derive the MACT floor limit. For more information on how we calculated
the MACT floors and other emission limits, see the Ferroalloys
Production MACT Floor Analysis document, which is available in the
docket.
    Using this method, the MACT floor (or 99 percent UPL) for exhaust
mercury concentrations from existing furnaces is 80 [micro]g/dscm at 2
percent carbon dioxide (CO2). This MACT floor limit is
higher than the actual emissions measured during the ICR performance
tests at each plant. Therefore, we anticipate that both of the existing
sources would be able to meet this limit without installing additional
controls.
    With regard to new sources, as described above, the MACT floor for
new sources cannot be less stringent than the emissions performance
that is achieved in practice by the best-controlled similar source. A
variability analysis similar to that used for existing sources was then
performed to calculate a 99 percent UPL using the three run test data
from the top source. For this source category, we calculate that the
UPL MACT floor limit for new sources is 16 [micro]g/dscm at 2 percent
CO2. This limit is based on the performance of the best
performing source.
    The next step in establishing MACT standards is the beyond the
floor analysis. In this step, we investigate other mechanisms for
further reducing HAP emissions that are more stringent than the MACT
floor level of control in order to ``require the maximum degree of
reduction in emissions'' of HAP. In setting such standards, section
112(d)(2) requires the Agency to consider the cost of achieving the
additional emission reductions, any non-air quality health and
environmental impacts, and energy requirements. Historically, these
factors have included factors such as solid waste impacts of a control,
effects of emissions on bodies of water, as well as the energy impacts.
    As described below, we considered beyond-the-floor control options
to further reduce emissions of mercury. Because of our limited data
set, we considered setting a MACT limit for existing sources based on
the performance of the best performing source (i.e., based upon the
test data used to calculate the MACT floor for new sources) such that
the MACT limit for existing sources would be the same as the UPL MACT
limit for new sources (i.e., 16 [micro]g/dscm). Under this option, the
best performing source would need no additional controls to meet the
limit, since their current performance defines the new source limit.
With regard to the other facility in the source category, as described
below, we believe this limit could be achieved by the addition of an
activated carbon injection system, which is a proven technology for
mercury control. Compliance would be demonstrated by periodic
performance testing and continuous parameter monitoring.
    In evaluating a beyond the floor option, we evaluate, among other
things, the costs of achieving additional emission reductions beyond
the floor level of control. No facilities in the source category use
add-on control devices or work practices to limit mercury emissions
beyond what is

achieved as co-control of the emissions with the particulate matter
control device. However, we identified both carbon bed technology and
activated carbon injection as commercially available mercury emission
reduction techniques. Carbon bed technology (which is one of the
primary control devices used at Industrial Gold Production facilities
in the U.S. to minimize mercury emissions, as described in the proposed
rule for that category \31\) does not appear to be a viable technology
to control the large volumes of airflow generated by the electric arc
furnaces in the Ferroalloys Production source category. The carbon bed
technology is applicable to gas streams with low volumes of airflow,
and is characterized with relatively high pressure drops. Accordingly
this technology is not used in industries with high volumes of airflow,
such as industrial boilers and power plants.
---------------------------------------------------------------------------

    \31\ National Emission Standards for Hazardous Air Pollutants:
Gold Mine Ore Processing and Production Area Source Category.
Proposed Rule (75 FR 22470);
---------------------------------------------------------------------------

    In contrast, activated carbon injection has been used to control
mercury emissions at various types of facilities that have large
volumes of airflow including some coal-fired power plants, waste
incinerators and cement kilns. Based on available information,
activated carbon injection appears to be a technologically feasible
control for mercury for these larger volume combustion sources. Mercury
reductions of up to 90 or 95 percent have been reported at these other
sources and should also be achievable at ferroalloys production
facilities. Based on data and information on these mercury controls for
other combustion sources (such as utility boilers, incinerators and
cement kilns), and based on our experience with these controls, we
conclude that activated carbon injection is a viable control technology
for the Ferroalloys Production source category.
    Activated carbon injection can be installed upstream or downstream
of an existing particulate matter control device. In cases where a
source is concerned about potential impacts of waste carbon on the
source's waste stream and resulting disposal options or the ability to
sell or reuse baghouse dust, the source can install the activated
carbon injection downstream of the particulate matter control device
with a separate polishing baghouse to collect the carbon. In other
cases, the source can install the activated carbon injection upstream
of the particulate matter control device and use the existing
particulate control device to remove the carbon from the airstream.
    We reviewed facility specific control options that included putting
the mercury controls downstream of the existing furnace baghouse to
avoid the potential issues with sale or reuse of baghouse dust
associated with upstream controls. Under this scenario, the activated
carbon injection system would be followed by a ``polishing'' baghouse
to capture the activated carbon for disposal. In the case of the
existing furnace scrubber, we assumed the source could put the
activated carbon injection system upstream of the scrubber, the carbon
would be captured by the scrubber and the resulting sludge treated
according to the existing treatment process at the plant. Based on
discussion \32\ with a vendor and other control technology experts, we
do not believe that the resulting carbon waste in either scenario would
trigger waste disposal concerns. We request comment on these
assumptions.
---------------------------------------------------------------------------

    \32\ Conversation with D. Lipscomb, Albemarle. August 22, 2011.
---------------------------------------------------------------------------

    We estimate that under this beyond the floor option described above
(i.e., a proposed limit of 16 [micro]g/dscm), that one facility would
need to install additional controls such as activated carbon injection
to meet this limit, and that this would achieve about 420 pounds of
reduction per year in mercury emissions. The capital costs are
estimated to be $1.7 million, annualized capital and operating costs to
be $1.4 million, with an overall cost-effectiveness of $3,300 per
pound. The general range of costs for mercury controls from other MACT
rules has been about $1,250 to $55,200 per pound of mercury removed (76
FR 25075, May 3, 2011). The EPA requests information on other control
technologies available to Ferroalloys Production manufacturers to
reduce mercury emissions. Other controls might include process changes,
substitution of materials, collection or enclosure systems, work
practices, or combinations of such methods; which reduce the volume of
mercury emissions from existing sources.
    It is important to note that there is no bright line for
determining cost-effectiveness. Each rulemaking is different and
various factors must be considered. Nevertheless, the cost-
effectiveness of mercury controls in this proposed rule for Ferroalloys
Production is near the lower end of the range. Some of the factors we
consider in determining the costs of control technologies under section
112(d)(2) include, but are not limited to the following: total capital
costs; annual costs; and costs compared to total revenues (e.g., costs
to revenue ratios). Other factors besides cost are considered into our
decision. For example, whether the standards significantly impact one
or more small businesses, whether the controls would significantly
impact production, and whether, and to what extent, the controls result
in adverse impacts to other media (e.g., hazardous waste issues). We
propose that these mercury controls are feasible for the Ferroalloys
Production source category from a technical standpoint and are cost
effective. We are proposing a MACT standard for mercury emissions of 16
[micro]g/dscm for both existing and new sources under the authority of
sections 112(d)(2) and (d)(3). To meet this proposed limit, we have
preliminarily determined that activated carbon injection is feasible to
implement for the Ferroalloys Production source category from a
technical standpoint and that control costs fall within the range of
other mercury controls in other MACT rules. More information regarding
how the MACT standards were calculated and the costs is provided in
Ferroalloys Production MACT Floor and Cost Memos, which are available
in the docket for this rulemaking.
    We are requesting comment on the proposed standard of 16 [micro]g/
dscm for mercury. We also seek comments and information on our
conclusion that activated carbon injection technology to meet the
mercury emissions limit for this source category is technically and
economically feasible. Moreover, we seek comments on the factors
related to costs and economics (such as those described in the
paragraph above) regarding the feasibility and costs of activated
carbon injection for this industry. We also seek comments on other
possible controls that could be effective to reduce mercury emissions
beyond the floor, including the amount and cost of the resulting
emissions reductions. Furthermore, we seek comment on whether work
practices to minimize mercury emissions, such as switching to manganese
ores with low mercury content, could be technically and economically
feasible.
    Moreover, we request comment on whether there is a basis to
subcategorize manganese production operations for mercury. For example,
is there a basis on which to subcategorize ferromanganese production
and silicomanganese production processes? Although we are requesting
comment on subcategorization, we do not believe that subcategorization
would have any substantive effect on the resulting standards or the
costs of controls since

there would be no change in the costs and feasibility of mercury
controls evaluated for these sources.
    We are proposing that any source installing activated carbon
injection would be required to continuously monitor the carbon
injection rate into the airstream being controlled. We request comment
on the level of variability in the carbon injection rate that should be
allowed, and what percent decrease in the rate should be considered
significant.
    We also propose that sources monitor the mercury content in the
manganese ore. Specifically, we propose that the determination of a
significant increase in mercury content would be that the 12-month
rolling weighted average mercury concentration based on monthly
sampling in the manganese ore increases by 10 percent or more compared
to the baseline weighted average mercury concentration. If that limit
is exceeded, the source would be required to readjust the carbon
injection rate as specified in the source's monitoring plan or retest
within 30 days if there is not a dedicated mercury control device. If a
new ore is added, sampling would be required as well.
    We request comment on this ore monitoring provision. We are
especially interested in any data that would show the variability in
mercury concentration between different ore samples from the same
location and the variability of the types of ores used in manganese
production. If ore type and mercury content are demonstrated to be
stable, we might consider reducing the frequency of sampling/
calculations to quarterly or less.
2. Polycyclic Aromatic Hydrocarbons (PAHs)
    PAH emissions are products of incomplete combustion from the
smelting operation, and a subset of the listed HAP POM. Some of these
emissions are likely to be in particulate form, but a significant
portion is expected to be in a gaseous form. Therefore, the existing
particulate matter control devices only achieve partial control of
these compounds. No existing facilities in the source category control
PAH or use work practices to limit emissions of PAH emissions
specifically. However, under today's proposal, these pollutants would
be controlled with the same activated carbon injection technology as
mercury. Because of this, emission reductions could be achieved via co-
control at no additional costs. Pursuant to CAA section 112(d)(2) and
112(d)(3), we are proposing to revise the 1999 NESHAP to include an
emission limit for PAH.
    We have stack test data from only one furnace for PAH emissions. As
such, the MACT floor would be based on the performance level achieved
at that furnace (i.e., the average emissions of that furnace plus an
amount to account for variability). Based on these data and applying
the 99 percent UPL, we calculate that the MACT floor limit for PAHs
would be 887 [micro]g/dscm. We also evaluated control performance that
could be achieved via co-control of mercury emissions with activated
carbon injection as a beyond-the-floor option. Based on information
from carbon vendors, an activated carbon system that is designed to
achieve a 90 percent reduction in mercury emissions (which we expect
would be applied to meet the proposed mercury standard discussed above)
should also achieve a high degree of reduction in PAH with no
additional costs. Assuming a 90 percent reduction from the calculated
99 percent UPL of 887 [micro]g/dscm, the resulting limit would be 89
[micro]g/dscm. Thus, a proposed limit for PAHs of 89 [micro]g/dscm
could be achieved with the same controls needed for mercury with no
additional costs.
    Therefore, pursuant to CAA sections 112(d)(2) and (d)(3), we are
proposing to revise the 1999 NESHAP to include an emission limit for
PAH of 89 [micro]g/dscm for new and existing sources.
3. Hydrochloric acid
    Hydrochloric acid (HCl) is a product of combustion, and the level
of emissions is dictated by the chlorine content of the coal or coke
used as a reducing agent in the smelting process. Based on test data
from the ICR, we estimate that the two facilities in this source
category emit 6 to 11 tpy of HCl. While these levels of emissions are
nontrivial, they are relatively low compared to some other types of
combustion sources. The primary reason for this is that manganese
producers use coke instead of coal as the primary reducing agent in the
smelting operation. Because coke is a refined product, much of the
original chlorine content in the coal is removed in the coking process,
which greatly reduces potential emissions. Second, one of the five
furnaces at these plants is equipped with a scrubber, which provides
co-control of particulate matter and HCl emissions. Notwithstanding the
relatively low HCl emissions from facilities in this source category,
section 112(d) requires us to set MACT for HAP emitted from the source
category. Pursuant to CAA section 112(d)(2) and 112(d)(3), we are
proposing to revise the 1999 NESHAP to include emission limits for HCl.
    As discussed above, the MACT floor limit is calculated based on the
average performance of the units in each category plus an amount to
account for these units' variability. To account for variability in the
operation and emissions, the stack test data were used to calculate the
average emissions and the 99 percent UPL to derive the MACT floor
limit. However, a number (50 percent) of the individual data points
were reported as below the applicable test detection limits.\33\ The
following discussion describes how we handle such data in our MACT
calculations. Also, as described below, we request comment on how this
uncertainty might influence establishing an emission limit instead of a
work practice standard.
---------------------------------------------------------------------------

    \33\ We conducted this analysis for all measured pollutant
according to the following method when non detects were reported.
However only the hydrochloric acid and formaldehyde data needed a
detection limit correction to adequately account for variability, as
described below.
---------------------------------------------------------------------------

    Test method measurement imprecision is a contributor to the
variability of a set of emissions data. One element is associated with
method detection capabilities and a second is a function of the
measurement value. Measurement imprecision is proportionally highest
for values measured below or near a method's detection level and
proportionally lower for values measured above the method detection
level.
    The probability procedures applied in calculating the MACT floor or
beyond the floor emissions limit inherently and reasonably account for
emissions data variability including measurement imprecision when the
database represents multiple tests from multiple emissions units for
which all of the data are measured significantly above the method
detection level. This is less true when the database includes some
emissions occurring below method detection capabilities that are
reported as the method detection level values.
    The EPA's guidance to facilities for reporting pollutant emissions
in response to the ICR data collection specified the criteria for
determining test-specific method detection levels. Those criteria
ensure that there is only about a 1 percent probability of an error in
deciding that the pollutant measured at the method detection level is
present when in fact it was absent. Such a probability is also called a
false positive or an alpha, Type I, error. Because of sample and
emissions matrix effects, laboratory techniques, sample size, and other
factors, method detection levels normally vary from test to test for
any specific test method and pollutant measurement. The expected

measurement imprecision is 40 to 50 percent or greater at levels
measured at the method detection level or less. The expected
measurement imprecision decreases to 10 to 15 percent for values
measured at a level about three times the method detection level or
greater.\34\
---------------------------------------------------------------------------

    \34\ American Society of Mechanical Engineers, Reference Method
Accuracy and Precision (ReMAP): Phase 1, Precision of Manual Stack
Emission Measurements, CRTD Vol. 60, February 2001.
---------------------------------------------------------------------------

    Also in accordance with our guidance, source owners identified
emissions data which were measured below the method detection level and
reported those values as equal to the method detection level as
determined for that test. An effect of reporting data in this manner is
that the resulting database is somewhat truncated at the lower end of
the measurement range (i.e., no values reported below the test-specific
method detection level). A MACT floor or beyond the floor emissions
limit based on a truncated database or otherwise including values
measured near the method detection level may not adequately account for
measurement imprecision contribution to the data variability.
    We applied the following procedures to account for the effect of
measurement imprecision associated with a database that includes method
detection level data. The following process also addresses the concerns
associated with use of a small data set, such as the Ferroalloys
Production data set for HCl. As a first step, we reviewed an HCl
emissions data set for the industrial boilers rule, which represents
several hundred emissions tests used in the floor calculations (i.e.,
best performers) for the boilers rule to determine typical method
detection levels. We have data from multiple industrial boilers tests
and used those data to confirm that method detection levels that
testers reported were as good as or better (i.e., lower) than the
values reported in the method. We presume that data for the best
performing units also reflect the capabilities of high quality testing
companies and laboratories. Further, the method detection levels
calculated from larger data sets are more representative of the
inherent measurement variability both within and between testing
companies than the limited Ferroalloys Production dataset. We believe
that emissions tests conducted with these methods for most combustion
operations (e.g., fossil fuel, biomass, and waste fired units; brick
and clay kilns; Portland cement kilns), including ferroalloys
production, should produce method detection levels very similar to the
level of 60 [micro]g/dscm that is the result of this review.
    The second step in the process was to calculate three times the RDL
and compare that value to the calculated MACT floor or beyond the floor
emissions limit. We use the multiplication factor of three to
approximate a 99 percent upper confidence interval for a data set of
seven or more values. If three times the RDL was less than the
calculated MACT floor emissions limit calculated from the UPL, we would
conclude that measurement variability was adequately addressed. The
calculated MACT floor or beyond the floor emissions limit would need no
adjustment. If, on the other hand, the value equal to three times the
RDL was greater than the UPL, we would conclude that the calculated
MACT floor or beyond the floor emissions limit does not account
entirely for measurement variability. If indicated, we substituted the
value equal to three times the RDL to apply as the adjusted MACT floor
or beyond the floor emissions limit. This adjusted value would ensure
measurement variability is adequately addressed in the MACT floor or
the beyond the floor emissions limit.
    For HCl, three times the RDL was less than the calculated 99
percent UPL for exhaust HCl concentration from existing furnaces. Thus,
for existing sources, the MACT floor for HCl is set at the UPL, or 809
[micro]g/dscm corrected to 2 percent CO2.
    Consistent with CAA section 112(d)(3), the MACT floor for new
sources cannot be less stringent than the emissions control that is
achieved in practice by the best-controlled similar source. The 99
percent UPL calculated for HCl based on the best performing source is
less stringent than the MACT floor for HCl at existing furnaces. We
determined that the use of the best performing source UPL is not
appropriate in this situation because the high variability and small
data pool would result in a new source MACT floor limit that is less
stringent than the limit based on the UPL calculated from the larger
data pool for existing sources. Given that the 99 percent UPL for new
sources is higher than the 99 percent UPL for existing sources, we
determined that the MACT limit for new sources should be equal to the
MACT limit for existing sources.
    We then considered a beyond-the-floor option to further reduce
emissions of HCl at existing sources based on application of additional
add-on control devices, such as lime injection, but their use is not
indicated given the high costs of installing and operating such
controls. There is also concern that use of this technology could
prevent the current practice of reusing or selling baghouse dust and
the resulting waste reduction benefits. See the Draft MACT Floor
Analysis for the Ferroalloys Production Source Category in the docket
for more discussion of this topic.
    Therefore, pursuant to CAA sections 112(d)(2) and 112(d)(3), we are
proposing to revise the 1999 NESHAP to include emission limits for new
and existing sources for HCl of 809 [micro]g/dscm. At this level, we do
not anticipate that either source would be required to install controls
to meet the limits. For more information on how these limits were
derived, see the Draft MACT Floor Analysis for the Ferroalloys
Production Source Category. As described above, there are some
measurements (i.e., 50 percent) reported as below the method detection
level. Because of the potential uncertainty in basing a limit partially
on non-detect values, we considered the possibility of proposing work
practice standards such as a limit on the amount of coal (the primary
source of chlorine in the raw materials) in lieu of numerical emission
limits. We request comment on whether this or other work practices
might be appropriate.
4. Formaldehyde
    Formaldehyde emissions are also products of incomplete combustion
from the smelting operation. Based on test data from the ICR, we
estimate that the two facilities in this source category emit
approximately 2 tpy of formaldehyde. Pursuant to CAA section 112(d)(2)
and 112(d)(3), we are proposing to revise the 1999 NESHAP to include
emission limits for formaldehyde.
    The measured average formaldehyde emissions ranged from 57 to 78
[micro]g/dscm corrected to 2 percent CO2. Because the
formaldehyde emissions data included some data points (50 percent)
reported as below the detection limit, we employed a version of the
methodology used for HCl to determine the MACT floor. However, in this
case we lack the underlying large data set of formaldehyde method
detection limits that we had for HCl method detection limits. In this
case, the first step was to define a method detection level that is
representative of the data used in defining the best performers for the
inclusive source category (i.e., combined data for all subcategories).
We identified all of the available reported pollutant specific method
detection levels and calculated the arithmetic mean value. We deemed
the resulting mean of the method detection levels as the (RDL). Three
times the RDL was

greater than the calculated 99 percent UPL for exhaust formaldehyde
concentrations from existing furnaces, resulting in a MACT floor of
three times the RDL, or 201 [micro]g/dscm at 2 percent CO2.
Based on available data, all of the existing sources could meet this
limit without installing additional controls.
    Due to the high variability in the data pool, the 99 percent UPL
for the best-performing source is less stringent than the existing
source MACT floor. Therefore, pursuant to CAA section 112(d)(2) and
112(d)(3), we are proposing to revise the 1999 NESHAP to include an
emission limit for formaldehyde for new and existing sources of 201
[micro]g/dscm based on the MACT floor calculation. We have not
identified any appropriate beyond-the-floor control technology options
specifically for formaldehyde. We recognize the potential for some co-
control of formaldehyde emissions that would be achieved by using
activated carbon injection to control mercury emissions, but we were
unable to quantify those reductions. More information regarding how the
MACT limits were calculated and the costs is provided in Ferroalloys
Production MACT Floor and Cost Memos, which are available in the docket
for this rulemaking. Finally, because of the potential uncertainty in
basing a limit partially on non-detect values, we considered the
possibility of proposing work practice standards. We request comment on
whether there are any work practices that might be appropriate.

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

    As described above, for the Ferroalloys Production source category,
we conducted an inhalation risk assessment for all HAP emitted. We also
conducted multipathway screening analyses for mercury and POM. Details
of the risk assessment and additional analyses can be found in the
residual risk documentation referenced in section III.B of this
preamble, which is available in the docket for this action. The Agency
considered the available health information--the MIR; the numbers of
persons in various risk ranges; cancer incidence; the maximum non-
cancer HI; the maximum worst-case acute non-cancer HQ; the extent of
non-cancer risks; the potential for adverse environmental effects; and
distribution of risks in the exposed population (54 FR 38044, September
14, 1989) in developing the proposed CAA section 112(f)(2) standards
for the Ferroalloys Production source category.
1. Inhalation Risk Assessment Results
    Table 5 of this preamble provides an overall summary of the results
of the inhalation risk assessment.

                                           Table 5--Ferroalloys Production Inhalation Risk Assessment Results
--------------------------------------------------------------------------------------------------------------------------------------------------------
   Maximum individual cancer risk  (in 1                                                   Maximum chronic non-cancer TOSHI \3\
               million) \1\                 Estimated population    Estimated annual   --------------------------------------------   Maximum screening
------------------------------------------- at increased risk of    cancer incidence                                                acute non- cancer HQ
   Based on actual     Based on allowable     cancer  >= 1-in-1     (cases per year)       Based on actual     Based on allowable            \4\
 emissions level \2\     emissions level           million                                 emissions level       emissions level
--------------------------------------------------------------------------------------------------------------------------------------------------------
               80                   100                26,000                 0.002                    90                   200                    10
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Estimated maximum individual excess lifetime cancer risk due to HAP emissions from the source category.
\2\ Based on the consistent views of major scientific bodies (i.e., NTP in their 12th Report on Carcinogens, IARC, and other international agencies)
  that consider all nickel compounds to be carcinogenic, we currently consider all nickel compounds to have the potential of being as carcinogenic as
  nickel subsulfide. To implement this approach we apply the nickel subsulfide IRIS URE without a factor to reflect the assumption that 100 percent of
  the total mass of nickel may be carcinogenic. The EPA also considers it reasonable to use a value that is 50 percent of the IRIS URE for nickel
  subsulfide for providing an estimate of the lower end of a plausible range of cancer potency values for different mixtures of nickel compounds. If the
  lower end of the nickel URE range is used, the maximum individual lifetime cancer risk based on actual emissions would be 50 in 1 million. The
  allowable cancer risk would remain 100 in a million because at one facility nickel is not the primary cancer driver. The estimated annual cancer
  incidence would also be reduced, but due to our presentation of incidence to one significant figure, remains 0.002. Estimated population values are
  not scalable with the nickel URE range, but would be lower using the lower value.
\3\ Maximum TOSHI. The target organ with the highest TOSHI for the Ferroalloys Production source category is the central nervous system.
\4\ The maximum off-site HQ acute value of 10 is driven by emissions of nickel. See section III.B of this preamble for explanation of acute dose-
  response values.

    The results of the chronic baseline inhalation cancer risk
assessment indicate that, based on estimates of current actual
emissions, the current maximum individual lifetime cancer risk posed by
these two facilities could be up to 80 in one million (50 in one
million with the lower nickel URE value), with process fugitive
emissions (from the furnace, crushing operation, and casting) of
nickel, chromium and arsenic as major contributors to the risk. The
total estimated cancer incidence from this source category based on
actual emission levels is 0.002 excess cancer cases per year or one
case in every 500 years, with emissions of nickel, chromium and arsenic
contributing 36 percent, 24 percent and 24 percent respectively, to
this cancer incidence. In addition, we note that approximately 1,100
people are estimated to have cancer risks greater than 10 in one
million, and approximately 26,000 people are estimated to have risks
greater than one in one million as a result of emissions from these two
facilities. When considering the risks associated with MACT-allowable
emissions, both facilities have allowable risks of 100 in one million,
driven by nickel, chromium VI, and arsenic at one facility (which would
have an allowable cancer risk of 70 in one million when using the lower
nickel URE value) and chromium VI and arsenic at the other facility
(which would have an allowable cancer risk of 100 in one million when
using the lower nickel URE value).
    The maximum modeled chronic non-cancer TOSHI value for the source
category based on actual emissions could be up to 90 with emissions of
manganese from process fugitives contributing greater than 90 percent
of those impacts. A TOSHI of 90 means that the modeled long-term
average air concentration of manganese at that location is about 4.5
[micro]g/m\3\, or 90 times above the RfC (i.e., 0.05 [micro]g/m\3\).
Approximately 28,000 people are exposed to TOSHI levels above 1 and
approximately 30 people are exposed to a TOSHI greater than 10. When
considering MACT-allowable emissions, which did not adjust the fugitive
emissions, the maximum chronic non-cancer TOSHI value could be up to
200.
    Our screening analysis for worst-case acute impacts indicates the
potential for two pollutants, nickel and arsenic, to exceed an HQ value
of 1, with a potential maximum HQ up to 10 for nickel and 9 for arsenic
based on acute REL values for each substance. There

are no AEGL, ERPG, or short-term occupational values for these
pollutants to use as comparison to acute REL values, as has been done
in other RTR actions. In addition, there are no reference values
available to assess any potential risks from acute exposure to
manganese. These acute result values were based on hourly emissions
estimates and a review of the facility boundaries to make sure the
estimated impacts were off facility property. Refer to Appendix 1 of
the Risk Assessment document in the docket for a detailed description
of how the hourly emissions were developed for this source category.
These results suggest there may be potential for acute impacts of
concern from the emissions of nickel and arsenic from the two
facilities in this category. In characterizing the potential for acute
noncancer impacts of concern, it is important to remember the upward
bias of these exposure estimates (e.g., worst-case meteorology
coinciding with a person located at the point of maximum concentration
during the hour) and to consider the results along with the
uncertainties related to the emissions estimates and the screening
methodology.
2. Multipathway Risk Screening and Results
    The PB-HAP emitted by facilities in this category include mercury,
POM (as benzo(a)pyrene toxicity equivalents, or TEQ), and lead. To
identify potential multipathway health risks from PB-HAP other than
lead, we first performed a screening analysis that compared emissions
of other PB-HAP emitted from the Ferroalloys Production source category
to emission threshold values. The two facilities in the source category
reported emissions of mercury and POM, and both of them had baseline
emission rates greater than the screening emission threshold values for
the pollutants indicating that there may be potential multipathway
impacts of concern due to emissions of these pollutants from these two
facilities.
    Since the two PB-HAP did not screen out during our initial
screening analysis, we refined our analysis somewhat with some
additional site-specific information to develop an ``intermediate
screen,'' which is a more realistic analysis but still considered a
screening analysis. (See Appendix 5 of the Risk Assessment document in
the docket for more information about this intermediate screen.) The
additional site-specific information included land use around the
facilities, the location of fishable lakes, and local wind direction
and speed. The result of this analysis was the development of site-
specific emission screening thresholds for POM and mercury. Based on
this intermediate screening analysis, neither facility screened out,
meaning that we cannot rule out the potential for multipathway impacts
of concern due to emissions of these pollutants from these two
facilities. We were unable to obtain the data necessary to conduct a
fully refined assessment of multipathway risks from these two
facilities.
    In evaluating the potential for multipathway effects from emissions
of lead, modeled maximum annual lead concentrations were compared to
the National Ambient Air Quality Standards (NAAQS) for lead (0.15
[micro]g/m\3\). Results of this analysis estimate that the NAAQS for
lead could be exceeded at one of the two facilities, largely due to
process fugitive emissions. This analysis estimates that the annual
lead concentrations could be as high as two times the NAAQS for lead,
and if the maximum 3-month rolling average concentrations were used,
the result could be even greater concentrations above the NAAQS.
However, this additional analysis was not conducted because, as shown
below (in section IV.C.2), the maximum annual lead concentration after
the proposed controls are applied is significantly below the NAAQS,
with a value of 0.02 [micro]g/m\3\.
3. Facilitywide Risk Assessment Results
    For both facilities in this source category, there are no other
significant HAP emissions sources present beyond those included in the
source category. All significant HAP sources have been included in the
source category risk analysis. Therefore, we conclude that the
facilitywide risk is essentially the same as the source category risk
and that no separate facilitywide analysis is necessary.

C. What are our proposed decisions based on risk acceptability and
ample margin of safety?

1. Risk Acceptability
    As noted in section III.C of this preamble, we weigh all health
risk factors in our risk acceptability determination, including the
MIR; the number of persons in various cancer and noncancer risk ranges;
cancer incidence; the maximum noncancer HI; the maximum acute noncancer
HQ; the extent of noncancer risks; the potential for adverse
environmental effects; distribution of cancer and noncancer risks in
the exposed population; and risk estimation uncertainty (54 FR 38044,
September 14, 1989).
    Based on the baseline inhalation risk assessment, we estimate that
the cancer risks to the individual most exposed could be up to 80 in
one million (50 in one million when using the lower nickel URE value)
due to actual emissions of arsenic, chromium and nickel from process
fugitives and up to 100 in one million due to MACT-allowable emissions,
mainly due to chromium, arsenic and nickel stack emissions. (There is
no change in the allowable cancer risk estimate when using the lower
nickel URE value.) We estimate that the incidence of cancer based on
actual emissions is 0.002 excess cancer cases per year, or 1 case every
500 years, and that about 26,000 people face a cancer risk greater than
one in one million due to HAP emissions from this source category. The
chronic noncancer TOSHI could be up to 90 due to actual emissions of
manganese from process fugitives and up to 200 due to MACT-allowable
emissions of manganese from process fugitives. We estimate that about
28,000 people face a TOSHI level greater than 1 and approximately 30
people face a TOSHI greater than 10 due to emissions from this source
category.
    With respect to potential acute non-cancer health risks, we
estimate that, based on our refined analysis, the worst-case HQ value
could exceed an HQ value of 1 for two pollutants, nickel and arsenic,
with a potential maximum HQ up to 10 for nickel and 9 for arsenic. This
indicates a potential acute concern relative to the baseline emissions
of these two pollutants based on the REL. In characterizing the
potential for acute noncancer impacts of concern, it is important to
remember the upward bias of these exposure estimates and to consider
the results along with the uncertainties related to the emissions
estimates and screening methodology. In the case of ferroalloys, the
acute emissions estimates were based on actual data from the ICR (i.e.,
there was not an acute emissions adjustment factor). Our assessment
also indicates the potential for multipathway impacts of concern based
on the intermediate screening assessment due to baseline emissions of
mercury and POM. Data were unavailable to conduct a fully refined
assessment of multipathway risks from these two facilities.
    The risk assessment for this source category was based on facility-
specific stack-test data and emissions estimates, giving us a generally
high degree of confidence in the results. We applied the two-step
analysis set out in the Benzene NESHAP to assess emissions from this
source category. Considering all of the above information, we are
proposing that the risks are

unacceptable, both for the actual emissions scenario and for the MACT-
allowable emissions scenario.
    The proposed determination that risks are unacceptable for this
source category is primarily based on the fact that the maximum chronic
noncancer HI values (90 based on actual emissions, 200 based on
allowable, both dominated by manganese emissions) are higher than 1 (an
HI exposure level of 1 is generally considered to be without
appreciable risk of adverse health effects). The fact that 28,000
people are estimated to have exposures greater than an HI of 1 (based
on actual emissions) also weighs in this proposed determination. The
fact that maximum individual cancer risks are above 1 in a million also
contributes to our determination of unacceptability, but to a lesser
extent. While the estimated maximum individual cancer risks would, by
themselves, not generally lead us to a determination that risks are
unacceptable, the fact that they occur along with the chronic noncancer
TOSHI greater than 1 (approximately 28,000 people are exposed to TOSHI
levels above 1 and approximately 30 people are exposed to a TOSHI
greater than 10) adds to our concern about these exposures, and further
supports our proposed determination that risks are unacceptable. The
total estimated cancer incidence (0.002 cases per year) is not very
high, and this fact did not weigh significantly in our proposed
determination of unacceptable risk. However, in the past EPA has
weighed an estimated cancer incidence of 0.002 cases per year heavily
in a determination of acceptable risk. EPA notes that there were no
non-cancer concerns in these previous instances. We further note that,
while our screening for potential acute and multi-pathway impacts of
concern from the 2 sources in the category did identify some potential
concerns for a few HAPs, these screening results did not weigh heavily
in our proposed determination that risks are unacceptable.
    Given that chronic noncancer risks associated with manganese
emissions are the primary determinant of unacceptable risks, we provide
here a brief discussion of the EPA's RfC associated with the inhalation
of manganese and our confidence in the principal studies supporting the
development of that RfC for context. The RfC is the level below which
there is not likely to be appreciable risk of deleterious effects;
however, the EPA cannot state at what exposure level there will be an
appreciable risk of deleterious effects. In the case of manganese, the
effect of concern was a decrease in visual reaction time in adults who
were occupationally exposed to manganese. The effects were seen at a
dose adjusted value of 0.05 mg/m\3\ and then to derive the RfC, the EPA
divided this value by 1000 to account for uncertainties related to
sensitive individuals (10x), use of the lowest exposure level at which
effects were observed in lieu of a level without effects (10x) and due
to database limitations (10x). We note that the concentration reflected
in the maximum TOSHI of 90 (0.0045 mg/m\3\) is approximately a factor
of 10 lower than the 0.05 mg/m\3\ dose adjusted effect level in an
adult male work force and used in the derivation of the RfC (0.00005
mg/m\3\). The EPA has ``medium confidence'' (as used and described in
the IRIS database) in the RfC value of 0.00005 mg/m\3\. The confidence
level reflects the overall level of uncertainty in the principle
studies, which were based on human occupational studies, and the
database.
    Overall confidence in the principal studies (Roels et al., 1987,
1992) is ``medium''. Neither of the principal studies identified a no
observed adverse effect level (NOAEL) for neurobehavioral effects, nor
did either study directly measure particle size or provide information
on the particle size distribution. The 1992 study by Roels et al. did
provide respirable and total dust measurements, but the 1987 study
measured only total dust.\35\ These limitations of the studies are
mitigated by the fact that the principal studies found similar
indications of neurobehavioral dysfunction, which was consistent with
the results of other human studies. In addition, the 1992 Roels et al.
study provides sufficient information to establish individual
integrated exposures; the 1987 Roels et al. study did not.
---------------------------------------------------------------------------

    \35\ ``Total and respirable dust concentrations were highly
correlated, with the Mn content of the respirable fraction
representing on average 25% of the manganese content in the total
dust. The RfC is based on the respirable fraction.
---------------------------------------------------------------------------

    Confidence in the database on manganese health effects is
``medium''. The duration of exposure was relatively limited and the
workers were relatively young in all of the principal and supporting
studies. These temporal limitations raise concerns that longer
durations of exposure and/or interactions with aging might result in
the detection of effects at lower concentrations, as suggested by
results from other studies. In addition, the studies, with the
exception of the 1992 Roels et al. study in which manganese exposure
was limited to manganese oxide, did not specify the species of
manganese to which workers were exposed. It is not clear whether
certain compounds or oxidation states of manganese are more toxic than
others. Although the primary neurotoxicological effects of exposure to
airborne manganese have been qualitatively well characterized by the
general consistency of effects across studies, the exposure-effect
relationship remains to be well quantified, and a no-effect level for
neurotoxicity has not been identified in any of these studies thus far.
Finally, the effects of manganese on development and reproduction have
not been studied adequately. See the full IRIS summary for manganese
for more information (IRIS, Manganese, available at: www.epa.gov/iris/subst/0373.htm).
    As noted in the 1989 Benzene NESHAP, the Agency weighs multiple
risk factors in making a determination of acceptable or unacceptable
risk, and notes that acceptability cannot be reduced to any single
factor. In applying the balancing factors to this action, EPA
considered a wide range of data including the MIR; the number of
persons in various cancer and noncancer risk ranges; cancer incidence;
the maximum noncancer HI; the maximum acute noncancer HQ; the extent of
noncancer risks; the potential for adverse environmental effects;
distribution of cancer and noncancer risks in the exposed population;
and risk estimation uncertainty (54 FR 38044, September 14, 1989).
    In summary, the MIR was 80 in a million based on actual emissions
and 100 in one million based on allowable emissions; the total
estimated cancer incidence was 0.002 cases per year (or 1 case in every
500 years); and approximately 30 people could be exposed at a TOSHI
greater than 10 while approximately 28,000 could be exposed at a TOSHI
greater than 1. Since the RfC is 1000 fold below the lowest level at
which neurological effects were seen, the maximum TOSHI of 90 (or 200
for allowable risks) is still below the effect level used to derive the
RfC and there is uncertainty as to exactly what level of exposure above
the RfC will lead to appreciable risk of adverse effects. The
population from which the effect level was derived was an adult male
worker population, and that this population does not necessarily
represent the general population. We note that the concentration
reflected in the maximum TOSHI of 90 (0.0045 mg/m\3\) is approximately
a factor of 10 lower than the 0.05 mg/m\3\ dose adjusted effect level
in an adult male work force which was used in the derivation of the
RfC.

    Based on our assessment of the information, we are proposing that
the risks are unacceptable. We solicit comment on all aspects of this
proposed determination. Specifically, we solicit any information (and
supporting data) that would further inform our proposed decision.
    We also solicit comment on whether an alternative balancing of all
the same factors including the weights afforded to individual factors
discussed above and their associated uncertainties could lead to a
different decision regarding risks. EPA also solicits any information
(and supporting data) that would further inform this alternative
approach.
    Under the two-step Benzene NESHAP approach, we are required under
CAA section 112(f)(2)(A) to make a determination as to what controls
are needed to achieve an ample margin of safety for the source category
after we make a determination on risk acceptability. The discussion of
the controls needed to achieve an ample margin of safety in section
IV.C.3 addresses both what would be needed if we find risks are
unacceptable as well as what would be needed if we find that risks are
acceptable.
2. Proposed Controls To Address Risks
    We conducted an assessment to estimate the risks from the two
facilities in the source category based on a post-control scenario
reflecting the proposed requirements described above to address
unregulated HAP (section IV.A) and the proposed controls described
below. Details are provided in the Draft Risk Assessment report which
is available in the docket for this action.
a. Allowable Stack Emissions
    In order to ensure that the risks associated with this source
category are acceptable, we evaluated the potential to reduce MACT-
allowable stack emissions, which had driven the cancer MIR based on
allowable emissions to 100 in a million, primarily due to allowable
stack emissions of arsenic, nickel and chromium, and contributed
significantly to the chronic noncancer TOSHI (based on allowable
emissions) of 200, primarily due to allowable stack emissions of
manganese. Our analysis determined that we could lower the existing
particulate matter emission limits by approximately 50 percent for
furnace stack emissions, by 80 percent for crushing and screening stack
emissions and by 98 percent for the metal oxygen refining process.
After the implementation of these tighter PM stack limits, the
estimated cancer MIR for the source category based on allowable
emissions would become 80 in one million and the TOSHI would be about
90.
    For the reasons described above, under the authority of CAA section
112(f)(2), we propose to set particulate matter emission limits for the
stacks at the following levels: 9.3 mg/dscm corrected to 2 percent
CO2 for new or reconstructed electric arc furnaces, 24 mg/
dscm corrected to 2 percent CO2 for existing electric arc
furnaces, 1.5 mg/dscm corrected to 2 percent CO2 for any
new, reconstructed or existing MOR process, and 13 mg/dscm for any new,
reconstructed or existing crushing and screening equipment. We believe
sources can achieve these limits with existing controls. These new
emissions limits will reduce potential risks due to allowable emissions
from the stacks and prevent backsliding. We propose that compliance for
existing sources will be demonstrated by annual stack testing and
installation and operation of bag leak detection systems for both new
and existing sources.
b. Process Fugitive Emissions Sources
    Process fugitive sources are partially controlled by the existing
MACT via a shop building opacity standard; however, that standard was
only intended to address tapping process fugitives generated under
``normal'' tapping process operating conditions. Casting and crushing
and screening process fugitives in the furnace building were not
included. Under the authority of section 112(d)(2) of the Act, which
allows the use of measures to enclose systems or processes to eliminate
emissions and measures to collect, capture or treat such pollutants
when released from a process, stack, storage, or fugitive emissions
point, we evaluated several options to achieve improved emissions
capture. We developed several control scenarios to assess options to
improve/add local ventilation and associated control (e.g., improve
tapping capture, install capture and control on casting operations),
but we concluded that these were all ineffective in significantly
reducing emissions and risks. As part of the technology review process,
we identified a furnace building ventilation system at a non-manganese
producer of ferroalloys. We evaluated an option based on this furnace
building ventilation system, which involves enclosing the furnace
building(s) and evacuating the emissions to a control device(s). Based
on our assessment we conclude that this option would reduce process
fugitive emissions by about 98 percent and reduce the maximum noncancer
TOSHI to about 2. A TOSHI of 2 means that the modeled long-term
concentration of manganese at that location would be about 0.1
[micro]g/m\3\ (i.e., about 2 times higher than the RfC). These controls
would also significantly reduce the emissions of arsenic, chromium and
nickel and therefore significantly reduce the cancer risks. These
reductions would result in acceptable risk levels. Therefore, under the
authority of CAA section 112(f), we are proposing such an approach,
whereby the furnace buildings must be enclosed and process fugitive
emissions would need to be collected under negative pressure at the
ridge vents of the shop building and ducted to a control device.
    We are proposing that the PM emissions limit (as a surrogate for
particulate metal HAP) at the control device would be the same as it is
for the furnace stacks (24 mg/dscm). This would allow sources the
option to duct some or all process fugitive emissions to an existing
furnace control device if it has excess capacity. If the existing
control device at the facility does not have sufficient excess capacity
to handle the captured emissions, the facility would have to install
additional controls capable of complying with the proposed emission
limit.
    The source would also have to monitor building opacity, prepare and
operate according to a process fugitives ventilation plan and conduct
annual performance testing of the building ventilation control device
to demonstrate compliance with the proposed standards. Baghouses would
be required to be equipped with BLDS. We also propose that facilities
would need to continue the practices to minimize outdoor fugitive dust
emissions that are required by the 1999 MACT rule which includes
implementing measures specified in their outdoor fugitive dust control
plans as approved by the Administrator.
    However, recognizing that there may be other control measures that
could achieve equivalent emissions reductions that we have not yet
identified, and to provide some flexibility for facilities to determine
the best approach to reduce their emissions, we are also proposing an
equivalent alternative compliance approach. Under this alternative
approach, we propose that facilities would still need to continue the
work practices to minimize outdoor fugitive dust emissions that are
required by the 1999 MACT rule which includes implementing measures
specified in their outdoor fugitive dust control plans as approved by
the Administrator. However, in lieu of building the full enclosure and
capture and evacuation system described above to control

process fugitive emissions, we are proposing that facilities can design
and implement an equivalent alternative approach (e.g., local capture,
controls, and work practices) to address the risks associated with
those process fugitive emissions. Compliance would be demonstrated by
ensuring facilities apply the equivalent alternative approach to
control process fugitive emissions, continue the work practices to
minimize outdoor fugitive dust emissions, and also conduct fenceline
monitoring to demonstrate that the ambient concentration of manganese
at their facility boundary is no more than 0.1 [mu]g/m\3\ on a 60-day
rolling average, as described below.
    Specifically, we propose to require that sources seeking to use
this alternative prepare and submit for the Administrator's approval a
written plan describing and explaining the equivalent alternative
approach that they propose to apply and a proposed compliance
monitoring network that must consist of at least two monitors located
at or near the facility boundary, and in locations expected to have the
highest concentrations of manganese, and the procedures for sampling,
sample handling and custody, sample analysis, quality assurance, and
recordkeeping procedures. The purpose of the ambient air monitoring
network would be to ensure that manganese concentrations in air near
the facility boundaries remain at or below 0.1 [mu]g/m\3\ based on 10-
sample rolling averages, with samples being collected every 6 days
(i.e., 60-day rolling averages). The monitoring plan must include a
minimum of two monitoring sites that are placed in locations that are
most likely to capture measurements of the maximum concentrations at or
near the facility boundaries. For example, at least one monitor must be
placed in the predominant downwind direction from main emissions
sources based on historical weather patterns in the area. This standard
for manganese emissions would be a surrogate for all particulate HAP
metals (including arsenic, nickel and chromium) since they are emitted
by the same processes and controlled with the same devices and
measures. We propose to set this alternative limit using manganese as a
surrogate for metal HAP because manganese is the primary HAP metal
emitted from this source category. We considered the feasibility of
using PM as a surrogate, but developing a reliable relationship between
fenceline manganese concentration and filterable PM concentration is
almost impossible. We request comment on the use of manganese as a
surrogate for HAP metals in the alternative approach.
    This alternative regulatory requirement would provide flexibility
to facilities in determining the within-facility emission sources that
should be captured and vented to a control device that are most
effective for reducing process fugitive emissions at their facilities.
However, any facility considering this alternative approach would need
to demonstrate that they can be expected to achieve the fenceline
limitation with the proposed alternative approach and obtain approval
from the Administrator. This is especially important for facilities
with a history of elevated ambient manganese concentrations based on
monitoring by state regulatory agencies or the EPA, or any facility
that has been confirmed as the main contributor to elevated monitored
manganese concentrations in a particular area. Nevertheless, we are
seeking comments on this proposed alternative requirement, including
the controls and practices that can achieve the equivalent level of
reductions, the averaging time for monitoring, and whether two monitors
would be sufficient or if more monitors may be warranted.
    We propose to set the fenceline concentration level at 0.1 [mu]g/
m\3\ to reflect the equivalent level of emissions control that we
estimate will be achieved with the requirement to enclose the furnace
building(s) and evacuate the emissions to a control device(s). As
described in section IV.D.2, the maximum modeled chronic noncancer
inhalation TOSHI value is 2 after full enclosure and evacuation of
emissions based on the post-control modeling analysis. This means that
the modeled concentration at the maximum impact location after these
controls are in place would be 0.1 [mu]g/m\3\, which is 2 times higher
than the value of the RfC for manganese. Therefore, achieving and
maintaining an air manganese level of 0.1 [mu]g/m\3\ at the facility
boundary is proposed as the equivalent alternative standard to minimize
emissions of HAP metals. Nevertheless, we request comment on other
concentration values that might be appropriate to serve as the
concentration level for fenceline monitoring under this alternative. We
also request comment on whether a different averaging period should be
required.
    As part of this alternative, we are also proposing a provision that
would allow for reduced monitoring if the facility demonstrates ambient
manganese concentrations less than 50 percent of the ambient manganese
concentration limit for 3 consecutive years at each monitor. We propose
that a revised monitoring plan may be submitted (for review and
possible approval by the Administrator) to reduce the sampling and
analysis frequency if all of the 10-sample rolling average
concentrations at each monitor are less than 50 percent of the limit of
0.1 [mu]g/m\3\ over a 3-year period.
    All of these proposed controls are described further under the
technology review (in section IV.D.2.) of this preamble.
c. Results of the Post-Control Risk Assessment
    The results of the post-control chronic inhalation cancer risk
assessment indicate that, based on actual emissions, the maximum
individual lifetime cancer risk posed by these two facilities, after
the implementation of the proposed controls, could be up to 5 in one
million, reduced from 80 in one million (i.e., pre-controls), with an
estimated reduction in cancer incidence to 0.0004 excess cancer cases
per year, reduced from 0.002 excess cancer cases per year. In addition,
the number of people estimated to have a cancer risk greater than or
equal to one in one million would be reduced from 26,000 to 1,300.
    The results of the post-control assessment also indicate that,
based on actual emissions, the maximum chronic noncancer inhalation
TOSHI value would be reduced to 2, from the baseline estimate of 90.
The number of people estimated to have a TOSHI greater than 1 would be
reduced from 28,000 to less than 10.
    We also estimate that after the implementation of controls, the
maximum worst-case acute refined HQ value would be reduced from a
potential high of 10 to 0.3 (based on the REL value for nickel
compounds) eliminating any potential for acute impacts of concern.
    Considering post-control emissions of multipathway HAP, mercury
emissions would be reduced approximately 88 percent, while POM
emissions would be reduced approximately 66 percent from the baseline
emission rates. Based on our intermediate screening approach for
multipathway risks, emissions of mercury ``screen out,'' or are reduced
below the screening threshold for both facilities, indicating no
potential for multipathway impacts of concern due to mercury. However,
emissions of POM (as benzo(a)pyrene TEQ) remain above the intermediate
screening thresholds for both facilities (one by a factor of 20 and one
by a factor of 2), indicating that we cannot rule out the potential for
multipathway impacts of concern due to emissions of POM from these
facilities.

As mentioned above, the highest lead concentration after controls, 0.02
[mu]g/m\3\, is well below the NAAQS, indicating a low potential for
multipathway impacts of concern due to lead.
3. Ample Margin of Safety Analysis and Proposed Controls
    Under the ample margin of safety analysis, we evaluate 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 due to emissions of HAP identified in our risk
assessment.
    We estimate that the actions proposed under CAA section 112(f)(2),
as described above to address unacceptable risks, will reduce the MIR
associated with arsenic, nickel and chromium from 80 in one million (50
in one million using the lower end of the nickel URE range) to 5 in one
million for actual emissions. The cancer incidence will be reduced from
0.002 to 0.0004, and the number of people estimated to have cancer
risks greater than one in one million will be reduced, from 26,000
people to 1,300 people. The chronic noncancer inhalation TOSHI will be
reduced from 90 to 2, and the number of people exposed to a TOSHI level
greater than 1 will be reduced from 28,000 people to less than 10
people. In addition, the maximum acute HQ value will be reduced from
potentially up to 10 to less than 1, and the potential multipathway
impacts will be reduced.
    Based on all of the above information, we conclude that the risks
after implementation of the proposed controls are acceptable. Based on
our research and analysis, we did not identify any cost-effective
controls beyond those proposed above that would achieve further
reduction in risk. Therefore we conclude that the controls to achieve
acceptable risks (described above) will also achieve an ample margin of
safety. Although we conclude that the implementation of the proposed
requirements described above will provide public health protection with
an ample margin of safety we acknowledge that there may be other
control technologies that may also achieve these goals.
    We are soliciting comments and information regarding additional
dust and process fugitive control measures and work practices that may
be more feasible to implement and effective in further reducing process
and dust fugitive emissions of metal HAP, or additional monitoring that
may be warranted to ensure adequate control of fugitive emissions. We
also request comments on the cost effectiveness of achieving the
proposed process fugitive control measures and any additional options
that may be more cost effective.
    We also note that we are soliciting comment on our proposed risk
finding. If we conclude, after evaluating data and information received
in comments on this proposed rule, that the risks posed by this source
category are acceptable, then based on the data and information we
currently have, we would likely adopt the same controls described in
section IV.C.2 as being necessary to provide an ample margin of safety.
As noted above in this section and in section IV.C.2.c., the proposed
controls provide significant risk reductions beyond the current rule.
Furthermore, as discussed more extensively in section IV.D.2 of this
notice, below, we conclude that these controls are cost effective and
technically feasible. We solicit comment on the appropriateness of
these controls in the event we find, based on data and information
received in comment, that the current rule provides an acceptable risk.

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

    Based on our technology review, we determined that there have been
advances in emissions control measures since the Ferroalloys Production
NESHAP was originally promulgated in 1999. Since promulgation,
facilities have steadily improved the performance of their control
devices through upgrades or replacements. They have also developed
improved capture techniques for some process fugitives (e.g., casting
and tapping emissions). Additional details regarding these analyses can
be found in the following technical document for this action which is
available in the docket: Draft Technology Review for the Ferroalloys
Production Source Category.
1. Metal HAP Emissions From Stacks
    We propose to continue to use particulate matter as a surrogate for
metal HAP other than mercury. For a discussion regarding the
appropriateness of particulate matter as a surrogate for non-mercury
metal HAP, please see the memo ``Surrogate for Metal HAP Emissions for
the Ferroalloys Source Category'' in the docket for this proposed rule.
Based on the results from the ICR test program, we determined that all
of the sources of stack emissions are emitting at significantly lower
levels than their maximum permitted levels. For this reason, under the
authority of CAA section 112(d)(6), we are proposing revised emission
limits for new and existing sources. We are also proposing that any
uncontrolled furnace vent stacks would be subject to the same
concentration limits.
    We calculated the proposed emission limits based on a UPL analysis,
resulting in a proposed existing source furnace stack emissions limit
of 24 mg/dscm and proposed new source furnace stack emissions limit of
9.3 mg/dscm. We also calculated a proposed stack emission limit of 13
mg/dscm for crushing and screening equipment that would apply to both
new and existing sources.
    The metal oxygen refining operation is a unique process, and so we
only have a single ICR test data point. Therefore, we calculated a
proposed emissions limit for this source using the 99 percent UPL from
the test data, resulting in a proposed limit of 3.9 mg/dscm that would
apply to new and existing metal oxygen refining operation sources. We
request comment on whether we should instead set the MOR limit to be
the same as the proposed furnace stack limit for existing sources. This
change would allow a facility to use any excess capacity in the MOR
control device to treat furnace emissions, if needed. Such a limit is
still more stringent than the current limit included in subpart XXX for
the MOR (approximately 69 mg/dscm).
    Based on our analyses, we expect that no additional controls would
be required for the facilities to comply with these proposed limits. To
demonstrate compliance, we propose that sources would be required to
conduct periodic performance testing, and develop and operate according
to a baghouse operating plan or continuously monitor scrubber operating
parameters. Furnace baghouses would be required to be equipped with bag
leak detection systems (BLDS).
2. Metal HAP Emissions From Process Fugitives
    As described above, we evaluated several options to improve and
increase the capture and control of process fugitive sources. The two
main options involve either local ventilation or building ventilation.
Local ventilation (e.g., hoods or ductwork located in close proximity
to an emissions source such as tapping or casting) is common in this
industry, but performance varies due to design of the capture system,
maintenance practices and control device capacity. Industry
representatives have expressed concern that extensive retrofitting of
local ventilation is complicated at existing facilities because of the
need for

material movement using large overhead cranes and ladles. We identified
a furnace building ventilation system at a ferrosilicon producer, using
a similar production process. This ``system'' is basically an enclosure
of the furnace building with evacuation of emission to a control
device.
    We evaluated an option to enclose the furnace building(s) and
evacuate the emissions to a control device(s) similar to the system
used at the ferrosilicon producing facility described above. Based on
that evaluation, we believe that it is feasible to install enclosures
and have the fugitive emissions at the ridge vents of the shop building
collected under negative pressure and ducted to a control device, and
have a PM emissions limit at the control device the same as it is for
the furnace stacks (i.e., 24 mg/dscm). This would allow sources the
option to duct some or all process fugitive emissions to an existing
furnace control device if it has excess capacity. If it does not have
excess capacity, the facility would have to install additional
controls. Under this option, the source would also have to monitor
building opacity; prepare and operate according to a process fugitives
emissions ventilation plan, which would include requirements to
demonstrate that the building is being operated at a negative pressure
of at least 0.007 inches of water; and conduct periodic performance
testing of the building ventilation control device to demonstrate
compliance with the proposed standards. Baghouses would be required to
be equipped with BLDS.
    We estimate the total capital costs of installing the required
ductwork, fans, and baghouses under this option to be $9.4 million and
the total annualized costs to be $2.3 million for the two plants. We
estimate that particulate metal HAP emissions would be reduced by 81
tons, resulting in a cost per ton of HAP removed at $28,000 per ton
($14 per pound). We also estimate that this option would achieve PM
emission reductions of 630 tons, resulting in a cost per ton of PM
removed at $3,600 per ton and achieve PM2.5 emission
reductions of 257 tons, resulting in a cost per ton of PM2.5
removed of $8800 per ton. In light of the technical feasibility and
cost effectiveness of this approach, we are proposing this option under
the authority of section 112(d)(6). These proposed requirements are
exactly the same as those proposed under Section 112(f) which are
described in section IV.C.2 of this preamble.
    As described above in section IV.C.2.b, we are also proposing an
equivalent alternative compliance approach. Facilities can design and
implement an equivalent alternative approach (e.g., local capture,
controls, and work practices) to achieve equivalent reductions of their
process fugitive emissions. Compliance would be demonstrated by
ensuring facilities apply the equivalent alternative approach to
control process fugitive emissions, continue the work practices to
minimize outdoor fugitive dust emissions, and also conduct fenceline
monitoring to demonstrate that the ambient concentration of manganese
at their facility boundary is no more than 0.1 [mu]g/m\3\ on a 60-day
rolling average.
3. Hydrochloric Acid, Formaldehyde, Mercury and PAH Emissions From
Furnace Stacks
    The controls for HCl, formaldehyde, mercury and PAHs were described
in Section IV.A., and no additional controls have been identified.
4. Outdoor Fugitive Dust Emissions
    The existing rule has a requirement for an outdoor fugitive dust
control plan. We are unable to quantify HAP emissions from outdoor
fugitive dust sources and did not identify any additional procedures or
controls that could be expected to have a significant impact on these
emissions. Therefore, we are not proposing to change the existing
requirements.

E. What other actions are we proposing?

1. Startup, Shutdown, Malfunction
    The United States Court of Appeals for the District of Columbia
Circuit vacated portions of two provisions in the EPA's CAA section 112
regulations governing the emissions of HAP during periods of SSM.
Sierra Club v. EPA, 551 F.3d 1019 (DC Cir. 2008), cert. denied, 130 S.
Ct. 1735 (U.S. 2010). Specifically, the Court vacated the SSM exemption
contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), that are part of
a regulation, commonly referred to as the ``General Provisions Rule,''
that the EPA promulgated under CAA section 112. When incorporated into
CAA section 112(d) regulations for specific source categories, these
two provisions exempt sources from the requirement to comply with the
otherwise applicable CAA section 112(d) emissions standard during
periods of SSM.
    We are proposing the elimination of the SSM exemption in this rule.
Consistent with Sierra Club v. EPA, the EPA is proposing standards in
this rule that apply at all times. We are also proposing several
revisions to Table 1 to subpart XXX of part 63 (the General Provisions
Applicability table). For example, we are proposing to eliminate the
incorporation of the General Provisions' requirement that the source
develop an SSM plan. We also are proposing to eliminate or revise
certain recordkeeping and reporting that related to the SSM exemption.
The EPA has attempted to ensure that we have not included in the
proposed regulatory language any provisions that are inappropriate,
unnecessary, or redundant in the absence of the SSM exemption. We are
specifically seeking comment on whether there are any such provisions
that we have inadvertently incorporated or overlooked.
    In proposing the standards in this rule, the EPA has taken into
account startup and shutdown periods and, for the reasons explained
below, has not proposed different standards for those periods.
    Information on periods of startup and shutdown received from the
industry in the ICR indicate that emissions during these periods do not
increase. Control devices such as baghouses for metal HAP particulate
control and activated carbon controls for mercury are started up before
the process units, and are operational during the shutdown phase of a
process. Therefore, no increase in emissions is expected during these
periods. Building ventilation systems for process fugitive emissions
will be in place at all times. Therefore, separate standards for
periods of startup and shutdown are not being proposed.
    Periods of startup, normal operations, and shutdown are all
predictable and routine aspects of a source's operations. However, by
contrast, malfunction is defined as a ``sudden, infrequent, and not
reasonably preventable failure of air pollution control and monitoring
equipment, process equipment or a process to operate in a normal or
usual manner * * *'' (40 CFR 63.2). The EPA has determined that CAA
section 112 does not require that emissions that occur during periods
of malfunction be factored into development of CAA section 112
standards. Under CAA section 112, emissions standards for new sources
must be no less stringent than the level ``achieved'' by the best
controlled similar source, and emission standards for existing sources
generally must be no less stringent than the average emissions
limitation ``achieved'' by the best performing 12 percent (or 5 sources
in cases where there are fewer than 30 sources in the source category)
of sources in the category. There is nothing in CAA section 112 that
directs the Agency to consider malfunctions in determining the level
``achieved'' by the best performing or best controlled sources when
setting emissions

standards. Moreover, while the EPA accounts for variability in setting
emissions standards consistent with the CAA section 112 case law,
nothing in that case law requires the Agency to consider malfunctions
as part of that analysis. Section 112 of the CAA uses the concept of
``best controlled'' and ``best performing'' unit in defining the level
of stringency that CAA section 112 performance standards must meet.
Applying the concept of ``best controlled'' or ``best performing'' to a
unit that is malfunctioning presents significant difficulties, as
malfunctions are sudden and unexpected events.
    Further, accounting for malfunctions 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 such, the
performance of units that are malfunctioning is not ``reasonably''
foreseeable. See, e.g., Sierra Club v. EPA, 167 F. 3d 658, 662 (DC 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
(DC 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, the goal of a best controlled or
best performing source is to operate in such a way as to avoid
malfunctions of the source and accounting for malfunctions could lead
to standards that are significantly less stringent than levels that are
achieved by a well-performing non-malfunctioning source. The EPA's
approach to malfunctions is consistent with CAA 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'' 40 CFR 63.2 (definition of
malfunction).
    Finally, the EPA recognizes that even equipment that is properly
designed and maintained can sometimes fail and that such failure can
sometimes cause an exceedance of the relevant emissions standard. (See,
e.g., State Implementation Plans: Policy Regarding Excessive Emissions
During Malfunctions, Startup, and Shutdown (Sept. 20, 1999); Policy on
Excess Emissions During Startup, Shutdown, Maintenance, and
Malfunctions (Feb. 15, 1983)). The EPA is therefore proposing to add to
the final rule an affirmative defense to civil penalties for
exceedances of emissions limits that are caused by malfunctions. See 40
CFR 63.1622 (defining ``affirmative defense'' to mean, in the context
of an enforcement proceeding, a response or defense put forward by a
defendant, regarding which the defendant has the burden of proof, and
the merits of which are independently and objectively evaluated in a
judicial or administrative proceeding). We also are proposing other
regulatory provisions to specify the elements that are necessary to
establish this affirmative defense; the source must prove by a
preponderance of the evidence that it has met all of the elements set
forth in 40 CFR 63.1627 (40 CFR 22.24). The criteria ensure that the
affirmative defense is available only where the event that causes an
exceedance of the emissions limit meets the narrow definition of
malfunction in 40 CFR 63.2 (sudden, infrequent, not reasonable
preventable and not caused by poor maintenance and or careless
operation). For example, to successfully assert the affirmative
defense, the source must prove by a preponderance of the evidence that
excess emissions ``[w]ere caused by a sudden, infrequent, and
unavoidable failure of air pollution control and monitoring equipment,
process equipment, or a process to operate in a normal or usual manner
* * *.'' The criteria also are designed to ensure that steps are taken
to correct the malfunction, to minimize emissions in accordance with 40
CFR 63.1623(g) and to prevent future malfunctions. For example, the
source must prove by a preponderance of the evidence that ``[r]epairs
were made as expeditiously as possible when the applicable emissions
limitations were being exceeded * * *'' and that ``[a]ll possible steps
were taken to minimize the impact of the excess emissions on ambient
air quality, the environment and human health * * *.'' In any judicial
or administrative proceeding, the Administrator may challenge the
assertion of the affirmative defense and, if the respondent has not met
its burden of proving all of the requirements in the affirmative
defense, appropriate penalties may be assessed in accordance with CAA
section 113 (see also 40 CFR 22.27).
    The EPA included an affirmative defense in the proposed rule in an
attempt to balance a tension, inherent in many types of air regulation,
to ensure adequate compliance while simultaneously recognizing that
despite the most diligent of efforts, emission limits may be exceeded
under circumstances beyond the control of the source. The EPA must
establish emission standards that ``limit the quantity, rate, or
concentration of emissions of air pollutants on a continuous basis.''
42 U.S.C. 7602(k) (defining ``emission limitation and emission
standard''). See generally Sierra Club v. EPA, 551 F.3d 1019, 1021 (DC
Cir. 2008). Thus, the EPA is required to ensure that section 112
emissions limitations are continuous. The affirmative defense for
malfunction events meets this requirement by ensuring that even where
there is a malfunction, the emission limitation is still enforceable
through injunctive relief. While ``continuous'' limitations, on the one
hand, are required, there is also caselaw indicating that in many
situations it is appropriate for the EPA to account for the practical
realities of technology. For example, in Essex Chemical v. Ruckelshaus,
486 F.2d 427, 433 (DC Cir. 1973), the DC Circuit acknowledged that in
setting standards under CAA section 111 ``variant provisions'' such as
provisions allowing for upsets during startup, shutdown and equipment
malfunction ``appear necessary to preserve the reasonableness of the
standards as a whole and that the record does not support the `never to
be exceeded' standard currently in force.'' See also, Portland Cement
Association v. Ruckelshaus, 486 F.2d 375 (DC Cir. 1973). Though
intervening caselaw such as Sierra Club v. EPA and the CAA 1977
amendments undermine the relevance of these cases today, they support
the EPA's view that a system that incorporates some level of
flexibility is reasonable. The affirmative defense simply provides for
a defense to civil

penalties for excess emissions that are proven to be beyond the control
of the source. By incorporating an affirmative defense, the EPA has
formalized its approach to upset events. In a Clean Water Act setting,
the Ninth Circuit required this type of formalized approach when
regulating ``upsets beyond the control of the permit holder.'' Marathon
Oil Co. v. EPA, 564 F.2d 1253, 1272-73 (9th Cir. 1977). But see,
Weyerhaeuser Co. v. Costle, 590 F.2d 1011, 1057-58 (DC Cir. 1978)
(holding that an informal approach is adequate). The affirmative
defense provisions give the EPA the flexibility to both ensure that its
emission limitations are ``continuous'' as required by 42 U.S.C.
7602(k), and account for unplanned upsets and thus support the
reasonableness of the standard as a whole.
    Specifically, we are proposing the following changes to the rule.
     Added general duty requirements in 40 CFR 63.1623(g) to
replace General Provision requirements that reference vacated SSM
provisions.
     Added replacement language that eliminates the reference
to SSM exemptions applicable to performance tests in 40 CFR
63.1625(a)(5).
     Added paragraphs in 40 CFR 63.1629(d) requiring the
reporting of malfunctions as part of the affirmative defense
provisions.
     Added paragraphs in 40 CFR 63.1629(b) requiring the
keeping of certain records during malfunctions as part of the
affirmative defense provisions.
     Developed Table 1 to subpart XXX of part 63 to reflect
changes in the applicability of the General Provisions to this subpart
resulting from a court vacatur of certain SSM requirements in the
General Provisions.
2. Electronic Reporting
    The EPA and other authorities such as state, local and tribal
agencies must have performance test data to conduct effective reviews
of CAA sections 112 and 129 standards, as well as for many other
purposes including compliance determinations, emission factor
development, and annual emission rate determinations. We believe that
improvements in the process of submitting, reviewing and storing test
data would result in increases in efficiency and cost savings to the
regulated community; state, local and tribal agencies; the public and
ourselves. These improvements are possible because stack testing firms
are increasingly collecting performance test data in electronic format,
making it possible to move to an electronic data submittal system that
would increase the ease and efficiency of data submittal and improve
data accessibility.
    Through this proposal, the EPA is proposing a step to increase the
ease and efficiency of data submittal and improve data accessibility.
Specifically, the EPA is proposing that owners and operators of
Ferroalloys Production facilities submit electronic copies of required
performance test reports to the EPA's WebFIRE database. The WebFIRE
database was constructed to store performance test data for use in
developing emission factors. A description of the WebFIRE database is
available at http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main.
    As proposed above, data entry would be through an electronic
emissions test report structure called the Electronic Reporting Tool
(ERT). The ERT would be able to transmit the electronic report through
the EPA's Central Data Exchange network for storage in the WebFIRE
database, making submittal of data very straightforward and easy. A
description of the ERT can be found at http://www.epa.gov/ttn/chief/ert/index.html.
    The proposal to submit performance test data electronically to the
EPA would apply only to those performance tests conducted using test
methods that will be supported by the ERT. The ERT contains a specific
electronic data entry form for most of the commonly used EPA reference
methods. A listing of the pollutants and test methods supported by the
ERT is available at http://www.epa.gov/ttn/chief/ert/index.html. We
believe that industry would benefit from this proposed approach to
electronic data submittal. Having these data, the EPA would be able to
develop improved emission factors, make fewer information requests, and
promulgate better regulations.
    One major advantage of the proposed submittal of performance test
data through the ERT is a standardized method to compile and store much
of the documentation required to be reported by this rule. Another
advantage is that the ERT clearly states what testing information would
be required. Another important proposed benefit of submitting these
data to the EPA at the time the source test is conducted is that it
should substantially reduce the effort involved in data collection
activities in the future. When the EPA has performance test data in
hand, there will likely be fewer or less substantial data collection
requests in conjunction with prospective required residual risk
assessments or technology reviews. This would result in a reduced
burden on both affected facilities (in terms of reduced manpower to
respond to data collection requests) and the EPA (in terms of preparing
and distributing data collection requests and assessing the results).
    State, local, and tribal agencies could also benefit from more
streamlined and accurate review of electronic data submitted to them.
The ERT would allow for an electronic review process rather than a
manual data assessment making review and evaluation of the source
provided data and calculations easier and more efficient. Finally,
another benefit of the proposed data submittal to WebFIRE
electronically is that these data would greatly improve the overall
quality of existing and new emissions factors by supplementing the pool
of emissions test data for establishing emissions factors and by
ensuring that the factors are more representative of current industry
operational procedures. A common complaint heard from industry and
regulators is that emission factors are outdated or not representative
of a particular source category. With timely receipt and incorporation
of data from most performance tests, the EPA would be able to ensure
that emission factors, when updated, represent the most current range
of operational practices. In summary, in addition to supporting
regulation development, control strategy development, and other air
pollution control activities, having an electronic database populated
with performance test data would save industry, state, local, tribal
agencies, and the EPA significant time, money, and effort while also
improving the quality of emission inventories and, as a result, air
quality regulations.
3. Emissions Averaging
    We are proposing to add an emissions averaging option for electric
arc furnace stack emissions (PM, mercury, PAH, HCl or formaldehyde). If
you have more than one existing emission source (e.g., electric arc
furnace) located at one or more contiguous properties, which are under
common control of the same person (or persons under common control),
you may demonstrate compliance by emission averaging among the existing
emission sources, if your averaged emissions for such emission sources
are equal to or less than the applicable emission limit.
    We are also proposing to allow averaging between existing process
fugitive control devices for PM stack emissions as a second averaging
group. However, we believe it may be appropriate to combine these
process fugitive stack emissions into the furnace stack averaging group
for PM emissions

for two reasons. First, both types of emissions are likely to be
controlled with similar, if not common control devices, e.g., large
fabric filters. Second, we are proposing to apply an identical PM
emission limit for both of these emission sources, which would simplify
averaging of PM emissions. We request comment on this option.
    We are also proposing to allow averaging between existing crushing
and screening equipment for PM stack emissions. We believe this is a
distinct averaging group compared to the furnace and process fugitives
groups. The airflow and associated control devices are typically much
smaller and they are subject to a more stringent emission limit than
the other PM sources. However, we request comment on the potential for
more broadly defined averaging options for this group.
    As part of the EPA's general policy of encouraging the use of
flexible compliance approaches where they can be properly monitored and
enforced, we are including emissions averaging for existing sources in
this proposed rule. Emissions averaging can provide sources the
flexibility to comply in the least costly manner while still
maintaining regulation that is workable and enforceable. Emissions
averaging would allow owners and operators of an existing affected
source to demonstrate that the source complies with the proposed
emission limits by averaging the emissions from an individual affected
emission unit that is emitting above the proposed emission limits with
other affected emission units at the same facility that are emitting
below the proposed emission limits and that are within the same
averaging group, as described below.
    This proposed rule includes an emissions averaging compliance
alternative because emissions averaging represents an equivalent, more
flexible, and less costly alternative to controlling certain emission
points to MACT levels. We have concluded that a limited form of
averaging could be implemented that would not lessen the stringency of
the MACT limits and would provide flexibility in compliance, cost and
energy savings to owners and operators of existing sources. We also
recognize that we must ensure that any emissions averaging option can
be implemented and enforced, will be clear to sources, and most
importantly, will be no less stringent than unit by unit implementation
of the MACT limits.
    The EPA is proposing to establish within a NESHAP a unified
compliance regimen that permits averaging within an existing affected
source across individual affected units subject to the standard under
certain conditions. Averaging across affected units is permitted only
if it can be demonstrated that the total quantity of any regulated
pollutant that may be emitted by that portion of a contiguous major
source that is subject to the NESHAP will not be greater under the
averaging mechanism than it could be if each individual affected unit
complied separately with the applicable standard. Under this test, the
practical outcome of averaging is equivalent to compliance with the
MACT limits by each discrete unit, and the statutory requirement that
the MACT standard reflect the maximum achievable emissions reductions
is, therefore, fully effectuated.
    In past rulemakings, the EPA has generally imposed certain limits
on the scope and nature of emissions averaging programs. These limits
include: (1) No averaging between different types of pollutants; (2) no
averaging between sources that are not part of the same affected
source; (3) no averaging between individual sources within a single
major source if the individual sources are not subject to the same
NESHAP; and (4) no averaging between existing sources and new sources.
This proposed rule is consistent with these limitations. First,
emissions averaging would only be permitted between individual sources
at a single existing affected source, and would only be permitted
between individual sources subject to the proposed Ferroalloys
Production NESHAP. Further, emissions averaging would not be permitted
between two or more different affected sources. Finally, new affected
sources could not use emissions averaging. Accordingly, we have
concluded that the averaging of emissions across affected units is
consistent with the CAA.
    In addition, this proposed rule would require each facility that
intends to utilize emission averaging to submit an emission averaging
plan, which provides additional assurance that the necessary criteria
will be met. In this emission averaging plan, the facility must include
the identification of: (1) All units in the averaging group; (2) the
control technology installed; (3) the process parameters that will be
monitored; (4) the specific control technology or pollution prevention
measure(s) to be used; (5) the test plan for the measurement of the HAP
being averaged; and (6) the operating parameters to be monitored for
each control device. Upon receipt, the regulatory authority would not
be able to approve an emission averaging plan containing averaging
between emissions of different types of pollutants or between different
affected sources (e.g., between furnaces and crushing and screening
equipment).
    We seek comment on use of a discount factor when emissions
averaging is used and on the appropriate value of a discount factor, if
used. Such discount factors (e.g., 10 percent) have been used in
previous NESHAP, particularly where there was variation in the types of
units within a common source category to ensure that the environmental
benefit was being achieved. In this situation, however, the affected
sources are more homogeneous, making emissions averaging a more
straight forward analysis. Further, with the monitoring and compliance
provisions that are being proposed, there is additional assurance that
the environmental benefit will be realized. The emissions averaging
provisions in this proposed rule are based in part on the emissions
averaging provisions in the Hazardous Organic NESHAP (HON). The legal
basis and rationale for the HON emissions averaging provisions were
provided in the preamble to the final HON.\36\
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    \36\ Hazardous Organic NESHAP (59 FR 19425; April 22, 1994).
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4. Other Changes
    The following lists additional minor changes to the NESHAP we are
proposing. The main focus of these changes is to ensure that the rule
provides adequate monitoring, reporting, recordkeeping and testing
provisions to ensure that the affected sources are able to demonstrate
continuous compliance with the proposed standards. These changes
reflect changes we have made to many other existing NESHAP to improve
the quality of these compliance requirements. This list also includes
proposed rule changes that address editorial corrections and plain
language revisions:

     Reduce frequency of emission testing for the primary
furnace control devices for PM and propose periodic testing for PM
and other regulated pollutants. This change is possible because of
requirement to conduct continuous monitoring. Also add a periodic
testing requirement for the building ventilation system control
devices and crushing and screening equipment control devices.
     Add requirement for new and existing baghouses that
control furnace or building ventilation systems to be equipped with
BLDS to demonstrate continuous compliance. Retain provisions for
baghouses to have a baghouse SOP manual.
     Add requirements to implement and enforce more detailed
requirements for

continuous parameter monitoring systems to ensure continuous
compliance.
     Reduce the shop building opacity limit to 10 percent
opacity to reflect current industry performance. Eliminate 6-minute
excursion level because it does not provide any significant
flexibility (sources that tend to exceed the general opacity limit
in any 6-minute period tend to do so for several minutes so that the
excursions for one 6-minute period is meaningless). Eliminate events
excluded from the opacity observation as they are infrequent, can be
avoided in some cases, are emitted from operations we intend to
control better, and can be confusing to enforce.
     Change the format of the PM standards to reflect an
outlet concentration format (mg/dscm). This format is the direct
output of the emissions test and reflects the constant output nature
of the predominant control device, i.e., a baghouse.
     Add PM continuous emissions monitoring system as an
alternative to installing and operating a BLDS.
     Editorial changes, including revising the titles of
sections in the subpart to better reflect the description of
proposed requirements and to make the regulation easier for the
reader to navigate.
     Update the recordkeeping and reporting sections to
reflect the new monitoring requirements and monitoring options
described above.
     Update the compliance dates to include the anticipated
dates the proposed requirements will become effective.

F. What compliance dates are we proposing?

    We are proposing that facilities must comply with the new proposed
requirements in this action (which are being proposed under CAA
sections 112(d)(2), 112(d)(3), 112(d)(6) and 112(f)(2) for all affected
sources), no later than 2 years after the effective date of this rule.
In the period between the effective date of this rule and the
compliance date, existing sources would continue to comply with the
existing requirements specified in Sec. Sec.  63.1650 through 63.1661.
    Under 40 CFR 63.6(i)(4)(ii), ``the owner or operator of an existing
source unable to comply with a relevant standard established * * *
pursuant to section 112(f) * * * may request that the Administrator
grant an extension allowing the source up to 2 years after the
standard's effective date to comply with the standard.'' The rule
further specifies a written application for such a request. Here, the
EPA is already fully aware of the steps needed for each source to
comply with the proposed standards and to reasonably estimate the
amount of time it will take each source to do so. We believe that the
2-year extension would be warranted in all cases for sources needing to
upgrade current practice. This includes the time needed to: Construct
required building ventilation systems and install associated control
devices for process fugitive sources; determine appropriate mercury and
PAH control devices, locations, amount and type of carbon needed and
assess potential waste disposal issues; select and install appropriate
monitoring technologies; seek bids, select a vendor, install and test
the new equipment; and, purchase, install and conduct QA and quality
control measures on compliance monitoring equipment (see Estimated Time
Needed to Achieve Compliance with The Proposed Revisions to the MACT
standard for Ferroalloys Production Facilities, which is available in
the docket for this proposed action). The EPA believes it reasonable to
interpret 40 CFR 63.6(i)(4)(ii) to allow this plenary finding, rather
than utilizing a facility-by-facility application process, when the
facts are already known and a category-wide adjudication is therefore
possible. In addition, utilizing this process allows for public comment
on the issue which would not be possible if a case-by-case application
process with a 90-day window for completion were used.

V. Summary of Cost, Environmental, and Economic Impacts

A. What are the affected sources?

    We anticipate that the two manganese production ferroalloys
production facilities currently operating in the United States will be
affected by these proposed amendments. We do not know of any new
facilities that are expected to be constructed in the foreseeable
future. However, there is one facility that has a permit to produce
ferromanganese or silicomanganese in an electric arc furnace, but it
did so for only a brief period, several years ago. It is possible that
this facility could resume production or another non-manganese
ferroalloy producer could decide to commence production of
ferromanganese or silicomanganese. One of the existing facilities is
considering building a new manganese furnace, but their timeline and
actual intent to go forward is unclear. Given this uncertainty, our
impact analysis is focused on the two existing sources that are
currently operating.

B. What are the air quality impacts?

    The EPA estimated the emissions reductions that are expected to
result from the proposed amendments to the 1999 NESHAP compared to the
2010 baseline emissions estimates. A detailed documentation of the
analysis can be found in: Draft Cost Impacts of the Revised NESHAP for
the Ferroalloys Production Source Category.
    Emissions of metal HAP from ferroalloys production sources have
declined in recent years, primarily as the result of state actions and
also due to the industry's own initiative. The current proposal would
cut HAP emissions (primarily particulate metal HAP such as manganese,
arsenic and nickel) by 60 percent from their current levels. Under the
proposed emissions limit for process fugitives emissions from the
furnace building, we estimate that the HAP emissions reductions would
be 81 tpy, including significant reductions of manganese. We also
anticipate mercury reductions of 420 lb/yr and PAH reductions of 2.5
tpy from installation of activated carbon injection controls at one
facility. Total HAP reductions for the two facilities are estimated to
be 84 tpy.
    Based on the emissions data available to the EPA, we believe that
both facilities will be able to comply with the proposed emissions
limits for HCl and formaldehyde without additional controls. There may
be some formaldehyde emission reductions at the facility that we
believe will be required to install an activated carbon injection
system, but we have not quantified these reductions because of the
uncertainty of the effectiveness of the activated carbon system
designed for mercury and PAH removal compared to formaldehyde removal.
We do not anticipate any reductions in HCl.

C. What are the cost impacts?

    Under the proposed amendments, ferroalloys production facilities
are expected to incur capital costs for the installation of ductwork
and baghouses for building ventilation and activated carbon injection
systems. There would also be capital costs associated with installing
new or improved continuous monitoring systems, included installation of
BLDS on the furnace and building ventilation baghouses that are not
currently equipped with these systems.
    The capital costs for each facility were estimated based on the
number and types of upgrades required. The memorandum Draft Cost
Impacts of the Revised NESHAP for the Ferroalloys Production Source
Category includes a complete description of the cost estimate methods
used for this analysis and is available in the docket.
    The majority of the capital costs estimated for compliance with the
amendments proposed in this action are for purchasing new control
devices. For the shop building ventilation system, we assumed that each
facility would

need to install a building ventilation system in order to comply with
the proposed shop building emissions limits. For each facility, we
estimated the square footage of shop building air that would need to be
evacuated and the size of control device that would be required.
Although the proposed amendments would provide the alternative option
to install monitors at or near the property boundary to demonstrate
compliance with the building ventilation requirements, we assume that
sources would be unlikely to meet the alternative standard without
improving the level of control in the shop building.
    To estimate the cost for the building ventilation fabric filter, we
contacted a vendor who had recently supplied a fabric filter to one of
the facilities to obtain assistance in developing a cost estimate for
the installation. The equipment-only cost supplied by the vendor was
used in conjunction with techniques described in the sixth edition of
the EPA Air Pollution Control Cost Manual \37\ to estimate total
installed capital cost and annual costs.
---------------------------------------------------------------------------

    \37\ http://epa.gov/ttn/catc/products.html#cccinfo.
---------------------------------------------------------------------------

    Our cost model included installation of the baghouse and any
necessary fans, ductwork, and site work, including extra ductwork for
connection to the building roof monitors. The total installed capital
cost of three fabric filters (two at one facility, one at the second
facility) designed for a flow-rate of 150,000 actual cubic feet per
minute was estimated at $9.4 million. The annualized capital cost and
operational and maintenance costs are estimated at $2.3 million, via
techniques described in the sixth edition of the EPA Air Pollution
Control Cost Manual. The annualized cost assumes a 20-year life
expectancy for the unit and, to be consistent with OMB Guidance in
Circular A-4, a 7 percent cost of capital as an estimate of the
annualized capital cost.
    We considered installation of both fixed carbon beds and activated
carbon injections for the control of mercury and PAH emissions. After
talking to carbon vendors, we learned that fixed carbon beds are not a
viable option given the size of the furnace airstream we would need to
control. We also considered whether to put the activated carbon
injection upstream or downstream of the existing PM control device. By
installing the system downstream of the PM control device, we would
avoid potential concerns with the activated carbon interfering with
potential sale or reuse of baghouse dust or potential increase in
mercury load in the scrubber sludge impoundment. This approach requires
installation of a separate ``polishing'' baghouse to capture the
injected carbon for disposal.
    Unlike activated carbon systems used primarily for control of
volatile organic compounds, we have been told that mercury impregnated
compounds cannot be recycled. There is concern that such downstream
control could result in sufficient concentration of mercury in the
baghouse dust that the facility would be required to treat such dust as
a hazardous waste under the RCRA. However, based on conversations with
vendors and other mercury control experts, we believe that the
resulting waste will most likely be nonhazardous. We are seeking
comments on the cost methodology and assumptions used to develop these
cost estimates.
    Costs for Activated Carbon Injection (ACI) were estimated using
cost equations developed for the Utility NESHAP.\38\ The calculated
equipment costs for ACI and fabric filters were used in conjunction
with techniques described in the sixth edition of the EPA Air Pollution
Control Cost Manual to estimate total installed capital cost and annual
costs. Our cost model included installation of the two ACI systems, one
polishing fabric filter, and associated fans, ductwork, and site work.
We estimate the total capital costs are $1.7 million and the annual
costs are $1.4 million.
---------------------------------------------------------------------------

    \38\ Sargent & Lundy, IPM Model--Revisions to Cost and
Performance for APC Technologies, Mercury Control Cost Development
Methodology Final, March, 2011. http://www.epa.gov/airmarkt/progsregs/epa-ipm/docs/append5_3.pdf.
---------------------------------------------------------------------------

    The estimated costs for the proposed change to the monitoring
requirements for baghouses, including installation of seven new BLDS
for four existing furnace baghouses and three building ventilation
baghouses is $270,000 of capital cost. The capital cost for a
differential pressure monitor to ensure that shop buildings are under
negative pressure is $9,200. The capital cost estimated for a
continuous parameter monitoring system for the wet scrubber at one
facility is estimated to be $50,000. Finally, the estimated capital
cost for carbon injection monitoring is $20,000. The capital costs for
all additional monitoring and recordkeeping requirements, including the
baghouse monitoring proposed, is estimated at $340,200.
    Annualized costs are estimated to be $94,000 for the BLDS, $18,000
for the scrubber parameter monitoring system, and $6,200 for the carbon
injection monitoring system. There is also an estimated annualized cost
to monitor the manganese ore content for mercury emissions of $1,200.
The estimated annual cost for reporting and recordkeeping is $37,000.
We estimate the costs of the periodic performance testing requirements
to be $800,000. The resulting total annualized costs are $347,000.
    The total annualized costs for the proposed rule are estimated at
$4.0 million (2010 dollars). Table 6 provides a summary of the
estimated costs and emissions reductions associated with the proposed
amendments to the Ferroalloys Production NESHAP presented in today's
action.

                Table 6--Estimated Costs and Reductions for the Proposed Standards in This Action
----------------------------------------------------------------------------------------------------------------
                                    Estimated       Estimated        Total HAP       Cost effectiveness in $ per
       Proposed amendment         capital cost     annual cost       emissions         ton total HAP reduction
                                    ($MM) \1\         ($MM)      reductions  (tpy)      (and in $ per pound)
----------------------------------------------------------------------------------------------------------------
Capture and Control Process                 9.4             2.3  81 (of metal HAP)  $0.03 MM per ton.
 Fugitives.                                                                         ($14 per pound).
MACT Limits for Mercury........             1.7             1.4  0.2 (of mercury).  $6.7 MM per ton.
                                                                                ($3,300 per pound).
MACT Limits for co-control of                NA             N/A  2.5 (of PAH).....  N/A.
 PAH.
HCl and formaldehyde                          0               0  0................  N/A.
 concentration limits.
Compliance testing over 3-year              N/A            0.26  N/A..............  N/A.
 period.
Annual average monitoring over             0.11            0.08  N/A..............  N/A.
 3-year period.
----------------------------------------------------------------------------------------------------------------

D. What are the economic impacts?

    We estimate that there will be no more than a 0.2 percent price
change and a similar reduction in output associated with the proposal.
The impacts to affected firms will be low because the annual compliance
costs are quite small when compared to the annual revenues for the two
affected parent firms (much less than 1 percent for each). The impacts
to affected consumers should also be quite small. Thus, there will not
be any significant impacts on affected firms and their consumers as a
result of this proposal.

E. What are the benefits?

    We estimate the monetized benefits of this regulatory action to be
$71 million to $170 million (2010$), at a 3 percent discount rate in
the implementation year (2015). The monetized benefits of the
regulatory action at a 7 percent discount rate are $63 million to $160
million (2010$) in the same implementation year. Using alternate
relationships between PM2.5 and premature mortality supplied
by experts, higher and lower benefits estimates are plausible, but most
of the expert-based estimates fall between these two estimates.\39\ A
summary of the monetized benefits estimates at discount rates of 3
percent and 7 percent is in Table 7 of this preamble.
---------------------------------------------------------------------------

    \39\ Roman, et al., 2008. Expert Judgment Assessment of the
Mortality Impact of Changes in Ambient Fine Particulate Matter in
the U.S. Environ. Sci. Technol., 42, 7, 2268-2274.

            Table 7--Summary of the Monetized Benefits Estimates for the Ferroalloys Industry in 2015
                                               [Millions of 2010$]
----------------------------------------------------------------------------------------------------------------
                                      Estimated
                                       emission      Total monetized      Total monetized benefits  (7% discount
             Pollutant                reductions      benefits  (3%                       rate)
                                        (tpy)         discount rate)
----------------------------------------------------------------------------------------------------------------
PM2.5..............................          257  $71 to $170..........  $63 to $160.
----------------------------------------------------------------------------------------------------------------
\1\All estimates are for the implementation year (``2015'', assuming the final rule is published in January
  2012) and are rounded to two significant figures so numbers may not sum across rows. All fine particles are
  assumed to have equivalent health effects. Benefits from reducing HAPs emissions are not included.

    These benefits estimates represent the total monetized human health
benefits for populations exposed to less PM2.5 in 2015 from
controls installed to reduce air pollutants in order to meet these
proposed standards. These estimates are calculated as the sum of the
monetized value of avoided premature mortality from reducing
PM2.5. To estimate human health benefits derived from
reducing PM2.5, we used the general approach and methodology
laid out in Fann, Fulcher, and Hubbell (2009).\40\ However, in this
proposal we utilized source apportionment air quality modeling for the
ferroalloys industry.\41\ Therefore all benefits per ton estimates are
specific to the ferroalloys sector.
---------------------------------------------------------------------------

    \40\ Fann, N., C.M. Fulcher, B.J. Hubbell. 2009. ``The influence
of location, source, and emission type in estimates of the human
health benefits of reducing a ton of air pollution.'' Air Qual Atmos
Health (2009) 2:169-176.
    \41\ U.S. Environmental Protection Agency. 2011. Technical
support document: Estimating the benefit per ton of reducing PM2.5
precursors from the ferroalloy sector (Draft); EPA: Research
Triangle Park, NC.
---------------------------------------------------------------------------

    To generate the BPT estimates, we used a model to convert emissions
of direct PM2.5 into changes in ambient PM2.5
levels and another model to estimate the changes in human health
associated with that change in air quality. Finally, the monetized
health benefits were divided by the emission reductions to create the
BPT estimates. These models assume that all fine particles, regardless
of their chemical composition, are equally potent in causing premature
mortality because there is no clear scientific evidence that would
support the development of differential effects estimates by particle
type. In this rule only directly emitted PM2.5 is
considered. Direct PM2.5 emissions convert directly into
ambient PM2.5; thus, to the extent that emissions occur in
population areas, exposures to direct PM2.5 will tend to be
higher than exposure to any other precursor, and monetized health
benefits will be higher as well.
    For context, it is important to note that the magnitude of the PM
benefits is largely driven by the concentration response function for
premature mortality. Experts have advised the EPA to consider a variety
of assumptions, including estimates based on both empirical
(epidemiological) studies and judgments elicited from scientific
experts, to characterize the uncertainty in the relationship between
PM2.5 concentrations and premature mortality. For this rule,
we cite two key empirical studies, the American Cancer Society cohort
study \42\ and the extended Six Cities cohort study.\43\ In the
Regulatory Impact Analysis (RIA) \44\ for this rule, we also include
benefits estimates derived from expert judgments and other assumptions.
---------------------------------------------------------------------------

    \42\ Pope et al, 2002. ``Lung Cancer, Cardiopulmonary Mortality,
and Long-term Exposure to Fine Particulate Air Pollution.'' Journal
of the American Medical Association. 287:1132-1141.
    \43\ Laden et al, 2006. ``Reduction in Fine Particulate Air
Pollution and Mortality.'' American Journal of Respiratory and
Critical Care Medicine. 173: 667-672.
    \44\ U.S. Environmental Protection Agency, 2006. Final
Regulatory Impact Analysis: PM2.5 NAAQS. Prepared by
Office of Air and Radiation. October. Available on the Internet at
http://www.epa.gov/ttn/ecas/ria.html.
---------------------------------------------------------------------------

    The EPA strives to use the best available science to support our
benefits analyses. We recognize that interpretation of the science
regarding air pollution and health is dynamic and evolving. After
reviewing the scientific literature and recent scientific advice, we
have determined that the no-threshold model is the most appropriate
model for assessing the mortality benefits associated with reducing
PM2.5 exposure. Consistent with this recent advice, we are
replacing the previous threshold sensitivity analysis with a new
``Lowest Measured Level (LML)'' assessment. While an LML assessment
provides some insight into the level of uncertainty in the estimated PM
mortality benefits, the EPA does not view the LML as a threshold and
continues to quantify PM-related mortality impacts using a full range
of modeled air quality concentrations.
    Most of the estimated PM-related benefits in this rule would accrue
to populations exposed to higher levels of PM2.5. Using the
Pope, et al., (2002) study, 89 percent of the population is exposed at
or above the LML of 7.5 [micro]g/m\3\. Using the Laden, et al., (2006)
study, 31 percent of the population is exposed above the LML of 10
[micro]g/m\3\. It is important to emphasize that we have high
confidence in PM2.5-related effects down to the lowest LML
of the major cohort studies. This fact is important,

because as we estimate PM-related mortality among populations exposed
to levels of PM2.5 that are successively lower, our
confidence in the results diminishes. However, our analysis shows that
the great majority of the impacts occur at higher exposures.
    This analysis does not include the type of detailed uncertainty
assessment found in the 2006 p.m.2.5 NAAQS RIA because we lack the
necessary air quality input and monitoring data to run the benefits
model. In addition, we have not conducted any air quality modeling for
this rule. However, to estimate BPT specifically for this sector we did
have some updated air quality modeling. The 2006 PM2.5 NAAQS
benefits analysis provides an indication of the sensitivity of our
results to various assumptions.
    It should be emphasized that the monetized benefits estimates
provided above do not include benefits from several important benefit
categories, including reducing other air pollutants, ecosystem effects,
and visibility impairment, as well as mercury and other HAPs. Although
we do not have sufficient information or modeling available to provide