[Federal Register Volume 82, Number 198 (Monday, October 16, 2017)]
[Rules and Regulations]
[Pages 48156-48187]
[FR Doc No: 2017-21937]

Vol. 82

Monday,

No. 198

October 16, 2017

Part II

 Environmental Protection Agency

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40 CFR Part 63

 National Emission Standards for Hazardous Air Pollutants: Nutritional
Yeast Manufacturing Residual Risk and Technology Review; Final Rule

Federal Register / Vol. 82 , No. 198 / Monday, October 16, 2017 /
Rules and Regulations

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[EPA-HQ-OAR-2015-0730; FRL-9969-08-OAR]
RIN 2060-AS93

National Emission Standards for Hazardous Air Pollutants:
Nutritional Yeast Manufacturing Residual Risk and Technology Review

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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SUMMARY: This action finalizes the residual risk and technology review
(RTR) conducted for the Manufacturing of Nutritional Yeast source
category regulated under national emission standards for hazardous air
pollutants (NESHAP). In addition, we are finalizing other amendments,
including revisions to the form of the volatile organic compounds (VOC)
standards for fermenters, removal of the option to monitor brew
ethanol, inclusion of ongoing relative accuracy test audit (RATA), and
revisions to other monitoring, reporting, and recordkeeping
requirements.

DATES: This final rule is effective on October 16, 2017. The
incorporation by reference of certain publications listed in the rule
is approved by the Director of the Federal Register as of October 16,
2017.

ADDRESSES: The Environmental Protection Agency (EPA) has established a
docket for this action under Docket ID No. EPA-HQ-OAR-2015-0730. All
documents in the docket are listed on the https://www.regulations.gov
Web site. Although listed in the index, some information is not
publicly available, e.g., confidential business information (CBI) or
other information whose disclosure is restricted by statute. Certain
other material, such as copyrighted material, is not placed on the
Internet and will be publicly available only in hard copy form.
Publicly available docket materials are available either electronically
through https://www.regulations.gov, or in hard copy at the EPA Docket
Center, EPA WJC West Building, Room Number 3334, 1301 Constitution Ave.
NW., Washington, DC. The Public Reading Room hours of operation are
8:30 a.m. to 4:30 p.m. Eastern Standard Time, Monday through Friday,
excluding legal holidays. The telephone number for the Public Reading
Room is<PHONE_NUMBER>, and the telephone number for the EPA Docket
Center is<PHONE_NUMBER>.

FOR FURTHER INFORMATION CONTACT: For questions about this final action,
contact Allison Costa, Sector Policies and Programs Division (Mail Code
E143-03), 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_ADDRESS>For specific information
regarding the risk modeling methodology, contact Chris Sarsony, Health
and Environmental Impacts Division (C539-02), Office of Air Quality
Planning and Standards, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina 27711; telephone number:<PHONE_NUMBER>;
and email address<EMAIL_ADDRESS>For information about the
applicability of the NESHAP to a particular entity, contact John Cox,
Office of Enforcement and Compliance Assurance, U.S. Environmental
Protection Agency, EPA WJC South Building (Mail Code 2227A), 1200
Pennsylvania Ave. NW., Washington, DC 20460; telephone number: (919)
564-1395; and email address<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:
    Preamble acronyms and abbreviations. We use multiple acronyms and
terms in this preamble. While this list may not be exhaustive, to ease
the reading of this preamble and for reference purposes, the EPA
defines the following terms and acronyms here:

BAE Batch-average concentration of brew ethanol in fermenter liquid
BAVOC Batch-average concentration of volatile organic compounds in
fermenter exhaust
CAA Clean Air Act
CDX Central Data Exchange
CEDRI Compliance and Emissions Data Reporting Interface
CEMS Continuous emission monitoring system
CFR Code of Federal Regulations
CPMS Continuous parameter monitoring system
CRA Congressional Review Act
EPA Environmental Protection Agency
ERT Electronic Reporting Tool
FID Flame ionization detector
GC Gas chromatograph
HAP Hazardous air pollutant(s)
HQ Hazard quotient
ICR Information Collection Request
MACT Maximum achievable control technology
NEI National Emissions Inventory
NESHAP National emission standards for hazardous air pollutants
NTTAA National Technology Transfer and Advancement Act
OMB Office of Management and Budget
ppmv Parts per million by volume
PRA Paperwork Reduction Act
RATA Relative accuracy test audit
REL Recommended exposure limit
RFA Regulatory Flexibility Act
RfC Reference concentration
RIN Regulatory Information Number
RTO Regenerative thermal oxidizer
RTR Risk and technology review
SSM Startup, shutdown, and malfunction
THC Total hydrocarbons
TOSHI Target organ-specific hazard index
UMRA Unfunded Mandates Reform Act
URE Unit risk estimate
VOC Volatile organic compound

    Background information. On December 28, 2016, the EPA issued a
proposed rulemaking presenting the results of the RTR of the
Manufacturing of Nutritional Yeast NESHAP, as well as proposing
additional revisions to the NESHAP. In this action, we are finalizing
decisions and revisions for the rule. We summarize some of the more
significant comments we received regarding the proposed rule and
provide our responses in this preamble. A summary of all other public
comments on the proposal and the EPA's responses to those comments is
available in the document titled, ``Nutritional Yeast Manufacturing
Risk and Technology Review: Summary of Public Comments and Responses,''
which is in the docket for this action (Docket ID No. EPA-HQ-OAR-2015-
0730). A ``track changes'' version of the regulatory language that
incorporates the changes in this action is also available in the
docket.
    Organization of this document. The information in this preamble is
organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document and other related
information?
    C. Judicial Review and Administrative Reconsideration
II. Background
    A. What is the statutory authority for this action?
    B. What is the Manufacturing of Nutritional Yeast source
category and how does the NESHAP regulate HAP emissions from this
source category?
    C. What changes did we propose for the Manufacturing of
Nutritional Yeast source category in our December 28, 2016,
proposal?
III. What is included in this final rule?
    A. What are the final rule amendments based on the risk review
for the Manufacturing of Nutritional Yeast source category?
    B. What are the final rule amendments based on the technology
review for the Manufacturing of Nutritional Yeast source category?
    C. What are the final rule amendments addressing emissions
during periods of startup, shutdown, and malfunction?
    D. What other changes have been made to the NESHAP?
    E. What are the effective and compliance dates of the standards?

    F. What are the requirements for submission of performance test
data to the EPA?
IV. What is the rationale for our final decisions and amendments for
the Manufacturing of Nutritional Yeast source category?
    A. Residual Risk Review for the Manufacturing of Nutritional
Yeast Source Category
    B. Technology Review for the Manufacturing of Nutritional Yeast
Source Category
    C. Revised Form of the Fermenter VOC Standard
    D. Removal of the Option To Monitor Brew Ethanol
    E. Requirement To Conduct RATA
    F. Requirement To Collect All Valid CEMS Data
    G. Compliance Dates for the Amendments
V. Summary of Cost, Environmental, and Economic Impacts and
Additional Analyses Conducted
    A. What are the affected facilities?
    B. What are the air quality impacts?
    C. What are the cost impacts?
    D. What are the economic impacts?
    E. What are the benefits?
    F. What analysis of environmental justice did we conduct?
    G. What analysis of children's environmental health did we
conduct?
VI. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
    B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs
    C. Paperwork Reduction Act (PRA)
    D. Regulatory Flexibility Act (RFA)
    E. Unfunded Mandates Reform Act (UMRA)
    F. Executive Order 13132: Federalism
    G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
    H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
    I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use
    J. National Technology Transfer and Advancement Act (NTTAA) and
1 CFR Part 51
    K. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
    L. Congressional Review Act (CRA)

I. General Information

A. Does this action apply to me?

    Regulated entities. Categories and entities potentially regulated
by this action are shown in Table 1 of this preamble.

 Table 1--NESHAP and Industrial Source Categories Affected by This Final
                                 Action
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                                                               NAICS \1\
                 NESHAP and Source Category                      Code
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Manufacturing of Nutritional Yeast..........................     311999
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\1\ North American Industry Classification System.

    Table 1 of this preamble is not intended to be exhaustive, but
rather to provide a guide for readers regarding entities likely to be
affected by the final action for the source category listed. To
determine whether your facility is affected, you should examine the
applicability criteria in the final Manufacturing of Nutritional Yeast
NESHAP (40 CFR part 63, subpart CCCC). If you have any questions
regarding the applicability of any aspect of this NESHAP, which we
refer to as ``subpart CCCC'' in this preamble, please contact the
appropriate person listed in the preceding FOR FURTHER INFORMATION
CONTACT section of this preamble.

B. Where can I get a copy of this document and other related
information?

    In addition to being available in the docket, an electronic copy of
this final action will also be available on the Internet. Following
signature by the EPA Administrator, the EPA will post a copy of this
final action at: https://www.epa.gov/stationary-sources-air-pollution/manufacturing-nutritional-yeast-national-emission-standards. Following
publication in the Federal Register, the EPA will post the Federal
Register version and key technical documents at this same Web site.
    Additional information is available on the RTR Web site at https://www3.epa.gov/ttn/atw/rrisk/rtrpg.html. This information includes an
overview of the RTR program, links to project Web sites for the RTR
source categories, and detailed emissions and other data we used as
inputs to the risk assessments.

C. Judicial Review and Administrative Reconsideration

    Under Clean Air Act (CAA) section 307(b)(1), judicial review of
this final action is available only by filing a petition for review in
the United States Court of Appeals for the District of Columbia by
December 15, 2017. Under CAA section 307(b)(2), the requirements
established by this final rule may not be challenged separately in any
civil or criminal proceedings brought by the EPA to enforce the
requirements.
    Section 307(d)(7)(B) of the CAA further provides that only an
objection to a rule or procedure which was raised with reasonable
specificity during the period for public comment (including any public
hearing) may be raised during judicial review. This section also
provides a mechanism for the EPA to reconsider the rule if the person
raising an objection can demonstrate to the Administrator that it was
impracticable to raise such objection within the period for public
comment or if the grounds for such objection arose after the period for
public comment (but within the time specified for judicial review) and
if such objection is of central relevance to the outcome of the rule.
Any person seeking to make such a demonstration should submit a
Petition for Reconsideration to the Office of the Administrator, U.S.
EPA, Room 3000, EPA WJC South Building, 1200 Pennsylvania Ave. NW.,
Washington, DC 20460, with a copy to both the person(s) listed in the
preceding FOR FURTHER INFORMATION CONTACT section, and the Associate
General Counsel for the Air and Radiation Law Office, Office of General
Counsel (Mail Code 2344A), U.S. EPA, 1200 Pennsylvania Ave. NW.,
Washington, DC 20460.

II. Background

A. What is the statutory authority for this action?

    Section 112 of the CAA establishes a two-stage regulatory process
to address emissions of hazardous air pollutants (HAP) from stationary
sources. In the first stage, we must identify categories of sources
emitting one or more of the HAP listed in CAA section 112(b) and then
promulgate technology-based NESHAP for those sources. ``Major sources''
are those that emit, or have the potential to emit, any single HAP at a
rate of 10 tons per year (tpy) or more, or 25 tpy or more of any
combination of HAP. For major sources, these standards are commonly
referred to as maximum achievable control technology (MACT) standards
and must reflect the maximum degree of emission reductions of HAP
achievable (after considering cost, energy requirements, and non-air
quality health and environmental impacts). In developing MACT
standards, CAA section 112(d)(2) directs the EPA to consider the
application of measures, processes, methods, systems, or techniques,
including but not limited to those that reduce the volume of or
eliminate HAP emissions through process changes, substitution of
materials, or other modifications; enclose systems or processes to
eliminate emissions; collect, capture, or

treat HAP when released from a process, stack, storage, or fugitive
emissions point; are design, equipment, work practice, or operational
standards; or any combination of the above.
    For these MACT standards, the statute specifies certain minimum
stringency requirements, which are referred to as MACT floor
requirements, and which may not be based on cost considerations. See
CAA section 112(d)(3). For new sources, the MACT floor cannot be less
stringent than the emission control achieved in practice by the best-
controlled similar source. The MACT standards for existing sources can
be less stringent than floors for new sources, but they cannot be less
stringent than the average emission limitation achieved by the best-
performing 12 percent of existing sources in the category or
subcategory (or the best-performing five sources for categories or
subcategories with fewer than 30 sources). In developing MACT
standards, we must also consider control options that are more
stringent than the floor under CAA section 112(d)(2). We may establish
standards more stringent than the floor, based on the consideration of
the cost of achieving the emissions reductions, any non-air quality
health and environmental impacts, and energy requirements.
    In the second stage of the regulatory process, the CAA requires the
EPA to undertake two different analyses, which we refer to as the
technology review and the residual risk review. Under the technology
review, we must review the technology-based standards and revise them
``as necessary (taking into account developments in practices,
processes, and control technologies)'' no less frequently than every 8
years, pursuant to CAA section 112(d)(6). Under the residual risk
review, we must evaluate the risk to public health remaining after
application of the technology-based standards and revise the standards,
if necessary, to provide an ample margin of safety to protect public
health or to prevent, taking into consideration costs, energy, safety,
and other relevant factors, an adverse environmental effect. The
residual risk review is required within 8 years after promulgation of
the technology-based standards, pursuant to CAA section 112(f). In
conducting the residual risk review, if the EPA determines that the
current standards provide an ample margin of safety to protect public
health, it is not necessary to revise the MACT standards pursuant to
CAA section 112(f).\1\ For more information on the statutory authority
for this rule, see the proposal published on December 28, 2016 (81 FR
95810).
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    \1\ The U.S. Court of Appeals for the District of Columbia
Circuit has affirmed this approach of implementing CAA section
112(f)(2)(A): NRDC v. EPA, 529 F.3d 1077, 1083 (D.C. Cir. 2008)
(``If EPA determines that the existing technology-based standards
provide an 'ample margin of safety,' then the Agency is free to
readopt those standards during the residual risk rulemaking.'').
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B. What is the Manufacturing of Nutritional Yeast source category and
how does the NESHAP regulate HAP emissions from this source category?

    The EPA promulgated the Manufacturing of Nutritional Yeast NESHAP
on May 21, 2001 (66 FR 27876). The standards are codified at 40 CFR
part 63, subpart CCCC. The manufacturing of nutritional yeast industry
consists of facilities that manufacture yeast for the purpose of
becoming an ingredient in dough for bread or any other yeast-raised
baked product, or for becoming a nutritional food additive intended for
consumption by humans. Facilities that manufacture nutritional yeast
intended for consumption by animals, such as an additive for livestock
feed, are not included in the description of sources covered by this
subpart in 40 CFR 63.2131. In addition, subpart CCCC clarifies that
fermenters are not subject to emission limitations during the
production of specialty yeast (e.g., yeast for use in wine, champagne,
whiskey, or beer) in 40 CFR 63.2132. The source category was originally
defined as Baker's Yeast Manufacturing in 1992, but was renamed
Manufacturing of Nutritional Yeast in 1998 to clarify the scope of the
source category. See the preamble for the proposed rule for additional
background (81 FR 95814, December 28, 2016). The source category
covered by subpart CCCC currently includes four facilities.
    The affected sources at nutritional yeast manufacturing facilities
are the collection of equipment used to manufacture Saccharomyces
cerevisiae yeast, including fermenters. The subpart CCCC emission
limitations apply to the final three stages of the fermentation
process, which are often referred to as stock (third-to-last stage),
first generation (second-to-last stage), and trade (last stage)
fermentation.
    Currently, the fermenters are subject to batch-average VOC (BAVOC)
emission limitations that differ for each fermentation stage, and which
must be met for 98 percent of all batches in each fermentation stage on
a rolling 12-month basis. The measurement of VOC is used as a surrogate
for the HAP of interest, acetaldehyde. The BAVOC limits are 300 parts
per million by volume (ppmv) for stock fermenters (third-to-last
stage), 200 ppmv for first generation fermenters (second-to-last
stage), and 100 ppmv for trade fermenters (last stage).
    In the original subpart CCCC requirements, facilities can
continuously monitor either the VOC concentration in the fermenter
exhaust or the brew ethanol concentration in the fermenter liquid to
determine compliance with the emission limitations. If a facility
monitors brew ethanol concentration, it must conduct an annual
performance test to determine the correlation between the brew ethanol
concentration in the fermenter liquid and the VOC concentration in the
fermenter exhaust gas.

C. What changes did we propose for the Manufacturing of Nutritional
Yeast source category in our December 28, 2016, proposal?

    On December 28, 2016, the EPA published a proposed rule in the
Federal Register for subpart CCCC, that address the results of the RTR
analyses and proposed other amendments. In the action, we proposed
finding that the risks from the Manufacturing of Nutritional Yeast
source category are acceptable; that additional emissions controls for
the source category are not necessary to provide an ample margin of
safety; and that there have been no developments in practices,
processes, and control technologies that warrant changes to the
fermenter emission limitations. Additionally, we proposed several
changes to the existing rule (apart from the RTR process) that were
intended to promote consistency with relevant statutory requirements
and goals. These changes included revising the form of the VOC
standards for fermenters; removing the option to monitor brew ethanol;
including requirements to conduct annual RATA; removing gas
chromatograph (GC) continuous emission monitoring system (CEMS) as an
option to monitor VOC concentration; collecting CEMS data at all times
during the batch monitoring period; using Procedure 1 of Appendix F to
part 60 for VOC CEMS; requiring electronic reporting; and revising
startup, shutdown, and malfunction (SSM) provisions.

III. What is included in this final rule?

    This action finalizes the EPA's determinations pursuant to the RTR
provisions of CAA section 112 for the Manufacturing of Nutritional
Yeast source category. This action also finalizes other changes to
subpart CCCC, including: Revising the form of the VOC standards for
fermenters; removing the

option to monitor brew ethanol; including requirements to conduct
ongoing RATA; using Procedure 1 of Appendix F to part 60 for VOC CEMS;
removing GC CEMS as an option to monitor VOC concentration; collecting
CEMS data at all times during the batch monitoring period; requiring
electronic reporting; and revising SSM provisions.

A. What are the final rule amendments based on the risk review for the
Manufacturing of Nutritional Yeast source category?

    The EPA proposed no changes to subpart CCCC based on the risk
review conducted pursuant to CAA section 112(f). Specifically, as we
proposed, we are finalizing our determination that risks from the
nutritional yeast manufacturing facilities are acceptable, and that the
standards provide an ample margin of safety to protect public health.
The EPA received no new data or other information during the public
comment period that changed that determination. Therefore, we are not
requiring additional controls under CAA section 112(f)(2).

B. What are the final rule amendments based on the technology review
for the Manufacturing of Nutritional Yeast source category?

    We determined that there are no developments in practices,
processes, and control technologies that warrant revisions to the MACT
standards for this source category. The EPA proposed no changes to
subpart CCCC based on the technology review conducted pursuant to CAA
section 112(d)(6). The EPA received no new data or other information
during the public comment period that affected the technology review
determination. Therefore, we are not finalizing revisions to the MACT
standards under CAA section 112(d)(6).

C. What are the final rule amendments addressing emissions during
periods of startup, shutdown, and malfunction?

    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008), the United States Court of Appeals for the District of
Columbia Circuit vacated portions of two provisions in the EPA's CAA
section 112 regulations governing the emissions of HAP during periods
of SSM. Specifically, the Court vacated the SSM exemptions contained in
40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), holding that under section
302(k) of the CAA, emissions standards or limitations must be
continuous in nature and that the SSM exemption violates the CAA's
requirement that some CAA section 112 standard apply continuously.
    Consistent with Sierra Club v. EPA, the EPA has established
standards in this rule that apply at all times. We have eliminated the
malfunction exemption in this rule, in addition to making other changes
to ensure that the rule's emission limitations apply continuously (the
latter changes are addressed in sections III.D and IV.C of this
preamble). While, for simplicity, we refer throughout this section to
the SSM exemption and the associated SSM plan requirements, only the
malfunction exemption and its removal are relevant to this action
because periods of startup and shutdown were never exempt from
emissions standards in this subpart. We have revised Table 6 to subpart
CCCC (the General Provisions applicability table) in several respects
as is explained in more detail below. For example, we have eliminated
the incorporation of the General Provisions' requirement that the
source develops an SSM plan. We have also eliminated and revised
certain recordkeeping and reporting that is related to the SSM
exemption as described in detail in the proposed rule and summarized
again here.
    In establishing the standards in this rule, the EPA has taken into
account startup and shutdown periods and, for the reasons explained
below, has not established alternate standards for those periods.
Periods of startup, normal operations, and shutdown are all predictable
and routine aspects of a source's operations. In this NESHAP, owners or
operators of nutritional yeast manufacturing facilities employ process
controls to limit emissions. These process controls are employed from
the time a fermenter starts production of a batch of yeast and continue
until the fermenter is emptied of yeast. Additionally, emissions are
averaged over the entire duration of each batch in order to determine
compliance with emission limitations, so there was no need to set
separate limits for periods of startup and shutdown in this rule.
    Malfunctions, in contrast, are neither predictable nor routine.
Instead they are by definition sudden, infrequent, and not reasonably
preventable failures of emissions control, process, or monitoring
equipment. 40 CFR 63.2 (definition of malfunction). The EPA interprets
CAA section 112 as not requiring emissions that occur during periods of
malfunction to be factored into development of CAA section 112
standards and this reading has been upheld as reasonable by the D.C.
Circuit. U.S. Sugar Corp. v. EPA, 830 F.3d 579, 606-610 (2016).
Instead, under CAA section 112, emissions standards for new sources
must be no less stringent than the level ``achieved'' by the best
controlled similar source and for existing sources generally must be no
less stringent than the average emission limitation ``achieved'' by the
best performing 12 percent of sources in the category. There is nothing
in CAA section 112 that directs the Agency to consider malfunctions in
determining the level ``achieved'' by the best performing sources when
setting emission standards. As the D.C. Circuit has recognized, the
phrase ``average emissions limitation achieved by the best performing
12 percent of '' sources ``says nothing about how the performance of
the best units is to be calculated.'' Nat'l Ass'n of Clean Water
Agencies v. EPA, 734 F.3d 1115, 1141 (D.C. Cir. 2013). While the EPA
accounts for variability in setting emissions standards, nothing in CAA
section 112 requires the Agency to consider malfunctions as part of
that analysis. A malfunction should not be treated in the same manner
as the type of variation in performance that occurs during routine
operations of a source. A malfunction is a failure of the source to
perform in a ``normal or usual manner'' and no statutory language
compels the EPA to consider such events in setting CAA section 112
standards. As the D.C. Circuit recognized in U.S. Sugar Corp,
accounting for malfunctions in setting emission standards would be
difficult, if not impossible, given the myriad different types of
malfunctions that can occur across all sources in the category and
given the difficulties associated with predicting or accounting for the
frequency, degree, and duration of various malfunctions that might
occur. Id. at 608 (``the EPA would have to conceive of a standard that
could apply equally to the wide range of possible boiler malfunctions,
ranging from an explosion to minor mechanical defects. Any possible
standard is likely to be hopelessly generic to govern such a wide array
of circumstances.'') As such, the performance of units that are
malfunctioning is not ``reasonably'' foreseeable. See, e.g., Sierra
Club v. EPA, 167 F.3d 658, 662 (D.C. Cir. 1999) (``The EPA typically
has wide latitude in determining the extent of data-gathering necessary
to solve a problem. We generally defer to an agency's decision to
proceed on the basis of imperfect scientific information, rather than
to `invest the resources to conduct the perfect study.' '') See also,
Weyerhaeuser v. Costle, 590 F.2d 1011, 1058 (D.C. Cir. 1978) (``In the
nature of things, no general limit, individual permit, or even any
upset provision can anticipate all upset situations. After a certain
point, the transgression of

regulatory limits caused by `uncontrollable acts of third parties,'
such as strikes, sabotage, operator intoxication or insanity, and a
variety of other eventualities, must be a matter for the administrative
exercise of case-by-case enforcement discretion, not for specification
in advance by regulation.''). In addition, emissions during a
malfunction event can be significantly higher than emissions at any
other time of source operation. For example, if an air pollution
control device with 99-percent removal goes off-line as a result of a
malfunction (as might happen if, for example, the bags in a baghouse
catch fire) and the emission unit is a steady state type unit that
would take days to shut down, the source would go from 99-percent
control to zero control until the control device was repaired. The
source's emissions during the malfunction would be 100 times higher
than during normal operations. As such, the emissions over a 4-day
malfunction period would exceed the annual emissions of the source
during normal operations. As this example illustrates, accounting for
malfunctions could lead to standards that are not reflective of (and
significantly less stringent than) levels that are achieved by a well-
performing non-malfunctioning source. It is reasonable to interpret CAA
section 112 to avoid such a result. The EPA's approach to malfunctions
is consistent with CAA section 112 and is a reasonable interpretation
of the statute.
    In subpart CCCC, it is unlikely that a malfunction would result in
a violation of the standards for fermenters. The rule provides an
option for owners or operators to determine the average VOC
concentration for all batches within each fermentation stage using data
from 12-month periods. This option limits the effect of malfunctions on
the ability of a facility to meet the emission limitations because the
averaging effectively minimizes ``spikes'' in emissions. Additionally,
many of the common malfunctions reported during EPA site visits by
owners or operators of nutritional yeast manufacturing facilities were
malfunctions of the emissions monitoring equipment. While the equipment
is unable to record accurate data during periods of malfunction, it
does not impact actual emissions because process controls could still
be used to limit emissions. In the unlikely event that a source fails
to comply with the applicable CAA section 112(d) standards as a result
of a malfunction event, the EPA would determine an appropriate response
based on, among other things, the good faith efforts of the source to
minimize emissions during malfunction periods, including preventative
and corrective actions, as well as root cause analyses to ascertain and
rectify excess emissions. The EPA would also consider whether the
source's failure to comply with the CAA section 112(d) standard was, in
fact, sudden, infrequent, not reasonably preventable and not instead
caused in part by poor maintenance or careless operation. 40 CFR 63.2
(definition of malfunction).
    If the EPA determines in a particular case that an enforcement
action against a source for violation of an emission standard is
warranted, the source can raise any and all defenses in that
enforcement action and the federal district court will determine what,
if any, relief is appropriate. The same is true for citizen enforcement
actions. Similarly, the presiding officer in an administrative
proceeding can consider any defense raised and determine whether
administrative penalties are appropriate.
    In summary, the EPA interpretation of the CAA and, in particular,
CAA section 112 is reasonable and encourages practices that will avoid
malfunctions. Administrative and judicial procedures for addressing
exceedances of the standards fully recognize that violations may occur
despite good faith efforts to comply and can accommodate those
situations. U.S. Sugar Corp. v. EPA, 830 F.3d 579, 606-610 (D.C. Cir.
2016).
1. 40 CFR 63.2150 General Duty
    We are revising the General Provisions table (Table 6 to subpart
CCCC) entry for 40 CFR 63.6(e)(1)(i) to specify that 40 CFR
63.6(e)(1)(i) does not apply to subpart CCCC. Section 63.6(e)(1)(i)
describes the general duty to minimize emissions. Some of the language
in that section is no longer necessary or appropriate in light of the
elimination of the SSM exemption. The current language in 40 CFR
63.6(e)(1)(i) characterizes what the general duty entails during
periods of SSM; with the elimination of the SSM exemption, there is no
need to differentiate between normal operations, startup and shutdown,
and malfunction events in describing the general duty. Therefore, we
are adding instead general duty regulatory text at 40 CFR 63.2150(d)
that reflects the general duty to minimize emissions while eliminating
the reference to periods covered by an SSM exemption.
    We are also revising the General Provisions table (Table 6 to
subpart CCCC) entry for 40 CFR 63.6(e)(1)(ii) to specify that 40 CFR
63.6(e)(1)(ii) does not apply to subpart CCCC. Section 63.6(e)(1)(ii)
imposes requirements that are not necessary with the elimination of the
SSM exemption or are redundant with the general duty requirement being
added at 40 CFR 63.2150.
2. SSM Plan
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.6(e)(3) does not apply to subpart CCCC.
Generally, these paragraphs require development of an SSM plan and
specify SSM recordkeeping and reporting requirements related to the SSM
plan. As noted, the EPA is removing the SSM exemptions. Therefore,
affected units will be subject to an emission standard during such
events. The applicability of a standard during such events will ensure
that sources have ample incentive to plan for and achieve compliance
and, thus, the SSM plan requirements are no longer necessary.
3. Compliance With Standards
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.6(f)(1) does not apply to subpart CCCC.
The current language of 40 CFR 63.6(f)(1) exempts sources from non-
opacity standards during periods of SSM. As discussed above, the Court
in Sierra Club vacated the exemptions contained in this provision and
held that the CAA requires that some CAA section 112 standard apply
continuously. Consistent with Sierra Club, the EPA is revising
standards in this rule to apply at all times.
4. 40 CFR 63.2161 Performance Testing
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.7(e)(1) does not apply to subpart CCCC.
Section 63.7(e)(1) describes performance testing requirements. The EPA
is instead adding a performance testing requirement at 40 CFR
63.2161(b). The performance testing requirements we are adding differ
from the General Provisions performance testing provisions in several
respects. The regulatory text does not include the language in 40 CFR
63.7(e)(1) that restated the SSM exemption and language that precluded
startup and shutdown periods from being considered ``representative''
for purposes of performance testing. As in 40 CFR 63.7(e)(1),
performance tests conducted under this subpart should not be conducted
during malfunctions because conditions during malfunctions are often
not representative of normal

operating conditions. The EPA is adding language in 63.2161(b) that
requires the owner or operator to record the process information that
is necessary to document operating conditions during the test and
include in such record an explanation to support that such conditions
represent normal operation. Section 63.7(e) requires that the owner or
operator make available to the Administrator such records ``as may be
necessary to determine the condition of the performance test''
available to the Administrator upon request, but does not specifically
require the information to be recorded. The regulatory text the EPA is
adding to subpart CCCC builds on that requirement and makes explicit
the requirement to record the information.
5. Monitoring
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.8 (c)(1)(i) and (iii) do not apply to
subpart CCCC. The cross-references to the general duty and SSM plan
requirements in those subparagraphs are not necessary in light of other
requirements of 40 CFR 63.8 that require good air pollution control
practices (40 CFR 63.8(c)(1)) and that set out the requirements of a
quality control program for monitoring equipment (40 CFR 63.8(d)).
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.8(d)(3) does not apply to subpart CCCC.
The final sentence in 40 CFR 63.8(d)(3) refers to the General
Provisions' SSM plan requirement which is no longer applicable. The EPA
is adding to the rule at 40 CFR 63.2182(c)(3) and 63.2183(e) text that
contains the same requirements as 40 CFR 63.8(d)(3), except that we are
requiring the program of corrective action for a malfunctioning
monitoring system to be included in the quality control program for a
CEMS (as described in 40 CFR 63.8(d)(2)) instead of in the SSM plan.
6. 40 CFR 63.2182 Recordkeeping
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.10(b)(2)(ii) does not apply to subpart
CCCC. Section 63.10(b)(2)(ii) describes the recordkeeping requirements
during a malfunction. The EPA is adding such requirements to 40 CFR
63.2182(a)(2) and (c)(5). The regulatory text we are adding differs
from the text in the General Provisions it is replacing in that the
General Provisions requires the creation and retention of a record of
the occurrence and duration of each malfunction of process, air
pollution control, and monitoring equipment. The EPA is now applying
the recordkeeping requirement to any failure to meet an applicable
standard and is requiring that the source record the date, time, and
duration of the failure rather than the ``occurrence.'' The EPA is also
adding to 40 CFR 63.2182(a)(2) and (c)(5) a requirement that sources
keep records that include a list of the affected source or equipment
and actions taken to minimize emissions, an estimate of the quantity of
each regulated pollutant emitted over the standard for which the source
failed to meet the standard, and a description of the method used to
estimate the emissions. Examples of such methods would include product-
loss calculations, mass balance calculations, measurements when
available, or engineering judgment based on known process parameters.
The EPA is requiring that sources keep records of this information to
ensure that there is adequate information to allow the EPA to determine
the severity of any failure to meet a standard, and to provide data
that may document how the source met the general duty to minimize
emissions when the source has failed to meet an applicable standard.
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.10(b)(2)(iv) does not apply to subpart
CCCC. When applicable, the provision requires sources to record actions
taken during SSM events when actions were inconsistent with their SSM
plan. The requirement is no longer appropriate because SSM plans will
no longer be required. The requirement previously applicable under 40
CFR 63.10(b)(2)(iv)(B) to record actions to minimize emissions and
record corrective actions is now specified at 40 CFR 63.2182(a)(2) and
(c)(5).
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.10(b)(2)(v) does not apply to subpart
CCCC. When applicable, the provision requires sources to record actions
taken during SSM events to show that actions taken were consistent with
their SSM plan. The requirement is no longer appropriate because SSM
plans will no longer be required.
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.10(c)(15) does not apply to subpart
CCCC. The provision allows an owner or operator to use the affected
source's SSM plan or records kept to satisfy the recordkeeping
requirements of the SSM plan to also satisfy the requirements of 40 CFR
63.10(c)(10) through (12) concerning additional recordkeeping
requirements for sources with continuous monitoring systems. The EPA is
eliminating this requirement because SSM plans will no longer be
required, and, therefore, 40 CFR 63.10(c)(15) no longer serves any
useful purpose for affected units.
7. 40 CFR 63.2181 Reporting
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.10(d)(5) does not apply to subpart
CCCC. Section 63.10(d)(5) describes the reporting requirements for
startups, shutdowns, and malfunctions. To replace the General
Provisions reporting requirement, the EPA is adding reporting
requirements to 40 CFR 63.2181(c)(5) and (7). The replacement language
differs from the General Provisions requirement in that it eliminates
periodic SSM reports as stand-alone reports. We are promulgating
language that requires sources that fail to meet an applicable standard
at any time to report the information concerning such events in the
semiannual compliance report already required under this rule in 40 CFR
63.2181. We are requiring that the report must contain the number,
date, time, duration, and the cause of such events (including unknown
cause, if applicable), a list of the affected source or equipment, an
estimate of the quantity of each regulated pollutant emitted over any
emission limitation, and a description of the method used to estimate
the emissions. Examples of such methods would include product-loss
calculations, mass balance calculations, measurements when available,
or engineering judgment based on known process parameters. The EPA is
promulgating this requirement to ensure that there is adequate
information to determine compliance, to allow the EPA to determine the
severity of the failure to meet an applicable standard, and to provide
data that may document how the source met the general duty to minimize
emissions during a failure to meet an applicable standard.
    We will no longer require owners or operators to determine whether
actions taken to correct a malfunction are consistent with an SSM plan,
because plans will no longer be required. The final amendments,
therefore, eliminate the cross reference to 40 CFR 63.10(d)(5)(i) that
contains the description of the previously required SSM report format
and submittal schedule from this section. These specifications are no
longer necessary

because the events will be reported in otherwise required reports with
similar format and submittal requirements.
    We are revising the General Provisions table (Table 6 to subpart
CCCC) to specify that 40 CFR 63.10(d)(5)(ii) does not apply to subpart
CCCC. Section 63.10(d)(5)(ii) describes an immediate report for
startups, shutdown, and malfunctions when a source failed to meet an
applicable standard, but did not follow the SSM plan. We will no longer
require owners or operators to report when actions taken during a
startup, shutdown, or malfunction were not consistent with an SSM plan,
because such plans will no longer be required.

D. What other changes have been made to the NESHAP?

    This rule finalizes revisions to several other Manufacturing of
Nutritional Yeast NESHAP requirements. We describe the revisions in the
following paragraphs.
    We are finalizing the proposed amendments to revise the form of the
fermenter VOC limits that require facilities to demonstrate compliance
using either the Average Option or Batch Option. In response to
comments, we are allowing facilities up to 1 year to demonstrate
compliance with the revised form of the emission limitations. The EPA
originally proposed that facilities would have to demonstrate
compliance immediately upon promulgation of the final rule.
    We are also finalizing the proposed amendments to several testing,
monitoring, recordkeeping, and reporting provisions. First, we are
finalizing amendments to require all facilities to monitor VOC
emissions using VOC CEMS and to remove the option to monitor brew
ethanol in the fermenter liquid and determine an annual correlation to
VOC concentration in the fermenter exhaust in order to demonstrate
compliance with fermenter VOC emission limitations. In reponse to
comments, we are allowing the affected facility up to 3 years to comply
with these requirements. The EPA originally proposed that the affected
facility would have 1 year to comply with these requirements. We are
also finalizing the related revisions to the rule text that corrected
references to ``brew ethanol monitors'' that had erroneously referred
to CEMS.
    Second, we are finalizing the proposed amendments to remove the
option to use GC CEMS to monitor VOC emissions. The use of GC CEMS
requires facilities to identify specific VOC species to monitor and no
facilities are currently using this method.
    Third, we are finalizing the proposed amendments to require the
collection of all valid CEMS data during batch monitoring periods and
the reporting of missing data as deviations. In response to comments,
we have added clarifying language in the rule specifying a minimum CEMS
cycle time of 15 minutes and allowing a minimum of two data points
(representing 15-minute periods) to constitute a valid hour of data
collection during periods of calibration, quality assurance, or
maintenance activities; and modified the recordkeeping requirements
accordingly (as stated in the General Provisions).
    Fourth, we are finalizing the proposed amendments to require
facilities to conduct regular RATA using Procedure 1 of Appendix F to
part 60 to evaluate the ongoing performance of CEMS. In response to
comments, we are requiring RATA to be conducted once every 3 years,
instead of annually as proposed. We are also adding language to the
rule to clarify that cylinder gas audits or relative accuracy audits
must be conducted in the quarters that RATA are not conducted,
consistent with the requirements of Procedure 1 of Appendix F to part
60.
    To increase the ease and efficiency of data submittal and data
accessibility, we are finalizing, as proposed, a requirement that
owners or operators of nutritional yeast manufacturing facilities
submit electronic copies of certain required performance test or
evaluation reports through the EPA's Central Data Exchange (CDX) Web
site using the Electronic Reporting Tool (ERT). This requirement to
submit performance test data or performance evaluation information
electronically to the EPA applies only to those performance tests or
evaluations conducted using test methods or evaluations that are
supported by the ERT.
    Lastly, we are finalizing the proposed minor language changes
throughout subpart CCCC that clarify the existing requirements and
restate the requirements in active voice. These amendments do not
change any existing requirements, but are intended to improve the
readability of subpart CCCC.

E. What are the effective and compliance dates of the standards?

    The revisions to the MACT standards being promulgated in this
action are effective on October 16, 2017.
    The compliance date for the removal of GC CEMS, collection of all
valid CEMS data from the entire batch monitoring period, requirement to
conduct RATA, use of Procedure 1 of Appendix F to part 60 for VOC CEMS,
revised SSM requirements, and the electronic reporting requirements for
nutritional yeast manufacturing facilities is October 16, 2017.
    Existing facilities must comply with the revised form of the
fermenter VOC emission limitations by October 16, 2018. Until October
16, 2018, facilities must continue to demonstrate compliance, either
using the existing form of the fermenter VOC emission limitations or
the revised form of the fermenter VOC limits, in their semiannual
compliance reports. As discussed in section IV.G of this preamble, this
timeframe was revised from immediate compliance in the proposed rule,
based on public comments, in order to allow facilities time to train
staff and update the necessary recordkeeping and reporting procedures.
    Facilities that currently demonstrate compliance by monitoring brew
ethanol concentration in the fermenter liquid must install CEMS by
October 16, 2020. Until October 16, 2020, emissions data must be
collected for each batch, either using the existing compliance method
(monitoring brew ethanol concentration) or with CEMS, for use in the
semiannual compliance reports with the applicable emission limitations.
As discussed in section IV.G of this preamble, this was revised from
the proposed 1-year compliance period, based on public comments, to
allow facilities adequate time to procure equipment; train staff; and
update operations and maintenance, recordkeeping, and reporting
procedures.
    Sources that are constructed or reconstructed after promulgation of
the rule revisions must comply with the emission limitations and
compliance requirements upon the effective date of the rule, October
16, 2017, or upon startup of the affected source, whichever is later.

F. What are the requirements for submission of performance test data to
the EPA?

    The EPA is requiring owners or operators of manufacturing of
nutritional yeast facilities to submit electronic copies of certain
required performance test reports and performance evaluation reports
(e.g., RATAs that are supported by the EPA's ERT) at the time of the
evaluation, through the EPA's CDX using the Compliance and Emissions
Data Reporting Interface (CEDRI). The electronic submittal will
increase the usefulness of the data contained in those reports, is in
keeping with current

trends in data availability and transparency, will further assist in
the protection of public health and the environment, will improve
compliance by facilitating the ability of regulated facilities to
demonstrate compliance with requirements and by facilitating the
ability of delegated state, local, tribal, and territorial air agencies
and the EPA to assess and determine compliance, and will ultimately
reduce burden on regulated facilities, delegated air agencies, and the
EPA. Electronic reporting also eliminates paper-based, manual
processes, thereby saving time and resources, simplifying data entry,
eliminating redundancies, minimizing data reporting errors, and
providing data quickly and accurately to the affected facilities, air
agencies, the EPA, and the public.
    The EPA Web site that stores the submitted electronic data,
WebFIRE, provides a user-friendly interface accessible to all
stakeholders. By making the records, data, and reports addressed in
this rulemaking readily available, the EPA, the regulated community,
and the public will benefit when the EPA conducts its CAA-required
technology and risk-based reviews. As a result of having reports
readily accessible, our ability to carry out comprehensive reviews will
be increased and achieved within a shorter period of time.
    We anticipate fewer or less substantial Information Collection
Requests (ICRs) in conjunction with prospective CAA-required technology
and risk-based reviews may be needed as a result of electronic
reporting, which results in a decrease in time spent by industry to
respond to data collection requests. We also expect the ICRs to contain
less extensive stack testing provisions, as we will already have stack
test data electronically. Reduced testing requirements would be a cost
savings to industry. The EPA should also be able to conduct these
required reviews more quickly. Although the regulated community may
benefit from a reduced burden of ICRs, the general public benefits from
the Agency's ability to provide these required reviews more quickly,
resulting in increased public health and environmental protection.
    Air agencies, as well as the EPA, can benefit from more streamlined
and automated review of the electronically submitted data.
Standardizing report formats allows air agencies to review reports and
data more quickly. Having reports and associated data in electronic
format will facilitate review through the use of software ``search''
options, as well as the downloading and analyzing of data in
spreadsheet format. Additionally, air agencies and the EPA can access
reports wherever and whenever they want or need, as long as they have
access to the Internet. The ability to access and review reports
electronically assists air agencies in determining compliance with
applicable regulations more quickly and accurately, potentially
allowing a faster response to violations which could minimize harmful
air emissions. This benefits both air agencies and the general public.
    For a more thorough discussion of electronic reporting required by
this rule, see the discussion in the preamble of the proposal (81 FR
95829, December 28, 2016). In summary, in addition to supporting
regulation development, control strategy development, and other air
pollution control activities, having an electronic database populated
with performance test data will save industry, air agencies, and the
EPA significant time, money, and effort while improving the quality of
emission inventories and air quality regulations, and enhancing the
public's access to this important information.

IV. What is the rationale for our final decisions and amendments for
the Manufacturing of Nutritional Yeast source category?

    For each issue, this section provides a description of what we
proposed and what we are finalizing, the EPA's rationale for the final
decisions and amendments, and a summary of key comments and responses.
For all comments not discussed in this preamble, comment summaries and
the EPA's responses can be found in the comment summary and response
document available in the docket for this rulemaking (EPA-HQ-OAR-2015-
0730).

A. Residual Risk Review for the Manufacturing of Nutritional Yeast
Source Category

1. What did we propose pursuant to CAA section 112(f) for the
Manufacturing of Nutritional Yeast source category?
    Pursuant to CAA section 112(f), the EPA conducted a residual risk
review and presented the results of this review, along with our
proposed decisions regarding risk acceptability and ample margin of
safety, in the December 28, 2016, proposed rule for subpart CCCC (81 FR
95825). The results of the risk assessment for the proposal are
presented briefly below in Table 2 of this preamble, and in more detail
in the proposal residual risk document, ``Residual Risk Assessment for
the Manufacturing of Nutritional Yeast Source Category in Support of
the December 2016 Risk and Technology Review Proposed Rule,'' which is
available in the docket for this rulemaking.

                                                           Table 2--Nutritional Yeast Manufacturing Inhalation Risk Assessment Results
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                             Maximum individual cancer    Estimated population at     Estimated annual cancer   Maximum chronic non-cancer        Maximum screening acute non-cancer HQ \4\
                             risk  (in 1 million) \2\    increased risk of cancer   incidence (cases per year)           TOSHI \3\         -----------------------------------------------------
                           ----------------------------      >= 1-in-1 million     --------------------------------------------------------
                                                       ----------------------------
 Number of facilities \1\     Based on      Based on      Based on      Based on      Based on      Based on      Based on      Based on    Based on actual emissions      Based on allowable
                               actual       allowable      actual       allowable      actual       allowable      actual       allowable           level \2\               emissions level
                              emissions     emissions     emissions     emissions     emissions     emissions     emissions     emissions
                              level \2\       level       level \2\       level       level \2\       level       level \2\       level
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
4.........................            2             2           750           750        0.0009        0.0009          0.08          0.08   HQREL = 0.2..............  HQREL = 0.2.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Number of facilities evaluated in the risk analysis.
\2\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\3\ Maximum target organ-specific hazard index (TOSHI). The target organ with the highest TOSHI for the Manufacturing of Nutritional Yeast source category is the respiratory system.
\4\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of hazard quotient (HQ) values. HQ values shown use the lowest
  available acute threshold value, which in most cases is the recommended exposure limit (REL). When HQ values exceed 1, we also show HQ values using the next lowest available acute dose-
  response value. See section III.A.3 of the proposal preamble (81 FR 95816, December 28, 2016) for explanation of acute dose-response values.

    Based on both actual and allowable emissions for the Manufacturing
of Nutritional Yeast source category, the maximum lifetime individual
cancer risk was estimated to be up to 2-in-1 million, the maximum
chronic non-cancer TOSHI value was estimated to be up to 0.08, and the
maximum off-facility site acute HQ value was estimated to be up to 0.2.
The total estimated national cancer incidence from these facilities was
0.0009 excess cancer cases per year or 1 case in every 1,100 years.
    There are no persistent and bioaccumulative HAP emitted by
facilities in this source category. Therefore, we did not consider any
human health multi-pathway risks as a result of emissions from this
source category.
    We weighed all health risk factors, including those shown in Table
2 of this preamble, in our risk acceptability determination, and
proposed that the residual risks from the Manufacturing of Nutritional
Yeast source category are acceptable (section IV.B. of proposal
preamble, 81 FR 95825, December 28, 2016).
    We then considered whether subpart CCCC provides an ample margin of
safety to protect public health and prevents, taking into consideration
costs, energy, safety, and other relevant factors, an adverse
environmental effect. In considering whether the standards should be
tightened to provide an ample margin of safety to protect public
health, we considered the same risk factors that we considered for our
acceptability determination and also considered the costs,
technological feasibility, and other relevant factors related to
emissions control options that might reduce risk associated with
emissions from the source category. Two control options were evaluated
for further reducing acetaldehyde emissions from fermenters at
nutritional yeast facilities: thermal oxidizers and wet (packed bed)
scrubbers. Due to the additional environmental impacts (increased
energy use and emissions of approximately 89 tpy of nitrogen oxides
that would be imposed by the control options and the low level of
current human health risk), along with the substantial costs associated
with these control options, we proposed that additional emissions
controls for this source category are not necessary to provide an ample
margin of safety (section IV.B.2 of proposal preamble, 81 FR 95825,
December 28, 2016).
    In addition, none of the seven pollutants identified by the EPA as
``environmental HAP'' (cadmium, dioxins/furans, polycyclic organic
matter, mercury, lead compounds, hydrogen chloride, and hydrogen
fluoride), which are known to cause adverse environmental effects, are
emitted; therefore, we did not conduct a separate environmental risk
analysis for this source category (see section III.A.6 of the proposal
preamble (81 FR 95819, December 28, 2016)).
2. How did the risk review change for the Manufacturing of Nutritional
Yeast source category?
    During the public comment period, the EPA received information that
the acetaldehyde emissions rate was tested at the AB Mauri facility in
2017 and was approximately 50 percent lower than the rate used to
estimate the total annual emissions included in the residual risk
analysis. The residual risk analysis performed for the proposed rule
was based on data reported in the 2011 National Emissions Inventory
(NEI) from all facilities. The new emissions rate cannot be used to
change previously reported data from a facility because there is no
clear evidence or test history to establish when the emission rate
decreased. Complete 2017 emissions data is not yet available for AB
Mauri, so the EPA could not repeat the risk analysis using newer data
for this facility. Importantly, the risk review had already found that
the risks are acceptable and the standards provide an ample margin of
safety using the higher 2011 NEI emissions data for this facility, so
it is possible that the residual risk from the Manufacturing of
Nutritional Yeast source category has decreased even farther. Since the
EPA concluded it was reasonable to not update the risk review following
proposal, we have finalized the risk assessment report and re-submitted
it to the docket as ``Residual Risk Assessment for the Manufacturing of
Nutritional Yeast Source Category in Support of the October, 2017 Risk
and Technology Review Final Rule.''
3. What key comments did we receive on the risk review and what are our
responses?
    We received comments in support of and against the proposed
residual risk review and our determination that no revisions were
warranted under CAA section 112(f)(2). Generally, the comments that
were not supportive of the determination from the risk review suggested
changes to the underlying risk assessment methodology. After review of
these comments, we determined that no changes were necessary. The
comments and our specific responses can be found in the document,
``Nutritional Yeast Manufacturing Risk and Technology Review: Summary
of Public Comments and Responses,'' which is available in the docket
for this action.
4. What is the rationale for our final approach and final decisions for
the risk review?
    For the reasons explained in the proposed rule, we determined that
the risks from the Manufacturing of Nutritional Yeast source category
are acceptable, and the current standards provide an ample margin of
safety to protect public health and prevent an adverse environmental
effect. Since proposal, neither the risk assessment nor our
determinations regarding risk acceptability, ample margin of safety, or
adverse environmental effects have changed. Therefore, we are not
revising subpart CCCC to require additional controls pursuant to CAA
section 112(f)(2) based on the residual risk review and are readopting
the existing standards under CAA section 112(f)(2).

B. Technology Review for the Manufacturing of Nutritional Yeast Source
Category

1. What did we propose pursuant to CAA section 112(d)(6) for the
Manufacturing of Nutritional Yeast source category?
    Pursuant to CAA section 112(d)(6), the EPA conducted a technology
review and summarized the results of the review in the proposed rule
for subpart CCCC (81 FR 95825, December 28, 2016). The results of the
technology review are briefly discussed below, and in more detail in
the memorandum, ``Technology Review for the Manufacturing of
Nutritional Yeast Source Category,'' which is available in the docket
for this action (Docket ID No. EPA-HQ-OAR-2015-0730-0016).
    The technology review focused on identifying and evaluating
developments in practices, processes, and control technologies for the
Manufacturing of Nutritional Yeast source category. We identified two
control technologies for further evaluation that were technically
feasible for further reducing acetaldehyde emissions from nutritional
yeast fermenters: thermal oxidizers, and wet (packed bed) scrubbers.
After identifying the control technologies that were technically
feasible, we then evaluated the costs and emissions reductions
associated with installing regenerative thermal oxidizers (RTOs) and
packed bed scrubbers at each of the four existing nutritional yeast
facilities. Considering the high cost per ton of acetaldehyde reduced
and potential adverse environmental impacts

associated with the installation of RTOs or packed bed scrubbers, we
did not consider these technologies to be cost effective for further
reducing acetaldehyde emissions from fermenters at nutritional yeast
manufacturing facilities. In light of the results of the technology
review, we proposed to conclude that changes to the fermenter emission
limitations were not warranted pursuant to CAA section 112(d)(6) (81 FR
95825, December 28, 2016).
2. How did the technology review change for the Manufacturing of
Nutritional Yeast source category?
    The technology review for the Manufacturing of Nutritional Yeast
source category has not changed since proposal. As proposed, the EPA is
not making changes to the standards pursuant to CAA section 112(d)(6).
3. What key comments did we receive on the technology review and what
are our responses?
    We received comments in support of the proposed determination from
the technology review that no revisions were warranted under CAA
section 112(d)(6). We also received one comment that asserted that cost
effectiveness should not be a consideration when examining standards
under CAA section 112(d)(6). We evaluated the comments and determined
that no changes regarding our determination were needed. These comments
and our specific responses to those comments can be found in the
comment summary and response document titled, ``Nutritional Yeast
Manufacturing Risk and Technology Review: Summary of Public Comments
and Responses,'' which is available in the docket for this action.
4. What is the rationale for our final approach for the technology
review?
    For the reasons explained in the preamble to the proposed rule, we
determined there were no new developments in practices or processes,
nor were cost-effective control technologies available to further
reduce acetaldehyde emissions from fermenters at nutritional yeast
manufacturing facilities (81 FR 95825, December 28, 2016). Since
proposal, neither the technology review nor our determination as a
result of the technology review has changed, and we are not revising
subpart CCCC pursuant to CAA section 112(d)(6).

C. Revised Form of the Fermenter VOC Standard

1. What did we propose?
    At proposal, the EPA explained that the current form of the
standards for VOC limits on fermenters was in direct conflict with the
statutory requirement that emission standards limit emissions on a
continuous basis, i.e., that some emission limitation applies at all
times, and, therefore, proposed to establish a revised form of the
standards (``Batch Option'') as well as an alternate standard for
compliance (``Average Option'') in Table 1 to subpart CCCC (81 FR
95826, December 28, 2016). Under the proposed Batch Option, each
individual batch manufactured must meet the existing VOC emission
limits (300 ppmv for stock fermentation, 200 ppmv for first generation
fermentation, and 100 ppmv for trade fermentation). Under the proposed
Average Option, all batch average VOC concentration data for each
fermentation stage in a 12-month period must be averaged together and
not exceed certain VOC emission limits, which are 5 percent lower than
the VOC emission limits established for individual batches in 2001 for
subpart CCCC (285 ppmv for stock fermentation, 190 ppmv for first
generation fermentation, and 95 ppmv for trade fermentation). We
referred to this reduction as a ``discount factor,'' consistent with
our use of the term in other MACT standards that allow averaging of
emissions data for compliance.
    Additionally, the proposed revisions to the general compliance
requirements in 40 CFR 63.2150(a) and (c) that remove the exemption for
compliance with emission limits during periods of malfunction will also
impact the determination of compliance with emission limits. The
practical effect of this change is that emissions from batches of yeast
produced during periods of malfunction, other than monitoring system
malfunctions, must now be included in calculations for compliance
purposes.
2. How did the requirements change since proposal?
    The EPA has not changed either the form or the level of emission
reductions that would be required under either the Batch or Average
Option. We have, however, revised our characterization of which option
represents the updated form of the original MACT standard and which can
be used as the alternative compliance method, as described in section
IV.C.3 of this preamble.
3. What key comments did we receive and what are our responses?
    Comment: Two commenters stated that the EPA improperly assumed a
need to change the fermenter VOC standards based on the Sierra Club v.
EPA SSM policy ruling that standards must apply at all times. One
commenter asserted that the EPA is confusing the concept of continuous
compliance as opposed to relief from compliance. Both commenters
remarked that the existing fermenter VOC standards apply at all times
and the facility must be in continuous compliance with the standard,
meaning that VOC concentration must be continuously monitored to ensure
that 98 percent of all batches do not exceed the VOC standards. A
commenter also stated that yeast manufacturers do continuously comply
with the existing fermenter VOC standards, as calculated under the
statistical averaging approach set out in the standard. The commenter
continued that the Sierra Club v. EPA SSM ruling did not say that
calculations embedded into MACT standards must be invalidated under the
logic the Court used to invalidate the EPA's general SSM policy.
    The commenter stated that other Court decisions addressing the
EPA's SSM policy similarly have no bearing on the Nutritional Yeast
rule. For example, the commenter remarked that in NRDC v. EPA, the
Court invalidated the affirmative defense provision of the Cement Kiln
NESHAP that excused Portland cement manufacturers if they experienced a
process malfunction. The commenter stated the Nutritional Yeast rule
does not provide any affirmative defense for non-compliance.
    Response: We disagree that the changes to the form of the standard
are unwarranted and that the Sierra Club v. EPA decision is
inapplicable in this context because we disagree with the commenters'
characterization of the existing form of the standard as an emission
limitation that applies at all times. A standard that allows up to 2
percent of batches to be produced without any applicable limitation on
emissions does not provide continuous emission reductions within the
meanings of CAA sections 112 and 302(k).
    The existing form of the standard is inconsistent with the D.C.
Circuit's holding that CAA sections 112 and 302(k), when read together,
require that emission standards apply on a continuous basis, and we are
remedying that inconsistency here. See Sierra Club v. EPA, 551 F.3d at
1027. While the Court was specifically addressing SSM

requirements in that case, its analysis was based on CAA section
302(k)'s requirement that emission standards, including those required
under CAA section 112(d)(2) and (3), ``assure continuous emission
reduction.'' Id. The Court discussed the legislative history of CAA
section 302(k), noting that ``the committee has made clear that
constant or continuous means of reducing emissions must be used to meet
these requirements. By the same token, intermittent or supplemental
controls or other temporary, periodic, or limited systems of control
would not be permitted as a final means of compliance.'' Id. (quoting
H.R. Rep. 95-294, at 92 (1977)). The Court's disposition of the SSM
issue was based on its determination that CAA section 302(k) does not
allow the EPA ``to relax emission standards on a temporal basis.'' Id.
at 1028 (citing NRDC v. EPA, 489 F.3d at 1364, 1374 (D.C. Cir. 2007)).
That same analysis--that some emission standard must provide emission
reductions at all times--is directly applicable to the emission
standard at issue here. The existing MACT standard for yeast
manufacturing allows up to 2 percent of batches to be produced without
any kind of emission reduction requirement, which is in direct conflict
with CAA section 302(k) and Sierra Club v. EPA.
    We disagree with the commenter's overly narrow interpretation of
Sierra Club v. EPA as applying only to SSM exemptions, as it ignores
the underlying determination that such exemptions are illegal because
they are inconsistent with the requirement that emission reductions
must be continuous. The existing form of the standard for yeast
manufacturing creates a limited or intermittent system of control. The
fact that this exemption was originally built into the standard does
not excuse its fundamental inconsistency with the statutory
requirements. We also disagree that we are confusing continuous
compliance with relief from compliance; again, the issue is broader
than just whether sources must comply continuously with a standard--it
is also, according to the D.C. Circuit's analysis, whether that
standard provides continuous emission reductions.
    The EPA acknowledges and understands that, in the current standard,
nutritional yeast facilities continuously monitor VOC concentration
during each batch. This is done both to monitor emissions for
compliance purposes and also because facilities use the data for
process control. However, continuous monitoring is not equivalent to
having a continuous emission standard when the continuous monitoring is
not accompanied by an emission reduction requirement. Critically,
facilities may currently exceed the VOC standards for up to 2 percent
of batches and these batches are allowed to emit an unlimited amount of
HAP and VOC emissions. The revised forms of the standards, be it the
Batch or Average Option, require that all monitored batch data are
included to determine compliance, which ensures that the standards do
not provide allowances for some batches of yeast to emit an unlimited
amount of HAP and VOC emissions.
    The EPA also notes that nutritional yeast facilities make hundreds
to thousands of batches of yeast within a 12-month period; therefore,
the 2-percent exemption allows a significant number of batches to
exceed the limits. For example, if there are 1,000 batches during a 12-
month period, up to 20 batches may operate without emission limits.
Again, there is no cap on their emissions and no penalty for these
exceedances, regardless of how much they exceed the emission limit or
the cause of the excursion. This ``time out'' from application of the
emission standard is inconsistent with the requirement that such
standards provide for continuous emission reductions.
    Relatedly, we further clarify that, separate from updating the form
of the standard so that an emission limitation applies to all batches
(i.e., continuously), we are also removing cross-references to sections
of the General Provisions that allow for exemptions from compliance
during periods of malfunction. These are two separate issues in the
context of this rulemaking, both of which were precipitated by the
Sierra Club v. EPA decision, as explained above. While removal of the
malfunction exemption means that owners or operators of nutritional
yeast manufacturing facilities must include data from every batch when
determining whether they have complied with the standard, this does not
preclude the EPA from appropriately addressing noncompliance when it
results from emissions that occur during periods of malfunction as
defined in 40 CFR 63.2, which is discussed in section III.C of this
preamble.
    We did not include affirmative defense language in the nutritional
yeast proposal and did not consider it for the rule revisions. Thus, we
agree that the NRDC v. EPA decision is not relevant to the revisions to
the form of the standards.
    Comment: Two commenters stated that allowing up to 2 percent of
batches to exceed the fermenter VOC emission limits is inherent in the
standards to account for the natural variability of the yeast
manufacturing process. One commenter remarked that changing the
fermenter VOC standards would be to reject the EPA's prior
determination that the standards needed to reflect the actual
functioning of the yeast fermentation process.
    Response: The EPA disagrees that an exemption from emission
limitations is the only option to address variability within a
standard. There are other options for addressing variability besides
raising the level of the standard. One such option is to express the
emission limitation as the average of emissions from all batches. Our
proposed Average Option, where a facility may average BAVOC emissions
from all batches within a given fermentation stage together within a
12-month period, provides flexibility for individual batches to emit
both below and above the prescribed numerical limits. Therefore, we
disagree that changing the form of the standard rejects the EPA's prior
determination that the standards needed to reflect the actual
functioning of the yeast fermentation process.
    Comment: Two commenters stated that the Average Option could be
adopted if no discount factor were applied because the Average Option
accounts for variability within the yeast manufacturing process. One of
the commenters does not support the 5-percent discount factor that is
part of the Average Option and suggested the EPA would be required to
re-open the MACT standard and revisit the administrative record that it
established in 2001 in order to justify such a change.
    Response: To address the requirement that the emission standards
must provide for continuous emission reductions, the EPA proposed to
change the current emissions standards in subpart CCCC that allow 2
percent of the batches to be exempted from the otherwise applicable
emission limitation. The EPA proposed that the ``Batch Option'' would
be the updated form of the MACT standard and would set emission limits
for different fermentation stages by simply eliminating the exemption
from the otherwise applicable emission limitation for up to 2 percent
of batches. However, we now recognize that requiring 100 percent of
batches to meet the original emission limitations, as opposed to 98
percent, is not what we determined to be MACT in the 2001 rulemaking.
That rulemaking acknowledged that there is a degree of

natural variance in the yeast fermentation process, such that the
maximum degree of emissions reduction achievable is the level
represented by 98 percent of batches meeting the applicable emission
limits (66 FR 27880, May 21, 2001). Therefore, while we are retaining
the Batch Option as an alternative compliance option, it does not
represent MACT.
    The EPA also proposed the Average Option for determining compliance
with the applicable emission limitations. Because we formulated this
option to reflect the level of emission reductions represented by the
original MACT standard, including the allowance for variability built
into that standard, we are now determining that it is the Average
Option that actually represents MACT. As the commenters acknowledge,
assessing compliance based on a 12-month rolling average of batch
emissions serves the same purpose of addressing batch variability as
the 2-percent exemption. We applied a discount factor specifically
because averaging multiple batches inherently provides more flexibility
to emit above such limits. We have also used discount factors in
conjunction with annual average emission limitations in the Boiler
MACT, where a 10-percent discount was applied for emissions averaging.
Allowing annual average BAVOC emissions to meet the original VOC
concentration limits established as MACT in 2001 (i.e., applying a 0-
percent discount factor) would actually relax the standard, both due to
the inherent flexibility of an averaging method and by potentially
allowing more than 2 percent of batches to exceed the emission
limitations set for each fermentation stage. To ensure that the annual
averaging method will maintain the level of emission reductions
represented by MACT, the EPA is finalizing a 5-percent discount factor
in the VOC emission limit for each fermentation stage, as described in
detail in the memorandum titled, ``Average Option Analysis for the
Manufacturing of Nutritional Yeast Source Category,'' available in the
docket for this rulemaking. The EPA believes that it is necessary to
include both components of the Average Option, as the 12-month rolling
average provides for a degree of flexibility to account for the natural
variance in the manufacturing process, while the 5-percent discount
factor maintains the level of emission reductions consistent with the
MACT determination, which is the level of emission reductions that
protect public health and prevent adverse effects on the environment.
    As discussed previously in this section, the changes to the form of
the standard were precipitated by the D.C. Circuit's 2008 ruling in
Sierra Club v. EPA that some emission standard must apply at all times.
551 F.3d 1019, 1027-28 (D.C. Cir. 2008). We did not re-open the MACT
calculation in this rulemaking; the revised form must continue to
reflect the emission reductions achieved by the best performers as
determined in the 2001 rule. The Average Option as finalized meets
these requirements.
    Comment: One commenter stated the EPA did not offer sufficient
technical support to justify that the proposed fermenter VOC emission
limits are merely a change in the ``form of the standards'' and not a
change in the standards themselves. The commenter contended that the
revised fermenter VOC standards are not equivalent to the existing
standards and there is no legal or technical basis for any changes to
the existing fermenter VOC standards. In addition, the commenter
maintained the proposed revisions fundamentally alter the standards,
and their stringency, by changing the formula used to assess whether
facilities are in compliance.
    Response: The EPA disagrees that there is no legal basis for
changing the form of the standard and that our revision to the form of
the standard fundamentally alters the standard itself. As discussed
previously in this section, we have not recalculated the MACT floor or
revisited the MACT determination; however, we have revised the current
form of the standard consistent with the D.C. Circuit's Sierra Club v.
EPA decision. It is not possible, strictly speaking, to demonstrate
that the revised form of the standard is ``equivalent to'' the existing
form of the standard because changing the form necessarily makes a
direct comparison between the current standard and the revised standard
infeasible. However, when revising the form, we have taken a reasonable
approach to make the MACT standard apply continuously and to ensure
that the revised form remains consistent with the level of emission
reductions we originally determined to represent the MACT standard.
That is, we have attempted to ensure, to the extent possible, that
changing the form of the standard does not fundamentally alter the MACT
standard that was finalized in 2001.
    The Average Option was developed to maintain flexibility for the
sources subject to the rule and is expected to maintain the level of
emission reductions represented by the existing MACT standard. To
support an alternate form of emission limitations that would allow for
emissions averaging and would also represent the existing MACT
standard, we considered information from the development of the
original MACT standard and analyzed more recent emissions data from the
facilities currently subject to this rule. Multiple years of individual
BAVOC emissions data were available for two facilities. Summary BAVOC
data were available for three facilities. A detailed description of the
analysis of the Average Option is available in the memorandum,
``Average Option Analysis for the Manufacturing of Nutritional Yeast
Source Category,'' which is available in the docket for this
rulemaking.
    With the revision of the form of the MACT standard, we retained
certain characteristics of the 2001 standard (e.g., rolling 12-month
calculation periods) to reduce the changes to ongoing operations and
reporting and recordkeeping procedures for affected sources. We
determined that an annual averaging method was the most appropriate
form to maintain the flexibility established in the 2001 MACT standard
to account for the variability in emissions and retain elements of the
reporting and recordkeeping provisions. We concluded, based on
available data, that we could use a normal (bell-curve) distribution to
simulate emissions from the yeast manufacturing process for the
purposes of establishing annual average emission limits.
    The 2001 MACT standard did not set the annual mean for the
distribution of BAVOC concentrations at 300 ppmv, 200 ppmv, and 100
ppmv for each of the last three fermentation stages, respectively.
Rather, it established an upper threshold that no more than 2 percent
of individual batches could exceed. As described in greater in the
memorandum, the emission limitations established under the annual
averaging compliance method will necessarily be lower than the upper
threshold established for the 98 percent of batches with individual
batch emission limitations under the 2001 MACT standard because the
limitations established under the annual averaging method represent the
mean of a normal distribution instead of an upper threshold.
    The simulated distribution depends on two parameters--mean and
standard deviation. Because the mean and discount factor are directly
related, we utilized the standard deviation as the key parameter for
determining the discount factor that would maintain both flexibility
for process variability and the level of emission reduction

established in the 2001 MACT standard. To do this we used the available
BAVOC data from two facilities to calculate the standard deviation for
12-month rolling averages (65 total for each fermentation stage). The
lowest observed standard deviations for each fermentation stage were 7
ppmv for the third-to-last stage, 5 ppmv for the second-to-last stage,
and 3 ppmv for the last stage of yeast manufacturing. Utilizing the
least-variable 12-month period to determine the average emission
limitation results in the lowest discount factor and gives facilities
the ability to operate at the highest annual average emission limit.
Applying these standard deviations results in discount factors of 5
percent for the third-to-last and second-to-last stage, and 6 percent
for the last stage. Instead of selecting different discount factors for
each stage, we determined that a 5-percent discount factor was
appropriate to apply to the 2001 VOC concentration limitations to
express the existing MACT standard in a new form.
    In summary, the Average Option uses an annual averaging methodology
to achieve the flexibility originally accomplished by allowing 2
percent of batches to exceed the established emission limits (300 ppmv,
200 ppmv, 100 ppmv). The revised form of the standard sets annual
average emission limitations that are 5 percent lower than the 2001
upper threshold emission limitations for individual batches to maintain
the level of emission reductions represented by the original form of
the MACT standard.
    Comment: Two commenters asserted the EPA determined that only 98
percent of batches could reasonably be expected to meet the emission
limits and, thus, this was the MACT floor (66 FR 27880, May 21, 2001).
One of the commenters also contended that if the 2001 fermenter VOC
standards had been computed based on all batches, rather than 98
percent of the batches, the standards would necessarily have been set
higher to accommodate process variability or some type of emissions
averaging.
    Response: We agree that in setting the MACT floor in 2001, the EPA
concluded that MACT is the control of 98 percent of the batches to
either at or below the VOC concentration limits. However, we disagree
that changing the form of the standard rejects our acknowledgment of
the actual functioning of the yeast fermentation process or, as
discussed previously in this section, the EPA's prior MACT floor
determination. The updated form of the standard, as expressed in the
``Average Option,'' maintains the level of emission reductions
represented by MACT. This is a change from the proposal, which
presented the ``Batch Option'' as the updated form of MACT. For further
discussion of the determination of the Average Option as MACT, see the
prior response in this section.
    The EPA disagrees that if the 2-percent exemption were not included
in the original MACT limits, the standards would necessarily have been
set higher. The numerical emission limits included in the MACT standard
were not set based on the actual emissions levels achieved by 98
percent of the batches produced; rather they relied on the existing
concentration-based limits included in two state rules, the state of
Wisconsin and the state of Maryland, that were based on reasonably
available control technology (RACT) and that were in place at the time
(66 FR 27879, May 21, 2001). However, some states applied discretion
concerning the number of exceedances of those emission limits that
could occur before finding a facility in violation of the standards.
For example, the state of Maryland's continuous emissions monitoring
policy allowed for one VOC concentration limit exceedance per facility
per quarter. Consistent with this policy, the EPA calculated the
average number of exceedances as a percent of the total number of
batches manufactured at the five facilities subject to RACT or RACT-
derived limitations during 1998 and calculated the overall average
exceedances (based on dividing the average number of exceedances for
the facilities by the average number of runs (where a run is a
fermentation of any stage) for the facilities) to be 1.3 percent,
noting that one of the facilities reported an unusually high number of
exceedances due to ``shakedown'' (testing) of a new fermenter. Notably,
one of the five yeast manufacturing facilities analyzed exceeded no
concentration limits (66 FR 27880, May 21, 2001). Given that one of the
facilities did not exceed the limits, that Maryland only allowed four
batches to exceed the limits each year, and that the average number of
exceedances calculated using data from a facility with an ``unusually
high number of exceedances'' was only 1.3 percent; as well as the
statements from a commenter during promulgation of the MACT floor that
``most batches display BAVOC below the . . . limits'' (66 FR 27880, May
21, 2001), we disagree that the limits would ``necessarily have been
set higher'' as the commenter contends.
    Comment: One commenter stated the Batch Option would never be
preferred from a compliance standpoint to the Average Option, and,
thus, considered the inclusion of the Batch Option as an alternative to
be illusory.
    Response: We acknowledge the comment. However, the EPA does not
support or prefer one option over another (i.e., the Batch Option
versus the Average Option). As explained above, while the EPA
considered the Batch Option to be the revised form of the MACT standard
at proposal, in light of comments received, we have determined that the
Average Option is the revised form of the MACT standard. In recognition
of information gathered from the development of the original rule and
during the site visits conducted for the RTR that some facilities may
be able to meet the current emission limits for all batches
manufactured during a year, we have retained the Batch Option as an
alternative compliance option that offers a more streamlined approach
to determining and reporting compliance.
4. What is the rationale for our final approach?
    For the reasons explained in the preamble to the proposed rule (81
FR 95826, December 28, 2016) and in our comment responses in section
IV.C.3 of this preamble, we are finalizing revisions to the form of the
fermenter VOC standards in Tables 1 and 7 to subpart CCCC. As noted
above, since proposal, the EPA's determination of which option, the
Batch Option or the Average Option, is the revised form of the original
MACT standard has changed, and we now find that the Average Option
represents MACT. However, we are finalizing both of the revised forms
of the standard with no changes to the standards themselves, and are
also finalizing the requirement that all sources must comply with one
of the two revised forms with the changes related to frequency
described in section IV.C.2 of this preamble. Additionally, we are
finalizing revisions to 40 CFR 63.2150 to remove the emission
limitation exemption during periods of malfunction, with the result
that emissions from batches produced during periods of malfunction,
other than monitoring system malfunctions, must now be included in
calculations for compliance purposes.

D. Removal of the Option To Monitor Brew Ethanol

1. What did we propose?
    The EPA proposed to remove one of two options for demonstrating
ongoing compliance in the 2001 rule, which allowed facilities to
monitor brew ethanol concentration in the fermenter liquid.
Specifically, we proposed to revise the requirements of 40 CFR

63.2166 and 63.2171, and Tables 3 and 4 to subpart CCCC to remove the
option to monitor brew ethanol as a means of demonstrating compliance.
The method for monitoring brew ethanol requires facilities to develop
an annual correlation of brew ethanol concentration to VOC
concentration in the fermenter exhaust and use the correlation to
determine compliance with the emission limitations. This method does
not account for batch-specific characteristics affecting emissions and
we subsequently determined it to be an unreliable indicator of a
facility's compliance with the standard. A detailed discussion is
available in the preamble to the proposed rule (81 FR 95827, December
28, 2016) and the supporting analysis is presented in the memorandum,
``Brew Ethanol Correlation Review for the Manufacturing of Nutritional
Yeast Source Category Memo Correction,'' which is available in the
docket for this action (Docket ID No. EPA-HQ-OAR-2015-0730-0181). We
proposed to require facilities that monitor brew ethanol to adopt the
remaining compliance demonstration option, which involves the
installation and use of CEMS to monitor VOC emissions directly in the
fermenter exhaust.
2. How did the requirements change since proposal?
    The EPA is making no changes to the removal of the option to
demonstrate compliance by monitoring brew ethanol in the fermenter
liquid and is finalizing this amendment as proposed. However, as
explained in section IV.G of this preamble, in response to public
comments, the EPA has allowed 2 additional years for facilities to
comply with this amendment in addition to the 1 year that was proposed.
3. What key comments did we receive and what are our responses?
    Comment: One commenter challenged the EPA's technical analysis
supporting the proposed removal of the option to monitor brew ethanol
as a method to demonstrate compliance with emission limitations, and
claimed that the analysis was fundamentally flawed and misleading. The
commenter disagreed with the EPA's finding that brew ethanol monitoring
resulted in a high level of inconsistency in the amount of VOC
emissions estimated for a particular brew ethanol concentration and
requested that brew ethanol monitoring be retained as a valid
parametric CEMS. The commenter also suggested that the EPA erred by
using ``hypothetical'' VOC concentrations instead of the actual batch-
average concentration values of brew ethanol in the fermenter liquid
(BAE) from one of the performance tests to demonstrate the potential
for emission limitation exceedances.
    The commenter provided a report that analyzed brew ethanol
correlation performance tests from 2007 through 2016 (see EPA-HQ-OAR-
2015-0730-0191-A2). The report presented the conclusion that the
combined 10 years (2007-2016) of performance test data demonstrated
that when using the actual BAE and maximum BAE results for each
fermentation stage over the 10-year period and applying the results to
each year's linear regression analysis, there was not a single year
where the facility would have exceeded the prescribed VOC emission
limitations for the tested batches. Furthermore, the commenter stated
that even when using the highest BAE observed during one of the
performance tests over the last 10 years and applying the most
unfavorable linear regression analysis from those 10 years, there was
no potential for the facility to have exceeded the corresponding VOC
emission limitations.
    Response: The commenter has provided no evidence to dispute the
EPA's central conclusion that the calculated brew ethanol linear
regression equations demonstrate an unacceptable level of variability.
The EPA's decision to disallow the brew ethanol monitoring option rests
on this conclusion. The analysis of ``higher end'' brew ethanol
concentrations, which the EPA believes remains reasonable (as discussed
below), was utilized to illustrate the effect of relying on the highly
variable brew ethanol linear regressions on compliance, and is not the
primary support for the EPA's decision to discontinue the brew ethanol
monitoring option.
    The core point of the EPA's analysis is that the level of VOCs
emitted for a given percentage of brew ethanol measured in a fermenter
is different for every batch that was tested in a given fermentation
stage between 2012 and 2016. The additional data submitted by the
commenter for the years 2007 through 2011 further support this finding.
Depending on which of the 10 performance test batches is evaluated, the
BAVOC value that would be calculated for a BAE value of 0.14 from a
batch manufactured in the third-to-last stage ranged from as low as 76
ppmv to as high as 207 ppmv. Similar results were reported for the
second-to-last and last fermentation stages. Our analysis of the
variability is provided in the memorandum titled, ``Brew Ethanol
Correlation Review for the Manufacturing of Nutritional Yeast Source
Category--Final Rule,'' which has been updated with the additional data
submitted by the commenter and is available in the docket for this
rulemaking.
    For many batches produced over the course of a year, the
variability between annual correlation equations will not affect the
facility's compliance status because the batches are well under the
established emission limitations for each of the correlation equations.
However, for those batches with higher brew ethanol concentrations, the
variability may have a significant impact on the resulting BAVOC value
calculated for those batches and the overall compliance status of the
yeast manufacturing facility, depending on the overall percentage of
batches with higher BAE values.
    For the purposes of estimating emissions, the current method does
not provide reliable information about the thousands of batches that
are not tested, other than showing whether emissions are rising or
falling. In order for the existing correlation method to be useful for
compliance purposes, it is necessary that the relationship between BAE
and BAVOC be relatively constant between batches for a given
fermentation stage, regardless of the point-in-time in which they were
tested. The manufacturing of yeast is a biological process and some
degree of variation is expected. However, emissions are also determined
by a few key process parameters, including the amount of available
oxygen and the composition and amount of the sugar and nutrient mixture
fed to the yeast in each batch. The review of the data in the
memorandum titled, ``Brew Ethanol Correlation Review for the
Manufacturing of Nutritional Yeast Source Category--Final Rule,'' which
is available in the docket for this rulemaking, shows that the
relationship between brew ethanol concentration and VOC emissions is
affected by some combination of these or other process parameters since
the correlation is not constant for each tested batch and each
fermentation stage. The inconsistent correlations suggest that the
brew-to-exhaust correlation method does not yield reliable emissions
information for batches of yeast other than those specific batches used
for the annual performance tests.
    The EPA disagrees that the use of sample VOC concentrations other
than the BAE values measured during a performance test with the
corresponding correlation equation to assess the brew ethanol
correlation method is misleading. Rather, this is the process

laid out in the rule for the facility to determine compliance with the
emission limitations. Each year, the facility is required to test only
three individual batches (one from each fermentation stage) out of the
thousands of batches that are manufactured during the year. The
facility then estimates BAVOC values for the thousands of other batches
using the correlations obtained during the performance tests that year.
The EPA analyzed 5 years of actual BAVOC values recorded by the
facility and used the corresponding year's correlation equations to
calculate a BAE value for every batch manufactured during those 5
years. The ``higher end'' values used in the memorandum, ``Brew Ethanol
Correlation Review for the Manufacturing of Nutritional Yeast Source
Category--Final Rule'' were all within the ranges of actual BAE values
measured during the corresponding years by the facility. The commenter
also stated that none of the 30 individual batches that were used for
an annual performance test between 2007 and 2016 exceeded the
prescribed VOC emission limitations. The EPA agrees; in fact, the
linear regression must be calculated from a batch that does not exceed
the emission limitations, as required by 40 CFR 63.2161(d)(3). If the
commenter does not agree that the correlation equation should be
applied to any BAE values other than those directly tested, the
commenter would seem to be suggesting that a performance test must be
conducted on each individual batch manufactured by a facility, which
would be cost-prohibitive and is not feasible for a facility. To
clarify, the EPA never stated that the facility exceeded the NESHAP
emission limitations for any of the batches monitored during a
performance test between 2011 and 2016. Rather, we demonstrated that
the relationship between the concentration of VOC in the fermenter
exhaust and the percent of brew ethanol in the fermenter liquid is not
consistent between batches. Therefore, the use of the relationship
between VOC concentration and percent of brew ethanol from one batch to
calculate emissions from all other batches in the same fermentation
stage over an arbitrary period of time is unreliable. While this could
mean that the facility under-reports emissions from some batches, it
also means that the facility could over-report emissions from some
batches. This potential for over-reporting is best illustrated with the
use of ``higher end'' BAE values. If a particular correlation was
established one year for a batch that had an unusually high
relationship between VOC concentration and brew ethanol percentage, the
continued use of that correlation for the period of that year could
conceivably cause the facility to calculate BAVOC values over the
emission limitations for enough batches that the facility would appear
to be out of compliance; such a circumstance would cause the facility
to incur significant compliance costs, regardless of what the actual
emissions were since actual emissions are not tested.
    As a point of clarification, the commenter refers to brew ethanol
monitoring as a ``parametric CEMS.'' The commenter is combining two
elements together that have different regulatory meanings. A continuous
monitoring system can be a continuous parameter monitoring system
(CPMS) or a CEMS, but a CPMS is not a CEMS. CPMS and CEMS are defined
separately at 40 CFR 63.2, such that a CPMS is ``used to sample,
condition (if applicable), analyze, and provide a record of process or
control system parameters'' and a CEMS is ``used to sample, condition
(if applicable), analyze, and provide a record of emissions''. The EPA
revised the rule language to use ``brew ethanol monitor'' instead of
``CEMS'' because a brew ethanol monitor does not record VOC emissions
and, thus, is not a CEMS. A brew ethanol monitor is used to measure the
brew ethanol concentration in the fermenter liquid, which is then used
to estimate VOC emissions via the brew ethanol correlation. The change
in terminology did not result in any changes to the existing
requirements. Rather it ensured the existing language was technically
correct.
    Comment: One commenter indicated that multiple facilities use brew
ethanol monitoring to calculate VOC emissions and, thus, brew ethanol
monitoring should not be eliminated as an acceptable option. The
commenter described that one facility uses brew ethanol monitoring as
well as CEMS to develop VOC emissions data, with the brew ethanol
monitoring serving as a quality assurance step.
    Response: Only one facility currently uses brew ethanol monitoring
to demonstrate compliance; the other facilities all utilize CEMS VOC
data to demonstrate compliance with the standard. Use of brew ethanol
monitoring for quality assurance does not prove its capability to
provide accurate and reliable data for a compliance demonstration. The
final rule does not prohibit the use of other methods of quality
assurance for process control in addition to the systems necessary to
meet the requirements of the rule.
    Comment: Two commenters argued that requiring facilities to install
flame ionization detection (FID) CEMS to replace brew ethanol
monitoring would not provide emissions data that is more reliable or
less variable and that the EPA has not shown that CEMS would result in
meaningful improvement to compliance or regulatory outcomes. One
commenter cited a letter (see EPA-HQ-OAR-2015-0730-0191-A54) that
commented on the accuracy of FID CEMS; the letter stated that the
presence of oxygen, moisture, and hydrocarbons in fermenter emissions
have the potential to interfere with FID CEMS technology and cause
variability in any data collected using FID CEMS.
    Response: The EPA disagrees that the use of brew ethanol monitoring
is comparable to the use of FID CEMS to monitor emissions from the
manufacturing of nutritional yeast. As explained previously in this
section and the memorandum, ``Brew Ethanol Correlation Review for the
Manufacturing of Nutritional Yeast Source Category--Final Rule,'' which
is available in the docket for this rulemaking, the brew ethanol method
does not account for batch-specific variables affecting emissions. An
FID CEMS, on the other hand, does indicate batch-specific emissions,
which increases confidence that reported emissions are reliable.
Additionally, such data can help a facility avoid the potential for
erroneously determining that it is out of compliance compared to the
scenario of using a batch with an unusually high ratio of VOC emissions
to brew ethanol content for the annual performance test and the
subsequent correlation calculation.
    While it is true that the accuracy of an FID CEMS can be affected
by factors such as moisture, the commenter does not acknowledge the
common procedures in place to minimize these effects (such as the use
of heated sample lines) or the difference between monitoring system
malfunctions and day-to-day reliability of these systems. Similarly,
the letter discusses technical issues with response factors. Response
factors are needed to establish the relationships of different gases to
the one used as the calibration standard for a measurement instrument.
Since the standard is expressed in terms of VOC as propane and the FID
CEMS are calibrated with propane (as required by 40 CFR 63.2163 (d)),
response factors are not used and the commenter's argument is
irrelevant.

4. What is the rationale for our final approach?
    For the reasons explained in the preamble to the proposed rule (81
FR 95827, December 28, 2016), in the comment responses in section
IV.D.3 of this preamble, and in the memorandum, ``Brew Ethanol
Correlation Review for the Manufacturing of Nutritional Yeast Source
Category--Final Rule,'' which is available in the docket for this
rulemaking, we are finalizing the removal of the option to demonstrate
compliance by monitoring brew ethanol in the fermenter liquid as
proposed, with the changes related to frequency described in section
IV.D.2 of this preamble.
    We finalized requirements at 40 CFR 63.2150(b) and 63.2166, and
Tables 3, 4, and 8 to subpart CCCC to remove the option to monitor brew
ethanol.

E. Requirement To Conduct RATA

1. What did we propose?
    The EPA proposed a requirement in 40 CFR 63.2163 to conduct annual
RATA for all VOC CEMS, which were previously exempt from this quality
assurance requirement. This proposed requirement specified the use of
Procedure 1 of appendix F to part 60 to evaluate the performance of the
installed VOC CEMS over an extended period of time (81 FR 95829,
December 28, 2016). The EPA also proposed to replace an outdated
reference with the current version of the EPA's traceability protocol
for use in quality assurance procedures for CEMS.
2. How did the requirements change since proposal?
    The EPA has maintained the proposed requirement to conduct ongoing
RATA; however, in response to public comments, we are revising the
frequency of the RATA. We are finalizing a requirement for facilities
to conduct RATA for each CEMS at least once every 3 years, instead of
annually. The EPA also corrected the proposed rule language (see 40 CFR
63.2163(b)(3)) to clarify that the current version of the EPA's
traceability protocol (EPA/600/R-12/531) replaces citation 2 of
Procedure 1 of appendix F to 40 CFR part 60; at proposal, the EPA
incorrectly cited reference 2 of Performance Specification 8 of
appendix B to 40 CFR part 60.
3. What key comments did we receive and what are our responses?
    Comment: A commenter did not support the proposed requirement to
require annual RATA for all CEMS and stated that it was a costly
procedure that would not enhance process control or achieve any valid
regulatory goal. If RATA are required, the commenter suggested that
RATA be conducted on a 3- to 5-year cycle, rather than annually. The
commenter also requested the final rule clarify that RATA are not
required every time a CEMS is repaired or replaced.
    One commenter stated the more stringent monitoring requirements
were not justified because it would not lead to a reduction in
emissions and would unnecessarily increase cost.
    Response: During the site visits conducted for this rulemaking, it
was noted that many of the malfunctions recorded by the facilities
subject to this rule were due to malfunctions of the compliance
monitoring systems. Regular RATA ensure the CEMS continue to produce
valid data, which is necessary for the owner or operator, as well as
the EPA, to ensure compliance. A RATA assesses both the instrument
accuracy in measuring the target analyte in the emission matrix (which
daily calibrations and audits using reference gases do not) as well as
the representativeness of the CEMS sampling location.
    It is routine for the EPA to require annual RATA of CEMS. While the
original rule did not require annual RATA for FID CEMS, the EPA has
finalized revisions to require ongoing quality assurance procedures
(including RATA) in many rules since 2001. For example, ongoing quality
assurance procedures were included in the Metal Coil Surface Coating,
Miscellaneous Coating Manufacturing, Plywood and Composite Wood
Products, and Portland Cement Manufacturing MACT standards, promulgated
on June 10, 2002; December 11, 2003; July 30, 2004; and February 12,
2013, respectively. The addition of RATA procedures to the Nutritional
Yeast rule helps complete this missing, but necessary, quality-
assurance component.
    However, to reduce burden, the EPA is finalizing a requirement to
conduct RATA at least once every 3 years, instead of annually, as
proposed.
    The EPA is not revising the rule language to state that RATA are
not required in certain instances. In fact, the replacement of a CEMS
would require a RATA to ensure accuracy of the measured data.
4. What is the rationale for our final approach?
    For the reasons explained in the preamble to the proposed rule (81
FR 95829, December 28, 2016) and in the comment responses in section
IV.E.3 of this preamble, we are finalizing requirements in 40 CFR
63.2163 to conduct RATA, as proposed, with the changes related to
frequency and the traceability protocol citation described in section
IV.E.2 of this preamble.

F. Requirement To Collect All Valid CEMS Data

1. What did we propose?
    The EPA proposed a requirement to collect CEMS data at all times
during each batch monitoring period, except for periods of monitoring
system malfunctions, required monitoring system quality assurance or
quality control activities, and any scheduled maintenance (81 FR 95829,
December 28, 2016). The requirements were proposed at 40 CFR 63.2163,
63.2170, 63.2181(c)(8), and 63.2182(b)(9).
2. How did the requirements change since proposal?
    The EPA is finalizing, as proposed, the requirement to collect all
valid CEMS data. In response to comments, we have also finalized
clarifications to the rule text to reinstate 40 CFR 63.8(c)(4)(ii),
(c)(7), and (g)(2) of the General Provisions that specify the minimum
operation requirements for CEMS (at least one cycle every 15 minutes),
the definition and requirements for ``out of control'' CEMS, and the
procedures for the reduction of CEMS data to hourly averages.
3. What key comments did we receive and what are our responses?
    Comment: A commenter stated that collecting CEMS data at all times,
instead of for 75 percent of the batch hours, is an impossible bar that
is not achievable in practice. The commenter stated that collecting
data from 75 percent of batch hours is a reasonable accommodation of
the fact that monitoring equipment cannot operate perfectly or be
calibrated 100 percent of the time in an industrial plant. The
commenter suggested a monitoring requirement of total CEMS uptime of 75
percent of fermentation time during rolling 12-month periods. The
commenter also requested the EPA clarify that ``at all times'' means
logging data once every 15 minutes.
    The commenter stated that nothing in the record supports the theory
that more stringent monitoring will add precision to the measurement
and that any such precision would not be meaningful from an operation
or compliance standpoint. The commenter noted the existing monitoring
requirements are sufficient to determine the average VOC concentration
in a fermenter batch and across numbers of batches. The commenter was
concerned that

requiring more stringent monitoring could subject facilities to
enforcement actions and citizen suits.
    The commenter recommended three alternative monitoring methods for
periods that CEMS are not available. The commenter also requested the
EPA define expressly the procedures for monitoring system out-of-
calibration, downtime, or missing data in the rule language, rather
than using cross references to other EPA technical procedures.
    Response: We emphasize that the proposed amendments specified that
data must be collected ``at all times during each batch monitoring
period, except for periods of monitoring system malfunctions, required
monitoring system quality assurance or quality control activities
(including, as applicable, calibration checks and required zero and
span adjustments), and any scheduled maintenance.'' We disagree that a
requirement to collect CEMS data at all other times is an impossible
bar that is not achievable in practice. As far back as 1994, the EPA's
Office of Water reported that total hydrocarbon (THC) CEMS, which are a
subset of VOC CEMS, along with other analyzers necessary to correct
values to standard moisture and oxygen content, were ``. . . able to
demonstrate a data capture rate of 100 percent, based on four
measurements per minute.'' \2\ Electronically submitted data from
Portland cement source owners or operators currently using VOC CEMS as
a compliance method also refutes the commenter's assertion. As shown
from a quick search of submissions to the EPA's ERT,\3\ at least five
separate facilities \4\ report greater than 90-percent uptime for their
THC CEMS.\5\ Moreover, none of the facilities reported an inability to
collect monitoring data at all times that their units were operating
and the commenter did not provide any examples of the inability to
collect data other than monitor malfunctions or quality assurance/
quality control activities.
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    \2\ Available at https://cfpub.epa.gov/webfire/index.cfm?action=fire.searchERTSubmission.
    \3\ Available at https://cfpub.epa.gov/webfire/index.cfm?action=fire.searchERTSubmission.
    \4\ The facilities and periods over which THC monitoring was
reported include: Ash Grove Cement in Durkee, Oregon, from July
through December 2016; Signal Mountain Cement Company in
Chattanooga, Tennessee, from September 2015 through December 2016;
Cemex Construction Materials Atlantic in Knoxville, Tennessee, from
February through December 2016; Holcim (US) in Theodore, Alabama,
from January through December 2016; and Lehigh Ready Mix Cement in
Leeds, Alabama, from July through December 2016.
    \5\ While the Portland cement manufacturing emission reports
only require CEMS downtime greater than or equal to 90 percent to be
reported [see 40 CFR 63.1354(b)(10)], subject facilities--just like
as proposed for nutritional yeast manufacturers--are required to
conduct all monitoring in continuous operation at all times that the
units are operating [see 40 CFR 63.1350(i) and (m)(2)].
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    We find that the commenter misinterprets the requirement to collect
data at all times. The proposed rule does not require the VOC CEMS to
be operating perfectly or calibrated for 100 percent of the time. In
fact, the rule specifically prohibits data collection during periods of
monitoring system malfunction or of required monitoring system quality
assurance or control activities--such as calibrations and scheduled
maintenance (see 40 CFR 63.2170(b)). Moreover, the rule allows owners
or operators to establish and follow their own CEMS quality control
programs with site-specific performance evaluation plans that cover
items such as initial and subsequent calibrations, calibration drift
specifications, preventive maintenance, accuracy audit procedures, and
CEMS corrective action procedures (see 40 CFR 63.8(d)(2)), as
referenced by Table 6 of the rule). The commenter's concern for
practicality regarding 100-percent data collection is misplaced; while
the rule requires complete data collection from certain periods, it
does not require 100-percent data collection. Moreover, in the event
that data are not collected as required during certain periods, the
occurrences are specified as deviations, rather than automatic
violations, of the rule; such deviations are to be reported by owners
or operators to regulatory authorities who would take appropriate
corrective action as necessary (see 40 CFR 63.2170(d)). Finally, source
owners or operators are able to use the aforementioned site-specific
monitoring plans to obtain approval from regulatory authorities for
replacement emissions monitoring capabilities through approaches such
as redundant or independent temporary systems prior to their use. While
we reasoned that a facility may achieve enhanced process control from
the amendments to the rule, this potential enhancement was not the
basis for requiring the collection of CEMS data at all times. Given the
variability in emissions throughout the process of manufacturing a
batch of yeast, it is necessary to collect data at all times the CEMS
are operational (given the exemptions noted above) to calculate
accurate BAVOC values. The goal of the revision is to ensure the values
collected and reported are suitable for demonstrating compliance with
the rule. The enhanced monitoring data will allow us, owners or
operators, and the public to have greater confidence in compliance
determinations based on those measurements, and, therefore, greater
confidence that the expected health benefits of the rule are achieved.
    We disagree with the commenter's view that the monitoring is more
stringent or could subject facilities to an increased number of
enforcement actions or citizen suits, as the rule requires compliance
with the emission limitations at all times. Monitoring itself does not
affect a facility's actual compliance status and, as stated above,
monitoring downtime is characterized as a deviation from, rather than
violation of, emission standards. Regarding enforcement discretion, we
rely on our regulatory partners to assess the individual, case-specific
facts and to take appropriate action when necessary to correct
problems. Owners or operators can take steps under their own control to
reduce or eliminate any compliance concerns through activities such as
increased attention to emissions-causing processes; and development,
acceptance, and use of redundant monitoring systems.
    We agree with the commenter's suggestion to clarify in the rule a
minimum CEMS cycle time of 15 minutes, in which a value would be
collected and recorded. This clarification was included by reinstating
the applicability of 40 CFR 63.8(c)(4)(ii) of the General Provisions in
Table 6. Furthermore, we have reinstated the applicability of 40 CFR
63.8(g)(2) of the General Provisions in Table 6 that allows a minimum
of two data points (each representing 15-minute periods) or an
arithmetic or integrated 1-hour average of CEMS data to constitute a
valid hour of data collection during periods of calibration, quality
assurance, or maintenance activities. These two sections of the General
Provisions were not applicable to the 2001 Manufacturing of Nutritional
Yeast, because alternate definitions were included in the rule. Now
that the CEMS requirements have been updated, there is no need for
separate requirements for this source category and the requirements
from the General Provisions can be applied.
    We do not agree with suggestions to write out monitoring system
procedures when those procedures already exist in other applicable
rules. Where relevant procedures already exist in other rules, our
policy is to cross-reference those procedures; cross-referencing
eliminates duplicative portions of rules and ensures consistency. While
we do not see the need for alternative monitoring methods for periods
when VOC CEMS are unavailable, since the

aforementioned data on the use of CEMS in other source categories from
the EPA's ERT showed no periods of VOC CEMS unavailability, the rule
does not prohibit owners or operators from proposing--and from
regulatory authorities accepting--alternate means for assessing
emissions as part of corrective action procedures for a malfunctioning