m
m0*
Review and Analysis of Emissions Test Reports
for Purposes of Reviewing the Natural Gas
Production Flares Volatile Organic Compounds
Emissions Factor Under Clean Air Act Section
130
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Review and Analysis of Emissions Test Reports for Purposes of Reviewing the Natural Gas
Production Flares Volatile Organic Compounds Emissions Factor Under Clean Air Act Section
130
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Sector Policies and Programs Division
Research Triangle Park, North Carolina 27711
February 2018
in
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Disclaimer
The EPA's Sector Policies and Programs Division of the Office of Air Quality Planning and
Standards, Office of Air and Radiation, reviewed and approved this report for publication.
Mention of trade names, commercial products, or company names is not intended to constitute
endorsement or recommendation for use.
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Table of Contents
Page
Section 1 Summary 1
Section 2 Background 4
2.1 Review of the Existing VOC Emissions Factor for Flares at Natural Gas Production
Site 4
2.2 Overview of Emissions Test Data Review for THC Emissions Factors Development.. 6
2.3 Overview of New Emissions Factor Analysis and Development 7
Section 3 Emissions Factor Analysis for Elevated Flares 9
Section 4 THC Emissions Factor Development for Enclosed Ground Flares 10
4.1 Field-Tested Enclosed Ground Flares - THC 10
4.1.1 Gas Volume Basis 11
4.1.2 Heat Input Basis 13
4.2 Manufacturer-Tested Enclosed Ground Flares - THC 14
4.2.1 Gas Volume Basis 17
4.2.2 Heat Input Basis 19
Section 5 Clarification of Heating Value Basis 21
Section 6 Conclusions 22
Section 7 References 23
Appendix A Consent Decree
Appendix B EPA's "Test Quality Rating Tool" Template (ICR Template)
List of Tables
Table S-l. Summary of New THC Emissions Factors Developed 3
Table 4-1. Overview of the Emissions Factor for THC Expressed in Terms of Gas
Volume from Field-Tested Enclosed Ground Flares 12
Table 4-2. Description of SCC Included in Table 4-1 12
Table 4-3. Analysis of Emissions Test Reports for Field-Tested Units, Gas Volume Basis 12
Table 4-4. Overview of the Emissions Factor for THC Expressed in Terms of Heat Input
from Field-Tested Enclosed Ground Flares 13
Table 4-5. Analysis of Emissions Test Reports for Field-Tested Units, Heat Input Basis 13
Table 4-6. Overview of the Emissions Factors for THC Expressed in Terms of Gas
Volume from Manufacturer-Tested Enclosed Ground Flares 17
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Table 4-7. Description of SCC Included in Table 4-6 17
Table 4-8. Analysis of Emissions Test Reports for Manufacturer-Tested Units, Gas
Volume Basis 18
Table 4-9. Overview of the Emissions Factors for THC Expressed in Terms of Heat
Input from Manufacturer-Tested Enclosed Ground Flares 19
Table 4-10. Analysis of Emissions Test Reports for Manufacturer-Tested Units, Heat
Input Basis 20
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Section 1
Summary
This report documents EPA's review and analysis of test reports for purposes of
conducting the review and, if necessary, revision of the existing volatile organic compounds
(VOC) emissions factor for flares at natural gas production sites pursuant to section 130 of the
Clean Air Act (CAA). The EPA would revise the emissions factor if, based on a review of the
available data, it concludes that revision is necessary. As explained in more detail below in this
report, the available flare data pertain to total hydrocarbon (THC) emissions and do not provide
sufficient information for estimating VOC emissions from the tested flares. As such, the
available data give no indication that the existing VOC emissions factor for flares at natural gas
production sites is somehow flawed or outdated and thus warrants revision; absent data
indicating such, the EPA cannot conclude that revision is necessary. Therefore, based on its
review of available flare data, the EPA concludes that it is not necessary to revise this existing
flare VOC emissions factor.
While the EPA has not revised the existing VOC emissions factor for flares at natural gas
production sites, it has used the available THC emissions data for enclosed ground flares to
develop two new total hydrocarbons (THC) emissions factors for enclosed ground flares at
natural gas production sites. Additionally, the EPA has developed four new THC emissions
factors for enclosed ground flares at certain chemical manufacturing processes. The six
emissions factors are finalized as an update to the Compilation of Air Pollutant Emission
Factors, Volume 1: Stationary Point and Area Sources, (AP-42) (EPA, 1995).
On October 16, 2016, Air Alliance Houston, Community In-Power and Development
Association, Inc. (CIDA), Louisiana Bucket Brigade, and Texas Environmental Justice
Advocacy Services (TEJAS), (collectively, "Plaintiffs") filed a lawsuit against the U.S.
Environmental Protection Agency (EPA) alleging that the EPA had failed to review and, if
necessary, revise the emissions factor for VOC from elevated flares and enclosed ground flares
at natural gas production sites at least once every three years as required in Section 130 of the
Clean Air Act (CAA). Air Alliance Houston, et al. v. McCarthy. No. 1:16-cv-01998-RC
(D.D.C.). On December 7, 2016, the Court entered a consent decree in this case. Under the terms
of the consent decree, by June 5, 2017, the EPA was to review and either propose revisions to the
VOC emissions factor for elevated and enclosed ground flares at natural gas production sites
under CAA Section 130, or propose a determination under CAA Section 130 that revision of the
emissions factor is not necessary and post the proposed revision or determination on the
Agency's AP-42 website. The consent decree further requires that by February 5, 2018, the EPA
issue a final revision or determination and post it on the Agency's AP-42 website. Appendix A
of this document contains a copy of the consent decree.
The EPA evaluated test data available to the Agency for elevated and enclosed ground
flares from natural gas production sites, as well as data from testing conducted by manufacturers
under 40 CFR part 60 subparts OOOO and OOOOa and 40 CFR part 63 subpart HH and HHH.
On June 5, 2017, the EPA proposed to determine that revision to the existing VOC emissions
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factor for flares at production sites is not necessary; at the same time the EPA proposed three
THC emissions factors for enclosed ground flares and updates to AP-42 Section 13.5 (Industrial
Flares). The EPA requested public comments on its proposal, and the public comment period
ended on August 18, 2017. EPA received a total of 3 comment letters. The EPA's Response-to-
Comments document (ERG, 2018) contains the Agency's responses to issues raised in the public
comments. After considering the public comments, the EPA is finalizing its proposed
determination and six new emissions factors in AP-42 Section 13.5 (Industrial Flares), as shown
in Table S-l.
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Table S-l. Summary of New THCa Emissions Factors Developed
Emissions Unit and
Pollutant
No. of
Available Units
with Emissions
Test Data
Source
Classification
Codes (SCC)
AP-42 Emissions
Factor
Representativeness
Enclosed Ground
Flares at Natural Gas
Production Sites
9
31000205
31000212
31000227
332 pound (lb) THC
(as propane)/million
standard cubic feet
(106scf) gas burned
or
0.335 lb THC (as
propane)/million
British thermal units
(106 Btu) heat input
Poorly
Enclosed Ground
Flares for Certain
Chemical
Manufacturing
Processes, Flare
Operating Under Low
Percent Load.b
29
30119701
30119705
30119709
30119741
30190099
8.37 lb THC (as
propane )/106 scf gas
burned
or
3.88e-3 lb THC (as
propane )/106 Btu
heat input
Moderately
Enclosed Ground
Flares for Certain
Chemical
Manufacturing
Processes, Flare
Operating Under High
Percent Load.b
30
30119701
30119705
30119709
30119741
30190099
2.56 lb THC (as
propane )/106 scf gas
burned
or
1.20e-3 lb THC (as
propane )/106 Btu
heat input
Moderately
a The test method for THC for these emissions factors is EPA Method 25 A.
b The dataset for these tests consisted of four different test conditions per unit: ramping back and forth between 0
and 30 percent of load; ramping back and forth between 30 percent and 70 percent of load; ramping back and
forth between 70 percent and 100 percent of load; and a fixed-rate maximum load condition. Analyses
determined that only the first condition was statistically different. Low percent load is represented by a unit
operating at less than 30 percent of maximum load.
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Section 2
Background
For purposes of reviewing the existing natural gas production site flare VOC emissions
factor, the EPA obtained field test reports containing operating parameter and emission rate data
on enclosed ground flares at natural gas production sites. Additionally, the EPA received
enclosed ground flare data from manufacturers conducting performance tests under 40 CFR part
60 subparts OOOO and 0000a and 40 CFR part 63 subparts HH and HHH.1 Finally, the EPA
located one test report for elevated flares, but the gas flowrate information contained in the test
report is claimed as confidential. The following documents the EPA's review and analysis of
these available source test reports.
The background file for AP-42 Section 13.5 contains the information discussed in this
document, including the data summary and emissions factor development workbook, the
Individual Test Rating (ITR) score sheets, and the test reports that EPA reviewed but did not use
in developing the THC emissions factors. A link to the background file is found under the
section's heading on the AP-42 website (https://www3.epa.gov/ttn/chief/ap42/chl3/index.htmn.
The test reports EPA used in the development of the emissions factors are listed as references in
AP-42 Section 13.5. These references can be accessed by clicking the reference's name in
Section 13.5.2
2.1 Review of the Existing VOC Emissions Factor for Flares at Natural Gas
Production Sites
An emissions factor for VOC from natural gas production flares (SCC 31000205) exists
in the EPA's WebFIRE database; however, this factor (5.60 lb per million cubic feet of gas
produced) is not included in AP-42. This factor was obtained from the 1990 AIRS Facility
Subsystem Source Classification Codes and Emission Factor Listing for Criteria Air Pollutants
(EPA, 1990). There is no background information in that document to indicate the source of the
data or the methods used to derive the emissions factor. As such, the emissions factor has a "U"
rating. For emissions factors developed prior to 2013, EPA assigned a letter rating (e.g., A, B, E)
to designate the quality of the factors. A "U" designation indicates an unrated factor, meaning
1 For the purposes of 40 CFR part 60 subparts OOOO and OOOOa and 40 CFR part 63 subparts HH and HHH,
these units are not considered flares. The definition of flare in these subparts specifically excludes these units. See
discussion in section 4.2.
2 In addition to the reports located in the background file, there were two additional field tests that were reviewed
but not used in the creation of the THC emissions factor for enclosed ground flares at natural gas production sites
due to low destruction efficiency. However, the results for these units are contained in a single report with two other
units that were used in the development of that emissions factor. As such, the entire report is listed as a reference in
Section 13.5, and the report for these two units that were not used in the development of this factor is not in the
background file.
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that the factor is developed from source tests that have not been thoroughly evaluated, research
papers, modeling data, or other sources that may lack supporting documentation. The data used
to develop an unrated emission factor are not necessarily poor, but there is not enough
information to rate the factor.
Available flare emissions data include data on THC emissions from both field-tested and
manufacturer-tested enclosed ground flares.3 For many types of sources, including enclosed
ground flares, it is less common to measure VOC emissions than it is to measure emissions of
specific compounds or THC. It is easier to measure THC emissions than VOC emissions because
THC can be determined using EPA Method 25 A, which counts the number of carbons in a gas
sample to provide a determination of THC emissions. To measure VOC emissions, one of two
approaches is generally taken: (1) THC emissions are measured with one method (e.g., EPA
Method 25A) while methane and ethane emissions are measured with a second method (e.g.,
EPA Method 18) and subtracted from the THC emissions, or (2) emissions of individual
compounds are measured with one or more test methods and then summed to obtain the VOC
emissions. Depending on the gas stream being measured, the number of organic compounds
present in the gas stream can be numerous, and it can be difficult to measure all of the
compounds individually.4
Consistent with Section 130 of the CAA, the EPA would revise the existing emissions
factor for flares at natural gas production sites if, based on a review of the available data, it
concludes that revision is necessary. As mentioned above, the available enclosed ground flare
data pertain to THC emissions data. They also do not provide sufficient information for
estimating VOC emissions from the tested flares because the reports either did not contain
methane and ethane emissions data or, where the report did include methane and ethane
emissions data, the measured methane and ethane emissions were higher than the THC
emissions, thus resulting in a negative value for VOC emissions. As such, these data do not shed
light on the VOC emissions from the tested units and therefore give no indication that the
existing VOC emissions factor warrants revision; absent data indicating such, the EPA cannot
conclude that revision is necessary. Therefore, based on its review of available flare data, the
EPA concludes that it is not necessary to revise this existing flare VOC emissions factor.
3 As explained in Section 3, we located but did not use data on one manufacturer-tested elevated flare as the data
have been claimed to contain confidential business information.
4 This is especially true in the case of combustion sources, because the compounds in the emissions stream are
different from the compounds in the inlet stream and there are many different organic compounds that may be
emitted as byproducts of combustion. This is one reason why programs such as the manufacturer testing program
under 40 CFR part 60 subparts OOOO and 0000a and 40 CFR part 63 subparts HH and HHH require the
measurement of THC instead of VOC.
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2.2 Overview of Emissions Test Data Review for THC Emissions Factors
Development
While the EPA has not revised the existing VOC emissions factor for flares at natural gas
production sites, it has developed two new THC emissions factors for enclosed ground flares at
natural gas production sites based on the THC emissions data for enclosed ground flares from
field-tested units. These data are based on enclosed ground flares in the natural gas production
sector burning various vent streams (e.g., tank vents, glycol dehydrator vents) during the time of
the tests. For enclosed ground flares with the SCCs specified in Tables 4-1 and 4-4 in Section 4.1
of this document, the EPA recommends the use of the THC emissions factors developed with
these data instead of the VOC emissions factor in WebFIRE, as background documentation for
this new emissions factor is available and the factor is based on field data from similar units.
The facility and emissions information for each test report are compiled in a test data
summary workbook called "EF Creation_THC_ONGflare_2018February.xlsm". For EPA to use
emissions data from a test report in developing an emissions factor, two basic test data elements
must be included in the report: (1) pounds per hour (lb/hr) emissions rate, or enough data to
calculate the lb/hr emissions rate, and (2) a related process rate (e.g., volume of gas burned per
hour (MMscf/hr) or heat input (MMBtu/hr)). The EPA reviewed each test report to confirm
whether these critical fields were available. The EPA also reviewed each test report to determine
flare operating characteristics (i.e., type of fuel burned, destruction and removal efficiency
(DRE), and flare exit velocity).
For each emissions test report used in developing the emissions factors (i.e., reports that
contain the two test data elements described above), EPA determined an ITR score by
completing the "Test Quality Rating Tool" tab in the EPA's WebFIRE Template and Test
Quality Rating Tool (including instructions) spreadsheet (available on the ERT website at:
https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert). Appendix
B provides the "Test Quality Rating Tool" template for the ITR. The ITR is a quantitative
measure of the quality of the data contained within a test report. The ITR score may range from 0
to 100 and gives a general indication of the level and quality of documentation available in the
test report and the level of conformance with the requirements of the standard test methods used
to measure the emissions. The "Test Quality Rating Tool" includes a series of questions related
to "Supporting Documentation Provided" (columns A and B) and related to "Regulatory Agency
Review" (columns G and H). Generally, the "Supporting Documentation Provided" columns are
an indication of the completeness of the test report while the "Regulatory Agency Review"
columns provide an indication of whether the test was conducted according to the requirements
of the standard test methods used to measure the emissions.
For the "Supporting Documentation Provided" portion, the ITR worksheet includes 8
general questions, 8 questions for manual test methods, and 10 questions for instrumental test
methods. Examples of the general questions include: whether the testing firm described
deviations from the test method or provided a statement that deviations were not required;
whether the test report provided a full description of the process and unit tested; and whether the
test report provided an assessment of the validity, representativeness, achievement of data quality
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objectives and usability of the data. For instrumental test methods, example questions include:
whether the test report provided: a complete description of the sampling system; inclusion of
response time tests; inclusion of calibration error tests; and inclusion of calibration drift tests.
The "Regulatory Agency Review" portion of the ITR worksheet includes 14 general questions,
33 questions for manual test methods, and 15 questions for instrumental test methods. This
portion of the worksheet includes questions on whether method quality assurance criteria were
met, whether samples were handled appropriately, and the representativeness of the data
collection.
For the test reports associated with the field-tested units, the EPA completed only for the
"General" and "Instrumental Test Methods" sections of the ITR worksheet. In these reports, the
only relevant data5 that is collected by a manual test method are the EPA Methods 2 and 4 data
for velocity and moisture. The "Manual Test Methods" portion of the worksheet is intended to
determine the quality of data for a manual method measuring a pollutant or diluent. It does not
fairly assess data quality for just velocity and moisture, because there is no corresponding lab
data. As such, the majority of the questions do not apply, and the report is penalized for not
having data that are not required. For the test reports associated with the manufacturer-tested
units, EPA completed all sections of the worksheet. This is because the testing procedures for the
manufacturer performance tests requires some of the necessary data to be collected by manual
test methods, such as determining certain compounds by EPA Method 3C. These data are then
used in the determination of the THC mass emissions rate.
ITR scores for the test reports in the analysis range from 20 to 78.6 The ITR scores for
the test reports reviewed are provided in a workbook called
"WF_ITR_ONGFlares_THC_2018February xlsx".
2.3 Overview of New Emissions Factor Analysis and Development
The emissions factor development approach followed the EPA's Recommended
Procedures for Development of Emissions Factors and Use of the WebFIRE Database (EPA,
2013). The workbook "EF Creation_THC_ONGflare_2018February.xlsm" provides the
emissions factor development calculations for each emissions factor. The EPA followed the
recommended procedures in the 2013 guidelines implicitly, including:
• procedures for assigning an ITR score for those test reports that are used in the
emissions factor analysis;
5 Some reports did have lab data for methane and ethane, but EPA did not use those data in the development of these
emissions factors. Where EPA used methane data (see Section 4.1 of this document for more information on use of
methane data), the tester obtained those data by instrumental test methods. Additionally, there is lab data for fuel
samples, but the ITR "Manual Test Methods" questions are intended to be used for stack test methods, not fuel
samples.
6 While the ITR is an assessment of the quality of the report, a low rating does not necessarily mean that the report
was not adequate for the intended purposes. The ITR also does not take into account conversations that may have
occurred between the facility and the regulatory authority to resolve any issues.
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• recommended statistical procedures for determining whether datasets are part of the
same data population;
• statistical procedures for determining whether any data points are outliers (i.e., outlier
checks); and
• procedures for determining whether data for a particular emissions unit should be
included in the emissions factor.
This last step, determining whether to include data from each unit, involves comparing
the Factor Quality Index (FQI) for different emissions units. The FQI is an indicator of the
emissions factor's ability to estimate emissions for the entire national population, and it is related
to both the ITR score and the number of units in the dataset. After the EPA completed the
statistical procedures, the Agency ranked the dataset by ITR score (high to low) and developed
an FQI for each unit in the candidate set. The FQI should decrease with each emissions unit. If
the FQI increases, EPA considers only average test values above the point where the FQI
increases in factor development.
Generally, the EPA combines emissions data from multiple tests conducted on a single
emissions unit so that each emissions unit is equally weighted with other units. However, there
are times when it may be necessary to subcategorize the emissions factor data from particular
units because the emissions are dissimilar. The recommended emissions factor development
procedures include a statistical procedure for determining whether emissions data are from the
same data population or whether emissions data should be subcategorized based on a
characteristic of the emissions unit (e.g., operating load). This analysis requires three or more
emissions units from each potential subcategory. For testing performed by the manufacturers,
each unit was tested under four different operating conditions. Instead of combining all of the
emissions data for each unit, the EPA performed a statistical analysis to determine whether the
data should be subcategorized. This is further discussed in Section 4.2 of this document.
Some of the data from EPA Method 25 A included test run averages reported as a
negative or zero value. Because the 2013 recommended procedures for emissions factor
development do not specify how this data should be handled, and because it is not possible for
emissions rates to be negative, the EPA excluded this data from emissions factor development in
this project.
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Section 3
Emissions Factor Analysis for Elevated Flares
Elevated flares do not lend themselves to conventional emissions testing methods, due to
the fact that the plume is not emitted through a stack. It is difficult, dangerous, and costly to
conduct extractive sampling on these plumes, as the tester must be elevated in a mobile testing
platform in order to follow the plume as it shifts direction. More recently, testing of some
elevated flares at refineries and chemical plants has been accomplished using passive Fourier
transform infrared spectroscopy (pFTIR) and differential infrared absorption LIDAR [light
detection and ranging] (DIAL). Both of these techniques must be performed by highly trained
and specialized operators, and as such, measurement of elevated flares with these techniques is
uncommon and infrequently required.
The EPA is aware of one flare manufacturer for natural gas production sites that has
conducted pFTIR testing on an elevated flare. During a site visit, this manufacturer, a non-
regulatory entity, provided the EPA data, which the manufacturer has claimed as confidential
business information (CBI). Because it is not possible to mask CBI data with only one report, the
EPA contacted the flare manufacturer to request a version of the report that does not contain
information that it considers to be CBI for use in this emissions factor development effort. The
manufacturer declined.
In light of the above, and absent other available data on elevated flares, the EPA has not
developed a new elevated flare VOC emissions factor. However, the existing VOC emissions
factor remains available in assisting industry and states in estimating VOC emissions from
elevated flares at natural gas production sites.
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Section 4
THC Emissions Factor Development for Enclosed Ground Flares
The EPA has developed THC emissions factors for enclosed ground flared based on data
for field and manufacturer-tested enclosed ground flares. The emissions data review and the
emissions factor development for each emissions factor are described below
While there is a current unrated VOC emissions factor in WebFIRE for flares from
natural gas production sites, the background data for that factor does not indicate if the factor
applies to enclosed ground flares or just elevated flares, nor does it detail the method used to
develop the factor. Further, because the measurement of VOC and THC vary, the data are not
often directly comparable. As such, the existing emissions factor from WebFIRE is not included
in the development of the new emissions factors described below.
4.1 Field-Tested Enclosed Ground Flares - THC
In this review and analysis, an enclosed ground flare refers to a thermal oxidation system
using a flame with an enclosure.7 Enclosed grounds flares are a commonly used control device at
natural gas production sites. However, for the purposes of 40 CFR part 60 subparts OOOO and
0000a and 40 CFR part 63 subparts HH and HHH, these units are not considered flares, as that
term is defined in those subparts. The definition of flare in these subparts specifically excludes
these units.8 In the Oil and Gas sector, these units are more commonly referred to as "enclosed
combustors". Enclosed combustors can be used to control the emissions from numerous sources
at natural gas production sites, including glycol dehydrators, condensate storage tanks, pumps,
and compressors.
The EPA reviewed data from test reports associated with 13 field-tested units for the
development of the enclosed ground flare THC emissions factors for natural gas production sites.
Each test report was analyzed and summarized, and for those test reports included in the
emissions factor analysis, given an ITR score. The emissions data (pounds of THC per hour [lb
THC/hr]) from these test reports are based on measurements taken with EPA Method 25A. Upon
reviewing the data, only 9 field-tested units had useable data and were included in the
development of an emissions factor. Certain test reports were excluded from the emissions factor
analysis because the demonstrated destruction efficiency was below 95 percent. Certain test
reports were excluded from the emissions factor analysis because there was not enough
information in the reports to determine the processes that were being controlled by the enclosed
ground flares.9 One test report was excluded from the emissions factor analysis because there
7 See Consent Decree, page 2.
8 In these subparts, a flare is defined as a thermal oxidation system using an open flame (without enclosure).
9 These reports did not include enough information to determine whether the enclosed ground flares were at natural
gas production sites. The reports also lacked information on the type of fuel that the flares were burning.
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was no process data included in the report. For the test reports used, some runs were eliminated
from the dataset because the average value of the run was zero or negative. Additionally, while
all of the reports included calculated emission rates of THC in lb/hr, the raw Method 25 A data
was bias corrected in these calculations. Method 25A does not specifically allow data to be bias
corrected; therefore, the emission rates were recalculated using the raw Method 25A results, and
available flowrate and stack moisture data. Lastly, some reports included results for methane and
total non-methane hydrocarbons (TNMHC) (as propane) in lieu of THC results. For these
reports, the methane data was divided by three to put it on an "as propane" basis and added to the
TNMHC results to obtain the THC (as propane) emissions rate.
In addition to this field-tested data, the EPA reviewed and analyzed test reports submitted
by manufacturers of enclosed combustors pursuant to 40 CFR part 60 subparts OOOO and
OOOOa and 40 CFR part 63 subparts HH and HHH. As explained in more detail in Section 4.2
of this document, our statistical analysis determined that the emissions profile for these
manufacturer-tested units is not likely to be representative of the THC emissions from an
enclosed combustor burning field gas. Therefore, the EPA used only the data from the field-
tested units in developing the enclosed ground flare THC emissions factors for natural gas
production sites.
4.1.1 Gas Volume Basis
Table 4-1 provides an overview of the THC emissions factor expressed in terms of gas
volume burned (lb THC/106 scf) developed using data from field-tested enclosed ground flares.
Test reports for nine units had useable data and were included in the development of an
emissions factor. These units had inlet gas volume flowrate as the available process data. These
useable emissions test reports are provided in Table 4-3. A list of available test report
information is provided in workbook "EF Creation_THC_ONGflare_2018February.xlsm".
The EPA's recommended emissions factor development procedures were followed for
the THC data. Test data from nine emissions units were combined for the emissions factor
development. The statistical analysis for determining outliers in the dataset was conducted, and
no data was found to be an outlier. As previously discussed, one of the last steps in developing
an emissions factor is a comparison of the FQI for test results. In the development of the
emissions factor for THC from enclosed ground flares based on field data, the FQI evaluation did
not exclude any test data from the dataset.
The workbook "EFCreation_THC_ONGflare_2018February.xlsm" provides the
emissions factor analysis, which characterizes the emissions factor as Poorly Representative.
Table 4-1 lists the SCCs applied to this factor and Table 4-2 provides a more detailed description
of each SCC.
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Table 4-1. Overview of the Emissions Factor for THC Expressed in Terms of Gas Volume
from Field-Tested Enclosed Ground Flares
No. of Units
Included in
Analysis
Test
Method
AP-42 Emissions Factor
Representativeness
SCC
9
EPA
Method 25A
332 lb THC (as propane)/
106scfgas burned
Poorly
31000205
31000212
31000227
Table 4-2. Description of SCC Included in Table 4-1
Level 1
Level 2
Level 3
Level 4
SCC
Description
Description
Description
Description
31000205
Industrial
Oil and Gas
Natural Gas
Flares
Processes
Production
Production
31000212
Industrial
Oil and Gas
Natural Gas
Condensate Storage
Processes
Production
Production
Tank
31000227
Industrial
Processes
Oil and Gas
Production
Natural Gas
Production
Glycol Dehydrator
Reboiler Still Stack
Table 4-3. Analysis of Emissions Test Reports for Field-Tested Units, Gas Volume Basis
Facility Name
Test Method
Average Test Result
ITR
Enterprise Products: Jackrabbit
Compressor Station
EPA Method
25A
601 lb THC/106 scf gas burned
47
Cimarron Energy: Greeley Gas Processing
Plant, 24" Unit "
EPA Method
25A
67.3 lb THC/106 scf gas burned
34
Cimarron Energy: Greeley Gas Processing
Plant, 48" Unit "
EPA Method
25A
87.4 lb THC/106 scf gas burned
34
Cimarron Energy: Greeley Gas Processing
Plant, 30" Unit
EPA Method
25A
51.5 lb THC/106 scf gas burned
37
ETC Canyon Pipeline, LLC: Debeque Gas
Plant
EPA Method
25A
403 lb THC/106 scf gas burned
32
ETC Canyon Pipeline, LLC: Rifle Bolton
EPA Method
25A
1,475 lb THC/106 scf gas burned
32
Que star Gas Management: Wonsits
Valley Compressor Station
EPA Method
25A
26.4 lb THC/106 scf gas burned
43
Cimarron Energy: Parshall
EPA Method
25A
243 lb THC/106 scf gas burned
42
Shell Exploration and Production Co.:
Pinedale
EPA Method
25A
35.2 lb THC/106 scf gas burned
37
12
-------
4.1.2 Heat Input Basis
Table 4-4 provides an overview of the THC emissions factor expressed in terms of gas
heat input (lb THC/106Btu) developed using data from field-tested enclosed ground flares. Six
test reports had useable data and were included in the development of an emissions factor. These
units had gas heat input rate as the available process data. These useable emissions test reports
are provided in Table 4-5. A list of available test report information is provided in workbook "EF
C reati onTHCON Gfl are_2018F ebruary. xl sm".
The EPA's recommended emissions factor development procedures were followed for
the THC data. Test data from six emissions units were combined for the emissions factor
development. The statistical analysis for determining outliers in the dataset was conducted, and
no data was found to be an outlier. As previously discussed, one of the last steps in developing
an emissions factor is a comparison of the FQI for test results. In the development of the
emissions factor for THC from enclosed ground flares based on field data, the FQI evaluation did
not exclude any test data from the dataset.
The workbook "EF Creation_THC_ONGflare_2018February.xlsm" provides the
emissions factor analysis, which characterizes the emissions factor as Poorly Representative.
Table 4-4. Overview of the Emissions Factor for THC Expressed in Terms of Heat Input
from Field-Tested Enclosed Ground Flares
No. of Units
Included in
Analysis
Test
Method
AP-42 Emissions Factor
Representativeness
scca
6
EPA
Method 25A
0.335 lb THC (as
propane )/106 Btu heat
input
Poorly
31000205
31000212
31000227
a A detailed description of these SCCs is included in Table 4-2.
Table 4-5. Analysis of Emissions Test Reports for Field-Tested Units, Heat Input Basis
Facility Name
Test Method
Average Test Result
ITR
Cimarron Energy: Greeley Gas
Processing Plant, 24" Unit
EPA Method 25A
0.029 lb THC/106Btu heat input
34
Cimarron Energy: Greeley Gas
Processing Plant, 48" Unit
EPA Method 25A
0.045 lb THC/106Btu heat input
34
Cimarron Energy: Greeley Gas
Processing Plant, 30" Unit
EPA Method 25A
0.026 lb THC/106Btu heat input
37
ETC Canyon Pipeline, LLC: Debeque
Gas Plant
EPA Method 25A
0.329 lb THC/106Btu heat input
32
ETC Canyon Pipeline, LLC: Rifle Bolton
EPA Method 25A
1.47 lb THC/106 Btu heat input
32
Cimarron Energy: Parshall
EPA Method 25A
0.106 lb THC/106 Btu heat input
42
13
-------
4.2 Manufacturer-Tested Enclosed Ground Flares - THC
The regulations in 40 CFR part 60 subparts OOOO and 0000a and 40 CFR part 63
subparts HH and HHH (hereinafter collective referred to as the "Oil and Gas sector rules")
provide owners and operators an exemption from performance testing if they purchase a unit that
has been tested by the manufacturer and the test demonstrates that the unit meets specific
requirements specified in these regulations.10 The criteria require that the unit achieve at least 95
percent destruction efficiency, average emissions of equal to or less than 10 parts per million by
volume (ppmv) wet THC (as propane), average emissions of equal to or less than 10 ppmv dry
carbon monoxide (CO), and no visible emissions while burning pure propylene under four test
conditions, with three test runs per condition. In the first condition, the unit is held steady at 90-
100 percent of the maximum design rate. In the second condition, the unit is ramped up and
down between 70 and 100 percent of the maximum design rate. In the third condition, the unit is
ramped up and down between 30 and 70 percent of the maximum design rate. In the fourth
condition, the unit is ramped up and down between 0 (or the minimum possible inlet flowrate)
and 30 percent of the maximum design rate.
As of December 1, 201711, 30 units12 were listed with a "Yes" in the "Control Device
Demonstrates Performance Requirements" column on the list maintained on the Oil and Gas
sector implementation page.13'14 Each of the test reports for these 30 units was reviewed,
analyzed, summarized, and given an ITR score. Based on the emissions test report review and
analysis, all the test reports for the 30 units had useable data and were included in the emissions
factor development process. The workbook "EF
Creation_THC_ONGflare_2018February.xlsm"provides a complete list of the available test
report information. The emissions data (lb THC/hr) in these test reports are based on
measurements taken with EPA Method 25A. Certain test runs were eliminated from the dataset
because the average value of the run was zero or negative. In most cases, the test report did not
10 In these subparts, these units are not considered flares. The definition of flare in these subparts specifically
excludes these units. In these subparts, a flare is defined as a thermal oxidation system using an open flame (without
enclosure).
11 Since December 1, 2017, two additional units have been listed with a "Yes" in the "Control Device Demonstrates
Performance Requirements" column. The EPA only included units that were listed as of December 1 in order to
provide enough time to perform the necessary data analysis and documentation for the emissions factors. Units listed
after December 1 will be included in any future reviews of the emissions factors.
12 There were actually 34 units listed with a "Yes" in the "Control Device Demonstrates Performance
Requirements" column, but four of these units are the same as other units sold under a different name. This is
indicted in footnotes to Tables 4-8 and 4-10.
13 https://www.epa.gov/stationarv-sources-air-pollution/performance-testing-combustion-control-devices-
manufacturers (EPA, 2012)
14 "Yes" means that the manufacturer has demonstrated that the specific model of control device listed achieves the
combustion control device performance requirements in NSPS subparts OOOO and OOOOa and NESHAP subparts
HH and HHH through performance testing conducted as specified in these subparts. "Yes" does not constitute an
endorsement by the EPA.
14
-------
include the lb/hr emission rate, and the EPA used the raw Method 25A, stack flowrate, and
moisture data to calculate the lb/hr emission rate.
The EPA's recommended emissions factor development procedures were followed for
the THC data associated with these manufacturer-tested units. Because testing was performed
under four different conditions, and it was uncertain what effect the conditions may have on
THC emissions, we conducted a statistical analysis to determine if these data all belong to the
same population. The statistical analysis showed that the data from the 0-to-30 percent ramping
condition do not belong to the same dataset as the rest of the conditions. Therefore, we divided
the data into two datasets. We also compared these two datasets to the field-tested units
discussed in Section 4.1 of this document. The statistical analysis showed that the data from the
field-tested units do not belong to either of these datasets. Therefore, we used the test reports
associated with the manufacturer-tested units to create four emissions factors: two for low-load
operating conditions (one expressed in terms of gas volume burned and another in terms of heat
input) and two for normal to high-load operating conditions (one expressed in terms of gas
volume burned and another in terms of heat input).15 We also conducted a statistical analysis to
determine outliers for each dataset, and found no data to be an outlier.
As discussed in Section 2.3 of this document, the last step in developing an emissions
factor is a comparison of the FQI for different units. When the FQI increases, only average test
values above the point where the FQI increases should be considered in the factor development.
In the development of the emissions factor for THC from manufacturer-tested enclosed ground
flares, the FQI evaluation excluded test data from two units from the dataset (these two reports
have the lowest ITR scores).
Finally, although we developed these factors using units tested for purposes of
demonstrating compliance with the Oil and Gas sector rules, we did not apply SCCs for natural
gas production to these emissions factors. In the Oil and Gas sector rules, propene (propylene)
must be used as the fuel during manufacturer performance testing16 even though it is not often
seen in natural gas production because propylene is harder to burn than methane and other
compounds expected to be sent to the enclosed combustor in the field. Therefore, while burning
propylene, it is expected to be more challenging for the units to meet the rules' required
destruction efficiency of at least 95 percent than if the unit were burning the fuel that would be
sent to the it in the field. However, the fact that the unit can meet the required destruction
efficiency, while useful in proving compliance with the rule, provides no information on the type
or quantity of compounds that would be expected to be emitted from a unit burning field gas, as
propylene is not generally a component of field gas. As such, the emissions data from the
manufacturer-tested units do not provide data that are appropriate for developing emissions
15 Data from only 29 test reports were used in the emissions factor development process for the low-load operating
condition. One test report was excluded because all of the test runs for that unit at the low load operating condition
were either negative values or zero. All 30 test reports were used in the emissions factor development process for the
normal to high-load operating condition.
16 See 40 CFR 60.5413(d)(2), 40 CFR 60.5413a(d)(2), 40 CFR 63.772(h)(2), and 40 CFR 63.1282(g)(2).
15
-------
factors for enclosed ground flares operating on natural gas production sites. The difference in
emissions profiles is demonstrated by the fact that the field-tested units and the manufacturer-
tested units are statistically not in the same dataset. Therefore, we did not apply the SCCs for
natural gas production to these units. We applied the same chemical manufacturing SCCs that
are applied to the original flare factors in AP-42 Table 13.5-1. The EPA developed those factors
based on flares burning an 80-20 mix of propylene and propane, which is similar to the
propylene burned by the enclosed ground flares during the manufacturer tests.
However, the fact that we did not apply natural gas production SCCs to these factors due
to the difference in emissions profiles between the manufacturer-tested units and enclosed
combustors burning field gas does not mean that the manufacturer-tested enclosed ground flares
should not be used to control emissions from natural gas production for purposes of complying
the Oil and Gas sector rules. These units have demonstrated high destruction efficiencies in a
controlled setting, well over 99 percent, well above the 95 percent reduction required in the Oil
and Gas sector rules.
16
-------
4.2.1 Gas Volume Basis
Table 4-6 provides an overview of the THC emissions factors expressed in terms of gas
volume burned (lb THC/106 scf) developed using data from manufacturer-tested enclosed ground
flares. Table 4-8 provides the useable emissions test reports. We based the low-load emissions
factor on the emissions test data from 29 test reports and the normal to high-load emissions
factor on the emissions test data from 30 test reports. Both factors are characterized as
Moderately Representative. The source classification codes applied to this factor are listed in
Table 4-6 and further described in Table 4-7.
Table 4-6. Overview of the Emissions Factors for THC Expressed in Terms of Gas Volume
from Manufacturer-Tested Enclosed Ground Flares
No. of Units
Included in
Analysis
Operating
Condition
Test
Method
AP-42 Emissions
Factor
Representativeness
SCC
30a
Normal to
High Percent
Load
EPA
Method 25A
2.56 lb THC (as
propane )/106 scf
gas burned
Moderately
30190099
30119701
30119705
30119709
30119741
29a
Low Percent
Loadb
EPA
Method 25A
8.37 lb THC (as
propane )/106 scf
gas burned
Moderately
a Two units were excluded from each dataset based on the FQI evaluation. This number represents the number of
units in the emissions factor analyses.
b Low percent load is represented by a unit operating at less than 30% of maximum load.
Table 4-7. Description of SCC Included in Table 4-6
SCC
Level 1
Description
Level 2
Description
Level 3
Description
Level 4
Description
30190099
Industrial
Processes
Chemical
Manufacturing
Fuel Fired Equipment
User Specified
30119701
Industrial
Processes
Chemical
Manufacturing
Butylene, Ethylene, Propylene,
Olefin Production
Ethylene: General
30119705
Industrial
Processes
Chemical
Manufacturing
Butylene, Ethylene, Propylene,
Olefin Production
Propylene: General
30119709
Industrial
Processes
Chemical
Manufacturing
Butylene, Ethylene, Propylene,
Olefin Production
Propylene: Fugitive
Emissions
30119741
Industrial
Processes
Chemical
Manufacturing
Butylene, Ethylene, Propylene,
Olefin Production
Ethylene: Flue Gas
Vent
17
-------
Table 4-8. Analysis of Emissions Test Reports for Manufacturer-Tested Units, Gas Volume Basis
Manufacturer Name
Unit Name
Test Method
Average Test Result in lb
THC/106 scf gas burned
ITR
Low Load
Normal to
High Load
ABUTEC
ABUTEC 20
EPA Method 25A
1.41
3.46
45
ABUTEC1
ABUTEC 20
EPA Method 25A
1.86
2.70
45
Alphabet Energy
Alphabet PGC
EPA Method 25A
30.4
10.9
76
Big Iron Oilfield Service
BNECU PI36
EPA Method 25A
7.15
2.28
49
Big Iron Oilfield Service
BNECU PI48b
EPA Method 25A
-
1.61
49
Black Gold Rush
BGR-18
EPA Method 25A
10.8
5.10
77
Cimarronc
CEI 1-24
EPA Method 25A
67.2
4.42
57
Cimarronc
CEI 1-30
EPA Method 25A
12.1
1.75
57
Cimarronc
CEI 1-48
EPA Method 25A
2.13
1.06
57
Cimarronc
CEI 1-60
EPA Method 25A
5.78
0.906
56
Cimarronc
48" HV ECD
EPA Method 25A
2.01
0.231
57
COMM Engineering
COMM OOOO
Combustor 200
EPA Method 25A
12.0
3.74
50
COMM Engineering
Model 2
EPA Method 25A
1.70
1.16
76
COMM Engineering
Model 3
EPA Method 25A
1.26
0.203
78
COMM Engineering
Model 4
EPA Method 25A
2.00
0.763
78
Coyote North
COMB 48"
EPA Method 25A
3.45
2.11
66
Hy-Bon/EDId
CH2.5
EPA Method 25A
3.82
2.31
75
Hy-Bon/EDId
CH10.0
EPA Method 25A
5.58
3.02
76
JLCC Combustion
FC 20
EPA Method 25A
3.09
1.75
52
John Zink
ZTOF040X30PF
EPA Method 25A
0.948
0.601
74
Kimark
KSF 1-48
EPA Method 25A
1.64
0.229
76
Leed Fabrication
36" Combustor
(EC36)
EPA Method 25A
14.5
2.45
57
Leed Fabrication®
48" Combustor
(EC48)
EPA Method 25A
78.0
10.1
30
Questor Technology
Q100
EPA Method 25A
1.31
1.97
56
Questor Technology
Q250
EPA Method 25A
7.07
4.55
56
REM Technology
(Spartan Controls)6
SlipStream GTS-12
EPA Method 25A
1.19
1.59
20
SFI Oil & Gas Production
Systems
SCD-36
EPA Method 25A
3.06
3.41
76
SFI Oil & Gas Production
Systems
SCD-48
EPA Method 25A
11.4
3.32
77
SFI Oil & Gas Production
Systems
SCD-60
EPA Method 25A
4.51
1.99
58
Zeeco, Inc.
EGF-48-30 (aka
EGF-4-30)
EPA Method 25A
7.83
3.66
58
a Also known as NOV MEVC 20 and MEVC 100.
b All test runs were negative values or zero, and this unit was removed from the dataset for the low load condition.
0 In the draft proposal, the EPA inadvertently used an older version of these test reports. The corrected, updated
versions were used in determining the final emissions factors.
d Also known as GCO ECD 1600 and GCO ECD 2000.
e These emissions units were excluded from the dataset for both emissions factors based on the FQI evaluation.
18
-------
4.2.2 Heat Input Basis
Table 4-9 provides an overview of the THC emissions factors expressed in terms of heat
input (lb THC/106Btu) developed using data from manufacturer-tested enclosed ground flares.
Table 4-10 provides the useable emissions test reports. We based the low-load emissions factor
on the emissions test data from 29 test reports and the normal to high-load emissions factor on
the emissions test data from 30 test reports. Both factors are characterized as Moderately
Representative.
Table 4-9. Overview of the Emissions Factors for THC Expressed in Terms of Heat Input
from Manufacturer-Tested Enclosed Ground Flares
No. ol' l nits
Included in
Aiiiilvsis
Opernlin"
Condition
Test
Method
AI>-42 Emissions
I'iiclor
kcpiTscnliilh encss
sec1
30a
Normal to
High Percent
Load
EPA
Method 25A
1.20e-3 lb THC
(as propane)/
106 Btu heat input
Moderately
30190099
30119701
30119705
30119709
30119741
29a
Low Percent
Loadb
EPA
Method 25A
3.88e-3 lb THC
(as propane)/
106 Btu heat input
Moderately
a Two units were excluded from each dataset based on the FQI evaluation. This number represents the number of
units in the emissions factor analyses.
b Low percent load is represented by a unit operating at less than 30% of maximum load.
0 A detailed description of these SCCs is included in Table 4-7.
19
-------
Table 4-10. Analysis of Emissions Test Reports for Manufacturer-Tested Units, Heat Input Basis
Manufacturer Name
Unit Name
Test Method
Average Test Result in lb
THC/106Btu Heat Input
ITR
Low Load
Normal to
High Load
ABUTEC
ABUTEC 20
EPA Method 25A
6.50E-04
1.59E-03
45
ABUTEC1
ABUTEC 20
EPA Method 25A
8.60E-04
1.25E-03
45
Alphabet Energy
Alphabet PGC
EPA Method 25A
1.40E-02
4.99E-03
76
Big Iron Oilfield Service
BNECU PI36
EPA Method 25A
3.29E-03
1.05E-03
49
Big Iron Oilfield Service
BNECU PI48b
EPA Method 25A
-
7.58E-04
49
Black Gold Rush
BGR-18
EPA Method 25A
5.01E-03
2.37E-03
77
Cimarron
CEI 1-24
EPA Method 25A
3.09E-02
2.05E-03
57
Cimarron
CEI 1-30
EPA Method 25A
5.57E-03
8.16E-04
57
Cimarron
CEI 1-48
EPA Method 25A
9.80E-04
4.85E-04
57
Cimarron
CEI 1-60
EPA Method 25A
2.67E-03
4.22E-04
56
Cimarron
48" HV ECD
EPA Method 25A
9.25E-04
1.07E-04
57
COMM Engineering
COMM OOOO
Combustor 200
EPA Method 25A
5.65E-03
1.94E-03
50
COMM Engineering
Model 2
EPA Method 25A
1.00E-03
5.65E-04
76
COMM Engineering
Model 3
EPA Method 25A
6.54E-04
1.00E-04
78
COMM Engineering
Model 4
EPA Method 25A
9.56E-04
3.75E-04
78
Coyote North
COMB 48"
EPA Method 25A
1.58E-03
9.82E-04
66
Hy-Bon/EDIc
CH2.5
EPA Method 25A
1.86E-03
1.13E-03
75
Hy-Bon/EDIc
CH10.0
EPA Method 25A
2.60E-03
1.41E-03
76
JLCC Combustion
FC 20
EPA Method 25A
1.41E-03
8.14E-04
52
John Zink
ZTOF040X30PF
EPA Method 25A
4.37E-04
2.78E-04
74
Kimark
KSF 1-48
EPA Method 25A
7.64E-04
1.07E-04
76
Leed Fabrication
36" Combustor
(EC36)
EPA Method 25A
6.67E-03
1.13E-03
57
Leed Fabricationd
48" Combustor
(EC48)
EPA Method 25A
3.61E-02
4.79E-03
30
Questor Technology
Q100
EPA Method 25A
6.12E-04
9.39E-04
56
Questor Technology
Q250
EPA Method 25A
3.28E-03
2.12E-03
56
REM Technology
(Spartan Controls)d
SlipStream GTS-12
EPA Method 25A
5.58E-04
7.42E-04
20
SFI Oil & Gas Production
Systems
SCD-36
EPA Method 25A
1.41E-03
1.57E-03
76
SFI Oil & Gas Production
Systems
SCD-48
EPA Method 25A
5.21E-03
1.53E-03
77
SFI Oil & Gas Production
Systems
SCD-60
EPA Method 25A
2.07E-03
9.21E-04
58
Zeeco, Inc.
EGF-48-30 (aka
EGF-4-30)
EPA Method 25A
3.59E-03
1.69E-03
58
a Also known as NOV MEVC 20 and MEVC 100.
b All test runs were negative values or zero, and this unit was removed from the dataset for the low load condition.
c Also known as GCO ECD 1600 and GCO ECD 2000.
d These emissions units were excluded from the dataset for both emissions factors based on the FQI evaluation.
20
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Section 5
Clarification of Heating Value Basis
In addition to adding new emissions factors to AP-42 Section 13.5, the EPA is adding
footnotes to Tables 13.5-1 through 13.5-3 to clarify the heating value basis that was used to
develop each factor. This clarification only applies to factors that are based on heating value, i.e.,
lb/106 Btu.
The heating value of a fuel is the energy released during combustion, generally expressed
as energy per mass of fuel (e.g., Btu/lb) or energy per volume of fuel (e.g., Btu/scf). Heating
value can be presented in two different forms. The higher heating value (also known as the gross
heating value or upper heating value) takes into account the latent heat of vaporization of water
in the combustion products. The lower heating value (also known as the net heating value or
lower heating value) subtracts the heat of vaporization of water vapor from the higher heating
value; it accounts for no recovery of the latent heat of vaporization of any water in the fuel or
water produced from combustion. The difference between the two heating values is more
pronounced as the content of hydrogen in the fuel increases, because hydrogen combines with
oxygen to create water during the combustion process.
It is necessary to clarify the heating value basis of the emissions factors in Section 13.5 in
order for users to more accurately estimate emissions. For example, the higher heating value of
propylene is 2336 Btu/scf and the lower heating value is 2185 Btu/scf. This means that for each
100 scf/hr of propylene burned, the higher heating value will estimate 0.0151 lb/hr more
emissions than the lower heating value. For a large flare, this difference would be more
prominent and could produce estimates that differ by hundreds or even thousands of pounds per
year. To resolve this issue, we are footnoting Tables 13.5-1 through 13.5-3 with the heating
value basis that was used when the factors were developed.
Additionally, based on comments received after proposal, we are adding clarifying
footnotes to Tables 13.5-1 through 13.5-3 to indicate that the emissions factors represent the
emissions exiting a flare, not the uncontrolled emissions entering the flare from the associated
process unit.
21
-------
Section 6
Conclusions
The following final actions are based on a review of available test reports associated with
flares at natural gas production sites.
1. Based on its review of available data, the EPA has concluded that it is not necessary
to revise the existing VOC emissions factor in WebFIRE for flares at natural gas
production sites.
2. The EPA has developed two THC emissions factors from field-tested units burning
field gas and is applying natural gas production SCCs to these factors. The EPA
recommends the use of these THC emissions factors instead of the VOC emissions
factor in WebFIRE for estimating VOC emissions from enclosed ground flares at
natural gas production sites.
3. The existing VOC emissions factor in WebFIRE remains available for estimating
emissions from elevated flares at natural gas production sites.
4. The EPA has developed four factors from manufacturer-tested units burning pure
propylene. The factors are based on the percent load of the inlet gas burned, with two
factors applying to low-load conditions and the other two factors applying to normal
to high-load conditions. The EPA is applying chemical manufacturing SCCs to these
factors.
5. The EPA has included these six new THC emissions factors as an update to AP-42
Section 13.5.
6. The EPA is clarifying the heating value basis for the emissions factors in AP-42
Tables 13.5-1 through 13.5-3 in order to allow users to generate more accurate
emissions estimates and clarifying that the emissions factors in the tables represent
the emissions at the exit of a flare, not the uncontrolled VOC or THC emissions
routed to the flare.
22
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Section 7
References
Air Alliance Houston, et al. v. McCarthy, No. l:16-cv-01998-RC (D.D.C.).
EPA (U.S. Environmental Protection Agency). 1990. AIRS Facility Subsystem Source
Classification Codes and Emission Factor Listing for Criteria Air Pollutants. U. S.
Environmental Protection Agency, Office of Air Quality Planning and Standards. EPA
450/4-90-003. March 1990.
EPA (U.S. Environmental Protection Agency). 1995. Compilation of Air Pollutant Emission
Factors, Volume 1: Stationary Point and Area Sources. AP-42, Fifth Edition, U.S.
Environmental Protection Agency, Office of Air Quality Planning and Standards. January
1995. Available at: https://www.epa.gov/air-emissions-factors-and-quantification/ap-42-
compilation-air-emission-factors
EPA (U.S. Environmental Protection Agency). 2012. Performance Testing for Combustion
Control Devices Manufacturers' Performance Test New Source Performance Standards
(NSPS) OOOO, OOOOa and Maximum Achievable Control Technology HH/HHH. Last
Updated December 14, 2017. Available at: https://www.epa.gov/stationary-sources-air-
pollution/performance-testing-combustion-control-devices-manufacturers
EPA (U.S. Environmental Protection Agency). 2013. Recommended Procedures for
Development of Emissions Factors and Use of the WebFIRE Database. U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards. August 2013 (Draft Final).
Available at: https://www.epa.gov/air-emissions-factors-and-quantification/procedures-
development-emissions-factors-stationary-sources
ERG (Eastern Research Group). 2018. Summary of EPA Responses to Public Comments
Received on the Proposed Emissions Factors for Enclosed Ground Flares at Natural Gas
Production Sites and Chemical Manufacturing Processes. February 1, 2018. Available at:
https://www3.epa.gov/ttn/chief/consentdecree/ONGflare/response to comments.pdf
23
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Appendix A
CONSENT DECREE
-------
Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 1 of 10
UNITED STATES DISTRICT COURT
FOR THE DISTRICT OF COLUMBIA
)
AIR ALLIANCE HOUSTON, el al„ )
)
) Case No. 1:16-cv-01998 (RC)
Plaintiffs, )
)
)
)
GINA McCarthy, Administrator, United ) CONSENT DECREE
States Environmental Protection Agency, in )
her official capacity, )
)
Defendant. )
)
)
)
WHEREAS, on October 16, 2016, Plaintiffs, Air Alliance Houston, Community In-
Power and Development Association, Inc., Louisiana Bucket Brigade, and Texas Environmental
Justice Advocacy Services, filed their Complaint alleging that Gina McCarthy, in her official
capacity as Administrator of the United States Environmental Protection Agency ("EPA"), failed
to perform nondiscretionary duties under Clean Air Act ("CAA") Section 130, 42 U.S.C. § 7430.
Specifically, Plaintiffs allege that EPA failed to review and, if necessary, revise the emissions
factor for volatile organic compounds ("VOCs") from elevated flares and enclosed ground flares
at natural gas production sites in the source category entitled "Crude Oil and Natural Gas
Production, Transmission and Distribution" (ONG source category) at least once every three
years. 42 U.S.C. § 7430;
WHEREAS, for purposes of this Consent Decree, an "elevated flare" is defined to be a
thermal oxidation system using an open flame without an enclosure;
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 2 of 10
WHEREAS, for purposes of this Consent Decree, an "enclosed ground flare" is defined
to be a thermal oxidation system using a flame with an enclosure;
WHEREAS, for purposes of this Consent Decree, "natural gas production sites" are
defined as the wells and all related processes used in the extraction, production, recovery, lifting,
stabilization, separation or treating of natural gas (including condensate). "Natural gas
production sites" include not only the pads where the wells are located, but also include stand-
alone sites where natural gas (including condensate and produced water) from several wells may
be separated, stored and treated."
WHEREAS, the relief requested in the Complaint includes, among other things, an order
from this Court to establish a date certain by which EPA must complete a review of the VOC
emissions factor for elevated flares and enclosed ground flares at natural gas production sites in
the ONG source category, and either revise this factor or make a final determination that revision
is not appropriate as required by CAA Section 130, 42 U.S.C. § 7430;
W11 ERE AS, the only segment in the ONG source category for which EPA has and
maintains an existing VOC emissions factor for flares is at the natural gas production sites, and
EPA includes this VOC emission factor in its WebFIRE database (SCC 31000205) (hereafter
referred to as the "Natural Gas VOC emissions factor");
WHEREiAS, EPA has not conducted a review of the Natural Gas VOC emissions factor
or revised this factor under CAA Section 130, 42 U.S.C. § 7430 in over three years;
WHEREAS, before filing the Complaint in this action. Plaintiffs served notice on EPA as
required by the CAA to inform EPA of Plaintiffs' intent to initiate the present action;
WHEsREAS, Plaintiffs and EPA (collectively "the Parties") have agreed to a settlement of
tin's action without admission of any issue of fact or law, except as expressly provided herein;
2
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 3 of 10
WHEREAS, the Parties, by entering into this Consent Decree, do not waive or limit any
claim, remedy, or defense, on any grounds, related to any final EPA action;
WHEREAS, the Parties consider this Consent Decree to be an adequate and equitable
resolution of all the claims in this matter and therefore wish to effectuate a settlement;
WHEREAS, it is in the interest of the public, Plaintiffs, EPA, and judicial economy to
resolve this matter without protracted litigation;
WHEREAS, the Parties agree that this Court has jurisdiction over this matter pursuant to
the citizen suit provision in CAA section 304(a)(2), 42 U.S.C, § 7604(a)(2), and that venue is
proper in the United States District Court for the District of Columbia pursuant to 28 U.S.C.
§ 1391(e);
WHEREAS, the Court, by entering this Consent Decree, finds that the Consent Decree is
fair, reasonable, in the public interest, and consistent with the Clean Air Act;
NO W THEREFORE, before the taking of testimony, without trial or determination of
any issues of fact or law, and upon the consent of the Parties, it is hereby ordered, adjudged and
decreed that:
1. This Court has jurisdiction over the claims set forth in the Complaint and may
order the relief contained in the Consent Decree. Venue is proper in the United States District
Court for the District of Columbia.
2. For the Natural Gas VOC emissions factor for elevated flares and enclosed
ground flares at the natural gas production sites in the ONG source category, the EPA
Administrator shall:
a. no later than June 5, 2017, review and either propose revisions to the Natural Gas
VOC emissions factor under CAA section 130, 42 U.S.C. § 7430, or propose a
3
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 4 of 10
determination that revision of the Natural Gas VOC emissions factor is not
necessary under CAA section 130,
b, no later than February 5, 2018, issue final revisions to the Natural Gas VOC
emissions factor under CAA section 130. or issue a final determination that
revision of the Natural Gas VOC emissions factor is not necessary under CAA
section 130.
3. EPA shall post the proposed revision or determination and the final revision or
determination, as described in paragraph 2 of this Consent Decree, on its AP-42 website (located
at http://www.epa.gov/ttn/chief/ap42A) on the dates described in paragraph 2. In addition, EPA
shall provide a copy of each such action to Plaintiffs' counsel indicated in Paragraph 15 within
seven days of posting.
4. Once EPA has completed ail of the actions set forth above and after the final
actions required by paragraphs 2 and 3 have been completed, EPA may move to have this
Consent Decree terminated, and the action dismissed. Plaintiffs shall have 30 days in which to
respond to such motion.
5. The deadlines established by this Consent Decree may be modified (a) by written
stipulation of EPA and Plaintiffs with notice to the Court, or (b) by the Court on motion of EPA
for good cause shown pursuant to the Federal Rules of Civil Procedure, and upon consideration
of any response by Plaintiff(s). Any other provision of this Consent Decree also may be
modified by the Court following motion of an undersigned party for good cause shown pursuant
to the Federal Rules of Civil Procedure and upon consideration of any response by a non-moving
party.
4
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 5 of 10
6. If a lapse in appropriations for EPA occurs within ninety (90) days prior to the
deadlines in Paragraph 2 of this Consent Decree, those deadlines will be extended automatically
one day for each day of the lapse in appropriations. Nothing in this paragraph shall preclude EPA
from seeking an additional extension through modification of this Consent Decree pursuant to
Paragraph 5.
7. In the event of a dispute between the Parties concerning the interpretation or
implementation of any aspect of this Consent Decree, the disputing party shall provide the other
parlies with a written notice outlining the nature of the dispute and requesting informal
negotiations. The Parties shall meet and confer in order to attempt to resolve the dispute. If the
Parties are unable to resolve the dispute within 14 days after receipt of the notice, a party may
petition the Court to resolve the dispute.
8. This Court shall retain jurisdiction over this matter to enforce the terms of this
Consent Decree and to consider any requests from Plaintiffs for costs of litigation, including
attorney fees.
9. Nothing in the terms of this Consent Decree shall be construed (a) to confer upon
this Court jurisdiction to review any final rule or determination issued by EPA pursuant to this
Consent Decree, (b) to confer upon this Court jurisdiction to review any issues that are within the
exclusive jurisdiction of the United States Courts of Appeals under CAA section 307(b)(1), 42
U.S.C, § 7607(b)(1), or (c) to waive any claims, remedies, or defenses that the Parties may have
under CAA section 307(b)(1), 42 U.S.C. § 7607(b)(1).
10. Nothing in this Consent Decree shall be construed to limit or modify any
discretion accorded EPA by the Clean Air Act or by general principles of administrative law in
taking the actions which are the subject of this Consent Decree, including the discretion to alter,
5
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 6 of 10
amend, or revise any final actions promulgated pursuant to this Consent Decree. EPA's
obligation to perform each action specified in this Consent Decree does not constitute a
limitation or modification of EPA's discretion within the meaning of this paragraph,
11. Except as expressly provided herein, nothing in this Consent Decree shall be
construed as an admission of any issue of fact or law. By entering into this Consent Decree,
EPA and Plaintiffs do not waive or limit any claim, remedy, or defense, on any grounds, related
to any final action EPA takes with respect to the actions addressed in this Consent Decree,
12. The Parties agree the Clean Air Act provides for the recovery of the costs of
litigation (including attorneys' fees) incurred in this matter pursuant to section 304(d) of the
CAA, 42 U.S.C. § 7604(d). The deadline for filing a motion for costs of litigation (including
attorney fees) for activities performed prior to entry of the Consent Decree is hereby extended
until ninety (90) days after this Consent Decree is entered by the Court. During this period, the
Parties shall seek io resolve informally any claim for costs of litigation (including attorney fees),
and if they cannot, Plaintiffs will file a motion for costs of litigation (including attorney fees) or a
stipulation or motion to extend the deadline to file such a motion. EPA reserves the right to
oppose any such request.
13. Plaintiffs reserve the right to seek additional costs of litigation, including attorney
fees, incurred subsequent to entry of this Consent Decree and arising from Plaintiffs' need to
enforce or defend against efforts to modify its terms or the underlying schedule outlined herein,
or for any other unforeseen continuation of this action, EPA reserves the right to oppose any
such request.
14. It is hereby expressly understood and agreed that this Consent Decree was jointly
drafted by Plaintiffs and EPA. Accordingly, the Parties hereby agree that any and all rules of
6
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 7 of 10
construction to the effect that ambiguity is construed against the drafting party shall be
inapplicable in any dispute concerning the terms, meaning, or interpretation of this Consent
Decree.
15. The Parties agree and acknowledge that before this Consent Decree is entered by
the Court, EPA must provide notice of this Consent Decree in the Federal Register and an
opportunity for public comment pursuant to CAA section 113(g), 42 U.S.C. § 7413(g). After
this Consent Decree has undergone notice and comment, the Administrator and/or the Attorney
General, as appropriate, shall promptly consider any written comments received in determining
whether to withdraw or withhold their consent to the Consent Decree, in accordance with CAA
section 113(g). If the Administrator and the Attorney General do not elect to withdraw or
withhold consent, EPA shall promptly file a motion that requests that the Court enter this
Consent Decree.
16. Any notices required or provided for by this Consent Decree shall be in writing,
via electronic mail or certified mail, and sent to each of the following counsel (or to any new
address of the Parties' counsel as filed and listed in the docket of the above-captioned matter, at a
future date):
a. For Plaintiffs Air Alliance Houston, Community In-Power and Development
Association, Inc., Louisiana Bucket Brigade, and Texas Environmental Justice
Advocacy Services:
Sparsh Khandeshi
Environmental Integrity Project
1000 Vermont Avenue, Suite 1100
Washington, D.C. 20005
skhandesh i@en v i ron menta 1 i ntegritv.org
Tel:" 202-263-4446
Eric Schaeffer
Environmental Integrity Project
7
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 8 of 10
1000 Vermont Avenue, Suite 1100
Washington, D.C. 20005
eschaeffer@environmentalintegritv.org
Tel: 202-263-4440
b. For Defendant EPA:
MScheie L, Waiter
United States Department of Justice
Environment & Natural Resources Division
999 18,h St.
Suite 370 - South Terrace
Denver, Colorado 80202
inichele.waller@usdoi.gov
Tel: 303-844-1345
17. EPA and Plaintiffs recognize and acknowledge that the obligations imposed upon
EPA under this Consent Decree can only be undertaken using appropriated funds legally
available for such purpose. No provision of this Consent Decree shall be interpreted as or
constitute a commitment or requirement that the United States obligate or pay funds in
contravention of the Anti-Deficiency Act, 31 U.S.C, § 1341, or any other applicable provision of
law.
18. If for any reason the Court should decline to approve this Consent Decree in the
form presented, this agreement is voidable at the sole discretion of either party and the terms of
the proposed Consent Decree may not be used as evidence in any litigation between the Parties.
19. The undersigned representatives of Defendant EPA and Plaintiffs Air Alliance
Houston, Community In-Power and Development Association, Inc., Louisiana Bucket Brigade,
and Texas Environmental Justice Advocacy Services certify that they are fully authorized by the
party they represent to consent to the Court's entry of the terms and conditions of this Consent
Decree,
8
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 9 of 10
COUNSEL FOR PLAINTIFFS:
Dated: December 1, 2016
/s/ Sparsh Khandeshi
Sparsh Khandeshi
Environmental Integrity Project
1000 Vermont Avenue, Suite 1100
Washington, D.C. 20005
s khandeshi@env[>onmentali'iuegiity,org
Tel: 202-263-4446
Eric Schaeffer
Environmental Integrity Project
1000 Vermont Avenue, Suite 1100
Washington, D.C, 20005
eschaeffer@environmen.tajintei2rity.org
Tel: 202-263-4440
Counsel for Plaintiffs Air Alliance Houston,
Community In-Power and Development
Association, Inc., Louisiana Bucket Brigade, and
Texas Environmental Justice Advocacy Services
COUNSEL FOR DEFENDANT;
Dated: December I, 2016 Is/ Michele L. Walter
JOHN C, CRUDEN
Assistant Attorney General
Environment & Natural Resources Division
MICHELE L. WALTER, D.C, Bar No. 487329
United States Department of Justice
Environment & Natural Resources Division
999 18,h St.
Suite 370 - South Terrace
Denver, Colorado 80202
Tel: 303-844-1345
E-mai 1: inichele.wa 1 ter@usdoi.tiov
Counsel for Defendant EPA
9
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Case l:16-cv-01998-RC Document 12 Filed 12/07/16 Page 10 of 10
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Appendix B
EPA'S "TEST QUALITY RATING TOOL" TEMPLATE
(ITR TEMPLATE)
August 2013
-------
A
B I G
H I N
1
Name of Facility where the test was performed
2
Name of Company performinq stationary source test
3
SCC of tested unit or units
4
Name of assessor and name of employer.
5
Name of regulatory assessor and regulatory agency name.
6
7
8
Emissions Factor Development Quality Indicator Value Rating 0
10
/ $/ /
Supporting Documentation Provided / & / Regulatory Agency Review /
/ <5* / / c«
/«?/ A*
V/
£ / Justification
y
11
General
12
As described in ASTM D7036-12 Standard Practice for
Competence of Air Emission Testing Bodies, does the testing
firm meet the criteria as an AETB or is the person in charge of
the field team a Ql for the type of testing conducted? A
certificate from an independent organization (e.g., Stack
Testing Accreditation Council (STAC), California Air
Resources Board (CARB), National Environmental Laboratory
Accreditation Program (NELAP)) or self declaration provides
documentation of competence as an AETB.
As described in ASTM D7036-12 Standard Practice for
Competence of Air Emission Testing Bodies, does the testing
firm meet the criteria as an AETB or is the person in charge of
the field team a Ql for the type of testing conducted? A
certificate from an independent organization (e.g., STAC,
CARB, NELAP) or self declaration provides documentation of
competence as an AETB.
13
Was a representative of the regulatory agency on site during
the test?
14
Is a description and drawinq of test location provided?
Is a description and drawinq of test location provided?
15
Has a description of deviations from published test methods
been provided, or is there a statement that deviations were not
required to obtain data representative of typical facility
operation?
Is there documentation that the source or the test company
sought and obtained approval for deviations from the
published test method prior to conducting the test or that the
tester's assertion that deviations were not required to obtain
data representative of operations that are typical for the
facility?
16
Were all test method deviations acceptable?
17
Is a full description of the process and the unit being tested
(including installed controls) provided?
Is a full description of the process and the unit being tested
(including installed controls) provided?
18
Has a detailed discussion of source operating conditions, air
pollution control device operations and the representativeness
of measurements made during the test been provided?
Has a detailed discussion of source operating conditions, air
pollution control device operations and the representativeness
of measurements made during the test been provided?
19
Were the operating parameters for the tested process unit and
associated controls described and reported?
Is there documentation that the required process monitors
have been calibrated and that the calibration is acceptable?
20
Was the process capacity documented?
21
Was the process operating within an appropriate range for the
test program objectives?
22
Were process data concurrent with testing?
23
Were data included in the report for all parameters for which
limits will be set?
24
Is there an assessment of the validity, representativeness,
achievement of DQO's and usability of the data?
Did the report discuss the representativeness of the facility
operations, control device operation, and the measurements of
the target pollutants, and were any changes from published
test methods or process and control device monitoring
protocols identified?
25
Have field notes addressing issues that may influence data
quality been provided?
Were all sampling issues handled such that data quality was
not adversely affected?
26
Manual Test Methods
27
Have the following been included in the report:
28
Dry gas meter (DGM) calibrations, pitottube and nozzle
inspections?
Was the DGM pre-test calibration within the criteria specified
by the test method?
29
Was the DGM post-test calibration within the criteria specified
by the test method?
30
Were thermocouple calibrations within method criteria?
31
Was the pitottube inspection acceptable?
32
Were nozzle inspections acceptable?
33
Were flow meter calibrations acceptable?
34
Was the Method 1 sample point evaluation included in the
report?
Were the appropriate number and location of sampling points
used?
35
Were the cyclonic flow checks included in the report?
Did the cyclonic flow evaluation show the presence of an
acceptable average gas flow angle?
36
Were the raw sampling data and test sheets included in the
report?
Were all data required by the method recorded?
37
Were required leak checks performed and did the checks meet
method requirements?
38
Was the required minimum sample volume collected?
39
Did probe, filter, and impinger exit temperatures meet method
criteria (as applicable)?
40
Did isokinetic sampling rates meet method criteria?
ITR.xIsx
ITR
-------
A
B
G
H
N
41
Was the sampling time at each point greater than 2 minutes
and the same for each point?
42
Did the report include a description and flow diagram of the
recovery procedures?
Was the recovery process consistent with the method?
43
Were all required blanks collected in the field?
44
Where performed, were blank corrections handled per method
requirements?
45
Were sample volumes clearly marked on the jar or measured
and recorded?
46
Was the laboratory certified/accredited to perform these
analyses?
Was the laboratory certified/accredited to perform these
analyses?
47
Did the report include a complete laboratory report and flow
diaqram of sample analysis?
Did the laboratory note the sample volume upon receipt?
48
If sample loss occurred, was the compensation method used
documented and approved for the method?
49
Were the physical characteristics of the samples (e.g., color,
volume, integrity, pH, temperature) recorded and consistent
with the method?
50
Were sample hold times within method requirements?
51
Does the laboratory report document the analytical procedures
and techniques?
52
Were all laboratory QA requirements documented?
53
Were analytical standards required by the method
documented?
54
Were required laboratory duplicates within acceptable limits?
55
Were required spike recoveries within method requirements?
56
Were method-specified analytical blanks analyzed?
57
If problems occurred during analysis, is there sufficient
documentation to conclude that the problems did not adversely
affect the sample results?
58
Was the analytical detection limit specified in the test report?
59
Is the reported detection limit adequate for the purposes of the
test proqram?
60
Were the chain-of-custody forms included in the report?
Do the chain-of-custody forms indicate acceptable
management of collected samples between collection and
analysis?
61
62
Have the following been included in the report:
63
Did the report include a complete description of the
instrumental method sampling system?
Was a complete description of the sampling system provided?
64
Did the report include calibration gas certifications?
Were calibration standards used prior to the end of the
expiration date?
65
Did calibration standards meet method criteria?
66
Did report include interference tests?
Did interference checks meet method requirements?
67
Were the response time tests included in the report?
Was a response time test performed?
68
Were the calibration error tests included in the report?
Did calibration error tests meet method requirements?
69
Did the report include drift tests?
Were drift tests performed after each runanddidthey meet
method requirements?
70
Did the report include system bias tests?
Did system bias checks meet method requirements?
71
Were the converter efficiency tests included in the report?
Was the NOX converter test acceptable?
72
Did the report include stratification checks?
Was a stratification assessment performed?
73
Did the report include the raw data for the instrumental
method?
Was the duration of each sample run within method criteria?
74
Was an appropriate traverse performed during sample
collection, or was the probe placed at an appropriate center
point (if allowed by the method)?
75
Were sample times at each point uniform and did they meet
the method requirements?
76
Were sample lines heated sufficiently to prevent potential
adverse data quality issues?
77
Was all data required by the method recorded?
88
89
90
91
92
93
Total
Manual Test 0
Instrumental Test 0
ITR.xIsx
ITR
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