Document ID: EPA-HQ-OAR-2014-0738-0032
Agency: epa
Document Type: Proposed Rule
Title: Notice of Final Approval for the Operation of Pressure-Assisted Multi-Point Ground Flares at The Dow Chemical Company and ExxonMobil
Chemical Company and Notice of Receipt of Approval Request for the Operation of a Pressure-Assisted Multi-Point Ground Flare at Occidental Chemical Corporation
Posted Date: 2015-08-31T04:00Z

[Federal Register Volume 80, Number 168 (Monday, August 31, 2015)]
[Proposed Rules]
[Pages 52426-52436]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-21420]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 60, 61 and 63

[EPA-HQ-OAR-2014-0738; FRL-9933-16-OAR]

Notice of Final Approval for the Operation of Pressure-Assisted 
Multi-Point Ground Flares at The Dow Chemical Company and ExxonMobil 
Chemical Company and Notice of Receipt of Approval Request for the 
Operation of a Pressure-Assisted Multi-Point Ground Flare at Occidental 
Chemical Corporation

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice; approval and request for comments.

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SUMMARY: This notice announces our approval of the Alternative Means of 
Emission Limitation (AMEL) requests for the operation of multi-point 
ground flares (MPGF) at The Dow Chemical Company's (Dow) Propane 
Dehydrogenation Plant and Light Hydrocarbons Plant located at its Texas 
Operations site in Freeport, Texas, and the ExxonMobil Chemical Company 
(ExxonMobil) Olefins Plant in Baytown, Texas, and its Plastics Plant in 
Mont Belvieu, Texas. This approval notice also specifies the operating 
conditions and monitoring, recordkeeping, and reporting requirements 
for demonstrating compliance with the AMEL that these facilities must 
follow.
    In addition, this notice solicits comments on an all aspects of an 
AMEL request from Occidental Chemical Corporation (OCC) in which long-
term MPGF burner stability and destruction efficiency have been 
demonstrated on different pressure-assisted MPGF burners that OCC has 
proposed for use in controlling emissions at its Ingleside, Texas, 
ethylene plant.
    Lastly, this notice presents and solicits comments on all aspects 
of a framework of both MPGF burner testing and rule-specific emissions 
control equivalency demonstrations that we anticipate, when followed, 
would afford us the ability to approve future AMEL requests for MPGF in 
a more efficient and streamlined manner.

DATES: The AMEL for the MPGF at Dow's Propane Dehydrogenation Plant and 
Light Hydrocarbons Plant located at its Texas Operations site in 
Freeport, Texas, and ExxonMobil's Olefins Plant in Baytown, Texas, and 
Plastics Plant in Mont Belvieu, Texas are approved and effective August 
31, 2015.
    Comments. Written comments on the AMEL request from OCC for their 
MPGF in Ingleside, Texas, or on the framework for streamlining future 
MPGF AMEL requests must be received on or before October 15, 2015.
    Public Hearing. Regarding the OCC MPGF in Ingleside, Texas, or the 
framework for streamlining future MPGF AMEL requests, if requested by 
September 8, 2015, we will hold a public hearing on September 15, 2015, 
from 1:00 p.m. [Eastern Standard Time] to 8:00 p.m. [Eastern Standard 
Time] in Corpus Christi, Texas. We will provide details on the public 
hearing on our Web site at: http://www.epa.gov/ttn/atw/groundflares/groundflarespg.html. To be clear, a public hearing will not be held 
unless someone specifically requests that the EPA hold a public hearing 
regarding the OCC MPGF or the framework for streamlining future MPGF 
AMEL requests. Please contact Ms. Virginia Hunt of the Sector Policies 
and Programs Division (E143-01), Office of Air Quality Planning and 
Standards, Environmental Protection Agency, Research Triangle Park, NC 
27711; telephone number: (919) 541-0832; email address: 
hunt.virginia@epa.gov; to request a public hearing, to register to 
speak at the public hearing or to inquire as to whether a public 
hearing will be held. The last day to pre-register in advance to speak 
at the public hearing will be September 14, 2015.

ADDRESSES: Submit your comments, identified by Docket ID Number EPA-HQ-
OAR-2014-0738, to the Federal eRulemaking Portal: http://www.regulations.gov. Follow the online instructions for submitting 
comments. Once submitted, comments cannot be edited or withdrawn. The 
EPA may publish any comment received to its public docket. Do not 
submit electronically any information you consider to be Confidential 
Business Information (CBI) or other information whose disclosure is 
restricted by statute. Multimedia submissions (audio, video, etc.) must 
be accompanied by a written comment. The written comment is considered 
the official comment and should include discussion of all points you 
wish to make. The EPA will generally not consider comments or comment 
contents located outside of the primary submission (i.e., on the web, 
cloud, or other file sharing system). For additional submission 
methods, the full EPA public comment policy, information about CBI or 
multimedia submissions, and general guidance on making effective 
comments, please visit http://www2.epa.gov/dockets/commenting-epa-dockets.
    Instructions. Direct your comments on the OCC MPGF or the framework 
for streamlining future MPGF AMEL requests to Docket ID Number EPA-HQ-
OAR-2014-0738. The EPA's policy is that all comments received will be 
included in the public docket without change and may be made available 
online at http://www.regulations.gov, including any personal 
information provided, unless the comment includes information claimed 
to be confidential business information (CBI) or other information 
whose disclosure is restricted by statute. Do not submit information 
that you consider to be CBI or otherwise protected through http://www.regulations.gov or email. Send or deliver information identified as 
CBI only to the following address: OAQPS Document Control Officer 
(C404-02),

[[Page 52427]]

Office of Air Quality Planning and Standards, U.S. Environmental 
Protection Agency, Research Triangle Park, North Carolina 27711, 
Attention: Docket ID Number EPA-HQ-OAR-2014-0738. Clearly mark the part 
or all of the information that you claim to be CBI. For CBI information 
on a disk or CD-ROM that you mail to the EPA, mark the outside of the 
disk or CD-ROM as CBI and then identify electronically within the disk 
or CD-ROM the specific information that is claimed as CBI. In addition 
to one complete version of the comment that includes information 
claimed as CBI, a copy of the comment that does not contain the 
information claimed as CBI must be submitted for inclusion in the 
public docket. Information so marked will not be disclosed except in 
accordance with procedures set forth in 40 CFR part 2. The http://www.regulations.gov Web site is an ``anonymous access'' system, which 
means the EPA will not know your identity or contact information unless 
you provide it in the body of your comment. If you send an email 
comment directly to the EPA without going through http://www.regulations.gov, your email address will be automatically captured 
and included as part of the comment that is placed in the public docket 
and made available on the Internet. If you submit an electronic 
comment, the EPA recommends that you include your name and other 
contact information in the body of your comment and with any disk or 
CD-ROM you submit. If the EPA cannot read your comment due to technical 
difficulties and cannot contact you for clarification, the EPA may not 
be able to consider your comment. Electronic files should not include 
special characters or any form of encryption and be free of any defects 
or viruses. For additional information about the EPA's public docket, 
visit the EPA Docket Center homepage at: http://www.epa.gov/dockets.
    Docket. The EPA has established a docket for this action under 
Docket ID Number EPA-HQ-OAR-2014-0738. All documents in the docket are 
listed in the regulations.gov index. Although listed in the index, some 
information is not publicly available, e.g., CBI or other information 
whose disclosure is restricted by statute. Certain other material, such 
as copyrighted material, is not placed on the Internet and will be 
publicly available only in hard copy. Publicly available docket 
materials are available either electronically in regulations.gov or in 
hard copy at the EPA Docket Center (EPA/DC), EPA WJC West Building, 
Room 3334, 1301 Constitution Ave. NW., Washington, DC. The Public 
Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through 
Friday, excluding legal holidays. The telephone number for the Public 
Reading Room is (202) 566-1744, and the telephone number for the EPA 
Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: For questions about this action, 
contact Mr. Andrew Bouchard, Sector Policies and Programs Division 
(E143-01), Office of Air Quality Planning and Standards (OAQPS), U.S. 
Environmental Protection Agency, Research Triangle Park, North Carolina 
27711; telephone number: (919) 541-4036; fax number: (919) 541-0246; 
and email address: bouchard.andrew@epa.gov.

SUPPLEMENTARY INFORMATION: 

Acronyms and Abbreviations

    We use multiple acronyms and terms in this notice. While this list 
may not be exhaustive, to ease the reading of this notice and for 
reference purposes, the EPA defines the following terms and acronyms 
here:

AMEL alternative means of emission limitation
Btu/scf British thermal units per standard cubic feet
CAA Clean Air Act
CFR Code of Federal Regulations
CPMS continuous parameter monitoring system
EPA Environmental Protection Agency
ESL effects screening level
FR Federal Register
HAP hazardous air pollutants
LEL lower explosive limit
LFL lower flammability limit
LFLcz combustion zone lower flammability limit
MPGF multi-point ground flare
NESHAP national emission standards for hazardous air pollutants
NHV net heating value
NHVcz combustion zone net heating value
NSPS new source performance standards
OAQPS Office of Air Quality Planning and Standards
OCC Occidental Chemical Corporation
OSHA Occupational Safety and Health Administration
PDH propane dehydrogenation unit
PFTIR passive Fourier transform infrared spectroscopy
psig pounds per square inch gauge
QA quality assurance
QC quality control
TAC Texas Administrative Code
TCEQ Texas Commission on Environmental Quality
VOC volatile organic compounds

Organization of This Document. The information in this notice is 
organized as follows:

I. Background
    A. Summary
    B. Flare Operating Requirements
    C. Alternative Means of Emission Limitation
II. Summary of Significant Public Comments on the AMEL Requests for 
Pressure-Assisted MPGF
    A. Regulatory Compliance Language and Calculation Methodology
    B. NHVcz and LFLcz Operating Limits and 
Averaging Time
    C. Monitoring Systems
    D. AMEL Mechanism and Process
    E. Other
III. Final Notice of Approval of the AMEL Requests and Required 
Operating Conditions
IV. Notice of AMEL Request for Occidental Chemical Corporation
V. Notice of Framework for Streamlining Approval of Future Pressure-
Assisted MPGF AMEL Requests

I. Background

A. Summary

    On February 13, 2015, the EPA published an initial notice in the 
Federal Register (FR) acknowledging receipt of AMEL approval requests 
for the operation of several MPGF at The Dow Chemical Company's Dow 
Propane Dehydrogenation Plant and Light Hydrocarbons Plant located at 
its Texas Operations site located in Freeport, Texas, and ExxonMobil's 
Olefins Plant in Baytown, Texas, and its Plastics Plant in Mont 
Belvieu, Texas (see 80 FR 8023, February 13, 2015). This initial notice 
also solicited comment on all aspects of the AMEL requests and the 
resulting alternative operating conditions that are necessary to 
achieve a reduction in emissions of volatile organic compounds (VOC) 
and organic hazardous air pollutants (HAP) at least equivalent to the 
reduction in emissions required by various standards in 40 CFR parts 
60, 61 and 63 that apply to emission sources that would be controlled 
by these pressure-assisted MPGF. These standards point to the operating 
requirements for flares in the General Provisions to parts 60 and 63, 
respectively, to comply with the emission reduction requirements. 
Because pressure-assisted MPGF cannot meet the velocity requirements in 
the General Provisions, Dow and ExxonMobil requested an AMEL. This 
action provides a summary of comments received as part of the public 
review process, our responses to those comments, and our approval of 
the requests received from Dow and ExxonMobil for an AMEL for the MPGF 
at the specific plants listed above, along with the operating 
conditions they must follow for demonstrating compliance with the AMEL.
    This action also solicits comments on all aspects of an AMEL 
request from OCC in which MPGF burner stability

[[Page 52428]]

and destruction efficiency have been demonstrated on different 
pressure-assisted MPGF burners that OCC has proposed for use in 
controlling emissions at its Ingleside, Texas, ethylene plant.
    Lastly, because we are aware that facilities plan to build or are 
considering use of MPGF as an emissions control technology, this action 
presents and solicits comments on all aspects of a framework for 
streamlining future MPGF AMEL requests that we anticipate, when 
followed, would afford the agency the ability to review and approve 
future AMEL requests for MPGF in a more efficient and expeditious 
manner. We note here though that all aspects of future AMEL requests 
would still be subject to a notice and comment proceeding.

B. Flare Operating Requirements

    In their requests, Dow and ExxonMobil cited various regulatory 
requirements in 40 CFR parts 60, 61 and 63 that will apply to the 
different flare vent gas streams that will be collected and routed to 
their pressure-assisted MPGF at each plant. These requirements were 
tabulated in the initial notice for this action (80 FR 8023, February 
13, 2015). The applicable rules require that control devices achieve 
destruction efficiencies of either 95 percent or 98 percent either 
directly, or by reference, or allow control by flares meeting the flare 
operating requirements in 40 CFR 60.18 or 40 CFR 63.11. The flare 
operating requirements in 40 CFR 60.18 and 40 CFR 63.11 specify that 
flares shall be: (1) Steam-assisted, air-assisted or non-assisted; \1\ 
(2) operated at all times when emissions may be vented to them; (3) 
designed for and operated with no visible emissions (except for periods 
not to exceed a total of 5 minutes during any 2 consecutive hours); and 
(4) operated with the presence of a pilot flame at all times. The flare 
operating requirements in 40 CFR 60.18 and 40 CFR 63.11 also specify 
requirements for both the minimum heat content of gas combusted in the 
flare and the maximum exit velocity at the flare tip.\2\ These 
provisions specify maximum flare tip velocities based on flare type 
(non-assisted, steam-assisted or air-assisted) and the net heating 
value of the flare vent gas (see 40 CFR 60.18(c)(3) and 40 CFR 
63.11(b)(6)). These maximum flare tip velocities are required to ensure 
that the flame does not ``lift off'' or separate from the flare tip, 
which could cause flame instability and/or potentially result in a 
portion of the flare gas being released without proper combustion. 
Proper combustion for flares is considered to be 98 percent destruction 
efficiency or greater for organic HAP and VOC, as discussed in our 
recent proposal titled ``Petroleum Refinery Sector Risk and Technology 
Review and New Source Performance Standards,'' 79 FR 36880, 36904-36912 
(June 30, 2014).
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    \1\ While Dow and ExxonMobil describe their flares as 
``pressure-assisted,'' these flares qualify as ``non-assisted'' 
flares under 40 CFR 60.18(b) or 63.11(b) because they do not employ 
assist gas.
    \2\ These requirements are not all inclusive. There are other 
requirements in 40 CFR 60.18 and 63.11 relating to monitoring and 
testing that are not described here.
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    The MPGF proposed by both Dow and ExxonMobil are different in both 
flare head design and operation than the more traditional steam-
assisted, air-assisted and non-assisted flare types currently able to 
comply with the flare operating requirements in 40 CFR 60.18 or 63.11. 
The MPGF technology operates by using the pressure upstream of each 
individual flare tip burner to enhance mixing with air at the flare tip 
due to high exit velocity, which in turn allows the MPGF to operate in 
a smokeless capacity. The MPGF are constructed differently than normal 
elevated flares in that they consist of many rows of individual flare 
tips which are approximately eight feet above ground level. The ground 
flare staging system opens and closes staging valves according to gas 
pressure such that stages containing multiple burners are activated as 
the flow and pressure increase or decrease in the header. While 
information supplied by Dow, and relied on by both Dow and ExxonMobil, 
indicates that the flare tips operate in a smokeless capacity and 
achieve high destruction efficiencies, the MPGF cannot meet the exit 
velocity requirements in 40 CFR 60.18 and 40 CFR 63.11, which limit the 
exit velocity at the flare tip to a maximum of 400 feet per second. The 
exit velocities from MPGF typically range from 600 feet per second up 
to sonic velocity (which ranges from 700 to 1,400 feet per second for 
common hydrocarbon gases), or Mach = 1 conditions. As a result, Dow and 
ExxonMobil are seeking an alternative means of complying with the flare 
operating requirements in 40 CFR 60.18 and 63.11; specifically, the 
exit velocity requirements in 40 CFR 60.18(c)(3), (c)(4) and (c)(5) and 
in 40 CFR 63.11(b)(6), (b)(7) and (b)(8).

C. Alternative Means of Emission Limitation

    As noted above, the specific rules in 40 CFR parts 60, 61 and 63, 
or the General Provisions for parts 60, 61 and 63 of the Clean Air Act 
(CAA) \3\ allow a facility to request an AMEL. These provisions allow 
the Administrator to permit the use of an alternative means of 
complying with an applicable standard, if the requestor demonstrates 
that the alternative achieves at least an equivalent reduction in 
emissions. The EPA provided notice of the requests and an opportunity 
for both a public hearing and opportunity for comment on the requests 
in the FR (see 80 FR 8023, February 13, 2015). After considering the 
comments received during the public comment period, the EPA is 
approving the AMEL requests and the use of the MPGF at Dow's two plants 
at its Texas Operations site in Freeport, Texas, and at ExxonMobil's 
two plants in Mont Belvieu, Texas, and Baytown, Texas.
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    \3\ CAA section 111(h)(3) states: ``If after notice and 
opportunity for public hearing, any person establishes to the 
satisfaction of the Administrator that an alternative means of 
emission limitation will achieve a reduction in emissions of any air 
pollutant at least equivalent to the reduction in emissions of such 
air pollutant achieved under the requirements of paragraph (1), the 
Administrator shall permit the use of such alternative by the source 
for purposes of compliance with this section with respect to such 
pollutant.'' Section 112(h)(3) contains almost identical language.
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II. Summary of Significant Public Comments on the AMEL Requests for 
Pressure-Assisted MPGF

    This section contains a summary of the major comments and 
responses, and rationale for the approved MPGF operating conditions and 
monitoring, recordkeeping and reporting requirements necessary to 
ensure the MPGF will achieve a reduction in emissions of HAP and VOC at 
least equivalent to the reduction in emissions of other traditional 
flare systems complying with the requirements in 40 CFR 60.18(b) and 40 
CFR 63.11(b).

A. Regulatory Compliance Language and Calculation Methodology

    Comment: Several commenters suggested that the EPA clarify the 
relationship between the AMEL and the requirements at 40 CFR 63.11 and 
40 CFR 60.18. Specifically, the commenters suggested that the EPA add 
the following or similar language: ``Compliance with applicable 
portions of 40 CFR 60.18 and 40 CFR 63.11, together with the AMEL, 
satisfy the new source performance standards (NSPS) and/or national 
emission standards for hazardous air pollutants (NESHAP) requirements 
that refer to 40 CFR 60.18 and 40 CFR 63.11.'' The commenters further 
state that adoption of this language would allow deletion of 
requirements #2 and #3 related to pilot

[[Page 52429]]

flames, visible flames, and visible emissions standards in the initial 
AMEL notice.
    Response: First, we clarify here for both of Dow's plants and both 
of ExxonMobil's plants that will use MPGF as a control device that 
compliance with the requirements in Section III of this AMEL notice 
satisfies the flare NSPS and NESHAP requirements referenced in 40 CFR 
60.18 and 40 CFR 63.11. However, we disagree with commenters that 
deletion of the language related to pilot flames and visible flames is 
appropriate given the unique design of MPGF installations and their 
various rows of hundreds of burners. The language currently in 40 CFR 
60.18 and 40 CFR 63.11 was intended to ensure that more traditional, 
individual flare tips had a flame present at all times by requiring 
that a pilot flame is always present. While having at least a single 
pilot flame is appropriate for a single flare tip, it in no way assures 
that each of the hundreds of flare tips that are arranged in multiple 
stages in a MPGF installation will ignite and have a flare flame when 
vent gas is sent to the system. Thus, we are not requiring Dow and 
ExxonMobil to comply with these requirements precisely as outlined 
currently in the General Provisions and are instead finalizing, based 
on information provided by these companies with respect to staging 
design and number of pilots per stage, a requirement in the AMEL that 
each stage of burners in the MPGF installation have at least two pilots 
with a continuously lit pilot flame. This requirement will provide the 
agency with a high level of assurance that a flare flame is present at 
all times when the other applicable requirements are also being met.
    Commenters also suggested that the language in the initial AMEL 
notice related to pilot flame presence at Section III, #2 (see 80 FR 
8030, February 13, 2015) had slightly different wording elements 
compared to the flare General Provisions requirements. We agree with 
the commenters that some of the language is different, but note that 
requiring at least two pilot flames on each stage of burners to be 
continuously lit and monitored as opposed to only a single pilot flame 
as prescribed in the General Provisions is a necessary change. However, 
we have incorporated language in this final action to be more 
consistent with the requirements in the General Provisions to allow 
pilot flames to be monitored by thermocouples ``or any other equivalent 
device used to detect the presence of a flame.''
    Lastly, we agree with the commenters that the language in the 
initial AMEL notice related to visible emissions at Section III, #3 is 
somewhat redundant with the requirements in the General Provisions, but 
given that we are requiring facilities to use a video camera to conduct 
visible emissions observations we must address the visible emissions 
requirements specifically.
    Comment: Several commenters recommended that the EPA include in the 
final AMEL notice the equations and references to physical data needed 
to calculate NHVcz and LFLcz.
    Response: We agree with the commenters and are incorporating these 
changes in this final action.

B. NHVcz and LFLcz Operating Limits and Averaging Time

    Comment: Several commenters suggested that the EPA should not set a 
precedent for potential future flare standards with respect to a 15-
minute averaging period for the combustion parameters (i.e., NHVcz and 
LFLcz) or on-line monitoring technology. Commenters also suggested that 
the operating requirements of NHVcz of 800 British thermal units per 
standard cubic foot (Btu/scf) or greater or LFLcz of 6.5 percent by 
volume or less are based on the single worst-case data point, that this 
is not consistent with the Marathon Petroleum test report data, and 
that establishing a limit based on the single worst test run could set 
bad precedent for future potential flare and/or AMEL standards.
    Response: First, we note that flares by their very nature are 
designed to handle and combust highly variable waste gas flows and 
compositions. Given that both Dow and ExxonMobil have requested use of 
MPGF for applications in controlling emissions related to periods of 
upset, maintenance, startup and shutdown, the question for the Agency 
becomes how do these facilities demonstrate to the satisfaction of the 
Administrator that this AMEL will achieve a reduction in emissions of 
VOC and HAP at least equivalent to the reduction in emissions required 
by the various standards in 40 CFR parts 60, 61 and 63 for highly 
variable flow and vent gas composition control scenarios.
    An assessment of the data we used to evaluate these AMEL requests 
suggests that at least an equivalent reduction in emissions control for 
MPGF has been demonstrated and can be maintained provided there is a 
stable, lit flame. In reviewing the supporting data, long-term 
stability was demonstrated by 20-minute test runs with fairly 
consistent flow and composition; however, there were also five test 
runs which showed instability in as little as 1 to 2 minutes. 
Considering that Dow and ExxonMobil will be producing and using olefins 
in their process, the Dow test is more appropriate and representative 
of the types of waste gas compositions and flows their MPGF will expect 
to handle compared to the natural gas and nitrogen mixtures burned in 
the Marathon test. Thus, the operating requirements of an NHVcz of 800 
Btu/scf or greater or LFLcz of 6.5 percent by volume or less which come 
from the Dow test, while conservative, provides reasonable assurance 
that these particular sources will maintain a stable flame for 
consistent flows and waste gas compositions expected to be burned by 
these particular sources as opposed to a refiner like Marathon whose 
waste gas originates from a different source category.
    Finally, the available data we are using to assess what the 
appropriate averaging time should be for these unique MPGF 
installations indicate that there could exist a gap between the MPGF 
system response (e.g., the sampling of the waste gas stream and the 
introduction of supplemental fuel to counteract a low heat content 
waste gas stream) and flame stability for situations of highly variable 
flow and/or highly variable waste gas composition. In light of this, we 
considered reasonable options that provide assurance that these MPGF 
installations will control emissions at a high level of efficiency with 
a stable, lit flame during these particular events. In evaluating these 
options, we concluded that a short averaging time is necessary to 
ensure that the MPGF installations will work as intended. Given the 
fact that we are allowing use of on-line gas chromatographs to perform 
compositional analysis to determine compliance with the NHVcz and LFLcz 
operating parameters, we cannot require shorter averaging times than 
the monitoring technology will allow, which is 15 minutes, and which we 
are finalizing in this action. In addition, we are also finalizing an 
alternative to allow the use of a calorimeter to monitor directly for 
NHVcz, which Dow or ExxonMobil may choose to use if they have similar 
concerns about variable flow/waste gas composition impacting flame 
stability, as these types of monitoring systems have significantly 
faster response times (e.g., 1 minute) than those of gas 
chromatographs. Lastly, we acknowledge the concerns presented with 
respect to setting precedent for potential future flare standards on 
averaging time and online monitoring technology. However, we note that 
this comment is beyond the

[[Page 52430]]

scope of this action and not relevant to the site-specific action of 
the AMEL requests for the use of MPGF at these specific Dow or 
ExxonMobil facilities.

C. Monitoring Systems

    Comment: A number of commenters suggested that pressure and flow 
monitors on each stage of the MPGF are unnecessary, as the MPGF are not 
designed with pressure and flow monitors on each individual stage, but, 
rather, rely on the monitoring system on the main flare header that is 
used by the process control system to open and close various stages of 
the flare system. Commenters instead suggested that flow and pressure 
should be monitored on the main flare header, as well as valve position 
indicators showing whether the valves are open or closed for each 
staging valve. Another commenter agreed that flare header pressure was 
important, but questioned why the initial AMEL notice did not require a 
minimum flare header pressure set at 15 pounds per square inch gauge 
(psig), since EPA stated that MPGF typically required 15 psig at the 
main flare header to properly operate. The commenter also suggested 
that the AMEL require monitoring of pressure at each stage and also set 
minimum flare header pressure requirements.
    Response: We agree that monitoring of flow and pressure on each 
individual stage is not needed as long as the flare header pressure and 
flow are adequately monitored. Given that the header pressure will be 
the maximum pressure at any point in the MPGF, the pressure of each 
stage will be at or lower than the main flare header pressure. As the 
commenters noted, the process control logic system opens and closes the 
staging valves based on the MPGF header pressure. Therefore, flare 
header pressure and information on which stages are open or closed will 
provide enough information to determine whether the MPGF is operating 
as designed. For example, if the pressure is low in the main flare 
header and below the minimum operating pressure of the burners in stage 
2, the valve position indicator for stage 2 as well any valve position 
indicators for stages after stage 2 should show that those stages are 
all closed. Both AMEL requests referenced the range of operating 
pressures of the burners/stages, and, therefore, this final AMEL 
requires that the MPGF burners be operated within the range of tested 
conditions or within the range of the manufacturer's specifications, as 
demonstrated using header pressure and valve position indicators. We 
note that, while we discussed a typical flare header operating pressure 
in the technical memorandum supporting the initial AMEL notice and 
discussions (see memorandum ``Review of Available Test Data on 
Multipoint Ground Flares'' at Docket ID Number EPA-HQ-OAR-2014-0738-
0002), we are providing the sites with a specific range of operating 
pressures to comply, as presented in their AMEL requests and supporting 
test data.
    Comment: One commenter suggested that the EPA should require each 
facility to install real-time fenceline monitoring to protect and 
inform communities if there is an increase in HAP crossing the 
fenceline during flaring events. The commenter stated that the proposed 
AMEL would allow operators to shift emissions from elevated flares to 
ground level, thus increasing ground-level pollution because emissions 
released at ground level, as compared to an elevated stack, do not 
disperse as far and remain in higher concentrations around the emitting 
source. The commenter stated that, as a result, the AMEL would increase 
exposure and risk and likely disproportionately impact minority and low 
income populations. Another commenter stated that based on dispersion 
modeling calculations conducted for the propane dehydrogenation unit 
(PDH) plant flare system, they project that the off-site concentrations 
of any air contaminant will be <1 percent of the TCEQ's effects 
screening level (ESL) for both the short-term one hour average 
concentrations and the annual averages.\4\ The commenter stated that 
these projected off-site impacts are similar to what is expected from 
an elevated flare. Given the low off-site concentrations predicted, it 
is the commenter's opinion that additional ambient air monitoring is 
not warranted for this AMEL request. Other commenters suggested that 
flow and composition monitoring, in concert with monitoring for flame 
presence, would provide substantially more valuable information for 
evaluating the downwind effect of a flameout as compared to ambient 
monitoring. Another commenter suggested lower explosive limit (LEL) 
monitors around a ground flare could provide an indication of a 
malfunction or slow, unburned leaks from staging valves that the direct 
waste gases and flare monitors might miss.
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    \4\ See ``Multi-Point Ground Level Flare Modeling Discussion'' 
at Docket ID Number EPA-HQ-OAR-2014-0738 for further information on 
modeling results.
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    Response: Comments on additional monitoring of the ambient 
concentrations of pollutants in the atmosphere surrounding the ground 
flare address a range of concerns. Some comments relate to the 
efficiency of the flare and the emission potential of the flare when 
the ground flare is working as expected, and other comments relate to 
when the ground flare experiences flameout or some other event where 
uncombusted materials have the potential to be emitted. We agree that 
the combination of pilot flame monitoring in concert with flow and 
composition monitoring (and pressure/staging valve monitoring) or use 
of LEL monitors in the immediate area of the ground flare are several 
methods the operator can use to identify an improperly-operating flare. 
However, if the suite of operating conditions being finalized in 
Section III below are met, we feel that the MPGF should operate 
properly and with a high level of destruction efficiency. Although we 
understand that the MPGF are equipped with safety interlocks and in 
some cases LEL monitors, we are not requiring they operate these 
systems under our final AMEL requirements for Dow and ExxonMobil. 
Rather, additional safety analyses should be addressed under the 
Occupational Safety and Health Administration's (OSHA) Process Safety 
Management \5\ and the EPA's Risk Management Program.\6\ Regarding 
comments pertaining to the need for some type of monitoring for 
communities that may be impacted by these MPGF installations, we are 
not mandating any type of fenceline or community monitoring in the AMEL 
approval because the approval is on the basis that the facilities have 
adequately demonstrated that the MPGF are capable of achieving or 
exceeding the emissions reductions mandated by the underlying NSPS and/
or NESHAP. However, through a separate effort, we are helping to 
facilitate discussions between the communities near these Dow and 
ExxonMobil facilities and the companies involved to explore possible 
monitoring that will address specific concerns of the communities (see 
``Community Open Forum Discussions'' at Docket ID Number EPA-HQ-OAR-
2014-0738).
---------------------------------------------------------------------------

    \5\ See https://www.osha.gov/SLTC/processsafetymanagement/ for 
more details.
    \6\ See http://www2.epa.gov/rmp for more details.
---------------------------------------------------------------------------

    Comment: A few commenters suggested that our provisions should 
allow for at least a 5 percent downtime limit for continuous monitoring 
data outside of maintenance periods, instrument adjustments and 
calibration checks, similar to the requirements in Texas VOC Sampling 
Rule protocol found at 30 TAC 115.725(d)(3).

[[Page 52431]]

    Response: First, we note that the Texas VOC sampling protocol only 
excludes time for ``normal calibration checks'' and does not exclude 
time for ``maintenance periods'' or ``instrument adjustments.'' Our 
initial AMEL notice required operation of the continuous parameter 
monitoring system (CPMS) at all times except during ``maintenance 
periods, instrument adjustments or checks to maintain precision and 
accuracy, calibration checks, and zero and span adjustments.'' Except 
for the time periods we excluded, we consider that the monitor should 
be continuously operated. However, we agree with the commenters that it 
is reasonable to set an upper limit on the time period for maintenance 
periods and instrument adjustments, so we are adding an additional 
sentence to the AMEL provisions as follows: ``Additionally, maintenance 
periods, instrument adjustments or checks to maintain precision and 
accuracy, and zero and span adjustments may not exceed 5 percent of the 
time the flare is receiving regulated material.''
    Comment: One commenter noted that, because operating personnel 
cannot enter the fenced area while the MPGF is operating, visual 
observation in accordance with the monitoring requirements of the 
General Provisions is impractical and cannot assure compliance. The 
commenter also stated that visible emissions from ground flares are a 
known problem and that community members in Port Arthur have submitted 
several complaints about smoke releases from the ground flare at the 
BASF Olefins Plant. Therefore, the commenter stated that it is 
imperative for the EPA to assure that the AMEL requires video 
monitoring that is adequate to assure compliance. Also, the EPA must 
require each facility to submit the video monitoring data to the 
appropriate authorities as part of any periodic compliance reports 
required by the CAA.
    Response: We agree that the MPGF systems should be operated with no 
visible emissions and we included a requirement in the initial AMEL 
notice to use video surveillance cameras to demonstrate compliance with 
this requirement. We did not, however, in the initial AMEL notice 
indicate how else the operators would demonstrate compliance with the 
visible emissions limit. We agree that because operating personnel 
cannot enter the fenced area while the MPGF is operating, it is 
difficult to understand how any daily EPA Method 22 visible emissions 
monitoring for only 5 minutes during the day when operators could enter 
(when the flare was not operating) would be an effective method of 
ensuring compliance with this requirement. Therefore, we are requiring 
that the MPGF operators employ the use of a surveillance camera for 
visible emissions monitoring and record and maintain footage of this 
video for all periods when the MPGF is ``operating,'' meaning burning 
gas other than pilots. While we are only requiring the video 
surveillance footage to be maintained as a record, we are requiring 
that Dow and ExxonMobil report in their periodic compliance reports any 
deviations of the visible emissions standard.

D. AMEL Mechanism and Process

    Comment: One commenter suggested that a successful demonstration of 
equivalent emissions control was provided for the proposed MPGF burners 
to be used at both ExxonMobil's Mont Belvieu Plastics Plant and Baytown 
Olefins Plant. In support of this suggestion, the commenter suggests 
that the two test reports submitted during the comment period, combined 
with the ExxonMobil AMEL application, provide the technical support and 
justification to demonstrate such equivalency for both of ExxonMobil's 
plants.
    Response: We agree with the commenter that the information 
submitted by ExxonMobil successfully demonstrates an equivalent level 
of emissions control for the MPGF burners that will be used at 
ExxonMobil's Mont Belvieu Plastics Plant and Baytown Olefins Plant, 
provided that the requirements specified in Section III below are met. 
Therefore, we are approving ExxonMobil's AMEL request to use a MPGF at 
both of its plants.
    Comment: Several commenters generally supported the AMEL process as 
an appropriate mechanism to authorize use of MPGF as an equivalent 
emissions control technology and also provided recommendations for 
using the AMEL process for future projects or updates. These 
recommendations included providing flexibility to facilities to 
accommodate burner equivalency, providing facilities with a simple 
mechanism that allows information or alternate combustion parameters to 
be updated without requiring re-approval where additional data are 
provided and providing facilities who elect to apply for an AMEL a 
process for providing the EPA with information that demonstrates a MPGF 
burner is stable over the expected design range in lieu of requiring 
additional emissions (i.e., combustion/destruction efficiency) testing.
    Response: In light of the comments received on providing 
flexibility for use of other, future MPGF burner designs and emissions 
testing, we are providing in this notice a framework for sources to 
consider and use to streamline potential future approvals of AMEL 
requests for MPGF installations. We note that facilities requesting any 
such alternative limit will still have to go through a public notice 
and comment review process.
    Comment: A few commenters provided additional test information for 
pressure-assisted flares for the EPA to consider as having equivalent 
performance to the other burner types addressed in the AMEL. 
Additionally, these commenters also suggested that flare manufacturers, 
instead of owners or operators of a particular source, be allowed to 
test and pre-certify a particular pressure-assisted flare type.
    Response: First, while we appreciate the additional pressure-
assisted flare test data submitted by commenters, there is significant 
detail lacking in the submittals to fully evaluate the equivalency of 
these particular flares at this time, and, given that some of the data 
submitted are for a flare tip not being proposed for use by Dow or 
ExxonMobil, we find that information to be outside the scope of the 
AMEL. With respect to allowing flare manufacturers, instead of owners 
or operators of sources that would possibly use a MPGF to control 
emissions, to test and pre-certify a particular type of pressure-
assisted flare, the CAA sections 111(h)(3) and 112(h)(3) limit AMEL 
requests to ``the owner or operator of any source.'' Thus, we cannot 
allow this particular request. We are, however, as part of this action 
seeking comment on a proposed framework for streamlining approval of 
future AMEL requests for MPGF installations which flare manufacturers, 
working in concert with the owner or operator of a source who wishes to 
use a pressure-assisted MPGF type installation, will be able to follow 
and provide to the agency the necessary input, testing and performance 
demonstration information.

E. Other

    Comment: One commenter stated that the AMEL request is based on 
inadequate data to assure 98 percent destruction efficiency and stated 
that the EPA must require facilities that seek permission to comply 
with the AMEL in lieu of the General Provisions to perform long-term 
passive Fourier transform infrared spectroscopy (PFTIR) testing to 
determine the operating limits necessary to assure an equivalent level 
of control. The commenter further indicated that studies have 
consistently shown that the mixture and specific

[[Page 52432]]

chemical composition of the gas discharged to a flare impact combustion 
efficiency and that the EPA did not verify or investigate whether the 
facilities seeking approval to operate under an AMEL will discharge gas 
to the proposed MPGF that is similar in chemical composition to the gas 
used in the tests used to develop the AMEL. Further, commenters' review 
of available data suggests that the facilities seeking approval to 
operate under an AMEL will discharge gas that exhibit hydrogen-olefin 
interactions.
    Response: As we stated in the initial AMEL notice, one general 
conclusion made from the EPA's 1985 study is that stable flare flames 
and high (>98-99 percent) combustion and destruction efficiencies are 
attained when flares are operated within operating envelopes specific 
to each flare burner and gas mixture tested, and that operation beyond 
the edge of the operating envelope can result in rapid flame de-
stabilization and a decrease in combustion and destruction 
efficiencies. The data where flameout of the burners occurred from test 
runs in both the Marathon 2012 test report and the Dow 2013 test report 
showed that the flare operating envelope was different for the 
different gas mixtures tested. Additionally, the data indicate that 
combustion degradation beyond the edge of the operating envelope for 
pressure-assisted MPGF burners is so rapid that when a flame is 
present, the flare will still achieve a high level of combustion 
efficiency right up until the point of flameout. The results of the 
available PFTIR testing demonstrated that when a flame was present on 
the pressure-assisted flare burners tested, an average combustion 
efficiency of 99 percent or greater was achieved. Since the initial 
AMEL notice, we received additional combustion efficiency test data 
that further confirms this observation (see OCC comments in Docket ID 
Number EPA-HQ-OAR-204-0738-0030). In other words, the critical 
parameter in ensuring that the MPGF will achieve equivalent efficiency 
is dependent on a stable MPGF burner flame rather than the actual 
combustion efficiency, which to date has always been 98 percent or 
better over the gas composition mixtures tested. Therefore, we do not 
find that there is a need to operate a continuous PFTIR to demonstrate 
continuous combustion efficiency for MPGF. Instead, we rely on the 
continuous measurement of net heating value or lower flammability limit 
operating limits to ensure that the MPGF are operating well above the 
points of flame instability for the gas compositions evaluated. 
Further, based on our understanding of the PFTIR testing method, it is 
technically impracticable to operate a continuous PFTIR due to 
interferences that would be present for a continuous system on the 
multipoint array of burners in the MPGF (e.g., availability of multiple 
sight lines and changing ambient conditions such as rain or fog). 
However, in the event that technology advancements make the continuous 
demonstration of combustion efficiency feasible, we acknowledge that 
this may provide another means by which operators can demonstrate 
equivalence with existing standards. Finally, while it is true that, in 
the development of operating limits for refinery flares, we noted in 
the refinery proposal that a higher NHV cz target was 
appropriate for some mixtures of olefins and hydrogen, the combustion 
zone operating limits we are finalizing in today's notice are 
significantly more stringent than combustion zone parameters developed 
for traditional elevated refinery flares, including those with hydrogen 
and olefins, which should alleviate any such concerns with respect to 
combustion efficiency for these types of gas mixtures. In addition, and 
as discussed elsewhere in this section, an olefinic gas mixture (i.e., 
propylene mixture) was tested and used to determine the NHV 
cz and LFL cz operating limits for the olefins 
plants applying for an AMEL. This gas mixture is both representative 
and challenging to the system with respect to the vent gas mixtures the 
MPGF will burn. In fact, when considering the full array of flare vent 
gas mixtures tested (e.g., natural gas mixtures in the Marathon test, 
propylene mixtures in the Dow test and ethylene mixtures in the OCC 
test) and their corresponding points of flare flame instability on the 
MPGF burners, no single data point has shown instability above the NHV 
cz (or below the LFL cz) operating limits being 
finalized for Dow and ExxonMobil in Section III below.
    Comment: One commenter suggested that flare minimization is also 
another important tool to mitigate the impact that MPGF will have on 
communities and suggested that the EPA require implementation of a 
flare management plan that requires facilities to:
    (1) Identify the sources of the gas routed to a flare;
    (2) Assess whether the gas routed to a flare can be minimized;
    (3) Describe each flare covered by the flare management plan;
    (4) Quantify the baseline flow rate to the flare after minimization 
techniques are implemented;
    (5) Establish procedures to minimize or eliminate discharges to the 
flare during startup and shutdown operations; and
    (6) If the flare is equipped with flare gas recovery, establish 
procedures to minimize downtime of the equipment.
    Response: We consider the requirement to develop a flare management 
plan to be outside the scope of this AMEL. The purpose of this AMEL is 
to set site-specific conditions that an operator of a MPGF can use as 
an alternative to the existing requirements of 40 CFR 60.18 or 40 CFR 
63.11 for flares, which do not include requirements for flare 
management plans.

III. Final Notice of Approval of the AMEL Requests and Required 
Operating Conditions

    Based on information the EPA received from Dow and ExxonMobil and 
the comments received through the public comment period, operating 
requirements for the pressure-assisted MPGF at both of Dow's plants and 
both of ExxonMobil's plants that will achieve a reduction in emissions 
at least equivalent to the reduction in emissions being controlled by a 
steam-assisted, air-assisted or non-assisted flare complying with the 
requirements of either 40 CFR 63.11(b) or 40 CFR 60.18(b) are as 
follows:
    (1) The MPGF system must be designed and operated such that the 
combustion zone gas net heating value (NHVcz) is greater than or equal 
to 800 Btu/scf or the combustion zone gas lower flammability limit 
(LFLcz) is less than or equal to 6.5 percent by volume. Owners or 
operators must demonstrate compliance with the NHVcz or LFLcz metric by 
continuously complying with a 15-minute block average. Owners or 
operators must calculate and monitor for the NHVcz or LFLcz according 
to the following:
    (a) Calculation of NHVcz
    (i) The owner or operator shall determine NHVcz from compositional 
analysis data by using the following equation:

[[Page 52433]]

[GRAPHIC] [TIFF OMITTED] TP31AU15.002

Where:

NHVvg = Net heating value of flare vent gas, British thermal units 
per standard cubic foot (Btu/scf). Flare vent gas means all gas 
found just prior to the MPGF. This gas includes all flare waste gas 
(i.e., gas from facility operations that is directed to a flare for 
the purpose of disposing of the gas), flare sweep gas, flare purge 
gas and flare supplemental gas, but does not include pilot gas.
i = Individual component in flare vent gas.
n = Number of components in flare vent gas.
xi = Concentration of component i in flare vent gas, volume 
fraction.
NHVi = Net heating value of component i determined as the heat of 
combustion where the net enthalpy per mole of offgas is based on 
combustion at 25 degrees Celsius ([deg]C) and 1 atmosphere (or 
constant pressure) with water in the gaseous state from values 
published in the literature, and then the values converted to a 
volumetric basis using 20 [deg]C for ``standard temperature.'' Table 
1 summarizes component properties including net heating values.

    (ii) FOR MPGF, NHVvg = NHVcz.
    (b) Calculation of LFLcz
    (i) The owner or operator shall determine LFLcz from compositional 
analysis data by using the following equation:
[GRAPHIC] [TIFF OMITTED] TP31AU15.003

Where:

LFLvg = Lower flammability limit of flare vent gas, volume fraction.
n = Number of components in the vent gas.
i = Individual component in the vent gas.
[chi]i = Concentration of component i in the vent gas, volume 
percent (vol %).
LFLi = Lower flammability limit of component i as determined using 
values published by the U.S. Bureau of Mines (Zabetakis, 1965), vol 
%. All inerts, including nitrogen, are assumed to have an infinite 
LFL (e.g., LFLN2 = [infin], so that [chi]N2/LFLN2 = 0). LFL values 
for common flare vent gas components are provided in Table 1.

    (ii) FOR MPGF, LFLvg = LFLcz.
    (c) The operator of a MPGF system shall install, operate, calibrate 
and maintain a monitoring system capable of continuously measuring 
flare vent gas flow rate.
    (d) The operator shall install, operate, calibrate and maintain a 
monitoring system capable of continuously measuring (i.e., at least 
once every 15-minutes), calculating, and recording the individual 
component concentrations present in the flare vent gas or the owner or 
operator shall install, operate, calibrate and maintain a monitoring 
system capable of continuously measuring, calculating and recording 
NHVvg.
    (e) For each measurement produced by the monitoring system, the 
operator shall determine the 15-minute block average as the arithmetic 
average of all measurements made by the monitoring system within the 
15-minute period.
    (f) The operator must follow the calibration and maintenance 
procedures according to Table 2. Maintenance periods, instrument 
adjustments or checks to maintain precision and accuracy and zero and 
span adjustments may not exceed 5 percent of the time the flare is 
receiving regulated material.

                                    Table 1--Individual Component Properties
----------------------------------------------------------------------------------------------------------------
                                                                             NHV i  (British
                                                         MW i  (pounds per  thermal units per
            Component                Molecular formula      pound-mole)       standard cubic   LFL i  (volume %)
                                                                                  foot)
----------------------------------------------------------------------------------------------------------------
Acetylene........................  C2H2................              26.04              1,404                2.5
Benzene..........................  C6H6................              78.11              3,591                1.3
1,2-Butadiene....................  C4H6................              54.09              2,794                2.0
1,3-Butadiene....................  C4H6................              54.09              2,690                2.0
iso-Butane.......................  C4H10...............              58.12              2,957                1.8
n-Butane.........................  C4H10...............              58.12              2,968                1.8
cis-Butene.......................  C4H8................              56.11              2,830                1.6
iso-Butene.......................  C4H8................              56.11              2,928                1.8
trans-Butene.....................  C4H8................              56.11              2,826                1.7
Carbon Dioxide...................  CO2.................              44.01                  0            [infin]
Carbon Monoxide..................  CO..................              28.01                316               12.5
Cyclopropane.....................  C3H6................              42.08              2,185                2.4
Ethane...........................  C2H6................              30.07              1,595                3.0
Ethylene.........................  C2H4................              28.05              1,477                2.7
Hydrogen.........................  H2..................               2.02                274                4.0
Hydrogen Sulfide.................  H2S.................              34.08                587                4.0
Methane..........................  CH4.................              16.04                896                5.0
Methyl-Acetylene.................  C3H4................              40.06              2,088                1.7
Nitrogen.........................  N2..................              28.01                  0            [infin]
Oxygen...........................  O2..................              32.00                  0            [infin]
Pentane+ (C5+)...................  C5H12...............              72.15              3,655                1.4
Propadiene.......................  C3H4................              40.06              2,066               2.16

[[Page 52434]]

 
Propane..........................  C3H8................              44.10              2,281                2.1
Propylene........................  C3H6................              42.08              2,150                2.4
Water............................  H2O.................              18.02                  0            [infin]
----------------------------------------------------------------------------------------------------------------

                                 Table 2--Accuracy and Calibration Requirements
----------------------------------------------------------------------------------------------------------------
                Parameter                    Accuracy requirements              Calibration requirements
----------------------------------------------------------------------------------------------------------------
Flare Vent Gas Flow Rate................  20 percent of    Performance evaluation biennially (every
                                           flow rate at velocities      two years) and following any period of
                                           ranging from 0.1 to 1 feet   more than 24 hours throughout which the
                                           per second.                  flow rate exceeded the maximum rated
                                          5 percent of      flow rate of the sensor, or the data
                                           flow rate at velocities      recorder was off scale. Checks of all
                                           greater than 1 foot per      mechanical connections for leakage
                                           second.                      monthly. Visual inspections and checks
                                                                        of system operation every 3 months,
                                                                        unless the system has a redundant flow
                                                                        sensor.
                                                                       Select a representative measurement
                                                                        location where swirling flow or abnormal
                                                                        velocity distributions due to upstream
                                                                        and downstream disturbances at the point
                                                                        of measurement are minimized.
Pressure................................  5 percent over   Review pressure sensor readings at least
                                           the normal range measured    once a week for straight-line
                                           or 0.12 kilopascals (0.5     (unchanging) pressure and perform
                                           inches of water column),     corrective action to ensure proper
                                           whichever is greater.        pressure sensor operation if blockage is
                                                                        indicated.
                                                                       Performance evaluation annually and
                                                                        following any period of more than 24
                                                                        hours throughout which the pressure
                                                                        exceeded the maximum rated pressure of
                                                                        the sensor, or the data recorder was off
                                                                        scale. Checks of all mechanical
                                                                        connections for leakage monthly. Visual
                                                                        inspection of all components for
                                                                        integrity, oxidation and galvanic
                                                                        corrosion every 3 months, unless the
                                                                        system has a redundant pressure sensor.
                                                                       Select a representative measurement
                                                                        location that minimizes or eliminates
                                                                        pulsating pressure, vibration, and
                                                                        internal and external corrosion.
Net Heating Value by Calorimeter........  2 percent of     Calibration requirements should follow
                                           span.                        manufacturer's recommendations at a
                                                                        minimum.
                                                                       Temperature control (heated and/or cooled
                                                                        as necessary) the sampling system to
                                                                        ensure proper year-round operation.
                                                                       Where feasible, select a sampling
                                                                        location at least two equivalent
                                                                        diameters downstream from and 0.5
                                                                        equivalent diameters upstream from the
                                                                        nearest disturbance. Select the sampling
                                                                        location at least two equivalent duct
                                                                        diameters from the nearest control
                                                                        device, point of pollutant generation,
                                                                        air in-leakages, or other point at which
                                                                        a change in the pollutant concentration
                                                                        or emission rate occurs.
Net Heating Value by Gas Chromatograph..  As specified in Performance  Follow the procedure in Performance
                                           Specification 9 of 40 CFR    Specification 9 of 40 CFR part 60,
                                           part 60, Appendix B.         Appendix B, except that a single daily
                                                                        mid-level calibration check can be used
                                                                        (rather than triplicate analysis), the
                                                                        multi-point calibration can be conducted
                                                                        quarterly (rather than monthly), and the
                                                                        sampling line temperature must be
                                                                        maintained at a minimum temperature of
                                                                        60 [deg]C (rather than 120 [deg]C).
----------------------------------------------------------------------------------------------------------------

    (2) The MPGF system shall be operated with a flame present at all 
times when in use. Each stage of MPGF burners must have at least two 
pilots with a continuously lit pilot flame. The pilot flame(s) must be 
continuously monitored by a thermocouple or any other equivalent device 
used to detect the presence of a flame. The time, date and duration of 
any complete loss of pilot flame on any stage of MPGF burners must be 
recorded. Each monitoring device must be maintained or replaced at a 
frequency in accordance with the manufacturer's specifications.
    (3) The MPGF system shall be operated with no visible emissions 
except for periods not to exceed a total of 5 minutes during any 2 
consecutive hours. A video camera that is capable of continuously 
recording (i.e., at least one frame every 15 seconds with time and date 
stamps) images of the flare flame and a reasonable distance above the 
flare flame at an angle suitable for visible emissions observations 
must be used to demonstrate compliance with this requirement. The owner 
or operator must provide real-time video surveillance camera output to 
the control room or other continuously manned location where the video 
camera images may be viewed at any time.
    (4) The operator of a MPGF system shall install and operate 
pressure monitor(s) on the main flare header, as well as a valve 
position indicator monitoring system for each staging valve to ensure 
that the MPGF operates within the range of tested conditions or within 
the range of the manufacturer's specifications. The pressure monitor 
shall meet the requirements in Table 2. Maintenance periods, instrument 
adjustments or checks to maintain precision and accuracy, and zero and 
span adjustments may not exceed 5 percent of the time the flare is 
receiving regulated material.
    (5) Recordkeeping Requirements
    (a) All data must be recorded and maintained for a minimum of three 
years or for as long as applicable rule subpart(s) specify flare 
records should be kept, whichever is more stringent.
    (6) Reporting Requirements
    (a) The information specified in (b) and (c) below should be 
reported in the timeline specified by the applicable rule subpart(s) 
for which the MPGF will control emissions.
    (b) Owners or operators should include the following information in 
their initial Notification of Compliance status report:

[[Page 52435]]

    (i) Specify flare design as a pressure-assisted MPGF.
    (ii) All visible emission readings, NHVcz and/or LFLcz 
determinations and flow rate measurements. For MPGF, exit velocity 
determinations do not need to be reported as the maximum permitted 
velocity requirements in the General Provisions at 40 CFR 60.18 and 40 
CFR 63.11 are not applicable.
    (iii) All periods during the compliance determination when a 
complete loss of pilot flame on any stage of MPGF burners occurs.
    (iv) All periods during the compliance determination when the 
pressure monitor(s) on the main flare header show the MPGF burners 
operating outside the range of tested conditions or outside the range 
of the manufacturer's specifications.
    (v) All periods during the compliance determination when the 
staging valve position indicator monitoring system indicates a stage of 
the MPGF should not be in operation and is or when a stage of the MPGF 
should be in operation and is not.
    (c) The owner or operator shall notify the Administrator of periods 
of excess emissions in their Periodic Reports. These periods of excess 
emissions shall include:
    (i) Records of each 15-minute block during which there was at least 
one minute when regulated material was routed to the MPGF and a 
complete loss of pilot flame on a stage of burners occurred.
    (ii) Records of visible emissions events that are time and date 
stamped and exceed more than 5 minutes in any 2 hour consecutive 
period.
    (iii) Records of each 15-minute block period for which an 
applicable combustion zone operating limit (i.e., NHVcz or LFLcz) is 
not met for the MPGF when regulated material is being combusted in the 
flare. Indicate the date and time for each period, the NHVcz and/or 
LFLcz operating parameter for the period and the type of monitoring 
system used to determine compliance with the operating parameters 
(e.g., gas chromatograph or calorimeter).
    (iv) Records of when the pressure monitor(s) on the main flare 
header show the MPGF burners are operating outside the range of tested 
conditions or outside the range of the manufacturer's specifications. 
Indicate the date and time for each period, the pressure measurement, 
the stage(s) and number of MPGF burners affected and the range of 
tested conditions or manufacturer's specifications.
    (v) Records of when the staging valve position indicator monitoring 
system indicates a stage of the MPGF should not be in operation and is 
or when a stage of the MPGF should be in operation and is not. Indicate 
the date and time for each period, whether the stage was supposed to be 
open but was closed or vice versa and the stage(s) and number of MPGF 
burners affected.

IV. Notice of AMEL Request for Occidental Chemical Corporation

    On December 16, 2014, OCC submitted an AMEL request indicating 
plans to construct an ethylene production unit that will be comprised 
of five ethane cracking furnaces and associated recovery equipment at 
its plant located in Ingleside, Texas. As part of this request, OCC 
described plans to control emissions from the ethylene production unit 
using two thermal oxidizers as both a primary and backup control device 
for periods of normal operation and low-pressure maintenance, startup, 
and shutdown events, and that it is seeking an AMEL for a MPGF 
installation for use during limited high-pressure maintenance, startup, 
and shutdown events as well emergency situations. As part of its AMEL 
request, as well as in its comments submitted to Docket ID Number EPA-
HQ-OAR-2014-0738-0030 on March 30, 2015, during the Dow and ExxonMobil 
initial AMEL notice comment period, OCC requested an AMEL for use of 
different MPGF burners at its plant located in Ingleside, Texas, than 
the burners Dow and ExxonMobil plan to use at their plants. 
Specifically, OCC provided both destruction efficiency/combustion 
efficiency testing and long-term MPGF flame stability testing for 
ethylene and ethylene-inert waste gas mixtures on its proposed MPGF 
burners. These test data show good performance below an NHVcz of 800 
Btu/scf or above an LFLcz of 6.5 volume percent, although OCC stated in 
the AMEL request that it plans to comply with the same compliance 
requirements laid out for Dow and ExxonMobil in Section III above. 
Therefore, we are seeking comment on whether these operating 
requirements would establish an AMEL for OCC that will achieve a 
reduction in emissions at least equivalent to the reduction in 
emissions for flares complying with the requirements in 40 CFR 63.11(b) 
or 40 CFR 60.18(b).

V. Notice of Framework for Streamlining Approval of Future Pressure-
Assisted MPGF AMEL Requests

    We are seeking comments on a framework sources may use to submit an 
AMEL request to the EPA to use MPGF as control devices to comply with 
NSPS and NESHAP under 40 CFR parts 60, 61, and 63. At a minimum, 
sources considering use of MPGF as an emissions control technology 
should provide the EPA with the following information in its AMEL 
request when demonstrating MPGF equivalency:
    (1) Project Scope and Background
    (a) Size and scope of plant, products produced, location of 
facility and the MPGF proximity, if less than 2 miles, to the local 
community and schools.
    (b) Details of overall emissions control scheme (e.g., low pressure 
control scenario and high pressure control scenario), MPGF capacity and 
operation (including number of rows (stages), number of burners and 
pilots per stage and staging curve), and MPGF control utilization 
(e.g., handles routine flows, only flows during periods of startup, 
shutdown, maintenance, emergencies).
    (c) Details of typical and/or anticipated flare waste gas 
compositions and profiles for which the MPGF will control.
    (d) MPGF burner design including type, geometry, and size.
    (e) Anticipated date of startup.
    (2) Regulatory Applicability
    (a) Detailed list or table of applicable regulatory subparts, 
applicable standards that allow use of flares, and authority that 
allows for use of an AMEL.
    (3) Destruction Efficiency/Combustion Efficiency Performance 
Demonstration
    (a) Sources must provide a performance demonstration to the agency 
that the MPGF pressure-assisted burner being proposed for use will 
achieve a level of control at least equivalent to the most stringent 
level of control required by the underlying standards (e.g., 98% 
destruction efficiency or better). Facilities can elect to do a 
performance test that includes a minimum of three test runs under the 
most challenging conditions (e.g., highest operating pressure and/or 
sonic velocity conditions) using PFTIR testing, extractive sampling or 
rely on an engineering assessment. Sources must test using fuel 
representative of the type of waste gas the MPGF will typically burn or 
substitute a waste gas such as an olefin gas or olefinic gas mixture 
that will challenge the MPGF to perform at a high level of control in a 
smokeless capacity.
    (i) If a performance test is done, a test report must be submitted 
to the agency which includes at a minimum: A description of the 
testing, a protocol describing the test methodology used, associated 
test method quality assurance/quality control (QA/QC) parameters, raw 
field and laboratory data sheets, summary data report sheets,

[[Page 52436]]

calibration standards, calibration curves, completed visible emissions 
observation forms, a calculation of the average destruction efficiency 
and combustion efficiency over the course of each test, the date, time 
and duration of the test, the waste gas composition and NHVcz and/or 
LFLcz the gas tested, the flowrate (at standard conditions) and 
velocity of the waste gas, the MPGF burner tip pressure, waste gas 
temperature, meteorological conditions (e.g., ambient temperature, and 
barometric pressure, wind speed and direction, relative humidity), and 
whether there were any observed flare flameouts.
    (ii) If an engineering assessment is done, sources must provide to 
the agency a demonstration that a proper level of destruction/
combustion efficiency was obtained, through prior performance testing 
or the like for a similar equivalent burner type design. To support an 
equivalent burner assessment of destruction/combustion efficiency, 
sources must discuss and provide information related to design 
principles of burner type, burner size, burner geometry, air-fuel 
mixing, and the combustion principles associated with this burner that 
will assure smokeless operation under a variety of operating 
conditions. Similarly, sources must also provide details outlining why 
all of these factors, in concert with the waste gas that was tested in 
the supporting reference materials, support the conclusion that the 
MPGF burners being proposed for use by the source will achieve at least 
an equivalent level of destruction efficiency as required by the 
underlying applicable regulations.
    (4) Long-Term MPGF Stability Testing
    (a) The operation of a MPGF with a stable, lit flame is of 
paramount importance to continuously ensuring good flare performance; 
therefore, any source wishing to demonstrate equivalency for purposes 
of using these types of installations must conduct a long-term 
stability performance test. Since flare tip design and waste gas 
composition have significant impact on the range of stable operation, 
sources should use a representative waste gas the MPGF will typically 
burn or a waste gas, such as an olefin or olefinic mixture, that will 
challenge the MPGF to perform at a high level with a stable flame as 
well as challenge its smokeless capacity.
    (b) Sources should first design and carry out a performance test to 
determine the point of flare flame instability and flameout for the 
MPGF burner and waste gas composition chosen to be tested. Successful, 
initial demonstration of stability is achieved when there is a stable, 
lit flame for a minimum of five minutes at consistent flow and waste 
gas composition. It is recommended, although not required, that sources 
determine the point of instability at sonic flow conditions or at the 
highest operating pressure anticipated. Any data which demonstrates 
instability and complete loss of flame prior to the five minute period 
must be reported along the initial stable flame demonstration. Along 
with destruction efficiency and combustion efficiency, the data 
elements laid out in 3(a)(i) should also be reported.
    (c) Using the results from (b) above as a starting point, sources 
must perform a minimum of three replicate tests at both the minimum and 
maximum operating conditions on at least one MPGF burner at or above 
the NHVcz or at or below the LFL cz determined in 4(b). If more than 
one burner is tested, the spacing between the burners must be 
representative of the projected installation. Each test must be a 
minimum of 15-minutes in duration with constant flow and composition 
for the three runs at minimum conditions, and the three runs at the 
maximum conditions. The data and data elements mentioned in 4(b) must 
also be reported.
    (5) MPGF Cross-light Testing
    (a) Sources must design and carryout a performance test to 
successfully demonstrate that cross-lighting of the MPGF burners will 
occur over the range of operating conditions (e.g., operating pressure 
and/or velocity (Mach) condition) for which the burners will be used. 
Sources may use the NHVcz and/or LFLcz established in 4 above and 
perform a minimum of three replicate runs at each of the operating 
conditions. Sources must cross-light a minimum of three burners and the 
spacing between the burners and location of the pilot flame must be 
representative of the projected installation. At a minimum, sources 
must report the following: A description of the testing, a protocol 
describing the test methodology used, associated test method QA/QC 
parameters, the waste gas composition and NHVcz and/or LFLcz of the gas 
tested, the velocity (or Mach speed ratio) of the waste gas tested, the 
MPGF burner tip pressure, the time, length, and duration of the test, 
records of whether a successful cross-light was observed over all of 
the burners and the length of time it took for the burners to cross-
light, records of maintaining a stable flame after a successful cross-
light and the duration for which this was observed, records of any 
smoking events during the cross-light, waste gas temperature, 
meteorological conditions (e.g., ambient temperature, and barometric 
pressure, wind speed and direction, relative humidity), and whether 
there were any observed flare flameouts.
    (6) Flaring Reduction Considerations
    (a) Sources must make a demonstration, considering MPGF 
utilization, on whether additional flare reduction measures, including 
flare gas recovery, should be utilized and implemented.
    (7) MPGF Monitoring and Operating Conditions
    (a) Based on the results of the criteria mentioned above in this 
section, sources must make recommendations to the agency on the type of 
monitoring and operating conditions necessary for the MPGF to 
demonstrate equivalent reductions in emissions as compared to flares 
complying with the requirements at 40 CFR 60.18 and 40 CFR 63.11, 
taking into consideration a control scheme designed to handle highly 
variable flows and waste gas compositions.
    We solicit comment on all aspects of this framework. We anticipate 
this framework would enable the agency to review and approve future 
AMEL requests for MPGF installations in a more expeditious timeframe 
because we anticipate that the information required by the framework 
would provide us with sufficient information to evaluate future AMEL 
requests. We note that all aspects of future AMEL requests would still 
be subject to a notice and comment proceeding.

    Dated: August 20, 2015.
Janet G. McCabe,
Acting Assistant Administrator.
[FR Doc. 2015-21420 Filed 8-28-15; 8:45 am]
 BILLING CODE 6560-50-P