Appendix G 

Quality Assurance of the 

Emissions Inventories
QA of the Emissions Inventories i 

The Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Appendix G 

North Carolina Attainment Demonstration June 15, 2007 
QA of the Emissions Inventories ii 

The Charlotte-Gastonia-Rock Hill, NC-SC 8-Hour Ozone Appendix G 

North Carolina Attainment Demonstration June 15, 2007 

TABLE OF CONTENTS

1.0 Introduction............................................................................................................................... 1 

2.0 Quality Assurance Of Area And Nonroad Mobile Sources Emissions Inventories ................. 1 

3.0 Quality Assurance Of Point Source Emissions Inventory ........................................................ 3 

3.1 Initial Data Evaluation ......................................................................................................... 3 

3.2 Follow up Review Performed by NCDAQ.......................................................................... 4 

3.3 Emission Inventory QA Review.......................................................................................... 5 

3.4 Eliminating Double Counting of EGU Units....................................................................... 6 

3.5 EGU Quality Assurance steps.............................................................................................. 7

4.0 Quality Assurance of On-Road Mobile Source Emissions Inventory ...................................... 8 
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North Carolina Attainment Demonstration June 15, 2007 

List of Acronyms 

Acronym Definition 

CERR Consolidated Emissions Reporting Rule 

EIIP Emission Inventory Improvement Program 

NIF National Emissions Inventory Input Format 

QA Quality Assurance 

SCC Source Classification Code 

SIWG Special Interest Workgroup 

USEPA U.S. Environmental Protection Agency 

USFS U.S. Forest Service 

VISTAS Visibility Improvement State & Tribal Association of the Southeast 
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North Carolina Attainment Demonstration June 15, 2007 

1.0 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 North Carolina 

Division of Air Quality (NCDAQ) decided to use the this modeling for its attainment 

demonstration. The sections below discuss the quality assurance (QA) procedures used by 

NCDAQ and the VISTAS/ASIP emissions inventory contractors. 

2.0 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. 

For the portion of the base 2002 inventory developed by North Carolina, specific QA procedures 

were followed. Under the direction of the QA coordinator, emission sources whose contribution 

were either at the high or low end of the range of estimates were scrutinized more closely to 

ensure that the emission estimates were estimated correctly. In addition, the raw data used in the 

calculations were verified to make sure transference to the spreadsheets was accomplished 

accurately. Furthermore, the formulas used to calculate the emissions were reviewed and 

checked for correctness. Random independent checks of the calculations were also performed to 

ensure the accuracy of the inventory. 

For the portion of the inventory developed by the VISTAS/ASIP contractor, MACTEC, specific 

QA procedures were followed. 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). 
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North Carolina Attainment Demonstration June 15, 2007 

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) format 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 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 
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North Carolina Attainment Demonstration June 15, 2007 

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. 

3.0 Quality Assurance Of Point Source Emissions Inventory 

3.1 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 that were not in tons 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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North Carolina Attainment Demonstration June 15, 2007 

• 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. 

3.2 Follow up Review Performed by NCDAQ 

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

point sources by the NCDAQ: 

• 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. 

• PAVE plots were generated to check to ensure emissions where showing up in all 

counties in North Carolina. Scale was lowered to make sure no emissions were omitted. 
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North Carolina Attainment Demonstration June 15, 2007 

• PAVE plots were animated over a 24-hr period to ensure diurnal changes in emissions 

were as they should be. 

• PAVE plots were visually inspected to make sure emissions were highest/lowest in 

logical places. 

• 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) parsed files were examined (i.e., Excel 

spreadsheets that provide unit-level results derived from the model plant projections 

obtained by the IPM) for accuracy. 

• 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. 

• Emissions and controls for Duke Energy and Progress Energy were compared to their 

latest updated plans for complying with North Carolina’s Clean Smokestack Act. (These 

plans varied substantially from the IPM results both in terms of current and future 

controls and timing of these controls. As a result, the NCDAQ replaced the IPM emission 

projections for 2009 with projections from the Duke Energy and Progress Energy 

compliance plans. 

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

facilities where new controls are scheduled to be installed. 

• Input files were examined to assure there were no double counted facilities (example 

would be if a facility was known by two different names and counted under each). 

3.3 Emission Inventory QA Review 

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: 
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North Carolina Attainment Demonstration June 15, 2007 

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. 

3.4 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 non-EGUs. Since this file contains both EGUs and nonEGU 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 
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North Carolina Attainment Demonstration June 15, 2007 

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 nonEGU inventory derived from the VISTAS cross-reference table to verify that units accounted for 

in IPM were not double-counted 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. 

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. 

3.5 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. 
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North Carolina Attainment Demonstration June 15, 2007 

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

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

NCDAQ submitted a number of corrections to the 2002 and 2009 point source emissions 

inventories and the VISTAS/ASIP contractor incorporated these changes into the final inventory. 

4.0 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. 

On-road mobile input data, such as speeds and vehicle miles traveled (VMT), was collected from 

the North Carolina Department of Transportation (NCDOT) and the Charlotte Department of 

Transportation (CDOT). The NCDAQ checked the speed information provided against previous 

sets of speeds for reasonableness. VMT and vehicle mix are additional data elements that are 

checked after they are formatted for SMOKE. This file is checked against the original source of 

the VMT and vehicle mix. Additionally, the following data elements are checked for accuracy in 

the input files prior to use in the modeling: pollutants, fuel Reid Vapor Pressure (RVP), 

inspection and maintenance program settings, anti-tampering program settings, calendar year, 

and evaluation month. All input files are printed and checked by hand against a “key” with the 

original source of the information. A person other than the one who generated the files always 

performs this QA step. If any discrepancies are found, they are marked on the hard copy and 

supplied back to the person who generated the input files for correction. Vehicle age distribution 

is another input referenced in the actual MOBILE6.2 input file. This file is checked against the 

original spreadsheet from which it is generated. Again, if any discrepancies are found, they are 

noted and returned to the person responsible for generating those files. 

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

NCDAQ. 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. The NCDAQ also graphed each 

county per pollutant for both 2002 and 2009 to check for reasonableness. Last, the NCDAQ 

compared the input files VISTAS used for modeling against the mobile input parameters 

supplied by the NCDAQ to ensure the correct mobile input parameters were utilized in the 

modeling process.