Appendix G 

Quality Assurance Of The Emissions Inventories 
TABLE OF CONTENTS 

I. INTRODUCTION ...............................................................................................................................1

II. QUALITY ASSURANCE OF AREA AND NONROAD MOBILE SOURCES EMISSIONS 

INVENTORIES...................................................................................................................................1

III. QUALITY ASSURANCE OF POINT SOURCE EMISSIONS INVENTORY .................................2

A. Initial Data Evaluation...................................................................................................................2

B. Follow up Review Performed by SCDHEC...................................................................................3

C. Emission Inventory QA Review ....................................................................................................3

D. Eliminating Double Counting of EGU Units.................................................................................4

E. EGU Quality Assurance steps........................................................................................................5

IV. Quality Assurance of On-Road Mobile Source Emissions Inventory .................................................5

Appendix G.1. Quality Assurance Project Plan............................................................................................6
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QUALITY ASSURANCE OF THE EMISSIONS INVENTORIES 

I. INTRODUCTION 

 The attainment modeling for the Charlotte-Gastonia-Rock Hill, NC-SC 8-hour ozone 

nonattainment area (the Metrolina area) was performed in conjunction with the regional haze modeling 

being done by the Southeast Regional Planning Organization, Visibility Improvement State and Tribal 

Association of the Southeast (VISTAS) and the fine particulate matter (PM2.5) and ozone modeling being

done by the Association of Southeastern Integrated Planning (ASIP). VISTAS and ASIP are run by the 

ten Southeast states (Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, 

Tennessee, Virginia and West Virginia). Since the regional haze and PM2.5 modeling uses annual 

simulations and includes an intermediate year that is the attainment year required for the Metrolina 

nonattainment area, the South Carolina Department of Health and Environmental Control (SCDHEC) 

decided to use this modeling for its attainment demonstration. The sections below discuss the quality 

assurance (QA) procedures used by SCDHEC and the VISTAS/ASIP emissions inventory contractors. 

II. QUALITY ASSURANCE OF AREA AND NONROAD MOBILE SOURCES EMISSIONS 

 INVENTORIES 

 Many emission estimation methods are based on AP-42 factors located on the U.S. 

Environmental Protection Agency (USEPA) website at http://www.epa.gov/ttn/chief/ap42/, factors given 

in the Procedures document, and factors given in the documents of the Emission Inventory Improvement 

Program (EIIP) website located at http://www.epa.gov/ttn/chief/eiip/. Sources of error would primarily be 

associated with multiplier values, data entry errors, and the accuracy of formulas. The inventory 

developed by the VISTAS/ASIP contractor, MACTEC, followed specific QA procedures. These 

procedures are outlined in the report entitled, Documentation of the Base G 2002 Base Year, 2009, and 

2018, Emission Inventories for VISTAS prepared for VISTAS by MACTEC, Inc. (a copy of this report is 

attached to Appendix F). Throughout the inventory development process, QA steps were performed to 

ensure that no double counting of emissions occurred, and to ensure that a full and complete inventory

was developed for VISTAS/ASIP. QA was an important component to the inventory development 

process and MACTEC performed the following QA steps on the area source component of the 2002 and 

2009 inventories: 

 

 1. All Consolidated Emissions Reporting Rule (CERR) and National Emissions Inventory (NEI) 

Input Format (NIF) State supplied data submittals were run through the USEPA's Format and Content 

checking software. 

 2. Source Classification Code (SCC) level emission summaries were prepared and evaluated to 

ensure that emissions were consistent and that there were no missing sources. 

 3. Fields were either added or used within each NIF data table to track the sources of data for 

each emission record. 

 4. Data product summaries were provided to both the VISTAS Emission Inventory Technical 

Advisor and to Area Source and Fires Special Interest Workgroup (SIWG) representatives for review and 

comment. Changes based on these comments were implemented in the files. 

 5. Version numbering was used for all inventory files developed. The version numbering process 

used a decimal system to track major and minor changes. For example, a major change would result in a 
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version going from 1.0 to 2.0. A minor change would cause a version number to go from 1.0 to 1.1. 

Minor changes resulting from largely editorial changes would result in a change from 1.00 to 1.01. 

 6. All final NIF files were checked using the USEPA's Format and Content checking software 

and summary information by State and pollutant were prepared comparing the current inventory to the 

previous version of the inventory. 

 In addition for the 2009 projection inventories, Tier comparisons (by pollutant) were developed 

between the 2002 base year inventory and the 2009 projection inventories. Also, total VISTAS/ASIP 

pollutant summaries were prepared to compare total emissions by pollutant between versions of the 

inventory. 

 For the fires inventory, data related to fuel loading and fuel consumption was reviewed and 

approved by the VISTAS Fire Special Interest Work Group (SIWG) to ensure that values used for each 

type of fire and each individual fire were appropriate. Members of the VISTAS Fire SIWG included 

representatives from most State Divisions of Forestry (or equivalent), as well as U.S. Forest Service and 

National Park Service personnel. 

III. QUALITY ASSURANCE OF POINT SOURCE EMISSIONS INVENTORY 

A. Initial Data Evaluation 

 The VISTAS/ASIP contractor, MACTEC, conducted an initial review of the 2002 point source 

CERR data in accordance with the QA procedures specified in the Quality Assurance Project Plan 

(QAPP) for this project (a copy of the QAPP is attached to this Appendix). The following evaluations 

were completed to identify potential data quality issues associated with the CERR data: 

 • Compared the number of sites in the CERR submittal to the number of sites in the 

VISTAS/ASIP draft 2002 inventory; the number of sites in the CERR submittal was less than in the 

VISTAS/ASIP draft 2002 inventory, since the CERR data was limited to major sources, while the 

VISTAS/ASIP draft 2002 inventory contained data for both major and minor sources; verified with state 

and local contacts that minor sources not included in the CERR point source inventory were included in

the CERR area source inventory. 

 

 • Checked for correct pollutant codes and corrected to make them NIF-compliant. 

 

 • Checked for types of particulate matter codes reported (i.e., PM-FIL, PM-CON, PM-PRI, 

PM10-PRI, PM10-FIL, PM25-PRI, PM25-FIL); corrected codes with obvious errors (i.e., changed 

PMPRI to PM-PRI). (The PM augmentation process for filling in missing PM pollutants is discussed in 

Appendix F). 

 

 • Converted all emission values to tons to allow for preparation of emission summaries using 

consistent units. 

 • Checked start and end dates in the Emissions Period record (PE) and Emissions record (EM) 

tables to confirm consistency with the 2002 base year. 

 • Compared annual and daily emissions when daily emissions were reported. In some cases, the 

daily value was non-zero (but very small) but the annual value was zero. This was generally the result of 

rounding in a state or local agency's submittal. 
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 • Compared ammonia emissions as reported in the CERR submittals and the 2002 Toxics 

Release Inventory; worked with state and local agencies to resolve any outstanding discrepancies. 

 • Compared sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions for Electric Generating 

Units (EGUs) to the USEPA's Clean Air Markets Division continuous emission monitoring (CEM) 

database to identify any outstanding discrepancies. (A full discussion of the EGU emissions analysis is 

discussed in Appendix F.) 

 • Prepared State-level emission summaries by pollutant for both the EGU and non-EGU sectors 

to allow state and local agencies to compare emissions as reported in the 1999 NEI Version 2, the 

VISTAS/ASIP draft 2002 inventory, and the CERR submittals. 

 • Prepared facility-level emission summaries by pollutant to allow state and local agencies to 

review facility level emissions for reasonableness and accuracy. MACTEC communicated the results of 

these analyses through email/telephone exchanges with the state and local point source contacts as well as 

through Excel summary spreadsheets. The state and local agencies submitted corrections and updates as

necessary to resolve any QA issues from these checks. 

B. Follow up Review Performed by SCDHEC 

 The following QA checks were performed both together and separate for EGU and non-EGU 

point sources by the SCDHEC: 

 • Data product summaries and raw NIF 3.0 data files were examined. 

 • NIF files were examined to identify problems with latitude and longitude, as well as, stack 

parameters. 

 • County emissions totals were examined to assure the counties with the highest emissions were 

consistent with what was expected. 

 • Errors detected in earlier model runs were rechecked with each successive model run to assure 

their correction was carried forward in subsequent runs. 

 • The Integrated Planning Model (IPM) results for all South Carolina EGUs were thoroughly 

reviewed. Changes were made when the IPM results differed from planned controls and/or expected 

control efficiencies. Comments were also made to account for agreed upon future emission rates in the 

Santee Cooper Consent Decree with SCDHEC and the USEPA. 

 • Facility level emission summaries for 2009 were examined for both the base case and CAIR 

case to ensure that emissions were consistent and that there were no missing sources. 

 • Ensured that stack parameters were modified appropriately and where necessary at facilities 

where new controls are scheduled to be installed. 

 • Data were examined to assure there were no double counted facilities (an example would be if 

a facility were known by two different names and counted under each). 

C. Emission Inventory QA Review 
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 Throughout the inventory development process, QA steps were performed to ensure that double 

counting of emissions did not occur and to ensure that a full and complete inventory was developed for

VISTAS/ASIP. QA was an important component to the inventory development process and MACTEC 

performed the following QA steps on the point source component of the VISTAS/ASIP revised 2002 base 

year inventory: 

 1. Facility level emission summaries were prepared and evaluated to ensure that emissions were 

consistent and that there were no missing sources. 

 2. State-level EGU and non-EGU comparisons (by pollutant) were developed between the 2002 

base year inventory, the draft VISTAS 2002 inventory, and the 1999 NEI Version 2 inventory. 

 3. Data product summaries and raw NIF 3.0 data files were provided to the VISTAS Emission 

Inventory Technical Advisor and to the Point Source, EGU, and non-EGU Special Interest Work Group 

representatives for review and comment. Changes based on these comments were reviewed and approved 

by the state and local point source contact prior to implementing the changes in the files. 

 4. Version numbering was used for all inventory files developed. The version numbering process 

used a decimal system to track major and minor changes. 

D. Eliminating Double Counting of EGU Units 

 The following procedures were used to avoid double counting of EGU emissions in the 2009 

point source inventory. The 2002 VISTAS point source emission inventory contains both EGUs and nonEGUs. Since this file contains both EGUs and non-EGU point sources and EGU emissions are projected 

using the IPM, it was necessary to split the 2002 point source file into two components. The first 

component contains those emission units accounted for in the IPM forecasts. The second component 

contains all other point sources not accounted for in IPM. 

 The VISTAS/ASIP contractor, Pechan, developed 2009 NIF files for EGUs from the IPM parsed 

files. All IPM matched units were initially removed from the 2009 point source inventory to create the

non-EGU inventory (which was projected to 2009 using the non-EGU growth and control factors). This 

was done on a unit-by-unit basis based on a cross-reference table that matches IPM emission unit 

identifiers (ORISPL plant code and BLRID emission unit code) to VISTAS NIF emission unit identifiers 

(FIPSST state code, FIPSCNTY county code, State Plant ID, State Point ID). When there was a match 

between the IPM ORISPL/BLRID and the VISTAS emission unit ID, the unit was assigned to the EGU 

inventory; all other emission units were assigned to the non-EGU inventory. 

 If an emission unit was contained in the NIF files created by Pechan from the IPM output, the 

corresponding unit was removed from the initial 2009 point source inventory. The NIF 2009 EGU files 

from the IPM parsed files were then merged with the non-EGU 2009 files to create the base 2009 point 

source files. 

 Next, MACTEC prepared several ad-hoc QA queries to verify that there was no double-counting 

of emissions in the EGU and non-EGU inventories. MACTEC reviewed the IPM parsed files to identify 

EGUs accounted for in IPM. MACTEC compared this list of emission units to the non-EGU inventory 

derived from the VISTAS cross-reference table to verify that units accounted for in IPM were not 

doublecounted in the non-EGU inventory. As a result of this comparison, MACTEC made a few 

adjustments in the cross-reference table to add emission units for four plants to ensure these units 

accounted for in IPM were moved to the EGU inventory. 
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 MACTEC reviewed the non-EGU inventory to identify remaining emission units with a Standard 

Industrial Classification (SIC) code of "4911 Electrical Services" or Source Classification Code of "1-01- 

xxx-xx External Combustion Boiler, Electric Generation". MACTEC compared the list of sources 

meeting these selection criteria to the IPM parsed file to ensure that these units were not double-counted. 

MACTEC asked state and local agencies to review the 2009 point source inventory to verify whether 

there was any double counting of EGU emissions. 

E. EGU Quality Assurance steps 

 Quality assurance was an important component to the inventory development process and 

MACTEC performed the following QA steps on the EGU component of the VISTAS/ASIP revised 2009 

EGU inventory: 

 1. Provided IPM parsed files (i.e., Excel spreadsheets that provide unit-level results derived from 

the model plant projections obtained by the IPM) to the VISTAS EGU SIWG for review and comment. 

 2. Provided facility level emission summaries for 2009 to the VISTAS EGU SIWG to ensure that 

emissions were consistent and that there were no missing sources. 

 3. Compared State-level emissions from the IPM parsed files with the post-processed NIF files to 

verify that the post-processed NIF files were consistent with the IPM parsed file results. 

 VISTAS/ASIP requested state and local contacts to review of these files. The SCDHEC 

completed a detailed review of the inventory prepared by the VISTAS/ASIP contractor. The SCDHEC 

submitted corrections to the 2002 and 2009 point source emissions inventories and the VISTAS/ASIP 

contractor incorporated these changes into the final inventory. 

IV. Quality Assurance of On-Road Mobile Source Emissions Inventory 

 Quality Assurance is one of the most important steps in performing an air quality modeling study. 

Because emissions inventory development is tedious, time consuming and involves complex 

manipulation of many different types of large data sets, errors are frequently made and, if rigorous QA 

measures are not in place, these errors may remain undetected. For the on-road mobile source category,

QA can be broken into two components: (1) input files/data, and (2) SMOKE outputs/summaries. 

 South Carolina On-road mobile input data, such as speeds and vehicle mix, came from the default 

values built into MOBILE6 and used the same assumptions as the CERR. Since much of South 

Carolina's On-road Mobile inputs were default, we put more emphasis on reviewing the resulting 

emissions for reasonableness. 

 Upon completion of the modeling, VISTAS supplied the emissions output summary files to the 

SCDHEC. The modeling was an iterative process. To ensure the latest information was incorporated into

the current modeling effort, the latest version of the county emissions were compared to previous draft 

versions of the county emissions. 
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Appendix G.1. 

Quality Assurance Project Plan