[Federal Register Volume 63, Number 148 (Monday, August 3, 1998)]
[Rules and Regulations]
[Pages 41326-41356]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-20147]



[[Page 41325]]

_______________________________________________________________________

Part II





Environmental Protection Agency





_______________________________________________________________________



40 CFR Part 52



Promulgation of Federal Implementation Plan for Arizona; Phoenix PM-10 
Moderate Area; Disapproval of State Implementation Plan for Arizona; 
Phoenix PM-10 Moderate Area; Final Rule

  Federal Register / Vol. 63, No. 148 / Monday, August 3, 1998 / Rules 
and Regulations  

[[Page 41326]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[FRL-6131-6]
RIN 2060-ZA02


Promulgation of Federal Implementation Plan for Arizona--Phoenix 
PM-10 Moderate Area; Disapproval of State Implementation Plan for 
Arizona--Phoenix PM-10 Moderate Area

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: Under the authority of section 110(c)(1) of the Clean Air Act 
(CAA or ``the Act''), EPA is today promulgating a federal 
implementation plan (FIP) to address the moderate area PM-10 
requirements for the Phoenix PM-10 nonattainment area. Specifically, 
for both the annual and 24-hour PM-10 standards, EPA is promulgating a 
demonstration that reasonably available control measures (RACM) will be 
implemented as soon as possible, a demonstration that it is 
impracticable for the area to attain the standards by the statutory 
attainment deadline and a demonstration that reasonable further 
progress (RFP) is being met.
    As part of the FIP, EPA is promulgating a fugitive dust rule to 
control PM-10 emissions from vacant lots, unpaved parking lots and 
unpaved roads, and is also promulgating an enforceable commitment to 
ensure that RACM for agricultural sources will be proposed by September 
1999, finalized by April 2000 and implemented by June 2000.
    In addition, EPA is today finalizing its disapproval of the Arizona 
moderate area plan's RACM, RFP and impracticability, demonstrations 
because those demonstrations do not adequately address the Act's 
moderate area PM-10 requirements.
    EPA recently established a new standard for PM-2.5 and also revised 
the PM-10 standards; however, today's action does not address those 
standards.

EFFECTIVE DATES: The FIP and SIP actions in this document are effective 
on September 2, 1998.

ADDRESSES: A copy of the docket no. A-09-98, containing material 
relevant to EPA's proposed and final actions, is available for review 
at: EPA Region 9, Air Division, 75 Hawthorne Street, San Francisco, 
California 94105. Interested persons may make an appointment with 
Eleanor Kaplan (415) 744-1159 to inspect the docket at EPA's San 
Francisco office on weekdays between 9 a.m. and 4 p.m.
    A copy of the docket no. A-09-98 is also available to review at the 
Arizona Department of Environmental Quality, Library, 3033 N. Central 
Avenue, Phoenix, Arizona 85012, (602) 207-2217, and at the EPA Air 
Docket Section, Waterside Mall, Room M-1500, 401 M Street, S.W., 
Washington, D.C. 20460, (202) 260-7549.

FOR FURTHER INFORMATION CONTACT: For questions and issues regarding the 
final measure for agricultural fields and aprons contact John Ungvarsky 
(415) 744-1286; for questions and issues regarding the final rule for 
unpaved parking lots, unpaved roads and vacant lots contact Karen Irwin 
(415) 744-1903; and for other general FIP and SIP questions and issues 
contact Doris Lo (415) 744-1287.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary
    A. Background
    B. Public Involvement in the FIP Process
    C. The Final FIP
II. Background
    A. SIP/FIP Background
    B. Summary of SIP/FIP Proposal
III. Disapproval of Arizona's Moderate Area PM-10 Plan
IV. Final FIP
    A. RACM/RACT Demonstration
    1. RACT and PM-10 Precursors
    2. RACM Demonstration
    B. FIP Measures
    1. Commitment for Agricultural Sector
    2. Rule for Unpaved Parking Lots, Unpaved Roads and Vacant Lots
    a. Background
    b. Summary of Changes to the Proposed FIP Rule
    c. Public Comments and EPA Responses
    C. Impracticability Demonstration
    1. Annual Standard
    2. 24-hour Standard
    D. Reasonable Further Progress Demonstrations
    1. Revised RFP Demonstration
    a. Annual Standard
    b. 24-hour Standard
    i. Gilbert Monitoring Site
    ii. West Chandler Monitoring Site
    2. Response to Comments on RFP Demonstrations
    E. Indian Reservations
V. Administrative Requirements
    A. Executive Order (E.O.) 12866
    B. Regulatory Flexibility Act Analysis
    1. Regulatory Flexibility Act Requirements
    2. RFA Analysis
    a. Federal Rule for Unpaved Roads, Unpaved Parking Lots and 
Vacant Lots
    b. Federal Commitment for Agriculture c. Certification
    C. Unfunded Mandates Reform Act (UMRA)
    D. Paperwork Reduction Act (PRA)
    E. Executive Order 13045: Protection of Children from 
Environmental Health Risks and Safety Risks
    F. Submission to Congress and the General Accounting Office
    G. Petitions for Judicial Review

I. Executive Summary

A. Background

    The Phoenix area violates both the annual and 24-hour national air 
quality standards for particulate matter with diameters of 10 microns 
or less (PM-10). Particulate matter affects the respiratory system and 
can cause damage to lung tissue and premature death. The elderly, 
children, and people with chronic lung disease, influenza, or asthma 
are especially sensitive to high levels of particulate matter. EPA 
recently established a new standard for particulate matter with 
diameters of 2.5 microns or less and revised the PM-10 standards. 
However, EPA also retained the pre-existing PM-10 standards for a 
limited amount of time. Today's action only addresses those pre-
existing PM-10 standards.
    The primary cause of the PM-10 problem in the Phoenix area is dust 
on paved roads kicked up by vehicle traffic, and windblown dust from 
construction sites, earth moving operations, unpaved parking lots and 
roads, disturbed vacant lots, agricultural fields and aprons, and other 
disturbed areas.
    When an area violates an air quality standard, the Clean Air Act 
(CAA) requires that the area be designated as nonattainment for that 
pollutant. Phoenix was originally designated and classified as a 
moderate nonattainment area for particulate matter, and Arizona was 
required to develop a plan that put into place a basic set of control 
measures. These measures did not adequately control the particulate 
pollution problem. When the area failed to attain the standards in 1994 
it was reclassified as a serious nonattainment area, and the State is 
now required to develop a plan with more comprehensive control 
measures.
    Despite the fact that the State is now working on its serious area 
plan, EPA is under court order, as a result of a lawsuit by the Arizona 
Center for Law in the Public Interest (ACLPI), to develop a moderate 
area federal implementation plan (FIP) for the Maricopa area. EPA is 
required to prepare this FIP because the State does not have an 
approved moderate area plan. Under the court order, EPA was required to 
issue the FIP by July 18, 1998.
    In its FIP proposal (63 FR 15920; April 1, 1998), EPA determined 
that not all the basic controls on sources contributing to violations 
of the particulate standards were in place. While the State had 
implemented a

[[Page 41327]]

number of measures, including controls on construction and earth moving 
operations, there remained a need for additional emissions reductions. 
Having considered its authority and resource constraints, EPA proposed 
two measures in that rulemaking for the control of dust from unpaved 
roads, parking lots, and vacant lots and agricultural fields and 
aprons. Specifically, EPA proposed a fugitive dust rule and an 
enforceable commitment in regulatory form to implement control measures 
for agricultural PM-10 sources by June 2000. These measures will 
contribute to the eventual attainment of both the annual and 24-hour 
PM-10 standards. EPA received comments from the public on the FIP 
proposal and has made changes to the proposed FIP rule for fugitive 
dust sources that it is finalizing today.
    The State now intends to submit its serious area particulate plan 
in December of 1998. If the plan includes control measures for the 
sources covered by the FIP and those measures are approved by EPA, the 
Agency will be able to withdraw the final FIP measures. EPA will 
continue working with the appropriate State and local agencies, as well 
as the agricultural community and the cities in the metropolitan area, 
to replace the FIP measures with State measures. EPA believes that 
clean air is likely to be achieved faster, and in greater harmony with 
local economic and community goals, if its role as a backstop is 
minimized by effective State and local actions. Because of the 
willingness of the State and local communities to identify and pursue 
solutions to their air quality problems, as evidenced by the Governor's 
Air Quality Strategies Task Force and the recently adopted Air Quality 
Measures Bill (SB 1427), EPA expects successful State and local action.

B. Public Involvement in the FIP Process

    On April 16, 1998, EPA held a workshop and public hearing on its 
proposal in Phoenix. The workshop provided an opportunity for EPA to 
explain to the community why the Agency is imposing this FIP, what 
measures are included in the FIP, and who will potentially be impacted 
by the FIP. The workshop also provided the community the opportunity to 
ask questions of EPA, and to make suggestions with respect to its 
proposed action. Following the workshop, EPA took formal testimony at a 
public hearing on the FIP proposal. In addition to the hearing 
testimony, EPA received 18 comment letters on the proposed FIP.
    The comments generally fell into two categories. Environmental and 
health organizations supported the dust rule, but commented that the 
FIP did not impose enough PM-10 controls for other source categories in 
the Phoenix PM-10 nonattainment area. On the other hand, several of the 
local jurisdictions and regulatory agencies commented that the FIP-
imposed controls were too stringent. EPA evaluated all the comments, 
did additional fieldwork and technical analysis, and revised the FIP 
accordingly.

C. The Final FIP

    In response to public comments, EPA revised the fugitive dust rule, 
but did not change the enforceable commitment for agriculture.
Fugitive Dust Rule
    Although EPA has approved a Maricopa County rule (MCESD Rule 310) 
which requires controls for unpaved roads, unpaved parking lots and 
vacant lots, the County is not adequately enforcing its rule for these 
three sources due to lack of resources. Consequently, EPA promulgated a 
FIP rule for these sources. EPA's fugitive dust rule is intended to 
establish basic levels of control that are substantially equivalent to 
those established by Maricopa County Rule 310. The primary difference 
between the FIP rule and Rule 310 is the greater specificity and detail 
regarding which control measures are appropriate for which sources. For 
each source category, the FIP rule includes three to four control 
measure options and allows alternative control measures.
    In order to effectively implement the FIP rule, EPA is providing 
additional inspection resources to the Maricopa County Environmental 
Services Department (MCESD) through a CAA section 105 grant. EPA will 
rely on these resources to assist the Agency in verifying compliance 
with the FIP rule. In order to remove the FIP requirement, MCESD will 
have to submit to EPA a credible implementation strategy for Rule 310, 
including the provision of its own additional inspection and 
enforcement resources that are not provided under an EPA grant. It is 
EPA's understanding that MCESD is trying to obtain these additional 
resources. EPA will continue working with the County to assist that 
effort so that the FIP rule can eventually be rescinded.
    Until the FIP is rescinded, however, EPA intends to work 
cooperatively with MCESD to inform the regulated community of the FIP 
rule's requirements. EPA plans to provide compliance assistance through 
informational brochures, toll free numbers and internet access. These 
tools will help EPA disseminate as much information as possible to the 
public. As new information becomes available, including alternative 
control measures that are being developed by regulated parties to 
comply with the rule, EPA will collaboratively work with these 
regulated parties to provide information to the public.
    EPA would like to clarify the Agency's position with respect to a 
major issue that was raised by several commenters on the proposed 
fugitive dust rule. These commenters believe that the FIP rule requires 
a more stringent level of control than Maricopa County Rule 310 and 
that, consequently, EPA is imposing an additional economic burden on 
local municipalities, and others impacted by the FIP rule. EPA believes 
that the FIP rule does not impose any additional compliance burden 
beyond that required by Rule 310. Because EPA will fully enforce the 
FIP rule, which has not occurred under Rule 310, regulated entities who 
have not been in compliance with existing requirements to date will 
need to spend the resources necessary to come into compliance. This is 
not an additional economic burden, but rather one that some members of 
the regulated community have deferred. However, should EPA receive new 
information in the future that indicates that the FIP controls are more 
stringent than those required by the Clean Air Act, the Agency will 
propose appropriate revisions to the FIP.
Enforceable Commitment for Agriculture
    As mentioned above, EPA has approved Maricopa County Rule 310 which 
requires control of fugitive dust sources, including agricultural 
sources. However, MCESD is not ensuring adequate enforcement of the 
rule for agricultural fields and aprons. Therefore, EPA is promulgating 
an enforceable commitment in regulatory form for the FIP that requires 
EPA to propose controls on agricultural sources by September 1999 and 
implement these controls by June 2000. The enforceable commitment has 
not changed from the April 1, 1998 proposal. In discussions with key 
stakeholders, general agreement was reached that these controls will be 
in the form of best management practices. EPA believes that this 
approach will ensure successful dust control in Maricopa's unique 
environment. We have worked closely with the Phoenix

[[Page 41328]]

farming community to develop this commitment, and their comments on the 
proposal support it.
    In order to remove the FIP requirements, the State will need to 
submit and receive approval of a SIP measure that replaces the 
enforceable commitment. In fact, the Arizona legislature has passed, 
and Governor Hull has signed, the legislative language needed to 
establish a state process to develop best management practices for 
control of PM-10. EPA expects to receive this legislative language as a 
SIP revision very shortly and will act on it expeditiously.
Tribal Issues
    There are three Indian reservations located within the Phoenix 
nonattainment area. However, since this FIP is designed to fill a gap 
that exists in the State plan which does not apply to sources within 
Indian country, EPA has not included Indian reservations in this FIP. 
All three tribes have expressed an interest in developing air quality 
programs. EPA will develop the data, in cooperation with the tribes, 
that is needed to properly assess whether controls are required to 
attain the standards. EPA will ensure that controls are implemented 
either through EPA-approved tribal measures or, if necessary, federal 
measures.
Conclusion
    EPA appreciates the comments that were made on the proposed FIP and 
will continue to work with the community as the Agency moves forward to 
implement the FIP measures. EPA will also continue to work with the 
community on the development of the State's serious area plan. EPA is 
hopeful that the local planning effort will result in an approvable SIP 
that will allow EPA to withdraw its FIP.

II. Background

A. SIP/FIP Background

    Today's federal implementation plan (FIP) is the result of over six 
years of planning and litigation regarding the control of PM-10 
emissions in the Phoenix area. On November 15, 1991, as required by the 
CAA, the State of Arizona submitted to EPA a moderate area PM-10 state 
implementation plan (SIP). EPA found that plan to be incomplete and, as 
a result, the State revised and resubmitted it on March 3, 1994. On 
April 10, 1995, EPA approved the revised plan which included reasonably 
available control measure (RACM) and reasonable further progress (RFP) 
demonstrations, and a demonstration that it was impracticable for the 
Phoenix area to attain the PM-10 national ambient air quality standards 
(NAAQS) by the statutory deadline of December 31, 1994.
    On May 1, 1996, the Arizona Center for Law in the Public Interest 
(ACLPI) filed in the United States Court of Appeals for the Ninth 
Circuit a petition for review of EPA's April 10, 1995 approval of the 
State's PM-10 moderate area plan. On May 14, 1996, the Ninth Circuit 
vacated EPA's approval of the plan for failing to adequately address 
the moderate area PM-10 requirements. Ober v. EPA, 84 F.3d 304 (9th 
Cir. 1996). Specifically, the Ninth Circuit found that the State's plan 
failed to meet the CAA's requirements for attainment, RFP and RACM for 
the 24-hour PM-10 standard and that EPA had failed to provide a 
sufficient opportunity for public comment on the RFP and RACM 
demonstrations for the annual PM-10 standard.
    As a result of the Ninth Circuit's ruling, EPA instructed the State 
of Arizona to submit by May 9, 1997 a plan addressing the Act's 
moderate area requirements for the 24-hour PM-10 standard at certain 
specified monitoring sites and to submit, by December 10, 1997, a full 
regional plan addressing those requirements for both the 24-hour and 
annual PM-10 standards.1
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    \1\ As a result of the litigation and the reclassification of 
the Phoenix area as a serious PM-10 nonattainment area, both plans 
were also required to address the best available control measure 
(BACM), RFP and attainment requirements in the CAA for serious 
areas.
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    Arizona submitted its 24-hour plan 2 (known as the 
microscale plan) on May 9, 1997. On August 4, 1997, EPA approved the 
microscale plan in part and disapproved it in part. 62 FR 41856. The 
State has not yet submitted the full regional plan, but has indicated 
that it intends to do so in December 1998.
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    \2\ Plan for Attainment of the 24-Hour PM-10 Standard, Maricopa 
County PM-10 Nonattainment Area, Final. ADEQ, May 1997.
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    Because EPA was unable to fully approve the State's microscale 
plan, the Agency is required by a U.S. District Court order to 
promulgate a FIP by July 18, 1998 that addresses the CAA's moderate 
area requirements for RACM, RFP and attainment for both the 24-hour and 
annual standards. Ober v. Browner, CIV 94-1318 PHX PGR (D. 
Ariz.).3
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    \3\ The Arizona Center for Law In the Public Interest (ACLPI), 
representing the plaintiffs in Ober, in a comment on the FIP 
proposal, contends that the proposed FIP does not contain 
contingency measures as required by section 172(c)(9) of the CAA. 
EPA disagrees. In today's final FIP, EPA is fulfilling an obligation 
under the consent decree in the district court Ober case that 
specifically requires the Agency to promulgate a federal plan for 
Phoenix that meets the moderate area RACM requirement in CAA section 
189(a)(1)(C), RFP requirement in section 172(c)(2) or 189(c)(1), and 
attainment requirement in section 189(a)(1)(B) of the Clean Air Act. 
See paragraph 6 of the Modified Second Consent Decree. EPA's 
obligation under the Ober decree does not extend to the section 
172(c)(9) contingency measures. The section 172(c)(9) contingency 
measure requirement is a separate and distinct statutory requirement 
and is not an integral part of RFP or attainment demonstrations 
under part D of the CAA. See, e.g., 57 FR 13498, 13543 (April 16, 
1992) and 61 FR 51599, 51607 (October 6, 1996). See also footnote 1 
in EPA's orginal proposed approval of the State moderate area PM-10 
plan for the Phoenix area, 59 FR 38402 (July 28, 1994).
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B. Summary of SIP/FIP Proposal

    On April 1, 1998, EPA proposed a FIP for the Phoenix PM-10 
nonattainment area that was published in the Federal Register at 63 FR 
15920. The proposed FIP included a demonstration that all RACM are 
being implemented, a demonstration that it is impracticable to attain 
the PM-10 standards with the implementation of all RACM and a 
demonstration that RFP in emissions reductions is being made.
    As part of its proposed RACM demonstration, EPA proposed a fugitive 
dust rule to control PM-10 emissions from vacant lots, unpaved parking 
lots and unpaved roads, and an enforceable commitment to ensure that 
RACM for agricultural sources will be proposed by September 1999, 
finalized by April 2000 and implemented by June 2000. Further detail on 
the proposed rule and commitment is provided in connection with the 
discussion of EPA's final actions in section IV. below and in the 
proposed rulemaking at 63 FR 15920, 15935.
    On April 1, 1998, EPA also withdrew a 1996 proposed action to 
restore its approval of portions of the State's moderate area SIP for 
the annual standard and proposed to disapprove the RACM and 
impracticability demonstrations in Arizona's moderate area plan because 
those demonstrations do not adequately address the Act's moderate area 
PM-10 requirements. Further discussion of the SIP actions is provided 
in section III. below and in the proposed rulemaking at 63 FR 15920, 
15925.
    EPA received 18 public comment letters from a wide range of parties 
including private citizens, state and local agencies, industry 
representatives, and environmentalists. EPA also held a public hearing 
on the proposed FIP in Phoenix at which 7 groups or individuals 
testified. Copies of the comment letters and the transcript of the 
public hearing can be found in the docket for this rulemaking.

[[Page 41329]]

III. Disapproval of Arizona's Moderate Area PM-10 Plan

    In its proposed action for this rulemaking, EPA withdrew its 
earlier proposal at 61 FR 54972 (October 23, 1996) to restore the 
Agency's approval of Arizona's moderate area PM-10 plan for the Phoenix 
nonattainment area.4 At the same time, EPA proposed to 
disapprove the RACM demonstration and the demonstration that attainment 
by the moderate area attainment deadline was impracticable in the 
State's moderate area plan. See 63 FR 15920, 15925-15926. EPA is today 
taking final action to disapprove that plan.
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    \4\ EPA received one public comment from ACLPI which supported 
EPA's withdrawal of its prior proposal to restore the approval of 
the State's moderate area SIP as well as the RACM and 
impracticability demonstrations therein.
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    The CAA establishes specific consequences if EPA finds that a state 
has failed to meet certain requirements of the CAA. Of particular 
relevance here is CAA section 179(a)(1), the mandatory sanctions 
provision. Section 179(a) sets forth four findings that form the basis 
for application of a sanction, including disapproval by EPA of a 
State's submission based on its failure to meet one or more required 
CAA elements. EPA has issued a regulation, codified at 40 CFR 51.31, 
interpreting the application of sanctions under section 179 (a) and 
(b).
    Generally, if EPA has not approved a revised SIP revision 
correcting the deficiency, within 18 months of the effective date of 
today's rulemaking, pursuant to CAA section 179(a) and 40 CFR 52.31, 
the offset sanction identified in CAA section 179(b) will be applied in 
the affected area. Similarly, if EPA has still not approved a SIP 
revision correcting the deficiency 6 months after the offset sanction 
is imposed, then the highway funding sanction will apply in the 
affected area, in accordance with 40 CFR 52.31.5 In 
addition, CAA section 110(c)(1) provides that EPA must promulgate a FIP 
no later than 2 years after a finding under section 179(a) unless EPA 
takes final action to approve the revised plan correcting the 
deficiency within 2 years of EPA's findings.
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    \5\ In a 1994 rulemaking, EPA established the Agency's selection 
of the sequence of these two sanctions: the offset sanction under 
section 179(b)(2) shall apply at 18 months, followed 6 months later 
by the highway sanction under section 179(b)(1) of the Act. EPA does 
not choose to deviate from this presumptive sequence in this 
instance. For more details on the timing and implementation of the 
sanctions, see 59 FR 39859 (August 4, 1994), promulgating 40 CFR 
52.31, ``Selection of sequence of mandatory sanctions for findings 
made pursuant to section 179 of the Clean Air Act.''
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    There are, however, certain exceptions to the general rule for the 
application of sanctions described above. The reader is referred to 40 
CFR 52.31(d) for the circumstances under which the application of 
sanctions may be stayed or deferred.

IV. Final FIP

A. RACM/RACT Demonstration

1. RACT and PM-10 Precursors
    In its proposed rulemaking, EPA determined that the SIP already 
included reasonably available control technology (RACT) for major 
sources of PM-10 and that the FIP did not need to further address this 
requirement. See 63 FR 15920, 15927. No comments were received on this 
determination.
    EPA also proposed to find, based on existing modeling, that major 
stationary sources of PM-10 precursors do not contribute significantly 
to PM-10 levels in the Maricopa area which exceed the PM-10 air quality 
standards, and therefore, RACT on these major sources is not required 
under CAA section 189(e). See 63 FR 15920, 15928. Under CAA section 
189(e), the control requirements applicable to major stationary sources 
of PM-10 must also be applied to major stationary sources of PM-10 
precursors, unless EPA determines such sources do not contribute 
significantly to PM-10 levels in excess of the standards in the area. 
EPA received one comment, addressed below, on this proposed finding.
    Comment: ACLPI asserts that EPA's proposal to waive the RACT 
requirement for major sources of PM-10 precursors on the ground that 
such sources do not significantly contribute to PM-10 levels is flawed 
because: (1) it is based on unapproved, draft modeling; (2) it is based 
on the unsupported and unwarranted assumption that major source 
contributions to secondary particulate levels are proportional to their 
presence in the inventory; and (3) it is based on the use of 
``significance'' levels from the Act's new source review program, which 
are not automatically transferrable to determinations under CAA section 
189(e).
    Response: EPA used the State's modeling as the technical basis for 
this FIP. As such, the modeling was subject to public comment as part 
of the FIP proposal and did not require a prior CAA section 110(k) 
approval for EPA to use it.
    Given the very small presence of major stationary sources in the 
precursor inventory (less than 7 percent of the entire precursor 
inventory is from major stationary sources), assuming a linear 
relationship between major stationary source emissions and their impact 
on ambient secondary concentrations is reasonable. EPA estimated that 
major stationary sources contribute 0.6 g/m\3\ to exceedances 
of the 24-hour standard and 0.3 g/m\3\ to exceedances of the 
annual standard, so even if major stationary sources contribute to 
secondary particulate formation at 2 to 3 times their presence in the 
inventory, they would still be an insignificant source of PM-10 in the 
Maricopa area.
    The use of significance levels from the new source review program 
to determine if a source contributes significantly to PM-10 levels in 
excess of the air quality standards in the Phoenix area is discussed in 
the next section.
2. RACM Demonstration
    In order to determine which RACM to include in the FIP, EPA first 
identified a list of 99 potential control measures. See Table 1 in the 
proposed rulemaking (63 FR 15920, 15929). This list of measures was 
taken from the list of measures developed for the State's 1991 moderate 
area plan and included the measures found in EPA's guidance 
6 as well as measures recommended by the Maricopa air 
agencies and in public comments on the State's moderate area SIP. Nine 
additional potential measures were recommended during the public 
comment period on FIP: the California Air Resources Board's diesel fuel 
standards, a mandatory roadside testing program for diesels, enhanced 
diesel inspection and maintenance (I/M), accelerated replacement/
retrofit of pre-1988 heavy duty diesel commercial vehicles, retrofit 
existing diesel vehicles (for example, with catalysts), California's 
off-road vehicle and engine standards, California's low emission 
vehicle standards, continuing expansion of the enforcement of Rule 310, 
and a smoking vehicle identification and repair program. See Letter, 
ACLPI to EPA, Region 9, May 18, 1998, p. 4 and Public Hearing to 
Comment on the Proposed FIP, Reporter's Transcript of Proceedings, p. 
7-10 (12:00 p.m. session), p. 5-9 (7:00 p.m. session). EPA added these 
nine additional measures to its list of 99, for a total of 108 
potential measures.
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    \6\ See 57 FR 18070, 18072 (Appendix C) (April 28, 1992).
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    Before evaluating the measures as RACM, EPA screened the list to 
determine which measures were applicable to the Phoenix area and for 
which EPA had legal authority. EPA then screened the list to determine

[[Page 41330]]

which measures it has already approved as State RACM or adopted at the 
federal level and considers RACM. Where EPA had already determined a 
measure to be RACM, no further analysis of the measure was necessary. 
Finally, the Agency evaluated the resulting shorter list of measures 
based on EPA's RACM criteria 7 to identify which measures 
constituted RACM for the Phoenix area. These three criteria are de 
minimis source category, technical feasibility (including when the 
measure could be implemented), and cost of implementation. For any RACM 
rejected for reasons of technology, cost, size of source category or 
timing of implementation, the Agency provided a reasoned justification. 
In all, eleven measures addressing fugitive dust from unpaved roads, 
unpaved parking lots, disturbed cleared land, and agriculture remained 
after the application of the RACM criteria.8
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    \7\ See 57 FR 13498, 13540 (April 16, 1992).
    \8\ Seven of the additional measures proposed in public comment 
are controls for diesel or gasoline on-road tailpipe emissions. 
Because diesel and gasoline tailpipe emissions are de minimis source 
categories for purposes of PM-10 RACM in Maricopa County, EPA has 
determined that the seven measures do not constitute RACM for the 
Phoenix area. One measure, California's non-road engine standards, 
would control non-road engine emissions. As noted in the RACM 
Technical Support Document (TSD) for the proposal (p. 8), EPA 
promulgated non-road engine standards in 1995 and considers these 
national standards to be RACM. Because RACM has already been adopted 
for this category, EPA does not need to further evaluate measures, 
such as the California standards, for this category. See 63 FR 
15920, 15929. Because the FIP rule controls the same sources as Rule 
310, it effectively operates to expand enforcement of the rule.
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    A complete description of EPA's approach to determining RACM can be 
found in the proposed rulemaking at 63 FR 15920, 15928. The results of 
the initial RACM evaluation are presented in Table 3 of the proposed 
rulemaking. See 63 FR 15920, 15933. The results of the final RACM 
evaluation and a detailed evaluation of each measure including the 
reasoned justification if the measure was rejected is in the final RACM 
TSD.
    EPA received several comments on the RACM demonstration and 
responds to the most significant below. EPA has responded to all 
comments in the TSD.
    Comment: ACLPI comments that the Center disagrees with EPA's 
proposal for exempting de minimis source categories from the RACM 
requirement of the CAA. ACLPI asserts that there is no authority in the 
Act for such an exemption, and that EPA's position that de minimis 
source categories need only be controlled to the level necessary to 
produce RFP and timely attainment illegally reads the RACM requirement 
out of the Act as to such sources.
    Response: The CAA does not define ``reasonably available control 
measure.'' Because the statute is silent, EPA has the discretion to 
develop a reasonable interpretation. Chevron U.S.A. Inc. v. NRDC, 467 
U.S. 837, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984). In 1992 preliminary 
guidance (General Preamble), EPA set forth the criteria for states to 
apply in determining RACM and reasonably available control technology 
(RACT) in PM-10 moderate area SIPs. Among other criteria, if a state 
could show that a measure was unreasonable because the emissions from 
the affected source would be insignificant, i.e., de minimis, such a 
measure could be excluded from further consideration. See 57 FR 13498, 
13540. Moreover, EPA believes that determining the reasonableness of a 
measure based on the degree to which the regulated source contributes 
to the problem is consistent with the RACM/RACT requirements of CAA 
sections 189(a)(1)(C) and 172(c)(1). Additionally, RACT is generally 
only required for major point sources; i.e., sources above a certain 
size threshold. See, for example, section 182(b)(2). See 57 FR 13498, 
13541 for discussion of EPA's historical definition of RACT.
    In developing its federal plan for the Phoenix area, EPA applied 
this criterion by defining a reasonably available measure, in part, as 
one that applies to a source that significantly contributes to PM-10 
exceedances. See 63 FR 15920, 15927. In discussing the de minimis 
criterion in its proposed rulemaking, EPA noted that the regulatory 
scheme for particulate matter in subpart 4 of the CAA establishes two 
graduated levels of controls, RACM and BACM, depending on the severity 
of the area's air quality. See CAA section 189(a) and (b). These 
statutory requirements, applicable to moderate and serious PM-10 areas, 
respectively, clearly contemplate that sources that contribute to a 
lesser degree to the particulate matter problem need not, in the first 
instance, bear the burden of emission reductions. Thus, in determining 
the initial level of control, EPA believes that it is appropriate to 
focus on the reasonable and practicable measures for reducing PM-10 
emissions from those sources identified through air quality modeling as 
contributing to a greater degree, i.e., significantly, to PM-10 
exceedances in the Phoenix area.
    Alternatively, even absent EPA's discretionary authority to develop 
reasonable interpretations in the face of statutory silence, as stated 
in the General Preamble, the inherent authority of administrative 
agencies to exempt de minimis situations from a statutory requirement 
has been upheld in contexts where an agency is invoking a de minimis 
exemption as ``a tool to be used in implementing the legislative design 
when ``the burdens of regulation yield a gain of trivial or no value.'' 
Alabama Power Co. v. Costle, 636 F.2d 323, 360-61 (D.C. Cir. 1979). See 
57 FR 13498, 13540. As noted in EPA's response to the comment below, 
the provision of RACM for the source categories for which measures were 
rejected because of de minimis emissions would have little impact on 
the nonattainment problem in the Phoenix area.
    Because the Act can reasonably be interpreted to allow the use of a 
de minimis criterion for judging whether a measure is RACM, EPA does 
not believe that its interpretation that de minimis source categories 
need only be controlled to the level necessary to produce RFP and 
timely attainment results in reading the RACM requirement out of the 
Act as to such sources.
    Comment: ACLPI further claims that EPA's de minimis exemption is 
contrary to the Act's emphasis on timely attainment and protection of 
health, and that control of a source category contributing de minimis 
amounts could make the difference between attainment and nonattainment. 
Therefore, ACLPI asserts that it is irrational for EPA to assert that 
such source categories are invariably de minimis.
    Response: For PM-10, EPA has not determined that a given source's 
or source category's emissions impact is invariably de minimis for 
determining RACM. What constitutes a de minimis source category is 
dependent upon specific facts of the nonattainment problem under 
consideration. In particular, it depends upon whether requiring the 
application of RACM for such sources or source categories would 
contribute significantly to the Act's purpose of achieving attainment 
of the NAAQS as expeditiously as practicable.
    For the Phoenix PM-10 nonattainment problem, the subject of this 
FIP, controls on the source categories that EPA found to be de minimis 
would not make the difference between attainment and nonattainment. 
Five Phoenix area monitoring sites with expected PM-10 exceedances were 
evaluated to determine which source categories were de minimis for the 
purpose of the RACM demonstration in this FIP: four sites for the 24-
hour standard and one site for the annual standard. In order to be 
considered a de minimis source category in the FIP's RACM analysis, a 
source category had to be de minimis at all five monitoring

[[Page 41331]]

sites and de minimis for both the 24-hour and annual standards. As 
illustrated in Table 1, three of the five evaluated monitoring sites 
did not have de minimis sources identified as contributing anything to 
the exceedance. At the two remaining sites--Greenwood and Salt River--
de minimis source categories contribute substantially less than 10 
percent to the exceedance and in neither case would complete 
elimination of these sources result in attainment at the 
site.9 Hence in Phoenix, the use of a de minimis source 
category criterion to judge the reasonableness of controls has not 
excused controls on sources that would make the difference between 
attainment and nonattainment.
---------------------------------------------------------------------------

    \9\ EPA has already approved the attainment demonstration for 
the Salt River monitor. See 62 FR 41856, 41862 (August 4, 1997). 
This attainment demonstration showed that controls on the de minimis 
source categories would not result in more expeditious attainment.

   Table 1.--Contribution of De Minimis Sources to Exceedances in the   
                        Phoenix Metropolitan Area                       
------------------------------------------------------------------------
                                                                   De   
                                                    De Minimis   Minimis
                                                      sources    sources
                                                      without    without
                      Monitor                         RACM as    RACM as
                                                    percent of   percent
                                                    exceedance  of PM-10
                                                                standard
------------------------------------------------------------------------
24-Hour Exceedances:                                                    
  West Chandler...................................        0          0  
  Gilbert.........................................        0          0  
  Maryvale........................................        0          0  
  Salt River......................................        3.9        4.3
Annual Exceedances:                                                     
  Greenwood.......................................        4.7        5.6
------------------------------------------------------------------------

    Comment: ACLPI claims that EPA's choice of 5 g/m\3\ and 1 
g/m\3\ as the significance thresholds for contributors to 24-
hour and annual PM-10 levels respectively has no rational basis 
whatsoever and that the fact that EPA uses these thresholds in the new 
source review programs does not make them logical choices as thresholds 
for an entirely different purpose.
    Response: As stated in the proposal, EPA is relying on the new 
source review permitting program's significance thresholds ``as a 
surrogate for determining which source categories require application 
of RACM'', and ``not for determining which source categories need 
controls for attainment.'' 63 FR 15920, 15927. The new source review 
program and nonattainment planning provisions are both elements in the 
CAA's title I provisions to attain and maintain the health-based air 
quality standards. The new source review program's significance levels 
are used to judge when a source will have a significant impact on a PM-
10 nonattainment area. See 40 CFR 51.165(b). For the purposes of this 
FIP only, EPA used the 5 g/m\3\ and 1 g/m\3\ 
significance thresholds for essentially the same purpose: to judge 
whether a source or source category has a significant impact on the 
Phoenix PM-10 nonattainment area.
    A significance threshold should be set at a level that segregates 
the insignificant source categories from the ones that contribute most 
to a nonattainment problem. As noted above in Table 1, in Phoenix, de 
minimis sources, i.e., those that contribute less than 5 g/
m\3\ to the 24-hour standard exceedances and 1 g/m\3\ to the 
annual standard exceedances, account in total for less than 10 percent 
of the impact at any monitor that exceeds either PM-10 standard. Thus, 
because the selected thresholds result in the imposition of controls on 
the sources that have a greater emissions impact on the air quality 
problem, their application, in EPA's view, is most likely to result in 
substantial air quality improvements.
    There were 12 source categories that fell beneath these surrogate 
significance thresholds and which EPA determined, therefore, were de 
minimis in the proposed FIP's RACM analysis: industrial yards, surface 
mining, other industrial activities, gasoline-powered engines, on-road 
motor vehicles, diesel-powered on-road motor vehicles, residential wood 
combustion, other fuel combustion (e.g., residential space and water 
heaters and commercial boilers), open burning and other area sources, 
charbroiling, locomotives, airport ground support equipment, and major 
point sources. Measures for residential wood combustion, open burning, 
and major point sources categories were excluded from the RACM analysis 
because RACM had already been approved for them. The list of potential 
RACM did not include measures for the other fuel combustion sources or 
the charbroiling categories, nor were any measures for these categories 
suggested in the public comments received on the FIP. See Table 1 in 
the proposed rulemaking, 63 FR 15920, 14929. The industrial yards, 
surface mining, and other industrial activities source categories were 
found to have an impact only at the Salt River monitor, a monitor for 
which EPA has already approved an attainment demonstration that showed 
controls on these sources would not result in more expeditious 
attainment. See 62 FR 41856, 41862.
    Tailpipe emissions from gasoline-powered engines which account for 
only 0.3 g/m \3\ impact on the annual standard exceedance at 
the Greenwood monitor are already subject to stringent controls 
including the emission standards under the Federal Motor Vehicle 
Control Program, Arizona's premier I/M program, and the State's Clean 
Burning Gasoline program. Diesel powered on-road vehicles including 
trucks are also subject to national diesel fuels standards and tailpipe 
emission standards. See 40 CFR 80.29 (diesel fuel standards) and 40 CFR 
part 86, subpart H and 62 FR 54694 (October 21, 1997) (diesel tailpipe 
standards).
    Finally, it is important to review how the significance thresholds 
actually affected the outcome of the RACM analysis. EPA used the de 
minimis criterion as a justification for excluding measures for 
tailpipe emissions from on-road motor vehicles, locomotives, airplanes, 
airport ground equipment, off-road motorcycles, and heavy-duty 
construction equipment. See Table 3 in the proposed rulemaking, 63 FR 
15920, 14933. The two latter categories are very small contributors to 
the overall non-road engine source category. In total, these categories 
contributed 1.4 g/m \3\ to the annual standard exceedance at 
the Greenwood monitor and nothing to the 24-hour exceedances.
    Comment: The Arizona Department of Environmental Quality (ADEQ) 
comments that the determination of significant and de minimis sources 
for the annual PM-10 standard which was based upon preliminary modeling 
results using Urban Airshed Modeling (UAM) should be re-evaluated 
because the emissions inventory and dispersion modeling have not been 
reconciled against receptor modeling, as recommended under EPA's 
guidance for PM-10 plans (PM-10 SIP Development Guideline, EPA-450/2-
86-001, June 1986). ADEQ suggests that this should concern EPA because 
the inventory source apportionment differs greatly from receptor 
modeling source apportionment from the 1989-90 Phoenix PM-10 Study 
(Desert Research Institute, 1991). ADEQ states that, while these data 
are not relatively recent, large changes in the character of ambient 
particulate pollution since the time that study was conducted would not 
be expected and these data have been corroborated by more recent 
chemical analysis of particulate monitor filters from monitors in the 
urbanized portion of the Phoenix metropolitan area. ADEQ notes that the 
emission inventory is dominated by sources of geologic PM, even for the 
fine (PM-2.5 and smaller) particulate. ADEQ states that it rarely

[[Page 41332]]

finds more than 10 percent geologic materials in the measured fine PM 
fraction, whereas the emissions inventory estimates that over 70 
percent of the fine PM is geologic. Based on the filter data, ADEQ 
concludes that the role of combustion sources relative to geologic 
sources is underestimated in the inventory, stating that carbon 
particles, both primary and secondary, rival geologic material in terms 
of PM-10 mass, but are minor in the PM-10 inventory that EPA is using.
    Response: EPA agrees that, ideally, dispersion and receptor 
modeling should be reconciled, using accepted protocols, such as the 
one in Protocol for Reconciling Difference Among Receptor and 
Dispersion Models (EPA-450/4-87-008). However, the concentrations to be 
reconciled should be matched in terms of sampling period; i.e., 1989/90 
data should not be used to reconcile modeling for 1995. Moreover, 
modeling of recent high PM-10 days would not necessarily be expected to 
match those observed in the Desert Research field study. During that 
field study, daily concentrations averaged 4 to 97 g/m \3\, 
depending on the monitoring site, with no 24-hour NAAQS exceedances 
observed. Although the data from this field study were all that were 
available for the State's initial moderate area plan and were 
acceptable on that basis, it is not reasonable to require analysis of 
recent, exceedance days to match the earlier work. Unfortunately, no 
later receptor modeling was available for the FIP for reconciliation. 
See also the response to ACLPI's comment regarding the differences 
between the 1989 and 1995 emission inventory in section IV.D.2. below.

B. FIP Measures

1. Commitment for Agricultural Sector
    In its April 1, 1998 proposed rulemaking, EPA proposed an 
enforceable commitment to adopt and implement RACM as required by CAA 
section 189(a)(1)(C) for the agricultural sector in the Phoenix 
nonattainment area. Specifically, the proposed commitment contained 
enforceable milestones for EPA's proposal (by September 1999), final 
adoption (by April 2000), and implementation (by June 2000) of RACM for 
agricultural fields and aprons. In the proposal, EPA explained its 
intention to use a stakeholder approach for the development of best 
management practices (BMPs) to meet the CAA's RACM requirement and 
provide PM-10 emission reductions from agricultural sources in the 
Phoenix area.
    EPA is today taking final action to promulgate an enforceable 
commitment in 40 CFR 52.127 to adopt and implement RACM as required by 
CAA section 189(a)(1)(C) for the agricultural sector. While EPA 
received a number of comments on its proposed commitment, to which it 
responds below and in the TSD, the Agency is, in this final rule, 
retaining the text of the commitment as proposed.
    Comment: ACLPI and the American Lung Association of Arizona (ALAA) 
claim that a mere commitment to develop unspecified controls for 
agricultural fields and aprons is inadequate and does not meet the CAA 
requirements or EPA guidance for enforceable measures as expeditiously 
as practicable. The commenters contend that such a commitment offers no 
assurance that adequate controls will ever be adopted.
    Response: Because the commenters provide no citations or analysis, 
in favor of a broad claim of inadequacy, EPA is left to divine the 
precise nature of their legal challenge to the provisions for 
agriculture in the proposed FIP. To the extent that the commenters are 
suggesting that ``a mere commitment'' is not cognizable under the CAA, 
EPA notes that the Agency has a long history of approving enforceable 
commitments in SIPs under the statute. Moreover, the milestones in such 
commitments have routinely been deemed to be enforceable in CAA section 
304 citizen suits. For an extensive discussion of the legal basis for 
such approvals under the CAA as amended in 1990, see 62 FR 1150, 1155-
1157 (January 8, 1997).
    In its April 1, 1998 Federal Register notice, EPA proposed a 
commitment to adopt and implement RACM for agricultural fields and 
aprons by specified dates that, as finalized today, will be enforceable 
in a citizen suit. In that proposal, EPA explained its rationale for 
addressing agricultural sources of PM-10 emissions. In short, the 
Agency believes that, given the current state of its knowledge of the 
local agricultural community and conditions, the BMP process the Agency 
intends to pursue is the approach most likely to lead to effective 
controls on these sources in the shortest possible time frame. See 63 
FR 15920, 15935-15936.
    EPA has issued detailed preliminary guidance on the appropriate 
methodology for determining RACM under CAA sections 172(c)(1) and 
189(a)(1)(C), as well as a list of available fugitive dust control 
measures. See 57 FR 13540-13541; 13560-13561 and 57 FR 18071, 18072. 
EPA followed this guidance in determining federal RACM in the proposed 
FIP. In carrying out its FIP commitment to propose RACM for 
agricultural fields and aprons by no later than September 1999, EPA 
will adhere to the RACM guidance in effect for these sources at that 
time. As with all proposed EPA rulemakings, the public will have the 
opportunity to state its views on the legal adequacy of the proposed 
controls. Should EPA fail to propose RACM for these sources by 
September 1999, ACLPI and ALAA may pursue their remedies under CAA 
section 304. Once EPA takes final adoption action, they can of course 
petition for review of that action under CAA section 307.
    Comment: ACLPI argues that since agricultural control measures have 
been adopted in other states, e.g., in California's Coachella Valley, 
or identified by the Governor's 1996 Task Force, there is no excuse for 
delay. ACLPI also comments that even if further delay in development of 
agricultural controls were warranted, EPA cannot justify taking more 
than a year to develop proposed rules and that there is no reason the 
Agency cannot adopt enforceable rules within 6 months. ACLPI asserts 
that 6 months would allow time for obtaining stakeholder input without 
turning rule development into a protracted exercise.
    Response: Prior to the FIP proposal, EPA evaluated available 
measures for agriculture adopted by the South Coast Air Quality 
Management District (SCAQMD): 403--Fugitive Dust; 403.1--Wind 
Entrainment of Fugitive Dust; and 1186--PM-10 Emissions from Paved and 
Unpaved Roads, and Livestock Operations. As discussed in the FIP 
proposal, EPA determined that there was insufficient information 
available to conclude that implementing the controls in these rules in 
Maricopa County would, taking all relevant factors into account, be 
appropriate, i.e., reasonable, and thus constitute RACM for this area. 
See 63 FR 15920, 15935. EPA intends to consider whether these or other 
measures would be appropriate for the Phoenix area during the BMP 
development process.
    ACLPI dismisses EPA's statements regarding the Agency's inability 
to ascertain the suitability of the SCAQMD measures for the Phoenix 
area by asserting that the ``techniques for controlling agricultural 
emissions are well known.'' This assertion ignores the fact, noted by 
EPA in its proposed rulemaking, that PM-10 strategies in an 
agricultural context are uniquely based on local circumstances, and 
could vary greatly due to factors such as regional climate, soil type, 
growing season, crop types, water availability, and relation to

[[Page 41333]]

urban centers. 62 FR 15920, 15935. A resolution of these uncertainties, 
in the context of an assessment of the potential mix of control 
measures, is critical to a determination of whether controls such as 
those contained in the SCAQMD rules are reasonably available for the 
Maricopa County nonattainment area and will contribute to attaining the 
PM-10 standards in the area. Such an assessment is fully consistent 
with EPA's guidance regarding the process for determining RACM.
    As a result, EPA determined that the goal of attaining the PM-10 
standards in Maricopa County with respect to agricultural sources would 
be best served by engaging all interested stakeholders in a joint 
comprehensive process on the appropriate mix of agricultural controls 
to implement in Maricopa County. EPA believes that this process, 
despite the additional time needed to work through it, will ultimately 
result in a best and most cost-effective controls on agricultural 
sources in the County. EPA has thus committed in the final FIP to 
propose RACM for the agricultural sector by September 1999, with final 
adoption in April 2000. Given the number of potential BMPs, the variety 
of crops types, the need for stakeholder input, and the time necessary 
to develop the BMPs into effective control measures, EPA believes that 
the adoption schedule is expeditious.10
---------------------------------------------------------------------------

    \10\ It is important to note that the measures identified by the 
Governor's 1996 Task Force were initially intended to be voluntary 
and would require a process virtually identical to that envisioned 
by EPA in its FIP in order to be developed into effective controls. 
The Task Force measures, along with any other measures potentially 
available for Maricopa County, will be evaluated as part of the BMP 
development process.
---------------------------------------------------------------------------

    Comment: The American Farm Bureau Federation (AFBF) contends that 
because little data exist for agriculture's contribution to PM-10, 
there is a need for sound science before regulation and the California 
Regional Particulate Matter Air Quality Study (CRPMAQS) will provide 
additional data. AFBF claims that any agricultural emission controls 
are premature and should be postponed until the CRPMAQS data is 
available. The Maricopa County Farm Bureau (MCFB) also comments that 
agricultural controls are premature, citing University of California 
and University of Arizona research suggesting current PM-10 emission 
estimates from agricultural sources are overstated.
    Response: On August 4, 1997, EPA disapproved portions of the 
State's microscale plan, in part because it demonstrated, through a 
scientific study, that agricultural sources contribute significantly to 
exceedances of the PM-10 air quality standards in Maricopa County, but 
did not provide for the implementation of RACM for agricultural fields 
and aprons. 62 FR 41856, 41862. As a result, EPA is providing for RACM 
implementation for these sources.
    Moreover, other than vague statements about lack of data and sound 
science, AFBF failed to describe any specific deficiencies in the 
scientific study that resulted in the conclusions in the microscale 
plan. Likewise, MCFB failed to cite any specific research data that 
would refute those conclusions. EPA believes that the microscale plan's 
conclusions were based on sound science, as demonstrated by an 
intensive study throughout 1995 which included field surveys, aerial 
photography, examination of activity logs, and interviews with source 
operators. See Microscale plan, Appendix A, Chapter 4. The study 
resulted in substantially better emissions inventory data than were 
usually available. The study included extensive monitoring and a 
thorough analysis of the area's PM-10 problem. The State used locally-
developed emission factors in its modeling. Overall, the episodes 
modeled in the microscale plan are representative of the conditions 
under which the exceedances of the 24-hour PM-10 NAAQS occur. Model 
performance was generally good and well within what can be expected 
from the type of model used. See 62 FR 31025, 31031.
    EPA will use the CRPMAQS and any other information appropriate for 
the Maricopa area as the data become available. However, it is 
important to note that the PM-10 exceedances in Maricopa County are 
typically caused by wind-blown, primary particulates (i.e., geologic 
sources). The PM-10 exceedances in the San Joaquin Valley (where the 
CRPMAQS is underway) are caused by primary and secondary particulates 
and typically are not associated with high wind events. While the 
CRPMAQS will yield a tremendous amount of new information, much of the 
information may not be applicable to Maricopa. For the foregoing 
reasons, EPA does not believe that postponing development of the BMPs 
pending the completion of the CRPMAQS would be appropriate.
    Comment: AFBF comments that this past March, the U.S. Department of 
Agriculture-Natural Resources Conservation Service (USDA-NRCS) 
Agricultural Air Quality Task Force agreed to develop a PM-10 
implementation policy that will help guide states and EPA when dealing 
with agriculture and PM-10. Thus, AFBF believes that any agricultural 
emission controls are premature and should be postponed until a USDA 
Task Force policy is available. MCFB and AFBF believe that if USDA 
develops a national policy which outlines voluntary controls for 
agricultural PM-10, enforceable provisions should be removed from the 
FIP and SIP. They state that the final FIP should include language that 
will allow for the FIP to be revised as data and policy become 
available.
    Response: Regarding the issue of whether the FIP agricultural 
provisions are premature, see EPA's response to AFBF's previous 
comment. In addition, EPA does not believe that postponing development 
of the BMPs pending the development of a USDA Task Force policy would 
be appropriate. EPA has worked extensively with MCFB, the Arizona Farm 
Bureau Federation and other stakeholders to craft a workable strategy 
for Maricopa County. The Arizona Federation supported legislation 
recently signed by Arizona Governor Hull for a State-led process for 
developing BMPs.11 EPA supports the position of the farming 
interests in Maricopa County to implement the recently adopted 
legislation and thereby maintain local control over the solution.
---------------------------------------------------------------------------

    \11\ Governor Hull recently signed SB 1427 ``Air Quality 
Measures'' which authorizes a state-led BMP process. Section 16. 
Title 49, chapter 3, article 2, of the Arizona Revised Statutes was 
amended by adding section 49-457, Agricultural best management 
practices committee; members; powers; permits; definitions. The 
State has indicated to EPA that section 49-457 will be submitted to 
EPA in the coming months as a replacement for the portion of the FIP 
which addresses agricultural sources.
---------------------------------------------------------------------------

    If EPA adopts a national policy for PM-10 emissions from 
agricultural sources that the State and the Maricopa County farming 
community would like to use, EPA will assess its implications for the 
area and work with the agricultural leaders and the local air agencies 
on any appropriate changes to the current strategy.
    Comment: MCFB comments that the 24-hour exceedances attributed to 
agricultural sources occurred during a dust storm and unless BACM are 
in place, EPA will not consider natural occurrences, such as a dust 
storm, as a source of PM-10. Because dust storms will happen whether or 
not BACM are in place, MCFB would like this policy to be changed before 
any industry is burdened with control measures.
    Response: Contrary to MCFB's contention, the exceedances which 
implicate agricultural sources did not occur during dust storms. Rather 
they

[[Page 41334]]

resulted from normal wind conditions which routinely occur. A review of 
the exceedances and monitoring data used in support of the State's 
microscale plan indicates that the exceedances were localized and did 
not occur at many of the monitoring sites. If the exceedances had been 
caused by a dust storm, exceedances would be expected throughout the 
County.
    EPA does have a policy 12 that permits dust raised by 
high winds from anthropogenic sources controlled with BACM to be 
treated as due to a natural event. Key aspects of the policy include 
that EPA will not designate an area as nonattainment when NAAQS 
violations are caused by natural events and EPA would consider 
redesignating an area to attainment if it had BACM in place and the 
only violations were due to high wind events. However, and more 
importantly, the policy is explicit that all exceedances, no matter 
what the cause, are of concern to public health and steps need to be 
taken to reduce public exposure to unhealthful particulate levels. 
Therefore, there is a need to reduce the level of exceedances during 
natural events even if the exceedances cannot be eliminated; hence, the 
requirement for BACM.
---------------------------------------------------------------------------

    \12\ Memorandum from Mary D. Nichols, EPA, to EPA Regional 
Offices, entitled ``Areas Affected by PM-10 Natural Events,'' dated 
May 30, 1996.
---------------------------------------------------------------------------

    Comment: MCFB states that Maricopa County is the fastest growing 
county in the nation and that rapid growth is forcing land out of 
agriculture at a rate of 6,000 acres per year. MCFB urges that because 
the growth is pushing agriculture out of business, agriculture should 
be released from further controls or it will only speed the 
disappearance of agriculture from the Phoenix area. MCFB believes that 
the only way to eliminate PM-10 is to regulate farmers out of existence 
in Maricopa County.
    Response: In the FIP proposal, EPA acknowledged that agricultural 
land is being converted into other uses. However, even with rapid 
conversion, agricultural lands will remain a significant source of PM-
10 for the foreseeable future. EPA's purpose here is to effectively 
control PM-10, not to put farmers out of business. Through the 
stakeholder process, EPA will work with the farming community to meet 
that goal while ensuring that the BMPs developed to meet the CAA's RACM 
requirement are economically feasible. In addition, some cities in 
Maricopa County have begun to express interest in preserving 
agricultural lands for open space. This interest may reduce the amount 
of land being converted from agricultural use.
2. Rule for Unpaved Parking Lots, Unpaved Roads and Vacant Lots
    a. Background. In its April 1, 1998 notice, EPA proposed a FIP rule 
for Phoenix that required RACM for unpaved parking lots, unpaved roads 
and vacant lots. The reader should consult that notice for a detailed 
discussion of the requirements EPA proposed for these sources. See 63 
FR 15920, 15937.
    In the FIP proposal, EPA explained that MCESD has adopted, and EPA 
has approved, MCESD Rule 310 that requires RACM for fugitive dust 
sources, including those regulated in the FIP. However, because EPA had 
previously determined that the County was not enforcing the rule for 
these three PM-10 sources, the Agency disapproved the State's RACM 
demonstration for them. 62 FR 41856, 41862.13 As a result, 
EPA is promulgating a federal RACM rule covering these sources. Because 
the deficiency in the State's RACM demonstration did not relate to the 
substance of MCESD's fugitive dust rule, EPA modeled its proposed rule 
on Rule 310.
---------------------------------------------------------------------------

    \13\ Section 221 of Rule 310 is entitled ``Reasonable Available 
Control Measure (RACM)'' and the term ``RACM'' is used throughout 
the rule. EPA has approved Rule 310 into the SIP as meeting the 
enforceability requirements of CAA sections 110(a)(2)(A) and 
172(c)(6). See 62 FR 31025, 31032 (June 6, 1997) and 62 FR 41856, 
41864. Regardless of the terminology in Rule 310, as just noted, EPA 
has determined that the County's implementation of the rule does not 
meet the RACM implementation requirement of CAA section 189(a)(1)(B) 
for unpaved roads, unpaved parking lots and vacant lots.
---------------------------------------------------------------------------

    The primary difference between the County rule and EPA's proposed 
rule was that, because EPA's San Francisco office would be responsible 
for its enforcement, the FIP rule provided greater specificity and 
detail regarding which control measures are appropriate for which 
sources. See 63 FR 15920, 15937; 15942-115943. Since, by its terms, the 
requirements of Rule 310 are so broad, the general effect of this 
greater specificity and detail was that EPA's proposed FIP rule, in its 
entirety, while achieving what the Agency believed to be a RACM level 
of control, was somewhat narrower in scope than the County's rule as it 
relates to unpaved roads, unpaved parking lots and vacant 
lots.14
---------------------------------------------------------------------------

    \14\ For example, section 312 of Rule 310 regulates users of 
unpaved roads, while EPA's rule proposed regulation of only owners 
and operators; and Rule 310 does not exempt any unpaved roads, while 
EPA's rule included a low ADT exemption.
---------------------------------------------------------------------------

    EPA is today promulgating a final FIP fugitive dust rule at 40 CFR 
52.128 that incorporates a number of changes in response to public 
comments. Those changes, summarized and discussed below and in the TSD, 
reflect the same fundamental philosophy described above. The net result 
of the substantive changes is to provide sources with greater 
flexibility than provided in the FIP proposal.15 For 
example, the final FIP rule includes an increase from 0.10 acre to 0.50 
acre in the de minimis disturbed surface area level for vacant lots; an 
increase from 150 average daily trips (ADT) to 250 ADT in the ADT 
exemption level for unpaved roads; a new de minimis use level for 
unpaved parking lots; and the elimination of the dust control plan 
(DCP) requirement for weed abatement.
---------------------------------------------------------------------------

    \15\ For the reasons discussed in this section, EPA believes 
that the final FIP rule, with the modifications made in response to 
comments, meets the RACM requirements of the CAA.
---------------------------------------------------------------------------

    In a separate rulemaking, EPA plans to propose and take comment on 
amendments to some of the alternative control measure (ACM) and test 
method provisions of today's final rule. While EPA believes that these 
changes are warranted,16 EPA cannot include them in today's 
final action because they are beyond the scope of the proposed FIP 
rule. Because EPA has a court-ordered deadline of July 18, 1998 to 
promulgate the FIP rule, the Agency is taking final action on its rule 
without the ACM and test method changes, but will publish the proposed 
amendments shortly.
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    \16\ EPA intends to propose new test methods to replace the 
opacity (and corresponding opacity standard) and the visible crust 
method as proposed in the FIP and include an additional test method 
for standing vegetation. In response to public comments, EPA 
conducted technical field work in Phoenix on the proposed test 
methods. While they were the best available methods known to EPA at 
the time of proposal, additional analysis has indicated that other 
test methods may be more accurate and comprehensive. EPA also 
intends to propose the elimination of the requirement to submit ACMs 
to EPA for approval unless the ACM's effectiveness cannot be 
measured by the test methods or specific language included in the 
rule. EPA is also considering whether to propose an amendment to the 
FIP rule that would require RACM for unpaved roads that are neither 
owned nor maintained by a public entity.
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    b. Summary of Changes to the Proposed FIP Rule. In addition to the 
substantive changes to the proposed FIP rule referenced above that 
provide additional flexibility, the final FIP rule also includes 
changes that clarify or revise the RACM implementation schedules. Other 
final FIP rule changes provide minor clarifications of the FIP rule 
provisions such as adding language to clarify test methods, exemptions 
and definitions. The substantive changes to the final FIP rule are 
summarized below by source category.
    Unpaved Parking Lots and Unpaved Roads. The final rule:

[[Page 41335]]

     Increases the ADT exemption level for unpaved roads from 
150 ADT to 250 ADT.
     Includes a de minimis use exemption for unpaved parking 
lots and requires RACM only on surfaces where vehicles park.
     Eliminates the 2-inch requirement for gravel and relies on 
the applicable test methods for compliance.
     Includes organic stabilizers in addition to chemical 
stabilizers.
     Eliminates the provision requiring RACM only where 70 
percent of the unpaved road is located within the Phoenix nonattainment 
area and focuses on the unpaved roads or portion of an unpaved road 
located within the nonattainment area.
     Clarifies that operators of privately-owned public access 
unpaved roads are the parties responsible for compliance with the RACM 
requirements.
    Vacant Lots. The final rule:
     Eliminates the requirement for dust control plans in favor 
of a provision requiring compliance with three RACM options.
     Increases the de minimis disturbed area level from 0.10 
acre (proposed rule) to 0.50 acre.
     Includes a de minimis exemption (5,000 square feet) for 
lots disturbed by motor vehicle trespassing.
     Modifies the time frame for RACM to be implemented on 
disturbed surfaces from eight months to 60 days, except for the initial 
eight months following the effective date of the rule.
     Expands RACM for motor vehicle disturbances on vacant 
lots.
     Eliminates the 2-inch requirement for gravel and relies on 
the applicable test methods for compliance.
     Includes an initial eight-month time frame following the 
final rule's effective date for implementation of RACM for motor 
vehicle disturbances and weed abatement.
     Clarifies the rule's test methods and contains language 
for some test methods that were previously only referenced in the 
proposed rule.
    General Changes. The final rule:
     Clarifies the requirements to which exemptions apply.
     Clarifies that the tribal lands within the Phoenix PM-10 
nonattainment area are not covered by the provisions of the FIP rule.
     Clarifies that Apache Junction is not covered by the 
provisions of the FIP rule.17
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    \17\ The Maricopa PM-10 nonattainment area is comprised of the 
greater Phoenix metropolitan area in Maricopa County and the Apache 
Junction area in Pinal County. The State submitted separate moderate 
area PM-10 plans for the Maricopa County portion and the Pinal 
County portion of the nonattainment area. The incompleteness finding 
that triggered EPA's obligation to promulgate this FIP was made only 
on the submitted plan for Maricopa County and thus EPA's FIP 
authority only extends to this part of the nonattainment area. The 
Pinal County plan became complete by operation of law on May 14, 
1992. As a result, EPA is clarifying that this FIP does not cover 
the Apache Junction area.
---------------------------------------------------------------------------

    c. Public Comments and EPA Responses. Implementation Costs.
    Comment: The Maricopa Department of Transportation (MCDOT) and the 
Arizona Chamber of Commerce (ACOC) assert that EPA's interpretation of 
Maricopa County Rule 310 as currently requiring suppression of dust on 
all unpaved public access roads is incorrect. MCDOT claims that in the 
development of the rule, MCDOT, MCESD and other stakeholders agreed to 
commit to a dust reduction program. MCDOT states that the rule called 
for use of RACM on unpaved roads in Section 312 with reference to the 
list of measures in Section 221. MCDOT further states that, while not 
explicitly stated in the rule, EPA and MCESD have always interpreted 
RACM to include a financial and cost effectiveness test and that MCESD 
has in practice accepted the SIP commitments for dust suppression and 
the five-year work plan for capital projects as what was reasonably 
available. MCDOT says that its commitment was to stabilize 25 miles of 
roadway per year. MCESD also makes similar comments regarding its 
acceptance of the five-year work plans for capital projects as 
satisfying the RACM requirement.
    Response: EPA notes that MCDOT concedes, by its references to 
sections 312 and 221 of Rule 310, that the regulatory scope of these 
sections of Rule 310 encompasses the same universe of sources and 
measures as the proposed FIP rule. Thus, the issue is whether any 
acceptance by MCESD of MCDOT's SIP commitment to stabilize 25 miles of 
roadway per year constitutes compliance with the rule. In EPA's final 
action on the State's microscale plan, EPA determined that the MCESD's 
implementation of Rule 310 (i.e., enforcement on a complaint basis for 
vacant lots, unpaved parking lots and unpaved roads 18) is 
inadequate and consequently disapproved the RACM demonstration in that 
plan for these sources. 62 FR 41856, 41865. EPA received no public 
comments which disagreed with this finding. Moreover, MCESD has never 
incorporated a 25 mile stabilization limit into Rule 310. Nor has EPA 
made a determination or approved into the Phoenix PM-10 SIP MCDOT's 25 
mile stabilization commitment as representing a RACM level of control. 
Therefore, as a legal matter, such an understanding between MCESD and 
MCDOT does not establish MCDOT's commitment as meeting the RACM 
requirements of the CAA.19
---------------------------------------------------------------------------

    \18\ The fact that MCESD enforces Rule 310 for these sources on 
a complaint basis is clear evidence that they are included within 
the regulatory scope of the rule.
    \19\ See footnote 13.
---------------------------------------------------------------------------

    As stated above, EPA modeled its FIP rule on Rule 310, but provided 
greater detail and specificity which had the effect of narrowing the 
scope of Rule 310. As explained in more detail below, EPA believes, 
based on the information currently available to the Agency, that the 
requirements of the final FIP rule meet the economic feasibility 
criterion in the Agency's guidance and represent RACM for unpaved 
roads.
    Comment: MCDOT and the City of Mesa claim that EPA did not provide 
any analysis as to what methods or criteria were used to identify RACM 
and that there is no cost-benefit analysis provided to demonstrate the 
reasonable availability and effectiveness of the proposed measures. The 
City of Mesa asserts that, as EPA stated in the proposed rulemaking, 
any measures that are determined to be de minimis, technologically 
infeasible or unreasonably costly should be removed from the list of 
RACM. This commenter concludes that EPA did not conduct this analysis 
as part of the proposed FIP.
    Response: In section IV.B. of its proposed rulemaking, EPA set 
forth the criteria that the Agency must apply in determining what 
measures constitute RACM. In general, EPA excludes measures it 
determines to be unreasonably costly, technologically infeasible or 
that apply to sources of PM-10 that are de minimis. 63 FR 15920, 15926. 
In section V of the FIP proposal, EPA provided a detailed description 
of its approach for determining which RACM to include in the proposed 
FIP. 63 FR 15920, 15927-34. For the purposes of the RACM analysis, 
public sector sources, like EPA, should evaluate the criterion relating 
to the cost of control measure implementation by considering the 
reasonableness of potential RACM based on the financial and resource 
capabilities of the governmental entity responsible for implementing 
such measures. The FIP RACM analysis involved a list of 99 potential 
RACM which were evaluated against 2 sets of criteria: (1) to determine 
if a measure was appropriate for federal implementation; and (2) to 
determine if a measure was RACM. The latter set of criteria include 
economic feasibility.

[[Page 41336]]

    EPA did not provide a cost-benefit analysis for the proposed FIP 
measures because, as discussed in the proposed FIP's Regulatory 
Flexibility Analysis, all of the requirements of the FIP's fugitive 
dust rule are already required under the County's Rule 310. See 63 FR 
15920, 15942. In fact, EPA believes, as stated previously, that the 
scope of the FIP rule as proposed (and as modified in this final 
action) is narrower than that of Rule 310. Hence the costs of 
compliance with the FIP rule should, to the extent that there is any 
cost differential, be less than those for Rule 310.20 See 63 
FR 15920, 15943-15944 and section VII.B.2. below for detailed 
discussions of this issue.
---------------------------------------------------------------------------

    \20\ For this reason, EPA disagrees with MCDOT's claim that 
compliance with the FIP rule implicates the cost-benefit analysis 
requirements of the Unfunded Mandates Reform Act. Nor does the FIP 
rule constitute a major federal action under the National 
Environmental Policy Act (NEPA) as the commenter suggests. EPA 
actions under the CAA are expressly exempt from that statute. 15 
U.S.C. Sec. 793(c)(1).
---------------------------------------------------------------------------

    Nevertheless, EPA did include estimates of control effectiveness 
and unit costs in the TSD for the FIP rule.21 As discussed 
in the TSD, the control effectiveness estimates were based on available 
data, which was limited. Thus only relatively crude estimates were 
developed for the emissions reductions associated with the FIP rule (or 
implementation of Rule 310). The unit costs are based on information 
found in documents prepared by or referenced by the Maricopa 
Association of Governments. The costs associated with the FIP rule and 
their relationship to the RACM determination are discussed further in 
response to the following comment.
---------------------------------------------------------------------------

    \21\ See sections 5.0, ``Emissions Reductions,'' and 6.0, ``Cost 
Estimates'' of the TSD for the Phoenix FIP Rule for Unpaved Parking 
Lots, Unpaved Roads and Vacant Lots.
---------------------------------------------------------------------------

    Comment: MCDOT comments that if Maricopa County were required to 
pave all public access unpaved roads within its jurisdiction, as 
described by the proposed rule, it would require an expenditure greater 
than $100 million, to as much as $300 million, or approximately 5-10 
years of the County's total capital improvements budget for 
transportation projects. Furthermore, MCDOT asserts that additional 
paving of parking lots and compliance by cities and towns within the 
County could, in aggregate, be nearly one billion dollars. MCDOT also 
claims that there is a substantial maintenance expense in the future 
for all roads paved or stabilized, which will create an additional tax 
burden.22
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    \22\ MCDOT elaborates on this point by claiming that long term 
maintenance data indicate that by paving these roads, life cycle 
maintenance costs will increase by a factor of five. MCDOT estimates 
that chemical stabilization will triple the maintenance cost of 
these roadways.
---------------------------------------------------------------------------

    Response: The final FIP rule does not require the County to pave 
all of its unpaved roads. The FIP rule requires RACM for unpaved roads 
with greater than 250 ADT (increased from 150 ADT in the proposed FIP 
rule). Compliance options include methods of stabilization that are 
less costly than paving.
    As discussed above and in the proposed FIP's Regulatory Flexibility 
Analysis, the FIP rule does not impose any additional compliance burden 
beyond that required by Rule 310. Thus, even without the FIP rule, EPA 
believes that EPA, a citizen, the State and the County could enforce 
under Rule 310 control measures that are more stringent than those 
required under the FIP rule.
    Because EPA had to develop the FIP rule within the court-ordered 
schedule, EPA was limited in the cost data available to the Agency for 
the economic feasibility analysis prong of the RACM criteria. See EPA's 
response to the previous comment. Unfortunately, while commenters on 
the proposed FIP rule provided conclusions as to what they deemed to be 
unreasonable compliance costs, they supplied no supporting data. 
Therefore, EPA was unable to use this information to refine its 
determination of the RACM level of control.
    Comment: The City of Mesa and MCDOT maintain that local governments 
should have the autonomy to target unpaved roads that are determined 
through local study and evaluation to significantly contribute to local 
or regional PM-10 levels and develop schedules for paving or 
stabilizing those roads with the greatest potential to decrease PM-10 
emissions.
    Response: In meeting the RACM requirements of the CAA, states are 
free to select the mechanisms they deem to be the most appropriate. 
Such decisions routinely involve evaluations of the concerns of local 
governments. While EPA has not approved Rule 310 as meeting the Act's 
RACM requirements for the unpaved road, unpaved parking lot and vacant 
lot source categories, clearly that rule was intended to provide a 
County-wide RACM regulatory scheme. If MCESD and the State believe that 
the rule can be modified to address the concerns raised by the City of 
Mesa, Maricopa County or other local jurisdictions, it is free to do so 
and EPA will determine whether the rule as modified represents RACM and 
can replace the FIP rule. In making this determination, EPA would 
evaluate information submitted by MCESD in the staff report 
accompanying the rule justifying why the rule as modified represents 
RACM.
    In developing the FIP rule, EPA was constrained by a number of 
factors that necessitated a single approach to implementing RACM for 
the entire Phoenix nonattainment area. For example, EPA's San Francisco 
office must be able to enforce the rule throughout the nonattainment 
area and inform regulated parties of the rule's requirements. Resources 
for public outreach would be inadequate should EPA need to administer 
RACM differently from one jurisdiction to another. Moreover, even if 
EPA could administer a rule that specifies a different RACM level of 
control for the numerous jurisdictions within the Phoenix nonattainment 
area, EPA lacks the detailed information it would need to do so. 
Furthermore, as noted above, such information has not been forthcoming 
in responses to the FIP proposal.
    Comment: MCDOT, ADEQ and the Arizona Chamber of Commerce all 
comment on the issue of legal responsibility for compliance with the 
proposed FIP rule's requirements for unpaved roads. The Chamber claims 
that the definition in Sec. 52.128(b)(17) of ``unpaved road'' as 
``those * * * owned by any federal, state, county, municipal or other 
governmental or quasi-governmental agencies' will cause prohibitively 
expensive disputes over ownership between private and public entities 
and, due to its vagueness, could include more than 100,000 roads in the 
County. The Chamber also comments that local governments do not have 
the financial resources to decide ownership and to implement RACM. 
MCDOT notes that there is no definition of ``ownership'' and that in 
some contexts the proposed rule refers to ``owner/operator'' and in 
others, strict legal ownership. In this connection, MCDOT states that 
ninety percent of the unpaved, public access roads it maintains in the 
nonattainment area are not in public ownership. ADEQ makes a similar 
point and believes that the FIP's requirements should apply only to 
publicly-owned roads.
    Response: EPA's intent in proposing the requirements for unpaved 
roads was to ensure that responsible entities apply RACM to control 
these fugitive dust sources. As stated in the proposed rulemaking, EPA 
intended to accomplish this goal by making the requirements of the FIP 
rule essentially mirror those of MCESD's Rule 310. Because Section 312 
of Rule 310 is very broadly drafted, EPA attempted in its

[[Page 41337]]

proposal to narrow those responsible for compliance to owners or 
operators of the pollution sources. In order to rectify the confusion 
perceived by the commenters, EPA has amended the final rule to add the 
word ``maintains'' in the definition of ``owner/operator'' in 
Sec. 52.128(b)(10) and to add the words ``or operated'' in the 
definition of ``unpaved road'' in Sec. 52.128(b)(17).
    EPA does not believe that the purpose of the FIP's unpaved road 
requirements is served by limiting them to those sources that are 
publicly owned, particularly in view of the statistics provided by 
MCDOT and ADEQ. Therefore, EPA has also removed the word ``public'' 
from the definition of ``unpaved road'' in Sec. 52.128(b)(17) and, 
consequently, from the RACM requirements for unpaved roads in 
Sec. 52.128(d)(2). Thus the final rule applies to unpaved roads that 
are open to public access, but are privately or publicly owned. These 
changes are intended to clarify that both owners, and operators, 
including those who conduct roadway maintenance, are legally 
responsible for complying with the RACM requirements of 
Sec. 52.128(d)(2).23
---------------------------------------------------------------------------

    \23\ EPA routinely requires that those responsible for operation 
and maintenance of a source comply with emission or performance 
standards established under the CAA. See CAA section 302(k) and (l).
---------------------------------------------------------------------------

    In response to comments regarding the vast number of roads 
implicated by the proposed RACM requirements, and the concomitant 
compliance costs, EPA has changed the ADT threshold in 
Sec. 52.128(d)(2) from 150 to 250 and limited the sources to which that 
section's requirements apply to those portions of an unpaved road 
located within the Phoenix PM-10 nonattainment area.
    Comment: MCESD comments that a 0.10 acre threshold is appropriate 
at which to expect the application of controls. However, MCESD believes 
that enforcement on vacant lots should be reactive (i.e. complaint 
driven) for sites less than a threshold of 10 to 50 acres and proactive 
on larger sites. However, weed abatement operations that are permitted 
will be inspected under Rule 310. The inability to know when a vacant 
lot has been disturbed significantly reduces the cost-effectiveness of 
a proactive enforcement program for vacant lots. The amount of time 
spent checking undisturbed vacant lots adds little value to efforts to 
reduce particulate pollution. In addition, MCESD recommends that EPA 
refine what level of enforcement and/or implementation represents RACM 
and which represents BACM. MCESD cites as an example that their 
contacts with Coachella Valley area cities referenced in EPA's proposal 
and the TSD established that their vacant lot provisions are enforced 
on a complaint-only basis.
    Response: In its proposed action on the microscale plan, EPA 
proposed to find that the plan did not assure implementation of either 
RACM or BACM as required by CAA sections 189(a)(1)(C) and 189(b)(1)(B) 
and to disapprove the RACM/BACM demonstrations for the unpaved parking 
lots, unpaved roads, and vacant land source categories. This proposed 
disapproval was based on the County's enforcement of Rule 310 for these 
source categories on a complaint-basis only. See 62 FR 31025, 31034-
31035. MCESD did not make the comments it now advances in connection 
with EPA's proposed action on the microscale plan. On August 4, 1997, 
EPA took final action to disapprove the microscale plan provisions for 
implementing RACM and BACM for these sources. 62 FR 41856, 41862.
    While EPA considered dust control rules for other areas, RACM and 
BACM determinations are made on a case by case basis. See e.g., 57 FR 
13498, 13540, 13561; and 59 FR 41998, 42010 (August 16, 1994). 
Therefore, the South Coast Air Quality Management District's approach 
to dust control in Coachella Valley is not determinative of what 
constitutes the implementation of RACM or BACM for the Phoenix 
nonattainment area. As demonstrated in EPA's action on the microscale 
plan, implementation of Rule 310's vacant lot provisions on a complaint 
basis is not sufficient to prevent these sources from contributing 
substantially to exceedances of the PM-10 NAAQS in the Phoenix area. 
See 62 FR 31025, 31031. Furthermore, RACM and BACM are levels of 
emission reduction control. See 59 FR 41998, 42010. In contrast, the 
resources allocated for, and the method and frequency of, enforcement 
are the means of ensuring that such emission reductions occur, but are 
not themselves control levels.
    The provisions of Rule 310 require that RACM, as specified in the 
rule, be implemented for the unpaved parking lots, unpaved roads and 
vacant land source categories. Having adopted such a rule, the County 
has notified the affected parties that they must comply with the rule's 
requirements and must ensure that it has the resources and a program 
for ensuring that compliance occurs. See CAA section 110(a)(2). 
Moreover, since the County has purported to define what constitutes 
RACM by the terms of its rule, it cannot then fail to ensure that those 
measures are comprehensively enforced and still meet the requirement to 
implement RACM in CAA section 189(a)(1)(C). If MCESD believes that Rule 
310 as adopted represents a level of control for certain sources that 
is beyond RACM or BACM, it is free to modify the rule and submit it to 
EPA with the appropriate justification. EPA will then evaluate the 
submittal for compliance with the CAA's RACM/BACM requirements.
    Comment: ACOC comments that the vacant lot ``Disturbed Surfaces'' 
provision of the proposed FIP rule would impose a huge economic burden 
on homebuilders and private landowners due to the fact that any amount 
of disturbed surface area left vacant for more than fifteen days is 
subject to the rule. Also, the average private citizen would likely be 
unaware of this requirement.
    Response: Since there is a de minimis vacant lot size, it is not 
true that any amount of disturbed area is subject to the rule. In the 
final rule, EPA has increased the de minimis threshold from 0.10 to 
0.50 acre of disturbed surface for stabilization of disturbed surfaces. 
In any case, the rule does not pose a huge economic burden on 
homebuilders; homebuilders need to receive a permit under Maricopa 
County Rules 200 and 310 for earth-moving operations over 0.1 acres, 
and are therefore not regulated under the FIP rule. However, should 
homeowners prepare vacant property for construction by scraping and 
leave the surface disturbed for over 15 days prior to construction and 
permit applicability, they are subject to the FIP rule. EPA based the 
fifteen-day time period on language in MCESD's Rule 310 and believes it 
is appropriate as the disturbed vacant lot will be a continual dust 
source until re-stabilized. EPA plans to provide outreach assistance to 
vacant lot owners within the first eight months following the effective 
date of the final rule prior to the required RACM implementation 
deadline in order to increase awareness of the FIP rule and its 
requirements.
    FIP Rule Requirements. De Minimis Levels.
    Comment: Several commenters state that the requirement in the 
proposed FIP rule to pave all public roads with 150 ADT is 
unreasonable. Commenters believe that the 150 ADT threshold is 
arbitrary, includes too many roads and is economically burdensome.
    Response: EPA believes that a higher ADT threshold is warranted and 
represents a RACM level of control. Therefore, in the final FIP rule, 
EPA has increased the ADT threshold from 150

[[Page 41338]]

to 250. This higher ADT threshold will relieve some of the cost burden 
on public entities, while targeting the roads that cause the most PM-10 
emissions. The final rule, with the 250 ADT threshold, will control 
dust on roads which receive two vehicles every five minutes, on 
average, throughout primary driving hours in a given day rather than 
one vehicle every five minutes. EPA, through a contractor, will by the 
end of 1998 acquire more data on the sources subject to the FIP rule, 
including unpaved roads and their ADT. Should EPA determine in the 
future, based on additional information, that the final FIP rule 
requirements do not represent a RACM level of control for the Phoenix 
area, the Agency will propose appropriate revisions to the FIP.
    Comment: The Grand Canyon Council of the Boy Scouts of America 
comments that the FIP rule should provide a de minimis use level below 
which requirements are not triggered. The Council claims that the 
proposed FIP's unpaved parking lot provision does not allow reduced 
compliance for lots that receive relatively little heavy use during the 
year (but are used more than 35 days a year). The Council suggests a de 
minimis level of ingress by fewer than 10 or 25 vehicles per day.
    Response: In the final rule, EPA addresses the Council's concern by 
establishing an exempted use level for unpaved parking lots of 10 
vehicles a day or less. Furthermore, since there are a number of 
unpaved parking lots significantly larger than 5,000 square feet where 
parking occurs only in a few localized areas, in the final rule, the 
owner/operator is only required to implement RACM on the portion of a 
lot (as opposed to the entire lot) on which vehicles park. 
Notwithstanding regular use of an unpaved parking lot by 10 or fewer 
vehicles, the rule offers flexibility for lots used no more than 35 
days a year to require RACM controls only if over 100 vehicles park on 
the lot and only for the duration that the vehicles are parked.
    Comment: MCESD comments that the 0.10 acre threshold for vacant 
lots is an appropriate threshold at which to expect application of 
controls, but that it is not reasonable to enforce all vacant lots at 
this level, except for weed abatement operations. Several other 
commenters suggest that a de minimis level of 0.10 acre for vacant lots 
is too small. Commenters also state that the regulatory burden on small 
residential property owners would be too high and that disturbed static 
lots do not contribute significantly to PM-10 compared to disturbed 
sites with active earth-moving operations. Commenters suggest that the 
de minimis level be increased to one or five acres.
    Response: In the final rule, EPA has increased the RACM 
implementation de minimis threshold for vacant lot requirements 
concerning weed abatement and disturbed surface from 0.10 acre to 0.50 
acre. The final rule's de minimis threshold of 0.50 acre is responsive 
to commenter's concerns to focus the FIP rule on larger disturbed 
areas; however, EPA does not believe a de minimis level greater than 
0.50 acres is warranted given MCESD's belief that weed abatement 
disturbing 0.1 acres merits control. Since the majority of vacant lot 
disturbances are caused by weed abatement and an uncontrolled weed 
abated lot would be covered by the requirements for disturbed surfaces, 
EPA believes there is a need for consistency between the weed abatement 
requirement and the disturbed surfaces requirement. Thus, EPA believes 
that a 0.50 acre de minimis level is appropriate.
    EPA does not believe that the regulatory burden of the FIP rule 
will be high on small residential property owners as the majority of 
residential property owners have homes on their property. The FIP rule 
does not apply unless the property is vacant and disturbed. Moreover, 
the FIP rule only applies where a vacant property's disturbed surface 
area is greater than the exemption levels. Where the FIP rule does 
apply, property owners have a number of RACM from which to choose, 
including lower cost alternatives such as re-vegetation and watering. 
In some cases, vacant lots naturally re-stabilize with rainfall to form 
a crust or they contain sufficient amounts of aggregate materials or 
vegetation such that the standards set forth in the FIP rule are met. 
For these reasons, EPA believes the commenters have over-estimated the 
regulatory impact of the FIP rule on vacant lot owners. Finally, as 
discussed in EPA's responses to comments regarding the cost impacts of 
the FIP rule, because all of the RACM discussed above and found in the 
FIP rule are already required by Maricopa County's Rule 310, the final 
FIP rule does not impose any additional regulatory burden beyond Rule 
310.
    Compliance Deadlines. Comment: The City of Phoenix comments that 
the final rule should move the compliance deadline for disturbed 
surfaces on vacant lots from eight months after the effective date of 
the rule to June 10, 2000. The City claims this is needed in order to 
ensure that property owners become aware of the rule and to implement 
dust control measures.
    Response: EPA believes an eight-month period of time is sufficient 
to conduct public outreach to vacant lot owners regarding FIP rule 
requirements to stabilize property or erect barriers. EPA plans to 
provide outreach assistance to vacant lot owners within the first eight 
months following the effective date of the final rule prior to the 
required RACM implementation deadline in order to increase awareness of 
the rule and its requirements. The only reason the RACM deadline for 
public unpaved roads is June 10, 2000 is due to EPA's recognition that 
public entities require additional time to budget funds to implement 
RACM. EPA believes that the majority of vacant lots with disturbed 
surfaces can be stabilized (unless further disturbed) by applying water 
or re-vegetating, thus, a long time-frame for implementing RACM is 
unwarranted. Notwithstanding the initial eight-month time frame for 
RACM implementation, the final rule requires that RACM be implemented 
within two months following a disturbance.
    Comment: MCDOT and MCESD comment that the June 10, 2000 deadline 
for RACM to be implemented on roads with 150 ADT or more is not 
feasible due to the large amounts of material and/or chemicals needed 
and the time needed to complete roadway design, right-of-way 
acquisition and construction. They state that no other attainment area 
has been required to establish a deadline for completion of 
stabilization of unpaved surfaces. MCESD and ADEQ suggest that a more 
appropriate and realistic compliance target should be an established 
schedule that extends beyond June 2000 for treating public unpaved 
roads using ADT to establish priorities.
    Response: Since EPA has increased the ADT threshold to 250 in the 
final rule, there will be fewer roads which require controls under the 
FIP rule by June 2000. The June 10, 2000 deadline has not been 
established by EPA arbitrarily. As discussed in the proposed 
rulemaking, the deadline for RACM implementation after the statutory 
deadline of December 10, 1993 is as soon as practicable. 63 FR 15920, 
15926. EPA does not believe it achieves the purposes of the CAA to 
allow long-delayed RACM implementation to extend beyond June 10, 2000 
the statutory deadline for the implementation of BACM.
    Comment: MCESD, ADEQ and the City of Mesa comment that the proposed 
FIP rule's requirement that a dust control plan (DCP) for weed 
abatement be submitted 60 days in advance is impractical, given that 
there is a fire

[[Page 41339]]

endangerment concern between the time weed abatement public notices are 
issued and a 60-day lead time to submit a DCP to EPA.
    Response: In the final rule, EPA has eliminated the requirement 
that DCPs for weed abatement be submitted to EPA for approval. Instead, 
the final rule establishes RACM requirements for conducting weed 
abatement on vacant lots. The RACM are those dust control measures that 
EPA would have expected to see in a DCP. The RACM are written broadly 
enough to allow responsible parties flexibility in what measures they 
use to control dust, provided that the surface is stabilized 
immediately following weed abatement to the standards set forth in the 
rule.

Alternative Control Measures (ACMs)

    Comment: The City of Mesa comments that the provisions in the 
proposed FIP rule for ACMs are unduly burdensome (in that they must be 
submitted to EPA for approval). Rather, the City believes that if an 
ACM renders the disturbed surface area stabilized without any ancillary 
adverse impact, it should be encouraged.
    Response: EPA agrees with this comment and, in a proposed amendment 
to the final FIP rule, the Agency intends to propose that ACMs be 
listed among other RACM in each provision to which they apply. EPA 
intends to propose that as long as the ACM meets the test method's 
criteria for stabilization and does not involve use of a prohibited 
material, prior EPA approval would not be required. Thus, the only ACM 
that would be submitted to EPA would be one that does not involve 
stabilizing an unpaved surface.
    Vacant Lot RACM. Comment: The City of Phoenix comments that EPA 
should allow alternatives for controlling dust from vacant lots where 
vehicles have caused the disturbed surface in addition to posting signs 
or barriers. The City claims that these controls are required 
regardless of the severity of the disturbance or implementation of 
other dust control measures, such as gravel.
    Response: In the final FIP rule, EPA adds gravel and chemical/
organic stabilizers to the list of RACM in the ``Motor Vehicle 
Disturbances'' provision. Therefore, a vacant lot owner may comply with 
both the ``Disturbed Surfaces'' and ``Motor Vehicle Disturbances'' 
requirements by applying one control measure. Applying gravel or 
stabilizers are the only RACM specified in the rule modification since 
other control measures listed under the ``Disturbed Surfaces'' 
requirement do not ensure dust control should further vehicle trespass 
occur.
    Comment: Several commenters question the technical justification 
for a 2-inch gravel requirement, suggesting that two inches of gravel 
may not be necessary in all cases to control particulate matter 
sufficiently.
    Response: EPA has eliminated reference in the FIP rule to 2 inches 
of gravel. Since the final rule requires that gravel be applied and 
maintained to a sufficient extent necessary to result in a stabilized 
surface, the test method will be the sole indicator of whether a source 
is sufficiently graveled.
    Test Methods. Comment: MCESD and the City of Mesa comment that the 
proposed visible crust test method for vacant lots would not be 
appropriate since local native soil crusts may crumble easily and 
measure less than 0.6 centimeters in thickness, yet still form a 
protective surface. ACOC and the Salt River Project (SRP) also question 
the scientific substantiality of the proposed visible crust test 
method.
    Response: In response to comments on the FIP proposal, EPA recently 
conducted the proposed test methods on sources in the Phoenix non-
attainment area. As a result of the findings, in a forthcoming proposed 
amendment to the final FIP rule, EPA will propose a new test method for 
visible crusts that involves dropping a small steel ball from a height 
of one foot and checking for pulverization of the surface. EPA believes 
that this new method allows a higher degree of replicability than the 
existing visible crust test method and is a better indicator of whether 
the crust is sufficiently protective given variations in soils.
    Comment: Several commenters mention that the requirement in the 
proposed FIP rule that the visible opacity of vehicles be tested at a 
specific speed on unpaved roads and unpaved parking lots is impractical 
and may be unsafe/illegal.
    Response: EPA has eliminated the speed limit requirement in the 
final rule. In a forthcoming proposed amendment to the final FIP rule, 
EPA will propose a new test method for unpaved roads and unpaved 
parking lots that involves collecting a surface sample as opposed to 
conducting a visible opacity test at a certain vehicle speed.
    Comment: Several commenters suggest that the proposed test methods 
are too complex to be understood and utilized by property owners who 
must comply with the rule.
    Response: EPA has eliminated the speed limit requirements from the 
test method in the final rule. In its forthcoming proposed amendment to 
the final FIP rule, EPA will propose to eliminate the opacity test 
method for visible emissions from unpaved roads and unpaved parking 
lots. The opacity test method requires opacity readings to be taken by 
persons certified in visible emissions training. EPA agrees that this 
test method is too complex for most property owners to attempt. 
Regarding the remaining test methods in the final rule, EPA believes 
much of the perceived complexity is a result of technical language 
which is necessary to ensure the test methods are enforceable. A 
certain minimum amount of complexity is necessary to ensure that the 
test methods can be repeated by more than one individual consistently 
and accurately, as well as to ensure that they do not result in over-
controlling sources. EPA plans to provide outreach assistance to 
property owners which will explain the test methods in layman's terms 
and provide information on the commercially available resources needed 
to conduct them.
    Enforcement of FIP Rule. Comment: ACLPI states that while it 
supports EPA's proposal to provide more enforcement resources for Rule 
310, the staff provided will still be grossly inadequate. ACLPI notes 
that EPA does not explain why just two additional inspectors will be 
adequate. ACLPI states that the Governor's Air Quality Strategies Task 
Force in 1998 preliminarily recommended that the County add 9 new 
positions for Rule 310 enforcement and that, to comply with the RACM 
mandate, Maricopa County must have the same or better enforcement 
resources than other air districts which have enforcement staffs of 
such size (or larger). ACLPI also claims that EPA's proposal also fails 
to provide the legal resources necessary to enforce against violators 
detected by the inspectors and believes that the FIP should require the 
County (or EPA) to have a full time attorney to conduct enforcement 
cases under Rule 310.
    While welcoming EPA's proposal to provide additional enforcement 
resources, ACLPI urges that the Agency take steps to ensure that such 
action does not encourage continuing and repeated avoidance by the 
County of its obligation to provide these enforcement resources. ACLPI 
asserts that one appropriate step would be for EPA to impose mandatory 
or discretionary sanctions on the County for its failure to adequately 
fund Rule 310 enforcement and suggests that if this or other steps are 
not taken, local and state governments will underfund the programs and 
wait for EPA to impose a FIP that includes federal enforcement dollars.

[[Page 41340]]

    Response: EPA would like to clarify at the outset that the 
discussion in the proposed rulemaking to which ACLPI refers addressed 
the Agency's compliance approach for the proposed FIP rule, and not 
Rule 310. Thus, to the extent that ACLPI's comments are directed to the 
inadequacy of Maricopa County's program for Rule 310 enforcement, they 
are not germane to this rulemaking.24 In particular, ACLPI's 
remarks regarding inspection and enforcement resource levels for Rule 
310 are entirely inapplicable. The statistics ACLPI cites from the 
Governor's Task Force Report relate to resources for the entire 
universe of sources, both permitted and unpermitted, regulated under 
Rule 310. The scope of the FIP rule, however, is considerably narrower 
than that of Rule 310 in that it only addresses vacant lots, unpaved 
parking lots, and unpaved roads, all fugitive dust sources not 
permitted under Rule 310.25
---------------------------------------------------------------------------

    \24\ That said, EPA agrees that the resources devoted by the 
County to compliance with Rule 310 are inadequate with respect to 
unpermitted sources and made such a finding in its action on the 
State's microscale plan. 62 FR 41856, 41860. In a March 10, 1998 
letter to Al Brown, Director, MCESD, EPA stated that to replace the 
FIP rule, MCESD must submit, as a SIP revision, a credible Rule 310 
enforcement strategy that demonstrates that the County has adequate 
resources of its own to ensure that Rule 310 is fully implemented 
for all fugitive dust sources. In this regard, EPA supports the 
additional resource levels recommended by the Governor's Task Force 
and understands that MCESD is in the process of trying to obtain 
them for the purpose of fully implementing Rule 310.
    \25\ The statistics ACLPI cites on the enforcement resources of 
other air districts represent the total number of inspectors for 
each of these districts to conduct all air quality inspections for 
all pollutant sources. Therefore, these staffing levels cannot be 
used as evidence that MCESD underfunds its fugitive dust program.
---------------------------------------------------------------------------

    To the extent that ACLPI's judgments may call into question the 
adequacy of EPA's enforcement of its own rule, EPA would like to 
clarify its FIP compliance program in two respects.26 First, 
in implementing the FIP rule, EPA is constrained by the remote location 
of its Regional Office in San Francisco. Because of that constraint, 
EPA believes that its compliance program for the FIP rule will benefit 
substantially by some kind of local presence. Therefore, EPA will be 
funding two inspectors to be provided to MCESD for fiscal year 1999 
(October 1, 1998 through September 30, 1999). The primary 
responsibility of these inspectors will be to ensure compliance with 
the FIP rule.27 If the FIP rule remains in place after 
September 1999, continuation of these inspector positions will depend 
on whether additional funding can be secured by EPA.
---------------------------------------------------------------------------

    \26\ The program is discussed further in the FIP proposal at 63 
FR 15920, 15938-15939.
    \27\ Nevertheless, these two inspectors will also have the 
opportunity to identify and report Rule 310 violations. Thus they 
will be able to provide some incidental assistance to MCESD's Rule 
310 compliance efforts.
---------------------------------------------------------------------------

    Second, as discussed in the proposed rulemaking, in addition to the 
two inspectors assigned to MCESD, the Agency will have at its disposal 
legal and technical personnel from its San Francisco office to ensure 
compliance with the FIP rule by conducting periodic joint inspections 
with MCESD and undertaking enforcement actions.
    Finally, EPA is somewhat perplexed by ACLPI's suggestion that, in 
the absence of federal CAA sanctions, local and state governments will 
underfund their Rule 310 enforcement program and wait for EPA to impose 
a FIP with federal enforcement dollars. As just explained, EPA is not 
in the FIP providing either funding or positions for the benefit of 
MCESD. Moreover, it has been the Agency's experience that the specter 
of an active federal presence in local affairs acts as a powerful 
motivator, a view that ACLPI itself has historically advanced. Indeed, 
the recent adoption of State legislation regulating PM-10 emissions 
from agricultural activities is evidence of such an effect.

C. Impracticability Demonstration

    The CAA requires moderate PM-10 nonattainment areas to demonstrate 
attainment of the PM-10 annual and 24-hour standards, or to show that 
attainment by the statutory deadline is impracticable. See section 
189(a)(1)(B). For this FIP, EPA has demonstrated that existing State 
controls, together with the RACM being promulgated by EPA, are not 
sufficient for attainment of either the 24-hour or the annual PM-10 
standard by December 31, 2001.28
---------------------------------------------------------------------------

    \28\ Under CAA section 189(c)(1), the moderate area attainment 
deadline was December 31, 1994. The Phoenix nonattainment area is 
now classified as serious. As a result, for the purposes of this 
moderate area FIP and the State's serious area SIP, the attainment 
deadline is December 31, 2001. CAA section 189(c)(2).
---------------------------------------------------------------------------

1. Annual Standard
    EPA based its annual standard attainment analysis on air quality 
modeling for the 1995 year performed by the Maricopa Association of 
Governments for Phoenix serious area PM-10 plan that is currently under 
development. See 63 FR 15920, 15939.
    As can be seen in Table 2, even assuming 100 percent control for 
sources subject to the FIP rule and the commitment for the agricultural 
sector (an unrealistic level of control; actual control levels will be 
less), simulated concentrations are still over the annual standard of 
50 ``g/m\3\. Thus, pursuant to CAA section 189(a)(1)(B), EPA 
is finding that attainment of the annual PM-10 standard by December 31, 
2001 is impracticable with the implementation of RACM.

        Table 2.--Annual Standard Impracticability Demonstration        
------------------------------------------------------------------------
                               Concentration               Concentration
                                 after SIP      Maximum      after FIP  
       Source category            controls      possible      controls  
                                g/     control     g/ 
                                    m\3\       (percent)        m\3\    
------------------------------------------------------------------------
Paved road dust..............           20.   ...........           20.0
Unpaved road dust............            2.9          100            0.0
Gasoline and Diesel vehicle                                             
 exhaust.....................            1.2  ...........            1.2
Agricultural dust............            0.2          100            0.0
Other area sources...........            1.4  ...........            1.4
Residential wood combustion..            0.4  ...........            0.4
Construction/earth moving....            5.4  ...........            5.4
Construction equipment,                                                 
 locomotives, other non-road                                            
 engines.....................            1.4  ...........            1.4
Major point sources..........            0.2  ...........            0.2
Windblown dust...............            0.4          100            0.0
Anthropogenic Total..........           33.5  ...........           30.0
Background...................           22    ...........           22  
    Total....................           55.5  ...........           52.0
------------------------------------------------------------------------


[[Page 41341]]

2. 24-hour Standard
    EPA based its 24-hour standard attainment analysis on air quality 
modeling of exceedances at four monitoring sites that was performed by 
ADEQ for the microscale plan. The four monitoring sites are: (1) Salt 
River, in an industrial area; (2) Gilbert, affected by agricultural and 
unpaved parking lot fugitive dust emissions; (3) Maryvale, with 
disturbed cleared areas nearby due to construction of a park; and (4) 
West Chandler, near a highway construction project. These sites were 
selected to represent a variety of conditions within the Maricopa 
nonattainment area. See 63 FR 15920, 15939.
    The microscale plan demonstrated attainment at the Salt River and 
Maryvale sites, and EPA approved the attainment demonstrations at these 
sites at the time it took final action on the microscale plan. 62 FR 
41856, 41862. The microscale plan did not demonstrate attainment at the 
West Chandler and Gilbert sites. These sites are addressed here.
    The FIP rule requires RACM for unpaved roads, vacant lots, and 
unpaved parking lots. These sources in total contribute 25 percent of 
the emissions to the exceedance at the Gilbert site and just 1 percent 
of the emissions to the exceedance at the West Chandler site. The FIP 
rule has a substantial impact for the Gilbert site, reducing ambient 
concentrations from 213 to 176 ``g/m3 but much less 
effect at West Chandler, reducing concentrations from 332 to just 316 
``g/m3. See Table 3. Because the FIP rule does not 
result in attainment at either site, EPA is finding that attainment of 
the 24-hour standard is impracticable with the implementation of RACM.
    As can be seen from Table 3, attainment at both sites will require 
substantial reductions from agricultural sources in addition to 
reductions from unpaved roads, unpaved parking lots, and vacant lots. 
While reductions from agricultural sources are expected through the 
implementation of BMPs by 2001, EPA is unable to quantify the impact of 
these BMPs at this time because they have not yet been developed. 
Therefore it is not possible to determine an expected level of control. 
Once the BMPs have been defined, EPA will be better able to estimate 
reductions from agricultural sources and will revisit this 
impracticability demonstration for the 24-hour standard and modify the 
demonstrations as necessary.

                     Table 3--Impracticability Demonstration for the 24-hour PM-10 Standard                     
----------------------------------------------------------------------------------------------------------------
                                               Concentration after SIP                  Concentration after FIP 
                                               controls g/m3    FIP control    controls g/m3  
              Source category               ----------------------------  (percent)  ---------------------------
                                               Chandler       Gilbert                   Chandler       Gilbert  
----------------------------------------------------------------------------------------------------------------
Agricultural fields........................         194.7  ............  ...........         194.7              
Agricultural aprons........................          21.7          55.6  ...........          21.7          55.6
Road construction..........................           6.9  ............  ...........           6.9              
Unpaved roads..............................           0.5           0.5           64           0.2           0.2
Paved Roads................................           0.2           1.6  ...........           0.2           1.6
Unpaved parking lots.......................  ............          51.3           56  ............          22.6
Vacant lots................................          28.1          14.5           56          12.4           6.4
Anthropogenic Total........................         252.1         123.4  ...........         236.1          86.3
Background.................................          80            90    ...........          80            90  
                                            --------------------------------------------------------------------
    Total..................................         332.1         213.4  ...........         316.1         176.3
----------------------------------------------------------------------------------------------------------------

    See section IV.D. below for a discussion of the estimated emission 
reductions from the FIP control measures.
    EPA received a number of comments on the proposed impracticability 
demonstrations. The most significant comments have been addressed below 
and all comments have been fully addressed in the Response to Comments 
TSD.
    Comment: ACLPI comments that EPA's impracticability demonstration 
is flawed because it does not include all RACM and uses an unapproved 
state model. ACLPI asserts that EPA's failure to include so called ``de 
minimis'' measures in the FIP, as well as the other measures the Agency 
has excluded from the FIP, could very well make the difference between 
the showing of impracticability and a showing of attainment. ACLPI 
notes that under the analysis in Table 5 of the proposed rulemaking, 
the FIP measures could reduce annual PM-10 levels to 52 g/
m3--only 2 g/m3 over the standard and 
yet EPA's ``de minimis'' policy allows the Agency to avoid adopting any 
measures that produce less than 1 g/m3 in 
improvement and thus, an additional package of ``de minimis'' measures 
could well make the difference between attainment and nonattainment. 
Based on the data in Table 2 of the proposed rulemaking, ACLPI asserts 
that, combined, the ``de minimis'' sources in that table would reduce 
PM-10 by 4.0 g/m3 on an annual basis--more than 
enough to produce attainment based on the data in Table 5 of the 
Proposed rulemaking. The Center concludes that far from showing 
impracticability, EPA's analysis shows that timely attainment is 
practicable with the adoption of additional measures that are already 
identified and for which there is no reasoned justification to reject.
    Response: EPA believes that ACLPI's comment addresses only the 
impracticability demonstration for the annual standard and is 
responding to it on that basis. As noted above, EPA used the State's 
modeling as the technical basis for this FIP. As such, the modeling was 
subject to public comment as part of the FIP proposal and did not 
require a prior CAA section 110(k) approval for EPA to use it. EPA also 
demonstrated that it has included all RACM available to it in the 
impracticability demonstration. See section IV.A.
    The projected 52 g/m \3\ concentration in Table 5 of the 
proposed rulemaking assumes complete elimination of emissions from 
unpaved roads, agricultural dust, and windblown dust--an unrealistic 
level of control. See 63 FR 15920, 15939. There is currently 
insufficient information to accurately calculate regional reductions 
from the FIP measure for unpaved parking lots, vacant lots, and the 
commitment for agricultural controls. By showing that attainment would 
still not result even with 100 percent control on these sources, EPA 
was able to find that attainment of the annual standard is 
impracticable with the implementation of RACM. However, because it was 
derived from an assumption of 100

[[Page 41342]]

percent control, the projected 52 g/m \3\ annual level is too 
optimistic and the actual concentration after implementation of the FIP 
RACM will be higher.
    The total impact of all de minimis source categories combined is 
3.4 g/m \3\, or less than 10 percent of the exceedance of the 
annual PM-10 standard at the Greenwood monitor.29 Attainment 
at the Greenwood monitor would require elimination of more than half 
the emissions from these sources in addition to eliminating all 
emissions from the sources subject to the FIP measures. These de 
minimis sources include on-road motor vehicles (already subject to 
tailpipe standards, I/M, and clean fuel requirements), residential wood 
combustion (already controlled at RACM levels), all other combustion 
sources, and major point sources (already subject to RACT). No measures 
exist that could reduce emissions from these sources by more than half 
by the end of 2001, short of banning or substantially curtailing their 
operations; neither option would constitute a reasonable level of 
control. A more practicable approach to attaining the standard at 
Greenwood is to a obtain the needed emission reductions from the source 
categories that contribute significantly to the nonattainment problem 
at the Greenwood monitor, source categories such as unpaved road dust 
and paved road dust. EPA is promulgating a rule in this FIP to reduce 
emissions substantially from unpaved roads and EPA evaluated a large 
number of measures to reduce emissions from paved roads (including many 
transportation control measures) and found none that were RACM for the 
Agency.
---------------------------------------------------------------------------

    \29\ The total sum of the impact of the de minimis source 
categories listed on Table 2 of the Proposed rulemaking is 4.0 
g/m \3\; however, in this FIP both agricultural dust and 
windblown dust are considered significant sources because they are 
significant sources for the 24-hour standard. As result the total 
impact of de minimis sources at the Greenwood monitor is only 3.4 
g/m \3\.
---------------------------------------------------------------------------

D. Reasonable Further Progress Demonstrations

    As discussed in the proposal, EPA interprets the RFP requirement 
for areas demonstrating impracticability as being met by showing that 
the implementation of all RACM has resulted in incremental emission 
reductions below pre-implementation levels. See 63 FR 15920, 15927.
    RFP is demonstrated separately for the annual and 24-hour standards 
because in the Phoenix area the mix of sources contributing to the 
annual standard exceedances differs from that contributing to the 24-
hour exceedances. In addition, since PM-10 exceedances in the Phoenix 
area are related almost entirely to primarily-emitted PM-10, only 
emissions of primarily-emitted PM-10 are evaluated for RFP.
    EPA has revised the annual standard RFP demonstration from the 
proposal to reflect the changes to the FIP fugitive dust rule. Although 
EPA does not believe that annual incremental reductions are required to 
be shown for moderate PM-10 nonattainment areas demonstrating 
impracticability, EPA has also revised the RFP tables (Tables 7, 8, and 
9) from the proposal to show that the FIP does, in fact, result in 
annual incremental reductions. See section IV.D.1. below.
    EPA received a number of comments on its interpretation of the RFP 
requirement for areas demonstrating impracticability as well as on the 
specifics of the RFP demonstration. EPA responds to the most 
significant comments in section IV.D.2. below and to all comments 
received in the response to comments TSD found in the docket for this 
rulemaking.
1. Revised RFP Demonstrations
    a. Annual Standard. EPA has revised the annual standard RFP 
demonstration to account for the increased ADT threshold for controls 
on unpaved roads in the FIP fugitive dust rule. Revisions to the FIP 
rule's provisions for vacant lots or unpaved parking lots did not 
affect the annual standard RFP demonstration because no reductions were 
assumed from these sources in the proposed demonstration. The final 
annual standard RFP demonstration showing incremental reductions 
between 1998 and 2001 is presented in Table 4.
    Emission levels for 1998, 1999, 2000, and 2001 were calculated by 
growing emissions from the emission inventory base year of 1994 and the 
modeling year of 1995 based on growth factors provided by MAG and by 
incorporating reductions from approved State RACM and BACM controls. 
Emissions levels for 2000 and 2001 also reflect the estimated emission 
reductions from the FIP rule for unpaved roads. The estimated 
effectiveness of controls on unpaved roads, 80 percent, was based on 
the research done for the microscale plan on the effectiveness of 
controls for unpaved parking (see Table 4-1 in the final microscale 
plan) and assumes a rule effectiveness of 80 percent per EPA's guidance 
(57 FR 13503). EPA has not changed these estimated control and rule 
effectiveness percentages in this final demonstration; however, the 
Agency estimates that the increase in the ADT applicability threshold 
in the FIP rule will reduce the total unpaved road VMT impacted by the 
rule from 90 percent to 50 percent.
    The annual standard RFP demonstration did not include emission 
reductions from the implementation of the FIP rule for unpaved parking 
lots and vacant lots. Although emission reductions are expected from 
these sources starting in 1999, there currently is insufficient 
information on the number of unpaved parking lots and vacant lots that 
will be subject to the FIP to estimate an emission reduction. 
Information from the surveys EPA will perform after promulgation of the 
rule will help in quantifying emission reductions from these sources. 
In addition, while reductions from agricultural sources are also 
expected starting in 2000, no emission reductions were assumed in the 
RFP demonstration for agricultural sources because the ultimate RACM 
have not been defined and therefore the expected level of control 
cannot be determined. Because the reductions expected from vacant lots, 
unpaved parking lots, and agricultural sources cannot at this time be 
quantified, the showing that the FIP will result annual incremental 
reductions is necessarily qualitative.
    As can be seen in Table 4, in order to show annual reductions from 
1998 to 1999, emission reductions of more than 87 mtpy would need to 
result from the implementation of the FIP fugitive dust on vacant lots 
and unpaved parking lots. The total regional inventory for unpaved 
parking lots is currently unknown. The regional inventory for vacant 
lots, however, is estimated to be 2020 mtpy in 1999. See RFP TSD. The 
FIP rule will need to reduce emissions in this category by a little 
more than 4 percent in order to demonstrate annual incremental 
reductions. Because application of dust control measures to a disturbed 
surface is expected to reduce fugitive dust from that surface by 56 
percent (see 63 FR 15920, 15941), EPA is confident that the rule will 
achieve at least a 4 percent overall reduction in regional fugitive 
dust emissions from vacant lots sufficient to show reductions in total 
regional PM-10 emissions from 1998 to 1999. 30
---------------------------------------------------------------------------

    \30\ This conclusion is supported by noting that the estimated 
reductions from applying the FIP rule to one vacant lot for one day 
at the Chandler monitoring site is 3.5 metric tons per windy day, 4 
percent of the total annual reductions needed to show an incremental 
reduction from 1998 to 1999.
---------------------------------------------------------------------------

    As can be also be seen in Table 4, in order to show annual 
reductions from 2000 to 2001, emission reductions of more than 239 mtpy 
would need to

[[Page 41343]]

result from the implementation of the BMPs on agricultural sources. The 
projected regional inventory for agricultural sources is 6,972 mtpy in 
2001. See RFP TSD. The FIP rule will need to reduce emissions in this 
category by slightly more than 3 percent in order to demonstrate annual 
incremental reductions between 2000 and 2001. Again, EPA has every 
confidence that such minimal reductions can be achieved.

           Table 4.--RFP Demonstration for the Annual Standard          
------------------------------------------------------------------------
                                           Total PM-10 emissions metric 
                  Year                              tons/year           
------------------------------------------------------------------------
1998...................................  61,017.                        
1999...................................  61,104--reductions from vacant 
                                          lots and unpaved parking lots.
2000...................................  57,607--reductions from vacant 
                                          lots and unpaved parking lots.
2001...................................  57,846--reductions from vacant 
                                          lots, unpaved parking lots,   
                                          agricultural sources.         
------------------------------------------------------------------------

    b. 24-hour Standard. For the 24-hour standard, EPA evaluated RFP 
only for the Gilbert and West Chandler sites, having already approved 
the RFP demonstrations at the Maryvale and Salt River sites as part of 
its action on the microscale plan. 62 FR 41856, 41862.
    Changes to the FIP fugitive dust rule do not affect the emission 
reductions assumed in the proposed RFP demonstrations for the 24-hour 
standard because the rule will continue to apply in the same manner and 
to the same extent as was assumed in the proposal. In other words, the 
changes to the FIP rule do not affect its application to the sources 
surrounding the Gilbert and West Chandler sites.
    As with the annual standard demonstration, 1998 emission levels 
were adjusted to reflect implementation of the improved controls on 
construction sources and 2001 emissions levels to reflect the estimated 
emission reductions from the proposed FIP rule for unpaved roads, 
unpaved parking lots, and vacant lots. Emission reductions estimates 
are again based on the research done for the microscale plan and assume 
a rule effectiveness of 80 percent per EPA's guidance. For unpaved 
roads, a control effectiveness of 80 percent is assumed. For vacant 
lots and unpaved parking lots, a control effectiveness of 70 percent is 
assumed. As with the annual standard, no emission reductions were 
assumed for agricultural sources. A more detailed analysis of the RFP 
demonstrations for the Gilbert and West Chandler monitors can be found 
in the RFP TSD.
    i. Gilbert Monitoring Site. The 24-hour exceedances at the Gilbert 
monitor are impacted by emissions from agricultural aprons, disturbed 
cleared lands (i.e., vacant lots), unpaved parking lots, and paved 
roads. 62 FR 31025, 31031. As can be seen from Table 5, the emission 
reductions from the FIP rule and commitment for unpaved parking lots 
and vacant lots and agricultural sources are sufficient to assure 
incremental emission reductions between 1998 and 2001 and annual 
incremental reductions 31 in the interim years. EPA, 
therefore, finds that the FIP assures RFP for the 24-hour standard at 
the Gilbert monitor.
---------------------------------------------------------------------------

    \31\ While there is no change in total emissions from 1999 to 
2000, EPA believes that annual incremental reductions are still 
shown because of the large reduction occurring in the early years 
between 1998 and 1999.

                                      Table 5.--RFP Demonstration for the 24-hour Standard--Gilbert Monitoring Site                                     
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                      Emissions(kg/day)                                 
        Source categories                FIP control (%) year      -------------------------------------------------------------------------------------
                                                                        1998         1999         2000                          2001                    
--------------------------------------------------------------------------------------------------------------------------------------------------------
Agriculture aprons...............  0 (2001).......................          165          165          165  165 (-reductions from BMPs).                 
Vacant lots......................  0.56 (1999)....................           76           33           33  33.                                          
Unpaved parking lots.............  0.56 (1999)....................          190           84           84  84.                                          
Paved roads......................  0..............................            5            5            5  5.                                           
                                  ----------------------------------------------------------------------------------------------------------------------
    Total........................  ...............................          436          287          287  287 (-reductions from BMPs).                 
--------------------------------------------------------------------------------------------------------------------------------------------------------

    ii. West Chandler Monitoring Site. The 24-hour exceedances at the 
West Chandler monitor are impacted by emissions from agricultural 
fields, agricultural aprons, road construction, disturbed cleared lands 
(i.e., vacant lots), unpaved roads, and paved roads. 62 FR 31025, 
31032. As can be seen from Table 6, the emission reductions from the 
FIP rule for unpaved roads and vacant lots and and the commitment for 
controls on agricultural sources are sufficient to assure incremental 
emission reductions between 1998 and 2001 and annual incremental 
reductions in the interim years; therefore, EPA finds that the FIP 
assures RFP for the 24-hour standard at the West Chandler monitor.

                                   Table 6.--RFP Demonstration for the 24-hour Standard--West Chandler Monitoring Site                                  
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                    Emissions (kg/day)                                  
         Source category               FIP control (%) Year      ---------------------------------------------------------------------------------------
                                                                      1998         1999         2000                           2001                     
--------------------------------------------------------------------------------------------------------------------------------------------------------
Agriculture.....................  0 (2001)......................        19378        19378        19378  19378 (-reductions from BMPs).                 
Vacant lots.....................  0.56 (1999)...................         6188         2723         2723  2723.                                          
Road Construction...............  0.............................          440          440          440  440.                                           
Agricultural apron..............  0 (2001)......................         1954         1954         1954  1954 (-reductions from BMPs).                  
Unpaved road....................  0.64 (2000)...................           49           49           18  18.                                            
Paved roads.....................  0.............................           37           37           37  37.                                            
                                 -----------------------------------------------------------------------------------------------------------------------
    Total.......................  ..............................        28046        24581        24550  24550 (-reductions from BMPs).                 
--------------------------------------------------------------------------------------------------------------------------------------------------------


[[Page 41344]]

2. Response to Comments on the RFP Demonstration
    EPA has responded to the most significant comments on the proposed 
RFP demonstration below. The TSD contains EPA's response to all 
comments received.
    Comment: ACLPI asserts that section 172(c)(2) of the Act 
specifically requires all nonattainment area SIPs to show RFP, and that 
both the Act and longstanding EPA guidance require that, to satisfy the 
RFP requirement, plans must provide for annual reductions in total 
emissions sufficient to produce steady progress toward attainment on a 
straight line basis or faster, citing CAA section 171(1) and 59 FR 
41988, 42016 (August 16, 1994); 52 FR 45044, 45066 (November 24, 1987); 
46 FR 7182, 7185 (January 22, 1981); EPA, Guidance Document for 
Correction of Part D SIP's for Nonattainment Areas (January 27, 1984). 
ACLPI disagrees with EPA's claim that for moderate areas demonstrating 
impracticability, the Act's RFP requirement is met by a showing that 
implementation of all RACM will result in ``incremental emission 
reductions below pre-implementation levels.'' ACLPI asserts that the 
Act does not in any way waive the RFP requirement for moderate PM-10 
areas claiming impracticability and explicitly sets out RFP as a 
requirement separate, distinct and in addition to RACM, comparing 
section 172(c)(1)(RACM) with section 172(c)(2)(RFP). ACLPI claims that 
EPA's reading of the RFP requirement for areas demonstrating 
impracticability would render the RFP mandate a mere redundancy, a 
result that is contrary to well-settled rules of statutory 
construction, citing N.J. Singer, 2A Statutes & Statutory Constr. 
Sec. 46.06 at 119-20 (1992 Rev.).
    Response: EPA agrees with ACLPI that the RFP requirement in section 
172(c)(2) is a separate and distinct requirement for nonattainment 
plans that is in addition to the requirement for RACM in section 
172(c)(1). It also agrees that all nonattainment plans must address the 
RFP requirement, including moderate area PM-10 plans demonstrating 
impracticability. EPA has not waived the RFP requirement and has fully 
addressed it in this FIP. See section IV.D.1. Section 171(1) of the CAA 
defines RFP as:

    [S]uch annual incremental reductions in emissions of the 
relevant air pollutant as are required by [Part D of title I of the 
Clean Air Act] or may reasonably be required by the Administrator 
for the purpose of ensuring attainment of the applicable national 
ambient air quality standard by the applicable date.

    As seen from this definition, the adequacy of the emission 
reductions required to demonstrate RFP is inextricably linked to the 
reductions necessary to ensure attainment and thus to the control 
strategy necessary for attainment. Because of this interconnection, EPA 
has historically required RFP to be demonstrated by showing that 
nonattainment plans provide for annual incremental emission reductions 
sufficient generally to maintain at least linear progress toward 
attainment by the applicable attainment deadline. See, e.g., 43 FR 
21673, 21675 (May 19, 1978), Criteria for Proposing approval of 
Revisions to [1979] Plans for Nonattainment Areas; 46 FR 7185 (January 
22, 1981), Approval of 1982 Ozone and Carbon Monoxide Plan Revisions 
for Areas Needing an Attainment Date Extension [under CAA section 
172(a)(2)]; 59 FR 41988, 42016 (August 16, 1994), State Implementation 
Plans for Serious PM-10 Nonattainment Areas. As described, for example, 
in the 1978 guidance document, the required linear reductions were 
represented graphically as a straight line drawn from the base year 
(i.e., the submittal year for the plan) emission inventory to the 
allowable emissions in the attainment year. RFP was shown if the annual 
emission reductions were sufficient to produce this ``straight-line 
rate.'' 32 See 43 FR 21675.
---------------------------------------------------------------------------

    \32\ This requirement for reductions on a ``straight-line rate'' 
has never been absolute. EPA has stated that it would accept less 
than a straight-line rate if the State could show that a lag was 
necessary to accommodate the time required for compliance. See 43 FR 
21675 and 44 FR 20372, 20377 (April 4, 1979). EPA has also noted 
that in certain situations, such as where there are a limited number 
of sources contributing to the nonattainment problem, where 
requiring linear progress reductions in PM-10 emissions to maintain 
RFP is less appropriate and in such situations an expeditious 
compliance schedule can be used to demonstrate RFP. See 59 FR 41998, 
42015.
---------------------------------------------------------------------------

    Since this straight-line rate demonstration requires a 
determination of the emission reductions needed for attainment, the 
guidance documents requiring linear progress for RFP in nonattainment 
plans has always been predicated on the existence of a concurrent 
statutory requirement that the nonattainment plan also demonstrate 
attainment. These guidance documents, however, provide little help in 
determining how RFP is to be demonstrated when a nonattainment plan is 
statutorily allowed not to demonstrate attainment, as is the case with 
certain moderate area PM-10 plans.
    Moderate area PM-10 plans demonstrating impracticability do not 
include a projection of the allowable emissions in the attainment year. 
Attainment projections for such areas are not required until submittal 
of the subsequent serious area plan. Thus, for moderate plans 
demonstrating impracticability, it is not possible to determine the 
linear rate of reductions required under the RFP guidance for plans 
demonstrating attainment because the line's end point, the allowable 
attainment level, is missing. Put simply, EPA's previous interpretation 
of and guidance for the RFP requirement in the Act do not work in areas 
demonstrating impracticability. In such a situation, it is necessary 
and appropriate to amend the previous guidance.33
---------------------------------------------------------------------------

    \33\ Under CAA section 193, guidance issued by EPA prior to the 
1990 CAA Amendments remain in effect except to the extent that it is 
inconsistent with any provision of the revised Act or is revised by 
the Administrator. As will be seen, EPA has both found that its 
previous RFP guidance requiring linear emission reductions is 
inconsistent with the statutory provisions allowing demonstration of 
impracticability for moderate PM-10 areas and revised that guidance 
for such areas.
---------------------------------------------------------------------------

    EPA issued preliminary guidance on interpreting the RFP requirement 
for moderate PM-10 areas demonstrating impracticability in its final 
approval of the Phoenix moderate area PM-10 plan, noting that the 
guidance was intended to clarify the confusion created by omissions in 
the Act and in prior EPA guidance. See 60 FR 18010, 18013 (April 10, 
1995). In that notice, EPA stated that RFP was demonstrated by showing 
that the implementation of all RACM has resulted in ``incremental 
reductions'' in emissions of PM-10. EPA clarified and further explained 
this guidance in its proposal to restore the Agency's approval of the 
Phoenix moderate area plan. See 61 FR 54972, 54973. As quoted above, 
RFP is defined in section 171(1) as either annual incremental 
reductions as are required under part D, or such reductions as the 
Administrator may reasonably require ``for the purpose of ensuring 
attainment of the [NAAQS] by the applicable date.'' In moderate PM-10 
area plans demonstrating impracticability, there is no demonstration of 
attainment, simply a demonstration that, even after the implementation 
of all RACM, it is impracticable for the area to attain the PM-10 
standard by the applicable attainment deadline. Once EPA has determined 
that all reasonable control measures that are available have been 
implemented and timely attainment still will not occur, there are no 
further reductions that it would be reasonable to require ``for the 
purpose of ensuring attainment'' by the applicable attainment deadline. 
Thus, the emissions reductions achieved through

[[Page 41345]]

implementation of all RACM, by definition, would satisfy the 
requirement to demonstrate reasonable further progress in the period 
before the Act requires a new plan that includes the additional 
measures needed to produce the net emissions reductions required for 
attainment.
    Moreover, EPA's interpretation is reasonable given the Act's scheme 
for PM-10 attainment. Among all the Act's numerous nonattainment 
requirements, the moderate area PM-10 provisions are unique in 
tolerating a planned failure to demonstrate attainment and deferring 
the obligation to demonstrate attainment to a later plan. EPA's 
interpretation of the general RFP requirement in section 172(c)(2), as 
it applies to moderate PM-10 areas demonstrating impracticability, must 
not only meet the Act's definition of RFP but must also be consistent 
with the statutory scheme for PM-10 attainment. For the reasons stated 
above, EPA believes that its interpretation of the RFP requirement for 
areas demonstrating impracticability is consistent with this scheme. 
Requiring RFP demonstrations to show emission reductions in excess of 
those resulting from the implementation of all RACM would conflict with 
the CAA section 189(a)(1)(B)(ii) provision for demonstrating 
impracticability.\34\
---------------------------------------------------------------------------

    \34\ EPA's approach is consistent with the rule, long 
articulated by the Ninth Circuit, that ``language in one section of 
the statute [is to be interpreted] consistently with the purposes of 
the entire statute considered as a whole.'' Adams v. Howerton, 673 
F.2d 1036, 1040 (9th Cir.), cert. denied, 458 U.S. 1111 (1982). See 
also In re Arizona Appetito's Stores, Inc., 893 F.2d 216, 219 (9th 
Cir. 1990) (courts to adopt interpretation that is harmonious with 
the statute's scheme and general purposes).
---------------------------------------------------------------------------

    Finally, this entire discussion is somewhat academic in the case of 
this FIP where the expeditious application of RACM not only results in 
incremental emission reductions below pre-implementation levels, but 
also in annual incremental reductions for both the 24-hour and annual 
PM-10 standards. See section IV.D.1.
    Comment: In its 1996 comments (which the Center requested be 
incorporated into its comments on the April 1, 1998 PM-10 FIP 
proposal), ACLPI argues that EPA wrongly suggests that the Act's RFP 
mandate disappears after the applicable attainment date has passed and 
does not reappear until the state submits a new SIP to meet a new 
attainment deadline. The Center asserts that under this view, a state 
that is delinquent in meeting an attainment deadline can actually do 
less to move toward attainment than an area that has yet to miss a 
deadline. Given that the whole purpose of the RFP mandate is to assure 
steady progress toward clean air, ACLPI argues that the purpose becomes 
even more urgent when an area is continuing to violate standards and 
that EPA's position is comparable to that rejected by the Court in 
Delaney v. EPA, 898 F.2d 687 (9th Cir. 1990). In addition, ACLPI argues 
that the approach proposed by EPA could not be more antithetical to the 
language and purpose of the CAA and that under such an approach, EPA 
could approve a SIP that will actually allow air quality to worsen 
since the SIP need only slow the rate of emissions growth until the 
attainment deadline but after the attainment deadline, the SIP need not 
even slow the rate of emissions growth and emissions can grow at any 
rate. ACLPI asserts that it is inconceivable that Congress intended a 
result so contrary to the public health goals of the Act, or to the 
plain meaning of the phrase, ``reasonable further progress.''
    Response: As stated above, the RFP mandate in the Act is intended 
to ensure that nonattainment plans provide for reasonable progress 
toward attainment by the applicable attainment date, as is clear from 
the plain language of the RFP definition in section 171(1) of the Act. 
As is apparent from that language, RFP, as the term is used in the CAA, 
applies only in the period prior to the applicable attainment date and 
does not continue in the period after that date.
    ACLPI purports to invest in the RFP mandate the solution to all 
potential problems with implementation plans, from delinquent plans and 
failure to actually attain the standards, to increasing emissions after 
attainment dates have passed. This all-encompassing view of the RFP 
mandate ignores the provisions of the Act that Congress added to 
specifically address each of these situations: the section 179(a) 
sanctions and section 110(c) federal plan requirements for addressing 
delinquent or inadequate plans; the reclassification requirements of 
sections 181(b)(2), 186(b)(2), and 188(b) (with their accompanying 
requirements for new plans in sections 182, 187, and 189) and the 
mandatory rate of progress requirements in sections 187(g) and 189(d) 
for addressing continuing violations after the serious area attainment 
date has passed; the requirement for contingency measures in section 
172(c)(9) to assure additional emission reductions after an area fails 
to attain but before a new plan is submitted to prevent emissions 
growth; and the maintenance plan requirements in section 175(A) to 
assure limits on emissions growth to prevent violations of the standard 
in areas redesignated to attainment.\35\
---------------------------------------------------------------------------

    \35\ In light of the new statutory provisions in the 1990 Clean 
Air Act Amendments, ACLPI's comment that EPA's position is 
comparable to that rejected by the Ninth Circuit in Delaney is 
inapposite. In that case, the Court was addressing the consequences 
of a lapsed attainment deadline in the absence of any related 
statutory provisions. In the 1990 Amendments, Congress provided 
specific actions to be undertaken should such a lapse occur.
---------------------------------------------------------------------------

    Given that there are other specific CAA provisions that address the 
hypothetical scenarios ACLPI envisions, there is no basis for invoking 
the general RFP provision as a gap-filling, all-purpose remedy for 
them. EPA's interpretation of the section 172(c)(2) RFP requirement as 
set forth in the FIP is consistent with the statutory purpose of 
achieving regular emission reductions as needed to assure attainment by 
the applicable attainment date.
    Comment: ACLPI comments that the Act's reclassification scheme does 
not support EPA's RFP approach because the purpose of reclassification 
is to prompt adoption of more stringent controls and not an excuse to 
bring progress to a stop.
    Response: EPA does not claim that the reclassification scheme 
supports its RFP approach. Equally, the reclassification scheme does 
not support ACLPI's proposition that the RFP requirement should apply 
after an applicable attainment date. As noted previously, the plain 
language of the RFP definition clearly indicates that RFP is only 
required in the period before the applicable attainment date and not 
after it has passed. As also noted previously, the CAA provision 
intended to address progress between a lapsed attainment date and the 
submittal of a revised nonattainment plan with its new RFP 
demonstration is the contingency measures provision in section 
172(c)(9).
    Comment: ACLPI claims that EPA's RFP analysis for the proposed FIP 
is flawed in several other key respects. First, ACLPI asserts that it 
is based on an emissions inventory that is not complete, current, and 
accurate, as required by the Act. ACLPI states that the inventory 
submitted by the state in connection with its 1991/1993 PM SIP revision 
showed vehicular exhaust as constituting 36 percent of total PM-10 
emissions (ADEQ, Final State Implementation Plan Revision, Revised 
Chapter 9 (Feb. 1994) p. 9-34) and in contrast, the inventory relied on 
in EPA's current RFP demonstration shows the same sources as amounting 
to only 8 percent of the inventory and that EPA offers no rational 
explanation for this glaring disparity. ACLPI notes that the State's 
prior inventory was based on

[[Page 41346]]

actual speciated monitoring data from the Phoenix area and that EPA's 
inventory appears to based on theoretical emission factors and 
speculation.
    Response: EPA based its RFP analysis for the proposed FIP on the 
1994 regional emission inventory prepared by MAG (see 1994 Regional PM-
10 Emission Inventory for the Maricopa County Nonattainment Area, Draft 
Final Report, MAG, May 1997) and additional inventory work prepared for 
the regional PM-10 modeling (see Technical Support Document for the 
Regional PM-10 Modeling in Support of the 1997 Serious Area PM-10 Plan 
for Maricopa County Nonattainment Area, Draft, MAG, October 1997). 
These inventories were prepared following the procedures in EPA 
guidance, using either EPA emission factors or other appropriate 
emission factors and Phoenix-specific activity data.
    It is not valid to conclude from the mere fact that this inventory 
differs in its apportionment of sources from the inventory in the 1991/
93 PM SIP that the regional 1994 inventory is inherently flawed. 
Inventories prepared at different times will naturally vary because 
improved methodologies are developed, new information about sources is 
collected, control measures are implemented, and emission growth rates 
vary across categories. All these factors tend to affect the percentage 
presence of a source category from inventory to inventory. Because it 
is the nature of inventories to change over time, EPA does not normally 
require new inventories to be reconciled against previous ones and any 
differences between them explained.
    The inventory in the 1991/93 PM-10 Plan referred to by ACLPI is the 
regional inventory modified (``normalized'') to reflect a 1989-1990 
source apportionment at three urban Phoenix monitors: Central Phoenix, 
West Phoenix, and South Scottsdale. 36 This source 
apportionment was performed using Chemical Mass Balance (CMB) modeling 
and monitored speciated data. As work has been done to evaluate the 
nature of the PM-10 problem in Phoenix, it has become increasing clear 
that PM-10 exceedances in the Phoenix area often have highly localized 
causes. In other words, the sources that contribute substantially to an 
exceedance are often located close to the exceeding monitor. As a 
result, any inventory that is developed based on the source 
apportionment from a given monitor or small set of similar monitors is 
only truly informative about the relative significance of sources 
around those monitors rather than about the relative significance of 
sources in a regional inventory.
---------------------------------------------------------------------------

    \36\ Strictly speaking, this normalized inventory is not an 
emission inventory at all, but merely the percent source 
contributions at a monitor multiplied by the total regional 
inventory as calculated by emission factors and source activity 
levels.
---------------------------------------------------------------------------

    Phoenix has a large number of fugitive dust sources such as 
construction sites, vacant lots, unpaved roads, and agricultural 
fields. Emissions from these sources need to be included in any 
regional inventory. However, as noted in EPA's proposed action on the 
microscale plan, fugitive dust PM-10 has more localized effects than 
other criteria pollutants because it is emitted near ground level and 
has relatively sharp spatial concentration gradients as dust settles 
out with distance from the emitting source. See 62 FR 31025, 31030. 
Consequently, it would be surprising to see a substantial contribution 
from fugitive dust sources at urban monitors where there were 
relatively few of these fugitive dust sources close by. The source 
apportionment at such monitors is much more likely to be influenced by 
local sources such as paved road dust and by fine particulate sources, 
such as vehicle exhaust, which tend to remain suspended in ambient air 
longer. This is exactly the source apportionment seen at the three 
urban monitors used to generate the 1991/93 Plan's normalized 
inventory. As a result, it is not surprising to see that the 1991/93 
Plan's normalized inventory skewed toward paved road dust and vehicle 
exhaust and away from fugitive dust. Basing the regional inventory on 
the source apportionment at urban monitors, however, will underestimate 
regional fugitive dust emissions. This underestimation is illustrated 
in the 1991/93 Plan's normalized inventory in which fugitive dust 
sources account for only 3 percent of the total regional PM-10 
emissions.
    Source apportionment at a monitor is a necessary part of preparing 
a PM-10 attainment demonstration because without a clear understanding 
of the relative contributions of sources causing an exceedance, it is 
impossible to know how controls will affect air quality.37 
But in preparing a regional inventory for an area as large and as 
diverse as Phoenix, with its many fugitive dust sources, source 
apportionment based on just a few urban monitors is unlikely to result 
in a regional inventory that correctly accounts for fugitive dust 
emissions.
---------------------------------------------------------------------------

    \37\ In the 1991/93 Plan, the primary purpose of the normalized 
inventory was to evaluate the effects of controls for the 
impracticability demonstration. See 1991/93 Plan, p. 9-39.
---------------------------------------------------------------------------

    Comment: ACLPI also asserts that EPA failed to accurately address 
growth in PM-10 emissions from vehicular exhaust. ACLPI notes that the 
Agency's inventory shows on-road exhaust emissions of PM-10 steadily 
decreasing from 1610 tpy in 1995 to 1037 tpy in 2001, but cites a MAG 
conformity analysis that shows vehicle exhaust emissions of PM-10 
increasing to 8,807 tpy (based on 24.13 tpd) by 2001. ACLPI argues that 
increased emissions are consistent with projected increases in VMT and 
with the lack of additional controls to limit motor vehicle emissions 
of PM-10 and that EPA cannot justify reliance on an inventory that 
shows decreasing motor vehicle emissions when this conflicts with 
reality.
    Response: The MAG conformity analysis is performed using an out-of-
date mobile source emissions model, the 1985 Particulate Model. See 
Conformity Analysis, MAG Long Range Transportation Plan Summary and 
1997 Update [and] MAG 1998-2002 Transportation Improvement Program, 
MAG, November 1997, p. 1-21. MAG uses this model in its conformity 
determinations in order to be consistent with the model used in the 
State's 1991/93 moderate area plan. In 1994, EPA released the PART5 
mobile source model for use in SIPs. As recommended by EPA guidance, 
the base and projected exhaust emission inventories in the FIP were 
developed using the PART5 model. See PM-10 Emission Inventory 
Requirements, OAQPS, EPA (EPA-454/R-94-033), September 1994, p. 14. The 
PART5 model changed the estimates of emissions from on-road motor 
vehicles. The difference between the conformity and FIP inventories is 
partly related to this change in emission models.
    The difference between the two inventories is also the result of 
the use of the normalized inventory from the 1991/93 PM-10 Plan in the 
conformity analysis. Again, MAG uses the normalized inventory to be 
consistent with the submitted PM-10 SIP. See Conformity Analysis, p. 1-
20. As discussed in the previous response, this normalized inventory 
substantially increased the vehicle exhaust portion of the inventory 
based on the source apportionment at three urban monitors. This 
normalized inventory does not accurately reflect the contribution of 
fugitive dust sources to the regional inventory and probably overstates 
vehicle exhaust emissions.
    Because the motor vehicle exhaust inventory in the MAG conformity 
analysis and the inventory in the FIP

[[Page 41347]]

were developed using substantially different methodologies and 
assumptions, the inventories are not comparable. As a result, it cannot 
be said that motor vehicle emissions are increasing from 1610 mtpy to 
8,807 mtpy as ACLPI claims.38 The motor vehicle exhaust 
inventory used in the FIP was based on the EPA's latest emission model 
and regional estimates of emissions and, as a result, EPA believes that 
it is the best inventory currently available.
---------------------------------------------------------------------------

    \38\ When projected 2001 emissions are estimated using the same 
methodology as used in the 1991/93 plan, motor vehicle exhaust PM-10 
emissions are projected to decline from 13,410 mtpy in 1989 (1991/93 
Plan, p. 9-41, figure converted to mtpy from english tpy) to 8,807 
mtpy in 2001 (Conformity Analysis, p. 6-3).
---------------------------------------------------------------------------

    Contrary to ACLPI's assertions, it is not surprising to see 
decreases in tailpipe PM-10 emissions despite the increases in VMT and 
the apparent lack of additional new control measures. This decline in 
emissions despite the substantial increase in VMT is due primarily to 
fleet turnover that brings cleaner cars into the fleet to replace 
older, dirtier ones and implementation of control programs such as I/M 
and clean fuel requirements. Decreasing motor vehicle emissions, in 
fact, reflects the reality of almost three decades of successful 
technological controls on motor vehicles.
    Comment: ACLPI states that the RFP demonstration does not show 
annual emission reductions--it only purports to show reductions in the 
year 2001.
    Response: As discussed above, EPA does not believe that annual 
emission reductions are necessary to demonstrate RFP in areas 
demonstrating the impracticability of attaining the PM-10 standard. 
However, EPA has qualitatively shown that this FIP should result in 
annual emission reductions from the 1998 promulgation until the 
December 31, 2001 attainment date.

E. Indian Reservations

    As discussed in EPA's proposed FIP, there are two Indian 
reservations (the Salt River Pima-Maricopa Indian Community and the 
Fort McDowell Mojave-Apache Indian Community) and a portion of a third 
reservation (the Gila River Indian Community) in the Phoenix PM-10 
nonattainment area. The FIP measures do not cover sources on these 
reservations. See 63 FR 15920, 15941. EPA received comments from the 
Salt River Pima-Maricopa Indian Community supporting EPA's proposal and 
reiterating their willingness to work with EPA under the EPA's Tribal 
Authority Rule which became effective on March 16, 1998.

V. Administrative Requirements

A. Executive Order (E.O.) 12866

    Under Executive Order 12866, 58 FR 51735 (October 4, 1993), the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to Office of Management and Budget (OMB) review 
and the requirements of the Executive Order. The Order defines 
``significant regulatory action'' as one that is likely to result in a 
rule that may:

    (1) have an annual effect on the economy of $100 million or more 
or adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or tribal governments or 
communities;
    (2) create a serious inconsistency or otherwise interfere with 
an action taken or planned by another agency;
    (3) materially alter the budgetary impact of entitlements, 
grants, user fees, or loan programs or the rights and obligations of 
recipients thereof; or
    (4) raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.

    Due to potential novel policy issues this action is considered a 
significant regulatory action and therefore must be reviewed by OMB. 
Changes made in response to OMB suggestions or recommendations will be 
documented in the public record.

B. Regulatory Flexibility Analysis

1. Regulatory Flexibility Act Requirements
    Under the Regulatory Flexibility Act (RFA), 5 U.S.C. section 601 
et. seq., EPA must prepare a regulatory flexibility analysis assessing 
the impact of any proposed or final rule on small entities unless EPA 
certifies that the rule will not have a significant economic impact on 
a substantial number of small entities. 5 U.S.C. 603, 604 and 605(b). 
Small entities include small businesses, small not-for-profit 
enterprises, and government entities with jurisdiction over populations 
of less than 50,000.
    For the purposes of this inquiry, as it applies to the two proposed 
federal measures, the fugitive dust rule and the commitment for the 
development and implementation of RACM for the agricultural sector, EPA 
is assuming that the affected or potentially affected sources 
constitute ``small entities'' as defined by the RFA.
    The final federal measures are intended to fill gaps in the Arizona 
PM-10 SIP for the Phoenix nonattainment area. For non-agricultural 
fugitive dust sources, while the County has adopted and EPA has 
approved Rule 310 into the SIP, the County has not made a commitment to 
provide adequate resources to ensure enforcement of the rule as it 
applies to the unpaved road, unpaved parking lot and vacant lot source 
categories.39 Further, application of Rule 310 to 
agricultural sources including fields and aprons is affected by the 
provision in section 102 (incorporating A.R.S. 49-504.4) that states 
that the rule ``shall not be construed so as to prevent normal farm 
cultural practices.'' Therefore, applicability of the rule to such 
sources depends on what dust-generating operation is occurring at the 
source. In other words, Rule 310 applies to some operations on 
agricultural fields and aprons and not to others.
---------------------------------------------------------------------------

    \39\ The County typically only ensures compliance with Rule 310 
for these sources on a complaint basis.
---------------------------------------------------------------------------

    2. RFA Analysis
    a. Federal Rule for Unpaved Roads, Unpaved Parking Lots, and Vacant 
Lots. The starting point for EPA's analysis is Maricopa County's Rule 
310. Regardless of the County's resources for enforcing the rule with 
respect to nonagricultural fugitive dust sources, those sources are 
legally responsible for complying with it. Failure to do so subjects 
such sources to potential enforcement action by EPA, the State, County 
and/or citizens. Thus, for the purpose of analyzing whether the 
proposed FIP rule will have ``a significant economic impact,'' EPA 
assumes that sources subject to the rule are complying with it. The 
appropriate inquiry then is whether the terms of EPA's proposed rule 
would impose a significant economic impact beyond that imposed by the 
terms of Rule 310.
    Section 101 of Rule 310 states that the purpose of the rule is 
``[t]o limit the emission of particulate matter into the ambient air 
from any property, operation or activity that may serve as an open 
fugitive dust source.'' Further, the provisions of the rule ``apply to 
any activity, equipment, operation and/or man-made or man-caused 
condition or practice * * * capable of generating fugitive dust. * * 
*'' Sections 305, 306, 309 and 312 of the rule contain the regulatory 
requirements applicable to the following source categories: vehicle use 
in open areas and vacant parcels, unpaved parking areas, vacant areas, 
and roadways. These requirements differ to some extent depending on the 
source category, but generally they mandate the implementation of RACM 
before certain dust-producing activities can be undertaken. RACM is 
defined in section 221 as ``[a] technique, practice, or procedure used 
to prevent or

[[Page 41348]]

minimize the generation, emission, entrainment, suspension and/or 
airborne transport of fugitive dust.'' As further defined in subsection 
221.1, and as pertinent to this analysis, RACM include, but are not 
limited to: curbing, paving, applying dust suppressants, and/or 
physically stabilizing with vegetation and gravel.
    While subsection 211.1 does not specify which of the listed 
measures are appropriate for what types of source categories, the 
general definition of RACM in section 221 together with the list of 
RACM measures in subsection 211.1 provide a basis for selecting 
measures which are appropriate for a particular source to prevent or 
minimize dust emissions, to the extent other provisions of Rule 310 do 
not specify a particular RACM measure.
    EPA's final fugitive dust rule is intended to establish a RACM 
requirement for unpaved parking lots, unpaved roads and vacant lots 
that is substantively equivalent to that established for the same 
sources by the Maricopa County rule. As noted above, the requirements 
of the County rule differ to some extent depending on the source 
category; EPA's proposed rule mirrors those differences. The primary 
difference between the County rule and EPA's final rule is that the EPA 
rule provides greater specificity and detail regarding which RACM are 
appropriate for a particular source category for the purpose of 
preventing or minimizing fugitive dust emissions.40
---------------------------------------------------------------------------

    \40\ EPA believes that it is reasonable and appropriate for its 
rule to be more specific and detailed than the County rule. As a 
result of the State's failure to commit sufficient enforcement 
resources for its rule, EPA is having to fulfill the role of primary 
enforcer of the RACM requirement for the sources described above. 
EPA Region 9 will be responsible for fulfilling that role, and it is 
located in San Francisco. Given the greater difficulties that Region 
9 will inevitably face in enforcing the RACM requirement in Arizona, 
it is reasonable for EPA to design a RACM rule that ensures EPA 
enforcement of the rule will be practicable. As described above, the 
County rule provides a general basis for determining which RACM 
should be applied to which source categories. But its lack of 
specificity makes it more likely that the agency enforcing the rule 
will routinely be called upon to address which RACM should be 
applied to which source categories. By addressing this issue in the 
FIP rule itself, EPA hopes to reduce the extent to which sources and 
others may have to consult with the Agency to determine which RACM 
are appropriate for a particular source or source category.
---------------------------------------------------------------------------

    In providing further specificity and detail, EPA's rule does not 
change the nature of the RACM requirement already applicable to sources 
covered by County Rule 310. The RACM required to be applied in the 
final FIP rule are the very measures listed in subsection 211.1 of Rule 
310. Beyond that, the RACM specified in the final rule for any 
particular source category are the appropriate RACM for that source 
category. What constitutes RACM for the source categories covered by 
the final FIP rule is relatively straightforward in light of the 
differences among the source categories, the low technology nature of 
the potential RACM and other available information. EPA therefore 
believes that its further specification of the RACM requirements does 
not change the nature of the RACM requirements already applicable under 
Maricopa County Rule 310 which is federally enforceable as an approved 
element of the Arizona SIP.
    The only other notable difference between the County rule and the 
final FIP rule that is relevant to this analysis is paragraph (f) of 
the proposed FIP rule. Rule 310 contains a recordkeeping requirement 
for permitted dust-generating activities, but does not contain such a 
requirement for unpermitted activities, including unpaved parking lots, 
unpaved roads and vacant lots. Therefore, paragraph (f) of the proposed 
FIP rule includes a requirement that owners/operators subject to the 
rule maintain records demonstrating appropriate application of RACM. 
EPA has determined that the recordkeeping requirements for the source 
categories covered in the FIP rule will not have a significant economic 
impact. In many cases, the owner/operator need only retain a purchase 
receipt or contractor work order for the control(s) implemented. When 
chemical stabilization is applied as a control measure, more specific 
information regarding the product being used is required. However, this 
information (e.g., type of product, label instructions) is readily 
available from vendors or easily determined at the time of application. 
EPA expects that the information the final FIP rule requires sources to 
keep will be retained by source owners or operators in any event in the 
normal course of business (e.g., for tax and accounting purposes).
    EPA's final fugitive dust rule incorporates a number of changes 
made in response to the public comments that EPA received on the FIP 
proposal. Those changes are summarized and discussed in section IV.B.2. 
above and in the TSD. The net result of the substantive changes is to 
provide sources with greater flexibility than provided in the FIP 
proposal and Rule 310. For example, the final FIP rule includes an 
increase from 0.10 acre to 0.50 acre in the de minimis disturbed 
surface area level for vacant lots; an increase from 150 to 250 ADT in 
the exemption level for unpaved roads; a new de minimis use level for 
unpaved parking lots; and the elimination of the DCP requirement for 
weed abatement. As a result of these and other changes, the 
requirements of the final FIP rule are effectively less stringent than 
both the rule as proposed and Rule 310. Thus the costs of compliance 
with the FIP rule are expected to be less than the proposed FIP rule 
and Rule 310.
    As the above discussion of the RACM requirements of the two rules 
makes clear, even though the final FIP rule differs from Rule 310 in 
that it is more specific and detailed, there should be no additional 
burden on regulated sources because they are already legally required 
to apply RACM under the County rule, and the RACM required by the final 
FIP rule are substantively identical to that required under Rule 
310.41
---------------------------------------------------------------------------

    \41\ Since, by its terms, the requirements of Rule 310 are so 
broad, the general effect of the greater specificity and detail is 
that EPA's FIP rule, in its entirety, is somewhat narrower in scope 
than the County's rule as it relates to unpaved roads, unpaved 
parking lots and vacant lots. For example, section 312 of Rule 310 
regulates users of unpaved roads, while EPA's rule regulates only 
owners and operators; and Rule 310 does not exempt any unpaved 
roads, while EPA's rule includes a low ADT exemption.
---------------------------------------------------------------------------

    Moreover, EPA believes that the additional recordkeeping 
requirement in the FIP rule will not have a significant economic impact 
on the affected sources. As stated above, and in section V.A.7.b. of 
the proposed rulemaking, the information required to be retained is 
minimal and is therefore not expected to entail any appreciable 
economic impact.
    b. Federal Commitment for Agriculture. EPA's final measure to 
control fugitive dust from agricultural fields and aprons consists of 
an enforceable commitment to propose and finalize adoption of RACM for 
those sources in September 1999 and April 2000, respectively. Prior to 
this formal rulemaking, EPA intends to convene a stakeholder process to 
develop the specific RACM that will ultimately be proposed for 
adoption. As discussed in detail in section V.A.7.a. of the proposed 
rulemaking, EPA intends the RACM to take the form of BMPs. During the 
BMP development process, EPA will investigate a myriad of factors, 
including the appropriate coverage of potential BMPs, regional climate, 
soil and crop types, and growing seasons. Because this aspect of 
today's action neither imposes specific regulatory requirements, nor 
obligates EPA to propose requirements necessarily applicable to small 
entities, it will not, by itself, have a significant economic impact on 
a substantial number of small entities. When EPA proposes specific RACM 
in the September 1999

[[Page 41349]]

rulemaking, it will either undertake a RFA analysis or certify the 
proposed rule, as appropriate.
    c. Certification. EPA has determined that it is not necessary to 
prepare a regulatory flexibility analysis in connection with this final 
rule. EPA has also determined that this rule will not have a 
significant economic impact on a substantial number of small entities.

C. Unfunded Mandates Reform Act (UMRA)

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), P.L. 
104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector.
    Under section 202 of the UMRA, EPA generally must prepare a written 
statement, including a cost-benefit analysis, when EPA promulgates 
``any general notice of proposed rulemaking that is likely to result in 
promulgation of any rule that includes any Federal mandate that may 
result in the expenditures by State, local, and tribal governments, in 
the aggregate, or by the private sector, of $100 million or more'' in 
any one year. A ``Federal mandate'' is defined, under section 101 of 
UMRA, as a provision that ``would impose an enforceable duty'' upon the 
private sector or State, local, or tribal governments'', with certain 
exceptions not here relevant.
    Under section 203 of UMRA, EPA must develop a small government 
agency plan before EPA ``establish[es] any regulatory requirements that 
might significantly or uniquely affect small governments'.
    Under section 204 of UMRA, EPA is required to develop a process to 
facilitate input by elected officers of State, local, and tribal 
governments for EPA's ``regulatory proposals'' that contain significant 
Federal intergovernmental mandates.
    Under section 205 of UMRA, before EPA promulgates ``any rule for 
which a written statement is required under [UMRA section] 202'', EPA 
must identify and consider a reasonable number of regulatory 
alternatives and either adopt the least costly, most cost-effective or 
least burdensome alternative that achieves the objectives of the rule, 
or explain why a different alternative was selected.
    As explained above, while the final federal fugitive dust rule may 
impose an enforceable duty on State or local governments, the resulting 
expenditures by those entities are expected to be minimal. Tribal 
governments are excluded from the coverage of this rule. In addition, 
there will be no current enforceable duties imposed on, or expenditures 
by, State, local or tribal governments or the private sector as a 
result of the federal commitment regarding the agricultural sector. 
Therefore, expenditures by State, local and tribal governments, in the 
aggregate, or by the private sector, will be well under $100 million 
per year as a result of today's federal measures. Consequently, 
sections 202, 204 and 205 of UMRA do not apply to today's final action. 
Therefore, EPA is not required and has not taken any actions to meet 
the requirements of these sections of UMRA.
    With respect to section 203 of UMRA, EPA has concluded that its 
final actions include no regulatory requirements that will 
significantly or uniquely affect small governments. As discussed in 
detail in IV.B.2. above, EPA believes that the RACM requirements of the 
final FIP rule for vacant lots, unpaved parking lots and unpaved roads 
are already legally required under Maricopa County Rule 310 which is 
federally enforceable as an approved element of the Arizona SIP. 
Moreover, the requirements of EPA's final FIP rule, while more specific 
and detailed, are substantively identical to those required under Rule 
310. Therefore, there should be no additional burden on regulated 
sources, including small governments. With respect to EPA's enforceable 
commitment for the agricultural sector, such a commitment neither 
imposes specific regulatory requirements, nor obligates EPA to propose 
requirements necessarily applicable to small entities. Thus, neither 
EPA's fugitive dust rule nor its commitment for the agricultural sector 
will significantly or uniquely affect small governments. Consequently, 
EPA has not developed a small government plan. Nevertheless, prior to 
EPA's proposed action, the Agency held numerous meetings with 
potentially affected representatives of the State and local governments 
to discuss the requirements of, and receive input regarding, the 
proposed federal fugitive dust rule and commitment for the agricultural 
sector.

D. Paperwork Reduction Act

    The information collection requirements in this final rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. An 
Information Collection Request (ICR) document has been prepared by EPA 
(ICR No. 1855.02) and a copy may be obtained from Sandy Farmer, OPPE 
Regulatory Information Division; U.S. Environmental Protection Agency 
(2137); 401 M St., S.W.; Washington, DC 20460 or by calling (202) 260-
2740.
    EPA's final FIP rule for unpaved parking lots, unpaved roads and 
vacant lots includes recordkeeping and reporting requirements which 
will help ensure source compliance with the rule's control 
requirements. In general, EPA believes the recordkeeping and reporting 
requirements are the minimal requirements necessary to demonstrate 
compliance. The requirements include:

--Owners/operators of unpaved roads must keep a record which indicates 
the date and type of control (i.e., paving, stabilizing, or applying 
gravel) applied to the road.
--Owners/operators of unpaved parking lots must keep a record which 
indicates the date and type of control (i.e., paving, stabilizing, 
applying gravel, or temporary stabilization for lots used less than 35 
days per year) applied to the unpaved parking lot.
--Owners/operators of vacant lots with disturbed surfaces must keep a 
record which indicates the date and type of control (i.e., applying 
ground cover vegetation, stabilizing, restoring to natural undisturbed 
state, or applying gravel) applied to the vacant lot.
--Owners/operators of vacant lots with motor vehicle disturbances must 
keep a record which indicates the date and type of control applied to 
the vacant lot.
--Agency surveys will be conducted by the EPA or other appropriate 
agency to determine the effectiveness of the rule in the Phoenix area.

    The estimated recordkeeping and reporting burden for the proposed 
FIP rule was about 9716 hours and the estimated labor cost was about 
$173,632. However, since the final FIP rule no longer requires the 
submittal of dust control plans for weed abatement activity, the 
estimated recordkeeping and reporting burden for the final FIP rule is 
about 5297 hours and the estimated labor cost is about $93,455. No 
capital/start-up costs or operational and maintenance costs are 
anticipated. Burden means the total time, effort, or financial 
resources expended by persons to generate, maintain, retain, or 
disclose or provide information to or for a Federal agency. This 
includes the time needed to review instructions; develop, acquire, 
install, and utilize technology and systems for the purposes of 
collecting, validating, and verifying information, processing and 
maintaining information, and disclosing and providing information; 
adjust the existing ways to comply with any previously applicable 
instructions and

[[Page 41350]]

requirements; train personnel to be able to respond to a collection of 
information; search data sources; complete and review the collection of 
information; and transmit or otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control number for EPA's 
regulations is listed in 40 CFR Part 9 and 48 CFR Chapter 15.
    Send comments on the Agency's need for this information, the 
accuracy of the provided burden estimates, and any suggested methods 
for minimizing respondent burden, including through the use of 
automated collection techniques, to the Director, OPPE Regulatory 
Information Division; U.S. Environmental Protection Agency (2137); 401 
M St., S.W.; Washington, DC 20460; and to the Office of Information and 
Regulatory Affairs, Office of Management and Budget, 725 17th St., N.W. 
Washington, DC 20503, marked ``Attention: Desk Officer for EPA.'' 
Comments are requested by September 2, 1998. Include the ICR number in 
any correspondence.

E. E.O. 13045: Protection of Children From Environmental Health Risks 
and Safety Risks

    Executive Order 13045, entitled ``Protection of Children from 
Environmental Health Risks and Safety Risks (62 FR 19885 (April 23, 
1997)), applies to any rule that EPA determines (1) ``economically 
significant'' as defined under E.O. 12866 and (2) the environmental 
health or safety risk addressed by the rule has a disproportionate 
effect on children. If the regulatory action meets both criteria, the 
Agency must evaluate the environmental health or safety effects of the 
planned rule on children; and explain why the planned regulation is 
preferable to other potentially effective and reasonably feasible 
alternatives considered by the Agency.
    Today's final action promulgating a moderate area PM-10 federal 
implementation plan for the Phoenix area is not subject to E.O. 13045 
because it is not an economically significant regulatory action as 
defined by E.O. and because it does not involve decisions on 
environmental health risks or safety risks that may disproportionately 
affect children.

F. Submission to Congress and the General Accounting Office

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. This rule is not a 
``major'' rule as defined by 5 U.S.C. 804(2).

G. Petitions for Judicial Review

    Under section 307(b)(1) of the Clean Air Act, petitions for 
judicial review of this action must be filed in the United States Court 
of Appeals for the appropriate circuit by October 2, 1998. Filing a 
petition for reconsideration by the Administrator of this final rule 
does not affect the finality of this rule for the purposes of judicial 
review nor does it extend the time within which a petition for judicial 
review may be filed, and shall not postpone the effectiveness of such 
rule or action. This action may not be challenged later in proceedings 
to enforce its requirements. (See section 307(b)(2)).

List of Subjects in 40 CFR Part 52

    Environmental protection, Air pollution control, Intergovernmental 
relations, Particulate matter, Reporting and recordkeeping 
requirements.

    Dated: July 17, 1998.
Carol M. Browner,
Administrator.

    For the reasons set forth in the preamble, part 52, chapter I, 
title 40 of the Code of Federal Regulations is amended as follows:

PART 52--APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS

    1. The authority citation for part 52 continues to read as follows:

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

Subpart D--Arizona

    2. Section 52.123 is amended by adding paragraph (h) to read as 
follows:


Sec. 52.123  Approval Status.

* * * * *
    (h) Pursuant to the federal planning authority in section 110(c) of 
the Clean Air Act, the Administrator finds that the applicable 
implementation plan for the Maricopa County PM-10 nonattainment area 
provides for the implementation of reasonably available control 
measures as required by section 189(a)(1)(C) and demonstrates 
attainment by the applicable attainment date as required and allowed by 
sections 172(c)(2) and 189(a)(1)(B).
    3. Section 52.124 is amended by adding paragraph (c) to read as 
follows:


Sec. 52.124  Part D disapproval.

* * * * *
    (c) The Administrator disapproves the attainment demonstration for 
the annual PM-10 national ambient air quality standard and the 
provisions for implementation of reasonably available control measures 
for the annual PM-10 national ambient air quality standard in the MAG 
1991 Particulate Plan for PM-10 for the Maricopa County Area and 1993 
Revisions (July 1993) submitted by the Arizona Department of 
Environmental Quality on August 11, 1993 as revised by the submittal of 
a Revised Chapter 9 on March 3, 1994 because they do not meet the 
requirements of sections 189(a)(1)(B) and 189(a)(1)(C) of Part D of 
title I of the Clean Air Act.
    4. Subpart D is amended by adding Secs. 52.127 and 52.128 to read 
as follows:


Sec. 52.127  Commitment to promulgate and implement reasonably 
available control measures for the agricultural fields and aprons.

    The Administrator shall promulgate and implement reasonably 
available control measures (RACM) pursuant to section 189(a)(1)(C) of 
the Clean Air Act for agricultural fields and aprons in the Maricopa 
County (Phoenix) PM-10 nonattainment area according to the following 
schedule: by no later than September, 1999, the Administrator shall 
sign a Notice of Proposed Rulemaking; by no later than April, 2000, the 
Administrator shall sign a Notice of Final Rulemaking; and by no later 
than June, 2000, EPA shall begin implementing the final RACM.


Sec. 52.128  Rule for unpaved parking lots, unpaved roads and vacant 
lots.

    (a) General. (1) Purpose. The purpose of this section is to limit 
the emissions of particulate matter into the ambient air from human 
activity on unpaved parking lots, unpaved roads and vacant lots.
    (2) Applicability. The provisions of this section shall apply to 
owners/operators of unpaved roads, unpaved parking lots and vacant lots 
and responsible parties for weed abatement on vacant lots in the 
Phoenix PM-10 nonattainment area. This section does not apply to 
unpaved roads, unpaved parking lots or vacant lots located on an 
industrial facility, construction, or earth-moving site that has an 
approved

[[Page 41351]]

permit issued by Maricopa County Environmental Services Division under 
Rule 200, Section 305, Rule 210 or Rule 220 containing a Dust Control 
Plan approved under Rule 310 covering all unpaved parking lots, unpaved 
roads and vacant lots. This section does not apply to the two Indian 
Reservations (the Salt River Pima-Maricopa Indian Community and the 
Fort McDowell Mojave-Apache Indian Community) and a portion of a third 
reservation (the Gila River Indian Community) in the Phoenix PM-10 
nonattainment area. Nothing in this definition shall preclude 
applicability of this section to vacant lots with disturbed surface 
areas due to construction, earth-moving, weed abatement or other dust 
generating operations which have been terminated for over eight months.
    (3) The test methods described in Appendix A of this section shall 
be used when testing is necessary to determine whether a surface has 
been stabilized as defined in paragraph (b)(16) of this section.
    (b) Definitions. (1) Average daily trips (ADT)--the average number 
of vehicles that cross a given surface during a specified 24-hour time 
period as determined by the Institute of Transportation Engineers Trip 
Generation Report (6th edition, 1997) or tube counts.
    (2) Chemical/organic stabilizer--Any non-toxic chemical or organic 
dust suppressant other than water which meets any specifications, 
criteria, or tests required by any federal, state, or local water 
agency and is not prohibited for use by any applicable law, rule or 
regulation.
    (3) Disturbed surface area--Any portion of the earth's surface, or 
materials placed thereon, which has been physically moved, uncovered, 
destabilized, or otherwise modified from its undisturbed natural 
condition, thereby increasing the potential for emission of fugitive 
dust.
    (4) Dust suppressants--Water, hygroscopic materials, solution of 
water and chemical surfactant, foam, or non-toxic chemical/ organic 
stabilizers not prohibited for use by any applicable law, rule or 
regulation, as a treatment material to reduce fugitive dust emissions.
    (5) EPA--United States Environmental Protection Agency, Region IX, 
75 Hawthorne Street, San Francisco, California 94105.
    (6) Fugitive dust--the particulate matter entrained in the ambient 
air which is caused from man-made and natural activities such as, but 
not limited to, movement of soil, vehicles, equipment, blasting, and 
wind. This excludes particulate matter emitted directly from the 
exhaust of motor vehicles and other internal combustion engines, from 
portable brazing, soldering, or welding equipment, and from 
piledrivers.
    (7) Lot--A parcel of land identified on a final or parcel map 
recorded in the office of the Maricopa County recorder with a separate 
and distinct number or letter.
    (8) Low use unpaved parking lot--A lot on which vehicles are parked 
no more than thirty-five (35) days a year, excluding days where the 
exemption in paragraph (c)(2) of this section applies.
    (9) Motor vehicle--A self-propelled vehicle for use on the public 
roads and highways of the State of Arizona and required to be 
registered under the Arizona State Uniform Motor Vehicle Act, including 
any non-motorized attachments, such as, but not limited to, trailers or 
other conveyances which are connected to or propelled by the actual 
motorized portion of the vehicle.
    (10) Off-road motor vehicle--any wheeled vehicle which is used off 
paved roadways and includes but is not limited to the following:
    (i) Any motor cycle or motor-driven cycle;
    (ii) Any motor vehicle commonly referred to as a sand buggy, dune 
buggy, or all terrain vehicle.
    (11) Owner/operator--any person who owns, leases, operates, 
controls, maintains or supervises a fugitive dust source subject to the 
requirements of this section.
    (12) Paving--Applying asphalt, recycled asphalt, concrete, or 
asphaltic concrete to a roadway surface.
    (13) Phoenix PM-10 nonattainment area--such area as defined in 40 
CFR 81.303, excluding Apache Junction.
    (14) PM-10--Particulate matter with an aerodynamic diameter less 
than or equal to a nominal 10 micrometers as measured by reference or 
equivalent methods that meet the requirements specified for PM-10 in 40 
CFR Part 50, Appendix J.
    (15) Reasonably available control measures (RACM)--Techniques used 
to prevent the emission and/or airborne transport of fugitive dust and 
dirt.
    (16) Stabilized surface--(i) Any unpaved road or unpaved parking 
lot surface in which any fugitive dust plume emanating from vehicular 
movement does not exceed 20 percent opacity as determined in section I. 
of Appendix A of this section.
    (ii) Any vacant lot surface with:
    (A) A visible crust which is greater than 0.6 centimeters (cm) 
thick and is not easily crumbled between the fingers as determined in 
section II.1. of Appendix A of this section;
    (B) A threshold friction velocity (TFV), corrected for non-erodible 
elements, of 100 cm/second or higher as determined in section II.2 of 
Appendix A of this section;
    (C) Flat vegetation cover equal to at least 50 percent as 
determined in section II. 3. of Appendix A of this section;
    (D) Standing vegetation cover equal to or greater than 30 percent 
as determined in section II. 4. of Appendix A of this section; or
    (E) Standing vegetation cover equal to or greater than 10 percent 
as determined in section II.4. of Appendix A of this section where 
threshold friction velocity, corrected for non-erodible elements, as 
determined in section II. 2 of Appendix A of this section is equal to 
or greater than 43 cm/second.
    (17) Unpaved Parking Lot--A privately or publicly owned or operated 
area utilized for parking vehicles that is not paved and is not a Low 
Use Unpaved Parking Lot.
    (18) Unpaved Road--Any road, equipment path, or driveway that is 
not paved which is open to public access and owned/operated by any 
federal, state, county, municipal or other governmental or quasi-
governmental agencies.
    (19) Urban or Suburban Open Area--An unsubdivided or undeveloped 
tract of land adjoining a residential, industrial or commercial area, 
located on public or private property.
    (20) Vacant Lot--A subdivided residential, industrial, 
institutional, governmental or commercial lot which contains no 
approved or permitted buildings or structures of a temporary or 
permanent nature.
    (c) Exemptions. The following requirements in paragraph (d) of this 
section do not apply:
    (1) In paragraphs (d)(1) and (d)(3)(iii) of this section: Any 
unpaved parking lot or vacant lot 5,000 square feet or less.
    (2) In paragraph (d)(1) of this section: Any unpaved parking lot on 
any day in which ten (10) or fewer vehicles enter.
    (3) In paragraphs (d)(3)(i) and (d)(3)(ii) of this section: Any 
vacant lot with less than 0.50 acre (21,780 square feet) of disturbed 
surface area(s).
    (4) In paragraph (d) of this section: Non-routine or emergency 
maintenance of flood control channels and water retention basins.
    (5) In paragraph (d) of this section: Vehicle test and development 
facilities and operations when dust is required to test and validate 
design integrity, product quality and/or commercial acceptance. Such 
facilities and

[[Page 41352]]

operations shall be exempted from the provisions of this section only 
if such testing is not feasible within enclosed facilities.
    (6) In paragraph (d)(3)(i) of this section: Weed abatement 
operations performed on any vacant lot or property under the order of a 
governing agency for the control of a potential fire hazard or 
otherwise unhealthy condition provided that mowing, cutting, or another 
similar process is used to maintain weed stubble at least three (3) 
inches above the soil surface. This includes the application of 
herbicides provided that the clean-up of any debris does not disturb 
the soil surface.
    (7) In paragraph (d)(3)(i) of this section: Weed abatement 
operations that receive an approved Earth Moving permit under Maricopa 
County Rule 200, Section 305 (adopted 11/15/93).
    (d) Requirements. (1) Unpaved parking lots.
    (i) Any owners/operators of an unpaved parking lot shall implement 
one of the following RACM on any surface area(s) of the lot on which 
vehicles enter and park.
    (A) Pave; or
    (B) Apply chemical/organic stabilizers in sufficient concentration 
and frequency to maintain a stabilized surface; or
    (C) Apply and maintain surface gravel uniformly such that the 
surface is stabilized.
    (ii) Any owners/operators of a Low Use Unpaved Parking Lot as 
defined in paragraph (b)(8) of this section shall implement one of the 
RACM under paragraph (d)(1)(i) of this section on any day(s) in which 
over 100 vehicles enter the lot, such that the surface area(s) on which 
vehicles enter and park is/are stabilized throughout the duration of 
time that vehicles are parked.
    (2) Unpaved roads. Any owners/operators of existing unpaved roads 
with ADT volumes of 250 vehicles or greater shall implement one of the 
following RACM along the entire surface of the road or road segment 
that is located within the Phoenix non-attainment area by June 10, 
2000:
    (i) Pave; or
    (ii) Apply chemical/organic stabilizers in sufficient concentration 
and frequency to maintain a stabilized surface; or
    (iii) Apply and maintain surface gravel uniformly such that the 
surface is stabilized.
    (3) Vacant lots. The following provisions shall be implemented as 
applicable.
    (i) Weed abatement. No person shall remove vegetation from any 
vacant lot by blading, disking, plowing under or any other means 
without implementing all of the following RACM to prevent or minimize 
fugitive dust.
    (A) Apply a dust suppressant(s) to the total surface area subject 
to disturbance immediately prior to or during the weed abatement.
    (B) Prevent or eliminate material track-out onto paved surfaces and 
access points adjoining paved surfaces.
    (C) Apply a dust suppressant(s), gravel, compaction or alternative 
control measure immediately following weed abatement to the entire 
disturbed surface area such that the surface is stabilized.
    (ii) Disturbed surfaces. Any owners/operators of an urban or 
suburban open area vacant lot of which any portion has a disturbed 
surface area(s) that remain(s) unoccupied, unused, vacant or 
undeveloped for more than fifteen (15) calendar days shall implement 
one of the following RACM within sixty (60) calendar days following the 
disturbance.
    (A) Establish ground cover vegetation on all disturbed surface 
areas in sufficient quantity to maintain a stabilized surface; or
    (B) Apply a dust suppressant(s) to all disturbed surface areas in 
sufficient quantity and frequency to maintain a stabilized surface; or
    (C) Restore to a natural state, i.e. as existing in or produced by 
nature without cultivation or artificial influence, such that all 
disturbed surface areas are stabilized; or
    (D) Apply and maintain surface gravel uniformly such that all 
disturbed surface areas are stabilized.
    (iii) Motor vehicle disturbances. Any owners/operators of an urban 
or suburban open area vacant lot of which any portion has a disturbed 
surface area due to motor vehicle or off-road motor vehicle use or 
parking, notwithstanding weed abatement operations or use or parking by 
the owner(s), shall implement one of the following RACM within 60 
calendar days following the initial determination of disturbance.
    (A) Prevent motor vehicle and off-road motor vehicle trespass/
parking by applying fencing, shrubs, trees, barriers or other effective 
measures; or
    (B) Apply and maintain surface gravel or chemical/organic 
stabilizer uniformly such that all disturbed surface areas are 
stabilized.
    (4) Alternative control measures. For sources subject to 
requirements in paragraphs (d)(1), (d)(2), (d)(3)(ii) and (d)(3)(iii) 
of this section: As an alternative to compliance, owners/operators may 
use any other alternative control measures approved by EPA pursuant to 
paragraphs (e)(1) and (e)(2) of this section as equivalent to the 
methods specified in paragraph (d) of this section.
    (5) Implementation date of RACM. All of the requirements in 
paragraph (d) of this section shall be effective eight (8) months from 
September 2, 1998. For requirements in paragraph (d)(3)(ii) and 
(d)(3)(iii) of this section, RACM shall be implemented within eight (8) 
months from September 2, 1998, or within 60 calendar days following the 
disturbance, whichever is later.
    (e) Administrative requirements. (1) Proposed alternative control 
measures for sources subject to paragraph (d)(2) of this section must 
be submitted to EPA for approval within one year from September 2, 
1998. Proposed alternative control measures for sources subject to 
paragraph (d)(1) of this section must be submitted to EPA for approval 
within 90 calendar days prior to the required RACM implementation date 
as specified in this section. Proposed alternative control measures for 
sources subject to paragraphs (d)(3)(ii) and (d)(3)(iii) of this 
section must be submitted to EPA for approval within 90 calendar days 
prior to the required RACM implementation date as specified in this 
section or within 60 calendar days following the initial determination 
of disturbance, whichever is later.
    (2) Upon receipt of an alternative control measure, EPA shall 
provide written notice within 30 calendar days to the owner/operator 
approving or disapproving the alternative control measure. Should EPA 
not provide written notice of approval or disapproval within the above 
deadline, the owner/operator shall assume that the alternative control 
measure is approved. Upon receiving notice of EPA approval, the owner/
operator shall implement the alternative control measure according to 
the timeframe established in this section unless otherwise specified by 
EPA. Upon receiving notice of EPA disapproval of the alternative 
control measure, the owner/operator shall implement RACM according to 
the specifications and timeframe established in this section. For 
sources submitting an alternative control measure under paragraphs 
(d)(3)(ii) or (d)(3)(iii) of this section, owners/operators shall 
implement the alternative control measure if approved by EPA within 60 
calendar days upon receiving written notice, or, upon disapproval of 
the alternative control measure, implement RACM as specified in this 
section within 60 calendar days upon receiving written notice.
    (f) Monitoring and records. (1) Any owners/operators that are 
subject to the provisions of this section shall compile and retain 
records that provide evidence

[[Page 41353]]

of control measure application, indicating the type of treatment or 
measure, extent of coverage and date applied. For control measures 
involving chemical/organic stabilization, records shall also indicate 
the type of product applied, vendor name, label instructions for 
approved usage, and the method, frequency, concentration and quantity 
of application.
    (2) Copies of control measure records and dust control plans along 
with supporting documentation shall be retained for at least three 
years.
    (3) Agency surveys. (i) EPA or other appropriate entity shall 
conduct a survey of the number and size (or length) of unpaved roads, 
unpaved parking lots, and vacant lots subject to the provisions of this 
rule located within the Phoenix PM-10 nonattainment area beginning no 
later than 365 days from September 2, 1998.
    (ii) EPA or other appropriate entity shall conduct a survey at 
least every three years within the Phoenix PM-10 nonattainment area 
beginning no later than 365 days from September 2, 1998, which 
includes:
    (A) An estimate of the percentage of unpaved roads, unpaved parking 
lots, and vacant lots subject to this rule to which RACM as required in 
this section have been applied; and
    (B) A description of the most frequently applied RACM and estimates 
of their control effectiveness.

Appendix A to Sec. 52.128 Test Methods To Determine Whether a Surface 
Is Stabilized

I. Unpaved Roads and Unpaved Parking Lots

    Conduct opacity observations in accordance with Reference Method 
9 (40 CFR Part 60, appendix A) and Methods 203A and 203C of this 
appendix, with opacity readings taken at five second observation 
intervals and two consecutive readings per plume beginning with the 
first reading at zero seconds, in accordance with Method 203C, 
sections 2.3.2. and 2.4.2 of this appendix. Conduct visible opacity 
tests only on dry unpaved surfaces (i.e. when the surface is not 
damp to the touch) and on days when average wind speeds do not 
exceed 15 miles per hour (mph).

Method 203A--Visual Determination of Opacity of Emissions From 
Stationary Sources for Time-Arranged Regulations

    Method 203A is virtually identical to EPA's Method 9 of 40 CFR 
part 60, appendix A except for the data-reduction procedures, which 
provide for averaging times other than 6 minutes. That is, using 
Method 203A with a 6-minute averaging time would be the same as 
following EPA Method 9. Additionally, Method 203A provides 
procedures for fugitive dust applications. The certification 
procedures provided in section 3 are virtually identical to Method 9 
and are provided here, in full, for clarity and convenience.

1. Applicability and Principle

    1.1  Applicability. This method is applicable for the 
determination of the opacity of emissions from sources of visible 
emissions for time-averaged regulations. A time-averaged regulation 
is any regulation that requires averaging visible emission data to 
determine the opacity of visible emissions over a specific time 
period.
    1.2  Principle. The opacity of emissions from sources of visible 
emissions is determined visually by an observer qualified according 
to the procedures of section 3.

2. Procedures

    An observer qualified in accordance with section 3 of this 
method shall use the following procedures for visually determining 
the opacity of emissions.
    2.1  Procedures for Emissions from Stationary Sources. These 
procedures are not applicable to this section.
    2.2  Procedures for Fugitive Process Dust Emissions. These 
procedures are applicable for the determination of the opacity of 
fugitive emissions by a qualified observer. The qualified field 
observer should do the following:
    2.2.1  Position. Stand at a position at least 5 meters from the 
fugitive dust source in order to provide a clear view of the 
emissions with the sun oriented in the 140-degree sector to the 
back. Consistent as much as possible with maintaining the above 
requirements, make opacity observations from a position such that 
the line of vision is approximately perpendicular to the plume and 
wind direction. As much as possible, if multiple plumes are 
involved, do not include more than one plume in the line of sight at 
one time.
    2.2.2  Field Records. Record the name of the plant or site, 
fugitive source location, source type [pile, stack industrial 
process unit, incinerator, open burning operation activity, material 
handling (transfer, loading, sorting, etc.)], method of control 
used, if any, observer's name, certification data and affiliation, 
and a sketch of the observer's position relative to the fugitive 
source. Also, record the time, estimated distance to the fugitive 
source location, approximate wind direction, estimated wind speed, 
description of the sky condition (presence and color of clouds), 
observer's position relative to the fugitive source, and color of 
the plume and type of background on the visible emission observation 
form when opacity readings are initiated and completed.
    2.2.3  Observations. Make opacity observations, to the extent 
possible, using a contrasting background that is perpendicular to 
the line of vision. For roads, storage piles, and parking lots, make 
opacity observations approximately 1 meter above the surface from 
which the plume is generated. For other fugitive sources, make 
opacity observations at the point of greatest opacity in that 
portion of the plume where condensed water vapor is not present. For 
intermittent sources, the initial observation should begin 
immediately after a plume has been created above the surface 
involved. Do not look continuously at the plume but, instead, 
observe the plume momentarily at 15-second intervals.
    2.3  Recording Observations. Record the opacity observations to 
the nearest 5 percent every 15 seconds on an observational record 
sheet. Each momentary observation recorded represents the average 
opacity of emissions for a 15-second period.
    2.4  Data Reduction for Time-Averaged Regulations. A set of 
observations is composed of an appropriate number of consecutive 
observations determined by the averaging time specified. Divide the 
recorded observations into sets of appropriate time lengths for the 
specified averaging time. Sets must consist of consecutive 
observations; however, observations immediately preceding and 
following interrupted observations shall be deemed consecutive. Sets 
need not be consecutive in time and in no case shall two sets 
overlap, resulting in multiple violations. For each set of 
observations, calculate the appropriate average opacity.

3. Qualification and Testing

    3.1  Certification Requirements. To receive certification as a 
qualified observer, a candidate must be tested and demonstrate the 
ability to assign opacity readings in 5 percent increments to 25 
different black plumes and 25 different white plumes, with an error 
not to exceed 15 percent opacity on any one reading and an average 
error not to exceed 7.5 percent opacity in each category. Candidates 
shall be tested according to the procedures described in paragraph 
3.2. Any smoke generator used pursuant to paragraph 3.2 shall be 
equipped with a smoke meter which meets the requirements of 
paragraph 3.3. Certification tests that do not meet the requirements 
of paragraphs 3.2 and 3.3 are not valid.
    The certification shall be valid for a period of 6 months, and 
after each 6-month period, the qualification procedures must be 
repeated by an observer in order to retain certification.
    3.2  Certification Procedure. The certification test consists of 
showing the candidate a complete run of 50 plumes, 25 black plumes 
and 25 white plumes, generated by a smoke generator. Plumes shall be 
presented in random order within each set of 25 black and 25 white 
plumes. The candidate assigns an opacity value to each plume and 
records the observation on a suitable form. At the completion of 
each run of 50 readings, the score of the candidate is determined. 
If a candidate fails to qualify, the complete run of 50 readings 
must be repeated in any retest. The smoke test may be administered 
as part of a smoke school or training program, and may be preceded 
by training or familiarization runs of the smoke generator during 
which candidates are shown black and white plumes of known opacity.
    3.3  Smoke Generator Specifications. Any smoke generator used 
for the purpose of paragraph 3.2 shall be equipped with a smoke 
meter installed to measure opacity across the diameter of the smoke 
generator stack. The smoke meter output shall display in-stack 
opacity, based upon a path length equal to the stack exit diameter 
on a full 0 to 100 percent chart recorder scale. The smoke meter 
optical design and performance shall meet the specifications shown 
in Table A of method 203C. The smoke meter shall be calibrated as 
prescribed in paragraph 3.3.1 prior to conducting each smoke reading 
test.

[[Page 41354]]

At the completion of each test, the zero and span drift shall be 
checked, and if the drift exceeds 1 percent opacity, the 
condition shall be corrected prior to conducting any subsequent test 
runs. The smoke meter shall be demonstrated at the time of 
installation to meet the specifications listed in Table A of method 
203C. This demonstration shall be repeated following any subsequent 
repair or replacement of the photocell or associated electronic 
circuitry including the chart recorder or output meter, or every 6 
months, whichever occurs first.
    3.3.1  Calibration. The smoke meter is calibrated after allowing 
a minimum of 30 minutes warm-up by alternately producing simulated 
opacity of 0 percent and 100 percent. When stable response at 0 
percent or 100 percent is noted, the smoke meter is adjusted to 
produce an output of 0 percent or 100 percent, as appropriate. This 
calibration shall be repeated until stable 0 percent and 100 percent 
readings are produced without adjustment. Simulated 0 percent and 
100 percent opacity values may be produced by alternately switching 
the power to the light source on and off while the smoke generator 
is not producing smoke.
    3.3.2  Smoke Meter Evaluation. The smoke meter design and 
performance are to be evaluated as follows:
    3.3.2.1  Light Source. Verify from manufacturer's data and from 
voltage measurements made at the lamp, as installed, that the lamp 
is operated within 5 percent of the nominal rated 
voltage.
    3.3.2.2  Spectral Response of Photocell. Verify from 
manufacturer's data that the photocell has a photopic response; 
i.e., the spectral sensitivity of the cell shall closely approximate 
the standard spectral-luminosity curve for photopic vision which is 
referenced in (b) of Table A of method 203C.
    3.3.2.3  Angle of View. Check construction geometry to ensure 
that the total angle of view of the smoke plume, as seen by the 
photocell, does not exceed 15 degrees. Calculate the total angle of 
view as follows:

xv = 2 tan-1 d/2L,

Where:

v = total angle of view;
d = the photocell diameter + the diameter of the limiting aperture; 
and
L = distance from the photocell to the limiting aperture.

    The limiting aperture is the point in the path between the 
photocell and the smoke plume where the angle of view is most 
restricted. In smoke generator smoke meters, this is normally an 
orifice plate.
    3.3.2.4  Angle of Projection. Check construction geometry to 
ensure that the total angle of projection of the lamp on the smoke 
plume does not exceed 15 degrees. Calculate the total angle of 
projection as follows:

p = 2 tan-1 d/2L

Where:

p = total angle of projection;
d = the sum of the length of the lamp filament + the diameter of the 
limiting aperture; and
L = the distance from the lamp to the limiting aperture.

    3.3.2.5  Calibration Error. Using neutral-density filters of 
known opacity, check the error between the actual response and the 
theoretical linear response of the smoke meter. This check is 
accomplished by first calibrating the smoke meter according to 3.3.1 
and then inserting a series of three neutral-density filters of 
nominal opacity of 20, 50, and 75 percent in the smoke meter path 
length. Use filters calibrated within 2 percent. Care 
should be taken when inserting the filters to prevent stray light 
from affecting the meter. Make a total of five nonconsecutive 
readings for each filter. The maximum opacity error on any one 
reading shall be 3 percent.
    3.3.2.6  Zero and Span Drift. Determine the zero and span drift 
by calibrating and operating the smoke generator in a normal manner 
over a 1-hour period. The drift is measured by checking the zero and 
span at the end of this period.
    3.3.2.7  Response Time. Determine the response time by producing 
the series of five simulated 0 percent and 100 percent opacity 
values and observing the time required to reach stable response. 
Opacity values of 0 percent and 100 percent may be simulated by 
alternately switching the power to the light source off and on while 
the smoke generator is not operating.

4. References

1. U. S. Environmental Protection Agency. Standards of Performance 
for New Stationary Sources; appendix A; Method 9 for Visual 
Determination of the Opacity of Emissions from Stationary Sources. 
Final Rule. 39 FR 219. Washington, DC. U. S. Government Printing 
Office. November 12, 1974.
2. Office of Air and Radiation. ``Quality Assurance Guideline for 
Visible Emission Training Programs.'' EPA-600/S4-83-011. Quality 
Assurance Division. Research Triangle Park, N.C. May 1982.
3. ``Method 9--Visible Determination of the Opacity of Emissions 
from Stationary Sources.'' February 1984. Quality Assurance Handbook 
for Air Pollution Measurement Systems. Volume III, section 3.1.2. 
Stationary Source Specific Methods. EPA-600-4-77-027b. August 1977. 
Office of Research and Development Publications, 26 West Clair 
Street, Cincinnati, OH.
4. Office of Air Quality Planning and Standards. ``Opacity Error for 
Averaging and Nonaveraging Data Reduction and Reporting 
Techniques.'' Final Report-SR-1-6-85. Emission Measurement Branch, 
Research Triangle Park, N.C. June 1985.
5. The U. S. Environmental Protection Agency. Preparation, Adoption, 
and Submittal of State Implementation Plans. Methods for Measurement 
of PM10 Emissions from Stationary Sources. Final Rule. 
Federal Register. Washington, DC. U. S. Government Printing Office. 
Volumes 55. No. 74. pps. 14246-14279. April 17, 1990.

Method 203C--Visual Determination of Opacity of Emissions From 
Stationary Sources for Instantaneous Limitation Regulations

    Method 203C is virtually identical to EPA's Method 9 of appendix 
A to 40 CFR part 60, except for the data-reduction procedures which 
have been modified for application to instantaneous limitation 
regulations. Additionally, Method 203C provides procedures for 
fugitive dust applications which were unavailable when Method 9 was 
promulgated. The certification procedures in section 3 are identical 
to Method 9. These certification procedures are provided in Method 
203A as well, and, therefore, have not been repeated in this method.

1. Applicability and Principle

    1.1  Applicability. This method is applicable for the 
determination of the opacity of emissions from sources of visible 
emissions for instantaneous limitations. An instantaneous limitation 
regulation is an opacity limit which is never to be exceeded.
    1.2  Principle. The opacity of emissions from sources of visible 
emissions is determined visually by a qualified observer.

2. Procedures

    The observer qualified in accordance with section 3 of this 
method shall use the following procedures for visually determining 
the opacity of emissions.
    2.1  Procedures for Emissions From Stationary Sources. Same as 
2.1, Method 203A.
    2.1.1  Position. Same as 2.1.1, Method 203A.
    2.1.2  Field Records. Same as 2.1.2, Method 203A.
    2.1.3  Observations. Make opacity observations at the point of 
greatest opacity in that portion of the plume where condensed water 
vapor is not present.
    Do not look continuously at the plume. Instead, observe the plume 
momentarily at the interval specified in the subject regulation. Unless 
otherwise specified, a 15-second observation interval is assumed.
    2.1.3.1  Attached Steam Plumes. Same as 2.1.3.1, Method 203A.
    2.1.3.2  Detached Steam Plumes. Same as 2.1.3.2, Method 203A.
    2.2  Procedures for Fugitive Process Dust Emissions.
    2.2.1  Position. Same as section 2.2.1, Method 203A.
    2.2.2  Field Records. Same as section 2.2.2, Method 203A.
    2.2.3  Observations.
    2.2.3.1  Observations for a 15-second Observation Interval 
Regulations. Same as section 2.2.3, Method 203A.
    2.2.3.2  Observations for a 5-second Observation Interval 
Regulations. Same as section 2.2.3, Method 203A, except, observe the 
plume momentarily at 5-second intervals.
    2.3  Recording Observations. Record opacity observations to the 
nearest 5 percent at the prescribed interval on an observational 
record sheet. Each momentary observation recorded represents the 
average of emissions for the prescribed period. If a 5-second 
observation period is not specified in the applicable regulation, a 
15-second interval is assumed. The overall time for which recordings 
are made shall be of a length appropriate to the regulation for 
which opacity is being measured.
    2.3.1  Recording Observations for 15-second Observation Interval 
Regulations.

[[Page 41355]]

Record opacity observations to the nearest 5 percent at 15-second 
intervals on an observational record sheet. Each momentary 
observation recorded represents the average of emissions for a 15-
second period.
    2.3.2  Recording Observations for 5-second Observation Interval 
Regulations. Record opacity observations to the nearest 5 percent at 
5-second intervals on an observational record sheet. Each momentary 
observation recorded represents the average of emissions for 5-
second period.
    2.4  Data Reduction for Instantaneous Limitation Regulations. 
For an instantaneous limitation regulation, a 1-minute averaging 
time will be used. Divide the observations recorded on the record 
sheet into sets of consecutive observations. A set is composed of 
the consecutive observations made in 1 minute. Sets need not be 
consecutive in time, and in no case shall two sets overlap. Reduce 
opacity observations by dividing the sum of all observations 
recorded in a set by the number of observations recorded in each 
set.
    2.4.1  Data Reduction for 15-second Observation Intervals. 
Reduce opacity observations by averaging four consecutive 
observations recorded at 15-second intervals. Divide the 
observations recorded on the record sheet into sets of four 
consecutive observations. For each set of four observations, 
calculate the average by summing the opacity of the four 
observations and dividing this sum by four.
    2.4.2  Data Reduction for 5-second Observation Intervals. Reduce 
opacity observations by averaging 12 consecutive observations 
recorded at 5-second intervals. Divide the observations recorded on 
the record sheet into sets of 12 consecutive observations. For each 
set of 12 observations, calculate the average by summing the opacity 
of the 12 observations and dividing this sum by 12.

3. Qualification and Test

    Same as section 3, Method 203A.

       Table A.--Smoke Meter Design and Performance Specifications      
------------------------------------------------------------------------
                 Parameter                          Specification       
------------------------------------------------------------------------
a. Light Source...........................  Incandescent lamp operated  
                                             at nominal rated voltage.  
b. Spectral response of photocell.........  Photopic (daylight spectral 
                                             response of the human eye--
                                             Reference 4.1 of section   
                                             4.).                       
c. Angle of view..........................  15 degrees maximum total    
                                             angle.                     
d. Angle of projection....................  15 degrees maximum total    
                                             angle.                     
e. Calibration error......................  +3-percent      
                                             opacity, maximum.          
f. Zero and span drift....................  1-percent       
                                             opacity, 30 minutes.       
g. Response time..........................   5 seconds.      
------------------------------------------------------------------------

II. Vacant Lots

    The following test methods shall be used for determining whether 
a vacant lot, or portion thereof, has a stabilized surface. Should a 
disturbed vacant lot contain more than one type of disturbance, 
soil, vegetation or other characteristics which are visibly 
distinguishable, test each representative surface for stability 
separately in random areas according to the test methods in section 
II. of this appendix and include or eliminate it from the total size 
assessment of disturbed surface area(s) depending upon test method 
results. A vacant lot surface shall be considered stabilized if any 
of the test methods in section II. of this appendix indicate that 
the surface is stabilized such that the conditions defined in 
paragraph (b)(16)(ii) of this section are met:

1. Determination of visible crust thickness

    Where a visible crust exists, break off a small piece of crust. 
Check whether it crumbles easily between the fingers. Using a ruler, 
measure the thickness of the crust. Determination of thickness shall 
be based on at least three (3) crustal measurements representative 
of the disturbed surface area. If thin deposits of loose uncombined 
grains cover more than 50 percent of a crusted surface, apply the 
test method in section II.2. of this appendix to the loose material 
to determine whether the surface is stabilized.

2. Determination of Threshold Friction Velocity (TFV)

    For disturbed surface areas that are not crusted or vegetated, 
determine threshold friction velocity (TFV) according to the 
following sieving field procedure (based on a 1952 laboratory 
procedure published by W. S. Chepil).
    (i) Obtain and stack a set of sieves with the following 
openings: 4 millimeters (mm), 2 mm, 1 mm, 0.5 mm, and 0.25 mm. Place 
the sieves in order according to size openings beginning with the 
largest size opening at the top. Place a collector pan underneath 
the bottom (0.25 mm) sieve. Collect a sample of loose surface 
material from an area at least 30 cm by 30 cm in size to a depth of 
approximately 1 cm using a brush and dustpan or other similar 
device. Only collect soil samples from dry surfaces (i.e. when the 
surface is not damp to the touch). Remove any rocks larger than 1 cm 
in diameter from the sample. Pour the sample into the top sieve (4 
mm opening) and cover the sieve/collector pan unit with a lid. 
Minimize escape of particles into the air when transferring surface 
soil into the sieve/collector pan unit. Move the covered sieve/
collector pan unit by hand using a broad, circular arm motion in the 
horizontal plane. Complete twenty circular arm movements, ten 
clockwise and ten counterclockwise, at a speed just necessary to 
achieve some relative horizontal motion between the sieves and the 
particles. Remove the lid from the sieve/collector pan unit and 
disassemble each sieve separately beginning with the largest sieve. 
As each sieve is removed, examine it for loose particles. If loose 
particles have not been sifted to the finest sieve through which 
they can pass, reassemble and cover the sieve/collector pan unit and 
gently rotate it an additional ten times. After disassembling the 
sieve/collector pan unit, slightly tilt and gently tap each sieve 
and the collector pan so that material aligns along one side. In 
doing so, minimize escape of particles into the air. Line up the 
sieves and collector pan in a row and visibly inspect the relative 
quantities of catch in order to determine which sieve (or whether 
the collector pan) contains the greatest volume of material. If a 
visual determination of relative volumes of catch among sieves is 
difficult, use a graduated cylinder to measure the volume. Estimate 
TFV for the sieve catch with the greatest volume using Table 1, 
which provides a correlation between sieve opening size and TFV.

 Table 1.--(Metric Units). Determination of Threshold Friction Velocity 
                                  (TFV)                                 
------------------------------------------------------------------------
                                                     Opening   TFV  (cm/
                 Tyler Sieve No.                      (mm)         s)   
------------------------------------------------------------------------
5................................................        4      10%.............................  5                         
 5% and < 10%....................  3                         
< 5% and  1%.....................  2                         
< 1%........................................  None.                     
------------------------------------------------------------------------

3. Determination of Flat Vegetation Cover

    Flat vegetation includes attached (rooted) vegetation or 
unattached vegetative debris lying on the surface with a predominant 
horizontal orientation that is not subject to movement by wind. Flat 
vegetation which is dead but firmly attached shall be considered 
equally protective as live vegetation. Stones or other aggregate 
larger than one centimeter in diameter shall be considered 
protective cover in the course of conducting the line transect 
method. Where flat vegetation exists, conduct the following line 
transect method.
    (i) Stretch a one-hundred (100) foot measuring tape across a 
disturbed surface area. Firmly anchor both ends of the measuring 
tape into the surface using a tool such as a screwdriver with the 
tape stretched taut and close to the soil surface. If vegetation 
exists in regular rows, place the tape diagonally (at approximately 
a 45 degree angle) away from a parallel or perpendicular position to 
the vegetated rows. Pinpoint an area the size of a \3/32\ inch 
diameter brazing rod or wooden dowel centered above each one-foot 
interval mark along one edge of the tape. Count the number of times 
that flat vegetation lies directly underneath the pinpointed area at 
one-foot intervals. Consistently observe the underlying surface from 
a 90 degree angle directly above each pinpoint on one side of the 
tape. Do not count the underlying surface as vegetated if any 
portion of the pinpoint extends beyond the edge of the vegetation 
underneath in any direction. If clumps of vegetation or vegetative 
debris lie underneath the pinpointed area, count the surface as 
vegetated unless bare soil is visible directly below the pinpointed 
area. When 100 observations have been made, add together the number 
of times a surface was counted as vegetated. This total represents 
the percent of flat vegetation cover (e.g. if 35 positive counts 
were made, then vegetation cover is 35 percent). If the disturbed 
surface area is too small for 100 observations, make as many 
observations as possible. Then multiply the count of vegetated 
surface areas by the appropriate conversion factor to obtain percent 
cover. For example, if vegetation was counted 20 times within a 
total of 50 observations, divide 20 by 50 and multiply by 100 to 
obtain a flat vegetation cover of 40 percent.
    (ii) Conduct the above line transect test method an additional 
two (2) times on areas representative of the disturbed surface and 
average results.

4. Determination of Standing Vegetation Cover

    Standing vegetation includes vegetation that is attached 
(rooted) with a predominant vertical orientation. Standing 
vegetation which is dead but firmly rooted shall be considered 
equally protective as live vegetation. Conduct the following 
standing vegetation test method to determine if 30 percent cover or 
more exists. If the resulting percent cover is less than 30 percent 
but equal to or greater than 10 percent, then conduct the Threshold 
Friction Velocity test in Section II.2. of this in order to 
determine whether the disturbed surface area is stabilized according 
to paragraph (b)(16)(ii)(E) of this section.
    (i) For standing vegetation that consists of large, separate 
vegetative structures (for example, shrubs and sagebrush), select a 
survey area representing the disturbed surface that is the shape of 
a square with sides equal to at least ten (10) times the average 
height of the vegetative structures. For smaller standing 
vegetation, select a survey area of three (3) feet by 3 feet.
    (ii) Count the number of standing vegetative structures within 
the survey area. Count vegetation which grows in clumps as a single 
unit. Where vegetation of different height and width exists, count 
it in groups with similar dimensions within the survey area. For 
each group, calculate the frontal silhouette area for the vegetative 
structures according to the following equations:


(Average height)  x  (Average width) = Average           Eq. 6          
 Dimensions                                                             
(Average Dimensions)  x  (Number of Vegetation) =        Eq. 7          
 Frontal Silhouette Area                                                
Frontal Silhouette Area of Group 1 + Frontal Silhouette  Eq. 8          
 Area of Group 2 (etc..) = Total Frontal Silhouette                     
 Area                                                                   
(Total Frontal Silhouette Area/Survey Area)  x  100 =    Eq. 9          
 Percent Cover of Standing Vegetation                                   
                                                                        

(Ensure consistent units of measurement, e.g. square meters or 
square inches when calculating percent cover.)

    (iii) Within a disturbed surface area that contains multiple 
types of vegetation with each vegetation type uniformly distributed, 
results of the percent cover associated with the individual 
vegetation types may be added together.
    (iv) Repeat this procedure on an additional two (2) distinct 
survey areas representing the disturbed surface and average the 
results.

5. Alternative Test Methods

    Alternative test methods may be used upon obtaining the written 
approval of the EPA.

[FR Doc. 98-20147 Filed 7-31-98; 8:45 am]
BILLING CODE 6560-50-U