the-floor standard under CAA section 112(d)(2). However, we are
soliciting comments, data, and other information regarding this
proposed decision, including data and information regarding the capital
and annual costs, cost effectiveness, non-air impacts, and other
relevant information that would be relevant for the remaining facility
regarding whether the NESHAP should include a zero-mercury standard as
a beyond-the-floor MACT standard. We intend to consider any such
submitted data and information, in addition to the data and information
contained in the records for the 2008 and 2011 proposals and in this
proposal, in reaching final conclusions under CAA section 112(d)(2)
regarding a zero-mercury standard beyond-the-floor.

B. What are the results of the risk assessment and analyses?

    As described above, for the Mercury Cell Chlor-Alkali Plant source
category, we conducted an inhalation risk assessment for all HAP
emitted, a multipathway screening assessment for the PB-HAP emitted,
and an environmental risk screening assessment for the PB-HAP emitted
from the source category. When we initiated this RTR and developed the
risk input files, there were two facilities operating in the source
category (Ashta in Ohio and Westlake in West Virginia); however, as
noted above, Ashta has since permanently shut down the mercury cell
process. We also conducted an environmental screening for HCl, because
we initially had some HCl emissions in our data set, but as described
above, after further review, we conclude those HCl emissions are due to
non-category sources. We present results of the risk assessment briefly
below and in more detail in the Residual Risk Assessment for the
Mercury Cell Chlor-Alkali Plant Source Category in Support of the Risk
and Technology Review 2020 Proposed Rule, which is available in the
docket for this action.
1. Chronic Inhalation Risk Assessment Results
    The EPA estimated inhalation risk is based on actual and allowable
emissions. The estimated baseline MIR posed by the source category is
less than 1-in-1 million based on actual emissions and MACT-allowable
emissions. The total estimated cancer incidence based on actual or
allowable emission levels is 0.0000003 excess cancer cases per year, or
one case every 3 million years. Emissions of 1,3-dichloropropene from
the mercury cell building at Ashta accounted for 100 percent of the
cancer incidence. No one is exposed to cancer risk greater than or
equal to 1-in-1 million based upon actual and allowable emissions (see
Table 1 of this preamble). However, based on the available data, the
1,3-dichloropropene was only emitted from Ashta, which is no longer
operating as a mercury cell facility, as discussed above. Furthermore,
we have no indication or data suggesting that this pollutant is emitted
from the one remaining facility.
    The maximum chronic noncancer TOSHI values for the source category
were estimated to be less than 1 (0.05) based on actual and allowable
emissions. For both actual and allowable emissions, respiratory risks
were driven by chlorine emissions from the mercury cell building.

                           Table 1--Inhalation Risk Assessment Summary for Mercury Cell Chlor-Alkali Plant \1\ Source Category
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Maximum        Estimated       Estimated
                                                         individual     population at   annual cancer
           Risk assessment                Number of      cancer risk   increased risk     incidence         Maximum chronic      Maximum screening acute
                                       facilities \2\      (1-in-1     of cancer >= 1-   (cases per       noncancer TOSHI \4\        noncancer HQ \5\
                                                        million) \3\    in-1 million        year)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Baseline Actual Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category......................               2           0.004               0       0.0000003  0.05 (respiratory)......  2 (REL), 7E-4 (AEGL2).
Facility-Wide........................               2             0.3               0          0.0001  0.05 (respiratory)......  .......................
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Baseline Allowable Emissions
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source Category......................               2           0.004               0       0.0000003  0.05 (respiratory)......  .......................
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on actual and allowable emissions.
\2\ Number of facilities in the risk assessment includes two facilities subject to 40 CFR part 63, subpart IIIII.
\3\ Maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\4\ Maximum TOSHI. The target organ with the highest TOSHI for the source category is the respiratory system.
\5\ The maximum estimated acute exposure concentration was divided by available short-term threshold values to develop an array of HQ values. The acute
  HQ shown was based upon the lowest acute 1-hour dose-response value, the REL for mercury (elemental). When an HQ exceeds 1, we also show the HQ using
  the next lowest available acute dose-response value.

2. Screening Level Acute Risk Assessment Results
    Based on our refined screening analysis of reasonable worst-case
acute exposure to actual emissions from the category, both facilities
exceeded an HQ of 1 (the HQ was 2) when compared to the 1-hour REL for
mercury (elemental). As discussed in section III.C.3.c of this
preamble, we used an acute hourly multiplier of 10 for all emission
processes. For this HAP, there are no AEGL-1 or ERPG-1 values for
comparison, but AEGL-2 or ERPG-2 values are available. For elemental
mercury, when the maximum off-site concentration is compared with the
AEGL-2 and ERPG-2, the maximum acute noncancer HQ is well below 1
(0.0007).
3. Multipathway Risk Screening Results
    PB-HAP emissions (based on estimates of actual emissions) were
reported from both facilities in the source category with both
exceeding the Tier 1 non-cancer screening threshold emission rate for
mercury. A Tier 2 screening analysis was conducted with no facilities
having an SV greater than 1 for any scenario (the fisher and farmer had
the highest SV at 0.4). There are no carcinogenic PB-HAP emitted from
the source category. So, there are no cancer SVs to report. Further
details on the Tier 2 screening analysis can be found in the Residual
Risk Assessment for the Mercury Cell Chlor-Alkali Plant Source Category
in Support of the Risk and Technology Review 2020 Proposed Rule, and
Appendix 10 of this report.

    An SV in any of the tiers is not an estimate of the cancer risk or
a noncancer HQ. Rather, an SV represents a high-end estimate of what
the risk or HQ may be. For example, facility emissions resulting in an
SV of 2 for a non-carcinogen can be interpreted to mean that we are
confident that the HQ would be lower than 2. Similarly, facility
emissions resulting in a cancer SV of 20 for a carcinogen means that we
are confident that the cancer risk is lower than 20-in-1 million. Our
confidence comes from the health-protective assumptions that are
incorporated into the screens: we choose inputs from the upper end of
the range of possible values for the influential parameters used in the
screens, and we assume food consumption behaviors that would lead to
high total exposure. This risk assessment estimates the maximum hazard
for mercury through fish consumption based on upper bound screens. As
discussed above, the maximum mercury Tier 2 noncancer SV based upon the
fisher scenario resulted in an SV less than 1.
4. Environmental Risk Screening Results
    As described in section III.A of this preamble, we conducted an
environmental risk screening assessment for the Mercury Cell Chlor-
Alkali Plant source category for the following pollutants: HCl and
mercury (methyl mercury and mercuric chloride). However, as noted
above, we subsequently determined that the HCl emissions are due to
non-category sources such as co-located HCl production.
    In the Tier 1 screening analysis, methyl mercury and divalent
mercury resulted in exceedances of ecological benchmarks by two
facilities. Divalent mercury emissions had Tier 1 exceedances for the
following benchmarks: Surface soil threshold level--invertebrate
communities by a maximum SV of 4. Methyl mercury had Tier 1 exceedances
for the following benchmarks: No Observed Adverse Effect Level
(NOAEL)--avian ground insectivores (woodcock) by a maximum SV of 6.
    A Tier 2 screening analysis was performed for divalent mercury and
methyl mercury. In the Tier 2 screening analysis, divalent mercury
emissions had no Tier 2 exceedances. Methyl mercury had Tier 2
exceedances for one facility exceeding the following benchmark: Surface
soil NOAEL for avian ground insectivores (woodcock) by a maximum SV of
2 with 0.1 percent of the soil area being above an SV of 2.
    For HCl, only one facility reported emissions. The average modeled
concentration around this facility (i.e., the average concentration of
all off-site data points in the modeling domain) did not exceed any
ecological benchmark. In addition, each individual modeled
concentration of HCl (i.e., each off-site data point in the modeling
domain) was below the ecological benchmarks. However, as explained
above, after further investigation, we conclude that the reported HCl
emissions are due to non-category sources.
5. Facility-Wide Risk Results
    The EPA estimated inhalation risk based on facility-wide emissions
to be 0.3-in-1 million, with an 0.0001 excess cancer cases per year, or
one case every 10,000 years. Emissions of metals (arsenic, chromium VI,
and nickel) from non-category sources account for 100 percent of the
cancer incidence. No one is exposed to cancer risk greater than or
equal to 1-in-1 million (see Table 1 of this preamble). The maximum
chronic noncancer TOSHI value for the source category was the same for
both actual emissions and allowable emissions with an HI less than 1
(0.05) for respiratory risks driven by chlorine emissions from the
mercury cell building.
6. What demographic groups might benefit from this regulation?
    To examine the potential for any environmental justice issues that
might be associated with the source category, we performed a
demographic analysis, which is an assessment of risks to individual
demographic groups of the populations living within 5 km and within 50
km of the facilities. In the analysis, we evaluated the distribution of
HAP-related cancer and noncancer risks from the mercury cell chlor-
alkali plant source category across different demographic groups within
the populations living near the two facilities.\23\
---------------------------------------------------------------------------

    \23\ Demographic groups included in the analysis are: White,
African American, Native American, other races and multiracial,
Hispanic or Latino, children 17 years of age and under, adults 18 to
64 years of age, adults 65 years of age and over, adults without a
high school diploma, people living below the poverty level, people
living two times the poverty level, and linguistically isolated
people.
---------------------------------------------------------------------------

    Results of the demographic analysis indicate that, for three of the
11 demographic groups, age greater than or equal to 65, age greater
than or equal to 25 years of age without a high school diploma, and
people below the poverty level, the percentage of the population living
within 5 km of facilities in the source category is greater than the
corresponding national percentage for the same demographic groups. When
examining the risk levels of those exposed to emissions from mercury
cell chlor-alkali plant facilities, we find that no one is exposed to a
cancer risk at or above 1-in-1 million or to a chronic noncancer TOSHI
greater than 1.
    The methodology and the results of the demographic analysis are
presented in a technical report, Risk and Technology Review--Analysis
of Demographic Factors for Populations Living Near Mercury Cell Chlor-
Alkali Plant Source Category Operations, available in the docket for
this action.

C. What are our proposed decisions regarding risk acceptability, ample
margin of safety, and adverse environmental effect?

1. Risk Acceptability
    As explained in section II.A of this preamble, the EPA sets
standards under CAA section 112(f)(2) using ``a two-step standard-
setting approach, with an analytical first step to determine an
`acceptable risk' that considers all health information, including risk
estimation uncertainty, and includes a presumptive limit on MIR of
approximately 1-in-10 thousand'' (54 FR 38045, September 14, 1989). The
EPA weighed all health risk measures and information, including science
policy assumptions and estimation uncertainties, in determining whether
risk posed by emissions from the source category is acceptable.
    As described above, the maximum cancer risk for inhalation exposure
to actual and allowable emissions from the Mercury Cell Chlor-Alkali
Plant source category is 0.004-in-1 million, which is more than four
orders of magnitude below 100-in-1 million, which is the presumptive
upper limit of acceptable risk. The EPA estimates emissions from the
category would result in a cancer incidence of 0.0000003 excess cancer
cases per year, or one case every 3 million years. Furthermore, as
described above, the facility estimated to pose those cancer risks is
no longer operating as a mercury cell facility. Inhalation exposures to
HAP associated with chronic noncancer health effects result in a TOSHI
of 0.05 based on actual and allowable emissions, 20 times below an
exposure that the EPA has determined is without appreciable risk of
adverse health effects. Exposures to HAP associated with acute
noncancer health effects result in an HQ less than or equal to 2 based
upon the 1-hour REL for elemental mercury, and when the maximum off-
site concentration is compared with the AEGL-2 and ERPG-2, the maximum
acute noncancer HQ is

well below 1 (0.0007). This information, in addition to the
conservative (health-protective) assumptions built into the screening
assessment, leads us to conclude that adverse effects from acute
exposure to emissions of this HAP from this source category are not
anticipated. Maximum noncancer hazard due to ingestion exposures
estimated using health-protective risk screening assumptions are below
an HQ of 1 (0.4) for the Tier 2 fisher scenario. The estimated
ingestion cancer risk is zero since we did not identify any
carcinogenic HAP emitted from the source category. Considering all of
the health risk information and factors discussed above, as well as the
uncertainties discussed in section III of this preamble, we propose
that the risks posed by emissions from the Mercury Cell Chlor-Alkali
Plant source category are acceptable.
2. Ample Margin of Safety Analysis
    As directed by CAA section 112(f)(2), we conducted an analysis to
determine whether the current emissions standards provide an ample
margin of safety to protect public health. Under the ample margin of
safety analysis, we evaluated the cost and feasibility of available
control technologies and other measures (including the controls,
measures, and costs reviewed under the technology review) that could be
applied to this source category to further reduce the risks (or
potential risks) due to emissions of HAP from the source category.
    As described above, the only HAP emitted from this source category
posing any risks of potential concern is elemental mercury, with a
maximum noncancer acute HQ of 2 based on the REL. Therefore, we
considered potential options to reduce mercury emissions under the
ample margin of safety analysis. The options we considered under the
ample margin of safety analysis are the exact same control options
described under the technology review section of this preamble (see
section IV.D below).
    First, as described in greater detail under the technology review
section, we evaluated the option of requiring a combination of
implementing a cell room monitoring program and performing work
practices as an approach to minimize mercury emissions. Under the
technology review section, we determined that this option does
constitutes a development in emissions control practices pursuant to
CAA section 112(d)(6) with very low costs, and, therefore, we are
proposing these requirements under the technology review. However,
since the one operating facility already conducts these two actions, we
do not expect any actual reductions in emissions and, therefore, we
would expect no actual reductions in risks. Since this option is not
expected to result in any risk reductions, we are not proposing to
adopt those requirements pursuant to CAA section 112(f).
    The other option we considered under the CAA section 112(d)(6)
technology review (described in section IV.D of this preamble) as well
as under CAA sections 112(d)(2) and (3), as described in section IV.A
of this preamble, is to require zero mercury emissions from existing
sources, which is the requirement for new and reconstructed mercury
cell chlor-alkali production sources. This option would eliminate
process vent and fugitive mercury emissions as it would force the
remaining facility to convert the operation to a non-mercury process or
close the mercury cell operation. As described in more detail in
sections IV.A and IV.D of this preamble, we estimate the capital cost
of converting the one remaining mercury cell facility to membrane cells
is just over $69 million. The estimated emissions of mercury would be
reduced from 126 pounds to zero pounds per year. Considering the costs
of conversion annualized over a time period of 20 years, the annual
costs are estimated to be approximately $2.8 million, which results in
a cost effectiveness of approximately $22,000 per pound of mercury
emissions eliminated. With regard to reductions in risks due to HAP
emissions as a result of this option, since this option would force
conversion or closure of the remaining one mercury cell facility, the
risks due to emissions of HAP for the source category would be zero,
since there would be no facilities in the source category.
    Nevertheless, after considering the options described above, since
the risks due to mercury emissions are already low (with a maximum
acute noncancer HQ of less than or equal to 2 based upon the 1-hour REL
and a maximum HQ of 0.0007 based on AEGL-2 and ERPG-2), and given the
costs described above, and because of the substantial uncertainties in
the emissions estimates and cost estimates, we are not proposing any
additional standards for mercury under CAA section 112(f).
    In summary, considering the very low cancer risks (MIR far less
than 1-in-1 million) and very low chronic noncancer risks (HI of 0.05)
to individuals exposed to HAP emitted from this source category, and
after considering possible options for mercury as described above, we
are proposing a determination that the existing standards provide an
ample margin of safety to protect public health.
3. Adverse Environmental Effect
    Based on the results of the environmental risk screening analysis,
we do not expect an adverse environmental effect, as defined by CAA
section 112(a)(7), as a result of HAP emissions from this source
category, and we are proposing that it is not necessary to set a more
stringent standard to prevent, taking into consideration costs, energy,
safety, and other relevant factors, an adverse environmental effect.

D. What are the results and proposed decisions based on our technology
review?

    As noted above, 40 CFR part 63, subpart IIIII currently includes
emission limitations for mercury emissions from process vents
(including emissions from end-box ventilation systems, hydrogen
systems, and mercury recovery facilities) and work practices for
fugitive mercury emissions from the cell room. We have identified a
development for cell room fugitive mercury emissions.
    With regard to fugitive mercury emissions from the cell room, the
current rule at 40 CFR 63.8192(a) through (f) requires a suite of
equipment standards and work practices. It also provides the option, in
lieu of the work practices otherwise required under CAA sections
63.8192(a) through (d), to institute a cell room monitoring program to
continuously monitor the mercury vapor concentration in the upper
portion of each cell room. See 40 CFR 63.8192 introductory text, and 40
CFR 63.8192(g). The single mercury cell facility still operating
complies via this alternative. However, while not required to do so
under the current regulation, the facility also performs all the work
practices. Therefore, the EPA determined that the combination of
implementing a cell room monitoring program and performing work
practices constitutes a development in emissions control practices.
This combination was the proposed option in the June 11, 2008, action
(73 FR 33258), and also included as a co-proposal in the March 14, 2011
(76 FR 13852), action. Since the only facility in the source category
is already implementing the monitoring program and performing these
work practices, there would be no costs (with the exception of
additional recordkeeping and reporting costs) or additional mercury
emission reductions associated with implementing a standard that
requires a combination of these practices.

    We also identified the option to require zero mercury emissions
from existing sources, which is the requirement for new and
reconstructed mercury cell chlor-alkali production sources. This option
would eliminate process vent and fugitive mercury emissions as it would
force the remaining facility to convert the operation to a non-mercury
process, or close the mercury cell operation, by a date no later than 3
years of the date of publication of the final rule. See CAA section
112(i)(3)(A). When the EPA originally listed the Chlorine Production
source category in 1992, there were 13 mercury cell chlor-alkali plants
in the U.S. Since that time, the number of facilities has steadily
declined to the current situation with only one facility. Many owners
of mercury cell facilities converted to the more efficient and more
environmentally friendly membrane cell technology, while other mercury
cell chlor-alkali plant owners have concluded the investment decision
was currently not in their company's interest given their assessment of
future economic conditions and have shut down their mercury cell chlor-
alkali plants entirely. Therefore, the zero mercury emissions option is
a demonstrated potential development in processes pursuant to CAA
section 112(d)(6).
    The EPA has considered this option previously since the
promulgation of the regulation in 2003, in the context of evaluating
whether a prohibition on mercury emissions would be a reasonable
beyond-the-floor MACT measure under CAA section 112(d)(2). As discussed
above, in 2008, the EPA proposed amendments to 40 CFR part 63, subpart
IIIII (73 FR 33258, June 11, 2008). One of the options evaluated for
this 2008 proposal was to require zero mercury emissions, and the EPA
evaluated the impacts of requiring conversion of mercury cell chlor-
alkali production plants to non-mercury technology. The EPA proposed
``to reject conversion to non-mercury technology as a beyond-the-floor
control requirement because of the high cost impact this forced
conversion would impose on the facilities in the industry.'' As noted
above, the EPA proposed the combination of mercury cell room monitoring
and work practices in the 2008 action (73 FR 33275).
    Considering comments received on the 2008 proposed cost and impacts
analysis of the option to convert to non-mercury technology, the EPA
significantly refined the analysis. The results of the revised analyses
were published in 2011, along with two proposed options to reduce
mercury emissions. One was an option to require all mercury cell chlor-
alkali facilities to comply with a zero-mercury emissions limitation
within 3 years of the finalization of the proposal (76 FR 13852, March
14, 2011). The other proposed option was to require continuous
monitoring of mercury in the upper regions of the cell room along with
work practices, as under the 2008 proposal (and as being proposed here
under CAA section 112(d)(6)). The revised analysis of the impacts of
conversion from mercury cells to membrane cells is discussed in detail
in the 2011 proposal and supporting documentation.
    Comments were received on the updated analysis and supplemental
2011 proposal. An environmental advocacy commenter (Docket Item No.
EPA-HQ-OAR-2002-0017-0152) supported the proposed zero-mercury option
but also commented that the EPA had overstated the costs and
understated the emission reductions and other benefits. Conversely,
three industry representatives (Docket Item Nos. EPA-HQ-OAR-2002-0017-
0150, -0151, and -0157) commented that the EPA's revised analysis had
underestimated the costs and negative economic impacts and overstated
the benefits. One industry representative (Docket ID No.EPA-HQ-OAR-
2002-0150) provided an analysis of the impacts of conversion specific
to the West Virginia facility (which is, as discussed previously, the
only mercury cell plant currently still in operation). The commenter
indicated that the cost of conversion estimated by the EPA for this
facility (around $43 million) was considerably less than the estimates
calculated by the facility (around $60 million). The commenter also
provided a cost-effectiveness analysis, which showed a cost of over
$77,000 per pound of mercury emissions eliminated for this facility.
The EPA has not yet finalized either of the options included in the
2011 supplemental proposal, or otherwise issued a final beyond-the-
floor MACT determination under CAA section 112(d)(2) for existing
source mercury emissions, as discussed above.
    For this proposal, the EPA re-examined the impacts of a zero-
mercury option. Specifically, the EPA evaluated the costs and cost
effectiveness of the replacement of the West Virginia mercury cell
facility with a membrane cell facility. As pointed out above, the EPA's
2011 estimate for the capital cost to convert the West Virginia
facility was just over $43 million and an annual cost of $2.6 million
per year. The EPA updated this estimate by adjusting the costs to 2019
dollars and incorporating the actual costs of conversion incurred by
the Ohio facility for their 2019/2020 conversion. The resulting updated
estimate is that the capital cost of converting the West Virginia
mercury cell facility to membrane cells is just over $69 million. The
estimated emissions of mercury would be reduced from 126 pounds to zero
pounds per year. Considering the costs of conversion annualized over a
time period of 20 years, the annual costs are estimated to be
approximately $2.8 million, which results in a cost effectiveness of
approximately $22,000 per pound of mercury emissions eliminated.\24\
While some commenters have suggested that the EPA's estimates of
mercury emissions from mercury cell chlor-alkali facilities are
underestimated due to ``unaccounted for'' mercury, the EPA's detailed
study conducted prior to the 2008 proposal demonstrated otherwise.
Specifically, the EPA stated ``The results of the almost one million
dollar study of fugitive emissions from mercury cell chlor-alkali
plants sponsored by EPA enables us to conclude that the levels of
fugitive emissions for mercury chlor-alkali plants are much closer to
the assumed emissions in the part 61 Mercury NESHAP, of 1,300 grams/
day/plant (around 0.5 tons/yr/plant) than the levels assumed by NRDC (3
to 5 tons/yr/plant). The results of this study suggest that the
emissions are routinely less than half of the 1,300 grams/day level,
with overall fugitive emissions from the five operating facilities
estimated at less than 1 ton per year of mercury.'' (73 FR 32666). This
study, and the EPA's basis for their conclusion regarding the magnitude
of mercury emissions from these facilities, is discussed in detail in
the 2008 proposal (73 FR 33262 through 33267). In addition, the West
Virginia facility is required under an agreement with the Attorney
General of Maryland to limit mercury emissions from the facility to
less than 150 pounds per year.\25\
---------------------------------------------------------------------------

    \24\ Memorandum. Norwood, P., SC&A, Inc. to Mulrine, P., EPA.
Updated Cost Analysis for Conversion of Mercury Cell Chlor-Alkali
Plants to Membrane Cells. December 3, 2020.
    \25\ PPG to Lower Mercury Emissions at Natrium Plant.
Environmental Protection Online. August 25, 2009. Available at
https://eponline.com/Articles/2009/08/25/PPG-to-Lower-Mercury-Emissions-at-Natrium-Plant.aspx?Page=1&p=1.
---------------------------------------------------------------------------

    The EPA also examined the non-air impacts associated with switching
from mercury cell to non-mercury cell processes. For 2019, the West
Virginia facility reported a total of 898.1 pounds of non-air mercury
releases. This consists of 9 pounds to streams/water bodies, 883.3
pounds to Resource

Conservation and Recovery Act, Subtitle C Landfills, and 5.8 pounds to
other offsite sources. All these releases would be eliminated with the
conversion to non-mercury cell processes. While the promulgation of a
zero-mercury standard would eliminate these ongoing releases, there
would be environmental impacts associated with the dismantling and
decommissioning of the West Virginia mercury cell plant. In 2008, the
EPA estimated that these activities would result in over 4,000 pounds
of mercury in wastes (for example, from contaminated piping and other
equipment). We believe this estimate still represents a reasonable
estimate of the wastes that would be generated. In addition, the
facility would need to deal with the several hundred tons of elemental
mercury that is currently contained in the cells. The options for
storing this mercury are limited by the Mercury Export Ban Act of 2008.
The only realistic options for long-term storage of this mercury are to
send it to U.S. Department of Energy storage facilities or to continue
to store it onsite, both of which would result in ongoing costs to the
facility.
    Based on these factors, we are not proposing the option of a zero-
mercury standard as part of our CAA section 112(d)(6) technology review
for this source category at this time. Moreover, as we are now
uncertain whether the assessments supporting the 2011 proposed option
to require elimination of mercury emissions from existing sources
continue to represent accurate estimates of the costs of requiring such
elimination at the single remaining plant, we are proposing that
promulgating a zero-mercury standard for existing sources would not be
a reasonable beyond-the-floor MACT standard under CAA section
112(d)(2). However, we are soliciting comments, data, and other
information regarding these proposed decisions, including data and
information regarding the costs, cost effectiveness, non-air, and
economic impacts and other relevant information regarding whether the
NESHAP should include a zero-mercury standard as either a beyond-the-
floor MACT standard or a revised standard under the technology review,
and whether the proposed work practices for chlorine emissions and
proposed amendments to the mercury work practices would be necessary if
a zero-mercury standard were to be adopted. We intend to consider any
such submitted data and information, in addition to the data and
information contained in the records for the 2008 and 2011 proposals
and in this proposal, in reaching final conclusions under CAA sections
112(d)(2) and (6) regarding a zero-mercury standard.
    Based on the analyses discussed above, we are proposing the first
option, which is to amend the rule to require both a cell room
monitoring program and work practice standards. Specifically, the
proposed amendments would require, beginning 6 months after the final
rule is published, compliance with all work practices in the rule and
associated recordkeeping and reporting requirements plus the cell room
monitoring program. The exception is the work practice to develop and
follow a floor-level mercury vapor measurement program required at 40
CFR 63.8192(d). The cell room monitoring program is similar to the
floor-level program, except that it is more comprehensive and effective
as it detects increased mercury levels throughout the cell room, while
the floor-level program only detects increased levels near the floor-
level walkways.

E. What other actions are we proposing?

    In addition to the proposed actions described above, we are
proposing additional revisions to the NESHAP. We are proposing
revisions to the SSM provisions of the MACT rule in order to ensure
they are consistent with the decision in Sierra Club v. EPA, 551 F. 3d
1019 (D.C. Cir. 2008), in which the court vacated two provisions that
exempted sources from the requirement to comply with otherwise
applicable CAA section 112(d) emission standards during periods of SSM.
We also are proposing various other changes to require electronic
reporting of performance test results, notifications, and reports. We
are also proposing two amendments to correct errors and improve the
compliance provisions in the rule, as well as proposing amendments to
address applicability for thermal mercury recovery units when chlorine
and caustic are no longer produced in mercury cells. Our analyses and
proposed changes related to these issues are discussed below.
1. SSM
    In its 2008 decision in Sierra Club v. EPA, 551 F.3d 1019 (D.C.
Cir. 2008), the court 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 exemption
contained in 40 CFR 63.6(f)(1) and (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 standards apply continuously.
    Consistent with Sierra Club v. EPA, we are proposing the
elimination of the SSM exemptions in this NESHAP, and we are proposing
that the emissions standards will apply at all times. We are also
proposing several revisions to Table 5 (the General Provisions
Applicability Table) which are explained in more detail below. For
example, we are proposing to eliminate the incorporation of the General
Provisions' requirement that sources develop an SSM plan. We also are
proposing to eliminate and revise certain recordkeeping and reporting
requirements related to the SSM exemption as described below.
    The EPA has attempted to ensure that the provisions we are
proposing to eliminate are inappropriate, unnecessary, or redundant in
the absence of the SSM exemption. We are specifically seeking comment
on whether we have successfully done so.
    In proposing the standards in this rule, the EPA has considered
startup and shutdown periods and, for the reasons explained below, is
not proposing alternate standards for those periods. In 2011, the EPA
proposed similar revisions to the SSM provisions as those being
proposed here. During the comment period for the 2011 rule, the mercury
cell chlor-alkali industry indicated that there were safety concerns
associated with complying with the emissions standards during startup
for the hydrogen vent stream. The industry provided general information
that suggested that the control device could not be operated until the
exhaust stream composition could be regulated. However, no additional
data or information has been received since 2011, and it is unclear
whether the one operating facility in the source category would violate
its emissions standards during these startup times, whether the
facility has changed operations since the 2011 rule to be able to
comply with the emissions standards during startup, or whether there
are other practices or standards that could apply during these periods
to ensure emissions are limited or reduced. In the absence of evidence
that the emissions standards cannot be met during startup, the EPA is
proposing that the emissions standards apply at all times. However, we
solicit comment and detailed information for any situations where
separate standards, such as work practices, would be more appropriate
during periods of startup and shutdown rather than the current
standard.

    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. 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 court in U.S. Sugar Corp.
v. EPA, 830 F.3d 579, 606-610 (2016). 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 (or the average emission limitation achieved by the best
performing sources where, as here, there are fewer than 30 sources in
the source 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 court 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. The EPA is
not required to treat a malfunction 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 court recognized in U.S. Sugar Corp., accounting for
malfunctions in setting 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 offline 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 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 was 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 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 (2016).
a. General Duty, SSM Plan, and Compliance with Standards
    We are proposing to revise the General Provisions Applicability
Table (Table 10) entry for ``Sec.  63.6(a)-(g), (i), (j)'' to ``Sec.
63.6(a)-(g), (i), (j), except for (e)(1)(i) and (ii), (e)(3), and
(f)(1)'' and to add a new entry for ``Sec.  63.6(e)(1)(i) and (ii),
(e)(3), and (f)(1),'' in which a ``No'' entry would be included in the
column, ``Applies to Subpart IIIII.'' 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. We are proposing instead to add
general duty regulatory text at 40 CFR 63.8222 that reflects the
general duty to minimize emissions while eliminating the reference to
periods covered by an 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

and SSM events in describing the general duty. Therefore, the language
the EPA is proposing for 40 CFR 63.8222 does not include that language
from 40 CFR 63.6(e)(1). In addition, 40 CFR 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 63.8222. Generally, 40 CFR 63.6(e)(3) requires
development of an SSM plan and specifies SSM recordkeeping and
reporting requirements related to the SSM plan. As noted, the EPA is
proposing to remove 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. The current language of
40 CFR 63.6(f)(1) exempts sources from nonopacity standards during
periods of SSM. As discussed above, the court in Sierra Club v. EPA
vacated the exemptions contained in this provision and held that the
CAA requires that some CAA section 112 standards apply continuously.
Consistent with Sierra Club v. EPA, the EPA is proposing that the
standards in this rule apply at all times.
b. Performance Testing
    We are proposing to revise the General Provisions Applicability
Table (Table 10) entry for ``Sec.  63.7(a)(1), (b)-(h)'' to ``Sec.
63.7(a)-(h), except for (a)(2) and (e)(1)'' and to add a new entry for
``Sec.  63.7(e)(1),'' in which a ``No'' entry would be included in the
column, ``Applies to Subpart IIIII.'' Section 63.7(e)(1) describes
performance testing requirements. The EPA is instead proposing to add a
performance testing requirement at 40 CFR 63.8232(a). The performance
testing requirements we are proposing to add differ from the General
Provisions performance testing provisions in several respects. The
regulatory text removes the cross-reference to 40 CFR 63.7(e)(1) and
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. The proposed performance testing provisions will not allow
performance testing during startup and shutdown events. 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
proposing to add language 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 proposing to add to this
provision builds on that requirement and makes explicit the requirement
to record the information.
c. Monitoring
    We are proposing to revise the General Provisions Applicability
Table (Table 10) entry for ``Sec.  63.8(a)(1), (a)(3); (b); (c)(1)-(4),
(6)-(8); (d); (e); and (f)(1)-(5)'' to ``Sec.  63.8(a)(1), (a)(3); (b);
(c)(1)(ii), (2)-(4), (6)-(8); (d)(1)-(2); (e); and (f)(1)-(5)'' and to
add entries for ``Sec.  63.8(c)(1)(i) and (iii)'' and ``Sec.
63.8(d)(3)'' in which a ``No'' entry would be included in the column,
``Applies to Subpart IIIII,'' for the new entries. The cross-references
to the general duty and SSM plan requirements in subparagraphs 40 CFR
63.8(c)(1)(i) and (iii) 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)). In
addition, 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 proposing to add to the rule at 40 CFR 63.8242(a)(3)(v) text that is
identical to 40 CFR 63.8(d)(3) except for the final sentence with the
reference to SSM.
d. Recordkeeping and Reporting
    We are proposing to revise the General Provisions Applicability
Table (Table 10) entry for ``Sec.  63.10(a); (b)(1); (b)(2)(i)-(xii),
(xiv); (b)(3); (c); (d)(1)-(2), (4)-(5); (e); (f)'' to ``Sec.
63.10(a); (b)(1); (b)(2)(vi)-(xii), (xiv); (b)(3); (c)(1)-(14); (d)(1)-
(2), (4); (e); (f)'' and to add entries for ``Sec.  63.10(b)(2)(i)-
(v),'' ``Sec.  63.10(c)(15),'' and ``Sec.  63.10(d)(5),'' in which a
``No'' entry would be included in the column, ``Applies to Subpart
IIIII,'' for the new entries. Section 63.10(b)(2)(i) describes the
recordkeeping requirements during startup and shutdown. These recording
provisions are no longer necessary because the EPA is proposing that
recordkeeping and reporting applicable to normal operations will apply
to startup and shutdown. In the absence of special provisions
applicable to startup and shutdown, such as a startup and shutdown
plan, there is no reason to retain additional recordkeeping for startup
and shutdown periods.
    Section 63.10(b)(2)(ii) describes the recordkeeping requirements
during a malfunction. The EPA is proposing to add such requirement to
40 CFR 63.8256(a)(2). The regulatory text we are proposing to add
differs from 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 proposing that this
requirement apply to any deviation from an applicable requirement,
which would include malfunctions, and is requiring that the source
record the date, time, and duration of the deviation rather than the
``occurrence.'' The EPA is also proposing to add requirements to 40 CFR
63.8256(a)(2) 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
proposing to require that sources keep records of this information to
ensure 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.
    When applicable, 40 CFR 63.10(b)(2)(iv) 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 required by 40 CFR 63.8256(a)(2).

    When applicable, 40 CFR 63.10(b)(2)(v) 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.
    The EPA is also proposing that 40 CFR 63.10(c)(15) no longer
applies. When applicable, 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, specified in 40 CFR
63.6(e), to also satisfy the requirements of 40 CFR 63.10(c)(10)
through (12). The EPA is proposing to eliminate this requirement
because SSM plans would no longer be required, and, therefore, 40 CFR
63.10(c)(15) no longer serves any useful purpose for affected units.
    Section 63.10(d)(5) describes the reporting requirements for SSM.
To replace the General Provisions reporting requirement, the EPA is
proposing to add reporting requirements to 40 CFR 63.8254(b)(8) and
(9). This language differs from the General Provisions requirement in
that it does not require a stand-alone report. With this revision, we
are proposing that sources that fail to meet an applicable standard or
regulatory requirement at any time report the information concerning
such events in the semi-annual compliance report already required under
this rule. We are proposing 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 limit, 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 proposing 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 SSM plans would no longer be required. The proposed 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.
    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
plans would no longer be required.
2. Electronic Reporting
    The EPA is proposing that owners and operators of mercury cell
chlor-alkali plants submit electronic copies of required performance
test reports, notifications, and reports through the EPA's Central Data
Exchange (CDX) using the Compliance and Emissions Data Reporting
Interface (CEDRI). A description of the electronic data submission
process is provided in the memorandum, Electronic Reporting
Requirements for New Source Performance Standards (NSPS) and National
Emission Standards for Hazardous Air Pollutants (NESHAP) Rules,
available in the docket for this action. The proposed rule requires
that performance test results collected using test methods that are
supported by the EPA's Electronic Reporting Tool (ERT) as listed on the
ERT website \26\ at the time of the test be submitted in the format
generated through the use of the ERT or an electronic file consistent
with the xml schema on the ERT website, and other performance test
results be submitted in portable document format (PDF) using the
attachment module of the ERT. The proposed rule requires that each
notification--such as a Revised NOCS--and each report--such as a
semiannual report--be submitted as a PDF upload in CEDRI.
---------------------------------------------------------------------------

    \26\ https://www.epa.gov/electronic-reporting-air-emissions/electronic-reporting-tool-ert.
---------------------------------------------------------------------------

    Additionally, the EPA has identified two broad circumstances in
which electronic reporting extensions may be provided. These
circumstances are (1) outages of the EPA's CDX or CEDRI which preclude
an owner or operator from accessing the system and submitting required
reports and (2) force majeure events, which are defined as events that
will be or have been caused by circumstances beyond the control of the
affected facility, its contractors, or any entity controlled by the
affected facility that prevent an owner or operator from complying with
the requirement to submit a report electronically. Examples of force
majeure events are acts of nature, acts of war or terrorism, or
equipment failure or safety hazards beyond the control of the facility.
The EPA is providing these potential extensions to protect owners and
operators from noncompliance in cases where they cannot successfully
submit a report by the reporting deadline for reasons outside of their
control. In both circumstances, the decision to accept the claim of
needing additional time to report is within the discretion of the
Administrator, and reporting should occur as soon as possible.
    The electronic submittal of the reports addressed in this proposed
rulemaking 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. Moreover,
electronic reporting is consistent with the EPA's plan \27\ to
implement Executive Order 13563 and is in keeping with the EPA's
agency-wide policy \28\ developed in response to the White House's
Digital Government Strategy.\29\ For more information on the benefits
of electronic reporting, see the memorandum, Electronic Reporting
Requirements for New Source Performance Standards (NSPS) and National
Emission Standards for

Hazardous Air Pollutants (NESHAP) Rules, referenced earlier in this
section.
---------------------------------------------------------------------------

    \27\ EPA's Final Plan for Periodic Retrospective Reviews, August
2011. Available at: https://www.regulations.gov/document?D=EPA-HQ-OA/2011/0156/0154.
    \28\ E-Reporting Policy Statement for EPA Regulations, September
2013. Available at: https://www.epa.gov/sites/production/files/2016-03/documents/epa-ereporting-policy-statement-2013/09/30.pdf.
    \29\ Digital Government: Building a 21st Century Platform to
Better Serve the American People, May 2012. Available at: https://obamawhitehouse.archives.gov/sites/default/files/omb/egov/digital-government/digital-government.html.
---------------------------------------------------------------------------

3. Compliance Provisions Rule Corrections
    We are proposing amendments to correct errors and improve the
compliance provisions of the rule. These changes, which are described
below, were included in the March 14, 2011, proposal (76 FR 13865) and
the June 2008 proposal (73 FR 33275).
a. Detection Limit for Mercury Monitor Analyzers
    Paragraph 63.8242 (a)(2) requires mercury continuous monitor
analyzers to have a detector capable of detecting a mercury
concentration at or below 0.5 times the mercury concentration level
measured during the performance test. Since promulgation of the NESHAP,
we have realized that detecting a concentration of 0.5 times the
mercury concentration could, in cases of low mercury concentrations, be
infeasible for the monitoring devices on the market. Information
available to us at this time shows that 0.1 [mu]g/m3 is the detection
limit of commonly commercially available analyzers. Analyzers with
detection limits at this level are more than sufficient to determine
compliance with the limitations in the NESHAP. Therefore, we are
proposing to revise this paragraph to require a detector capable of
detecting a mercury concentration at or below 0.5 times the mercury
concentration measured during the test or 0.1 [mu]g/m3.
b. Averaging Period for Mercury Recovery Unit Compliance
    The NESHAP is inconsistent as to whether the rule requires a daily
average or an hourly average to determine continuous compliance with
the emissions standard for mercury recovery units. While 40 CFR
63.8243(b) indicates that this averaging period is daily, another
paragraph, 40 CFR 63.8246(b), states that limit is based on the average
hourly concentration of mercury. It was our intention for compliance to
be based on a daily average, and the inclusion of ``hourly'' in 40 CFR
63.8246 (b) was a drafting error. Therefore, we are proposing to
correct this error by replacing ``hourly'' in 40 CFR 63.8246(b) with
``daily.''
4. Applicability for Mercury Recovery Units
    As discussed previously, all but one mercury cell plant has closed
or converted to membrane cells since the promulgation of the 2003
Mercury Cell Chlor-Alkali Plants MACT. When these situations have
occurred at plants with on-site thermal mercury recovery units, it has
been common for these units to continue to operate to assist in the
treatment of wastes associated with the shutdown/conversion. We are not
aware of any mercury recovery units still in operation and the
Westlake, West Virginia, facility does not operate a thermal mercury
recovery unit that is subject to the emission limitations in the rule.
Regardless, under the applicability of the 2003 Mercury Cell Chlor-
Alkali Plants MACT, these units would no longer be an affected source
after the chlorine production facility ceased operating. Furthermore,
while the NESHAP already effectively prohibits the construction or
reconstruction of a new mercury cell chlor-alkali production facility,
it does not do the same for mercury recovery facilities. Therefore,
there exists the possibility that there is an existing mercury recovery
unit of which we are unaware or that a mercury recovery facility
subject to new source standards could be constructed or reconstructed.
Therefore, these proposed amendments would require any mercury recovery
unit to comply with the requirements of the Mercury Cell Chlor-Alkali
Plants MACT for such units, as long as the mercury recovery unit
operates to recover mercury from wastes generated by a mercury cell
chlor-alkali plant.

F. What compliance dates are we proposing?

    From our assessment of the time frame needed for compliance with
the entirety of the revised requirements, the EPA considers a period of
6 months to be the most expeditious compliance period practicable and,
thus, is proposing that the affected source be in compliance with all
of this regulation's revised requirements within 6 months of the
regulation's effective date.
    For existing sources, we are proposing two changes to the work
practice standards. While these proposed work practice standards are
based on the practices in place at the single facility in the source
category, they will require some modifications to the procedures
currently employed at the facility. Specifically, they will need to
develop and implement a recordkeeping system to record and maintain the
records required for the mercury cell work practices and to incorporate
the required material in the requisite reports. Also, while the
facility has standard operating procedures in place to reduce fugitive
emissions of chlorine upon which the proposed requirements are based,
they will need to develop and implement a recordkeeping system to
record and maintain the records required for the fugitive chlorine
inspection requirements and to incorporate the required material in the
requisite reports. We propose that a 6-month period of time would be
adequate for these activities.
    In addition, we are proposing to add a requirement that
notifications, performance test results, and compliance reports be
submitted electronically. We are also proposing to change the
requirements for SSM by removing the exemption from the requirements to
meet the standards during SSM periods and by removing the requirement
to develop and implement an SSM plan. Our experience with similar
industries that are required to convert reporting mechanisms to install
necessary hardware and software, become familiar with the process of
submitting performance test results electronically through the EPA's
CEDRI, test these new electronic submission capabilities, and reliably
employ electronic reporting shows that a time period of a minimum of 3
months, and, more typically, 6 months is generally necessary to
successfully accomplish these revisions. Our experience with similar
industries further shows that this sort of regulated facility generally
requires a time period of 6 months to read and understand the amended
rule requirements; to evaluate their operations to ensure that they can
meet the standards during periods of startup and shutdown as defined in
the rule and make any necessary adjustments; and to update their
operation, maintenance, and monitoring plans to reflect the revised
requirements.
    We solicit comment on the proposed compliance periods, and we
specifically request submission of information from sources in this
source category regarding specific actions that would need to be
undertaken to comply with the proposed amended requirements and the
time needed to make the adjustments for compliance with any of the
revised requirements. We note that information provided may result in
changes to the proposed compliance dates.

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

    There is only one mercury cell chlor-alkali facility currently
operating in the U.S. The facility will be subject to the Mercury Cell
Chlor-Alkali Plants NESHAP affected by the proposed amendments to 40
CFR part 63, subpart IIIII.

B. What are the air quality impacts?

    We are not proposing revisions to the mercury emission limits for
process vents other than to make them applicable during SSM periods,
and we do not anticipate any air quality impacts as a result of this
proposed amendment, since the one subject facility is already in
compliance with emission limits during all periods, including SSM. We
are proposing changes to require both the mercury cell room monitoring
program and the work practice standards for fugitive mercury emissions,
and are proposing new work practice standards for fugitive chlorine
emissions. However, these proposed changes are based on the current
practices in place at the one subject facility. Therefore, we also do
not anticipate any air quality impacts as a result of these proposed
amendments to the work practices.

C. What are the cost impacts?

    As noted earlier, the single facility in the source category is
complying with the alternative cell room monitoring program. While not
currently required, the facility is also implementing the work
practices. Therefore, the only costs that would be incurred with the
proposed requirement to comply with both the cell room monitoring
program and the work practices are those costs associated with the work
practice recordkeeping and reporting. We estimate these costs to be
$36,000 per year for the mercury work practices recordkeeping and
reporting and $49,000 for the chlorine inspection program recordkeeping
and reporting (all costs in 2020 dollars). Another way to present these
costs is to show them in terms of present value, in which the stream
over time of costs per year for the proposal requirement is discounted
to the present day. For this proposal, the present value of the costs
in total is $445,000 in 2020 dollars, calculated over an 8-year period
from 2022 to 2029 (assuming promulgation in 2021), estimated at a 7
percent discount rate and discounted to 2020. The equivalent annualized
value of these costs, which is an annualized value of costs consistent
with the present value, is $74,500 in 2020 dollars, and also estimated
at a 7 percent discount rate and discounted to 2020.

D. What are the economic impacts?

    Economic impact analyses focus on changes in market prices and
output levels. If changes in market prices and output levels in the
primary markets as a result of complying with the rule are significant
enough, impacts on other markets may also be examined. Both the
magnitude of costs needed to comply with a proposed rule and the
distribution of these costs among affected facilities can have a role
in determining how the market prices and output levels will change in
response to a proposed rule. The total cost associated with this
proposed rule is estimated to be $85,000 per year in 2020 dollars,
which is the cost associated with additional recordkeeping and
reporting costs. The economic impact associated with this cost,
calculated as an annual cost per sales, for the parent firm owning the
single affected facility is 0.001 percent, and is not expected to
result in a significant market impact, regardless of whether it is
fully passed on to the consumer or fully absorbed by the affected firm.

E. What are the benefits?

    The EPA does not anticipate reductions in HAP emissions as a result
of the proposed amendments to the Mercury Cell Chlor-Alkali Plants
NESHAP. However, the proposed amendments would improve the rule by
codifying the existing practices to reduce emissions into enforceable
requirements, ensuring that the standards apply at all times. Also,
requiring electronic submittal of initial notifications, performance
test results, and reports will increase the usefulness of the data and
ultimately result in less burden on the regulated community. Because
these proposed amendments are not considered economically significant,
as defined by Executive Order 12866, and because no emission reductions
were estimated, we did not estimate any health benefits from reducing
emissions.

VI. Request for Comments

    We solicit comments on this proposed action. In addition to general
comments on this proposed action, we are also interested in additional
data that may improve the risk assessments and other analyses. We are
specifically interested in receiving any improvements to the data used
in the site-specific emissions profiles used for risk modeling. Such
data should include supporting documentation in sufficient detail to
allow characterization of the quality and representativeness of the
data or information. Section VII of this preamble provides more
information on submitting data.

VII. Submitting Data Corrections

    The site-specific emissions profiles used in the source category
risk and demographic analyses and instructions are available for
download on the RTR website at https://www.epa.gov/stationary-sources-air-pollution/mercury-cell-chloralkali-plants-national-emissions-standards. The data files include detailed information for each HAP
emissions release point for the facilities in the source category.
    If you believe that the data are not representative or are
inaccurate, please identify the data in question, provide your reason
for concern, and provide any ``improved'' data that you have, if
available. When you submit data, we request that you provide
documentation of the basis for the revised values to support your
suggested changes. To submit comments on the data downloaded from the
RTR website, complete the following steps:
    1. Within this downloaded file, enter suggested revisions to the
data fields appropriate for that information.
    2. Fill in the commenter information fields for each suggested
revision (i.e., commenter name, commenter organization, commenter email
address, commenter phone number, and revision comments).
    3. Gather documentation for any suggested emissions revisions
(e.g., performance test reports, material balance calculations).
    4. Send the entire downloaded file with suggested revisions in
Microsoft[supreg] Access format and all accompanying documentation to
Docket ID No. EPA-HQ-OAR-2020-0560 (through the method described in the
ADDRESSES section of this preamble).
    5. If you are providing comments on a single facility or multiple
facilities, you need only submit one file for all facilities. The file
should contain all suggested changes for all sources at that facility
(or facilities). We request that all data revision comments be
submitted in the form of updated Microsoft[supreg] Excel files that are
generated by the Microsoft[supreg] Access file. These files are
provided on the project website at https://www.epa.gov/stationary-sources-air-pollution/mercury-cell-chloralkali-plants-national-emissions-standards.

VIII. Statutory and Executive Order Reviews

    Additional information about these statutes and Executive Orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.

A. Executive Orders 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review

    This action is not a significant regulatory action and was,
therefore, not submitted to OMB for review.

B. Executive Order 13771: Reducing Regulations and Controlling
Regulatory Costs

    This action is not expected to be an Executive Order 13771
regulatory action because this action is not significant under
Executive Order 12866.

C. Paperwork Reduction Act (PRA)

    The information collection activities in this rule have been
submitted for approval to OMB under the PRA. The Information Collection
Request (ICR) document that the EPA prepared has been assigned EPA ICR
number 2046.10. You can find a copy of the ICR in the docket for this
rule, and it is briefly summarized here.
    The information requirements in this rulemaking are based on the
notification, recordkeeping, and reporting requirements in the NESHAP
General Provisions (40 CFR part 63, subpart A), which are mandatory for
all operators subject to national emission standards. These
notifications, reports, and records are essential in determining
compliance, and are specifically authorized by CAA section 114 (42
U.S.C. 7414). All information submitted to the EPA pursuant to the
recordkeeping and reporting requirements for which a claim of
confidentiality is made is safeguarded according to Agency policies set
forth in 40 CFR part 2, subpart B.
    The EPA is proposing amendments that revise provisions pertaining
to emissions during periods of SSM; add requirements for electronic
reporting of notifications and reports and performance test results;
and make other minor clarifications and corrections. This information
will be collected to assure compliance with the Mercury Cell Chlor-
Alkali Plants NESHAP.
    Respondents/affected entities: Owners or operators of mercury cell
chlor-alkali facilities.
    Respondent's obligation to respond: Mandatory (42 U.S.C. 7414).
    Estimated number of respondents: One total for the source category.
This facility is already a respondent and no new facilities are
expected to become respondents as a result of this proposed action.
    Frequency of response: Initially, occasionally, and semi-annually.
    Total estimated burden: 3,567 total hours (per year) for the source
category, of which 1,680 are estimated as a result of this action.
Burden is defined at 5 CFR 1320.3(b).
    Total estimated cost: The total estimated cost of the rule is
$428,000 (per year) for the source category, including $8,200
annualized capital or operation and maintenance costs. We estimate that
$0 of the $8,200 in total annualized capital or operation and
maintenance costs is a result of this proposed action. Recordkeeping
and reporting costs of $205,000 estimated as a result of this action
are included in the $428,000 in total costs.
    An agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless it displays a
currently valid OMB control number. The OMB control numbers for the
EPA's regulations in 40 CFR are listed in 40 CFR part 9.
    Submit your comments on the Agency's need for this information, the
accuracy of the provided burden estimates, and any suggested methods
for minimizing respondent burden to the EPA using the docket identified
at the beginning of this rule. You may also send your ICR-related
comments to OMB's Office of Information and Regulatory Affairs via
email to<EMAIL_ADDRESS>Attention: Desk Officer for the
EPA. Since OMB is required to make a decision concerning the ICR
between 30 and 60 days after receipt, OMB must receive comments no
later than February 8, 2021. The EPA will respond to any ICR-related
comments in the final rule.

D. Regulatory Flexibility Act (RFA)

    I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. The parent
company for the single affected facility in the source category is not
a small entity given the Small Business Administration small business
size definition for this industry (1,000 employees or greater for NAICS
325180).

E. Unfunded Mandates Reform Act (UMRA)

    This action does not contain an unfunded mandate of $100 million or
more as described in UMRA, 2 U.S.C. 1531-1538, and does not
significantly or uniquely affect small governments. The action imposes
no enforceable duty on any state, local, or tribal governments or the
private sector.

F. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.

G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments

    This action does not have tribal implications, as specified in
Executive Order 13175. The mercury cell chlor-alkali plant affected by
this proposed action is not owned or operated by tribal governments or
located within tribal lands. Thus, Executive Order 13175 does not apply
to this action.

H. Executive Order 13045: Protection of Children from Environmental
Health Risks and Safety Risks

    This action is not subject to Executive Order 13045 because it is
not economically significant as defined in Executive Order 12866, and
because the EPA does not believe the environmental health or safety
risks addressed by this action present a disproportionate risk to
children. As the proposed rule amendments would not change emissions of
HAP and risk to anyone exposed, the EPA estimates that the proposed
rule amendments would have no effect on risks to children. This
action's health and risk assessments are contained in section IV.B of
this preamble and the document, Residual Risk Assessment for the
Mercury Cell Chlor-Alkali Plant Source Category in Support of the Risk
and Technology Review 2020 Proposed Rule, which is available in the
docket for this rulemaking.

I. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use

    This action is not subject to Executive Order 13211, because it is
not a significant regulatory action under Executive Order 12866.

J. National Technology Transfer and Advancement Act (NTTAA)

    This rulemaking does not change the existing technical standards in
the rule.

K. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations

    The EPA believes that this action does not have disproportionately
high and adverse human health or environmental effects on minority
populations, low-income populations, and/or indigenous peoples, as
specified in Executive Order 12898 (59 FR 7629, February 16, 1994)
because it does not change the level of environmental protection for
any affected populations and does not have any disproportionately high
and adverse human health or environmental effects on any population,
including any

minority, low income, or indigenous populations.
    To gain a better understanding of the source category and near
source populations, the EPA conducted a demographic analysis for
mercury cell chlor-alkali facilities to identify any overrepresentation
of minority, low income, or indigenous populations with cancer risks
above 1-in-1 million. This analysis only gives some indication of the
prevalence of sub-populations that may be exposed to air pollution from
the sources; it does not identify the demographic characteristics of
the most highly affected individuals or communities, nor does it
quantify the level of risk faced by those individuals or communities.
More information on the source category's risk can be found in section
IV of this preamble. The complete demographic analysis results and the
details concerning its development are presented in the technical
report, Risk and Technology Review--Analysis of Demographic Factors for
Populations Living Near Mercury Cell Chlor-Alkali Facilities, available
in the docket for this action.

List of Subjects in 40 CFR Part 63

    Environmental protection, Air pollution control, Hazardous
substances, Reporting and recordkeeping requirements.

Andrew Wheeler,
Administrator.
[FR Doc. 2021-00174 Filed 1-7-21; 8:45 am]
BILLING CODE 6560-50-P


[Federal Register Volume 79, Number 84 (Thursday, May 1, 2014)]
[Notices]
[Page 24740]
[FR Doc No: 2014-09984]

-----------------------------------------------------------------------

DEPARTMENT OF HOMELAND SECURITY

Federal Emergency Management Agency

[Internal Agency Docket No. FEMA-4171-DR; Docket ID FEMA-2014-0003]

Tennessee; Major Disaster and Related Determinations

AGENCY: Federal Emergency Management Agency, DHS.

ACTION: Notice.

-----------------------------------------------------------------------

SUMMARY: This is a notice of the Presidential declaration of a major
disaster for the State of Tennessee (FEMA-4171-DR), dated April 11,
2014, and related determinations.

DATES: Effective Date: April 11, 2014.

FOR FURTHER INFORMATION CONTACT: Dean Webster, Office of Response and
Recovery, Federal Emergency Management Agency, 500 C Street SW.,
Washington, DC 20472,<PHONE_NUMBER>.

SUPPLEMENTARY INFORMATION: Notice is hereby given that, in a letter
dated April 11, 2014, the President issued a major disaster declaration
under the authority of the Robert T. Stafford Disaster Relief and
Emergency Assistance Act, 42 U.S.C. 5121 et seq. (the ``Stafford
Act''), as follows:

    I have determined that the damage in certain areas of the State
of Tennessee resulting from a severe winter storm during the period
of March 2-4, 2014, is of sufficient severity and magnitude to
warrant a major disaster declaration under the Robert T. Stafford
Disaster Relief and Emergency Assistance Act, 42 U.S.C. 5121 et seq.
(the ``Stafford Act''). Therefore, I declare that such a major
disaster exists in the State of Tennessee.
    In order to provide Federal assistance, you are hereby
authorized to allocate from funds available for these purposes such
amounts as you find necessary for Federal disaster assistance and
administrative expenses.
    You are authorized to provide Public Assistance in the
designated areas and Hazard Mitigation throughout the State.
Consistent with the requirement that Federal assistance be
supplemental, any Federal funds provided under the Stafford Act for
Hazard Mitigation will be limited to 75 percent of the total
eligible costs. Federal funds provided under the Stafford Act for
Public Assistance also will be limited to 75 percent of the total
eligible costs, with the exception of projects that meet the
eligibility criteria for a higher Federal cost-sharing percentage
under the Public Assistance Alternative Procedures Pilot Program for
Debris Removal implemented pursuant to Section 428 of the Stafford
Act.
    Further, you are authorized to make changes to this declaration
for the approved assistance to the extent allowable under the
Stafford Act.

    The Federal Emergency Management Agency (FEMA) hereby gives notice
that pursuant to the authority vested in the Administrator, under
Executive Order 12148, as amended, Terry L. Quarles, of FEMA is
appointed to act as the Federal Coordinating Officer for this major
disaster.
    The following areas of the State of Tennessee have been designated
as adversely affected by this major disaster: Carroll, Cheatham,
Dickson, Haywood, Houston, Madison, Shelby, and Tipton Counties for
Public Assistance. All counties within the State of Tennessee are
eligible to apply for assistance under the Hazard Mitigation Grant
Program.

    The following Catalog of Federal Domestic Assistance Numbers
(CFDA) are to be used for reporting and drawing funds: 97.030,
Community Disaster Loans; 97.031, Cora Brown Fund; 97.032, Crisis
Counseling; 97.033, Disaster Legal Services; 97.034, Disaster
Unemployment Assistance (DUA); 97.046, Fire Management Assistance
Grant; 97.048, Disaster Housing Assistance to Individuals and
Households In Presidentially Declared Disaster Areas; 97.049,
Presidentially Declared Disaster Assistance--Disaster Housing
Operations for Individuals and Households; 97.050, Presidentially
Declared Disaster Assistance to Individuals and Households--Other
Needs; 97.036, Disaster Grants--Public Assistance (Presidentially
Declared Disasters); 97.039, Hazard Mitigation Grant.

W. Craig Fugate,
Administrator, Federal Emergency Management Agency.
[FR Doc. 2014-09984 Filed 4-30-14; 8:45 am]
BILLING CODE 9111-23-P