[Federal Register Volume 62, Number 150 (Tuesday, August 5, 1997)]
[Proposed Rules]
[Pages 42088-42090]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-20582]
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ENVIRONMENTAL PROTECTTION AGENCY
40 CFR Part 52
[CO-001-0017 and CO-001-0018; FRL-5869-4]
Clean Air Act Approval and Promulgation of the Denver, Colorado
Mobile Source Emissions Budgets for PM10 and NOX
AGENCY: Evironmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: EPA is requesting additional comments on certain aspects of
the State Implementation Plan (SIP) revisions for the Denver
PM10 and NOX mobile source emissions budgets that
were submitted by the Governor of Colorado. EPA initially proposed
approval of the SIP revisions on October 3, 1996 (61 FR 51631). During
that rulemaking's public comment period, EPA received several comments.
Due to the complexity of the issues, EPA is asking interested parties
to submit additional information on two issues. This information may
help EPA make a more informed decision on the appropriateness of
approving both the PM10 and NOX emissions budget
SIPs.
DATES: Comments on this request for additional information must be
received in writing on or before September 4, 1997.
ADDRESSES: Copies of the State's original PM10 and
NOX emissions budget SIPs, comments received during the
public comment period, and other information are available for
inspection during normal business hours at the Environmental Protection
Agency, Region VIII, Air Program, 999 18th Street, 3rd Floor, South
Terrace, Denver, Colorado 80202-2466.
FOR FURTHER INFORMATION CONTACT: Callie Videtich at (303) 312-6434.
SUPPLEMENTARY INFORMATION:
I. Background
On July 18, 1995, and April 22, 1996, the Colorado Governor
submitted revisions to the Denver PM10 SIP which establish
mobile source emissions budgets for PM10 and NOX
respectively. These budgets are used under EPA regulations for making
transportation related conformity determinations as required by section
176(c) of the Act. EPA's transportation conformity rule provides that
these budgets establish a cap on motor vehicle-related emissions which
cannot be exceeded by the predicted transportation system emissions in
the future unless the cap is amended by the State and approved by EPA
as a SIP revision and attainment and maintenance of the standard can be
demonstrated.
EPA proposed approval of both emissions budgets on October 3, 1996
(61 FR 51631) along with the Denver PM10 SIP. Following a 60
day public comment period, EPA finalized approval of the Denver
PM10 SIP on April 17, 1997 (62 FR 18716). EPA did not take
final action on the emissions budget submittals in order to more
thoroughly consider comments received on the proposals during the
public comment period.
II. This Action
Based upon a thorough review, EPA has concluded that additional
information is needed in order for EPA to make an informed decision
about certain aspects of the SIPs based upon public comments responding
to our proposed approval of the PM10 and NOX
emissions budgets. EPA is seeking additional information on the two
issues outlined below.
1. It appears to EPA that the Colorado legislature, through Senate
Bill 95-110 (codified at section 25-7-105(1)(a)(III), C.R.S.), changed
the PM10 emissions budgets that the Colorado Air Quality
Control Commission (AQCC) had adopted on February 16, 1995. EPA wishes
to take comment on whether the PM10 budgets that were
ultimately submitted to EPA for approval were adopted after reasonable
notice and public hearing as required by section 110 of the Clean Air
Act (CAA). Section 110(a)(2) of the CAA provides that ``[e]ach
implementation plan submitted by a State under this Act shall be
adopted by the State after reasonable notice and public hearing.''
Robert Yuhnke, on behalf of COPIRG, Colorado Environmental Coalition,
Citizens for Balanced Transportation, American Lung Association of
Colorado, Environmental Defense Fund, and Ms. Stephanie Mines, and
Frank Johnson, on behalf of the Colorado Attorney General's Office,
have submitted information that touches on this question. Their letters
may be examined at the address listed above. EPA wishes to obtain
further comment on this issue. In particular, EPA is concerned that the
legislative action did not meet the CAA's requirements for notice and
public hearing and that no subsequent public hearing was held before
the AQCC. The Colorado Attorney General's Office has suggested that
hearings held before the AQCC in September and October 1994, and in
February 1995, were adequate to satisfy the CAA's hearing requirement,
and that there is no requirement that a hearing be held at every step
in the State review process. It has also indicated that the State
legislative process is an open and public process and that the
legislators are accountable to the electorate.
2. Commentors were concerned that the budgets do not demonstrate
attainment considering growth in non-mobile sources, and that the
adopted NOX budget of 119.4 tons per day was not consistent
with the NOX inventory of 102.7 tons per day used in the
maintenance demonstration. (In the following discussion, EPA uses the
terms ``mobile source'' and ``mobile source emissions'' to mean ``motor
vehicle'' and ``motor vehicle emissions,'' consistent with the State's
submittal. Neither the State's budget submittal nor EPA's conformity
rule regulate emissions from non-road mobile sources.)
The Regional Air Quality Council's(RAQC's) proposal to the AQCC to
increase the emissions budget was based on an analysis showing that the
Denver modeling region could tolerate mobile source PM10
emissions of 221 tons per day in 2015 before a violation of the
PM10 standard would occur. (This analysis was not submitted
at the time the budgets were submitted to EPA, but was referenced in
[[Page 42089]]
proceedings before the RAQC and the AQCC in 1994 and was provided by
the RAQC on April 23, 1997.) By contrast, the attainment and
maintenance demonstrations are based on emissions levels of 41 and 44
tons per day, respectively. The RAQC defined the difference between 44
tons per day and 221 tons per day (i.e., 177 tons) as a ``safety
margin'' in emissions and assigned 16 tons of this safety margin to
mobile source PM10 (i.e., raised the SIP's budget to 60 tons
per day) in order to facilitate future conformity determinations by the
Denver Regional Council of Governments (DRCOG). The RAQC and the State
justified the increase of the budget from 44 to 60 tons by noting that
this increase represented only a small portion of the available safety
margin. The RAQC's analysis assumed 2015 emissions levels of all non-
mobile sources, and assumed zero NOX emissions from mobile
sources (i.e., that all emissions were direct PM10
emissions).
The RAQC's analysis is strictly a mathematical analysis of the
maximum level of emissions that could theoretically be accommodated in
each grid in the modeling domain; it is not an analysis of any
particular projected growth scenario for Denver. The analysis assumes
equal levels of emissions in each grid of the modeling domain, from
downtown Denver to rural outlying portions of the domain. Although the
safety margin provision in Section 93.132(b) of the conformity rule
applies only to existing adopted SIPs which contained a built-in safety
margin, section 93.132(a) clearly envisions cases in which a SIP
quantifies a safety margin and explicitly assigns some or all of it to
the mobile source budget. This general provision applies to situations
where a state reanalyzes a SIP to quantify and assign the safety
margin.
As noted above, the RAQC's analysis accounts for growth in non-
mobile sources of emissions to 2015 levels but does not account for
mobile source NOX (all mobile source emissions are treated
as PM10 emissions). To quantify the impact of this omission,
EPA reviewed documents related to the attainment demonstration and
found that an increase of 10.4 tons per day of NOX would
lead to a 1.0g/m3 increase in PM10 concentrations
(source: July 7, 1994 and February 8, 1995 Kevin Briggs memoranda).
Thus, the adopted budget of 119.4 tons per day of NOX would
equate to approximately 22 tons per day of PM10. Subtracting
this 22 tons from the RAQC's original 221 ton budget, a 199 ton
PM10 budget along with a 119.4 ton NOX budget
would still provide for attainment of the NAAQS. However, the State has
only revised the SIP to establish a 60 ton PM10 budget and a
119.4 ton NOX budget. Thus, NOX emissions of
119.4 tons per day can be easily by accommodated within the 177 ton
PM10 safety margin identified by the RAQC and the State.
The fact that the 119.4 ton per day NOX budget can be
accommodated within the safety margin identified by the RAQC is one
reason that EPA is not concerned that this budget is inconsistent with
the SIP's 1998 maintenance demonstration budget of 102.7 tons per day.
The other reason is the SIP's requirement that each conformity
determination must include a modeling analysis demonstrating attainment
of the PM10 NAAQS (discussed below). Even though the adopted
NOX budget is higher than the inventory used in the
maintenance demonstration, DRCOG's transportation plans and
transportation improvement programs (TIPs) must still pass a modeling
analysis showing attainment of the NAAQS, incorporating the impacts of
the 119.4 ton NOX budget, or the plans and TIPs cannot be
found to conform.
EPA believes that the NAAQS are protected by the SIP's requirement
for dispersion modeling each time a conformity analysis is conducted.
The SIP requires that DRCOG support each conformity determination with
a dispersion modeling analysis that shows that each grid in the
modeling domain will be in attainment, considering the emissions
expected from implementation of the transportation plan or TIP. If the
modeling analysis shows that emissions reductions are needed in any
locations in order to provide for attainment of the NAAQS, it is
incumbent upon DRCOG to identify and ensure implementation of any
measures needed to provide those reductions. Thus, DRCOG must satisfy
two types of tests to demonstrate conformity: compliance with the 60
ton PM10 budget and the 119.4 ton NOX budget, and
a dispersion modeling analysis showing no violations.
The commentors quote the preamble to EPA's November 24, 1993
transportation conformity regulation in objecting to the use of
dispersion modeling in conformity determinations. EPA believes that the
Act precludes the use of dispersion modeling as a substitute for an
emissions budget test. However, EPA's conformity rule did not
anticipate situations where a state would wish to require a regional
dispersion modeling analysis in addition to an emissions budget test.
EPA does not believe that such an application of dispersion modeling is
precluded by either the Act or the conformity rule. One commentor
suggested that the State adopt subregional emissions budgets in lieu of
requiring dispersion modeling; however, as a practical matter, the
requirement for dispersion modeling has the same effect as establishing
subregional budgets because in either case a certain target level of
emissions has to be met in each grid in order for each grid to show
attainment.
In fact, the requirement for dispersion modeling in addition to a
budget test is arguably more protective of the NAAQS than the budget-
only process envisioned by the conformity rule. First, a supplemental
requirement for dispersion modeling is certainly more protective than a
region-wide budget alone. The commentors argue that subregional budgets
for problem grids could be identified. However, establishing fixed
subregional budgets through the SIP process would not provide the
flexibility to consider future growth patterns. Due to changes in the
geographic distribution of growth, NAAQS problems could emerge in areas
of the city outside of the area for which subregional budgets had been
established, in the geographic area covered only by the region-wide
budget. A requirement for dispersion modeling each time a conformity
determination is made ensures that these new ``hotspots'' are
identified and addressed. A one-time effort to establish subregional
budgets would not.
EPA notes that the SIP does not require growth in non-mobile
sources to be considered in conducting dispersion modeling for the
purposes of conformity determinations. However, the RAQC factored in
the future year contribution of non-mobile source emissions (estimated
at 23.8 tons per day in 2015 in the February 8, 1995 Briggs memorandum,
or 29 tons per day in the April 23, 1997 RAQC memorandum) in defining
the region's 177 ton per day safety margin (and thus, in setting the 60
ton budget). More importantly, this aspect of the conformity modeling
methodology (that is, not considering growth in non-mobile sources each
time a conformity determination is made) is consistent with the way
conformity is applied in the other nonattainment areas throughout the
country which rely solely on their SIP emission budgets. Growth in non-
mobile sources must be considered when budgets are set through the SIP
process; however, there is no requirement for future conformity
determinations to continually re-evaluate the adequacy of these budgets
given growth in non-mobile sources.
[[Page 42090]]
In summary, EPA believes that the fact that only a small portion of
the SIP's safety margin has been allocated to the mobile source
emissions budget, along with the requirement for dispersion modeling
each time a conformity determination is conducted, are adequate to
ensure that the NAAQS are protected by the emissions budgets adopted by
the State and submitted to EPA. EPA is requesting further comment in
support of or opposed to this rationale for approving the budget
submittals.
III. Proposed Action
EPA is seeking additional information from interested parties on
two issues related to the Denver PM10 and NOX
mobile source emissions budget SIPs. EPA initially proposed approval of
the SIP revisions on October 3, 1996 (61 FR 51631).
As indicated elsewhere in this document, EPA will consider any
comments received by September 4, 1997 relating to the two issues
described above relating to the two SIPs.
IV. Executive Order 12866
The Office of Management and Budget (OMB) has exempted this
regulatory action from E.O. 12866 review.
V. Regulatory Flexibility
Under the Regulatory Flexibility Act, 5 U.S.C. 600 et seq., EPA
must prepare a regulatory flexibility analysis assessing the impact of
any proposed or final rule on small entities (5 U.S.C 603 and 604).
Alternatively, EPA may certify that the rule will not have a
significant economic impact on a substantial number of small entities.
Small entities include small businesses, small not-for-profit
enterprises, and government entities with jurisdiction over populations
of less than 50,000.
SIP approvals under sections 110 and subchapter I, part D of the
CAA do not create any new requirements but simply approve requirements
that the State is already imposing. Therefore, because this proposed
Federal SIP approval does not impose any new requirements, I certify
that it does not have a significant impact on any small entities
affected. Moreover, due to the nature of the Federal-State relationship
under the CAA, preparation of a flexibility analysis would constitute
Federal inquiry into the economic reasonableness of state action. The
CAA forbids EPA to base its actions concerning SIPs on such grounds.
Union Electric Co. v. U.S. E.P.A., 427 U.S. 246, 256-66 (1976); 42
U.S.C. 7410(a)(2).
VI. Unfunded Mandates
Under section 202, of the Unfunded Mandates Reform Act of 1995
(``Unfunded Mandates Act''), signed into law on March 22, 1995, EPA
must prepare a budgetary impact statement to accompany any proposed or
final rule that includes a Federal mandate that may result in estimated
costs to State, local, or tribal governments in the aggregate; or to
the private sector, of $100 million or more. Under section 205, EPA
must select the most cost-effective and least burdensome alternative
that achieves the objectives of the rule and is consistent with
statutory requirements. Section 203 requires EPA to establish a plan
for informing and advising any small governments that may be
significantly or uniquely impacted by the rule.
EPA has also determined that this proposed action does not include
a Federal mandate that may result in estimated costs of $100 million or
more to State, local, or tribal governments in the aggregate, or to the
private sector. This Federal action would approve pre-existing
requirements under State or local law, and would impose no new Federal
requirements. Accordingly, no additional costs to State, local, or
tribal governments, or to the private sector would result form this
action.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Hydrocarbons,
Intergovernmental relations, Nitrogen dioxide, Particulate matter,
Reporting and recordkeeping requirements, Sulfur dioxide, Volatile
organic compounds.
Authority: 42 U.S.C. 7401-7671q.
Dated: July 14, 1997.
Jack W. McGraw,
Acting Regional Administrator.
[FR Doc. 97-20582 Filed 8-4-97; 8:45 am]
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