EPA-450/4-91-011
EMISSION INVENTORY
REQUIREMENTS FOR
CARBON MONOXIDE
STATE IMPLEMENTATION PLANS
By
Emission Inventory Branch
Technical Support Division
And
Radian Corporation
Research Triangle Park, NC 27709
Office of Air Quality Planning and Standards
Office of Air and Radiation
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
March 1991
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DISCLAIMER
This report has been reviewed by the Office of Air
Quality Planning and Standards, U. S. Environmental Protection
Agency, and has been approved for publication. Any mention of
trade names or commercial products does not constitute
endorsement or recommendation for use.
EPA-450/4-91-011
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PREFACE
This document describes the emission inventory
requirements related to the preparation and submission of carbon
monoxide (CO) State Implementation Plans (SIPs) for those areas
required to revise their plan as a result of provisions contained
in the 1990 Clean Air Act Amendments (CAAA). This document
represents a revision and an update to the document entitled
Emission Inventory Requirements for Post-1987 Carbon Monoxide
State Implementation Plans (EPA-450/4-88-020) issued in December
1988 in response to the proposed Post-1987 Ozone/CO Policy.
As with the previous requirements document, the primary
focus of this document and its requirements discussion is base
year emission inventories. Other CO SIP inventories required or
necessitated by the CAAA, including periodic and modeling
inventories, are also identified and requirements for these
inventories are briefly discussed. Because both base year
inventories and attainment demonstrations for CO nonattainment
areas above 12.7 ppm are due in final form by November 15, 1992,
the importance of early submittal of base year inventories and
preparation of modeling inventories is emphasized. More detailed
guidance on these inventories will be issued by the U. S.
Environmental Protection Agency (EPA) in subsequent guidance
documents (see Section 6.0).
Guidance herein provides details of the 1990 CAAA CO
SIP emission inventory requirements beyond those discussed in
Guidance for Initiating Ozone/CO SIP Emission Inventories
Pursuant to the 1990 Clean Air Act Amendments. February 1991.
While discussions in this document are consistent with the
February 1991 guidance, one change concerns the temporal basis
for CO emissions reporting. In the base year and periodic
inventories, States will be required to report CO emissions on a
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daily basis, rather than an 8 hour basis, as was discussed in the
February guidance.
Another change concerns the schedule for submittal of
Inventory Preparation Plans, which describe how and when the
inventories will be prepared and reported to EPA. The plan shall
present a blueprint for the methods and data sources a State
plans to use to compile and document its inventories. The IPP
shall also contain a specification of the intended quality
assurance program for each inventory compilation and a schedule
for preparation and submittal of each inventory. In the February
guidance document, a date was listed (October 1, 1991) by which
the plans must be agreed upon by EPA and in final form. However,
no initial submittal date was mentioned. Guidance herein
includes the October 1 date for a final Inventory Preparation
Plan and adds a requirement for submittal of the initial
Inventory Preparation Plan by July 31, 1991 (see Section 3.1).
The most significant changes incorporated into this
guidance from that provided to support the proposed Post-1987
Policy are summarized below.
• As mentioned above, inventory preparation plans
(IPPs) shall be developed for each nonattainment
area that describe how and when the required
emission inventories for the area will be prepared
and submitted to EPA. IPPs were not required
under the proposed Post-1987 Ozone/CO policy
guidance. Each IPP must be submitted to EPA no
later than July 31, 1991, for review and approval.
IPPs must be agreed upon with EPA and in final
form by October 1, 1991. EPA will not accept for
review any submitted CO SIP inventory for which
there is not an approved IPP.
• The MOBILE4 model, required under the proposed
Post-1987 Policy guidance for estimating on-road
mobile source emission factors, is being revised
and updated by EPA. The revised model, MOBILE4.1
(to be issued in May 1991), must be used to
estimate on-road vehicle emissions for CAAA SIP
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inventories. The majority of the changes to the
model are internal such that there are essentially
no added requirements placed on the user, with the
possible exception of generating emissions on an
hourly basis. Specific guidance on the updated
model will be issued in May 1991.
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Computerized data management and reporting
requirements for CAAA SIP inventories have been
significantly expanded beyond those found in the
guidance accompanying the previous policy. All CO
SIP emission inventory data must be provided to
EPA in an AIRS (Aerometric Information Retrieval
System) compatible format or directly into AIRS.
The data elements States must input into AIRS for
SIP inventories are discussed in the document.
EPA will be issuing additional guidance in 1991 on
the use of AIRS and its subsystems.
Written inventory documentation requirements have
been clarified and expanded for the purpose of
providing EPA with a better basis to perform
inventory quality review assessments. A specific
outline has been provided to States to indicate
the content and organization of the information
that States shall provide to EPA.
EPA's Office of Mobile Sources (QMS) is actively
engaged in research to develop new methodologies
for estimating CO emissions from several mobile
source categories. Interim research results which
have been provided and which are recommended for
States' use in CO SIP inventory development are
discussed. The source categories principally
affected are non-road mobile sources such as
airplanes and trains. Work has also been
performed on revising the methods for deriving
vehicle-miles-traveled (VMT) estimates for on-road
mobile sources emissions.
States with SIP emission inventories prepared
under the proposed Post-1987 Policy that have
1987, 1988, or 1989 base years and that have been
determined by the EPA Regional Offices to be
complete, comprehensive, and accurate will be
allowed to update certain portions of these
inventories to a 1990 base year instead of having
to totally redevelop the inventories with 1990
data. Criteria for determining which inventories
can be updated and which can not have been
developed by EPA and will be applied on an
inventory-specific basis by the EPA Regional
Offices. Some specifications for updating are
provided in this document.
CO SIP revisions under the CAAA must include
certain inventories that go beyond requirements in
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the proposed Post-1987 Policy. States shall
prepare periodic and modeling inventories that are
associated with tracking required emission
reductions and demonstrating attainment.
Overviews of these inventories and their
requirements are presented, and schedules are
provided to indicate when detailed development
guidance will be forthcoming.
VII
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TABLE OF CONTENTS
Page
DISCLAIMER ii
PREFACE iii
LIST OF TABLES viii
1.0 OVERVIEW OF DOCUMENT 1
1 .1 Purpose 1
1.2 Summary of Document Contents 1
2.0 INTRODUCTION TO INVENTORY REQUIREMENTS 3
2.1 Nonattainment Classifications 3
2.2 Summary of Inventory Types 5
3.0 EMISSION INVENTORY REQUIREMENTS 7
3.1 Inventory Preparation Plans 7
3.2 Base Year Emissions Inventories 11
3.2.1 AIRS Compatible Reporting 14
3.2.2 Geographic Area to be Inventoried . 14
3.2.3 Pollutants to be Inventoried .... 15
3.2.4 Applicable Source Categories .... 15
3.2.5 Updated Mobile Emissions Model
(MOBILE4.1) 15
3.2.6 Updating from 1987/1988/1989 to 1990 16
3.3 Temporal Basis of Emissions 20
3.3.1 Peak CO Season 20
3.3.2 Typical Operating Day Emissions . . 21
3.4 Spatial Allocation of Emissions 21
3.5 Temperature 22
3.6 Rule Effectiveness (RE) and Rule Penetration . 23
3.7 Point Sources 25
3.8 Area Sources 27
3.9 Mobile Sources 28
3.10 Periodic Emission Inventories 29
3.11 Modeling Inventories 30
3.12 Quality Assurance 31
3.13 References 31
Vlll
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TABLE OF CONTENTS
Page
4.0 COMPUTERIZED DATA MANAGEMENT AND REPORTING .... 33
4.1 Point Source Inventory 34
4.2 Point Source Data Elements 37
4.3 Area and Mobile Source Inventory 42
4.4 Area and Mobile Source Data Elements 44
4.5 Format for Area and Mobile Source Data .... 47
5.0 DOCUMENTATION OF THE INVENTORY 48
6.0 BIBLIOGRAPHY 56
APPENDIX A - SUMMARY OF REQUIRED CARBON
MONOXIDE SIP INVENTORIES BY NONATTAINMENT
AREA CLASSIFICATION A-l
APPENDIX B - POINT, AREA, AND MOBILE SOURCE
CATEGORIES NECESSARY FOR CONSIDERATION IN
CO SIP INVENTORIES B-l
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LIST OF TABLES
Page
3-1 Topics to be Included in Inventory Preparation Plans 12
5-1 Outline for EPA Recommended Format/Contents for CO SIP
Emission Inventory Reports 50
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1.0 OVERVIEW OF DOCUMENT
1.1 Purpose
This document describes the emission inventory
requirements that are contained, either explicitly or implicitly,
in the 1990 Clean Air Act Amendments (CAAA) for those areas that
are required to revise their State Implementation Plan (SIP) for
attainment of the National Ambient Air Quality Standard (NAAQS)
for carbon monoxide (CO). The purposes of the document are to
identify the types of inventories required, to describe the
objective and ultimate use of the inventories, and to define
specifications for what data elements must be contained in the
inventories and how these elements must be developed.
1.2 Summary of Document Contents
As noted above, this section presents the purpose of
the document and also provides an overview of the document
organization and contents. The key points and format of the
material presented in the remaining sections of this document are
outlined below.
Section 2.0 presents an introduction to CO SIP emission
inventory requirements under the CAAA. It summarizes the
different CO nonattainment classifications and the general
emission inventory requirements applicable to each
classification.
The specific details of inventory development and
compilation requirements are provided in Section 3.0. The
majority of the discussion is focused on the base year inventory.
Topics such as AIRS (Aerometric Information Retrieval System)
compatible data reporting, geographic areas of inventory
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coverage, pollutants of interest, source categories of interest,
inventory updating, and newly developed tools for inventory
development are discussed. EPA requirements for a new feature,
inventory preparation plans, are presented and fully explained.
In addition, requirements regarding the temporal and
spatial allocation of emissions, the selection of ambient
temperatures, the application of rule effectiveness, and the
definitions of point, area, and mobile sources are discussed.
Section 3.0 also addresses requirements relating to periodic and
modeling inventories and quality assurance provisions.
Section 4.0 discusses the computerized data management
and reporting requirements that have been established by the
Environmental Protection Agency (EPA) for SIP inventories
compiled under the CAAA. These data management provisions apply
to point, area, and mobile data. Section 4.0 details State
requirements relating to the use of AIRS for reporting all SIP
emissions data.
Section 5.0 specifies the manner in which States shall
provide written documentation for their emission inventories.
Requirements for both documentation format and content are
discussed.
Section 6.0 provides bibliographic citations of
currently existing EPA guidance materials for the development of
CO SIP inventories. The list of guidance is divided into four
categories: CO SIP inventory guidance/requirements, quality
assurance/inventory review guidance, emission factors/models, and
general inventory guidance.
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2.0 INTRODUCTION TO INVENTORY REQUIREMENTS
This section of the document summarizes the different
classifications, found in the CAAA of 1990, by which carbon
monoxide (CO) nonattainment areas are delineated. The types of
SIP inventories that are either explicitly or implicitly
contained in the CAAA, according to nonattainment classification,
are also identified in this section. These different types and
their requirements are specified in greater detail in
Section 3.0.
2.1 Nonattainment Classifications
Two classifications are contained in the CAAA for CO
nonattainment areas. These two groupings, known as moderate and
serious, are defined as follows [Section 186(a)(1) ].
CO Nonattainment Classifications
Area Class Design Value (ppm) Attainment Date
Moderate 9.1 to 16.4 December 31, 1995
Serious 16.5 and above December 31, 2000
Even though they are classified as moderate areas, CO
nonattainment areas with design values greater than 12.7 ppm have
more stringent overall requirements than do moderate areas with
values in the 9.1 up to 12.7 range (Section 187). The extra
requirements include compiling additional vehicle miles travelled
(VMT) projections [187 (a)(2)(A)], preparing contingency plans if
projected VMT levels are not met and attainment is not achieved
[187 (a)(2)(B)(3)], establishing enhanced vehicle inspection and
maintenance (I/M) programs [187 (a)(2)(B)(6)], and preparing
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specific plans to demonstrate that attainment and necessary
annual emission reductions will be met [187 (a)(2)(B)(7)].
Specifically, States that have serious CO areas or
moderate CO areas with a design value greater than 12.7 ppm must
comply with the following additional requirements per the CAAA
(unless a waiver is granted through Section 187(c) ).
1. The SIP revision shall contain a forecast of VMT for
each year before the year in which the plan projects
attainment will be reached. The forecast must be based
on guidance to be issued by the EPA Administrator.
Annual updates of the forecasts have to be submitted
together with annual reports regarding the extent to
which such forecasts proved to be accurate. The annual
reports must contain estimates of actual VMT in each
year for which a forecast was required [Section 187
(a) (2) (A)] .
2. The SIP revision plan must provide for the
implementation of specific measures to be undertaken if
any estimate of VMT submitted in an annual report (as
required in No. 1 above) exceeds the number predicted
in the most recent prior forecast, or if the area fails
to attain the NAAQS by the specified date. The
measures shall be included in the plan as contingency
measures to take effect without further action by the
State or the Administrator if the prior forecast has
been exceeded by an updated forecast or if the NAAQS is
not attained by the deadline [Section 187
(a) (2) (B) (3)] .
3. The SIP revision plan must contain provisions for an
enhanced vehicle I/M program as required under CAAA
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Section 182 (c)(3) as it pertains to CO [Section 187
(a) (2) (B) (6)] .
4. The SIP revision must demonstrate that attainment will
be met by the applicable date and that required annual
emission reductions will be met [Section 187
(a) (2) (B) (7)] .
Two 1-year extensions for reaching CO attainment are
available to States if: 1) all SIP requirements and commitments
for an area were met and 2) no more than one exceedance of the CO
NAAQS occurred in the year preceding the extension year [Section
181 (a) (5) and Section 186 (a) (4)] .
2.2 Summary of Inventory Types
For CO nonattainment areas, States must generally
compile three types of inventories. The exception to this
requirement would be moderate CO areas with a design value equal
to or less than 12.7 ppm. These areas are required to compile
only two types of inventories, a base year inventory and periodic
inventories. Moderate areas above 12.7 ppm and serious areas are
required to develop a base year inventory, periodic inventories,
and modeling inventories to comply with CAAA provisions [Section
187 (a)(l), (a) (5), (a) (7) , and 187 (d) (1) ] .
The base year inventory is the primary inventory from
which all other CO inventories are derived. Thus, all
inventories should be consistent with data provided in the base
year inventory. It establishes the basis for determining rate of
progress requirements, and is used as the basis for periodic
inventories and attainment demonstrations. The base year
inventory must reflect actual CO emissions during the 1990 base
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year. More details on the requirements States must meet for the
base year inventory are provided in Section 3.2.
Periodic CO inventories essentially require the same
information as the base inventories. The primary difference
between them is the basis year for the emissions. Modeling
inventories are required for moderate areas above 12.7 ppm and
serious areas because CAAA provisions require such areas to make
attainment demonstrations using air quality dispersion models
[Section 187 (a)(7) and 187 (d)(1) ]. Base year and projected
modeling inventories must be developed. The base year modeling
inventory shall address actual emissions, while the projected
modeling inventory shall be based on allowable emissions, where
they exist.
More detailed specifications of the requirements States
must adhere to for periodic and modeling inventories are provided
in Sections 3.10 and 3.11, respectively. A summary of the
inventory requirements by CO nonattainment classification is
provided in Appendix A.
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3.0 EMISSION INVENTORY REQUIREMENTS
As discussed in Section 2.0, revised carbon monoxide
(CO) SIPs under the CAAA shall include base year, periodic, and
modeling inventories. Emission estimates shall be determined to
the extent possible using source specific information in
conjunction with methodologies described in the inventory
guideline references listed in Section 6.0. One such reference,
Procedures for the Preparation of Emission Inventories for
Precursors of Ozone - Volume I1, is recommended for inventorying
base year CO emissions from stationary sources. A revised and
updated version of this document is scheduled to be issued by EPA
in May 1991 and will address issues specific to CO inventories.
Another reference, Procedures for Emission Inventory Preparation,
Volumes IV: Mobile Sources2 should be referred to for
inventorying base year CO emissions from mobile sources. A
revised and updated version of the mobile sources document is
also scheduled to be issued by EPA in May 1991.
More specifically, States shall be guided by the
requirements described in this section of the document for SIP
inventory preparation under the CAAA. The nature and
requirements of each inventory type are presented and discussed.
Base year inventory requirements and their relation to other
inventories' requirements are discussed in Section 3.2. Specific
requirements for periodic inventories are discussed in Section
3.10, and modeling inventories in Section 3.11. Inventory
elements common to all inventory types (e.g., temporal basis of
emissions, temperature, rule effectiveness, etc.) are discussed
in other parts of Section 3.0. Quality assurance (QA)
requirements for all SIP inventory submittals are discussed in
Section 3.12.
3.1 Inventory Preparation Plans
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Under the previously proposed Post-1987 Ozone/CO
Policy, States were not required to tell EPA how they planned to
prepare, document, and submit their base year emission
inventories prior to the actual submittal of the materials. For
the purposes of the CAAA and their emission inventory
requirements, EPA is adopting a new approach. For CAAA base year
inventories, EPA is requiring that States prepare a brief
Inventory Preparation Plan (IPP) that specifies to EPA how they
intend to develop, document, and submit their inventories. The
plans will give States the chance to tell EPA how they plan to
compile the required inventories, and will allow EPA to provide
feedback to avoid having States use approaches that are not
consistent with EPA requirements. With the use of IPPs, EPA can
help guide the preparation of inventories and attempt to ensure
that emission estimates are of higher quality and are consistent
with the CAAA requirements. States shall submit IPPs to EPA
Regional Offices and EPA Headquarters no later than July 31,
1991. IPPs are due in final form (i.e., agreed upon by EPA) by
October 1, 1991.
In addition to technical data, the IPPs shall contain
schedules for when the States plan to submit draft and final
inventories or inventory components to EPA. If the State plans
to submit an inventory in component pieces (e.g., point source
component, area source component, etc.), the IPP shall clearly
make this distinction and indicate a draft and final submittal
date for each component. The final submittal dates shall be
consistent with the ultimate inventory delivery dates specified
in the CAAA and presented in Section 3.0 of this document.
Multi-State nonattainment areas shall define how they will
coordinate preparation and submittal of the inventories.
Each States shall submit its IPP to its EPA Regional
Office (RO) for review no later than July 31, 1991. Each State
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should also send EPA Headquarters a copy of the document and any
correspondence relating to the plans. EPA Headquarters copies
should be sent to: Chief, Inventory Guidance and Evaluation
Section, Emission Inventory Branch (MD-14), Technical Support
Division, U.S. Environmental Protection Agency, Research Triangle
Park, North Carolina, 27711.
States shall prepare an IPP for each specific
nonattainment area for which a base year inventory is required by
the CAAA, to the extent that different approaches will be used.
If a State has multiple nonattainment areas but plans to use the
same overall approach for each, the State can submit a single IPP
that details that approach and the areas to which it will apply.
States need to be aware that EPA will not accept a base year
inventory for review from a State until EPA has received,
reviewed, and approved an IPP for that inventory. EPA approval
of an IPP does not, however, signify that EPA unconditionally
accepts all of the information to be contained in the actual
inventory. The inventory will be reviewed separately and on its
own merits regardless of how well or how poorly the IPP was
assembled. In approving an IPP submitted, EPA will accept the
intended approach for inventory compilation. The results
produced by these approved approaches will have to undergo a
separate review and approval process.
An IPP shall address how a State plans to inventory all
sources (regardless of size) of CO for CO nonattainment areas.
Separate discussions shall be used to address stationary point,
stationary area, on-road mobile, and non-road mobile sources. If
an inventory started under other programs will be utilized (e.g.,
under the proposed Post-1987 Policy), this should be stated.
Generally, the State's starting point for the base year inventory
effort should be summarized.
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For point sources, States shall define how all
pertinent emission sources will be identified and located.
States shall describe how point source activity levels and
associated parameters will be developed, and how these data will
be used to calculate emission estimates. States must describe
any source surveys that are planned, and if they intend to use
existing data contained in systems such as SAMS (SIP Air
Pollutant Inventory Management System), AIRS (Aerometric
Information Retrieval System), individual State EIS (Emissions
Inventory System), or State permitting files. The extent to
which a State plans to use EPA's AIRS and PC-SAMS data base
management systems to compile their point source inventory shall
be explained.
For stationary area and non-road mobile sources, the
plan shall explicitly state which source categories will be
addressed and which will not be addressed (with justification for
exclusion). For those categories to be included, the plan shall
indicate what calculational method will be used to calculate
emissions. If a State plans on using EPA's inventory guidance
for all categories, it should report that it will be applying the
EPA-recommended approaches. If the EPA guidance has alternative
methods for a category, the IPP should clearly indicate which
method the State intends to use in its inventory. Particular
emphasis should be given to categories for which the State plans
to use an approach other than that recommended in EPA's guidance.
Any major assumptions that will be used that affect the
development of emission estimates in a category shall be clearly
stated.
For on-road mobile sources, the IPP shall provide a
clear indication of how the State intends to develop VMT (vehicle
miles traveled) estimates and mobile source emission factors.
Any predictive models that will be applied shall be identified
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and key assumptions in the use of the models shall be stated.
Other items that shall be addressed include specifications of the
vehicle classes that will be covered, the fuel RVP (Reid vapor
pressure) level to be used or method used to determine RVP, and
inspection/maintenance (I/M) and anti-tampering programs that are
in place.
The IPP must clearly describe how the State plans to
present document, and submit the inventory to EPA. The general
kinds of documentation that will be provided and the form of this
documentation shall be described to the extent that EPA can judge
if it would be satisfactory for inventory review purposes. The
IPP shall specify the written and computerized methods that a
State plans to compile and submit its data, keeping in mind that
States must submit their final SIP inventory data in AIRS or in
an AIRS-compatible format. States must clearly delineate whether
and how State data base/data systems will be used and how data
will be input into the AIRS Facility Subsystem (AFS) and the AIRS
Area and Mobile Source (AMS) Subsystem.
One component that must be contained in an IPP is the
QA plan for the inventory. This plan shall describe the overall
QA program that the State intends to use during the compilation
of the inventory. The QA plan shall be constructed according to
the guidance provided in Section 3.12 of this discussion.
Generally, EPA envisions that the IPPs will be brief.
It is EPA's intent that they be concise and to the point, and
only provide as much detail as is necessary to communicate to the
Agency how the State intends to develop and present its
inventory. However, the document must contain sufficient
information to enable EPA to make a judgment that the intended
State inventory approach is sound and consistent with EPA's
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requirements. Although no specific IPP format is required, the
discussion should include the topics listed in Table 3-1.
3.2 Base Year Emission Inventories
The base year inventory is the primary inventory from
which other CO inventories are derived. It establishes the basis
for determining rate of progress requirements, and is used as the
basis for periodic inventories and attainment demonstrations.
The base year CO inventory is defined in the 1990 CAAA to be a
"current inventory." EPA interprets this to mean an inventory
for 1990 (year of enactment). The inventory shall address actual
CO emissions during the peak CO season for the area. All
stationary point and area sources and on-road/non-road mobile
sources are to be included in the compilation. Peak CO season
shall reflect the three consecutive months when peak CO air
quality concentrations occur. For many, but not all, areas of
the country, the peak CO season will be in the wintertime months.
For areas where winter is the peak CO season, the 1990 base year
inventory shall include the winter months beginning in 1989 and
extending into 1990 (e.g., December 1989 and January-February
1990). Emissions shall be determined for a typical operating day
during the designated peak CO season.
States are required to submit the final base year
inventory for each of their CO nonattainment areas to EPA no
later than November 15, 1992. Attainment demonstrations for
areas above 12.7 ppm are also due by November 15, 1992. In order
to meet this schedule and allow sufficient time for EPA review
and State incorporation of EPA comments, draft base year
inventories should be submitted as soon after January 1, 1992 as
is feasible, but no later than to May 1, 1992.
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TABLE 3-1. TOPICS TO BE INCLUDED IN
INVENTORY PREPARATION PLANS
IPP Topics
A. Introduction
- define what nonattainment area the plan is for, whether
attainment for CO only, or both CO and 03,
classification(s) of the area.
- background/basis for the inventory (i.e., previous
efforts that are viable and related), starting point
- define how the plan is structured, what does it contain
- specify who is responsible for the inventory and who is
actually compiling it (air agency, consultants, etc.)
B. Point Sources Approach
- how will sources be identified and located
- how will minor sources be identified
- define role of existing data (AIRS, NAPAP, permitting
data, etc.)
- identify data collection methods to be used (e.g.,
surveys, etc.)
- basis for activity level data and emission estimates
- basis for control efficiencies
- application of rule effectiveness
- basis for rule penetration and rule effectiveness
levels
C. Area and Non-Road Mobile Sources Approach
- what categories will be addressed and why
- what categories will be excluded and why
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TABLE 3-1. Continued
what estimation methods will be used (e.g., AP-42,
Procedures Document, site-specific surveys, etc.)
- methods for collecting activity/commodity level data
- application of rule effectiveness
- basis for rule penetration and rule effectiveness
levels
D. On-Road Mobile Sources Approach
- specification of how VMT are to be determined
- specification of the mobile source emissions model used
(will be an updated version of MOBILE4)
- specification of key assumptions for the emissions
model involving parameters such as temperature, speeds,
existence of I/M and anti-tampering programs,
incorporation of vehicle refueling losses, etc.
E. Documentation Approach
- written presentation and documentation
- computerized compilations and documentation
- use of AIRS online, PC-SAMS and PC-AMS
- submission of data in AIRS-compatible format
F. Quality Assurance Plan
- description of QA program
- how QA program will affect and benefit inventory
- description of adherence to previously issued QA
guidance
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The remainder of Section 3.2 presents base year
inventory requirements pertaining to factors such as AIRS-
compatible reporting (3.2.1), inventory geographic area (3.2.2),
pollutants to be inventoried (3.2.3), source categories to be
inventoried (3.2.4), an updated version of MOBILE4 (3.2.5), and
inventory updates from 1987/88/89 to 1990 (3.2.6).
3.2.1 AIRS Compatible Reporting
The AIRS will be the official repository for all
emission inventory data. Therefore, all SIP data must be
submitted in an AIRS compatible format in order to be accepted.
The EPA will provide PC software packages for States to perform
preliminary inventory preparation activities (see Section 4.0).
Point source data transfer from the SAMS PC package to the AFS
will be possible beginning in January 1992. Area source data
transfer from the new area and mobile source PC package to the
AIRS Area and Mobile Source Subsystem (AMS) will be available in
May 1992. Specifications for AIRS reporting are detailed in
Section 4.0 of this document.
3.2.2 Geographic Area to be Inventoried
Most geographic areas for CO nonattainment designations
will be defined by EPA by July 13, 1991. These designations will
be made under the provisions of the CAAA, which require each
State to submit to EPA a list of all areas in the State
indicating designations (attainment, nonattainment,
unclassifiable) for CO (or affirming existing designations) and
describing their boundaries. The designations will be published
in Part 81 of the Code of Federal Regulations. All point, area
and mobile sources of CO within the designated nonattainment area
shall be included in the base year emission inventory as well as
the periodic and modeling inventories.
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Modeling demonstrations need to be performed in
designated nonattainment areas with a CO design value that
exceeds 12.7 ppm. This modeling demonstration shall include both
areawide and hot spot modeling. The areawide model shall be
either the RAM or the UAM (Urban Airshed Model). The model
currently proposed for hot spot demonstrations is CAL3QHC. The
hot spot model and its use are described in detail in References
3 and 4.
3.2.3 Pollutants to be Inventoried
Carbon monoxide (CO) is the only pollutant that needs
to be included in the CO SIP emission inventories compiled under
the 1990 CAAA. The inventory shall contain CO emission estimates
and other required data (see Section 4.0) from stationary point
and area, on-road mobile, and non-road mobile sources.
3.2.4 Applicable Source Categories
The types of sources to be included in base year
inventories under the CAAA are essentially the same as those
found in the proposed Post-1987 Policy. Base year inventories
are required to address all stationary point and area sources,
non-road mobile sources, and on-road mobile sources. A tentative
listing of the point, area, and mobile source categories that
must be evaluated for inclusion in the inventory are listed in
Appendix B. Table B-l lists individual point source categories.
Area and mobile source categories are listed in Table B-2. A
final listing will be included in the revised version of the
Procedures Document.1
Formats for reporting 1990 emission inventory data will
differ from previous requirements. Information and requirements
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on formats and systems for base year inventory data reporting are
contained in Section 4.0.
3.2.5 Updated Mobile Emissions Model (MOBILE4.1)
In May of 1991, EPA plans to issue an updated version
of its mobile source emissions estimation model, MOBILE4. The
updated version of MOBILE4 will be known as MOBILE4.1 and will
replace and supersede its predecessor. States are required to
use MOBILE4.1 in determining highway mobile source emissions for
all of their base year emission inventories under the CAAA.
California shall consult with EPA Region 9 in determining the
mobile model to be used. The overall application of MOBILE4.1
for base year inventory purposes is generally the same as that
used for MOBILE4 with the exception of an option to run hour by
hour. The majority of the enhancements in the revised model are
internal to the model and do not directly impact the user for
base year inventory emission factor generation purposes.
Specific guidance on the scope of the model changes and their
impacts, and on the use of the model for base year inventories
will be issued in May 1991.
3.2.6 Updating from 1987/1988/1989 to 1990
Several ozone and CO nonattainment areas that received
SIP calls in 1988 or 1989 have prepared or have begun preparation
of base year emission inventories per the requirements and
guidance in the proposed Post-1987 03/CO Policy (52 FR 45044,
November 24, 1987). These inventories have either 1987, 1988, or
1989 as their base year. For the purposes of the CAAA, these
inventories have to be either updated to 1990, the year of
enactment of the CAAA, or redone totally to reflect a 1990 base
year. States which have fully completed portions of their base
year inventories for 1987, 1988, or 1989 that they desire to
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update and have received EPA approval of these portions will be
considered for approval to update. Otherwise, States shall
prepare a completely new inventory for base year 1990. For the
purposes of accuracy and providing an inventory that will meet
the goals of the CAAA, EPA encourages all areas to prepare new
1990 base year inventories even if they assembled base year
inventories for 1987/1988/1989.
States shall work with their respective EPA RO to
determine if they can perform updates to 1987/1988/1989
inventories that have been prepared, and to determine how these
updates should be performed. Regional Office questions will be
resolved by EPA air headquarters staff [Office of Air Quality
Planning and Standards (OAQPS)]. Before any updating can be
performed on 1987/1988/1989 inventories, States shall receive
written authorization from the appropriate EPA Regional Office
allowing them to do so. EPA will not accept any updated
inventories in cases where this prior authorization is not
received. For nonattainment areas that meet the above stated
conditions, States shall request from their EPA Regional Office
as soon as possible approval to perform an update if the State
does not desire to reconstruct a 1990 base year inventory from
the start. In their petition, States should clearly document the
case for why they should be allowed to perform an update of the
1987/1988/1989 inventory. Once approval to perform an update is
received, the State shall complete and submit an IPP as required
by EPA under the CAAA (see Section 3.1 for details on the IPP
requirements).
For States that are able to perform updates to the
1987/1988/1989 base year inventories, the updating process will
likely be split along the lines of point, area, non-road mobile,
and on-road mobile sources. EPA plans to issue more direct
formal guidance for performing updates (e.g., specific growth
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factors to use on an individual source category basis) in May
1991. However, for the purposes of this guidance discussion, the
following general guidance should be followed.
3.2.6.1 Point Sources
All stationary point sources of CO with emissions of
100 tons/yr or greater shall be re-inventoried completely and not
simply updated. Existing point source guidance in the Procedures
Document (revised version to be issued in May 1991) shall be used
to inventory the major sources. Sources with emissions less than
100 tons/yr can be adjusted to the 1990 base year using scaling
factors based on industrial growth for the category generally or
the plant specifically. The intended approach and source of the
growth factors must be fully explained in the IPP. Such an
approach negates having to resurvey each small CO point source;
however, States are encouraged to re-inventory these sources if
feasible. A new inventory of this type should give more accurate
current emissions data than could be obtained by adjusting older
data with growth factors.
In the one to three year span since the previous base
year inventories were compiled, it is possible that new point
sources could have come into being that need to be added to the
1990 base year inventory. Once new sources are identified, they
should be inventoried according to the updated guidance in the
revised Procedures Document due to be issued in May 1991. For
major sources, additions should be well known to the State/local
agencies. Similarly, major plant shutdowns or curtailments
should be well documented. Other methods that States should use
to identify possible new sources or identify source shutdowns
include reviewing current industrial directories, reviewing
recent permitting records for new plants and existing plant
changes, and reviewing nationally-oriented data bases such as the
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Toxic Release Inventory System (TRIS) for SARA 313 reporting
records.
3.2.6.2 Area and Non-Road Mobile Sources
Practically all of the emission estimates for area and
non-road mobile sources are based on the use of an emission
factor and some activity/commodity level(s) (e.g., population,
employment, equipment counts, etc.) that is a surrogate indicator
of emissions. States can perform updates for these source types
by examining how the surrogate activity levels have changed over
the period to 1990. For most of the source categories, changes
over the one to three year span will not have been large. For
each area and non-road mobile source category, States must
investigate the key emissions surrogate parameters and determine
how they have changed since the previous base year inventories
were developed. The 87/88/89 inventory should be reviewed to
determine what the key emission surrogates are. They will
generally be expressed in the emission factor itself (e.g., Ibs
CO/capita) or in a multi-step calculation process (e.g., pieces
of equipment x hours of operation per piece x Ibs CO/hr of
operation). In some cases, the extrapolation to 1990 will be
very easy to perform because the surrogate statistics are readily
available (e.g., population). In other cases, the State must
determine new data that are very site-specific (e.g., airplane
takeoff/landing cycles at an airport) to the point that the
category is actually being reinventoried as opposed to being
updated.
States are reminded that EPA will be issuing new
inventory procedures guidance for some area and non-road mobile
source categories in May 1991 that may significantly affect how
emissions are to be determined. For these categories (railroads,
aircraft, solvent uses), it will likely not be possible to
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perform updates from the previous estimates. Instead, new
emission estimates shall be prepared using the new methodology.
Furthermore, updated inventories must meet the requirements for
coverage of source categories (Section 3.2.4), data reporting
(Section 4.0), and other basic requirements described herein and
in the revised Procedures Documents (References 1 and 2) to be
issued in May.
3.2.6.3 On-Road Mobile Sources
On-road (highway) mobile source emission estimates must
be derived from scratch using a 1990 base year for all areas,
including those with 1987/1988/1989 base year inventories that
were allowed to update their overall inventory. There are
several reasons EPA is adopting this requirement. One relates to
the way that mobile source models calculate emission factors.
Relatively significant changes occur in the factors with fleet
turnover from one model year to the next. Also, with new road
construction, VMT patterns change that significantly impact
mobile source emissions. These changes may involve not only more
roads, but also changes in speeds both higher and lower. For
example, in 1990, several interstate roads now have 65 mile per
hour speed limits instead of 55. Since the on-road mobile source
component of these inventories is often the major contributor to
total area emissions, it makes sense to reevaluate its emissions
from year to year. The planned release of a new version of the
mobile source emissions estimation model, MOBILE4.1, in May 1991
also provides additional justification for totally reevaluating
mobile source emissions as opposed to application of a growth
factor. [California shall consult with EPA Region 9 in
determining the mobile source model to be used.]
The planned May 1991 release of new guidance for
determining VMT further solidifies the need for States to re-
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calculate on-road mobile source emissions for the purposes of the
1990 base year inventories under the CAAA. States should use the
updated version of MOBILE4 and VMT development guidance to be
issued in May 1991 to construct their 1990 on-road mobile source
inventories. State air agency staff should begin contacting
Metropolitan Planning Office (MPO) personnel (or their
equivalent) to become familiar with the MPO's VMT estimation
methods, base years of data, and overall capabilities, and to
explain to the MPOs the CAAA provisions.
3.3 Temporal Basis o£ Emissions
The temporal basis on which CO emissions must be
expressed for 1990 base year inventories under the CAAA is the
peak CO period of the year for each nonattainment area.
Generally, emissions must be reflective of a typical operating
day during the peak CO season. More specific guidance is
provided below for determining peak CO season and typical daily
emissions.
3.3.1 Peak CO Season
Peak CO season should reflect the months when peak CO
air quality concentrations occur. States shall define their peak
CO season to be the three contiguous months when the highest CO
NAAQS exceedance episode days occur. This determination shall be
based on ambient data for the last three to four years. For
many, but not all, areas of the country, the peak CO season will
be in the wintertime months. For areas where winter is the peak
CO season, the 1990 base year inventory will include the winter
months beginning in 1989 and extending into 1990 (e.g., December
1989 and January-February 1990) .
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Source category activity data must be developed that
are correlated with the peak CO season as defined for each
nonattainment area. States should determine their peak CO season
prior to assembling their IPP. The peak CO season shall be
defined in the IPP and a brief documentation given for the period
selected.
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3.3.2 Typical Operating Day Emissions
For CO nonattainment area base year inventories,
emissions must be determined and expressed on the basis of an
average operating day during the peak CO season. A typical
operating day shall consist of a 24-hour period. Additional
procedural guidance on how to determine operating day emissions
will be provided in the updated procedures document guidance to
be issued in May 1991. For those CO nonattainment areas required
to do modeling, operating day emissions must be further allocated
to an hourly basis, as discussed below.
If the CO design value for the nonattainment area is
less than 12.7 ppm CO, a 24-hour daily CO emissions estimate is
acceptable. However, if the design value is greater than 12.7
ppm, hourly CO emission estimates are required for modeling
purposes. The required techniques for control strategy
demonstrations for areas exceeding the 12.7 ppm design value are
the RAM Model5 or the UAM.6 Guidance on deriving hourly emission
estimates for the representative operating day in the peak CO
season can be obtained from the dispersion modeling guidance
document Procedures for the Preparation of Emission Inventories
for Volatile Organic Compounds. Volume II: Emission Inventory
Requirements for Photochemical Air Quality Simulation Models.7
Although this document was prepared specifically for temporally
allocating VOC emissions, this is generally applicable to CO
emission sources as well. The revised version to be issued in
May 1991 will address CO modeling specific issues.
3.4 Spatial Allocation of Emissions
If the nonattainment area has a design value less than
or equal to 12.7 ppm CO, a countywide emissions inventory is
acceptable. If the design value of the area is greater than 12.7
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ppm CO, then the control strategy demonstration must be performed
with the RAM Model or the UAM. If the RAM Model is used for
control strategy demonstrations, mobile and area sources need to
be allocated to square grid cells within the modeling domain that
covers the geographic area of the inventory discussed in Section
3.2.2 of this document. The size of the grid cells used in the
RAM Model can vary over the modeling domain. The recommended
grid square sizes are from 1 to 5 kilometers (km), with a 1 km
grid square recommended for the central business district (CBD)
of urban areas and larger grid squares recommended for areas
outside the CBD. Dispersion models such as the RAM model require
that point sources be allocated to the exact location in
Universal Transverse Mercator (UTM) coordinates and that stack
parameters (e.g., height, diameter, exit velocity, and exit
temperature) be specified for input.
Guidance on preparing a spatially resolved emissions
inventory for dispersion modeling is contained in Procedures For
The Preparation Of Emission Inventories For Volatile Organic
Compounds. Volume II: Emission Inventory Requirements For
Photochemical Air Quality Simulation Models.7 Again, although
this document was prepared specifically for spatial allocation of
VOC emissions, the guidance is generally applicable to CO
emissions.
The spatial allocation requirements for the UAM are the
same as those for the RAM Model with one difference. The
difference is that the grid square size for allocation of mobile
and area sources needs to remain constant over the modeling
domain for the UAM. The recommended grid square size for UAM is
from 2 to 5 kilometers. The choice of grid square size depends
on the size of the area being modeled, the resources available
for modeling, and the degree of resolution needed to determine
the effects of a particular control strategy.
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3.5 Temperature
The MOBILE4.1 model requires that temperature be
entered as a key variable to the model's estimation of CO
emission factors for mobile sources. States must determine the
temperatures, for calculational purposes, that are appropriate
for the peak CO season they have defined. Furthermore, hourly
temperatures are required for input to the UAM for episode day
modeling. Guidance concerning temperature determinations will be
issued in the updated procedures guidance documents in May 1991.
3.6 Rule Effectiveness (RE) and Rule Penetration
Past inventories have assumed that regulatory programs
would be implemented with full effectiveness, achieving all of
the required or intended emission reductions and maintaining that
level over time. However, experience has shown regulatory
programs to be less than 100 percent effective for most source
categories in most areas of the country. The concept of applying
rule effectiveness in the SIP emission inventory has evolved from
this observation. In short, RE reflects the ability of a
regulatory program to achieve all the emission reductions that
could be achieved by full compliance with the applicable
regulations at all sources at all times.
Several factors should be taken into account when
estimating the effectiveness of a regulatory program. These
include: (1) the nature of the regulation (e.g., whether any
ambiguities or deficiencies exist, whether test methods and/or
recordkeeping requirements are prescribed); (2) the nature of the
compliance procedures (e.g., taking into account the long-term
performance capabilities of the control); (3) the performance of
the source in maintaining compliance over time (e.g., training
programs, maintenance schedule, recordkeeping practices); and (4)
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the performance of the implementing agency in assuring compliance
(e.g., training programs, inspection schedules, follow-up
procedures).
Rule effectiveness shall be applied for stationary
sources that are affected by a regulation and for which emissions
are determined by means of emission factors and control
efficiency estimates. No rule effectiveness factor is needed in
cases where no control is applied or there is no applicable
regulation.
In the proposed Post-1987 Ozone/CO policy, it was
stated that a factor of 80 percent should be used to estimate RE
in the base year inventories for most point and area sources.
For the purpose of base year CO inventories under the CAAA, EPA
will allow the use of the 80 percent default value, but will also
give States the option to derive local category-specific RE
factors according to guidance contained in Reference 8.
The RE factor shall be applied to the estimated control
efficiency in the calculation of emissions from a source. An
example of the application is given below.
Uncontrolled emissions = 50 Ibs/day
Estimated control efficiency = 90%
Rule effectiveness = 80%
Emissions after control = 50 [1 - (0.90) (0 . 80) ]
=50 [I - (0.72)]
= 14 Ibs/day
Thus, the application of RE results in a total emission reduction
of 72 percent.
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Fuels programs, such as local controls on volatility,
should be adjusted for effectiveness because of a number of
assumptions regarding market penetration, compliance, etc.
associated with implementation of such programs. States should
contact their EPA Regional Office for guidance on how to adjust
the base year inventory for the effectiveness of these programs.
In addition to RE, another important regulatory
consideration is the extent to which a regulation may cover
emissions from a source category. When estimating emissions
using methodologies for source categories where a rule or
regulation applies, agencies shall incorporate an estimate of the
amount of rule penetration by means of the following formula:
Rule Uncontrolled emissions
Penetration = covered by the regulation x 100 percent
Total uncontrolled emissions
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Once uncontrolled emissions and rule penetration are
determined, RE should be applied as discussed above. An example
of how to incorporate both penetration and RE in the same source
category follows.
Uncontrolled emissions = 100,000 tpy
Control efficiency required by the regulation = 95
percent
Rule penetration = 60 percent
Rule effectiveness = 80 percent
Emissions from the category =
(100,000) [1 - (0.60) (0.95) (0.80)] = 54,400 tpy
Further discussions of the use of rule effectiveness and rule
penetration are included in Reference 8.
3.7 Point Sources
Although a revised version of the procedures document
for CO is scheduled for release in May of 1991, the guidance for
inventorying point sources of CO has essentially not been changed
from what was contained in the document Procedures for the
Preparation of Emission Inventories for Precursors of Ozone.
Volume I1 (EPA 450/4-88-021, December 1988). For this reason,
States should immediately begin data gathering for the
development of the point source component of their base year
inventories. There is no reason to postpone data gathering and
development because no new guidance is planned for point sources
that will significantly affect States' 1990 base year inventory
efforts. Some refinements and enhancements may be issued to the
previous guidance for selected source categories, but this
information will not affect the basic activity data that States
need to be collecting on individual point sources. States are
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encouraged to submit the point source portion of the inventory to
EPA as early as January 1, 1992.
As under the previously proposed Post-1987 Policy, the
point source emissions cutoff definition for CO sources is 100
tons/yr. While sources with emissions at these levels and above
must be inventoried as individual point sources, States are
encouraged to inventory sources below these cutoffs on an
individual point source basis as well. Smaller CO sources may
either be inventoried as individual point sources or aggregated
in the area source component of the base year inventory.
Detailed process and emissions data shall be collected and
reported for each CO point source that emits 100 tons per year or
more. A summary listing of plant names, locations and total
plant emissions (tons/day) is required for sources of CO that
emit at least 100 tons per year.
The 100 ton/yr cutoff level is not necessarily
consistent with the "major source" delineations given in the CAAA
for CO sources. This is because the two types of cutoffs are to
be used for different purposes. In several cases, the CAAA have
established other major source cutoff definitions for purposes
such as the application of RACT (reasonably available control
technology), for new source review, and for Emissions
Statements. For example, in serious CO nonattainment areas,
major sources are defined as those with the potential to emit 50
tons/yr CO. However, because these other lower cutoffs do exist,
States should consider the benefits of going ahead and
inventorying sources of CO below 100 tons/yr if possible.
New point sources that have come into being since the
previous base year inventory was compiled need to be included in
this base year inventory. For major sources, additions should be
obvious and well known to the State/local agencies. Similarly,
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major plant shutdowns or curtailments should be well documented.
Other methods that States may use to identify possible new
sources or identify source shutdowns include reviewing current
industrial directories, reviewing recent permitting records for
new plants and existing plant changes, and reviewing nationally-
oriented data bases such as the TRIS for SARA 313 reporting
records. Again, the methodologies to be used should be specified
in the IPP.
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3.8 Area Sources
Area sources include those emissions from stationary
and non-highway sources that are too small and/or too numerous to
be included in the point source inventory, but which can
contribute collectively to CO nonattainment. One such source
category is residential fuel combustion, including woodstoves and
fireplaces. For source categories such as this, all sources may
be addressed as area sources in the inventory because of the
difficulty in identifying the few operations that may be major
emitters.
In a number of previous SIP submittals, emissions from
many small sources have been left out of inventories because of a
lack of available procedures or lack of emphasis on this portion
of the inventory. Existing methodologies can be used to estimate
emissions from the various area source categories. Detailed
procedures are discussed in Reference 1. However, some of these
techniques are briefly described herein for emphasis.
Emissions from certain area source categories may be
estimated on a per capita basis. This procedure may be necessary
when the availability of other area source estimating
methodologies is limited. Population estimates used in making
such emission estimates should be documented. Specific
information on per capita factors is contained in Reference 1.
Another area source procedure essentially uses
nationally derived emissions-per-employee factors to calculate
emissions from sources in an area based on areawide employment
data. The procedure is best utilized for those source categories
where (a) total employment in the source category is known for
the area, and (b) where there are numerous sources whose
emissions are typically less than the cutoffs mentioned above for
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point sources, but whose collective emissions represent a
significant total.
When compiling their area source inventories, States
should also be aware that EPA's JEIOG has identified some new
area source categories that were previously uninventoried for CO
emissions. These area sources must be addressed in the 1990 base
year inventories. The new area source guidance material will be
issued in May 1991 as a part of the updated procedures guidance
document.
3.9 Mobile Sources
Mobile sources consist of two types, on-road mobile
sources (e.g., automobiles, trucks, motorcycles) and non-road
mobile sources (e.g., trains, airplanes, agricultural equipment,
industrial equipment, construction vehicles, off-road
motorcycles, marine vessels, and other site-specific vehicles).
Guidance on this issue can be found in Reference 2.
The on-road mobile sources portion of the inventory
must include a detailed accounting of vehicle emissions in the
designated nonattainment area. Emissions from local traffic, as
well as emissions from traffic on major highways, must be
included in the analysis. On-road mobile source emissions shall
be derived by multiplying VMT by MOBILE4.1 emission factors. The
base year for the VMT shall be 1990. Specifications on the
required use of MOBILE4.1 variables such as temperature, speed,
etc. will be provided in the May 1991 procedures guidance.
States must determine VMT by the procedures specified
by EPA. In May 1991, EPA will be issuing new inventory
procedures guidance that contains updated methods for determining
on-road vehicle VMT. States shall be required to use the new
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procedures to produce their 1990 base year inventories under the
CAAA. The new VMT guidance to be issued in May represents an
update to that contained in Reference 2 for deriving on- road
vehicle VMT.
States shall present on-road mobile source CO emissions
by individual county (or other equivalent basis) within the
nonattainment area, as well as by vehicle class and by roadway
type. States shall also report MOBILE4.1 input and output data
and a discussion of how VMT estimates were developed (see Section
4.0 and 5.0). For modeling inventories, mobile source data (as
well as point and area source data) such as VMT, temperature and
emissions, must be developed on a gridded, hourly basis.
Emissions from most non-road mobile sources are
determined based on a source activity variable that is a
surrogate indicator of emissions. Activity levels for each
non-road category shall be developed using revised guidance to be
issued in May 1991 (Reference 2) .
In May 1991, as a part of EPA's updated procedures
guidance, new inventorying procedures will be presented that
States shall use to develop non-road emissions estimates for
trains and airplanes . The new procedures for trains and
airplanes are required for the 1990 base year inventories.
3 . 10 Periodic Emission Inventories
As identified in Section 2.0, States are required to
develop and submit to EPA periodic CO emission inventories.
Periodic CO inventories shall require essentially the same
information as the base year CO inventory. The primary
difference between them is the basis year for the inventory. The
first periodic inventory must be based on 1993 emission rate and
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activity level information [Section 187 (a)]. It is due in final
form to EPA no later than September 30, 1995, and subsequent ones
no later than the end of each 3-year period thereafter, until the
area is redesignated to attainment [Section 187 (a)(5)].
Periodic CO inventories must address actual CO emissions during
the CO season on a typical daily basis. Emission estimates shall
be prepared according to the general procedures for base year
inventories outlined in Section 3.2.
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3.11 Modeling Inventories
Modeling inventories are necessary for CO because of
CAAA provisions that require Attainment Demonstrations to be made
for certain CO nonattainment areas [Section 187 (a)(7) and
187(d)(1) ]. Moderate areas exceeding a design value of 12.7 ppm
must submit an attainment plan before November 15, 1992 that
projects how attainment will be achieved by December 31, 1995.
The same requirement exists for serious areas except that
attainment must be demonstrated by December 31, 2000. Base year
and projected modeling inventories will be needed. Base
inventories are used for evaluating model performance while
projected inventories are used as "future base cases" upon which
additional control strategies are superimposed in an attainment
demonstration.
This modeling demonstration shall include both areawide
and hot spot modeling. The areawide model should be either the
RAM or the UAM. The model currently proposed for hot spot
demonstrations is CAL3QHC. The hot spot model and its use are
described in detail in References 3 and 4. EPA will provide more
direction to States on areawide modeling in the near future.
The CO base year modeling inventory shall represent
actual emissions representative of the base year episodes
selected for modeling. Emissions would be determined for an
average 24-hour operating day during the peak CO season. See
Sections 3.3 and 3.4 for a discussion of temporal and spatial
reporting of emissions for modeling inventories. All stationary
point and area sources and all mobile source types must be
included in the inventory. Activity levels and production data
used to calculate emissions should represent actual data.
Conversely, the projection modeling inventory would be based on
allowable emissions dictated by regulatory limits, and not actual
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emissions. The emission levels in effect will represent the
results that State expects from its SIP control strategies.
Activity levels used to estimate emissions should be those
expected in the future attainment year (i.e., 1995 for moderate
areas or 2000 for serious areas).
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3.12 Quality Assurance
States are required to design and implement a quality
assurance (QA) program to enhance the overall reliability and
accuracy of the CO SIP emission inventories prepared in response
to the CAAA. States must design a QA program and prepare a QA
plan that is consistent with the previously issued guidance
document: Guidance for the Preparation of Quality Assurance
Plans for 0,/CO SIP Emission Inventories9 (EPA 450/4-88-023).
States are required to submit QA plans as an initial step in
their inventory development work and receive EPA approval on
their plans early on in the process. The QA plans must be
submitted no later than July 31, 1991, as a part of a State's IPP
which is a new requirement for the 1990 base year inventories.
The full provisions and requirements of the IPPs are explained in
Section 3.1. The content and general form of QA plans must be
consistent with the previously issued guidance.
As an aid to States in the preparation and checking of
their inventories prior to submittal to EPA, the Agency has been
preparing a set of quality review guidelines. These guidelines
will contain what is essentially a checklist of items that an
inventory must contain or address in order for the inventory to
be considered acceptable for review by EPA. The guidelines will
address whether inventories meet developed specifications for
completeness, consistency (both internal and with national
trends), reasonableness of emission values, and emissions
documentation. EPA is planning to issue the final review
guidelines in July 1991.
3.13 References
1. Procedures For The Preparation Of Emission Inventories
For Precursors Of Ozone. Volume I. EPA-450/4-88-021,
Third Edition, U. S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research
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Triangle Park, NC, December 1988. Revised version to
be issued May 1991, will supersede this guidance.
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Procedures For Emission Inventory Preparation. Volume
IV: Mobile Sources. EPA-450/4-81-026d, U. S.
Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle Park, NC,
July 1989. Revised version to be issued May 1991, will
supersede this guidance.
User's Guide to CAL30HC - A Modeling Methodology for
Predicting Pollutant Concentrations Near Roadway
Intersections. Parsons Brinckerhoff Quade and Douglas,
Inc., New York, NY. September 1990.
Guideline for Modeling Carbon Monoxide from Roadway
Intersections (Draft Report). Schewe, G. J., et al.
PEI Associates, Cincinnati, Ohio. October 1990.
User's Guide for RAM - Second Edition.
EPA-600/8-87-046. U. S. Environmental Protection
Agency, Research Triangle Park, NC. October 1987.
User's Guide for the Urban Airshed Model - Volume I:
User's Manual for UAM (CB-IV). EPA-450/4-90-007a.
Systems Applications, Inc., San Rafael, CA, and U. S.
Environmental Protection Agency, Research Triangle
Park, NC. June 1990.
Procedures For The Preparation Of Emission Inventories
For Volatile Organic Compounds. Volume II: Emission
Inventory Requirements For Photochemical Air Quality
Simulation Models. EPA-450/4-79-018, U. S.
Environmental Protection Agency, Research Triangle
Park, NC, September 1979. Revised version to be issued
May 1991, will supersede this guidance and will address
CO specific issues.
Procedures For Estimating And Applying Rule
Effectiveness In Post-1987 Base Year Emission
Inventories For Ozone And Carbon Monoxide State
Implementation Plans. U. S. Environmental Protection
Agency, Office of Air Quality Planning and Standards,
Research Triangle Park, NC,
June 1989.
Guidance For The Preparation Of Quality Assurance Plans
For 03/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.
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4.0 COMPUTERIZED DATA MANAGEMENT AND REPORTING
Emission inventory information for base year, periodic,
and modeling inventories under the CAAA shall be provided to EPA
in both written and computerized formats. Computerized
submittals of emissions data and documentation must meet the
specifications set forth by EPA's National Air Data Branch
(NADB). The computerized submittals are discussed in this
Section, while the written reporting/documentation requirements
are summarized in Section 5.0.
Computerized submittals must be input to the Aerometric
Information Retrieval System (AIRS), with point source data on
the AIRS Facility Subsystem (AFS) and area and mobile source data
on the Area and Mobile Source Subsystem (AMS). If States do not
input State Implementation Plan (SIP) inventory data directly to
AIRS, then they must submit data in a computer-readable
AIRS-compatible format. Methods for providing AIRS-compatible
formats are discussed in this section. AIRS transactions
submitted by States will be updated to AIRS by EPA Regional
Offices which will then provide the States with printed reports.
States will review these reports and correct any errors before
final EPA confirmation of inventory completeness is given.
States are advised to establish internal coordination
procedures to eliminate potential conflicts between the
submittals of their SIP data to AFS and their other regular
submittals of compliance and emissions data to AFS. Some SIP
data elements will be uniquely "owned" by SIP emission inventory
users who submit data to AFS. Other data elements in AFS will be
shared in common with other State or local agency users who
submit other emissions or compliance data to AFS. The AFS
security procedures will permit only authorized users to update
the data base. Where data element ownership is shared by SIP
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emission inventory users, and other emissions and compliance
users, the updating of a data element by different users is
possible at different times. Effective internal coordination by
States is necessary to insure that data reported to meet a SIP
requirement do not conflict with or inappropriately change data
that have been reported to AFS by other State personnel. For
emissions data, the data elements contained in the previous
National Emissions Data System (NEDS) can be reported to AFS as
batch data updates. States who are direct users of AFS may also
perform online updates to the AFS database. The SIP submittals
made by States using SAMS (SIP Air Pollutant Inventory Management
System) or AFS batch transactions (see following subsection)
should not contain transactions that change emissions data values
for pollutants not required for the SIP inventory (such as PM10
or S02, for example) unless the submittal of such data has been
coordinated with and approved by the persons who normally submit
such data. Similarly, changes to other shared emissions data
elements such as latitude/longitude or UTM coordinates, stack
parameters and common point general and segment general level
data elements should be coordinated with other emissions
inventory personnel to insure that SIP data updates do not
improperly change their data.
For compliance data, the only data elements that are
shared by SIP inventory and compliance users are the plant name,
street address, city code and city name, ZIP code and SIC codes
on the plant general level. SIP inventory personnel must
coordinate with compliance personnel to insure that inappropriate
changes to these data elements do not occur as the result of a
SIP inventory data submittal to AFS.
Various submittal mechanisms will be available for the
States to fulfill their inventory requirements. The information
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below addresses inventory data management issues for point, area,
and mobile sources.
4.1 Point Source Inventory
States submitting point source inventories can choose
one of four basic options to submit their data:
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Option When Available
(1) SAMS Version 3.I1 Now
(2) SAMS Version 4 . O2 Now
(3) AFS Batch Transaction
Format Available3 May 17, 1991
(4) Interactive direct entry
to AFS December 31, 1991
NOTES: (1) SAMS Version 3.1 (used for the Post-87 SIP
inventories). If currently using Version 3.1,
States should update to SAMS Version 4.0 to
achieve compatibility of data format with AFS (see
discussion below).
(2) SAMS Version 4.0 which includes additional data
elements (Stack-ID and Segment-ID) and edits to
ensure compatibility with AFS. A later version of
SAMS, Version 4.1, will include the capability to
generate an AFS formatted transaction file
(available mid-July 1991).
(3) This format must be used by States submitting data
electronically from their own computer system
directly to EPA's mainframe.
Option (1)
States may have already begun work to update their
inventories to 1990 by using SAMS Version 3.1. However, prior to
uploading to AFS, reconciliation of SAMS 3.1 data with the AFS
data structure at the stack and segment levels of related
SAMS/AFS facilities will be required. SAMS Version 4.0 allows
entering this additional information thereby reducing to a
minimum the data conversion process from SAMS to AFS.
Information relative to the required data elements for the
inventory is also provided in this guidance document.
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If States are currently using SAMS Version 3.1, please
contact John Ackermann of NADB at (919) 541-5687 (FTS 629-5687)
to discuss the data reconciliation process and issues.
Option (2)
SAMS Version 4.0 can be installed on a PC so that it
can be used to update a SAMS data base prepared with an earlier
version. By using the new data elements and AFS-edit routine in
Version 4.0, the SAMS user can prepare 1990 SIP data on SAMS (PC)
that will be consistent with their State's files on AFS
(mainframe). The National Air Data Branch has developed
AFS computer printout reports that can assist State and local
agencies in the identification of AFS stack and segment ID
numbers for input to SAMS Version 4.0. These reports (AFS Quick
Look reports) may be obtained from EPA Regional Office AFS
Emissions Contacts or by contacting Jerry Husketh of NADB at
(919) 541-5449 (FTS 629-5449). Names and phone numbers for the
Regional Office contacts can be obtained by calling Jerry Husketh
at the number above.
There will be a later release of SAMS Version 4.1,
available in mid-July 1991. This newer version will provide a
capability to generate AFS-acceptable transactions as an output
from SAMS. The AFS-formatted transaction data from SAMS will be
uploaded to the EPA IBM mainframe and then updated to AFS. EPA
will review the submitted inventory prior to updating the AFS
files. The updating of AFS will begin in January 1992.
Option (3)
States submitting an AFS formatted transaction file to
EPA (format definitions will be provided in May 1991) can either
mail a magnetic non-labeled tape or transmit a data set (if State
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has appropriate connectivity and technical resources) to the
National Computer Center. Tape submitted data should be
structured in IBM extended binary coded decimal interchange code
(EBCDIC). The loading of the transaction files to AFS will begin
in January 1992. Contact Jerry Husketh of NADB at (919) 541-5449
(FTS 629-5449) for more information.
Option (4)
In the long-term, the preferred option is to enter the
SIP inventory point source data directly into AFS. However, this
option will not be available to users until January 1992.
Contact John Ackermann at (919) 541-5687 (FTS 629-5687) or Jerry
Husketh at (919) 541-5449 (FTS 629-5449), NADB, if States plan to
use this approach.
4.2 Point Source Data Elements
Applicable data elements that will be supported by AFS
are as follows. Data elements required for the ozone/CO
inventories are shaded. These data elements are more explicitly
defined in documentation for SAMS Version 4.0 and will be further
defined with the specification of AFS batch transaction formats
to be provided in May 1991.
List of Data Elements for Plant General Level:
Description
**FIPS state code1
**FIPS county code1
*year of record for emissions
**plant ID from AFS (or NEDS)
*plant name
*street address
*city name2
*zip code
local plant ID
*FIPS city code1'2
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*plant latitude3
*plant longitude3
*UTM zone3
*UTM easting3
*UTM northing3
township/modeling grid
*primary SIC code
secondary SIC code
tertiary SIC code
principal product
number of employees
plant area
plant contact
contact telephone number
type of inventory
plant comment
* Mandatory for AFS format, for Adds.
** Mandatory for both Adds and Changes to AFS.
for FIPS codes: While SAMS currently uses SAROAD
codes, these will be converted to FIPS codes by SAMS
software when AFS transactions are created by SAMS
users. States that generate AFS transactions from
other software must use FIPS codes.
2Note for city: enter data for either city name or
FIPS city code but not both. If city code is reported
to AFS, this will be used to generate a city name and
the city name field entry will be ignored. SIP
inventory users in New England States are requested to
report the FIPS city code if possible. This will
permit AFS to generate the appropriate Metropolitan
Statistical Area (MSA) codes for those States. Except
for New England States, the MSA code can be generated
from county codes so that city code is not necessary.
3Note for plant location: enter data for either
lat/long or UTM, but not both. For cases where both
are reported, UTM data will be used to update AFS and
lat/long data will be ignored.
List of Data Elements for Point General Level
Description
**FIPS state code
**FIPS county code
**plant ID from AFS (or NEDS)
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**point ID from AFS
local point ID
hours per day
days per week
hours operated per year
start time (each workday)
end time (each workday)
percent throughput - Dec. thru Feb.
percent throughput - March thru May
percent throughput - June thru Aug.
percent throughput - Sept. thru Nov.
boiler capacity
space heat percentage
point comment
** Mandatory for both Adds and Changes to AFS
List of Data Elements for Point Pollutant Level
Description
**FIPS state code
**FIPS county code
**plant ID from AFS (or NEDS)
**point ID from AFS
**pollutant code or CAS code
measured emissions at point
emission measurement method code
measured emissions units
SIP regulation in place for point
compliance year for point
emission limitation for point
emission limitation value
emission limitation units
** Mandatory for both Adds and Changes to AFS.
List of Data Elements for Stack Level:
Description
**FIPS state code
**FIPS county code
**plant ID from AFS (or NEDS)
**stack ID from AFS
*stack height (ft)1-3
*stack diameter (ft)1'3
*plume height (vent height, ft)1-3
latitude for stack2'3
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longitude for stack2'3
UTM easting for stack2'3
UTM northing for stack2'3
temperature of exit gases (F)
exhaust gas flow rate (ACFM)
exit gas velocity (ft/sec)
* Mandatory for AFS format, for Adds.
** Mandatory for both Adds and Changes to AFS.
required either to enter stack height and
stack diameter or to enter plume height (vent
height).
2Note: for Stack location (if different from Plant),
enter either lat/long or UTM, but not both.
3Note: required for AFS only if a stack exists and
stack
ID has been entered; for SIP inventories, this
parameter is
not required if no stack exists or if photochemical
modeling
is not required for an attainment demonstration.
List of Data Elements for Segment General Level
Description
**FIPS state code
**FIPS county code
**plant ID from AFS (or NEDS)
**point ID from AFS
** segment ID from AFS
*SCC number
sulfur percentage
ash percentage
heat content
confidentiality
process rate units
actual annual process rate2
maximum design rate2
03 season process rate (daily)2
CO season process rate (daily)2
stack ID related to this segment1
segment comment
* Mandatory for AFS format, for Adds.
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** Mandatory for both Adds and Changes to AFS .
: required for AFS only if a stack exists; for
SIP inventories,
this parameter is not required if no stack exists or
if photochemical
modeling is not required for attainment demonstration.
2Note : these parameters must be provided unless they
are deemed to
be confidential or their reporting is prohibited by
State law.
List of Data Elements for Segment Pollutant Level:
Description
**FIPS state code **FIPS county code
**plant ID from AFS (or NEDS)
**point ID from AFS
**segment ID from AFS
**pollutant code or CAS code
primary control device code1
secondary control device code1
control efficiency1
SIP regulation in place for segment
compliance year for segment
emission limitation description for segment
emission limitation value
emission limitation units
emission estimation method
emission factor2
seasonal adjustment factor
annual nonbanked emissions (estimated actual)
annual banked emissions
rule effectiveness3
03 season emissions (Ib/day)
CO season emissions (Ib/day)
** Mandatory for both Adds and Changes to AFS.
•"•Note: required for SIP inventories only when a
control device exists.
2Note: required for SIP inventories only when the
emission estimation
method code indicates that an emission factor was used
(i.e., method
codes 3 and 5 for SAMS reporting or method code 9 for
AFS batch
50
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format reporting). For other method codes, an
emission factor does not
apply and is not required.
3Note: required for SIP inventories only when rule is
in place that affects
emissions of the pollutant.
4.3 Area and Mobile Source Inventory
The NADB is developing a new AIRS subsystem to handle
the area and mobile source inventories. The new mainframe
software is called AMS and will facilitate State data entry,
update, and access to area source data. Since AMS will not be
able to upload State data in formatted transactions until May
1992 (AMS "National" capability by November 1992), AMS data entry
software is being developed on a personal computer (PC).
States have three basic options to submit their area
source data. However, please note that option 3 will not be
available in time for the draft area and mobile source inventory
submittals but could be used for final base year submittals or
periodic inventory updates.
Option When Available
(1) AMS-PC Version 1.0 June 28, 1991
(2) AMS Batch Transaction
Format Available July 31, 1991
(3) AMS Mainframe Interactive
Direct Entry May 29, 1992
Option (1)
The AMS-PC package will be available to the States by
June 28, 1991. States may use the AMS-PC package to submit their
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1990 base-year inventory for area and mobile sources. The AMS-PC
Version 1.0 will be a basic data-entry system for State-prepared
emissions values, and will have only minimal calculation
capabilities. The AMS-PC package will be compatible with the
mainframe AIRS AMS in categories, codes, and edits, and will be
consistent with EPA's guidance for SIP 1990 base-year
inventories. Note that SAMS Version 4.0 and Version 4.1 will not
provide the appropriate categories and formats to develop the
1990 area source or mobile source inventory; therefore, SAMS
cannot be used for the purpose of submitting AMS inventory data.
Option (2)
States planning to transmit a computer generated data
set or magnetic tape file will need to supply data in EPA's AMS
batch transaction format. This format will be defined and
distributed to the States in July 1991. Tape submitted data
should be structured in IBM EBCDIC.
AMS transactions generated from the AMS-PC and AMS
batch transactions generated and submitted from State computers
will be updated to the AMS mainframe data base. The capability
to update this SIP data to the mainframe is scheduled for May
1992. During the period of January through May, 1992, the
Technical Support Division will provide assistance with basic
edits and review of draft inventories submitted as AMS batch
transactions from State computers. The Regions and the States
will receive additional information and guidance regarding area
and mobile source procedures in the near future. State personnel
should contact John Ackermann or Sue Kimbrough of NADB to
indicate what type of approach will be used for their area and
mobile source inventories.
Option (3)
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The AMS mainframe data entry capability for area and
mobile source data will be available in May 1992. States will be
able to do corrections, updates or projections interactively to
base year data existing or imported into AMS. States planning
to use this approach will need AMS training and should coordinate
their submittal plan with Sue Kimbrough of NADB, at (919) 541-
5457 (FTS 629-5457).
4.4 Area and Mobile Source Data Elements
Area and mobile source data should be reported either
using AMS or in a computer readable format compatible with AMS,
as stated previously. A tentative list of data elements to be
supported by AMS is included below. This list does not cover the
bulk of the on-road mobile source data elements (e.g., inputs to
and outputs from the MOBILE model) that will be required with the
inventory submittal. AMS data elements and formats (including
on-road mobile source data) will be defined more explicitly in
AMS documentation to be finalized by July 31, 1991. Shaded data
elements are required for SIP emission inventories.
List of Data Elements for Source Category Level:
Provider (EPA or State)
Inventory Type (Base Year, RFP Projection, etc)
Base Year
State Code
County Code
City Code
Zone (for City or County Subdivision)
Source Category (from valid EPA AMS Source Classification Codes)
Activity Level (annual quantity consumed, produced, etc. -
associated with emissions)
Activity Level Units (units of measure for activity level - e.g.,
cubic feet, tons, employees, VMT)
Activity Level Process (burned, produced, consumed, etc.)
Activity Level Method (EPA SIP, State, etc.)
Activity Level Origin (Input by user, calculated, etc.)
Activity Level Limit (maximum activity allowed by regulation)1
Activity Level Limit Units1
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Activity Level Limit Process1
Ash Content Percent
Sulfur Content Percent
Comment
•"•Note: Required for SIP inventories only when the
activity level is limited by regulation.
List of Data Elements for Pollutant Level:
Provider
Inventory Type
Base Year
State Code
County Code
City Code
Zone
Source Category
Pollutant Code
Emission Factor
Emission Factor Decimal
Emission Factor Units
Emission Factor Limit (maximum factor allowable by regulation)
Emission Factor Limit Decimal1
Emission Factor Limit Units1
Emission Factor - QA
Emission Factor - QA Decimal
Emission Factor - QA Units
Percent Reactivity
Days Per Week
Weeks Per Year
SIP Rule in Place
Year Regulated
Year Last Modified
Rule Penetration
Rule Effectiveness
Control Equipment
Control Efficiency
Percent Usage
Comment
•"•Note: Required for SIP inventories only when the
emission rate is limited by regulation.
List of Data Elements for Period Level
Provider
Inventory Type
Base Year
State Code
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County Code
City Code
Zone
Source Category
Pollutant Code
Period Code (Typical Winter Day, Peak Ozone Season, etc.)
Period Begin Month
Period End Month
Period Throughput
Interval Code (1 HR, 3 HR, 8 HR, etc.)
Hour 00 .. Hour 23 Throughput
Start Hour
Weekday Adjustment Factor
Saturday Adjustment Factor
Sunday Adjustment Factor
Emission Factor
Emission Factor Decimal
Emission Factor Units
Emission Factor Limit
Emission Factor Limit Decimal
Emission Factor Limit Units
List of Data Elements for Emissions Level:
Provider
Inventory Type
Base Year
State Code
County Code
City Code
Zone
Source Category
Pollutant Code
Emissions Type (Actual. Allowable, Uncontrolled)
Annual Emissions
Annual Emissions Decimal
Annual Emissions Units
Period Code
Daily Emissions
Daily Emissions Decimal
Daily Emissions Units
Interval Code
Interval Emissions
Interval Emissions Decimal
Interval Emissions Units
Note: If EPA or State default values are used, the origin (EPA or
State) and level (National, State or County) are required to be
indicated each time a default is used.
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4.5 Format for Area and Mobile Source Data
Previously, the SIP guidance documents and the SAMS
system provided for a series of source categories that ranged
from the detailed level to a very aggregated level. However, the
source category codes developed for use within AMS have been
designed to encourage the user to submit data at a more detailed
level. Therefore, the AMS source categories are significantly
different from the manner in which source categories have been
designated in past SIP guidance. A tentative listing of major
AMS source categories is included in Appendix B. A detailed
listing of the final AMS source category codes and descriptions
will be provided in AMS guidance to be issued by July 1991.
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5.0 DOCUMENTATION OF THE INVENTORY
Base year emission inventory information under the
Clean Air Act Amendments (CAAA) shall be provided to EPA in both
written and computerized formats. The written presentation has
to contain documentation that is extensive enough for the Agency
to reproduce the emission estimates that are submitted in the
inventory. Written reporting/documentation requirements are
summarized in this section. The use of AIRS may alleviate the
need for detailed hard copy data reporting because of the ability
of AIRS to generate the necessary reports. However, this does
not eliminate the need for certain documentation of the inventory
such as the specification of how applicable sources were
identified, where activity data were derived, and how rule
effectiveness levels were determined. The parallel
specifications for computerized submittals are presented in
Section 4.0.
Under the CAAA, EPA is requiring that States prepare
written inventory documentation reports according to a more
standardized set of guidelines. Inventory reports that are not
prepared according to the guidelines will be harder for EPA to
review and are more likely to be deemed unacceptable by the
Agency. This does not mean that every State inventory report
must be organized precisely the same and look identical. EPA's
primary interest is that all inventories 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 they are reported in. Inventories not meeting the minimum
data reporting and documentation standards established in this
discussion shall, however, be deemed unacceptable and returned to
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the States for modification before any further technical quality
review will be performed.
EPA has already published a detailed guidance document
on this issue that States need to consult before preparing their
written reports. This document is entitled Example Emissions
Inventory Documentation for Post-1987 Ozone State Implementation
Plans (EPA 450/4-89-018). The full reference for the document is
given in citation
No. 4 of the Section 6.0 bibliography. If a State does not have
the report, copies can be obtained from the Emission Inventory
Branch of OAQPS. As the title implies, the guidance document
provides a complete example of how an inventory should be
compiled and documented. The kinds of summary tables and
graphics that States need to provide to EPA for their base year
inventories are clearly shown. The examples cover point, area,
and mobile sources, and they address quality assurance aspects of
the inventory. Even though the guidance was prepared for ozone
inventories, the examples are equally applicable and
transferrable to CO inventories. It also provides States
guidance on how to summarize quality assurance activities that
need to be carried out in the compilation of the inventory.
EPA's recommended outline for the organization and
content of a State's inventory report is given in Table 5-1. The
combination of the Table 5-1 outline with the Example Emissions
Inventory Documentation report should provide States with all of
the guidance necessary to prepare an inventory documentation
report that will satisfy EPA and the intent of the CAAA.
The introduction to an inventory report shall contain a
description of the nonattainment area that has been inventoried;
a listing of the counties covered; a map of the area including
the 25-mile boundary outside of the nonattainment area; an
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identification of who prepared the inventory and who are the
respective contacts for major inventory components; a description
of major inventory problems or deficiencies; and a discussion of
how the remainder of the report is organized. After the
introduction, the report must contain a thorough summary of the
emissions data by pollutant, source type (point, area, mobile),
and geographic area. The Example Emissions Inventory
Documentation report provides several examples of tables and
graphics that can be presented for point, area, and mobile
sources. At a minimum, the report must include summary emissions
tables by pollutant and by source type; summary emissions tables
by
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TABLE 5-1. OUTLINE FOR EPA RECOMMENDED FORMAT/CONTENTS FOR
CO SIP EMISSION INVENTORY REPORTS
I. Cover and Title Page
A. Title (geographic area, type of inventories,
pollutants, base year)
B. Responsible agency [e.g., NC Dept of Health and
Natural Resources]
C. Report date (date completed/distributed)
D. Preparer (if different from responsible agency -
e.g., contractor)
II. Table of Contents
A. Contents
B. Tables
C. Figures
III. Introduction
A. Reason for report being prepared, purpose
[For example, In response to letter from to
, dated requesting preparation of
a SIP for demonstration of attainment of ozone
NAAQS in (geographic area). beginning with an
emission inventory for base year 1990. Base year
emission inventory serves as the basis for
emissions modeling and projections for future
years.]
B. Geographic area covered, base year, type of
inventory (03 SIP, CO SIP), pollutants included
(VOC, NOX, CO)
C. Brief discussion of contents of report
[Note: Include a paragraph or less describing
each major report section. For example, Section 2
summarizes stationary point, area and mobile
source emissions by county. Section 3 describes
stationary point source emissions and includes a
discussion of methods used to gather data,
calculate annual and seasonal emissions, and
presents a summary of emissions by plant.
Detailed point source emissions data are presented
in Appendix F. Section 4 discusses...]
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D. Discussion of automated data systems used (SAMS,
AIR AFS, AMS-PC, State system)
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TABLE 5-1. Continued
E. Major problems, deficiencies, portions of
inventory not included
F. List of primary guidance documents and references
used (EPA guidance documents, AP-42, etc.)
G. List of contacts for each distinct portion of the
inventory
IV. Summary
A. Emissions (annual and seasonal) of each pollutant
by major category (point, area, mobile - broken
down by non-road sources and on-road vehicles;
brief discussion in footnote, etc. to clarify what
each includes - point sources above cutoff, area
sources excluding non-road mobile sources?,
non-road sources include aircraft, trains,...)
B. See example tables and graphics given in Example
Emissions Inventory Documentation for Post-1987
Ozone State Implementation Plans (EPA-450/4-89-
018) .
V. Documentation of Emissions Methods/Data/Estimates*
A. Stationary Point Source Emissions*
1. discussions of procedures and methodologies
2. example surveys/questionnaires
3. list of plants by primary product and total
emissions
4. detailed data for each plant (can put in
appendix instead)
5. point source emissions summary
B. Stationary Area Source Emissions*
1. discussion of procedures and methodologies
2. list of source categories and emissions
3. calculations and discussion for each source
category
4. area source emissions summary
C. Mobile Source Emissions*
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TABLE 5-1. Continued
1. Non-Road Mobile Sources
a. same information as for stationary area
sources
2. On-Road Vehicles
a. mobile model inputs and outputs
b. VMT estimates
c. emission estimates
d. documentation (can put all or part in
Appendices)
e. mobile source emissions summary
f. discussion of procedures and
methodologies
VI. Quality Assurance/Quality Checking (QA/QC)
A. QA/QC plan - discussion of QA/QC methodologies
used
B. Results
C. QA procedures can also be discussed in individual
source category sections
VII. Appendices
A. Lengthy data, calculations, documentation of
methodologies/models
Notes: Both annual (except for on-road mobile sources) and
seasonal emissions (CO - CO season typical weekday emissions)
should be presented in the summary and sections describing
emissions.
All pages in the report (including appendices) should be
numbered. All reports shall be bound except computer printouts.
Sources of information should be referenced throughout. Include
complete list(s) of references within body of report (preferably
at end of each section).
Margins of report should be adequate so that copying of report
will not lose text, page numbers, or other important information.
In addition to hard copy reporting requirements for
emissions data, data must be reported in a computerized AIRS
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compatible format (Section 4.0). To the extent that data
have been successfully loaded onto AIRS and reports can be
generated from AIRS for nonattainment areas, this may
alleviate transmittal of portions of the hard copy inventory
that contain the detailed emissions data.
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county; and graphics illustrating the contribution to areawide
emissions by source type. States are required to report
emissions data both on an annual (except on-road mobile sources)
and CO season daily basis. Separate discussions must be
presented to describe inventory development procedures and
results for point, area, non-road mobile, and on-road mobile
sources. In addition to the specific parameters germane to
point, area, and mobile source types, each source type discussion
needs to explain how emissions were temporally allocated to a
daily basis and how rule effectiveness was incorporated into each
emission estimate.
The point source discussion shall include a description
of how the list of sources to be inventoried was identified. The
discussion shall address the issue of completeness of source
coverage (i.e., how did you ensure that all 100 ton/yr sources
were identified). Data collection methods and tools shall be
thoroughly explained and documented. All information surveys
that may have been conducted must be discussed and the results
provided (probably in an appendix). All sources inventoried
shall be listed according to their source category type (e.g.,
refinery, power plant,
steel mill, etc.). The methodology by which activity levels and
emissions were determined for each plant or source category (when
applicable) shall be succinctly but explicitly explained. Large
volumes of detailed data shall be put into appendices but clearly
linked to the text discussion in terms of how they were used to
determine emissions. Summary tables and graphics shall be
prepared to address just point source emissions (e.g., summary
table on CO point source emissions ranked by source category
type).
The area source discussion shall cover stationary area
sources, with off-highway mobile sources included in the mobile
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source discussion. The report must state if any source
categories were not considered in the inventory and why. All of
the source categories covered shall be listed and the method used
to determine emissions identified. If the EPA-recommended
approach in the Procedures Document (EPA-450/4-88-021) was used,
but a different emission factor was used, this must be noted.
For all approaches used (EPA or otherwise), the derivation of
activity/commodity level data shall be thoroughly discussed. As
needed, supporting data can be put into appendices but the
appendices shall be fully explained and clearly linkable back to
the text discussion and emission estimates. Like point sources,
emission summaries shall be developed for area sources. The
summaries must reflect emissions by county and for the entire
nonattainment area. Examples for these types of sources are
found in the Example Emission Inventory Documentation report.
In the mobile sources section of the inventory report,
States shall clearly describe how non-road mobile emissions were
calculated, how on-road vehicle emission factors were determined,
and how vehicle miles traveled (VMT) estimates were determined.
For on-road vehicle emission factors, the States must fully
report how they used the updated MOBILE4 model to help determine
emissions. The values used for all input parameters required by
the model shall be presented and their basis discussed. The
emission factors produced by the model shall be presented by
vehicle class. For VMT, the State must describe the methodology
employed to generate VMT data, key assumptions and inputs to the
process, and the group responsible for the estimates. The VMT
data determined shall be presented by road type classification
and by vehicle class. States must explicitly describe the
derivation of VMT. It is not acceptable to simply state that the
Department of Transportation ran a transportation planning model
and provided the air agency with VMT numbers. Simply providing a
computer printout of a transportation modeling run, without any
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explanation, is also not acceptable. The agency that is
responsible for the overall inventory must ensure that sufficient
documentation is provided to fully explain how VMT and mobile
source emission factors were derived.
The report shall fully describe how the VMT data were
combined with the emission factors to produce mobile source
emission estimates. The calculated estimates must be provided in
summary form by vehicle class, by pollutant, and by county.
Simple examples of how these summaries can be provided are given
in the Example Emissions Inventory Documentation report
referenced previously.
The inventory report shall have a separate section that
describes the implementation of the State's QA plan and the
results achieved by the QA program. For all source category
types, the QA discussion shall address the completeness of the
inventory (e.g., are all of the EPA-recommended area source
categories accounted for), reasonableness of the emission
estimates (e.g., are estimates for a category consistent with
some other related parameter for the area), and relative accuracy
of the data (e.g., do all of the individual county emission
figures total to the sums given for the whole area). The QA
discussion must show the range of quality review that was
performed and how this review benefitted the inventory. The
Emission Inventory Branch will be issuing additional quality
review guidance in July 1991 to help States perform many of these
quality checks and provide the kinds of QA feedback deemed
necessary by EPA.
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6.0 BIBLIOGRAPHY
The purpose of this section is to identify and provide
bibliographic citations of currently existing EPA guidance
materials for the development of CO emission inventories. The
list of existing guidance is divided into four categories: CO
inventory guidance/requirements, quality assurance/inventory
review guidance, emission factors/models, and general inventory
guidance. If updates to an existing document are planned in
response to the Clean Air Act Amendment (CAAA), this is indicated
in the guidance citation.
CO Inventory Guidance/Requirements
1. Procedures For The Preparation Of Emission Inventories
For Precursors Of Ozone. Volume I, EPA-450/4-88-021,
Third Edition, U. S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research
Triangle Park, NC, December 1988. [Revised version to
be completed in May 1991 and will specifically address
CO issues in addition to ozone.]
2. Procedures For The Preparation Of Emission Inventories
For Volatile Organic Compounds. Volume II: Emission
Inventory Requirements For Photochemical Air Quality
Simulation Models. EPA-450/4-79-018, U. S.
Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle Park, NC,
September 1979. [Revised version to be completed in
May 1991 and will specifically address CO issues in
addition to ozone.]
3. Procedures For Emission Inventory Preparation, Volume IV:
Mobile Sources. EPA-450/4-81-026d, U. S. Environmental
Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle, Park, NC, July 1989 (also
listed below under General Inventory Guidance). [Revised
version to be completed in May 1991.]
4. Example Emission Inventory Documentation For Post-1987
Ozone State Implementation Plans (SIPs). EPA-450/4-89-
018, U. S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park,
NC, October 1989.
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5. Procedures For Estimating And Applying Rule Effectiveness
In Post-1987 Base Year Emission Inventories For Ozone And
Carbon Monoxide State Implementation Plans. U. S.
Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle Park, NC, June
1989.
6. SIP Air Pollutant Inventory Management System (SAMS)
Version 4.0 and SAMS User's Manual. U. S. Environmental
Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle Park, NC, March 1991.
Quality Assurance/Inventory Review Guidance
7. Guidance For The Preparation Of Quality Assurance Plans
For 03/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.
8. Quality Assurance Program For Post-1987 Ozone And Carbon
Monoxide State Implementation Plan Emission Inventories.
EPA-450/4-89-004, U. S. Environmental Protection Agency,
Office of Air Quality Planning and Standards, Research
Triangle Park, NC, March 1989.
9. Quality Review Guidelines For Post-1987 State
Implementation Plan (SIP) Base Year Emission Inventories
(Draft), U. S. Environmental Protection Agency, Office of
Air Quality Planning and Standards, Research Triangle
Park, NC, February 1990. [Final version to be completed
in July 1991.]
10. Guidelines For Review Of Highway Source Emission
Inventories For 1982 State Implementation Plans. EPA-
450/12-80-002, U. S. Environmental Protection Agency,
Research Triangle Park, NC, December 1980. [This
document will be superseded by the Quality Review
Guidelines document above, to be completed in July 1991.]
General Inventory Guidance
11. Procedures For Emission Inventory Preparation, U. S.
Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle, Park, NC:
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a. Volume I: Emission Inventory Fundamentals. EPA-
450/4-81-026a, September 1981.
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b. Volume II: Point Sources. EPA-450/4-81-026b,
September 1981.
c. Volume III: Area Sources. EPA-450/4-81-026C,
September 1981.
d. Volume IV: Mobile Sources. EPA-450/4-81-026d
(Revised), July 1989. [Updated version to be
completed in May 1991.]
e. Volume V: Bibliography. EPA-450/4-81-026e,
September 1981.
Emission Factors/Models
12. Compilation of Air Pollutant Emission Factors. Volumes I and
II and its supplements, Fourth Edition, AP-42, U. S.
Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle Park, NC, September
1985.
13. AIRS Facility Subsystem Source Classification Codes (SCCs) And
Emission Factor Listing For Criteria Pollutants. U. S.
Environmental Protection Agency, Office of Air Quality
Planning and Standards, Research Triangle Park, NC, September
1989.
14. User's Guide to MOBILE4 (Mobile Source Emission Factor Model).
EPA-AA-TEB-89-01, U. S. Environmental Protection Agency,
Office of Mobile Sources, Ann Arbor, MI, February 1989.
[Revised version of MOBILE4 and documentation to be completed
in May 1991.]
To obtain copies of any of these documents, contact Mary Ann
Stewart at (919) 541-4340 or FTS 629-4340.
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APPENDIX A
SUMMARY OF REQUIRED CARBON MONOXIDE SIP INVENTORIES
BY NONATTAINMENT AREA CLASSIFICATION
A-l
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The type of inventories that are required (either explicitly
or implicitly) to be compiled under the Clean Air Act Amendments
(CAAA) of 1990 for each different carbon monoxide nonattainment
classification are delineated below. The timing of each inventory
is also denoted.
CO Nonattainment Areas
Moderate Areas:
a) Base Year Inventory -- Required by November 15, 1992, base
year is 1990, only pollutant inventoried is CO, represents
actual emissions on a typical daily period basis in the
peak CO season
b) Periodic Inventory -- A revised base year inventory is
required to be submitted no later than September 30, 1995,
and every 3 years thereafter until the area is
redesignated to attainment, represents actual emissions.
c) Modeling Inventory -- Areas exceeding a design value of
12.7 must submit an attainment demonstration plan by
November 15, 1992 that demonstrates attainment by December
31, 1995. To make the Attainment Demonstration, base year
and projected modeling inventories are needed. The level
of inventory detail is dictated by whether proportional
rollback or gridded dispersion modeling is required. The
base year modeling inventory will have a base year
consistent with the CO season, while the projected
modeling inventory will have a 1995 base year. The
projected modeling inventory will be used to determine if
the proposed SIP control strategies are adequate to reach
attainment by the designated date.
Serious Areas:
a) Base Year Inventory -- Same requirements as Moderate Areas
b) Periodic Inventory -- Same requirements as Moderate Areas
A-2
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Modeling Inventory -- Serious areas must submit an
attainment demonstration plan by November 15, 1992 that
demonstrates attainment by December 31, 2000. To make the
Attainment Demonstration, base year and projected modeling
inventories are needed. The level of inventory detail is
dictated by whether proportional rollback or gridded
dispersion modeling is required. The base year modeling
inventory will have a base year consistent with the CO
season, while the projected modeling inventory will have a
2000 base year. The projected modeling inventory will be
used to determine if the proposed SIP control strategies
are adequate to reach attainment by the designated date.
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APPENDIX B
POINT, AREA, AND MOBILE SOURCE CATEGORIES
NECESSARY FOR CONSIDERATION IN CO SIP INVENTORIES
B-l
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TABLE B-l. INDIVIDUAL POINT SOURCE CATEGORIES
External Fuel Combustion
Utility Boilers
Industrial Boilers
Commercial/Institutional Boilers
Other External Fuel Combustion
Stationary Internal Combustion
Reciprocating Engines
Gas Turbines
Waste Disposal
Municipal Waste
Combustion
Refuse Derived Fuel
Mass Burn
Co-fired
Other
Industrial Processes
Iron And Steel Manufacture
Coke Production
Coke Pushing
Coke Oven Doors
Coke Byproduct Plant
Coke Charging
Coal Preheater
Topside Leaks
Quenching
Battery Stacks
B-2
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TABLE B-l. Continued
Sintering
Electric Arc Furnaces
Other Process Units (specify)
Petroleum Refineries
Mineral Products
Cement
Glass
Other
B-3
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TABLE B-2. AREA AND MOBILE SOURCE CATEGORIES
Stationary Source Fuel Combustion
Electric Utility
Industrial
Commercial/Institutional
Residential
Waste Disposal. Treatment & Recovery
On-Site Incineration
Industrial On-Site Incineration
Commercial/Institutional On-Site Incineration
Residential On-Site Incineration
Open Burning
Industrial
Commercial/Institutional
Residential
Miscellaneous Area Sources
Other Combustion
Forest Wildfires
Managed (Slash/Prescribed) Burning
Charcoal Grilling
Structure Fires
Firefighting Training
Aircraft/Rocket Engine Firing & Testing
Mobile Sources
On-Road Vehicles
Light Duty Gasoline Vehicles (LDGV)
Light Duty Gasoline Trucks 1 (LDGT 1)
B-4
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TABLE B-2. Continued
Light Duty Gasoline Trucks 2 (LDGT 2)
Heavy Duty Gasoline Vehicles (HDGV)
Motorcycles (MC)
Light Duty Diesel Vehicles (LDDV)
Light Duty Diesel Trucks (LDDT)
Heavy Duty Diesel Vehicles (HDDV)
Non-Road Vehicle Gasoline
Recreational Vehicles
Construction Equipment
Industrial/Commercial Equipment
Lawn & Garden Equipment
Farm Equipment
Non-Road Vehicle Diesel
Construction Equipment
Industrial/Commercial Equipment
Farm Equipment
Aircraft
Military Aircraft
Commercial Aircraft
Civil Aircraft
Unpaved Airstrips
Marine Vessels
Coal
Diesel Fuel
Residual Oil
Gasoline
Railroads
Coal
Diesel
B-5
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