[Federal Register Volume 60, Number 68 (Monday, April 10, 1995)]
[Rules and Regulations]
[Pages 18010-18020]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8215]



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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52

[AZ31-1-6531; FRL-5173-8]


Approval and Promulgation of Implementation Plans; Arizona-
Phoenix Nonattainment Area; PM10

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: EPA is finalizing the approval of a revision to the Arizona 
State Implementation Plan (SIP) proposed in the Federal Register on 
July 28, 1994. The revision was submitted to EPA by Arizona to fulfill 
the State's obligation to revise its SIP to meet the PM10 
(particulate matter less than or equal to 10 microns in aerodynamic 
diameter) ``moderate'' area planning requirements of the Clean Air Act 
(CAA or Act). This approval action will incorporate this revision into 
the federally approved SIP. The intended effect of approving this 
revision is to regulate emissions of PM10 in the Phoenix Planning 
Area (PPA). The revised SIP controls PM10 emissions from sources 
including, but not limited to, paved roads, construction and demolition 
activities, unpaved parking areas and roads, nonmetallic mineral mining 
and processing facilities, open burning activities, uncovered haul 
trucks and farming operations. Thus, EPA is finalizing the approval of 
this revision into the Arizona SIP under provisions of the CAA 
regarding EPA action on SIP submittals, SIPs for national primary and 
secondary ambient air quality standards and plan requirements for 
nonattainment areas.

EFFECTIVE DATE: This action is effective on May 10, 1995.

ADDRESSES: Copies of the SIP revision are available for public 
inspection at EPA's Region IX office during normal business hours. 
Copies of the submitted SIP revisions are available for inspection at 
the following locations:

Plans Development Section (A-2-2), Air and Toxics Division, U.S. 
Environmental Protection Agency, Region IX, 75 Hawthorne Street, San 
Francisco, CA 94105.
Environmental Protection Agency, Air Docket (6102), 401 ``M'' Street 
SW., Washington, DC 20460.
Arizona Department of Environmental Quality, 3033 North Central Avenue, 
Phoenix, AZ 85012.

FOR FURTHER INFORMATION CONTACT: Robert Pallarino, (415) 744-1212.
SUPPLEMENTARY INFORMATION: [[Page 18011]] 

I. Background

A. CAA Requirements

    On the date of enactment of the 1990 Clean Air Act Amendments, 
PM10 areas, including the PPA, meeting the conditions of section 
107(d) of the Act were designated nonattainment by operation of law. 
Once an area is designated nonattainment, section 188 of the Act 
outlines the process for classification of the area and establishes the 
area's attainment date. In accordance with section 188(a), at the time 
of designation, all PM10 nonattainment areas were initially 
classified as ``moderate'' by operation of law. See 40 CFR 81.303 
(1993). A moderate area may subsequently be reclassified as ``serious'' 
if at any time EPA determines that the area cannot practicably attain 
the PM10 NAAQS by the applicable attainment date for moderate 
areas, December 31, 1994. Moreover, a moderate area is reclassified by 
operation of law if the area is not in attainment after the applicable 
attainment date, which is December 31, 1994 for the PPA. EPA is 
required to make a determination and provide public notice regarding 
whether the area has attained within six months following the 
attainment date. See Section 188(b), 42 U.S.C. 7513(a).
    The air quality planning requirements for moderate PM10 
nonattainment areas are set out in subparts 1 and 4 of title I of the 
Act. EPA has issued guidance in its General Preamble describing EPA's 
views on how the Agency will review SIPs and SIP revisions submitted 
under title I of the Act, including those containing moderate PM10 
nonattainment area SIP provisions. 57 FR 13498 (April 16, 1992); 57 FR 
18070 (April 28, 1992). The General Preamble provides a detailed 
discussion of the EPA's interpretation of the Title I requirements.
    States with initial moderate PM10 nonattainment areas were 
required to submit, among other things, the following provisions by 
November 15, 1991:1

    \1\There are additional submittals associated with moderate 
PM10 nonattainment plans, such as a permit program for the 
construction of new and modified major stationary sources and 
contingency measures. See sections 189(a) and 172(c)(9). These 
submittals were required to be submitted in 1992 and 1993, 
respectively, and are not the subject of today's action which 
addresses only those plan provisions required to be submitted on 
November 15, 1991.
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    1. Provisions to assure that reasonably available control measures 
(RACM) (including such reductions in emissions from existing sources in 
the area as may be obtained through the adoption, at a minimum, of 
reasonably available control technology (RACT)) shall be implemented no 
later than December 10, 1993;
    2. Either a demonstration (including air quality modeling) that the 
plan will provide for attainment as expeditiously as practicable but no 
later than December 31, 1994, or a demonstration that attainment by 
that date is impracticable;
    3. Pursuant to section 189(c)(1), for plan revisions demonstrating 
attainment, quantitative milestones which are to be achieved every 3 
years and which demonstrate reasonable further progress (RFP) toward 
attainment by December 31, 1994;2 and

    \2\As discussed in the Federal Register notice proposing 
approval of this plan, the PM10 plan for the PPA does not 
demonstrate attainment by December 31, 1994, but rather includes the 
alternative demonstration that attainment by that date is 
impracticable. Therefore, section 189(c) does not apply. However, as 
discussed further in this notice, areas demonstrating that 
attainment is impracticable are required by section 172(c)(2) to 
demonstrate RFP. See Section IV. of this Notice, ``Reasonable 
Further Progress''.
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    4. Provisions to assure that the control requirements applicable to 
major stationary sources of PM10 also apply to major stationary 
sources of PM10 precursors, except where the Administrator 
determines that such sources do not contribute significantly to 
PM10 levels which exceed the NAAQS in the area.
    In today's rulemaking action, EPA is taking final action to approve 
Arizona's moderate PM10 SIP revision for the PPA, which includes 
the State's demonstration that attainment of the PM10 NAAQS by 
December 31, 1994, is impracticable for the PPA. EPA is also announcing 
its intention to reclassify the PPA as a serious nonattainment area 
pursuant to section 188(b)(2). However, EPA is not making a finding as 
to whether the PPA has attained the PM10 NAAQS in today's action, 
but, as discussed elsewhere in this Notice, will be doing so in a 
separate action in the coming months. See Section III. Once EPA 
determines the PPA has not attained the PM10 NAAQS, the area will 
be reclassified to serious by operation of law.

B. Proposed SIP Approval

    EPA proposed approval of the moderate area PM10 SIP revision 
for the PPA on July 28, 1994 (59 FR 38402). EPA's proposed approval was 
based on a preliminary finding that the State's submittal meets the 
requirements of the Act, including: (1) an inventory of all sources of 
PM10 in the nonattainment area; (2) provisions to implement RACM 
by December 10, 1993; and (3) a demonstration that attainment of the 
PM10 NAAQS by the moderate area attainment date, December 31, 
1994, is impracticable.
    EPA proposed simultaneously to approve Maricopa County Rule 310--
Open Fugitive Dust Sources, 311--Particulate Matter from Process 
Industries, 314--Open Outdoor Fires, and 316--Nonmetallic Mineral 
Mining and Processing, as new rules the State adopted as RACM for the 
PPA. EPA also proposed to reclassify the PPA as a serious area and 
invited public comment on whether final action should occur under 
section 188(b)(1) or 188(b)(2) of the CAA.

II. Today's Action

    In today's document, EPA is taking final action to approve the 
moderate area PM10 state implementation plan revision for the PPA. 
The SIP revision for the PPA was submitted by the State of Arizona on 
August 11, 1993 and March 3, 1994. Maricopa County Rule 314 was adopted 
by the State and submitted to EPA on January 4, 1990. The State also 
submitted a revised version of Maricopa County Rule 310--Open Fugitive 
Dust Sources on December 19, 1994. The County revised this rule to 
delete provision 221.9 of the Rule as requested by EPA. See 59 FR 
38407, July 28, 1994. Specifically, EPA is approving and incorporating 
by reference into the SIP the MAG 1991 Particulate Plan for PM10 
for the Maricopa County Area and 1993 Revisions, the Revised Chapter 9 
and Maricopa County Rule 311--Particulate Matter from Process 
Industries and Rule 316--Nonmetallic Mineral Mining and Processing, 
Maricopa County Rule 314--Open Outdoor Fires and Maricopa County Rule 
310--Open Fugitive Dust Sources. EPA is also stating its intention, but 
is not taking final action at this time, to reclassify the PPA under 
section 188(b)(2) of the Act. EPA is not taking final action on its 
proposal to reclassify the PPA under section 188(b)(1) of the Act.

III. Reclassification

    As stated above, EPA is not reclassifying the PPA in this document. 
However, EPA intends to propose reclassification of the PPA to a 
serious area pursuant to section 188(b)(2) of the Act.
    The Act provides two mechanisms for reclassifying moderate 
PM10 nonattainment areas as serious PM10 nonattainment areas. 
Section 188(b)(1) gives EPA the discretion to reclassify any area which 
EPA determines cannot practicably attain the NAAQS by the applicable 
attainment date at any time before the attainment date. In the case 
[[Page 18012]] of the PPA, the CAA-mandated attainment date was 
December 31, 1994. The second mechanism for reclassification, provided 
by section 188(b)(2), is to make a finding after the attainment date 
has passed that the area has not attained the NAAQS.
    The difference between these two mechanisms involves the timing of 
submittals of certain plan provisions. Under section 188(b)(1), if EPA 
were to take final action on its proposal to reclassify the PPA as 
serious (see 59 FR 38406, July 28, 1994) the State would be required to 
submit its serious area SIP revision in two parts. Within 18 months of 
the final action reclassifying the PPA, the State would be required to 
submit provisions to assure the implementation of best available 
control measures (BACM) no later than four years after the date of 
reclassification. The State's demonstration that the plan provides for 
attainment of the PM10 NAAQS by the serious area attainment date 
(December 31, 2001) would have to be submitted within four years of the 
date of reclassification.
    Under section 188(b)(2) of the Act, if EPA makes a determination 
after the moderate area attainment date has passed that the PPA has not 
attained the NAAQS, then within 18 months after the date of 
reclassification, the State is required to submit provisions to assure 
the implementation of BACM no later than four years after the date of 
reclassification and a demonstration that the plan will provide for 
attainment of the PM10 NAAQS by December 31, 2001. The practical 
difference in these two approaches is the timing of the submittal of 
the attainment demonstration and how it affects the BACM determination.
    Under section 188(b)(1), the State would initially develop its BACM 
determination in the absence of an attainment demonstration with the 
potential result that the chosen measures would not ultimately attain 
the PM10 standards by the applicable attainment date. Such a 
result, however, would not be revealed until several years later, when 
the air quality modeling analysis is conducted for the attainment 
demonstration. If, at that point, additional measures were found to be 
necessary for the area to attain the PM10 NAAQS, new measures 
would have to be developed, adopted and submitted to EPA. In contrast, 
under section 188(b)(2), all the required elements of the serious area 
plan including the attainment demonstration must be submitted to EPA 
within 18 months of reclassification. Thus, under section 188(b)(2), 
EPA believes the process of attaining the PM10 standards is 
expedited.
    In its notice of proposed rulemaking, EPA expressed its intent to 
reclassify the PPA under section 188(b)(2) of the Act. EPA believed 
that since the State originally concluded that the PPA could not 
practicably attain the PM10 NAAQS by December 31, 1994 when it 
developed its November 1991 plan submission and that, despite 
procedural delays and plan updates culminating in the 1993 and 1994 SIP 
submittals, this conclusion has not changed, the State has been on 
notice for more than three years that reclassification was likely. 
Under these circumstances, a delay of four years for the submission of 
a serious area attainment demonstration is unwarranted. Rather, the 
Agency believed that it is more appropriate to accelerate, to the 
maximum extent possible, the State's submission of a complete serious 
area plan to attain the PM10 NAAQS.
    Notwithstanding the reasons above, EPA stated in its proposed 
rulemaking that there could be valid reasons advanced for reclassifying 
the PPA under section 188(b)(1). Therefore, EPA proposed to reclassify 
the PPA using its discretionary authority under section 188(b)(1). EPA 
stated its intent to finalize the reclassification under section 
188(b)(1) only if it received compelling arguments from commenters. EPA 
received comments on the issue of reclassification from the Arizona 
Department of Environmental Quality (ADEQ), Maricopa Association of 
Governments (MAG), Maricopa County Environmental Services Department 
(MCESD), Arizona Department of Transportation (ADOT), and Arizona 
Center for Law in the Public Interest (ACLPI). The comments from ADEQ, 
MAG, MCESD, and ADOT all encouraged EPA to reclassify the PPA 
immediately under section 188(b)(1). These commenters were concerned 
that the State's ability to complete the required technical elements of 
the serious area SIP revision, particularly an improved and updated 
emission inventory and an accurate air quality analysis including air 
quality modeling, would require the longer submittal time for a 
demonstration of attainment afforded under section 188(b)(1) of the 
Act. Many of the commenters also argued that taking final action to 
reclassify the PPA before the moderate area attainment date would 
expedite the air quality benefits which would be provided by the 
serious area plan since the BACM implementation date would occur 
sooner.
    EPA has not been persuaded by these comments to reclassify the PPA 
under section 188(b)(1). EPA believes that the State has been aware for 
a number of years that, even taking into consideration the 
implementation efforts it has now undertaken in complying with the 
PM10 Moderate area planning requirements, that it was 
impracticable to demonstrate attainment of the PM10 NAAQS by 
December 31, 1994. Thus, EPA does not believe the State has provided 
any valid basis to delay submittal of an attainment demonstration by 
four years. Furthermore, the schedule for developing and submitting the 
technical elements of the serious area SIP revision is no different 
than the schedule for submitting a complete SIP revision for areas 
designated nonattainment after the passage of the 1990 CAA amendments. 
Under section 189(a)(2)(B) these areas are required to submit SIP 
revisions within 18 months after the date they are redesignated. The 
requirements for developing the technical elements of a serious area 
SIP are not substantially different from those for a moderate area.
    Regarding the BACM implementation date, the Act simply states that 
BACM is to be implemented no later than four years after 
reclassification to serious. Under the overall scheme of the Act, the 
State is certainly permitted and, in fact, encouraged to implement BACM 
on as expeditious a schedule as practicable before the four-year 
deadline.
    EPA also notes that ACLPI opposed reclassification of the PPA under 
188(b)(1) because it would have the effect of rewarding the State's 
delay in preparing its PM10 SIP by giving the State four years 
instead of 18 months to submit its serious area plan revision. However, 
EPA is not taking final action to reclassify the PPA under section 
188(b)(1). For the reasons stated above, EPA believes that 
reclassification under section 188(b)(2) is the appropriate action to 
take in this case. EPA will be reviewing the PM10 monitoring data 
for the PPA and will make an official determination of whether the PPA 
has attained the PM10 NAAQS by June 30, 1995 or sooner. To 
demonstrate attainment of the PM10 NAAQS by the applicable 
attainment date (December 31, 1994), the PPA would need to show that it 
has had no violations of the PM10 standards, 24 hour and annual, 
in the past three years (1992, 1993, and 1994). 40 CFR part 50, 
appendix K. The State recorded violations of both standards in 1992 and 
1993.

IV. Reasonable Further Progress

    Section 172(c)(2) of the Act states that nonattainment area plans 
shall require [[Page 18013]] reasonable further progress (RFP). RFP is 
defined by section 171(1) as ``such annual incremental reductions in 
emissions of the relevant air pollutant as are required by this part or 
may reasonably be required by [EPA] for the purpose of ensuring 
attainment of the applicable [NAAQS] by the applicable date.'' However, 
there is a gap in the statute in that the PM10 specific provisions 
of the Act do not clearly specify when and in what manner states 
containing PM10 nonattainment areas that ultimately demonstrate it 
is impracticable to attain the NAAQS by the Moderate area deadline, 
such as the PPA, which is the subject of this document, must 
demonstrate they have met the RFP requirement. While section 189(c)(1) 
of the Act requires PM10 SIP revisions to contain quantitative 
milestones which are to be achieved every 3 years until the area is 
redesignated attainment and which must also demonstrate reasonable 
further progress, that section, by its explicit terms, only applies to 
areas with ``plan revisions demonstrating attainment.'' However, while 
it appears that the Act does not provide specifically for a 
quantitative milestone reporting requirement showing RFP is met for 
areas that demonstrate it is impracticable to attain the PM10 
NAAQS by the applicable deadline, EPA nonetheless believes, based on 
the general nonattainment area provisions regarding RFP as well as the 
overall purpose and structure of Title I and Part D of the Act, that 
such areas are not thereby relieved of the obligation to periodically 
demonstrate that they are meeting the requirement for RFP. 
Consequently, for purposes of implementing the RFP requirement for such 
areas, EPA believes that where the language in section 171(1) indicates 
that the purpose of the RFP reductions is to ensure ``attainment of the 
applicable [NAAQS] by the applicable [attainment] date,'' the 
applicable attainment date for areas demonstrating that it is 
impracticable to attain would be the date set by section 188(c) when 
the area is reclassified as serious. Similarly, since the Act does not 
explicitly provide for states with PM10 nonattainment areas which 
demonstrate it is impracticable to attain to submit periodic reports 
demonstrating that RFP is being met, such as is required under section 
189(c)(1) for PM10 areas which demonstrate attainment, EPA 
believes it may invoke the discretionary authority provided the Agency 
under section 110(p) of the Act to require the submittal of such 
reports. That section states that ``any State shall submit'' such 
reports as EPA may require, and on such schedules as EPA may prescribe, 
providing information on specific data but also including ``any other 
information [EPA] may deem necessary to assess the development 
effectiveness, need for revision, or implementation of any plan or plan 
revision required under this Act.'' The initial RFP report for such 
areas is to be included in the SIP submittal containing the area's 
demonstration of impracticability, and should show that even though the 
emissions reductions achieved through the implementation of all RACM 
may not be enough to enable the area to demonstrate attainment by the 
Moderate area deadline of December 31, 1994, such implementation has 
resulted in ``incremental reductions'' in emissions of PM10 as the 
RFP definition in section 171(1) specifies. Once the area has been 
reclassified, subsequent RFP report submittals will be timed to reflect 
emissions reductions which will be achieved due to the implementation 
of BACM. In summary then, EPA's policy is that the requirement to 
submit periodic reports demonstrating that RFP (as defined in section 
171(1)) is being met applies equally to PM10 nonattainment areas 
that demonstrate attainment by the applicable deadline and to such 
areas that demonstrate it is impracticable to attain by such date; for 
the former areas the requirement applies pursuant to sections 189(c)(1) 
and 172(c)(2), for the latter areas the requirement applies pursuant to 
sections 172(c)(2) and 110(p). As described in greater detail elsewhere 
in this document, the Phoenix Planning Area, has provided information 
along with its impracticability demonstration, which proves to EPA's 
satisfaction that it has met the requirement to demonstrate RFP. 
Finally, the discussion in this document regarding the demonstration of 
RFP in PM10 nonattainment areas which demonstrate that attainment 
by the applicable attainment date is impracticable represents EPA's 
preliminary guidance on this issue, and is intended to clarify the 
confusion created by omissions in the Act and in prior EPA guidance. 
EPA also intends, in the very near future, to issue more comprehensive 
guidance on this issue.

V. Response to Comments on Proposed SIP Approval

    Only ACLPI commented on EPA's proposed approval of the SIP 
revision; other commenters addressed reclassification. EPA appreciates 
the comments submitted by ACLPI, which are detailed and thoughtful. 
Some of the comments raise difficult issues regarding the State's 
compliance with complex planning requirements, which often depend on 
coordination between a number of local governments. ACLPI's most 
detailed comments concern the State's implementation of RACM, 
particularly Transportation Control Measures (TCMs). In this document, 
EPA is providing its general response to ACLPI's comments on the 
implementation of RACM, and EPA is also providing very detailed 
responses concerning individual TCMs and other specific measures raised 
in ACLPI's comments in the Technical Support Document (TSD) 
accompanying this document.

A. Technical Issues

1. Monitoring
    Comment: The PM10 SIP revision for the PPA does not provide 
for the establishment and operation of a PM10 monitoring network 
which meets the requirements of EPA guidelines and regulations. 
According to a 1992 EPA audit, the monitoring network for the Phoenix 
area ``fails to meet many of the minimum CFR requirements''.
    Response: EPA disagrees with the comment. The PM10 SIP 
revision provides for establishing and operating a PM10 monitoring 
network in the PPA which meets the requirements of EPA guidelines and 
regulations. 40 CFR part 58; ``Guideline for the Implementation of the 
Ambient Air Monitoring Regulations 40 CFR Part 58.'' The relevant 
provisions of the PPA's monitoring network are in Appendix B, Exhibit 
14 of the SIP revision. Appendix B, Exhibit 14 also discusses proposed 
modifications to the network and the method by which the Maricopa 
County Environmental Services Department (MCESD) will address episode 
occurrences.
    Since a 1992 Re-Evaluation of the Maricopa County Air Pollution 
Control Program that was conducted by EPA, the MCESD has made and 
documented progress to meet the requirements in 40 CFR parts 50 and 58. 
The MCESD was required by the Agency to develop a Corrective Action 
Plan (CAP) to address deficiencies documented in the 1992 Re-
Evaluation. The progress on the CAP is being monitored by EPA, Region 
IX Air Quality Section and Compliance and Oversight Section, through 
review and verification of progress reports by MCESD and visits with 
the MCESD Air Monitoring Program personnel. EPA has also withheld 
federal grant money to encourage the MCESD to address CAP commitments 
and regulatory requirements in a timely manner. There have been 
improvements by MCESD, [[Page 18014]] including revising the Quality 
Assurance Program Manual (conditionally approved by Region IX pending 
minor additions), revamping its entire PM10 network with new 
equipment including four continuous PM10 samplers, quality 
assurance training for air monitoring staff, and others.
    Comment: A 1992 audit by Dames and Moore (DM) found that the 
monitoring network did not have adequate numbers of neighborhood scale 
and middle scale monitors, as directed by EPA guidance. Several 
homogenous subregions in the area have no monitoring station or one 
station. In addition, little or no monitoring is conducted within 500 
meters from several major sources. DM also found that the total number 
of monitoring stations is far below that required by EPA guidance. 
Under EPA spatial siting guidelines, there should be approximately 94 
monitoring stations in the nonattainment area. Yet the SIP shows only 9 
permanent PM10 stations. DM also found that the monitoring program 
was inadequately staffed.
    Response: EPA does not agree with the DM audit's comments on 
network adequacy, particularly concerning the necessary number of air 
monitoring sites recommended by DM. EPA criteria, in 40 CFR part 58, 
requires the Maricopa County network to consist of six (6) to ten (10) 
National Air Monitoring Stations (NAMS). The district is also required 
to operate State and Local Air Monitoring Stations (SLAMS). Part 58 
does not contain a numerical requirement for SLAMS. Maricopa County's 
network consists of six (6) NAMS, two (2) SLAMS, and five (5) Special 
Purpose Monitoring Stations (SPMS), for a total of thirteen (13) SLAMS 
(NAMS are defined as a subset of SLAMS). The network's only deficiency 
is that it lacks a category (a) NAMS site with a high concentration 
monitoring objective. But this deficiency is being corrected and a 
special purpose monitor has been set up at the proposed location for a 
Category (a) site. An EPA protocol provides that this sampler will be 
run for at least one year. The data will then be evaluated to determine 
if the site meets the objectives and should be proposed as a NAMS. 
However, even without a category (a) site, the MCESD air monitoring 
network is measuring PM10 values above the 24 hour standard.
    Part 58 requirements for ambient air monitoring networks intend the 
SLAMS networks to be representative of the four basic monitoring 
objectives stipulated in part 58 over the air basin. See 40 CFR part 
58, appendix D. Annual network reviews are requested of the districts 
and evaluated by the EPA to insure it is representative of the 
monitoring stations and to insure optimum use of resources. EPA, 
therefore, disagrees that 94 monitoring stations should be required in 
the nonattainment area.
    Comment: In a May 15, 1992 letter to the State EPA stated that the 
SIP must include provisions for follow-up monitoring and annual network 
reviews. The State was to insure that the monitoring network in place 
as of January 1, 1994, would be appropriate to evaluate attainment. EPA 
also stated that the SIP revision should include a plan for 
establishing PM10 episode monitoring stations. None of these 
requirements have been met in the form of enforceable, funded 
commitments by the State or local governments.
    Response: The State has addressed these requirements in the 
PM10 SIP revision for the PPA which is enforceable now on the 
State level, and which will be enforceable federally once this final 
notice becomes effective. Appendix B, Exhibit 14 contains additional 
information on the County's air quality surveillance system. Appendix 
B, Exhibit 15 contains the County's Rule 510--Air Quality 
Standards--which provides for the establishment of pollutant monitoring 
in accordance with EPA guidance and Federal regulations. Appendix B, 
Exhibit 16 contains the County's Rule 600 which addresses emergency 
episodes. Appendix B, Exhibit 17 contains further information on the 
State's procedures for the prevention of emergency episodes.
    Comment: The technical support document accompanying EPA's proposed 
rulemaking asserts that the SIP provides for correction of the 
monitoring deficiencies by January 1, 1994. We ask EPA to identify 
precisely where the SIP shows a legally enforceable commitment to this 
effect, and where the SIP shows a commitment of financial resources to 
complete the job. Moreover, because the January 1, 1994 date has long 
since passed, the correction of deficiencies should now be complete. We 
ask EPA to indicate where the State has documented actual correction of 
the deficiencies, if this has in fact occurred.
    Response: As discussed in the preceding response, Maricopa County 
has made documented progress in meeting all of the Federal air quality 
monitoring requirements. The appendices to the PM10 plan, cited 
above, provide specific information on the County's progress in 
correcting deficiencies with the monitoring network.
2. Emission Inventory
    Comment: The State's emission inventory is not accurate or current 
as required by the CAA.
    Response: EPA disagrees with this comment and believes that the 
emissions inventory is accurate to within an acceptable degree of 
uncertainty. The State followed EPA-recommended emissions inventory 
procedures in use at the time of inventory preparation. A degree of 
uncertainty is particularly associated with PM10 inventories 
because PM10 emissions are especially time- and place-specific. 
Emission factors from a study in one area may differ for another area. 
PM10 emissions also vary with activity levels and there are many 
activities, such as residential wood burning, for which there has been 
little accurate quantification. EPA recognizes that there are some 
differences between the emissions inventory fractions estimated from 
usual inventory methods and the source proportions determined from 
Chemical Mass Balance (CMB) modeling. However, EPA does not consider 
these differences to invalidate the inventory. The monitored results 
used in the CMB analysis reflect differences in distance, dispersion, 
and deposition of the emissions from various PM10 sources. A 
source's contribution at a particular monitor is not expected to be in 
the same proportion as its contribution to the area's total emissions. 
This explains the inventory/CMB discrepancies.
    Furthermore, accuracy of the emissions inventory is not critical to 
demonstrating impracticability of attainment. This is because a 
demonstration of impracticability may be based on the CMB apportionment 
results and not specifically on the emissions inventory. The inventory 
total is used only as a normalization scaling factor. EPA may have 
reached a different conclusion if, for example, the State sought to 
rely on a dispersion model, which requires a more accurate emissions 
inventory, instead of the CMB receptor model. However, based on the 
selected modeling, EPA believes that the inventory is sufficiently 
accurate to comply with the requirements of the Act and, more 
specifically, to serve as the basis for the demonstration of 
impracticability.
3. Modeling
    Comment: The SIP does not meet the requirements of the Act and EPA 
guidance for an adequate modeling analysis.
    Response: EPA disagrees with this comment. The State's modeling 
[[Page 18015]] complies with EPA guidelines, which allow for a receptor 
model such as CMB even though a dispersion model is recommended when 
possible. See Memorandum from John Calcagni, ``PM10 SIP 
Demonstrations Policy for Initial Moderate Areas'' (March 4, 1991).
    EPA recognizes that the State attempted to validate a dispersion 
model but was unsuccessful, in large part because of the degree of 
spatial and temporal accuracy required in the emissions inventory for 
use as input to a dispersion model. EPA believes that the State 
provided a reasonable level of effort to develop its dispersion model. 
Because it failed, however, the State is justified (and provided its 
justification in the SIP revision) in using a CMB receptor model. EPA 
has determined that the State's modeling complies with EPA guidelines.
    EPA also anticipates the PPA will be reclassified as a serious 
area. Reclassification will provide additional time for the State to 
improve its modeling. When the State ultimately seeks to make an 
attainment demonstration, EPA will apply more stringent criteria for 
the spatial and temporal accuracy of the emissions inventory, 
corroborating models, and treatment of secondary particulates. 
Nevertheless, EPA believes that the modeling submitted by the State in 
this PM10 SIP revision complies with the requirements and guidance 
established by EPA for a moderate area SIP revision and demonstration 
of impracticability.
    Comment: EPA's proposed finding that PM10 precursors do not 
contribute significantly to PM10 levels that exceed the NAAQS in 
the PPA was made without any objective standard against which to 
measure significance. EPA's proposed action on this issue is arbitrary 
and capricious.
    Response: EPA disagrees with this comment. EPA recognizes that on 
individual sampling days there were detectable contributions of one 
PM10 precursor, secondary ammonium nitrate. Yet the average 
overall contribution of secondary ammonium nitrate was less than five 
percent of the total annual inventory. See 1989-1990 Phoenix PM10 
Study, Volume II: Source Apportionment, DRI, April 12, 1991, p. S-2. 
This magnitude of contribution is not significant for purposes of this 
action, although EPA acknowledges that such a contribution might 
warrant further attention if the State were attempting to submit an 
attainment demonstration for the 24-hour NAAQS. EPA believes that a 
contribution of less than five percent secondary ammonium nitrate is 
within the degree of uncertainty and is near the ``noise'' level for 
CMB results.
    In general, because of the complexity of the chemistry involved, 
there is no EPA-recommended method and no scientific consensus for 
dealing with secondary particulates. A number of PM10 areas have 
dealt with this problem by assuming that secondary particulates are 
roughly proportional (or scale) to emissions of primary particulates. 
EPA believes that in the absence of better scientific or technical 
information, including better EPA guidance, this approach is 
reasonable. Consistent with this approach, the PPA scaled down their 
total PM10 emissions inventory to exclude the contributions from 
PM10 precursors. Indeed, if the PPA had included the contributions 
from PM10 precursors, this would have resulted in the recording of 
proportionately higher concentrations of PM10 in excess of the 
NAAQS. Therefore, if the PPA had explicitly accounted for the 
contribution of PM10 precursors, the State's conclusion that 
attainment is impracticable would be strengthened, not weakened.
4. Mobile Source Budget
    Comment: ACLPI states that in order to determine conformity of 
transportation plans, projects, and programs with this SIP, a mobile 
source emission budget must be identified.
    Response: EPA does not agree that the State was required to 
identify a mobile source emission budget. The moderate area SIP 
revision for the PPA demonstrates that attainment of the PM10 
NAAQS is impracticable by December 31, 1994. Mobile source emission 
budgets are only required to be identified in SIP revisions which 
demonstrate attainment. The preamble to EPA's transportation conformity 
rule states:

    Some moderate PM10 nonattainment areas may have submitted 
SIPs which demonstrate that the area cannot attain the PM10 
standard by the applicable attainment date. These areas have been or 
will be reclassified as serious areas under section 188(b) of the 
Clean Air Act. Such SIPs which do not demonstrate attainment do not 
have budgets and are not considered control strategy SIPs for the 
purposes of transportation conformity.

58 FR 62196, November 24, 1993.
    Thus, EPA's transportation conformity rule explicitly contemplated 
and determined that PM10 areas demonstrating impracticability, 
like the PPA, would not have provided for and would not be required to 
identify a mobile source emission budget until an approvable attainment 
demonstration is submitted.

B. Demonstration of Impracticability

    Comment: The State's demonstration of the impracticability of 1994 
attainment is contrary to both the language and purpose of the Act. The 
plain thrust of sections 188 and 189, in combination with section 172, 
is that states should make every effort to attain by 1994. Rather than 
searching for combinations of control measures that would produce 
timely attainment, the state merely lists 13 control measures, asserts 
that they are insufficient to attain by 1994, and then ``finds'' that 
impracticability has been demonstrated.
    Response: EPA disagrees. As discussed throughout this document, 
including in relevant responses to comments, EPA has determined that 
Arizona has implemented all RACM, and that the correct number of 
implemented measures is 67. EPA has also determined that the PPA has 
complied with the requirement of section 172(c)(2) that it demonstrate 
it is meeting RFP, by showing a measurable increment of PM10 
reductions between the baseline and the emissions reductions achieved 
through implementation of all RACM. EPA believes, therefore, that 
Arizona's SIP submittal does not contain mere assertions, but 
appropriate and acceptable demonstrations that are consistent, not only 
with the criteria contained in EPA's guidance, but with the Act's 
language and purpose as well. Again, as discussed further elsewhere in 
this Notice, EPA also believes that Congress recognized that many areas 
initially designated Moderate for PM10 would not be capable of 
developing SIP revisions which demonstrated attainment by the 
applicable attainment date. This is evident by the fact that, for 
PM10, the Act also allows States to demonstrate earlier than the 
applicable attainment deadline that implementation of RACM will not 
provide for attainment and, thus, that attainment by the Moderate area 
deadline is impracticable. Since this provision is unique to PM10 
(the Act generally provides fixed attainment dates for other pollutants 
which, if the area fails to meet, subjects it to a mandatory ``bump-
up''), it seems clear that the language and intent of the Act are to 
first provide PM10 areas with an opportunity to attain the NAAQS 
through the implementation of reasonable, but not necessarily 
exhaustive, efforts (i.e. RACM), and then to provide those areas that 
cannot achieve the NAAQS by the applicable attainment date with an 
alternative--to demonstrate that attainment is impracticable. However, 
such areas [[Page 18016]] must then go through a second planning effort 
which will require the implementation of more stringent measures, i.e. 
BACM.
    Comment: ACLPI commented that the State's demonstration of 
impracticability is deficient because it fails to address the 24 hour 
standard.
    Response: EPA disagrees that the impracticability of meeting both 
standards must be demonstrated. The PPA cannot be redesignated to 
attainment for PM10 until the State can demonstrate that the SIP 
provides for attainment of both the annual and the 24-hour NAAQS. 
Conversely, if the SIP demonstrates that even with the implementation 
of RACM it cannot attain any one of the standards (annual or 24-hour) 
by December 31, 1994, then it has demonstrated that PM10 
attainment is impracticable. As an additional matter, it should be 
noted that the PPA is proportionately farther above the 24-hour NAAQS 
than it is above the annual NAAQS. Thus, given that the 
impracticability of attaining the annual NAAQS has been demonstrated, 
EPA agrees with the State's conclusion that attaining the more 
difficult 24-hour NAAQS would likely be shown to be similarly 
impracticable.
    Comment: ACLPI commented that EPA should not evaluate 
practicability from the present point in time: i.e., whether attainment 
by December 31, 1994 is now practicable. The issue is whether timely 
attainment would have been practicable had the state implemented all 
RACM as expeditiously as practicable, and no later than December 10, 
1993. ACLPI also states that, based on the decision in Delaney v. EPA, 
898 F. 2d 687 (1990), the state would be obligated to provide for 
attainment as soon as possible if achievable via implementation of RACM 
as expeditiously as practicable.
    Response: EPA is concluding in this action that Arizona has met the 
Act's requirement to implement all RACM by December 10, 1993. EPA is 
also concluding that the State has demonstrated that attainment of the 
PM10 NAAQS by December 31, 1994, is impracticable even with timely 
implementation of all RACM. EPA therefore believes that the detailed 
explanations in this notice, including those contained in other 
relevant responses to comments, and in the accompanying technical 
support document should adequately address the issue raised by this 
comment. EPA further believes that the requirements that are relevant 
to consider are those contained in the CAA, as amended in 1990, and not 
statements taken from the Delaney opinion, which was construing 
requirements under the CAA as amended in 1977. As stated previously in 
this document, sections 172(c) and 189(a)(1)(C) when read together 
require the implementation of all RACM as expeditiously as practicable 
but no later than December 10, 1993. Additionally, section 189(a)(1)(B) 
requires either a demonstration that the plan provides for attainment 
by December 31, 1994 or a demonstration that attainment by that date is 
impracticable. Since EPA believes both that the RACM implementation 
requirement has been met and that an acceptable demonstration of 
impracticability has been provided by the State, no further response is 
required.

C. RACM

    Comment: ACLPI commented generally that the SIP, EPA Guidance and 
public comments identified 161 potential measures as RACM, but that the 
revised PM10 SIP rejected all but 13 of the measures without 
providing adequate justification. Similarly, the state adopted only one 
new transportation control measure, while failing to adopt, without 
explanation, every other potentially available TCM.
    Response: The general and detailed comments by ACLPI concerning 
RACM raise difficult issues concerning the State planning requirements, 
and EPA appreciates the time and thought that ACLPI has contributed to 
this process. However, ACLPI has misunderstood the number of measures 
that the State implemented or rejected as RACM. The revised PM10 
SIP did not reject all but 13 measures from the list of possible RACM. 
As discussed below and in substantial detail in the accompanying TSD, 
the State has implemented all possible RACM (in some cases, by 
demonstrating that partial implementation of a measure is all that was 
reasonable to implement by December 10, 1993) and has provided EPA with 
a reasoned justification for the rejection of the remaining measures as 
not constituting RACM.
    EPA disagrees with ACLPI regarding its RACM interpretation as it 
relates to transportation control measures (TCMs). In its comments 
regarding whether the State should have considered various proposed 
TCMs to be reasonably available, ACLPI asserts that the Court of 
Appeals for the Ninth Circuit held in Delaney v. EPA, ``that TCMs 
listed in section 108 of the Act are presumed to be reasonably 
available.'' ACLPI goes on to argue that ``Congress adopted and 
endorsed this decision in the 1990 Clean Air Act amendments,'' and 
cites for this proposition 136 Cong. Rec. S16971 (daily ed. Oct. 27, 
1990). In reliance on these claims, ACLPI concludes that Arizona ``has 
failed to rebut the [presumption regarding the] availability of the 
section 108 measures in the instant SIP, and therefore the SIP must be 
rejected.'' EPA disagrees with both assertions and with the conclusion 
ACLPI derives from them as well. In the General Preamble (57 FR 13560-
13561) EPA presents a detailed discussion of its interpretation of the 
RACM requirement, including implementation of TCMs. EPA continues to 
stand by that interpretation and the General Preamble discussion is 
explicitly referenced herein as forming part of the justification for 
the action being taken in this document.
    The portion of that discussion that relates to TCMs acknowledges 
that in pre-amended Act guidance EPA created a presumption that all of 
the TCMs listed in section 108(f) were RACM for all areas, and required 
areas to specifically justify a determination that any measure was not 
RACM based on local circumstances. However, EPA then explicitly 
repudiated that earlier guidance, explaining that, based on its 
experience in implementing TCMs in subsequent years, local 
circumstances varied to such a degree that it was inappropriate to 
presume that all of the measures listed in section 108(f) were per se 
reasonably available for all nonattainment areas. See 44 FR 20372-20375 
(April 4, 1979). Under EPA's revised guidance, all states are required, 
at a minimum, to address the section 108(f) measures, and where such a 
measure is determined to be reasonably available to implement it in 
accordance with section 172(c)(1).
    With respect to Delaney, the General Preamble states EPA's belief 
that the court did not hold, as ACLPI claims, that the statute required 
the Agency to interpret the RACM requirement to create a presumption 
that all TCMs are reasonably available. Instead, the court held that 
EPA itself had created such a presumption and, therefore, was bound to 
apply its own then-applicable 1979 RACM guidance. An administrative 
agency is permitted to revise or alter prior guidance so long as that 
guidance continues to represent a reasonable interpretation of the 
statutory requirement. Nothing in the court's decision precluded EPA 
from revising its own guidance based on later experience in 
implementing TCMs. EPA also believes that the Senate managers' 
statement endorsing the Agency's 1979 RACM guidance as construed by the 
Delaney court reflected the view of several legislators who had wanted 
the Senate Committee bill to require that all section 108(f) measures 
be implemented [[Page 18017]] in severe nonattainment areas. However, 
the final version of the Senate bill did not adopt this position. 
Consequently, any subsequent statements by any legislators that appear 
to consider the interpretation relating to TCMs in EPA's 1979 RACM 
guidance as still being applicable post-1990 could not be said to 
reflect the views of the Congress as a whole, and thus should not be 
accorded weight.
    Sections 172(c) and 189(a)(1)(C), along with relevant EPA guidance, 
require the State to implement all RACM provisions in its moderate area 
plan to reduce PM10 emissions. EPA's proposed approval of the 
revised PM10 SIP concluded that there was an initial list of 161 
potential RACM. See 59 FR 38404. EPA has determined that the State 
implemented 67 of those measures as RACM. Of the remaining 94 potential 
RACM, 62 measures were duplicates of other measures. Finally, EPA 
believes that the State acted in accordance with Agency guidance in 
determining that the remaining 32 measures were not in fact, reasonably 
available because either; (1) The source made a de minimis contribution 
of PM10 or (2) the measure was rejected on the basis of economic 
or technological infeasibility. Thus, EPA has determined that the State 
has satisfied its moderate area RACM requirements under sections 172(c) 
and 189(a)(1)(C).
    In some cases, RACM has been met through partial implementation of 
a measure, such as doubling rather than tripling bus service or 
implementing measures only in populous municipalities. The State 
provided more detailed justification explaining why partial 
implementation of many measures constitutes RACM in ``Summary of Local 
Government Commitments to Implement Measures and Reasoned Justification 
for Non-Implementation for the MAG 1991 Particulate Plan for PM10 
and Select Measures from the Clean Air Act Section 108(f)'' (``MAG 
Supplementary Document''). The Mag Supplementary Document was submitted 
at EPA's request after EPA proposed to approve the revised PM10 
SIP in an effort to respond to comments received by EPA claiming that 
the SIP submittal did not contain sufficient detail regarding the 
State's justification for rejecting potential RACM. The MAG 
Supplementary Document has been included in the Administrative Record 
for this rulemaking and, to the extent that it provides additional 
detail and elaborates on the State's reasoning regarding its RACM 
determination, forms, in part, a complementary basis for EPA's final 
approval of the State's revised PM10 SIP, including EPA's finding 
that the State complied with its obligation under Sections 172(c) and 
189(a)(1)(C) to implement all RACM.
    The list of 67 RACM the State has implemented includes 41 measures 
that were adopted in the State's 1993 Carbon Monoxide and Ozone Plans 
(``1993 CO Plan''). EPA believes that adoption and inclusion of the 
measures in the 1993 CO Plan is a sufficiently meaningful and legally 
binding action by the State which, moreover, constitutes compliance 
with the Act's requirement to submit a plan which includes provisions 
to assure that RACM is implemented no later than December 10, 1993. 
ACLPI's comments on individual measures addressed in the accompanying 
TSD state that certain measures have not been adopted ``in committed 
form.'' For the measures in the 1993 CO Plan, EPA believes that the 
State has provided adequate evidence that the plan is being implemented 
and is enforceable. The State's 1993 CO plan builds upon the control 
strategy developed and adopted for the MAG 1987 CO plan. Many of the 
measures in the 1993 CO plan continue implementation of transportation 
control measures included in the 1987 CO plan. The 1993 CO plan also 
contains new control measures that were not in the 1987 CO plan. EPA is 
aware that, for the most part, the State is not claiming PM10 
emission reduction credits for the measures developed for their CO and 
ozone plans. The PM10 SIP does take emission reduction credit for 
Maricopa County's Trip Reduction Ordinance and the operation of two 
alternative fueled buses. The State explained instead that reductions 
from RACM in the 1987 CO Plan were calculated in the 1989 baseline 
PM10 emission inventory. These CO measures may qualify as RACM 
regardless of whether emissions reduction credit can be assigned, as 
noted by EPA's proposed approval, stating: ``These CO measures are 
included in the PM10 SIP revision because they could also reduce 
particulate matter emissions.'' 59 FR 38404. EPA has not received 
direct adverse comment on the proposal to include the CO measures in 
the State's revised PM10 SIP as RACM, and is therefore taking 
final action on that proposal. The 41 measures from the CO and Ozone 
Plans that are treated as RACM in the revised PM10 SIP are listed 
in the TSD, Attachment #2, for this NFRM.
    In addition to RACM from the 1993 CO Plan, the State is 
implementing measures required by national rulemakings. These measures 
are also RACM for the moderate area PM10 SIP. For example, the 
State must ensure that cleaner commercial aircraft land in the PPA 
based on the federal Airport Noise Control Act, 49 U.S.C. App. 2151 
(1990) (ANCA). Municipalities in the PPA are required to comply with 
ANCA. Thus, even though the clean aircraft requirement is established 
by ANCA, it also satisfies the State's obligation to assure 
implementation of RACM. EPA believes the State may satisfy the RACM 
obligation pursuant to compliance with ANCA rather than through 
adoption in the revised PM10 SIP of measure No. 45, ``Replacement 
of High Emitting Aircraft,'' offered in the public comments. The 
accompanying TSD lists RACM which are based on national rulemakings or 
emissions standards.
    For diesel fuel controls, EPA believes that the State has 
adequately demonstrated that partial implementation of this measure 
through compliance with national diesel fuel standards is RACM, and 
that the State has also justified rejecting implementing the California 
diesel fuel standards as RACM. Likewise, the State's partial 
implementation of a measure requiring conversion of its diesel fleet to 
clean fuels constitutes RACM. The State has also partially implemented 
measures regulating nonroad utility heavy duty engines and utility 
engines through compliance with national standards. EPA believes that 
partial implementation of this measure is all that was reasonable for 
the state to implement by December 10, 1993. The implementation of 
controls associated with diesel fuels and engines is discussed more 
fully in the accompanying TSD. The TSD also discusses the State's 
justification for rejecting as RACM an inspection and maintenance 
testing program for diesel vehicles.
    Comprehensive rules are another source of RACM. The State submitted 
several comprehensive rules, such as Rules 310, 311, 314 and 316, that 
encompass RACM that are separate from the initial list of 161 possible 
measures. For example, Rule 310 addresses 13 of the 15 measures that 
EPA considered to be reasonably available for the control of fugitive 
dust. See 59 FR 38404. The accompanying TSD provides a more detailed 
discussion of RACM for fugitive dust based on implementation of Rule 
310. To control residential wood combustion, Maricopa County has 
adopted a new rule, Residential Woodburning Restriction Ordinance 
(RWRO), and the State has included a provision in HB 2001 that provides 
a personal income tax deduction for people that purchase EPA-certified 
wood heaters. The County also has a [[Page 18018]] public education and 
awareness program in place to inform residents of the impacts of 
residential wood combustion on air quality and public health and the 
requirements of the County's woodburning restriction ordinance. These 
measures cover all of the four RACM listed by EPA in its General 
Preamble to address particulate matter emissions from residential wood 
combustion. The State's adoption of the County's RWRO satisfies the 
obligation to adopt measures to reduce emissions from residential wood 
combustion. As with measures in the 1993 CO Plan, EPA believes that the 
State has adopted the RWRO in sufficiently meaningful legal form to 
ensure that RACM is being implemented in compliance with the Act. The 
TSD also discusses this measure.
    From the initial list of 161 possible RACM, EPA determined that 62 
measures are duplicates of others and consequently did not require any 
further consideration. These duplicate measures are also listed in the 
TSD, Attachment #1.
    Finally, EPA has determined that the State was justified in 
rejecting 32 of the remaining measures from the list of 161 possible 
RACM. These measures, which are listed in the TSD, Attachment #3, were 
discussed in EPA's proposed approval, 59 FR 38404, and are not 
reasonably available because they are either de minimis or economically 
or technologically infeasible. Certain measures are not reasonably 
available because the contribution from the source is de minimis in the 
PPA, such as Public Comment No. 37 which provides for reducing 
emissions from ship berthing. There are no ship berthing facilities in 
the PPA. Alternatively, the State has provided reasoned justifications 
to reject certain measures as RACM based on economic or technological 
infeasiblity, such as railroad electrification. Those measures rejected 
from the initial list of 161 possible RACM, and the justifications for 
such rejections, are provided in the accompanying TSD.
    For the reasons stated above, EPA has determined that the State has 
satisfied its obligation under the Act to submit a plan containing 
provisions to assure that RACM has been implemented by December 10, 
1993, and, consistent with Agency guidance, has provided a reasoned 
justification for rejecting other potential measures on grounds that 
they are not RACM. The accompanying TSD provides a detailed response to 
each specific measure or type of measure that was raised in ACLPI's 
comments on the RACM portion of EPA's proposed approval of the State's 
revised PM10 SIP. Many other measures were duplicates of measures 
that were either adopted or rejected. For the remaining measures which 
the State rejected, EPA has given careful consideration to ACLPI's 
thorough comments. On balance, however, the State has complied with its 
obligation to provide EPA with a reasoned justification for the 
rejection of the remaining potential RACM.

D. RFP

    Comment: The SIP fails to show RFP as required by section 172(c)(2) 
of the Act. According to the SIP, emissions of PM10 increase in 
1994 compared to the baseyear.
    Response: EPA disagrees with the commenter's assertion that the SIP 
does not demonstrate reasonable further progress in reducing PM10 
emissions. While the State's demonstration showed a small reduction in 
PM10 emissions from the implementation of Maricopa County's Rule 
310--Fugitive Dust, EPA believes that the emission reduction that the 
State associated with this rule was overly conservative. When the State 
calculated the emission reduction potential for Rule 310, they only 
applied the control effectiveness to the urban portions of the PPA. EPA 
believes the control effectiveness should have been applied to the 
entire nonattainment area since the rule applies throughout Maricopa 
County which includes the entire nonattainment area. When EPA 
recalculated the emission reduction benefits of the SIP's control 
strategy the reduction potential equals 8,677 tons per year. The 1989 
base year inventory is 40,975 tons per year and was projected to grow 
to 45,981 tons per year in 1994. Therefore, the total 1994 projected 
inventory after application of RACM would equal 37,304 tons per year 
which shows, consistent with EPA's guidance on demonstrating RFP, which 
is described in greater detail earlier in this notice, that the area 
has indeed made progress in reducing emissions from the base year 
total, and thus has demonstrated it has met the requirements of section 
172(c)(2) for the period 1990-1994.

E. Rules

    Comment: Rule 310 is not approvable because the rule does not meet 
the Act's or EPA's criteria for enforceability. The rule must make 
clear to whom it applies and be sufficiently specific that a source is 
fairly on notice as to the standard it must meet. No threshold level of 
dust generation is specified, leaving sources to guess as to when the 
ordinance will be triggered.
    Response: Rule 310 does specify the sources that are subject to 
control. Rule 310 applies to any activity, equipment, operation and/or 
man-made or man-caused condition or practice capable of generating 
fugitive dust. Section 300 of the Rule further specifies the types of 
activities and sources of fugitive dust that are subject to the rule's 
requirements (e.g., vehicle use in open areas and vacant parcels; 
unpaved parking areas/staging areas; unpaved haul/access roads; 
disturbed surface areas; vacant areas; material handling operations; 
material transport; haul trucks; roadways, streets and alleys; and 
cattle feedlots and livestock areas). Further, as discussed in more 
detail in response to the next comment, the requirements of Rule 310 
are triggered if a source of fugitive dust violates either the 20% 
opacity standard in Section 301 or the requirement to implement RACM in 
Sections 301 through 314. Thus, any activity that causes visible 
emissions in excess of 20 percent opacity or any activity that is 
carried out contrary to the implementation of RACM is a violation of 
Rule 310. For new sources of fugitive dust, Rule 310 requires 
compliance with an approved dust control plan as implementation of 
RACM, subject to approval by the control officer; existing sources of 
fugitive dust are required to comply with the RACM defined in the Rule.
    Comment: The standards of performance [in Rule 310] are equally 
vague. The rule merely states that reasonably available control 
measures must be applied. That term is in turn defined merely by 
listing examples of vaguely described control steps without requiring 
use of any specific measure or a specific level of effort in any 
specific context. Thus, any specific level of control that the County 
seeks to impose will be subject to challenge.
    Response: ACLPI's comments tend to oversimplify the requirements of 
Rule 310. Because of the very many different circumstances under which 
fugitive dust can be generated, it would be nearly impossible for the 
County to predict every situation and prescribe a specific control 
measure for it. As noted above, Rule 310 contains two standards to 
enforce. One standard with which all sources are required to comply is 
the 20% opacity limit. The second standard is the RACM requirement. New 
sources of fugitive dust are required to comply with approved dust 
control plans, which become enforceable as permit conditions. For 
existing sources of fugitive dust, Rule 310 addresses the variability 
of sources and activities by either prescribing RACM (see, e.g., 
Section 311.2) or listing potential reasonably available fugitive dust 
control measures (see, e.g., Sections 306 [[Page 18019]] & 221). Yet 
Rule 310 allows a source to tailor its own control strategy to fit its 
particular situation and EPA believes that such flexibility is 
necessary. When the activity or situation does not involve a high 
degree of variability, the measures that apply to that source are 
typically more prescriptive. For example, Section 311.2, which applies 
to all haul trucks operating in the PPA, sets forth specific 
requirements as RACM. If haul trucks fail to implement these measures, 
there is a violation of Rule 310. Even if the haul trucks comply with 
Section 311.2, but still violate the 20% opacity standard, there is a 
violation of Rule 310. Other sections of the rule are equally 
enforceable through permit conditions. Section 303 of Rule 310 requires 
that a permit application for any new source subject to Section 302 of 
Rule 310 shall include a Control Plan to prevent or minimize fugitive 
dust, and the Control Plan must be approved by the County Control 
Officer. If the County determines through a violation of the separate 
20% opacity standard that a Control Plan is not sufficient to control 
fugitive dust, the responsible party is required to revise the control 
plan accordingly. Thus, the County will be able to enforce the 
provisions of this Rule 310 through two standards: the 20% opacity 
standard and the requirement to implement RACM through a Control Plan 
or as defined in the Rule.
    The original version of Rule 310 that was submitted to EPA 
contained a provision that EPA believed threatened the enforceability 
of the rule. The original rule contained a provision (221.9) that 
allowed the Control Officer to approve the use of alternative control 
methods not listed in the rule. This provision has since been deleted 
from Rule 310.
    Comment: The State and County have not committed the necessary 
resources and personnel to ensure enforcement of rules 310, 311, 314, 
and 316, as required under section 110(a)(2)(E) and EPA guidance. Nor 
does the SIP contain a program to provide for enforcement of any of the 
SIP control strategies, as required by section 110(a)(2)(C) of the Act.
    Response: The County has committed the necessary resources and 
personnel to implement rules 310, 311, 314, and 316. Details on the 
level of personnel and funding, as required by section 110(a)(2)(E) of 
the Act, as well as enforcement strategies as required by section 
110(a)(2)(C) of the Act are provided in the document ``MAG 1991 
Particulate Plan for PM10 for the Maricopa County Area and 1993 
Revisions, Commitments for Implementation, Volume Three'', section 
entitled ``Maricopa County''.

F. Other

1. Public Comment
    Comment: In the process of developing and submitting the PM10 
SIP revision for Phoenix, MAG and the State have on several occasions 
failed in their responsibility to seriously consider public comment 
prior to adopting plans.
    Response: The State has provided a section in all of its PM10 
SIP submittals which includes all public comments received and the 
State's responses to those comments.
2. State Assurances
    Comment: The PM10 SIP does not contain, as required by section 
110(a)(2)(E)(iii) of the CAA, the necessary assurances that, where the 
State has relied on a local or regional government, agency, or 
instrumentality for the implementation of any plan provision, the State 
has responsibility for ensuring adequate implementation of such plan 
provision.'' While the State contends that this requirement is met by 
A.R.S. Sec. 49-406.J, the process laid out by this State statute does 
not meet the plain requirements of section 110(a)(2)(E)(iii) and is 
completely inconsistent with the Act's requirements for SIP 
enforceability, timely implementation of control measures, and 
expeditious attainment.
    Response: EPA has historically adopted a rule of reasonableness in 
construing the language of section 110(a)(2)(E)(iii) of the Act with 
respect to the extent to which the State must show that its plan 
evinces a showing of responsibility sufficient to ensure adequate 
implementation of the plan's provisions by local or regional 
governments. EPA, for example, does not require the State to adopt into 
its own plan the local government's implementing provisions, but has 
considered it sufficient for the State to describe and reference those 
provisions and the accompanying descriptions of the local 
municipalities intended implementation actions. The State has included 
in its plan submission a copy of the Arizona Laws Relating to 
Environmental Quality, Sec. 49-406. J. of which contains the assurances 
required by section 110(a)(2)(E). If any person fails to implement an 
emission limitation or control measure, the relevant State official is 
required to issue a written finding to that effect, which may also 
necessitate the holding of a conference regarding the failure with the 
offending person. If a determination is made that the failure has not 
been corrected, the attorney general, at the responsible official's 
request, must file an action, seeking either ``a preliminary 
injunction, a permanent injunction, or any other relief provided by 
law.'' Section 49-407 of the Arizona Revised Statutes provides that 
citizens may sue the director to perform his or her duty. While some 
opportunity is provided to rectify problems short of taking legal 
action, EPA does not believe this is unreasonable, nor that the 
affected State officials ultimately have discretion to ignore the law's 
requirements. The comment engages in some speculation, describing 
several possible scenarios under which implementation by the local 
authorities may not occur. Despite these concerns--which are admittedly 
speculative--EPA believes, based on its experience in administering 
this provision of the Act, that the relevant sections of the State's 
law provides an adequate degree of assurance that the control measures 
in the plan are enforceable and will be fully implemented.

VI. Executive Order 12866

    The Office of Management and Budget has exempted this regulatory 
action from Executive Order 12866 review.

VII. Regulatory Flexibility

    Under the Regulatory Flexibility Act, 5 U.S.C. 600 et seq., EPA 
must prepare a regulatory flexibility analysis assessing the impact of 
any proposed or final rule on small entities. 5 U.S.C 603 and 604. 
Alternatively, EPA may certify that the rule will not have a 
significant economic impact on a substantial number of small entities. 
Small entities include small businesses, small not-for- profit 
enterprises, and government entities with jurisdiction over populations 
of less than 50,000.
    SIP approvals under section 110 and subchapter I, part D of the 
Clean Air Act do not create any new requirements, but simply approve 
requirements that the State is already imposing. Therefore, because the 
federal SIP approval does not impose any new requirements, I certify 
that it does not have a significant impact on small entities affected. 
Moreover, due to the nature of the federal-state relationship under the 
Clean Air Act, preparation of a regulatory flexibility analysis would 
constitute federal inquiry into the economic reasonableness of state 
action. The Clean Air Act forbids EPA to base its actions concerning 
SIPs on such grounds. Union Electric Co. v. U.S. E.P.A., 427 U.S. 246, 
256-66 (S.Ct. 1976); 42 U.S.C. 7410(a)(2). [[Page 18020]] 

List of Subjects in 40 CFR Part 52

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

    Note: Incorporation by reference of the State Implementation 
Plan for the State of Arizona was approved by the Director of the 
Federal Register on July 1, 1982.

    Dated: February 28, 1995.
Felicia Marcus,
Regional Administrator.

    Part 52, chapter I, title 40 of the Code of Federal Regulations is 
amended as follows:

PART 52--[AMENDED]

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

    Authority: 42 U.S.C. 7401-7671q.

Subpart D--Arizona

    2. Section 52.120 is amended by adding paragraphs (c) (67)(i)(B), 
(73), (74), and (77) and by adding and reserving paragraphs (c) (72), 
(75), and (76) to read as follows:


Sec. 52.120  Identification of plan.

* * * * *
    (c) * * *
    (67) * * *
    (i) * * *
    (B) Amended Maricopa County Division of Air Pollution Control Rule 
314, adopted July 13, 1988.
* * * * *
    (72) [Reserved]
    (73) Plan revisions were submitted on August 11, 1993 by the 
Governor's designee.
    (i) Incorporation by reference.
    (A) The Maricopa Association of Governments 1991 Particulate Plan 
for PM10 for the Maricopa County Area and 1993 Revisions, Chapters 
1, 2, 3, 4, 5, 6, 7, 8, 10 and Appendices A through D, adopted August 
11, 1993.
    (74) Plan revisions were submitted by the Governor's designee on 
March 3, 1994.
    (i) Incorporation by reference.
    (A) Maricopa County Division of Air Pollution Control new Rule 316, 
adopted July 6, 1993, and revised Rule 311, adopted August 2, 1993.
    (B) The Maricopa Association of Governments 1991 Particulate Plan 
for PM10 for the Maricopa County Area and 1993 Revisions, Revised 
Chapter 9 adopted on March 3, 1994.
    (75) [Reserved]
    (76) [Reserved]
    (77) Amended regulations for the Maricopa County Division of Air 
Pollution Control submitted by the Governor's designee on December 19, 
1994.
    (i) Incorporation by reference.
    (A) Maricopa County Division of Air Pollution Control Rule 310, 
adopted on September 20, 1994.

[FR Doc. 95-8215 Filed 4-7-95; 8:45 am]
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