Promulgation of Federal Implementation Plan for ArizonaPhoenix PM-10 Moderate Area; Disapproval of State Implementation Plan for ArizonaPhoenix PM-10 Moderate Area
Federal RegisterAug 3, 1998
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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.
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\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.
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\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.
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\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.
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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
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\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.
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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.
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\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).
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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.
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\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.
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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.
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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
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\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).
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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.
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\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.
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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
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\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.
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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\
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\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).
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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\
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\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.
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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.
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\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.
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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 fu
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