[Federal Register Volume 61, Number 182 (Wednesday, September 18, 1996)]
[Proposed Rules]
[Pages 49087-49090]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-23822]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 52
[AZ-030-0006; FRL-5611-8]
Approval and Promulgation of Implementation Plans; Arizona--
Phoenix Nonattainment Area; Carbon Monoxide Emission Inventory
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed rule.
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SUMMARY: EPA is proposing to approve, as meeting the requirements of
sections 172(c)(3) and 187(a)(1) of the Clean Air Act (CAA) and EPA
guidance, the 1990 base year carbon monoxide (CO) emission inventory
for the Phoenix CO nonattainment area. This document also discusses
EPA's review of the 1995 projected year inventory for the Phoenix area.
DATES: Written comments on this proposal must be received by October
18, 1996.
ADDRESSES: Written comments should be sent to: Wienke Tax, A-2-1, U.S.
Environmental Protection Agency,
[[Page 49088]]
Region 9, 75 Hawthorne Street, San Francisco, California 94105.
The rulemaking docket for this document, Docket No. 96-AZ-003, may
be inspected and copied at the following location between 8 a.m. and
4:30 p.m. on weekdays. A reasonable fee may be charged for copying
parts of the docket. U.S. Environmental Protection Agency, Region 9,
Air and Toxics Division, Mobile Sources Section, A-2-1, 75 Hawthorne
Street, San Francisco, California 94105.
FOR FURTHER INFORMATION CONTACT: Wienke Tax, Mobile Sources Section,
Air and Toxics Division, U.S. Environmental Protection Agency, Region
9, 75 Hawthorne Street, San Francisco, California 94105, (415) 744-
1223.
SUPPLEMENTARY INFORMATION:
I. CAA Requirements and EPA Guidance for Emission Inventories
Sections 172(c)(3) and 187(a)(1) of the CAA require that a
comprehensive, accurate, and current base year inventory of actual
emissions be submitted to EPA as a state implementation plan (SIP)
revision for each area designated as nonattainment and classified
moderate or serious for carbon monoxide.1 EPA has provided
guidance to States for developing these CO inventories, most recently
in Emission Inventory Requirements for Carbon Monoxide State
Implementation Plans, (EPA-450/4-91-011) March, 1991) (``Emission
Inventory Requirements''). While not an explicit requirement of the
CAA, projected inventories are closely related to the base year
inventory, and it is reasonable to review them in conjunction with the
base year inventory.
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\1\ At the time of the SIP submittals that are the subject of
today's notice, Phoenix was classified as moderate and, because its
design value is under 12.7 ppm, was considered a low moderate area.
EPA has recently found that the Phoenix area failed to attain the CO
NAAQS by the statutory deadline. See 61 FR 39343 (July 29, 1996) As
a consequence of this finding, the area has been reclassified to
``serious'' under section 186(b)(2). As a result, the area is now
subject to the section 187(b) requirements for serious CO areas.
These requirements include those applicable to CO areas with design
values between 12.7 ppm and 16.4 ppm (high moderate areas) in
section 187(a). For the purpose of today's action, however, the
relevant CAA requirements are those that apply to low moderate CO
nonattainment areas.
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A technically-sound emissions inventory is important for a number
of reasons. First, it is used to identify pollutant sources for new or
additional controls and so provides a basis for the control strategy.
Second, the inventory provides a means of assessing progress in
achieving reductions from existing controls. Finally, both current and
projected inventories are used as inputs to air quality modeling to
demonstrate attainment of the national ambient air quality standards
(NAAQS).
The Clean Air Act requires that emissions inventories be
comprehensive, accurate, and current. To be comprehensive, the
inventory must include all stationary point and area sources, non-road
mobile sources, and on-road mobile sources. To be accurate, the
inventory must be based on data representative of sources within the
nonattainment area. To be current, the inventory must represent 1990
(the year of the CAA enactment) or later.
A. Requirements for Base Year Inventories
The base year inventory is the primary inventory from which all
other CO inventories are derived. The base year inventory is defined in
the CAA as a ``current inventory'' which EPA interprets to mean 1990.
See ``General Preamble for the Implementation of Title I of the Clean
Air Act Amendments of 1990'' 57 FR 13498, 13530 (April 16, 1992).
Annual emission inventory estimates are adjusted to represent the CO
season weekday inventory (the ``planning inventory''). EPA recommends a
three month peak CO season as the basis for the planning inventory
estimates. See Emission Inventory Requirements, page 11.
Stationary sources are grouped into point and area sources. Point
sources are any stationary source emitting more than 100 tons per year
of CO. Area sources generally include small stationary sources (e.g.,
stationary internal combustion engines) and ubiquitous emissions not
associated with a permit (e.g., fireplaces). Mobile source estimates
are divided into on-road and non-road categories. Emissions inventories
for on-road mobile sources (e.g., automobiles, motorcycles, buses, and
trucks) are generally developed using the latest version of MOBILE,
EPA's mobile source emission factor model. The non-road mobile source
inventory includes emissions from categories ranging from lawn mowers
to marine vessels.
In documenting its on-road mobile source inventory, states must
report on how on-road vehicle emission factors and vehicle miles
travelled (VMT) estimates were determined. The state must fully
document how the most recent MOBILE model (MOBILE5a) was used to
estimate emission factors for the vehicle fleet. For VMT, the state
should describe the methodology employed to generate VMT data and the
key assumptions and inputs to the process. Finally, the state must
describe how the VMT data were combined with the emission factors to
produce mobile source emissions estimates. See Emission Inventory
Requirements, page 54.
In its emissions inventory submittal, a state is also required to
describe the implementation of the state's emission inventory quality
assurance (Q/A) program and the results achieved by that program. For
all source category types, the Q/A discussion must address the
completeness of the inventory, reasonableness of the emissions
estimates, and relative accuracy of the data. See Emission Inventory
Requirements, page 55.
A detailed discussion of EPA's emission inventory requirements can
be found in the Technical Support Document (TSD) for this rulemaking as
well as in the cited guidance documents. The TSD and all cited
documents can be requested from the contact person listed at the
beginning of this notice.
B. Guidance on Projected Emissions Inventories
Future year inventories are needed for projecting and modeling
attainment. Future year inventories are developed using base year
inventory estimates adjusted using growth and control factors. EPA's
guidance for developing projected year inventories is found in
Procedures for Preparing Emissions Projections, (EPA-450/4-91-019)
July, 1991.
Inventory projections attempt to project how the combination of
future emission controls and changes in source activity will influence
future emission rates. Growth factors are developed using socioeconomic
forecasts (i.e., population, housing, employment, and motor vehicle
activity) and Standard Industrial Classification data. Growth rates for
motor vehicles consider projected changes in vehicle miles traveled,
trips, and vehicles in use. Control factors are used to adjust future
year inventory estimates to account for reductions from adopted and
scheduled measures. All growth and control factors and their derivation
should be thoroughly documented.
All emissions projected for future years should be based on the
same inventory methodologies and computational principles as the base
year emissions. For example, if a travel demand model is used for
estimating travel in the base year, the same model should be applied to
estimate travel demand for projected years. Using the same methodology
ensures consistency in format and content between base year
[[Page 49089]]
and projection year emissions estimates and prevents possible spurious
inventory differences due to changes in methodology.
For further information on requirements for emission inventory
projections, see the TSD.
II. The Maricopa CO Emissions Inventory Submittal
The Arizona Department of Environmental Quality (ADEQ) initially
submitted the 1990 base year (annual and average daily emissions) as
well as projected 1995 and 2005 CO inventories for the entire Phoenix
nonattainment area on November 15, 1993 as part of the Maricopa
Association of Governments (MAG) 1993 Carbon Monoxide Plan for the
Maricopa County Area (CO Plan). On April 4, 1994, ADEQ submitted
updated and improved inventories as part of MAG's 1993 Carbon Monoxide
Plan for the Maricopa County Area--Addendum (Addendum).2 These
revised inventories reflected adjustments to growth factors and the
impact of measures in Arizona House Bill 2001. Both submittals became
complete by operation of law under CAA section 110(k)(1)(B) on May 15,
1994 and October 8, 1994, respectively.
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\2\ On August 9, 1993, EPA issued a SIP call under section
110(k)(5) of the CAA that required Arizona to submit a plan to EPA
that demonstrated attainment of the CO NAAQS in the Phoenix area by
December 31, 1995. As an area with a design value under 12.7 ppm,
the State would not otherwise have been required to submit an
attainment plan for the Phoenix area. See section 187(a). CAA
section 187(a)(1) requires the submittal of a comprehensive,
accurate, current inventory of actual emission for all CO
nonattainment areas whether or not they have a separate requirement
to submit an attainment demonstration.
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The Maricopa County Division of Air Pollution Control (MCAPC)
prepared the stationary (point and area) and non-road mobile source
portions of the inventories, while MAG Transportation and Planning
Office prepared the transportation data and the on-road mobile sources
emissions estimates. Quality assurance/quality control procedures were
performed by MCAPC and ADEQ.
A. Baseline (1990) Emissions Inventory
Because CO violations in Phoenix occur primarily from November
through January, November and December of 1989 and January of 1990 were
chosen as the basis for the planning inventory, as per EPA guidance.
See Emission Inventory Requirements, page 11. The emissions data
section of the inventories contains a summary of 1990 emissions data by
source type (point, area and mobile), for both average daily emissions
and annual emissions. See ``1990 Base Year Carbon Monoxide Emission
Inventory for the Maricopa County, Arizona Nonattainment Area,'' MCAPC,
August 1993 (located in Appendix B, Exhibit 1 of the CO Plan) (``EI
Documentation'') at page 1-6. Inventory development procedures are
discussed separately for point, area, non-road mobile and on-road
mobile sources in the EI Documentation.
MCAPC was the lead agency responsible for developing the point
source inventory. All methods for collecting point source data and
estimating emissions were documented, and detailed emissions
information was provided (see Chapter 2 of the EI Documentation) and
entered into EPA's Aerometric Information Retrieval System (AIRS).
Point source base year emissions totalled 1299 tons CO per year (<1% of="" the="" inventory,="" without="" accounting="" for="" on-road="" mobile="" source="" emissions)="" and="" 8.7="" tons="" co="" per="" average="" co="" season="" day=""><1% of="" the="" inventory).="" see="" ei="" documentation,="" page="" 1-6.="" mcapc="" evaluated="" all="" area="" sources="" included="" in="" epa's="" guidance="" document="">3 for their significance in Maricopa County except
residential incineration; open burning at industrial, commercial/
institutional, and residential sources; and charcoal grilling. The
first two categories are prohibited by law; charcoal grilling was not
addressed because suitable emission factors and activity data were not
available and because emissions contributions from this category were
judged to be negligible. See EI Documentation, page 3-1. A rule
effectiveness (RE) factor of 80 percent was applied to source
categories subject to regulation, as recommended by EPA for all
categories except woodburning. Rule penetration was estimated per EPA
guidance. See EI Documentation, page 3-1. While EPA recommends a 50
percent RE factor for woodburning, woodburning is only a small fraction
of the Maricopa CO inventory, so the assumption of a 80 percent RE
factor is insignificant in this instance. Total CO base year emissions
from area sources were 13,337.8 tons per year in 1990 (7.3% of
inventory, without accounting for on-road mobile source emissions), and
87.65 tons per average CO season day (7.7% of inventory). See EI
Documentation, page 1-6.
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\3\ Procedures for the Preparation of Emission Inventories for
Precursors of Ozone, Volume I, (EPA 450/4-88-021) December 1988.
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Non-road source categories inventoried in the CO Plan include
aircraft, locomotives, and non-road equipment sources. EPA's Office of
Mobile Sources prepared the emissions estimates for the non-road
equipment source categories. See Chapter 3 of the EI Documentation.
These categories included recreational vehicles, construction
equipment, industrial/commercial equipment, lawn and garden equipment,
and farm equipment. Emissions calculations were presented for aircraft
(commercial, military, general aviation) and locomotives, per EPA
guidance. See Procedures for Emission Inventory Preparation, Volume IV:
Mobile Sources (EPA-450/4-81-026d Revised) 1992. (Procedures, Mobile
Sources). Non-road CO emissions for 1990 totalled 167,303 tons (91.9%
of inventory, without accounting for on-road mobile sources), while
average daily CO season emissions totalled 238 tpd (20.8% of
inventory). See EI Documentation, page 1-6.
On-road mobile sources were inventoried per EPA guidance found in
Procedures, Mobile Sources. MAGTPO prepared the 1990 VMT estimates,
using the Highway Performance Monitoring System (HPMS) data for 1990
collected by the Arizona Department of Transportation (ADOT). The HPMS
data were supplemented by traffic count data and estimates of total
street mileage in the CO nonattainment area from MAGTPO. The CO Plan
contains an extensive discussion of the conversions performed on the
HPMS data to produce inventory-compatible VMT estimates. See EI
Documentation, Chapter 5.
The version of the MOBILE model used to develop on-road mobile
emission factors for the November 1993 and March 1994 submittals was
MOBILE5. The CO Plan fully documents the inputs to the model. See EI
Documentation, Chapter 5. On-road mobile source emission factors and
emissions are presented by vehicle class and roadway type. Total CO
baseline emissions from on-road mobile sources totalled 807.7 tons per
CO season day (70.7% of inventory). See EI Documentation, Chapter 5.
Chapter 6 of the EI Documentation contains a discussion of quality
assurance and quality control (QA/QC) procedures used by the various
agencies in developing the inventory. The QA/QC procedures included
checks for accuracy, reasonableness, and completeness, including
reviews by independent parties. More detailed procedures included
reviewing the descriptive information contained in each section to
assure completeness, clarity, and correctness; examining formulae,
calculations and conversions to assure freedom from errors and
inconsistencies; evaluating data quality to assure the worth and
usefulness of
[[Page 49090]]
the inventory; and assessing, where possible, the significance of the
calculated quantities to assure accuracy and justifiable precision.
EPA has concluded that the baseyear emission inventories in the MAG
CO Plan and Addendum conform to EPA's guidance and the CAA requirements
for CO inventories and are therefore proposed for approval.
B. Projected Emissions Inventory
The CO Plan contained a 1995 attainment year projected emission
inventory. See Addendum, Exhibit 3. This inventory was prepared by MAG
using the methodologies in EPA's guidance.4 The Addendum modified
the projected inventory in several respects. First, in response to
comments received during the public hearing on the Plan, MCAPC revised
the growth factors used to project 1990 emissions to 1995. Secondly, in
November 1993, the Arizona legislature passed H.B. 2001 which included
additional commitments for measures designed to bring the region into
attainment for CO. A few minor additional adjustments to modeling
inventories were also made and the effects of the existing oxygenated
fuels program on non-road emissions was included. Overall, these
changes resulted in slight decreases (1-4 percent) in projected CO
emissions for future years.
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\4\ While the CO Plan and Addendum include a year 2005 CO
projected emission inventory, EPA did not review that inventory.
Neither the Clean Air Act nor EPA guidance requires states to
demonstrate maintenance after the applicable attainment date until
an area requests redesignation to attainment under section 175A(a).
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EPA has concluded from its review of the 1995 projected year
emission inventory in the MAG CO Plan and Addendum that it conformed
EPA's guidance for CO projected inventories.
III. Summary of EPA Actions
Because EPA has concluded that it conforms to EPA guidance for base
year emission inventories, EPA is proposing to approve, pursuant to
sections 172(c)(3) and 187(a)(1) of CAA, the 1990 CO base year
inventory for the Maricopa CO nonattainment area. EPA is also finding
that the 1995 projected year inventory conforms to EPA guidance.
Nothing in this proposed action should be construed as permitting
or allowing or establishing a precedent for any future request for
revision to any SIP. Each request for a revision to the SIP shall be
considered separately in light of specific technical, economic and
environmental factors and in relation to relevant statutory and
regulatory requirements.
IV. Administrative Requirements
A. Executive Order 12866
This action has been classified as a Table 3 action for signature
by the Regional Administrator under the procedures published in the
Federal Register on January 19, 1989 (54 FR 2214-2225), as revised by a
July 10, 1995 memorandum from Mary Nichols, Assistant Administrator for
Air and Radiation. The Office of Management and Budget (OMB) has
exempted this regulatory action from E.O. 12866 review.
B. Regulatory Flexibility Act
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 impact on a substantial number of small entities. Small
entities include small business, small not-for-profit enterprises and
government entities with jurisdiction over populations of less than
50,000.
SIP approvals under subchapter I, part D of the Clean Air Act, do
not create any new requirements, but simply approve requirements that a
state is already imposing. The action proposed today is simply the
approval of technical information required to be developed under the
CAA and imposes no state or federal requirements on any entity.
Therefore, the Administrator certifies 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 Clean Air Act forbids EPA
to base its actions concerning SIPs on such grounds. Union Electric Co.
v. U.S.E.P.A., 427 U.S. 246, 256-66 (S.Ct. 1976); 42 U.S.C. 7410(a)(2).
C. 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 that 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 this rule.
EPA has determined that the approval action proposed does not
include a federal mandate that may result in estimate costs of $100
million or more to either state, local, or tribal governments in the
aggregate, or to the private sector. This Federal action approves pre-
existing requirements under state or local law, imposes no new federal
requirements. Accordingly, no additional costs to State, local or
tribal governments, or to the private sector, results from this action.
Accordingly, no costs to State, local, or tribal governments, or to the
private sector, result from this action.
List of Subjects in 40 CFR Part 52
Environmental protection, Air pollution control, Carbon monoxide,
Intergovernmental relations.
Authority: 42 U.S.C. 7401-7671q.
Dated: September 9, 1996.
Felicia Marcus,
Regional Administrator.
[FR Doc. 96-23822 Filed 9-17-96; 8:45 am]
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