouping despite the fact

that disturbed vacant lands include lands that are disturbed for reasons other than construction

activity.

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 proposed

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.

As discussed above, the MAG plan

made no distinction between significant

sources for the annual standard and

those for the 24-hour standard and, as

a result, it made no distinction between

BACM and MSM for the annual

standard and those for the 24-hour

standard. We have already extensively

reviewed the MAG plan's BACM and

MSM provisions for the annual standard

and these reviews are applicable to the

24-hour standard. Thus, except for

clarifying and/or updating information

on a few measures, we have not revised

our evaluations of BACM and MSM for

most of the significant source categories.

Four categories-on-road engines

(technology controls), nonroad engines,

unpaved roads and construction dusthave undergone moderate changes.

Our analysis of the agricultural source

category has changed substantially from

the annual standard proposal. As

discussed above, we based our review in

the annual standard proposal on the

State's legislation requiring the adoption

of measures for agriculture. Since then,

the State has adopted the agricultural

general permit rule and has submitted

revisions to the Maricopa County

serious area plan containing the

demonstration that the general permit

rule represents BACM and MSM. For

today's proposal, we have based our

review of BACM and MSM for the

agricultural sources on the general

permit rule and the State's additional

documentation. Our revised analysis

applies to both the annual and 24-hour

standards.

a. Technology Controls for On-road

Motor Vehicle Exhaust

This category includes tailpipe and

tire wear emissions of primary PM-10

from on-road motor vehicles. On-road

motor vehicles include both gasoline

and diesel-powered passenger cars,

light, medium, and heavy duty trucks,

buses, and motorcycles.

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

(I/M) programs, fuels, programs to

encourage alternative fueled vehicle

usage, and programs to accelerate fleet

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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 Cleaner Burning

Gasoline program which mandates the

use of either Phase II federal

reformulated gasoline or California

reformulated gasoline; 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.

As noted before, Arizona has in place

a 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.

See EPA TSD, Table ORM-3 in the

section "Implementation of BACM and

MSM for On-Road Motor Vehicle

Exhaust and Paved Road Dust

(Technology Standards and Fuels)."

The MAG plan identified just a few

measures from other areas as potential

MSM. These measures have either been

adopted or we have concluded that the

measure need not be included to assure

the inclusion of MSM.

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. 16 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.

Based on information in the

Microscale plan, emissions from onroad motor vehicle are not implicated in

24-hour exceedances in the Phoenix

area. Microscale plan, pp. 17-19. All

currently available evidence is that 24-

hour exceedances are caused by local

fugitive dust sources and controls on

these sources alone will result in the

earliest practicable date for attainment

of the 24-hour PM-10 standard in the

Phoenix area. Microscale plan, pp. 17-

19. Because implementation of CARB

diesel would not result in earlier

attainment and thus unnecessary for

expeditious attainment, we propose to

find that the MAG plan provides for the

inclusion of MSM to our satisfaction

absent the adoption and implementation

of CARB diesel.

Except for one, all the adopted BACM

and MSM were implemented by June

10, 2000, the BACM implementation

deadline for the Phoenix area. The

exception is the requirement that pre1988 heavy duty diesel vehicles

registered in the nonattainment area

meet 1988 federal emission standards.

This measure will not be fully

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 transportation

control measures (described in the next

section) in the MAG plan provides for

the implementation of RACM and

BACM and the inclusion of MSM for onroad motor vehicle exhaust for the 24-

hour standard.

Since the annual standard proposal

was published in April 2000, changes

have been made to two on-road motor

vehicle controls that were included in

that proposal: the remote sensing (RSD)

program in the State's vehicle emissions

inspection program (VEIP) and changes

to the State's incentives for purchase of

alternatively-fueled vehicles or

conversions to alternatively-fueled

vehicles.

16 Arizona has already adopted half of the CARB

diesel standards, the 500 ppm sulfur limit. 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. Also, in January 2001, we

established a new diesel fuel sulfur limit of 15 ppm

as part of our overall program to control emissions

from heavy duty diesel vehicles. They new limit

which will apply to Arizona will be fully in place

by September, 2006. 66 FR 5002 (January 8, 2001).

In 2000, the Arizona legislature

converted the RSD program from a

regulatory program to a pilot program

because of its high cost per ton of

emissions reduced 17 In July 2001,

Arizona submitted a SIP revision that

included all changes to State's VEIP

program that had been made since we

last approved it in 1995, including the

changes to the RSD program. 2001 I/M

SIP submittal, p. 26. We consider this I/

M program submittal to be Arizona's

current statement of what elements

constitute its VEIP.

The RSD program is not credited in

the RFP or attainment demonstrations

for the annual standard. The State

justifies its revision to this program

based on the implementation cost of the

unrevised program, that is, they have

determined that the unrevised program

was economically infeasible. We believe

that this change to the overall on-road

motor vehicle control program in the

MAG plan do not adversely affect our

previously proposed finding that the

plan provides for the implementation of

RACM and BACM and the inclusion of

MSM for this source category for the

annual standard found at 65 FR 19964,

19972.

b. Transportation Control Measures

(TCMs) for On-road Motor Vehicle

Exhaust and Paved Road Dust

TCMs can reduce PM-10 emissions in

both the on-road motor vehicle exhaust

and paved road dust source categories

by reducing vehicle miles traveled

(VMT) and vehicle trips (VT). 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 24-hour PM-10

concentrations in the Phoenix area (See

EPA TSD section, "BACT for Major

Stationary Sources of PM-10

Precursors" which shows that total

17 ADEQ, Final Arizona State Implementation

Plan Revision, Basic and Enhanced Vehicle

Emissions Inspection/Maintenance Program, June

2001 ("2001 I/M SIP submittal"), p. 26.

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secondary particulates from all sources

have a maximum impact of 9.2 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

vehicle exhaust.

In total, the MAG plan identifies 19

TCMs for consideration, including the

CAA section 108(f) measures. The plan

does not identify any potential most

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

potential MSM from other States.

Arizona has a long history of adopting

and then enhancing programs to reduce

emissions from on-road motor vehicles

by reducing VMT, VT, and/or

congestion. 18 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 and

acceptable justification for the rejection.

All the adopted TCM BACM were

implemented by June 10, 2000, the

BACM implementation date for the

Phoenix area, or have on-going

implementation schedules because they

are part of an on-going capital

18 These plans include the MAG moderate and

serious area carbon monoxide plans and MAG

moderate area ozone plan.

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 nonroad 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

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

potential most stringent measures from

other States.

We have adopted national emission

standards for a broad range of nonroad

engines. We consider that these

standards, which apply to nonroad

engines sold in Arizona constitute at

minimum a 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. CAA section

209(e)(2)(B).

Arizona legislation allows ADEQ to

adopt certain California nonroad engine

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

originally committed to adopt these

California nonroad standards; however,

subsequently, we adopted federal

nonroad engine standards that will

achieve essentially the same PM-10

reductions in the Phoenix area that

adoption of the California ones would.

As a result, Arizona determined that

adoption of the California standards

would not justify the resources ADEQ

would need to expend to adopt,

implement, and enforce them and has

now withdrawn its commitment. See

letter, Jacqueline E. Schafer, ADEQ, to

Laura Yoshii, EPA, "Justification for not

implementing CARB Off-road engine

standards for the Maricopa County PM10 SIP," September 7, 2001 ("ADEQ OffRoad Letter").

Arizona has adopted and

implemented a year-round Cleaner

Burning gasoline program and limits on

the sulfur content of diesel fuels. 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 nonroad engines

but does not adopt it. MAG plan, Table

10-7. 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.

Based on information in the

Microscale plan, emissions from

nonroad engines are not implicated in

24-hour exceedances in the Phoenix

area. Microscale plan, pp. 17-19. All

currently available evidence is that 24-

hour exceedances are caused by local

fugitive dust sources and controls on

these sources alone will result in the

earliest practicable date for attainment

of the 24-hour PM-10 standard in the

Phoenix area. Microscale plan, pp. 17-

19. Because implementation of CARB

diesel would not result in earlier

attainment and thus unnecessary for

expeditious attainment, we propose to

find that the MAG plan provides for the

inclusion of MSM to our satisfaction

absent the adoption and implementation

of CARB diesel.

We, therefore, propose to find that

MAG plan provides for the

implementation of RACM and BACM

and inclusion of MSM for nonroad

engines.

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

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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 VMT and VT, preventing

deposition of material onto a roadway,

and cleaning material off the roadway.

We have already discussed measures for

reducing VMT and VT in the section on

TCMs above.

The MAG plan lists several potential

BACM for paved road dust. It also lists

a number of potential 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 potential 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

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 PM-10-

efficient street sweepers measure

described below, all the adopted BACM

for paved roads were implemented by

June 10, 2001, the BACM

implementation deadline for the

Phoenix area, or have on-going

implementation schedules because they

are part of an 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, a MSM, 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. MCESD Rule 310, sections

308.2(c) and 308.3 address dirt track out

from construction/industrial sites

requiring 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 off-site each day to

control and prevent track out by

installing a track out control device. The

rule also requires all work sites to clean

up spillage or track out immediately

when it extends a cumulative distance

of 50 linear feet or more and, where

track out extends less than 50 feet, to

clean it up at the end of the work day.

The MAG plan identifies, as a

potential MSM for track out, South

Coast (Los Angeles area) Air Quality

Management District's (South Coast

AQMD) 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 each other out. MSM Study, p.

C-4.19 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 simply

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.

The commitments are set depending on

the resources available to each

jurisdiction to implement them.

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

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 MCESD

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

19 The "MSM Study" is the "Most Strigent PM10 Control Measure Analysis," Sierrra Research,

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

the MAG plan.

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in Imperial County (California)

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 310'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

roadways are track out, erosion, and

spill removal requirements and road

sweeping.

The MAG plan includes each of these

measures:

Material spillage, erosion, or

accumulation. MCESD 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

AQMD's Rule 1186 and Mojave Desert

(San Bernadino, California) AQMD'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 either the South Coast or

Mojave Desert 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,

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

and Air Quality (CMAQJ 20 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 in 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. 21 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

daily traffic (if available).22 MAG will

use this information to estimate the

emission reductions 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 PM20 CMAQ funds are federal transportation funds

awarded to certain nonattainment areas for

congestion management of air qualitytransportation projects such as paving unpaved

roads.

21 Some street sweepers may be additions to, as

opposed to replacements of, existing equipment. 22 See MAG, "Methodology for Evaluating

Congestion Mitigation and Air Quality

Improvement Projects," Draft Revised, June 21,

2001, pp. 18-22.

10 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. In addition, 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

will be implemented 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 only as

they replace existing equipment.

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

being purchased and placed in

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operation 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 be

reduced 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 on unpaved parking lots and

windblown dust entrained from the

disturbed surface of unpaved parking

lots.

There are two principal ways to

control emissions from unpaved parking

lots: prohibit unpaved parking lots or

treat existing lots. MAG plan identified

both: a prohibition on unpaved haul

road 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 potential MSM, South

Coast's Rule 403 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, section

303 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's standards/test

methods. 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, section 302.1 applies the same

stabilization requirements to parking

lots on permitted facilities. 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

first specifically considering whether

the plan provides for the

implementation of RACM for these

sources. 23 In our 1998 moderate area

PM-10 FIP for the Phoenix area, we

promulgated a RACM fugitive dust rule

applicable to unpaved parking lots in

the Phoenix PM-10 nonattainment area.

40 CFR 52.128(d)(3). This rule provides

a starting point for determining whether

the MAG plan's measures for unpaved

parking lots meet RACM. It is not

necessary for them 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. 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

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 (located in

23 While a serious area PM-10 plan must provide

for both the implementation of RACM (to the extent

that it has not already satisfied the requirement in

its moderate area plan) 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 generally necessary. However, in this particular

case, we have already established through our FIP

rule what we consider to be a RACM-level of

control for this source category. Thus our FIP rule

provides us with a baseline against which we can

review whether the MAG plan provides not only for

RACM but also goes beyond that for BACM. We also

intend to eventually withdraw the FIP rule in favor

of local controls. 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.

An explicit determination now simplifies this

future action.

the eastern third of the County). Rule

310.01 requirements became effective

when the rule was adopted on February

2000. In light of the fact that Rule

310.01 requirements are the same as the

FIP rule requirements and MCESD has

made enforceable commitments to

improve compliance and enforcement of

Rule 310.01, we propose that the MAG

plan provides for the implementation of

RACM. Given the additional city/town

commitments in the MAG plan that

collectively increase the stringency of

control on unpaved parking lots, we

propose that the MAG plan also

provides for the implementation of

BACM. Both Rule 310.01 and the city/

town commitments were implemented

prior to June 10, 2000, the BACM

implementation deadline for the

Phoenix area.

As the only potential MSM, the MAG

plan identifies South Coast's Rule 403

which requires sources to apply dust

suppressants to stabilize at least 80

percent of unstabilized surface area and

to comply with a 0 percent opacity

property line limit. The MAG plan

deems the respective requirements

roughly equivalent to Rule 310. MAG

plan, p. 10-29. 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 such that

it is at least equivalent to that of South

Coast Rule 403. We, therefore, propose

to find that the MAG plan correctly

concludes that there are no MSM 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. MAG plan, Table 5-2. The plan

also identified controls on weed

abatement operations and off-road

racing as potential MSM. MAG plan,

Table 10-7. 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.

Both MCESD rules 301 and 301.01

address vacant lots. Rule 310

requirements apply to vacant lots

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located at permitted facilities (including

construction sites) and Rule 310.01

requirements apply to nonpermitted

sources. 24 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 this source

category. See Footnote 23. In our FIP,

we promulgated a RACM fugitive dust

rule applicable to disturbed vacant land

in the Phoenix PM-10 nonattainment

area. 40 CFR 52.128(d)(3). This rule

provides a starting point for determining

whether the MAG plan's measures for

disturbed vacant lands meet the RACM

requirement. It is not necessary for them

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. 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. 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 resemble the Phoenix FIP rule's

weed abatement requirements, except

24 Permitted sources include any facility

permitted by MCESD and are not limited solely to

those facilities with earthmoving permits, Rule 310,

section 102.

that Rule 310's threshold for coverage is

lower.25

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 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 cityowned vacant lots. See EPA TSD section

"Implementation of BACM and

Inclusion of MSM for Disturbed Vacant

Land."

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 (as

discussed below), 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 which collectively increase the

stringency of control on vacant

disturbed lands, we propose that the

MAG plan also provides for the

implementation of BACM. All measures

for vacant disturbed lands were

implemented prior to the June 10, 2000

BACM implementation deadline for the

Phoenix area.

For its MSM analysis, 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 and

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 MSM 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

25 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 and 40 CFR 52.129(c)(3) and (d)(3)(i).

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.

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 does 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 23. In our

FIP, we promulgated a RACM fugitive

dust rule applicable to unpaved roads in

the Phoenix PM-10 nonattainment area.

40 CFR 52.128(d)(3). This rule provides

a starting point for determining whether

the MAG plan's measures for unpaved

roads meet the RACM requirement. It is

not necessary for them 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.

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 principal

control measure 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 (VPD) 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 accomplished before

June 10, 2000-paving all 80 miles of its

publicly-owned unpaved roads

regardless of the level of vehicle travel.

Phoenix Commitment, Measure 98-DC50264

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7. Other cities, such as Tempe and

Gilbert, have very few remaining miles

of public unpaved roads/alleys. See

Tempe Commitments, Measure 98-DC-7

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).26

MAG and MCDOT have committed to

pave County minimal maintenance

roads within the nonattainment area

that currently exceed 150 VDT and meet

criteria to become public highways,

using $22 million in CMAQ and

MCDOT funds. 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 account for 40 percent of all VMT

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 VDT. The County's

evaluation process takes into account

whether estimated costs of paving are

excessive (greater than $500,000 per

mile).27 When MCDOT identifies a road

that meets these criteria (i.e. the road

can be declared a public highway and

costs are not excessive), it will

26 Pacific Environmental Service, "Survey for

Fugitive Dust Emission Sources", April 15, 1999.

27 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.

recommend that the Board of

Supervisors open and declare the road

a public highway.28

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 little traffic on it.29 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 24-hour 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

28 Maricopa County provided an update to us of

their efforts to identify and pave County minimal

maintenance roads. Kelly McMullen, MCDOT, via

email on May 4, 2001. The County identified

approximately 68 miles of minimal maintenance

roads (courtesy grading only) that potentially could

have over 150 VPD traffic. Of those roads, the

County was unable to gather traffic count

information for approximately 3 miles due to

repeated counter vandalism or theft. The County

included remaining roads with traffic counts over

130 VPD (allowing for short term growth seasonal

variation, etc.) in its program to pave, totaling

approximately 65 miles, consisting of

approximately 186 segments. The first group of

these roads was expected to have a bid awarded in

June 2001 and be paved by Fall 2001. Design work

for the second group was expected to begin in

Summer 2001 and is expected to go to bid for

construction within the next twelve months. Design

work for the third group also expected to begin in

Summer 2001 and is expected to be bid

approximately 10-12 months following the second

group. This third group reflects the most difficult

engineering and environmental issues. Based on

project engineer estimates at this time, the County

believes that six segments totaling approximately

3.0 miles may exceed the reasonable cost threshold

of $500,000 per mile, or have issues with adjoining

property owners that are not possible to resolve

within the SIP time frames. The County will

evaluate whether another method of dust

suppression may be viable for those segments. 29 Through MAG, we requested additional

information on private unpaved roads from the

cities of Chandler, Scottsdale, Gilbert, Glendale,

Mesa, Phoenix, Tempe, Peoria, Avondale, Carefree,

Cave Creek, El Mirage, Goodyear, and Surprise.

Letter Colleen McKaughan, EPA, to Lindy Bauer,

MAG, March 21, 2001. All but three cities

responded to the survey. Five cities state that they

currently have no private unpaved roads with

greater than 150 VPD. Three cities indicate they do

not believe there are private unpaved roads with

greater than 150 VPD in their jurisdictions. The

remaining cities either have a small number of

private road miles identified with greater than 150

VPD or make no statement regarding the number of

private road miles with greater than 150 VPD in

their jurisdictions. Letter Lindy Bauer, MAG, to

Colleen McKaughan, EPA, June 29, 2001.

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's 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 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 these roads will be stabilized.

Evaluation of unpaved road measures

in other areas found none that are more

stringent than the measures for unpaved

roads in the MAG plan. MAG plan,

Table 10-7. We agree and propose to

find that there are no other MSM 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. Construction Sites and Activities

Sources of fugitive dust emissions at

construction sites 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 earthmoving, represent some

90 percent of the emissions in this

source category.

The suggested measure in the MAG

plan for controlling emissions from

construction sites are actually various

means of improving compliance with

controls rather than new control

requirements for construction sites. See

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MAG plan, Table 5-2. MCESD had

already adopted controls for

construction sites in its fugitive dust

rule, Rule 310. The plan also identifies

several potential MSM. See MAG plan,

Table 10-7. We propose to find that the

MAG plan evaluates a comprehensive

set of potential controls for construction

sites emissions including the potentially

MSM from other states.

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 30 and sources subject to title V

permits, 3 1 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 permitted sources, Rule 310

requires that a 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.

32

Specific Rule 310 requirements

include:

* a 20 percent opacity requirement

for any dust generating operation

* wind event controls

* implementation of controls before,

after and while conducting any dust

generating operation, including

weekends, after work hours and

holidays

* required controls and standards for:

* unpaved parking lots

3 0 Earthmoving 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.

31 Title V permits are operating permits required

by Title V of the Clean Air Act for major stationary

sources and certain other stationary sources.

32 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.

* 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 for all fugitive dust

sources; the contingency measure is to

be immediately implemented if the

primary control 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 controls for earthmoving

activities, 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.3a

Test methods associated with

stabilization and opacity standards are

contained in Appendix C, which was

submitted with Rule 310.

The 1999 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 SIPapproved version of Rule 310.

In addition to these Rule 310

revisions, MCESD made three

enforceable commitments to further

strengthen requirements for

construction sites in 1999. See Maricopa

County Commitments, Revised Measure

6. MCESD has recently revised these

commitments and will take the

revisions to the Maricopa County Board

of Supervisors in December, 2001 for

formal adoption as enforceable

commitments. See Letter, Al Brown,

MCESD to Jack Broadbent, EPA,

33 Unpaved roads must meet a 6 percent silt

content standard or, alternatively, a 0.33 oz/ft 2 silt

loading standard, while unpaved parking lots must

meet an 8 percent silt content standard or,

alternatively, a 0.33 oz/ft2 silt loading standard.

September 13, 2001 (MCESD

commitment letter). The commitments

are to:

1. Research and develop a standard(s)

and test method(s) for earth moving

sources, designed to be enforceable and

meet BACM requirements as to

stringency and the number of sources

that it applies to. Revise Rule 310 and/

or Appendix C by no later than

December 2002 to modify the existing

opacity standard/test method or add an

additional opacity standard(s)/test

method(s), tailored to non-process

fugitive dust sources that create

intermittent plumes. This commitment

will be met in its entirety only if the

standard(s)/test method(s) is approved

by EPA. The County is also proposing

to support and coordinate with Clark

County, Nevada in the ongoing research

to develop fugitive dust test methods

through the appropriation of $25,000.

2. Part 1: Onsite Implementation of Dust

Control Plan

Raise awareness of onsite project

supervisors to acquire and read

approved site dust control plans thereby

improving the implementation of the

dust control plan at the construction

site. This objective will be achieved

through one-on-one contact at the time

of inspection and through the

development of a revised training

curriculum and supporting materials for

both a classroom setting and onsite aids

for improved project management.

Maricopa County inspectors will

continue to go over dust control plans

with construction site personnel during

the initial site inspection and whenever

issues arise during subsequent

inspections. The training curriculum

being developed by the Arizona

Department of Transportation (ADOT) is

scheduled for completion in winter of

2002 and implementation of the second

level of dust control education will

begin March-June 2003.

Part 2: Dust Control Plan Improvements

Research, develop and incorporate

additional requirements for dust

suppression practices/equipment into

dust control plans and/or Rule 310 by

March-December 2002. Based on the

ADOT research, MCESD research or

other alternative research, Maricopa

County will develop a growing list of

criteria for effective versus ineffective

dust suppression practices that address

various site circumstances.

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

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Rule 310 and the dust control plan.

Distribute sample log sheets with issued

permits and conduct outreach to sources

by December 2001.

The first 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.

Field research is needed to identify an

appropriate standard(s) and test

method(s) to meet this commitment.

MCESD originally committed to

complete this research and revise the

opacity method by July 2001 but was

unable to do so. It now intends to work

with Clark County which has recently

conducted research on test methods for

earthmoving sources and is planning to

conduct a second phase of research.

MCESD will contribute funding to these

efforts. MCESD has requested a one-year

extension of the deadline in its original

commitment in order to monitor,

validate and verify the resulting test

method(s) performance in Maricopa

County.

The second commitment addresses

our concern that 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. Also, for effective dust

control, certain soil types may require

substantial pre-wetting, thorough

mixing of water into the soil for uniform

penetration, and/or dust surfactant or

tackifyer combined with water; neither

Rule 310 nor DCPs currently require

such measures for any sites.

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 and

has made it difficult to establish these

criteria. Because of this difficulty

MCESD has revised its original

commitment to allow additional time to

develop them.

MCESD has also expanded its original

commitment to include a program to

work with on-site supervisors to assure

that they obtain and review the DCP for

their sites. In implementing Rule 310

during the last year, it found that site

supervisors do not have or do not know

what is in their DCPs and thus may not

be implementing appropriate dust

control methods.

The third 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 revised its

original commitment to allow additional

time to work with its stakeholders to

develop daily recordkeeping log sheets

to provide sufficient detail documenting

the implementation of dust controls.

We propose to find that Rule 310 as

adopted on February 16, 2000 and

combined with the commitments by

MCESD to make certain additional

changes to the Rule, provide for the

implementation of RACM and BACM on

construction sites for the 24-hour PM10 standards. 34 We have also

determined that the revised

commitments do not affect our previous

proposed finding that Rule 310

combined with the commitments

provide for the implementation of

RACM and BACM on construction sites

for the annual standard. 65 FR 19964,

19980. 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).

The MAG plan identifies several

potential most stringent construction

site fugitive dust measures either in or

under consideration for inclusion in

others SIPs. See MSM Study, Table 1-

2 and Table 3-1.

34 These revised commitments are currently

unenforceable because they have not been adopted

by Maricopa County's Board of Supervisors. We are,

however, proposing to approve these commitments

under CAA section 110(k)(3) as an enforceable

element of the Arizona SIP because we fully expect

that the Board will adopt these commitments as

enforceable SIP commitments and the State will

submit them as a complete SIP revision prior to our

final action. However, if we do not receive the

adopted commitments by the time we must take

final action, we propose to conditionally approve

them under CAA section 110(k)(4). If we take final

action to conditionally approve these commitments,

MCESD will have one year to fulfill the

commitment or the approval will turn into a disapproval and we would no longer be able to find

that the MAG plan provides for the implementation

of BACM and the inclusion of MSM on construction

sites for either the annual or 24-hour standards.

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 310'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

controls 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 potential most 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

measures. 35 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 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

35 These requirements are not in Clark County's

fugitive dust rule but rather are required practices

in dust control permits.

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handling or transferring bulk material,

chemical/physical stabilization, or

sheltering/enclosure of the operation

and transfer line. While Maricopa

County Rule 310 requires owners/

operators to comply with a 20 percent

opacity standard for any dust generating

operation and DCP must include a

control measure for every fugitive dust

source (including bulk material

handling/transfer), it does not contain

specific requirements as Imperial

County does for this activity. However,

watering 15 minutes prior to handling

may be overly prescriptive and not

necessary in all cases to meet the rule's

performance standards. We propose to

find that Maricopa County's second

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. See Footnote 34.

i. Agricultural Sources

The agriculture source category covers

all dust generating activities and sources

on farms and ranches. These activities

and sources include land planning,

tilling, harvesting, fallow fields,

prepared fields, field aprons, and

unpaved roads. This source category is

a very significant contributor to 24-hour

PM-10 standard exceedances in the

Phoenix area. At the West Chandler site,

55 percent of the modeled exceedance

was due to agricultural sources (a cotton

field and its apron). At the Gilbert site,

26 percent of the modeled exceedance

was due to an agricultural source (a

field apron). See Microscale plan, pp.

18-19.

In order to develop adequate controls

for this source category, Arizona passed

legislation in 1997 establishing an

Agricultural Best Management Practices

(BMP) Committee and directing the

Committee to adopt by rule by June 10,

2000, an agricultural general permit

specifying best management practices

for reducing PM-10 from agricultural

activities. The legislation also required

that the implementation of agricultural

controls begin with an education

program starting by June 10, 2000 with

full implementation by December 31,

2001. See Arizona Revised Statutes

(A.R.S.) 49-457.

After a series of meetings during 1999

and 2000, the Agricultural BMP

Committee adopted the agricultural

general permit and associated

definitions, effective May 12, 2000, at

Arizona Administrative Code (AAC)

R18-2-610, "Definitions for R18-2-

611," and 611, "Agricultural PM-10

General Permit; Maricopa PM10

Nonattainment Area" (collectively,

general permit rule). The State

submitted the general permit rule in

July 2000 and its analysis quantifying

the emission reductions expected from

the rule and the demonstration that the

rule meets the CAA's RACM, BACM and

MSM requirements in June 2001. We

proposed to approve it as meeting the

CAA requirement for RACM on June 29,

2001 and signed the approval on

September 10, 2001. See 66 FR 34598.

The general permit rule requires a

commercial farmer to implement by

December 31, 2001 at least one BMP for

three categories of emission sources on

a farm: tillage and harvest, noncropland, and cropland. R18-2-610

defines commercial farmer as "an

individual, entity, or joint operation in

general control of 10 or more

continuous acres of land used for

agricultural purposes within the

boundary of the Maricopa County PM10

nonattainment area." R18-2-610

defines tillage and harvest as "any

mechanical practice that physically

disturbs cropland or crops on a

commercial farm." R18-2-610 defines

non-cropland as "any commercial farm

land that: is no longer used for

agricultural production; is no longer

suitable for production of crops; is

subject to a restrictive easement or

contract that prohibits use for the

production of crops; or includes a

private farm road, ditch, ditch bank,

equipment yard, storage yard, or well

head." R18-2-610 defines cropland as

"land on a commercial farm that: is

within the time frame of final harvest to

plant emergence; has been tilled in a

prior year and is suitable for crop

production, but is currently fallow; is a

turn-row." R18-2-610 defines a BMP as "a technique verified by scientific

research, that on a case-by-case basis is

practical, economically feasible and

effective in reducing PM-10 particulate

emissions from a regulated agricultural

activity."

For enforcement purposes, a

commercial farmer is required to

maintain a record demonstrating

compliance with the general permit. A

commercial farmer not in compliance

with the general permit is subject to a

series of compliance actions described

in A.R.S. 49-457.1-K.

The BMP Committee began

implementing the general permit rule in

June 2000 by means of an extensive

educational outreach program informing

growers about the BMPs. In addition,

the BMP Committee developed a Guide

to Agricultural PM-10 Best Management

Practices to provide information and

guidance on how to effectively

implement BMPs.36 Farmers must be in

compliance with the general permit rule

by December 31, 2001.

For the reasons discussed below and

more extensively in the section

"Implementation of BACM and

Inclusion of MSM for Agricultural

Sources" in the EPA TSD, we propose

to find that the State's general permit

rule meets the CAA's requirements to

provide for the implementation of

BACM by June 10, 2000 in CAA section

189(b)(1)(B) and to include MSM in

section 188(e). Our proposed finding is

applicable to both the annual and 24-hr

standards. It revises our previously

proposed finding in the annual standard

proposal that the State's commitment in

the MAG plan to adopt and implement

agricultural best management practices

meets the CAA's requirements for

BACM and MSM by substituting the

BMP general permit rule. 65 FR 19964,

19981.

In September 1998, the Agricultural

BMP Committee appointed an Ad-hoc

Technical Group to develop a

comprehensive list of potential BMPs

for regulated sources in the Maricopa

County nonattainment area. Participants

on the Ad-hoc Group included the

USDA NRCS, USDA Agricultural

Research Service, University of Arizona

College of Agriculture, ADEQ,

University of Arizona College of

Agriculture and Cooperative Extension,

Western Growers Association, Arizona

Cotton Growers Association, Arizona

Farm Bureau Federation, and EPA. BMP

TSD, p. 15.

The Ad-hoc Technical Group

reviewed available dust control

regulations, literature, and technical

documents, and developed a list of 65

conservation practices potentially

suitable to agricultural sources in the

Maricopa County nonattainment area for

further consideration. BMP TSD, p. 16.

These 65 measures represented a broad

spectrum of potential BMPs, many of

which related to conservation practices

used in the western United States that

had never been evaluated in the context

of reducing PM-10.

The Agricultural BMP Committee

thoroughly reviewed the potential

practices presented by the Ad-hoc

Technical Group and evaluated the

potential BMPs using available

information on technological feasibility,

costs, and energy and environmental

impacts. After an analysis of the limited

36 "Guide to Agricultural PM-10 Best

Management Practices, Maricopa County, Arizona

PM-10 Nonattainment Area," Governor's

Agricultural BMP Committee, First edition,

February, 2001.

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information available and numerous

public discussions, the Committee

decided to include 34 of the 65 BMPs

in the general permit rule and divided

these 34 BMPs into the three categories

of farm activities specified in A.R.S. 49-

457.N.: 10 BMPs applicable to the tillage

and harvest category; 10 BMPs

applicable to the non-cropland category;

and 14 BMPs applicable to the cropland

category. See BMP TSD, 17. In selecting

these BMPs, the Committee deemed

them to be feasible, effective and

common sense practices for the Phoenix

area which minimized potential

negative impacts on local agriculture.

Of the 31 potential BMPs eliminated,

the majority were dropped because they

either duplicated another BMP or did

not reduce PM-10. Other reasons for

elimination included the

impracticability of a BMP for the

Maricopa County Area, lack of cost

effectiveness, or infeasibility of

implementation. See June 13, 2001 BMP

submittal, Enclosure 3, Attachment 8.

At the time the BMP Committee was

developing the general permit rule,

there was very limited available

information concerning the

technological feasibility, costs, and

energy and environmental impacts of

these BMPs. Although the Committee

determined that all the selected BMPs

were technologically feasible control

requirements, it found that calculating

the other impacts on a commercial

farmer was difficult. Because of the

variety, complexity, and uniqueness of

farming operations in Maricopa County,

the Committee concluded that farmers

need a variety of BMPs in each of the

three categories of agricultural activities

to choose from in order to tailor PM-10

controls to their individual

circumstances. Further, the BMP

Committee acknowledged that there is a

limited amount of scientific information

available concerning the emission

reduction and cost effectiveness of some

BMPs, especially in relation to Maricopa

County. The BMP Committee balanced

the limited scientific cost effectiveness

information with the common sense

recognition that the BMPs would reduce

wind erosion and the entrainment of

agricultural soils, thereby reducing PM10. As a result, and given the myriad

factors that affect farming operations,

the BMP Committee concluded that

requiring more than one BMP for each

of the three agricultural categories could

not be considered technically justified

and could cause an unnecessary

economic burden to farmers. Instead,

the BMP Committee and ADEQ agreed

to monitor the effectiveness of the BMPs

and adjust the program, if needed, in the

future. BMP TSD, p. 18.

The general permit rule, as finally

adopted by the BMP Committee in May

2000 as BACM and MSM, requires that

commercial farmers implement at least

one BMP for the tillage and harvest,

cropland, and non-cropland categories

by December 31, 2001.

We define a BACM-level of control 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. Based on the BMP committee's

findings regarding technological

feasibility and economic effects of

requiring more than one BMP per

category, we believe that the BMP rule

provides the maximum degree of

emission reductions achievable from the

agriculture source category in the

Phoenix area and, therefore, meets the

BACM requirement in section

189(b)(1)(B). 37

A requirement that an individual

source select one control method from

a list, but allowing the source to select

which is most appropriate for its

situation, is a common and accepted

practice for the control of dust. For

example, in its PM-10 FIP for Phoenix,

we promulgated a RACM rule

applicable to, among other things,

unpaved parking lots, unpaved roads

and vacant lots. The rule allows owners

and operators to choose one of several

listed control methods (pave, apply

chemical stabilizers or apply gravel). 40

CFR 52.128(d). In the case of the FIP,

those subject to the fugitive dust rule

were given a choice of control methods

in order to accommodate their financial

circumstances. 38

37 We also considered a BACM-level control as

going beyond existing RACM-level controls, such as

expanding use of RACM (e.g., paving more miles of

unpaved roads). Addendum at 42013. As noted

previously, we have proposed to approve the

general permit rule as meeting the RACM

requirement in CAA section 189(a)(1)(C). 66 FR

34598. In that proposal, we stated our belief "that

the general permit rule represents a comprehensive,

sensible approach that meets, and in fact far

exceeds, the RACM requirements of CAA section

189(a)(1)(C) and EPA guidance interpreting those

requirements." 66 FR 34598, 34602. Moreover, we

explained that the State also intended the general

permit rule and its enabling legislation to meet the

CAA's serious area requirements. 66 FR 34598,

34599. Thus today's proposal that the general

permit rule meets the BACM and MSM

requirements of the Act is consistent with our prior

action.

38 See, as examples, SCAQMD Rule 403

(providing for alternative compliance mechanisms

for the control of fugitive dust from earthmoving,

disturbed surface areas, unpaved roads etc.); and

SCAQMD Rule 1186 (requiring owners/operators of

certain unpaved roads the option to pave,

chemically stabilize, or install signage, speed

bumps or maintain roadways to inhibit speeds

greater than 15 mph). We proposed to approve these

Allowing sources the discretion to

choose from a range of specified options

is particularly important for the

agricultural sector because of the

variable nature of farming. As a

technical matter, neither we nor the

State is in a position to dictate what

precise control method is appropriate

for a given farm activity at a given time

in a given locale. The decision as to

which control method from an array of

methods is appropriate is best left to the

individual farmer. Moreover, the

economic circumstances of farmers vary

considerably. As a result, it is

imperative that flexibility be built into

any PM-10 control measure for the

agricultural source category whether

that measure is required to meet the

RACM or BACM requirements of the

Act.

We believe that the work of the BMP

Committee resulted in the timely

adoption of the general permit and

educational programs that requires

BACM implementation on a schedule

that will allow time for the agricultural

community to understand and select

appropriate BMPs and to transition to

new practices, some of which may

involve the purchase of new equipment.

Based on these factors, we believe that

the BMP implementation schedule is as

expeditious as practicable and meets the

BACM implementation deadline for the

Phoenix area of June 10, 2000.

The MAG plan identified two

potentials MSM for agricultural sources

(1) cessation of tilling on high winds

days in South Coast's Rule 403.1 and (2)

soil erosion plans in South Coast's Rule

403. MAG plan, Table 10-8. The plan

concluded that neither is, by itself,

MSM for the Phoenix area.

South Coast's 403.1, "Wind

Entrainment of Fugitive Dust," applies

only in the Coachella Valley (Palm

Springs) portion of the South Coast Air

Basin and requires that, when wind

speeds exceed 25 miles per hour (mph),

agricultural tilling and soil mulching

activities should cease. While the

measure applies throughout the year,

the high wind days tend to occur during

a high-wind season that extends

between April and June. The Coachella

Valley typically experiences high winds

on 47 days of the year. MAG estimated

that there were a total of 37 hours,

SCAQMID rules as meeting the RACM and/or BACM

requirements of the CAA on August 11, 1998 (63

FR 42786) and took final action approving them on

December 9, 1998 (63 FR 67784). See also the

approval of Maricopa County Environmental

Services Department (MCESD) Rule 310 as meeting

the RACM/BACM requirements (62 FR 41856,

August 4, 1997) and the proposal to approve

updated Rule 310 and MCESD Rule 310.01 as

meeting the same requirements (65 FR 19964, April

13, 2000).

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representing 11 days, with wind speeds

greater than 15 mph in 1995 in

Maricopa County.

The BMP general permit rule includes

"limited activity during high wind

event" as one of ten BMPs that a grower

can choose for the Tillage and Harvest

category. According to an analysis in the

MAG plan, postponing tilling on high

wind days would reduce emissions by

72 percent on high-wind days. MSM

study, p. 4-23. However, because only

15 percent of the Maricopa County PM10 nonattainment area tilling occurs

during the high wind season (March

through September) and because less

than 4 percent of the days during this

period experience winds greater than 15

mph, the air quality benefits of the

measure would be small (i.e, 0.08 metric

tons per average annual day in 1995) for

the annual standard. MSM study, p. 4-

23. Emissions from tilling are a very

small contributor to total agricultural

emissions on the 1995 design day

(which was a high-wind day),

representing just 1.6 percent of all

agricultural emissions and are not

implicated in 24-hour exceedances.

URS, Technical Support Document for

Quantification of Agricultural Best

Management Practices, June 8, 2001 (Ag

Quantification TSD), p. 3-11 and

Microscale plan, pp. 18-19. Moreover,

based on the limited amount of

information available regarding the

control efficiencies for the ten BMPs in

the Tillage and Harvest category, the

control efficiency for "limited activity

during high-wind event" is on average

as effective or less effective than the

other BMPs in this category. Ag

Quantification TSD, pp. 2-8 to 2_10.

South Coast's Rule 403, "Fugitive

Dust," requires the implementation of

conservation practices to reduce PM-10

from agricultural sources in the South

Coast PM-10 nonattainment area. Under

Rule 403(h), agricultural operations

exceeding 10 acres within the South

Coast Air Basin are exempt from the

rule's requirements for fugitive dust if

the farmer implements the conservation

practices in the most recent Rule 403

Agricultural Handbook. See "Rule 403

Agricultural Handbook: Measures to

Reduce Dust from Agricultural

Operations in the South Coast Air

Basin," South Coast AQMD, December

1998 (the Handbook). Because the

requirements of Rule 403 are more

stringent than the requirements for

conservation practices in the Handbook,

it is assumed that farmers will always

choose to comply with the latter's

provisions. Thus the Handbook, rather

than Rule 403 itself, is effectively the

potential MSM.

For a variety of reasons, it is difficult

to directly compare the requirements in

the general permit with the

requirements in the Handbook. First, the

South Coast did not attempt to estimate

the reductions and cost from each

conservation practice. Second, the types

of crops grown in Maricopa County and

the South Coast area differ significantly.

For example, cotton is a dominant crop

in Maricopa County but is not grown in

the South Coast Air Basin. Third, the

Handbook allows a grower to substitute

a local ordinance for the three

conservation practices required for

"inactive" agricultural land; however,

the minimum requirements for the local

ordinance are not specified. Handbook,

section II, p.4. Fourth, the general

permit rule and the Handbook also

differ in terms of exemption and

waivers. The general permit rule does

not exempt any crop types or provide a

waiver option, but the Handbook

exempts orchards, vine crops, nurseries,

range land, and irrigated pastures from

requiring a practice for the active and

inactive categories. Finally, the

Handbook also allows farmers to request

a waiver if the farmer cannot apply the

required practices or a verifiable

alternative.

While the general permit rule divides

agricultural activities into three

categories and the Handbook divides

them into six, and the terminology used

is different, the categories of activities

covered are essentially coterminous. Cf.

Handbook, section I and ACC R18-2-

610.7, .12, .22, .33. However, depending

on the type of farming operation, the

general permit rule would require

implementation of at least one BMP for

each of the Tillage and Harvest,

Cropland, and Non-Cropland categories

and the Handbook requires from one to

three practices for its six agricultural

categories.

As discussed above, in the BACM

section of this TSD, the BMP Committee

concluded that, because of the variety,

complexity, and uniqueness of farming

operations and because agricultural

sources vary by factors such as regional

climate, soil type, growing season, crop

type, water availability, and relation to

urban centers, agricultural PM-10

strategies must be based on local factors.

Therefore, the general permit rule, as

finally adopted by the BMP Committee

in May 2000, reflects the conclusion of

the BMP Committee that farmers need a

variety of BMPs to choose from in order

to tailor PM-10 controls to their

individual circumstances. Further, the

BMP Committee acknowledged that

there is a limited amount of scientific

information available concerning the

emission reduction and cost

effectiveness of some BMPs, especially

in relation to Maricopa County. The

BMP Committee balanced these

limitations with the common sense

recognition that the BMPs would reduce

wind erosion and the entrainment of

agricultural soils, thereby reducing PM10.

While the Committee surveyed

measures adopted in other geographic

areas, these measures were of limited

utility in determining what measures

are available for the Maricopa County

area. Given the limited scientific

information available and the myriad

factors that affect farming operations,

the BMP Committee concluded that

requiring more than one BMP could not

be considered technically justified and

could cause an unnecessary economic

burden to farmers.

Adding to concerns about the

economic feasibility of requiring more

BMPs per farming activity is the general

uncertainty regarding the cost of the

BMPs and continued viability of

agriculture in Maricopa County.

Between 1987 and 1997, the number of

farms operating in Maricopa County

declined by approximately 30 percent

and the amount of land farmed declined

by approximately 50 percent. This trend

is expected to continue. Finally, in

order to justify additional requirements

for farming operations in the area

beyond those in the general permit rule,

the BMP Committee determined that a

significant influx of money and

additional research would be needed.

BMP TSD, p. 18.

Based on all of these factors, the BMP

Committee concluded that the

Handbook's practices were neither

technologically nor economically

feasible for agricultural sources in

Maricopa County. BMP TSD, p. 18.

We agree with the analysis of the BMP

Committee. As noted previously, the

development of the general permit rule

was a multi-year endeavor involving an

array of agricultural experts familiar

with Maricopa County agriculture.

Maricopa County is only the second

area in the country where formal

regulation of PM-10 emissions from the

agricultural sector has ever been

attempted. For the reasons discussed

above, we propose to conclude that the

BMP general permit rule meets or

exceeds the stringency of South Coast

Rule 403.1's requirement for cessation

of tilling during high winds. Based on

the forgoing analysis of the Handbook,

we also propose to conclude that the

Handbook's requirements are neither

technologically nor economically

feasible for Maricopa County. Because

all the identified potential MSM have

either not been demonstrated to be more

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stringent than existing Maricopa County

controls or found to be infeasible for the

area, we propose to find that the MAG

plan provides for the inclusion of MSM

as required by CAA section 188(e) to our

satisfaction.

j. Residential Wood Combustion

The residential wood combustion

(RWC) category includes emissions from

the burning of solid fuel in residential

fireplaces and woodstoves as well as

barbecues and firepits.

Measures to control PM-10 from

residential woodburning include a

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

lists 11 potential BACM and 10

potential MSM. MAG plan Tables 5-2

and 1-7. We believe these list are

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

gLg/m3). 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 gLg/m 3. We proposed to approve the

revised ordinance as part of the annual

standard proposal. 65 FR 19964, 19990.

In addition, A.R.S. section 9-500.16 and

A.R.S. section 11-875 (1998) required

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. All measures were

implemented by June 10, 2000, the

BACM implementation deadline for the

Phoenix area. We, therefore, propose to

find that the MAG plan provides for the

implementation BACM for residential

wood combustion.

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 (NH 3). 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 NOx emissions were

identified and have been evaluated for

on-road motor vehicles and nonroad

engines. We believe this 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 in the Phoenix area and therefore

are not technologically feasible. 39 The

estimated reduction in ammonia from

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 NOx that should be called significant

in terms of contributing to ammonium

nitrate levels. See MAG plan, Table 3-

1.

Arizona has adopted a number of

measures for controlling NOx emissions

from motor vehicles and nationally, we

have established emission standards for

control of NOx from both on- and

nonroad engines. The MAG plan does

not identify any technologically feasible

measures for the control of ammonia.

For these reasons, 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 enforceable

commitments are found in Maricopa

County, 1999 Revised Measure 6,

adopted December 15, 1999. A narrative

description of them 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 E.3.h.

"Construction Sites and Activities."

39 We consider a measure technologically feasible

for an area only if it has the potential to reduce

emissions in a manner that reduces ambient

concentrations in the area.

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These improvements to the

compliance and enforcement programs

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.

We review these enforceable

commitments and their current status

below:

Staffing

Maricopa County committed to

increasing its inspection staff to 8

inspectors, 1 supervisor, 1 aide and 2

enforcement officers by the end of

January 2000 and to add a coordinator

to the Small Business Environmental

Assistance Program to assist smaller

builders and construction companies

and to help develop and implement

education programs. It also committed

to hire an attorney in the County

Attorney's office to expedite civil

litigation and to assist with prosecuting

Class One Misdemeanor cases by April

2000. Total resources devoted to the

fugitive dust program were to be

increased to 15 positions, a 25 percent

increase over previous levels. After

reaching the committed staffing level,

MCESD was to review the program in

March 2000 to evaluate its effectiveness

and the potential need to add more staff.

By the end of January 2000,

inspection unit staffing increased to 8

inspectors, 1 supervisor, 1 coordinator

(to oversee permit issuance and track

notices of violations), 2 aides and 2

enforcement officer. By May 2000, the

County Attorney's office hired an

attorney, paralegal, and support staff. In

2000, the Department found that the

existing staff in the Small Business

Environmental Assistance Program was

able to handle the workload for assisting

smaller builders and construction

companies and for helping to develop

and implement education programs.

MCESD will re-evaluated the need for

an additional coordinator in the small

business assistance program when the

second generation outreach and

education materials are completed. In

total, resources devoted to the fugitive

dust program during the past year were

17 positions, a 42 percent increase over

previous levels.

Organization

MCESD created a new enforcement

section 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, MCESD committed to

locate inspectors in two new regional

offices to provide quicker response

times to dust-related complaints and

allow more time in the field. It has in

fact located inspectors in four regional

offices.

Funding

For FY 1999-2000, revenue for

fugitive dust program was projected to

be $1.12 million from annual earth

moving permit fees, a $772,000 increase

over the previous level. The increase

was due to the 1998 fee increase for

earth moving permits.

For FY 2000-2001, anticipated

revenue for the fugitive dust program is

approximately $1.7 million, generated

from annual earth moving permit fees.

This is a $1.35 million increase over the

previous level.

Inspection Program

MCESD committed to 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

committed to initially direct its

inspections to cities lacking such

programs and to track the city plans that

are required by State statute to stabilize

target unpaved roads, alleys and

unpaved shoulders.

Prior to its adopting additional

commitments in December 1999,

MCESD had already 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.

MCESD did develop by April, 2000

inspection priorities for vacant lots and

unpaved parking lots considering lot

size and number of sources with larger

lots being inspected first and smaller

lots in succeeding years. EPA and

MCESD initially attempted, but were

unsuccessful, to convert an Assessor's

Office database of vacant lots into a

user-friendly format for identifying

priority lots. Now, MCESD inspectors

are assigned geographical districts and

are compiling notes on the vacant lots

and unpaved parking lots in each

district during their routine surveillance

activities. Under current MCESD policy,

the inspectors are first directed to

handle all complaints and then to begin

to address the larger sites on the

individual district lists. In 2000, the

inspectors made 499 inspections on

vacant lots, unpaved parking lots, and

unpaved roads.

Enforcement Program

To meet its commitment to revise its

enforcement program, MCESD issued a

revised air quality enforcement policy

on April 28, 2000. See Air Quality

Violation Reporting and Enforcement

Policy and Procedure, MCESD, April 28,

2000. This policy:

* Includes guidelines for initiating

various enforcement actions

* Includes guidelines for reinspecting

* Defines 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

* Identifies priority violations

* Includes guidelines for when to

seek penalties reflecting the economic

benefit of noncompliance, if feasible

* Includes guidelines for seeking and

determining higher penalties for repeat

violators

* Includes 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 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 enables

the enforcement officers to work on

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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.

In 2000, MCESD revised its dust

control guidelines with its partners

ADOT and Arizona State University.

This year ADOT secured a research

grant directed towards developing

educational tools and outreach

programs. This product will enhance

the current guidelines, add information

on the life cycle costs of controls and

controls' impact on the construction

process, and develop additional

outreach tools. In addition, MCESD is

currently working with two contractors

to develop a model environmental

management system for construction.

These two efforts will add to the

technical knowledge on dust control

and offer additional tools for companies

to increase compliance with regulations.

Program Evaluation and Tracking

MCESD committed to track the

number of inspections, number and type

of enforcement actions, amount of

penalties assessed, and amount of

penalties collected. It also committed to

conduct mid-year reviews of the

program in September, 2000 and again

in March 2001 to evaluate progress and

future needs.

MCESD conducted its reviews and

will conduct then again in September,

2001 and again in March 2002 to

evaluate progress and future needs. In

2000, MCESD conducted 6625

inspections. In the first year of operation

under the new enforcement process, it

issued 189 violations, processed 145

settlement cases and netted $425,000 in

fines (May 1, 2000 to April 30, 2001).

G. Attainment Date Extension

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 SIP revisions containing a

demonstration of attainment by the most

expeditious alternative date practicable.

We evaluate the Maricopa County

serious area plan's compliance with

each of these requirements below.

1. Apply for an Extension

A state must apply for an extension

and concurrently submit a SIP revision

containing a demonstration that the area

will attain by the most expeditious

alternative date practicable. The state

must provided the public reasonable

notice and a hearing on the application

before it is sent to EPA.

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. The documentation

supporting this request is found 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,

including the demonstration that the

area will attain the 24-hour standard by

the earliest alternative date practicable.

2. Demonstrate the Impracticability of

Attainment by December 31, 2001

CAA section 189(b)(1)(a)(ii) and our

proposed policy on extension requests

require that the serious area 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 in order to claim

that attainment by that date is

impracticable.

To evaluate the impracticability of

attainment by 2001, the MAG plan

evaluated the impact of BACM on

sources at both the West Chandler and

Gilbert sites in 2001. The evaluation

showed these BACM-level controls left

24-hour PM-10 levels well above the

24-hour standard at both sites in 2001,

thus demonstrating attainment is

impracticable by then. MAG plan,

Appendix C, Exhibit 3, pp. 3-10 and 3-

11.

In this demonstration, the MAG plan

assumes controls only on the "permitted" sources, that is, only on

those sources that receive permits from

MCESD. The plan assumes that all

"nonpermitted" sources-unpaved

roads, vacant lots, and unpaved parking

lots-are uncontrolled in 2001. MAG

plan, Appendix C, Exhibit 3, pp. 3-10

and 3-11. This latter assumption does

not reflect the efforts by MCESD to

assure the implementation of BACM on

these sources and is inconsistent with

the assumptions made for these sources

in the annual standard impracticability

demonstration.

To check to see if using consistent

assumptions between the annual

standard and 24-hour standard

demonstrations would show that

attainment of the 24-hour standard is

practicable by 2001, we recalculated the

2001 impacts at each monitor using the

control assumptions from the annual

standard demonstrations and additional

control information from the BMP TSD.

In these recalculations, we assume that

the sources at the microscale site are in

full compliance with the applicable

rule. See the "Extension RequestDemonstrate the Impracticability of

Attainment by December 31, 2001" in

the EPA TSD.

Our recalculations show that

attainment of the 24-hour standard at

the West Chandler site remains

impracticable by 2001. The principal

sources at this site are an agricultural

field, its apron, and a construction site.

The site needs substantial reductions, in

excess of 50 percent, in agricultural

emissions in addition to controls on the

construction site before the 24-hour

standard can be attained. This level of

emission reduction from agricultural

sources is not expected until 2006.

However, our recalculations show

that attainment of the 24-hour standard

at the Gilbert site is practicable by 2001.

The site's primary source, an unpaved

parking lot, is subject to full control

under Rule 310.01 by 2001 and controls

on this source together with controls on

the other major source at Gilbert, a

vacant lot (also required by Rule 310.01)

result in the site showing attainment by

2001.

In order to show attainment, a plan

must show attainment at each location

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within the nonattainment area. Because

the West Chandler site is still unable to

show attainment of the 24-hour

standard by 2001, the Phoenix

nonattainment area as a whole is unable

to show attainment by that date. Thus

the MAG plan's conclusion that

attainment of the 24-hour standard in

the Phoenix area is impracticable by

December 31, 2001 is correct. We,

therefore, propose to find that

attainment of the 24-hour standard is

impracticable by December 31, 2001.

3. Complied With Commitments and

Requirements in the SIP

We interpret this criterion to mean

that the state has implemented the

emissions reducing measures in the

plan revisions it has submitted to

address the CAA requirements in

sections 172 and 189 for PM-10

nonattainment areas.

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 principal controls in

this plan were Rule 310 and the County

woodburning ordinances. The 1991 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 plan also

contained a large number of

commitments from the local

jurisdictions to implement 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

earlier 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

In our proposed policy for granting

extension requests under CAA section

188(e), we suggest a 5-step process for

identifying and adopting MSM. See

section V.B.4. of this preamble. This

process is similar to the one we have

established for determining BACM, but

with one additional step, to compare the

potential MSM against measures already

adopted in the area to determine if the

existing measures are most stringent.

The first two steps in our proposed

MSM policy are to develop a detailed

emissions inventory of PM-10 sources

and source categories and to 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. The MAG plan,

however, excludes no source categories

of directly-emitted PM-10 from its MSM

analysis and moves directly to the third

step in the MSM determination,

identifying potential MSM in other

implementation plans or used in

practice in other states for each source

categories 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.

The fourth step in our proposed

policy for MSM is to compare the

potential MSM for each significant

source category against the measures, if

any, already adopted for that source

category in the local area. In the MAG

plan, 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

lists of affected sources, fewer

exemptions, and/or one or more

substantive regulatory provisions not

found in the Maricopa measure. The final step in our proposed policy

for MSM is to provide for the adoption

of any MSM that is more stringent than

existing similar local measures and

provide for implementation as

expeditiously as practicable or, in lieu

of providing for adoption, provide a

reasoned justification for rejecting the

potential MSM, i.e., why such measures

cannot be feasibly implemented in the

area. In the MAG plan, MSM that

remained after the screening in step 4

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, MAG plan, p. 10-46, and

BMP TSD, pp. 19 to 27.

Based on our analysis of the MAG

plan's provisions for identifying and

adopting MSM, we propose to find that

the MAG plan demonstrates 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 potential MSM for

commercial feedlots/livestock areas.

However, the two rules control different

emission activities 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 fewer than 80 dairies

(most of which are actually outside the

nonattainment area). 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 and are not necessary

for expeditious attainment. We,

therefore, propose to 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

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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. Since then, the medical waste

incinerators in this category have shut

down and today there are even fewer

emissions. Because incinerators are a

trivial source and controls on them

would not advance the attainment date

and are not necessary for expeditious

attainment, we propose to find that the

MAG plan provides 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 be 0.6 mtpd or 227 mtpy.

1994 Regional PM-10 Inventory, p. 4-

25. This is 0.4 percent of the daily

directly-emitted 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 AQMD is developing a new rule

to deal with underfired charbroilers and

MCESD will wait until South Coast

completes its rulemaking, now

scheduled for late 2001, to adopt this

measure. 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

establish MSM for controls 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 CAA section

189(b)(1)(A)(ii). We also propose to find

that the attainment demonstration relies

on control measures that either are

approved or have been proposed for

approval and meet our SIP

enforceability criteria; that the

emissions estimates credited to 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.

The following is a brief summary of

our evaluation of the modeling in the

MAG plan. Our full evaluation is in the

EPA TSD section "Extension RequestDemonstrate Attainment by the Most

Expeditious Alternative Date Practicable

after December 31, 2001."

a. Air Quality Modeling

The attainment demonstration for the

24-hour standard is divided into two

parts, a microscale analysis and a

regional analysis. The microscale part

evaluates 24-hour exceedances at four

monitoring sites in the Phoenix area

using a version of the industrial source

complex (ISC) model. The regional part

evaluates 24-hour levels throughout the

rest of the Maricopa County

nonattainment area using the Urban

Airshed Model-Linear Chemistry

version (UAM-LC).

As discussed previously, Arizona has

made three submittals that contain

elements of the attainment

demonstration for the 24-hour PM-10

standard: the 1997 Microscale plan, the

2000 revised MAG plan, and the 2001

BMP TSD. A more complete description

of these submittals can be found in

section 2 of this preamble and in section

1 of the EPA TSD. We briefly describe

here how these submittals fit together to

create the overall attainment

demonstration for the 24-hour standard.

The first of the three submittals, the

1997 Microscale plan, contains a

microscale, or localized, inventory and

modeling analysis using the ISCST

model of 24-hour standard exceedances

at four monitoring sites in the Phoenix

area: Maryvale, Salt River, West

Chandler and Gilbert. It shows

attainment of the standard at the

Maryvale and Salt River sites but does

not demonstrate attainment for the

Gilbert and West Chandler sites, both of

which were substantially affected by

agricultural sources.40

The second submittal, the 2000

revised MAG plan contains a regional

modeling analysis of 24-hour standard

exceedances using UAM-LC. It also

uses the ISCST model to determine that

a 58 percent reduction in agricultural

emissions is needed to attain the 24-

hour standard at the West Chandler site

40Because we have already approved the

attainment demonstrations at the Maryvale and Salt

River sites, we do not further discuss these sites in

this proposal. See 62 FR 41856, 41863.

and 20 percent at the Gilbert site. 41

However, at the time of its submittal,

Arizona had not yet completed adoption

of its BMP general permit rule and also

had not yet quantified the expected

reductions from rule and thus was

unable to model the impact of the rule

at these two sites.

The third submittal, the 2001 BMP

TSD, documents the expected emission

reductions from the BMP general permit

rule. This submittal does not contain

new modeling but rather shows that the

rule's emission reductions, together

with a reasonable estimate of land use

change, provide greater reductions than

needed for attainment at the Gilbert and

West Chandler sites.

1. Modeling Approach to the 24-Hour

PM-10 Standard Attainment

Demonstration

Our guidance on attainment

demonstrations generally assumes that

the entire nonattainment area will be

modeled using a dispersion model.42

However, emissions inventory

development and modeling for areas

with substantial fugitive dust problems,

such as the Phoenix area, have proved

difficult, because of fugitive dust

emissions' marked uncertainty and their

temporal and spatial variability.

Accurately estimating emissions for

input to dispersion modeling of fugitive

dust over a large area is much more

difficult than for point sources of

gaseous pollutants, which were the

archetypes for development of much of

our modeling guidance.

Thus, in areas dominated by fugitive

dust sources, the approach of

intensively inventorying and modeling a

small area is a reasonable one. This

approach is also more reflective of the

nature of fugitive dust. Fugitive dust

PM-10 is emitted near ground level and

has relatively sharp spatial gradients as

dust settles out with distance from the

source, and hence has more localized

effects than the other criteria pollutants,

which are typically buoyant and

gaseous.

Under the microscale approach used

in the MAG plan, the areas around the

exceeding monitors are deemed to be

representative of locations throughout

the nonattainment area. Attainment is

41 See p. 3-9 in ADEQ, "Evaluation for

Compliance with the 24-hour PM-10 Standard for

the West Chandler and Gilbert Microscale Sites,"

June 1999 (ADEQ TSD), found in Appendix C,

Exhibit 3 of the MAG plan.

42 A dispersion model models how emissions

from sources are dispersed into the atmosphere

based on local wind patterns and speeds and other

meteorological parameters. The two principal

inputs into a dispersion model are temporally- and

spatially- distributed emissions and meteorological

information.

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demonstrated at locations representing

the various mixes of emission sources

that occur in the area. Although a

specific emitting activity, such as new

housing construction, will eventually

decline in a given location, it will

reappear elsewhere as the metropolitan

area grows. A location that is currently

experiencing a lot of construction can

thus be used to represent locations

where construction will occur in the

future. Moreover, in the MAG plan all

locations exceeding the 24-hour PM-10

standard in 1995 were subjected to

analysis. A demonstration of attainment

at these locations will show that the

mixes of sources that caused

exceedances in the Phoenix area will be

controlled sufficiently to meet the

standard.

Although there is solid reasoning

underpinning the microscale approach

in a fugitive dust-dominated area such

as Phoenix, there is concern that for a

large urban area the sheer number of

sources, especially fugitive dust area

sources, could make for a pervasive

regional component of PM-10 in

addition to the more localized or

microscale component. Additionally, a

portion of PM-10 is fine particles,

which can stay suspended longer and so

can be transported greater distances

than coarse particulate.

Fine particulate includes secondary

particulate, which forms chemically in

the air from precursors like ammonia

and oxides of sulfur and nitrogen.

Secondary particulate is formed by

chemical reactions in a mixture of

emissions from various sources, spread

over hours and a spatial scale of 10's of

kilometers. Like ozone, it is a regional

pollutant, and so needs to be modeled

on a larger scale. Although only a small

fraction (4 percent) of the total PM in

the Maricopa area, secondary particulate

is present. While this regional

component could partly be addressed by

adding a background concentration to

microscale modeling, the determination

of a background is ambiguous since it

includes the effect of sources similar to

those in the microscale domain. For

these reasons, the MAG plan include

regional modeling in addition to the

microscale analysis.

2. EPA's Review of the Air Quality

Modeling in the MAG Plan

In today's proposal, we focus our

discussion on the supplemental

microscale modeling for the Gilbert and

West Chandler sites in the ADEQ TSD

and the evaluation of the agricultural

general permit rule in the BMP TSD. We

have already extensively reviewed both

the microscale modeling and the

regional modeling in previous proposals

and found them acceptable. See our

proposal on the Microscale plan at 62

FR 31025, 31029 and the proposal on

the annual standard at 65 FR 19964,

19985. 4 3 See also the EPA TSD section

on "Extension Request-Demonstrate

Attainment by the Most Expeditious

Alternative Date Practicable after

December 31, 2001."

The approach used for the

supplemental modeling in the ADEQ

TSD is essentially the same approach

used in the Microscale plan. They differ

in just three ways. First, the ADEQ TSD

uses a new calculation of background

concentrations (that is, the impact on

ambient PM-10 levels in the microscale

area of sources outside the microscale

area). Second, it evaluates PM-10

concentrations at multiple locations

within the microscale domain. Finally,

it evaluated various levels of reductions

from agricultural controls, in order to

determine the emission reductions

needed for attainment.

New background values were

calculated in order to reflect the

regional implementation of controls.

These controls reduce the contribution

to ambient PM-10 levels in the

microscale area of sources outside the

microscale area. To recalculate the

background values, ADEQ split the

background between windblown and

non-windblown contributions, applying

controls only to the windblown

contribution. See ADEQ TSD, p. 3-7.

The evaluation of PM-10

concentrations at multiple locations

within the microscale area is an

improvement to the previous microscale

modeling. In the Microscale plan, the

evaluation was limited to the actual

location of the ambient air quality

monitor within the microscale domain.

The evaluation of the emissions

reductions needed for attainment in

2006 at the West Chandler site

(assuming a 90 percent level of control

on the construction site) showed that a

58 percent reduction in emissions from

agricultural aprons and fields was

needed. For the Gilbert site, a 20 percent

emission reduction is shown to be

needed from the agricultural apron.

ADEQ TSD, pp. 3-9.

The BMP TSD shows that BMP

general permit rule, together with a

43 For the regional model, 65 individual days

were analyzed in the base year and attainment year,

that is, MAG ran the UAM-LC model for each of

these 65 24-day days. To evalute the 24-hour

standard, the individual results from each one of

these modeling runs are used. To evaluate the

annual standard, the results from all the modeling

runs for each year are averaged together. Thus, in

reviewing the modeling for the annual standard

demonstrations, we necessarily also reviewed the

modeling for the regional 24-hoar standard

demonstrations.

reasonable estimate of land use changes,

provide a 60.3 percent reduction by

2006. This reduction is sufficient to

demonstrate attainment by 2006 at West

Chandler. For the Gilbert site, the rule

provides more than the 20 percent

needed for attainment by 2006. BMP

TSD, p. 9.

This 60.3 percent reduction at the

West Chandler site is a combination of

a 36.6 percent emissions reduction from

the BMP general permit and a 37

percent emissions from the conversion

of agricultural land to residential and

commercial use. 44 This land use

conversion rate is derived from a land

use model for the overall nonattainment

area and represents the reduction

regionally in agricultural lands between

1995 and 2006. BMP TSD p. 28.

Under the microscale approach, the

areas around the exceeding monitors are

deemed to be representative of locations

throughout the nonattainment area.

Thus, applying regionally the controls

needed for attainment at these

representative sites is assumed to assure

attainment at similar sites throughout

the nonattainment area. One aspect of

this approach, which was not

adequately explored in earlier

submittals, is to how to treat the

inevitable changes in land uses and

activities within the microscale

domains. For example, construction

activity, like that at the West Chandler

site, will eventually be completed and

no longer contribute to emissions in the

area.45

A land use and socioeconomic model,

in conjunction with a dispersion model,

could legitimately show that

exceedances no longer occur in the area

simply based on this change in land use.

However, just waiting for land use

changes alone to reduce emissions is not

an acceptable method of demonstrating

attainment at the individual microscale

sites because once again, the premise

underlying the microscale approach is

that each site is representative of other

similar areas in the nonattainment area.

In a growing metropolitan area like that

of Phoenix, there will always be areas

with on-going construction.

On the other hand, the opposite

extreme of assuming no conversion of

agricultural lands at all does not seem

reasonable either. The reality is that the

44 The reductions are not additive because the

BMP general permit rule reduces emissions only

from the land left in agricultural production. The

overall control effectiveness is calculated as the

percent lost agricultural lands + BMP rule

effectiveness * percent remaining agricultural lands

or 37% + 0.366*63%.

45 In fact, at the West Chandler site, the

construction is complete and agricultural land has

been converted to residential and commercial uses.

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metropolitan area is growing and

agricultural land is rapidly being

converted. Such changes have been

observed over the past decades and are

projected to continue.

In this situation, using an estimate

from the area's land use model of the

conversion of agricultural lands to occur

by 2006 is a reasonable approach to use.

This approach is a compromise between

the extremes of the no-conversion and

the total-conversion assumptions. It is

driven by the area's socioeconomic

projections that are used for many

purposes and represent the best

available information about the land use

changes the overall area will experience.

Also, using an area average figure is

consistent with the area wide

application of control measures required

under the submittal's approach. Reliably

predicting the conversion for a

particular small area (several square

miles in the microscale approach)

would be problematic in any case, since

it would depend on knowing

individuals' purchase decisions and

development plans. Aggregate

conversion figures, driven by larger

economic forces and representing the

average of many actions, should be more

reliable.

Assuming some land use change is

more in line with the traditional use of

microinventories in EPA's PM-10

attainment demonstration guidance, and

also is in line with how attainment

demonstrations are performed in

general. Typically the projections for

land use, employment, industrial

production, population, vehicle traffic,

etc. are part of the baseline conditions

assumed in projecting future air quality;

in an attainment demonstration they are

independent of, but used in conjunction

with, estimates of control measure

effectiveness. In other words, reductions

that occur naturally because of

socioeconomic changes are implicitly

counted in attainment demonstrations.

Conversely, growth in emission sources,

e.g., vehicle traffic, are also implicitly

counted and must be compensated for

by additional emission reductions.

In summary, we believe that the

approach used in 2001 BMP TSD, while

not completely consistent with how the

microscale approach was implemented

in the 1997 Microscale plan,

nevertheless, is a reasonable balance

between different possible

implementations of a microscale

approach. Overall, we propose to find

that technical evaluation in the MAG

plan is adequate to support the

attainment demonstration for the 24-

hour standard at the West Chandler and

Gilbert sites.

b. Control Measures Relied on for

Attainment

For demonstrating attainment of the

24-hour PM-10 standard, the MAG plan

relies on reductions in directly-emitted

PM-10 from 3 measures: MCESD's

Rules 310 and 310.01 and the

agricultural BMP general permit rule.

ADEQ TSD, pp. 3-3 to 3-6 and BMP

TSD, p. 8. We have proposed to approve

all of these measures. See 65 FR 19992,

19989 and 66 FR 34598.

As part of these proposed approvals,

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. For

MCESD's rules, see sections on

proposed approval of Rule 310 and

310.01 in the TSD supporting the

annual standard proposal. For the

agricultural general permit rule, see 66

FR 34598.

We have also evaluated the emissions

reductions credited to each measure in

the attainment demonstrations to ensure

they are reasonable. In performing the

microscale analysis, ADEQ first

determined that each significant, nonagricultural source at the microscale

sites (e.g., the unpaved parking lot at the

Gilbert site) was large enough to be

subject to Rules 310 or 310.01.46 For

each of these sources, ADEQ then

applied the control factor used in the

Microscale plan for that source. Except

for the agricultural sources, it did not

use rule effectiveness factors for either

the sources in the microscale

component or the sources in the

windblown background component in

the attainment demonstrations.

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. Because RE factors are

intended to reflect the variations in

compliance among large numbers of

sources, they are applied to source

categories rather than to individual

sources.

We agree that it is appropriate not to

apply an RE factor to the individual

4 6 Rule 310 and Rule 310.01 do not apply to

sources under a certain size. For example, Rule

310.01 does not apply to vacant lots under 0.1

acres. Rule 310.01, section 301.

sources at each microscale site; 47

however, we believe that an RE factor

should be applied to the windblown

background source categories because

each category represents multiple

sources. To determine the effect of

applying the RE factor to sources in the

windblown background, we reevaluated the attainment

demonstrations at both Gilbert and West

Chandler. We found that the plan still

demonstrates attainment of the 24-hour

standard as expeditiously as practicable.

See EPA TSD section "Extension

Request-Demonstrate Attainment by the

Most Expeditious Alternative Date

Practicable after December 31, 2001,"

We find that the emission reduction

estimates for each source category are

consistent with research on the

applicable control methods and are

appropriately applied in the attainment

demonstrations. For more information

on the quantification of emission

reductions from Rules 310 and 310.01

see the section "Extension RequestDemonstrate Attainment by the Most

Expeditious Alternative Date Practicable

after December 31, 2001" in the EPA

TSD for the annual standard proposal.

For more information on the

quantification of emission reductions

from the agricultural general permit

rule, see the section "Implementation of

BACM and Inclusion of MSM for

Agricultural Sources" in the EPA TSD

for this proposal.

We have also determined that the

measures relied on for attainment are

being expeditiously implemented. Rule

310 and 310.01 are effective now.

Implementation of the agricultural

general permit rule began in July 2000

and will be completed by December 31,

2001.

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. Nothing in this

additional information presented on the

five factors suggests that granting an

extension of the attainment date for the

Phoenix area to 2006 is inappropriate.

a. Nature and Extent of Nonattainment

In the Phoenix area, elevated 24-hour

levels of PM-10 occur mainly in areas

with large fugitive dust sources or with

a concentration of fugitive dust sources.

47 At each microscale site, there is only a single

source in each category, that is there is a single

vacant lot, a single construction site, a single

agricultural field with its apron, a single unpaved

parking lot.

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Areas such as this can be found

throughout the Phoenix nonattainment

area, so we would expect that there are

elevated 24-hour PM-10 levels

throughout the Phoenix area. In order to

attain the 24-hour standard in this

situation, controls need to be uniformly

implemented throughout the area, a task

that generally requires longer to achieve

than implementing controls in a few

localized areas.

b. Types and Numbers of Sources or

Other Emitting Activities

Primary contributors to elevated PM10 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 to inform them of

our FIP fugitive dust rule; 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.

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 nonroad 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 nonroad engines)

target emissions from on and nonroad

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 24-hour PM-10

standard and not from on- and nonroad

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

emissions inventory in the Maricopa

nonattainment area and are the most

significant contributors to 24-hour PM10 exceedances. 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 and

other capital improvements needed 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 attainment date for the 24-hour

PM-10 standard in the Phoenix PM-10

serious nonattainment area from

December 31, 2001 to December 31,

2006.

H. Reasonable Further Progress and

Quantitative Milestones

CAA section 172(c)(2) requires

nonattainment plans to provide for

reasonable further progress (RFP).

Section 171(1) of the Act defines RFP as "such annual incremental reductions in

emissions of the relevant air pollutant as

are required by this part [part D 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."

CAA section 189(c) also requires PM10 plans demonstrating attainment to

contain quantitative milestones which

are to be achieved every 3 years until

the area is redesignated attainment and

which demonstrate RFP. These

quantitative milestones should consist

of elements that allow progress to be

quantified or measured. Addendum at

42016.

1. Reasonable Further Progress

The MAG plan provides for annual

progress toward attaining the 24-hour

standard. This demonstration shows

that most of the projected reductions

occur after 2001; however, this is an

artifact of the assumption that there are

no controls on agricultural sources,

vacant lots and unpaved parking prior

to December 31, 2001. This assumption

does not reflect the efforts by MCESD to

assure the implementation of BACM on

these sources and the requirement for

BMPs to be implemented by then. If the

RFP demonstration is revised to include

emission reductions from BACM on

these sources, then the majority of the

emission reductions occur before 2001.

See the "Reasonable Further Progress

and Quantitative Milestones" section in

the EPA TSD.

In order to demonstrate RFP, the plan

first regionalizes the inventories at the

two microscale sites by multiplying

emissions from each source by a factor

of 360, which is the ratio of the size of

the nonattainment area (2,880 square

miles) to the size of the microscale sites

(8 square miles). It then calculates the

emission reductions from the

application of the adopted measures to

these sources. Next, it annualizes these

emission reductions by multiplying the

sources-which are all windblown

sources-by 11, the number of windy

days in 1995. Finally, the annualized

figure is divided by 365 days to get an

average annual day emission reductions.

See BMP TSD, pp. 29-31.48

Regionalizing and annualizing the

microscale inventories is a good

approach to demonstrating RFP and

establishing milestones for the 24-hour

standard in the Phoenix area. Just a few

source categories are explicitly

identified contributors to exceedances

of this standard, and it is effective

controls on these categories that are

necessary for progress and attainment.

Therefore, closely tracking the effect of

48 There was an error in the original RFP

calculation on pages 29 to 31 in the BMP TSD.

ADEQ corrected this error and provided us a

revised RFP and contingency measure

demonstrations and quantitative milestones in a

letter. See letter, Jacqueline E. Schafer, ADEQ, to

Laura Yoshii, EPA, "Addendum to June 13, 2001,

Submittal of State Implementation Plan revision for

the Agricultural Best Management Practices

program in the Maricopa County PM-10

Nonattainment Area," September 7, 2001 ("ADEQ

RFP Addendum Letter")

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those controls on these source categories

is essential. Regionalizing and

annualizing the microscale inventories

allows this to be done.

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 given the

evidence that progress is being made

over time and the implementation of

controls are not being delayed.

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 [24-hour

PM-10] national ambient air quality

standard by the applicable date" as

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

2. Quantitative Milestones

Quantitative milestones based on

regionalized and annualized microscale

inventories are provided for 2001, 2003,

and 2006. See RFP Addendum Letter,

Enclosure 2. These are the same

milestone years used for the annual

standard. See 65 FR 19964, 19988. The

assumptions regarding control

measures' implementation and

effectiveness that underlie the

quantitative milestones are reasonable

and consistent with the RFP

demonstration.

The plan does not provide milestones

for each of the two microscale sites.

Milestones are intended as checks along

the way, a means of judging actual

emission reductions and control

measure implementation against those

projected in the plan. Arguably, given

the microscale analysis that is the basis

for the Phoenix area's 24-hour standard

plan, quantitative milestones should be

established for both the West Chandler

and Gilbert sites. However, this

approach would actually defeat the

purpose of the quantitative milestones

rather than fulfill it.

In order to report on a quantitative

milestone at the microscale sites,

Arizona would need to evaluate the

implementation of controls at each site.

However, land uses and activities

around each of these microscale sites

have changed significantly since 1995.

For example, at the West Chandler site,

the road construction has been

completed and the agricultural field and

its apron have been converted into

stores. Thus, reporting on each site's

quantitative milestones would tell us

more about the land use changes around

each site than about the implementation

of controls. Because of this, the

quantitative milestones for the 24-hour

plan need to reflect regional

implementation of controls. The MAG

plan's approach of regionalizing and

annualizing the emissions inventories

from the microscale sites and then

basing its RFP demonstration and

milestones on the resulting inventory is

an appropriate way to deal with these

requirements for the 24-hour standard.

For these reasons, we propose to find

that the MAG plan meets the

quantitative milestone requirement in

CAA section 189(c)(1) for the 24-hour

standard.

L Contingency Measures

Section 172(c)(9) of the Clean Air Act

requires that implementation plans

provide for the implementation of

specific measures to be undertaken if

the area fails to make RFP or attain by

its attainment deadline. These

contingency measures are to take effect

without further action by the State or

the Administrator. The Act does not

specify how many contingency

measures are necessary nor does it

specify the level of emission reductions

they must produce.

We interpret the "take effect without

further action by the State or the

Administrator" to mean that no further

rulemaking actions by the State or EPA

would be needed to implement the

contingency measures. Addendum at

42015.

The purpose of contingency measures

is to ensure that additional emission

reductions beyond those relied on in the

attainment and RFP demonstrations are

available if there is a failure to make

RFP or attain by the applicable

attainment date. These additional

emission reductions will assure

continued progress towards attainment

while the SIP is being revised to fully

correct the failure. To ensure this

continued progress, we recommend that

contingency measures provide emission

reductions equivalent of one year's

average increment of RFP. Addendum at

42016.

Certain core control measure

requirements such as RACM, BACM,

and MSM may result in a state adopting

and expeditiously implementing more

measures than are strictly necessary for

expeditious attainment and/or RFP.

Because of this and because these core

requirements effectively require the

implementation of all non-trivial

measures that are technologically and

economically feasible for the area, states

are left with few, if any, substantive

unimplemented control measures. In

fact, under the Act's PM-10 planning

provisions, if there were a measure or

set of measures that were

technologically and economically

feasible and could collectively generate

substantial emission reductions, e.g.,

one year's worth of RFP, then a state

would be hard pressed to justify

withholding their implementation. 4 9

If we read the CAA to demand that

the only acceptable contingency

measure are those that are adopted but

not implemented, then states face a

difficult choice: adopt the controls for

immediate implementation and clearly

meet the core control measure

requirements but fail the contingency

measure requirement or adopt the

control measures but hold

implementation in reserve to meet the

contingency measure requirement but

potentially fail the core control measure

requirements.

However, states do not need to face

this difficult choice if we read the CAA

to allow adopted and implemented

measures to serve as contingency

measures, provided that those measures'

emission reductions are not needed to

demonstrate expeditious attainment

and/or RFP. There is nothing in the

language of section 172(c)(9) that

prohibits this interpretation. This

approach to the contingency measure

requirement also has the benefit of

allowing states to build uncredited

cushions into their attainment and RFP

demonstrations, which makes actual

failures to make progress or attain less

likely, while still obtaining the air

quality and public health benefits from

the implemented measures.

We have allowed this approach,

which is effectively the early

implementation of contingency

measures, in ozone and carbon

monoxide plans. See memorandum, G.

T. Helms, Chief, Ozone/Carbon

Monoxide Programs Brand, OAQPS to

Air Branch Chiefs, Regions I-X, "Early

Implementation of Contingency

Measures for Ozone and Carbon

Monoxide (CO) Nonattainment Areas,"

August 13, 1993. In this memorandum,

we note that several states wished to

implement their contingency measures

early even though they were not needed

for their attainment or RFP

demonstrations and that "[i]t seems

illogical to penalize nonattainment areas

that are taking extra steps to ensure

attainment of the NAAQS by having

them adopt additional [replacement]

contingency measures now." This

rationale applies with equal force to

PM-10 plans.

49 We do not believe that States are obligated by

section 172(c)(9) to adopt infeasible or unreasonable measures or measures that individual or collectively have trivial benefit.

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Annual Standard

The revised MAG plan as submitted

in February 2000 identifies 5 measures

as contingency measures with a

collective emission reduction of 5.5

mtpd: the agricultural BMP general

permit rule, off-road engine standards,

the clean burning fireplace ordinance,

and additional dust controls from the

cities of Tempe and Phoenix. MAG

plan, p. 8-19.

Since the MAG plan was submitted,

Arizona has made changes to its

contingency measure package for the

annual standard. First, Arizona has

withdrawn its commitment to adopt

California's off road vehicle standards

because the federal nonroad program

produces essentially the same emission

reductions. ADEQ Off-Road Letter.

Second, the emission reductions from

the agriculture contingency measure

have been recalculated based on the

BMP general permit rule as adopted.

The emission reductions from the

revised contingency measures package

are now 6.9 mtpd. See EPA TSD

"Contingency Measures" for more

details on the emission calculations.

All the measures that have been

identified in the MAG plan as

contingency measures have been

adopted and are being implemented but

are not credited in the attainment, RFP

or milestone demonstrations for the

annual standard and are not necessary

to demonstrate expeditious attainment

of that standard. Under our applicable

policies, states are allowed to use

implemented but uncredited measures

as contingency measures.

Under our contingency measure

policy, we recommend contingency

measures have total emission reductions

equal to or more than the annual RFP

increment. For the Phoenix area, the

average annual increment in RFP for the

annual standard is 5.5 mtpd/year for the

full 11-year period, 1995 to 2006. See

EPA TSD, "Reasonable Further Progress

and Quantitative Milestones."

Collectively, the specified contingency

measures generate 6.9 mtpd.

Based on this analysis, we propose to

find that the MAG plan provides for the

implementation of contingency

measures for the annual standard as

required by CAA section 172(c)(9).

24-Hour Standard

The identified contingency measure

for the 24-hour standard is controls for

unpaved roads and alleys. BMP TSD, p.

30. This measure comprises not only the

unpaved road provisions in MCESD

Rule 310.01 but also the commitments

by local jurisdictions to control unpaved

roads. See MAG plan, pp. 7-75 to 7-94.

This measure is estimated to reduce

emissions by 12.19 mtpd in 2006. MAG

plan, p. 8-9. The average annual

increment in RFP for the 24-hour

standard is 10.9 mtpd/year. See ADEQ

RFP Addendum Letter, Enclosure 1.

The unpaved road measure that is

identified in the MAG plan as

contingency measure for the 24-hour

standard has been adopted and is being

implemented but is not credited in the

attainment, RFP or milestone

demonstrations for the 24-hour standard

and is not necessary to demonstrate

expeditious attainment of that standard.

Under our applicable policies, states are

allowed to use implemented but

uncredited measures as contingency

measures.

Based on this analysis, we propose to

find that the MAG plan provides for the

implementation of contingency

measures for the 24-hour standard as

required by CAA section 172(c)(9).

J. 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 (51.230-51.232) and

for resources in 40 CFR 51.280.

States and responsible local agencies

must demonstrate that they have the

legal authority to adopt and enforce

provisions of the SIP and to obtain

information necessary to determine

compliance. SIPs must also describe the

resources that are available or will be

available to the State and local agencies

to carry out the plan, both at the time

of submittal and during the 5-year

period following submittal of the MAG

plan.

Other than revisions to Maricopa

County's revised commitments to

improve Rule 310, we are not proposing

to approve any control measures in this

proposal. All commitments and rules

relied on in the MAG plan to meet the

CAA requirements for the 24-hour PM10 standard are already approved, were

proposed for approval in the annual

standard proposal, or proposed for

approval in a subsequent notice. In

these notices, we have already proposed

to find that the implementing agencies

for the MAG plan have adequate

resources for implementing their

respective commitments and provided

an opportunity for comment. We are not

reproposing these findings.

Finally, we initially proposed to find

in the annual standard proposal that all

agencies and jurisdictions have

adequate authority under Arizona state

law to implement their respective

commitments and, where applicable, to

obtain information necessary to

determine compliance. 65 FR 19964,

19989. While minor changes have been

made to several control measures (e.g.,

the remote sensing program), the State

continues to have adequate authority to

implement the measures. No other

changes have been made to any agencies

and/or jurisdictions authority since we

proposed the annual standard.

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

and the BMP General Permit.

Procedures for monitoring compliance

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

rules are described in Maricopa

County's commitments and the BMP

TSD. See Maricopa County

commitment, 1999 Revised Measure 6

and BMP TSD, pp 33-34.

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).

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V. CAA Requirements for BACM and

Attainment Date Extension and EPA's

Guidance on Meeting These

Requirements

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 was June 10, 2000.

The Act does not define what level of

control constitutes a BACM-level of

control. In guidance, we have defined it

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. This level of control is

dependent on the deadline by which

BACM must be implemented. 5

We also considered a BACM-level

control as going beyond existing RACMlevel controls, such as expanding use of

RACM (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.

BACM is a best available control

measure. A control measure is a

combination of a statement of

applicability and the control

requirement, that is, what sources in the

category are subject to the measure and

what the measure require the sources to

do to reduce emissions. 51 Both these

elements must be specified before the

measure's level of control (i.e., its

stringency) can be determined, thus in

setting out a BACM, a state must specify

both the measure's control requirement

5o We have long held that an otherwise available

measure is reasonable and thus not an available

measure if it cannot be implemented on a schedule

that will advance the attainment date. See, for

example, 57 FR 13498, 13560 (April 16, 1992). See,

also Delaneyv. EPA 898 F.2d 695 (9th Cir. 1990)

which required the adoption of "all available

control measures" to attain "as soon as possible"

and not simply all available control measures. The

most clear example of this is a measure that cannot

be implemented until after the applicable

attainment date.

51 An example: a measure requires all unpaved

roads with ADT over 150 be stabilized by either

paving, graveling, or treating with chemical

stabilizers. The control requirement here is

"Stabilize using one of these three methods: paving,

graveling, or chemical stabilization" and the

applicability is "all unpaved roads with ADT over

150."

and its applicability. The control

requirement alone is not sufficient.

BACM must be applied to 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 5 gLg/m 3

or more of PM-10 to a location of 24-

hour 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. 5 2

The recent decision by the Ninth

Circuit Court of Appeals in Ober v.

Whitman 243 F.3d 1190 (9th Cir. 2001)

(Ober I) supports the use of a de

minimis exemption in BACM analyses.

Ober I was a challenge to our 1998 PM10 moderate area FIP for the Phoenix

area in which we exempted from the

RACM requirement, source categories

with de minimis impacts on PM-10

levels. In the FIP, we established a de

minimis threshold of 1 gLg/m 3 for the

annual standard and 5 gLg/m 3 for the 24-

hour standard, borrowing these

thresholds from our new source review

program for attainment areas to as a

starting point in the de minimis

analysis. In evaluating the

appropriateness of these thresholds, we

showed that they did not eliminate

controls that would make the difference

between attainment and nonattainment

by the applicable attainment deadline,

and therefore were the appropriate

thresholds. See 63 FR 41326, 41330

(August 3, 1998).

52 This principle is best illustrated by an example:

In Area A, attainment of the 24-hour standard by

December 31, 2001 requires that PM-10 ambient

levels at exceeding locations be reduced by 40 pg/ m 3 to 150 pg/m 3

. After application of BACM to all

source categories above the proposed de minimis

level, PM-10 levels are reduced by 32 pg/m 3.

BACM on the proposed de minimis source

categories would reduce levels by a further 3 pg/ M 3

, but still leaves ambient levels 5 ig/m 3 short of

the reduction needed to show attainment. Since

application of BACM to the proposed de minimis

source categories still leaves ambient levels above

the attainment level of 150 pg/m 3, the proposed de

minimis level is appropriate.

In its ruling, the court held that we

have the power to make de minimis

exemptions to control requirements

under the Clean Air Act and that our

use of the de minimis levels from the

NSR program was appropriate. Ober II at

1195 and 1197. In addition, the court

determined that it was appropriate for

us to use, as a criterion for identifying

de minimis sources, whether controls

on the sources would result in

attainment by the attainment deadline.

Ober II at 1198. Ober 11 dealt with a de

minimis exemption from the RACM

requirement, but its reasoning applies

equally to the BACM requirement.

We have outlined in our guidance a

multi-step process for identifying

BACM. Addendum at 42010-42014. The

steps are:

1. develop a detailed emissions

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

when it bears on the BACM

determination, and

4. provide for the implementation of

the BACM or provide a reasoned

justification for rejecting any potential

BACM.

B. 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.

6. the technological and economic

feasibility of various control measures.

We may grant only one extension for

an area and that extension cannot be for

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more than 5 years after 2001; that is, the

extended attainment date can be no later

than December 31, 2006. CAA section

188(e).

We first presented our preliminary

interpretation of the attainment date

extension provision in our proposed

approval of the annual standard

provisions in the MAG plan. See 66 FR

19992, 19967. Based on comments we

received on it during that proposal's

comment period, we have clarified

certain aspects of the policy but have

made no substantive changes to it. We

will provide our full response to

comments received on the annual

standard proposal when we take final

action.

This interpretation is our preliminary

view of the section 188(e) requirements

and we again request comment on it. We

emphasize that these are our

preliminary views and they are subject

to modification as we gain more

experience reviewing extension requests

from other areas.

In the following sections we discuss

the five requirements a State must meet

before we can consider granting an

attainment date extension.

1. Apply for an Attainment Date

Extension

Under CAA section 188(e), a State

must apply for an extension of the

attainment deadline. The request should

be accompanied by the SIP submittal

containing the most expeditious

alternative attainment date

demonstration required by CAA section

189(b)(1)(A)(ii). The state must be

provided the public with reasonable

notice and a hearing on the request

before it is sent to EPA.

Extension requests are not SIP

submittals per se 53 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 SIP, 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

53 This is clear from the wording of section 188(e)

which makes a distinction between the application

for an extension and the SIP revision that must

accompany it: "at the time of the such application,

the State must submit a revision to the

implementation plan that includes a demonstration

of attainment by the most expeditious alternative

date practicable." This attainment demonstration is

the one required by section 189(b)(1)(A)(ii).

that the implementation of BACM on

significant (that is, non-de minimis)

source categories will not bring the area

into attainment by December 31, 2001.

In serious areas, BACM is required to be

in place in advance of the 2001

attainment date; therefore, we believe

that it is reasonable to interpret the Act

to require that a state provide at least for

the implementation of BACM on

significant source categories before it

can claim impracticability of attainment

by 2001. 54 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 claim impracticability of

attainment by 1994, the moderate area

attainment date. See 57 FR 13498, 13544

(April 16, 1992). The Ober II court

found this approach reasonable. Ober II

at 1198.

The statutory provision for

demonstrating impracticability requires

that the demonstration be based on air

quality modeling. See section

189(b)(1)(A). We have established

minimum requirements for air quality

modeling. See discussion on air quality

modeling later in this TSD.

3. Have Complied With all

Requirements and Commitments in its

Implementation Plan

We interpret this criterion to mean

that the state has implemented the

emission reducing measures in the plan

revisions it has submitted to address the

CAA requirements in sections 172 and

189 for PM-10 nonattainment areas.

The purpose of this criterion is to

assure that a state is not receiving

additional time to attain because it

failed to implement already-adopted or

already-committed-to control measures.

Given this purpose, we believe our

review under this criterion should be

limited to the implementation status of

control measures from earlier PM-10

plans and not be an expansive review of

the implementation status of every

provision in submitted implementation

plans, whether or not it is an emission

reducing measure.

We read this provision not to require

the area to have a fully approved plan

that meets the CAA's requirements for

moderate areas. We base this reading on

the plain language of section 188(e)

54 As described in the section on the BACM

requirement, if applying BACM-level controls to

one or more of the proposed de minimis source

categories would result in attainment by December

31, 2001, then those categories are not de minimis

(i.e., they are significant) and must have BACM

applied to them. Therefore, states cannot use the de

minimis exemption to BACM to avoid applying

controls that would result in attainment by 2001.

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 or if the

area has failed to meet a RFP milestone.

Part of determining whether a state

has implemented its commitments and

requirements in earlier plans is

assessing whether the state retains the

legal authority for them and is funding,

staffing, and enforcing them at the level

assumed or committed to in those plans.

Thus any determination that the state

has met its commitments and

requirements in earlier plans is also a

finding that it has retained its legal

authority and has met its commitments

regarding enforcement, funding, and

staffing.

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 be feasibly 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 a

BACM-level of control 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 propose to define a "most

stringent measure" level of control 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 be

feasibly implemented in the area. A

MSM then is a control measure that

delivers this level of control.

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.

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Given this similarity between the

BACM requirement and the MSM

requirement, 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 to determine if the existing

measures are most stringent:

1. Develop a detailed emissions

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 as

necessary,

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 of any

MSM that is more stringent than

existing similar local measures and

provide for implementation as

expeditiously as practicable or, in lieu

of providing for adoption, provide a

reasoned justification for rejecting the

potential MSM, i.e., why such measures

cannot be feasibly implemented in the

area.

The MSM provision only requires that

a state consider the best controls from

elsewhere in the country for

implementation in the area requesting

an attainment date extension. It looks to

see-and the results are completely

dependent on-how well other areas

have controlled their PM-10 sources. If

other areas have not controlled a

particular source or source category

well, then the resulting level of control

from the MSM will not be the maximum

feasible level of control for that source

or source category in the local area.

Even if they have controlled them well,

the resulting level of control may still

not be the maximum feasible level

because local conditions may allow a

higher degree of control than has been

achieved elsewhere.

The MSM provision does not require

a state to consider if local sources or

source categories can be controlled at a

level greater than the most stringent

level from other areas. In other words,

it does not require states to determine

and adopt the maximum feasible level

of control that could be applied to a

source or a source category given local

conditions and the additional

implementation time afforded by an

extension.

In considering the MSM provision,

the inclination is to assume that there

are always better controls in other areas

than there are in the local area. This

assumption is unwarranted, especially

for areas that have already gone through

the process of identifying and adopting

BACM for their significant sources in

order to meet the section 189(b)(1)(B)

requirement. These areas are likely to

have already evaluated the best controls

from other areas and either adopted

them as BACM or rejected them as not

feasible for their area. As a result, the

likelihood of finding substantial new

controls during a MSM evaluation in

one of these areas is low. 5 5

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 the 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 request 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

55 There is also an inclination to assume that the

MSM requirement is the provision in section 188(e)

that implements the Act's general strategy of

offsetting longer attainment time frames with more

stringer control and therefore, the MSM

requirement must be interpreted to result in the

adoption of measures more stringent than BACM.

We believe, however, that this offsetting function is

actually served by the CAA section 189(b)(i)(A)(ii)

requirement for PM-10 plans to demonstrate

attainment by the most expeditious date

practicable, if attainment by 2001 is impracticable.

Because we are required to grant the shortest

possible extension, a state must demonstrate that it

has adopted the set of control measures that will

result in the most expeditious date practicable for

attainement. This requirement may very well

require that a state adopt controls that go beyond

the most stringent measures adopted or

implemented elsewhere.

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.

Like the RACM and BACM

requirements, there is no explicit

provision in the Act prohibiting an

exemption from the MSM requirement

for de minimis sources of PM-10

pollution. We are using here the same

principles for determining when a

source is considered de minimis under

the MSM requirement that we used for

the RACM requirement that the Ober II

court upheld and thus we have

constructed the de minimis exemption

for the MSM requirement to prevent

states from eliminating any controls on

sources or source categories that alone

or together would result in more

expeditious attainment of the PM-10

standards.

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

unless the emission benefit of the new

measure is substantially greater than the

existing measure.

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.

Judging stringency. The stringency of

a control measure is determined

primarily by a combination of its

applicability and its control

requirement, that is, who in the source

category is subject to the measure and

what does the measure requires them to

do to reduce emissions. When we use

the term "measure" in the context of the

MSM requirement, we are referring to

this combination; we are not referring to

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just the control requirement or to

individual methods of control.

The approach we propose to use in

evaluating the selection of the most

stringent among multiple measures, i.e.,

evaluating the determination of when

one control measure is more stringent

than another, is:

1. If there is only a single measure

applicable to a source category then we

will compare the measures directly. If

there are multiple control measures

with diverse controls requirements

applicable to a source category (e.g.,

tailpipe emissions are controlled

through fuels, emission standards,

inspection and maintenance programs,

and transportation control measures)

then we will compare measures with

similar control requirements against one

another. If several measures apply the

same or very similar control

requirements to a source category, that

is they have the same control

requirement but different applicablities

(e.g., MCESD Rule 310.01 and City and

County commitments all require similar

controls on unpaved roads), then will

use the collective stringency of all the

measures in the stringency analysis.

2. We will review all the provisions

of a rule that apply to a specific type of

source (e.g., all the rule provision that

apply to vacant lots) as an inseparable

measure. As discussed above a rule's

stringency is defined by a combination

of its applicability and control

requirements (as they apply to a single

type of source). They are not separable

elements that can be compared in

isolation to another rule. 5 6

3. In a MSM analysis, a measure's

stringency should be determined

assuming that it is appropriately

adopted, implemented and enforced.

Thus, we will not use a measure's

implementation mechanisms (e.g., rule

versus commitment), funding level,

compliance schedule, test method,

resources available for enforcement, or

other similar items as criteria for

judging relative stringency. 57

A state may determine which measure

or measures are most stringent either

56 For example, South Coast Rule 403 covers

vacant lots, construction sites, and agriculture

among other fugitive dust sources. MCESD's Rule

310.01 covers vacant lots and Rule 310 covers construction sites. The Arizona BMP rule covers agricultural sources. Under this test we would

evaluate Rule 403's provisions for vacant lots

against Rule 310.01 provisions for vacant lots; Rule

403's provisions for construction sites against Rule

310's provision for construction sites; Rule 403's

provisions for agricultural sources against the BMP

rule's ones.

57 However, once a State determines a measure is

a feasible most stringent measure, it must convert

the measure into a legally enforceable form and

provide the necessary level of resources, etc. to

ensure its implementation.

qualitatively or quantitatively. It is the

state's responsibility, however, to assure

that any determination is well

documented and persuasive.

Once a state has identified a potential

most stringent measure, it must provide

for the adoption of any MSM that is

more stringent than existing measures

and provide for implementation as

expeditiously as practicable or, in lieu

of providing for adoption, provide a

reasoned justification for rejecting the

potential MSM, i.e., why such measures

cannot be feasibly implemented in the

area.

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 indicates that Congress

granted us considerable discretion in

determining whether a plan in fact

provides for 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 and to

how we have interpreted the CAA's

other general control requirements,

RACM and BACM.

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 and to the

failure to include measures that could

provide for more expeditious attainment

and less weight to those measures for

source categories that contribute little to

the PM-10 problem and 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 by the most expeditious date

practicable using air quality modeling

after December 31, 2001. This

demonstration is the final criterion that

must be met before we may grant an

extension request.

There are two parts to reviewing a

modeled attainment demonstration:

evaluating the technical adequacy of the

modeling itself, and evaluating the

control measures that are relied on to

demonstrate attainment.

We have established technical

requirements for modeling PM-10 in

SIP attainment demonstrations. Please

see discussion later in this TSD on

modeling requirements for PM-10 SIPs.

In order to evaluate the control

measures relied on in the attainment

demonstration to determine if:

1. We have approved it into the SIP

or the State has submitted it to us for

approval into the SIP.

2. It is enforceable under our SIPenforceability standards or qualifies to

be credited under our mobile source

voluntary measures policy. 58

3. The plan provides reasonable

assurances, including funding and other

resource commitments, that it will be

implemented and enforced.

4. It will be implemented on the most

expedient schedule practicable.

5. The emission reductions credited to

it are reasonable and consistent with the

implementation resources and schedule,

and for any reductions coming from

mobile source voluntary measures, that

they do not collectively exceed 3

percent of the total reductions needed

for attainment. 59

Our determination of whether the

plan provides for attainment by the

most expeditious date practicable will

depend on whether we find that the

plan provides for appropriate BACM,

MSM, and any other technologically

and economically feasible measures that

will result in attainment as

expeditiously as practicable and that

these measures are implemented on an

expeditious schedule.

Please see section 3 of the EPA TSD

for additional discussion of our

proposed interpretation of the extension

requirements.

VI. 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. For this reason, this proposed

action is also not subject to Executive

Order 32111, "Actions Concerning

Regulations That Significantly Affect

Energy Supply, Distribution, or Use" (66

FR 28355, May 22, 2001). 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

53 Memorandum, Richard D. Wilson, Acting

Assistant Administrator for Air and Radiation, to

EPA Regional Administrators, 1-10, "Guidance on

Incorporating Voluntary Mobile Source Reduction

Programs in State Implementation Plans (SIPs),"

October 24, 1997.

59 Ibid., page 5.

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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 (Public Law 104-4). This rule

also does not have a substantial direct

effect on one or more Indian tribes, on

the relationship between the Federal

Government and Indian tribes, or on the

distribution of power and

responsibilities between the Federal

Government and Indian tribes, as

specified by Executive Order 13175 (65

FR 67249, November 9, 2000), nor will

it 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, EPA's

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), EPA has no authority

to disapprove a SIP submission for

failure to use VCS. It would thus be

inconsistent with applicable law for

EPA, when it reviews 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 note) do not apply. As required by

section 3 of Executive Order 12988 (61

FR 4729, February 7, 1996), in issuing

this proposed rule, EPA has taken the

necessary steps to eliminate drafting

errors and ambiguity, minimize

potential litigation, and provide a clear

legal standard for affected conduct. EPA

has 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: September 14, 2001.

Mike Schulz,

Acting Regional Administrator, Region IX.

[FR Doc. 01-24203 Filed 10-1-01; 8:45 am]

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