new sources (based on the best performing facility, Facility N). In the
beyond-the-floor analysis, we evaluated the impacts of adding a second
carbon adsorber in series with the controls applied to achieve the MACT
floor level of control. We estimate the capital cost would be $3
million with a total annualized cost of $1.3 million per year, an
emission reduction of 9 lb/yr of mercury, and a cost effectiveness of
$150,000/lb of mercury. Because of the small emission reduction and
high cost effectiveness associated with this additional control, we
decided not to go beyond the floor. Therefore, for existing sources of
carbon processes with mercury retorts, the MACT floor limit is the MACT
standard for this affected source. We also considered possible beyond-
the-floor options for new carbon processes with mercury retorts, but
concluded these options were not cost-effective or feasible.
5. Compliance Alternative for New Carbon Process Sources
    Comment: One commenter noted that the compliance ``alternative'' of
97 percent would be unlawful unless EPA specified that carbon sources
had to meet the more stringent of either the floor standard or a 97
percent reduction standard. The commenter stated that because floors
must reflect the emission level achieved by the best performing
sources, allowing sources to meet a 97 percent reduction standard that
was less stringent than the emission level actually achieved by the
relevant best sources would contravene section 112(d)(3) and well-
established D.C. Circuit court precedent.
    One commenter supported EPA's use of the percent control
alternative to the new source MACT for the carbon group. The commenter
believes that the percent control alternative for new source carbon
group MACT should also be available as an alternative to the existing
source MACT for the carbon group.
    Another commenter stated that another facility, which has an
average mercury reduction efficiency level of 99.995 percent,
represents the ``best controlled'' similar source for the carbon
process group and should be the basis for the alternative limits for
new carbon processes.
    Several commenters requested clarification of the way in which
compliance with the alternative for percent reduction would be
demonstrated for new sources when there are multiple control devices on
an emission unit.
    Response: We eliminated in the final rule the compliance
alternative of 97 percent reduction for new carbon processes. After
reviewing the comments received on this standard and giving further
consideration to the practicality of how it would be measured, we
concluded that this option would be difficult to implement,
particularly when multiple processes that are operated at different
times vent to a single control device and stack. In addition, we have
limited data supporting this compliance alternative. In proposing this
alternative for comment, we had hoped to, but did not receive
additional data indicating that the 97 percent reduction option would
be equivalent in stringency to the proposed new source limit of 0.14
pounds of mercury per ton of concentrate. Largely due to the reasons
stated above, we have eliminated the 97 percent control efficiency
option for new carbon processes in the final rule. In addition we are
not allowing this percent reduction to be used for existing carbon
sources. We also note that the facility that one commenter identified
as having an average mercury reduction efficiency level of 99.995
percent is now being used as the ``best controlled'' similar source for
the final MACT standard for new carbon processes with mercury retorts.

D. Compliance Determinations

1. Timing for Compliance Determinations
    Comment: Several commenters requested that the compliance deadline
for existing sources be 3 years after the effective date of the rule,
rather than the 2 years proposed. The commenters noted that several
facilities will have to install control devices to achieve the MACT
floor limits that have been proposed. The commenters explained that the
controls must be custom designed for the unique characteristics of each
process and associated process streams at each facility and stated that
it can be time consuming and difficult to design, procure, construct,
and implement emission controls to ensure effective operation for the
particular source.
    Response: After reviewing the information provided in public
comments on the challenges of retrofitting new controls, we believe
that allowing 3 years for existing sources to comply is appropriate.
Given the complexity of the sources, the combinations of control
devices that are needed in many cases, and the amount of time necessary
for designing, installing, testing, and commissioning additional
emission controls for mercury, we conclude that 2 years may not provide
adequate time for existing sources to comply with the final emission
standards.
    Comment: Several commenters recommended that the rule specify that
source testing results be used to determine compliance for the calendar
year in which the test was conducted rather than to determine
compliance for the prior 12 months. The commenters suggested that the
source test results be applied to the hours of operation at the end of
the calendar year to determine the source's compliance with the MACT
standard on an annual basis, as required in the NMCP. The commenters
suggested that, if more than one source test is conducted in a year,
the facility should average the mercury emission test results to
determine compliance for the calendar year in which the tests were
conducted.
    Another commenter commented that the annual compliance testing
should not be constrained to the same calendar quarter each year. The
commenter stated that this can lead to testing during periods of
operation that may not represent normal production capacities. The
commenter believes that mercury emissions testing should be scheduled
for the most appropriate time interval throughout the calendar year.
    Response: The permitting authority needs to be able to determine
compliance with the NESHAP as soon as possible after the tests are
completed and test results are available. Consequently, the final rule
requires that initial compliance be determined based on production data
and operating hours for all full calendar months between the date the
rule is published in the Federal Register and the date of the
compliance test, and subsequently, annual compliance must be based on
production data and operating hours for the 12 full calendar months
preceding the compliance test. This allows the permitting authority to
determine if the affected source is in compliance in a timely manner.
(This is consistent with the way compliance determinations are made in
another MACT rule that uses a similar format--National Emission
Standards for Hazardous Air Pollutants for Primary Lead Smelting, 40
CFR part 63, subpart TTT.) If compliance was based on a calendar year,
as suggested by the commenter, then we would not know if a source is in
compliance until after December each year. For example, if a source
conducted its compliance test in March, we would have to wait about 9
more months before we could determine if that source was actually in
compliance. After those 9 months, if the source was not in compliance,
it would mean that the source could have been out of compliance for the
previous 9 months.
    Moreover, we do not believe that compliance with the NESHAP based
on the production data from the 12 months prior to the compliance test
would cause problems with reporting under the State program. It is our
understanding that the emissions limits in the Nevada State Phase 2
permits are (or will be) based on concentration in the stacks (e.g.,
micrograms per cubic meter ([mu]g/m\3\)). The limits in this final rule
are based either on pounds of mercury per million tons of ore or pounds
of mercury per tons of concentrate. Therefore, the companies can
continue to report the annual emissions as required under the TRI
program and the State program without conflict with this rule.
    If multiple compliance tests are conducted during the year, then a
compliance determination must be made for each separate compliance test
based on the production data and hours of operation for the 12 full
calendar months preceding each test (i.e., the results of multiple
compliance tests conducted throughout the year are not averaged to
provide a single compliance determination for the year).
    We understand that the rule, as proposed, may have required all
existing sources to conduct their subsequent annual compliance tests in
the same calendar quarter, and this may pose a scheduling problem
because of the large number of facilities located in the same State
(e.g., Nevada). Our concern was that subsequent annual compliance
tests, if not separated in time, could be conducted for two different
years with little time between the two tests (e.g., only a few days
apart for the extreme case where the first test is conducted in late
December and the second one in early January of the following year). We
are providing scheduling flexibility by requiring that annual
compliance tests be at least 3 months apart and no more than 15 months
apart, and we are providing a similar separation for the period between
the initial compliance test and the first annual compliance test. We do
not believe that tracking multiple compliance dates is a particular
problem for the permitting authority because that is the case for many
other source categories subject to annual compliance testing.
2. Test Methods
    Comment: Several commenters supported EPA's proposal of alternate
Methods 30A and 30B for demonstrating compliance. One commenter
supported EPA's requirement to use Method 29 as an emission test
method, but recommended two revisions: Requiring a determination of the
absence of cyclonic flow before sampling, and a minimum sampling time
of 90 minutes for each test run. The commenter also stated that they do
not support the use of the Ontario Hydro Method (ASTM D6784-02), Method
30A, or Method 30B as mercury test methods. The commenter believes that
the methods of demonstrating compliance with the emissions standards
should be consistent with the methods utilized to establish the
emission standards, which were based mainly on Method 29 data. The
commenter said that the typical gas streams associated with the gold
mining industry have high particulate loadings, high mercury
concentrations, sulfur dioxide (SO2), and contain
particulate-bound mercury. The commenter also stated that the
alternative methods were not developed specifically for the gold mining
industry and their typical gas streams and concluded that the results
from the various alternative methods will yield varying results, will
not be comparable, and will provide inconsistent reporting of overall
mercury emissions.

    Response: Method 29 references Method 1, which requires cyclonic
flow checks under certain circumstances. Consequently, in the final
rule, we have removed the specific requirements for cyclonic flow
checks prior to every stack test that were in Sec.  63.11646(a)(1)(vi)
of the proposed rule. Owners or operators should follow the
requirements in the applicable EPA reference method and any additional
requirements specified by the permitting authority.
    When specifying the minimum requirements for compliance tests, it
is more important to specify a minimum sampling volume than a minimum
sampling time because the detection of a regulated pollutant is a
function of the volume of the sample rather than the length of time
taken to collect the sample. Thus, the final rule does not specify a
minimum sampling time. We are also changing the required minimum
sampling volume to be 30 dscf rather than the 60 dscf as proposed in
Sec.  63.11646(a)(2) because we believe that 30 dscf generally will be
adequate for detecting mercury emissions for this industry. Affected
facilities should be aware, however, that the minimum sample volume may
sometimes result in a failure to detect any mercury (a non-detect)
emitted from a process unit subject to the emission standard (for the
group of process units within the affected source) because of a mercury
concentration at the outlet lower than expected. If the emission
testing results for any of the emission points yield a non-detect
value, then the minimum detection limit (MDL) must be used in
calculating the emissions for that emission point and, in turn, for
calculating the sum of the mass emissions for all emission points
subject to the emission standard for determining compliance. If the
resulting mercury emissions (in pounds of mercury per ton of
concentrate, or pounds of mercury per million tons of ore) for the
affected source are greater than the MACT emission standard, the owner
or operator may use procedures that produce lower MDL results and
repeat the mercury emissions testing one additional time for any
emission point for which the measured result was below the MDL. If this
additional testing is performed, the results from that testing must be
used to determine compliance (i.e., there are no additional
opportunities allowed to lower the MDL).
    After reviewing the information provided by the commenter about
Method 29, we agree with the commenter that Method 29 is the most
appropriate method for compliance determinations for this source
category because of the unique characteristics of these sources.
Therefore, we are promulgating Method 29 as the main method for
compliance in this rule. Alternative methods, such as 30B and the
Ontario Hydro method (OHM; ASTM D6784-02), could be used to demonstrate
compliance for this source category if approved by the permitting
authority. These alternative methods (such as 30B and OHM) may prove to
be more appropriate under certain circumstances. However, we have
omitted Method 30A as an option in the final rule, as it is not yet in
general use.

E. Monitoring

1. Compliance Assurance
    Comment: One commenter noted that EPA's proposed mercury standards
are expressed in a format of pounds of mercury per million tons of ore
processed and observed that the proposed rule requires stack testing
only once a year. The commenter claims that EPA's proposed monitoring
requirements would not demonstrate whether sources are in compliance
with their emission standards, which renders the rule unenforceable.
According to the commenter, the once-a-year stack test would provide no
indication as to what a mine's emissions were the rest of the year. The
commenter said that a source that failed its stack test would have only
one violation of emission standards, even if that test showed that the
source likely violated its emission standard throughout the year. The
commenter believes that EPA's proposed monitoring requirements would
not assure compliance with the proposed emission standards. The
commenter also noted that EPA proposed to require sources to monitor
their mercury emissions either with CEMs, sampling, or various types of
parametric monitoring; however, these methods do not provide direct
information about the pounds of mercury emitted. Consequently, none of
these monitoring methods could be used to demonstrate whether a source
is in or out of compliance with the proposed emission standards.
    According to another commenter, all three affected source
categories should be required to use CEMS at all times and at all
emission points. The commenter stated that the ore pretreatment group
especially needs CEMS because of variable levels of mercury in the ore
and different operational measures within the control of the facility.
    Other commenters supported a requirement for continuous monitoring
and said that the CEMS should be incorporated into the compliance
regime as well. The commenters believe that, if the monitoring results
indicate that the mine is consistently out of compliance for a period
of one week without correction, the process unit should be subject to
compliance-based penalties and/or shut down until corrections are made
and the process unit is back in compliance. According to the
commenters, quarterly stack testing should still be required to
demonstrate that the CEMS is working.
    Response: We recognize the importance of requiring adequate
monitoring to assure compliance with the emission standards. Because of
the higher mercury emitting potential of the roaster, we proposed the
option of mercury monitoring using CEMS or weekly monitoring with PS
12B with associated parametric monitoring as well. We are including in
the final rule the option to perform continuous PS 12B monitoring, and,
as with the CEMS, associated parametric monitoring would not be
required. We are changing the frequency of the proposed weekly
concentration monitoring approach for roasters to twice per month (at
least 11 days apart) and would allow a facility to conduct a Method 30B
test (as an alternative to a PS 12B test), supplemented with continuous
parametric monitoring. We changed the frequency because we believe that
sampling twice per month, coupled with continuous parametric
monitoring, is sufficient for determining that the roaster control
devices are operating properly. We added the alternative of using
Method 30B because this method directly measures mercury concentration
and is a valid means of determining whether the concentration is below
the operating limit established during the initial performance test.
The twice per month Method 30B measurements will provide a
concentration value that can be compared to that operating limit to
determine if an exceedance of the operating limit has occurred. Also,
if the twice monthly sampling shows repeated deviations over time, EPA
could decide at a later date that CEMS or continuous monitoring with PS
12B are appropriate and necessary for roasters.
    We disagree with the commenter that the proposed monitoring
requirements render the rule unenforceable. Although the mercury
concentrations monitoring for roasters along with the parametric
monitoring of all control devices on all units do not directly measure
pounds of mercury per ton of input, we believe that these actions,
along with the annual emissions compliance tests, is still an
acceptable approach to assure

compliance with the emission standards all year long. Parametric
monitoring of control devices assures that the control devices are
operating properly (and reducing emissions) on an ongoing basis. Any
exceedance of the parameter limits or operating limits triggers
corrective action. If corrective action does not return the mercury
concentration within the established limits, the plant must conduct a
full compliance test and determine if the source is meeting the mass-
based (lb/million tons of ore) emission standard.
    We do not believe that we should include CEMS as a monitoring
option for the non-roaster sources. These sources have less potential
mercury emissions, and requiring CEMS on all these other units would be
quite costly and burdensome. Moreover, most of these other units are,
or will be, controlled with carbon adsorbers, and the carbon adsorber
monitoring required by the final rule is an effective means of ensuring
the controls are working effectively on a continuing basis. We consider
that either frequent testing of carbon beds to monitor for breakthrough
using Method 30B, or frequent adsorbent sampling for mercury content,
is an effective way to ensure these mercury control systems are
operating properly on a continuing basis. The final rule also requires
parametric monitoring of wet scrubbers that are considered the final
mercury control (i.e., not followed by a carbon adsorber or calomel
mercury scrubber). We believe that annual tests coupled with
appropriate parametric monitoring of the wet scrubbers are sufficient
to ensure emissions are properly controlled on a continuing basis.
    With regard to the comment that quarterly stack testing should be
required for facilities using a CEMS, we believe that following the
Quality Assurance (QA) procedures detailed in 40 CFR 60, Appendix F,
are sufficient to ensure the CEMS continues to operate as designed, and
in this case, additional stack sampling is not necessary.
2. Operating Limits
    Comment: One commenter stated that the operating limits for
roasters and for carbon adsorbers are inappropriate and set up a second
set of MACT standards. The commenter claimed that the operating limits
do not take into account the effects of: Hours of operation of a
process unit on mercury emissions; reduction in performance of a
process unit offset by an improvement in performance of another process
unit; variability in the exhaust gas flow rates with no appreciable
effect on the corresponding mercury emission rate; and variability in
the inlet mercury concentrations to a carbon adsorber. These factors
all result in variability in the outlet mercury concentration. The
commenter also noted that the proposed operating limit for carbon
adsorbers could result in premature carbon change out, resulting in the
generation of more waste. The commenter recommended that EPA defer to
the Nevada state monitoring requirements and only provide for
monitoring of throughput and annual mercury emission testing to
demonstrate compliance with the MACT emission standard. The commenter
believes that any operating limit parameters must be established based
on manufacturer specifications and recommendations in coordination with
the permitting authority and not based on values measured during source
compliance testing.
    Response: We proposed the mercury operating limits as a monitoring
tool to ensure that the processes within individual affected sources
and their associated control devices are functioning properly on a
continuing basis and not as a second set of MACT standards. We
developed emission standards for four affected sources, and the
emission standard for an affected source applies to the sum of
emissions from all process units within the affected source. One unit
could have an upward fluctuation in mercury concentration, but the
group of process units could still meet the MACT limit. We see the
value of the operating limit approach as sufficient to detect
significant increases in emissions and as a valuable tool to ensure the
control devices are operating effectively and provide quick
notification of a potential problem with controls or emissions. The
monitoring parameters are used as compliance indicators, and the
relevant mercury operating limits are the main ``triggers'' of a
possible emissions increase and are set to alert facility operators
when emissions are greater than the corresponding mercury operating
limit. We believe it is important to have such monitoring in the rule
to ensure the control devices are working properly.
    Regarding specific comments about monitoring the carbon adsorber,
the State of Nevada has had good results with conducting sampling of
the carbon adsorber to maintain its performance. The final rule offers
an additional option of measuring the mercury concentration exiting the
carbon adsorber that also achieves the same objective of avoiding
breakthrough of the bed. We do not expect sudden dramatic failures of
this technology. Instead, we expect to obtain close control of
performance by ensuring that the carbon is changed in a way that
prevents breakthrough. This monitoring methodology should also prevent
premature replacement of the bed.
    We disagree with the comments that only monitoring for throughput
and annual emissions testing are sufficient to demonstrate compliance
with the MACT standards. Such an approach does not yield sufficient
data to assure compliance with the emission standards either directly
or indirectly by assuring that the control devices are operating
properly. The parametric monitoring and operating limits specified in
this final rule provide assurance that control devices are properly
operated and maintained between emissions tests, and exceedances of the
operating limit require corrective action. With regard to the comment
that any operating limit parameters should be based solely on
manufacturer specifications and/or in consultation with the permitting
authority, we have provided various options in this rule for
establishing control device parameter limits. Control device operating
parameter values sometimes are site-specific and are associated with a
level of emissions from the source. Therefore, it is generally
preferable for certain control device parameter limits to be associated
with an emissions test that demonstrates compliance with the emissions
standards. However, we agree that certain parameters for mercury
scrubbers applied to roasters, such as the ranges associated with
ensuring the proper chemistry of the scrubber, are best provided by the
system's manufacturer. Guarantees of performance are usually
conditioned by requiring that the system be operated as designed and
specified by the manufacturer, and there is no assurance that a
potentially narrow range that would be established during a short
performance test reflects the full applicable range of proper
operation. We also realize that it may be preferable that the permit
authority establish the parameter limits for some of the control
devices in this industry because of some of the unique characteristics
of the processes and control devices used in this industry and the
experience of the permit authority with addressing these sources.
Therefore, this final rule allows three options for establishing
parameter limits: (1) Based on the initial compliance test; (2)
according to the manufacturer's specifications; or (3) based on limits
established by the permitting authority.
    Comment: Some commenters stated that their established parametric

monitoring programs are sufficient to confirm that mercury emission
controls are functioning properly for roasters. The commenters also
stated that the NMCP permits have required parametric limits and that
additional CEMS for mercury would neither improve the operation of
these current controls, nor reduce mercury emissions. The commenters
concluded that the operating parameters monitored on a regular basis
are key parameters for measuring the efficiency and operation of the
mercury controls and that operating each of these units within the
optimum ranges ensures that mercury emissions are being effectively
controlled.
    Response: As discussed above, we do not believe parametric
monitoring alone is sufficient for roasters because of the very high
mercury emission potential, unless the facility has adequately
demonstrated that the mercury emissions from the roasters are
consistently very low (e.g., less than 10 pounds per million tons). We
have concluded that the combined approach of annual stack compliance
testing along with the mercury concentration monitoring and parametric
monitoring requirements and options outlined in this rule are necessary
to detect excess emissions and to ensure controls are working
effectively on a continuous basis. We note that for facilities that
choose to monitor the mercury concentration from the roaster with CEMS
or continuous PS 12B sampling, they do not have to do parametric
monitoring. For facilities that can demonstrate their mercury emissions
are less than 10 lbs per million tons of ore, they only have to do
parametric monitoring, no mercury concentration monitoring.
3. Mercury Concentration Monitoring for Roasters
    Comment: One commenter stated that the proposed provisions for
monitoring mercury concentrations in roaster emissions are not based on
roaster process and pollution control device operational parameters and
would not yield reliable information that can be used for detecting and
correcting problems. The commenter also stated that the formula for
establishing the mercury operation limit for roasters is not
appropriate because it uses an emission limit that is based on emission
test data from several process units in addition to the roaster. The
commenter recommended using the methods proposed for parametric
monitoring of roaster emission control devices for all roasters. The
commenter also has concerns about utilizing PS 12A (mercury CEMS) and
PS 12B for emissions monitoring purposes because there are terms and
conditions listed in the proposed rule that are not fully defined. The
commenter also recommended deleting the emissions monitoring
requirements for mercury concentration for carbon adsorbers for the
same reasons described above for roasters.
    Response: We disagree with the comment that monitoring the mercury
concentration in roaster emissions would not yield reliable information
that can be used for detecting and correcting problems. An elevated
mercury concentration in the roaster stack gas indicates that there
could be a problem with either the process or the control device, which
could result in excess mercury emissions from that unit. Monitoring the
mercury concentration in roaster emissions provides a direct measure of
the regulated pollutant (mercury). The commenter is correct that the
formula for establishing the mercury operating limit for roasters is
based on emission tests performed on several processes units in
addition to the roaster. However, for the facilities with roasters that
will be subject to the requirements to monitor mercury concentration,
the roaster is the biggest source of potential mercury emissions within
the affected source. Therefore, we conclude that changes in the mercury
concentration in the roaster exhaust gases provide a reasonable
indication of overall emissions from the affected source. In addition,
the operating limit is not used directly to determine compliance with
the MACT emission standard. As mentioned above, it is designed to
detect elevated mercury concentrations in the roaster stack gas, which
could indicate a problem with either the process or the control device.
We continue to believe that it is necessary and appropriate to monitor
mercury concentration for the largest source of potential mercury
emissions in the source category (i.e., the roaster) to detect
excursions in emissions that must be addressed when the operating limit
is exceeded. By developing the mercury operating limit from the
emission standard and compliance test results, an exceedance of the
mercury operating limit will indicate a potential increase in emissions
and that corrective actions are needed.
    As described above, we believe that either continuous mercury
sampling or mercury sampling twice per month (coupled with continuous
parametric monitoring of the control device) should be required for the
roaster emissions. If a CEMS is used, the daily average mercury
concentration is calculated by averaging the hourly emissions
concentrations during that day. The final rule includes continuous
sampling with PS 12B as an option for monitoring roasters. If PS 12B is
used for continuous integrated sampling (i.e., without parametric
monitoring), the daily average concentration is determined by assigning
the mercury concentration measured by the sorbent trap monitoring
system (total mass of mercury collected during the sampling period
divided by the sample volume) as the daily average value to each of the
days covered by the integrated sample.
    A third option is based on short-term sampling twice per month (at
least 11 days apart) for mercury concentration using either PS 12B or
Method 30B, and if this option is chosen, continuous parametric
monitoring of the mercury scrubber must also be performed. For this
short-term sampling option (twice per month sampling) each measured
mercury concentration must be compared to the operating limit to
determine if an exceedance has occurred. For the contents of the
monitoring plan, see 40 FR 63.8(d)(3) and 40 CFR part 60, Appendix F.
    We also disagree that parametric monitoring alone is sufficient for
carbon adsorbers. For carbon adsorbers, measuring the mercury
concentration exiting the carbon bed is also a direct measure of the
pollutant of interest. (The other option as established for years in
NDEP operating permits involves sampling the carbon for mercury
content.) An elevated mercury concentration indicates that there could
be a problem with either the process or the control device, which could
result in excess mercury emissions from that unit. We have established
exit concentration monitoring requirements in many rules for emissions
of organic compounds exiting carbon adsorbers. That monitoring has
proven to be effective to prevent or detect breakthrough, and the same
principles apply here for mercury.
    Comment: Commenters stated that CEMS for gold mining operations are
not capable of accurately measuring mercury emissions and that there
are three major challenges with the feasibility of mercury CEMS for the
gold mining industry: Mercury CEMS calibration, sample transport, and
system operability and reliability. The commenters are concerned with
the unavailability of a means to calibrate the CEMS for roasters
because existing calibrator designs are simply not capable of
generating mercury concentrations high enough to provide meaningful
upscale calibration points

that correspond to gold mining source characteristics. The commenters
noted the unavailability of National Institute of Standards and
Technology (NIST) traceable calibration gases and stated that the
current calibration standards traceable to NIST do not apply to the
full range of mercury concentrations that can be present in the exhaust
gases of roasters. The commenters concluded that the lack of a NIST-
traceable standard is a fatal flaw that precludes using mercury CEMS to
monitor roaster emissions. Regarding sample transport, the commenters
said that current designs of mercury CEMS for coal-fired electric
generating units require high temperature umbilical lines to transport
the sample from the stack to the analyzer and that CEMS on coal-fired
electric generating units have seen umbilical failures occur,
representing another challenge to having CEMS function consistently for
the continuous monitoring of mercury from industrial sources. The
commenters were also concerned with the CEMS operability and
reliability because mercury CEMS must contain some type of converter to
reduce oxidized mercury to elemental mercury and premature catalytic
failures periodically occur in these units resulting in several days of
missing data. The commenters continued by stating that users reported
mercury CEMS to be unavailable as much as 30 to 40 percent of the
electric generating unit operating time. The commenters believe the
amount of downtime to be expected from these systems on roasters would
likely be even higher. The commenter concluded that the breakdown
events, combined with the other types of failures, result in data
availability that is substantially inferior to parametric monitoring
and cannot justify the significant cost and resource investment
necessary to install, operate, and maintain these devices.
    The commenters are concerned that continuous data reports of
mercury emissions that are not accurate, reliable, or credible could be
offered as ``credible evidence'' to assert a violation. The commenter
concluded by stating that this concern was particularly troubling in
Nevada, where there are separate mercury limits established pursuant to
State law.
    Response: Regarding the feasibility of using CEMS to monitor
mercury emissions from roasters, CEMS have been demonstrated for
process units similar to roasters (e.g., coal-fired power plants), and
we believe there is no technical reason why they will not work for the
roasters. (See NESCAUM, 2010. Technologies for Control and Measurement
of Mercury Emissions from Coal-Fired Power Plants in the United States:
A 2010 Status Report Northeast States for Coordinated Air Use
Management (NESCAUM) July 2010).
    Many of the issues with mercury CEMS have been resolved as
facilities have gained experience with their use. However, we realize
that mercury concentrations in the exhaust gases from roasters can be
higher than the range of concentrations for coal-fired power plants,
and that the calibration standards traceable to NIST, that have been
available in the past, have not applied to the full range of mercury
concentrations that can be present in the exhaust gases from roasters.
Nevertheless, as we discussed in the proposal preamble, CEMS
manufacturers supply calibration standards for the ranges of
concentrations seen at roasters.
    In addition, the NIST has recently completed certification of a
`NIST Prime' elemental mercury gas generator at concentrations of 41,
68, 85, 105, 140, 185, 230, 287, and 353 [mu]g/m\3\. Mercury gas
generator vendors may now submit elemental mercury gas generators for
certification to serve as `Vendor Primes' in a wide range of
concentrations. Therefore NIST traceable mercury gas standards can now
be made available in concentrations that cover the full range of the
concentrations typically measured from roasters.
    After consideration of public comments, we continue to believe CEMS
are a valuable tool and a reasonable option for monitoring mercury
concentrations and comparing those concentrations to the operating
limit that is established by CEMS measurements made during the
compliance test. However, we also point out that the final rule does
not require the use of CEMS; instead, the final rule includes CEMS as
one of the three monitoring options. The other two options that we are
promulgating for monitoring mercury from roasters are: (1) Continuous
monitoring using PS 12B; and (2) twice per month sampling using PS 12B
or Method 30B coupled with parametric monitoring. All three of these
monitoring options are intended to ensure that emissions from the
roasters are not exceeding operating limits, or if they do exceed the
operating limits, that corrective actions are taken in a timely manner
to bring the emissions down to within the operating limits. If these
corrective actions are not successful then the facility must perform a
complete compliance test using the methods in section 63.11646 to
determine whether the affected source is in compliance with the MACT
standard. The CEMs can also be used to help identify problems with
control systems and ensure that corrective actions are taken
immediately to fix such problems. The exceedance of the operating limit
is not intended to determine if the source in violation of the MACT
standard. Rather, it would be the subsequent compliance test pursuant
to section 63.11646 that would be used to determine if the source is in
compliance with the MACT standard.
    We understand the commenter's concerns regarding the transport of
samples and converter failures. However, we have revised the final rule
to give facilities 3 years to comply with the rule which will allow
extra time to successfully set-up and operate controls and monitoring
equipment to be able to comply with the MACT standards. We believe this
will provide sufficient time, for facilities that choose the CEMs
monitoring option, to identify and resolve issues with the transport of
samples and converters.
    Comment: One commenter stated that the regulated industry has no
experience with direct measurements of mercury concentrations at the
roaster exhaust gas stream. As a result, the commenter believes that
there will be problems in collecting data, establishing appropriate
timeframes for sampling under PS 12B, maintaining instrument
reliability for CEMS, and in establishing confidence in the accuracy of
the results reported by these methods. The commenter claimed that the
calculated operating limit based on source testing and simultaneous
direct measurements may not be reflective of the future daily
operations of all the stack emissions. The commenter noted that flow
rate measurements are critical in verifying compliance with actual
emission limits because sometimes lower flow rates of the stack exhaust
gas flow can artificially elevate the mercury concentration in the gas
stream with no real effect on emissions. The commenter concluded that
any exceedance in mercury concentration should be verified first with a
compliance test before halting the roaster production.
    Response: We have learned from the comments received that there may
be a learning curve for facilities to implement the concentration
monitoring procedures. As described in section V.D. of this preamble,
we have established in the final rule a compliance date that is 3 years
after the effective date of the final rule for existing sources, partly
to allow sources time to ensure they can successfully comply with the
monitoring requirements, but mainly to allow time to install new
mercury emission

controls that we believe will be necessary to meet the emission
standards in the final rule.
    We agree that mercury concentration measurements are not direct
measurements of the emissions rate from the affected source and that
flow rate, production, and other factors need to be considered. These
are some of the reasons that the operating limit is not being used as a
direct measure of compliance with the MACT standards. However,
concentration measurements above the operating limit should indicate
that either controls are not working effectively or other problems are
occurring. In either case, exceedances of the operating limit require
investigation and may require corrective actions. The requirement to
shut down the roaster has been removed from this final rule. However an
exceedance of the mercury concentration does trigger corrective action,
and if not corrected requires a compliance test.
    Comment: One commenter requested that EPA reduce the weekly Method
12B monitoring frequency to quarterly or at most monthly. The commenter
also requested that EPA include a provision that allows for a source to
demonstrate a correlation or consistency of performance such that the
Method 12B sampling frequency can be further reduced based on the
permitting authority's acceptance of the demonstration. The commenter
suggested that if multiple Method 12B samples are collected in a single
day or over multiple days in the calendar week, then the samples should
be averaged, and this average concentration should be compared to the
operating limit. The commenter said that, for stacks with high mercury
concentration, the sample collection time may be only an hour or two,
and in this case, it may be important to collect more than one sample
in a single day or over multiple days to obtain a representative
mercury concentration measurement.
    Response: After taking into consideration the commenter's
rationale, under this monitoring option, the final rule requires the
sampling of mercury concentration at least twice per month (with 2
samples taken at least 11 days apart) instead of weekly sampling as
proposed. If multiple samples are taken during the twice per month
period, each result must be compared to the operating limit separately
(i.e., not averaged). Otherwise, a high result from a sample taken near
the end of the sampling period might not trigger corrective actions to
correct a problem that developed at that time if the results are
averaged with previous samples during periods of good performance. We
do not agree with the suggestion to allow the monitoring frequency to
be reduced if the monitoring results demonstrate consistency over the
long term. We believe that monitoring the mercury concentration at
least twice per month is necessary for roasters to ensure that
potential problems with control systems are identified quickly and
corrective actions are taken in a timely manner.
4. Parametric Monitoring of Control Device for Roasters
    Comment: Some commenters recommended that EPA remove the provisions
requiring monitoring of the mercury scrubber liquor flow rate and
scrubber pressure drop because each facility that has a roaster has a
unique sequence of air pollution control devices, and monitoring
parameters that may be appropriate for one roaster may not be
applicable to another. One of the commenters said that the scrubber
liquor flow rate is not currently monitored, nor is it considered a
critical parameter in the daily operation of the scrubber mercury
removal tower associated with roasters at their facility. The commenter
further explained that the scrubber is not a spray tower, but instead
the liquor is recirculated in the tower, so the pump is monitored to
insure it is operational. The commenter stated that the pressure drop
across the mercury removal tower at its roasters is monitored, but is
not considered a critical parameter and that the mercuric ion and
chloride ion concentrations that they monitor are the critical
parameters that define the effectiveness of the mercury scrubber.
    Another commenter added that, for the calomel-based mercury
scrubbers, the key parameter is the reagent concentration in the
solution exiting the scrubber and that maintaining the exit reagent
concentration ensures there is sufficient reagent to react with the
mercury vapor. The commenter noted that low exit concentrations
indicate that either the liquor flow rate is too low, or the fresh
reagent addition rate is too low. Thus, liquor flow rate does not need
to be monitored in addition to reagent exit concentration. The
commenter stated that if EPA continues to require them, the ranges
should be based on the manufacturer's specification or an alternative
value approved by the permitting authority, as opposed to the three
test runs from the initial compliance test. One commenter recommended
that the corresponding range or limit for parametric deviations be
applied to a daily average value rather than continuous instantaneous
values or single samples.
    Another commenter also stated that the requirement to establish the
minimum water flow rate and pressure drop of the wet scrubber on
readings taken during the performance test should not apply to
scrubbers on roasters. The commenter noted that these parameters were
intended to monitor for physical processes, and the scrubbers on
roasters often include chemical reactions, which are not monitored.
    Response: We agree that pressure drop is not relevant to mercury
scrubbers because, unlike venturi scrubbers applied to control PM
emissions, it is not related to its mercury emission control
performance. We have removed pressure drop monitoring from the final
rule for mercury scrubbers. However, we continue to believe that it is
important to monitor the scrubber flow rate to ensure the scrubber
solution is being delivered to the system and that the flow is
adequate, which is related to the system's performance. We understand
that some facilities monitor mercury scrubber solution line pressure
(solution header pressure) as an indicator of flow rate, and we agree
this is adequate to ensure proper flow. Consequently, the final rule
requires hourly monitoring of scrubber flow rate (or line pressure) for
mercury scrubbers on roasters. As with the inlet temperature operating
range, the minimum flow rate or line pressure must be established by
one of the following three ways: (1) During the initial compliance
test, (2) from the manufacturer's specifications, or (3) based on the
limits established by the permitting authority. If the facility chooses
the option to establish the limits during initial compliance, the final
rule requires the scrubber flow rate operating limit to be based on
either the lowest value for any run of the initial compliance test or
10 percent less than the average value measured during the compliance
test and the inlet gas temperature operating limit to be based on
either the highest value for any run of the initial compliance test or
10 percent higher than the average value measured during the compliance
test. The final rule requires hourly monitoring and that corrective
action is triggered if the flow rate or line pressure falls below the
established parameter limit.
    Regarding the acceptability of scrubber flow rate and inlet gas
temperature parameter values that were approved by permitting
authorities prior to this final rule, such values must be established
as specified in the final rule

and are not presumed in advance to be acceptable. Note that the
monitoring requirements for wet scrubbers in Sec.  63.11647 of the
final rule would not apply to the mercury scrubbers on roasters, or any
wet scrubber prior to the mercury scrubber on the roasters.
    Comment: One commenter believes that establishing a maximum
operating temperature for inlet gas concentrations by artificially
increasing this temperature during compliance testing may destroy the
control equipment, conflict with recommended operating temperatures,
and artificially increase the reported mercury emissions. The commenter
concluded that these parameters are not deemed critical in the
effective operation of a mercury calomel scrubber. Another commenter
added that their Compliance Assurance Monitoring (CAM) plan provides
for an inlet gas temperature range of 32[deg] to 134 [deg]F to prevent
water freezing problems or extremely hot gas temperatures that could
damage the mercury scrubber. The commenter stated that mercury
scrubbers remove mercury from the gas stream through a chemical
reaction and not a condensation mechanism and that lower temperatures
will not remove (via condensation) additional mercury. The commenter
explained that, although mercury scrubber inlet gas temperature is not
a relevant control performance parameter, their facility maintains the
inlet gas temperature below 134 [deg]F and monitors the temperature
daily to prevent damage to the controls system from excessively low or
high gas temperatures.
    Response: After additional review of operating permits and
consideration of public comments, we have found that the inlet
temperature of the mercury scrubber is monitored and maintained within
a range to provide operational flexibility with the lower end bounded
to prevent freezing and the upper end bounded to prevent damage to
equipment, which in turn could lead to excess emissions. In addition,
we have learned that this temperature is dependent on the cooling tower
water temperature used in the process, and this water temperature can
vary quite widely from winter to summer. Facilities may not be able to
address the issues described above if they can only use initial
compliance testing to establish the inlet temperature operating range,
as we proposed. Consequently, the final rule provides the following
three ways for a facility with a roaster to establish an operating
range for inlet temperature: (1) Based on the maximum inlet temperature
during the initial compliance test; (2) from the manufacturer's
specifications; or (3) based on the limits established by the
permitting authority. If the facility chooses the option to establish
the limits during initial compliance, the final rule requires the inlet
gas temperature operating limit to be based on either the highest value
for any run of the initial compliance test or 10 percent higher than
the average value measured during the compliance test. The facility
must monitor the temperature hourly, and any exceedance of the upper
limit for temperature would trigger corrective action.
5. Exceeding the Operating Limits for Roasters
    Comment: One commenter was concerned about the consequences of
exceeding a parametric monitoring limit. The commenter remarked that
shutting down the roaster for exceeding a monitoring parameter without
evidence of an ongoing emission limit exceedance is arbitrary and
capricious, unnecessarily punitive, and threatens the economic
viability of the regulated sources. The commenter pointed out that the
ranges of parameters measured during source testing are not necessarily
the only ranges within which the unit can operate effectively. The
parameters proposed by EPA are not the best parameters for monitoring
roaster emissions and do not directly correlate to mercury emissions or
proper control system operation. The commenter also objected to the
period of only 45 minutes to investigate and take corrective action.
    One commenter recommended that the corrective action response time
be extended minimally to 48 hours after daily average values are
processed, plus an additional 24 hours to verify the daily average
parametric value was within limits. For facilities that conduct PS 12B
sampling and a daily average parametric deviation persists for 96
hours, the commenter recommended requiring sampling of the roaster's
exhaust using PS 12B within the next 24 hours, then evaluating the
mercury concentration results. If the mercury concentration is below
the operating limit, then, within 10 days of receiving the analytical
results, the facility should be required to either petition the
permitting authority for a change in the parametric limits, or provide
the permitting authority with a compliance plan that details corrective
actions taken to date and the plan and schedule for bringing the
parameter back within range. The commenter said that, if the mercury
concentration is above the operating limit, the facility will be
required to schedule an independent source testing firm to perform a
compliance test within 45 days using one of the approved methods
described in the rule. The commenter noted that the Nevada State agency
requires 30 days to review the testing protocol, and source testing
companies typically require 30 days or more advanced notice.
    For roasters where direct concentration measurements are not
required and a daily average parametric deviation persists for 96
hours, the commenter recommended that within 48 hours, the facility
should: (1) Provide the permitting authority with a compliance plan
that details corrective actions taken to date and the plan and schedule
for bringing the parameter back within the limits; or (2) schedule an
independent source testing firm to perform a compliance test within 45
days using one of the approved methods described in the rule. The
commenter concluded that, if the test results show that the source has
exceeded the threshold of 10 lb/million tons of ore, the facility would
be required to implement direct mercury concentration measurements.
    One commenter requested that EPA provide an exception from the
shutdown requirement when it can be demonstrated that, notwithstanding
an exceedance of the parametric operating range, the roaster mercury
emissions are less than the operating limit for mercury concentration.
The commenter stated that the mercury concentration measurement is a
more direct indication of the ultimate mercury emissions that the
parametric monitors are designed to address.
    Response: We have investigated in greater detail the issues
associated with monitoring roasters, and we have consulted with NDEP
and the owners and operators of roasters to learn more about
appropriate roaster monitoring. We understand that sometimes the ranges
of parameters measured during source testing are not necessarily the
only ranges within which the unit can operate effectively, that is why
in the final rule we are offering two other options for establishing
the ranges: (1) Based on manufacturer's specifications; and (2) ranges
approved by the permitting authority. We believe that monitoring the
scrubber flow rate, inlet gas temperature, and scrubber liquid
chemistry, as required in the final rule, are appropriate parameters to
monitor. We have also revised the requirements of this final rule to
provide assurance that timely corrective actions are taken when a
monitoring parameter is exceeded, and we have included requirements for
testing for

mercury concentrations to determine if the corrective actions were
successful or if a deviation has occurred. The final rule includes
parametric monitoring of the mercury scrubbers applied to roasters to
control mercury. If a parameter is outside of the established range or
limit, corrective actions are triggered. If corrective actions do not
result in the parameter reading being corrected and verified within 48
hours, a mercury concentration measurement (using CEMs, Method 30B, 29,
OHM, or PS 12B) must be made to determine if the operating limit for
mercury concentration is being exceeded. The measurement must be
performed and the concentration determined within 48 hours (after the
initial 48 hours, or a total of 96 hours). If the measured mercury
concentration meets the operating limit for mercury concentration, the
corrective actions are deemed successful. In addition, the owner or
operator may request approval from the permitting authority to change
the parameter range or limit based on measurements of the parameter at
the time the mercury concentration measurement was made. If, on the
other hand, the operating limit is exceeded, the exceedance must be
reported as a deviation and the facility must conduct a full compliance
test within 40 days to determine if the source is in compliance with
the MACT limit. See Sec.  63.11647(d) of final rule.
    Comment: For facilities that monitor roasters with a CEMS, one
commenter proposed that corrective action be required within 48 hours
of receiving and processing the results from the CEMS data, plus an
additional 24 hours should be allowed to collect verification data to
see if the daily average concentration was restored below the operating
limit. The commenter recommended that, if the exceedance persists, the
facility should be required to schedule an independent source testing
firm to perform a compliance test within 45 days.
    For facilities that choose PS 12B monitoring, the commenter
recommended that a deviation be considered an exceedance of the
operating limit if the average of three consecutive sampling results
(three weeks) were above the established limit. The commenter proposed
that the facility should then have one week to take corrective actions,
an additional week to take the verification sample using PS 12B, with
receipt of results the following week (three weeks total). The
commenter stated that if the exceedance persists, the facility should
be required to schedule an independent source testing firm to perform a
compliance test within 45 days using one of the approved methods
described in the proposed rule.
    Response: After considering these comments on the mercury
concentration operating limit and the above discussion on parametric
monitoring of roasters, we have made several clarifications in the
final rule. If a mercury concentration operating limit is exceeded from
either daily average measurements from a CEMS, continuous sampling
using PS 12B, or from sampling twice per month (at least 11 days apart)
using PS 12B or Method 30B, the exceedance must be reported to the
permit authority as a deviation and corrective actions must be
implemented within 48 hours upon receipt of the sampling results that
show the deviation. Moreover, within 96 hours of the exceedance, the
owner or operator must measure the concentration again (with the CEMS,
PS 12B, Method 30B, Method 29, or OHM) and demonstrate to the permit
authority that the operating limit for mercury concentration has been
met, or inform the permit authority that the limit continues to be
exceeded. If the operating limit is still exceeded after these 96
hours, the owner or operator must conduct a full compliance test for
the ore pretreatment affected source within 40 days to determine if the
affected source is in compliance with the MACT emission standard. If
the source is determined to be in compliance, the compliance test may
also be used to establish a new operating limit for mercury
concentration. See Sec.  63.11647(a)(1)(ii), (a)(2)(ii), and (a)(3)(ii)
of the final rule.
    Comment: One commenter requested that EPA provide an exception to
the shutdown requirement for facilities that have well-controlled
roasters and elect to monitor under the proposed Option 3. The
commenter believes a facility should have time (45 days) to demonstrate
that the roaster's mercury emissions remain less than 10 lbs of mercury
per million tons of ore. The commenter stated that this would be
achieved by scheduling an independent source testing firm to perform a
compliance test using methods described in the rule, and calculations
that demonstrate compliance with the limit of 10 lbs per million tons
of ore.
    Response: As we have discussed above, the final rule relies in part
on parametric monitoring of mercury scrubbers used on roasters to
assure compliance with the applicable emission standards, and when the
measured parametric values are out of the established operating range,
corrective actions must be taken. This is no different for facilities
that qualify for the exemption described in Sec.  63.11647(a)(5) of the
final rule (i.e., facilities exempt from mercury concentration
monitoring by having demonstrated that their roaster emissions are less
than 10 lb/million tons of ore). For these facilities, the final rule
similarly requires that corrective actions be taken to restore the
scrubber operating parameters to the established operating range. If
the parameters are not restored to the established range within 48
hours of triggering the corrective actions, the owner or operator must
perform mercury concentration sampling of the roaster emissions using
PS 12B, Method 30B, Method 29, CEMS or OHM and determine the mercury
concentration within 48 hours following the initial 48 hours (or a
total of 96 hours from the time the parameter range was exceeded). The
measured concentration must be compared to a mercury concentration
operating limit that is based on Equation 2 in the final rule, where
the value for ``Ctrap'' in Equation 2 is based on the
mercury concentration for the roaster measured during the most recent
compliance test. If the measured mercury concentration meets the
operating limit for mercury concentration, the corrective actions are
deemed successful. In addition, the owner or operator may request
approval from the permitting authority to change the parameter range or
limit based on measurements of the parameter at the time the mercury
concentration measurement was made. If the operating limit is exceeded,
the facility must take corrective actions and report it to the permit
authority as a deviation. The owner or operator must also conduct a
compliance test within 40 days to determine if the roaster operations
are in compliance with the emission standard. See Sec.  63.11647(d) of
the final rule. We also note that the requirement to shut down the
roaster has been removed from this final rule.
6. Carbon Adsorber Temperature Monitoring
    Comment: Several commenters stated their concern with the proposed
requirement of monitoring gas stream temperature at the inlet to the
carbon adsorber and maintaining the inlet temperature below the maximum
temperature established during the compliance test. They noted that the
primary purpose for monitoring the inlet gas stream temperature of
carbon adsorbers is to prevent spontaneous combustion of the sulfidized
carbon in the adsorber, not to detect excursions in mercury emissions.
The commenters also stated that some carbon adsorption systems heat the
gas stream prior to the

carbon adsorber to prevent moisture buildup and/or subsequent
condensation in the carbon. The commenters explained that the NMCP
already requires that the exit gas temperature of condensers prior to
the carbon adsorbers be established to minimize mercury emissions from
the condenser. The commenters believe that an increase in inlet gas
temperature to a carbon adsorption unit is not indicative of an
increase in inlet gas stream mercury emissions because the high
operating temperatures of the processes volatilize approximately 100
percent of mercury. The commenters stated that establishing a maximum
operating temperature for inlet gas concentrations by artificially
increasing this temperature during compliance testing may destroy
mercury control equipment; conflict with NMCP requirements and/or
manufacturer's recommended operating temperatures; artificially
increase the reported mercury emissions; or artificially decrease the
allowable operating limit for mercury concentration.
    The commenters continued by stating that, if EPA persisted in
requiring the monitoring of the gas stream inlet temperature, the
maximum inlet temperature limit should be established by either the
manufacturer's recommendation and/or concurrence with the permitting
authority. The commenters proposed monitoring the inlet temperature
once per shift as an option to continuously monitoring the inlet
temperature and comparing the daily averages rather than the hourly
averages to the operating limit. The commenters noted that many
facilities do not have digital acquisition systems capable of recording
continuous data, and monitoring once per shift is sufficient to
maintain control performance. The commenters suggested that, if
corrective action is needed, the facility should be allowed to sample
the carbon loading to demonstrate that the effectiveness of the carbon
adsorber has not been adversely impacted.
    Response: The purpose of monitoring the inlet temperature to carbon
adsorbers is not to provide an indication of higher mercury
concentrations in the inlet stream as suggested by the commenters. The
purpose is related to the fact that temperature is a fundamental
parameter that affects the efficiency and capacity of carbon adsorbers.
Generally, higher temperatures result in lower capacity and earlier
breakthrough and, in fact, high temperatures are used to desorb
adsorbed pollutants to regenerate carbon. In the extreme of
temperature, the carbon adsorber might actually be desorbing rather
than acting as a control device. This is particularly important for
those carbon adsorbers applied to high temperature thermal processes,
such as carbon kilns and melt furnaces, where it is possible for the
exhaust temperature to rise above the normal operating temperature or
above the temperature at which the carbon adsorber was designed to
operate. For high temperature processes (such as furnaces), and not
those such as electrowinning where the temperature may be near ambient
conditions, we continue to require monitoring the inlet temperature.
Owners or operators must establish an operating limit for temperature
based on one of the following: (1) The maximum temperature during the
initial compliance test; (2) from the manufacturer's specifications; or
(3) based on limits established by the permitting authority. If this
established operating limit is exceeded corrective action must be taken
and the exceedance reported as a deviation to the permit authority.
Further, the final rule requires facilities to monitor inlet
temperature once per shift rather than continuously, as was proposed.
Because inlet temperatures should not vary greatly over the course of
an 8- to 12-hour period, we believe monitoring once per shift is
adequate. We also conclude that if a temperature exceedance has
occurred, the carbon bed should be sampled or the outlet concentration
determined, depending on the monitoring option chosen, within 48 hours
to ensure no permanent damage to the carbon adsorber occurred as a
result of the deviation. We believe the temperature exceedance should
be reported as a deviation even if the subsequent monitoring shows that
the carbon bed is operating properly because the subsequent monitoring
would not necessarily detect if mercury had been desorbed and excess
emissions occurred.
7. Monitoring of Wet Scrubbers
    Comment: One commenter proposed that only the scrubber water flow
rate monitoring be required for wet scrubbers on the quenching circuits
associated with the roaster. The commenter wanted to confirm that wet
scrubber monitoring does not apply to wet scrubbers or condensers on
roasters. Another commenter asked that EPA confirm that the term ``wet
scrubbers'' does not include condensers, which are used throughout the
mining processes for gas cooling to condense water or (in the case of
retorts) mercury. Another commenter asked EPA to confirm that wet
scrubber monitoring does not apply to wet scrubbers associated with ore
preheaters.
    One commenter noted that continuous readings on wet scrubbers are
unreliable and proposed monitoring the water flow rate and pressure
drop once per shift. The commenter noted that if any water flow rate or
pressure drop reading exceeds the operating limit, the facility should
follow the procedures for operating limit exceedances. The commenter
stated that many facilities do not have data acquisition systems
capable of recording continuous data and that wet scrubbers are
primarily used to control particulates. The commenter concluded by
stating that wet scrubbers are not key mercury controls and monitoring
once per shift is sufficient to maintain control performance on a
continuing basis.
    One commenter wanted to confirm that the limits established during
testing would not be more stringent than the requirements set forth in
the Standards of Performance for New Stationary Sources for Metallic
Mineral Processing Plants, which allows for plus or minus 30 percent.
Another commenter recommended that the operating limit for wet scrubber
monitoring be based on either the lowest average value during any test
run or no lower than 10 percent below the average value measured during
the test.
    Response: We are clarifying in the final rule that Sec.
63.11647(h) applies only to wet scrubbers not followed by a mercury
control system (i.e., carbon adsorber, calomel mercury scrubber, etc.).
It is necessary to monitor the primary mercury emission control device,
which is the last stage of the exhaust gas cleaning treatment train, to
ensure it is operating properly and controlling mercury emissions, and
the rule does not require that wet scrubbers in the gas treatment train
(typically used for control of PM and/or SO2) prior to the
primary mercury emission control device be monitored under this rule
for mercury emissions. However, if there is no carbon adsorber or
mercury scrubber, and the wet scrubber in question is the only control
device for mercury emissions, the final rule requires that it be
monitored once per shift per operating day (e.g., minimum of two times
per day) for pressure drop and flow rate with operating limits that are
either established during the initial compliance test, from the
manufacturer's specifications, or based on approval from the permitting
authority (except for pressure drop for autoclaves as discussed above).
This applies to wet scrubbers on ore preheaters and quenching if there
is no

carbon adsorber or mercury scrubber in the exhaust gas treatment train.
As discussed above, the scrubber monitoring for roasters applies to the
mercury scrubber (located at or near the end of the exhaust gas
treatment train) and does not apply to the wet scrubbers that are used
to remove PM and SO2 prior to the mercury scrubber.
    We are clarifying in the final rule that condensers, such as those
found at roasters and mercury retorts, are not wet scrubbers. We agree
that monitoring and recording the pressure drop once per shift is
adequate for monitoring these wet scrubbers to ensure they are
operating properly. We disagree that a buffer of  30
percent based on a certain New Source Performance Standard (NSPS)
subpart is appropriate for this NESHAP for mercury. The comment
suggesting an option of a  10 percent buffer around the
average value during the performance test has merit as an option to
only using the lowest value during any individual run as the operating
limit. If the system is so stable that it shows very minimal
variability during the performance test, we agree that it is
appropriate to add  10 percent to account for potential
future variability. Consequently, we are incorporating this option in
the final rule, as suggested by the commenter. However, we are using
 10 percent rather than  30 percent. We are
also clarifying for the final rule for wet scrubbers on an autoclave,
that facilities must establish the pressure drop range according to
manufacturer's specifications.
8. Monitoring of Multiple Units Ducted to One Stack
    Comment: Commenters requested clarification that, for facilities
that have two roasters ducted together through a shared mercury control
system, the mercury concentration monitoring would be conducted on the
combined exhaust stream. The commenters also requested clarification
that the mercury concentration operating limit for two roasters that
share a control system would be established during the simultaneous
operation of the roasters in order to account for the combined mercury
emissions from both roasters.
    Commenters also requested clarification that, for facilities with
multiple process units ducted together through a shared carbon
adsorber, the mercury concentration monitoring would be conducted on
the combined exhaust stream. The commenters also requested
clarification that the mercury concentration operating limit for a
carbon adsorber for multiple units that share the carbon adsorber would
be established during the simultaneous operations of all process units
in order to account for the combined mercury emissions.
    Response: We agree with the commenters in general and have made the
following clarifications in the final rule. If two roasters share a
common control device and stack, the mercury concentration operating
limit can be based on both roasters operating if possible. However,
monitoring for mercury concentration must be performed at the frequency
specified in the final rule whether only one or both roasters are
operating. We also have clarified that, for multiple process units
vented to a common carbon adsorber, the mercury concentration operating
limit can be based on all units operating if possible. However, the
ongoing mercury concentration monitoring must be performed at the
frequency specified in the final rule for whatever units are operating
at the time.
9. Monitoring Mercury Concentration in Roaster Ore
    Comment: One commenter objected to the proposed requirement to
conduct additional compliance testing if the mercury concentration in
the ore fed to the roaster is higher than any concentration measured in
the previous 12 months. The commenter stated that there would not be an
increase in the mercury emissions from their roasters because of the
extensive series of mercury controls, some of which operate more
efficiently at higher mercury loadings with unchanged stack emissions.
In addition, the commenter noted that the rule does not provide details
on how to measure the mercury ore concentration or what threshold of
significance would be used to show an increase in ore mercury content
occurred. The commenter concluded that the requirement would only
provide extra cost and burden without any environmental benefit.
    Response: We agree with the commenter and have removed this
requirement (Sec.  63.11647(a)(4)(iii) of proposed rule) from the final
rule. We have no data showing that the mercury content of the ore has a
significant effect on the performance of mercury scrubbers applied to
roasters, which are designed to handle and operate efficiently for a
range of mercury inlet concentrations. In addition, roasters condense
and recover elemental mercury prior to the mercury scrubber, and any
increase in mercury loading would likely result in an increase in the
recovery of liquid elemental mercury. We have identified and require
the monitoring of parameters associated with the scrubber chemistry,
and maintaining these parameters within the established range for which
the mercury scrubber was designed. This monitoring approach helps
ensure that the mercury scrubbers are controlling mercury emission
independent of variations in ore mercury content.

VI. Summary of Environmental, Economic and Health Benefits

    For proposal, we estimated baseline mercury emissions to be 3,119
lb/yr based on the available emissions data and average process data
for the period 2007 to 2009. To estimate the impacts of the final rule,
we have revised our baseline mercury emissions estimate to account for
the recent installation of new mercury emission controls at two
facilities and additional test data received since proposal. As a
result of these changes, we now estimate baseline mercury emissions to
be 2,636 lb/yr. We estimate the final MACT standard will reduce mercury
emissions from gold mine ore processing and production by 1,461 lb/yr
from the baseline emissions levels of 2,636 lb/yr down to a level of
1,176 lb/yr once this NESHAP is fully implemented. The annual emissions
expected after the MACT standards are implemented (1,176 lb/yr)
represent an estimated 77 percent reduction from 2007 emissions (5,000
lb/yr), a 95 percent reduction from the emissions level in 2001 (about
23,000 lb/yr), and more than 97 percent reduction from uncontrolled
emissions levels (more than 37,000 lb/yr). The capital cost of emission
controls is estimated as $36 million with a total annualized cost of $8
million per year. The capital costs for monitoring, reporting, and
recordkeeping are estimated as $0.5 to $1.0 million with a total
annualized cost of $0.7 to $1.5 million per year, depending on the
monitoring option that is chosen. The overall cost effectiveness is
estimated to be about $6,300 per pound of mercury reduced. The cost of
compliance is estimated to be less than 0.8 percent of sales for all
affected firms. We therefore believe that the economic impact on an
affected company would be insignificant. Electricity consumption is
expected to increase by about 12,600 megawatt-hours per year due to
increased fan capacity for carbon adsorbers and the installation of
refrigeration units or condensers on a few process units. Non-hazardous
solid waste (spent carbon containing mercury that must be regenerated
or disposed of) would increase by about 7 tons per year.

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    This action is a ``significant regulatory action'' under the terms
of Executive Order 12866 (58 FR 51735, October 4, 1993) because it may
raise novel legal or policy issues. Accordingly, EPA submitted this
action to the Office of Management and Budget (OMB) for review under
Executive Order 12866, and any changes made in response to OMB
recommendations have been documented in the docket for this action.

B. Paperwork Reduction Act

    The information collection requirements in this final rule have
been submitted for approval to OMB under the Paperwork Reduction Act,
44 U.S.C. 3501 et seq. The Information Collection Request (ICR)
document prepared by EPA has been assigned EPA ICR No. 2383.01.
    The recordkeeping and reporting requirements in this final rule are
based, in large part, on the information collection requirements in
EPA's NESHAP General Provisions (40 CFR part 63, subpart A). The
recordkeeping and reporting requirements in the General Provisions are
specifically authorized by section 114 of the CAA (42 U.S.C. 7414). All
information other than emissions data submitted to EPA pursuant to the
information collection requirements for which a claim of
confidentiality is made is safeguarded according to CAA section 114(c)
and EPA's implementing regulations at 40 CFR part 2, subpart B.
    This final NESHAP will require applicable one-time notifications
according to the NESHAP General Provisions. In addition, owners or
operators must submit annual notifications of compliance status and
report any deviations in each semiannual reporting period. Records of
all performance tests, measurements of feed input rates, monitoring
data, and corrective actions will be required.
    The average annual burden for this information collection averaged
over the first 3 years of this ICR is estimated to total 483 labor
hours per year at a cost of approximately $26,847 per year for the 21
facilities that will be subject to this final rule, or approximately 23
hours per year per facility. Capital costs are estimated as $1.0
million, operation and maintenance costs are estimated as $52,000 per
year, and total annualized cost (including capital recovery) is
estimated as $360,210 per year for this final rule's information
collection requirements. No costs or burden hours are estimated for new
sources because none is projected for the next 3 years. Burden is
defined at 5 CFR 1320.3(b).
    An agency may not conduct or sponsor, and a person is not required
to respond to, a collection of information unless the collection
displays a currently valid OMB control number. The OMB control numbers
for EPA's regulations in 40 CFR part 63 are listed in 40 CFR part 9. In
addition, EPA is amending the table in 40 CFR part 9 of currently
approved OMB control numbers for various regulations to list the
regulatory citations for the information requirements contained in this
final rule.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act generally requires an agency to
prepare a regulatory flexibility analysis of any rule subject to notice
and comment rulemaking requirements under the Administrative Procedure
Act or any other statute unless the agency certifies that this rule
would not have a significant economic impact on a substantial number of
small entities. Small entities include small businesses, small not-for-
profit enterprises, and small governmental jurisdictions.
    For the purposes of assessing the impacts of this final NESHAP on
small entities, a small entity is defined as: (1) A small business
whose parent company meets the Small Business Administration size
standards for small businesses found at 13 CFR 121.201 (less than 500
employees for gold mine ore processing and production facilities--NAICS
212221); (2) a small governmental jurisdiction that is a government of
a city, county, town, school district, or special district with a
population of less than 50,000; and (3) a small organization that is
any not-for-profit enterprise that is independently owned and operated
and is not dominant in its field.
    After considering the economic impacts of this final rule on small
entities, I certify that this action will not have a significant
economic impact on a substantial number of small entities. This final
rule is estimated to impact about 21 gold mine ore processing and
production facilities, none of which are owned by small entities. Thus,
there are no impacts to small entities from this final rule. Although
this final rule will contain requirements for new sources, EPA expects
few, if any, new sources to be constructed in the next several years.
Therefore, EPA did not estimate the impacts for new affected sources
for this final rule.
    Although this final rule will not have a significant economic
impact on a substantial number of small entities, EPA nonetheless has
tried to reduce the impact of this final rule on small and large
entities. These standards establish emission limits that reflect
practices and controls that are used throughout the industry and in
many cases are already required by State operating permits. These
standards also require only the essential monitoring, recordkeeping,
and reporting needed to verify compliance. These final standards were
developed based on information obtained from industry representatives
in our surveys, consultation with business representatives and their
trade association and other stakeholders.

D. Unfunded Mandates Reform Act

    This final rule does not contain a Federal mandate that may result
in expenditures of $100 million or more for State, local, and tribal
governments, in the aggregate, or to the private sector in any one
year. This final rule is not expected to impact State, local, or tribal
governments. The total nationwide annualized cost of this final rule
for affected industrial sources is $9.1 million/yr. Thus, this final
rule is not subject to the requirements of sections 202 and 205 of the
Unfunded Mandates Reform Act (UMRA).
    This final rule is also not subject to the requirements of section
203 of UMRA because it contains no regulatory requirements that might
significantly or uniquely affect small governments. This final rule
will not apply to such governments and will not impose any obligations
upon them.

E. Executive Order 13132: Federalism

    This action does not have federalism implications. It will not have
substantial direct effects on the States, on the relationship between
the national government and the States, or on the distribution of power
and responsibilities among the various levels of government, as
specified in Executive Order 13132. This final rule does not impose any
requirements on state and local governments. Thus, Executive Order
13132 does not apply to this action.
    In the spirit of Executive Order 13132, and consistent with EPA
policy to promote communications between EPA and State and local
governments, EPA specifically solicited comment on this proposed action
from State and local officials.

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

    This action does not have tribal implications, as specified in
Executive Order 13175 (65 FR 67249, November 9, 2000). This final rule
imposes no requirements on tribal governments; thus, Executive Order
13175 does not apply to this action. Although EPA requested comment
from tribal officials in developing this action, no comments on the
proposal were received from tribal governments. However, the reductions
in mercury emissions to the environment, which will be achieved by this
final rule, will certainly benefit tribal populations within the
vicinity of affected gold mine ore processing and production
facilities.

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

    EPA interprets Executive Order 13045 (62 FR 19885, April 22, 1997)
as applying only to those regulatory actions that are based on health
or safety risks, such that the analysis required under section 5-501 of
the Executive Order has the potential to influence the regulation. This
action is not subject to Executive Order 13045 because it is based
solely on technology performance. However, we note that the final rule
will result in significant reductions in emissions of mercury, and thus
will provide benefits to children's health.

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

    This action is not a ``significant energy action'' as defined in
Executive Order 13211 (66 FR 28355, May 22, 2001) because it is not
likely to have a significant adverse effect on the supply,
distribution, or use of energy. We have concluded that this final rule
will not likely have any significant adverse energy effects because
energy consumption would increase by only 12,600 megawatt-hours per
year.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (``NTTAA''), Public Law 104-113 (15 U.S.C. 272 note),
directs EPA to use voluntary consensus standards (VCS) in its
regulatory activities unless to do so would be inconsistent with
applicable law or otherwise impractical. VCS are technical standards
(e.g., materials specifications, test methods, sampling procedures,
business practices) that are developed or adopted by voluntary
consensus standards bodies. NTTAA directs EPA to provide Congress,
through OMB, explanations when the Agency decides not to use available
and applicable VCS.
    This final rulemaking involves technical standards. EPA decided to
use ASME PTC 19.10-1981, ``Flue and Exhaust Gas Analyses,'' for its
manual methods of measuring the oxygen or carbon dioxide content of the
exhaust gas. These parts of ASME PTC 19.10-1981 are acceptable
alternatives to EPA Method 3B. This standard is available from the
American Society of Mechanical Engineers (ASME), Three Park Avenue, New
York, NY 10016-5990.
    Another VCS, ASTM D6784-02, ``Standard Test Method for Elemental,
Oxidized, Particle-Bound and Total Mercury in Flue Gas Generated from
Coal-Fired Stationary Sources (Ontario Hydro Method)'' is an acceptable
alternative to EPA Method 29 for this NESHAP if approved by the permit
authority. This performance test method is available from ASTM
International. See http://www.astm.org/.
    EPA has also decided to use EPA Methods 1, 1A, 2, 2A, 2C, 2D, 2F,
2G, 3, 3A, 3B, 4, 12A, 12B, 29, 30B, SW-846 Method 7471B, ``Mercury in
Solid or Semisolid Waste (Manual Cold-Vapor Technique),'' (incorporated
by reference--see Sec.  63.14) and ASTM D6784-02, ``Standard Test
Method for Elemental, Oxidized, Particle-Bound and Total Mercury in
Flue Gas Generated from Coal-Fired Stationary Sources,'' (incorporated
by reference--see Sec.  63.14). Although the Agency has identified 14
VCS as being potentially applicable to these methods cited in this
rule, we have decided not to use these standards in this final
rulemaking. The use of these VCS would have been impractical because
they do not meet the objectives of the standards cited in this rule.
The search and review results are in the docket for this final rule.
    Under section 63.7(f) and section 63.8(f) of Subpart A of the
General Provisions, a source may apply to EPA for permission to use
alternative test methods or alternative monitoring requirements in
place of any required testing methods, performance specifications, or
procedures in the final rule.

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

    Executive Order 12898 (59 FR 7629, February 16, 1994) establishes
Federal executive policy on environmental justice. Its main provision
directs Federal agencies, to the greatest extent practicable and
permitted by law, to make environmental justice part of their mission
by identifying and addressing, as appropriate, disproportionately high
and adverse human health or environmental effects of their programs,
policies, and activities on minority populations and low-income
populations in the United States.
    EPA has determined that this final rule will not have
disproportionately high and adverse human health or environmental
effects on minority or low-income populations because it will increase
the level of environmental protection for all affected populations
without having any disproportionately high and adverse human health or
environmental effects on any population, including any minority or low-
income population.
    Additionally, the Agency has reviewed this rule to determine if
there were any existing disproportionately high and adverse human
health or environmental effects on minority or low-income populations
that could be mitigated by this rulemaking. An analysis of demographic
data showed that the areas in closest proximity to gold mines are very
rural, with low total populations. The population total for block
groups which centers are within 3 miles of a gold mine facility is
1,580. At the three mile radius, minority populations and children's
populations are underrepresented when compared to national averages,
while populations living below poverty are overrepresented. The
aggregate average percentages for these groups are 26.3 percent, 30.5
percent, and 26 percent for minority populations, populations living
below poverty, and children's populations, respectively. These averages
are compared to national averages across block groups for these
populations which are 31.8 percent, 12.5 percent, and 25.7 percent.
There were only two block groups with centers within 3 miles of any
gold mine, and the total population living below poverty was found to
be 492.
    In determining the aggregate demographic makeup of the communities
near affected sources, EPA used census data at the block group level to
identify demographics of the populations considered to be living near
affected sources, such that they have notable exposures to current
emissions from these sources. In this approach, EPA reviewed the
distributions of different socio-demographic groups in the locations of
the expected emission reductions from this rule. The review

identified those census block groups within a circular distance of a 1,
3, and 5 miles of affected sources and determined the demographic and
socio-economic composition (e.g., race, income, education, etc.) of
these census block groups. The radius of 3 miles (or approximately 5
kilometers) has been used in other demographic analyses focused on
areas around potential sources.5 6 7 8 Gold mine facilities
were assumed to have an average area of 7 square miles and buffered
distances were calculated beyond the 7 square mile area to count
populations not within the mine boundaries. EPA's demographic analysis
has shown that these areas have an overrepresentation of populations
below poverty, and an underrepresentation of minority and children's
populations.\9\
---------------------------------------------------------------------------

    \5\ U.S. GAO (Government Accountability Office). Demographics of
People Living Near Waste Facilities. Washington, DC: Government
Printing Office; 1995.
    \6\ Mohai P, Saha R. ``Reassessing Racial and Socio-economic
Disparities in Environmental Justice Research''. Demography.
2006;43(2):383-399.
    \7\ Mennis J. ``Using Geographic Information Systems to Create
and Analyze Statistical Surfaces of Populations and Risk for
Environmental Justice Analysis''. Social Science Quarterly,
2002;83(1):281-297.
    \8\ Bullard RD, Mohai P, Wright B, Saha R, et al. Toxic Waste
and Race at Twenty 1987-2007. United Church of Christ. March 2007.
    \9\ The results of the demographic analysis are presented in
``Review of Environmental Justice Impacts for Gold Mines'', December
2010, a copy of which is available in the docket.
---------------------------------------------------------------------------

    This action establishes national emission standards for new and
existing gold mines. The EPA estimates that there are approximately 23
such locations covered by this rule. The rule will reduce emissions of
mercury (Hg), and as a result have positive health and welfare benefits
to sustenance fishing communities, many of which are often considered
to have environmental justice concerns.
    EPA defines ``Environmental Justice'' to include meaningful
involvement of all people regardless of race, color, national origin,
or income with respect to the development, implementation, and
enforcement of environmental laws, regulations, and policies. To
promote meaningful involvement, EPA has developed a communication and
outreach strategy to ensure that interested communities have access to
this rule and are aware of its content. EPA will publicize the
rulemaking via EJ newsletters, Tribal newsletters, EJ listservs, and
the Internet, including EPA's Office of Policy's Rulemaking Gateway Web
site (http://yosemite.epa.gov/opei/RuleGate.nsf/). EPA will also
conduct targeted outreach to EJ communities as appropriate. Outreach
activities may include providing general rulemaking fact sheets (e.g.,
why is this important for my community) for EJ community groups and
conducting conference calls with interested communities. In addition,
State and Federal permitting requirements will provide State and local
governments and members of affected communities the opportunity to
provide comments on the permit conditions associated with permitting
the sources affected by this rulemaking.
    Overall, this final rule is expected to reduce mercury emissions
from gold mine ore processing and production facilities and thus
decrease the amount of such emissions to which all affected populations
are exposed.

K. Congressional Review Act

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the
Small Business Regulatory Enforcement Fairness Act of 1996, generally
provides that before a rule may take effect, the agency promulgating
the rule must submit a rule report, which includes a copy of the rule,
to each House of the Congress and to the Comptroller General of the
United States. EPA will submit a report containing this final rule and
other required information to the U.S. Senate, the U.S. House of
Representatives, and the Comptroller General of the United States prior
to publication of this final rule in the Federal Register. A major rule
cannot take effect until 60 days after it is published in the Federal
Register. This action is not a ``major rule'' as defined by 5 U.S.C.
804(2). This final rule will be effective on February 17, 2011.

List of Subjects

40 CFR Part 9

    Environmental protection, Reporting and recordkeeping requirements.

40 CFR Part 63

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

    Dated: December 16, 2010.
Lisa P. Jackson,
Administrator.

    For the reasons stated in the preamble, title 40, chapter I, of the
Code of Federal Regulations is amended as follows:

PART 9--[AMENDED]

0
1. The authority citation for part 9 continues to read as follows:

    Authority:  7 U.S.C. 135, et seq., 136-136y; 15 U.S.C. 2001,
2003, 2005, 2006, 2601-2671; 21 U.S.C. 331j, 346a, 348; 31 U.S.C.
9701; 33 U.S.C. 1251, et seq., 1311, 1313d, 1314, 1318, 1321, 1326,
1330, 1342, 1344, 1345(d) and (e), 1361; E.O. 11735, 38 FR 21243, 3
CFR, 1971-1975 Comp. p. 973; 42 U.S.C. 241, 242b, 243, 246, 300f,
300g, 300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-1, 300j-
2, 300j-3, 300j-4, 300j-9, 1857, et seq., 6901-6992k, 7401-7671q,
7542, 9601-9657, 11023, 11048.

Subpart A--[Amended]

* * * * *

0
2. The table in Sec.  9.1 is amended by adding an entry in numerical
order for ``63.11647-63.11648'' under the heading ``National Emission
Standards for Hazardous Air Pollutants for Source Categories'' to read
as follows:

Sec.  9.1  OMB Approvals under the Paperwork Reduction Act.

* * * * *

------------------------------------------------------------------------
                                                             OMB control
                      40 CFR citation                            No.
------------------------------------------------------------------------

                                * * * * *
------------------------------------------------------------------------
   National Emission Standards for Hazardous Air Pollutants for Source
                             Categories \3\
------------------------------------------------------------------------

                                * * * * *
------------------------------------------------------------------------
63.11647-63.11648..........................................     2060-NEW
------------------------------------------------------------------------

                                * * * * *
------------------------------------------------------------------------
 * * * * *
\3\ The ICRs referenced in this section of the table encompass the
  applicable general provisions contained in 40 CFR part 63, subpart A,
  which are not independent information collection requirements.

* * * * *

PART 63--[AMENDED]

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

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

Subpart A--[Amended]

0
4. Section 63.14 is amended by adding paragraph (b)(66), revising
paragraph (i)(1), and adding paragraph (k)(1)(v) to read as follows:

Sec.  63.14  Incorporation by reference.

* * * * *
    (b) * * *
    (66) ASTM D6784-02 (Reapproved 2008), Standard Test Method for
Elemental, Oxidized, Particle-Bound and Total Mercury in Flue Gas
Generated from Coal-Fired Stationary Sources (Ontario Hydro Method),

approved April 1, 2008, IBR approved for Sec.  63.11646(a)(1)(vi),
Sec.  63.11647(a)(1)(ii), Sec.  63.11647(a)(3)(ii), and Sec.
63.11647(d).
* * * * *
    (i) * * *
    (1) ANSI/ASME PTC 19.10-1981, Flue and Exhaust Gas Analyses [Part
10, Instruments and Apparatus], issued August 31, 1981 IBR approved for
Sec. Sec.  63.309(k)(1)(iii), 63.865(b), 63.3166(a)(3),
63.3360(e)(1)(iii), 63.3545(a)(3), 63.3555(a)(3), 63.4166(a)(3),
63.4362(a)(3), 63.4766(a)(3), 63.4965(a)(3), 63.5160(d)(1)(iii),
63.9307(c)(2), 63.9323(a)(3), 63.11148(e)(3)(iii), 63.11155(e)(3),
63.11162(f)(3)(iii) and (f)(4), 63.11163(g)(1)(iii) and (g)(2),
63.11410(j)(1)(iii), 63.11551(a)(2)(i)(C), 63.11646(a)(1)(iii), table 5
to subpart DDDDD of this part, and table 1 to subpart ZZZZZ of this
part.
* * * * *
    (k) * * *
    (1) * * *
    (v) SW-846 Method 74741B, Revision 2, ``Mercury in Solid or
Semisolid Waste (Manual Cold-Vapor Technique)'' February 2007, IBR
approved for Sec.  63.11647(f)(2).
* * * * *

0
5. Part 63 is amended by adding subpart EEEEEEE to read as follows:
Subpart EEEEEEE--National Emission Standards for Hazardous Air
Pollutants: Gold Mine Ore Processing and Production Area Source
Category

Applicability and Compliance Dates

Sec.
63.11640 Am I subject to this subpart?
63.11641 What are my compliance dates?

Standards and Compliance Requirements

63.11645 What are my mercury emission standards?
63.11646 What are my compliance requirements?
63.11647 What are my monitoring requirements?
63.11648 What are my notification, reporting, and recordkeeping
requirements?

Other Requirements and Information

63.11650 What General Provisions apply to this subpart?
63.11651 What definitions apply to this subpart?
63.11652 Who implements and enforces this subpart?
63.11653 [Reserved]

Tables to Subpart EEEEEEE of Part 63

Table 1 to Subpart EEEEEEE of Part 63--Applicability of General
Provisions to Subpart EEEEEEE

Subpart EEEEEEE--National Emission Standards for Hazardous Air
Pollutants: Gold Mine Ore Processing and Production Area Source
Category

Applicability and Compliance Dates

Sec.  63.11640  Am I subject to this subpart?

    (a) You are subject to this subpart if you own or operate a gold
mine ore processing and production facility as defined in Sec.
63.11651, that is an area source.
    (b) This subpart applies to each new or existing affected source.
The affected sources are each collection of ``ore pretreatment
processes'' at a gold mine ore processing and production facility, each
collection of ``carbon processes with mercury retorts'' at a gold mine
ore processing and production facility, each collection of ``carbon
processes without mercury retorts'' at a gold mine ore processing and
production facility, and each collection of ``non-carbon concentrate
processes'' at a gold mine ore processing and production facility, as
defined in Sec.  63.11651.
    (1) An affected source is existing if you commenced construction or
reconstruction of the affected source on or before April 28, 2010.
    (2) An affected source is new if you commenced construction or
reconstruction of the affected source after April 28, 2010.
    (c) This subpart does not apply to research and development
facilities, as defined in section 112(c)(7) of the Clean Air Act (CAA).
    (d) If you own or operate a source subject to this subpart, you
must have or you must obtain a permit under 40 CFR part 70 or 40 CFR
part 71.

Sec.  63.11641  What are my compliance dates?

    (a) If you own or operate an existing affected source, you must
comply with the applicable provisions of this subpart no later than
February 17, 2014.
    (b) If you own or operate a new affected source, and the initial
startup of your affected source is on or before February 17, 2011, you
must comply with the provisions of this subpart no later than February
17, 2011.
    (c) If you own or operate a new affected source, and the initial
startup of your affected source is after February 17, 2011, you must
comply with the provisions of this subpart upon startup of your
affected source.

Standards and Compliance Requirements

Sec.  63.11645  What are my mercury emission standards?

    (a) For existing ore pretreatment processes, you must emit no more
than 127 pounds of mercury per million tons of ore processed.
    (b) For existing carbon processes with mercury retorts, you must
emit no more than 2.2 pounds of mercury per ton of concentrate
processed.
    (c) For existing carbon processes without mercury retorts, you must
emit no more than 0.17 pounds of mercury per ton of concentrate
processed.
    (d) For existing non-carbon concentrate processes, you must emit no
more than 0.2 pounds of mercury per ton of concentrate processed.
    (e) For new ore pretreatment processes, you must emit no more than
84 pounds of mercury per million tons of ore processed.
    (f) For new carbon processes with mercury retorts, you must emit no
more than 0.8 pounds of mercury per ton of concentrate processed.
    (g) For new carbon processes without mercury retorts, you must emit
no more than 0.14 pounds of mercury per ton of concentrate processed.
    (h) For new non-carbon concentrate processes, you must emit no more
than 0.1 pounds of mercury per ton of concentrate processed.
    (i) The standards set forth in this section apply at all times.

Sec.  63.11646  What are my compliance requirements?

    (a) Except as provided in paragraph (b) of this section, you must
conduct a mercury compliance emission test within 180 days of the
compliance date for all process units at new and existing affected
sources according to the requirements in paragraphs (a)(1) through
(a)(13) of this section. This compliance testing must be repeated
annually thereafter, with no two consecutive annual compliance tests
occurring less than 3 months apart or more than 15 months apart.
    (1) You must determine the concentration of mercury and the
volumetric flow rate of the stack gas according to the following test
methods and procedures:
    (i) Method 1 or 1A (40 CFR part 60, appendix A-1) to select
sampling port locations and the number of traverse points in each stack
or duct. Sampling sites must be located at the outlet of the control
device (or at the outlet of the emissions source if no control device
is present) and prior to any releases to the atmosphere.
    (ii) Method 2, 2A, 2C, 2D, 2F (40 CFR part 60, appendix A-1), or
Method 2G (40 CFR part 60, appendix A-2) to determine the volumetric
flow rate of the stack gas.
    (iii) Method 3, 3A, or 3B (40 CFR part 60, appendix A-2) to
determine the dry

molecular weight of the stack gas. You may use ANSI/ASME PTC 19.10,
``Flue and Exhaust Gas Analyses'' (incorporated by reference-see Sec.
63.14) as an alternative to EPA Method 3B.
    (iv) Method 4 (40 CFR part 60, appendix A-3) to determine the
moisture content of the stack gas.
    (v) Method 29 (40 CFR part 60, appendix A-8) to determine the
concentration of mercury, except as provided in paragraphs (a)(1)(vi)
and (vii) of this section.
    (vi) Upon approval by the permitting authority, ASTM D6784;
``Standard Test Method for Elemental, Oxidized, Particle-Bound and
Total Mercury in Flue Gas Generated from Coal-Fired Stationary Sources
(Ontario Hydro Method)'' (incorporated by reference--see Sec.  63.14)
may be used as an alternative to Method 29 to determine the
concentration of mercury.
    (vii) Upon approval by the permitting authority, Method 30B (40 CFR
part 60, appendix A-8) may be used as an alternative to Method 29 to
determine the concentration of mercury for those process units with
relatively low particulate-bound mercury as specified in Section 1.2 of
Method 30B.
    (2) A minimum of three test runs must be conducted for each
performance test of each process unit. Each test run conducted with
Method 29 must collect a minimum sample volume of 0.85 dry standard
cubic meters (30 dry standard cubic feet). If conducted with Method 30B
or ASTM D6784, determine sample time and volume according to the
testing criteria set forth in the relevant method. If the emission
testing results for any of the emission points yields a non-detect
value, then the minimum detection limit (MDL) must be used to calculate
the mass emissions rate (lb/hr) used to calculate the emissions factor
(lb/ton) for that emission point and, in turn, for calculating the sum
of the emissions (in units of pounds of mercury per ton of concentrate,
or pounds of mercury per million tons of ore) for all emission points
subject to the emission standard for determining compliance. If the
resulting mercury emissions are greater than the MACT emission
standard, the owner or operator may use procedures that produce lower
MDL results and repeat the mercury emissions testing one additional
time for any emission point for which the measured result was below the
MDL. If this additional testing is performed, the results from that
testing must be used to determine compliance (i.e., there are no
additional opportunities allowed to lower the MDL).
    (3) Performance tests shall be conducted under such conditions as
the Administrator specifies to the owner or operator based on
representative performance of the affected source for the period being
tested. Upon request, the owner or operator shall make available to the
Administrator such records as may be necessary to determine the
conditions of performance tests. Performance tests must be conducted
under operating conditions (including process or production
throughputs) that are based on representative performance. Record and
report to the permit authority the process throughput for each test
run. For sources with multiple emission units (e.g., two roasters, or a
furnace, electrowinning circuit and a mercury retort) ducted to a
common control device and stack, compliance testing must be performed
either by conducting a single compliance test with all affected
emissions units in operation or by conducting a separate compliance
test on each emissions unit. Alternatively, the owner or operator may
request approval from the permit authority for an alternative testing
approach. If the units are tested separately, any emissions unit that
is not tested initially must be tested as soon as is practicable. If
the performance test is conducted when all affected units are
operating, then the number of hours of operation used for calculating
emissions pursuant to paragraphs (a)(6) and (7) of this section must be
the total number of hours for the unit that has the greatest total
operating hours for that period of time, or based on an appropriate
alternative method approved by the permit authority to account for the
hours of operation for each separate unit in these calculations.
    (4) Calculate the mercury emission rate (lb/hr), based on the
average of 3 test run values, for each process unit (or combination of
units that are ducted to a common stack and are tested when all
affected sources are operating pursuant to paragraph (a)(3) of this
section) using Equation (1) of this section:
[GRAPHIC] [TIFF OMITTED] TR17FE11.003

Where:

E = mercury emissions in lb/hr;
Cs = concentration of mercury in the stack gas, in grains per dry
standard cubic foot (gr/dscf);
Qs = volumetric flow rate of the stack gas, in dry standard cubic
feet per hour; and
K = conversion factor for grains (gr) to pounds (lb), 1.43 x
10-4.

    (5) Monitor and record the number of one-hour periods each process
unit operates during each month.
    (6) For the initial compliance determination for both new and
existing sources, determine the total mercury emissions for all the
full calendar months between the compliance date and the date of the
initial compliance test by multiplying the emission rate in lb/hr for
each process unit (or combination of units ducted to a common stack
that are tested together) by the number of one-hour periods each
process unit (or the unit that had the greatest total operating hours
among the combination of multiple units with one stack that are tested
together, or an alternative method approved by the permit authority,
pursuant to paragraph (a)(3) of this section) operated during those
full calendar months prior to the initial compliance test. This initial
period must include at least 1 full month of operations. After the
initial compliance test, for subsequent compliance tests, determine the
mercury mass emissions for the 12 full calendar months prior to the
compliance test in accordance with the procedures in paragraph (a)(7)
of this section. Existing sources may use a previous emission test for
their initial compliance determination in lieu of conducting a new test
if the test was conducted within one year of the compliance date using
the methods specified in paragraphs (a)(1) through (a)(4) of this
section, and the tests were representative of current operating
processes and conditions. If a previous test is used for their initial
compliance determination, 3 to 12 full months of data on hours of
operation and production (i.e., million tons of ore or tons of
concentrate), including the month the test was conducted, must be used
to calculate the emissions rate (in units of pounds of mercury per
million tons of ore for the ore pretreatment affected sources, or in
units of pounds of mercury per tons of concentrate for the other
affected sources).
    (7) For compliance determinations following the initial compliance
test for new and existing sources, determine the total mercury mass
emissions for each process unit for the 12 full calendar

months preceding the performance test by multiplying the emission rate
in lb/hr for each process unit (or combination of units ducted to a
common stack that are tested together) by the number of one-hour
periods each process unit (or the unit that had the greatest total
operating hours among the combination of multiple units with one stack
that are tested together, or an alternative method approved by the
permit authority, pursuant to paragraph (a)(3) of this section)
operated during the 12 full calendar months preceding the completion of
the performance tests.
    (8) You must install, calibrate, maintain and operate an
appropriate weight measurement device, mass flow meter, or densitometer
and volumetric flow meter to measure ore throughput for each roasting
operation and autoclave and calculate hourly, daily and monthly totals
in tons of ore according to paragraphs (a)(8)(i) and (a)(8)(ii) of this
section.
    (i) Measure the weight or the density and volumetric flow rate of
the oxidized ore slurry as it exits the roaster oxidation circuit(s)
and before the carbon-in-leach tanks. Alternatively, the weight of the
ore can be measured ``as fed'' if approved by the permit authority as
an acceptable equivalent method to measure amount of ore processed.
    (ii) Measure the weight or the density and volumetric flow rate of
the ore slurry as it is fed to the autoclave(s). Alternatively, the
weight or the density and volumetric flow rate of the oxidized ore
slurry can be measured as it exits the autoclave and before the carbon-
in-leach tanks if approved by the permit authority as an acceptable
equivalent method to measure amount of ore processed.
    (9) Measure the weight of concentrate (produced by electrowinning,
Merrill Crowe process, gravity feed, or other methods) using weigh
scales for each batch prior to processing in mercury retorts or melt
furnaces. For facilities with mercury retorts, the concentrate must be
weighed in the same state and condition as it is when fed to the
mercury retort. For facilities without mercury retorts, the concentrate
must be weighed prior to being fed to the melt furnace before drying in
any ovens. For facilities that ship concentrate offsite, measure the
weight of concentrate as shipped offsite. You must keep accurate
records of the weights of each batch of concentrate processed and
calculate, and record the total weight of concentrate processed each
month.
    (10) You must maintain the systems for measuring density,
volumetric flow rate, and weight within  5 percent
accuracy. You must describe the specific equipment used to make
measurements at your facility and how that equipment is periodically
calibrated. You must also explain, document, and maintain written
procedures for determining the accuracy of the measurements and make
these written procedures available to your permitting authority upon
request. You must determine, record, and maintain a record of the
accuracy of the measuring systems before the beginning of your initial
compliance test and during each subsequent quarter of affected source
operation.
    (11) Record the weight in tons of ore for ore pretreatment
processes and concentrate for carbon processes with mercury retorts,
carbon processes without mercury retorts, and for non-carbon
concentrate processes on a daily and monthly basis.
    (12) Calculate the emissions from each new and existing affected
source for the sum of all full months between the compliance date and
the date of the initial compliance test in pounds of mercury per ton of
process input using the procedures in paragraphs (a)(12)(i) through
(a)(12)(iv) of this section to determine initial compliance with the
emission standards in Sec.  63.11645. This must include at least 1 full
month of data. Or, if a previous test is used pursuant to paragraph
(a)(6) of this section for the initial compliance test, use a period of
time pursuant to paragraph (a)(6) of this section to calculate the
emissions for the affected source. After this initial compliance test
period, determine annual compliance using the procedures in paragraph
(a)(13) of this section for existing sources.
    (i) For ore pretreatment processes, divide the sum of mercury mass
emissions (in pounds) from all roasting operations and autoclaves
during the number of full months between the compliance date and the
initial compliance test by the sum of the total amount of gold mine ore
processed (in million tons) in these process units during those same
full months following the compliance date. Or, if a previous test is
used to determine initial compliance, pursuant to paragraph (a)(6) of
this section, then the same 3 to 12 full months of production data
(i.e., million tons of ore) and hours of operation referred to in
paragraph (a)(6) of this section, must be used to determine the
emissions in pounds of mercury per million tons of ore.
    (ii) For carbon processes with mercury retorts, divide the sum of
mercury mass emissions (in pounds) from all carbon kilns, preg tanks,
electrowinning, mercury retorts, and melt furnaces during the initial
number of full months between the compliance date and the initial
compliance tests by the total amount of concentrate (in tons) processed
in these process units during those same full months following the
compliance date. If a previous test is used to determine initial
compliance, pursuant to paragraph (a)(6) of this section, then the same
3 to 12 full months of production data (i.e., tons of concentrate) and
hours of operation referred to in paragraph (a)(6) of this section,
must be used to determine the emissions in pounds of mercury per tons
of concentrate.
    (iii) For carbon processes without mercury retorts, divide the sum
of mercury mass emissions (in pounds) from all carbon kilns, preg
tanks, electrowinning, and melt furnaces during the initial number of
full months between the compliance date and the initial compliance
tests by the total amount of concentrate (in tons) processed in these
process units during those same full months following the compliance
date. If a previous test is used to determine initial compliance,
pursuant to paragraph (a)(6) of this section, then the same 3 to 12
full months of production data (i.e., tons of concentrate) and hours of
operation referred to in paragraph (a)(6) of this section, must be used
to determine the emissions in pounds of mercury per tons of
concentrate.
    (iv) For non-carbon concentrate processes, divide the sum of
mercury mass emissions (in pounds) from mercury retorts and melt
furnaces during the initial number of full months between the
compliance date and the initial compliance tests by the total amount of
concentrate (in tons) processed in these process units during those
same full months following the compliance date. If a previous test is
used to determine initial compliance, pursuant to paragraph (a)(6) of
this section, then the same 3 to 12 full months of production data
(i.e., tons of concentrate) and hours of operation referred to in
paragraph (a)(6) of this section, must be used to determine the
emissions in pounds of mercury per tons of concentrate.
    (13) After the initial compliance test, calculate the emissions
from each new and existing affected source for each 12-month period
preceding each subsequent compliance test in pounds of mercury per ton
of process input using the procedures in paragraphs (a)(13)(i) through
(iv) of this section to determine compliance with the emission
standards in Sec.  63.11645.
    (i) For ore pretreatment processes, divide the sum of mercury mass

emissions (in pounds) from all roasting operations and autoclaves in
the 12-month period preceding a compliance test by the sum of the total
amount of gold mine ore processed (in million tons) in that 12-month
period.
    (ii) For carbon processes with mercury retorts, divide the sum of
mercury mass emissions (in pounds) from all carbon kilns, preg tanks,
electrowinning, mercury retorts, and melt furnaces in the 12-month
period preceding a compliance test by the total amount of concentrate
(in tons) processed in these process units in that 12-month period.
    (iii) For carbon processes without mercury retorts, divide the sum
of mercury mass emissions (in pounds) from all carbon kilns, preg
tanks, electrowinning, and melt furnaces in the 12-month period
preceding a compliance test by the total amount of concentrate (in
tons) processed in these process units in that 12-month period.
    (iv) For non-carbon concentrate processes, divide the sum of
mercury mass emissions (in pounds) from mercury retorts and melt
furnaces in the 12-month period preceding a compliance test by the
total amount of concentrate (in tons) processed in these process units
in that 12-month period.
    (b) At all times, you must operate and maintain any affected
source, including associated air pollution control equipment and
monitoring equipment, in a manner consistent with safety and good air
pollution control practices for minimizing emissions. Determination of
whether such operation and maintenance procedures are being used will
be based on information available to the Administrator which may
include, but is not limited to, monitoring results, review of operation
and maintenance procedures, review of operation and maintenance
records, and inspection of the source.

Sec.  63.11647  What are my monitoring requirements?

    (a) Except as provided in paragraph (a)(5) of this section, you
must monitor each roaster for mercury emissions using one of the
procedures in paragraphs (a)(1), (a)(2), or (a)(3) of this section and
establish operating limits for mercury concentration as described in
paragraph (a)(4) of this section.
    (1) Perform sampling and analysis of the roaster's exhaust for
mercury concentration using EPA Performance Specification 12B (40 CFR
part 60, appendix B and Procedure 5 of appendix F) or EPA Method 30B
(40 CFR part 60, appendix A-8) at least twice per month. A minimum of
two measurements must be taken per month that are at least 11 days
apart from other consecutive tests. The mercury concentration must be
maintained below the operating limit established in paragraph (a)(4) of
this section. The results of the sampling must be obtained within 72
hours of the time the sample is taken.
    (i) To determine the appropriate sampling duration, you must review
the available data from previous stack tests to determine the upper
99th percentile of the range of mercury concentrations in the exit
stack gas. Based on this upper end of expected concentrations, select
an appropriate sampling duration that is likely to provide a valid
sample and not result in breakthrough of the sampling tubes. If
breakthrough of the sampling tubes occurs, you must re-sample within 7
days using a shorter sampling duration.
    (ii) If any mercury concentration measurement from the twice per
month sampling with PS 12B or Method 30B is higher than the operating
limit, the exceedance must be reported to the permit authority as a
deviation and corrective actions must be implemented within 48 hours
upon receipt of the sampling results. Moreover, within 96 hours of the
exceedance, the owner or operator must measure the concentration again
(with PS 12B (40 CFR part 60, appendix B and Procedure 5 of appendix
F), Method 30B or Method 29 (40 CFR part 60, appendix A-8), or ASTM
D6784(incorporated by reference--see Sec.  63.14)) and demonstrate to
the permit authority that the mercury concentration is no higher than
the operating limit, or inform the permit authority that the limit
continues to be exceeded. If the measured mercury concentration exceeds
the operating limit for mercury concentration after these 96 hours, the
exceedance must be reported as a deviation within 24 hours to the
permitting authority. The owner or operator must conduct a full
compliance test pursuant to Sec.  63.11646(a) for the roaster
operations within 40 days to determine if the affected source is in
compliance with the MACT emission standard. For facilities that have
roasters and autoclaves, the owner or operator can use the results of
the previous compliance test for the autoclaves to determine the
emissions for those process units to be used in the calculations of the
emissions for the affected source. If the source is determined to be in
compliance, the compliance test may also be used to establish a new
operating limit for mercury concentration (in accordance with paragraph
(e) of this section).
    (2) Install, operate, calibrate, and maintain a continuous