[Federal Register Volume 59, Number 53 (Friday, March 18, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-6390]


[[Page Unknown]]

[Federal Register: March 18, 1994]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 52

[WY2-1-5111; FRL-4851-4]

 

Clean Air Act Proposed Approval and Promulgation of PM10 
Implementation Plan for the City of Sheridan, WY

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice of proposed rulemaking.

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SUMMARY: EPA proposes approval of the State Implementation Plan (SIP) 
submitted by the State of Wyoming to achieve attainment of the National 
Ambient Air Quality Standards (NAAQS) for particulate matter with an 
aerodynamic diameter less than or equal to a nominal 10 micrometers 
(PM10). The SIP was submitted by the State of Wyoming to satisfy 
certain Federal requirements for an approvable nonattainment area 
PM10 SIP for the City of Sheridan, Wyoming.

DATES: Comments on this proposed action must be received in writing by 
April 18, 1994.

ADDRESSES: Comments should be addressed to: Douglas M. Skie, Chief, Air 
Programs Branch, (8ART-AP), Environmental Protection Agency, Region 
VIII, 999 18th Street, suite 500, Denver, Colorado 80202-2466.
    Copies of the State's submittal and other information are available 
for inspection during normal business hours at the following locations: 
Environmental Protection Agency, Region VIII, Air Programs Branch, 999 
18th Street, 6th floor, South Tower, Denver, Colorado 80202-2466; and 
Air Quality Division, Department of Environmental Quality, Herschler 
Building, 4th floor, 122 West 25th Street, Cheyenne, Wyoming, 82002

FOR FURTHER INFORMATION CONTACT: Sara Summers, Environmental Protection 
Agency, Region VIII, Air Programs Branch, 999 18th Street, suite 500, 
Denver, Colorado, 80202-2466, (303) 293-0966.

SUPPLEMENTARY INFORMATION:

I. Background

    The Sheridan, Wyoming area was designated nonattainment for 
PM10 and classified as moderate under sections 107(d)(4)(B) and 
188(a) of the Act, upon enactment of the Clean Air Act Amendments of 
1990.\1\ See 56 FR 56694 (November 6, 1991); and 40 CFR 81.351 
(specifying PM10 nonattainment designation for the Sheridan area). 
The air quality planning requirements for moderate PM10 
nonattainment areas are set out in part D, subparts 1 and 4, of Title I 
of the Act.\2\
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    \1\The 1990 Amendments to the Clean Air Act made significant 
changes to the Act. See Public Law No. 101-549, 104 Stat. 2399. 
References herein are to the Clean Air Act, as amended (``the 
Act''). The Clean Air Act is codified, as amended, in the U.S. Code 
at 42 U.S.C. 7401, et seq.
    \2\Subpart 1 contains provisions applicable to nonattainment 
areas generally and Subpart 4 contains provisions specifically 
applicable to PM10 nonattainment areas. At times, Subpart 1 and 
Subpart 4 overlap or conflict. EPA has attempted to clarify the 
relationship among these provisions in the ``General Preamble'' and, 
as appropriate, in today's notice and supporting information.
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    The EPA has issued a ``General Preamble'' describing EPA's 
preliminary views on how EPA intends to review SIPs and SIP revisions 
submitted under Title I of the Act, including those State submittals 
containing moderate PM10 nonattainment area SIP requirements (see 
generally 57 FR 13498 (April 16, 1992) and 57 FR 18070 (April 28, 
1992)). Because EPA is describing its interpretations here only in 
broad terms, the reader should refer to the General Preamble for a more 
detailed discussion of the interpretations of Title I advanced in this 
proposal and the supporting rationale. In this action on the Wyoming 
moderate PM10 SIP for Sheridan, EPA is proposing to apply its 
interpretations taking into consideration the specific factual issues 
presented. Thus, EPA will consider any timely submitted comments before 
taking final action on this proposal.

    Those States containing initial moderate PM10 nonattainment 
areas (those areas designated nonattainment by operation of law under 
section 107(d)(4)(B) of the Act) were required to submit, among other 
things, the following provisions by November 15, 1991:

    1. Provisions to assure that reasonably available control measures 
(RACM) (including such reductions in emissions from existing sources in 
the area as may be obtained through the adoption, at a minimum, of 
reasonably available control technology (RACT)) shall be implemented no 
later than December 10, 1993;

    2. Either a demonstration (including air quality modeling) that the 
plan will provide for attainment as expeditiously as practicable but no 
later than December 31, 1994 or a demonstration that attainment by that 
date is impracticable;

    3. Quantitative milestones which are to be achieved every 3 years 
and which demonstrate reasonable further progress (RFP) toward 
attainment by December 31, 1994; and

    4. Provisions to assure that the control requirements applicable to 
major stationary sources of PM10 also apply to major stationary 
sources of PM10 precursors except where the Administrator 
determines that such sources do not contribute significantly to 
PM10 levels which exceed the NAAQS in the area. See sections 
172(c), 188, and 189 of the Act.

    Some provisions are due at a later date. States with initial 
moderate PM10 nonattainment areas were required to submit a permit 
program for the construction and operation of new and modified major 
stationary sources of PM10 by June 30, 1992 (see section 189(a)). 
Such States also must submit contingency measures by November 15, 1993 
which become effective without further action by the State or EPA, upon 
a determination by EPA that the area has failed to achieve RFP or to 
attain the PM10 NAAQS by the applicable statutory deadline (see 
section 172(c)(9) and 57 FR 13510-13512, 13543-13544).

II. This Action

    Section 110(k) of the Act sets out provisions governing EPA's 
review of SIP submittals (See 57 FR 13565-66). In this action, EPA is 
proposing to grant approval of the Sheridan, Wyoming, PM10 SIP 
because EPA believes it meets all applicable requirements of the Act 
that were due on November 15, 1991. (Also note that EPA is proposing to 
approve the contingency measures submitted for the area). The SIP 
includes the original document submitted to EPA on August 28, 1989, and 
eight subsequent submittals containing additional information. The 
dates of these submittals are: October 24, 1989, November 21, 1989, 
December 20, 1989, February 16, 1990, March 29, 1990, August 21, 1991, 
November 8, 1991, and March 3, 1992.

A. Analysis of State Submission

1. Procedural Background
    The Act requires States to observe certain procedural requirements 
in developing implementation plans for submission to EPA. Section 
110(a)(2) of the Act provides that each implementation plan submitted 
by a State must be adopted after reasonable notice and public 
hearing.\3\ Section 110(1) of the Act similarly provides that each 
revision to an implementation plan submitted by a State under the Act 
must be adopted by such State after reasonable notice and public 
hearing.
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    \3\Also Section 172(c)(7) of the Act requires that plan 
provisions for nonattainment areas meet the application provisions 
of section 110(a)(2).
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    The EPA also must determine whether a submittal is complete and 
therefore warrants further EPA review and action (see section 110(k)(1) 
and 57 FR 13565). The EPA's completeness criteria for SIP submittals 
are set out at 40 CFR part 51, appendix V (1992). The EPA attempts to 
make completeness determinations within 60 days of receiving a 
submission. However, a submittal is deemed complete by operation of law 
if a completeness determination is not made by EPA six months after 
receipt of the submission.
    The State of Wyoming held a public hearing on July 17, 1989, to 
entertain public comment on the implementation plan for the city of 
Sheridan. The State provided adequate notice of public hearing; the 
State requires 45 days notice. Following the public hearing, the plan 
was adopted by the State, signed by the Governor on July 17, 1989, and 
submitted to EPA on August 28, 1989, as a proposed attachment to the 
SIP. On March 8, 1990, EPA determined that the Sheridan SIP submittal 
was administratively and technically complete and proceeded to draft a 
Federal Register notice proposing to approve the SIP. However, upon 
enactment of the 1990 Amendments to the Act, EPA re-assessed the SIP 
for conformance with the Amendments and determined that additional 
information was required to comply with the new Amendments. Of the 
eight submittals made subsequent to the original document, four were 
received to address requirements of the new Amendments.
    Following submittal of the additional information required by the 
1990 Amendments, the SIP revision was reviewed by EPA to determine its 
completeness, in accordance with the completeness criteria set out at 
40 CFR part 51, appendix V (1992). The final submittal was received on 
March 5, 1992, and a letter dated April 14, 1992, was forwarded to the 
Governor indicating the completeness of the submittal and the next 
steps to be taken in the review process. As noted in this action, EPA 
proposes to approve the Wyoming PM10 SIP submittal for Sheridan, 
and invites public comment on the action.
2. Accurate Emissions Inventory
    Section 172(c)(3) of the Act requires that nonattainment plan 
provisions include a comprehensive, accurate, current inventory of 
actual emissions from all sources of relevant pollutants in the 
nonattainment area. The emissions inventory should also include a 
comprehensive, accurate, and current inventory of allowable emissions 
in the area. See, for example, section 110(a)(2)(K). Because the 
submission of such inventories is a necessary adjunct to an area's 
attainment demonstration (or demonstration that the area cannot 
practicably attain), the emissions inventories must be received with 
the attainment demonstration submission (see 57 FR 13539).
    Wyoming submitted an emissions inventory in 1989 for base year 
1986. This base year emissions inventory was subsequently revised and 
resubmitted in March 1992. The base year inventory (both versions) 
identified fugitive road dust as the primary cause of nonattainment 
contributing over 74.35 percent of the total emissions during the time 
that the violations were recorded. Additional contributing sources 
included natural gas, 0.01 percent; coal burning, 1.61 percent; wood 
burning, 14.80 percent; automobile emissions, 0.51 percent; Veterans 
Medical Center, 1.12 percent; Sheridan Forest Products, 0.75 percent; 
Wyoming Sawmill, 2.38 percent; and Burlington Northern, 4.38 percent.
    The EPA is proposing to approve the emissions inventory because it 
generally appears to be accurate and comprehensive, and provides a 
sufficient basis for determining the adequacy of the attainment 
demonstration for this area consistent with the requirements of 
sections 172(c)(3) and 110(a)(2)(K) of the Clean Air Act.\4\ For 
further details see the Technical Support Document (TSD).
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    \4\The EPA issued guidance on PM10 emissions inventories 
prior to the enactment of the Clean Air Act Amendments in the form 
of the 1987 PM10 SIP Development Guideline. We believe that 
this document provides a general basis for meeting the requirements 
of the revised Act.
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3. RACM (Including RACT)
    As noted, the initial moderate PM10 nonattainment areas must 
submit provisions to assure that RACM (including RACT) are implemented 
no later than December 10, 1993 (see sections 172(c)(1) and 
189(a)(1)(C)). The General Preamble contains a detailed discussion of 
EPA's interpretation of the RACM (including RACT) requirement (see 57 
FR 13539-13545 and 13560-13561). The EPA's interpretation of this 
requirement is set out here only in broad terms.
    The State should first identify available control measures 
evaluating them for their reasonableness in light of the feasibility of 
the controls and the attainment needs of the area. A State may reject 
an available control measure if the measure is technologically 
infeasible or the cost of the control is unreasonable.
    Three source categories were identified as contributing to the 
PM10 nonattainment problem in Sheridan. However, the SIP only 
relies on one control strategy to demonstrate attainment, the Sanding 
Winter Maintenance Program (SWMP), which was adopted on July 17, 1989. 
This plan, developed by the Sheridan Air Quality Committee, designates 
streets to be sanded during the winter season. Included are major 
streets, hills, school zones, and dangerous intersections. The plan 
specifies a material application rate which has been determined to 
provide adequate traction, and sanding material specifications which 
insures use of a clean and durable media. A comprehensive street 
sweeping and flushing program will remove material before dust problems 
occur. The reduction in PM10 emissions from fugitive road dust, 
between the base year inventory (911.84 tpy), and the attainment 
inventory (738.11 tpy) was calculated at 19% or 173.73 tpy. Credit for 
this reduction is given to the SWMP only. No credit was taken for two 
other control strategies outlined in the SIP, a voluntary woodburning 
curtailment program and dust control plans for three industrial 
sources. The reduction in ``total'' PM10 emissions between the 
base year inventory (1238.98 tpy) and attainment inventory (1137.39 
tpy) is 8% or 101.19 tpy. (The reason for the reduction in fugitive 
road dust emissions being greater than the reduction for total 
emissions between the base and attainment years, is that there was an 
increase in fugitive dust emissions over the same period of 87.35 tpy 
from two industrial sites. The overall result, however, is a net 
decrease in emissions). The voluntary woodburning curtailment plan and 
the industrial dust control plan were submitted with the SIP; EPA is 
taking no action on these two programs.
    A more detailed discussion of the individual source contributions 
and their associated control measures (including available control 
technology) can be found in the TSD. EPA has reviewed the State's 
documentation and concluded that it adequately justifies the control 
measures to be implemented. RACM does not require the implementation of 
all available control measures where an area demonstrates timely 
attainment and the implementation of additional available control 
measures would not expedite attainment. 57 FR 13543. The implementation 
of Wyoming's PM10 nonattainment plan control strategy will result 
in the attainment of the PM10 NAAQS by December 31, 1994.\5\ By 
this document, EPA is proposing to approve the Sheridan SIP, which 
includes the proposal to approve RACM (including RACT).
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    \5\The Act requires demonstration of attainment by December 31, 
1994. However, when this SIP was submitted, the Group I requirements 
called for attainment demonstration in 1989, with maintenance 
through 1994. Although the State did submit additional information 
in response to the Clean Air Act Amendments, the demonstration of 
attainment did not change. EPA believes, however, that since the 
Wyoming DEQ has shown maintenance of the NAAQS through 1994, the 
State has met the requirements to show attainment by December 31, 
1994.
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4. Demonstration
    As noted, the initial moderate PM10 nonattainment areas must 
submit a demonstration (including air quality modeling) showing that 
the plan will provide for attainment as expeditiously as practicable 
but no later than December 31, 1994 (see section 189(a)(1)(B) of the 
Act). Alternatively, the State must show that attainment by December 
31, 1994 is impracticable. In the General Preamble, EPA recommended 
that the attainment demonstrations for the initial moderate areas 
follow existing modeling guidelines for PM10 or, if appropriate, 
be developed consistent with the supplemental attainment demonstration 
policy issued for initial areas (see 57 FR 13539).
    Wyoming conducted an attainment demonstration using dispersion 
modeling in combination with receptor modeling for Sheridan. The State 
submitted the PM10 modeling protocol to EPA on July 12, 1988. The 
submittal included an explanation justifying the protocol, as follows: 
since the PM10 data collected during the 11 quarters prior to 
development of the initial modeling protocol were in compliance with 
the 24-hour PM10 standard, the Division did not find it necessary 
to model for the 24-hour standard.\5\ In fact, a violation of the 24-
hour PM10 NAAQS has not been monitored in this area.\6\ A single 
exceedence of 198 g/m3 was monitored on November 12, 1991. 
However, data results (Attachment 6 of the Appendix to the SIP) showed 
that, even with the ``gray zone'' allowance, the annual PM10 
standard had been violated. (The ``gray zone'' allowance refers to a 20 
percent overestimation of PM10 concentrations resulting from 
design flaws in the pre-1987 non-reference Sierra Anderson SA321A 
sampler; the problem was resolved when the sampler was modified and 
became the SA321B.) This explained the reasoning for the State's 
decision to focus on the annual standard, and for the annual PM10 
standard of 50 g/m3 becoming the controlling standard. EPA 
responded to the State on October 26, 1988 supporting this approach.
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    \5\The Act requires demonstration of attainment by December 31, 
1994. However, when this SIP was submitted, the Group I requirements 
called for attainment demonstration in 1989, with maintenance 
through 1994. Although the State did submit additional information 
in response to the Clean Air Act Amendments, the demonstration of 
attainment did not change. EPA believes, however, that since the 
Wyoming DEQ has shown maintenance of the NAAQS through 1994, the 
State has met the requirements to show attainment by December 31, 
1994.
    \6\EPA does not anticipate much change in population, based upon 
population data for Sheridan County submitted by DEQ on November 8, 
1991. The data were obtained from the January 1988 and July 1991 
reports from the Department of Administration and Information, 
Division of Economic Analysis, ``Wyoming Population and Employment 
Forecast Report.'' The population forecast including the years 1986 
(population = 26,449) through 1994 (population = 24,209), indicates 
that Sheridan County will not reach the 1986 population until the 
year 2004. After having examined the impact of growth on the 24-hour 
PM10 NAAQS, the Division is confident of maintenance of the 
standard.
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    The demonstration for the annual standard indicates that the NAAQS 
for PM10 will be attained by 1989 in Sheridan, Wyoming, and 
maintained.\7\ Maintenance of the standard was addressed in the 
Division's December 20, 1989 letter to EPA. The annual PM10 NAAQS 
standard will be attained when the expected annual arithmetic mean 
concentration is less than or equal to 50 g/m3. The original 
demonstration predicted that the annual design concentration in the 
attainment year of 1989 would be 48.8 g/m3 (Control Option #6, 
1989 SIP). The revised attainment demonstration submitted in March 
1990, predicted an annual concentration of 46 g/m3, 
demonstrating attainment of the annual PM10 NAAQS. The control 
strategy used to achieve the annual design concentration is summarized 
in the section titled ``RACM (including RACT).'' As discussed, because 
there have been no violations of the 24-hour PM10 standard in 
Sheridan, an attainment analysis of the 24-hour standard was not 
performed. EPA believes that the controls adopted to protect the annual 
standard are sufficient to maintain the 24-hour standard. For a more 
detailed description of the attainment demonstration and the control 
strategies used, see the TSD accompanying this document.
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    \7\See footnote 5.
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5. PM10 Precursors
    The control requirements which are applicable to major stationary 
sources of PM10 also apply to major stationary sources of 
PM10 precursors unless EPA determines such sources do not 
contribute significantly to PM10 levels in excess of the NAAQS in 
that area (see section 189(e) of the Act). The General Preamble 
contains guidance addressing how EPA intends to implement section 
189(e) (57 FR 13539-13540 and 13541-13542).
    An analysis of air quality and emissions data for the nonattainment 
area of Sheridan demonstrates that violations of the annual NAAQS are 
attributable chiefly to direct particulate matter emissions from re-
entrained road dust and woodburning. The emission inventory and CMB 
data for Sheridan did not reveal any significant sources of sulfates or 
nitrates in the area. Consequently, EPA is proposing to find that major 
sources of precursors of PM10 do not contribute significantly to 
PM10 levels in excess of the NAAQS. The consequence of this 
finding is to exclude any such sources from the applicability of 
PM10 nonattainment area control requirements. Further discussion 
of the analyses and supporting rationale for EPA's finding are 
contained in the TSD accompanying this notice. Note that while EPA is 
proposing to make a general finding for this area, today's proposed 
finding is based on the current character of the area including, for 
example, the existing mix of sources in the area. It is possible, 
therefore, that future growth could change the significance of 
precursors in the area. The EPA intends to issue future guidance 
addressing such potential changes in the significance of precursor 
emissions in an area.
6. Quantitative Milestones and Reasonable Further Progress (RFP)
    The PM10 nonattainment area plan revisions demonstrating 
attainment must contain quantitative milestones which are to be 
achieved every 3 years until the area is redesignated attainment and 
which demonstrate RFP, as defined in section 171(1), toward attainment 
by December 31, 1994 (see section 189(c) of the Act). Reasonable 
further progress is defined in section 171(1) as such annual 
incremental reductions in emissions of the relevant air pollutant as 
are required by Part D or may reasonably be required by the 
Administrator for the purpose of ensuring attainment of the applicable 
NAAQS by the applicable date.
    In considering the quantitive milestones and RFP provisions for 
this initial moderate area, EPA has reviewed the attainment 
demonstration for the area to determine the nature of any milestones 
necessary to ensure timely attainment and whether annual incremental 
reductions should be required in order to ensure attainment of the 
PM10 NAAQS by December 31, 1994 (see section 171(1) of the Act). 
The PM10 SIP for the Sheridan nonattainment area demonstrates 
attainment by December 31, 1994 satisfying the initial quantitive 
milestone requirement.\8\ EPA also proposes to find that at this time 
the SIP meets Reasonable Further Progress.
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    \8\The emissions reduction progress made prior to the attainment 
date of December 31, 1994 (only 46 days beyond the November 15, 1994 
milestone date) will satisfy the first milestone requirement (57 FR 
13539). The de minimis timing differential makes it administratively 
impractable to require separate milestone and attainment 
demonstrations.
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7. Enforceability Issues
    All measures and other elements in the SIP must be enforceable by 
the State and EPA (see sections 172(c)(6), 110(a)(2)(A) and 57 FR 
13556). The EPA criteria addressing the enforceability of SIPs and SIP 
revisions were stated in a September 23, 1987 memorandum (with 
attachments) from J. Craig Potter, Assistant Administrator for Air and 
Radiation, et al. (see 57 FR 13541). Nonattainment area plan provisions 
must contain a program that provides for enforcement of the control 
measures and other elements in the SIP (see section 110(a)(2)(C)). The 
credited control measure contained in the SIP is the SWMP, addressed 
above under the section headed ``RACM (Including RACT).'' This control 
measure applies to winter time street sanding and sweeping. The mayor 
of Sheridan approved and adopted the street sanding plan on February 
21, 1989. This signed document was submitted as part of the August 28, 
1989 SIP submittal. The program designates specific city limitations/
guidelines for the following parameters: sanding routes, application 
rates, sanding materials and street cleaning. The program, according to 
the State's Attorney General, is enforceable by the State if the local 
agency fails to implement the program. The authority is derived 
directly from state statute (W.S. 35-11-201, 701 and 901).
8. Contingency Measures
    As provided in section 172(c)(9) of the Act, all moderate 
nonattainment area SIP's that demonstrate attainment must include 
contingency measures. See generally 57 FR 13510-13512 and 13543-13544. 
These measures must be submitted by November 15, 1993 for the initial 
moderate nonattainment areas. Contingency measures should consist of 
other available measures that are not part of the areas's control 
strategy. These measures must take effect without further action by the 
State or EPA, upon a determination by EPA that the area has failed to 
make RFP or attain the PM10 NAAQS by the applicable statutory 
deadline. The Sheridan SIP's contingency measure is the use of a 
chemical de-icer in lieu of sand on certain roadways. The SIP provides 
that the contingency measure can take effect without further action by 
the State or EPA Administrator, should EPA determine that the Sheridan, 
Wyoming nonattainment area has failed to make RFP or to attain the 
PM10 standard by the statutory attainment date of December 31, 
1994. After review of the contingency measure, EPA is proposing to 
approve the Sheridan, Wyoming, contingency plan.

III. Implications of Today's Action

    The EPA is proposing to approve the plan revision originally 
submitted to EPA for the Sheridan nonattainment area on August 28, 1989 
along with the subsequent submittals mentioned earlier (including the 
contingency measure). The State of Wyoming has demonstrated that the 
Sheridan moderate PM10 nonattainment area attained the PM10 
NAAQS in 1989 and that it will continue to maintain the standard 
through 1994.
    As noted, additional submittals for the initial moderate PM10 
nonattainment areas, such as a new source review permit program meeting 
the requirements of sections 173 and 189 of the Act, were due after the 
November 15, 1991 SIP requirements addressed in this notice. The EPA 
will determine the adequacy of any such submittal as appropriate.

IV. Request for Public Comments

    The EPA is requesting comments on all aspects of today's proposal. 
As indicated at the outset of this notice, EPA will consider any 
comments received by April 18, 1994.

V. Executive Order (EO) 12866

    This action has been classified as a Table 2 action by the Regional 
Administrator under the procedures published in the Federal Register on 
January 19, 1989 (54 FR 2214-2225), as revised by an October 4, 1993 
memorandum from Michael H. Shapiro, Acting Assistant Administrator for 
Air and Radiation. A future notice will inform the general public of 
these tables. On January 6, 1989, the Office of Management and Budget 
(OMB) waived Table 2 and Table 3 SIP revisions (54 FR 222) from the 
requirements of section 3 of Executive order 12291 for 2 years. The EPA 
has submitted a request for a permanent waiver for Table 2 and Table 3 
SIP revisions. The OMB has agreed to continue the waiver until such 
time as it rules on EPA's request. This request continues in effect 
under Executive Order 12866 which superseded Executive Order 12291 on 
September 30, 1993.

VI. Applicability to Future SIP Decisions

    Nothing in this action should be construed as permitting or 
allowing or establishing a precedent for any future request for 
revision to any State Implementation Plan. Each request for revision to 
any State Implementation Plan shall be considered separately in light 
of specific technical, economic, and environmental factors and in 
relation to relevant statutory and regulatory requirements.

VII. Regulatory Flexibility

    Under the Regulatory Flexibility Act, 5 U.S.C. 600 et seq., EPA 
must prepare a regulatory flexibility analysis addressing 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 population of less than 
50,000.
    SIP approvals under section 110 and subchapter I, part D of the 
Clean Air Act do not create any new requirements, but simply approve 
requirements that the State is already imposing. Therefore, because the 
Federal SIP-approval does not impose any new requirements, I certify 
that it does not have a significant impact on small entities affected. 
Moreover, due to the nature of the federal-state relationship under the 
Act, preparation of a regulatory flexibility analysis would constitute 
federal inquiry into the economic reasonableness of state action. The 
Clean Air Act forbids EPA to base its action 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).

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, and Volatile 
organic compounds.

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

    Dated: March 2, 1994.
William P. Yellowtail,
Regional Administrator.
[FR Doc. 94-6390 Filed 3-17-94; 8:45 am]
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