& EPA
         United Stales
         Environmental Protection
           Office of Air Quality
           Planning and Standards
           Research Triangle Park, NC 27711
EPA-452/R-92-003
Julv 1992
         Air
TECHNICAL SUPPORT DOCUMENT
TO AID STATES WITH THE
DEVELOPMENT OF CARBON
MONOXIDE STATE
IMPLEMENTATION PLANS

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h-
o
O
TECHNICAL SUPPORT DOCUMENT TO
AID STATES WITH THE DEVELOPMENT
   OF CARBON MONOXIDE STATE
      IMPLEMENTATION PLANS
       Ozone/Carbon Monoxide Programs Branch
               U S Environmental Protection Agency
               Region 5, Library (PL-12J)
               77 West Jackson Boulevard, 12th Hoor
               Chicago, IL 60604-3590


       U. S. Environmental Protection Agency
     Office of Air Quality Planning and Standards
        Research Triangle Park, NC 27711

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                                    CONTENTS


                                                                               Page

I   EXECUTIVE SUMMARY  	    1

II   PROVISIONS OF THE CLEAN AIR ACT OF 1990 FOR
    CO NONATTAINMENT AREAS	    3
    A.  INTRODUCTION 	    3
    B.  REQUIREMENTS FOR MODERATE CO NONATTAINMENT AREAS LESS THAN
        OR EQUAL TO 12.7 PPM	    3
        1.   Emission Inventories	    3
        2.   Inspection and Maintenance Corrections	    3
        3.   Periodic Inventory  	    4
        4.   Attainment Demonstration  	    4
        5.   Use of Oxygenated Fuels	    4
        6.   New Source Review	    5
        7.   Contingency Measures	    5
    C.  REQUIREMENTS FOR MODERATE CO NONATTAINMENT AREAS GREATER
        THAN 12.7 PPM	    7
        1.   Vehicle Miles Traveled Forecasts	    7
        2.   Contingency Measures	    7
        3.   Enhanced Inspection and Maintenance	    7
        4.   Attainment Demonstration  	    7
        5.   New Source Review	    7
    D.  REQUIREMENTS FOR SERIOUS CO NONATTAINMENT AREAS	    8
        1.   Major Stationary Source Definition	    8
        2.   Transportation Control Measures  	    8
        3.   Clean Fuel Vehicle Fleet Program  	    8
        4.   Milestone and Attainment Failures (Economic Incentive Programs)	    8
    E.  REQUIREMENTS FOR NOT-CLASSIFIED CO NONATTAINMENT AREAS	    9
        1.   Not-Classified Areas	    9
        2.   Section 172 (b-c) Requirements for Not-Classified Areas  	    9
        3.   Attainment Dates for Not-Classified Areas 	   10

III ADDITIONAL CO NONATTAINMENT AREA REQUIREMENTS OR ISSUES	   11
    A.  MULTISTATE CO NONATTAINMENT AREAS  	   11
        1.   MultiState Coordination	   11
        2.   Joint Work Plan	   11
        3.   Attainment Demonstration  	   11
    B.  RULE EFFECTIVENESS  	   12
    C.  AREAS WITH SIGNIFICANT STATIONARY SOURCES OF CO	   12
    D.  AREAS WITH LOW MOBILE SOURCE CO EMISSIONS	   13
    E.  REDESIGNATION/RECLASSIFICATION	   13
        1.   Moderate Areas That Do Not Attain ("Bump up")  	   13
        2.   Section 179B International Border Areas  	   14
        3.   Redesignation from Nonattainment to Attainment	   14
        4.   Redesignation from Attainment to Nonattainment	   14
    F.  EXTENSIONS OF ATTAINMENT DATES	   15
                                         in

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    G.  MAINTENANCE PLANS  	   15

IV  SIP-RELATED ISSUES	.'	   17
    A.  INTRODUCTION  	   17
    B.  INVENTORY DEVELOPMENT AND UPDATING	   17
        1.   Base Year Inventory	   17
        2.   Periodic Inventory  	   18
        3.   Modeling Inventory  	   18
        4.   Registration Distributions and MOBILE4.1 Projections  	   19
        5.   Other Inventory Issues	   19
        6.   Additional References for Inventory Development Updating  	   20
    C.  CONTROLS FOR STATIONARY SOURCES	   20
        1.   Industrial CO Controls   	   20
        2.   Residential Wood Burning 	   22
    D.  CONTROLS FOR MOBILE SOURCES	   23
        1.   Inspection and Maintenance  	   23
        2.   Oxygenated Fuels	   23
        3.   Transportation Control  Measures  	   24
        4.   New Light-Duty Truck Emissions Standards	   25
        5.   Clean Fuel Vehicle Fleet Programs	   25
        6.   Cold Temperature Starts  	   26
        7.   California Low Emission Vehicle Program	   26
        8.   Federal Tier II Standards	   26
    E.  OTHER MOBILE SOURCE CONTROL ISSUES	   26
        1.   Nonroad Engines and Vehicles   	   27
        2.   Locomotives	   27
        3.   Aircraft	   27
    F.  MODELING ASSESSMENTS	   28
        1.   Intersection	   28
        2.   Areawide Analyses	   28
    G.  VMT CONSIDERATIONS	   29
        1.   General Information	   29
        2.   Reporting	   29
        3.   Tracking  	   30
        4.   Forecasting	   30
        5.   Contingency Measures	   31
    H.  SERIOUS AREA ISSUES  	   32
        1.   Milestone Demonstration	   32
        2.   Transportation Control  Measures  	   32
        3.   Clean Fuel Vehicle Fleet Programs	   33
    I.   CONTINGENCY MEASURES 	   34
        1.   Implementation of Measures	   34
        2.   Interaction with VMT Offsets 	   34
        3.   Margin of Error	   35
    J.   LONG-TERM CONTROL MEASURES AND STRATEGIES 	   35

V   THE RELATIONSHIP OF THE  CO SIP WITH OTHER CAAA PROVISIONS	   37
    A.  TITLE II: MOTOR VEHICLES  	   37
        1.   On-board Diagnostics  	   37
        2.   Oxygenated Fuels	   37
                                          IV

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        3.   Clean Fuel Vehicle Fleets	  38
    B.   NEW SOURCE REVIEW   	  38
    C.   ECONOMIC INCENTIVES PROGRAMS   	  39
    D.   CONFORMITY	  39
        1.   Interim Period	  40
        2.   Emission Budgets for Transportation Conformity 	  40
        3.   Maintenance Plans	  41
        4.   Failure to Meet a Milestone/Attainment	  41

APPENDIX A:  CHECKLIST	A-l

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                            ABBREVIATIONS AND ACRONYMS
Act          Clean Air Act
CAAA       Clean Air Act Amendments of 1990
CO          carbon monoxide
CMSA       Consolidated Metropolitan Statistical Area
DOT         U.S. Department of Transportation
EIP          Economic Incentive Program
FHWA       Federal Highway Administration
FID          Flame lonization Detection
FTA         Federal Transit Administration
g/mi         grams per mile
GVWR       gross vehicle weight rating
HC          hydrocarbon
HPMS       Highway Performance Monitoring System
I/M          Inspection and Maintenance
LAER       Lowest Achievable Emission Rate
Ibs           pounds
LDT         light-duty truck
LDV         light-duty vehicle
LEV         low emission vehicle
LVW         loaded vehicle weight
MACT       maximum achievable control technology
mph          miles per hour
MSA         Metropolitan Statistical Area
NAAQS      National Ambient Air Quality Standard
NOX          nitrogen oxide
NSPS        New Source Performance Standard
NSR         New Source Review
QMS         Office of Mobile Sources
ppm          parts per million
RACT       reasonably available control technology
RACM       reasonably available control measures
RFP          Reasonable  Further Progress
RIA          Regulatory Impact Analysis
SIP          State Implementation Plan
TCM         transportation control measures
TW          test weight
tpy          tons per year
VMT         vehicle miles traveled
VOC         volatile organic compounds
UAM        Urban Airshed Model
                                            VI

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                                          SECTION I
                                   EXECUTIVE SUMMARY

    Section 104 of the Clean Air Act (Act) Amendments of 1990 (CAAA) amends Part D of Title I
of the Act by adding additional provisions for carbon monoxide (CO) nonattainment areas (Subpart
3). The two additional sections to Subpart 3 are sections 186 and 187, which pertain to the
classification of CO nonattainment areas and to the submission requirements of the State
implementation plans (SIP's) for these areas, respectively.  This document provides the States with
guidance in developing their SIP for the moderate and serious CO nonattainment areas under their
administration.  This guidance document should be used  in conjunction with discussions between the
States and the Environmental Protection Agency (EPA) Regional Office staffs and with other relevant
EPA offices, as well as with the appropriate referenced EPA materials.

    The purpose of this guidance is to provide technical  specifications to support the policy presented
in the "General Preamble: Implementation of Title I CAAA of 1990" [57 FR  13948] (General
Preamble).  The  General Preamble  is the appropriate guidance citation to be incorporated in the
development of SIP's.

    The major elements and requirements of sections 186 and 187 are presented in this document,
with appropriate references to other EPA guidance and technical  materials.  The key elements of the
requirements for the CO SIP materials are:

         Existing and newly designated CO nonattainment areas  are classified into three categories
         with specific and additive requirements as the designations become more severe.

         The CAAA establishes several new classifications for air quality control regions for CO,
         including not-classified areas,  multistate nonattainment areas,  and areas with significant
         stationary sources of CO, with separate requirements for these areas.

         The deadlines for attainment demonstration and achievement are accompanied by bump-up
         provisions which place increased requirements on these nonattainment areas.

         The development and maintenance of emission  inventories and other forecasting and
         tracking mechanisms, such as  those for vehicle  miles traveled (VMT), will play increasingly
         important roles in the SIP process.

         The role of inspection/maintenance (I/M)  and clean fuel fleet programs, transportation
         control measures, and  the use of oxygenated fuels will play increasingly important and
         prominent roles in the SIP's for CO nonattainment areas, illustrating the heavy contribution
         of this pollutant by mobile sources.

         Long-term control strategies and measures, economic incentive programs, and contingency
         measures will play  increasingly important and prominent roles in the SIP's for certain CO
         nonattainment areas.

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         States are required to continue control programs for CO sources for at least 10 years after
         the redesignation of an area to attainment status.  These requirements place increased
         demands on the State agencies to prepare and implement programs and strategies with
         longer time horizons.

         Modeling analyses and increased monitoring networks will be necessary to show continuing
         maintenance or attainment of the National Ambient Air Quality Standards (NAAQS.)

         Because several other provisions of the CAAA affect CO nonattainment areas, States must
         be aware of the interaction with Title II,  and new source review, economic incentive
         programs, and conformity requirements.

         A checklist has been prepared to assist the State agencies in preparing the SIP's for CO.

    Section II of this document outlines the provisions of sections 186 and  187 of the CAAA.
Section III presents information on general issues or requirements relevant to the preparation of the
CO SIP submittals. Section IV discusses SIP-related issues which are unique to the SIP submittals for
CO nonattainment areas.  Section V discusses the relationship between the requirements of the SIP
submittals for CO nonattainment areas and other CAAA provisions. Appendix A presents a checklist
that has been developed to provide a step-by-step approach to the  preparation of the CO SIP
submittal. This checklist should be helpful in ensuring that the SIP submittal is complete.

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                                       SECTION II
            PROVISIONS OF THE CLEAN AIR ACT OF 1990 FOR CO
                              NONATTAINMENT AREAS
A.  INTRODUCTION

    Title I of the CAAA establishes revised requirements for areas that have not attained the NAAQS
for CO. These requirements include attainment deadlines, area classifications, and the required
provisions of the SIP's for these nonattainment areas.  The two pertinent sections of the CAAA are
section 186 and section 187.

    Section 186 establishes nonattainment classifications, moderate (design values between 9.1 and
16.4 ppm), serious (design values greater than  16.4 ppm), and  "not-classified," for nonattainment
areas that do not meet the classification scheme, and sets deadlines for the attainment of the primary
CO NAAQS within these areas.  Section 187,  which establishes the SIP requirements for the
nonattainment areas, further differentiates between moderate areas with design values less than or
equal to 12.7 ppm and those with design values above 12.7 ppm.  Serious nonattainment areas must
meet all the requirements of moderate  areas plus additional  requirements.  The requirements of
section 187 include SIP provisions for  regular  emission inventories, forecasts and verification  of
VMT, contingency measures, vehicle I/M programs, attainment demonstrations, transportation control
measures (TCM's), and use of special  oxygenated gasoline.

    One of the main goals of the CAAA was to overhaul previous Act provisions regarding planning
for NAAQS attainment. These Amendments modify the existing law and set standards and
requirements to address previous failure to  attain CO standards.  Title I of the CAAA  ("Provisions for
Attainment and Maintenance of NAAQS") amends and supplements Title I of the Act ("Air Pollution
Prevention and Control").  The revised general requirements for all SIP's, regardless of the
attainment demonstration required, appear early in Title I of the CAAA and should be reviewed, but
will not be covered in this document.

B.  REQUIREMENTS FOR MODERATE CO NONATTAINMENT AREAS LESS THAN OR
    EQUAL TO 12.7 PPM

    /.   Emission Inventories

    Section 187(a)(l) requires moderate CO areas to submit comprehensive emissions inventories
from all sources by November 15, 1992, as described in section 172(c)(3).  Draft 1990 base year
inventories addressing actual CO emissions during the peak  CO season for the area should have been
submitted by May 1, 1992, as specified in an EPA guidance document ("Emission Inventory
Requirements for Carbon Monoxide State Implementation Plans," EPA, OAQPS, EPA-450/4-91-011,
March 1991).

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    2.   Inspection and Maintenance Corrections

    Section 187(a)(4) requires States with-moderate CO nonattainment areas that already include I/M
programs, or that were required by the pre-1990 Act to include I/M programs in their SIP's, to
submit to EPA immediately upon enactment any revisions necessary to provide for a program no less
stringent than that required prior to enactment or committed to in the SIP in effect at the time of
enactment, whichever is more stringent. Requirements for I/M programs are contained in section
182(a)(2)(B).  In short, the moderate areas must maintain existing I/M programs and  make corrections
to those programs to meet existing I/M policy; when updated policy is published, these areas must
submit revisions to address any revised guidance. (See "Notice of Proposed Rulemaking on
Requirements for Preparation, Adoption, and Submittal of Implementation Plans:
Inspection/Maintenance Program Requirements," expected in Federal Register, 1992.)

    Section 202(m) requires the Administrator to promulgate regulations requiring manufacturers to
install diagnostic systems on all new light-duty vehicles and light-duty trucks. Section 202(m)(3)
requires States with I/M programs to amend their SIP's within 2 years of EPA requiring them to do
so by including inspection of on-board diagnostics systems.  (See "Notice of Proposed Rulemaking on
On-Board Diagnostics" [56 FR 48272]. The final  regulation is expected in  the summer of 1992.)

    3.   Periodic Inventory

    Section 187(a)(5) requires States with moderate CO nonattainment areas to submit periodic
inventories beginning on September 30, 1995, and then every 3 years  thereafter until redesignated to
attainment.  The periodic inventory must meet the same requirements  as the base year inventory. By
meeting these specific periodic inventory requirements, States will also satisfy the general periodic
inventory requirements of section 172(c)(3).  (See  "Guidance for Initiating Ozone/CO SIP Emission
Inventories Pursuant to the 1990 Clean Air Act Amendments," EPA, February 1991.  See also
General Preamble [57 FR 13948, April 16, 1992] Section III.A.2.(a).)

    4.   Attainment Demonstration

    No attainment demonstration is required for moderate CO areas with CO design values of 12.7
ppm or less.

    5.   Use of Oxygenated Fuels

    Section 211(m) requires any State containing all or part of a CO nonattainment area with a design
value of 9.5 ppm or greater (based on 1988 and 1989 data) to submit SIP revisions containing
oxygenated fuel requirements. Section 187(b) requires such SIP revisions within 2 years of
enactment. Because section 211(m) is more detailed than section!87(b)(3),  and  applies to a greater
number of CO nonattainment areas, the substantive requirements of section211(m) should be followed
in preparing SIP revisions. (Design value and  interpretation methodology guidance contained in a
June 18, 1990, memorandum from William Laxton, Director, Technical Support Division, to the
Regional Division Directors, should be used to determine which areas are subject to this
requirement.) The oxygenated gasoline program must require gasoline in the specified control area to
contain not less than 2.7 percent oxygen by weight, during that portion of the year in which the areas
are prone to high ambient concentration of CO. The length of the control period is to be established
by the Administrator and shall not be less than 4 months in length unless a State can demonstrate that,
because of meteorological conditions, a reduced period will  assure that there will be no CO
exceedances outside of such reduced  period.  These requirements are to  generally cover all gasoline

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sold or dispensed in the larger of the consolidated metropolitan statistical area (CMSA) or the
metropolitan statistical area (MSA) in which the nonattainment area is located.  Even though it may
be only a small portion of a CMSA that is designated as a nonattainment area, the entire CMSA must
enact oxygenated fuel programs. However, a contiguous State is not  required to establish  a program
for any portion of the CMSA which is in  the contiguous State and is entirely in attainment.

     Oxygenated fuel requirements  must generally take effect no later than November  1, 1992.  (See
"Oxygenated Fuels Labeling Regulations-Notice of Proposed Regulations," [56 FR 31148, July 9,
1991]; "Supplemental Notice of Proposed Guidance on Establishment of Control Periods Under
Section 211(m) of the CAA as Amended," [57 FR 4408,  February 5, 1992]; and "Proposed
Guidelines for Oxygenated Gasoline Credit Programs under section 211(m) of the CAA as Amended,"
[57 FR 4413, February 5, 1992].)

     6.   New Source Review

     The Part D, New Source Review (NSR),  permit requirements of section 173 apply in CO
nonattainment areas.  All moderate CO nonattainment areas with a design value of 12.7 or less must
submit proposed Part D  NSR programs no later than November 15, 1993, in accordance with the
requirements of section 172(c)(5) and section 173. The major stationary source threshold for all
moderate areas  remains unchanged  at 100 tpy of CO.  (See upcoming NSR update package, expected
fall 1992, and General Preamble [57 FR 13948]  Section III.G.  See also Section V.B.  of this
document.)

     7.   Contingency Measures

     For  CO areas with design values of 12.7 ppm or less, contingency measures  are needed  to satisfy
the provisions under section 172(c)(9) and are due by November  15, 1993, as set by EPA under
section 172(b).  These provisions require contingency measures to be  implemented in the event that
an area fails to reach attainment by the applicable attainment date.

     Such contingency measures, once triggered, are to take effect automatically, without further
action by the State or the Administrator. The  trigger for  section  172(c)(9) contingency measures is a
finding by EPA that an area failed to  attain the CO NAAQS by the applicable attainment date
(December 31,  1995). The requirement for contingency measures will "take effect without further
action by the State or the Administrator" which means that no further rulemaking activities by the
State or EPA would be needed to implement the  measures.  Certain actions, such as notification of
sources,  modification of permits, etc., would probably be needed before a measure could be
implemented effectively.  States must show that their contingency measures can be implemented with
minimal further action on their part and with no additional rulemaking actions.  In general, EPA will
expect all actions needed to effect full implementation of the measures to occur within 60 days after
EPA notifies the State of its failure.

    Due to the specification that contingency measures, once triggered,  must take effect without
further action by the State or EPA,  all contingency measures must be  adopted and enforceable prior to
submittal to EPA on November 15, 1993.

    The  CAAA do not specify how many contingency measures are needed  or the magnitude of
emission  reductions they must provide if an  area fails to attain the CO NAAQS.  The EPA believes
that one appropriate choice of contingency measures would be to provide for the  implementation of

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sufficient VMT reductions or emissions reductions to counteract the effect of 1 year's growth in VMT
while the State revises its SIP to incorporate all of the new requirements of a "serious" CO area.

    Some examples of contingency measures for these areas include:

         •    Measures required by the next higher classification (e.g., an enhanced I/M
              program)
         •    Transportation control measures
         •    An employer trip reduction program
         •    An economic incentive program (the following are taken from Appendix W of
              the upcoming "Notice  of Proposed Rulemaking" on  economic incentive
              programs):

              Fee Programs — Road pricing mechanisms are fee programs that are available to
              curtail low occupancy  vehicle use, fund transportation system improvements and
              control measures, spatially and temporally shift driving patterns, and attempt to effect
              land usage changes. Primary examples include increased peak period roadway, bridge,
              or tunnel tolls (this could  also be accomplished  with automated vehicle identification
              systems as well), and toll  discounts for pooling arrangements and zero-emitting/low-
              emitting vehicles.

              Tax Code Provisions  — Mobile source tax code incentive strategies include waiving or
              lowering any of the following for zero or low-emitting vehicles:  vehicle registration
              fees, vehicle property tax, sales  tax, taxicab license  fees,  and parking taxes.

              Subsidies — A State may  create  incentives for reducing emissions by offering direct
              subsidies, grants, or low interest loans to encourage purchase of lower-emitting capital
              equipment or a switch to less-polluting operating practices.  Examples of such
              programs include clean vehicle conversions, starting shuttle bus or van pool programs,
              and mass transit  fare subsidies.

              Early Reduction Programs  — An example would include an old  car scrappage
              program.

         •    A more stringent oxygenated fuels program than is statutorily required.

    The EPA concludes that, to be beneficial,  contingency measures must be implemented within 12
months after the finding of failure to  attain the  CO NAAQS. Contingency measures for CO areas
should achieve emissions reductions that are adequate to counteract the effect of 1 year's growth in
VMT. States should therefore be aware  that late implementation of contingency measures  may result
in the failure to achieve the requisite  level of emissions reductions.  The examples listed above are
merely suggestions. States should  select contingency measures which can be implemented within the
12-month period following the failure.

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C.  REQUIREMENTS FOR MODERATE CO NONATTAINMENT AREAS GREATER THAN
    12.7 PPM

    In addition to the requirements noted below, these CO nonattainment areas must also meet all the
requirements listed in Section B.

    1.   Vehicle Miles Traveled Forecasts

    Section 187(a)(2)(A) requires that States include a forecast of VMT for each year before the
attainment year in the SIP revision for CO submitted to EPA by November 1992 under section
187(a)(7).  The SIP revision must provide for annual forecast updates and annual reports attesting to
the accuracy of the forecasts, as well as estimates of actual VMT in each year for which a forecast
was required.  (See "Section 187 VMT Forecasting and Tracking Guidance," EPA, March 1992,
issued January 1992.)

    2.   Contingency Measures

    Section 187(a)(3) requires areas with design values greater than 12.7 ppm to implement
contingency measures if any estimate of actual VMT or any updated VMT forecast for the area
contained in an annual report for any year prior to  attainment exceeds the number predicted in the
most recent VMT forecast.  (See "Margin of Error" discussion, Section III.I.3  of this document,
regarding exceedance trigger.)  Contingency measures are also  triggered by failure to attain the
NAAQS for CO by the attainment deadline.  Contingency measures must be submitted with the CO
SIP by November 15, 1992. These contingency requirements for SIP's supersede the contingency
requirements contained in the 1982 ozone and CO SIP guidance (46 FR 7182, January 21, 1981).

    3.   Enhanced Inspection and Maintenance

    Section 187(a)(6) requires CO nonattainment areas with a design value greater than 12.7  ppm to
implement enhanced I/M programs in urbanized nonattainment  areas with 1980 populations of
200,000 or greater (as defined by the Bureau of the Census). The plan must meet the requirements  of
section 182(c)(3).  (See "Notice of Proposed Rulemaking on Requirements for Preparation, Adoption,
and Submittal of Implementation Plans:  Inspection/Maintenance Program Requirements," expected in
Federal Register, 1992.)

    4.   Attainment  Demonstration

    Section 187(a)(7) requires a demonstration of attainment by November  15, 1992.  This can be
met through application of a modeling analysis, following the guidance contained in the current EPA
"Guideline on Air Quality Models (Revised)."  A SIP  control strategy, also due by November 15,
1992, must be included to ensure that the area meets the specific annual emissions reductions deemed
necessary for the area to attain the standard by the  attainment date.  (See Section IV.F of this
document for a discussion of "Modeling Assessments.")

    5.   New  Source Review

    All CO nonattainment areas with a design value greater than  12.7 ppm  must submit Part  D NSR
programs meeting the requirements of section 172(c)(5) and section 173 by November  15, 1992.  (See
upcoming NSR update package, expected fall  1992, and General Preamble [57  FR 13948] Section
III.G.  See  also Section V.B of this document.)

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D.   REQUIREMENTS FOR SERIOUS CO NONATTAINMENT AREAS

     /.   Major Stationary Source Definition

     Section 187(c)(l) states that the term "major stationary source" shall include any stationary
source that emits or has the potential to emit 50 tpy or more of CO.  (See memorandum from
William Laxton, Technical Support Division, to Regional Air Division Directors, "Guidance for
Determining Significant Stationary Sources of Carbon Monoxide,"  May  13, 1991.)  Such designations
shall be included in the SIP to be submitted by  November 15, 1992.  Without such  a determination,
"major stationary source" shall refer to any stationary source that emits (or has the  potential to emit)
100  tpy or more of CO.

     2.   Transportation Control Measures

     The TCM's for serious CO areas must be equivalent to those  required for severe areas.  Section
187(b)(2) and 187(a)(2)(B) requires serious CO areas (and Denver,  Colorado) to adopt and implement
enforceable TCM's to offset any growth in emissions from growth  in VMT and, in conjunction with
other control measures, to comply with the periodic emissions reduction requirements of the CAAA.
In addition, serious areas must adopt employee  trip reduction programs,  as described in section
182(d)(l)(B), though Denver has no such requirement. The TCM's are due November 15, 1992.
Applicable TCM's are listed in section 108(f).  (See Section IV.D.3 of this document.)

     3.   Clean Fuel Vehicle  Fleet Program

     Section 246(a)(2)(B) requires  that all CO nonartainment areas with  1980 populations of 250,000
or more and design values of  16.0 ppm or greater submit SIP revisions providing for clean fuel
vehicle fleet programs by May 15, 1994. The programs must require a specified percentage of fleet
vehicles in model year  1998 and thereafter to be clean fuel vehicles that use only clean alternative
fuels when operating in the area.  (See "Clean Fuel Fleet Credit Programs, Transportation Control
Measure Exemptions, and Related Provisions" [56 FR 50196].)

     4.   Milestone and Attainment Failures (Economic Incentives Programs)

     Economic incentives and  transportation control programs, as described in section 182(g)(4), are
required for serious areas under several different types of failure:  failure to submit a milestone
demonstration, section 187(d)(3); failure to meet the milestone, section  187(d)(3); or failure to attain
the standard by the applicable attainment date, section 187(g).  In all  such cases, the State shall
submit a plan revision containing such incentives within 9  months of failure or of EPA notification to
the State of the failure. (See Section V.C of this document.)
E.  REQUIREMENTS FOR "NOT-CLASSIFIED" CO NONATTAINMENT AREAS

    1.   "Not-classified" Areas

    A "not-classified" area is an area that retained its nonattainment designation at enactment, under
section 107(d)(l)(c), but for which data are not available to conclude whether or not the area violated
the standard for CO during the 2-year period from 1988 to  1989.  Subpart 3  of Part  D does not

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the standard for CO during the 2-year period from 1988 to 1989.  Subpart 3 of Part D does not
apply, though some parts of Subpart 1 do. Unless such areas are  redesignated to attainment in section
107(d)(l)(c), certain SIP revisions are due no later than 3  years from the date of designation (i.e., by
November  15, 1993).  The requirements for  "not-classified" areas are contained in the following
sections.

    2.   Section 172  (b-c) Requirements for "Not-classified" Areas

    The CO "not-classified" areas will remain in nonattainment until the five redesignation
requirements (i-v) under section 107(d)(3)(E) are met.  The provisions contained in this section are
described below.  Not-classified CO areas must meet certain SIP requirements under section 172(c),
Subpart 1 as discussed below.  Specifically, all "not-classified" areas must submit  an emissions
inventory and a nonattainment NSR program.

         a.   Reasonable Available  Control Measures (RACM)

    Because these areas are already in or near attainment, EPA does not believe that any measures
other  than what may already be in place or are otherwise required under the Act are "reasonably
available."   Therefore, no additional control measures are required as part of RACM.

         b.   Attainment demonstration

    Section 187(a)(7)  specifically exempts moderate areas with design values of 12.7 ppm  or less
from  requiring an attainment demonstration.  The EPA will presume that existing SIP requirements
and any existing and future Federal requirements (e.g., the Title II rules) will be sufficient to provide
for attainment in these areas.  Likewise, no attainment demonstration is required for "not-classified"
areas.

         c.   Reasonable Further Progress (RFP)

    Since EPA presumes that a "not-classified" area is already in or near attainment, a RFP
requirement is deemed to have been met by any existing SIP requirements, plus Federal measures.

         d.   Emissions Inventory

    An emissions inventory is specifically required under  this section and is not tied to an  area's
proximity to attainment.  Moreover, even if these areas are already attaining or near attainment, they
will need such an inventory to develop an approvable maintenance plan under section 175A.  The
emissions inventory should be included in the SIP revision that is  required  3 years from designation.
The emissions inventory must be submitted by November  15, 1993. The emissions inventory that is
submitted to fulfill this requirement may also serve as the  basis for a redesignation request.

         e.   New Source Review

    All nonattainment areas, including  "not-classified" areas, are  required  to adopt NSR programs
meeting the requirements of section 173, as amended. By November 15, 1993, all "not-classified"
areas  must  submit rules to implement the new Part D NSR permit requirements of section 172(c)(5)
and section 173 of the CAAA. In the meantime, all existing NSR rules remain in  effect.  (See
upcoming NSR update package, expected  fall 1992, and General Preamble [57 FR 13948] Section
III.G. See  also Section V.B of this document.)

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    The EPA will not require nonattainment NSR rules for "not-classified" areas that have submitted
a complete redesignation request that includes the appropriate air quality monitoring evidence that the
area is no longer violating the NAAQS.  However, these areas must continue to apply their existing
NSR program or comply with the NSR permitting requirements of 40 CFR Part 51, Appendix S.

         f.   Monitoring

    Section 172(b) and (c) explicitly states that nonattainment areas should meet the "applicable"
monitoring requirements of section 110(a)(2).  This includes maintaining an ambient monitoring
network to assure that the NAAQS continue to be met at the problem locations in the area.

         g.  Contingency Measures

    Since "not-classified"  areas generally present less serious CO problems than moderate areas, and
contingency measures are not likely to  be necessary to assure attainment for these areas, EPA believes
it appropriate not to apply  the requirement for contingency measures for these areas under a de
minimis approach. This approach is authorized by Alabama Power v. Costle (636 F.2d 323, 360-61,
404-05, DC Circuit 1980), which held  that EPA may exempt de minimis actions from a statutory
requirement when the burdens of regulation would yield little or no value.

    3.   Attainment Dates for Not-Classified Areas

    Section 172(a)(2) requires an attainment date of no later than 5 years from  an area's
nonattainment designation. Since "not-classified" areas are deemed to have been designated on the
date of enactment of the CAAA (November 15,  1990), that attainment date is November  15, 1995.

    If a complete redesignation request is submitted prior to the SIP submittal date, all future
effective SIP submittal requirements are invalidated.
                                              10

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                                       SECTION m
                    ADDITIONAL CO NONATTAINMENT AREA
                             REQUIREMENTS OR ISSUES
A.  MULTISTATE CO NONATTAINMENT AREAS

     /.   Multistate Coordination

     Section 187(e) establishes the requirements for "multistate CO nonattainment areas," defined as
single CO nonattainment areas that cover more than one State.  Each State so affected must take all
reasonable steps to coordinate both the SIP revisions required and the implementation of SIP's that
apply. Failure to take such coordination steps could result in EPA disapproval of SIP revisions
submitted under this section. Under section 187(e)(2), a State failing to provide a demonstration of
attainment for that State's portion of a multistate CO nonattainment area may petition EPA to make a
finding that such a State could have demonstrated attainment, but for the failure of one or more other
States in the area to adequately implement measures required in the multistate CO plan.  Such a
determination would absolve the State from the imposition of the section 179 sanctions under a
finding of failure to provide an adequate attainment demonstration.

     2.   Joint  Work Plan

     Each multistate CO nonattainment area should develop and submit to EPA a joint work plan to
demonstrate early cooperation and integration. The work plan should include a schedule for
developing the emissions inventories, the VMT forecasts, and the attainment demonstration (if
required) for the entire  multistate area. The work plan can be in the form of a letter and cosigned by
all States in the nonattainment area.  The work plan should have been submitted by July 31, 1992.
Each State within a multistate CO nonattainment area is responsible for meeting the requirements
relevant to their portion of the nonattainment area.

     3.   Attainment Demonstration

     In order to  be sufficient to  avoid a section 187(e)(2) finding of failure to demonstrate attainment,
an attainment demonstration must meet the requirements outlined in section 187(a)(7) which requires
areas to  submit a plan showing that the CO NAAQS will be attained by the applicable attainment date
as well as provide for such specific annual emissions reductions as are necessary to attain the
standards by that date.  Moderate, multistate CO nonattainment areas with design values of 12.7 ppm
or less at the time of classification are not required to meet the requirements of developing an
attainment demonstration, as in  section 187(a).
                                              11

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B.  RULE EFFECTIVENESS

    While CO emissions are predominantly from mobile sources, some stationary source emissions
reductions may be creditable in a CO nonattainment strategy as a result of improved rule
effectiveness.  However, rule effectiveness will apply only to a very limited subset of CO-emitting
sources — controlled stationary sources.

    Rule effectiveness is a measure of the degree to which compliance with a rule is achieved across
sources and time.  The actual emissions reductions realized by a control program is a function of the
degree of rule effectiveness achieved.  The rule effectiveness factors are applied to appropriate
sources in the SIP emissions inventory in order to obtain the most accurate estimate of actual
emissions.  In order to adequately document rule effectiveness improvements, a rule effectiveness
study approved by EPA's Stationary Source Compliance Division (SSCD)  must be performed to
demonstrate the improvement.

    A rule effectiveness study requires coordination between the State and EPA and will require both
a field inspection and an office investigation.  The effectiveness ratio calculations will be based on a
comparison of actual emissions to the allowable emissions for sources included in the study. These
emissions must be documented as part of the field investigation phase of the study, and the
calculations must be based on emissions testing,  sampling, and usage data  identified for each source
during the investigation.  A State may develop its own local category-specific rule effectiveness
factors, upon approval, instead of applying the 80 percent default figure.  Procedures for determining
rule effectiveness are incorporated in a November 7, 1991 EPA draft, "Rule Effectiveness Study
Protocol and Procedures for Estimating and Applying Rule Effectiveness in Post-1987 Base Year
Emission Inventories for Ozone and Carbon Monoxide State Implementation Plans," (EPA,  OAQPS,
June 1989, revision due summer 1992) and in "Emission Inventory Requirements for Carbon
Monoxide State Implementation Plans" (EPA-450/4-91-011, March 1991).
C.  AREAS WITH SIGNIFICANT STATIONARY SOURCES OF CO

    Section 187(c)(3) calls for the Administrator to issue guidelines and rules for determining
whether stationary sources contribute significantly to CO levels in an area.  In the case of a serious
area in which stationary sources contribute significantly to CO levels, section 187(c)(l) requires the
State to revise the definition of major stationary sources in that area to include any stationary source
that emits (or has the potential to emit) 50 tpy or more of CO.

    A significant CO stationary source problem is determined through the results of dispersion
modeling of one or more stationary sources of CO in the area. (See guidance in EPA memorandum,
dated  May 13, 1991, from William G.  Laxton, Director, Technical Support Division,  regarding
"Guidance for Determining Significant Stationary Sources of Carbon Monoxide.")  See section
187(c)(2) for CO nonattainment areas where mobile source requirements do not  contribute
significantly and section III.D. below.
                                               12

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D.  AREAS WITH LOW MOBILE SOURCE CO EMISSIONS

    The waiver provisions of section 187(c).(2) provide the Administrator with discretionary authority
to waive certain mobile source requirements in both moderate and serious CO nonattainment areas
where mobile sources do not contribute significantly to CO nonattainment levels in the area.
Specifically, the Administrator may waive any requirements that pertain to transportation controls,
I/M, or oxygenated fuels on a case-by-case basis, where the Administrator determines by rule that the
mobile source contribution is convincingly demonstrated to be de minimis in relation to the cause of
the area's overall CO problem.

    The EPA will  only consider granting a waiver from controls on mobile CO sources under section
187(c)(2) if it is clear that  mobile source emissions in the aggregate are insignificant in the violating
areas, and if there  is a SIP submittal demonstrating attainment of the CO NAAQS by the required
date without such mobile source controls. This would be in addition to a showing under section
187(c)(3) that stationary sources "contribute significantly to carbon monoxide levels in the area." The
attainment demonstration should use EPA-approved modeling techniques  (i.e., a complete modeling
analysis is needed considering point, area, and mobile source emissions).  The waiver would be
granted upon approval of the CO SIP. The State makes  the request for a waiver at the submittal of
the CO SIP as part of the SIP. The waiver of mobile source measures would no longer apply if a
subsequent maintenance plan demonstration relied on such mobile source measures.
E.  REDESIGNATION/RECLASSIFICATION

    /.   Moderate Areas That Do Not Attain ("Bump up")

    Under section 186(b)(2)(A), the Administrator must make a determination within 6 months
following the attainment date (December 31,  1995 for CO moderate areas classified on the date of
enactment) whether such areas attained the standard based on their quality-assured, publicly-available
design value as of the attainment date. Any moderate CO area that the Administrator finds has not
attained the standard by the attainment date will be reclassified as serious by operation of law.  This
upward  reclassification is termed  "bump up."

    Upon reclassification to serious, an area  must meet all applicable requirements for a serious CO
area under section 187(b). Under section 187(f) the Administrator may adjust any applicable
deadlines (other than the attainment date) where such deadlines are shown to be infeasible.  December
31, 2000 becomes the area's new attainment date.

    States that have not attained, but have met all applicable requirements contained in their SIP's
(provided that they have not exceeded the NAAQS more than once during the year of the attainment
deadline), may apply for up to two 1-year extensions of the attainment date under section 186(a)(4).
Such an application should be made as soon as the necessary air quality data are available.

    Under section 107(d)(3)(F), no nonattainment area (or any portion thereof) can  be redesignated to
not-classified.

    2.   Section  J79B International Border Areas

    Under Section 179B of the amended Act, an area that can demonstrate that it is affected by
foreign sources (e.g., Mexico), will not be "bumped up"  if the area has met its own SIP
                                              13

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requirements.  To qualify, if a State must establish to the satisfaction of EPA that it would have
attained the CO NAAQS but for emissions emanating from outside the United States, it will not be
subject to the bump-up provisions for failure to attain for CO in section 186(b)(2).

    The emissions inventory for modeling for such an area must include vehicle emissions occurring
in the United States that are generated by vehicles registered in an adjacent foreign country; such an
inventory must be completed by the State prior to modeling the United States' portion of emissions
and attempting to demonstrate attainment.  Because very few areas are likely to be affected by this
provision, EPA will determine on a case-by-case basis whether the State has satisfactorily  made the
required demonstration. (See General Preamble Section V.C [57 FR 13948].)  '

    3.   Redesignation from Nonattainment to Attainment

    Redesignation to attainment can occur only upon the Administrator's finding that the five
redesignation requirements of section 107(d)(3)(E) are met:  (1) the area has met the NAAQS, (2) the
SIP has been fully approved under section 110(k), (3) the improvement in air quality is due to
permanent and enforceable reductions in emissions resulting from SIP implementation, (4) a
maintenance plan (section 175A) has been submitted and approved,  and (5) the State containing such
area has met all requirements applicable to the area under section 110 and Part D. In addition, EPA
will not approve redesignations until the area has valid Part C Prevention of Significant Deterioration
(PSD) rules in place and has them approved.

    Under section 107(d)(3)(D), the Governor may initiate redesignation independent of notification
by the Administrator.  In such a case,  the Administrator shall approve  or deny such a designation
within 18 months of receipt  of a complete State redesignation submittal.  The existing SIP remains in
effect during this time.

    4.   Redesignation from Attainment to Nonattainment

    Under section 107(d)(3), the Administrator may notify the State's  Governor that "on the basis of
air quality data, planning and control considerations, or any other air quality-related considerations
the Administrator deems appropriate," the designation of an area should be revised to nonattainment.
Such a notice shall be made public. The Governor shall submit a nonattainment designation request
to the Administrator within  120 days of such a notification.

    Under section 107(d)(3)(D), the Governor, on his/her own, may initiate designation, independent
of notification by the Administrator.  In such  a case, within 18 months of receipt of a State
nonattainment designation submittal, the Administrator shall approve or deny such a designation.  The
existing SIP remains in effect for the affected area during this time.
                                               14

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F.  EXTENSIONS OF ATTAINMENT DATES

    Section 186(a)(4) allows a State to apply to the Administrator for an extension of the attainment
date by a period of 1 year (the "extension year"), provided that the State has complied with all SIP
requirements and no more than one exceedance of the NAAQS for CO has occurred in the year
preceding the extension year.  No more than two 1-year extensions may be issued for a single
nonattainment area.  The Administrator may take from 3 to 6 months into the next year to review the
necessary air quality data to make an extension determination.
G.  MAINTENANCE PLANS

    Section 175(A) requires that upon submission of a request for redesignation of a nonattainment
area under section  107(d), a State must also submit a SIP revision to provide for the maintenance of
the primary NAAQS for CO for at least  10 years after redesignation. The plan should contain all
those measures calculated as necessary to maintain attainment of the NAAQS. To ensure that the plan
extends 10 years from redesignation, the State should  submit a maintenance plan that extends at least
12 years.  (See "Ozone and Carbon Monoxide Areas Designated Nonattainment," EPA, OAQPS,
October 26,  1991.  The redesignation guidance will be issued at a future date.)

    Subsequently,  8 years after redesignation of an area to attainment [section 175(A)(b)J, the State
shall submit to the  Administrator an additional revision of the applicable SIP  for maintaining the
primary NAAQS for 10 years after the expiration of the initial 10-year period.  Until the maintenance
plan is approved and redesignation  from  nonattainment to attainment approved, the existing SIP
continues to  apply.

    Maintenance plans must include the  contingency provisions, in section 175(A)(d), "as the
Administrator deems necessary to assure that the State will promptly correct any violation of the
standard which occurs after the redesignation of the areas as an attainment area."  At a minimum, the
contingency measures must contain any measures removed from the SIP during the redesignation
process because it was determined that such measures  were not needed in the SIP in order to maintain
the standard.
                                              15

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                                       SECTION IV
                                 SIP-RELATED ISSUES
A.  INTRODUCTION

    For areas with CO levels greater than 12.7 ppm, the SIP contains a control strategy aimed at
achieving attainment by a specified date.  The control strategy is based on specific emissions
reductions that are either measured or carefully calculated under established procedures for making
emissions projections based on emissions inventories. The ability of a SIP to adequately reflect an
achievable control strategy and an attainable demonstration of compliance with the NAAQS rests upon
the State's ability to develop adequate emissions inventories and models.

    In some cases, EPA has pending SIP submissions.  Generally, EPA would not act on SIP's
submitted prior to the CAAA. However, if there are overlapping portions of pending SIP's and the
required SIP's of the  CAAA, that part of the pending SIP that is still in force and applicable may be
acted upon.  Areas that were designated as nonattainment areas prior to enactment of the CAAA  and
had previous SIP requirements under the existing act will be subject to EPA action only as required
by the  CAAA.
B.  INVENTORY DEVELOPMENT AND UPDATING

    /.   Base Year Inventory

    Section 187(a)(l) requires States in moderate and serious nonattainment areas to submit a
"comprehensive, accurate, current inventory of actual emissions from all sources" within 2 years of
enactment (November 15, 1992). The base year inventory represents actual, typical daily peak season
CO emissions. The peak CO season shall reflect the 3 consecutive months when peak CO air quality
concentrations occur (generally the winter months). For areas where winter is the peak CO season,
the 1990 base year inventory shall include the winter months beginning in 1989 and extending into
1990 (e.g., December 1989  and January and February 1990).  All stationary point and area sources
and all high way/nonroad mobile sources must be included in the inventory.  A State is not required to
include vehicle emissions occurring  in the United States generated from vehicles registered in the
adjacent foreign country in the base year  inventory. (All States except California should use the
updated MOBILE4.1 to estimate mobile source emissions in development of all  1990 base year
inventories.)  (See "Emission Inventory Requirements for Carbon Monoxide State Implementation
Plans," EPA, OAQPS, EPA-450/4-91-011,  March 1991, issued January 1991.)

    2.   Periodic Inventory

    According to section 187(a)(5), moderate (and serious) CO nonattainment areas are required to
submit periodic (revised base year) inventories by September 30, 1995, and then every 3 years


                                             17

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thereafter until the area is redesignated as an attainment area.  The periodic inventory represents
actual emissions.  The first periodic inventory must be based on 1993 emission rate and activity level
information, section 187(a).  (See "Emission Inventory Requirements for Carbon Monoxide State
Implementation Plans," EPA, OAQPS, EPA-450/4-91-011, March 1991, issued January 1991.)

    3.   Modeling Inventory

    Section 187(a)(7) and  187(d)(l) requires moderate nonattainment areas exceeding a design value
of 12.7 ppm to submit an attainment demonstration plan (by November 15, 1992) that demonstrates
attainment by December 31,  1995.  To make the attainment demonstration, base year and projected
modeling inventories are needed. The base year modeling inventory will have a base year consistent
with the CO design value and the peak CO season, while the projected modeling inventory will have a
1995 base year.  The projected modeling inventory will be used to determine if the proposed SIP
control strategies are adequate to reach attainment by the designated date.  (See  "Emission Inventory
Requirements for Carbon Monoxide State Implementation Plans," EPA,  OAQPS, EPA-450/4-91-011,
March 1991 issued January 1991.)

    Serious nonattainment areas must also submit an attainment demonstration plan (by November
15, 1992) which demonstrates how attainment will be achieved by no later than  December 31, 2000.
As above, the base year modeling inventory will have a base year consistent  with the CO design
value, while the projected modeling inventory will have a 2000 base year.

    The CO base year modeling inventory shall represent actual emissions representative of the base
year episodes selected for modeling.  Emissions are determined for an average, 24-hour operating day
during the peak CO season; thus the modeling inventory must be temporally  allocated to hourly
values. Guidance on deriving hourly emissions estimates for the representative operating day in the
peak CO  season can be obtained from the dispersion modeling guidance  document "Procedures for the
Preparation of Emission Inventories for Carbon Monoxide and Precursors of Ozone, Volume II:
Emission Inventory Requirements for Photochemical Air Quality Simulation Models," (EPA, OAQPS,
EPA-450-/4-4-91-014, May 1991.)

    Spatial allocation of emissions over square grid cells varies with the model used (RAM model or
UAM) in that the choice of model will determine the appropriate grid square size.  (See the
discussion in Section 3.4 of "Emission Inventory Requirements for Carbon Monoxide State
Implementation Plans," EPA, OAQPS, EPA-450/4-91-011, March 1991.) Further  guidance on spatial
allocation can be found in  "Procedures for the Preparation of Emission  Inventories for Carbon
Monoxide and Precursors of  Ozone, Volume II:  Emission Inventory Requirements for Photochemical
Air Quality Simulation Models" (EPA, OAQPS, EPA-450-/4-4-91-014,  May 1991.)  (See details on
modeling in section IV.F of this document.)

    4.   Registration Distributions and MOBILE4.1 Projections

    Since MOBILES is not expected in final form until late summer 1992, leaving  CO nonattainment
areas little time to use it for their attainment demonstrations (due November  15, 1992), these areas
should use MOBILE4.1 instead of MOBILES for their projections.  As a result, States will have to
make changes to the vehicle registration distributions used for these projections.  To do this, they can
either update the distributions for the projection year, based on local information, or provide EPA
with their current distributions, and EPA  will supply an updated distribution  figure  for them.

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5.   Other Inventory Issues

The following are the most recent guidance and documentation on emissions inventories:

     1.    "Procedures for Preparing Emission Projections" (EPA-450/4-91-019, July 1991).

     2.    "Emission Inventory Requirements for Carbon Monoxide State Implementation Plans,"
          (EPA-450/4-91-011, March 1991) a revision of "Emission Inventory Requirements for
          Post-1987 Carbon Monoxide State Implementation Plans," (EPA-450/4-88-020,
          December 1988).

     3.    "Guidance for Initiating Ozone/CO  SIP Emission Inventories Pursuant to the 1990
          Clean Air Act Amendments," (EPA, February 1991).

Some specific changes to note are:

     •    In the base year and periodic inventories, States will be required to report CO
          emissions on a daily basis, rather than an 8-hour basis.

     •    The revised model,  MOBILE 4.1, must be used to estimate highway vehicle
          emissions for CAAA SIP inventories.

     •    All CO SIP emissions inventory data should be provided  to EPA in an AIRS
          (Aerometric  Information Retrieval System) compatible format or directly into
          AIRS.

     •    States with SIP emissions inventories prepared under the  proposed post-1987
          policy (52 FR 45044, November 24, 1987) that have 1987, 1988, or 1989 base
          years and that have been determined by the EPA Regional Offices to be
          complete, comprehensive, and accurate will be allowed to update certain
          portions of these inventories to a 1990 base year instead of having to totally
          redevelop the inventories with 1990 data.

    •    The periodic and modeling inventories are associated with tracking required
          emissions reductions and attainment demonstration and are additions to the
         post-1987 policy.

6.   Additional References for Inventory Development Updating

    1.    "Procedures for the Preparation of Emission Inventories for Carbon  Monoxide and
         Precursors of Ozone - Volume 1: General Guidance for Stationary Sources," Third
         edition (EPA, OAQPS, EPA-450/4-91-016, May 1991).

    2.    "Procedures for Emission Inventory Preparation, Volume IV:  Mobile Sources,"
         (EPA, QMS,  EPA-450/4-81-026d, summer 1992).
                                         19

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C.  CONTROLS FOR STATIONARY SOURCES

    Stationary source control information for CO is limited because the motor vehicle sector (and, in
some cases, residential wood combustion as area sources) is the major contributor to CO
nonattainment in most areas. Industrial CO controls have rarely been considered an important part of
urban area CO control plans. Industrial sources are controlled under the Act largely through NSR
(required in all CO nonattainment areas).

    In limiting the States' opportunities to set up a growth allowance, the CAAA establishes
emissions offsets as the primary regulatory mechanism for accommodating major new source growth
without jeopardizing the Act's mandate for reasonable progress toward NAAQS  attainment.  The
basic requirement in section 173(a)(l) remains the same in that to  issue a permit the State must
demonstrate that the new source growth does not interfere with the approved demonstration of
reasonable progress for the area.  (See General Preamble [57  FR 13948] Section III G.2.)

    A lowest achievable emission rate (LAER) is still required for major new or modified sources.
Section 172(c)(i) maintains the provision that CO areas develop RACM and reasonably available
control technology (RACT)  controls for existing major sources (sources of 100 tpy or more). The
major stationary  source definition lowers to 50 tpy in serious  CO nonattainment  areas if stationary
sources significantly contribute  to the nonattainment problem.  (For the development of RACM and
RACT controls, see "Control Technologies for CO Emissions," EPA, OAQPS, EPA-450/3-79006,
March 1979.)

    /.   Industrial CO Controls

    Control information on industrial sources is limited.  An EPA consultant, PEDCo, estimated the
costs and reductions for a number of industrial source CO controls for a national regulatory analysis.
(See letter and attachments from Donald J. Henz to Susan E.  Schechter, PEDCo Environmental, Inc.,
Cincinnati, OH,  May 14, 1979). Four general industry categories are covered.

    1. Iron and Steel
    2. Aluminum
    3. Solid Waste Disposal
    4. Chemicals

    Most controls provide reductions of 90 to 99.5 percent.  Table 1 is a compilation of the control
devices and efficiencies from this study.  (See also  "Control Technologies for CO Emissions," EPA,
OAQPS, EPA-450/3-79006, March 1979.)
                                             20

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    2.   Residential  Wood Burning

    In 1988, EPA promulgated a new source performance standard (NSPS) for new residential wood
heaters (53 FR 5860,  February 26, 1988). (See also  "Regulatory Impact Analysis (RIA) Residential
Wood Heater NSPS," EPA, December  1986.)  The standard is structured in two phases and requires
wood stove manufacturers to have their units certified through laboratory testing to certain prescribed
(particulate matter) emission limits.  The limits are increasingly stringent from phase I to II.

    The goal of the NSPS is to improve the performance of wood heaters nationwide.  Three types of
units have been certified:

    1.   Catalytic — The catalyst provides for combustion at lower temperatures, thus reducing
         emissions.  The catalyst is a thin molded ceramic base coated with a slurry containing
         palladium or platinum.

    2.   Noncatalytic — Noncatalytic units employ design features (e.g., secondary combustion
         chambers) that enhance combustion by manipulating key parameters such as firebox
         temperature, turbulence, residence time of combustion gases, and preheated secondary air.

    3.   Pellet1:  Pellet stoves burn small cylindrical compressed pellets made from wood, sawdust,
         and other biomass fuel.  The pellets are fed to the firebox by a motorized auger which
         allows the operator to control the rate of fuel feed.

    The NSPS may not be sufficient in itself to bring about attainment in nonattainment areas for
particulate matter (PM-10) and CO where emissions from wood stoves and fireplaces are significant.
A document entitled "Guidance Document for Residential Wood Combustion Emission Control
Measures"  (EPA, OAQPS, EPA-450/2-89-015, September 1989)  describes measures available for
additional control in four areas: public education and  awareness,  improving wood burning
performance, reduction in use, and curtailment.

    Public education and awareness include educating the public about the health effects of emissions
from wood burning and the need for controls to reduce unhealthful wood smoke concentrations.

    Improving wood  burning performance includes the converting of existing "conventional" stoves
to cleaner burning units. Such units include the three types that have been certified (catalytic,
noncatalytic, and pellet) and devices that have not been certified but which  can document similar or
better emissions performance.  Numerous "in-home"  field test studies have documented the reduced
emissions of CO and PM-10 and enhanced efficiency  of these types of certified  devices. (See
Emission Factor Document for AP-42, Section 1.10,  "Residential Wood Stoves," December 1991.)
In addition, EPA has reviewed in-home field test data for devices not certified,  such as masonry
stoves, that indicates improved emissions over uncontrolled  wood stoves.  (In both cases, the
appropriate type of data is in-home field test data (versus laboratory) that more  accurately portrays
emissions included in  nonattainment area emission inventories.)

    Measures to reduce wood stove and fireplace use include programs to convert wood burners to
alternative  forms of heat or fireplace technology (e.g., gas logs).  Such measures also include
restrictions on the number and density of wood stoves and fireplaces in housing units.
    'Not all pellet stoves are certified. Sorne models are "not affected" by the wood heater NSPS for failure to meet
all the applicability criteria, including a 35-2-1 or less air-to-fuel ratio.

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    Curtailment is a temporary measure to reduce wood burning over short periods of time when
atmospheric inversions trap wood-burning emissions and cause concentrations to reach levels well in
excess of the standards.  The curtailment is usually for 24-hour periods.
D.  CONTROLS FOR MOBILE SOURCES

    Title I of the Act specifically mandates the following motor vehicle controls:

         •   Basic I/M in CO nonattainment areas with a design value of 12.7 ppm or less
             (subject to section 187(a)(4) savings clause) and enhanced I/M in urbanized
             areas within CO nonattainment areas with a design value above 12.7 ppm and
             1980 populations of 200,000 or greater.

         •   Employer Trip Reduction Programs in serious CO areas; TCM's in serious CO
             areas and Denver.

    Title II of the Act mandates the following control measures:

         •   Oxygenated fuels in most CO nonattainment areas.
         •   New emission standards for light-duty trucks.
         •   Fleet clean fuel programs in CO areas with design values of at least 16.0 ppm
             and population greater than 250,000.
         •   A federally mandated cold temperature CO standard.

    1.   Inspection and Maintenance

    The EPA is preparing to propose a rule regarding both basic and enhanced I/M program
requirements for CO areas.  The EPA currently favors the high-tech I/M option for an enhanced
program including a biennial  centralized program with vehicles tested using a transient exhaust
emission test. The CO  emissions reductions from enhanced I/M should be modeled using
MOBILE4.1 (or MOBILES where available). The regulations will provide guidance on the final
program elements and on modeling inputs.

    2.   Oxygenated Fuels

    The oxygenated fuel requirements  were  proposed in "NPRM for Oxygenated  Gasoline Labeling,"
"Proposed Guidelines for Oxygenated Gasoline Credit Programs," and  "Proposed  Guidance on
Establishment of Control Periods by Area," [56 FR 31149, July 9, 1991].  The oxygenated gasoline
program must require gasoline in the specified control area to contain not less than 2.7 percent
oxygen by weight, during  that portion of the year in which the areas are prone to high ambient
concentrations of CO.  The length of the control period is to be established by the Administrator and
shall not be less than 4 months in length unless a State can demonstrate that, because of
meteorological conditions, that a reduced period will assure that there will  be no CO exceedances
outside of such reduced period. These requirements are to generally cover all gasoline  sold or
dispensed  in the larger of the CMSA or the MSA in which the nonattainment area is located.
However,  a contiguous State  need not establish a program for any portion  of the CMSA which is in
the contiguous State and is entirely in attainment.  Emissions  reductions from oxygenated fuels can be
modeled using MOBILE4.1.  (See also "Proposed Waiver Guidelines for Oxygenated Gasoline
Waivers under section 211[m][3]fc]," [56 FR 43593, September 3, 1991],  "Supplemental  Notice of
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Proposed Guidance on Establishment of Control Periods Under Section 211[m] of the CAA as
Amended," [57 FR 4408, February 5, 1992] and "Proposed Guidelines for Oxygenated Gasoline
Credit Programs under section  211[m] of tfie CAA as Amended," [57 FR 4413, February 5, 1992.])

    Oxygenated gasoline is required for all States with CO nonattainment areas with design values of
9.5 ppm or greater based on 1988 and 1989 data.  For areas that have CO design values of 9.5 ppm
or greater for any 2-year period after 1989, the Act requires that a revision to the SIP shall be
submitted within 18 months after the stated 2-year period.

    3.   Transportation Control Measures

    The EPA is currently developing guidance on an assortment of TCM's.  The TCM's attempt
either to increase vehicle speed by  reducing congestion or to reduce VMT. Increasing vehicle speed
to no higher than 58 mph decreases the per-vehicle emissions of CO.  Since total emissions are
directly proportional to VMT,  decreasing VMT will decrease emissions.  The EPA has published
information documents regarding 16 TCM's identified in section  108 of the Act:

         •    Programs for improved public transit.
         •    Restriction of certain roads or lanes to, or construction of such roads or lanes
              for use by, passenger buses or high-occupancy vehicles.
         •    Employer-based transportation management plans, including incentives.
         •    Trip-reduction ordinances.
         •    Traffic flow improvement programs that achieve emission reductions.
         •    Fringe and transportation corridor parking facilities serving multiple occupancy
              vehicle programs or transit service.
         •    Programs to limit or restrict vehicle use in downtown areas or other areas of
              emission concentration, particularly during periods of peak use.
         •    Programs for the provision of all forms of high-occupancy, shared-ride
              services.
         •    Programs to limit portions of road surfaces or certain sections of the
              metropolitan area to the use of non-motorized vehicles or pedestrian use, both
              as to time and place.
         •    Programs for secure bicycle storage and other facilities, including bicycle
              lanes, for the convenience  and protection of bicyclists in both public and
              private areas.
         •    Programs to control extended idling of vehicles.
         •    Programs to reduce  motor  vehicle emissions, consistent with Title II, which are
              caused by extreme cold start conditions.
         •    Employer-sponsored programs to permit flexible work schedules.
         •    Programs and ordinances to facilitate non-automobile travel, provision and
              utilization of mass transit,  and to generally reduce the need for single-occupant
              vehicle travel, as part of transportation planning and development efforts of a
              locality, including programs and ordinances applicable to new shopping
              centers, special  events, and other centers of vehicle activity.
         •    Programs for new construction and major reconstructions of paths, tracks, or
              areas solely for  the use by pedestrian or other non-motorized means of
              transportation when  economically feasible and in the public interest; and
         •    Programs to encourage the voluntary removal from use and the marketplace of
              pre-1980 model light-duty  vehicles and trucks.
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    The EPA previously issued guidance on implementing TCM's in SIP's in 1990, including a list
of TCM reference documents (See "Revised Final Report:  Transportation Control Measures State
Implementation Plan Guidance," EPA, September 1990, and "Transportation Control Measure
Information Documents," draft, EPA, OMS, October 1991). The U.S. Department of Transportation
(DOT) has also evaluated measures to relieve traffic congestion.  (See  "Evaluation of Travel Demand
Management Measures to Relieve Traffic Congestion,"  DOT, FHWA,  FHWA-SA-90-005, February
1990.)  The TCM Information  Documents, which provide a qualitative discussion of the 16 TCM's
listed in section 108, will be available in the spring/summer of 1992. A Federal Register notice will
announce their availability.

    The EPA's Office of Mobile Sources  (OMS) is producing a document that will estimate the
emission effects of TCM's and changes in travel activity. A draft of this document is  expected
summer 1992.  In addition, EPA is developing a Best Practices Manual, also expected summer 1992.
This document will provide analytical guidance on a range of transportation issues, including TCM's,
from the practitioner's perspective.

    4.   New Light-Duty Truck Emission Standards

    Title II of the  Act requires new trucks to meet a more stringent set of CO tailpipe emission
standards than the current set of standards. Light-duty trucks (LDT's)  with a gross vehicle weight
rating (GVWR) up to 6,000 Ibs and a loaded vehicle weight (LVW) up to 3,750 Ibs must meet a CO
standard of 3.4 g/mi with a 5-year or 50,000-mile useful life guarantee. This is the same as the
current  standard for cars. The new standard for LDT's with GVWR of up to 6,000 Ibs and LVW of
3,751 -  5,750 Ibs or LDT's with GVWR of more than 6,000 Ibs and a  test weight (TW) of 3,751 to
5,750 Ibs is 4.4 g/mi.  The LDT's over 6,000 Ibs GVWR and over 5,750 Ibs TW must meet a CO
standard of 5.0 g/mi.  These standards are to be fully phased in by  1999 and can be modeled using
MOBILE4.1.

    5.   Clean Fuel Vehicle Fleet Programs

    Section 246(a)(2)(B) requires that all CO areas with a  1980 population of a least 250,000 and a
CO design value of at  least  16.0 ppm submit SIP revisions providing for clean fuel vehicle fleet
programs by May 15,  1994. Areas where mobile sources are not a significant contributor to the
nonattainment status may be able to obtain a waiver from the clean-fuel program.  (See section III.D
of this document.  Other areas  may opt into this program.)

    The fleet clean fuel  program is phased in over 3 years beginning in the  1998 model year.  More
stringent Phase II standards begin with model year 2001 (or earlier, depending on availability of clean
fuel vehicles).

    The EPA will  set  the clean fuel fleet emission standard, guidelines for a credit program,
regulations for vehicle conversions to meet the standards, and regulations exempting these vehicles
from certain TCM's.  More information should be available as  EPA proposes and finalizes the
standard. (See "Clean Fuel Fleet Credit Programs, TCM Exemptions, and Related Provisions," [56
FR 50196] Octobers,  1991.)

    6.   Cold Temperature CO Standard

    The EPA will  require cars to achieve  a 10 g/mi CO emission standard at 20° F, with a 5-year or
50,000-mile useful  life guarantee for their  emission control systems beginning with the 1994 model
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year.  Comparable standards will be established for LDT's.  This requirement will be phased in over
3 years, with 40 percent of cars required to meet this standard in 1994, 80 percent in 1995, and 100
percent in 1996 and thereafter.  The final rule for this is pending.  (See the draft final rule [40 CFR
Part 86].) Cold temperature standards for LDT's must be set by EPA at a level comparable in
stringency to the standard for cars.  Emission benefits can be modeled using MOBILE4.1.

    7.   California Low Emission Vehicle Program

    The California low emission vehicle (LEV) program sets more stringent vehicle exhaust
standards. Compliance with these standards can be achieved with the use of advanced vehicle
emission control technology, clean burning fuels, or a combination of the two.  Section 177 provides
the opportunity for individual States to require compliance with standards which are different than the
Federal standards, as long as such standards are identical to the California standards  and are adopted
at least 2 years prior to commencement of the model year.

    8.   Federal Tier II Standards

    The CAAA  calls for EPA to determine whether or not more stringent standards  for LDV's
(LDV's)  and LDT's should be established.  These standards would become effective  after  model year
2003 but before model year 2006. Pending standards set forth in the CAAA are one-half of Tier I
levels. The study may examine standards more or less stringent than those suggested in the Act (but
more stringent than Tier I).  Standards will be promulgated if: (1) there is a need for further
reductions, (2) the  standards are technologically feasible,  and (3) the reductions achievable through
these standards are cost effective.

    The Act also contains provisions for Tier II cold start standards. If,  as of June  1, 1997, six or
more nonattainment areas have a CO design value of 9.5  ppm or greater,  the Tier II  standards will
become effective.  The Tier II LDV standard at 20° F lowers to 3.4  g/mi.  Equivalent standards will
be established for LDT's.
E.  OTHER MOBILE SOURCE CONTROL ISSUES

    The following mobile source categories may be included in SIP inventories under future Federal
rulemaking.

    1.   Nonroad Engines and Vehicles

    In November 1991, EPA completed a study that provides a full inventory of emissions from
nonroad engines and vehicles in 24 nonattainment areas.  (See "Nonroad Engine and Vehicle
Emission Study - Report," EPA, 21A-2001, November 1991.)  This study was required by
section213(a) of the Act. If these  sources are determined to be significant contributors to ozone or
CO concentrations in more than one nonattainment area, section 213(a) also requires EPA to regulate
these sources' emissions within 12 months after completion of the study.  The EPA will propose a
determination of significance for nonroad sources  in the summer of 1992, along with its first
proposed regulations for these sources.  Categories to be regulated are not yet determined.
Locomotives and aircraft were not part of the section 213(a) study, because the Act provides
separately for these categories.
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    An EPA contractor is currently revising the inventories provided in the initial section 213(a)
study so that they conform to the final nonattainment area boundaries that were published in the
Federal Register on November 6,  1991.  The contractor will also prepare nonroad inventories for
several additional serious and above ozone nonattainment areas and CO nonattainment areas with
design values greater than 12.7 ppm.

    The revised, EPA-supplied inventories may be used directly in SIP submittals, though EPA will
also provide the methodologies used to construct the inventories so that an area may modify the
estimates based on additional local activity rates. Estimates for recreational vessels in particular may
benefit from local information.  The EPA will not supply commercial vessel inventories except for the
six areas inventoried in "Commercial Marine Vessel Contributions to Emission Inventories," which
was prepared for EPA by Booz-Allen-Hamilton, Inc. in October, 1991.  Other areas may construct
their own commercial vessel inventories using the methodology described in this report or the
methodology described in Chapter 7 of the 1989 version of Volume IV of "Procedures for Emission
Inventory Preparation."

    When preparing projections for nonroad inventories, States should refer to the document
"Procedures for Preparing Emission Projections," (EPA, OAQPS, 450/4-91-019, July 1991).  For
States other than California,  growth and activity rates  for nonroad equipment should not be offset by
assuming a decrease in emission factors at  this time.

    2.   Locomotives

    Diesel engine equipment has undergone significant modernization in the last decade leading to
downward trends in CO emissions.  New engines are cleaner and more fuel efficient, and are serviced
more frequently.  Decisions  are scheduled  to be made by EPA over the next 5 years about how to
regulate new locomotives.  Because fleet turnover is slow, new standards will not have much of an
emission impact before 2000.

    3.   Aircraft

    New aircraft emission standards for hydrocarbons (HC) were established in 1984.  Design
changes necessary to meet these new standards have also resulted in a slight reduction in CO
emissions. (See "Procedures  for Emission Inventory Preparation, Volume IV:  Mobile Sources,"
Draft, Chapter 5: Emissions from Aircraft, EPA, October 30, 1991.) As the  older aircraft are
phased out, additional reductions will result.

    The CO emissions  from aircraft are particularly high when the aircraft is operating in the
taxi/idle modes.  Single-engine taxiing or reduced-engine taxiing can reduce emissions. Reducing taxi
and idle times for the aircraft will  also reduce CO emissions.
F.  MODELING ASSESSMENTS

    Both urban areawide and hot spot intersection modeling are required for SIP attainment
demonstrations.  Urban areawide modeling is generally required to assess the mesoscale component of
the CO problem, while hot spot modeling is required to assess microscale (i.e., localized) effects of
congested intersections.  The results of the urban areawide and hot spot intersection modeling need to
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be added together and the sum shown must be below the CO NAAQS to demonstrate attainment.
Other approaches for CO attainment demonstration may be approved on a case-by-case basis by EPA.
States are encouraged to consult their Regional Office.

    The term "hot spot" refers to a small area where source and dispersion characteristics can lead to
very high concentrations of CO. A typical hot spot occurs where motor vehicle traffic is high and
slow-moving due to congestion or traffic control devices.  Hot spot modeling is recommended for CO
attainment demonstrations and CO maintenance plans.

    /.   Intersection

    Modeling of CO for roadway intersection air quality analyses should follow the procedures
contained in "Guideline for Modeling Carbon Monoxide from Roadway Intersections," (EPA,  October
1990, under revision).   The recommended hot spot intersection model is CAL3QHC.  (See "User's
Guide for CAL3QHC," EPA, September  1990, under revision.)  States conducting analyses prior to
the release of the revised modeling guidance should use the guidance currently available. Areas
conducting analyses after the release of the revised guidance should use the revised guidance.  This
model combines CALINE3 dispersion with a traffic model to calculate delays and queues that occur at
traffic intersections. The EPA is allowing the continued use of either the TEXIN2 or CALINE4
intersection models in areas where their use has been previously established.  The mobile source
emission factor input to these models should be calculated through the use of the MOBILE4.1  model.

    2.   Areawide Analyses

    For areawide analyses,  the recommended model is either RAM  (see Catalano, J.A., D.B. Turner
and H. Novak, "User's Guide for RAM,"  2nd  ed., EPA, EPA/600/8-87/046, 1987) or the Urban
Airshed Model (see "Guideline for Regulatory  Application of the Urban Airshed Model for Areawide
CO," EPA, May 1992). The Urban Airshed Model (UAM) is the preferred areawide model for
stagnation situations.

    Where point sources of CO are of  concern, such  as large steel plants, these sources should be
modeled using the screening and refined procedures described  in Sections 4 and 5 of the "Guideline
on Air Quality Models," (EPA, EPA-450/2-78-027R, July 1986, under revision).
G.  VMT CONSIDERATIONS

    1.   General Information

    Section 187(a)(2)(A) requires that States with moderate and serious nonartainment areas with
design values greater than 12.7 ppm must submit a forecast of VMT for each year before the
attainment year in the SIP revision for CO submitted to EPA by November  1992 under section
187(a)(7).  This includes annual updates of the forecasts, as well as annual evaluations as to the
accuracy of the forecasts. States should follow the guidance incorporated in "Section 187 VMT
Forecasting and Tracking Guidance" (EPA, March 1992, issued January 1992).  States that wish to
develop alternative forecasting and tracking methods must demonstrate technical equivalency to the
guidance.

    Motor vehicles are the dominant source of CO in most nonattainment areas.  The CO emissions
from highway motor vehicles are a  product of gram-per-mile emission factors (reflecting periods both
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of travel at certain speeds and parking) and the number of miles driven.  The emission factors are a
function of trip length and traffic flow, with average traffic speed being the most common indicator of
flow. The more VMT growth there is likely to be in an area, the more effort is required to reduce
both per-vehicle and stationary source emissions to attain the ambient CO standard by the required
deadlines.  Consequently, the CO attainment plan is built largely around forecasted VMT in the
attainment year.

    Approvable CO nonattainment SIP's must contain a good tracking system and contingency
measures to hedge against uncertainty in the initial VMT forecasts by providing for detection of
deviations from the forecast and potential mid-course corrections prior to the attainment date.  In
particular, EPA guidance calls for the use of systematic traffic ground counts as  the underlying data
for estimates in the future of actual VMT,  at least in the urbanized area.

    2.   Reporting

    The statutory requirement for annual VMT reports suggests that Congress intended the reports,
and any action that they indicate is necessary, to be completed reasonably soon after the close of the
reporting period.  Annual reports on actual  VMT and subsequent forecasts should be submitted
annually no later than each  September 30.   Since most States now submit Highway Performance
Monitoring System  (HPMS) data reports to the Federal Highway Administration (FHWA)  around
June 30, this time line allows States additional time to respond to FHWA data validity questions, and
to prepare updated projections, projected-versus-actual comparisons,  and other elements for the report
to EPA.  The first forecast  includes the year 1993 and each year prior to the year of attainment.
Annual reports  must contain estimates of actual VMT in the nonattainment area in  each year for
which a forecast is required.

    In accordance with section 187(d)(l), States containing serious CO nonattainment areas must also
submit (by  March 31, 1996) a demonstration that emission reductions achieved by  December 31,
1995, were as expected in the SIP. Data to estimate actual 1995 VMT may not be available this
early, in which  case the most recent forecast of 1995  VMT may be used.

    The SIP should identify the organization responsible for submitting these reports. Pursuant to
section 121, the SIP must provide for consultation among all affected agencies, including, but not
limited to, the State Department of Transportation, local metropolitan planning organizations, the
State Department of Environment (or its equivalent), local air  agencies, and local councils  of
government.

    Each annual report should provide a comprehensive history of VMT forecasts and estimates of
actual VMT. The report submitted on September 30, 1994 should also contain the original 1993,
1994, and 1995 VMT forecasts, as well as updated forecasts of 1994 and 1995 VMT. Any changes
in boundaries should be accounted for in such reports.  (See "Section 187 VMT Forecasting and
Tracking Guidance," EPA,  March 1992, issued January  1992, for checklist of documentation required
with the annual  reports.)

    Each State  containing a moderate or a serious CO nonattainment area with a design value greater
than 12.7 ppm at the time of classification should commit in its SIP to keeping all information
supporting the annual reports  referred to in  this section for 3 years and to allowing EPA to audit that
supporting information.  Such an audit would  be conducted in  consultation with FHWA.
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    3.   Tracking

    The EPA specifies the use of the HPMS for purposes of tracking 1993 and later year VMT.
With this approach, traffic counts taken at various points on  an urban area's road network are directly
expanded into an estimate of areawide VMT using statistics on the number of roadway miles
associated with each sampling section.  Since HPMS will be used to track VMT after 1990, areas
using a network model to estimate 1990 VMT must accept the risk entailed in comparing data derived
from two different estimation methods,  recognizing  that the discrepancy may not be apparent until the
later HPMS data are reported.

    Since the HPMS system cannot spatially resolve VMT within the boundaries of the FHWA-
defmed Federal Aid Urbanized Area, and since the Federal Aid Urbanized Area, in turn, may not
fully encompass the nonattainment area  and generally does not follow political subdivisions, States
should identify a "VMT tracking area" for purposes of VMT forecasting and tracking.  "Section 187
VMT Forecasting and Tracking Guidance," (EPA, March  1992, issued January 1992) defines a VMT
tracking area.

    4.   Forecasting

    By November 15, 1992, all States containing moderate and/or serious CO nonattainment areas
with design values greater than 12.7 ppm at the time of classification must forecast annual VMT for
each year from 1993 until the year in which the SIP forecasts attainment.

    Since moderate nonattainment areas must attain the primary NAAQS for CO by December 31,
1995, an affected  State must forecast 1993, 1994, and 1995 VMT by November 15, 1992, unless the
SIP demonstrates that the area will reach attainment prior to 1995, in which case the State only needs
to forecast VMT through the year of attainment.

    Since serious nonattainment areas must attain the primary NAAQS for CO by December 31,
2000, a State containing an area classified as a serious nonattainment area must forecast 1993, 1994,
1995, 1996, 1997, 1998, 1999,  and 2000 VMT by November 15, 1992, unless the SIP demonstrates
that the area will reach attainment prior to 2000, in  which case no forecast is required for years after
the attainment date.

    All States containing a serious CO nonattainment area (currently only the Los Angeles South
Coast Air Basin nonattainment area is so classified)  should forecast VMT in the VMT tracking area
by applying growth  factors, based on a validated network-based travel demand modeling process (the
"Network Travel Demand Model Method"), to the actual annual  1990 VMT. (See Section 3.0 and 4.2
of section 187 "VMT Forecasting and Tracking Guidance," EPA, March 1992, issued January 1992.)

    All States containing a moderate CO nonattainment area with a design value greater than 12.7
ppm at the time of classification should  forecast VMT in the VMT tracking area by the method just
described for serious CO areas if validated travel demand models are currently available, or if such
models could be made available in time to allow the required SIP revisions and submissions. If the
validated travel demand model is unavailable, the State may submit a request to the EPA Regional
Administrator for an EPA commitment to propose approval of a SIP based on the Historical VMT
Method.  (See Section 4.3 of section 187 "VMT Forecasting and Tracking Guidance," EPA, March
1992, issued January 1992.)  The EPA Regional Administrator will review the request in consultation
with the FHWA regional office and will attempt to respond to the request within 30 days.
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    Affected States that track actual VMT using an HPMS-like alternative for a VMT tracking area
smaller than the full urbanized area, and do not use the network model method for forecasting, should
use historical data from the alternative counting program to forecast growth, if data were collected in
the 1985-1990 period. If not, the State should justify some other forecasting method as being
reliable, or forego use of the alternative HPMS-like method. (See Section 4.3 of section 187 "VMT
Forecasting and Tracking Guidance," EPA, March 1992, issued January 1992.)

    5.   Contingency Measures

    The VMT forecast for the attainment year is the basis for the area's attainment demonstration.
Section 187(a)(3) requires that a State subject to the VMT forecasting/tracking provision must provide
in its  SIP for the implementation of contingency measures if the annual estimate of actual VMT or a
subsequent VMT forecast exceeds the last forecast of VMT or if the area fails to attain the CO
NAAQS by the attainment date. For CO areas with design values of 12.7 ppm or less, contingency
measures are needed to satisfy the provisions under section 172(c)(9) and are due by November 15,
1993, as set by EPA under section 172(b).  These provisions require contingency measures  to be
implemented  in the event that an area fails to attain by the applicable attainment date.  All
contingency measures for CO areas with design values above 12.7 ppm must be adopted and
enforceable and submitted to EPA by November 15,  1992, as set by EPA under section  172(b).

    Contingency measures, once triggered, are to take effect automatically,  without further rule-
making action by the State or the Administrator.  Certain actions, such as notification of sources,
modification of permits,  etc.,  would probably  be needed before a  measure could be implemented
effectively. States must  show that their contingency measures can be implemented with minimal
further action on their part and with no additional rulemaking actions.  (See  General Preamble, 57 FR
13948, Section III.B.2.b.)

    The EPA concludes that, to be beneficial, contingency measures must be implemented within 12
months following the finding of failure to attain the CO NAAQS — after the  finding that actual VMT
or newly forecasted VMT exceeds previously forecasted VMT. Contingency measures for CO areas
should achieve emissions reductions to counteract the effect of 1 year's growth in VMT. Therefore,
States should be aware that late implementation of contingency measures may result in the failure to
achieve the requisite level of emissions reductions. The examples listed in Section II.B.7 of this
document are merely suggestions.  States should select contingency measures which can be
implemented  within the 12-month period following the failure.
H.  SERIOUS AREA ISSUES

    /.   Milestone Demonstration

    By March 31, 1996, all States containing serious CO nonattainment areas must submit to the
Administrator a "milestone" demonstration that the area has achieved the specific emissions reductions
required by December 31, 1995. This is to ensure that a serious area is well on track toward meeting
the attainment date of December 31, 2000.  Affected States should use the annual VMT forecasts
developed in accordance with VMT forecasts for the 1992 SIP submittal as the starting point for the
serious area milestone inventory required under section 187(d)(l).  The Administrator shall  determine
whether or not a State's demonstration is adequate within 90 days after the Administrator's receipt of
a demonstration containing all information required by the Administrator.

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    Failure to meet the milestone demonstration will necessitate submission of a plan revision within
9 months after such failure.  The State shall submit a plan revision as required under section
187(d)(3) to implement an economic incentive and transportation control program, as described under
section 182(g)(4) in order to meet the emissions reductions of the December 31, 2000 attainment date.
Economic incentives and transportation control programs are required for failure to submit a
milestone demonstration, failure to meet the milestone, or failure to attain the standard by the
applicable attainment date.  A State should anticipate any such failures and begin to develop such
programs as soon as possible, without waiting for such failure to occur.

    2.   Transportation Control Measures

    Serious CO areas (and Denver, Colorado) must adopt and implement enforceable TCM's to
offset any growth in emissions from growth in VMT and, in conjunction with other control measures,
as necessary to  comply with the periodic emissions reduction  requirements of the CAAA.  The
TCM's, which are required to offset any growth in emissions from growth in VMT and number of
vehicle trips and to achieve necessary reductions in mobile source emissions, are due by November
15, 1992.  States should choose from the list of TCM's and other measures in section 108(f).  These
requirements are contained in section 187(b)(2) for CO areas and section 187(a)(2)(B) for Denver.

    All serious CO areas covered by the clean fuel vehicle fleet program (except for areas in New
York State, should any such area ultimately be bumped to serious), as well  as Denver, must explain
why any section 108(f) measure is not adopted, what proposed emission  reduction measures will
provide comparable reductions, or why such reductions are not necessary to attain the CO NAAQS.
This requirement may be met by an attainment demonstration, using EPA modeling techniques, that
shows the other adopted control measures are sufficient to provide for attainment by the required
date.  (See "Guidance on Air Quality Models," revised, EPA, EPA-450/2-78-027R,  July 1986.)

    This later requirement must be met by any serious CO area meeting the section  246 definition of
"covered area." Section 246 defines "covered areas" as areas with a CO design value of 16 ppm or
greater, excluding those areas in which  mobile sources do not contribute significantly to CO
exceedances. Currently, this requirement would apply to the Denver and Los Angeles areas.  Areas
that are not "covered areas"  are not required by this provision to justify  their rejection of TCM's.
(See General Preamble,  57 FR 13948, Section III.B.3.b.)

    The EPA is developing further guidance on the quantification of TCM's. Either OMS or the
Regional Offices should be consulted.

    3.   Clean Fuel Vehicle Fleet Programs

    Section 246(a)(2)(B) requires that all CO nonattainment areas with 1980 populations of 250,000
or more and design values of 16.0 ppm or greater submit SIP revisions providing for clean fuel
vehicle fleet programs by May 15,  1994. The programs must require a  specified percentage of fleet
vehicles in model  year 1998 and thereafter to be clean fuel vehicles that  use only clean alternative
fuels when operating in the area.

    For LDV's and LDT's, the required percentage must be  30 percent  in  1998, 50 percent in 1999,
and 70 percent in  2000 and thereafter.  For heavy-duty trucks, the percentage must be 50 percent in
each of the respective years. Light-duty vehicles and LDT's in fleets participating in this program for
these model  years must also meet the Title II clean fuel vehicle standards for model year 2001.  If
                                              32

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LDV's and LDT's of 6,000 Ibs GVWR or less are not available in California before model year
2001, the phase-in schedules will be delayed accordingly.

    Some of the major program requirements include the following: that the fuel providers make
clean alternative fuel available to fleet operators; that Federal fleets (except certain vehicles certified
by the Secretary of Defense as needing an exemption based on national security grounds) be included
in the program; and that credits consistent with EPA regulations due 1 year from enactment be issued
for  (1) purchasing more vehicles than required,  (2) purchasing vehicles that exceed the established
standards, or (3) purchasing vehicles prior to the effective date of the program.  In addition, certain
TCM's may not apply to covered fleet vehicles consistent with EPA regulations.
I.  CONTINGENCY MEASURES

    /.   Implementation of Measures

    By November 15, 1992, a State containing a moderate and/or a serious CO nonattainment area
with a design value greater than  12.7 ppm at the time of classification must commit in its SIP to
implement specific measures if any estimate of VMT in the area or a subsequent VMT forecast
exceeds the number predicted in  the most recent prior forecast or if the area fails to attain the CO
NAAQS.  Such measures take effect automatically without further action by the State or the
Administrator.

    The CAAA do not specify how many contingency measures are needed or  the magnitude of
emission reductions (or VMT reductions) they must provide.  The EPA believes that, for serious
nonattainment areas,  a logical contingency measure for failure to attain by the attainment date would
be the adoption of a requirement for a minimum 3.1 percent oxygen content of  gasoline subject to the
waiver provisions in  section 211(m)(3).  This suggested contingency measure parallels the
requirement under section 211(m)(7) for serious areas which fail to attain the CO NAAQS by
December 31, 2000,  to adopt and implement an oxygenated fuels program of at least 3.1  percent.
For serious areas that fail to meet rate of progress requirements, for moderate areas that fail to  attain
by the attainment date, and for all areas that exceed a VMT forecast, States may select contingency
measures for the reduction of CO emissions. (See General Preamble, 57 FR 13948.) For additional
contingency measure examples, refer to Section II.B.7 of this document.

    The EPA interprets the requirement for contingency measures to "take effect without further
action by the State or the Administrator" to mean that no further rulemaking activities by the State or
EPA would be needed to implement the measures.  Certain actions, such as notification of sources,
modification of permits, etc., would probably be needed before a measure could be implemented
effectively.  States must show that their contingency measures  can be implemented  with minimal
further action on their part and with no additional rulemaking actions.  In general,  EPA will expect
all actions needed to  effect full implementation of the measures to occur within  60  days after EPA
notifies the State of its failure.

    2.   Interaction with VMT  Offsets

    The EPA believes that, for an exceedance  of a VMT forecast, one appropriate choice of
contingency measures would be to provide for the implementation of sufficient VMT reductions or
emissions reductions  to counteract the effect of 1 year's growth in VMT while the  State revised its
SIP (including VMT  projections) to provide for attainment by the applicable date.  These measures
                                              33

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may offset either the excess VMT in the nonattainment area or the additional CO emissions in the
area that are attributable to the additional VMT.  Since EPA will require the State to revise its SIP
within 1  year of finding that VMT levels are exceeding forecasts, the contingency measures should be
capable of reducing VMT or resultant emissions by an amount equal to the projected annual growth
rate for VMT.  In other words, if VMT is expected to increase at a rate of 2 percent per year, the
contingency measures under this alternative should be capable of reducing future VMT (or offsetting
VMT growth) by 2  percent.

    3.   Margin of Error

    The need to preserve the integrity of the attainment demonstration and to react to unexpected
VMT growth must be balanced against the desirability of preventing a false trigger of the contingency
measures caused by the uncertainty in the VMT estimation and reforecasting processes.  This
uncertainty can result in a merely transitory appearance in  1 year that actual or  newly reforecasted
VMT exceeds the original VMT forecast, with the situation reversing in the next year or the year
thereafter.

    The sampling and non-sampling error inherent in HPMS points to  a practical and theoretical need
for a margin of error around VMT estimates and forecasts  so that contingencies are not triggered  for
small,  and possibly  random, deviations from forecasted VMT.  At the same time, actual annual VMT
cannot be allowed to creep above the original attainment-producing forecast without limit.  Though
successively higher  forecasts may remain within the established margin of error compared to the
previous  forecasts, they could, in fact, be drifting further and further from the original forecast.

    In order  for a margin of error to serve the purpose of  preventing a false trigger of contingency
measures without allowing unchecked VMT growth, actual annual VMT and later forecasts should
never be allowed to be more than the defined margin above the forecast that is  the basis for an
approved attainment demonstration.   The use of an attainment-producing forecast  as the base for
measuring deviations ensures that growth in VMT remains  consistent with the attainment
demonstration (except for a de minimis deviation), or,  if it does not, that contingency measures are
triggered.

    Consequently, contingency measures will be triggered upon a finding by EPA that an estimate of
actual annual VMT  or an updated VMT forecast exceeds the most recent prior VMT forecasts by
more than 5.0 percent in  1994, 4.0 percent in 1995, and 3.0 percent thereafter.  These declining
percentages are based on  expected improvements that will be made in calculation of VMT.
Contingency measures will also be triggered even if the margin of error is less  than the specified
percentage for that year if, cumulatively, estimates of actual VMT or VMT forecasts exceed the VMT
forecast relied upon in the attainment demonstration for the area by more than 5.0 percent.  (See
General Preamble 57 FR  13948.)

J.  LONG-TERM CONTROL MEASURES AND STRATEGIES

    Some serious CO nonattainment areas (and perhaps areas  with long-term attainment dates for
other pollutants) may  need additional time to fully develop  and adopt certain "long-term" measures
that would be the preferred means to reach attainment. These measures would  include those that
require complex analyses and decision making and coordination among a number  of government
agencies.
                                              34

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     Such areas will be allowed reasonable additional time to complete full development and adoption
under the following conditions: (1) the plan containing the demonstration of attainment must identify
each measure for which additional time would be needed for full development and adoption, (2) the
plan must show that the long-term measures cannot be fully developed and adopted by the submittal
date for the attainment demonstration, (3) the plan must contain an enforceable commitment by the
relevant agency that development and adoption will occur on an expeditious schedule to achieve
specified emissions reductions from each long-term measure for each year through the attainment
year, (4) the plan must contain "backstop" measures that would be implemented to achieve equivalent
emissions reductions unless the long-term measure is adopted on schedule, and (5) the long-term
measures must not be needed to meet any emission reduction requirement during the first 6 years
after enactment.

     The "backstop" measures required under condition 4 must be submitted with the 1992 attainment
demonstration in fully adopted form. The "backstop" measures must be designed to go into effect
automatically on a schedule sufficient to achieve all of the reductions identified with each long-term
measure for each year through the attainment year. The "backstop" measures may represent broad,
across-the-board reductions in emissions, ratiier than thoroughly analyzed and developed control
measures.  For this reason, EPA does not anticipate the actual  implementation of "backstop" measures
in most cases, as States will have ample opportunity to submit  SIP revisions incorporating the fully
developed long-term  measures and to delete the "backstop" measures from the SIP.  Additionally, if a
long-term measure cannot be developed, then the State has the option of submitting a SIP revision
identifying a fully developed and adopted  alternative measure to replace the original long-term
measure prior to any necessary implementation of "backstop" measures.

     Thus, a State may find that progress can be achieved with measures that are fully developed by
the 1992 SIP submittal date.  However, the State may determine that expeditious attainment of the
NAAQS is impossible, unless the SIP also includes measures which cannot be fully developed until
after the  1992 SIP is  due.  In its 1992 SIP submittal, the State must clearly describe each  of these
long-term measures and  show that each measure cannot be fully developed and adopted until a
specified future date, despite expeditious implementation efforts.  The 1992 SIP must include with
each long-term measure  an enforceable schedule binding responsible agencies to achieve identified
emissions reductions  from each measure.

    Along with these provisions, the State's 1992 SIP submittal must include "backstop"  measures.
The "backstop" measures must be fully adopted and scheduled  for implementation to achieve
reductions equivalent to those assigned each year by the long-term measures.  When each long-term
measure is fully developed, it must be submitted to EPA as a SIP amendment.  This amendment
would also propose deletion of the associated "backstops."  The EPA's approval of the long-term
measures would also  rescind from the SIP the "backstop" measures.
                                              35

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                                       SECTION V
              THE RELATIONSHIP OF THE CO SIP WITH OTHER
                                  CAAA PROVISIONS
A.  TITLE II: MOTOR VEHICLES

    /.   On-Board Diagnostics

    Section 202 requires the manufacturers' installation of on-board diagnostic systems on new
LDV's and LDT's, beginning with model year 1994.  States that have SIP's containing I/M programs
must amend their plans within 2 years of EPA requiring them to do so,  to provide for inspection of
on-board diagnostic systems. (See "Notice of Proposed Rulemaking on On-Board Diagnostics," [56
FR 48272].  Final rulemaking expected July 1992.)

    2.   Oxygenated Fuels

    Section 211(m) requires CO nonattainment areas with a design value of 9.5 ppm or greater
(based on the 2-year period of 1988 and 1989) to submit a SIP revision  to implement the use of
oxygenated fuels [see section 187(b)(3)].  Such provisions apply to fuel  retailers in the larger of the
CMSA's in which the nonattainment area is located or, if the area is not located in a CMSA, the
MSA in which the area is located.  However, a contiguous State need not establish a program for any
portion of the CMSA which is in the contiguous State and is entirely in  attainment.  For any town
included in a CMSA subject to the "oxyfuel" provisions, the entire county will be subject to the
oxyfuel  program.  The oxygenated gasoline program must require gasoline in the specified control
area to contain not less than 2.7 percent oxygen by weight, during that portion of the year in which
the areas are prone to high ambient concentration of CO.  The length of the control period is to be
established by the Administrator and shall not be less than 4 months in length unless a State can
demonstrate that, because of .meteorological conditions, that a reduced period will assure that there
will be no CO exceedances outside of such reduced period. (Waivers for a shorter period must be
submitted by the Governor and demonstrated to the Administrator and must include meteorological
data.) A waiver to section 211(m) may be granted by the Administrator upon a State's demonstration
that such requirements would prevent or interfere with the attainment of the primary NAAQS for any
air pollutant other than CO,  or upon demonstration of inadequate supply of the oxygenated fuel.

    During the period when section 211 (m) (2) applies, trade in marketable oxygen credits from
gasolines with higher oxygen content than required to offset the sale or use of gasoline with a lower
oxygen content than required will be permitted.  However, no credits may be transferred between
nonattainment areas.  Although  EPA strongly recommends that States adopt credit programs, such
credit programs are still optional for States to adopt. A State may adopt a per-gallon 2.7 percent
requirement as its option.
                                             37

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    Upon failure of a serious CO nonattainment area to achieve attainment by the specified
attainment date, the State shall submit a plan revision for the area providing for the implementation of
3.1 percent oxygenated fuel.  (See "Oxygenated Fuels Labeling Regulations-Notice of Proposed
Regulations," [56 FR 31148, July 9, 1991]; "Supplemental Notice of Proposed Guidance on
Establishment of Control Periods Under Section 211(m) of the CAA as Amended," [57 FR 4408,
February 5,  1992]; and "Proposed Guidelines for Oxygenated Gasoline Credit Programs under
section211(m) of the CAA as Amended," [57 FR 4413, February 5, 1992].)

    3.   Clean Fuel Vehicle  Fleets

    Section 246(a)(2)(B) requires all CO nonattainment areas with a 1980 population of 250,000 or
more and a design value of 16.0 ppm or greater to provide for clean fuel vehicle fleet programs no
later than May 15,  1994.  The programs must require a specified percentage of fleet vehicles in
model year 1998 and thereafter to be clean fuel vehicles and use clean alternative fuels when
operating in the nonattainment area.
B.  NEW SOURCE REVIEW

    The EPA is in the process of amending its NSR regulations to reflect the changes mandated by
the CAAA.  For guidance on offsets, refer to the upcoming NSR update package (expected fall 1992).
In the meantime, this section is meant to provide the minimum statutory requirements States must use
to revise their existing NSR nonattainment permit plan provisions. While the NSR provisions can
lead to construction bans and increased emissions offsets for new and modifying sources, these
sources are generally not the predominant contributors to CO nonattainment.  Nonetheless, CO
nonattainment areas must  meet  NSR requirements.  (See General Preamble, 57 FR  13948,  Section
III.G.)

    The CAAA require States to adopt SIP revisions subject to EPA approval that  incorporate the
new preconstruction permitting requirements for  new and modified sources.  The EPA has previously
announced its interpretation that the new NSR  requirements did not go  into effect with passage of the
CAAA, but rather become effective in accordance with the schedule  for State adoption of SIP
revisions.  (See J. Seitz memo, "New Source Review (NSR) Program Transitional Guidance," p.6,
March 11,  1991.)  New rules for most CO nonattainment areas are due 3 years from the date of
nonattainment designation.

    If these deadlines pass without States submitting NSR  revisions, EPA may impose sanctions on
delinquent States.  The sanctions include reducing a State's highway funds, section!79(b)(l), or
increasing emissions offsets (to at least 2 to 1) for new  and modified sources, section 179(b)(2).  In
addition to  imposing sanctions, EPA is also required to promulgate a FIP when it finds that a State
has failed to make a required SIP submirtal or  has made an incomplete submission.  Finally, EPA
may impose a construction ban where the Administrator determines that a State "is  not acting in
compliance with any requirement or prohibition of the Act relating to the construction of new sources
or the modification of existing sources ..." [CAAA section 113(a)(5)].
C.  ECONOMIC INCENTIVE PROGRAMS

    The use of economic incentives are explicitly allowed for in the general SIP requirements [section
110(a)(2)], the general provisions for nonattainment SIP's [section 172(c)(6)], and in the system of

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regulations for controlling emissions from consumer or commercial products [section 183(e)(4)].  In
some cases, economic incentives are mandated such as upon State failure to submit a milestone
demonstration or to meet a required specific emission reduction milestone, or for serious CO
nonattainment areas to attain the standard.  [See section  187(d)(3) and 187(g)].  States are encouraged
to incorporate economic incentive programs as early as possible, even in anticipation of attainment or
milestone failure.

     Section 182(g)(4)(A) defines a State economic incentive program as one that is consistent with
EPA rules (expected in November 1992).  Although section 182(g)(4) refers to ozone economic
incentive programs, this definition also applies to economic incentive programs for CO. Such
programs may  include systems of emission fees, marketable permits, or State fees on the sale or
manufacture of products, as well as incentives and requirements to reduce vehicle emissions and
VMT, including any of the transportation control  measures in section 108(f).

     It is expected that the Economic Incentive Program  (EIP) rules will be broadly applicable to any
type of EIP, and will provide flexibility to States  in the development of innovative, market-based
programs for permitted stationary, area, and mobile sources. The EIP  rules will require that EIP's
submitted by States for approval to the EPA as part of a SIP for a nonattainment area contain design
features that will ensure that emissions reductions credited to the program will be quantifiable and
consistent with the SIP attainment and RFP demonstrations;  any credited emissions reductions will be
surplus to reductions required by, and credited to, other implementation plan provisions to avoid
double counting of reductions; programs are federally enforceable and that credited reductions are
permanent within the timeframe specified within the program; and no interference with other
requirements of the Act will occur.  The proposed rules  will identify key program provisions which
must generally be  included to ensure that the above requirements will be met. However, it is not
expected that the rules will limit flexibility and innovation beyond those constraints that are necessary
to meet these requirements.
D.   CONFORMITY

     Section 176(c) provides the framework for ensuring that Federal actions conform to air quality
plans under section 110.  Before any agency, department, or instrumentality of the Federal
Government engages in, supports in any way, provides financial assistance for, licenses, permits, or
approves any activity, that agency has an affirmative responsibility to ensure that such action
conforms to the applicable implementation plan (e.g., SIP, FIP, Tribal Implementation Plan).  (See
"Guidance  for Determining Conformity of Transportation Plans, Programs and Projects with Clean
Air Act Implementation Plans During Phase 1 of the Interim Period," EPA and DOT, June  1991.)
The Notice of Proposed Rulemaking  (NPR) for conformity is expected in the fall of 1992.  The intent
of the conformity provisions is to ensure that air quality considerations play a greater role in federally
supported transportation planning efforts as well as other Federal activities. (See General Preamble,
57 FR 13948, Section III.H.2.)

     Conformity to an implementation plan means that proposed activities must not (1) cause or
contribute to any new violation of any standard in any area, (2) increase the frequency or severity of
any existing violation of any standard in any area, or (3) delay timely attainment of any standard or
any required interim emission reductions or other milestones in any area. Once EPA promulgates
transportation conformity to FHWA and Federal Transit Administration (FTA) regulations, each State
must submit a SIP revision to EPA and DOT, indicating the procedures by which conformity
assessments will be made. The EPA's rule establishing the criteria and procedures for determining
                                              39

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general conformity will require each State to submit a SIP revision to EPA establishing conformity
procedures consistent with the rule.

    /.   Interim Period

    Until the effective date of the EPA final rule establishing the criteria and procedures for
determining conformity, transportation conformity should be determined according to "Guidance for
Determining Conformity of Transportation Plans, Programs and Projects with Clean Air Act
Implementation Plans During Phase I of the Interim Period,"  (EPA/DOT, June 1991).  During the
period between the effective date of EPA's final rule and the  approval of SIP revisions demonstrating
RFP and attainment (Phase II of the interim period), the transportation conformity criteria will be
consistent with  section 176(c)(3).

    2.   Emission Budgets for Transportation Conformity

    For nonattainment areas required  to demonstrate RFP and attainment, the SIP revision will
contain statements of the motor vehicle emissions on which the demonstrations are based.  These
statements will  become the "emission budgets" (for the criteria pollutant and its precursors) for
highway and transit vehicles. The  transportation plans and programs produced by the transportation
planning process will be required to result in emissions which are within the budget.  Regional
emissions analyses will be required to  demonstrate that emissions from the transportation system after
the plans and programs are implemented will not exceed the emissions budget, despite any difference
that may exist between the area's current  and forecasted population, employment, and travel demand
and those that were assumed at the time of SIP preparation and adoption.

    Emission budgets should be stated clearly and unambiguously in the SIP so that future
comparisons can be made accurately.  At  the State's option, one or more alternative emission budgets
may be included in the SIP,  each of which is shown to produce milestone compliance and/or
attainment.

    Moderate CO nonattainment areas with design  values of  12.7 ppm or less are not required to
demonstrate attainment and therefore will not have  an existing basis for establishing emission  budgets
for the purpose of conformity.  For these areas, States may choose one of two options to include in
the SIP:

    Option  1:  The State may elect to extend the interim conformity criteria of section 176(c)(3) (A)
    for the entire period prior to EPA approval of  either a section 175A maintenance  SIP or,
    following bump-up, a SIP that meets RFP and  attainment requirements.

    Option 2:  The State may voluntarily submit, as a SIP revision, an attainment demonstration and
    corresponding motor vehicle emissions budget, like higher classified areas.  This may show that
    transportation plans that cause emission increases are in fact compatible with attainment,  thereby
    providing the transportation planning process flexibility to adopt such plans later.

    3.   Maintenance Plans

    For States  with areas redesignated to attainment and operating under a maintenance plan  under
section 107(d),  the emissions budget concept for conformity still applies.  A budget for motor vehicle
emissions must  be established in the maintenance plan and shown to be consistent with the
maintenance demonstration in light of expected emissions from other sources.
                                              40

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    4.   Failure to Meet a Milestone/Attainment

    Failure to meet a milestone or to attain by the appropriate date will require development of a new
emissions budget as part of replanning. Until a new SIP is approved or a Federal plan is
promulgated, the previous budgets will remain in effect for the purpose of demonstrating conformity.
                                              41

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42

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                                   APPENDIX A:  CHECKLIST


A.  MINIMUM REQUIREMENTS

1.  Moderate CO Nonattainment Areas (less than or equal to 12.7 ppm):

    o    Emissions inventory by November 15, 1992

    o    I/M corrections by November 15, 1992 (committal SIP under section 110 (k) (4) expected)

    o    Periodic inventory by September 30, 1995, and every 3 years thereafter

    o    Oxygenated fuel programs in effect by November 1,  1992

    o    Section 172(c)(9) contingency measures due by November 15, 1993

2.  Moderate CO Nonattainment Areas (greater than 12.7 ppm):

    o    As above

    o    VMT forecasts by November 15, 1992

    o    Enhanced I/M, in urbanized areas with 1980 populations of 200,000 or more, by November 15, 1992
         (committal SIP under section 110(k)(4) expected)

    o    Attainment demonstration by November 15, 1992

    o    SIP control strategy by November 15, 1992

    o    NSR programs submitted by November 15, 1992

    o    Section 187(a)(3) contingency measures due by November 15, 1992

3.  Serious CO Nonattainment Areas:

    o    As above

    o    TCM's and employer trip reduction programs by November 15, 1992

    o    Clean fuel vehicle fleet programs by May 15, 1994

4.   "Not-Classified" Areas

    o    SIP revisions due 3 years from date of designation (November 15, 1993)

    o    Emissions inventory included in SIP revision

    o    Attainment date no later than 5 years from designation (November 15, 1995 for areas designated on
         enactment of CAAA)
                                               A-l

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5.  Other Deadlines

    o    Multistate work plans by July 31, 1992

    o    Redesignation areas submit SIP revision with maintenance plans to ensure NAAQS for at least 10
         years after redesignation

6.  SIP Control Strategy

    o    Base year inventory by November 15, 1992

    o    Periodic inventory by September 30,  1995

    o    Modeling inventory by November 15, 1992

    o    Attainment demonstration plan (serious areas) by November 15, 1992


B.  ADMINISTRATIVE CHECKLIST

1.    Were the following terms defined?

    Nonattainment Area                            	Yes    	No
    RACT/RACM                                	Yes    	No
    TCM's                                      	Yes    	No
    Contingency Measures                         	Yes    	No


Comments:
2.  Did the plan contain evidence of involvement and consultation of the public, local governments, and
    State legislators?

         Yes       No
Comments:


3.   Was a certificate submitted documenting a public hearing?

     	Yes  	No

Comments:


4.   Did the plan provide for public availability of emission data?

     	Yes  	No

Comments:
                                                A-2

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5.  Did the plan document the State's authority to determine compliance of CO sources (including
    recordkeeping, inspections,  and source testing)?

         Yes      No
Comments:
6.  Did the plan document the State's authority to install, maintain, and use emission monitoring and
    controlling devices?

         Yes       No
Comments:


7.   Were copies of laws or regulations provided that define the State's authorities?

     	Yes  	No

Comments:


8.   Did the State delegate authority to a local agency to implement portions of this plan?

     	Yes  	No

Comments:


9.   Did the plan identify the organizations that are developing, implementing and enforcing the plan?

     	Yes  	No

Comments:


10.  Were the responsibilities of each organization identified?

     	Yes  	No

Comments:

11.  Did the plan include  a list of any memorandum of understanding among agencies responsible for
     developing, implementing, and enforcing the plan?

     	Yes  	No

Comments:
                                               A-3

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12. Did the plan include a summary of procedures used to involve the public, government, and elected
    officials in developing the plan?

         Yes       No
Comments:


13.  Were any comments from the above sources discussed in the plan?

    	Yes 	No

Comments:


14. Did the plan contain a description of resources available to responsible agencies?

    	Yes 	No

Comments:


C.  ATTAINMENT DEMONSTRATIONS FOR AREAS GREATER THAN 12.7 PPM

/.   Did the plan discuss the methodology used to demonstrate attainment?

    	Yes  	No

Comments:


2.    Was urban areawide modeling utilized for the attainment demonstration?

    	Yes 	No

Comments:


3.    Was hotspot modeling utilized for the attainment demonstration?

    	Yes  	No

Comments:


D.  BASE YEAR EMISSION INVENTORY CHECKLIST

    Refer to "Quality Review Guideline for 1990 Base Year Emission Inventories" (EPA-450/4-91-022
September 1991).
                                              A-4

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E.   MOBILE SOURCES

1.   Were the vehicle emissions divided into categories (light duty, heavy duty, diesel, automobile, truck, etc)?

     	Yes  	No

Comments:


2.   Were methods included for estimating traffic parameters?

     	Yes  	No

Comments:


3.   Were references included for traffic parameters?

     	Yes  	No

Comments:


4.   Does the plan include emissions from railroads and aircraft?

     	Yes  	No

Comments:


F.   AREA SOURCES

/.   Does the plan describe how area sources that overlap with the geographical boundaries of the
     nonattainment area were included in the emissions inventory?

         Yes       No
Comments:


G.  EMISSIONS PROJECTIONS

1.  Were population projections consistent with other growth indicators (housing, VMTs,  etc.)?

    	Yes  	No

Comments:


2.  Did the inventory specify how growth is incorporated into the baseline projection inventory?

    	Yes  	No

Comments:
                                               A-5

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3.  Did mobile source projections factor in more stringent emission controls for automobiles produced in the
    future?

         Yes      No
Comments:


H.  RACT/RACM AND CONTROL STRATEGIES

1.  Did the plan describe the control measures to be implemented?

    	Yes  	No

Comments:


2.  Did the plan describe the implementation schedule?

    	Yes  	No

Comments:


3.  Was the enforcement agency responsible for control measures identified?

    	Yes 	No

Comments:


4.  Will all currently available control measures be implemented by the appropriate deadlines?

    	Yes 	No

Comments:


5.  Did the plan describe the methods used to calculate control effectiveness?

    	Yes  	No

Comments:


6.   Were alternate control strategies considered?

    	Yes  	No

Comments:
                                                A-6

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7.  Did the plan describe maintenance procedures for control techniques?




    	Yes   	No




Comments:







I.  IMPLEMENTATION SCHEDULE




1.  Did the plan include a timetable for the implementation of RACT/RACM?




    	Yes   	No




Comments:







2.  Will the implementation schedule be achieved?




    	Yes  	No




Comments:







3.  Did the plan identify the implementation enforcement agency?




    	Yes   	No




Comments:







J.  RELATIONSHIP TO OTHER PROGRAMS




1.  Did the plan identify sources operating with Part D (NSR) permits?




    	Yes   	No




Comments:




2.  Were offset requirements defined for new sources?




    	Yes   	No




Comments:







3.  Were any preconstruction bans in effect?




    	Yes   	No




Comments:
                                              A-7

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4.  Did the plan include any additional State or local standards?

    	Yes   	No

Comments:


K.  REPORTING REQUIREMENTS

/.  Did the plan report emission data using the new permitting requirements of the amendments to the
    CAA?

    	Yes   	No

Comments:

2.  Were reporting mechanisms identified for attainment failure?

    	Yes   	No

Comments:


3. Were record-keeping procedures described?

    	Yes   	No

Comments:
                                              A-8

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