MEMORANDUM

TO: Brian Shrager/SPPD

FROM: Eastern Research Group, Inc.

DATE: November 2011

SUBJECT: Revised (November 2011) Standardization of Reported Data from the Public 

Comment Period and Questionnaire for Boilers, Process Heaters, Incinerators 

and Other Combustion Units

1.0 INTRODUCTION

This memorandum discusses the changes since the promulgation of the March, 2011 

final rule (76 FR 15608) in the methods used to standardize unit-level and emissions data 

reported by industry under the development of the Major Source Industrial, Commercial, and 

Institutional Boiler and Process Heater NESHAP. The methods used to standardize data for 

consideration in the promulgated rule are described in the memorandum, “Revised 

Standardization of Reported Data from the Public Comment Period and Questionnaire for 

Boilers, Process Heaters, Incinerators and Other Combustion Units” in the docket.

1 This 

memorandum only discusses the changes in methodology, and incorporates the memorandum 

for the promulgated rule by reference.

This memorandum is divided into the following sections:

1.0 Introduction

2.0 Summary of Changes in Standardization Methodology

3.0 References

Appendix A: New Pollutant Emissions Conversion Equations

Appendix B: Changes to Fuels for Emissions Testing Data

Appendix C: Summary of Changes in Control Configurations
2.0 SUMMARY OF CHANGES IN STANDARDIZATION METHODOLOGY

This section summarizes the changes in standardization methodology since the 

promulgated March, 2011 rule. The methods used to standardize unit-level and emissions data 

for the promulgated rule are described in the memorandum, “Revised Standardization of 

Reported Data from the Public Comment Period and Questionnaire for Boilers, Process Heaters, 

Incinerators and Other Combustion Units” in the docket1. The majority of the methods used to 

standardize data remained unchanged for the reconsideration of the promulgated rule; only 

the changes to the standardization methodology are discussed in this section.

2.1 New Pollutant Emission Conversion Equations

Two new pollutant emission conversion equations were created in order to standardize 

additional emissions data received during the reconsideration proposal period. These two

equations are presented in Appendix A of this memorandum. The first equation standardizes 

emissions reported as concentrations corrected to a carbon dioxide (CO2) percentage into the 

desired concentrations corrected to three percent O2. The equation is derived from Equations 

19-1 and 19-6 from EPA Method 19.

2 Emissions are first converted into an emission factor using 

a carbon F factor (Fc) using Equation 19-6 from Method 19. The resultant emission factor is 

then converted back into a concentration using a dry F factor (Fd) and Equation 19-1 from 

Method 19. These separate conversions were combined into one equation. Some emissions 

data were initially reported in concentrations corrected to a CO2 percentage for the 

development of the Major Source Industrial, Commercial, and Institutional Boilers and Process 

Heaters NESHAP; those data were not utilized in any impacts analyses for the promulgated rule. 

The previously-reported emissions data and new emissions data reported as concentrations 

corrected to a CO2 percentage were standardized and utilized in the impacts analyses and the 

development of MACT floors for the reconsideration proposal. The methods used to estimate 

cost and emission impacts and the methods used to develop MACT floors are provided in other 

memoranda.

3,4

The second equation standardizes dioxin/furan emissions data reported in units of 

micrograms per cubic meter at seven percent oxygen (μg/dscm @ 7% O2) into the desired units 

of nanograms per cubic meter at seven percent oxygen (ng/dscm @ 7% O2). Additional 
dioxin/furan emissions data were reported in units of μg/dscm @ 7% O2; no dioxin/furan 

emissions data had previously been reported in these units of measure. A summary of all new 

emissions data submitted after the promulgation of the March, 2011 final rule is presented in 

another memorandum.

5

2.2 Molecular Weight Change for NOx

When standardizing emissions data from a heat input basis to a concentration (or vice 

versa), the molecular weight of the specific pollutant in question is used in the standardization 

equation. Industry reported emissions testing and continuous emissions monitoring (CEMS) 

data for NOx in units of lb/MMBtu; the standardization of these data required a molecular 

weight for NOx in order to convert to parts per million (ppm) concentrations. All analysis 

conducted for the promulgated rule used a molecular weight of 76.0116 grams per gram-mole 

(g/mol). Emissions of NOx primarily consist of nitric oxide (NO) and nitrogen dioxide (NO2), and 

thus the molecular weight used to standardize emissions data for the promulgated rule was the 

sum of the molecular weights of these two compounds. However, the U.S. EPA guidance for 

developing emission factors suggests using only the molecular weight of NO2 (46.01 g/mol) 

when analyzing or standardizing NOx emissions.

6 All NOx emissions data were re-standardized 

using this corrected molecular weight, where necessary.

2.3 Changes to Toxic Equivalency Factors

It was determined that toxic-equivalent dioxin/furan (TEQ D/F) emissions were 

calculated improperly for the March, 2011 rule. TEQ D/F emissions are calculated by 

multiplying the total mass emissions of 17 specific congeners by their respective toxic 

equivalency factor (TEF). This provides standardized emissions of all congeners on a relative 

toxicity basis. The procedures used to calculate TEQ D/F emissions are detailed in another 

memorandum.7 For the March, 2011 rule, the 2005 World Health Organization toxic 

equivalency factor for octa-chlorinated dibenzodioxins and octa-chlorinated dibenzofurnas was 

applied to all dioxin/furan congeners for which a TEF was not specified.8 These additional 

congeners for which a TEF was not specified should not have been factored into the TEQ D/F 

calculation since these congeners have a TEF of zero. TEQ D/F emissions were recalculated in 

the EPA ICR databases for only the select 17 congeners. 
2.4 Corrections to Fuels Combusted during Emissions Testing

Fuel information was not readily available for all reported emissions testing data. For 

several data sets—particularly those reported in the Electronic Reporting Tool (ERT)—

assumptions were made as to the specific fuels combusted during the emissions testing period. 

These assumptions were typically based on other reported data sets from the same facility, or 

based on the universe of fuels specified to be combusted by the particular emission unit. These 

assumptions were investigated for their accuracy. A summary of the resultant changes based 

on this review is provided in Appendix B.

2.5 Comparison of Controls Installed Versus Controls Employed for Emissions Testing

Control devices were reported in several parts of the ICR survey. Some of the controls 

represented current configurations while other controls represented historical control device 

configurations. Facility correspondence from the University of Notre Dame (facility ID: 

INNotreDame) specified that previously-reported test data should be disregarded since the 

emissions control technologies employed by their units have been upgraded since the 

emissions testing occurred. This correspondence initiated an inventory-wide investigation into 

the units which reported test data employing outdated control configurations. This review led 

to test data being designated as being outdated and inappropriate to use for 22 boilers or 

process heaters because the data were representative of historical control configurations. A list 

of these units and an explanation of the data that were disregarded is provided in another 

memorandum.4

This review also led to changes in the total level of control currently installed on 9 

specific units. These changes in control type also affected the emissions and cost impacts 

estimated for the units. The methods used to estimate emission and cost impacts are 

described in another memorandum.3 A summary of the changes to the level of control for these 

9 units is provided in Appendix C.
3.0 REFERENCES

1. Gibson, G., and A. Singleton, ERG. Revised Standardization of Reported Data from the 

Public Comment Period and Questionnaire for Boilers, Process Heaters, Incinerators and 

Other Combustion Units. January 2011.

2. U.S. Environmental Protection Agency. Method 19 – Determination of Sulfur Dioxide 

Removal Efficiency and Particulate Matter, Sulfur Dioxide, and Nitrogen Oxide Emission 

Rates.

3. Eastern Research Group, Inc. Revised (November 2011) Methodology for Estimating 

Cost and Emissions Impacts for Industrial, Commercial, and Institutional Boilers and 

Process Heaters National Emission Standards for Hazardous Air Pollutants – Major 

Source. November 2011.

4. Eastern Research Group, Inc. Revised MACT Floor Analysis (November 2011) for the 

Industrial, Commercial, and Institutional Boilers and Process Heaters National Emission 

Standards for Hazardous Air Pollutants – Major Source. November 2011.

5. Eastern Research Group, Inc. Handling and Processing of Corrections and New Data in 

the EPA ICR Databases – Revised November 2011. November 2011.

6. U.S. Environmental Protection Agency. Procedures for Preparing Emission Factor 

Documents. EPA-454/R-95-015. Revised November 1997.

7. Eastern Research Group, Inc. Revised November 2011 Development of Baseline 

Emission Factors for Boilers and Process Heaters at Commercial, Industrial, and 

Institutional Facilities. November 2011.

8. Van den Berg, M. et. al. The 2005 World Health Organization Reevaluation of Human 

and Mammalian Toxic Equivalency Factors for Dioxins and Dioxin-Like Compounds. 

Oxford Journals: Toxicological Sciences. Volume 93, Issue 2. July 2006.
APPENDIX A

New Pollutant Emissions Conversion Equations
Table A-1: New Pollutant Emission Conversion Equations Added since Promulgation

Reported 

Emission 

Units

Associated 

Pollutants EQ ID Conversion Equation

Resulting 

Converted 

Emission Units

ppm @ 12% 

CO2

1 Non-metals FF11 * (100/12% CO2) * ((20.946-

3)/20.946) * (Fc/Fd) ppm @ 3% O2

μg/dscm @ 

3% O2

Dioxin/Furans FF13 * (1000 ng/ug) * ((20.946-7)/(20.946-

3))

ng/dscm @ 7% 

O2

1 Conversion is derived from Equations 19-1 and 19-6 from EPA Method 19. Emission concentrations are 

first standardized to a lb/MMBtu emission factor using a carbon F factor (Fc) and Equation 19-6. Then, 

the emission factor is converted back to a concentration using a dry F factor (Fd) and Equation 19-1. 

Equation FF11 in the table above combines those two steps into one equation. A list of Fc and Fd (in 

dscf/MMBtu) for specific fuels can be found in Table 19-2 of EPA Method 19.
APPENDIX B

Changes to Fuels for Emissions Testing Data
APPENDIX C

Summary of Changes in Control Configurations