[Federal Register Volume 88, Number 28 (Friday, February 10, 2023)]
[Notices]
[Pages 8844-8860]
[FR Doc No: 2023-02811]

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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OAR-2021-0299; FRL-8193-01-OAR]

Notice of Final for Approval of Alternative Means of Emission
Limitation

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice, final approval.

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SUMMARY: This action announces the EPA approval of the request by Flint
Hills Resources (FHR), under the Clean Air Act (CAA), for an
alternative means of emission limitation (AMEL) to utilize a leak
detection sensor network (LDSN) with a detection response framework
(DRF) at its Meta-Xylene and Mid-Crude process units located at FHR's
West Refinery in Corpus Christi, Texas. The EPA received 6 public
comments on the October 13, 2021, initial notice for this AMEL. This
approval document specifies the alternative leak detection and repair
(LDAR) requirements that this facility must follow to demonstrate
compliance with the approved AMEL. In addition, this notice finalizes a
framework that facilities can follow to help expedite and streamline
approval of future AMEL requests for similar systems.

DATES: The approval of the AMEL request from FHR to utilize a LDSN with
a DRF at its Meta-Xylene and Mid-Crude process units located at FHR's
West Refinery in Corpus Christi, Texas, as specified in this document,
is effective on February 10, 2023.

ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OAR-2021-0299. All documents in the docket are
listed on the https://www.regulations.gov/ website. Although listed,
some information is not publicly available, e.g., Confidential Business
Information 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
form. Publicly available docket materials are available electronically
through https://www.regulations.gov/.

FOR FURTHER INFORMATION CONTACT: For questions about this action,
contact Mr. Neil Feinberg, Sector Policies and Programs Division (E143-
01), Office of Air Quality Planning and Standards, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina 27711;
telephone number:<PHONE_NUMBER>; fax number:<PHONE_NUMBER>; and email
address: [email protected].

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

AMEL alternative means of emission limitation
AVO audio, visual, or olfactory
CAA Clean Air Act
CDX Central Data Exchange
CFR Code of Federal Regulations
CRADA Cooperative Research and Development Agreement
DRF detection response framework
DTU upper limit of the detection threshold band
EPA Environmental Protection Agency
EST eastern standard time
FHR Flint Hills Resources
FID flame ionization detector
FEMP Fugitive Emissions Management Plan
GPS Global Positioning System
HC hydrocarbon
HON National Emission Standards for Hazardous Air Pollutants for
Organic Hazardous Air Pollutants From the Synthetic Organic Chemical
Manufacturing Industry
LDAR leak detection and repair
LDSN leak detection sensor network
LDSN-DRF leak detection sensor network-detection response framework
NC Leaker non-compliant leaker
NSPS new source performance standards
OGI optical gas imaging
ppbe parts per billion equivalent
ppm parts per million
ppmv parts per million by volume
PSL potential source location
QA/QC quality assurance/quality control
QIP quality improvement program
VOC volatile organic compounds
ZIC zone of inadequate coverage

    Organization of this document. The information in this document is
organized as follows:

I. Background
II. Summary of Public Comments on FHR's AMEL Request and the
Framework for Streamlining Approval of Future LDSN-DRF AMEL Requests
III. Framework for Streamlining Approval of Future LDSN-DRF AMEL
Requests
IV. Final Notice of Approval for the Mid-Crude and Meta-Xylene
Process Units at the FHR West Refinery AMEL Request and Required
Operating Conditions

I. Background

    On April 21, 2020, FHR requested an AMEL under the CAA to use a
leak detection sensor network-detection response framework (LDSN-DRF)
at its West and East Refineries located in Corpus Christi, Texas in
lieu of the traditional LDAR program using Method 21 of appendix A-7 of
part 60 (EPA Method 21) required by a number of applicable regulations
in 40 CFR parts 60, 61, and 63. See Table 1 in section IV of this
notice for a complete list of applicable regulations for this AMEL.
    In the initial notice, the EPA solicited comment on all aspects of
the AMEL request and alternative LDAR requirements that would be
necessary to achieve a reduction in emissions of volatile organic
compounds (VOC) and hazardous air pollutants (HAPs) at least equivalent
to the reduction in emissions required by the applicable LDAR standards
listed in Table 1 in section IV of this notice. The initial notice also
presented and solicited comment on all aspects of a generic framework
for future LDSN-DRF AMEL requests, which would afford the EPA the
ability to evaluate those requests in a more efficient and streamlined
manner.
    FHR included in its AMEL application information to demonstrate
that the LDSN-DRF will achieve a reduction in emissions at least
equivalent to the reduction in emissions achieved by the requirements
in the applicable standards summarized in Table 1 of section IV of this
notice for the Meta-Xylene and Mid-Crude process units located at FHR's
West Refinery in Corpus Christi, Texas. For FHR's AMEL request,
including any supporting materials FHR submitted, see Docket ID No.
EPA-HQ-OAR-2021-0299.
    This action finalizes the EPA's approval of this AMEL request.
Section II summarizes the comments received on the request and our
responses thereto. Section III sets forth the final operating
conditions EPA has established for the LDSN-DRF as part of this AMEL
approval.

II. Summary of Public Comments on FHR's AMEL Request and the Framework
for Streamlining Approval of Future LDSN-DRF AMEL Requests

    This section contains a summary of all comments received on the
October 13, 2021, initial notice,\1\ and the EPA's responses to those
comments. This section also contains rationale for the alternative LDAR
requirements that are approved in this notice. The EPA received six
comments on the initial notice.\2\
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    \1\ 86 FR 56934 (October 13, 2021).
    \2\ See Document ID Nos. EPA-HQ-OAR-2021-0299-0032 (TRICORD
Consulting, LLC), EPA-HQ-OAR-2021-0299-0033 (Anonymous), EPA-HQ-OAR-
2021-0299-0034 (ATLAS), EPA-HQ-OAR-2021-0299-0035 (Molex), EPA-HQ-
OAR-2021-0299-0036 (FHR), EPA-HQ-OAR-2021-0299-0037 (Eastman
Chemical Company).

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A. Comments and Responses Related to General Framework for Future LDSN-
DRF AMEL Requests

    The EPA solicited comment on all aspects of the general framework
proposed for future AMEL requests using a LDSN-DRF. Two comments were
received specific to the proposed framework.\3\
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    \3\ See Document ID Nos. EPA-HQ-OAR-2021-0299-0035 and EPA-HQ-
OAR-2021-0299-0036.
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    Comment: In their comments, FHR and Molex, LLC requested that the
general framework provide flexibility to apply the same Molex LDSN
design and deployment processes to similar units without the need to
conduct an additional pilot test. Both commenters stated that the
science behind the technology is established, and ``substantial''
controlled gas release experiments, including the pilot test results
\4\ presented for this AMEL support their request for flexibility.
Specifically, FHR and Molex suggested addition of the phrase ``if
necessary to demonstrate equivalency'' to the language in paragraph
III.D.(3) regarding submission of the results of the pilot study
conducted for each unit in a LDSN-DRF AMEL application.
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    \4\ See ``Progress on LDAR Innovation, Report on Research Under
CRADA #914-16'', EPA Publication Number EPA/600/R-20/422, revision
0.8, located at Document ID No. EPA-HQ-OAR-2021-0299-0014.
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    Response: The EPA disagrees with the commenters' recommendation
that test studies are not necessary for each process unit for which an
AMEL application is submitted. At this time, it is still appropriate to
require test studies for LDSNs on additional process units in order to
gather more information on how the networks perform in different types
of process units. The EPA may reevaluate its position on the necessity
of test studies in the future if it has more data with which to do so.
The EPA is providing the framework as described in section III of this
notice, with no changes from the initial notice. We anticipate this
framework would enable the Agency to evaluate future AMEL requests for
LDSN-DRF installations in a more expeditious timeframe because we
anticipate that the information required by the framework would provide
sufficient information to evaluate future AMEL requests on a case-by-
case basis. We note that all aspects of future AMEL requests will still
be subject to the notice and comment process.

B. Comments and Responses Related to the Equivalency Demonstration

    Comment: One commenter \5\ raised concerns with two of the
assumptions made by FHR when performing simulation modeling to
demonstrate equivalency of the LDSN-DRF to the applicable EPA Method 21
LDAR requirements: (1) Leaks would be repaired within 7 days of
detection and (2) a leak would remain constant from the time it is
detected until it is repaired. This commenter referenced a statement in
the EPA's Best Practices Guide for LDAR \6\ that notes a common problem
related to the repair requirements is that sources fail to complete
repairs within the specified timeline in the regulation. The commenter
then states that it is, therefore, inappropriate to assume that a leak
would be repaired in half the amount of time required by the applicable
regulation, and instead suggests that FHR should perform new
simulations assuming 10 to 15 days for repairs. Further, the commenter
suggests that FHR should conduct more equivalency simulations that do
not assume a constant leak rate because FHR's discussion on PSL closure
acknowledges that a PSL cannot be closed if there is an increase in the
detection level. In the commenter's opinion, this assumes that FHR
knows that leak rates can change and not remain constant until
repaired.
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    \5\ See Document ID No. EPA-HQ-OAR-2021-0299-0033.
    \6\ EPA, Leak Detection and Repair: A Best Practices Guide,
located at https://www.epa.gov/sites/default/files/2014-02/documents-ldarguide.pdf.
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    Response: The AMEL requires leaks to be repaired within 15 days of
detection, with a first attempt within the first five days. During the
pilot study, there was a median repair time of 2 and 3 days for the
Mid-Crude and Meta-Xylene units, respectively. Based on this
information, the EPA finds no reason that the average repair time would
exceed 7 days. The commenter is correct that a leak can increase over
time, but they fail to note that it could also decrease. The EPA has
determined the assumption of a constant leak rate between detection and
repair is appropriate for this AMEL.
    Comment: One commenter noted that some leaks above the upper limit
of the detection threshold (DTU) were found by EPA Method 21 and not by
the LDSN and asked how realistic it was that the LDSN would detect
leaks in a complex process unit.
    Response: The EPA acknowledges that some leaks above the DTU were
found with EPA Method 21 during the pilot test studies. However, during
the pilot test studies, FHR continued to adapt and adjust the network.
Additionally, FHR is adding additional sensors to the network in areas
that previously had gaps in coverage. These changes should ensure the
LDSN performs adequately and identifies all leaks above the DTU. The
annual compliance demonstrations provide added assurance of network
performance by verifying there are no undetected leaks above the DTU.
The EPA also notes that the results of the pilot study presented in the
Cooperative Research and Development Agreement (CRADA) showed greater
emission reductions using the LDSN than with EPA Method 21.
    Comment: One commenter \7\ stated that the sensor network only
minimally outperformed EPA Method 21 by at most 2 percent. The
commenter further stated that the size and scope of the study and the
results suggest this technology still needs scrutiny and that the pilot
study was performed in controlled conditions with a team of motivated
researchers present.
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    \7\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
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    Response: The EPA has found the performance of the LDSN to be
equivalent or better than current work practice requirements for the
Mid-Crude and Meta-Xylene process units at FHR's West Refinery in
Corpus Christi, Texas. Thus, the EPA finds it appropriate to issue this
AMEL for those process units. Any future approval of this technology
would be evaluated based on the information provided in that specific
application.

C. Comments and Responses Related to the LDSN

    Comment: FHR and Molex commented that updating the sensor detection
floor continuously on a 15-minute basis would result in erroneous
sensor failure indications and requested the expansion of corrective
action options to include other appropriate solutions. They stated that
the sensor detection floor is based on raw sensor readings which are
collected every second and provided an example where a sensor would be
shown as failing when updating the sensor detection floor while
detecting a continuous leak. They stated that no sensor would pass the
detection floor update requirement once every 15 minutes, as currently
included in the proposal. Both commenters requested a requirement for
monthly review of the sensor detection floor, with corrections made if
the sensor did not pass review. They

claimed that a bump test is not a calibration, is not performed in a
``clean'' environment as calibrations are, and adjusting readings based
on bump tests would create additional uncertainty in sensor readings.
Additionally, FHR and Molex commented that adjusting the sensor
detection floor based on a bump test is inappropriate as the sensor
detection floor is a fixed number set by the manufacturer.
Additionally, one commenter asked for clarification on how the baseline
levels are continuously monitored, while another asked for
clarification on the detection level that indicated emissions. Finally,
one commenter asked how sensors would be calibrated and verified.
    Response: The EPA is updating the requirements for the sensor
detection floor. First, the EPA is revising the requirement for a
continuously updated sensor detection floor such that the data must be
reviewed each day to confirm each sensor detection floor remains below
the established threshold of 10 parts-per-billion by volume isobutylene
equivalent (ppbe) during at least one 10-minute period in the past 72-
hour period. Further, the EPA agrees with FHR and Molex that adjusting
the sensor detection floor based on a bump test is inappropriate due to
the variable bump test responses observed during the pilot study, which
are not related to the baseline noise of the instrument. An emissions
anomaly is defined as any detection by the sensor network greater than
the detection floor. Sensors must be calibrated by the manufacturer
prior to deployment. Once installed, each sensor must be tested for
responsivity and wireless communication by challenging it with
isobutylene gas or another appropriate standard. Sensors must pass a
quarterly bump test or be recalibrated or replaced.
    Comment: FHR and Molex stated in their comments that the collection
of wind speed and wind direction data is critical to the operation of
the LDSN. However, both commenters stated that the requirement to have
a wind sensor located in each individual process unit is not necessary.
To support their comments, FHR and Molex provided clarification that
the pilot study conducted for this AMEL at their West Refinery was
performed with one wind sensor that covered both process units.
Further, the commenters stated that analysis of wind data from the West
Refinery and the Corpus Christi airport showed no substantial
differences between wind sensors at 450 feet apart and wind sensors at
4 miles apart. Therefore, the commenters recommended that the EPA
revise the requirement to allow a minimum of one wind sensor covering
up to a 2-mile radius.
    Another commenter \8\ requested clarification on the acceptance
criterion for the comparison of the LDSN north orientation wind
direction sensor with data from the meteorological station located at
the FHR refinery. This same commenter also asked why wind speed
information was not included in the LDSN since wind can affect the
sensitivity of the sensor measurements.
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    \8\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
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    Response: The EPA agrees with FHR and Molex that one meteorological
station on the FHR site is sufficient for both process units and has
made this change within the AMEL. As noted by both commenters, only one
wind sensor was used during the pilot study, and the EPA has determined
that equivalent emission reductions were achieved based on that pilot
study. See 86 FR 56941 (October 13, 2021). Regarding the use of wind
speeds, the EPA notes that wind speeds are continuously collected at
least once every 15 minutes (paragraph IV.A.(4)), recorded as part of
the LDSN (paragraph IV.C.(8)), and are used for quality assurance
checks of the network (paragraph IV.A.(5)(d)). The acceptance criteria
are listed in the AMEL.
    Comment: FHR requested additional flexibility in meeting quarterly
quality assurance/quality control (QA/QC) requirements by allowing QA/
QC tests to be within the same month of the quarter (or no more than
123 days apart) rather than the 100 days apart included in the initial
notice. FHR commented that tracking by days would present an additional
burden and reduce flexibility that the applicable LDAR regulations
already afford. As an example, FHR stated that new source performance
standards (NSPS) VV and NSPS VVa require quarterly activities within
the same month of the quarter (i.e., Month 1 (January/April/July/Oct))
and not within a specific number of days. FHR requested this same
flexibility for the quarterly QA/QC requirements in the AMEL. Finally,
FHR requests some flexibility if there is an outage of at least 3 weeks
during the quarter such that either the ``days apart'' requirement does
not apply for the quarter in which the outage occurs or the number of
days in the outage are not counted in determining the 123-day
requirement.
    Response: The EPA agrees with FHR and has changed the requirements
in paragraph IV.A.(5) to state quarterly QA/QC activities must be
conducted no more than 123 days apart. EPA disagrees that additional
flexibility is needed for a prolonged unit outage, as these QA/QC
procedures are necessary to establish that the LDSN is working as
intended.
    Comment: FHR and Molex commented that requiring an ambient moisture
adjustment for all sensors during every bump test is not necessary or
practical. To support their comments, FHR stated that the Gulf Coast
experiences significant day-to-day variation in ambient moisture
levels, citing relative humidity data for Corpus Christi in October
2021.\9\ Using the proximity of a sensor node to a steam letdown
station as an example, FHR and Molex further explained that localized
relative humidity conditions can vary significantly within a specific
process unit, with moisture levels potentially changing with each steam
plume that passes a sensor node. Additionally, Molex stated that even
when a sensor has a response to humidity changes, using a higher gas
concentration (e.g., 1 part per million (ppm) instead of 0.5 ppm
isobutylene) may be an appropriate step. Because these localized
conditions may not affect all sensor nodes in the process unit, FHR and
Molex recommended allowing ambient moisture adjustments as necessary,
in place of requiring these adjustments for all sensors during each
bump test. Finally, FHR requested revisions to the recordkeeping
requirements related to the ambient moisture level during bump tests if
the requested changes are made in the AMEL.
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    \9\ See Document ID Nos. EPA-HQ-OAR-2021-0299-0035 and EPA-HQ-
OAR-2021-0299-0036.
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    Response: There was not sufficient information provided to
substantiate the removal of the requirement. The EPA is retaining the
moisture adjustment requirement due to general sensitivities of sensors
to humidity. The EPA has clarified the criteria for these adjustments
in paragraph IV.A.(5)(b)(i). The EPA has not made any adjustments to
the recordkeeping requirements as a result of this clarification.
    Comment: FHR and Molex requested a correction to the vertical
sensor placement requirement in the AMEL. Specifically, both commenters
noted that the initial notice required placement of sensors at least
every 20 feet vertically. The commenters stated their concern that this
was an error and that placement every 40 feet vertically was included
in the LDSN design used for the pilot test study and equivalency
demonstration. As such, the commenters requested clarification that
sensor placement within 40 feet vertically is required. Another

commenter \10\ asked how the AMEL ensures all LDAR components are
covered under the AMEL.
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    \10\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
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    Response: The EPA is clarifying that sensors must be spaced no more
than 40 feet apart vertically, such that no component is more than 20
feet vertically from a sensor. The data submitted by FHR demonstrates
that this vertical spacing provides coverage for all applicable
components. The LDSN-DRF requirements in this AMEL are designed to
cover all LDAR components in the Mid-Crude and Meta-Xylene process
units at FHR's West Refinery. As part of the AMEL, FHR must document
that all LDAR components covered by the AMEL are less than the required
distances from a sensor node both vertically and horizontally. These
distance limits are based on the pilot test study used in the
equivalency demonstration.
    Comment: FHR and Molex requested a change in the response factor
requirement from 3 to 10. FHR stated that EPA Method 21 requires a
response factor of 10, and FHR requested this same response factor for
the LDSN because it is equivalent to the EPA Method 21 requirement.
Further, FHR stated that the response factor for all streams within the
process units covered by this AMEL is less than 3, which would meet
their requested limit of 10. Additionally, FHR is concerned that
limiting the use of the LDSN to streams with a response factor of 3 or
less will restrict the applicability of the AMEL and may affect the use
of the AMEL in the Mid-Crude and Meta-Xylene process units should
certain operational changes occur that result in those process units
having process streams with response factors above 3. Similarly, Molex
commented that this limit would potentially prevent other facilities
from applying for an AMEL. Finally, both FHR and Molex commented that
Molex has significantly improved the ability of their algorithm to
detect leaks and requested that the allowable response factor limit be
increased. Another commenter \11\ noted that there was no data to
support the system would perform adequately for response factors
greater than 10 and noted that ethylene was particularly difficult to
detect during the testing.
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    \11\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
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    Response: In the initial AMEL application, FHR stated that the
average response factor in the Meta-Xylene unit is 0.8, and that the
response factor for some LDAR streams in the Mid-Crude unit can be as
high as 3. While it is possible that the LDSN will perform adequately
at response factors greater than 3, the data in the pilot test study
and equivalency demonstration was limited to streams with response
factors at or below 3. As such, without further data supporting the
system's performance for streams with higher response factors for these
process units, the EPA is retaining the response factor limit of 3 at
the Mid-Crude and Meta-Xylene process units at FHR's West Refinery in
Corpus Christi, Texas. Because each AMEL is site-specific, the EPA
would evaluate any future AMEL requests, including the appropriate
response factor limit, based on data provided for the site-specific
application of the LDSN-DRF system.
    Comment: One commenter \12\ noted that sensor maintenance may be
extensive with the quarterly bump test requirements and replacements
within 30 days if the sensor fails. Another commenter \13\ asked why
the passing criterion of a bump test is only 50 percent of the
standard's nominal concentration, how initial calibration and set-up of
sensors would be conducted and verified, and how sensor baseline levels
are continuously monitored to ensure proper operation.
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    \12\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
    \13\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
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    Response: Sensors must be calibrated by the manufacturer prior to
deployment. Once installed, each sensor must be tested for responsivity
and wireless communication by challenging it with isobutylene gas or
another appropriate standard. Sensors must pass a quarterly bump test
or be recalibrated or replaced. These bump tests are not calibrations,
but simply tests for responsiveness.
    Comment: One commenter noted that the LDSN was similar to a
Continuous Emissions Monitoring System and asked what repercussions
there would be for excessive downtime. The commenter noted that an
appeal of the LDSN is the continuous monitoring, as opposed to
intermittent EPA Method 21 monitoring, but noted that sensor failure is
inevitable.
    Response: Each individual sensor is limited to a downtime of no
more than 10 percent on a rolling 12-month basis. Anything above this
threshold is a deviation. These deviations must be included in the
semiannual reports required under the AMEL. Deviations from any
requirement or obligation established in this AMEL, including the
individual sensor downtime limitation, are violations that may be
subject to enforcement.

D. Comments and Responses Related to the DRF

    Comment: The EPA included a 30-day repair requirement for leaks on
components not subject to LDAR requirements in the initial notice. FHR
commented that non-LDAR component leaks are outside the scope of the
regulations covered in this AMEL; therefore, repair should not be
required under this AMEL. To support their comment, FHR noted these
non-LDAR component leaks are regulated separately under programs such
as CERCLA and TCEQ rules, with such leaks reported as title V
deviations and subject to enforcement. In follow up discussions,\14\
FHR requested that if the EPA were to require repair under this AMEL
for non-LDAR component leaks, then these leaks should also have
provisions for delay of repair consistent with the provisions for LDAR
component leaks. Additionally, FHR requested that if a non-LDAR leak is
identified during an investigation for a potential source location
(PSL), then repair of that non-LDAR component leak should provide
allowance to close the PSL. Another commenter \15\ asked if these non-
LDAR component leaks would be subject to a 15-day repair requirement.
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    \14\ See supporting materials from May 25, 2022, follow-up
discussions with FHR located at Docket ID No. EPA-HQ-OAR-2021-0299.
    \15\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
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    Response: The EPA disagrees with FHR and has maintained a
requirement in this AMEL to complete and verify repairs of leaks on
non-LDAR components within 30 days of identification. The EPA included
a 30-day repair requirement for leaks on components not subject to LDAR
requirements in the initial notice both to require repair of leaks
found (whether or not the leak is from an LDAR component) and to ensure
that the LDSN is not confounded by the presence of these non-LDAR
component leaks. 86 FR 56943 (October 13, 2021). The EPA still finds
that these leaks have the potential to negatively impact the
performance of the LDSN by potentially masking leaks from covered LDAR
components which may occur in the same area as the non-LDAR component
leak. Additionally, these non-LDAR component leaks would already
require repair under the general duty to reduce emissions in each of
the applicable subparts. However, the EPA does agree with FHR that
delay of repair provisions should also apply to non-LDAR

components; therefore, the AMEL approved in this notice allows for
delay of repair of non-LDAR component leaks when repair cannot be
completed within 30 days of identification and either: (1) The repair
is technically infeasible without a process unit shutdown or (2) the
non-LDAR component is isolated from the process and does not remain in
contact with process fluids. We also note that these requirements will
not supersede repair requirements in other regulations to which these
non-LDAR components may be subject, and that leak sources outside the
AMEL covered area are not included in this repair requirement.
    Comment: FHR noted that the initial notice did not address their
request to close a PSL if no emissions source is identified and there
is no update to the PSL for 14 days (i.e., there are no positive
detections for more than five percent of the time over a 72-hour
period). In their comments, FHR again requests the ability to close the
PSL if, after complying with the initial and secondary surveys, there
are no updates to the PSL for 14 days, instead of keeping the PSL open
and conducting a final EPA Method 21 survey after 90 days, as required
in paragraph IV.B.(4). FHR noted in their comments that the requested
14-day closure option would not apply to leaks that are ongoing and
continuing to generate positive detection in the sensor network. They
further state that if a PSL is closed and the leak reappears, the
system would generate a new PSL which is then subject to the
investigation requirements of the DRF. FHR provided suggested revisions
to paragraph IV.B.(4) of the AMEL to incorporate closure of the PSL at
both 14 days and 90 days.
    Another commenter \16\ stated that a PSL should not be closed out
if the leak is unable to be found. This commenter raised concerns that
the AMEL appeared to allow operations/maintenance to ``close out'' a
PSL when a leak is unable to be found even when the sensor is detecting
a leak.
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    \16\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
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    Finally, FHR recommended specific revisions to the recordkeeping
and reporting requirements for PSL closures. First, they recommended
adding records and reporting of a source outside the AMEL-covered
process unit or a non-LDAR component leak source to paragraph
IV.C.(11), as applicable. Second, FHR recommended adding records and
reporting for PSL closures that occur where no cause of the PSL was
determined after 14 days. Lastly, FHR recommended reporting the number
of PSLs that are closed because the emissions were authorized, from a
source outside the AMEL covered process unit, and from a non-LDAR
component leak source.
    Response: The EPA agrees that there is the potential to have a
transient leak and it is reasonable to close a PSL if the sensor nodes
are not showing any indication of leak after 14 days and the required
investigations have been conducted following generation of the PSL.
Further, the EPA agrees that if a persistent leak is present, or the
leak reappears, the LDSN is expected to continue generating a new PSL
or updates to an existing PSL, thus triggering new investigations for
the emissions source. Therefore, the EPA has revised paragraph IV.B.(4)
to include an allowance to close the PSL if the initial and secondary
investigations failed to identify the leak source and there have been
no updates to the PSL for 14 days as requested by FHR.
    Further, the EPA is clarifying the requirements for PSL closure in
situations where 90 days have passed since the original PSL
notification, but the sensor nodes still indicate the presence of a
leak. First, we are adding language to paragraph IV.B.(4)(b) to specify
the requirements of that paragraph apply when 90 days have passed since
the original PSL notification.\17\ Second, we are clarifying that a
full survey of all LDAR-applicable components must be conducted within
10 calendar days following the 90-day period following the original PSL
notification to verify there are no detectable leaks within that PSL
before closure of the PSL is allowed. Finally, the EPA is making the
requested adjustments to the recordkeeping and reporting requirement.
---------------------------------------------------------------------------

    \17\ Paragraph IV.B(3) requires initiating a new investigation
within 3 calendar days when the detections increase by a factor of 2
since the original PSL notification.
---------------------------------------------------------------------------

    Comment: FHR commented that the requirements around the accuracy
and precision of the Global Positioning System (GPS) data collected
during the 30-minute initial investigation are too narrow and limit the
use of future technological advancements. Additionally, FHR raised a
concern regarding how the exact path generated by the GPS tracking may
be evaluated for compliance. Specifically, FHR noted that the process
units included in this AMEL are multi-story with dense equipment areas.
The specific path generated by the GPS tracking may indicate the
technician was outside the PSL during the investigation or may indicate
gaps in data. To address these concerns, FHR suggested revisions to the
language in paragraph IV.B.(1)(g) that include: (1) Record of
coordinates to an accuracy and precision of 5 or more decimals of a
degree, and (2) using the North America Datum of 1983 or newer to
document the path taken by or presence of the technician in the PSL.
    Response: The EPA agrees with this comment and the suggested
revisions provided by FHR because it is not our intent to limit the
technology options to meet this GPS tracking requirement. As such, we
have revised the AMEL to require records of the latitude and longitude
coordinates in decimal degrees to an accuracy and precision of 5 or
more decimals of a degree using the North American Datum of 1983 or
newer to document the path taken by or presence of the technician in
the PSL during the screening investigation.
    Comment: One commenter \18\ raised concerns with the requirement to
conduct an initial investigation within 3 days of a new PSL
notification. This commenter stated that a first attempt at repair is
required within 5 days of leak detection, but FHR would not begin
looking for a leak source until 3 days after the LDSN has identified a
potential leak. The commenter notes that waiting 3 days to investigate
the PSL would allow for greater emissions and little time to make a
good effort at a first attempt to repair the leaking component.
Further, this commenter points to the requirements at 40 CFR
63.163(c)(1), which state repairs must be made ``as soon as
practicable,'' and states their belief that the 3-day gap between LDSN
detection and PSL investigation does not meet this requirement.
---------------------------------------------------------------------------

    \18\ See Document ID No. EPA-HQ-OAR-2021-0299-0033.
---------------------------------------------------------------------------

    Response: The EPA notes that the LDSN is a continuous system, and
as such, PSLs can form at any time. It is reasonable to allow some
timeframe for an investigation to begin to ensure that the appropriate
personnel are onsite to conduct the investigation. Additionally,
current work practices only require inspections of components on an
infrequent basis. Allowing a short timeframe after PSL formation to
begin an investigation still addresses issues much sooner than they
would be under current work practices. As such, the EPA has found that
the requirements of this AMEL result in equivalent or better emission
reductions when compared to the current LDAR requirements.

    Comment: One commenter \19\ stated that FHR should have to monitor
all LDAR applicable components in a PSL using EPA Method 21 to ensure
that no leaks in the PSL are missed. This commenter correctly noted
that the AMEL would require FHR to perform an investigation to identify
the source of a leak in a PSL, and that once FHR identifies one
component with a maximum concentration of 3,000 parts-per-million by
volume (ppmv) they would not be required to monitor any more components
in the PSL. The commenter stated their concern that leaking components
would be missed, and this is counter to a common problem identified in
the EPA's Best Practices Guide for LDAR,\20\ failure to monitor all
regulated components. Another commenter \21\ noted that typical
analyzers that would be used to obtain an EPA Method 21 concentration
reading will lose 10 times a source concentration measurement for every
one-inch the sensor or probe moves away from the emission source but
did not provide additional information on this statement. This same
commenter noted that the higher leak definition seems to contradict the
efficacy of the system when compared to EPA Method 21 programs,
especially where the EPA has lowered leak definitions for petroleum
refineries.
---------------------------------------------------------------------------

    \19\ See Document ID No. EPA-HQ-OAR-2021-0299-0033.
    \20\ EPA, Leak Detection and Repair: A Best Practices Guide,
located at https://www.epa.gov/sites/default/files/2014-02/documents-ldarguide.pdf.
    \21\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
---------------------------------------------------------------------------

    Response: The EPA disagrees with the commenter. Requiring every
component in every PSL to be monitored would be more stringent than the
requirements summarized in Table 1. The design of the LDSN is such that
it will continuously operate and continue to find any additional
leaking components once a PSL is closed out. The results of the pilot
test study and equivalence modeling demonstrate, to the Administrator's
satisfaction, that the emission reductions achieved by the LDSN-DRF are
equivalent or better than the emissions reductions achieved by the
current LDAR requirements. While there may be some small leaks that go
undetected, due to the continuous nature of the network, larger leaks,
or even clusters of small leaks, can be found and fixed much faster.
    Comment: One commenter \22\ requested that the EPA define what
facility information would be included or required to issue a PSL. This
commenter also asked what concentration (in ppmv) defines ``emission
anomalies'' \23\ and whether this is a fixed concentration or if it
varies by process unit.
---------------------------------------------------------------------------

    \22\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
    \23\ 86 FR 56939 (October 13, 2021).
---------------------------------------------------------------------------

    Response: This LDSN uses a web-based analytics platform that
automatically acquires and analyzes the real-time data from the sensor
nodes, along with wind and facility component locations, to issue a
PSL. As stated in response to comment in section II.C, an emissions
anomaly is defined as any detection by the sensor network greater than
the detection floor.
    Comment: One commenter asked if a leaking component placed on delay
of repair will result in the continuous detection of that emission or
if those sensors detecting the component will be shut down or adjusted.
    Response: Placing a component on delay of repair does not require
the sensors detecting those emissions to be shut down. Sensors will
still detect emissions from the component, but a PSL is generated that
isolates the emissions from that component and allows the system to
still identify emissions from other nearby areas.
    Comment: One commenter \24\ raised concerns that the DRF is a
protocol that facility operations will need to follow to support this
new LDAR approach. The commenter stated that similar to the common
stereotypes surrounding LDAR technicians/contractors failing to perform
their duties, an argument can be made on the potential disconnect
between facility operations and environmental staff. This commenter
raised questions about incentives for operations to manage the system
and what potential compliance gaps may occur for failure to report an
emissions event, ignored sensor readings, failure to investigate a PSL,
or failure to complete required documentation.
---------------------------------------------------------------------------

    \24\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
---------------------------------------------------------------------------

    Response: This AMEL applies to the Mid-Crude and Meta-Xylene
process units at FHR's West Refinery in Corpus Christi, Texas. FHR must
comply with all of the conditions in the AMEL. The failure to comply
with any condition in the AMEL, like the failure to comply with any of
the work practice standards replaced by the AMEL, is a CAA violation
subject to enforcement.

E. Comments and Responses Related to Recordkeeping and Reporting

    Comment: FHR requested specific modifications to the requirements
for documentation related to management of change (MOC) to clarify that
this documentation requirement is only for MOC in the AMEL covered
process units.\25\ Another commenter \26\ stated that evaluating sensor
network MOC would likely require constant involvement with Molex.
---------------------------------------------------------------------------

    \25\ See Document ID No. EPA-HQ-OAR-2021-0299-0036.
    \26\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
---------------------------------------------------------------------------

    Response: The EPA agrees with FHR's request and has made this
change within the AMEL. The comment regarding Molex's involvement in
MOC is outside the scope of this AMEL.
    Comment: FHR and Molex requested revisions to paragraph IV.C.(7) of
the AMEL related to the recordkeeping requirements for raw sensor data.
The EPA included a requirement to maintain records of all raw sensor
readings, in addition to, the percent of time positive detections were
registered during the 72-hour lookback, and the minimum, average, and
maximum detection floor. FHR and Molex commented that this amount of
recordkeeping would create vast amounts of data that could be better
managed as part of a batch, periodic evaluation. Further, the
commenters noted that while the algorithm is constantly performing the
calculations to provide this data, the data is not specifically
recorded (i.e., the data elements are not saved as defined in the
requirement). Both commenters state that these calculations could be
recreated at any time from the raw data that is saved and requests that
the AMEL be modified to require records of the raw data, records of any
notifications, and alerts from the algorithm and periodic validation of
the algorithm. FHR and Molex suggested specific language for paragraph
IV.C.(7) in their letters.\27\
---------------------------------------------------------------------------

    \27\ See Document ID Nos. EPA-HQ-OAR-2021-0299-0035 and EPA-HQ-
OAR-2021-0299-0036.
---------------------------------------------------------------------------

    Response: The EPA disagrees that these data are superfluous and
finds that recording of these data is important to maintain in order to
establish an enforceable record of performance. Additionally, if
algorithms for generating alerts change over time, the EPA is concerned
it would alter the ability of FHR to replicate those original records
as they were generated. For these reasons, the EPA has not removed the
requirement to retain these records.
    Comment: FHR commented that some reporting requirements in the
applicable subparts are no longer meaningful to components covered by
the AMEL. For example, FHR noted the percent leaker calculation will no
longer be meaningful because the number of components monitoring with
EPA Method 21 will be

minimal compared to the total population of equipment, thus, the
percent leaker value is no longer a meaningful metric. FHR recommended
a revision to paragraph IV.D.(1) to state that reporting of required
information in the relevant subparts be limited to components not
covered by the AMEL.
    Response: The EPA has added language to clarify reporting
requirements from relevant subparts that are no longer relevant and
replaced by the LDSN.
    Comment: One commenter \28\ stated that new reporting and
recordkeeping requirements are potentially burdensome and would be
prone to compliance gaps. This commenter further stated there would be
confusion for the industry on how to properly report information, and
confusion for the EPA on how to properly evaluate those reports.
---------------------------------------------------------------------------

    \28\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
---------------------------------------------------------------------------

    Response: The EPA disagrees that the recordkeeping and reporting
requirements within the AMEL are prone to compliance gaps. The
requirements within the AMEL are necessary to ensure compliance with
the AMEL and are stated clearly. Without more information on these
potential gaps, we are not adjusting the reporting and recordkeeping
requirements based on this comment.

F. Comments and Responses Related to Additional Annual Compliance
Demonstration

    Comment: FHR commented that the proposed method to determine which
valves to monitor for the annual compliance verification would be
complicated to execute and proposed an alternative or secondary option
that would require monitoring all valves in light liquid/gas vapor (LL/
GV) service every 2 years, with half monitored in the first year and
half monitored in the second year of a 2-year cycle. This monitoring
alternative would be in addition to monitoring all pumps in every
annual compliance verification survey. FHR stated that implementing the
proposed valve monitoring would be difficult to execute in practice,
requiring field surveys to measure distances of valves both
horizontally and vertically from individual sensor nodes.
    In their proposed alternative, FHR would monitor 50 percent of the
LL/GV valves each year (e.g., odd numbered valves monitored in year 1
and even numbered valves in year 2). They stated that this would result
in performing EPA Method 21 monitoring on more valves than the method
proposed by the EPA, and it would provide for easier administration of
the annual compliance verification as it is based on the current
tagging system in place at the refinery. FHR further stated that any
EPA Method 21 instrument readings greater than 18,000 ppmv would be
plotted on a plot plan showing the sensors and active PSLs, and
corrective action would be triggered as outlined in paragraph
IV.E.(1)(e) of the initial notice (86 FR 56949; October 13, 2021). FHR
also requested the removal of the phrase ``under current
investigation'' as an investigation may not have been initiated when
this compliance monitoring is conducted.
    Response: The EPA recognizes that the proposed verification
strategy in FHR's comments is easier to implement and will result in
more components monitored with EPA Method 21 during the annual
compliance demonstration of the LDSN. As such, we are revising the
final AMEL to allow an alternative verification procedure based in part
on FHR's comments. The final AMEL will allow FHR to monitor 50 percent
of the LL/GV valves in the process unit at a time, as suggested in
their comment.
    Comment: FHR and Molex both commented that, as proposed, a single
component with a reading of 18,000 ppmv or greater (excluding active
PSLs or components on delay of repair) would result in noncompliance
for the entire LDSN, with that noncompliance extending until the
corrective actions are complete and FHR has re-monitored the process
unit to demonstrate no components are leaking above 18,000 ppmv outside
an active PSL. These commenters requested revisions to the AMEL that
would allow FHR the opportunity to address small gaps in the LDSN
without considering the entire LDSN out of compliance. FHR stated that
as written, one single gap in coverage invalidates the entire network
even if it is working as designed and detecting leaks in the unit, and
non-compliance with the AMEL would equate to non-compliance with all
the underlying LDAR regulations. Further, FHR noted that the steps
required to come back into compliance could extend beyond 120 days,
especially since the EPA would have to review and approve any changes
to the LDSN. Therefore, FHR also requested an avenue to come back into
compliance in less than the 120-day cycle outlined by the EPA.
    FHR provided a recommendation on how gaps they classified as
``minor'' could be addressed if the EPA were to accept their
recommendation. FHR proposed using a threshold of 10 percent of
monitored components above 18,000 ppmv to determine when the entire
LDSN is out of compliance versus when a more targeted approach to
addressing compliance issues may be appropriate. Specifically, FHR
recommended that if less than 10 percent of the components monitored
during the annual compliance verification were found leaking above
18,000 ppmv, and these components had not been identified by the LDSN
(not in an active PSL and not on delay of repair), then FHR would
conduct EPA Method 21 monitoring of all remaining LL/GV valves and
pumps within a 15-foot radius of each 18,000 ppmv leaking component and
repair any leaks identified. FHR would then modify the LDSN, and the
non-compliance period would end after conducting the described EPA
Method 21 monitoring and repairing all leaking components (or placing
them on delay of repair, as applicable). FHR stated that all leaking
components found above 18,000 ppmv would be considered deviations of
the AMEL and reported as such. In addition, FHR stated they would
conduct quarterly EPA Method 21 monitoring of all LL/GV valves and
pumps within this 15-foot radius until the LDSN modification is
completed and the modification has been tested through the required EPA
Method 21 monitoring following the modification. FHR stated that any
component found leaking above 18,000 ppmv during these quarterly
monitoring events would be considered a deviation and reported as such
in the periodic AMEL report and applicable title V deviation report.
    FHR also proposed that, if more than 10 percent of the components
monitored during the annual compliance verification were leaking above
18,000 ppmv and these components had not been identified by the LDSN,
then the LDSN is not working properly and in this circumstance, FHR
stated that it is appropriate to consider the LDSN out of compliance
with the AMEL. In this situation, FHR stated that EPA Method 21
monitoring would be conducted as required in the underlying LDAR
regulations on all AMEL covered LL/GV valves and pumps until the LDSN
system is redesigned, approved, implemented, and tested through the
required EPA Method 21 monitoring following the modification.
    Additionally, FHR requested the timeline for submitting proposed
revisions to the LDSN be changed to either 45 calendar days or,
alternatively, 30 business days because it would take 7 to 10 days to
verify if any identified leaks are within an active PSL or on delay of
repair. Engagement with Molex for the redesign would take 2 weeks,

and FHR would need at least 2 weeks to develop the proposal prior to
submitting the LDSN revisions to the EPA for approval.
    FHR also proposed defining several keys terms related to their
proposed approach to determining compliance through the annual
verification discussed in these comments: (1) Active PSL, (2) non-
compliant (NC) leaker, and (3) zone of inadequate coverage (ZIC).
First, FHR proposed to define an active PSL as ``a PSL where a
detection or PSL update has occurred within the previous 14 days or a
PSL that is generated up to 72 hours after the monitoring event,
indicating that the LDSN algorithm was in the process of determining
whether a leak had begun when the monitoring took place.'' Next, they
proposed to define a non-compliant leaker (NC leaker) as ``a component
exhibiting a 18,000 ppmv leak or greater during annual compliance
verification monitoring that is outside an active PSL and/or is not a
leaker currently on delay of repair.'' Finally, FHR proposed to define
the ZIC as ``a 15-foot radius horizontally and vertically around a
component that is found to be leaking above 18,000 ppmv during any
annual compliance verification monitoring conducted pursuant to
paragraph IV.E.(1)(b)-(c).''
    Response: The EPA agrees with FHR that it is not appropriate to
consider the entire system out of compliance due to the LDSN failing to
detect a single leak of 18,000 ppmv or greater. However, we do not
agree with FHR's proposal that compliance of the entire LDSN is
achieved until more than 10 percent of monitored components are found
leaking above 18,000 ppmv during the additional annual compliance
demonstration. The EPA has revised the additional annual compliance
demonstration to: (1) define NC leakers, (2) define when a root cause
analysis and corrective action must be conducted, and (3) define what
steps must be taken to bring the system back into compliance. First,
the EPA is requiring FHR to plot all components with leaks above 3,000
ppmv on a plot plan of the process unit. For any component not already
identified in a PSL or placed on delay of repair, a NC leaker would be
defined as either of the following: (1) a component with a leak above
3,000 ppmv that is within 18 feet of a sensor node or (2) a component
included in the LDSN-DRF system with a leak equal to or greater than
18,000 ppmv, regardless of distance to a sensor node. Each NC leaker is
a deviation of the AMEL and may be subject to enforcement. Each NC
leaker should be reported as a deviation until repairs are made and
verified and all other components in the ZIC are monitored with EPA
Method 21 and repaired or placed on delay of repair as necessary.
Additionally, FHR must perform a root cause analysis and take
corrective action to address issues with the LDSN. If 2 or more NC
leakers are found, the LDSN is out of compliance unless corrective
action is completed within 45 days.
    Comment: FHR and Molex requested removal of the requirement for
leak simulations using a controlled release of isobutylene after
modifying the LDSN. Both commenters stated the 1.4 g/hr controlled
release is not directly correlated to an 18,000-ppmv leak rate.
Further, both commenters stated that conducting a controlled release is
more appropriate for scientific experiments and requires a controlled
environment with no other interfering gases. Further, both commenters
noted that the 2-year annual compliance verification clock would reset
with each non-compliant leaker found, which will ensure at least 2
additional EPA Method 21 surveys of the redesigned system. Both
commenters agree with retaining the requirement to conduct a follow up
survey with EPA Method 21 within 60 days after implementing any changes
to the LDSN.
    Response: The EPA agrees with the commenters and has made this
change to remove the requirement to conduct a controlled gas release of
isobutylene following LDSN modification. However, the EPA notes that
FHR could utilize a controlled gas release of isobutylene as part of
the root cause analysis/corrective action requirements in paragraph
IV.E.(1)(i.)
    Comment: One commenter \29\ expressed concerns that the
requirements of the additional annual compliance demonstration are not
more cost-effective than the EPA Method 21 requirements the AMEL would
replace. They specifically stated that a compliance issue would be
identified if a ``statistically significant'' number of EPA Method 21
readings are greater than 1.2 times the DTU but noted that the term
``statistically significant'' was not clearly defined. Further, the
commenter noted that random sampling does not seem like an acceptable
performance metric or a safe mode of operation. Finally, the commenter
noted the requirements to reevaluate the LDSN and perform additional
EPA Method 21 upon redesign seems costly.
---------------------------------------------------------------------------

    \29\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
---------------------------------------------------------------------------

    Response: The EPA notes that this comment applies to the
verification proposed by FHR in its AMEL application. In the AMEL
proposed by the EPA, the EPA did not propose that less than a
statically significant number of leaks that were greater than 1.2 times
the DTU would verify the system works. Instead, the EPA proposed that
there should be no leaks above the DTU in order to verify that the
system works. The potential cost effectiveness is not a factor in the
EPA's determination of equivalency of this AMEL and is, therefore, out
of scope.
    Comment: One commenter \30\ suggested performing 2 additional
biennial (every other year) compliance demonstrations after FHR
demonstrates no leaks above 18,000 ppmv during 2 consecutive annual
demonstrations, before allowing the sunset clause on additional annual
demonstrations to come into effect. This commenter also asked whether
FHR or a third-party would be conducting the EPA Method 21 monitoring
for these compliance demonstrations, stating that use of staff from
another facility or a third-party may provide a more robust compliance
demonstration.
---------------------------------------------------------------------------

    \30\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
---------------------------------------------------------------------------

    Response: The commenter did not provide any additional information
to support the necessity of additional biennial demonstrations after
FHR finds no leaks above the specific thresholds defined in section
IV.E of the AMEL. The EPA notes that revisions have been made to the
additional annual compliance demonstration based on feedback from other
commenters. The EPA does not specify who would perform the EPA Method
21 monitoring and leaves that to the discretion of FHR.

G. Comments and Responses on Other Topics Related to the AMEL

    Comment: FHR requested additional references be added to Table 5 of
the initial notice (Table 1 in section IV of this notice) so that they
are covered under the AMEL. The specific references and provisions
include the following:

 40 CFR part 60, subparts GGG and GGGa (NSPS GGG and NSPS
GGGa)--NSPS for Equipment Leaks of VOC in Petroleum Refineries
 40 CFR 63.163(d)(2)--National Emission Standards for Hazardous
Air Pollutants for Organic Hazardous Air Pollutants From the Synthetic
Organic Chemical Manufacturing Industry (HON) pump quality improvement
program (QIP)
 40 CFR 63.181(b)(1)(i)--List of identification numbers for
equipment subject to the HON

 40 CFR 63.181(b)(4)-(5)--List of instrumentation systems and
list of screwed connectors
 40 CFR 63.181(h)--QIP program recordkeeping
 40 CFR 60.482-7(h)(2) and 40 CFR 60.482-7a(h)(2)--Criteria for
a valve to be designated as difficult-to-monitor
 40 CFR 60.486(b)(2) and 40 CFR 60.486a(b)(2)--Leak tag removal
after 2 consecutive months of monitoring with no leaks detected after
repair
 40 CFR 60.486(e)(1) and 40 CFR 60.486a(e)(1)--List of
identification numbers of equipment subject to 40 CFR part 60, subparts
VV and VVa (NSPS VV and NSPS VVa).

    Another commenter \31\ stated their support for the EPA to remove
requirements for maintaining a list of components or tracking LDAR
changes on a component-by-component basis because these activities can
add significant cost to a traditional LDAR monitoring program. This
commenter also stated that moving away from tracking LDAR changes and
tagging of individual LDAR components would encourage further
acceptance of newer technologies.
---------------------------------------------------------------------------

    \31\ See Document ID No. EPA-HQ-OAR-2021-0299-0037.
---------------------------------------------------------------------------

    Response: The EPA agrees with FHR that some of the specific
references and provisions are appropriate for inclusion in this AMEL.
As such, Table 1 of the AMEL has been updated to include:
     NSPS GGG and NSPS GGGa because the LDSN-DRF has been
demonstrated to provide emission reductions at least equivalent to
those required by the requirements in those subparts.
     HON pump QIP because we are already including the valve
QIP and view the AMEL as an alternative for pumps as well.
     QIP program recordkeeping because it is not relevant if
FHR is not using the QIP.
     Criteria for a valve to be designated as difficult-to-
monitor because the AMEL already serves as an alternative for
difficult-to-monitor monitoring.
     Leak tag removal after 2 consecutive months of monitoring
with no leaks detected after repair because the 2-month follow up on
leaking valves is not required under the AMEL.
    We disagree that the other references to the lists of equipment
identification numbers are appropriate to add to Table 1. Because the
AMEL requires FHR to maintain records that indicate what equipment is
complying with the AMEL or the applicable EPA Method 21 requirements,
the EPA finds that maintaining these lists of equipment are important
for compliance assurance purposes.
    Comment: Multiple commenters supported the implementation and
advancement of sensor networks for leak detection. One commenter \32\
stated their support for alternative means of compliance that do not
include duplicative EPA Method 21 monitoring as that decreases the
creation and adoption of new technology. Another commenter \33\ noted
that programs such as this LDSN-DRF, should be implemented because they
can speed up the leak detection process.
---------------------------------------------------------------------------

    \32\ See Document ID No. EPA-HQ-OAR-2021-0299-0037.
    \33\ See Document ID No. EPA-HQ-OAR-2021-0299-0033.
---------------------------------------------------------------------------

    Response: The EPA has noted the support for these sensor networks.
    Comment: One commenter \34\ stated that the abbreviation ``ppbe''
was not included in the Table of Abbreviations.
---------------------------------------------------------------------------

    \34\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
---------------------------------------------------------------------------

    Response: This abbreviation has been added as requested.
    Comment: One commenter \35\ remarked on the CRADA between FHR,
Molex, and the EPA Office of Research and Development. First, this
commenter stated that FHR did not present the results of their study at
a recent conference, thus preventing public scrutiny of its results and
in direct conflict with one of the longer-term objectives of the CRADA
to ``disseminate non-proprietary technical learning established in this
CRADA by publishing aspects of this research as part of scientific
conferences and in peer reviewed journal articles and reports.''
---------------------------------------------------------------------------

    \35\ See Document ID No. EPA-HQ-OAR-2021-0299-0034.
---------------------------------------------------------------------------

    Next, the commenter provided comments comparing the CRADA to EPA
Method 21. Specifically, the commenter stated that the CRADA postulates
unsubstantiated claims that are critical of EPA Method 21, such as
modest emission reduction estimates based on concentration measurements
at the leak interface, high turnover rates for inspectors, inefficiency
with monitoring all components to find the few that are leaking, and
difficulty with interfacing the data management and reporting software
in multiple touchpoints. This commenter provided counter arguments to
the statements in the CRADA, specifically noting that data loss is an
issue also built into the LDSN-DRF.
    Third, the commenter noted that common complaints about EPA Method
21 could also apply to the LDSN-DRF. The specific complaints noted in
the comment letter deal with inefficiencies of programs (most
components are not leaking), expense (safety and human capital), non-
efficacy (all leaks will not be identified, or there may be a long time
between checks), and proneness to error (recordkeeping for thousands of
inspection events). The commenter noted that with the wrong incentives
in place, LDAR can be ineffective. On the other hand, the commenter
also notes that having an effective LDAR program provides additional
``eyes and ears'' for operations and maintenance because they can
proactively inform these programs. The comment is concerned that the
LDSN-DRF system would remove the presence of LDAR contractors from the
refinery.
    Response: The EPA made all the information provided by FHR
available to the public in this docket and provided the opportunity for
the public to comment on the data. Additionally, the report from the
CRADA is publicly available.\36\ Whether or not this study was
presented in other forums is outside the scope of this AMEL.
---------------------------------------------------------------------------

    \36\ https://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryId=350905&Lab=CEMM.
---------------------------------------------------------------------------

    Comment: One commenter \37\ asked how EPA would perform an audit of
this AMEL. This commenter also specifically asked how the EPA would
determine that enough sensors are present in the process unit to
effectively detect leaks, noting that FHR determined that additional
sensors were needed during the pilot study.
---------------------------------------------------------------------------

    \37\ See Document ID No. EPA-HQ-OAR-2021-0034.
---------------------------------------------------------------------------

    Response: An additional annual compliance verification procedure
has been established in section IV.E of the AMEL which includes EPA
Method 21 monitoring of components to ensure that the LDSN-DRF is
properly detecting leaks from components covered by this AMEL. This
procedure includes EPA Method 21 monitoring of components covered by
this AMEL to verify that the LDSN-DRF is detecting leaks as intended.
The EPA would also look at records related to sensor downtime, actions
taken in response to PSLs, and sensor bump tests, among other
information required by the AMEL to determine compliance with the
requirements. The procedure for developing the optimized sensor node
placement is laid out in the CRADA report, and the information provided
in FHR's AMEL application demonstrates that the LDSN-DRF will provide a
reduction in emissions at least equivalent to the reduction in
emissions

required by the applicable LDAR standards.
    Comment: One commenter \38\ stated that this LDSN framework should
not replace, but instead should supplement, current LDAR practices.
---------------------------------------------------------------------------

    \38\ See Document ID No. EPA-HQ-OAR-2021-0034.
---------------------------------------------------------------------------

    Response: For the purposes of this AMEL, the EPA finds the pilot
test study shows the LDSN provides equivalent or better emission
reductions as the current LDAR requirements for the Mid-Crude and Meta-
Xylene process units at FHR's West Refinery in Corpus Christi, Texas.

H. Out of Scope Comments

    Several comments were received that are outside the scope of this
AMEL.
    Comment: One commenter asked if the LDSN will detect methane leaks
and if the EPA will ask for methane reductions in the future.
    Response: The AMEL is an alternative to LDAR work practices for VOC
and HAP emissions. Any use of the LDSN for methane detection is outside
the scope of this AMEL.
    Comment: One commenter \39\ asked if this AMEL will address how the
facility will estimate emissions and permitted emission rates for
equipment leak fugitive sources, and what effect this AMEL will have on
permitting emission factors and control efficiencies based on
traditional leak definitions and monitoring frequencies.
---------------------------------------------------------------------------

    \39\ See Document ID No. EPA-HQ-OAR-2021-0299-0032.
---------------------------------------------------------------------------

    Response: This AMEL does not address how the facility will estimate
emissions and permitted emission rates for equipment leak fugitive
sources, as that is outside the scope of this AMEL, and the applicable
standards summarized in Table 1 of section IV.
    Comment: One commenter stated that the data presented in this AMEL
shows that nontraditional LDAR components should be monitored too.
    Response: Expanding the requirements of current LDAR programs is
outside of the scope of this AMEL. Additionally, this AMEL is limited
in scope to the proposed LDSN-DRF and whether or not it results in
equivalent or better emissions reductions. However, we note that we are
requiring the repair of non-LDAR leaks in this AMEL when they
contribute to a PSL.
    Comment: One commenter stated that the pilot study indicated that
the facility's LDAR program was not run as well as it could be and
asked why the LDSN would be any different.
    Response: This is outside the scope of this AMEL.

III. Final Framework for Streamlining Approval of Future LDSN-DRF AMEL
Requests

    The EPA is finalizing a framework that sources may use to submit an
AMEL request to the EPA for the use of a LDSN-DRF to comply with the
LDAR requirements under 40 CFR parts 60, 61, and 63. Sources applying
for use of a LDSN-DRF as a work practice standard should provide the
EPA with the following information, at a minimum, in their AMEL
application to demonstrate equivalency of emission reductions.

A. Site-Specific Information Related to All Process Unit(s) Included in
the Alternative Request

    1. Site name and location and applicable process units.
    2. Detailed list or table of applicable regulatory subparts for
each included process unit, the citations within each subpart that will
be replaced or changed by the AMEL and, if changed, how it will be
changed, and the authority that allows for use of an AMEL.
    3. Details of the specific equipment or components that will be
inspected and repaired as part of the AMEL and whether any equipment
within the process unit will not be covered by the AMEL.
    4. A diagram showing the location of each sensor in the process
unit and the minimum spacing that achieves equivalence (i.e., the
furthest distance a component can be located from a sensor while
demonstrating equivalence), taking into consideration multi-level and
elevated components.
    5. Information on how MOC will be addressed. At a minimum, the MOC
must include a determination of whether the changes are within the LDSN
coverage area (i.e., within the specified radius of coverage for each
individual sensor, including coverage based on elevation) or if changes
will result in components added to an applicable EPA Method 21 work
practice where the LDSN would not provide coverage. The MOC must also
address updates to the diagrams of each sensor or the list of equipment
identification numbers, as applicable.

B. Identification of Monitoring Techniques Used for Both the LDSN and
DRF

    1. Identification of the sensors that will be used to detect and
locate leaks, including the sensor measurement principle, type, and
manufacturer.
    2. Data recording frequency, the minimum data availability for the
system and for each sensor, and the process for dealing with periods
where data is not available.
    3. Initial and ongoing QA/QC measures and the timeframes for
conducting such measures.
    4. Restrictions on where the sensors cannot be used.
    5. How meteorological data will be collected, the specific data
that will be collected, and how it will be paired with the sensor data.

C. Defined Work Practice

    1. Description of what triggers action, description of the
action(s) that is triggered, and the timeline for performing the
action(s).
    2. Definition for when a leak requires repair.
    3. Identification of repair deadlines, including verification of
repair.
    4. Description for how repairs will be verified.
    5. Actions that will be taken if an alert is issued by the system,
but a leak cannot be found.
    6. Initial and continuous compliance procedures, including
recordkeeping and reporting, if the compliance procedures are different
than those specified in the applicable subpart(s).
    7. Compliance assurance procedures to ensure the LDSN is operating
as designed and corrective actions (including timeframes) in response
to findings.

D. Demonstration of Equivalency

    1. Demonstration of the emission reduction achieved by the
alternative work practice including restrictions and downtime.
Restrictions should include any conditions which are not demonstrated
as equivalent in the request, such as replacement of audio, visual, or
olfactory (AVO) monitoring or no detectable emissions standards.
    2. Determination of equivalency between the standard work practice
and the alternative requested, which may include modeling results.
    3. Results of the pilot test study conducted for each unit.
    a. For each PSL generated, the date for each notice, the identified
emission source, the date the associated emission source was found for
each PSL, the date the emission source was repaired, the EPA Method 21
reading associated with the emission source, and the date of the last
required and next required EPA Method 21 inspection for the emission
source (or identification of the source as not subject to inspection).
    b. For each leak found with an EPA Method 21 inspection that was
not found by the LDSN-DRF during the test study, the date the leak was
found, the EPA Method 21 reading for the leak, the date the leak was
repaired, and the inspection frequency of the component.

    c. The results of all EPA Method 21 inspections for the unit during
the test study.

IV. Final Notice of Approval for the Mid-Crude and Meta-Xylene Process
Units at the FHR West Refinery AMEL Request and Required Operating
Conditions

    Based on information the EPA received from FHR and the comments
received through the public comment period, the EPA is approving FHR's
request for an AMEL for the LDSN-DRF system for the Mid-Crude and Meta-
Xylene process units located at FHR's West Refinery in Corpus Christi,
Texas. The specific requirements of this LDSN-DRF AMEL are provided in
this section. The approved work practice requirements for the LDSN-DRF
will achieve a reduction in emissions at least equivalent to the
emissions reductions achieved by the portion of the current LDAR work
practice specified in Table 1. This AMEL replaces the portions of the
work practice standards outlined in Table 1. The leak definitions
specified in Table 2 apply to all EPA Method 21 instrument readings
required by this AMEL.

            Table 1--Summary of LDAR Requirements To Be Replaced With the LDSN-DRF AMEL Requirements
----------------------------------------------------------------------------------------------------------------
     Applicable  rules with LDAR                                       Requirement replaced with LDSN-DRF AMEL
             requirements                        Citation                            requirements
----------------------------------------------------------------------------------------------------------------
NSPS VV..............................  60.482-2(a)(1)..............  EPA Method 21 monitoring of pumps in light
                                                                      liquid service.
                                       60.482-7(a) and (c).........  EPA Method 21 monitoring of valves in gas/
                                                                      vapor service and in light liquid service.
                                       60.482-7(h)(2)..............  EPA Method 21 monitoring criteria for
                                                                      difficult-to-monitor.
                                       60.482-7(h)(3)..............  EPA Method 21 monitoring at a reduced
                                                                      frequency for valves in gas/vapor service
                                                                      and in light liquid service that are
                                                                      designated as difficult-to-monitor.
                                       60.486(b)(2)................  Leak tag removal after 2 consecutive months
                                                                      of monitoring with no leaks detected after
                                                                      repair.
                                       60.486(g)...................  Schedule of monitoring and leak percentage
                                                                      for valves utilizing skip periods.
NSPS VVa.............................  60.482-2a(a)(1).............  EPA Method 21 monitoring of pumps in light
                                                                      liquid service.
                                       60.482-7a(a) and (c)........  EPA Method 21 monitoring of valves in gas/
                                                                      vapor service and in light liquid service.
                                       60.482-7a(h)(2).............  EPA Method 21 monitoring criteria for
                                                                      difficult-to-monitor.
                                       60.482-7a(h)(3).............  EPA Method 21 monitoring at a reduced
                                                                      frequency for valves in gas/vapor service
                                                                      and in light liquid service that are
                                                                      designated as difficult-to-monitor.
                                       60.482-11a(a), (b), (b)(1),   EPA Method 21 monitoring of connectors in
                                        (b)(3), (b)(3)(i)-(iv), and   gas/vapor service and in light liquid
                                        (c).                          service.
                                       60.486a(b)(2)...............  Leak tag removal after 2 consecutive months
                                                                      of monitoring with no leaks detected after
                                                                      repair.
                                       60.486a(g)..................  Schedule of monitoring and leak percentage
                                                                      for valves utilizing skip periods.
NSPS GGG.............................  60.482-2(a)(1), by reference  EPA Method 21 monitoring of pumps in light
                                        from 60.592.                  liquid service.
                                       60.482-7(a) and (c), by       EPA Method 21 monitoring of valves in gas/
                                        reference from 60.592.        vapor service and in light liquid service.
                                       60.482-7(h)(3), by reference  EPA Method 21 monitoring at a reduced
                                        from 60.592.                  frequency for valves in gas/vapor service
                                                                      and in light liquid service that are
                                                                      designated as difficult-to-monitor.
                                       60.486(g), by reference from  Schedule of monitoring and leak percentage
                                        60.592.                       for valves utilizing skip periods.
NSPS GGGa............................  60.482-2a(a)(1) by reference  EPA Method 21 monitoring of pumps in light
                                        from 60.592a.                 liquid service.
                                       60.482-7a(a) and (c) by       EPA Method 21 monitoring of valves in gas/
                                        reference from 60.592a.       vapor service and in light liquid service.
                                       60.482-7a(h)(3) by reference  EPA Method 21 monitoring at a reduced
                                        from 60.592a.                 frequency for valves in gas/vapor service
                                                                      and in light liquid service that are
                                                                      designated as difficult-to-monitor.
                                       60.482-11a(a), (b), (b)(1),   EPA Method 21 monitoring of connectors in
                                        (b)(3), (b)(3)(i)-(iv), and   gas/vapor service and in light liquid
                                        (c) by reference from         service.
                                        60.592a.
                                       60.486a(g) by reference from  Schedule of monitoring and leak percentage
                                        60.592a.                      for valves utilizing skip periods.
HON..................................  63.163(b)(1)................  EPA Method 21 monitoring of pumps in light
                                                                      liquid service.
                                       63.163(d)(2)................  Quality improvement program for pumps.
                                       63.168(b)-(d)...............  EPA Method 21 monitoring of valves in gas/
                                                                      vapor service and in light liquid service.
                                       63.168(f)(3)................  EPA Method 21 monitoring following
                                                                      successful repair of valves in gas/vapor
                                                                      service and in light liquid service.
                                       63.173(a)(1)................  EPA Method 21 monitoring of agitators in
                                                                      gas/vapor service and in light liquid
                                                                      service.
                                       63.173(h)...................  EPA Method 21 monitoring at a reduced
                                                                      frequency for agitators in gas/vapor
                                                                      service and in light liquid service that
                                                                      are designated as difficult-to-monitor.
                                       63.174(a)-(c)...............  EPA Method 21 monitoring of connectors in
                                                                      gas/vapor service and in light liquid
                                                                      service.
                                       63.175(c)(3), (d)(1), and     Quality improvement program for valves
                                        (d)(4)(ii).                   where the leak rate is equal to or exceeds
                                                                      2 percent.
                                       63.178(c)(1)-(3)............  EPA Method 21 monitoring of components
                                                                      using the alternative means of emission
                                                                      limitation for batch processes.
                                       63.181(b)(1)(ii)............  Schedule by process unit for connector
                                                                      monitoring.
                                       63.181(b)(7)(i) and (ii)....  Identification, explanation, and monitoring
                                                                      schedule of difficult-to-monitor
                                                                      components.
                                       63.181(d)(7)................  Listing of connectors subject to EPA Method
                                                                      21 monitoring.
                                       63.181(d)(8)................  EPA Method 21 monitoring for batch
                                                                      processes.
                                       63.181(h)...................  Quality improvement program recordkeeping.
----------------------------------------------------------------------------------------------------------------

                                       Table 2--Applicable Leak Definitions for Components in the LDSN-DRF System
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Initial          Final
  LDSN leak source classification    Leak source component     LDSN leak definition         repair         effective       Final repair  confirmation
                                             class                                      attempt (days)  repair  (days)
--------------------------------------------------------------------------------------------------------------------------------------------------------
LDAR Component Leak--``LDAR''......  Agitator--FF.........  500 ppmv..................               5              15  <500 ppmv.
LDAR Component Leak--``LDAR''......  Agitator--VV.........  2,000 ppmv................               5              15  <2,000 ppmv.
LDAR Component Leak--``LDAR''......  Agitator--HON........  10,000 ppmv...............               5              15  <10,000 ppmv.
LDAR Component Leak--``LDAR''......  Compressor--HON......  500 ppmv..................               5              15  <500 ppmv.
LDAR Component Leak--``LDAR''......  Compressor--non HON..  2,000 ppmv................               5              15  <2,000 ppmv.
LDAR Component Leak--``LDAR''......  Compressor in          AVO.......................               5              15  No AVO indication.
                                      Hydrogen Service.
LDAR Component Leak--``LDAR''......  Connector............  500 ppmv..................               5              15  <500 ppmv.

LDAR Component Leak--``LDAR''......  Pump--with permit      500 ppmv..................               5              15  <500 ppmv.
                                      specifying 500 ppmv.
LDAR Component Leak--``LDAR''......  Pump--HON............  1,000 ppmv................               5              15  <1,000 ppmv.
LDAR Component Leak--``LDAR''......  Pump--VV.............  2,000 ppmv................               5              15  <2,000 ppmv.
LDAR Component Leak--``LDAR''......  Valve................  500 ppmv..................               5              15  <500 ppmv.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Agitator--Hydrocarbon  10,000 ppmv...............       Follow emission event      <10,000 ppmv.
 Event''.                             (HC) but non LDAR.                                     reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Compressor--HC but     2,000 ppmv................       Follow emission event      <2,000 ppmv.
 Event''.                             non LDAR.                                              reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Connector--HC but non  500 ppmv..................       Follow emission event      <500 ppmv.
 Event''.                             LDAR.                                                  reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Pump--HC but non LDAR  2,000 ppmv................       Follow emission event      <2,000 ppmv.
 Event''.                                                                                reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Relief Device--HC but  500 ppmv..................       Follow emission event      <500 ppmv.
 Event''.                             non LDAR.                                              reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Valve--HC but non      500 ppmv..................       Follow emission event      <500 ppmv.
 Event''.                             LDAR.                                                  reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
Non-LDAR Component Leak--``Emission  Other................  500 ppmv..................       Follow emission event      <500 ppmv.
 Event''.                                                                                reporting and repair
                                                                                guidelines.
                                                                                --------------------------------
``Authorized Emission'' \1\........  Authorized Emission..  N/A.......................             N/A             N/A  N/A.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Authorized emissions may include emissions from a stack or otherwise allowed. These emissions are not considered equipment leaks for purposes of
  this AMEL.

A. LDSN Specifications

    1. Sensor Selection.
    A sensor meeting the following specifications is required:
    a. The sensor must respond to the compounds being processed.
    The average response factor of each process stream must be less
than or equal to 3. If the average response factor of a process stream
is greater than 3, the components in that service are not covered by
this AMEL.
    b. The sensor must be capable of maintaining a detection floor of
less than 10 ppbe on a 10-minute average. The detection floor is
determined at three times the standard deviation of the previous 10
minutes of data excluding excursions related to emissions peaks.

Detection FloorSensor n = 3 x SDLocal n

Detection FloorSensor n = Calculated detection floor of
sensor n (ppbe)
SDLocal n = Local (previous ten minutes) standard
deviation of measurements excluding transient spikes (sensor raw
output typically mV)

    c. The sensor must record data at a rate of once per second.
    d. Records of sensor selection must be maintained as specified in
IV.C(3) and records of detection floor must be maintained as specified
in IV.C(g).
    2. Sensor placement.
    The sensor placement must meet the following specifications:
    a. The Mid-Crude process unit must have a minimum of 44 sensors and
the Meta-Xylene process unit must have a minimum of 10 sensors.
    All components covered by the LDSN-DRF must be no further than 50
feet from a sensor node in the horizontal plane and no more than 20
feet from a sensor node in the vertical plane. Sensor nodes must be
placed and must remain in accordance with the single level and multi-
level records required in IV.C(4).
    b. As part of the management of change procedure, FHR must identify
if the changes (i.e., additions or removals) to process equipment in
the Mid-Crude and Meta-Xylene process units are within the 50-foot
radius and 20-foot vertical distance to any single sensor within the
process unit or whether new process streams exist within the LDSN.
    FHR must identify any LDAR-applicable components associated with
the changes to the process equipment that are outside of the 50-foot
radius and 20-foot vertical distance requirements for the LDSN and
either comply with the standard EPA Method 21 LDAR requirements for
those components as required in the applicable subpart(s) or add
additional sensor nodes to the LDSN such that all of the LDAR-
applicable components covered by the LDSN-DRF are no further than 50
feet from a sensor node in the horizontal plane and no more than 20
feet from a sensor node in the vertical plane. FHR must identify any
LDAR-applicable components associated with the changes to the process
equipment that contain process streams with a response factor of
greater than three and comply with the standard EPA Method 21 LDAR
requirements for those components as required in the applicable
subpart(s). FHR must maintain the management of change records in
IV.C(5).
    3. PSL Notifications.
    The system must perform a 72-hour lookback a minimum of once per
day that includes the previous 24-hour period to determine the percent
of time positive detections were registered. Positive detections are
defined as peak excursions above the detection floor. If positive
detections are registered for at least 5 percent of the time during the
rolling 72-hour lookback, a PSL notification must be issued. Records of
raw sensor readings and PSL notifications must be maintained in
accordance with IV.C(7) and (9), respectively.
    4. Meteorological Data.
    FHR must continuously collect wind speed and wind direction data at
least once every 15 minutes. The wind sensor must be located onsite and
within 2 miles of each sensor node. FHR must maintain records in
accordance with IV.C(8).
    5. QA/QC.
    The following QA/QC must be employed for the sensors in the
network:
    a. Sensors must be calibrated by the manufacturer prior to
deployment.

    Once installed, each sensor must be tested for responsivity and
wireless communication by challenging it with isobutylene gas or
another appropriate standard. FHR must maintain records in accordance
with IV.C(6).
    b. FHR must conduct a bump test on each sensor quarterly.
    At a minimum, quarterly bump tests must be conducted no more than
123 days apart.
    (i) The bump test must be conducted with isobutylene gas or another
appropriate standard (e.g., with similar response factors) and include
a mechanism to provide nominally ambient level moisture to the gas
(within 25 percent of ambient relative humidity).
    (ii) The bump test is successful if the response of the sensor
exceeds 50 percent of the nominal value of the standard. The bump test
may be repeated immediately up to 2 additional times if the first bump
test is unsuccessful.
    (iii) If the bump test is unsuccessful after the third try, the
sensor must be recalibrated or replaced with a calibrated sensor within
24 hours of the third unsuccessful try. After recalibration, a new bump
test must be conducted following the procedure outlined above.
    (iv) FHR must maintain records of the bump test in accordance with
IV.C(6).
    c. The health of each sensor must be confirmed for power and data
transmission at least once every 15 minutes.
    Data transmission, which includes data recorded by the sensor every
second as noted in IV.A(1)(c), must occur at least once every 15
minutes. Appropriate corrective actions must be taken for any sensors
that fail to collect data in accordance with IV.A(1)(b) and (c) and
transmit data in accordance with this paragraph to ensure any errors or
malfunctions are corrected in a timely manner. Such periods are
considered downtime until corrected. If a sensor repair is necessary,
FHR must test the responsivity and wireless communication of the sensor
through a bump test according to the procedure specified in IV.A(5)(b).
FHR must maintain records of sensor health in accordance with IV.C(6).
    d. The sensor detection floor shall be reviewed at 00:00 UTC each
day to confirm each sensor detection floor remains below the
established threshold of 10 ppbe during at least one 10-minute period
in the past 72-hour period. If a sensor does not pass the detection
floor review, then a sensor fault notification shall be issued, and the
sensor issue shall be corrected through repair, replacement, or another
appropriate measure, unless FHR can demonstrate the sensor was
continuously experiencing positive detections during this time.
    e. At least once each calendar quarter, conduct a check for wind
direction to ensure the wind sensor is properly oriented to the north.
If the wind sensor is not within 15 degrees of true north, it must be
adjusted to point to true north. At a minimum, quarterly wind direction
checks must be conducted no more than 123 days apart. The results of
the quarterly check for wind direction must be kept in accordance with
IV.C(8).
    6. Downtime.
    The sensor network must continuously collect data as specified in
paragraph IV.A(5)(c), except as specified in this paragraph:
    a. The rolling 12-month average operational downtime of each
individual sensor must be less than or equal to 10 percent.
    b. Operational downtime is defined as a period of time for which
the sensor fails to collect or transmit data as specified in IV.A(5)(c)
or the sensor is out-of-control as specified in IV.A(6)(c).
    c. A sensor is out-of-control if it fails a bump test or if the
sensor output is outside of range.
    The beginning of the out-of-control period for a failed bump test
is defined as the time of the failure of a bump test. The end of the
out-of-control period is defined as the time when either the sensor is
recalibrated and passes a bump test, or a new sensor is installed and
passes the responsivity and communication challenge. The out-of-control
period for a sensor outside of range starts at the time when the sensor
first reads outside of range and ends when the sensor reads within
range again.
    d. The downtime for each sensor must be calculated each calendar
month. Once 12 months of data are available, at the end of each
calendar month, FHR must calculate the 12-month average by averaging
that month with the previous 11 calendar months. FHR must determine the
rolling 12-month average by recalculating the 12-month average at the
end of each month.
    e. FHR must maintain records of the downtime for each sensor in
accordance with IV.C(13).

B. DRF Specifications

    When a new PSL notification is received, the following requirements
apply:
    1. An initial screening investigation must begin within 3 calendar
days of receiving a new PSL notification.
    a. The initial screening investigation must utilize technology that
can detect hydrocarbons or that is capable of responding to the
compounds or mixture of compounds in the process streams at levels
appropriate for locating leaks.
    This technology must be maintained per manufacturer
recommendations. Technologies that the EPA finds appropriate for use
are photoionization detectors (PID), flame ionization detectors (FID),
and optical gas imaging (OGI) cameras.
    b. Each potential leak source identified in the initial screening
investigation must be monitored by EPA Method 21 as specified in
section 60.485a(b) of 40 CFR part 60, subpart VVa.
    c. If an instrument reading equal to or greater than the
concentrations listed in Table 2 is measured, a leak is detected.
    The maximum instrument reading must be recorded for each leak
identified. A weatherproof and readily visible identification shall be
attached to the leaking equipment. The identification may be removed
once the component has been repaired, with the repair confirmed through
follow up EPA Method 21 monitoring.
    d. When a leak is detected, it shall be repaired as specified in
the applicable subpart(s), except as specified in this paragraph.
    1. If the leak source is not applicable to LDAR but is within the
AMEL covered area, repairs must be completed and verified within 30
calendar days of identification or placed on delay of repair. Delay of
repair of equipment for which leaks have been detected will be allowed
when repair cannot be completed within 30 days of identification and
either the repair is technically infeasible without a process unit
shutdown or the non-LDAR equipment is isolated from the process and
does not remain in contact with process fluids. Repair of this
equipment must occur prior to the end of the next process unit shutdown
or prior to ending the equipment's isolation from the process and
returning process fluids to the equipment. These requirements do not
supersede repair requirements for other regulations.
    2. If the leak source is determined to be associated with
authorized emissions (e.g., regulated emissions from a stack or process
equipment that are not fugitive emissions), the facility must document
this information for the record, and the PSL can be closed.
    e. If a single leak is detected at 3,000 ppmv or greater by EPA
Method 21, the investigation is complete, and the PSL can be closed
once this leak and any

leaks above the leak definitions specified in Table 2 found by Method
21 during this investigation have been repaired in accordance with the
applicable subpart(s) or for non-LDAR equipment leaks, when the repair
has been verified by EPA Method 21.
    f. If a total of 3 leaks are detected below 3,000 ppmv but above
the leak definitions specified in Table 2 by EPA Method 21, the
investigation is complete, and the PSL can be closed once these leaks
and any leaks above the leak definitions specified in Table 2 found by
Method 21 during this investigation have been repaired in accordance
with the applicable subpart(s) or for non-LDAR equipment leaks, when
the repair has been verified by EPA Method 21.
    g. For each initial screening investigation in which a potential
leak source is not identified after 30 minutes of active screening
within the PSL, record the latitude and longitude coordinates in
decimal degrees to an accuracy and precision of 5 or more decimals of a
degree using the North American Datum of 1983 or newer to document the
path taken by or presence of the technician in the PSL during the
screening investigation. Include the date and time stamp of the start
and end of the investigation. The PSL must remain open, but the initial
screening investigation may stop.
    2. A second screening investigation must be conducted within 7
calendar days of stopping the initial screening investigation as
described in IV.B(1)(g). The requirements specified in IV.B(1)(a)
through (f) apply to this second screening investigation.
    3. If no potential leak sources are identified during the second
screening investigation, and the PSL detection level increases by 2
times the initial detection level, a PSL update notification must be
sent to facility personnel based on the higher detection level. A new
screening investigation must occur within 3 calendar days of receiving
the PSL update notification with the higher detection level, following
the conditions specified in paragraphs IV.B(1)(a) through (f). This
step must be repeated every time the PSL notification is sent, and a
leak source is not found in the previous screening. The PSL must remain
open until the conditions in IV.B(1)(e) or (f) are met.
    4. If no potential leak source has been identified following the
screening investigations in IV.B(2) and (3), the PSL can be closed
after meeting the conditions specified in either paragraph IV.B(4)(a)
or (b).
    a. If 14 days have passed since a positive detection within the PSL
(i.e., there have been no peak excursions above the detection floor),
the PSL may be closed.
    b. If 90 days have passed since the original PSL notification, all
sensors used to create the PSL must be bump tested in accordance with
IV.A(5)(b) and a full survey of the LDAR-applicable components within
the PSL must be conducted with EPA Method 21 within 10 calendar days.
    A leak is defined by the applicable subpart(s). All leaks
identified during this survey must be repaired and verified after which
the PSL will be closed. If no leaks are identified in this final
screening, ``no leak source found'' must be recorded and the PSL will
be closed.
    c. FHR must maintain the records in accordance with IV.C(9)-(11).

C. Recordkeeping

    The following records related to the LDSN-DRF must be maintained in
addition to the records from the relevant subparts, except as noted in
Table 1.
    1. Fugitive Emission Management Plan (FEMP) detailing the
boundaries of the Meta-Xylene and Mid-Crude process units which are
complying with this AMEL.
    The plan must include the records for the LDSN specified in
paragraph IV.C(4), a list of identification numbers for equipment
subject to the EPA Method 21, no detectable emissions, or AVO work
practice requirements of the applicable subparts, and a map clearly
depicting which areas in each process unit are covered by the LDSN-DRF
and which are covered by the EPA Method 21, no detectable emissions, or
AVO work practices.
    2. Records of the sensor response factors for the applicable
process streams.
    3. Manufacturer, measurement principle, response factors, and
detection level for each sensor.
    4. Records of sensor placement, including geographic information
system (GIS) coordinates and elevation of the sensor from the ground,
and diagrams showing the location of each sensor and the detection
radius of each sensor. One diagram must show all sensors, with an
indication of the level each sensor is located on. Additional diagrams
showing sensor layout must be provided for each level of the process
unit.
    5. Records of each MOC in an AMEL covered unit. For each MOC,
records of the determination that IV.C(5)(a), (5)(b), or (5)(c)
applies. The MOC must also address updates to the diagrams in the FEMP
of each sensor or the list of equipment identification numbers, as
applicable.
    a. The changes are within the LDSN coverage area (i.e., no further
than 50 feet from a sensor node in the horizontal plane and no more
than 20 feet from a sensor node in the vertical plane) and the response
factor of any new process streams is less than or equal to 3.
    b. The response factor any new process streams is less than or
equal to 3 and additional sensor nodes are being added to the LDSN such
that all the LDAR-applicable components covered by the LDSN-DRF are no
further than 50 feet from a sensor node in the horizontal plane and no
more than 20 feet from a sensor node in the vertical plane.
    c. The components will be added to an applicable EPA Method 21, no
detectable emissions, or AVO work practice where the LDSN would not
provide coverage.
    6. Records of initial and subsequent calibrations, bump tests for
responsivity and wireless communication initially and upon sensor
repair or reset, quarterly bump tests, bump tests prior to PSL closure
where leaks have not been found within 90 days, and bump tests
following out-of-control periods, including dates and results of each
calibration and bump test, as well as a description of any required
corrective action and the date the corrective action was performed.
Records of calibration gases used for the bump tests, the ambient
moisture level during the bump tests, and the mechanism for providing
nominally ambient level moisture to the gas during the bump tests.
Records of sensor health related to power and data transmission.
    7. Raw Sensor Readings. Additionally, for each sensor, the percent
of time positive detections were registered during the 72-hour lookback
must be recorded each day and the minimum, average, and maximum
detection floor.
    8. Network Meteorological Data, Including Wind Direction and Wind
Speed.
    Record the results of each quarterly check of the wind sensor
orientation. Record the latitude and longitude coordinates of the
original location of the wind sensor. The wind sensor must remain
within 300 feet of the original location. Record each movement of the
wind sensor, the latitude and longitude coordinates for the new
location, and the distance in feet between the new location and the
original location.
    9. PSL Documentation. For each PSL, the record must include the
notification date, investigation start date, investigation results
including the date each leak was found, leaking component

location description, EPA Method 21 reading, repair action taken, date
of repair, and EPA Method 21 reading after repair. Additionally, for
equipment placed on delay of repair, note that the equipment was placed
on delay of repair and the reason for the delay of repair.
    10. PSL documentation where PSL is not closed out after the initial
investigation.
    For each PSL that cannot be closed out after the initial
investigation, the record must include each screening investigation
performed, including the latitude and longitude coordinates indicating
the path taken during the screening investigation, the start and end
date and times of the investigation, any OGI video taken during the
investigation, and any Method 21 readings observed during the
investigation. The record must also include the date of each PSL update
notification sent to facility personnel when the PSL detection level
increases by 2 times the initial detection level.
    11. If a PSL is caused by an authorized emission source or a source
outside the AMEL-covered process unit, the documentation must include
the notification date, investigation start date, investigation results,
emission source identification, and description of the ``authorized
emissions'' or source outside the AMEL-covered process unit.
    12. Records of PSLs closed out where no cause of the PSL was
determined. Note whether the PSL was closed because 14 days had passed
since a positive detection within the PSL or the PSL was closed
following the EPA Method 21 inspection conducted 90 days after the
original PSL notification.
    13. For each sensor, the date and time of the beginning and end of
each period of operational downtime.
    14. For each additional annual compliance demonstration conducted
under the compliance assurance provisions of IV.E below, the
documentation must include:
    a. The date of each survey conducted with Method 21 of appendix A-7
of part 60.
    b. If valves are monitored in accordance with IV.E(1)(b)(i) through
(v), the plot plan showing the verification zone of each sensor, the
list of valves in the verification zones, and the total population of
valves in the process unit.
    c. If valves are monitored in accordance with IV.E(1)(b)(vi), the
list of all valves in the process unit and identification of each valve
monitored during the survey.
    d. The EPA Method 21 reading for each valve and pump monitored.
    e. For each leak found, the date each leak was found, leaking
component location description, repair action taken, date of repair,
and EPA Method 21 reading after repair.
    Additionally, for equipment placed on delay of repair, note that
the equipment was placed on delay of repair and the reason for the
delay of repair. Delay of repair shall be determined and signed-off
from the relevant process unit supervisor or person of similar
authority that the piece of equipment is technically infeasible to
repair without a process unit shutdown.
    f. Plot plan with all components identified with EPA Method 21
screening values greater than 3,000 ppmv, all active PSLs, and the
locations of each sensor node, if applicable.
    g. Identification of all non-compliant leakers and each zone of
incomplete coverage.
    h. For each survey conducted in a zone of incomplete coverage, the
information in IV.D.(14)(a), (14)(d), and (14)(e), as well as an
identification of each valve and pump monitored.
    i. The start and end dates and results of any required root cause
analysis, any corrective action taken in response to a non-compliant
leaker, and any corrective action plans developed.
    14. Records of deviations where a deviation means FHR fails to meet
any requirement or obligation established in this AMEL or fails to meet
any term or condition that is adopted to implement an applicable
requirement or obligation in this AMEL and that is included in the
operating permit for the Mid-Crude or Meta-Xylene process units at FHR.

D. Reporting

    Semiannual reports must be submitted via the Compliance and
Emissions Reporting Data Interface (CEDRI), which can be accessed
through the EPA's Central Data Exchange (CDX) (https://cdx.epa.gov),
following the procedures specified in 40 CFR 63.9(k). Semiannual
reports must include the following information:
    1. All of the information required in the relevant subparts for
components not covered by this AMEL.
    2. For each PSL, the notification date, investigation start date,
investigation results including the date each leak was found, type of
component, EPA Method 21 reading, and date of repair. For each PSL that
was not closed out after the initial investigation, the date of each
PSL update notification sent to facility personnel when the PSL
detection level increases by 2 times the initial detection level, each
investigation start date, and results for each investigation.
    3. Identification of equipment placed on delay of repair and the
facts that explain each delay of repair.
    4. The number of PSLs that were closed out where no cause of the
PSL was determined. Note how many PSLs were closed because 14 days had
passed since a positive detection within the PSL and how many PSLs were
closed following the EPA Method 21 inspection conducted 90 days after
the original PSL notification.
    5. The number of PSLs that were closed because the emissions were
authorized.
    6. The number of PSLs that were closed because the source was found
to be outside the AMEL covered process unit.
    7. The operational downtime percentage for each sensor determined
each month.
    8. For each sensor that fails a bump test, identification of the
sensor, date of failed bump test, and corrective action taken.
    9. Any changes to the sensor network, including those resulting
from the compliance assurance actions in IV.E.
    10. For the additional annual compliance demonstration in IV.E:
    a. The date of each EPA Method 21 survey.
    b. The number of valves and pumps monitored.
    c. The number of leaks identified.
    d. The number of non-compliant leakers.
    e. The number of leaks identified above 18,000 ppmv.
    f. Date of each survey conducted in a zone of incomplete coverage,
and for each survey in a zone of incomplete coverage the number of
valves and pumps monitored and the number of leaks identified.
    g. Any corrective action taken if there are non-compliant leakers.
    11. Once the criteria in IV.E(3) is met, a statement that FHR has
met the criteria and additional annual compliance demonstrations are no
longer required.
    12. Reports of deviations recorded under IV.C(15) which occurred in
the semi-annual reporting period, including the date, start time,
duration, description of the deviation, and corrective active.

E. Additional Annual Compliance Demonstration

    In addition to continuous compliance with the LDSN-DRF as required
by the sections IV.A-D, the following annual compliance demonstration
actions are required for the LDSN-DRF system located in the Meta-Xylene
and Mid-Crude process units:

    1. Method 21 of appendix A-7 of part 60 must be conducted in each
process unit equipped with the LDSN-DRF according to the following
requirements:
    a. The first survey must be conducted within 12 calendar months of
implementation of the AMEL in a given process unit.
    Subsequent surveys must be conducted no sooner than 10 calendar
months and no later than 12 calendar months after the preceding survey.
    b. Identify the valves to be monitored as described below.
    Monitor the valves as described in IV.E(1)(b)(i) through (v) or
IV.E(1)(b)(vi) using Method 21 of appendix A-7 of part 60 as specified
in section 60.485a(b) of 40 CFR part 60, subpart VVa, with the
exception that the high scale calibration gas must be 20,000.(+/ -
1000.) ppmv.
    (i) Determine the total number of valves located in the individual
process unit. The minimum number of valves monitored must equal 20
percent of the total population of valves in the process unit.
    (ii) Identify each verification zone on a plot plan. The
verification zone is the area between the radii that are 45 and 50 feet
from each individual sensor. Determine the total number of valves that
occur in only one sensor verification zone (i.e., verification zones
that have no overlap with other verification zones). If the number of
valves that occur in only one sensor verification zone is greater than
the minimum number of valves that must be monitored, monitor a random
selection of these valves according to IV.E(1)(b)(v).
    (iii) If the number of valves that occur in only one sensor
verification zone is less than the minimum number of valves that must
be monitored, determine the total number of valves that occur in all
verification zones, including those that overlap. If the total number
of valves in all verification zones is greater than the minimum number
of valves that must be monitored, monitor all the valves that occur in
only one sensor verification zone. Additionally, monitor a random
selection of valves, chosen in accordance with IV.E(1)(b)(v), that
appear in verification zones that overlap until the 20 percent minimum
is achieved.
    (iv) If the number of valves in all verification zones is less than
20 percent of the total population, then monitor all of the valves in
all verification zones. Additionally, monitor a random sample of
additional valves within the LDSN but outside of the verification
zones, chosen in accordance with IV.E(1)(b)(v), until the 20 percent
minimum is achieved.
    (v) Random sampling of valves. To determine the random selection of
valves to monitor, determine the population of valves that must be
randomly sampled as determined in IV.E(1)(b)(ii), (iii), or (iv) (i.e.,
the total valve population in one sensor verification zone, the total
valve population in verification zones that overlap, or the total valve
population minus the number of valves in the verification zones).
Divide the population of valves by the number of valves that must be
sampled and round to the nearest integer to establish the sampling
interval. Using the valve IDs sequentially, monitor valves at this
sequential interval (e.g., every 5 valves). Alternatively, use the
valve IDs and a random number generator to determine the valves to
monitor. Each survey conducted under IV.E(1)(a) must start on a
different valve ID such that the same population of valves is not
monitored in each survey.
    (vi) In lieu of implementing IV.E(1)(b)(i) through (v), FHR may
elect to monitor 50 percent of the total number of light liquid and gas
vapor (LL/GV) valves that occur within the LDSN coverage area each
year. This shall be done by dividing the valves into 2 sets, with each
set containing every other valve in the given tag range (e.g., all odd
numbered valves in one set and all even numbered valves in the second
set). In the first survey, one set of valves shall be monitored, such
that nominally 50 percent of the valves have been monitored. Each
subsequent survey must rotate between the 2 sets of valves such that
the same population of valves is not monitored during 2 consecutive
surveys.
    c. Monitor each pump located in the process unit using Method 21 of
appendix A-7 of part 60 as specified in section 60.485a(b) of 40 CFR
part 60, subpart VVa.
    d. For purposes of this monitoring, a leak is identified as an
instrument reading above the leak definitions in Table 2 of this AMEL.
    All identified leaks must be repaired or placed on delay of repair
within 15 calendar days of detection, with a first attempt completed
within 5 calendar days of detection.
    e. Once the annual monitoring survey is complete, any components
identified with EPA Method 21 screening values greater than 3,000 ppmv
shall be plotted on a plot plan of the process unit along with all
active PSLs and the locations of each sensor node.
    Any LDAR applicable component that is not in an active PSL or which
was not previously placed on delay of repair, will be considered a NC
leaker if it meets at least one of the specifications in IV.E(1)(e)(i)
or (ii):
    (i) A component identified with an EPA Method 21 screening value
above 3,000 ppmv that is located within 18 feet of any sensor node.
    (ii) A component identified with an EPA Method 21 screening value
above 18,000 ppmv that is located anywhere in the LDSN coverage area.
    f. For each NC leaker, FHR must identify a ZIC. The ZIC shall be
defined as the area with a 15-foot radius horizontally and vertically
around the leaking component.
    Monitoring with Method 21 of appendix A-7 of part 60 shall be
conducted for all LL/GV valves and pumps in the ZIC that were not
already monitored during the most recent annual survey. The leak
definitions in Table 2 shall be used to determine if a leak is
detected. Any identified leaks shall be repaired or placed on delay of
repair per IV.E(1)(d).
    g. All NC leakers shall be deviations of the AMEL and reported as
such. The period of noncompliance shall end when the monitoring under
IV.E(1)(f) has been completed and repairs for all leaking components
have been made and verified or the components have been placed on delay
of repair.
    h. Until the actions in IV.E.(1)(f) are completed, FHR shall
monitor all LL/GV valves and pumps in the ZIC quarterly using Method 21
of appendix A-7 of part 60.
    i. For each NC leaker, FHR shall conduct a root cause analysis
(RCA) to determine the cause of the defect of the sensor network and to
determine appropriate corrective action. The RCA shall begin within 5
days and be completed no later than 45 days after completion of the
most recent annual survey. FHR must submit a corrective action plan
within 15 days of the completion of the RCA to [email protected]. For any
NC leaker with an EPA Method 21 screening value above 18,000 ppmv, the
corrective action plan must include revisions to the sensor network.
Revisions to the sensor network must include the addition of new