& EPA
        United States
        Environmental Protection
        Agency
           Office of Air Quality
           Planning and Standards
           Research Triangle Park, NC 27711
EPA-452/R-92-005
October 1992
        Air
GUIDANCE ON THE ADJUSTED
BASE YEAR EMISSIONS
INVENTORY AND THE
1996 TARGET FOR THE
15 PERCENT
RATE OF PROGRESS PLANS

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  Guidance  on  the Adjusted Base
Year Emissions Inventory  and  the
 1996 Target  for  the  15 Percent
      Rate-of-Progress Plans
 Ozone/Carbon Monoxide Programs Branch
  U.S.  Environmental Protection Agency
   Office of Air  Quality Planning and
               Standards
   Research Triangle Park,  NC  27*711
             U S Environmental Protection Agency
             Region 5, Library (P1.12J)
             77 West Jackwn Boulevard,
             Chicago, ti 60604-3590

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  Guidance  on the Adjusted  Base
Year  Emissions  Inventory and the
 1996 Target  for the  15  Percent
      Rate-of-Progress  Plans
 Ozone/Carbon Monoxide Programs Branch
  U.S. Environmental Protection Agency
   Office of Air Quality Planning and
              Standards
   Research Triangle Park, NC  27711

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                        TABLE OF CONTENTS
                                                              Page

ACKNOWLEDGEMENTS   	    V

LIST OF TABLES	vi

LIST OF FIGURES	vii

ACRONYMS AND ABBREVIATIONS	viii

EXECUTIVE SUMMARY  	    1

1.0  INTRODUCTION  	    5
     1 .1  Purpose	    6
     1 .2  Background	    7
     1.3  Organization of Report   	    8

2.0  CALCULATION OF THE 1996 TARGET	    9
     2.1  Calculation  of the 1990  Adjusted  Base  Year
          Inventory  	    9
          Mobile Source Adjustments  	   12
          RACT Rule Corrections	14
          I/M Program  Corrections  	   15
     2.2  1996 Target  Level of'Emissions   	   15
     2.3  Requirements of Section  1 82 (b) (1) (A) (ii)   	17
     2.4  Emissions Factor Adjustments   	   17

•3.0  RATE-OF-PROGRESS  PLAN ELEMENTS	19
     3.1  Base Year Inventory	,  .   20
          Guidance Documents for Preparing  Base  Year
               Inventory	20
          Documentation Requirements of Base  Year  Inventory  .   22
     3.2  Additional Rate-of-Progress Plan  Elements  	   22
          1990 Rate-of-Progress Base Year Inventory	23
          1990 Adjusted Base Year  Inventory	23
          Required 15  Percent Reductions   	   24
          Total  Expected Reductions  	   24
          Target Level for 1996	25
          Economic Activity and Growth:  Determinants  and
               Indicators	25
          Control  Measures/Factors  .  .  	   26
     3.3  Attainment Demonstration  	   28

4.0  CREDITABILITY OF  EMISSIONS REDUCTIONS   	   29
     4.1  RACT Programs	30
          RACT Fix-Ups	   30
          RACT Catch-UpS	31
     4.2  Inspection and Maintenance Programs 	   32
     4.3  Preenactment Banked Emissions Reduction  Credits  .  .   32
     4.4  Maximum  Achievable Control Technology  (MACT)
          Standards	34
          General  Requirements   	   34
          Early  Reductions Program  	   34
     4.5  Rule Effectiveness Improvements  	   35

                              - iii

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 5.0   PREVIEW OF  THE  DEVELOPMENT  OF  EMISSIONS  PROJECTIONS,
      CONTROL STRATEGY,  AND  1996  MILESTONE  COMPLIANCE
      DEMONSTRATION  	   37

•REFERENCES	39

 APPENDIX A:   DEFINITION OF  TERMS  	  A-1

 APPENDIX B:   CALCULATION OF EMISSIONS  REDUCTIONS FROM RACT
      RULE CORRECTIONS	B-1

 APPENDIX C:   CALCULATION OF EMISSIONS  REDUCTIONS FROM I/M
      PROGRAM CORRECTIONS  	  C-1
                                IV

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                        ACKNOWLEDGEMENTS

     This report was prepared by Andrew D. Bollman and Randy
Strait of E.H. Pechan and Associates, Inc. of Durham, North
Carolina.  The work was conducted under EPA Contract No. 68-DO-
0120, Work Assignment No.  2-43; with contributions from the
following EPA Offices:  Ozone/Carbon Monoxide Programs Branch and
Emission Inventory Branch of the Office of Air Quality Planning
and Standards, and the Emission Planning and Strategies Division
of the Office of Mobile Sources.
                                v

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                          LIST OF TABLES

•Number                                                        Page

1.    PROJECTION AND CONTROL FACTOR FORMATS  	  27
A-1.  MAJOR SOURCE THRESHOLDS AND MINIMUM EMISSIONS OFFSET
      RATIO REQUIREMENTS FOR OZONE NONATTAINMENT AREA
      CLASSIFICATIONS  	 A-3
C-1.  INSPECTION AND MAINTENANCE (I/M)  PROGRAM INPUTS  .  . .  . C-1
                                VI

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                         LIST OF FIGURES

Number                                                       Page

Figure 1.  Flow chart for rate-of-progress calculations.  .  .   10
Figure 2.  Flow chart for example rate-of-progress
     calculations	16

Figure 3.  Example of use of preenactment banked emissions
     credits	33
                               VII

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                    ACRONYMS AND ABBREVIATIONS
Act
AFS
AIRS
AMS
BEA
CAAA
CO
•CTG
EKMA
EPA
FIPS
FMVCP
FR
gal
I/M
Ib
MACT
NAAQS
NOX
OCS
psi
RACT
RFP
ROM
RVP
SIP
SSCD
tpy
UAM
VMT
VOC
Clean Air Act
AIRS Facility Subsystem
Aerometric Information Retrieval System
AIRS Area and Mobile Source Subsystem
Bureau of Economic Analysis
1990 Clean Air Act Amendments
Carbon Monoxide
Control Technique Guideline
Empirical Kinetic Modeling Approach
U.S. Environmental Protection Agency
Federal Information Processing Standards
Federal Motor Vehicle Control Program
Federal Register
gallon(s)
Inspection and Maintenance
pound(s)
Maximum Achievable Control Technology
National Ambient Air Quality Standard(s)
Nitrogen Oxides
Outer Continental Shelf
pounds per square inch
Reasonably Available Control Technology
Reasonable Further Progress
Regional Oxidant Modeling
Reid Vapor Pressure
State Implementation Plan
Stationary Source Compliance Division
tons per year
Urban Airshed Model
vehicle miles traveled
Volatile Organic Compound(s)
                               VI11

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                         EXECUTIVE  SUMMARY

      Section  182(b)(1)  of  the  Clean  Air  Act  (Act)  Amendments of
 1990  (CAAA) requires  all ozone nonattainment  areas classified as
 moderate  and  above  to submit a State implementation plan (SIP)
 revision  by November  15, 1993,  which describes,  in part,  how the
 areas will achieve  an actual emissions reduction of at least
 15  percent during the first 6  years  after  enactment of the CAAA
 (November 15,  1996).   The  portion  of the SIP  revision that
 illustrates the  plan  for the achievement of this emissions
 reduction is  subsequently  defined  in this  document as the "rate-
 of-progress plan."

      The  focus of this guidance document is on the requirements
 due November  1992 relative to  the  rate-of-progress plan,
 including adjustments that must be made  to the base year (1990)
 emissions inventories.   This document clarifies guidance provided
 in  an August  7,  1992  memorandum from Mr. J. David Mobley,  Chief,
 Emissions Inventory Branch, to U.S.  Environmental Protection
 Agency (EPA)  Regional Chiefs,  regarding  "November 15, 1992,
 Deliverables  for RFP  and Modeling  Emission Inventories."

      Section  182(a)(1)  of  the  CAAA requires all nonattainment
•areas to  submit  within 2 years of  enactment  (November 15,  1992),
 a comprehensive,  accurate, and current inventory of ozone season
 typical weekday  emissions  from all sources.   State agencies are
 responsible for  the development of this  "base year inventory."
 Draft base year  inventories were scheduled to be submitted to EPA
 during the period of  January'1  to  May 1, 1992.   Final base year
 inventories,  which  incorporate comments  from  EPA's review of the •
 draft inventory,  and  draft adjusted  base year inventories,
 described in  this guidance document,  are due  no later than
 November  15,  1992.

      This document  assists States  in determining the 1996 target
- level of  emissions  under the rate-of-progress plan requirement
 for moderate  and above ozone nonattainment areas.   States will
 use this  target  emissions  level in determining what strategies
 will  be necessary to  control emissions so  that the nonattainment
 area  will comply with the  15 percent volatile organic compounds
 CVOC)  emissions  reduction  requirement.   This  document uses an
 example 1996  target emissions  calculation  to  describe the
 procedures that  States should  follow to  calculate the 1996 target
 level.  It also  describes  EPA's documentation requirements for
 the November  1992 submittals relative to the  rate-of-progress
.plan.  The schedule for rate-of-progress plan deliverables is
 listed below:

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     November  1992:
           •    Final  1 990 base year inventory..1
           •    1990 rate-of-progress base year inventory  (limited
               to nonattainment area and excluding biogenic
               emissions).2
               Initial 1990 adjusted base year inventory.3
               Required  15 percent reductions.3
               Total  expected reductions by  1996.3
               Target level for 1996.3
               Growth factors for developing projected  rate-of-
               progress  and attainment modeling inventories.3
               CAAA mandated control measures and their
               associated control efficiencies.3
 1 States must allow for public review of the base year inventories
 if  they are  to be used in a regulatory exercise such as  rate-of-
 progress plans, attainment demonstrations, or maintenance  plans.
 While  1990 base year inventories must be submitted  to EPA  by
 November 15,  1992, EPA will allow the public review process  to
 occur  after  this date  (because of the length of time generally
 required for scheduling and completing the public review
 process).  If public review is held after the November  15
 submittal, then prior to November 15, 1993, and prior to
 application  in any regulatory activities, the inventory  must be
 revised to reflect responses to public review comments.

 2The rate-of-progress inventory is a subset of the  final 1990
 base year inventory and should be identified within the  base year
 inventory documentation.  This means that within the base  year
 inventory submittal, emissions from anthropogenic sources  (i.e.,
.excluding biogenics) within the nonattainment area  (excluding
 sources within the 25-mile buffer zone and sources  in a  model
 domain but outside of the nonattainment area) should, be
 identified.   This can be accomplished by summarizing emissions in
 the inventory for nonattainment area anthropogenic  sources and
 then summarizing emissions for all other sources.   Thus, the
 rate-of-progress inventory should be submitted as part of  the
 1990 base year inventory package due by November 15, 1992.

 3The EPA stated in an August 7, 1992 memorandum from Mr. J.  David
 Mobley, Chief, Emission Inventory Branch, to EPA Regional  Office
 Chiefs, regarding "November 15, 1992, Deliverables  for RFP and
 Modeling Emission Inventories," that these items  (initial  1990
 adjusted base year inventory through remaining items under
 November  1992) are required by November 15, 1992.   If, however,  a
 State  will be submitting a full draft 15 percent rate-of-progress
 plan for public review in early 1993  (i.e., no later than  March
 1993), they  may wait and submit the draft plan to EPA at the
 beginning of the public review period rather than submitting
 these  items  in November 1992.  Please note, however, that  for
 areas  involved in regional oxidant modeling  (ROM) exercises,
 growth and control factors need to be submitted to  EPA by
 November  15,  1992.

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     May  1993:
           •    Draft  1996 projected emissions  inventory with
               controls.

     November  1993:
           •    Fully  adopted rate-of-progress  plan, .including
               attainment demonstration  for moderate  areas  not
               using  the urban airshed model  (UAM).

     Various reductions will result from implementation of  the
 1990 CAAA.  Some of these reductions  are creditable toward  the
 15 percent VOC emissions reduction requirements  while others are
 not creditable.  This document incorporates a  review  of the
 creditability  of emissions  control programs mentioned in the
 CAAA.  This discussion assists States in planning  a control
•strategy  to meet the  1996 target  emissions level.  All real,
 permanent, and enforceable  post-1990  VOC emissions reductions are
 creditable toward  the 15 percent  requirement except for
 reductions resulting  from the following:

     1.    The  Federal motor vehicle control program  (FMVCP)
           tailpipe or evaporative standards promulgated prior to
           1990.

     2.    Federal  regulations specifying Reid  vapor pressure
           (RVP) limits for  nonattainment areas (55 FR 23666,  June
           11,  1990).

     3.    State regulations required  under section 182(a)(2)(A)
           to correct  deficiencies in  existing  reasonably
           available control technology  (RACT)  rules.

     4.    State regulations required  under section 182(a)(2)(B)
           to establish an inspection  and maintenance  (I/M)
           program  or  correct deficiencies in existing I/M
           programs.

     Finally,  this document provides  a brief preview  of the
 development of emissions projections  and control strategies,
 along  with a discussion of  the 1996 milestone  compliance
 demonstration. The EPA is  not requiring that  a  complete draft
 control strategy be included in  the rate-of-progress  plan until
 May  1993.  However, CAAA mandated control measures and their
 associated control efficiencies  are required in  November 1992;
 additional control measures to meet the  15 percent emissions
 reduction requirement are encouraged, but not  required for  the
 November  1992  submittal.  Guidance for the May and November 1993
 submittals will be released in the fall  of 1992.

     The  EPA may require States  to make  corrections to the  final
 1990 base year, 1990  rate-of-progress base year, initial 1990
 adjusted  base  year inventories,  as well  as the 1996 target  level
 of emissions.  These  corrections  will only be  required if
 emissions factors  or  methodologies change significantly,  and
 these  changes  occur before  such  time  that it is  impossible  for

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States to make adjustments to their 15 percent emissions
reduction calculations and associated control strategies.  For
example, a revised MOBILE model (MOBILES.0)  is due for release
this fall.  Its use will not be required in the November 1992
submittal, but will be required in the November 1993 submittal.

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1 .0  INTRODUCTION

     Section 182(b)(1) of the CAAA requires all ozone
nonattainment areas classified as moderate and above to submit a
SIP revision by November 15, 1993, which describes, in part, how
the areas will achieve an actual emissions reduction of at least
15 percent during the first 6 years after enactment of the CAAA
(November 15, 1996).   Emissions and emissions reductions shall be
calculated on a typical weekday basis for the "peak" 3-month
ozone period (generally June through August).  The 15 percent VOC
emissions reduction required by November 15, 1996 is defined
within this document as "rate of progress."4  Furthermore,  the
portion of the SIP revision that illustrates the plan for the
achievement of the emissions reduction is subsequently defined in
this document as the "rate-of-progress plan."

     Additionally, States with intrastate moderate ozone
nonattainment areas will generally be required to submit
attainment demonstrations with their SIP revisions due by
November 15, 1993  (such areas choosing to use the UAM to prepare
their attainment demonstrations will be allowed to submit
attainment demonstrations by November 15, 1994).  States choosing
to run UAM for their intrastate moderate areas must submit their
15 percent rate-of-progress plan and a committal SIP addressing
the attainment demonstration.  The committal SIP subject to a
section 110(k)(4) approval would include, at a minimum, evidence
that grid modeling is well under way and a commitment, with
schedule, to complete the modeling and submit it as a SIP
revision by November 1994.  The completed attainment
demonstration would include any additional controls needed for
attainment.

     It.is important to note that section 182(b)(1) also requires
the SIP for' moderate areas to provide for reductions in VOC and
nitrogen oxide (NOX)  emissions "as necessary to attain the
national primary ambient air quality standard for ozone" by
4The EPA recognizes that the CAAA term,  both the 15 percent VOC
emissions reduction requirement of section 182(b)(1) and the
section 182(c)(2)(B) requirement for 3 percent per year VOC
emissions reductions averaged over each consecutive 3-year period
from November 15, 1996 until the attainment date, as reasonable
further progress requirements.  However, because the CAAA require
SIP revisions for the 15 percent reduction to be submitted in
1993 and SIP revisions for the 3 percent per year reductions to
be submitted in 1994, EPA believes that it would be clearer,
within the context of both the 15 percent rate-of-progress plan
and the post-1996 rate-of-progress plan guidance documents that
EPA is producing, to create distinct labels for these two
seemingly similar reductions.  The 1994 SIP revisions describing
the requirement for 3 percent VOC emissions reductions averaged
over each consecutive 3-year period from November 15, 1996 until
the attainment date, constitute the post-1996 rate-of-progress
plan.

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 November  15,  1996.   This  requirement can be met  through  the  use
 of  EPA-approved  modeling  techniques and the adoption  of  any
 additional  control measures beyond those needed  to meet  the
 15  percent  emissions reduction  requirements.

      Section  182(c)(2)  requires all ozone nonattainment  areas
 classified  as serious and above to submit a SIP  revision by
'November  15,  1994 which describes, in part, how  each  area will
 achieve additional VOC emissions  reductions of 3 percent per year
 averaged  over each consecutive  3-year period  from November 15,
 1996  until  the area's attainment  date.  It is important  to note
 that  section  182(c)(2)(C)  allows  for actual NOX  emissions
 reductions  (exceeding growth) that occur after the base  year of
 1990  to be  used  to meet post-1996 emissions reduction
 requirements  for ozone nonattainment areas classified as serious
 and above,  provided  that  such NOX reductions  meet the criteria
 outlined  in forthcoming substitution guidance.   The portion  of
 the SIP revision (due in  1994)  that illustrates  the plan for the
 achievement of these post-1996  reductions in  VOC or NOX  is
 subsequently  defined in this document as the  "post-1996  rate-of-
 progress  plan."  This plan must also contain  an  attainment
 demonstration based  on photochemical grid modeling.   The EPA will
 distribute  a  separate guidance  document on the development of the
 post-1996 rate-of-progress plan in early 1993,

      Demonstrating achievement  of the 15 percent VOC  emissions
 reductions  by November 15, 1996,  and then subsequently
 demonstrating achievement of the  3 percent per year VOC  emissions
 reductions  averaged  over  each consecutive 3-year period  from
'November  15,  1996 until the attainment date,  are termed  milestone
 demonstrations.  Achievement of the milestones must be
 demonstrated  within  90 days of  the milestone  date (i.e., the
 15  percent  VOC emissions  reductions must be demonstrated by
 February  13,  1997).   Rules regarding the development  of  the
 milestone demonstrations  will be  promulgated  in  the summer of
 1993  and  will address the timing  problem of developing a full
 emissions inventory  to meet the milestone demonstration
 requirement.

 1.1  Purpose

      The  purpose of  this  document is to provide  guidance on  the
 calculation and  presentation of the adjusted  base year inventory
 and the  1996  target  level of emissions.  The  1996 target
 emissions "level  facilitates planning for the  15  percent  VOC
 emissions reduction  requirement.  This guidance  document alerts
 the reader  to special circumstances regarding emissions
 inventories and  emissions estimates that should  be considered
 during the  development of the rate-of-progress plan,  including
 the procedures to follow  in adjusting the 1990 base year
 inventory to  calculate the 1996 target level  of  emissions.   It
•also  provides information on the  creditability of emissions
 reductions  for various control  programs.  This document  assists
 States in preparing  the required  information  in  the proper

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States in preparing the required information in the proper
format.  Finally, this guidance presents an example 1996 target
emissions calculation.

     It is important to note that the scope of this document
comprises the preparation of the November 1992 rate-of-progress
plan deliverables.  Therefore, it does not discuss the May and
November 1993 submittals that involve the calculation of the
projected 1996 inventory and development of the control strategy.
A separate guidance document entitled, "Growth Factors,
Projections, and Control Strategies," will discuss these topics
as they relate to the 1993 submittals.  The EPA will publish the
requirements for the 1996 milestone demonstration in a rulemaking
expected in the summer of 1993.

     This document addresses many programs and procedures that
are more fully addressed in other guidance documents.  This
guidance does not supersede these other guidance documents;
rather, it intends to pull together the relative material
pertaining to the development of the rate-of-progress plan.

1.2  Background

     Facilities, States, and the EPA currently estimate emissions
for various purposes.  Under the CAAA, facilities have new
requirements in terms of permits, annual emissions statements,
and compliance certifications.  State agencies are currently
responsible for the production of a base year emissions
inventory, periodic inventories, and annual aerometric
information retrieval system  (AIRS) facility subsystem (AFS)
inventories.  The EPA develops and utilizes emissions estimates
and emissions inventories in virtually all of their air programs.
The focal point for this guidance document is adjusting the 1990
base year inventory for the rate-of-progress SIP revision.

     The 1990 base year- inventory emissions are reported on an
annual and seasonal basis.  For determination of the 15 percent
VOC emissions reduction, emissions are based on typical ozone
season weekday emissions.  For the base year inventory, these
emissions are measured for a typical weekday during the 1990 peak
ozone season.  The peak ozone season is the contiguous 3-month
period for which the highest ozone exceedance days have occurred
in the previous 3 to 4 years.  The EPA's focus on typical ozone
season weekday VOC emissions  (an interpretation of the definition
in section 182(b)(l)(B) of baseline actual emissions during the
"calendar year" of enactment) is consistent with prior EPA
guidance.  This stems from the fact that the ozone national
ambient air quality standard  (NAAQS) is an hourly standard that
is generally violated during ozone season weekdays when
conditions are conducive for ozone formation.  These ozone
seasons are typically the summer months.

     With the 15 percent VOC emissions reduction, moderate
nonattainment areas are generally expected to be able to attain
the ozone NAAQS within the applicable timeframe.  Therefore, the

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base program that all areas classified as moderate and above
nonattainment must meet is the 15 percent rate-of-progress
reduction.  In cases where modeling shows VOC emissions
reductions greater than 15 percent and/or NOX  reductions  are
necessary to attain the standard, additional emissions reductions
will be required on a schedule that is sufficient to meet the
attainment deadline.  Section 182(c)(2)(C) allows for actual NOX
emissions reductions (exceeding growth) that occur after the base
year of 1990 to be used to meet post-1996 emissions reduction
requirements for ozone nonattainment areas classified as serious
and above.  Therefore,  it is recommended that State agencies
track the actual NOX emissions reductions  occurring  between 1990
and 1996.  More specific guidance regarding NOX  substitutions is
currently under development within the EPA.

1.3  Organization of Report

     The organization of this report is as follows.   Section 2 of
this document provides a sample calculation of the 1996 target
level of emissions.  Section 3 of this document presents the
rate-of-progress plan elements.   This section highlights
information on documenting the adjustments to the 1990 base year
inventory for calculation of the 1996 target level of emissions.
Section 4 of this document discusses the creditability of
emissions reductions from various programs to the 15 percent
requirement.  The final section of this document provides a
preview of the development of emissions projections, the control
strategy, and the milestone demonstration that is due in 1997.
Appendix A of this document provides a list of definitions for
EPA terms used throughout this document.  Appendix B describes
the calculation of emissions reductions from RACT rule
corrections, and Appendix C outlines this procedure for I/M
program corrections.

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 2.0  CALCULATION OF THE  1996  TARGET

     To determine  their  control  strategies  for  achieving the
 required VOC  emissions reductions, States will  need to calculate
 the  1996 target level of emissions—the maximum amount of
 emissions allowed  in 1996 given  the rate-of-progress requirement.
 Figure 1 provides  an overview of how  this target level is
 derived.  Sections 2.1 and 2.2 of this document detail the
 calculation of this target using a hypothetical example.

 2.1  Calculation of the  1990  Adjusted Base  Year Inventory

     The CAAA specify the emissions "baseline"  from which the
'15 percent reduction is  calculated.   This baseline  value is
 termed the 1990 adjusted base year inventory.
 Section 182(b)(1)(B) defines  baseline emissions (for purposes of
 calculating the 15 percent VOC emissions reduction)  as "the total
 amount of actual VOC or  NOX emissions from  all  anthropogenic
 sources in the area during the calendar year of enactment."
 Section 182(b)(1)(D) excludes from the baseline the emissions
 that would be eliminated by FMVCP regulations promulgated by
 January 1, 1990, and RVP regulations  (55 FR 23666,  June 11,
 1990), which  require maximum  RVP limits in  nonattainment areas
 during the peak ozone season.

     The 1990 base year  inventory is  first  adjusted by removing
 all  biogenic  emissions as well as emissions from sources located
 outside of the designated nonattainment boundary (e.g.,  within
 the  modeling  domain).  This inventory, which contains only actual
 anthropogenic emissions  occurring within the designated
 nonattainment boundaries during  the base year,  is termed the
 rate-of-progress base year inventory.  The  adjusted base year
 inventory is  derived from the rate-of-progress  base year
 inventory by  removing the expected FMVCP and RVP reductions from
 the  rate-of-progress base year inventory.   Preenactment banked
'emissions credits  should not  be  included in any of  these
 inventories because they do not  represent actual emissions in
 1990.  The following illustrates the  general procedure for
 determining the 1990 adjusted base year inventory.

 Step 1:   Develop  the 1990 Base  Year  Inventory
           (includes all  emissions within the UAM modeling domain)

           Final 1990  Base Year VOC Emissions Inventory
                       [pounds/day (Ib/day)]

              Point Sources                    1,000
              Area Sources                     2,500
              Mobile Sources                   3,500
              Biogenic Sources               +  5,000
              Total                           12,000

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     As  shown,  the  first  step  records  the  total  1990 base year
 inventory  emissions from  the four  emissions  source types:  point,
 area, mobile,  and biogenic.  The EPA required that the 1990 base
 year inventory be submitted by the States  in draft form by May
.1992, and  in  final  form by November 15,  1992.  However,  EPA is
 allowing additional time  for States to complete  the public
 hearing  process.  In the  example presented above,  the modeling
 domain is  larger than the nonattainment area boundaries so the
 emissions  for the modeling domain  are  presented.   Here,  the total
 point-source  inventory is 1,000 Ib/day.  Area sources account for
 2,500 Ib/day.   The  1990 base year  mobile source  inventory is
 3,500 Ib/day.   In documenting  the  base year  inventory,  States
 must also  specify which sources and emissions are  located within
 the nonattainment area and which are not.  This  is an important
 requirement for documenting the inventory, as ozone inventories
 will include  either point sources  outside  of the nonattainment
 area  (in the  25-mile buffer zone)  or all sources in the UAM
 modeling domain (if UAM modeling is to be  performed).

 Step 2:    Develop 1990 Rate-of-Progress Base Year  Inventory for
           Nonattainment Area

         1990 Rate-of-Progress Base Year Inventory  (Ib/day)

  Point Sources (-200 from outside  nonattainment  area)        800
  Area Sources (-500 from  outside nonattainment area)        2,000
  Mobile  Sources (-500 from outside nonattainment area)    + 3,000
  Total                                                      5,800

     The second step develops  the  1990 rate-of-progress base year
 inventory  for the nonattainment area.   This  inventory comprises
 the anthropogenic stationary  (point and area)  and  mobile sources
 in the nonattainment area; all biogenic emissions  are removed
 from the base year  inventory.   In  the  example presented above,
 200 Ib/day, 500 Ib/day, and 500 Ib/day were  contributed from VOC
 point, area,  and mobile sources, respectively, that are located
 in the modeling domain but outside of  the  nonattainment area
 boundary.   In this  example, there  were no  outer  continental shelf
 (OCS) sources (any  DCS sources that were not located within the
 designated nonattainment  area  would also be  removed from the base
 year inventory).

 Step 3:  Develop Adjusted Base Year Inventory

          -  1990 Adjusted  Base Year Inventory  (Ib/day)

         Point Sources                                800
         Area Sources                               2,000
         Mobile Sources (-FMVCP and RVP — 500)   + 2,500
         Total                                      5,300


     The third step consists of developing the 1990 adjusted base
 year inventory from which the  15 percent reduction is calculated.


                                11

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 First,  the mobile  source portion of  the  1990 rate-of-progress
 base  year inventory calculated in Step 2 must be adjusted as
•required by  section 182(b)(1)(B) and (D) of the CAAA.   This
 adjustment excludes emissions reductions that would occur by  1996
 as  a  result  of  the FMVCP promulgated prior to the  CAAA.   In other
 words,  the adjusted base year inventory  excludes the emissions
 reductions that would occur as a result  of fleet turnover between
 1990  and 1996 even without the CAAA.

      The 1990 adjusted base year inventory must also exclude
 emissions reductions that would result in 1996 from RVP
 regulations  promulgated by November  15,  1990, or required under
 section 211(h)  of  the Act.  The pertinent regulations  (55 FR
 23666,  June  11,  1990) specify maximum RVP's of 9.0 or  7.8 pounds
 per square inch (psi) for each State during the summer months,
 beginning in 1992.  In other words,  the  1990 adjusted  base year
 inventory must  also exclude the emissions reductions that would
 occur as a result  of the difference  between the actual RVP in
 place in 1990 and  the required 9.0 or 7.8 psi RVP  in 1996.
 Deleting these  mobile source emissions reductions  from the
 adjusted inventory decreases the adjusted inventory and thus,
 also  the 15  percent emissions reductions required.  However,
 these mobile source emissions reductions are fully included in
 the total emissions reductions and thus, serve to  reduce the
.total emissions allowed  (as determined by calculating  the target
 level of emissions).

      The net effect of these adjustments is that States are not
 able  to take credit for emissions reductions that  would result
 from  fleet turnover of current standard  cars and trucks,  or from
 already existing Federal fuel regulations.  However, the SIP  can
 take  full credit for the benefits of any new vehicle emissions
 standards, as well as any other new  Federal or State motor
 vehicle or fuel program that will be implemented in the
 nonattainment area, including Tier 1 exhaust standards,  new
 evaporative  emissions standards, reformulated gasoline,  enhanced
 I/M,  California low emissions vehicle program, transportation
 control measures,  etc.

 Mobile Source Adjustments

      The mobile source portion of the adjusted base year
 inventory is calculated using the MOBILE emissions factor model.
 States may use  MOBILE4.1 to come up  with initial estimates of  the
 adjusted base year inventory.  However,  as soon as MOBILES
 becomes available, States should switch  to MOBILES.  MOBILE4.1 or
 MOBILES must be run in calendar year 1990, and again for calendar
'year  1996  (the  1996 run must not include any new CAAA  measures).
 Since MOBILE4.1 does not include new CAAA measures, no change  in
 modeling assumptions other than RVP  is needed for  the  1996 run.
 MOBILES will have  a flag that will run the model using the FMVCP
 that  was in  place  in 1990 for any calendar year.   This flag will
 be  documented in the MOBILES User's  Guide.
                                12

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     The following description uses MOBILE4.1  for  reference.   The
method for calculating  the expected reductions from  the  FMVCP and
RVP is the same using MOBILES except  that  the  flag described
above must be  set to achieve the projected emissions in  1996  in
the absence of any new  CAAA measures.  Users must  still  set the
appropriate RVP as described below.

Actual 1990 emissions =
 [1990 vehicle miles traveled  (VMT)](MOBILE4.1  emissions  factors
     from A);  and

Adjusted 1990  emissions =
 (1990 VMT)(MOBILE4.1 emissions factors from B).

 (A)  MOBILE4.1 run from the 1990 base year inventory.  Emissions
     factors from this  run will be used with actual  1990 VMT  to
     calculate actual 1990 emissions; and

 (B)  MOBILE4.1 run as in the 1990  base year inventory run except
     that:  1) 1996 will be used as the evaluation year  (this
     will change the vehicle mix to account for fleet turnover);
     and 2) the RVP is  set to 9.0  or  7.8 as appropriate  for the
     area.  Emissions factors from this run and 1990 VMT will be
     used to calculate  the adjusted 1990 emissions.

      Expected Reductions from FMVCP  and RVP (1990-1996)  =
         Actual 1990 emissions - Adjusted  1990 emissions

This is the amount that is subtracted from the mobile source
portion in the "rate-of-progress base year inventory" to get  the
mobile source  portion of the adjusted base year inventory
.(step 3).  For Step 5,  this amount will be added to  the  required
 15 percent reductions and other required reductions  to calculate
the total reductions from the 1990 baseline that must occur to
comply with CAAA requirements.

     In the hypothetical example presented in  step 3,  the FMVCP
and RVP regulations represent a decrease in emissions of
500 Ib/day.  This reduction reflects  what  the  1990 emissions
would be if the same fleet that is projected to be operating  in
1996 were operating in  1990.  In addition,  the effects of RVP
regulations, which will result in  lower evaporative  losses, are
factored out,  even though the regulations  were not necessarily in
force in 1990.

     The 1990  motor vehicle baseline  emissions,  after factoring
out the reductions from the effects of the FMVCP and RVP program,
are then added to the 1990 inventory  of nonmotor vehicle
anthropogenic  VOC emissions to calculate the 1990  adjusted base
year inventory.  This composite emissions  inventory,  an
aggregated total, is the inventory used to calculate the required
15 percent emissions reductions.   In  the example presented above,
emissions for  the 1990  adjusted base  year  inventory  total
5,300 Ib/day.
                                13

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 Step  4:  Calculate required  (15 percent) creditable  reductions

              15 percent = 5,300 x 0.15 = 795 Ib/day

      For Step 4,  the adjusted base year  inventory  is multiplied
 by  0.15 to  calculate the  amount of the required  15 percent
 emissions reduction.

 Step  5:  Calculate total  expected reductions by  1996

            Total Expected Reductions by 1996 (Ib/day)

              Required 15 percent                795
              Expected Reductions from           500
              FMVCP and RVP  (1990-1996)
              Corrections to RACT Rules          305
              Corrections to I/M Programs      + 200
              Total                            1,800

      In the fifth step, the  total required  reductions from  the
 1990  rate-of-progress base year inventory are calculated.   The
 total reductions  comprise the reductions necessary to meet  the
 15  percent  requirement  and the expected  reductions from the
 noncreditable programs  (RVP, pre-CAAA FMVCP, RACT  rule
 corrections, and  I/M program corrections).  Corrections to  RACT
.rules and I/M programs  are discussed below.  In  the  above
 example, the emissions  reductions expected  to result from the
 corrections to  RACT rules are 305 Ib/day, and the  emissions
 reductions  expected to  result from corrections to  the I/M program
 are 200 Ib/day.   The total expected  reductions by  1996 from the
 nonattainment area  (i.e., prior to growth)  are 1,800 Ib/day
 (step 5).

 RACT  Rule Corrections

      Section 4.1  of this  document discusses cases  where RACT rule
 corrections do  not directly  result in quantifiable emissions
 reductions. Any  incidental  reductions that occur  in these
 instances may be  handled  as  part of  a rule  effectiveness
 improvement.  Corrections to RACT rules  that may result in
 additional, enforceable,  and quantifiable emissions  reductions
 include situations where  either:

      •   A rule  was missing (i.e.,  a State committed to
          develop a rule  as  part of  its  1977 SIP,  or post-
           1982  SIP, but never carried through on the
          commitment prior to the CAAA).

      •   The limit was wrong.

      •   A capture system is now required.

 Reductions  from these types  of RACT  rule corrections are not
 creditable  toward the 15  percent VOC emissions reduction


                                14

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requirement.   However,  the  amount  of  emissions  reductions from
these  corrections  should be calculated,  as  they are part of the
total  reductions from the 1990  rate-of-progress base year
inventory  that are required by  the CAAA.  Appendix B describes
the methods  for estimating  the  amount of these  noncreditable
emissions  reductions.

I/M Program  Corrections

     Corrections to I/M programs are  necessary  when either:
.(1) the  area's I/M program  does not meet the  reductions  achieved
by EPA's minimum requirements,  or  (2) an area's program  does not
meet the standards of its current  SIP.   The calculation  of the
emissions  reductions associated with  I/M program corrections
requires two MOBILE4.1  runs (or MOBILES  when  it becomes
available).   Appendix C presents the  methods  for calculating the
emissions  reductions from I/M program corrections.

2.2  1996  Target Level of Emissions

     The final step is to calculate the  1996  target level of
emissions  for planning purposes.

Step 6:  Set target level for 1996

     To  calculate  the 1996  target  emissions level,  the total
reductions from Step 5 are  subtracted from  the  1990 rate-of-
progress base year inventory for the  nonattainment area.   The
1996 target  level  of emissions  is  4,000  Ib/day  as shown  below.

     Target  Level    =    Step 2 -  Step 5
                     =    1 990 Rate-of-Progress  Base Year
                          Inventory For Nonattainment Area - Total
                          Reductions
                          5,800  Ib/day -  1,800 Ib/day
                          4,000  Ib/day

Figure 2 provides  an overview of the  steps  followed in
calculating  the example 1996 target level of  emissions.

     It  is important to note that  although  moderate and  higher
nonattainment area classifications are required to provide a
rate-of-progress plan describing how  a 15 percent VOC emissions -
reduction  will be  achieved  between 1990  and 1996,  moderate areas
are not  required to show that they have  met the 15 percent
emissions  reduction requirement.   Instead,  they are required to
show that  they have attained the NAAQS as of  November 15,  1996.

     Moderate areas must, therefore,  plan for and implement a
control  strategy that will  result  in  attainment.   If,  for
example, modeling  for the attainment  demonstration shows  that an
18 percent VOC emissions reduction will  be  necessary for  a
particular moderate area to attain by 1996, then the State should
plan for and include control measures in their  SIP submittal to


                                15

-------

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 reach  this  18  percent  reduction.   These  States  need to track the
 post-implementation emissions  using the  modeled attainment
•percentage  rather  than the 15  percent  rate-of-progress
 requirement.

 2.3  Requirements  of Section 182(b)(1)(A)(ii)

     Nonattainment areas  can achieve less  than  the 15 percent
 required reductions under the  following  restrictive
 circumstances. The State must demonstrate that the area has a
 new source  review  program equivalent to  the requirements in
 extreme  areas  [section 182(e)]/ except that "major source" must
 include  any source that emits,  or  has  the  potential to emit,
 5  tons per  year  (tpy)  of  VOC or NOX.   Additionally, all  major
 sources  of  VOC and NOX (down to 5  tpy) in  the area must  be
 required to have RACT-level controls.  In  light of technological
 achievability, the State's plan must also  include all mobile and
 stationary  source  control measures that  can be  feasibly
 implemented in the area.   In addition, the State must demonstrate
 that the area's plan includes  the  measures that are achieved by
 sources  in  the same source category in nonattainment  areas of the
 next higher classification. More  detailed guidance on this
 showing  will be provided  in forthcoming  EPA guidance  expected in
 the fall of 1992 regarding the development of control strategies
.for the  rate-of-progress  demonstration plan.

 2.4  Emissions Factor  Adjustments

     Emissions factors, as well as inventory calculation
 methodologies, are continually being improved.   If emissions
 factors  or  methodologies  change significantly,  the EPA may advise
 the States  to  correct  the base year emissions inventory to
 reflect  such changes.   The release of  a  revised MOBILE model
 (MOBILES.0)  is pending.  The use of MOBILES.0 is not  required for
 the SIP  submittal  due  in  November  1992.  Any emissions values
 calculated  using MOBILE4.1  will have to  be recalculated before
 submittal of the final rate-of-progress  plan in November 1993.
 If other significant changes occur in  emissions factors or
 methodologies  before which time it is  impossible for  States to
 make adjustments to their 15 percent calculations and associated
 control  strategies, then  EPA may require States to make
 corrections to the base year emissions inventory,  as  well as to
 the adjusted base  year inventory and the 1996 target  level of
 emissions.   Such corrections would be  made prior to the submittal
 of any subsequent  rate-of-progress demonstration.
                                17

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3.0  RATE-OF-PROGRESS PLAN ELEMENTS

     Required submittals for the rate-of-progress plan will be
staggered to allow additional time for the control  strategy
development process.  The dates and specific elements that are
required for these submittals are listed below:


     November 1992:
          •    Final 1990 base year inventory.5
          •    1990 rate-of-progress base year inventory  (limited
               to nonattainment area and excluding  biogenic
               emissions).6
          •    Initial  1990 adjusted base year inventory.7
          •    Required 15 percent reductions.7
5States must allow for public review of the base year inventories
if they are to be used in a regulatory exercise such as  rate-of-
progress plans, attainment demonstrations, or maintenance plans.
While  1990 base year inventories must be  submitted  to EPA by
November 15,  1992, EPA will allow  the public review process to
occur  after this date  (because of  the length of time generally
required for  scheduling and completing the public review
process).  If public review is held after the November  15
submittal, then prior to November  15, 1993, and prior to
application in any regulatory activities, the inventory  must  be
revised to reflect responses to public review comments.

6The rate-of-progress inventory is a subset of the  final 1990
base year inventory and should be  identified within the  base  year
inventory documentation.  This means that within the base year
inventory submittal, emissions from anthropogenic sources  (i.e.,
excluding biogenics) within the nonattainment area  (excluding
sources within the 25-mile buffer  zone and sources  in a  model
domain but outside of the nonattainment area) should be
identified.   This can be accomplished by  summarizing emissions in
the inventory for nonattainment area anthropogenic  sources and
.then summarizing emissions for all other  sources.   Thus, the
rate-of-progress inventory should  be submitted as part of the
1990 base year inventory package due by November 15, 1992.

7The EPA stated in an August 7, 1992 memorandum from Mr. J. David
Mobley, Chief, Emission Inventory  Branch, to EPA Regional Office
Chiefs, regarding "November 15, 1992, Deliverables  for RFP and
Modeling Emission Inventories," that these items  (initial 1990
adjusted base year inventory through remaining items under
November 1992) are required by November 15, 1992.   If, however, a
State  will be submitting a full draft 15  percent rate-of-progress
plan for public review in early 1993  (i.e., no later than March
1993), they may wait and submit the draft plan to EPA at the
beginning of  the public review period rather than submitting
these  items in November 1992.  Please note, however, that for
areas  involved in ROM exercises, growth and control factors need
to be  submitted to EPA by November 15, 1992.

                                19

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           •    Total expected reductions by 1996.7
               Target level for 1996.7
           •    Growth factors for developing projected  rate-of-
               progress and attainment modeling inventories.7
           •    CAAA mandated control measures and their
               associated control efficiencies.7

     May  1993:
           •    Draft 1996 projected emissions inventory with
               controls.

     November  1993:
           •    Fully adopted rate-of-progress plan,  including
               attainment demonstration for moderate areas  not
               using the UAM.

Each of the items required for the November 1992 submittal  are
described in this section.  Subsequent rate-of-progress plan
submittals are discussed briefly in section 5.0 of  this document.
Further details on these elements will be provided  in the
document  entitled, "Growth Factors, Projections, and Control
Strategies," to be issued in the fall of 1992.


3.1  Base Year Inventory

     Section 182(a)(1) requires all nonattainment areas to  submit
a comprehensive, accurate, and current inventory of actual
emissions from all sources by November 15, 1992.  This  inventory
is for calendar year 1990 and is identified as the  base year
inventory.  It includes anthropogenic sources of NOX and carbon
monoxide  (CO)  emissions, as well as anthropogenic and biogenic
sources of VOC.  The base year inventory includes actual VOC,
NOX, and  CO emissions for the area on both an annual basis
 (except for on-road mobile sources and biogenics) and a typical
weekday basis  during the peak ozone season, which is generally
the summer months.  All stationary and mobile sources within the
nonattainment  area, and stationary sources with emissions of
100 tpy or greater of VOC, NOX,  and CO emissions within a 25-mile
wide buffer of the designated nonattainment area, must  be
included  in the compilation.  Including sources within  a 25-mile
buffer is necessary to ensure that all sources capable  of
affecting air  quality within the nonattainment area are
adequately accounted for in modeling demonstrations and strategy
development.   For nonattainment areas that will perform
.photochemical  grid modeling  (e.g., serious and above areas  and
multi-State moderate areas), emissions for the entire modeling
domain are required in the base year inventory.

Guidance  Documents for Preparing Base. Year Inventory

     Guidance  documents are available from EPA that specifically
pertain to the calculation and presentation of the  1990 base year
inventory for  the purpose of ozone nonattainment area SIP


                                20

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development.  Guidance related to the requirements for the 1990
base year inventory is available in the following document:

     •    Emission Inventory Requirements for Ozone State
          Implementation Plans. (See reference 1.)

Guidance specific to inventorying stationary sources is available
in:

     •    Procedures for the Preparation of Emission Inventories
          for Carbon Monoxide and Precursors..of Ozone.  Volume I:
          General Guidance for Stationary Sources.  (See reference
          2.)

For mobile sources the primary guidance documents include:

     •    Procedures for Emission Inventory Preparation.  Volume
          IV; Mobile Sources.  (See reference 3.)

     •    User's Guide to MOBTLE4.1.  (See reference 4.)

     •    VMT Forecasting and Tracking Guidance.  (See reference
          5.)

Guidance specific to inventorying biogenic sources is available
in:

     •    Personal Computer Version of the Biogenic Emissions
          Inventory System  (PC-BEIS) And User's Guide.  (See
          reference 6.)

Other guidance documents related to the 1990 inventory are:

     •    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.  (See reference 7.)

     •    Guidance for the _Preparation of Quality Assurance Plans
          for 03/CO SIP Emission Inventories. (See reference 8.)

          Quality Review Guidelines for 1990 Base Year Emission
          Inventories. (See reference 9.)

     •    Example Documentation Report for 1990 Base Year Ozone
          and Carbon Monoxide State Implementation Plan Emission
          Inventories. (See reference 10.)

          Guidelines for Estimating and Applying Rule
          Effectiveness for Ozone/CO State Implementation Plans.
          (See reference 11.)
                                21

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Documentation Requirements of Base Year Inventory

     States must provide their base year inventory information in
both written and computerized formats.  Adequate documentation on
the source of the emissions estimates is required in the
submission of the final base year inventory.  This documentation
will facilitate the milestone compliance determination and any
necessary emissions estimate recalculations during the
implementation of the SIP.  Requirements and guidance for
documentation of the base year inventory are presented in
Emission Inventory Requirements for Ozone State Implementation
Plans (EPA-450/4-91-010) and Example Documentation Report for
1990 Base Year Ozone and Carbon Monoxide State Implementation
Plan Emission Inventories (EPA 450/4-92-007).

     The written presentation of emissions inventory information
has to be extensive enough for EPA to reproduce the emissions
inventory elements that are submitted.  The EPA's primary concern
is that all inventory elements address the crucial elements
inherent in a good inventory and provide summary data and
documentation that allow the quality of the inventory effort to
be effectively judged.  Therefore, the emphasis is on the types
of data that need to be reported and not the specific format in
which they are reported.  Inventories not meeting the minimum
data reporting and documentation standards established in these
documents will be deemed unacceptable and returned to the States
for modification before any further technical quality review will
be performed.

     Adequate documentation includes all of the information that
is necessary to understand how an emissions estimate was made.
This level of documentation will allow EPA and the States to
determine what the effects would be if some of the data were
revised.  For example, to understand the effect of changes in
emissions factors, the State needs to document where the factors
were employed and the supporting data (such as activity data)
that were used in the emissions estimation process.

     Some activity data may be revised during the period between
submission of the rate-of-progress plan and the milestone
demonstration (this could include preliminary population data
obtained before the 1990 census data were finalized or VMT
estimates that were later revised using a more sophisticated
model).  Therefore, States must document the source of the data
as well as the date or version of the data  (and whether the data
are draft or final estimates).

3.2  Additional Rate-of-Progress Plan Elements

     Rate-of-progress plan requirements under the CAAA result in
the need to develop two inventories in addition to the base year
inventory:  the rate-of-progress base year inventory and the
adjusted base year inventory.  The rate-of-progress base year
inventory is an inventory of actual anthropogenic 1990 emissions
for the nonattainment area that is used to track the progress of

                                22

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the  15 percent reduction plan.  The  1990 adjusted base  year
inventory, which  is also developed for  the  rate-of-progress  plan,
does not contain  the  expected emissions reductions  from the  FMVCP
and RVP program from  the 1990 rate-of-progress base year
inventory.  The required 15 percent  reductions are  calculated
from this adjusted base year inventory  and  not the  rate-of-
progress base year inventory, thus lowering the  States'  emissions
reduction burden.

1990 Rate-of-Progress Base Year Inventory

     .The 1990 rate-of-progress base  year inventory  accounts  for
the  total anthropogenic VOC, CO,  and NOX emissions  in the
'nonattainment area.   The rate-of-progress base year inventory
differs from the  1990 base year inventory in that the rate-of-
progress base year inventory does not include biogenic  source
emissions nor emissions from sources located outside of the
nonattainment area, while  the base year inventory includes these
emissions  (e.g.,  for  point, area, and mobile sources outside of
the  nonattainment area but within the UAM domain).   States should
document which sources and emissions are located within the
nonattainment area as well as which  are located  outside of the
nonattainment area.   Also, the total biogenic emissions, which
are  also removed  from the  base year  inventory, should be listed.
Emissions for anthropogenic sources  within  the nonattainment area
can  be distinguished  in the AIRS  data set by using  the
appropriate retrieval criteria.   The rate-of-progress base year
inventory facilitates the  calculation of the adjusted base year
inventory.

1990 Adjusted Base Year Inventory

     The  1990 adjusted base year  inventory  is the starting point
for  calculating the required 15 percent reductions,  and also the
first step in calculating  the total  expected reductions by 1996
•and  the 1996 target level  of emissions. The 1990 adjusted base
year inventory does not contain the  expected FMVCP  (in  effect as
of November 15, 1990)  and  RVP program emissions  reductions from
the  1990 rate-of-progress  base year  inventory.   This adjustment
lessens the States' emissions reduction burden,  because the
baseline emissions total from which  the required 15 percent
reduction is calculated has been  lowered.

     Documentation of the  adjusted base year inventory  will  take
two  distinct forms.   The written  documentation must include  the
expected emissions reductions from the  FMVCP and RVP program, as
well as both the  actual 1990 motor vehicle  emissions using 1990
VMT  and MOBILE emissions factors, and the adjusted  emissions
using 1990 VMT and the MOBILE emissions factors  in  calendar  year
1996 with the appropriate  RVP for the nonattainment area as
mandated by EPA.  (See reference 12.)  States must provide EPA
with information  on how the MOBILE model was run in calculating
the  expected emissions reductions from  the  FMVCP and RVP program.
Section 2.1 of this document provides a description of  how the
reductions from these programs are calculated.

                              - 23

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      For  purposes  of  the AIRS Area  and Mobile  Source  Subsystem
 (AMS)  adjusted base year submittal,  States must provide  the RVP
 inputs as required under the CAAA for the nonattainment  area,  and
 run  the MOBILE model  with a 1996 vehicle mix  (the  1990 base year
 inventory submittal will contain the actual 1990 motor vehicle
'emissions).   Because  the calculation of the FMVCP  and RVP program
 emissions reductions  requires two separate runs of the MOBILE
 model (see section 2.1 of this document for details), States will
 not  submit the emissions reductions from these programs  directly
 into AIRS.

      Other requirements for documentation and  submittal  of the
 adjusted  base year inventory to AIRS are the same  as  those for
 the  1990  base year inventory.  States should realize  that there
 will be no submittal  of an "adjusted" point-source inventory for
 AFS  because the  point-source emissions are not altered in the
 calculation of the adjusted inventory from the rate-of-progress
 base year inventory.  The point-source emissions for  both the
 rate-of-progress and  adjusted base  year inventories can,
 therefore,  be directly retrieved from the 1990 base year
 inventory.   Stationary area-source  emissions are not  altered
 either.   All adjustments apply to mobile source emissions.   Base
 year and  adjusted  base year point and stationary emissions are
 different because  of  the different  geographic  coverage.   The AIRS
 has  a flag to indicate that the emissions are  within  the
 designated nonattainment area boundaries and,  therefore,  can
 separate  the point and stationary area-source  portions to develop
•portions  of these  two different inventories.

 Required  15 Percent Reductions

      The  required  15  percent reductions represent  the amount of
 creditable emissions  reductions that must be demonstrated in the
 rate-of-progress plan.  The amount  of these required  emissions
 reductions is calculated by multiplying the adjusted  base year  "
 inventory by 0.15.  The results of  the 15 percent  emissions
 reduction calculation can be documented on a single sheet of
 paper as  the "required 15 percent reductions."

 Total Expected Reductions

      In addition to the creditable  15 percent  reductions,  there
 are  other emissions reductions that are required under the CAAA.
 The  "total expected reductions" are the sum of the following:

      •    15 percent  reductions.
      •    Expected reductions from  the FMVCP  (in effect  as of
           November 15, 1990) and RVP program  (1990-1996).
      •    Reductions  from corrections to RACT  rules.
      •    Reductions  from corrections to I/M programs.

 The  expected reductions from the FMVCP and RVP program and any
 required  corrections  to RACT rules  and I/M programs,  which are
 calculated based on the methods described in section  2.1  of this
 document,  should be documented on paper showing each  step,

                                24

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discussing any assumptions made,  and  stating  the  origin of the
numbers used  in  the  calculations.

Target Level  for 1996

     The  target  level  of  emissions  for  1996 is  the  maximum amount
of  1996 anthropogenic  emissions within  the nonattainment area
that are  permitted to  occur  while complying with  the  rate-of-
progress  requirements.  The  emissions level is  determined by
subtracting the  total  expected reductions from  the  1990 rate-of-
progress  base year inventory.  The  EPA  expects  the  States to
document  the  target  emissions level for 1996  as well  as the
calculations  made in determining  the  target.  In  order  to develop
control measures in  time  to  meet  the  required reductions by 1996,
'States should submit their 1996 target  level  of emissions to EPA
by  November 1992.

     The  following section provides background  on growth factors
and discusses how the  growth factors  that are required  with the
November  1992 SIP submittal  should  be determined  and  documented.

Economic  Activity and  Growth:  Determinants and Indicators

     Economic activity is a  factor  influencing  the  level and form
of  anthropogenic pollution.  Economic activity  levels are
determined by the forces  of  supply  and  demand.  But emissions are
determined by specific production processes  (e.g.,  xx printing or
yy  printing), inputs to those processes (e.g.,  low  solvent versus
...), and the levels of output.   With no change in  the
utilization of those processes, no  additional processes,  and no
change in quality or quantity of  inputs to those  processes,  the
relationship  of  output to emissions seen in the past  should be
projected to  occur in  the future.   However, if  utilization rates
change, new processes  are adopted,  or there are input changes,
the relationship between  output level and emissions seen in the
past may  not  be  an appropriate assumption for projecting future
• emissions.

     Note that growth  factors are not included  in the
calculations  of  the  1990  adjusted base  year inventory or the 1996
target.   Growth  factors are  needed, however,  for  the  15 percent
demonstration as part  of  the rate-of-progress plan  that is due on
November  15,  1993 for  all moderate  and  above  nonattainment areas.
Growth factors are also needed for  the  attainment demonstration
that is due on November 15,  1993  for  moderate ozone nonattainment
areas using empirical  kinetic modeling  approach (EKMA),  and on
November  15,  1994 for  moderate ozone  nonattainment  areas using
UAM and all serious  and above ozone nonattainment areas.   States
should include the draft  rate-of-progress growth  factors in both
computer  and  written formats to EPA by  November 15, 1992.   Two
sets of growth factors  should be  provided.  One set is  used to
project the growth between 1990 and 1996 for  rate-of-progress
plan purposes, and the  other set  is used to project growth up
through the year of  attainment for  the  attainment demonstration
for modeling  purposes.  These sets  are  basically  the  same for

                                25

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moderate areas, which must demonstrate attainment by  1996.   The
computer format for the growth factor submittal is presented in
Table  1.  Other information that should be included with  the list
of growth factors includes:  State ID, county ID, zone  code  (if
the growth factor is to be used for a specific zone within a
county), source category code  (either SIC, AFS source
classification code, or AMS source category code), growth factor
reference  (e.g., Bureau of Economic Analysis  (BEA), plant-
supplied, etc.), and control information discussed below.  Any
information not contained in the spreadsheet file (e.g.,  which
agency submitted the growth information and assumptions made in
preparing the information) should be submitted on paper
accompanying the PC disk).

     Well known sources of information and guidance on  economic
activity projections include the BEA's Regional Projections  to
2040  (see references 13,  14, and 15) and Procedures for Preparing
Emissions Projections  (EPA-450/4-91-019).  (See reference  16.)
There  will be more information forthcoming regarding  economic
activity and growth in a separate volume of the rate-of-progress
plan guidance, entitled "Growth Factors, Projections, and Control
Strategies," to be issued in the fall of 1992.

Control Measures/Factors

     The CAAA mandated controls and their associated  control
efficiencies and rule effectiveness factors for both  the  rate-of-
progress plan and the attainment demonstration are required  in
written and computer diskette  (see Table 1) formats by
November 15, 1992.  The additional controls required  to meet the
15 percent and/or attainment demonstration requirements are
encouraged, but not required for this submittal.

     The control measure information consists primarily of a list
of control measures and associated control efficiencies on a
computer diskette file formatted as depicted in Table 1.  For
-control measures that will be applied during modeling of
attainment, control information must be reported for  the  entire
modeling domain, unless measures are specifically limited to the
nonattainment area.  Supplied control information for attainment
year strategies will be used as input to the upcoming ROM
exercises to improve consistency between ROM and urban  area
modeling results.

     Also included should be the rule penetration (percentage of
rule coverage) associated with new area-source control  measures
and any expected changes  in rule effectiveness for point  or  area
sources.  In addition to  the data on spreadsheet, paper
documentation should be provided describing the control measures,
assumptions made, and any further explanation needed  for  the
information listed on the spreadsheet.
                                26

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3.3  Attainment Demonstration

     States that do not intend to use UAM must submit their
attainment demonstrations as part of the rate-of-progress SIP
revision that is due in November 1993.  Moderate areas are
expected to attain the NAAQS for ozone by November 15, 1996.
These moderate areas may either use UAM or EKMA in their modeling
demonstrations.  Serious and above areas are required to use UAM
in their modeling demonstrations.  Moderate interstate
nonattainment areas are required to use UAM; moderate intrastate
areas have the option of using UAM.  Those moderate areas
electing to use EKMA must submit a SIP revision by November 1993
incorporating a modeling demonstration which shows that the
identified control measures will be sufficient to attain the
NAAQS by November 15, 1996.  If an area elects to use the UAM for
its modeling demonstration, it may apply for a 1-year extension
(to November 1994) for submitting a SIP revision reflecting an
attainment demonstration.  Both UAM and EKMA require emissions
inventories for VOC, NOX,  and CO.
                               28

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 4.0   CREDITABILITY OF  EMISSIONS  REDUCTIONS

      This  section discusses  the  creditability of emissions
 reductions from selected control programs to the 15 percent VOC
 emissions  reduction requirement-   This  presentation is not
 intended to be  comprehensive in  scope;  instead,  it  is included to
'provide preliminary guidance while States begin  developing their
 control strategies.  A future document  in this guidance series,
 "Growth Factors,  Projections,  and Control Strategies," will
 describe details on emissions reductions creditability for
 additional control measures.

      States can credit emissions reductions  toward  the 15 percent
 VOC  emissions reduction requirement only if  the  CAAA do not
 specify that  such emissions  reductions  are not creditable, and
 the  reductions  meet the following requirements.   All emissions
 reductions must be real,  permanent,  and enforceable.  States must
 keep careful  records of all  emissions reductions to ensure that
 the  same reductions are not  "double-counted" or,  more simply,
 used more  than  one time.   In all circumstances,  any real
 emissions  reductions that contribute to attainment  of the
 standard are  creditable in the attainment demonstration.

      Section  182(b)(1)(C)  and section 182(b)(1)(D)  explicitly
 disallow certain reductions  from counting toward the fulfillment
 of the 15  percent reduction  in emissions requirement.  All real,
 permanent, and  enforceable post-1990 VOC emissions  reductions are
 creditable toward the  15 percent requirement except for
•reductions resulting from the following:

      1.    The FMVCP tailpipe or  evaporative  standards promulgated
           prior to 1990.

      2.    Federal regulations on RVP (55 FR  23666,  June 11,
           1990).

      3.    State regulations  required under section  182(a)(2)(A)
           submitted to correct deficiencies  in existing RACT
           rules.

      4.    State regulations  required under section  182(a)(2)(B)
           to  establish an I/M program or correct deficiencies in
           existing I/M programs.

 Remember that the noncreditables identified  in numbers 1  and 2
 above are  not contained in the 1990 adjusted base year inventory
 that is used  to calculate the 15 percent emissions  reduction.
 The  1990 adjusted base year  inventory,  in effect, decreases the
 target level  of emissions (i.e.,  the total level of emissions
 allowed to be produced).   Also,  these programs cannot be used to
.achieve the 15  percent VOC emissions reductions.

      The following paragraphs provide a brief discussion of
 programs that are creditable toward the 15 percent  emissions
 reduction  requirement.   Also briefly discussed are  examples where

                                29

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 reductions  are not  creditable  to  the  15 percent  reduction
 (i.e., RACT rule  and  I/M  fix-ups).  Not discussed  in  this section
 are  the  noncreditable emissions reductions  from  the FMVCP and RVP
 program;  section  2.1  of this document  discusses  these programs
 and  how  the emissions reductions  from  these programs  are
 calculated  and treated for  rate-of-progress purposes.

     The programs described here  do not constitute an exhaustive
 list of  all potential creditable  programs.  Any  other new
 requirements which  generate reductions within  a  nonattainment
 area,  such  as the marine  vessel loading regulations,  are
 creditable  toward the 15  percent.

 4.1  RACT Programs

     Emissions reductions resulting from required  corrections to
 VOC  RACT rules  ("RACT fix-ups") are not creditable toward the
 required 15 percent VOC emissions reduction; any future
 reductions  resulting  from measures not associated  with the
•required corrections  would  be  creditable.   For example,  RACT rule
 corrections involving revision to applicability  thresholds and
 emissions limits, or  additions of missing regulations that were
 required preenactment are not  creditable toward  the 15 percent
 VOC  emissions reduction requirements  (or offsets).  If the State
 revises  the emissions limit or changes the  applicability
 threshold beyond  the  level  required in EPA  guidance  (see
 reference 17), and  these  modifications result  in further
 emissions reductions, these additional reductions  are creditable.
 In this  case, the State would  need to  differentiate,  through
 documentation submitted in  the rate-of-progress  plan,  between
 emissions reductions  that occurred through  a correction  to the
 RACT rule and the additional reductions that resulted from
 extension of the  rule to  sources  of a  lower threshold than
 recommended in EPA's  model  RACT rule  guidance.

 RACT Fix-Ups

     Section 182(b) (1) (D) (iii) specifies that  emissions
 reductions  generated  from corrections  to RACT  rules  (RACT fix-
 ups) required under section 182(a)(2)(A) are not creditable
 toward meeting the  rate-of-progress requirements.  These
.corrections can be  described in two ways:  (1)  where the  emissions
 reductions  from the corrections are difficult  to attribute
 directly to the fix-up  (any emissions  reductions associated with
 these  types of corrections  may generally be considered rule
 effectiveness improvements), and  (2)  where  the resultant decrease
 in emissions is more  clearly attributable to RACT  fix-ups.

     In  the first case, emissions reductions associated  with such
 fix-ups  are difficult to  sort-out from those achieved from rule
 effectiveness and,  therefore,  EPA believes  that  it is appropriate
 to allow such corrections,  in  combination with improved
 compliance  programs that  result in additional, quantifiable,  and
 enforceable emissions reductions, to  count  towards meeting the
 rate-of-progress  requirements  as  part  of a  rule  effectiveness

                                30

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improvement effort.  For example, RACT rule corrections  that  add
the appropriate recordkeeping requirements or  test  methods  do not
directly result in additional emissions  reductions.   However,  the
resulting RACT rules are more enforceable, and the  corrections
make determining compliance an easier task.  The  EPA believes
that in such situations, credit  is  given to the States for
improving the compliance programs,  not for correcting the RACT
rules, although the RACT fix-up  program  was essential to creating
more enforceable rules.

     In the second case, however, corrections  do  result  in
additional, enforceable, and quantifiable emissions reductions.
These corrections, which are not creditable toward  the 15 percent
requirement, include situations  where:

     •    A rule was missing  (i.e., a State committed to
          develop a rule as part of its  1977 SIP, or post-
          1982 SIP, but never carried through  on  the
          commitment prior to the CAAA).

     •    The limit was wrong.

     •    A capture system is now required to  ensure meeting
          the RACT limit.

     Appendix B provides example emissions reduction calculations
for each of these three examples.   These examples are not
intended to be fully inclusive.  States  should evaluate  all RACT
rule corrections to determine if such corrections result in real,
enforceable, and permanent emissions reductions.  If so, such
reductions must be quantified and considered noncreditable  in the
•SIP development process.

RACT Catch-Ups
   *
     Emissions reductions resulting from RACT  catch-ups  are
creditable.  One example of a RACT  catch-up occurs  when  applying
the RACT rules to the  newly designated portions of  a preenactment
nonattainment area not previously subject to the  rules.  For
example, if an area is extended  to  include three  counties that
were not previously part of the  nonattainment  area,  application
of RACT rules to sources in those counties will result in
creditable emissions reductions.14  However,  States that employed
s_tatewide RACT rule implementation  .to avoid the new source
preconstruction monitoring requirements  will not  necessarily
receive credit.  Such  States will only receive credit for the
emissions reductions resulting from the  enhancement of RACT rule
requirements brought about by the CAAA,  extending beyond RACT
rule requirements already on the books,  and implemented  after the
1990 base year.
 14In addition, if the counties were not part of an existing I/M
.program,  extension  of  the  I/M program  to  the  counties  will  result
 in creditable reductions.

                                31

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     Reductions achieved through rules adopted pursuant  to  any
new control technique guideline  (CTG) are creditable only to  the
extent that the reductions were not required by a SIP or Federal
implementation plan developed under the pre-amended Act.  For
example, if a non-CTG rule in a SIP prior to enactment  (or
required to be included in such a SIP) required an
81 percent reduction in VOC emissions and a new CTG for  the same
source category recommends a 90 percent reduction, to the extent
that a specific source achieves the 90 percent reduction, only up
to 9 percent would be creditable.  In addition, if a State  was
required to adopt a RACT rule for a particular source under the
pre-amended Act but failed to do so, adoption of a rule  for that
source would be considered part of the RACT fix-ups.  Therefore,
any reductions achieved by such a rule would not be creditable.

4.2  Inspection and Maintenance Programs

     The I/M Section of the Emission Planning and Strategies
Division of the EPA's Office of Mobile Sources has published  a
draft technical support document that discusses I/M program
performance standards for VOC emissions.  (See reference  18.)
Emissions reductions that result from corrections to I/M programs
that failed to meet this performance standard, or from
corrections to programs that failed to meet a more stringent
standard previously included in the SIP, are not creditable
toward the 15 percent emissions reduction requirement.   Any other
improvements in I/M programs required by the CAAA  (such  as
enhanced I/M) or any improvements that a State chooses to make in
a new SIP are creditable.  In the case where a State has both
made corrections to its SIP according to the EPA's minimum
performance standard, and included additional provisions that go
beyond that standard, the State will model two I/M programs in
the MOBILE model to calculate the creditable reductions; one
representing the program up to the EPA's minimum standard,  and
the other with the State's full I/M program.  The difference
between the two programs' emissions reductions represents the
portion of the total emissions reduction that is creditable '
toward the 15 percent emissions reduction requirement.   Appendix
•C provides details on calculating the emissions reductions  from
I/M program corrections.

4.3  Preenactment Banked Emissions Reduction Credits

     If the State has an emissions credit bank that meets the
EPA's requirements under an earlier policy statement  (see
reference 19), the State is allowed to use its preenactment
banked emissions reduction credits to facilitate the location of
new sources in nonattainment areas during the 1990-1996  period.
However, because these reduction credits represent emissions  that
are not included in the 1990 base year inventory, any additional
emissions that result from the use of banked credits must be
treated as growth in order to ensure that the 15 percent VOC
emissions reduction requirement is achieved.  Also, it is
important to note that the use of preenactment banked emissions


                                32

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credits  must be in accordance with  the offset ratios prescribed
in  the CAAA (e.g., 1.3 to 1 in  severe areas.)

      Figure 3 presents an example of the use of preenactment
banked emissions credits during the 1990-1996 period.  In  this
example,  a new 30 tpy source of VOC emissions wishes to  locate in
a severe nonattainment area, and the State allows the source  to
use available preenactment banked emissions credits.  Because the
source wants to locate in a severe  nonattainment area, 39  tpy of
VOC emissions must be removed from  the bank  (i.e., 30 tpy  x 1.3 =
39  tpy).   Although the bank has been reduced by 39 tpy,  there has
been a 30 tpy increase in emissions in the^nonattainment area due
to  the new source.  To assure that  new source growth will  not
.interfere with the 15 percent VOC emissions reduction requirement
when preenactment banked credits are used, existing sources must
eventually, by time of reconciliation, reduce their emissions at
least as much as the emissions  growth.
                     Bank
                              39 tpy in bank
                   New Source
                              Allowed to emit
                                + 30 tpy
                                         9 tpy from offset
                                         ratio of 1.3 to 1
                                         for severe area
                  Existing Sources
                            -15 tpy   -15 tpy

                       Must be offset by 30 tpy emission reductions
                    Figure 3.  Example of use  of
                   preenactment  banked emissions
                              credits.
                                 33

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 4.4   Maximum Achievable  Control Technology  (MACT)  Standards

 General Requirements

      Many of the  189 hazardous air pollutants  listed under
 section 112(b)(1)  of the Act are VOC's.  Any emissions  reductions
 of a  hazardous VOC resulting from the application  of a  MACT
 standard is  creditable toward the 15 percent VOC emissions
 reduction requirement for ozone nonattainment  areas.  Any
 incidental emissions reduction of a non-hazardous  VOC -resulting
 from  the application of  a MACT standard  is  also creditable toward
 the 15 percent VOC emissions reduction requirement.   It is
 important to note that some sources will be subject  to  both  MACT
 standards and RACT rules.  Because only  the more stringent of  the
 two standards will apply in these cases, States should  be aware
 that  double  counting of  the VOC emissions reductions from these
 two programs is not permitted.

      States  should recognize that reductions resulting  from  MACT
 standards must occur prior to November 15,  1996, to  be  creditable
.toward the 15 percent VOC emissions reduction  requirements.  Most
 MACT  standards will not  be promulgated until after the  post-1996
 emissions reduction requirements take effect.  Guidance regarding
 the creditability of MACT reductions toward the post-1996
 reduction requirements is presently under development within EPA.

      Section 112(d)(1) of the CAAA requires the promulgation of
 regulations  establishing emissions standards for categories  and
 subcategories of  major sources and area  sources of the  189
 hazardous air pollutants.  The emissions standard  for a
 particular hazardous air pollutant emitted  from a  new or existing
 source must  be based on  the maximum degree  of  reduction that the
 Administrator determines is achievable through the application of
 emissions control technologies.  The determination of MACT
 considers the cost of achieving such emissions reductions and  any
 non-air quality health and environmental impacts and energy
 requirements.

 Early Reductions  Program

      As a temporary alternative to complying with  an applicable
 MACT  standard, an existing source may elect to comply with the
 early reduction requirements of section  112(i)(5).   By  electing
'to achieve early  reductions, an existing source may,  under
 certain conditions, meet an alternative  emissions  limit in lieu
 of meeting an otherwise  applicable MACT  standard.  The
 alternative  emissions limit expires 6 years after  the otherwise
 applicable MACT standard compliance date, at which time the
 source must  comply with  the MACT requirement.  Except as follows,
 to obtain the MACT compliance extension  the reduction must be
 achieved before the otherwise applicable MACT  standard  is first
 proposed.  A source may  also obtain an extension if  it  commits to
 make  the 90  percent reduction prior to proposal of the  MACT
 standard and actually achieves the 90 percent  reduction prior  to
 January 1, 1994.

                                34

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     The  early  reduction  program  requires  a  source  to achieve
 hazardous air pollutant emissions reductions of  at  least  90
 percent  (at  least  95  percent  in the  case of  particulates).   The
 emissions reduction must  be determined  from  a comparison  of the
 actual post-control emissions with the  actual and verifiable
•emissions in a  base year  not  earlier than  1987.   A  base year of
 1985 or  1986 can be used  by a source if its  emissions data  are
 based on  information  received by  the Administrator  prior  to
 November  15, 1990, pursuant to an information request issued
 under section 114  of  the  Act.

     Hazardous  VOC emissions  reductions under the early reduction
 program  are  creditable  toward the 15 percent VOC emissions
 reduction requirements  to the extent that  reductions were taken
 after the 1990  base year  inventory applicable to the 15 percent
 VOC emissions reduction requirements.   Because a source can
 credit reductions  that  took place prior to 1990  toward the  early
 reduction program, the  entire 90  percent early reduction  may not
 be creditable toward  the  rate-of-progress  requirement.

     States  should be aware that  EPA is developing  a policy
 regarding potential conflicts between the  early  reduction program
 and the  RACT requirements.  (See reference  20.)   The interaction
 between  the  early  reduction program  and RACT requirements causes
 concern  because the prospect  of applying RACT requirements  to
 sources  that already  made early reductions would effectively
 limit the attractiveness  of,  and  therefore participation  in,  the
.early reductions program.  Additionally, States  should also be
 aware that early reductions must  be  taken  prior  to  November 15,
 1996, to be  credited  toward the 15 percent VOC emissions
 reduction requirements.   Guidance regarding  the  creditability of
 section  112(i)(5)  early reductions toward  the post-1996 reduction
 requirements is presently under development  within  EPA.   Readers
 interested in further details regarding the  section 112(i)(5)
 early reductions program  are  referred to the proposed regulations
 published in the Federal  Register.  (See reference 21.)  Final
 rules are anticipated by  early 1993.

 4.5  Rule Effectiveness Improvements

     Many States with preexisting nonattainment  areas have
 already  adopted rules defining RACT  for most of  the larger
 sources,  including non-CTG categories.  In such  cases,  there is
 .considerable concern  about what additional measures are needed to
 meet the  15  percent VOC emissions reduction  requirement.  One
 method of achieving creditable reductions  from stationary sources
 in such  areas is to improve the implementation of existing
 regulations.  This is referred to as rule  effectiveness
 improvement.  These improvements  are subject to  the same
 creditability constraints  as  are  the other emissions
                                35

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 reductions.15  Rule effectiveness improvements must reflect real
 emissions  reductions  resulting  from  specific  implementation
 program  improvements.  Actual emissions reductions must  result
 from  improving  rule effectiveness; simply calculating  a  higher
 rule  effectiveness using a different methodology  is  not
 creditable.

      Rule  effectiveness improvements must be  documented  at  a
 minimum  by conducting a post-implementation  (after the
 implementation  of rule effectiveness improvement  programs)
 source-specific emissions study.  Two methods are available for
 calculating  creditable rule  effectiveness improvements;  both
•require  that a  post-implementation Stationary Source Compliance
 Division (SSCD)  protocol study  be conducted.   The first  method
 involves pre- and post-rule  effectiveness improvement
 implementation  studies as delineated by SSCD.  For example, if
 the rule effectiveness increases from 50 to 75 percent,  the
 emissions  reductions  associated with this improvement  would be
 creditable.   The second approvable method uses the EPA default
 value of 80  percent for the  pre-rule effectiveness improvement
 rule  effectiveness value.  Thus, if  the results of a SSCD
 protocol study  show 85 percent  rule  effectiveness after
 implementation,  the increase in emissions reductions associated
 with  the improvement  from 80 to 85 percent would  be  creditable
 toward the 15 percent rate-of-progress requirement.  Additional
 discussion of rule effectiveness, including provisions for  the
 calculation  and use of category-specific rule effectiveness
 factors, is  available in Guidelines  for Estimating and Applying
 Rule  Effectiveness for Ozone/CO State Implementation Plans.  (See
 reference  22.)   The document "Growth Factors,  Projections,  and
 Control  Strategies,"  to be released  in the fall of 1992,  will
 provide  a  list  of control measures that involve rule
 effectiveness improvements.  Future  guidance  is under  development
 for the  quantification of rule  effectiveness  improvements.  The
 EPA plans  to issue the quantification guidance by late fall of
 1992.
 15For example, some RACT rule corrections that result in improved
 rule effectiveness may be  creditable;  a  discussion of this
 appears in section 4.1  of  this  document.

                                36

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5.0  PREVIEW OF THE DEVELOPMENT OF EMISSIONS PROJECTIONS,  CONTROL
     STRATEGY, AND 1996 MILESTONE COMPLIANCE DEMONSTRATION

     This document focuses on  the development  and  submittal  of
the elements of the rate-of-progress plan due  by November  15,
1992.  While EPA review of this submittal is underway,  States
should undertake the calculation of emissions  projections  for the
year 1996 and  the development  of full control  strategies.  These
elements of the rate-of-progress plan will be  due  in  draft form
to EPA by May  15, 1993.  The fully adopted rate-of-progress  plan
is then due by November 15, 1993.  A separate  guidance  document
is being developed by EPA on these other elements  of  the rate-of-
progress plan, which will include hypothetical nonattainment area
examples in describing the development of the  required  elements
for these submittals.  This guidance is expected to be  available
in the fall of 1992.

     The first milestone demonstration must illustrate  that  the
area has reached the 1996 target level of emissions as  defined  in
•the 15 percent VOC emissions reduction demonstration  plan.
Actual annual  and typical ozone season weekday emissions for
point sources  should be listed by facility.  Area  and off-highway
source emissions for each county by source category should also
be listed.  Finally, the highway vehicle emissions should  be
listed.  Once  the emissions from all of the known  anthropogenic
sources are listed, the total  emissions for the nonattainment
area should be computed and compared to the 1996 target.

     Section 182(a)(3)(A) requires the States  to submit periodic
inventories starting the third year after submission  of the  base
year inventory required by section 182(a)(1) and every  3 years
thereafter until the area is redesignated to attainment.   The EPA
recommends that States synchronize their schedules for  developing
the periodic inventories so that the second periodic  inventory
 (which would be due no later than November 15,  1998)  is submitted
by February 13, 1997 and addresses emissions in 1996.   By
accelerating preparation and submittal of the  1996 periodic
inventory, the milestone demonstration that is due for  serious
and above areas by February 13, 1997 can be based  on  this
periodic inventory.  If similarly accelerated,  future periodic
inventories would then also coincide with subsequent  milestone
.demonstrations.  The periodic  inventory is to  be based  on  actual
emissions and  will cover VOC,  NOX, and CO emissions sources.
Like the base  year inventory,  the periodic inventory  is to be
determined using typical peak  ozone season weekday emissions.

     The specific reporting requirements for the 15 percent  VOC
emissions reduction milestone  demonstration will be addressed in
an EPA regulation to be promulgated in the summer  of  1993.  This
regulation will address summary data needs as  well as detailed
reporting requirements.  The rule will also address consequences
of submitting  an inadequate demonstration  (in  terms of
documentation) as well as consequences of failure  to  demonstrate
the 15 percent VOC emissions reduction.


                                37

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                            REFERENCES

1.   Emission Inventory Requirements  for Ozone State
     Implementation Plans, EPA-450/4-91-010, U.S. Environmental
     Protection Agency, Office of Air Quality Planning  and
     Standards, Research Triangle Park, NC.  March  1991.

2.   Procedures for the Preparation of Emission  Inventories  for
     Carbon Monoxide and Precursors of Ozone.  Volume I:  General
     Guidance for Stationary Sources, EPA-450/4-91-016, U.S.
     Environmental Protection Agency, Office of  Air Quality
     Planning and Standards, Research Triangle Park, NC.  May
     1991 .

3.   Procedures for Emission Inventory Preparation, Volume IV:
     Mobile Sources, EPA -450/4-81-026d  (Revised),  U.S.
     Environmental Protection Agency, Office of  Air Quality
     Planning and Standards, Research Triangle Park, NC.  July
     1992.

4.   User's Guide to MOBILE4.1  (Mobile Source Emission  Factor
     Model), EPA-AA-TEB-91-01, U.S. Environmental Protection
     Agency, Office of Mobile Sources, Ann Arbor, MI.   July  1991.

5.   Vehicle Miles Traveled Forecasting and Tracking Guidance,
     U.S. Environmental Protection Agency, Office of Mobile
     Sources, Ann Arbor, MI.  March 1992.

6.   Personal Computer Version of the Bioqenic Emissions
     Inventory System  (PC-BEIS) And User's Guide, EPA-450/4-91-
     017, U.S. Environmental Protection Agency,  Research  Triangle
     Park, NC.  July 1991.

. 7.   Procedures for the Preparation _of Emissions Inventories for
     Carbon Monoxide and Precursors of Ozone.  Volume II:
     Emission Inventory Requirements  for Photochemical  Air
     Quality Simulation Models.  EPA-450/4-91-014,  U.S.
     Environmental Protection Agency, Office of  Air Quality
     Planning and Standards, Research Triangle Park, NC.  May
     1991 .

8.   Guidance for the Preparation of  Quality Assurance  Plans for
     0,/CO SIP Emission Inventories,  EPA-450/4-88-023, U.S.
     Environmental Protection Agency, Office of  Air Quality
     Planning and Standards, Research Triangle Park, NC.
     December 1988.

9.   Quality Review Guidelines for  1990 Base Year Emission
     Inventories. EPA-450/4-91-022, U.S. Environmental  Protection
     Agency, Office of Air Quality Planning and  Standards,
     Research Triangle Park, NC.  July 1992.

10.  Example Documentation Report for 1990 Base  Year Ozone and
     Carbon Monoxide State Implementation Plan Emission
     Inventories, EPA-450/4-92-007, U.S. Environmental  Protection

                                39

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     Agency,  Office of Air Quality Planning and Standards,
     Research Triangle'Park,  NC.   March 1992.

11.   Guidelines for Estimating and Applying Rule Effectiveness
     For Ozone/CO State Implementation Plans,  Draft Report,
     Prepared by Alliance Technologies Corporation, Prepared for
     U.S. Environmental Protection Agency,  Office of Air Quality
     Planning and Standards,  Ozone and Carbon Monoxide Branch,
     Research Triangle Park,  NC.   April 1992 (final report
     forthcoming).

12.   55 FR 23666,  "Volatility Regulations for Gasoline and
     Alcohol Blends Sold in Calendar Years 1992 and Beyond," June
     11, 1990.

13.   BEA Regional Projections to 2040, Volume I:  States, U.S.
     Department of Commerce,  Bureau of Economic Analysis,
     Washington, D.C., U.S. Government Printing Office.  October
     1990.

14.   BEA Regional Prelections to 2040, Volume II:  Metropolitan
     Statistical Areas,  U.S.  Department of Commerce/ Bureau of
     Economic Analysis,  Washington, D.C., U.S. Government
     Printing Office.  October 1990.

15.   BEA Regional Projections to 2040, Volume III: BEA Economic
     Areas,  U.S. Department of Commerce,  Bureau of Economic
     Analysis, Washington, D.C.,  U.S. Government Printing Office.
     October 1990.

16.   Procedures for Preparing Emissions Projections, EPA-450/4-
     91-019,  U.S.  Environmental Protection Agency, Office of Air
     Quality Planning and Standards, Research Triangle Park, NC.
     July 1991.

17.   Model Volatile Organic Compound Rules for Reasonable
     Available Control Technology:  Planning for Ozone
     Nonattainment Pursuant to Title I of the Clean Air Act
     (Staff Working Document), U.S. Environmental Protection
     Agency,  Office of Air Quality and Planning Standards,
     Research Triangle Park,  NC.   June 1992.

18.   I/M Costs, Benefits, and Impacts Analysis, U.S.
     Environmental Protection Agency, Office of Mobile Sources,
     Ann Arbor, MI.  February 1992.

19.   51 FR 233 "Emissions Trading Policy Statement; General
     Principles for Creation, Banking and Use of Emission
     Reduction Credits; Final Policy Statement and Technical
     Issues Document."  December 4, 1986.

20.   "Early Reductions Program/Title I Interface," Memorandum
     from John S. Seitz, U.S. Environmental Protection Agency,
     Office of Air Quality Planning and Standards, Research
     Triangle Park, NC.  December 20, 1991.

                               40

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21.  56 FR 27338.  "National Emission Standards for Hazardous Air
     Pollutants for Source Categories; Proposed Regulations
     Governing Compliance Extensions for Early Reductions of
     Hazardous Air Pollutants." June 13, 1991.

22.  Reference 11.
                               41

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                 APPENDIX A:  DEFINITION OF TERMS

     This appendix provides  the  specific definitions  of  EPA terms
as they are used  in  this  guidance.  Different  EPA programs
sometimes use different definitions of  the  same  term  (e.g.,  major
source).  This appendix notes where conflicts  occur in the
definition of a term used in this guidance.  These definitions
are presented for the purposes of this  guidance  document only;
the reader is advised to  refer to specific  regulations,  policies,
and sections of the  Act to obtain complete  definitions for  the
program or title  of  interest.

Area Source  Any  stationary or non-road source that is too  small
and/or too numerous  to be included in the  stationary  point-source
emissions inventories.

Attainment Demonstration   Moderate and  above ozone nonattainment
'areas must demonstrate that the  reductions  specified  in  the
revised SIP will  result in modeled air  quality for the
nonattainment area that achieves attainment by the applicable
attainment date.  This requirement can  be  met  through the
application of an EPA-approved model and EPA-approved modeling
techniques described in the current version of the Guidance on
Air Quality Models16  (EPA-450/2-78-027R),  which is currently
under revision.   Two models are  suggested:  the  UAM or EKMA.   The
EPA requires the  submittal of attainment demonstrations  employing
UAM for serious and  above areas  and multi-State  moderate areas as
part of the SIP revision  due by  November 15, 1994. Attainment
demonstrations based on EKMA for moderate  nonattainment  areas
within a  single state (intrastate moderate areas)  must be
submitted as part of the  SIP revision due  by November 15, 1993,
unless the State  chooses  to use  UAM, in which  case the
demonstration must be submitted  as part of the SIP revision due
by November 15, 1994. The use of EKMA  is  described in Guideline
for Use of City-Specific  EKMA in Preparing Ozone SIP/s (EPA-
450/4-80-027) as  well as  the aforementioned guideline that  is
under revision.   This document,  and the appropriate Regional
Office, should be consulted before an analysis is conducted with
this modeling approach.   The use of UAM is described  in  Guideline
• for Regulatory Application of the .Urban Airshed  Model (EPA-450/4-
91-013) .1V
 16Guidance on Air Quality Models  (Revised), EPA-450/2-78-027R,
 July 1986  (currently under  revision).

 17Guideline for .Regulatory Application of the Urban Airshed
 Model,  EPA-450/4-91-013,  U.S.  Environmental Protection Agency,
 Office  of  Air  Quality Planning and Standards,  Research Triangle
 Park, NC.

                                A-1

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 Attainment  Determination   The EPA must determine  within 6  months
 after  the applicable  attainment date whether  an area  has attained
'the NAAQS for  ozone.  The  attainment dates  are as follows:

      •    Marginal  areas —   November 15,  1993.
      •    Moderate  areas —   November 15,  1996.
      •    Serious areas  —   November 15,  1999.
      •    Severe areas   —   November 15,  2005  (severe areas
                              with a 1986-1988 ozone  design value
                              of 0.190 up to, but not including
                              0.280 parts per million have until
                              November 15,  2007).
      •    Extreme areas  —   November 15,  2010.

 In making the  attainment determination, EPA will  use  the most
 recently available, quality-assured air quality data  covering the
 3-year  period  preceding the  attainment date.  For ozone, the
 average number of exceedances per year after  adjustment for
 missing data are used to determine whether  the area has attained.

 Basic  Inspection and  Maintenance  (I/M)  Programs  requiring the
 inspection  of  vehicles including, but not limited to,  measurement
 of tailpipe emissions, and mandating that vehicles with tailpipe
 emissions higher than the  program cutpoints be repaired to pass a
'tailpipe emissions  retest.   Basic I/M programs must be at  least
 as stringent as the requirements set out in section 182(a) (2) (B) .

 Maior  Stationary Source  The CAAA have multiple definitions for
 major  stationary sources depending upon the nonattainment
 classification and  the pollutant.  Section  302 of the CAAA
 defines a major stationary source as one that directly emits,  or
 has the potential to  emit, 100 tpy or more  of any air pollutant.
 As exceptions  to this rule,  major stationary  source emissions
 thresholds, as defined in  Part D of Title I of the CAAA, are
 listed  in Table A-1 for both VOC and NOV sources.
                                       A.

 Milestone Compliance  Demonstration  For serious and above
 classified  nonattainment areas, demonstrating achievement  of the
 15 percent  VOC emissions reduction over the 1990-1996 period,  or
 demonstrating  subsequent 3 percent VOC emissions  reductions per
 year averaged  over  each consecutive 3-year  period from November
 15, 1996 until the  attainment date.  Section  182(g)(2)  requires
 that within 90 days of the date on which an applicable milestone
 occurs  (not including an attainment date on which a milestone
 occurs  in cases where the  standard has been attained),  States
 with nonattainment  areas must submit a demonstration  that  the
•milestone has  been  met  (e.g., the 15 percent  VOC  emissions
 reduction is demonstrated  by February 13, 1997).   The EPA  expects
 to release  regulations pertaining to the requirements of the
 milestone demonstration in the Summer of 1993.

 1990 Adjusted  Base  Year Inventory  Section  182(b)(1)(B)  and (D)
 describes the  inventory  (hereafter referred to as the adjusted
 base year inventory)  from  which moderate and  above ozone
 nonattainment  areas must achieve a 15 percent reduction in VOC

                               A-2

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TABLE A-1.  MAJOR  SOURCE  THRESHOLDS AND  MINIMUM EMISSIONS OFFSET
 RATIO REQUIREMENTS FOR OZONE NONATTAINMENT AREA CLASSIFICATIONS
Ozone Nonattainment Area
Extreme
Severe
Serious
Moderate
Moderate, in an ozone
transport region
Marginal
voc
(tpy)
10
25
50
100
50
100
NOX
(tpy)
10
25
50
100
100
100
Minimum
Emissions
Offset Ratio
Required
1.5 to 118
1.3 to I13
1.2 to 1
1.15 to 1
1.15 to 1
1.1 to 1
 Marginal,  in an ozone
   transport region

 All other nonattainment areas,
   outside of an ozone
   transport region19

 All other nonattainment areas,
   in an ozone transport region19

 Attainment, in an ozone
   transport region
 50



100


100


 50
100



100


100


100
1.15 to 1



>1.0 to 1


1.15 to 1


1.15 to 1
18The minimum  ratio  is  reduced  to  1.2  to  1  if  the  applicable
State implementation plan requires all major sources of VOC and
NOX emissions  to use best available control technology.

19The other  nonattainment areas are submarginal, transitional,
and incomplete/no data.
                               A-3

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 emissions  by 1996.   This  inventory  is  equal  to "the total amount
 of  actual  VOC or  NOX emissions from all anthropogenic  (man-made)
 sources  in the area  during  the calendar year of enactment,"
 excluding  the emissions that  would  be  eliminated by FMVCP
 regulations promulgated by  January  1,  1990,  and RVP regulations
 (55 FR 23666,  June 11, 1990), which require  specific maximum RVP
 levels for gasoline  in particular nonattainment areas  during the
 peak ozone season.   The 1990  rate-of-progress base  year inventory
 (defined below) removes biogenic emissions and emissions from
 sources  listed in the base  year inventory that are  located
 outside  of the nonattainment  area.  The adjusted base  year
•inventory  removes the emissions reductions from the FMVCP and RVP
 program  from the  1990 rate-of-progress base  year inventory.  The
 adjusted base year inventory, which is due by November 15,  1992,
 is  used  to calculate the  required 15 percent reductions.

   Adjusted Base Year Emissions Inventory = Base Year Emissions
                  Inventory, minus the  following:

      •     Biogenic source emissions.
      •     Emissions  from  sources outside of  the nonattainment
           area boundary.
      •     Emissions  reductions from the FMVCP.
      •     Emissions  reductions from the RVP  rules.20

 1990 Base  Year Inventory  The 1990  base year inventory is an
 inventory  of actual  annual  and typical weekday peak ozone season
 emissions  that States use in  calculating their adjusted and
 projected  inventories, and  in developing their control strategy.
 The base year inventory comprises emissions  for the area during
 the peak ozone season, which  is generally the summer months.   It
 includes anthropogenic sources of NOX  and CO  emissions,  and both
 anthropogenic and biogenic  sources  of  VOC emissions.   Also
.included in the inventory are emissions from all stationary point
 sources  and area  sources  as well as highway  and nonhighway mobile
 sources  located within the  nonattainment area,  and  stationary
 sources  with emissions of 100 tpy or greater' of VOC, NOX, and CO
 emissions  within  a 25-mile  wide buffer zone  of the  designated
 nonattainment area.  The  base year  inventory contains  off-shore
 sources  located within the  nonattainment area boundaries and off-
 shore stationary  sources  with emissions of 100 tpy  or  greater of
 VOC,  NOX,  or  CO emissions within the 25-mile  wide buffer area.
 For nonattainment areas that  will perform photochemical grid
 modeling (e.g., serious and above areas and  multi-State moderate
 areas),  emissions for the entire modeling domain, which is
 usually  larger than  the nonattainment  area because  ozone is an
 area-wide  problem, are required in  the modeling inventory.   This
 modeling inventory could  be submitted  with the base year
 inventory, or the modeling  inventory submittal could be in a
 separate package.  It is  important  to  note that the 1990 base
 20See figures 1 and 2 in section 2.0 of this document for a
 further description of  the  relationship of  the  adjusted base year
 inventory to the  1990 rate-of-progress base year  inventory.

                               A-4

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 year inventory serves as the starting point for all other
 inventories.

 1990 Rate-of-Progress Base Year Inventory  An accounting of all
 anthropogenic VOC,  CO,  and NOX  emissions  in the nonattainment
 area.   This emissions inventory is calculated by removing
 biogenic emissions  and the emissions from sources that are
 located outside of  the nonattainment area from the base year
'inventory.   This inventory is used in developing the adjusted
 base year inventory.   It is also used as  the basis from which to
 calculate the 1996  target level of emissions.

 1996 Target Level of  Emissions   The 1996  target level of
 emissions is the maximum amount of ozone  season VOC emissions
 that can been emitted by an ozone nonattainment area in 1996 for
 that nonattainment  area to be in compliance with the 15 percent
 rate-of-progress requirements.   It is calculated by first taking
 15 percent  of the adjusted base year inventory emissions.  This
 emissions value is  then added to the expected emissions
 reductions  due to the FMVCP and RVP program,  and from corrections
 to any deficient RACT rules and I/M programs.   The summation of
 the 15 percent,  the expected reductions from deficient I/M and
 RACT programs,  and  reductions from the FMVCP and RVP program are
 then subtracted from  the 1990 rate-of-progress base year
 inventory to arrive at the 1996 target level of emissions.  This
 target is used by States to design their  15 percent VOC emissions
 reduction control strategies.  The projected control strategy
 inventory used in the rate-of-progress plan must be at or below
 the 1996 target level of emissions to demonstrate that the 15
 percent VOC emissions reduction will be accomplished.

    1996 Target Level  of Emissions = Rate-of-Progress Base Year
                  Inventory,  minus the following:

      •    15 percent  of the adjusted base year inventory
           emissions.
      •    Emissions reductions  from corrections to any deficient
           RACT rules.
      •    Emissions reductions  from corrections to deficient I/M
           programs.
      •    Emissions reductions  from the pre-1990 FMVCP.
      •   Emissions reductions  from RVP rules.

 Peak Ozone  Season  The contiguous 3-month period of the year
 during which the highest ozone  exceedance days  have occurred over
 the 3  to 4  years prior to the 1990 base year.   Most ozone
 nonattainment areas have a peak ozone season lasting from June
 through August.

 Offset Ratios  For  the purpose  of satisfying the emissions offset
 reduction requirements  of section 173(a)(1)(A),  the emissions
 offset ratio is  defined as the  ratio of total  actual emissions
.reductions  of VOC (and NOX unless  exempted  under  section  182[f])
 obtained as offsets from existing sources to total allowable
 emissions increases of  such pollutant from the  new source.  (See

                                A-5

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 Table  A-1  for  a  list  of  offset  ratios by  nonattainment  area.)
 Additional information on  offsets  will be provided in forthcoming
 guidance  regarding the interaction of the 15 percent  VOC
 emissions reduction requirements of  Title I with  the  emissions
 reduction requirements of  other Titles  (i.e./  New Source Review,
 Title  II  reductions,  etc.).

 Point  Source   Any  stationary  source  that  has the  potential to
 emit more than some specified threshold level  of  a pollutant or
 is  identified  as an individual  source in  a State's emissions
 inventory.  For  base  year  SIP inventory purposes,  point sources
 are defined as sources emitting 10 tpy or more of VOC emissions
 or  100 tpy or  more of NOX or  CO emissions.

'Post-1996 Rate-of-Progress Plan The portion of the SIP revision
 due by November  15, 1994,  which describes how  serious and above
 areas  plan to  achieve the  post-1996, 3 percent per year VOC
 emissions reductions  averaged over each consecutive 3-year period
 from November  15,  1996 until  the attainment date.   This SIP
 revision  also  includes the attainment'demonstration for moderate
 interstate nonattainment areas  and serious and above
 nonattainment  areas.

 RACT "Catch-ups"  The application  of RACT for  all applicable
 sources as listed  in  section  182(b)(2), regardless of what was
 previously required.  Each moderate  and above  ozone nonattainment
 area  (as  well  as attainment areas  within  the ozone transport
 region) are subject to the RACT "catch-up" requirement  of section
 182(b)(2).  The  new law  requires any of the above areas that had
 not previously adopted RACT consistent with all of the  CTG's to
 "catch-up" and apply  RACT  to  all sources  covered  by a
 preenactment or  post-enactment  CTG document.   Many of these areas
 were not  previously required  to apply RACT to  sources covered by
 Group  III CTG's  (CTG's published after September  198,2).   In
 addition,  areas  previously considered rural nonattainment,  which
 had to apply RACT  only to  certain  major sources in certain CTG
•categories under prior policy,  will  have  to revise their SIP's to
 apply  RACT to  all  sources, including nonmajor  sources,  that are
 covered by any CTG.   The RACT "catch-up"  provision also requires
 these  nonattainment areas  to  adopt RACT rules  for all major
 sources not covered by a CTG.   Additional information on the RACT
 "catch-up" program will  be provided  in forthcoming guidance
 regarding the  interaction  of  RACT  rules with emissions
 inventories.

 RACT "Fix-ups"  Corrections States are required to make under
 section 182(a)(2)(1)  to  their current RACT rules  to make up for
 deficiencies  (e.g., improper  exemptions)  in pre-amendment plans.
 Under  RACT "fix-ups", States  are required to have RACT  rules that
 comply with section 172(b) of the  pre-1990 Act, as interpreted by
 EPA's  pre-amendment guidance.   Since the  RACT  "fix-up"  provisions
 refer  to  RACT  as required  by  pre-amended  section  172(b),  only
 areas  subject  to pre-amended  section 172(b) need  to meet the RACT
 "fix-up"  requirement.  Therefore,  for nonattainment areas that
 will be expanded to contain regions  that  were  designated

                                A-6

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'attainment prior  to  enactment,  the  RACT  corrections  are only for
 the original  nonattainment. area.  The  RACT  "fix-up"  provision
 essentially codifies EPA's SIP  calls,  issued in May  1988 and
 November  1989 (as announced in  the  Federal  Register  on September
 7, 1988  [53 FR  34500]  and July  30,  1990  [55 FR 30973]).  The RACT
 fix-ups were  due  on  May 15,  1991.   Between  May 24  and June 24,
 1991,  EPA's Regional offices mailed letters to several Governors
 and air agency  officials concerning the  progress of  the States  in
 meeting RACT  "fix-up" requirements  and listing the outstanding
 deficiencies  that still had not been corrected.  Additional
 information on  the RACT "fix-up" program will be provided in
 forthcoming guidance regarding  the  interaction of  RACT rules with
 emissions inventories.

 Rate-of-Progress  Plan  The portion  of  the SIP revision due by
 November  15,  1993, that describes how  moderate and above ozone
 nonattainment areas  plan to achieve the  15  percent VOC emissions
 reduction.  All moderate intrastate areas that choose to utilize
 the EKMA  in their attainment demonstration,  are also required to
 include their attainment demonstration in this SIP revision.

 Rule  Effectiveness (RE)   For stationary  sources, a measure of the
•extent to which a regulatory program achieves emissions
 reductions.   An RE of 100 percent reflects  a regulatory program
 achieving all the emissions reductions that could  be achieved by
 full  compliance with the applicable regulations at all sources  at
 all times.  However,  regulations typically  are not 100 percent
 effective due to  limitations of control  techniques or
 shortcomings  in the  implementation  and enforcement process.  The
 EPA allows the  use of three different  methods for  determining RE:
 an 80 percent default value; results from EPA Questionnaires; or
 results from  a  Stationary Source Compliance Division (SSCD)
 study.

 Volatile  Organic  Compound  Any  compound  of  carbon, excluding CO,
 carbon dioxide, carbonic acid,  metallic  carbides or  carbonates,
 and ammonium  carbonate,  which participates  in atmospheric
 photochemical reactions.  This  includes  any organic  compound
 other than those  EPA has determined to have negligible
 photochemical reactivity.21
 2157 Federal Register 3945, February 3, 1992.

                               A-7

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                            APPENDIX  B:
  CALCULATION OF EMISSIONS REDUCTIONS FROM RACT RULE CORRECTIONS

     Section 4.1  of  this  document  discusses  cases  where RACT rule
 corrections  do  not directly result in quantifiable emissions
 reductions.   Any  incidental reductions  that  occur  in these cases
'may  be  handled  as part  of a rule effectiveness  improvement.
 Corrections  to  RACT  rules that  may result  in additional,
 enforceable,  and  quantifiable emissions reductions include
 situations where:

      •    A  rule  was missing (i.e.,  a State  committed to
          develop a  rule  as part of  its 1977 SIP,  or post-
          1982  SIP,  but never carried through on the
          commitment prior to the  CAAA).
      •    The limit  was wrong.
      •    A  -capture  system is now  required to ensure meeting
          a  RACT  limit.

 For  the case where a rule was missing,  the State should first
 calculate the uncontrolled emissions in 1990 and multiply the
 1990 uncontrolled emissions by  the appropriate  growth factor.
 Next,  the State must evaluate the  expected emissions reduction in
 1996 by calculating  1996  emissions (including growth and
 controls) and subtracting this  number from 1990 emissions.  This
 total expected  emissions  reduction should  be added to the total
 reductions in step 5 in the example  in  section  2.1 of this
 document.  These  reductions are not  creditable  toward the 15
•percent VOC  emissions reduction requirement.

      For the second  case, the State  should first evaluate the
 pound (Ib) VOC/gallon  (gal) solids for  each  limit.

 1990 limit = 3.5  Ib  VOC/gal coating

 1)  1990 Ib VOC/gal solids =

      3.5 Ib  VOC  x    1 gal coating  = 0.476  gal VOC
          gal coating  7.36 Ib VOC            gal coating

 2)  Calculate solids  in 1  gal coating:
      1   - 0.476 = 0.524 gal solids

 3)  Calculate gallons of coating needed  to  get gallon of solids:
      1  gal coating = 1.908 gal  coating
      0.524 gal  solids      gal  solids

 4)  Convert  3.5  Ib/gal coating to Ib  VOC/gal  solids:
      3.5 Ib  VOC  x    1.908 gal  coating  = 6.678  Ib VOC
      gal coating      gal  solids                gal solids

 The 1996 limit  will  be 2.9 Ib/gal.

      Similarly, convert 2.9 Ib  VOC/gal  coating  to Ib VOC/gal
 solids.

                                B-1

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5) 2.9 Ib VOC x 1 gal VOC = 0.394 gal VOC
   gal coating  7.36 Ib VOC       gal coating

6) Volume of solids in 1 gal coating:
     1 - 0.394 = 0.606 gal solids

7) Calculate gallons of coating needed to get 1 gallon of solids;
     1 gal coating = 1.650 gal coating
     0.606 gal solids      gal solids

8) Convert 2.9 Ib VOC gal coating to Ib VOC/gal solids:
     2.9 Ib VOC  x  1.650 gal coating = 4.785 Ib VOC
     gal coating       '   gal solids          gal solids

The facility uses 100 gal solids in 1990
                      day

9) Compare 1990 and 1996 Emissions:

  1990 = 6.678 Ibs VOC x 100 gal solids = 667.8 Ibs VOC
               gal solids        day            day

  1996 = 4.785 Ib VOC x 100 gal solids x growth factor(1.2)
               gal solids       day
                                             = 574.2 Ib VOC
                                                     day

1990 Emissions - 1996 Emissions = 667.8 - 574.2 =93.6 Ib VOC
                                                       day

Therefore, 93.6 Ib VOC/day are noncreditable.

     For the third case where a capture system is required,
expected emissions reductions should be calculated in the
following way.  First, uncontrolled emissions should be
determined.

     1990 Paper Coaters:
         •   80 percent  of  emissions  coming  out  of  the  oven and
             vented  to an incinerator of  98  percent  demonstrated
             destruction efficiency.
         •   20 percent  of  emissions  are  fugitive from
             uncontrolled flash-off area.

     Total uncontrolled emissions in 1990 =

         1,000 Ib/day if total is uncontrolled,  however,
         when system is  controlled, 80 percent of  this
         is captured, and 98 percent  of captured
         emissions are destroyed.
                               B-2

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     So, emissions  from  the  incinerator  after  control  are
     1,000  Ib/day x (1-(0.80))  x  (1-(0.98))  =

         (1,000 Ib/day) x  (0.20) x  (0.02) =  4  Ib/day
         controlled.  Total Emissions from incinerator +
         fugitives = 4 Ib/day + (1,000 Ib/day  x  (0.20))
         = 204 Ib/day

 1996 Emissions:
     New State rule now  requires permanent total enclosure,
     so the controlled emissions are:

         1,000 Ib day  (1.0)  (0.02) = 20  Ib/day

 Noncreditable Emissions  Reductions  =
 1990 Emissions - 1996 Emissions    =  204 Ib/day -  20  Ib/day
                                      184 Ib/day

     The preceding  examples  are not intended to  be  fully
 inclusive.  States  should  evaluate  all RACT  rule corrections to
.determine if such measures result in real, enforceable, and
 permanent emissions reductions.  If so,  such reductions must be
 quantified  and considered  in the SIP development process  when
 preparing the 1996  target  level of  emissions.  If a State is
 unclear on  how to calculate  such reductions, then the  State
 should consult with the  Regional Office  and  Headquarters  for
 guidance.
                               B-3

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                           APPENDIX C:
 CALCULATION OP  EMISSIONS REDUCTIONS  PROM I/M PROGRAM CORRECTIONS

     Corrections to I/M programs occur when either  (1) the area's
I/M program does not meet the reductions achieved by EPA's
minimum requirements, or  (2) an area's program does not meet the
standards of their current SIP.  I/M program corrections are
calculated by modeling two separate I/M programs in MOBILE4.1:
the area's current I/M program, and the stricter of:  the I/M
program described in the area's SIP,  or the minimum I/M program
as specified by EPA.  MOBILE4.1 (or MOBILES with the flag set to
turn off new CAAA measures) should be run for calendar year 1996
using I/M input that describes the program before and after
corrections are made.  The difference between the resulting
emissions factors is then multiplied by 1990 VMT to get the
emissions reduction associated with the I/M program correction.

     In case 1,  the motor vehicle emissions factor is calculated
for 1996 with the area's current program and with EPA's model
program.  In each case, the MOBILE model is run with the pre-CAAA
FMVCP and phase II RVP.  No additional CAAA requirements are
modeled.  Sample MOBILE4.1 inputs for EPA's model program are
shown in Table C-l.

   TABLE C-l.  INSPECTION AND MAINTENANCE (I/M) PROGRAM INPUTS


 I/M Program Characteristics	Input	

 Start year (January 1)                            1983

 Pre-1981 model  stringency rate                    20%

 First model year covered                          1968

 Last model year covered                           2020

 Waiver rate (pre-1981)                            0%

 Waiver rate (1981 and newer)                       6%

 Compliance rate                                   100%

 Inspection type                                   Centralized

 Inspection frequency                              Annual

 Vehicle types covered                             LDGV
The difference in motor vehicle emissions with the current
program and the model program is the I/M program correction.
This correction should only be calculated for areas within the
nonattainment area which were required to have an I/M program
under the Act.
                               C-l

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     The following describes an example  I/M program correction
calculation.  It is important  for  States t° realize that  these
reductions are not creditable  toward  the 15 percent VOC emissions
reduction requirement.


               SAMPLE I/M CORRECTION CALCULATION:22

1990 VMT:  101.6 million miles per day

1996 MOBILE4.1 emissions factor with  area's current program:
     1.291 grams/mile

1996 MOBILE4.1 emissions factor with  EPA's minimum model  program:
     1.248 grams/mile

Calculate motor vehicle emissions:

current program:

     101.6 x  106 miles x 1 .291  grams = 288,911 Ibs/day
             day               mile

model  program:

     101.6 x  106 miles x 1.248 grams = 279,288 Ibs/day
             day               mile

Calculate I/M correction:

     I/M correction =    Emissions with  current  I/M -
                         Emissions with  model I/M

                         288,911 - 279,288

                    =    9,623 Ib/day of noncreditable  emissions.


     In case  2, motor vehicle  emissions  are calculated  with the
area's current program as implemented and with the program
required under the area's SIP.  Again, MOBILE4.1 input  files
.should model  the FMVCP and  phase II RVP  but no additional CAAA
controls.  The difference between  these  two estimates is  the  I/M
correction.
 22This calculation uses total VMT and a total speed/vehicle type
 weighted emissions  factor.   Alternatively, VMT and  emissions
 factors  by vehicle  type/roadway  class  could  be used to  calculate
 total emissions  under  the current  program and EPA's model
 program.


                               C-2

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