of PB-HAP emissions to determine whether a refined assessment of the
impacts from multipathway exposures is necessary. This determination is
based on the results of a tiered screening analysis that relies on the
outputs from models that estimate environmental pollutant
concentrations and human exposures for four PB-HAP. Two important types
of uncertainty associated with the use of these models in RTR risk
assessments and inherent to any assessment that relies on environmental
modeling are model uncertainty and input uncertainty.\20\
---------------------------------------------------------------------------

    \20\ In the context of this discussion, the term ``uncertainty''
as it pertains to exposure and risk encompasses both variability in
the range of expected inputs and screening results due to existing
spatial, temporal, and other factors, as well as uncertainty in
being able to accurately estimate the true result.
---------------------------------------------------------------------------

    Model uncertainty concerns whether the selected models are
appropriate for the assessment being conducted and whether they
adequately represent the actual processes that might occur for that
situation. An example of model uncertainty is the question of whether
the model adequately describes the movement of a pollutant through the
soil. This type of uncertainty is difficult to quantify. However, based
on feedback received from previous SAB reviews and other reviews, we
are confident that the models used in the screen are

appropriate and state-of-the-art for the multipathway risk assessments
conducted in support of RTR.
    Input uncertainty is concerned with how accurately the models have
been configured and parameterized for the assessment at hand. For Tier
1 of the multipathway screen, we configured the models to avoid
underestimating exposure and risk. This was accomplished by selecting
upper-end values from nationally-representative datasets for the more
influential parameters in the environmental model, including selection
and spatial configuration of the area of interest, lake location and
size, meteorology, surface water and soil characteristics and structure
of the aquatic food web. We also assume an ingestion exposure scenario
and values for human exposure factors that represent reasonable maximum
exposures. The multipathway screens include some hypothetical elements,
namely the hypothetical farmer and fisher scenarios. It is important to
note that even though the multipathway assessment has been conducted,
no data exist to verify the existence of either the farmer or fisher
scenario outlined above.
    In Tier 2 of the multipathway assessment, we refine the model
inputs to account for meteorological patterns in the vicinity of the
facility versus using upper-end national values and we identify the
actual location of lakes near the facility rather than the default lake
location that we apply in Tier 1. By refining the screening approach in
Tier 2 to account for local geographical and meteorological data, we
decrease the likelihood that concentrations in environmental media are
overestimated, thereby increasing the usefulness of the screen. The
assumptions and the associated uncertainties regarding the selected
ingestion exposure scenario are the same for all the Tiers.
    For both Tiers 1 and 2 of the multipathway assessment, our approach
to addressing model input uncertainty is generally cautious. We choose
model inputs from the upper end of the range of possible values for the
influential parameters used in the models, and we assume that the
exposed individual exhibits ingestion behavior that would lead to a
high total exposure. This approach reduces the likelihood of not
identifying high risks for adverse impacts.
    Despite the uncertainties, when individual pollutants or facilities
do screen out, we are confident that the potential for adverse
multipathway impacts on human health is very low. On the other hand,
when individual pollutants or facilities do not screen out, it does not
mean that multipathway impacts are significant, only that we cannot
rule out that possibility and that a refined multipathway screening
analysis for the site might be necessary to obtain a more accurate risk
characterization for the source category.
    For further information on uncertainties and the multipathway
screening methods, refer to the Appendix 5 of the Residual Risk
Assessment for the Secondary Aluminum Production Source Category in
Support of the 2014 Supplemental Proposal.
    We completed a Tier 3 refined multipathway screening analysis for
this supplemental proposal for assessing multipathway risks. This
assessment contains less uncertainty compared to the Tier 1 and Tier 2
screens. The Tier 3 screen reduces uncertainty through improved lake
evaluations used in the Tier 2 screen and by calculating the amount of
mass lost to the upper air sink through plume rise. Nevertheless, some
uncertainties also exist with these refined assessments. The Tier 3
multipathway screen and related uncertainties are described in detail
in the Residual Risk Assessment for the Secondary Aluminum Production
Source Category in Support of the 2014 Supplemental Proposal, which is
available in the docket for this action.
f. Uncertainties in the Environmental Risk Screening Assessment
    For each source category, we generally rely on site-specific levels
of environmental HAP emissions to perform an environmental screening
assessment. The environmental screening assessment is based on the
outputs from models that estimate environmental HAP concentrations. The
same models, specifically the TRIM.FaTE multipathway model and the
AERMOD air dispersion model, are used to estimate environmental HAP
concentrations for both the human multipathway screening analysis and
for the environmental screening analysis. Therefore, both screening
assessments have similar modeling uncertainties.
    Two important types of uncertainty associated with the use of these
models in RTR environmental screening assessments--and inherent to any
assessment that relies on environmental modeling--are model uncertainty
and input uncertainty.\21\
---------------------------------------------------------------------------

    \21\ In the context of this discussion, the term
``uncertainty,'' as it pertains to exposure and risk assessment,
encompasses both variability in the range of expected inputs and
screening results due to existing spatial, temporal and other
factors, as well as uncertainty in being able to accurately estimate
the true result.
---------------------------------------------------------------------------

    Model uncertainty concerns whether the selected models are
appropriate for the assessment being conducted and whether they
adequately represent the movement and accumulation of environmental HAP
emissions in the environment. For example, does the model adequately
describe the movement of a pollutant through the soil? This type of
uncertainty is difficult to quantify. However, based on feedback
received from previous SAB reviews and other reviews, we are confident
that the models used in the screen are appropriate and state-of-the-art
for the environmental risk assessments conducted in support of our RTR
analyses.
    Input uncertainty is concerned with how accurately the models have
been configured and parameterized for the assessment at hand. For Tier
1 of the environmental screen for PB-HAP, we configured the models to
avoid underestimating exposure and risk to reduce the likelihood that
the results indicate the risks are lower than they actually are. This
was accomplished by selecting upper-end values from nationally-
representative datasets for the more influential parameters in the
environmental model, including selection and spatial configuration of
the area of interest, the location and size of any bodies of water,
meteorology, surface water and soil characteristics and structure of
the aquatic food web. In Tier 1, we used the maximum facility-specific
emissions for the PB-HAP (other than lead compounds, which were
evaluated by comparison to the secondary lead NAAQS) that were included
in the environmental screening assessment and each of the media when
comparing to ecological benchmarks. This is consistent with the
conservative design of Tier 1 of the screen. In Tier 2 of the
environmental screening analysis for PB-HAP, we refine the model inputs
to account for meteorological patterns in the vicinity of the facility
versus using upper-end national values, and we identify the locations
of water bodies near the facility location. By refining the screening
approach in Tier 2 to account for local geographical and meteorological
data, we decrease the likelihood that concentrations in environmental
media are overestimated, thereby increasing the usefulness of the
screen. To better represent widespread impacts, the modeled soil
concentrations are averaged in Tier 2 to obtain one average soil
concentration value for each facility and for each PB-HAP. For PB-HAP
concentrations in water, sediment and fish tissue, the

highest value for each facility for each pollutant is used.
    For the environmental screening assessment for acid gases, we
employ a single-tiered approach. We use the modeled air concentrations
and compare those with ecological benchmarks.
    For both Tiers 1 and 2 of the environmental screening assessment,
our approach to addressing model input uncertainty is generally
cautious. We choose model inputs from the upper end of the range of
possible values for the influential parameters used in the models, and
we assume that the exposed individual exhibits ingestion behavior that
would lead to a high total exposure. This approach reduces the
likelihood of not identifying potential risks for adverse environmental
impacts.
    Uncertainty also exists in the ecological benchmarks for the
environmental risk screening analysis. We established a hierarchy of
preferred benchmark sources to allow selection of benchmarks for each
environmental HAP at each ecological assessment endpoint. In general,
EPA benchmarks used at a programmatic level (e.g., Office of Water,
Superfund Program) were used, if available. If not, we used EPA
benchmarks used in regional programs (e.g., Superfund Program). If
benchmarks were not available at a programmatic or regional level, we
used benchmarks developed by other agencies (e.g., NOAA) or by state
agencies.
    In all cases (except for lead compounds, which were evaluated
through a comparison to the NAAQS), we searched for benchmarks at the
following three effect levels, as described in section III.A.6 of this
preamble:
    1. A no-effect level (i.e., NOAEL).
    2. Threshold-effect level (i.e., LOAEL).
    3. Probable effect level (i.e., PEL).
    For some ecological assessment endpoint/environmental HAP
combinations, we could identify benchmarks for all three effect levels,
but for most, we could not. In one case, where different agencies
derived significantly different numbers to represent a threshold for
effect, we included both. In several cases, only a single benchmark was
available. In cases where multiple effect levels were available for a
particular PB-HAP and assessment endpoint, we used all of the available
effect levels to help us to determine whether risk exists and if the
risks could be considered significant and widespread.
    The EPA evaluates the following seven HAP in the environmental risk
screening assessment: cadmium, D/F, POM, mercury (both inorganic
mercury and methyl mercury), lead compounds, HCl and HF, where
applicable. These seven HAP represent pollutants that can cause adverse
impacts for plants and animals either through direct exposure to HAP in
the air or through exposure to HAP that is deposited from the air onto
soils and surface waters. These seven HAP also represent those HAP for
which we can conduct a meaningful environmental risk screening
assessment. For other HAP not included in our screening assessment, the
model has not been parameterized such that it can be used for that
purpose. In some cases, depending on the HAP, we may not have
appropriate multipathway models that allow us to predict the
concentration of that pollutant. The EPA acknowledges that other HAP
beyond the seven HAP that we are evaluating may have the potential to
cause adverse environmental effects and, therefore, the EPA may
evaluate other relevant HAP in the future, as modeling science and
resources allow.
    Further information on uncertainties and the Tier 1 and 2 screening
methods is provided in Appendix 5 of the Residual Risk Assessment for
the Secondary Aluminum Production Source Category in Support of the
2014 Supplemental Proposal, available in the docket for this action.

B. How did we consider the risk results in making decisions for this
supplemental proposal?

    As discussed in section II.A of this preamble, in evaluating and
developing standards under CAA section 112(f)(2), we apply a two-step
process to address residual risk. In the first step, the EPA determines
whether risks are acceptable. This determination ``considers all health
information, including risk estimation uncertainty, and includes a
presumptive limit on maximum individual lifetime [cancer] risk (MIR) of
approximately [1-in-10 thousand] [i.e., 100-in-1 million].'' 54 FR
38045, September 14, 1989. If risks are unacceptable, the EPA must
determine the emissions standards necessary to bring risks to an
acceptable level without considering costs. In the second step of the
process, the EPA considers whether the emissions standards provide an
ample margin of safety ``in consideration of all health information,
including the number of persons at risk levels higher than
approximately 1-in-1 million, as well as other relevant factors,
including costs and economic impacts, technological feasibility, and
other factors relevant to each particular decision.'' Id. The EPA must
promulgate emission standards necessary to provide an ample margin of
safety.
    In past residual risk actions, the EPA considered a number of human
health risk metrics associated with emissions from the categories under
review, including the MIR, the number of persons in various risk
ranges, cancer incidence, the maximum non-cancer HI and the maximum
acute non-cancer hazard. See, e.g., 72 FR 25138, May 3, 2007; 71 FR
42724, July 27, 2006. The EPA considered this health information for
both actual and allowable emissions. See, e.g., 75 FR 65068, October
21, 2010; 75 FR 80220, December 21, 2010; 76 FR 29032, May 19, 2011.
The EPA also discussed risk estimation uncertainties and considered the
uncertainties in the determination of acceptable risk and ample margin
of safety in these past actions. The EPA considered this same type of
information in support of this action.
    The agency is considering these various measures of health
information to inform our determinations of risk acceptability and
ample margin of safety under CAA section 112(f). As explained in the
Benzene NESHAP, ``the first step judgment on acceptability cannot be
reduced to any single factor'' and, thus, ``[t]he Administrator
believes that the acceptability of risk under [previous] section 112 is
best judged on the basis of a broad set of health risk measures and
information.'' 54 FR 38046, September 14, 1989. Similarly, with regard
to the ample margin of safety determination, ``the Agency again
considers all of the health risk and other health information
considered in the first step. Beyond that information, additional
factors relating to the appropriate level of control will also be
considered, including cost and economic impacts of controls,
technological feasibility, uncertainties, and any other relevant
factors.'' Id.
    The Benzene NESHAP approach provides flexibility regarding factors
the EPA may consider in making determinations and how the EPA may weigh
those factors for each source category. In responding to comment on our
policy under the Benzene NESHAP, the EPA explained that:

``[t]he policy chosen by the Administrator permits consideration of
multiple measures of health risk. Not only can the MIR figure be
considered, but also incidence, the presence of non-cancer health
effects, and the uncertainties of the risk estimates. In this way,
the effect on the most exposed individuals can be reviewed as well
as the impact on the general public. These factors can then be
weighed in each individual case. This approach complies with the
Vinyl Chloride mandate that the Administrator

ascertain an acceptable level of risk to the public by employing
[her] expertise to assess available data. It also complies with the
Congressional intent behind the CAA, which did not exclude the use
of any particular measure of public health risk from the EPA's
consideration with respect to CAA section 112 regulations, and
thereby implicitly permits consideration of any and all measures of
health risk which the Administrator, in [her] judgment, believes are
appropriate to determining what will `protect the public health'.''

    See 54 FR at 38057, September 14, 1989. Thus, the level of the MIR
is only one factor to be weighed in determining acceptability of risks.
The Benzene NESHAP explained that ``an MIR of approximately one in 10
thousand should ordinarily be the upper end of the range of
acceptability. As risks increase above this benchmark, they become
presumptively less acceptable under CAA section 112, and would be
weighed with the other health risk measures and information in making
an overall judgment on acceptability. Or, the Agency may find, in a
particular case, that a risk that includes MIR less than the
presumptively acceptable level is unacceptable in the light of other
health risk factors.'' Id. at 38045. Similarly, with regard to the
ample margin of safety analysis, the EPA stated in the Benzene NESHAP
that: ``EPA believes the relative weight of the many factors that can
be considered in selecting an ample margin of safety can only be
determined for each specific source category. This occurs mainly
because technological and economic factors (along with the health-
related factors) vary from source category to source category.'' Id. at
38061. We also consider the uncertainties associated with the various
risk analyses, as discussed earlier in this preamble, in our
determinations of acceptability and ample margin of safety.
    The EPA notes that it has not considered certain health information
to date in making residual risk determinations. At this time, we do not
attempt to quantify those HAP risks that may be associated with
emissions from other facilities that do not include the source
categories in question, mobile source emissions, natural source
emissions, persistent environmental pollution or atmospheric
transformation in the vicinity of the sources in these categories.
    The agency understands the potential importance of considering an
individual's total exposure to HAP in addition to considering exposure
to HAP emissions from the source category and facility. We recognize
that such consideration may be particularly important when assessing
non-cancer risks, where pollutant-specific exposure health reference
levels (e.g., RfCs) are based on the assumption that thresholds exist
for adverse health effects. For example, the agency recognizes that,
although exposures attributable to emissions from a source category or
facility alone may not indicate the potential for increased risk of
adverse non-cancer health effects in a population, the exposures
resulting from emissions from the facility in combination with
emissions from all of the other sources (e.g., other facilities) to
which an individual is exposed may be sufficient to result in increased
risk of adverse non-cancer health effects. In May 2010, the SAB advised
the EPA ``that RTR assessments will be most useful to decision makers
and communities if results are presented in the broader context of
aggregate and cumulative risks, including background concentrations and
contributions from other sources in the area.'' \22\
---------------------------------------------------------------------------

    \22\ The EPA's responses to this and all other key
recommendations of the SAB's advisory on RTR risk assessment
methodologies (which is available at: http://yosemite.epa.gov/sab/
sabproduct.nsf/4AB3966E263D943A8525771F00668381/$File/EPA-SAB-10-
007-unsigned.pdf) are outlined in a memo to this rulemaking docket
from David Guinnup titled, EPA's Actions in Response to the Key
Recommendations of the SAB Review of RTR Risk Assessment
Methodologies.
---------------------------------------------------------------------------

    In response to the SAB recommendations, the EPA is incorporating
cumulative risk analyses into its RTR risk assessments, including those
reflected in this proposal. The agency is: (1) Conducting facility-wide
assessments, which include source category emission points as well as
other emission points within the facilities; (2) considering sources in
the same category whose emissions result in exposures to the same
individuals; and (3) for some persistent and bioaccumulative
pollutants, analyzing the ingestion route of exposure. In addition, the
RTR risk assessments have always considered aggregate cancer risk from
all carcinogens and aggregate non-cancer hazard indices from all non-
carcinogens affecting the same target organ system.
    Although we are interested in placing source category and facility-
wide HAP risks in the context of total HAP risks from all sources
combined in the vicinity of each source, we are concerned about the
uncertainties of doing so. Because of the contribution to total HAP
risk from emission sources other than those that we have studied in
depth during this RTR review, such estimates of total HAP risks would
have significantly greater associated uncertainties than the source
category or facility-wide estimates. Such aggregate or cumulative
assessments would compound those uncertainties, making the assessments
too unreliable.

C. How did we perform the technology review?

    Our technology review focused on the identification and evaluation
of developments in practices, processes and control technologies that
have occurred since the MACT standards were promulgated. Where we
identified such developments, in order to inform our decision of
whether it is ``necessary'' to revise the emissions standards, we
analyzed the technical feasibility of applying these developments and
the estimated costs, energy implications, non-air environmental
impacts, as well as considering the emission reductions. We also
considered the appropriateness of applying controls to new sources
versus retrofitting existing sources.
    Based on our analyses of the available data and information, we
identified potential developments in practices, processes and control
technologies. For this exercise, we considered any of the following to
be a ``development'':
     Any add-on control technology or other equipment that was
not identified and considered during development of the original MACT
standards.
     Any improvements in add-on control technology or other
equipment (that were identified and considered during development of
the original MACT standards) that could result in additional emission
reduction.
     Any work practice or operational procedure that was not
identified or considered during development of the original MACT
standards.
     Any process change or pollution prevention alternative
that could be broadly applied to the industry and that was not
identified or considered during development of the original MACT
standards.
     Any significant changes in the cost (including cost
effectiveness) of applying controls (including controls the EPA
considered during the development of the original MACT standards).
    We reviewed a variety of data sources in our investigation of
potential practices, processes or controls to consider. Among the
sources we reviewed were the NESHAP for various industries that were
promulgated since the MACT standards being reviewed in this action. We
reviewed the regulatory requirements and/or technical analyses
associated with these regulatory actions to identify any practices,
processes and control technologies considered in these efforts that
could be applied to emission

sources in the Secondary Aluminum Production source category, as well
as the costs, non-air impacts and energy implications associated with
the use of these technologies. Additionally, we requested information
from facilities regarding developments in practices, processes or
control technology. Finally, we reviewed information from other
sources, such as state and/or local permitting agency databases and
industry-supported databases.

IV. Revised Analytical Results and Proposed Decisions for the Secondary
Aluminum Production Source Category

A. What are the results of the risk assessment and analysis?

1. Inhalation Risk Assessment Results
    Table 3 provides an overall summary of the results of the
inhalation risk assessment.

                                Table 3--Secondary Aluminum Production Source Category Inhalation Risk Assessment Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                     Maximum individual cancer                 Estimated   Maximum chronic non-cancer
                                      risk (in 1-million) \a\     Estimated    population           TOSHI \b\
                                    ---------------------------    annual          at     ----------------------------
                                                                   cancer      increased                                  Worst-case maximum screening
    Number of facilities modeled       Based on      Based on     incidence     risk of      Based on      Based on         acute non-cancer HQ \c\
                                        actual      allowable    (cases/yr)   cancer  >=1-    actual       allowable
                                       emissions    emissions        \d\          in-1       emissions     emissions
                                                                              million \d\      level         level
--------------------------------------------------------------------------------------------------------------------------------------------------------
Major Sources (52).................           0.6            4        0.0007            0        0.04           0.1    HQ(REL) = 0.7 (HF).
                                                                                HQ(AEGL1) = 0.4 (HCl).
Area Sources (103).................           0.3            1        0.001             0        0.0003         0.001  NA.
Facility-wide (52 Major Sources)...          70             NA        0.05        760,000        1             NA      NA.
--------------------------------------------------------------------------------------------------------------------------------------------------------
 \a\ Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category for major sources and for D/F emissions from
  the area sources.
 \b\ Maximum TOSHI. The target organ with the highest TOSHI for the Secondary Aluminum Production source category for both actual and allowable
  emissions is the respiratory system.
 \c\ There is no acute dose-response value for D/F. Thus an acute HQ value for area sources was not calculated. The maximum off-site HQ acute value of
  0.7 for actuals is driven by emissions of hydrofluoric acid. See section III.A.3 of this document for explanation of acute dose-response values. Acute
  assessments are not performed on allowable emissions.
 \d\ These estimates are based upon actual emissions.

    The inhalation risk modeling performed to estimate risks based on
actual and allowable emissions relied primarily on emissions data from
the ICRs. The results of the chronic baseline inhalation cancer risk
assessment indicate that, based on estimates of current actual
emissions, the MIR posed by the Secondary Aluminum Production source
category from major sources and from area sources was less than 1-in-1
million. The estimated cancer incidence is slightly higher for area
sources compared to the major sources due to the larger number of area
sources nationwide. The total estimated cancer incidence from secondary
aluminum production sources from both major and area sources based on
actual emission levels is 0.002 excess cancer cases per year, with
emissions of D/F, naphthalene and PAH contributing 48 percent, 31
percent and 11 percent, respectively, to this cancer incidence. In
addition, we note that there are no excess cancer risks greater than or
equal to 1-in-1 million as a result of actual emissions from this
source category over a lifetime. The maximum modeled chronic non-cancer
HI (TOSHI) value for the source category for both major and area
sources based on actual emissions was estimated to be 0.04, with HCl
emissions from group 1 furnaces accounting for 99 percent of the HI.
    When considering MACT-allowable emissions, the MIR is estimated to
be up to 4-in-1 million, driven by emissions of D/F compounds,
naphthalene and PAHs from the scrap dryer/delacquering/decoating kiln.
The estimated potential cancer incidence considering allowable
emissions for both major and area sources is estimated to be 0.014
excess cancer cases per year, or 1 case every 70 years. Approximately
3,400 people were estimated to have cancer risks greater than or equal
to 1-in-1 million considering allowable emissions from secondary
aluminum plants. When considering MACT-allowable emissions, the maximum
chronic non-cancer TOSHI value was estimated to be 0.1, driven by
allowable emissions of HCl from the group 1 furnaces.
2. Acute Risk Results
    Our screening analysis for worst-case acute impacts based on actual
emissions indicates no pollutants exceeding an HQ value of 1 based upon
the REL.
3. Multipathway Risk Screening Results
    Results of the worst-case Tier 1 screening analysis indicate that
36 of the 52 major sources exceeded the PB-HAP emission cancer
screening rates (based on estimates of actual emissions) for D/F, and 3
of the 52 major sources exceeded the Tier 1 screen value for PAHs.
Regarding area sources, 60 of the 103 area sources exceeded the PB-HAP
emission cancer screening rates (based on estimates of actual
emissions) for D/F. For the compounds and facilities that did not
screen out at Tier 1, we conducted a Tier 2 screen. The Tier 2 screen
replaces some of the assumptions used in Tier 1 with site-specific
data, including the location of fishable lakes and local precipitation,
wind direction and speed. The Tier 2 screen continues to rely on high-
end assumptions about consumption of local fish and locally grown or
raised foods (adult female angler at 99th percentile consumption for
fish \23\ for the subsistence fisherman scenario and 90th percentile
consumption for locally grown or raised foods \24\ for the farmer
scenario). It is important to note that, even with the inclusion of
some site-specific information in the Tier 2 analysis, the multipathway
screening analysis is still a very conservative, health-protective
assessment (e.g., upper-bound consumption of local fish and locally
grown and/or raised foods) and in all likelihood will yield results
that serve as an upper-bound multipathway risk associated with a
facility.
---------------------------------------------------------------------------

    \23\ Burger, J. 2002. Daily Consumption of Wild Fish and Game:
Exposures of High End Recreationists. International Journal of
Environmental Health Research 12:343-354.
    \24\ U.S. EPA. Exposure Factors Handbook 2011 Edition (Final).
U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-09/
052F, 2011.
---------------------------------------------------------------------------

    While the screening analysis is not designed to produce a
quantitative risk result, the factor by which the emissions exceed the
threshold serves as a rough gauge of the ``upper-limit'' risks we would
expect from a facility. Thus, for

example, if a facility emitted a PB-HAP carcinogen at a level 2 times
the screening threshold, we can say with a high degree of confidence
that the actual maximum cancer risks will be less than 2-in-1 million.
Likewise, if a facility emitted a noncancer PB-HAP at a level 2 times
the screening threshold, the maximum noncancer hazard would represent
an HQ less than 2. The high degree of confidence comes from the fact
that the screens are developed using the very conservative (health-
protective) assumptions that we describe above.
    Based on the Tier 2 cancer screening analysis, 25 of the 52 major
sources and 34 of the 103 area sources emit D/F above the Tier 2 cancer
screening thresholds for the subsistence fisher and farmer scenarios.
The individual D/F emissions are all scaled based on their toxicity to
2,3,7,8-tetrachlorodibenzo-p-dioxin and reported as toxic equivalents
(TEQs). The subsistence fisher scenario for the highest risk facilities
exceeds the D/F cancer threshold by a factor of 80 for the major
sources and by a factor of 70 for the area sources. The Tier 2 analysis
also identifies 23 of the 52 major sources and 26 of the 103 area
sources emitting D/F above the Tier 2 cancer screening thresholds for
the subsistence farmer scenario. The highest exceedance of the Tier 2
screen value is 40 for the major sources and 20 for the area sources
for the farmer scenario.
    We have only one major source emitting PAHs above the Tier 2 cancer
screen value with an exceedance of 2 for the farmer scenario. All PAH
emissions are scaled based on their toxicity to benzo(a)pyrene and
reported as TEQs.
    A more refined Tier 3 multipathway screening analysis was conducted
for six Tier 2 major source facilities. The six facilities were
selected because the Tier 2 cancer screening assessments for these
facilities had exceedances greater than or equal to 50 times the screen
value for the subsistence fisher scenario. The major sources
represented the highest screened cancer risk for multipathway impacts.
Therefore, further screening analyses were not performed on the area
sources. The Tier 3 screen examined the set of lakes from which the
fisher might ingest fish. Any lakes that appeared to not be fishable or
not publicly accessible were removed from the assessment, and the
screening assessment was repeated. After we made the determination the
critical lakes were fishable, we analyzed plume rise data for each of
the sites. The Tier 3 screen was conducted only on those HAP that
exceeded the Tier 2 screening threshold, which for this assessment were
D/F and PAHs. Both of these PB-HAP are carcinogenic. The Tier 3 screen
resulted in lowering the maximum exceedance of the screen value for the
highest site from 80 to 70. Results for the other sites were all less
than 70. The highest exceedance of the Tier 2 cancer screen value of 40
for the farmer scenario was also reduced in the Tier 3 screening
assessment to a value of 30 for the major sources within this source
category.
    Overall, the refined multipathway screening analysis for D/F and
PAHs utilizing the Tier 3 screen predicts a potential lifetime cancer
risk of 70-in-1 million or lower to the most exposed individual, with
D/F emissions from group 1 furnaces handling other than clean charge
driving the risk. Cancer risks due to PAH emissions for the maximum
exposed individual were less than 1-in-1 million.
    The chronic non-cancer HQ is predicted to be below 1 for cadmium
compounds and 1 for mercury compounds. For lead, we did not estimate
any exceedances of the primary lead NAAQS.
    Further details on the refined multipathway screening analysis can
be found in Appendix 8 of the Residual Risk Assessment for the
Secondary Aluminum Production Source Category in Support of the 2014
Supplemental Proposal, which is available in the docket.
4. Environmental Risk Screening Results
    As described in section III.A of this document, we conducted an
environmental risk screening assessment for the Secondary Aluminum
Production source category for the following seven pollutants: PAHs,
mercury (methyl mercury and mercuric chloride), cadmium, lead, D/F, HCl
and HF.
    Of the seven pollutants included in the environmental risk screen,
major sources in this source category emit PAHs, mercuric chloride,
cadmium, lead, D/F, HCl and HF. In the Tier 1 screening analysis for
PB-HAP, none of the individual modeled concentrations for any facility
in the source category exceeded any of the ecological benchmarks
(either the LOAEL or NOAEL) for PAHs, mercuric chloride, cadmium and D/
F. For lead, we did not estimate any exceedances of the secondary lead
NAAQS. For HCl and HF, the average modeled concentration around each
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 and HF (i.e.,
each off-site data point in the modeling domain) was below the
ecological benchmarks for all facilities.
    Of the seven pollutants included in the environmental risk screen,
area sources in this source category are regulated only for D/F. In the
Tier 1 screening analysis for D/F, none of the individual modeled
concentrations for any facility in the source category exceeded any of
the ecological benchmarks (either the LOAEL or NOAEL) for D/F.
5. Facility-Wide Risk Assessment Results
    Considering facility-wide emissions at the 52 major sources, the
MIR is estimated to be 70-in-1 million driven by arsenic and Ni
emissions, and the chronic non-cancer TOSHI value is calculated to be 1
driven by emissions of cadmium compounds. The above risks are driven by
emissions from the potline roof vents at the co-located primary
aluminum production operations. The Secondary Aluminum Production
source category represents less than 1 percent of the inhalation risks
from the facility-wide assessment based upon actual emissions.
Emissions from primary aluminum sources are being addressed in a
separate action. Details regarding primary aluminum sources are
available at http://www.epa.gov/ttn/atw/alum/alumpg.html.
6. What demographic groups might benefit from this regulation?
    To determine whether or not to conduct a demographics analysis,
which is an assessment of risks to individual demographic groups, we
look at a combination of factors including the MIR, non-cancer TOSHI,
population around the facilities in the source category and other
relevant factors. For the Secondary Aluminum Production source
category, inhalation risks were low with excess cancer risks being less
than 1-in-1 million and non-cancer hazards being less than 1.
Therefore, we did not conduct an assessment of risks to individual
demographic groups for this rulemaking. However, we did conduct a
proximity analysis for both area and major sources, which identifies
any overrepresentation of minority, low income or indigenous
populations near facilities in the source category. The results of the
proximity analyses suggest there are a higher percent of minorities,
people with low income, and people without a high school diploma living
near these facilities (i.e., within 3 miles) compared to the national
averages for these subpopulations. However, as explained above, the
risks due to HAP emissions from this source category are low for all
populations (e.g., inhalation cancer risks are less than 1-in-1 million

for all populations and non-cancer hazard indices are less than 1).
Furthermore, we do not expect this supplemental proposal to achieve
reductions in HAP emissions. Therefore, we conclude that this
supplemental proposal will not have disproportionately high and adverse
human health or environmental effects on minority or low-income
populations because it does not affect the level of protection provided
to human health or the environment. However, this supplemental
proposal, if finalized, will provide additional benefits to these
demographic groups by improving the compliance, monitoring and
implementation of the NESHAP.
    The detailed results of the proximity analyses can be found in the
EJ Screening Report for Secondary Aluminum Area Sources and the EJ
Screening Report for Secondary Aluminum Major Sources, which are
available in the docket for this rulemaking.

B. What are our proposed decisions regarding risk acceptability, ample
margin of safety and adverse environmental effects based on our revised
analyses?

1. Risk Acceptability
    As noted in section II.A.1 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 25.'' (54 FR 38045, September 14, 1989).
---------------------------------------------------------------------------

    \25\ 1-in-10 thousand is equivalent to 100-in-1 million. The EPA
currently describes cancer risks as ``n-in-1 million.''
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    In this proposal, the EPA estimated risks based on both actual and
allowable emissions from secondary aluminum facilities. As discussed
above, in determining acceptability, we considered risks based on both
actual and allowable emissions.
a. Estimated Risks From Actual Emissions
    The baseline inhalation cancer risk to the individual most exposed
to emissions from the Secondary Aluminum Production source category is
from major sources with cancer risks less than 1-in-1 million based on
actual emissions. The total estimated incidence of cancer for this
source category from both major and area sources due to inhalation
exposures is 0.002 excess cancer cases per year, or 1 case in 500
years. The agency estimates that the maximum chronic non-cancer TOSHI
from inhalation exposure for this source category is from major sources
with an HI of 0.04 based on actual emissions, with HCl emissions from
group 1 furnaces accounting for a large portion (99 percent) of the HI.
    The multipathway screening analysis, based upon actual emissions,
indicates the excess cancer risk from this source category is lower
than 70-in-1 million with D/F emissions representing 99 percent of
these potential risks based on the fisher scenario. The multipathway
MIR cancer risks are the same for both the major and area sources
within this source category for the fisher scenario. For the farmer
scenario, the excess cancer risk is lower than 30-in-1 million for the
major sources and 20-in-1 million for the area sources. There were no
facilities within this source category having a multipathway non-cancer
screen value greater than 1 for cadmium or mercury. In evaluating the
potential for multipathway effects from emissions of lead, modeled
maximum annual lead concentrations were compared to the secondary NAAQS
for lead (0.15 [mu]g/m\3\). Results of this analysis estimate that the
NAAQS for lead would not be exceeded at any off-site locations.
    As noted above, the multipathway screens are conservative and
incorporate many health-protective assumptions. For example, the EPA
chooses inputs from the upper end of the range of possible values for
the influential parameters used in the Tier 2 screen and assumes that
the exposed individual for each scenario exhibits ingestion behavior
that would lead to a high total exposure. A Tier 2 or 3 exceedance of a
cancer or non-cancer screen value cannot be equated with an actual risk
value or a HQ or HI. Rather, it represents a high-end estimate of what
the risk or hazard may be. For example, a non-cancer screen value of 2
can be interpreted to mean that we have high confidence that the HI is
lower than 2. Similarly, a cancer screen value of 30 for a carcinogen
means that we have high confidence that the risk is lower than 30-in-1-
million. Confidence comes from the conservative, or health-protective,
assumptions that are used in the Tier 2 and Tier 3 screens. The Tier 3
screen improves the accuracy of the Tier 2 screen through validation of
impacted lakes assessed and accounting for mass lost to the upper air
sink, which reduces the uncertainty in the screen. The maximum Tier 3
exceedance of the cancer screen values for the secondary aluminum
source category are 70 for the sustainable fisher scenario and 30 for
the farmer scenario, both driven by D/F emissions from major sources.
    The screening assessment of worst-case acute inhalation impacts
from baseline actual emissions indicates no pollutants exceeding an HQ
value of 1 based on the REL, with an estimated worst-case maximum acute
HQ of 0.7 for HF based on the 1-hour REL.
b. Estimated Risks From Allowable Emissions
    The EPA estimates that the inhalation cancer risk to the individual
most exposed to emissions from the Secondary Aluminum Production source
category is up to 4-in-1 million based on allowable emissions from
major sources, with D/F, naphthalene and PAH emissions driving the
risks. The EPA estimates that the incidence of cancer due to inhalation
for the entire source category based on allowable emissions could be up
to 0.014 excess cancer cases per year, or 1 case approximately every 70
years. About 3,400 people face an estimated increased cancer risk
greater than or equal to 1-in-1 million due to inhalation exposure to
allowable HAP emissions from this source category.
    The risk assessment estimates that the maximum chronic non-cancer
TOSHI from inhalation exposure values for the source category is up to
0.1 based on allowable emissions, driven by HCl emissions from major
sources.
c. Acceptability Determination
    In determining whether risks are acceptable for this source
category, the EPA considered all available health information and risk
estimation uncertainty as described above. As noted above, the agency
estimated risk from actual and allowable emissions. While there are
uncertainties associated with both the actual and allowable emissions,
we consider the allowable emissions to be an upper bound, based on the
conservative methods we used to calculate allowable emissions.
    The risk results indicate that both the actual and allowable
inhalation cancer risks to the individual most exposed are up to but no
greater than approximately 4-in-1 million, based on allowable emissions
which is considerably less than 100-in-1 million, the presumptive limit
of acceptability. The MIR based on actual emissions is 0.6-in-1
million, well below the presumptive limit as well. The maximum chronic
non-cancer hazard indices for both the actual and allowable inhalation
non-cancer risks to the individual most exposed are less than 1. The
maximum individual non-cancer HI is 0.04 based on actual

emissions and 0.1 based on allowable emissions.
    The maximum acute non-cancer HQ for all pollutants was below 1,
with a maximum value of 0.7 based on the REL for hydrofluoric acid. The
excess cancer risks from the multipathway screen from actual D/F and
PAH emissions from major and area sources indicate that the risk to the
individual most exposed could be up to, but no greater than, 70-in-1
million for the fisher scenario and 30-in-1 million for the farmer
scenario. These results are less than 100-in-1 million, which is the
presumptive limit of acceptability. The multipathway Tier 2 screen for
non-cancer is at 1 for mercury and cadmium.
    The multipathway screens are based on model runs that use upper end
values for influential parameters and we assume that the exposed
individual exhibits ingestion behavior that would lead to a high total
exposure. The multipathway screens also include some hypothetical
elements, namely the existence and location of the hypothetical farmer
and fisher.
    Considering all of the health risk information and factors
discussed above, including the uncertainties discussed in section
III.A.8 of this preamble, the EPA proposes that the risks at baseline
are acceptable since the cancer risks are below the presumptive limit
of acceptability and the non-cancer results indicate there is minimal
likelihood of adverse non-cancer health effects due to HAP emissions
from this source category.
2. Ample Margin of Safety Analysis
    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 in this source category to
further reduce the risks (or potential risks) due to emissions of HAP
identified in our risk assessment, along with all of the health risks
and other health information considered in the risk acceptability
determination described above. In this analysis, we considered the
results of the technology review, risk assessment and other aspects of
our MACT rule review to determine whether there are any cost-effective
controls or other measures that would reduce emissions further to
provide an ample margin of safety with respect to the risks associated
with these emissions.
    Our inhalation risk analysis indicated very low potential for risk
from the facilities in the source category, and, therefore, very little
inhalation risk reductions could be realized regardless of the
availability of control options. Our technology review, which was
conducted for the 2012 proposal and is in large part applicable to this
supplemental proposal (see section IV.C below for more discussion of
the technology review), did not identify any new practices, controls or
process options that are being used in this industry or in other
industries that would be cost effective for further reduction of these
emissions and risks.
    Our multipathway screening analysis results for the 2012 proposal
indicated exceedances of the worst-case screening levels which did not
necessarily indicate any risks. However, they did suggest a potential
for risks. For this supplemental proposal, a more refined multipathway
screening analysis was conducted, including a Tier 3 screen for the top
six major source facilities for cancer. The more refined screening
analysis was conducted only on those PB-HAP that exceeded the screening
threshold, which for this assessment were PAHs and D/F. The refined
multipathway screening analysis showed that the earlier screening
analysis for the 2012 proposal over-predicted the potential cancer risk
when compared to the refined analysis for three of the six facilities
assessed, with emissions of D/F driving these cancer risks. The
remaining facilities had the same cancer screen value in the refined
analysis as in the earlier screening results when rounded to 1
significant figure. The cancer risks due to PAH emissions were less
than 1-in-1 million based on the refined analysis.
    To evaluate the potential to reduce D/F emissions and risks, as
part of our revised ample margin of safety analysis, we used the same
analysis that we conducted for the 2012 proposal except that we
incorporated more recent D/F emissions data and control cost
information. As in the analysis conducted for the 2012 proposal, we
evaluated two control options. Option 1 considered lowering the
existing D/F emissions limit from 15 to 10 [mu]g TEQ/Mg feed for all
group 1 furnaces processing other than clean charge. Option 2
considered lowering the existing D/F limit for group 1 furnaces
processing other than clean charge after applying a subcategorization
based on facility production capacity. An emission reduction to 10
[mu]g TEQ/Mg represents a level that could potentially be met with an
activated carbon injection system. With regard to the option of
lowering the D/F emission limit to 10 [mu]g TEQ/Mg feed for group 1
furnaces handling other than clean charge, we estimate that about 12
furnaces at eight facilities would need to reduce their D/F emissions
and that the total capital costs would be $390,000 with total
annualized costs of $1.4 million. This option would achieve an
estimated 0.49 grams TEQ reduction of D/F emissions with an overall
cost effectiveness of about $2.9 million per gram D/F TEQ. For the
second option, facilities with group 1 furnace production capacity
greater than 200,000 tpy (melting other than clean charge) would be
required to meet a limit of 10 [mu]g TEQ/Mg limit. For this option, we
estimate that 4 furnaces at two facilities would be required to reduce
their D/F emissions. We estimate that the total capital costs would be
$130,000 with total annualized costs of $460,000. This option would
achieve an estimated 0.12 grams TEQ reduction of D/F emissions with an
overall cost-effectiveness of about $3.8 million per gram D/F TEQ. As
we concluded in the ample margin of safety analysis for the 2012
proposal, our analysis indicates that these options would result in
very little emission reductions (0.49 grams TEQ of D/F for Option 1 and
0.12 grams TEQ of D/F reductions for Option 2) and, therefore, would
result in little or no changes to the potential risk levels. After
considering the costs and the level of reductions that would be
achieved, we have decided, as we did in the 2012 proposal, not to
propose any of these options. For more information on this analysis,
see the Supplemental Proposal Technical Support Document for the
Secondary Aluminum Production Source Category, which is available in
the public docket for this proposed rulemaking.
    In the 2012 proposal, we also evaluated possible options based on
work practices to achieve further emission reductions. The current
subpart RRR NESHAP includes work practices to minimize D/F emissions
which include scrap inspection, limitations on materials processed by
group 2 furnaces, temperature and residence time requirements for
afterburners controlling sweat furnaces, labeling requirements,
capture/collection requirements and requirements for an operations,
maintenance and monitoring plan that contains details on the proper
operation and maintenance of processes and control equipment. For the
2012 proposal, we searched for and evaluated other possible work
practices such as good combustion practices, better scrap inspection
and cleaning, and process monitoring. However, none of these potential
work practices were determined to be feasible and effective

in further reducing D/F emissions for this source category. Thus, we
did not identify any feasible or applicable work practices for this
industry beyond those that are currently in the MACT rule. Therefore,
in the 2012 proposal we did not propose any additional work practices.
Since the 2012 proposal, we have not identified any changes in the
sources of emissions, the types of pollutants emitted or the work
practices available to be used in the secondary aluminum production
industry. Therefore, as in the 2012 proposal, we are not proposing any
revisions to subpart RRR based on work practices. Further details on
work practices and control options are provided in the Supplemental
Proposal Technology Review for the Secondary Aluminum Production Source
Category, which is available in the public docket for this rulemaking.
    In accordance with the approach established in the Benzene NESHAP,
we weighed all health risk information and factors considered in the
risk acceptability determination, including uncertainties, along with
the cost and feasibility of control technologies and other measures
that could be applied in this source category, in making our ample
margin of safety determination. In summary, our risk analysis indicated
very low potential for risk, and we identified no developments in
technology that would be cost effective in reducing HAP emissions
relative to reductions already being achieved. We also did not identify
any cost effective approaches to further reduce D/F emissions and
multipathway risk beyond what is already being achieved by the current
NESHAP.
    Because of the high cost associated with the use of activated
carbon injection systems and because work practices are already
required to help ensure low emissions, and in light of the
considerations discussed above, we propose that the existing MACT
standards provide an ample margin of safety to protect public health.
3. Adverse Environmental Effects
    Based on the results of our environmental risk screening
assessment, we conclude that there is not an adverse environmental
effect as a result of HAP emissions from the Secondary Aluminum
Production source category. 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.

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

    A technology review was conducted for the Secondary Aluminum
Production source category and is described in the 2012 proposal at 77
FR 8596, February 14, 2012. Details of the technology review and its
findings are available in the memorandum, Draft Technology Review for
the Secondary Aluminum Production Source Category (Docket item EPA-HQ-
OAR-2010-0544-0144). The typical controls used to minimize emissions at
secondary aluminum facilities include fabric filters for control of PM
from aluminum scrap shredders; afterburners for control of THC and D/F
from thermal chip dryers; afterburners plus lime-injected fabric
filters for control of PM, HCl, THC and D/F from scrap dryers/
delacquering kilns/decoating kilns; afterburners for control of D/F
from sweat furnaces; fabric filters for control of PM from dross-only
furnaces and rotary dross coolers; lime-injected fabric filters for
control of PM and HCl from in-line fluxers; and lime-injected fabric
filters for control of PM, HCl and D/F from group 1 furnaces. In our
review of technology, we determined that there have been some
developments in practices, processes or control technologies that have
been implemented in this source category since promulgation of the
current NESHAP. We stated in the 2012 proposal that these findings did
not warrant any changes to subpart RRR. Following the 2012 proposal, no
public comments were received that would alter the conclusions of our
technology review for the Secondary Aluminum Production source
category. Therefore, for this supplemental proposal, we are proposing
that the technology review findings are still valid. The EPA is not
aware of any changes in technology development since the 2012 proposal.
    As part of the technology review for the 2012 proposal, we also
evaluated other technologies that have the potential to reduce HAP
emissions, in particular emissions of D/F. See Draft Technical Support
Document for the Secondary Aluminum Production Source Category, Docket
item EPA-HQ-OAR-2010-0544-0152. We have updated that analysis for this
supplemental proposal. See Supplemental Proposal Technical Support
Document for the Secondary Aluminum Production Source Category and the
Supplemental Proposal Technology Review for the Secondary Aluminum
Production Source Category, which are available in the public docket
for this rulemaking. Under this analysis, we evaluated the same
approaches that were evaluated under the ample margin of safety
analysis described in section IV.B of this document. We evaluated the
option of lowering the existing D/F limit from 15 to 10 [mu]g TEQ/Mg
feed for group 1 furnaces processing other than clean charge either at
all secondary aluminum facilities or only at larger secondary aluminum
facilities based on facility production capacity. The lower D/F
emissions limits potentially could be met by using an activated carbon
injection system. Using updated information on emissions and control
costs, we estimate that about 12 furnaces at eight facilities would
need to reduce their D/F emissions to meet the 10 [mu]g TEQ/Mg feed for
group 1 furnaces and that the total capital costs would be $390,000
with total annualized costs of $1.4 million. This option would achieve
an estimated 0.49 grams TEQ reduction of D/F emissions with an overall
cost effectiveness of about $2.9 million per gram D/F TEQ. For the
second option, only facilities with group 1 furnace production capacity
greater than 200,000 tpy (melting other than clean charge) would be
required to meet the lower 10 [mu]g TEQ/Mg limit. For this option, we
estimate that four furnaces at two facilities would be required to
reduce their D/F emissions. We estimate that the total capital cost
would be $130,000 with total annualized costs of $460,000. This option
would achieve an estimated 0.12 grams TEQ reduction of D/F emissions
with an estimated overall cost effectiveness of $3.8 million per gram
D/F TEQ. (The details of this analysis are in the Supplemental Proposal
Technical Support Document for the Secondary Aluminum Production Source
Category, which is available in the public docket for this rulemaking.
After considering the costs and the small emission reductions that
would be achieved, we have decided not to propose any of these options.

D. What other actions are we proposing?

    In the 2012 proposal, we proposed amendments to correct and clarify
existing requirements in subpart RRR. In this supplemental proposal, we
are proposing revisions to certain rule corrections and clarifications
that were in the 2012 proposal as well as proposing alternative
compliance options to the operating and monitoring requirements for
sweat furnaces. On these limited revisions, we are soliciting comment.
As discussed above, the 2012 proposal also contained other proposed
rule corrections and clarifications for which we are not proposing any
changes in this document, and,

therefore, for which we are not seeking public comment (if EPA
nonetheless were to receive any such comments, the comments would be
outside the scope of this supplemental proposal and would not be
considered).
1. Changing Furnace Classification
    In the 2012 proposal, we proposed to address an area of uncertainty
under subpart RRR by specifying in 40 CFR 63.1514 rule provisions
expressly allowing changes in furnace classification, subject to
procedural and testing requirements, operating requirements and
recordkeeping requirements. We proposed a frequency limit of no more
than one change in classification (and associated reversion) every six
months, with an exception for planned control device maintenance
activities requiring shutdown. We received comments on the 2012
proposal requesting additional or unlimited changes in furnace
classification. Based on the information received, we reevaluated the
appropriate limit on frequency of furnace classification changes. The
EPA received from one commenter an inventory of the number of
classification changes that occurred each year at a specific subpart
RRR furnace over a nearly 10-year period (available in the docket for
this rulemaking). The highest number of furnace classification changes
in one year, including both planned and unplanned changes, was nine.
    Based on the comments and information received and because of the
potential difficulty in distinguishing between a planned and unplanned
change in classification, we are proposing and requesting comments on a
revised limit on the frequency of changes in furnace classification of
four (including the four associated reversions) in any 6-month period,
including both planned and unplanned changes in classification, with a
provision allowing additional changes by petitioning the permitting
authority for major sources, or the Administrator for area sources.
These revisions in proposed 40 CFR 63.1514(e) would balance the
interest in allowing industry to make furnace classification changes
while preserving the EPA's and delegated authorities' practical and
effective enforcement of the emission limitations, work practice
standards and other requirements of subpart RRR. We request that any
commenter who would like the EPA to consider a different limit on
frequency to include a specific rationale and factual basis for why a
different frequency would be appropriate as well as any data on
historical frequencies of furnace classification changes under subpart
RRR.
    We are specifically requesting comments on the revised proposed
provisions in 40 CFR 63.1514(e), which addresses the frequency of
changing furnace classification. No substantive changes have been made
to the other proposed provisions in 40 CFR 63.1514, and we are not
requesting comments on any other aspect of the proposed provisions for
furnace classification changes. We will address the comments previously
received on the 2012 proposal, as well as comments that are received in
response to the revised proposed frequency limit in this document, when
we take final rulemaking action.
2. Worst Case Scenario Testing
    In the 2012 proposal, we proposed amendments to clarify that
performance tests under multiple scenarios may be required in order to
reflect the emissions ranges for each regulated pollutant. We received
comments on the 2012 proposal that the worst case charge materials, and
blends of these, have differing process rates and, therefore, the
charge rate from the stack tests is not representative of the charge
rate that will be achieved during normal operations. Based on the
comments received and recognizing that it may be necessary to conduct
performance tests under one or multiple scenarios to be representative
of the range of normal operating conditions, we are proposing revised
language in 40 CFR 63.1511(b)(1) to clarify the conditions under which
subpart RRR performance tests must be conducted. The intention in the
subpart RRR rule is to require testing under ``worst case'' conditions
from the standpoint of emissions and to establish parameters based on
such testing that ensure compliance under all operating conditions. For
example, in a response to comments on the original proposed subpart RRR
rule regarding the inlet temperature requirement for fabric filters,
the EPA stated that testing under worst case conditions, such as higher
than normal fabric filter inlet temperatures, could provide a larger
temperature operating range, which would be used to monitor and ensure
continuous compliance between periodic performance tests (65 FR 15699,
March 23, 2000). In the EPA response-to-comments document (Summary of
Public Comments and Responses on Secondary Aluminum NESHAP, December
14, 1999, Docket No. A-92-61, item V-C-1, comment 4.1.47), the EPA
explained that requiring multiple tests over a range of different
furnace operating conditions will show that the selected monitoring
parameters are valid indicators of emissions and that it may not be
possible for a single test to be representative of worst case
conditions and that more than a single test may be required. It is not
permissible, for example, to demonstrate compliance while processing
relatively uncontaminated scrap, and then at a later time, when the
supply of this scrap is constrained, process more heavily contaminated
scrap, without demonstrating compliance under these conditions based on
previous emissions testing or on new emissions testing if previous
tests would not be representative of the emissions from the processing
of the more heavily contaminated scrap.
    To clarify the requirements for testing, we are proposing that
performance tests be conducted under representative (normal) conditions
expected to produce the highest level of HAP emissions expressed in the
units of the emission standards for the HAP (considering the extent of
scrap contamination, reactive flux addition rate and feed/charge rate).
If a single test condition is not expected to produce the highest level
of emissions for all HAP, testing under two or more sets of conditions
(for example high contamination at low feed/charge rate and low
contamination at high feed/charge rate) may be required. Any subsequent
performance tests for the purposes of establishing new or revised
parametric limits shall be allowed upon pre-approval from the
permitting authority for major sources or the Administrator for area
sources. These new parametric settings shall be used to demonstrate
compliance for the period being tested. We solicit comment on whether
the proposed amendment adequately addresses and clarifies the
requirement that multiple tests may be necessary to represent different
operational conditions.
3. Testing of Uncontrolled Furnaces
    As explained in the 2012 proposal, while subpart RRR specifies
capture and collection requirements for emission units that are
equipped with add-on air pollution control devices, there are no such
requirements for furnaces that are not equipped with an add-on air
pollution control device. To clarify how uncontrolled sources are to be
tested for compliance, in 2012 we proposed compliance alternatives for
uncontrolled affected sources. Specifically, in 2012 we proposed either
the installation of ACGIH hooding or an assumption of 67-percent
capture

efficiency for furnace exhaust (i.e., multiply emissions measured at
the furnace exhaust outlet by 1.5 to calculate the total estimated
emissions from the furnace). Under the 2012 proposed provisions, if the
source fails to demonstrate compliance using the 67-percent capture
efficiency assumption, the source would have to retest using hooding
that meets ACGIH guidelines or petition the permitting authority for
major sources, or the Administrator for area sources, that such hoods
are impractical and propose alternative testing procedures that will
minimize unmeasured fugitive emissions. In the 2012 proposal, we
proposed that the retesting would need to occur within 90 days.
    We received comments that the EPA was proposing to mandate ACGIH
hooding during performance testing for uncontrolled furnaces.
Commenters also provided information that ACGIH-compliant hoods are not
possible to install on round top furnaces.
    Based on the comments received and our consideration of specific
testing scenarios and types of uncontrolled furnaces, we are proposing
revised requirements for the testing of uncontrolled furnaces. In this
supplemental proposal, we are proposing that if the source fails to
demonstrate compliance by the uncontrolled furnace using the 67-percent
capture efficiency assumption proposed in the 2012 proposal, then they
must retest using ACGIH hooding within 180 days (rather than the 90
days specified in the 2012 proposal), or the source can petition the
appropriate authority within 180 days that such hoods are impracticable
and propose alternative testing procedures to minimize emissions. No
time constraints on petitioning the appropriate authority were
specified in the 2012 proposal. In this supplemental proposal, we are
also proposing to clarify situations and circumstances whereby
installation of hooding according to ACGIH guidelines would be
considered impractical and are adding examples of procedures for
minimizing fugitive emissions during testing for such situations and
circumstances. The EPA is proposing conditions that would be considered
impractical to install hooding according to ACGIH guidelines. The EPA
is also proposing alternative procedures to minimize fugitive emissions
in the event that ACGIH-compliant hooding cannot be installed. These
alternative procedures are described in more detail below.
    Comments on the 2012 proposal also contained information regarding
the feasibility of installing ACGIH-compliant hooding on certain
furnace types in preparation for testing. Based on our review of the
information submitted by the commenters, we agree that it is not
possible to install ACGIH-compliant hoods on round top furnaces for
testing because the top of the furnace would have to be removed by a
crane operating above the furnace. We also agree that case-by-case
impracticability determinations are not necessary for round top
furnaces. Consequently, we are proposing that existing round top
furnaces be excluded from the proposed requirement either to install
ACGIH-compliant hooding or to use a 67-percent capture efficiency, as
well as from the proposed requirement that a petition of impracticality
be submitted to the appropriate authority. Instead, we propose that
round top furnaces must be operated to minimize fugitive emissions
during testing. We have not received any documentation to support
requests by commenters to exclude other types of furnaces such as box
reverberatory furnaces and box reverberatory furnaces with a side door.
Therefore, we have not proposed to exclude them, but we are prepared to
evaluate any comments submitted regarding impracticality and other
types of furnaces and, most importantly, supporting documentation that
we may receive from commenters.
    Under this supplemental proposal, owners or operators of
uncontrolled furnaces, including round top furnaces, who petition the
appropriate authority that it is impractical to install ACGIH-compliant
hooding would be required to minimize fugitive emissions from such
furnaces during testing. In response to commenters' requests, we are
proposing example procedures that can be used to minimize unmeasured
fugitive emissions during testing. These procedures may include, if
practical, one or more of the following, but are not limited to:
     Installing a hood that does not entirely meet ACGIH
guidelines;
     Using the building as an enclosure and measuring emissions
exhausted from the building if there are no other furnaces or other
significant sources in the building of the pollutants to be measured;
     Installing temporary baffles on the sides or top of the
furnace opening, if it is practical to do so where they will not
interfere with material handling or with the furnace door opening and
closing;
     Increasing the exhaust rate from the furnace from furnaces
with draft fans, so as to capture emissions that might otherwise escape
into the building;
     Minimizing the time the furnace doors are open or the top
is off;
     Delaying gaseous reactive fluxing until charging doors are
closed or the top is on;
     Agitating or stirring molten metal as soon as practicable
after salt flux addition and closing doors as soon as possible after
solid fluxing operations, including mixing and dross removal;
     Keeping building doors and other openings closed to the
greatest extent possible to minimize drafts that would divert emissions
from being drawn into the furnace; and
     Maintaining burners on low-fire or pilot operation while
the doors are open or the top is off.
    We are also proposing revised amendments to clarify in what
circumstances installation of temporary capture hoods for testing would
be considered impractical. We are proposing that temporary capture
hooding installation would be considered impractical if:
     Building or equipment obstructions (for example, wall,
ceiling, roof, structural beams, utilities, overhead crane or other)
are present such that the temporary hood cannot be located consistent
with acceptable hood design and installation practices;
     Space limitations or work area constraints exist such that
the temporary hood cannot be supported or located to prevent
interference with normal furnace operations or avoid unsafe working
conditions for the furnace operator; or
     Other obstructions and limitations subject to agreement by
the permitting authority for major sources, or the Administrator for
area sources.
    We invite comments and solicit information on certain aspects of
the proposed compliance provisions for testing of uncontrolled
furnaces. Specifically, we are soliciting comments and information on
the requirements in this supplemental proposal that specify the types
of obstacles and limitations that can be used to show that testing
using ACGIH-compliant hooding is impractical, the procedures that can
be implemented to minimize unmeasured fugitive emissions during
testing, and the exemption of existing round top furnaces from the
requirements to test using ACGIH-compliant hooding or apply the 67-
percent capture efficiency assumption. We are not soliciting comment on
any other element of the provisions proposed in the 2012 proposal
regarding testing of uncontrolled furnaces.

4. Annual Inspections of Capture/Collection Systems
    In the 2012 proposal, we proposed codifying in subpart RRR our
existing interpretation that annual hood inspections include flow rate
measurements using EPA Reference Methods 1 and 2 in Appendix A to 40
CFR part 60. These flow rate measurements supplement the effectiveness
of the required visual inspection for leaks, to reveal the presence of
obstructions in the ductwork, confirm that fan efficiency has not
declined and provide a measured value for air flow. Commenters
requested that the EPA allow flexibility in the methods used to
complete the annual inspections of capture/collection systems stating
that the use of volumetric flow measurement was often not necessary and
Method 1 and 2 tests could be a cost burden for some facilities.
Comments also indicated that routine, but less frequent, flow rate
measurements could ensure that capture/collection systems are operated
properly and suggested alternative methods of ensuring the efficiency
of capture/collection systems.
    Based on the comments received and our consideration of inspection
needs, the EPA is proposing additional options that provide more
flexibility in how affected sources can verify the efficiency of their
capture/collection system. Instead of annual Methods 1 and 2 testing,
we propose that sources may choose to perform flow rate measurements
using EPA Methods 1 and 2 once every 5 years provided that a flow rate
indicator consisting of a pitot tube and differential pressure gauge is
installed and used to record daily the differential pressure and to
ensure that the differential pressure is maintained at or above 90
percent of the pressure differential measured during the most recent
Method 2 performance test series, and that the flow rate indicator is
inspected annually. As another option to annual flow rate measurements
using Methods 1 and 2, the EPA is proposing to allow Methods 1 and 2
testing to be performed every 5 years provided that daily measurements
of the revolutions per minute (RPM) of the capture and collection
system's fan are taken, the readings are recorded daily and the fan RPM
is maintained at or above 90 percent of the RPM measured during the
most recent Method 2 performance test. Further, we are proposing that
as an alternative to the flow rate measurements using Methods 1 and 2,
the annual hood inspection requirements can be satisfied by conducting
annual verification of a permanent total enclosure using EPA Method
204. We are further proposing that as an alternative to the annual
verification of a permanent total enclosure using EPA Method 204,
verification can be performed once every 5 years if negative pressure
in the enclosure is directly monitored by a pressure indicator and
readings are recorded daily or the system is interlocked to halt
material feed should the system not operate under negative pressure. In
this supplemental proposal, we are also proposing that readings outside
a specified range would need to be investigated and steps taken to
restore normal operation, and that pressure indicators would need to be
inspected annually for damage and operability.
5. Sweat Furnace Operating and Monitoring Requirements
    We are also proposing to amend 40 CFR 63.1506(c) and 63.1510(d) to
provide sweat furnaces with alternative compliance options to the ACGIH
Guidelines and the required annual flow rate measurements using EPA
Methods 1 and 2. We are proposing that in lieu of meeting the ACGIH
guidelines for capture and collection and the annual flow rate
measurements using Methods 1 and 2, sweat furnaces may comply by
demonstrating negative air flow into or towards the sweat furnace
opening as well as operating and maintaining the sweat furnace in such
a way that minimizes fugitive emissions.
6. Startup, Shutdown, Malfunction and the Malfunction Affirmative
Defense
    In the 2012 proposal, we proposed to eliminate provisions that
exempt sources from the requirement to comply with the otherwise
applicable CAA section 112(d) emission standards during periods of
Startup, Shutdown and Malfunction (SSM). We explained in the 2012
proposal that because the scrap processed at secondary aluminum
production facilities is the source of emissions, we expect emissions
during startup and shutdown would be no higher, and most likely would
be significantly lower, than emissions during normal operations since
no scrap is processed during those periods. We stated that we knew of
no reason why the existing standards should not apply at all times. For
production processes in the Secondary Aluminum Production source
category where the standards are expressed in units of pounds per ton
of feed or similar units (i.e., thermal chip dyers, scrap dryer/
delacquering kiln/decoating kilns, dross-only furnaces, in-line fluxers
using reactive flux and group 1 furnaces), the 2012 proposal included a
method for demonstrating compliance with those limits based on
emissions measured during startup and shutdown.
    Because conducting meaningful testing during periods of startup and
shutdown can be problematic, in this supplemental proposal we are
proposing an additional method that can be used to demonstrate
compliance with production based emission limits during periods of
startup and shutdown. Together, these proposed compliance provisions
for periods of startup and shutdown better reflect the MACT requirement
for those periods. Recognizing that the source of HAP emissions is the
processing of scrap and the use of fluxes during processing and that
the heat for processing in the Secondary Aluminum Production source
category is generated exclusively by use of clean fuels--natural gas,
propane or electricity--we are proposing that compliance with emission
standards during startup and shutdown can be demonstrated by keeping
records that show that the feed/charge rate was zero, the flux rate was
zero and the affected source or emission unit either was heated with
electricity, propane or natural gas as the sole sources of heat or was
not heated (see proposed section 63.1513(f)). We are also proposing
that the following records be kept: The date and time of each startup
and shutdown, the quantity of feed/charge and flux introduced during
each startup and shutdown and the types of fuel used to heat the unit
during startup and shutdown.
    We are also proposing to define periods of startup and shutdown.
For the purposes of subpart RRR, startup means ``the period of
operation for thermal chip dryers, scrap dryers/delacquering kilns,
decoating kilns, dross-only furnaces, group 1 furnaces, in-line
fluxers, sweat furnaces and group 2 furnaces that begins with equipment
warming from a cold start or a complete shutdown. Startup ends at the
point that feed/charge is introduced.'' Shutdown means the period of
operation for thermal chip dryers, scrap dryers/delacquering kilns,
decoating kilns, dross-only furnaces, group 1 furnaces, in-line
fluxers, sweat furnaces and group 2 furnaces that begins when the
introduction of feed/charge is halted and all product has been removed
from the emission unit (e.g., by tapping a furnace).''
    We solicit comments and additional information related to the
proposed definitions of startup and shutdown, as well as the additional
option proposed in this supplemental proposal for demonstrating
compliance during

periods of startup and shutdown based on the presence (or absence) in
the furnace of feed/charge or fluxing, and the type of combustion fuels
or the absence of combustion fuels. We are also proposing to move the
requirements for compliance demonstration during startup and shutdown
from the emission standards section (section 63.1505), where they were
in the 2012 proposal, to the more appropriate compliance demonstration
section (section 63.1513). However, we are not soliciting comments on
the compliance demonstration method for periods of startup and shutdown
that was presented in the 2012 proposal.
    In the 2012 proposal, we proposed to eliminate provisions that
exempt sources from the requirement to comply with the otherwise
applicable CAA section 112(d) emission standards during periods of SSM.
We also included provisions for affirmative defense to civil penalties
for violations of emission standards caused by malfunctions. 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. As explained in the 2012
proposal (77 FR 8598), 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. Under 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 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 United States Court of Appeals for the District of
Columbia 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 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 section 112 standards.
    Further, 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. As a result, 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
section 112 to avoid such a result. The EPA's approach to malfunctions
is consistent with section 112 and is a reasonable interpretation of
the statute.
    In the 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.
    If the EPA determines in a particular case that 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,
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.
    As noted above, the 2012 proposal included an affirmative defense
to civil penalties for violations caused by malfunctions. The EPA
included the affirmative defense in the 2012 proposal as it had in
several prior rules in an effort to create a system that incorporates
some flexibility, recognizing that there is a tension, inherent in many
types of air regulation, to ensure adequate compliance while
simultaneously recognizing that despite the most diligent of efforts,
emission standards may be violated under circumstances entirely beyond
the control of the source. Although the EPA recognized that its case-
by-case enforcement discretion provides sufficient flexibility in these
circumstances, it included the

affirmative defense in the 2012 proposal and in several prior rules to
provide a more formalized approach and more regulatory clarity. See
Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1057-58 (D.C. Cir. 1978)
(holding that an informal case-by-case enforcement discretion approach
is adequate); but see Marathon Oil Co. v. EPA, 564 F.2d 1253, 1272-73
(9th Cir. 1977) (requiring a more formalized approach to consideration
of ``upsets beyond the control of the permit holder.''). Under the
EPA's regulatory affirmative defense provisions, if a source could
demonstrate in a judicial or administrative proceeding that it had met
the requirements of the affirmative defense in the regulation, civil
penalties would not be assessed. The United States Court of Appeals for
the District of Columbia Circuit vacated an affirmative defense in one
of the EPA's section 112(d) regulations. NRDC v. EPA, 749 F.3d 1055
(D.C. Cir. 2014) (vacating affirmative defense provisions in section
112 rule establishing emission standards for Portland cement kilns).
The court found that the EPA lacked authority to establish an
affirmative defense for private civil suits and held that under the
CAA, the authority to determine civil penalty amounts in such cases
lies exclusively with the courts, not the EPA. Specifically, the court
found: ``As the language of the statute makes clear, the courts
determine, on a case-by-case basis, whether civil penalties are
`appropriate.' '' See NRDC v. EPA, 749 F.3d 1055, 1063 (D.C. Cir. 2014)
(``[U]nder this statute, deciding whether penalties are `appropriate'
in a given private civil suit is a job for the courts, not for EPA.'').
In light of NRDC, the EPA is withdrawing its proposal to include a
regulatory affirmative defense provision in this rulemaking and in this
supplementary proposal has eliminated section 63.1520 (the provision
that established the affirmative defense in the proposed rule published
in the Federal Register on February 14, 2012 (77 FR 8576)). As
explained above, if a source is unable to comply with emissions
standards as a result of a malfunction, the EPA may use its case-by-
case enforcement discretion to provide flexibility, as appropriate.
Further, as the D.C. Circuit recognized, in an EPA or citizen
enforcement action, the court has the discretion to consider any
defense raised and determine whether penalties are appropriate. Cf.
NRDC v. EPA, 749 F.3d 1055, 1064 (D.C. Cir. 2014) (arguments that
violation were caused by unavoidable technology failure can be made to
the courts in future civil cases when the issue arises). The same logic
applies to EPA administrative enforcement actions.

E. What compliance dates are we proposing?

    In the 2012 proposal, the EPA proposed that owners or operators of
existing affected sources comply with the proposed amendments within 90
days of the publication of the final rule in the Federal Register.
Commenters stated that the proposed 90 day compliance deadline was
insufficient for sources to comply with certain provisions of the final
rule. They maintained that the rule changes would require operational
planning, maintenance planning, reprogramming of data acquisition
systems, design and installation of hooding equipment and/or
negotiations with permitting authorities to gain performance test plan
approvals (with provisions to minimize fugitive emissions during
testing in place of capture hoods). They pointed out that facilities
that choose to design and install capture hoods for performance testing
will need time to design and complete these installations, conduct
initial performance testing and modify their operations, charge
materials and/or products to ensure compliance. Some rule changes,
furnace switching, HF testing and testing uncontrolled furnaces for
example, would require revisions to operation, maintenance and
monitoring (OM&M) plans as well as to permits to include newly
established operating parameters in cases where changes to furnace
classifications are made. Commenters stated that compliance with HF
emission standards that may affect choice of flux materials, daily
calculation of HF emissions and compliance with SAPU limit that will
require reprogramming of data systems to include HF and/or fluoride
containing flux composition data would also require time to be
researched, selected, purchased, financed and installed. Commenters
suggested compliance deadlines ranging from 2 to 3 years.
    The EPA agrees with commenters that the proposed 90-day compliance
deadline is insufficient for sources to comply with certain provisions
of the final rule and is proposing extended compliance periods. The EPA
is proposing a 180-day compliance period for the revisions listed in
section 63.1501(d). For the amendments to include HF emissions (in
section 63.1505(i)(4) and (k)(2)), the testing of existing uncontrolled
furnaces (sections 63.1512(e)(4), (e)(5), (e)(6) and (e)(7)), and
changing furnace classification (section 63.1514), the EPA agrees that
a longer compliance period is required and is proposing a compliance
date of 2 years after promulgation.

V. Summary of the Revised Cost, Environmental and Economic Impacts

A. What are the affected sources?

    We estimate that there are 161 secondary aluminum production
facilities that will be affected by this proposed rule. We performed
risk modeling for 155 of these sources (52 of the 53 major sources and
103 of the 108 area sources). There were six facilities that are
subject to the Secondary Aluminum NESHAP that were not included in the
risk assessment input modeling files. The facilities that were not
included in the risk assessment input files included one major HAP
source and five area HAP sources. The major HAP source was not included
because the secondary aluminum equipment at the source consists of
group 2 furnaces, for which the EPA did not have HAP emissions
estimates. The five area sources were not included because they had no
equipment subject to D/F emission standards, which are the only
standards in the NESHAP applicable to area sources. We estimate that
nine secondary aluminum facilities have co-located primary aluminum
operations. The affected sources at secondary aluminum production
facilities include new and existing scrap shredders, thermal chip
dryers, scrap dryer/delacquering kiln/decoating kilns, group 2
furnaces, sweat furnaces, dross-only furnaces, rotary dross cooler and
secondary aluminum processing units containing group 1 furnaces and in-
line fluxers.

B. What are the air quality impacts?

    No changes are being proposed to numerical emissions limits. This
supplemental proposal affects the number of times that a furnace can
switch operating modes, clarifies how uncontrolled furnaces are to
conduct emissions testing, extends the compliance deadline, revises the
monitoring requirements for annual inspection of capture/collection
systems, clarifies the requirements for conducting performance testing
under worst case conditions and provides monitoring alternatives for
sweat furnaces. These proposed amendments would not have any
appreciable effect on emissions or result in emission reductions,
although the proposed requirements for testing uncontrolled furnaces
could result in some unquantifiable emission reduction. Therefore, no
quantifiable air quality impacts are expected. However, these

proposed amendments will help to improve compliance, monitoring and
implementation of the rule.

C. What are the cost impacts?

    We conservatively estimate the total cost of the proposed
amendments to be $1,711,000 per year (in 2011 dollars). However,
depending on assumptions used for the costs for installing temporary
hooding for uncontrolled furnaces, the estimate of total annualized
costs could range from $611,000 to $2,871,000 per year.
    Our estimate for the source category includes an annualized cost of
$1,200,000 to $3,460,000 for installing hooding that meets ACGIH
guidelines for testing uncontrolled furnaces, assuming that 107
furnaces choose that option (rather than assuming a 67-percent capture
efficiency for their existing furnace exhaust system). We believe that
a number of these 107 furnaces will choose to apply the 67-percent
assumption rather than install hooding. Therefore, these total cost
estimates are considered conservative (more likely to be overestimates
rather than underestimates) of the total costs to the industry. Our
estimates of total costs also include an annualized cost of $11,000 for
testing for HF on uncontrolled furnaces that are already testing for
HCl. Finally, we estimate cost savings of $600,000 per year for
furnaces that change furnace operating modes and turn off their control
devices. Our estimate of savings is based on 50 furnaces turning off
their controls for approximately 6 months every year. This savings
reflects the cost of testing (to demonstrate these furnaces remain in
compliance with emission limits) minus the savings realized from
operating with the control devices turned off.
    We estimate that 57 facilities will be affected and that the cost
per facility ranges from negative $36,000 (a cost savings) per year for
a facility changing furnace operating modes to $216,500 per year for a
facility installing hooding for testing.
    The estimated costs are explained further in the document titled
Updated Cost Estimates for the Proposed Rule Changes to Secondary
Aluminum NESHAP, which is available in the docket for this action.

D. What are the economic impacts?

    We performed an economic impact analysis for the proposed revisions
and amendments in this supplemental proposed rulemaking. This analysis
estimates impacts based on using annualized cost-to-sales ratios for
affected firms. For the 28 parent firms affected by this proposed rule,
the cost-to-sales estimate for each parent firm is less than 0.1
percent. For more information, please refer to the document titled
Economic Impact Analysis for the Secondary Aluminum Supplemental
Proposal, which is available in the docket.

E. What are the benefits?

    We do not anticipate any significant reductions in HAP emissions as
a result of these proposed amendments. However, we think that the
proposed amendments will help to improve the clarity of the rule, which
can improve compliance and minimize emissions. Certain provisions also
provide operational flexibility with no increase in HAP emissions.

VI. Request for Comments

    As discussed in detail above, we solicit comments on the revised
risk assessment and proposed changes presented in this supplemental
proposal. We are not re-opening comment on any other elements of the
2012 proposal (77 FR 8576, February 14, 2012). Comments previously
received on the 2012 proposal, along with comments received on and
within the scope of this supplemental proposal, will be addressed in
the final rulemaking action.
    We are also interested in any additional data that may help to
reduce the uncertainties inherent in the risk assessments and other
analyses. We are specifically interested in receiving corrections to
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 on the RTR
Web page at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html. 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 page, 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, etc.).
    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-2010-0544 (through one of the methods
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.
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 RTR Web
page at http://www.epa.gov/ttn/atw/rrisk/rtrpg.html.

VIII. Statutory and Executive Order Reviews

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

    This action is not a ``significant regulatory action'' under the
terms of Executive Order 12866 (58 FR 51735, October 4, 1993) and is,
therefore, not subject to review under Executive Orders 12866 and 13563
(76 FR 3821, January 21, 2011).

B. Paperwork Reduction Act

    The information collection requirements in this proposed action
have been submitted for approval to OMB under the Paperwork Reduction
Act, 44 U.S.C. 3501 et seq. The ICR document prepared by the EPA has
been assigned the EPA ICR number 2453.01.
    We are proposing changes to the paperwork requirements to the
Secondary Aluminum Production source category that were proposed in
2012.
    In addition, in the 2012 proposal, we included an estimate of the
burden associated with the affirmative defense in the ICR. However, as
explained above, we are withdrawing our proposal

to include affirmative defense provisions, and the burden estimate has
been revised accordingly.
    We estimate 161 regulated entities are currently subject to subpart
RRR. The annual monitoring, reporting and recordkeeping burden for this
collection (averaged over the first 3 years after the effective date of
the standards) for these amendments to subpart RRR is estimated to be
$2,990,000 per year. This includes 1,694 labor hours per year at a
total labor cost of $162,000 per year, and total non-labor capital and
operation and maintenance (O&M) costs of $2,828,000 per year. The total
burden for the federal government (averaged over the first 3 years
after the effective date of the standard) is estimated to be 271 labor
hours per year at an annual cost of $12,231. Burden is defined at 5 CFR
1320.3(b).
    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.
    To comment on the agency's need for this information, the accuracy
of the provided burden estimates and any suggested methods for
minimizing respondent burden, the EPA has established a public docket
for this rule, which includes this ICR, under Docket ID No. EPA-HQ-OAR-
2010-0544. Submit any comments related to the ICR to the EPA and OMB.
See the ADDRESSES section at the beginning of this document for where
to submit comments to the EPA. Send comments to OMB at the Office of
Information and Regulatory Affairs, Office of Management and Budget,
725 17th Street NW., Washington, DC 20503, Attention: Desk Office for
the EPA. Since OMB is required to make a decision concerning the ICR
between 30 and 60 days after December 8, 2014, a comment to OMB is best
assured of having its full effect if OMB receives it by January 7,
2015. The final rule will respond to any OMB or public comments on the
information collection requirements contained in this proposal.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency
to prepare a regulatory flexibility analysis of any rule subject to
notice and comment rulemaking requirements under the Administrative
Procedure Act, or any other statute, unless the agency certifies that
the rule will not have a significant economic impact on a substantial
number of small entities. Small entities include small businesses,
small organizations and small governmental jurisdictions.
    For purposes of assessing the impacts of this action on small
entities, small entity is defined as: (1) A small business as defined
by the Small Business Administration's (SBA) regulations at 13 CFR
121.201; (2) a small governmental jurisdiction that is a government of
a city, county, town, school district or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise that is independently owned and operated
and is not dominant in its field. For this source category, which has
the NAICS code 331314 (i.e., Secondary Smelting and Alloying of
Aluminum), the SBA small business size standard is 750 employees
according to the SBA small business standards definitions.
    After considering the economic impacts of these proposed changes on
small entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. We
determined in the economic and small business analysis that, using the
results from the cost memorandum, 28 entities will incur costs
associated with the proposed rule. Of these 28 entities, nine of them
are small. Of these nine, all of them are estimated to experience a
negative cost (i.e., a cost savings) as a result of the proposed action
according to our analysis. For more information, please refer to the
Economic Impact Analysis for the Secondary Aluminum Supplemental
Proposal, which is available in the docket.

D. Unfunded Mandates Reform Act

    This action does not contain a Federal mandate that may result in
expenditures of $100 million or more for state, local and tribal
governments, in the aggregate, or the private sector in any one year.
Thus, this action is not subject to the requirements of section 202 or
205 of the Unfunded Mandates Reform Act (UMRA).
    This action is also not subject to the requirements of section 203
of UMRA because it contains no regulatory requirements that might
significantly or uniquely affect small governments as it contains no
requirements that apply to such governments nor does it impose
obligations upon them.

E. 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, as
specified in Executive Order 13132. None of the facilities subject to
this proposed action are owned or operated by state governments. Thus,
Executive Order 13132 does not apply to this proposed action.
    In the spirit of Executive Order 13132, and consistent with the EPA
policy to promote communications between the EPA and State and local
governments, the EPA specifically solicits comment on this proposed
rule from state and local officials.

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

    This action does not have tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). There are no
secondary aluminum production facilities that are owned or operated by
tribal governments. Thus, Executive Order 13175 does not apply to this
action. The EPA specifically solicits additional comments on this
proposed action from tribal officials.

G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks

    This action is not subject to Executive Order 13045 (62 FR 19885,
April 23, 1997) because it is not economically significant as defined
in Executive Order 12866 and because the agency does not believe the
environmental health or safety risks addressed by this action present a
disproportionate risk to children. This action's health and risk
assessments are contained in sections III and IV of this document. The
public is invited to submit comments or identify peer-reviewed studies
and data that assess effects of early life exposures to the pollutants
emitted by this source category.

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

    This action is not subject to Executive Order 13211 (66 FR 28355,
May 22, 2001) because it is not a significant regulatory action under
Executive Order 12866.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Public Law 104-113 (15 U.S.C. 272 note),
directs the EPA to use voluntary consensus standards (VCS) in its
regulatory

activities unless to do so would be inconsistent with applicable law or
otherwise impractical. VCS are technical standards (e.g., materials
specifications, test methods, sampling procedures and business
practices) that are developed or adopted by VCS bodies. NTTAA directs
the EPA to provide Congress, through OMB, explanations when the agency
decides not to use available and applicable VCS.
    This proposed action involves technical standards. Therefore, the
agency conducted a search to identify potentially applicable VCS. The
VCS ASTM D7520-09, ``Standard Test Method for Determining the Opacity
of a Plume in the Outdoor Ambient Atmosphere'' was identified as an
acceptable alternative to EPA Method 9. The standard was developed and
is published by the American Society for Testing and Materials (ASTM).
The standard can be obtained by contacting ASTM at 100 Barr Harbor
Drive, Post Office Box C700, West Conshohocken, PA 19428-2959 or at
their Web site, http://www.astm.org.
    In addition, as a result of comments received on the 2012 proposal,
EPA Method 26 was identified as a reasonable alternative to EPA Method
26A and EPA Method 204 was identified as a reasonable alternative
method for EPA Methods 1 and 2. The EPA agrees that EPA Methods 26 and
204 are acceptable alternatives for use in this rule. Therefore, the
EPA has proposed adding ASTM D7520-09, ``Standard Test Method for
Determining the Opacity of a Plume in the Outdoor Ambient Atmosphere,''
as an alternative method for the currently required EPA Method 9; EPA
Method 26 as an alternative for the currently required EPA Method 26A;
and EPA Method 204 as an alternative to the currently required EPA
Methods 1 and 2.
    The EPA welcomes comments on this aspect of the proposed rulemaking
and, specifically, invites the public to identify potentially-
applicable VCS and to explain why such standards should be used in this
regulation.

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

    Executive Order 12898 (59 FR 7629, February 16, 1994) establishes
federal executive policy on environmental justice. Its main provision
directs federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies and activities on minority populations and low-income
populations in the United States.
    The EPA has determined that this proposed rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it does not
affect the level of protection provided to human health or the
environment. This proposed rule will not relax the emission limits on
regulated sources and will not result in emissions increases.
    Because our residual risk assessment determined that there was
minimal residual risk associated with the emissions from facilities in
this source category, a demographic risk analysis was not necessary for
this category. However, the EPA did conduct a proximity analysis for
both area and major sources. The results of these analyses are
summarized in section IV.A.6 of this notice and in more detail in the
EJ Screening Report for Area Sources and the EJ Screening Report for
Major Sources, which are available in the docket for this rulemaking.

List of Subjects in 40 CFR Part 63

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

    Dated: November 13, 2014.
Gina McCarthy,
Administrator.
    For the reasons stated in the preamble, part 63 of title 40,
chapter I, of the Code of Federal Regulations is proposed to be amended
as follows:

PART 63--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS
FOR SOURCES CATEGORIES

0
1. The authority citation for part 63 continues to read as follows:

    Authority: 42 U.S.C. 7401 et seq.

Subpart RRR--NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR
POLLUTANTS FOR SECONDARY ALUMINUM PRODUCTION

0
2. Section 63.1501 is amended by adding paragraphs (d), (e), and (f) to
read as follows:

Sec.  63.1501  Dates.

* * * * *
    (d) The owner or operator of an existing affected source must
comply with the following requirements of this subpart by [DATE 180
DAYS FROM PUBLICATION OF THE FINAL RULE IN THE Federal Register]: Sec.
63.1505 (k) introductory text, (k)(1) through (k)(5), other than the
emission standards for HF in (k)(2); Sec.  63.1506 (a)(1), (c)(1),
(g)(5), (k)(3), (m)(4), (n)(1); Sec.  63.1510, (b)(5), (b)(9), (d)(2),
(d)(3), (f)(1)(ii), (i)(4), (j)(4), (n)(1), (o)(1), (o)(1)(ii),
(s)(2)(iv), (t) introductory text, (t)(2)(i), (t)(2)(ii), (t)(4),
(t)(5); Sec.  63.1511(a) introductory text, (b) introductory text,
(b)(1), (b)(6), (c)(9), (f)(6), (g)(5); Sec.  63.1512(e)(1), (e)(2),
(e)(3), (h)(2), (j), (j)(1)(i), (j)(2)(i), (o)(1), (p)(2); Sec.
63.1513(b) introductory text, (b)(1), (e)(1), (e)(2), (e)(3), (f);
Sec.  63.1516 (b) introductory text, (b)(2)(iii), (b)(3), (d); Sec.
63.1517(b)(16)(i), (b)(18), (b)(19), (c).
    (e) The owner or operator of an existing affected source must
comply with the following requirements of this subpart by [DATE 2 YEARS
FROM PUBLICATION OF THE FINAL RULE IN THE Federal Register]: Sec.
63.1505(i)(4) and (k)(2) emission standards for HF; Sec.  63.1512(e)(4)
through (7) requirements for testing existing uncontrolled group 1
furnaces; and Sec.  63.1514 requirements for change of furnace
classification.
    (f) The owner or operator of a new affected source that commences
construction or reconstruction after February 14, 2012 must comply with
all of the requirements listed in paragraphs (d) and (e) of this
section by [DATE OF PUBLICATION OF THE FINAL RULE IN THE Federal
Register] or upon startup, whichever is later.
0
3. Section 63.1503 is amended by adding in alphabetical order
definitions for ``round top furnace,'' ``shutdown,'' and ``startup'' to
read as follows:

Sec.  63.1503  Definitions.

* * * * *
    Round top furnace means a cylindrically-shaped reverberatory
furnace that has a top that is removed for charging and other furnace
operations.
* * * * *
    Shutdown means the period of operation for thermal chip dryers,
scrap dryers/delacquering kilns, decoating kilns, dross-only furnaces,
group 1 furnaces, in-line fluxers, sweat furnaces and group 2 furnaces
that begins when the introduction of feed/charge is halted and all
product has been removed from the emission unit (e.g., by tapping a
furnace).
* * * * *
    Startup means the period of operation for thermal chip dryers,
scrap dryers/delacquering kilns, decoating kilns, dross-only furnaces,
group 1 furnaces, in-line fluxers, sweat furnaces and group 2 furnaces
that begins with equipment warming from a cold start or

a complete shutdown. Startup ends at the point that feed/charge is
introduced.
* * * * *
0
4. Section 63.1506 is amended by adding paragraph (c)(4) to read as
follows:

Sec.  63.1506  Operating requirements.

* * * * *
    (c) * * *
    (4) In lieu of paragraph (c)(1) of this section, the owner or
operator of a sweat furnace may design, install and operate each sweat
furnace in accordance with paragraphs (c)(4)(i) through (iii) of this
section.
    (i) As demonstrated by an annual negative air flow test conducted
in accordance with Sec.  63.1510(d)(3), air flow must be into the sweat
furnace or towards the plane of the sweat furnace opening.
    (ii) The owner or operator must maintain and operate the sweat
furnace in a manner consistent with the good practices requirements for
minimizing emissions, including fugitive emissions, in paragraph (a)(5)
of this section. Procedures that will minimize fugitive emissions may
include, but are not limited to the following:
    (A) Increasing the exhaust rate from the furnace with draft fans,
so as to capture emissions that might otherwise escape from the sweat
furnace opening;
    (B) Minimizing the time the sweat furnace doors are open;
    (C) Keeping building doors and other openings closed to the
greatest extent possible to minimize drafts that would divert emissions
from being drawn into the sweat furnace;
    (D) Maintaining burners on low-fire or pilot operation while the
doors are open;
    (E) Conducting periodic inspections and maintenance of sweat
furnace components to ensure their proper operation and performance
including but not limited to, door assemblies, seals, combustion
chamber refractory material, afterburner and stack refractory, blowers,
fans, dampers, burner tubes, door raise cables, pilot light assemblies,
baffles, sweat furnace and afterburner shells and other internal
structures.
    (iii) The owner or operator must document in their OM&M plan the
procedures to be used to minimize emissions, including fugitive
emissions, in addition to the procedures to ensure the proper operation
and maintenance of the sweat furnace.
* * * * *
0
5. Section 63.1510 is amended by revising paragraph (d)(2) and adding
paragraph (d)(3) to read as follows:

Sec.  63.1510  Monitoring requirements.

* * * * *
    (d) * * *
    (2) Inspect each capture/collection and closed vent system at least
once each calendar year to ensure that each system is operating in
accordance with the operating requirements in Sec.  63.1506(c) and
record the results of each inspection. This inspection shall include a
volumetric flow rate measurement taken at a location in the ductwork
downstream of the hoods that is representative of the actual volumetric
flow rate without interference due to leaks, ambient air added for
cooling or ducts from other hoods. The flow rate measurement must be
performed in accordance with paragraphs (d)(2)(i), (ii), or (iii) of
this section. As an alternative to the flow rate measurement specified
in this paragraph, the inspection may satisfy the requirements of this
paragraph, including the operating requirements in Sec.  63.1506(c), by
including permanent total enclosure verification in accordance with
(d)(2)(i) or (iv) of this section.
    (i) Conduct annual flow rate measurements using EPA Methods 1 and 2
in Appendix A to 40 CFR part 60, or conduct annual verification of a
permanent total enclosure using EPA Method 204; or
    (ii) As an alternative to annual flow rate measurements using EPA
Methods 1 and 2, measurement with EPA Methods 1 and 2 can be performed
once every 5 years, provided that:
    (A) A flow rate indicator consisting of a pitot tube and
differential pressure gauge (Magnehelic[supreg], manometer or other
differential pressure gauge) is installed with the pitot tube tip
located at a representative point of the duct proximate to the location
of the Methods 1 and 2 measurement site; and
    (B) The flow rate indicator is installed and operated in accordance
with the manufacturer's specifications; and
    (C) The differential pressure is recorded during the Method 2
performance test series; and
    (D) Differential pressure readings are recorded daily, and
maintained at or above 90 percent of the pressure differential
indicated by the flow rate indicator during the most recent Method 2
performance test series; and
    (E) An inspection of the pitot tube and associated lines for
damage, plugging, leakage and operational integrity is conducted at
least once per year; or
    (iii) As an alternative to annual flow rate measurements using EPA
Methods 1 and 2, measurement with EPA Methods 1 and 2 can be performed
once every 5 years, provided that:
    (A) Daily measurements of the capture and collection system's fan
revolutions per minute (RPM) are made by taking three measurements with
at least 5 minutes between each measurement, and averaging the three
measurements; and
    (B) Readings are recorded daily and maintained at or above 90
percent of the RPM measured during the most recent Method 2 performance
test series.
    (iv) As an alternative to the annual verification of a permanent
total enclosure using EPA Method 204, verification can be performed
once every 5 years, provided that:
    (A) Negative pressure in the enclosure is directly monitored by a
pressure indicator installed at a representative location;
    (B) Pressure readings are recorded daily or the system is
interlocked to halt material feed should the system not operate under
negative pressure;
    (C) When there are readings outside the range specified in the OM&M
plan, the facility investigates and takes steps to restore normal
operation, which may include initial inspection and evaluation,
recording that operations returned to normal without operator action or
other applicable actions; and
    (D) An inspection of the pressure indicator for damage and
operational integrity is conducted at least once per calendar year.
    (3) In lieu of paragraph (d)(2) of this section, the owner or
operator of a sweat furnace may inspect each sweat furnace at least
once each calendar year to ensure that they are being operated in