Document ID: EPA-HQ-OAR-2010-0239-0361
Agency: epa
Document Type: Rule
Title: National Emission Standards for Hazardous Air Pollutants: Gold Mine Ore Processing and Production Area Source Category; and Addition to Source Category List for Standards
Posted Date: 2011-02-17T05:00Z

[Federal Register Volume 76, Number 33 (Thursday, February 17, 2011)]
[Rules and Regulations]
[Pages 9450-9489]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-2608]

[[Page 9449]]

Vol. 76

Thursday,

No. 33

February 17, 2011

Part III

Environmental Protection Agency

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40 CFR Parts 9 and 63

National Emission Standards for Hazardous Air Pollutants: Gold Mine Ore 
Processing and Production Area Source Category; and Addition to Source 
Category List for Standards; Final Rule

  Federal Register / Vol. 76 , No. 33 / Thursday, February 17, 2011 / 
Rules and Regulations  

[[Page 9450]]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 9 and 63

[EPA-HQ-OAR-2010-0239; FRL-9242-3]
RIN 2060-AP48

National Emission Standards for Hazardous Air Pollutants: Gold 
Mine Ore Processing and Production Area Source Category; and Addition 
to Source Category List for Standards

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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

SUMMARY: EPA is adding the gold mine ore processing and production area 
source category to the list of source categories to be regulated under 
Section 112(c)(6) of the Clean Air Act due to its mercury emissions. 
EPA is also promulgating national emission standards for hazardous air 
pollutants to regulate mercury emissions from this source category.

DATES: This final rule is effective on February 17, 2011. The 
incorporation by reference of certain publications listed in the final 
rule is approved by the Director of the Federal Register as of February 
17, 2011.

ADDRESSES: EPA has established a docket for this action under Docket ID 
No. EPA-HQ-OAR-2010-0239. All documents in the docket are listed on the 
http://www.regulations.gov Web site. Although listed in the index, some 
information is not publicly available, e.g., Confidential Business 
Information (CBI) or other information whose disclosure is restricted 
by statute. Certain other material, such as copyrighted material, is 
not placed on the Internet and will be publicly available only in hard 
copy form. Publicly available docket materials are available either 
electronically through www.regulations.gov or in hard copy at the EPA 
Headquarters Library, Room Number 3334, EPA West Building, 1301 
Constitution Ave., NW., Washington, DC. The EPA/DC Public Reading Room 
hours of operation are 8:30 a.m. to 4:30 p.m. Eastern Standard Time 
(EST), Monday through Friday. The telephone number for the Public 
Reading Room is (202) 566-1744, and the telephone number for the Air 
and Radiation Docket and Information Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Mr. Chuck French, Sector Policies and 
Program Division, Office of Air Quality Planning and Standards (D243-
02), Environmental Protection Agency, Research Triangle Park, North 
Carolina 27711, telephone number (919) 541-7912; fax number (919) 541-
3207, e-mail address: french.chuck@epa.gov.

SUPPLEMENTARY INFORMATION: The information presented in this preamble 
is organized as follows:

I. General Information
    A. Does this action apply to me?
    B. Where can I get a copy of this document?
    C. Judicial Review
II. Addition to Section 112(c)(6) Source Category List
III. What is the statutory authority and regulatory approach for the 
proposed standards?
IV. Summary of Significant Changes Since Proposal
    A. Applicability
    B. Final Emission Standards
    C. Compliance Dates
    D. Compliance Requirements
    E. Monitoring Requirements
    F. Definitions
V. Summary of Responses to Major Comments
    A. Statutory Requirements
    B. Applicability
    C. MACT Floors
    D. Compliance Determinations
    E. Monitoring Requirements
    F. Definitions
VI. Summary of Environmental, Economic and Health Benefits
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children From 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions To Address 
Environmental Justice in Minority Populations and Low-Income 
Populations
    K. Congressional Review Act

I. General Information

A. Does this action apply to me?

    The regulated categories and entities potentially affected by this 
final rule include:

------------------------------------------------------------------------
                                                         Examples of
             Category               NAICS code \1\   regulated entities
------------------------------------------------------------------------
Industry:
    Gold Ore Mining..............           212221  Establishments
                                                     primarily engaged
                                                     in developing the
                                                     mine site, mining,
                                                     and/or
                                                     beneficiating
                                                     (i.e., preparing)
                                                     ores valued chiefly
                                                     for their gold
                                                     content.
                                                     Establishments
                                                     primarily engaged
                                                     in transformation
                                                     of the gold into
                                                     bullion or dore bar
                                                     in combination with
                                                     mining activities
                                                     are included in
                                                     this industry.
------------------------------------------------------------------------
\1\ North American Industry Classification System.

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be affected by this 
action. To determine whether your facility would be regulated by this 
action, you should examine the applicability criteria in 40 CFR 
63.11640 of subpart EEEEEEE (National Emission Standards for Hazardous 
Air Pollutants (NESHAP): Gold Mine Ore Processing and Production Area 
Source Category). If you have any questions regarding the applicability 
of this action to a particular entity, consult either the air permit 
authority for the entity or your EPA Regional representative, as listed 
in 40 CFR 63.13 of subpart A (General Provisions).

B. Where can I get a copy of this document?

    In addition to being available in the docket, an electronic copy of 
this final action will also be available on the Worldwide Web (WWW) 
through the EPA Technology Transfer Network (TTN). Following signature, 
a copy of this final action will be posted on the TTN's policy and 
guidance page for newly proposed or promulgated rules at the following 
address: http://www.epa.gov/ttn/oarpg/. The TTN provides information 
and technology exchange in various areas of air pollution control.

C. Judicial Review

    Under Section 307(b)(1) of the Clean Air Act (CAA), judicial review 
of this final rule is available only by filing a petition for review in 
the U.S. Court of

[[Page 9451]]

Appeals for the District of Columbia Circuit by April 18, 2011. Under 
section 307(d)(7)(B) of the CAA, only an objection to this final rule 
that was raised with reasonable specificity during the period for 
public comment can be raised during judicial review. Moreover, under 
section 307(b)(2) of the CAA, the requirements established by this 
final rule may not be challenged separately in any civil or criminal 
proceedings brought by EPA to enforce these requirements.
    Section 307(d)(7)(B) also provides a mechanism for us to convene a 
proceeding for reconsideration, ``[i]f the person raising an objection 
can demonstrate to EPA that it was impracticable to raise such 
objection within [the period for public comment] or if the grounds for 
such objection arose after the period for public comment (but within 
the time specified for judicial review) and if such objection is of 
central relevance to the outcome of the rule.'' Any person seeking to 
make such a demonstration to us should submit a Petition for 
Reconsideration to the Office of the Administrator, U.S. EPA, Room 
3000, Ariel Rios Building, 1200 Pennsylvania Ave., NW., Washington, DC 
20460, with a copy to the person listed in the preceding FOR FURTHER 
INFORMATION CONTACT section.

II. Addition to Section 112(c)(6) Source Category List

    For reasons stated in the preamble to the proposed rule (75 FR 
22470, April 28, 2010), we are adding the gold mine ore processing and 
production area source category to the list of source categories under 
section 112(c)(6) on the basis of its mercury emissions. The preamble 
for the proposed rule provides a description of this industry including 
the processes used and the typical control technologies applied.

III. What is the statutory authority and regulatory approach for the 
proposed standards?

    As explained in the preamble to the proposed rule, CAA section 
112(c)(6) requires that EPA set standards under section 112(d)(2) or 
(d)(4). The mercury standards for the gold mine ore processing and 
production area source category are being established under CAA section 
112(d)(2), which requires maximum available control technology (MACT) 
level of control. Under CAA section 112(d), the MACT standards for 
existing sources must be at least as stringent as the average emissions 
limitation achieved by the best performing 12 percent of existing 
sources (for which the administrator has emissions information) for 
source categories and subcategories with 30 or more sources, or the 
best performing 5 sources for categories and subcategories with fewer 
than 30 sources (CAA section 112(d)(3)(A) and (B)). This level of 
minimum stringency is called the MACT floor. For new sources, MACT 
standards must be at least as stringent as the emission control that is 
achieved in practice by the best controlled similar source (CAA section 
112(d)(3)). EPA also must consider more stringent ``beyond-the-floor'' 
control options. When considering beyond-the-floor options, EPA must 
consider not only the maximum degree of reduction in emissions of HAP, 
but must take into account costs, energy, and nonair quality health and 
environmental impacts when doing so.

IV. Summary of Significant Changes Since Proposal

    This section summarizes the significant changes to the rule since 
proposal. Additional information on the basis for these changes and 
other changes can be found in the Summary of Responses to Major 
Comments in section V of this preamble and in the Summary of Comments 
and Responses document which is available in the docket for this 
action.

A. Applicability

    We have clarified in Sec.  63.11651 of the final rule that the term 
``gold mine ore processing and production facility'' does not include 
individual prospectors and very small pilot scale mining operations. 
These types of operations are very small and were not included in the 
section 112(c)(6) inventory that was the basis for the listing of the 
gold mine ore processing and production source category.

B. Final Emission Standards

    We have made changes to all of the proposed emission standards as 
the result of the following developments: (1) Inclusion of additional 
emissions test data received since proposal; \1\ (2) additional 
analyses in response to public comments on the proposed rule; \2\ and 
(3) further review of the data used to develop the standards for the 
proposed rule. The changes are summarized below and described in more 
detail in section V of this preamble. We estimate the final MACT 
standards will reduce mercury emissions from gold mine ore processing 
and production down to a level of about 1,180 pounds per year, which 
will be an estimated 77 percent reduction from the 2007 emissions level 
(5,000 lb/yr), a 95 percent reduction from year 2001 emissions level 
(about 23,000 lb/yr), and more than 97 percent reduction from 
uncontrolled emissions levels (more than 37,000 lb/yr).
---------------------------------------------------------------------------

    \1\ The new test data used in final MACT standard calculations 
can be found in the docket as docket items: EPA-HQ-OAR-2010-0239-
0359 and EPA-HQ-OAR-2010-0239-0360.
    \2\ Analyses for the final MACT standards can be found in the 
docket in the document titled: ``Development of the MACT Floors and 
MACT for the Final NESHAP for Gold Mine Ore Processing and 
Production'' (also known as the ``MACT Development Document'').
---------------------------------------------------------------------------

Ore Pretreatment Processes
    In the proposed rule, the proposed mercury emission standards for 
both existing and new ore pretreatment processes were 149 pounds per 
million tons of ore processed (lb/million tons of ore). In the final 
rule, the emission standard for existing sources is 127 lb/million tons 
of ore; and for new sources the emission standard is 84 lb/million tons 
of ore. The final emission standards are based on several changes to 
the data set used in the MACT analysis. Since we issued the proposed 
rule, we collected emissions data from more recent tests that were not 
available at proposal. Further, we learned that two emissions tests 
that we used to develop the MACT floor in our proposed rule had been 
invalidated by the Nevada Division of Environmental Protection (NDEP), 
and we removed those test results from the database. Information on the 
specific tests invalidated and the rationale are available in the 
docket (docket item number EPA-HQ-OAR-2010-0239-0061). We also 
discovered that the test data for a unit within the ore pretreatment 
affected source at a facility should have been included as part of a 
different unit at the same facility. We have also dropped the data for 
one facility from the analysis because their autoclave was shut down in 
2007 and dismantled, and the only test data we had for them was one 
test of the autoclave when it was operating in 2006. Moreover, we 
conducted additional beyond-the-floor analyses for the ore pretreatment 
affected source. The new information and analyses described above are 
discussed in more detail in section V.C of this preamble and in the 
MACT Development Document which is available in the docket for this 
rulemaking.
    The resulting data set included emissions data for four facilities 
that ranged from 45 to 165 lb/million tons of ore. Based on these data, 
and using the same upper prediction limit (UPL) approach used for 
proposal to account for variability, we determined the MACT floor to be 
158 lb/million tons of ore for existing sources of ore pretreatment 
processes and 84 lb/

[[Page 9452]]

million tons of ore for new sources. As explained in the proposed rule 
(75 FR at 22482), the technologies that we estimate are needed to 
achieve the MACT floor level of performance for existing ore 
pretreatment processes include calomel-based mercury scrubbers on 
roasters and venturi scrubbers on autoclaves and ancillary roaster 
operations. The preamble to the proposed rule provides a description of 
the UPL and the approach and calculations used to derive the UPL. The 
UPL is also discussed further in section V.
    In our beyond-the-floor analysis, we evaluated the potential to add 
condensers and carbon adsorbers to control autoclaves, and the 
potential to add carbon adsorbers to control the ore pre-heaters. Based 
on this beyond-the-floor analysis, we concluded that it is feasible and 
cost-effective to establish the MACT standard for existing sources at a 
level lower than the MACT floor. Based on the analysis, we determined 
the MACT standard for existing sources to be 127 lb/million tons of 
ore. For new sources, we determined that it was not feasible and cost-
effective to establish a standard lower than the new source MACT Floor 
(of 84 lb/million tons); therefore the MACT standard for new sources 
was determined to be 84 lb/million tons.
    The technologies needed to achieve the new source MACT floor will 
depend on the types of ore processed, amount of mercury in the ore, and 
specific process units used. Nevertheless, we conclude that, at a 
minimum, the controls that would be needed would include calomel-based 
mercury scrubbers on roasters and venturi scrubbers on autoclaves and 
ancillary roaster operations. Additional controls that will likely be 
needed to achieve emissions at or below the new source MACT floor level 
include condensers and carbon adsorbers on autoclaves, and carbon 
adsorbers on ore preheaters.
    Table 1 summarizes the MACT floor analysis for existing and new ore 
pretreatment processes. The beyond-the-floor analyses are explained 
further in section V of this preamble and in more detail in the MACT 
Development document.

       Table 1--MACT Floor Results for Ore Pretreatment Processes
------------------------------------------------------------------------
                                                               Average
                                                             performance
                         Facility                            (lb/million
                                                            tons of ore)
------------------------------------------------------------------------
A.........................................................            45
C.........................................................            56
E.........................................................            71
D.........................................................           165
Average of the 4 facilities...............................            84
99% UPL for existing sources (i.e., the MACT Floor for               158
 existing sources)........................................
99% UPL for new sources \1\ (i.e., the MACT Floor for new             84
 sources).................................................
------------------------------------------------------------------------
\1\ The MACT Floor for new sources is based on the average performance
  of Facility A (i.e., 45) plus an amount to account for variability
  (i.e., 45 + 39 = 84).

Carbon Processes
    Under the proposed rule, all carbon processes were subject to the 
same proposed mercury emissions limits of 2.6 pounds per ton of 
concentrate (lb/ton of concentrate) for existing sources and, for new 
sources, either 0.14 lb/ton of concentrate or 97 percent reduction in 
uncontrolled mercury emissions. These limits would have applied to 
facilities that operate mercury retorts and facilities that do not 
operate mercury retorts. In the final rule, we distinguish between 
carbon processes with mercury retorts and carbon processes without 
mercury retorts because we believe there are unique differences in 
these two types of processes. Therefore, the final rule specifies 
separate emission standards for these two types of processes. Moreover, 
the final emission standards for carbon processes reflect inclusion of 
new test data that were not available at proposal. We also revised our 
data set based on new information that we received since proposal which 
impacted which sources were among the best performing sources. Based on 
the data that we have, there are 10 facilities that have carbon 
processes with mercury retorts, and we have mercury emissions data for 
all 10 of these facilities. There are approximately 7 facilities that 
have carbon processes without mercury retorts, and we have 
comprehensive and reliable mercury emissions data for 2 of these 
facilities. These 2 facilities are the best controlled facilities 
within that group based on the information we have. (See section V for 
further details.) For carbon processes with mercury retorts, the 
emission standard in the final rule is 2.2 lb/ton of concentrate for 
existing sources and 0.8 lb/ton of concentrate for new sources. For 
carbon processes without mercury retorts, the emission standard in the 
final rule is 0.17 lb/ton of concentrate for existing sources and 0.14 
lb/ton of concentrate for new sources.
    For carbon processes, regardless of whether the facility operates a 
mercury retort, we estimate that to meet the MACT floor facilities 
would generally need to have mercury condensers and carbon adsorbers to 
control mercury emissions. We also considered beyond-the-floor options 
for both existing and new sources for these process groups, which were 
based on the addition of a second carbon adsorber; however, we rejected 
those options because they are not cost effective. Additional 
information on the analyses performed can be found in the MACT 
Development document in the docket for this rulemaking.
    We also eliminated in the final rule the compliance alternative of 
97 percent reduction for new carbon processes. After reviewing the 
comments received on this proposed alternative 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 to the proposed new source limit of 0.14 pounds of 
mercury per ton of concentrate. For the reasons stated above, we 
eliminated the 97 percent control efficiency option for new carbon 
processes in the final rule.
    Table 2 summarizes the results of the MACT floor analysis for 
carbon processes with mercury retorts, and Table 3 summarizes the 
analysis for carbon processes without mercury retorts.

  Table 2--MACT Floor Results for Carbon Processes With Mercury Retorts
------------------------------------------------------------------------
                                                              Average
                                                            performance
                         Facility                            (lb/ton of
                                                            concentrate)
------------------------------------------------------------------------
N........................................................           0.53
J........................................................           0.74
I........................................................           1.06
A........................................................           1.47
H........................................................           1.67
D........................................................           2.20
C........................................................           3.71
G........................................................           8.17
E........................................................          14.49
B........................................................          20.60

[[Page 9453]]

 
Average of top 5.........................................           1.1
99% UPL for existing sources (i.e., MACT Floor for                  2.2
 existing sources).......................................
99% UPL for new sources (i.e., MACT Floor for new                   0.8
 sources)................................................
------------------------------------------------------------------------

Table 3--MACT Floor Results for Carbon Processes Without Mercury Retorts
------------------------------------------------------------------------
                                                              Average
                                                            performance
                         Facility                            (lb/ton of
                                                            concentrate)
------------------------------------------------------------------------
M........................................................          0.058
F........................................................          0.098
Average of top 2 facilities..............................          0.078
99% UPL for existing sources (i.e., MACT Floor for                 0.17
 existing sources).......................................
99% UPL for new sources (i.e., MACT Floor for new                  0.14
 sources)................................................
------------------------------------------------------------------------

Non-Carbon Concentrate Processes
    Under the proposed rule, the mercury emission standards for non-
carbon concentrate processes were 0.25 lb/ton of concentrate for 
existing sources and 0.2 lb/ton of concentrate for new sources. In the 
final rule, the emission standards for these sources are 0.2 lb/ton of 
concentrate for existing sources and 0.1 lb/ton of concentrate for new 
sources. These standards are based on using new emissions data that 
were not available when we developed the proposal, along with the data 
that were used for the proposal. For non-carbon concentrate processes, 
we estimate that to meet the MACT floors, for both existing and new 
sources, facilities would generally need to control mercury emissions 
using mercury condensers and carbon adsorbers. As explained in the 
proposed rule, we considered beyond-the-floor controls for these 
processes (which were based on adding a second carbon adsorber to the 
MACT floor level controls) but concluded those controls would not be a 
cost-effective option. There are approximately 3 facilities in the U.S. 
that use these types of processes. We have emissions tests data for 2 
of these facilities.
    Table 4 summarizes the results of the MACT floor analysis for non-
carbon concentrate processes.

    Table 4--MACT Floor Results for Non-Carbon Concentrate Processes
------------------------------------------------------------------------
                                                              Average
                                                            performance
                         Facility                            (lb/ton of
                                                            concentrate)
------------------------------------------------------------------------
K........................................................          0.047
L........................................................          0.078
Average of 2 facilities..................................          0.062
99% UPL for existing sources (i.e., MACT Floor for                 0.2
 existing sources).......................................
99% UPL for new sources (i.e., MACT Floor for new                  0.1
 sources)................................................
------------------------------------------------------------------------

C. Compliance Dates

    In the final rule, we provide in Sec.  63.11641 that the compliance 
date for existing sources is 3 years after promulgation of the final 
rule as opposed to 2 years as proposed. We reviewed the information 
provided in public comments on the challenges of installing new 
controls, especially for autoclaves, which, although the controls have 
not yet been demonstrated, have been proposed by facilities with 
autoclaves in their Nevada Mercury Control Program (NMCP) permit 
applications. We also considered the installation of new controls on 
the roaster preheaters, which also have not yet been demonstrated, but 
have been proposed by these facilities in their NMCP permit 
applications. We concluded 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.

D. Compliance Requirements

    Section 63.11646(a)(1) of the final rule does not include Method 
30A, as was proposed, as an appropriate method for determining mercury 
concentration because it is not yet in general use. This paragraph 
further clarifies that the use of ASTM D6784-02 and Method 30B are 
allowed for compliance tests only if approved by the permit authority 
as opposed to automatically being allowed as in the proposal. The final 
rule also does not include the requirement to follow the acetone rinse 
procedures and the absence of cyclonic flow determination requirement, 
which were in subparagraphs (v) and (vi) respectively of our proposed 
Sec.  63.11646(a)(1). Method 29 already includes requirements for the 
acetone rinse, so there is no need to specify those procedures in the 
rule; and Method 1, which is required by the rule, addresses the issue 
of cyclonic flow.
    In Sec.  63.11646(a)(2), we changed the minimum sample volume when 
Method 29 is used to determine compliance from the proposed 60 dry 
standard cubic feet (dscf) to 30 dscf. We believe this volume is 
adequate for detecting mercury in the samples and determining mercury 
emissions for this industry. We have also expanded this section to 
address non-detect values. If the emission testing results for any of 
the emission points yield a non-detect value, the final rule requires 
that the minimum detection limit (MDL) be used to calculate the mass of 
emissions (in pounds of mercury) for that emission point that would 
subsequently be used in the calculations to determine if the source is 
in compliance with the MACT standard. If the resulting calculations 
indicate that mercury emissions are greater than the MACT emission 
standard, the owner or operator may repeat the mercury emissions 
testing one additional time for any emission point for which the 
measured result was below the MDL using procedures that produce lower 
MDL results. If this additional testing is performed, the results from 
that testing must be used to determine compliance.
    For sources with multiple emission units (e.g., two roasters) 
ducted to a common control device and stack, we have clarified in Sec.  
63.11646(a)(3) that compliance testing must either be performed with 
all affected emissions units in operation, if this is possible, or 
units must be tested separately. We also clarified that the 
establishment of operating limits for units that share a common stack 
can be based on emissions when all process units are operating 
together, or based on testing units separately. However, this 
requirement does not affect the frequency and schedule for monitoring, 
which are specified in the rule. If facilities have batch type 
processes that cannot be operated simultaneously, then the facility can 
test some or all of the units individually.
    In Sec.  63.11646(a)(6) and (7), we clarify that the production 
data used in compliance determinations are based on full calendar 
months. For the initial compliance test, data for all the full calendar 
months between publication of the final rule and the initial compliance 
test must be used. This initial compliance determination must include 
at least one full month of production

[[Page 9454]]

data (e.g., hours of operation, and million tons of ore processed or 
tons of concentrate processed) including the month the test was 
conducted. For subsequent annual compliance tests, data for the 12 full 
calendar months prior to the annual compliance test must be used to 
demonstrate compliance. In addition, we clarify in paragraphs Sec.  
63.11646(a)(5), (6) and (7) that compliance determinations are based on 
the number of 1-hour periods each process unit operates. By using the 
1-hour period terminology, the final rule language is consistent with 
the terminology used in the General Provisions to part 63.
    Because the final rule does not include the 97 percent reduction 
option that was in Sec.  63.11645(e)(2) of the proposed rule, we have 
removed from the final rule the compliance requirement for that option 
that was in Sec.  63.11646(b) of the proposed rule, which addressed 
testing the inlets and outlets for sources choosing that proposed 
option.

E. Monitoring Requirements

    Section 63.11647(a) of the final rule includes an additional option 
for monitoring mercury emissions from roasters. The proposed rule 
specified two options for monitoring mercury emissions: Paragraph 
(a)(1) specified weekly sampling using PS 12B; and paragraph (a)(2) 
specified continuous monitoring using a mercury continuous emissions 
monitoring system (CEMS). In the final rule, we added paragraph (a)(3) 
to provide a third option of continuous sampling using PS 12B. In 
addition, paragraph (a)(1) in the final rule was changed to require 
sampling at least twice per month using either PS 12B or Method 30B 
rather than weekly. We believe that Method 30B is an acceptable 
alternative method for monitoring purposes and allows owners and 
operators more flexibility in how they monitor roaster emissions. We 
also believe that sampling twice per month coupled with extensive 
parametric monitoring of control devices (as explained below) is 
sufficient for the monitoring option in paragraph (a)(1).
    Section 63.11647(a)(4)(iii) of the proposed rule would have 
required additional compliance testing if the mercury concentration in 
the ore fed to the roaster was higher than any concentration measured 
in the previous 12 months. We have removed this requirement from the 
final rule because it is not clear 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, 
condensers are used to recover liquid elemental mercury prior to the 
mercury scrubber, and any increase in mercury loading would likely 
result in an increase in the recovery of elemental mercury.
    The final rule incorporates several changes to Sec.  63.11647(b), 
which addresses monitoring of calomel-based mercury scrubbers (i.e., 
mercury scrubbers) that are used to control emissions from roasters. 
The proposed rule required monitoring of the scrubber liquid flow, 
liquid chemistry, scrubber pressure drop, and scrubber inlet gas 
temperature hourly. The final rule does not include the requirement to 
monitor pressure drop across calomel-based scrubbers because we 
conclude that pressure drop is not related to mercury emission control 
performance by this type of control device. In addition, the final rule 
allows hourly monitoring of the line pressure in the scrubber liquid 
supply line as an alternative to hourly monitoring of scrubber liquid 
flow rate. Line pressure monitoring is already in practice at some 
facilities and provides the same type of information as does liquid 
flow rate. As was proposed, the final rule allows the operating limit 
for scrubber liquid flow rate (or line pressure) and inlet gas 
temperature to be based on the minimum flow rate (or line pressure) or 
maximum inlet gas temperature established during the initial 
performance test. It also includes two additional options for setting 
these operating limits: (1) Based on the manufacturer's specifications 
if certain types of systems are designed to operate within a specified 
range of flow rates or temperatures; and (2) based on 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. This requirement takes into account the fact that, although 
initially the system may exhibit little variability from test run to 
test run, the short-term variability in performance may increase with 
time. Additional discussion of these changes can be found in section 
V.E of this preamble and in the Summary of Public Comments and 
Responses document in the docket for this rulemaking.
    In response to comments, we have revised the requirements for 
corrective action following control device monitoring parameter 
exceedances specified in Sec.  63.11647(d). Under the final rule, if 
the corrective actions taken following an exceedance do not result in 
the parameter value (e.g., liquid flow rate, line pressure, or inlet 
gas temperature) being returned to within the parameter range or limit 
within 48 hours, a mercury concentration measurement 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 from the time the parameter was exceeded. 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 measured mercury concentration indicates the operating 
limit for mercury concentration is exceeded, the exceedance must be 
reported as a deviation within 24 hours to the permitting authority, 
and the facility must perform a compliance test (pursuant to Sec.  
63.11647(d)) within 40 days to determine whether the source is in 
compliance with the MACT standard. We believe 40 days is appropriate 
because it may take 3 to 4 weeks to schedule and have the testing 
contractor on site, and, following completion of the test, another week 
or so to receive the final test results, and allows sufficient time to 
notify the permitting authority. We also removed the requirement that 
roasters must be shut down if a parameter is out of range.
    In Sec.  63.11647(a)(1)(ii) of the final rule, we require these 
same corrective actions described above (i.e., measuring mercury 
concentration within 48 hours, reporting a deviation if the data show 
the operating limit was exceeded within 24 hours, and conducting a 
compliance test within 40 days) for exceedances of mercury 
concentration operating limits indicated by the results of the twice 
monthly monitoring using PS 12B or Method 30B, CEMS, or continuous 
monitoring using PS 12B. In such cases, the owner or operator must use 
the results of the compliance test to determine if the ore pretreatment

[[Page 9455]]

process affected source is in compliance with the emission standard. If 
the source is determined to be in compliance, the owner or operator may 
use this compliance test to establish a new operating limit for mercury 
concentration for the roaster. We also removed the requirement that 
roasters must be shut down if the mercury concentration is out of 
range.
    In the final rule, Sec.  63.11647(f)(1) requires monthly sampling 
of the exhaust stream of carbon adsorbers using Method 30B. The 
duration of sampling must be at least the minimum sampling time 
specified in Method 30B and up to one week. The proposed rule required 
a full week of such sampling, but, as pointed out by one of the 
commenters, breakthrough of the sampling trap from exhaust streams with 
high mercury concentrations could occur before a week had elapsed.
    Section 63.11647(f)(2) of the final rule clarifies that sampling of 
the carbon bed must be collected from the inlet and outlet of the bed. 
This paragraph also specifies that, for carbon adsorbers with multiple 
carbon columns or beds, the sampling should be performed in the first 
and last column or bed rather than at the inlet or outlet.
    We have deleted Sec.  63.11647(f)(3) in the proposed rule, which 
allowed the carbon bed change-out rate to be determined based on 
historical data and the estimated life of the carbon. We have concluded 
that this method would not be adequate to ensure that breakthrough does 
not occur earlier than expected.
    We have clarified Sec.  63.11647(h) with respect to the monitoring 
of scrubbers (other than the calomel-based mercury scrubbers described 
above). Under the final rule, owners or operators are required to 
monitor and record water flow rate (or line pressure) and scrubber 
pressure drop once per shift; they also must record any occurrences 
when the water flow rate (line pressure) or pressure drop are outside 
the operating range, take corrective actions to return the water flow 
rate (line pressure) or pressure drop back in range, and record the 
corrective actions taken. At proposal, the water flow rate and pressure 
drop were to be monitored continuously. However, measuring the water 
flow rate (line pressure) and pressure drop once per shift will provide 
two to three measurements per day, and we believe that is sufficient to 
assure proper operations of the wet scrubber, and thus assure 
compliance with the emission standards. We have also added the option 
of monitoring the line pressure in the scrubber liquid supply line as 
an alternative to monitoring scrubber liquid flow rate because line 
pressure monitoring is already in practice at some facilities and 
provides the same type of information as does liquid flow rate. As was 
proposed, the final rule allows the operating limit for water flow rate 
and pressure drop to be based on the minimum value during the initial 
performance test. It also includes two additional options for setting 
the operating limit: (1) Based on the manufacturer's specifications; 
and (2) based on limits established by the permitting authority. We 
have also clarified that, for scrubbers on autoclaves, the pressure 
drop parameter range should be established from manufacturer's 
specifications only.

F. Definitions

    We have added a definition of carbon adsorber to Sec.  63.11651 to 
clarify that this term, as used in the final rule, includes control 
devices consisting of a single fixed carbon bed, multiple carbon beds 
or columns, carbon filter packs or modules, and other variations of 
carbon adsorber design.
    The definition of ``gold mine ore processing and production 
facility'' in Sec.  63.11651 of the rule has been clarified to state 
that small operations, such as prospectors and very small pilot scale 
mining operations, that process or produce less than 100 pounds of 
concentrate per year are excluded from the source category. These 
prospectors and very small pilot-scale operations (that process at or 
below this level) were not included in the section 112(c)(6) inventory 
that was the basis for the listing of gold mine ore processing and 
production source category. These types of very small operations were 
not intended to be subject to the final rule, and we do not expect any 
significant emissions from them. We also clarified that the source 
category does not include facilities at which 95 percent or more of the 
metals produced are metals other than gold. For example, if other non-
ferrous metals (such as copper, lead, nickel, or zinc) comprise 95 
percent or more of the product, the facility is not part of the gold 
ore processing and production source category.

V. Summary of Responses to Major Comments

A. Statutory Requirements

1. Listing of the Gold Mine Ore Processing and Production Source 
Category Under Section 112(c)(6)
    Comment: One commenter stated that adding the gold mine ore 
processing and production category to the list of categories required 
by Clean Air Act (CAA) section 112(c)(6) was correct and required 
because gold mines accounted for a significant portion of the aggregate 
emissions of mercury in the baseline year (1990) and because they still 
do so today. Other commenters stated that EPA does not have the 
authority to list gold mining processing and production as a source 
category under section 112(c)(6) and noted that section 112(c)(6) 
requires EPA to list, by 1995, categories of sources that make up 90 
percent of the 1990 emissions for a subset of hazardous air pollutants 
(HAP), including mercury. The commenters said that EPA concluded its 
statutory listing obligation for mercury in 1998 with the publication 
of a list of source categories constituting 90 percent of aggregate 
mercury emissions, and that gold mining was not included on that list 
in 1998. In addition, the commenters said that the CAA requires EPA to 
list all categories under section 112(c)(6) by 1995 and complete 
issuance of standards for all listed sources by 2000, a task that would 
be impossible if EPA had the authority to add source categories ad 
infinitum.
    Response: We appreciate the commenter's support in listing the gold 
mine processing and production area source category pursuant to section 
112(c)(6). We disagree, however, with the commenters that assert that 
EPA is precluded from listing additional categories pursuant to section 
112(c)(6). The commenters appear to be arguing that EPA is limited to a 
single listing opportunity under section 112(c)(6) and, having not 
listed gold mine ore processing and production in the initial 1998 
listing effort, EPA is now foreclosed from doing so. There is nothing 
in the language of section 112(c)(6), however, that precludes EPA from 
listing additional source categories to the extent EPA determines that 
those categories are needed to meet the 90 percent requirement in 
section 112(c)(6). Indeed, the commenter's reading is contrary to the 
fundamental purpose of section 112(c)(6).
    The core requirement of section 112(c)(6) is that EPA ``shall * * * 
list categories and subcategories of sources assuring that sources 
accounting for not less than 90 per centum of the aggregate emissions 
of each such pollutant'' are subject to standards under either 
11217FE0(d)(2) or (d)(4). EPA reasonably interprets section 112(c)(6) 
as allowing it to revise the list to add categories, where, as here, it 
determines that it needs the additional categories to meet the 90 
percent requirement in section 112(c)(6). Indeed, EPA has previously 
revised the section 112(c)(6)

[[Page 9456]]

list to add a source category, where EPA determined that category was 
needed to meet its 90 percent requirement for mercury. See 72 FR 74087 
(Dec. 28, 2007) (adding area source electric arc furnaces to the 
section 112(c)(6) list).
    As explained in the proposed rule, we have a 1990 baseline 
emissions inventory, and it is against this baseline that we assess 
compliance with the 90 percent requirement for each of the pollutants 
specified in section 112(c)(6). EPA explained in the initial 1998 
listing notice that it was using 1990 as the baseline year for 
assessing compliance with the 90 percent requirement. As EPA has 
developed emission standards for the sources included on the initial 
section 112(c)(6) list, it has acquired additional information on those 
sources and their emissions in 1990, which has resulted in some 
revisions to the 1990 baseline emissions inventory estimates. These 
revisions resulted in the need to regulate an additional source 
category. See 72 FR 74087 (setting standards for area source electric 
arc furnaces).
    In addition to obtaining additional information concerning the 
source categories on the initial list, EPA has obtained additional 
information concerning the 1990 emissions of other sources. As 
explained in the preamble to the proposed rule, at the time of the 
initial section 112(c)(6) listing, there was very little available 
information on mercury emissions from gold mine ore processing and 
production. See 75 FR 22471. Because EPA lacked emissions information 
on mercury emissions from this source category at the time of the 
listing decision, EPA was unable to estimate the 1990 baseline mercury 
emissions from the gold mine ore processing and production source 
category and include this category in the first listing effort. Based 
on information that became available after the initial listing, EPA now 
finds that regulation of the area source gold mine ore processing and 
production category is needed to meet the 90 percent requirement for 
mercury. 75 FR 22471. Under the commenters' view, EPA cannot add any 
additional categories to the section 112(c)(6) list following the 
initial listing. If true, EPA could not meet its section 112(c)(6) 
obligation--a result Congress could not have intended. EPA reasonably 
interprets section 112(c)(6) in a manner that allows the Agency to 
achieve that provision's core requirement. EPA repeats that it sees 
nothing in the language or purpose of section 112(c)(6) that precludes 
it from listing additional source categories as needed.
    Finally, Congress left to EPA's discretion which categories and 
subcategories of sources to include on the section 112(c)(6) list. We 
have determined that we need the gold mine ore processing and 
production source category to meet the 90 percent requirement in 
section 112(c)(6) for mercury and are therefore now setting standards 
for that category.
    We also reject the comment that the task of completing standards by 
2000 would be impossible if EPA had the authority to add source 
categories. Nevertheless, EPA is under a court ordered deadline to 
complete section 112(c)(6) standards by January 16, 2011. (Sierra Club 
v. EPA, Consolidated Case No. 01-1537, D.D.C).
    Comment: Some commenters claimed that EPA did not provide an 
adequate basis for its 1990 emissions estimate for gold mining 
processing and production. Specifically, they questioned EPA's 
estimated emissions of 4.4 tons from this source category in the 1990 
baseline year.
    Response: Although the commenters question EPA's estimated 
emissions of 4.4 tons from this source category in the 1990 baseline 
year, they did not provide an alternative method for calculating such 
emissions or alternative data or assumptions that should be used. They 
also did not explain what they think the 1990 baseline emissions should 
have been. EPA continues to maintain that its baseline emissions 
estimate is reasonable. The methodology EPA used to derive that 
estimate is described in docket item EPA-HQ-OAR-2010-0239-0175.
    Comment: Several commenters stated that Phase 2 permits under the 
Nevada Mercury Control Program (NMCP), which are scheduled for issuance 
by the end of 2010, will result in MACT-level controls on all thermal 
units at Nevada gold mines. According to the commenters, these permits 
are the culmination of a 7-year collaborative effort between NDEP and 
the gold mining industry to substantially reduce mercury emissions from 
gold mine processes. The commenters said that the proposal does not 
address how the NESHAP will result in reductions in mercury at gold 
mines in areas of the country other than Nevada, where the mercury 
content of the ore in gold mines is non-existent or only a fraction of 
the amount found in Nevada, and Nevada accounted for 99 percent of 
mercury emissions associated with gold mining operations in the United 
States. According to the commenters, this shows that if Nevada has an 
equivalent mercury control program for the gold mining industry, then 
there is nothing to be gained from imposing a Federal program, and if 
EPA acknowledges that the mines in Nevada are already well controlled, 
then the listing of gold mining and the promulgation of an additional 
layer of regulation at substantial cost to industry, but with little 
environmental benefit, is both legally indefensible and practically 
unsupportable.
    Response: As explained above, we are regulating the gold mine ore 
processing and production source category to meet the 90 percent 
requirement in section 112(c)(6) for mercury and are therefore setting 
standards for that category. Based on our 1990 baseline inventory for 
section 112(c)(6) and other emissions information for subsequent years, 
we estimate that this industry was among the top ten highest emitting 
categories of mercury emissions in the U.S. in 1990 and has remained in 
the top 10 since that time. Moreover, even though most emissions are 
from facilities located in Nevada, several commenters expressed serious 
concerns about the potential for mercury emissions from new gold mines 
in other States (e.g., Alaska). We share these concerns about potential 
emissions from new gold mine facilities. Finally, Congress left to 
EPA's discretion which categories and subcategories of sources to 
include on the section 112(c)(6) list. We are regulating the gold mine 
ore processing and production source category to meet the 90 percent 
requirement in section 112(c)(6) for mercury and are therefore now 
promulgating a Federal NESHAP for existing and new gold mine ore 
processing and production facilities.
2. Emission Standards for HAP Other Than Mercury
    Comment: One commenter stated that CAA section 112(c)(6) provides 
that EPA must ``list categories and subcategories of sources assuring 
that sources accounting for not less than 90 percent of each 
[enumerated] pollutant are subject to standards under subsection (d)(2) 
or (d)(4) of this section.'' The commenter also stated that the D.C. 
Circuit has held repeatedly that when EPA sets standards for a category 
or subcategory of sources under section 112(d)(2), EPA has a statutory 
duty to set emission standards for each HAP that the sources in that 
category or subcategory emit (e.g., National Lime Ass'n v. EPA, 233 
F.3d 625, 633-634 (D.C. Cir. 2000)). The commenter concluded that when 
EPA sets standards for gold mines under section 112(d)(2), as section 
112(c)(6) requires it to do, EPA must set section 112(d)(2) emission 
standards for all the HAP that gold mines emit.
    The commenter said that EPA appears to believe that because gold 
mines are

[[Page 9457]]

needed only to reach the section 112(c)(6) requirement of 90 percent 
for mercury and not for the other pollutants enumerated in section 
112(c)(6), EPA's only obligation under section 112(c)(6) is to set 
section 112(d)(2) standards for mercury. The commenter said that 
section 112(c)(6) expressly requires EPA to issue section 112(d)(2) 
standards for the ``sources'' in the categories listed under section 
112(c)(6), not some subset of the pollutants that those sources emit, 
and that section 112(d)(2) standards must include emission standards 
for each HAP that a source category emits. The commenter continued by 
stating that nothing in the CAA exempts EPA from this requirement. The 
commenter concluded that, had Congress wished to give EPA discretion to 
set standards for only some of the pollutants emitted by a category 
listed under section 112(c)(6), it would have done so expressly.
    Response: EPA disagrees with the comment that, even though EPA 
lists a category under section 112(c)(6) due to the emissions of one or 
more HAP specified in that section, EPA must issue emission standards 
for all HAP (including HAP not listed in section 112(c)(6)) that 
sources in that category emit. The commenter cited in support the 
opinion by the United States Court of Appeals for the DC Circuit in 
National Lime Ass'n v. EPA, 233 F.3d 625, 633-634 (D.C. Cir. 2000)). 
The part of the National Lime opinion referenced in the comment dealt 
with EPA's failure to set emission standards for certain HAPs emitted 
by major sources of cement manufacturing because the Agency found no 
sources using control technologies for those HAP. In rejecting EPA's 
argument, the court stated that EPA has ``a statutory obligation to set 
emission standards for each listed HAP.'' Id. at 634. The Court noted 
the list of HAP in section 112(b) and stated that section 112(d)(1) 
requires that EPA ``promulgate regulations establishing emission 
standards for each category or subcategory of major sources * * * of 
hazardous air pollutants listed for regulation. * * *'' Id. (Emphasis 
added). For the reasons stated below, we do not believe that today's 
final rule is controlled by or otherwise conflicts with the National 
Lime decision.
    National Lime did not involve section 112(c)(6). That provision is 
ambiguous as to whether standards for listed source categories must 
address all HAP or only the section 112(c)(6) HAP for which the source 
category was listed. Section 112(c)(6) requires that ``sources 
accounting for not less than 90 per centum of the aggregate emissions 
of each such [specific] pollutant are subject to standards under 
subsection (d)(2) or (d)(4).'' This language can reasonably be read to 
mean standards for the section 112(c)(6) HAP or standards for all HAP 
emitted by the source. Under either reading, the source would be 
subject to a section 112(d)(2) or (d)(4) standard.
    The commenter insists that once a section 112(d)(2) standard comes 
into play, all HAP must be controlled (per National Lime). But this 
result is not compelled by the pertinent provision, section 112(c)(6). 
That provision is obviously intended to ensure controls for specific 
persistent, bioaccumulative HAP, and this purpose is served by a 
reading which compels regulation under section 112(d)(2) only of the 
HAP for which a source category is listed under section 112(c)(6), 
rather than for all HAP.
    The facts here support the reasonableness of EPA's approach. Gold 
mine ore processing is an area source category listed under section 
112(c)(6) for regulation under section 112(d)(2) solely due to its 
mercury emissions. There is special statutory sensitivity to regulation 
of area source categories in section 112. For example, an area source 
category may be listed for regulation under section 112 if EPA makes an 
adverse effects finding pursuant to Section 112(c)(3) or if EPA 
determines that the area source category is needed to meet its section 
112(c)(3) obligations to regulate urban HAP or its section 112(c)(6) 
obligations to regulate certain persistent bioaccumulative HAP. 
Therefore, unless an area source category emits a section 112(c)(3) 
urban HAP or a section 112(c)(6) HAP and EPA determines that such 
category is needed to meet the 90 percent requirement set forth in 
section 112(c)(3) and (c)(6), findings related to adverse human health 
or environmental effects are required before EPA can regulate that area 
source category--findings EPA is unable to make for non-mercury HAP 
emitted from the gold mine ore processing and production source 
category at this time. Moreover, to the extent EPA lists an area source 
category pursuant to section 112(c)(3) (whether that finding is based 
on adverse effects to human health or the environment or a finding that 
the source is needed to meet the 90 percent requirement in section 
112(c)(3), the statute gives EPA discretion to set generally available 
control technology (``GACT'') standards for such sources. 42 U.S.C. 
7412(d)(5).
    EPA does not interpret section 112(c)(6) to create a means of 
automatically compelling regulation of all HAP emitted by area sources 
unrelated to the core object of section 112(c)(6), which is control of 
the specific persistent, bioaccumulative HAP, and thereby bypassing 
these otherwise applicable preconditions to setting section 112(d) 
standards for area sources. Nor does National Lime address the issue, 
since the case dealt exclusively with major sources.\3\ 233 F. 3d at 
633. Consequently, EPA disagrees with the comment that it is compelled 
to promulgate section 112(d)(2) MACT standards for all HAP emitted by 
gold mine ore processors.
---------------------------------------------------------------------------

    \3\ EPA acknowledges that major sources regulated under section 
112 must be subject to MACT standards for all HAP emitted from the 
source category consistent with National Lime.
---------------------------------------------------------------------------

3. Emission Standards for Fugitive Emissions
    Comment: One commenter stated that gold mines have significant 
fugitive emissions of mercury, but that EPA did not propose standards 
for these emissions or mention them in its proposal. The commenter said 
that EPA has a statutory obligation to set standards for gold mine 
mercury emissions under section 112(d)(2) and (3), and must set 
emission standards for all the mercury emissions from the listed 
category. Another commenter described a recent preliminary study at two 
facilities in Nevada that found fugitive mercury air emissions from 
various non-point sources at those two mining operations such as from 
leach pads and tailings ponds.
    One commenter stated that means to control fugitive emissions are 
available, such as enclosing their leaching operations. By enclosing 
the leaching process, the commenter believes that mines could eliminate 
this source of fugitive emissions. The commenter also stated that mines 
should not send tailings into open tailing ponds, but into closed 
treatment facilities that would remove mercury and other HAP from the 
tailings and prevent their release to the air. The commenter 
recommended that EPA evaluate the use of sulfur-based complexing agents 
for removing mercury during cyanidization of gold. According to the 
commenter, research indicates that these products appear useful for 
substantially reducing mercury in process solution during heap 
leaching.
    Response: Due to the lack of information, we have not included 
fugitive mercury emissions at gold mine facilities in our 1990 baseline 
emission estimate (or in our more recent emissions estimates) for the 
gold mine ore processing and production area source category. 
Accordingly, these fugitive emissions are not part of the

[[Page 9458]]

source category we are listing and regulating in this final rule. Other 
than the recent preliminary research at two facilities, we have no data 
on fugitive mercury emissions at gold mine facilities. The recent 
preliminary research suggests that some fugitive emissions may be 
occurring at these facilities from large non-point sources such as 
tailings ponds, leach fields and waste rock piles. However, it is our 
understanding that this preliminary research has not yet been published 
or peer-reviewed. Thus, at this juncture, we do not have sufficient 
information on fugitive emissions.
    Furthermore, we have very little information on how these fugitive 
mercury emissions might be controlled. A few commenters suggested that 
certain compounds were available that may be useful for limiting these 
emissions. However, as far as we know, there has been no demonstration 
that these compounds would work effectively to limit the emissions, and 
we do not know the costs or potential adverse impacts of applying these 
chemicals. Therefore, we question the feasibility and practicality of 
applying these chemicals to limit fugitive mercury emissions from these 
non-point sources. We also question the feasibility and practicality of 
enclosing the leaching operations or the tailings ponds, as suggested 
by some commenters.
    As explained in the proposed rule, the gold mine ore processing and 
production area source category covers the thermal processes that occur 
after ore crushing, including roasting operations (i.e., ore dry 
grinding, ore preheating, roasting, and quenching), autoclaves, carbon 
kilns, electrowinning, preg tanks, mercury retorts, and furnaces. The 
data and calculations used to derive the estimated 4.4 tons of mercury 
emissions for this source category for the 1990 baseline inventory for 
section 112(c)(6) reflect emissions from the thermal processes 
described above, and the final MACT standards address all of these 
processes.
4. Major Source Determination
    Comment: One commenter noted that the proposal stated that the gold 
mining processing and production source category consists of only area 
sources; however, the proposal indicated that actual emissions of 
hydrogen cyanide (HCN) at a few facilities were near the major source 
threshold. The commenter concluded that EPA violates both the CAA and 
its own regulations by basing its evaluation of whether gold mines are 
major sources on their actual emissions instead of their potential 
emissions.
    The commenter further noted that the proposal requested comment on 
a certification process that would allow gold mines to avoid major 
source status whereby companies could certify that they are area 
sources by implementing certain ``management practices'' and then 
certifying to EPA that they had done so. The commenter stated that such 
a certification process would be unlawful in calculating a sources 
``potential to emit'' because the management practices are not 
``control equipment,'' ``restrictions on hours of operation or on the 
type or amount of material combusted, stored, or processed,'' and would 
not be ``federally enforceable.''
    Other commenters supported EPA's conclusion and determination that 
the gold mines are area sources of HAP. According to the commenters, 
EPA's methodology in making this determination was extremely 
conservative because EPA did not apply what the commenters believe to 
be a key correction factor. Application of this correction factor would 
have reduced the HCN emissions estimates from by approximately 40-50%. 
The commenters also stated that fence line testing at selected gold 
mine operations demonstrated that these levels of HCN were below all 
applicable public health standards.
    The commenters believe that, because the gold mines are area 
sources of HCN, they should not be subject to section 112 work practice 
standards or newly developed certification requirements. The commenters 
noted that it is not technically practical to set systematic work 
practice standards to reduce HCN emissions for every gold mining 
operation to follow because each mine is unique in its mineralogy and 
cyanide leaching processes, and different process solution pH values 
are necessary to enhance gold recovery.
    The commenters explained that for economic, health, and safety 
reasons, they already implement work practice standards designed to 
minimize HCN. The commenter concluded that the combination of these 
work practice standards and the annual TRI reporting more than 
adequately ensure that gold mining operations will remain area sources 
of HCN.
    Response: Contrary to the assertions of one of the commenter's, EPA 
did not state in the preamble to the proposed rule that the sources at 
issue had actual emissions ranging from 5 to 9 tons. By contrast, EPA 
stated that ``a few facilities are close to the major source threshold 
due to hydrogen cyanide (HCN).'' 75 FR 22479. EPA failed to clarify in 
the preamble to the proposed rule that the range of 5 to 9 tons 
represented potential to emit calculations for the largest-emitting 
sources. Specifically, as explained in the document ``Estimated 
Emissions of HCN from Gold Mine Facilities in the U.S.'' (which is 
available in the docket for this rulemaking), EPA estimated the 
potential to emit for the five largest sources assuming that these 
sources would be operating every day of the year, 24 hours a day, at 
100 percent of its current capacity. These assumptions and calculations 
resulted in a potential to emit estimate of 5 tons of HCN per year for 
the largest source. EPA then completed a second set of calculations, 
using the same assumptions (i.e., operating every day of the year, 24 
hours a day, at full capacity), but without applying the surface area 
correction factor, and those calculations resulted in a conservative 
potential to emit estimate of 9 tons of HCN per year for the largest 
source. The emission estimates for the remaining large facilities were 
all below 9 tons.
    The commenters correctly point out that in determining whether a 
source is a ``major source'' under CAA section 112, we must consider 
the source's potential to emit, as well as its actual emissions. See 
CAA section 112(a)(1) and 40 CFR 63.2. As noted above, we specifically 
examined the sources' potential to emit and concluded that all sources' 
potential to emit were below the major source thresholds.
    Some commenters allege that EPA significantly overestimated HCN 
emissions from the larger sources by not accounting for certain 
correction factors. They assert that if one were to account for the 
appropriate correction factors in developing the potential to emit 
values, HCN emissions would ``range from 3.7-4.5 tpy for the larger 
mines compared to the 5-9 tpy estimate'' (See document titled ``PTE 
Emission Estimates for HCN'' by the Nevada Mining Association, which is 
available in the docket for this action). Other commenters make a 
blanket, unsupported assertion that the Agency has underestimated HCN 
emissions from the source category because they believe that without 
the management practices currently employed by sources in the category, 
HCN emissions would exceed the major source thresholds at the larger 
sources. These latter commenters, however, made only conclusory 
statements and did not demonstrate that HCN emissions from the larger 
sources would exceed the major source thresholds if the management 
practices were not employed.

[[Page 9459]]

    In sum, EPA has developed conservative estimates of the sources' 
potential to emit HCN. At one end of the range EPA estimates potential 
emissions of 5 tons per year of HCN for the largest source, which is 
well below the major source threshold of 10 tons per year of a single 
HAP. At the other end of the range EPA estimates potential emissions of 
9 tons per year for that same largest source, which is a conservative 
estimate and is still below the major source threshold. The emission 
estimates for the remaining large facilities were all below 9 tons. We 
understand that the sources at issue implement various management 
practices as part of their operations to minimize the use and emissions 
of cyanide to protect workers, to comply with Mine Safety and Health 
Administration (MSHA) standards, to comply with their agreements to the 
International Cyanide Code, and for economic reasons (to reduce 
operational and supply costs). We currently do not have sufficient 
information to explicitly quantify emissions reductions achieved 
through these management practices, but nothing in the record suggests 
that the facilities would be major sources if they failed to employ the 
management practices. Accordingly, we are taking final action today to 
list the gold mine ore processing and production area source category 
and regulate its mercury emissions pursuant to CAA section 112(c)(6).
    Although not required, we intend to send letters to various Gold 
Mining Processing and Production companies pursuant to Section 114 of 
the Clean Air Act to confirm our conclusion that the sources' potential 
to emit remain below major source thresholds.
5. Title V Permit Exemption
    Comment: In the proposal preamble, EPA solicited comment on whether 
a title V exemption ``is appropriate under section 502(a) for any 
particular sources in this category.'' One commenter offered the 
following reasons for not exempting gold mines from title V permitting 
requirements:
     EPA did not properly determine whether some or all sources 
in the category are major sources by determining each source's 
potential to emit.
     The CAA allows EPA to exempt area sources from title V 
permitting only if it establishes that compliance with the title V 
permitting requirements would be ``impracticable, infeasible or 
unnecessarily burdensome.'' However, EPA does not claim that such 
requirements are ``impracticable,'' ``infeasible,'' or ``unnecessarily 
burdensome'' for gold mines.
     It is feasible and within the gold mining companies' 
financial means to comply with title V permitting requirements.
    The commenter believes that the text and legislative history of the 
CAA make plain that Congress intended ordinary citizens to be able to 
get emissions and compliance information about air toxics sources and 
to be able to use that information in enforcement actions and in public 
policy decisions on a State and local level. According to the 
commenter, Congress did not think that enforcement by States or other 
government entities was enough; if it had, Congress would not have 
enacted the citizen suit provisions. The commenter said that, if a 
source does not have a title V permit, it is difficult or impossible 
for a member of the public to obtain relevant information about its 
emissions and compliance status or to bring enforcement actions. The 
commenter stated that to the extent the informational and enforcement 
benefits provided by title V permits can be considered a burden, these 
benefits far outweigh that burden.
    The commenter also noted that title V provides important monitoring 
benefits and that title V permits are necessary to provide adequate 
monitoring. The commenter concluded by stating that the legislative 
history of the CAA shows that Congress did not intend EPA to exempt 
source categories from compliance with title V unless doing so would 
not adversely affect public health, welfare, or the environment; 
however, exempting gold mines from title V would adversely affect 
public health, welfare and the environment by depriving the public of 
important informational and enforcement benefits.
    One State agency commented that additional title V permitting would 
subject both the source and the State agency to additional resource 
burdens. The commenter points out that major sources of criteria 
pollutant emissions are currently subject to title V permit 
requirements in Nevada and that sources not subject to major source 
permitting requirements are subject to Nevada's minor source permitting 
program. In addition, the NMCP requires all mining sources to obtain 
mercury-specific operating permits to construct. The commenter believes 
that these permit programs would provide a strong basis for 
implementing and enforcing any Federal MACT requirements for the gold 
mining industry, and there would be nothing gained by subjecting these 
sources to title V permitting.
    Several commenters stated that EPA should exercise its discretion 
and exempt the gold mine ore processing and production industry from 
the title V requirements as impracticable, infeasible, and 
unnecessarily burdensome. The commenters said that, in light of EPA's 
findings in other similar rulemakings for area sources, the four 
factors set forth in the Exemption Rule support a finding that title V 
permitting is ``unnecessarily burdensome'' for the gold mine ore 
processing and production area source category.
    In discussing the first factor of the Exemption Rule, whether title 
V would result in significant improvements to the compliance 
requirements, the commenters said that the proposed NESHAP for the gold 
mine ore processing and production area source category includes 
extensive monitoring, recordkeeping, and reporting requirements that 
are more comprehensive than title V requirements. The commenters 
believe that Nevada regulations and permits provide an additional layer 
of compliance assurance on the Federal NESHAP that obviates the need 
for title V permitting. The commenters claimed that the additional 
layering of title V does not ``significantly improve'' upon the 
proposed and existing compliance requirements.
    Regarding the second factor in the Exemption Rule, whether title V 
permitting would impose significant burdens on the area source category 
and whether the burdens would be aggravated by any difficulty the 
sources may have in obtaining assistance from permitting agencies, the 
commenters said that there are extensive administrative burdens and 
costs associated with the title V permitting process, including 
mandatory activities that have been previously identified by EPA. The 
commenters claimed that many of the area source gold mines are owned 
and operated by small entities that are already required to comply with 
comprehensive State permitting requirements for mercury emissions and 
that requiring title V permits for them would result in resources being 
redirected away from more useful and necessary efforts.
    The commenters explained that the third factor in the Exemption 
Rule examines whether the costs of title V permitting for the area 
source category would be justified, taking into consideration any 
potential gains in compliance likely to occur for such sources. The 
commenters claim that there do not appear to be any gains in compliance 
to justify the additional costs that would be imposed on these area 
sources from title V permitting

[[Page 9460]]

based on the lack of significant improvements in compliance 
requirements and the substantial additional costs and burdens 
associated with title V compliance.
    The commenters noted that the fourth factor in the Exemption Rule 
analysis is whether there are implementation and enforcement programs 
in place that are sufficient to assure compliance with the NESHAP for 
the area source category, without relying on title V permits. The 
commenters claimed that the proposed rule includes all necessary 
monitoring to effectively implement its requirements, and the area 
sources for the gold mine ore processing and production are already 
permitted under State permit programs. According to the commenters, all 
non-title V sources in Nevada are required to hold ``Class II'' 
operating permits that must contain, among other things, all applicable 
emission limitations and standards. The commenters said that other 
States where gold mine ore processing and production area source are 
located either would be covered by a comparable delegated State air 
program or by EPA.
    The commenters stated that EPA regularly provides title V 
exemptions for area sources similar to gold mine ore processing and 
production area sources and cited examples from the past year. The 
commenters claim that the existing and proposed compliance and 
monitoring requirements for the gold mines are generally more stringent 
than those found in the other NESHAPs for which EPA has granted a title 
V permit exemption.
    The commenters stated that exempting the gold mine ore processing 
and production area source category from title V permitting will not 
adversely affect public health, welfare, or the environment because 
title V permits do not generally impose substantive air quality control 
requirements. According to the commenters, requiring title V permits 
also carries the potential of adversely affecting public health, 
welfare, or the environment by shifting State agency resources away 
from ensuring compliance with a program that is reducing mercury 
emissions from gold mines.
    The commenters stated that EPA should exempt the gold mine ore 
processing and production area source category from title V permitting 
requirements, and at a minimum, should exempt area source gold mines 
that are subject to Nevada's comprehensive mercury control program.
    Response: After reviewing the comments, we continue to believe that 
it is appropriate that all gold mine ore processing and production 
facilities be required to obtain title V permits. Most of the other 
area source categories for which we have provided title V permit 
exemptions have hundreds or thousands of facilities that are mostly 
owned by small businesses. In contrast, there are an estimated 21 
facilities that are subject to this final rule, and, based on our 
research and analyses, none of the facilities are owned by small 
businesses; most of these facilities are owned by large, and in some 
cases, multi-national, corporations. Therefore, we conclude that the 
argument of financial burden, which has supported title V exemption for 
other source categories, does not apply to the gold mining industry 
(see Economic and Small Business Analysis, which is available in the 
docket).
    Currently, it is our understanding that 7 of the 21 facilities that 
will be subject to the final rule already have title V permits (5 in 
Nevada and 2 in other states). Further, there are approximately 5 
facilities in all other States (i.e., except Nevada) that do not 
currently have title V permits that will be subject to this final rule, 
so title V permitting will apply to no more than a few facilities in 
any one of these other States. Therefore, we do not believe the 
requirement for title V permitting will be overly burdensome to the 
permitting authorities in those States. Although there are more 
facilities in Nevada that will be subject to the final rule, as the 
commenters point out, Nevada already has an effective permitting system 
in place. Five of the 14 gold mine facilities in Nevada already have 
title V permits. Because of Nevada's existing permitting system and 
experience with title V permitting, we do not think that it is an undue 
burden on the State of Nevada to require title V permits from the other 
gold mine facilities located within the State. We also think it is 
important for the public in States where these facilities are located 
to have access to emissions and monitoring data and the opportunity for 
public involvement in the permitting of these facilities that is 
provided by title V permitting.
6. Reconstruction
    Comment: Several commenters believe it is appropriate to group 
under each of the umbrella ``affected sources'' all the equipment 
associated with each particular process in order to ensure a reasonable 
application of the reconstruction provisions found in the General 
Provisions. The commenters asked that EPA reaffirm that the 50 percent 
fixed capital cost trigger for determining reconstruction would be 
measured against all equipment components needed for the defined 
processes, and that reconstruction at one affected source as defined in 
the standard will not affect or result in reconstruction at another 
affected source.
    The commenters also noted that the definition of ``reconstruction'' 
authorizes EPA to establish special provisions in a particular standard 
for the application of the reconstruction criteria to the affected 
source. The commenters said that the ``carbon processes'' affected 
source illustrates that the affected source can consist of several 
pieces of interconnected equipment that together constitute the process 
line, and it can be anticipated that production needs will give rise to 
the need to add more pieces of equipment to an existing carbon process 
line or even to install a whole new carbon process line. The commenters 
provided three examples: Adding a new component to an existing carbon 
processes group; construction of a new carbon group due to expansion at 
a facility that has an existing carbon group; and installation of new 
pollution control equipment. The commenter said that consideration of 
whether or where new MACT requirements should apply in these examples 
warrants the development of special reconstruction provisions in this 
standard, or EPA should clarify that the three examples would not be 
considered reconstruction under the proposed rule.
    The commenters asked that EPA either clarify that the three 
examples would not be considered reconstruction, or alternatively, add 
the following provisions to the proposed rule: (1) An addition of a new 
piece of equipment to address production requirements is not considered 
a reconstruction, (2) the expansion of a facility by the construction 
of a completely new process line will not be considered a 
reconstruction of an existing process line, and (3) the installation of 
air pollution control equipment to comply with this standard is not 
considered a reconstruction.
    Response: The determination of what constitutes a reconstruction is 
directly tied to the definition of the affected source and the 
definition of reconstruction in the part 63 General Provisions:

    Reconstruction, unless otherwise defined in a relevant standard, 
means the replacement of components of an affected or a previously 
nonaffected source to such an extent that:
    (1) The fixed capital cost of the new components exceeds 50 
percent of the fixed capital cost that would be required to

[[Page 9461]]

construct a comparable new [affected] source; and
    (2) It is technologically and economically feasible for the 
reconstructed source to meet the relevant standard(s) established by 
the Administrator (or a State) pursuant to section 112 of the Act. 
Upon reconstruction, an affected source, or a stationary source that 
becomes an affected source, is subject to relevant standards for new 
sources, including compliance dates, irrespective of any change in 
emissions of hazardous air pollutants from that source.

    For each of the four affected sources in the final rule, we have 
defined the affected source as the collection of processes associated 
within each affected source. Consequently, if one process within the 
affected source is upgraded or replaced with a new process, the 50 
percent fixed capital cost criterion would be based on the fixed 
capital cost of replacing all processes in the affected source, not 
just the capital cost of the process being upgraded or replaced. For 
example, if a new carbon kiln is added to an existing group of carbon 
processes with mercury retorts, the capital cost of the new carbon kiln 
would be divided by the fixed capital cost of constructing a comparable 
new affected source containing all of the processes within the existing 
affected source of carbon processes with mercury retorts to calculate 
the percent for comparison to the 50 percent criterion.
    With regard to the scenario where a new carbon process with a 
mercury retort is installed, the affected source is defined as the 
collection of all applicable processes within the affected source, and 
because of this, a facility could not have two carbon processes with 
mercury retorts affected sources, such as the commenter suggested, 
where one group is new and the other is existing. For example, if a new 
group of carbon processes with mercury retorts is installed at a 
facility in addition to an existing group of carbon processes with 
mercury retorts, the two groups (all carbon processes with mercury 
retorts at the facility) collectively would be a single affected 
source. In this case, the fixed capital cost criterion would be based 
on the fixed capital cost of replacing the existing affected source 
with a comparable new affected source, and if the new processes exceed 
50 percent of that cost, all of the carbon processes with mercury 
retorts would be subject to the new source limit for carbon processes. 
There would not be separate and different emission standards for the 
two sets of carbon sources with mercury retorts (the older group and 
newer group) because the collection of all of these processes is the 
affected source.
    We do not see a necessity to provide criteria for this final rule 
that are different from the requirements in the General Provisions for 
determining what constitutes a reconstruction. We also think it is 
appropriate to exclude the cost of emission control equipment from the 
cost calculation for reconstruction determinations.

B. Applicability

    Comment: Several commenters stated the rule should exempt 
individuals (prospectors), laboratories, small mining operations, and 
non-leaching operations. The commenters urged EPA to include in the 
final rule all of the following exemptions to avoid the problem of 
unintended regulation of sources that were not meant to be included in 
the source category: Gold mining operations that produce less than 100 
pounds of concentrate per year, which would exempt analytical labs that 
perform small bench scale processing tests on gold ores; gold mining 
operations that do not leach or dissolve gold, which would exempt 
placer and other non-leaching operators, including both small 
commercial efforts as well as individual recreation-type prospectors; 
and gold mining operations that process less than 1,000 tons per year 
of gold ore, which would exempt certain small scale pilot plants and 
related testing operations. The commenters said that the exemptions 
suggested above will not reduce in any way the effectiveness of the 
proposed rule in controlling mercury emissions from the targeted larger 
mines, nor will they lead to increased mercury emissions, but they will 
exclude regulation of a large number of small operators who do not emit 
any significant mercury.
    Response: Section 63.11640(c) of the proposed rule provides that 
the emissions standards for this area source category do not apply to 
research and development facilities, as that term is defined under CAA 
section 112(c)(7). We did not receive any adverse comments concerning 
this provision, and are finalizing the provision in this rule.
    Further, as mentioned above in section IV, we are clarifying in 
this final rule that this area source category does not include 
individual prospectors and very small pilot scale mining operations. 
Prospectors and other very small pilot-scale operations (e.g., 
operations that produce or process less than 100 pounds of concentrate 
per year) are very small and were not included in the section 112(c)(6) 
inventory that was the basis for the listing of gold mine ore 
processing and production source category. We believe that emissions 
from the very small scale operations described above to be very 
minimal.
    By contrast, the commenter's suggested 1,000 tons/yr ore threshold 
may include operations beyond the very small scale pilot operations 
discussed above. We believe that the 100 pounds of concentrate per year 
more appropriately reflect these very small scale operations.
    We are not making the suggested change of excluding operations that 
do not leach or dissolve gold because certain gold mine facilities in 
the source category use flotation or gravity flotation processes and 
perform thermal processing of concentrate in melt furnaces, which can 
have significant emissions of mercury. However, as mentioned above we 
are clarifying that this final rule does not apply to these very small 
scale operations.

C. MACT Floors

1. Consideration of Variability in Determining Floors
    Comment: One commenter acknowledged that EPA may consider 
variability in calculating the best sources' performance, but stated 
that EPA's method of considering variability seeks to assure that none 
of the sources among those identified as best performers would ever 
exceed the floor level. The commenter claims that such an approach 
ignores the reality that sources' emission levels are largely within 
their control, and although a great deal of variability may be 
statistically conceivable if EPA chooses a high enough prediction limit 
(in this case the 99th percentile) that does not mean that a well-
operated source actually would experience such variability. The 
commenter said that one of the main points of having emission standards 
is to ensure that sources not only deploy the appropriate control 
measures, but also use those control measures consistently to minimize 
emissions.
    The commenter said that using an upper prediction limit to set 
standards reflecting the statistical worst performance these sources 
could have in a purely statistical sense does not yield an accurate 
picture of the best sources actual performance, and it is especially 
arbitrary in the absence of any explanation of why EPA thinks that the 
relevant best sources' performance would ever be so bad, other than the 
fact that it is statistically possible.
    Response: As described previously, the MACT floor limits are 
calculated based on the performance of the lowest

[[Page 9462]]

emitting sources in each of the MACT floor pools. We ranked all of the 
sources for which we had data based on their emissions and identified 
the lowest emitting sources.
    As the commenter concedes, EPA can consider variability in 
assessing sources' performance when setting MACT standards. See Brick 
MACT, 479 F.3d at 881-82; and Mossville Envt'l Action Now v. EPA, 370 
F.3d 1232, 1241-42 (D.C. Cir 2004) (reaffirming that EPA can assess 
variability in determining the level of emissions control achieved by 
the best performing sources).
    Variability in facilities' performance has various causes. One 
source of variability for these facilities is the differing mercury 
concentrations in the input materials. Another source of variability is 
due to normal variations in performance of the control devices for 
which both run-to-run and test-to-test variability must be 
accounted.\4\ A review of the run-by-run emissions data in the record 
shows that emission rates from one run to the next for well-operated 
sources can vary by as much as a factor of 8. We need to account for 
sources' variability (both due to control device performance and 
variability in inputs) in assessing sources' performance when 
developing technology-based standards. Accordingly, EPA accounts for 
variance in test data, between units, and among facilities when 
developing the MACT standard.
---------------------------------------------------------------------------

    \4\ Run-to-run variability is essentially within-test 
variability, and encompasses variability in individual runs 
comprising the compliance test, and includes uncertainties in 
correlation of monitoring parameters and emissions, and imprecision 
of stack test methods and laboratory analysis. 72 FR at 54877 (Sept. 
27, 2007). Test-to-test variability results from variability in 
pollution device control efficiencies over time. Test-to-test 
variability can be termed long-term variability. 72 FR at 54878.
---------------------------------------------------------------------------

    In determining the MACT floor limits, we first determine the 
average emissions of the top performers based on available data. We 
then assess variability of the best performers by using a statistical 
formula designed to estimate a MACT floor level that is equivalent to 
the average of the best performing sources based on future compliance 
tests. Specifically, the MACT floor limit is an upper prediction limit 
(UPL) calculated with the Student's t-test. The Student's t-test has 
also been used in other EPA rulemakings (e.g., NESHAP for Cement 
Manufacturing, NSPS for Hospital/Medical/Infectious Waste Incinerators, 
and NESHAP for Industrial, Commercial, and Institutional Boilers and 
Process Heaters) in accounting for variability. A prediction interval 
for a future observation is an interval that will, with a specified 
degree of confidence, contain the next (or some other pre-specified) 
randomly selected observation from a population. In other words, the 
prediction interval estimates what the upper bound of future values 
will be, based upon present or past background samples taken. The UPL 
consequently represents the value which we can expect the mean of 
future observations (i.e., emission test runs) to fall below within a 
specified level of confidence, based upon the results of an independent 
sample from the same population. In other words, if we were to randomly 
select a future test condition from any of these sources (e.g., average 
of 3 runs) we can be 99 percent confident that the reported level will 
fall at or below the 99 percent UPL value. We note that the methodology 
accounts for both short-term and long-term variability and encompasses 
run-to-run and test-to-test variability.
    For this rule, we used the 99 percent UPL analysis on the emissions 
data for the top performing sources to account for the variance. In the 
context of determining the MACT floor, the 99 percent UPL represents 
the value below which the mean of future compliance tests (based on, 
for example, a 3-run average) would fall 99 percent of the time. A 99 
percent level of confidence means that a facility, whose emissions are 
consistent with the best performing sources, has one chance in 100 of 
exceeding the emission standard.
    We believe that using the 99 percent UPL is appropriate for this 
rule. As noted above, this approach is consistent with several other 
previous rulemakings. It also makes sense from a practical standpoint. 
If we selected a lower number (e.g., 95 percent UPL) this would mean 
that a best performing source that is performing at the MACT level of 
control would potentially exceed the limit 5 percent of the time--which 
we do not believe is a reasonable approach for this rule. See 
Mossville, 379 F.3d at 1241-42); see also 70 FR at 59438 (Oct. 12, 
2005) (explaining use of 99th percentile). With regard to the 
commenter's statement that no sources among the best performers would 
ever exceed the MACT standard, we believe this is incorrect. The 
commenter provided no basis for this statement, and we do not believe 
the commenter based this statement on an analysis of the variability in 
the data.
    We do not believe that the UPL analysis reflects the statistical 
worst performance the top five performing sources could have. The UPL 
calculation is dependent on the data that we have, and reflects the 
actual variability in the test data for the best performing sources. It 
does not reflect worst-case performance. We continue to believe that 
the UPL does yield an accurate picture of the best sources' performance 
as best as possible with taking into account variance between the 
facilities, units at the facilities, and between test runs for the 
different units (including variability in input materials).
    Furthermore, although the average of several data sets may show a 
top performing source meeting the emission standard by a significant 
margin, the variability in emissions inherent in any one compliance 
test could easily indicate much higher emissions, and, in some cases, 
an exceedance of the emission standard. We continue to believe that the 
UPL analysis evaluated at 99 percent confidence is appropriate for this 
source category.
    Moreover, we believe the data we used to calculate the MACT 
standards are representative of the normal performance of the best 
performing sources for several reasons. First, the test results that we 
are using in our MACT database are tests conducted under Nevada's 
mercury emission control program, and are conducted to determine 
whether a facility is in compliance with State requirements. Facilities 
typically try to perform as well as they can during such tests. State 
(and often EPA) permitting authority staff are notified before a 
performance test is conducted to provide an opportunity to attend and 
observe the test, and they often attend to ensure the source is 
operating properly and that the testing is performed according to the 
strict requirements in the codified test methods.
    Test reports are carefully reviewed by the permitting authority, 
and any failure to follow the test method or abnormal operation of a 
source is flagged. These data are usually invalidated, and invalidated 
tests are not used in our MACT standard calculations. For example, 
several tests from these facilities were invalidated by the NDEP 
because the specified testing procedures were not followed or the 
emission control device was not operating properly, and we have not 
used those results in our analysis for those reasons. We have collected 
additional data from test reports not available at the time of 
proposal, and one of those tests was invalidated because NDEP 
representatives discovered that the emission control device was not 
operating properly during the test. Therefore, we also did not use 
those test data.
    The commenter believes that floors must be set at the average 
emission level

[[Page 9463]]

achieved by the best performers when they are operating properly. We 
agree that the performance data characterizing the emission level 
achieved by the top performers must be data obtained when they are 
operating properly, and we believe that is the case for our current 
database for this source category.
    As described above, the MACT floor is based on the average 
performance of the top performers plus an amount to account for 
variability. We have appropriately developed a MACT standard based on 
emissions from the top 5 best performing sources that accounts for 
variability because, over an extended period of time, the emissions 
from each of these best performing facilities (even the best 
controlled) will vary above and below the facility average. For 
example, we expect that about half of the duration of the year the 
emissions from a best performing facility would be somewhat below their 
average and that about half of the duration of the year their emissions 
would be somewhat higher than their average. If we set the MACT limit 
exactly equal to the average emissions level achieved by the best 
performers (without accounting for variability), and we had a source 
that was performing at exactly the MACT level over the course of the 
year, the measured emissions level on roughly half the days of the year 
would suggest that the source is emitting at levels above the MACT 
limit, and on about half of the other days of the year the measured 
emissions level would suggest that the source is emitting at levels 
less than the MACT limit. We reasonably and appropriately accounted for 
variability in the data consistent with established statistical theory 
and practice and judicial precedent. Finally, ignoring variability of 
the best performing sources and using only the average performance 
would virtually guarantee that some of even the best performers would 
exceed the floor limit at least some of the time.
    Thus, we developed a MACT standard based on the average of the best 
performing sources that accounts for variability. We accomplished this 
by calculating the MACT standard from this average performance and 
accounting for variability by using the 99 percent UPL. The specific 
calculations are presented in the MACT floor document in the docket for 
this rulemaking. Furthermore, we agree with the comment that one of the 
points of having emission standards is to ensure that sources not only 
deploy the appropriate control measures, but also use those control 
measures consistently to minimize emissions. We believe that the MACT 
standards established in this rule along with the requirements to 
monitor and maintain control device parameters within certain ranges 
will ensure control measures are applied consistently to minimize 
emissions.
    Comment: Another commenter stated that consideration should be 
given to defining the inherent range of measurement error and requiring 
more test runs in order to reduce variability due to process variation. 
The commenter said that this would also better clarify when variability 
was due to operational controls, which could be addressed, rather than 
due to factors that cannot be controlled, such as mercury content in 
the ore. The commenter asked for clarification on how inconsistent runs 
should be treated, what defines an acceptable set of runs, and at what 
point more runs would be required to provide reliable data.
    The commenter also stated that the degree of variability allowed in 
the development of the new source limit for ore pretreatment appears to 
be out of line with the new source limits for carbon processes and non-
carbon processes. The commenter believes that ore pretreatment 
variability for new sources is higher than existing sources because low 
thermal units were included in the same category, high emissions were 
allowed in the data set, and variable emissions were allowed in data 
set. The commenter recommended that, if EPA continues to use Goldstrike 
as the best performing source for new source MACT, then they should re-
evaluate and reduce the variability to be equal to or less than the 
variability for existing sources.
    Response: We agree with the commenter that the testing process 
would be more accurate if the number of test runs was increased. 
However, we balance several factors in determining the minimum number 
of runs required, and because the compliance testing is supplemented by 
various types of continuous or periodic parametric monitoring, we have 
concluded that three test runs are appropriate for this final rule. 
Although we have not proposed a formal procedure to assess the 
consistency of test runs, the permitting authority performs routine 
reviews of compliance test data to identify potential outliers and 
results that suggest further investigation is needed. For example, a 
routine review tracks trends in performance, and in particular, flags 
any trends in deteriorating performance over time. An unusually high 
run among the three runs also attracts attention and would be examined 
to determine if it might have been caused by a problem with the 
process, control device, sampling, or analysis. If the permitting 
authority identifies inconsistent runs, they have the authority to 
invalidate any or all runs. A source would be required to perform more 
runs to provide reliable data if two to three runs were invalidated.
    We agree with the commenter that the degree of variability used in 
the development of the proposed new source MACT standard for the ore 
pretreatment group appeared to be inconsistent with the degree of 
variability used in the development of the proposed new source MACT 
standard for carbon processes and non-carbon concentrate processes. We 
agree with the commenter that the ore pretreatment degree of 
variability at proposal for new sources was higher than the degree of 
variability for existing sources. We do not believe that the 
variability was higher because low thermal units (i.e., autoclaves) 
were included in the same category, but because two tests of the ore 
preheater/dry grinding processes at Goldstrike were allowed in the data 
set. These tests had, as the commenter identified, inconsistently high 
emissions (as compared to other tests at other times for the same 
units) and inconsistent variability between the runs. We have 
determined that the tests the commenter is referring to are not 
representative of normal operation, and those tests have been removed 
from our database because the NDEP invalidated the tests due to 
possible sample contamination. (See the MACT Floor Document in the 
docket for the final rulemaking for more details). We continue to use 
Goldstrike as the best performing source for the ore pretreatment new 
source MACT, and the variability for new source MACT is now less than 
that of the variability for existing source MACT, and is less than the 
variability calculated at the time of proposal.
2. General Comments on MACT
    Comment: Some commenters stated that the MACT floor already 
represents installation and operation of MACT controls, and the use of 
emissions data from facilities that are already controlling their 
mercury emissions creates an artificially low MACT floor. The 
commenters said that the low MACT floor penalizes facilities that 
voluntarily invested in pollution control technology and creates a 
substantial disincentive for industry and States to move ahead of EPA 
in reducing emissions of HAP.
    Response: We acknowledged at proposal that many gold mine 
facilities are already well controlled for many

[[Page 9464]]

reasons, including participation in the NMCP. We also acknowledge that 
the top performing facilities that are the basis for the MACT floor 
calculation are the top performers because they have installed 
controls. CAA section 112(d)(3)(B) requires that, for a category with 
fewer than 30 sources, the MACT floor not be less stringent than ``the 
average emission limitation achieved by the best performing 5 sources 
(for which the Administrator has or could reasonably obtain emission 
information).'' (Emphasis added). EPA has information on the well-
controlled facilities and used the information to conduct MACT floor 
analysis, as required by the CAA. Although the MACT floor may be 
considered more stringent in comparison to floors that would have been 
established if no facilities had mercury emission controls, we do not 
consider the floor to be ``artificially low'' because consistent with 
the statute, it reflects the level achieved in practice by the best 
performing sources. See 112(d)(3). We do not believe that the MACT 
floor penalizes facilities that invested in pollution control 
technology because those facilities will be able to meet the MACT 
standards. We do not consider that this final rule creates a 
disincentive for industry and States to move ahead of EPA in reducing 
HAP emissions because as facilities reduce mercury emissions by adding 
controls required by State programs, they will be able to meet the 
NESHAP. Most of the facilities that will not meet the current final 
standards have already proposed to add controls to their units in their 
Phase 2 applications for the NMCP.
3. MACT for the Ore Pretreatment Group
    Comment: Several commenters supported EPA's general approach to 
establish three groups of affected sources in the proposal. On the 
other hand, several commenters suggested that EPA develop separate 
emission standards for roasters and autoclaves for existing and new 
sources. One commenter stated that roaster and autoclave processes are 
different from each other based on the mercury species released, 
controls utilized, and their rates of mercury emissions. The commenter 
said that roasters commonly reach temperatures of 400[deg] to 
700[deg]C, releasing gaseous elemental mercury, whereas autoclaves 
commonly reach temperatures of 175[deg] to 230[deg]C producing reactive 
gaseous mercury and sulfate and forming mercury sulfate. According to 
the commenter, autoclaves are expected to be able to improve efficiency 
over time. The commenter noted that roasters produce one to two orders 
of magnitude higher emissions than do autoclaves. The commenter 
believes that facilities that only use autoclaves should not be allowed 
the leeway to emit at the rate that facilities employing roasters are 
allowed. The commenter recommends that the ore pretreatment group be 
divided into high temperature pretreatment processes (roasters) and low 
temperature pretreatment processes (autoclaves and ancillary roaster 
processes, such as dry grinding, pre-heating, and quenching).
    Response: We discussed in section V.A. of the preamble to the 
proposed rule our rationale for establishing the different affected 
sources, including the ore pretreatment processes affected source. We 
believe it is appropriate to maintain the ore pretreatment group 
affected source, as we had proposed. We do not agree with the comment 
that roasters necessarily have higher emissions that are one to two 
orders of magnitude higher than emission from autoclaves. The available 
data show a wide range in emissions from autoclaves (from 0.4 to 115 
lb/million tons of ore). This range overlaps the range for roasters and 
their ancillary equipment, which have combined emissions between 42 to 
71 lb/million tons of ore. Regardless of the mercury species released, 
controls utilized, operating temperatures, or control efficiency over 
time, autoclaves and roasters process the same input material (i.e., 
ore) and are intended for the same purpose (i.e., to oxidize the ore). 
Therefore, we believe that it is appropriate to maintain the ore 
pretreatment affected source as we had proposed, keeping roasting 
operations and autoclaves together.
    Comment: One commenter stated that EPA failed to consider beyond-
the-floor standards for roasters and that if additional reductions are 
achievable at roasters, then EPA must set additional beyond-the-floor 
standards for roasters.
    A commenter also stated that although EPA's standard for new ore 
pretreatment facilities is as high as its standard for existing 
facilities, EPA does not propose or discuss setting beyond-the-floor 
standards for new sources. The commenter claims that EPA has a 
statutory obligation to ensure that its new source standards reflect 
the maximum achievable reduction in emissions.
    Response: Following proposal, we continued to investigate the 
performance of facilities with ore pretreatment processes and 
opportunities for additional control. We collected data from more 
recent tests that were not available at proposal, and these new data 
show that emission control performance at these facilities has 
continued to improve. We identified two previous tests in the proposal 
database that were suspect, and we confirmed with NDEP that these tests 
should be invalidated and not used in the analysis because of possible 
sample contamination. We have also dropped the data for one facility 
from the analysis because their autoclave was shutdown in 2007 and 
dismantled, and we only had one test of the autoclave when it was 
operating in 2006. For these reasons, we did not include data for that 
facility in the analysis, which is now based on the only four 
facilities currently operating.
    Based on the addition and change described above with respect to 
our available data, we revised the MACT floor analysis for the ore 
pretreatment processes. The revised MACT floor for existing sources 
decreased from 175 lb/million tons at proposal to 158 lb/million tons, 
and the new source MACT floor dropped from 163 lb/million tons to 84 
lb/million tons.
    The MACT floor limit for existing ore pretreatment processes is 
based on the use of calomel-based mercury scrubbers on roasters and wet 
scrubbers on autoclaves and ancillary roaster operations. We conducted 
a beyond-the-floor analysis during the development of the proposed 
rule. The roasters were already equipped with very good mercury 
controls (condensers and calomel-based mercury scrubbers), and we did 
not identify any beyond-the-floor options for the roasters. However, we 
identified as a beyond-the-floor control for autoclaves the 
installation of both a refrigeration unit (or condenser) and a carbon 
adsorber. We continue to believe that the roasters stacks are well 
controlled, but since our proposal, we have identified a beyond-the-
floor control option (carbon adsorption) for the ore pre-heaters/dryers 
(ancillary roaster operation) that could achieve additional emissions 
reductions of approximately 70 percent (or more) for those units. Two 
of the three facilities with roasters have already proposed in their 
NMCP Phase 2 permit applications to apply controls to their preheaters/
ore dryers, and these two companies have submitted cost estimates for 
applying a carbon adsorption system. Using the cost estimates submitted 
by the affected facilities, we estimate the capital costs for control 
of roaster preheaters/dryers for the three facilities with roasters as 
$3 million with a total annualized cost of $1.6 million per year. We 
also estimate a reduction of 118 lb/yr of mercury emissions would be 
achieved at an overall cost effectiveness of about $13,800 per pound of 
mercury. We

[[Page 9465]]

believe that these costs and cost effectiveness are reasonable. As 
required under CAA section 112(d)(2), we have also considered non-air 
quality health and environmental impacts and energy requirements of 
this additional control. We conclude that this is an acceptable beyond-
the-floor control technology for existing roaster preheaters/ore 
dryers. Therefore, we included the beyond-the-floor control for ore 
preheaters/dryers, as well as the beyond-the-floor control for 
autoclaves, in determining the MACT standard in this final rule for 
existing sources of ore pre-treatment processes. After applying the 
appropriate variability analyses to the data, we determined that the 
MACT standard for existing sources is 127 lb/million tons of ore.
    As mentioned above, we have revised the new source MACT floor. We 
also did a beyond-the-floor analysis for new sources in the ore pre-
treatment processes group. However, we did not establish the MACT 
standard for new sources based on this beyond-the-floor analysis 
because we did not identify a feasible and cost-effective option to 
achieve reductions greater than the new source MACT floor. Therefore, 
for new sources of ore pretreatment processes, the MACT ``floor'' is 
the MACT standard for the affected source. The final new source MACT 
standard is 84 lb/million tons of ore, which is considerably more 
stringent compared to the proposed standard of 149 lb/million tons of 
ore and reflects the maximum achievable reduction in emissions.
    Comment: One commenter stated that the proposed estimated capital 
costs of $890,000 and total annualized cost of $720,000 for beyond-the-
floor autoclave controls are not representative of actual costs of 
installing a refrigeration unit (or condenser) and a carbon adsorber on 
autoclaves. The commenter estimates that capital costs for autoclave 
controls will range from $18 million to at least $30 million, and 
annual operating costs could range from $2 million to $60 million, 
depending on which controls, if any, are determined to be technically 
feasible. The commenter believes that based on these cost estimates, 
beyond-the-floor MACT controls would be cost prohibitive and are not 
justified for the ore pretreatment affected source group.
    Another commenter estimated that for the installation of carbon 
adsorbers on their autoclaves to control mercury emissions, the capital 
costs would range from $30 million to $35 million, annual operating 
costs would be $2 million per year, and the annual energy requirements 
would be 11,400 megawatt-hours per year with an annual energy cost of 
$900,000.
    Response: After reviewing the new cost estimates provided by the 
commenters, we agree that capital and total annualized cost estimates 
of the beyond-the-floor controls on autoclaves in the proposal were 
underestimated. We evaluated the detailed cost estimate based on an 
engineering study for a carbon adsorption system provided by one of the 
commenters (see details in the comment above on capital, operating, and 
energy costs), and our review of these details indicates it to be a 
reasonable cost estimate and more representative. Therefore, we have 
used this estimate as the basis for our estimate of the costs of the 
beyond-the-floor mercury emission controls for autoclaves. Our revised 
estimates are that the capital cost for installing carbon adsorbers on 
autoclaves would be $29.3 million, with a total annualized cost of $4.9 
million per year, which would result in an estimated reduction of 431 
lb/yr of mercury emissions per year and an overall cost effectiveness 
of about $11,000 per pound of mercury. Based on these new costs and 
estimated reductions we conclude that the beyond the floor controls are 
affordable and justified for the ore pretreatment affected source.
    Comment: Several commenters noted that, at the proposed new source 
MACT limit of 149 pounds/million tons of ore, the proposed new source 
Donlin Creek Mine, located in Alaska, would be allowed to emit 3,200 
lb/yr of mercury based on a projected production rate of 22 million 
tons/yr of ore.
    Response: With respect to this proposed new gold mine in Alaska, 
the commenters' estimate of 3,200 lb/yr of mercury emissions is 
inaccurate and a significant overestimate for a number of reasons. The 
two primary reasons are that, based on available information, if the 
facility is built, only an estimated 15 percent of the ore mined will 
be processed in autoclaves (not 100 percent as assumed by the 
commenters), and that the commenters' estimate is based on assuming 
that the average emissions level for the facility throughout the year 
would be at the maximum allowed at the proposed new source limit (149 
lb/million tons of ore), which has been significantly reduced since 
proposal.
    With the new source MACT standard in the final rule that is about 
two times more stringent (i.e., lower) than the proposed MACT standard, 
along with corrections described above, we estimate that far less than 
3,200 lb/yr would be emitted from this new source if it is ever built. 
Assuming continuous operation for 365 days per year, an estimated 21.5 
million tons/yr of ore mined, about 3.2 million tons/yr processed in 
autoclaves (15 percent), and assuming the source would emit at the 
average emission level used to calculate the revised new source MACT 
(45 lb/million tons of ore), we calculate that mercury emissions would 
be about 144 lb/yr, which is about 5 percent of the estimate provided 
by the commenters. Considering that the facility has yet to go through 
the permitting process and that, if it is built, it will likely include 
emissions controls that would reduce the emissions below 45 lb/million 
tons of ore, we believe that, if the facility is built, emissions would 
quite likely be lower than 144 lb/yr.
4. MACT for Carbon Processes
    Comment: Several commenters objected to including Facility M in the 
MACT floor determination for new and existing sources in the carbon 
processes affected source because it is not representative of, or 
similar to, other sources, because it has unusually low mercury 
concentrations in its ore, and no need for a retort to remove and 
recover mercury. They noted that, because the mercury content of the 
gold ore is fixed, the only way for other facilities to reduce 
emissions of mercury is to apply mercury emission controls, but, for 
many facilities, emission controls will not be enough to meet the 
proposed MACT standard. The commenters stated they were aware that the 
DC Circuit Court had constrained EPA's discretion to set floors that 
fail to consider material inputs, but they said gold mines were 
different from the remanded source categories (brick kilns and cement 
kilns) because gold mining operations process very large quantities of 
ore, and the ore is the only material input that results in mercury 
emissions. The commenters stated that, in adopting section 112, 
Congress expressly cautioned EPA against setting standards that would 
require mining operations to change the ore used as essential 
feedstock. The commenters said that, by ignoring the mercury content in 
the ore being mined and processed at the facilities in the MACT floor 
determination, EPA is requiring facilities to consider the substitution 
of, or changes in, the ore that is processed because there is no other 
way to achieve the standard. The commenters recommended that EPA 
address, as a threshold matter, the differences in processing and 
emissions across facilities that result from the variable concentration 
of mercury in ore. The commenters recommended that Facility M not be 
considered the ``best controlled similar source'' for purposes of 
setting the new source MACT floor because the

[[Page 9466]]

facility is not similar to other sources. The commenters stated that, 
if EPA does not exclude from the source category facilities that do not 
use retorts to process concentrate, then they should subcategorize 
them.
    Response: After consideration of comments and a re-examination of 
the design of the facilities at issue, the emission controls, and other 
factors affecting emissions from the carbon processes at Facility M, we 
agree that this facility is quite different and unique compared to most 
other gold mine ore processing and production facilities, including 
other facilities in Nevada, in its carbon process. The difference is 
manifested in the processing train in that mercury retorts are not 
needed or used at Facility M to recover mercury. As the commenter 
notes, the CAA allows EPA to ``distinguish among classes, types and 
sizes of sources within a category'' in developing MACT emission 
standards, and gold mine facilities without mercury retorts are 
different in both class and type from those with mercury retorts. 
Accordingly, in the final rule, we identify and set separate MACT 
standards for these two different types of carbon processes: those that 
use mercury retorts; and those, such as the carbon process at Facility 
M, that do not use mercury retorts.
    As part of our re-analysis of the MACT floor and the MACT for 
sources that are in the carbon processes with mercury retorts group and 
sources that are in the carbon processes without mercury retorts group, 
we considered new data that were not available at the time of proposal. 
Over the past one to two years since our data collection effort for the 
proposal, facilities in Nevada have continued to add controls and 
improve emission control as part of the NMCP. The new data indicate 
there were two facilities with carbon processes without mercury retorts 
operating in 2009. Using the data from these two facilities, we 
determined that the MACT floor limits for carbon processes without 
mercury retorts are 0.17 lb/ton of concentrate for existing sources and 
0.14 lb/ton of concentrate for new sources (based on the best 
performing facility, Facility M).
    In our beyond-the-floor analysis, we considered the addition of a 
carbon adsorber on an uncontrolled emission unit within an existing 
affected source. We estimate the capital cost as $210,000 with a total 
annualized cost of $72,000 per year, an emission reduction of 1.63 lb/
yr of mercury, and a cost effectiveness of $44,000/lb of mercury. We do 
not believe that the small emission reduction that this control option 
would achieve is justified in light of its cost. We therefore decided 
not to go beyond-the-floor. We also considered possible beyond-the-
floor options for new carbon processes without mercury retorts, but 
concluded these options were not cost-effective or feasible. Therefore, 
for new and existing sources of carbon processes without mercury 
retorts, the MACT floor limit is the MACT standard for this affected 
source.
    As part of our re-analysis for the carbon group processes with 
mercury retorts, we collected and evaluated additional data. As 
discussed above, several of the facilities have improved emission 
control over the levels observed in the database we used at proposal. 
Two facilities with newly-installed controls replaced two higher-
emitting facilities that were in the top 5 at proposal, and all three 
of the other facilities that remained in the top 5 had lower levels of 
emissions after considering the new data. The results are that the MACT 
floor limits for carbon processes with mercury retorts are 2.2 lb/ton 
of concentrate for existing sources and 0.8 lb/ton of concentrate for 
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.

[[Page 9467]]

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.

[[Page 9468]]

    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

[[Page 9469]]

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

[[Page 9470]]

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

[[Page 9471]]

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

[[Page 9472]]

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

[[Page 9473]]

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

[[Page 9474]]

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

[[Page 9475]]

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

[[Page 9476]]

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.

[[Page 9477]]

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.

[[Page 9478]]

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

[[Page 9479]]

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),

[[Page 9480]]

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

[[Page 9481]]

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

[[Page 9482]]

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

[[Page 9483]]

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 
emissions monitoring system (CEMS) to continuously measure the mercury 
concentration in the final exhaust stream from each roaster according 
to the requirements of Performance Specification 12A (40 CFR part 60, 
appendix B) except that calibration standards traceable to the National 
Institute of Standards and Technology are not required. You must 
perform a data accuracy assessment of the CEMS according to section 5 
of Appendix F in part 60 and follow the applicable monitoring 
requirements in Sec.  63.8 as provided in Table 1 to subpart EEEEEEE.
    (i) You must continuously monitor the daily average mercury 
concentration from the roaster and maintain the daily average 
concentration below the operating limit established in paragraph (a)(4) 
of this section.
    (ii) If the daily average mercury concentration from the CEMs 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 the CEMs (40 CFR part 60, 
appendix B and Procedure 5 of appendix F) 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, and 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 results may also be used to establish a 
new operating limit for mercury concentration (in accordance with 
paragraph (e) of this section).
    (iii) You must submit a monitoring plan that includes quality 
assurance and quality control (QA/QC) procedures sufficient to 
demonstrate the accuracy of

[[Page 9484]]

the CEMS to your permitting authority for approval 180 days prior to 
your initial compliance test. At a minimum, the QA/QC procedures must 
include daily calibrations and an annual accuracy test for the CEMS.
    (3) Continuously measure the mercury concentration in the final 
exhaust stream from each roaster using EPA Performance Specification 
12B (40 CFR part 60 appendix B and Procedure 5 of appendix F).
    (i) You must continuously measure the mercury concentration in the 
roaster exhaust and maintain the average daily mercury concentration 
below the operating limit established in paragraph (a)(4) of this 
section. 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 the daily average mercury concentration 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 and 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 results may also be 
used to establish a new operating limit for mercury concentration (in 
accordance with paragraph (e) of this section).
    (4) Use Equation (2) of this section to establish an upper 
operating limit for mercury concentration as determined by using the 
procedures in paragraphs (a)(1), (a)(2), or (a)(3) of this section 
concurrently while you are conducting your annual compliance 
performance stack tests according to the procedures in Sec.  
63.11646(a).
[GRAPHIC] [TIFF OMITTED] TR17FE11.004

Where:

OLR = mercury concentration operating limit for the roaster (or 
roasters that share a common stack) (in micrograms per cubic meter);
Ctest = average mercury concentration measured by the 
monitoring procedures (PS 12A or PS 12B or 30B) during the 
compliance performance stack test (in micrograms per cubic meter);
EL = emission standard for ore pretreatment processes (in lb/million 
tons of ore);
CT = compliance test results for ore pretreatment processes (in lb/
million tons of ore).

    (5) For roasters that utilize calomel-based mercury control systems 
for emissions controls, you are not required to perform the monitoring 
for mercury emissions in paragraphs (a)(1), (a)(2), or (a)(3) of this 
section if you demonstrate to the satisfaction of your permitting 
authority that mercury emissions from the roaster are less than 10 
pounds of mercury per million tons of ore throughput. If you make this 
demonstration, you must conduct the parametric monitoring as described 
below in paragraphs (b) and (c) of this section.
    (i) The initial demonstration must include three or more 
consecutive independent stack tests for mercury at least one month 
apart on the roaster exhaust stacks. Subsequent demonstrations may be 
based upon the single stack test required in paragraph (a) of section 
Sec.  63.11646. The results of each of the tests must be less than 10 
pounds of mercury per million tons of ore. The testing must be 
performed according to the procedures in Sec.  63.11646(a)(1) through 
(a)(4) to determine mercury emissions in pounds per hour.
    (ii) Divide the mercury emission rate in pounds per hour by the ore 
throughput rate during the test expressed in millions of tons per hour 
to determine the emissions in pounds per million tons of ore.
    (b) For facilities with roasters and a calomel-based mercury 
control system that choose to monitor for mercury emissions using the 
procedures in paragraph (a)(1) of this section or that qualify for and 
choose to follow the requirements in paragraph (a)(5) of this section, 
you must establish operating parameter limits for scrubber liquor flow 
(or line pressure) and scrubber inlet gas temperature and monitor these 
parameters. You may establish your operating parameter limits from the 
initial compliance test, according to the manufacturer's 
specifications, or based on limits established by the permitting 
authority. If you choose to establish your operating parameter limits 
from the initial compliance test, monitor the scrubber liquor flow (or 
line pressure) and scrubber inlet gas temperature during each run of 
your initial compliance test. The minimum operating limit for scrubber 
liquor flow rate (or line pressure) is either the lowest value during 
any run of the initial compliance test or 10 percent less than the 
average value measured during the compliance test, and your maximum 
scrubber inlet temperature limit is the highest temperature measured 
during any run of the initial compliance test or 10 percent higher than 
the average value measured during the compliance test. You must monitor 
the scrubber liquor flow rate (or line pressure) and scrubber inlet gas 
temperature hourly and maintain the scrubber liquor flow (or line 
pressure) at or above the established operating parameter and maintain 
the inlet gas temperature below the established operating parameter 
limit.
    (c) For facilities with roasters and a calomel-based mercury 
control system that choose to monitor for mercury emissions using the 
procedures in paragraph (a)(1) of this section or that qualify for and 
follow the requirements in paragraph (a)(5) of this section, you must 
establish operating parameter ranges for mercuric ion and chloride ion 
concentrations or for oxidation reduction potential and pH using the

[[Page 9485]]

procedures in paragraph (c)(1) or (c)(2) of this section respectively.
    (1) Establish the mercuric ion concentration and chloride ion 
concentration ranges for each calomel-based mercury control system. The 
mercuric ion concentration and chloride ion concentration ranges for 
each calomel-based mercury control system must be based on the 
manufacturer's specifications, or based on approval by your permitting 
authority. Measure the mercuric ion concentration and chloride ion 
concentrations at least once during each run of your initial compliance 
test. The measurements must be within the established concentration 
range for mercuric ion concentration and chloride ion concentration. 
Subsequently, you must sample at least once daily and maintain the 
mercuric ion concentration and chloride ion concentrations within their 
established range.
    (2) Establish the oxidation reduction potential and pH range for 
each calomel-based mercury control system. The oxidation reduction 
potential and pH range for each calomel-based mercury control system 
must be based on the manufacturer's specifications, or based on 
approval by your permitting authority. Install monitoring equipment to 
continuously monitor the oxidation reduction potential and pH of the 
calomel-based mercury control system scrubber liquor. Measure the 
oxidation reduction potential and pH of the scrubber liquor during each 
run of your initial compliance test. The measurements must be within 
the established range for oxidation reduction potential and pH. 
Subsequently, you must monitor the oxidation reduction potential and pH 
of the scrubber liquor continuously and maintain it within the 
established operating range.
    (d) If you have an exceedance of a control device operating 
parameter range provided in paragraphs (b) or (c) of this section, you 
must take corrective action and bring the parameters back into the 
established parametric ranges. If the corrective actions taken 
following an exceedance do not result in the operating parameter value 
being returned within the established range within 48 hours, a mercury 
concentration measurement (with PS 12B or PS 12A CEMS (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)) must be made to determine if the operating limit for 
mercury concentration is being exceeded. The measurement must be 
performed and the mercury concentration determined within 48 hours 
(after the initial 48 hours, or a total of 96 hours from the time the 
parameter range was exceeded). If the measured mercury concentration 
meets the operating limit for mercury concentration established under 
Sec.  63.11647(a)(4), the corrective actions are deemed successful, and 
the owner or operator can request the permit authority to establish a 
new limit or range for the parameter. 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 and 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 with the MACT emission standard, the compliance test 
may also be used to establish a new operating limit for mercury 
concentration (see paragraph (e) of this section).
    (e) You may submit a request to your permitting authority for 
approval to change the operating limits established under paragraph 
(a)(4) of this section for the monitoring required in paragraph 
(a)(1),(a)(2), or (a)(3) of this section. In the request, you must 
demonstrate that the proposed change to the operating limit detects 
changes in levels of mercury emission control. An approved change to 
the operating limit under this paragraph only applies until a new 
operating limit is established during the next annual compliance test.
    (f) You must monitor each process unit at each new and existing 
affected source that uses a carbon adsorber to control mercury 
emissions using the procedures in paragraphs (f)(1) or (f)(2) of this 
section. A carbon adsorber may include a fixed carbon bed, carbon 
filter packs or modules, carbon columns, and other variations.
    (1) Continuously sample and analyze the exhaust stream from the 
carbon adsorber for mercury using Method 30B (40 CFR part 60, appendix 
A-8) for a duration of at least the minimum sampling time specified in 
Method 30B and up to one week that includes the period of the annual 
performance test.
    (i) Establish an upper operating limit for the process as 
determined using the mercury concentration measurements from the 
sorbent trap (Method 30B) as calculated from Equation (3) of this 
section.
[GRAPHIC] [TIFF OMITTED] TR17FE11.005

Where:

OLC = mercury concentration operating limit for the carbon adsorber 
control device on the process as measured using the sorbent trap, 
(micrograms per cubic meter);
Ctrap = average mercury concentration measured using the 
sorbent trap during the week that includes the compliance 
performance test, (micrograms per cubic meter);
EL = emission standard for the affected sources (lb/ton of 
concentrate);
CT = compliance test results for the affected sources (lb/ton of 
concentrate).

    (ii) Sample and analyze the exhaust stream from the carbon adsorber 
for mercury at least monthly using Method 30B (40 CFR part 60, appendix 
A-8). When the mercury concentration reaches 75 percent of the 
operating limit, begin weekly sampling and analysis. When the mercury 
concentration reaches 90 percent of the operating limit, replace the 
carbon in the carbon adsorber within 30 days. If mercury concentration 
exceeds the operating limit, change the carbon in the carbon adsorber 
within 30 days and report the deviation to your permitting authority.
    (2) Conduct an initial sampling of the carbon in the carbon bed for 
mercury 90 days after the replacement of the carbon. A representative 
sample must be collected from the inlet of the bed and the exit of the 
bed and analyzed using SW-846 Method 7471B (incorporated by reference--
see Sec.  63.14). The depth to which the sampler is inserted must be 
recorded. The design capacity is established by calculating the average 
carbon loading from the inlet and outlet measurements. Sampling and 
analysis

[[Page 9486]]

of the carbon bed for mercury must be performed quarterly thereafter. 
When the carbon loading reaches 50 percent of the design capacity of 
the carbon, monthly sampling must be performed until 90 percent of the 
carbon loading capacity is reached. The carbon must be removed and 
replaced with fresh carbon no later than 30 days after reaching 90 
percent of capacity. For carbon designs where there may be multiple 
carbon columns or beds, a representative sample may be collected from 
the first and last column or bed instead of the inlet or outlet. If the 
carbon loading exceeds the design capacity of the carbon, change the 
carbon within 30 days and report the deviation to your permitting 
authority.
    (g) You must monitor gas stream temperature at the inlet to the 
carbon adsorber for each process unit (i.e., carbon kiln, melt furnace, 
etc.) equipped with a carbon adsorber. Establish a maximum value for 
the inlet temperature either during the annual performance test 
(required in Sec.  63.11646(a)), according to the manufacturer's 
specifications, or as approved by your permitting authority. If you 
choose to establish the temperature operating limit during the 
performance test, establish the temperature operating limit based on 
either the highest reading during the test or at 10[deg]F higher than 
the average temperature measured during the performance test. Monitor 
the inlet temperature once per shift. If an inlet temperature exceeds 
the temperature operating limit, you must take corrective actions to 
get the temperature back within the parameter operating limit within 48 
hours. If the exceedance persists, within 144 hours of the exceedance, 
you must sample and analyze the exhaust stream from the carbon adsorber 
using Method 30B (40 CFR part 60, appendix A-8) and compare to an 
operating limit (calculated pursuant to (f)(1)(i)) or you must conduct 
carbon sampling pursuant to (f)(2) of this section. If the 
concentration measured with Method 30B is below 90 percent of the 
operating limit or the carbon sampling results are below 90 percent of 
the carbon loading capacity, you may set a new temperature operating 
limit 10[deg]F above the previous operating limit or at an alternative 
level approved by your permit authority. If the concentration is above 
90 percent of the operating limit or above 90 percent of the carbon 
loading capacity you must change the carbon in the bed within 30 days 
and report the event to your permitting authority, and reestablish an 
appropriate maximum temperature limit based on approval of your permit 
authority.
    (h) For each wet scrubber at each new and existing affected source 
not followed by a mercury control system, you must monitor the water 
flow rate (or line pressure) and pressure drop. Establish a minimum 
value as the operating limit for water flow rate (or line pressure) and 
pressure drop either during the performance test required in Sec.  
63.11646(a), according to the manufacturer's specifications, or as 
approved by your permitting authority. If you choose to establish the 
operating limit based on the results of the performance test, the new 
operating limit must be established based on either the lowest value 
during any test run or 10 percent less than the average value measured 
during the test. For wet scrubbers on an autoclave, establish the 
pressure drop range according to manufacturer's specifications. You 
must monitor the water flow rate and pressure drop once per shift and 
take corrective action within 24 hours if any daily average is less 
than the operating limit. If the parameters are not in range within 72 
hours, the owner or operator must report the deviation to the 
permitting authority and perform a compliance test for the process 
unit(s) controlled with the wet scrubber that has the parameter 
exceedance within 40 days to determine if the affected source is in 
compliance with the MACT limit. For the other process units included in 
the affected source, the owner or operator can use the results of the 
previous compliance test to determine the emissions for those process 
units to be used in the calculations of the emissions for the affected 
source.
    (i) You may conduct additional compliance tests according to the 
procedures in Sec.  63.11646 and re-establish the operating limits 
required in paragraphs (a) through (c) and (f) through (h) of this 
section at any time. You must submit a request to your permitting 
authority for approval to re-establish the operating limits. In the 
request, you must demonstrate that the proposed change to the operating 
limit detects changes in levels of mercury emission control. An 
approved change to the operating limit under this paragraph only 
applies until a new operating limit is established during the next 
annual compliance test.

Sec.  63.11648  What are my notification, reporting, and recordkeeping 
requirements?

    (a) You must submit the Initial Notification required by Sec.  
63.9(b)(2) no later than 120 calendar days after the date of 
publication of the final rule in the Federal Register or within 120 
days after the source becomes subject to the standard. The Initial 
Notification must include the information specified in Sec.  
63.9(b)(2)(i) through (b)(2)(iv).
    (b) You must submit an initial Notification of Compliance Status as 
required by Sec.  63.9(h).
    (c) If a deviation occurs during a semiannual reporting period, you 
must submit a deviation report to your permitting authority according 
to the requirements in paragraphs (c)(1) and (2) of this section.
    (1) The first reporting period covers the period beginning on the 
compliance date specified in Sec.  63.11641 and ending on June 30 or 
December 31, whichever date comes first after your compliance date. 
Each subsequent reporting period covers the semiannual period from 
January 1 through June 30 or from July 1 through December 31. Your 
deviation report must be postmarked or delivered no later than July 31 
or January 31, whichever date comes first after the end of the 
semiannual reporting period.
    (2) A deviation report must include the information in paragraphs 
(c)(2)(i) through (c)(2)(iv) of this section.
    (i) Company name and address.
    (ii) Statement by a responsible official, with the official's name, 
title, and signature, certifying the truth, accuracy and completeness 
of the content of the report.
    (iii) Date of the report and beginning and ending dates of the 
reporting period.
    (iv) Identification of the affected source, the pollutant being 
monitored, applicable requirement, description of deviation, and 
corrective action taken.
    (d) If you had a malfunction during the reporting period, the 
compliance report required in Sec.  63.11648(b) must include the 
number, duration, and a brief description for each type of malfunction 
which occurred during the reporting period and which caused or may have 
caused any applicable emission limitation to be exceeded. The report 
must also include a description of actions taken by an owner or 
operator during a malfunction of an affected source to minimize 
emissions in accordance with Sec.  63.11646(b), including actions taken 
to correct a malfunction.
    (e) You must keep the records specified in paragraphs (e)(1) 
through (e)(3) of this section. The form and maintenance of records 
must be consistent with the requirements in section 63.10(b)(1) of the 
General Provisions.
    (1) As required in Sec.  63.10(b)(2)(xiv), you must keep a copy of 
each

[[Page 9487]]

notification that you submitted to comply with this subpart and all 
documentation supporting any Initial Notification, Notification of 
Compliance Status, and semiannual compliance certifications that you 
submitted.
    (2) You must keep the records of all performance tests, 
measurements, monitoring data, and corrective actions required by 
Sec. Sec.  63.11646 and 63.11647, and the information identified in 
paragraphs (c)(2)(i) through (c)(2)(vi) of this section for each 
corrective action required by Sec.  63.11647.
    (i) The date, place, and time of the monitoring event requiring 
corrective action;
    (ii) Technique or method used for monitoring;
    (iv) Operating conditions during the activity;
    (v) Results, including the date, time, and duration of the period 
from the time the monitoring indicated a problem to the time that 
monitoring indicated proper operation; and
    (vi) Maintenance or corrective action taken (if applicable).
    (3) You must keep records of operating hours for each process as 
required by Sec.  63.11646(a)(5) and records of the monthly quantity of 
ore and concentrate processed or produced as required by Sec.  
63.11646(a)(10).
    (f) Your records must be in a form suitable and readily available 
for expeditious review, according to Sec.  63.10(b)(1). As specified in 
Sec.  63.10(b)(1), you must keep each record for 5 years following the 
date of each recorded action. You must keep each record onsite for at 
least 2 years after the date of each recorded action according to Sec.  
63.10(b)(1). You may keep the records offsite for the remaining 3 
years.
    (g) After December 31, 2011, within 60 days after the date of 
completing each performance evaluation conducted to demonstrate 
compliance with this subpart, the owner or operator of the affected 
facility must submit the test data to EPA by entering the data 
electronically into EPA's WebFIRE data base through EPA's Central Data 
Exchange. The owner or operator of an affected facility shall enter the 
test data into EPA's data base using the Electronic Reporting Tool or 
other compatible electronic spreadsheet. Only performance evaluation 
data collected using methods compatible with ERT are subject to this 
requirement to be submitted electronically into EPA's WebFIRE database.

Other Requirements and Information

Sec.  63.11650  What General Provisions apply to this subpart?

    Table 1 to this subpart shows which parts of the General Provisions 
in Sec. Sec.  63.1 through 63.16 apply to you.

Sec.  63.11651  What definitions apply to this subpart?

    Terms used in this subpart are defined in the Clean Air Act, in 
Sec.  63.2, and in this section as follows:
    Autoclave means a pressure oxidation vessel that is used to treat 
gold ores (primarily sulfide refractory ore) and involves pumping a 
slurry of milled ore into the vessel which is highly pressurized with 
oxygen and heated to temperatures of approximately 350[deg] to 430[deg] 
F.
    Calomel-based mercury control system means a mercury emissions 
control system that uses scrubbers to remove mercury from the gas 
stream of a roaster or combination of roasters by complexing the 
mercury from the gas stream with mercuric chloride to form mercurous 
chloride (calomel). These scrubbers are also referred to as ``mercury 
scrubbers.''
    Carbon adsorber means a control device consisting of a single fixed 
carbon bed, multiple carbon beds or columns, carbon filter packs or 
modules, and other variations that uses activated carbon to remove 
pollutants from a gas stream.
    Carbon kiln means a kiln or furnace where carbon is regenerated by 
heating, usually in the presence of steam, after the gold has been 
stripped from the carbon.
    Carbon processes with mercury retorts means the affected source 
that includes carbon kilns, preg tanks, electrowinning cells, mercury 
retorts, and melt furnaces at gold mine ore processing and production 
facilities that use activated carbon, or resins that can be used as a 
substitute for activated carbon, to recover (adsorb) gold from the 
pregnant cyanide solution.
    Carbon processes without mercury retorts means the affected source 
that includes carbon kilns, preg tanks, electrowinning cells, and melt 
furnaces, but has no retorts, at gold mine ore processing and 
production facilities that use activated carbon, or resins that can be 
used as a substitute for activated carbon, to recover (adsorb) gold 
from the pregnant cyanide solution.
    Concentrate means the sludge-like material that is loaded with gold 
along with various other metals (such as silver, copper, and mercury) 
and various other substances, that is produced by electrowinning, the 
Merrill-Crowe process, flotation and gravity separation processes. 
Concentrate is measured as the input to mercury retorts, or for 
facilities without mercury retorts, as the input to melt furnaces 
before any drying takes place. For facilities without mercury retorts 
or melt furnaces, concentrate is measured as the quantity shipped.
    Deviation means any instance where an affected source subject to 
this subpart, or an owner or operator of such a source:
    (1) Fails to meet any requirement or obligation established by this 
subpart, including but not limited to any emissions limitation or work 
practice standard;
    (2) Fails to meet any term or condition that is adopted to 
implement an applicable requirement in this subpart and that is 
included in the operating permit for any affected source required to 
obtain such a permit; or
    (3) Exceeds any operating limit established under this subpart.
    Electrowinning means a process that uses induced voltage on anode 
and cathode plates to remove metals from the continuous flow of 
solution, where the gold in solution is plated onto the cathode. Steel 
wool is typically used as the plating surface.
    Electrowinning Cells means a tank in which the electrowinning takes 
place.
    Gold mine ore processing and production facility means any 
industrial facility engaged in the processing of gold mine ore that 
uses any of the following processes: Roasting operations, autoclaves, 
carbon kilns, preg tanks, electrowinning, mercury retorts, or melt 
furnaces. Laboratories (see CAA section 112(c)(7)), individual 
prospectors, and very small pilot scale mining operations that 
processes or produces less than 100 pounds of concentrate per year are 
not a gold mine ore processing and production facility. A facility that 
produces primarily metals other than gold, such as copper, lead, zinc, 
or nickel (where these metals other than gold comprise 95 percent or 
more of the total metal production) that may also recover some gold as 
a byproduct is not a gold mine ore processing and production facility. 
Those facilities whereby 95 percent or more of total mass of metals 
produced are metals other than gold, whether final metal production is 
onsite or offsite, are not part of the gold mine ore processing and 
production source category.
    Melt furnace means a furnace (typically a crucible furnace) that is 
used for smelting the gold-bearing material recovered from mercury 
retorting, or the gold-bearing material from electrowinning, the 
Merrill-Crowe

[[Page 9488]]

process, or other processes for facilities without mercury retorts.
    Mercury retort means a vessel that is operated under a partial 
vacuum at approximately 1,100 [deg] to 1,300 [deg]F to remove mercury 
and moisture from the gold bearing sludge material that is recovered 
from electrowinning, the Merrill-Crowe process, or other processes. 
Mercury retorts are usually equipped with condensers that recover 
liquid mercury during the processing.
    Merrill-Crowe process means a precipitation technique using zinc 
oxide for removing gold from a cyanide solution. Zinc dust is added to 
the solution, and gold is precipitated to produce a concentrate.
    Non-carbon concentrate processes means the affected source that 
includes mercury retorts and melt furnaces at gold mine ore processing 
and production facilities that use the Merrill-Crowe process or other 
processes and do not use carbon (or resins that substitute for carbon) 
to recover (adsorb) gold from the pregnant cyanide solution.
    Ore dry grinding means a process in which the gold ore is ground 
and heated (dried) prior to additional preheating or prior to entering 
the roaster.
    Ore preheating means a process in which ground gold ore is 
preheated prior to entering the roaster.
    Ore pretreatment processes means the affected source that includes 
roasting operations and autoclaves that are used to pre-treat gold mine 
ore at gold mine ore processing and production facilities prior to the 
cyanide leaching process.
    Pregnant solution tank (or preg tank) means a storage tank for 
pregnant solution, which is the cyanide solution that contains gold-
cyanide complexes that is generated from leaching gold ore with cyanide 
solution.
    Pregnant cyanide solution means the cyanide solution that contains 
gold-cyanide complexes that are generated from leaching gold ore with a 
dilute cyanide solution.
    Quenching means a process in which the hot calcined ore is cooled 
and quenched with water after it leaves the roaster.
    Roasting operation means a process that uses an industrial furnace 
in which milled ore is combusted across a fluidized bed to oxidize and 
remove organic carbon and sulfide mineral grains in refractory gold 
ore. The emissions points of the roasting operation subject to this 
subpart include ore dry grinding, ore preheating, the roaster stack, 
and quenching.

Sec.  63.11652  Who implements and enforces this subpart?

    (a) This subpart can be implemented and enforced by the U.S. EPA or 
a delegated authority, such as your state, local, or tribal agency. If 
the U.S. EPA Administrator has delegated authority to your state, 
local, or tribal agency, then that agency has the authority to 
implement and enforce this subpart. You should contact your U.S. EPA 
Regional Office to find out if this subpart is delegated to your state, 
local, or tribal agency.
    (b) In delegating implementation and enforcement authority of this 
subpart to a state, local, or tribal agency under 40 CFR part 63, 
subpart E, the authorities contained in paragraph (c) of this section 
are retained by the Administrator of the U.S. EPA and are not 
transferred to the state, local, or tribal agency.
    (c) The authorities that will not be delegated to state, local, or 
tribal agencies are listed in paragraphs (c)(1) through (4) of this 
section.
    (1) Approval of alternatives to the applicability requirements in 
Sec.  63.11640, the compliance date requirements in Sec.  63.11641, and 
the applicable standards in Sec.  63.11645.
    (2) Approval of an alternative nonopacity emissions standard under 
Sec.  63.6(g).
    (3) Approval of a major change to a test method under Sec.  
63.7(e)(2)(ii) and (f). A ``major change to test method'' is defined in 
Sec.  63.90(a).
    (4) Approval of a major change to monitoring under Sec.  63.8(f). A 
``major change to monitoring'' is defined in Sec.  63.90(a).
    (5) Approval of a waiver of recordkeeping or reporting requirements 
under Sec.  63.10(f), or another major change to recordkeeping/
reporting. A ``major change to recordkeeping/reporting'' is defined in 
Sec.  63.90(a).

Sec.  63.11653  [Reserved]

Tables to Subpart EEEEEEE of Part 63

          Table 1 to Subpart EEEEEEE of Part 63--Applicability of General Provisions to Subpart EEEEEE
 [As stated in Sec.   63.11650, you must comply with the applicable General Provisions requirements according to
                                              the following table]
----------------------------------------------------------------------------------------------------------------
             Citation                      Subject           Applies to  subpart EEEEEEE         Explanation
----------------------------------------------------------------------------------------------------------------
Sec.   63.1(a)(1), (a)(2), (a)(3),  Applicability........  Yes............................
 (a)(4), (a)(6), (a)(10)-(a)(12),
 (b)(1), (b)(3), (c)(1), (c)(2),
 (c)(5), (e).
Sec.   63.1(a)(5), (a)(7)-(a)(9),   Reserved.............  No.............................
 (b)(2), (c)(3), (c)(4), (d).
Sec.   63.2.......................  Definitions..........  Yes............................
Sec.   63.3.......................  Units and              Yes............................
                                     Abbreviations.
Sec.   63.4.......................  Prohibited Activities  Yes............................
                                     and Circumvention.
Sec.   63.5.......................  Preconstruction        Yes............................
                                     Review and
                                     Notification
                                     Requirements.
Sec.   63.6(a), (b)(1)-(b)(5),      Compliance with        Yes............................
 (b)(7), (c)(1), (c)(2), (c)(5),     Standards and
 (e)(1)(iii), (f)(2), (f)(3), (g),   Maintenance
 (i), (j).                           Requirements.
Sec.   63.6(e)(1)(i) and (ii),      Startup, Shutdown and  No.............................  Subpart EEEEEEE
 (e)(3), and (f)(1).                 Malfunction                                             standards apply at
                                     Requirements (SSM).                                     all times.
Sec.   63.6(h)(1), (h)(2),          Compliance with        No.............................  Subpart EEEEEEE does
 (h)(4),(h)(5)(i), (ii), (iii) and   Opacity and Visible                                     not contain opacity
 (v), (h)(6)-(h)(9).                 Emission Limits.                                        or visible emission
                                                                                             limits.
Sec.   63.6(b)(6), (c)(3), (c)(4),  Reserved.............  No.............................
 (d), (e)(2), (e)(3)(ii), (h)(3),
 (h)(5)(iv).
Sec.   63.7, except (e)(1)........  Applicability and      Yes............................
                                     Performance Test
                                     Dates.
Sec.   63.7(e)(1).................  Performance Testing    No.............................
                                     Requirements Related
                                     to SSM.

[[Page 9489]]

 
Sec.   63.8(a)(1), (b)(1), (f)(1)-  Monitoring             Yes............................
 (5), (g).                           Requirements.
Sec.   63.8(a)(2), (a)(4), (b)(2)-  Continuous Monitoring  Yes............................  Except cross
 (3), (c), (d), (e), (f)(6), (g).    Systems.                                                references to SSM
                                                                                             requirements in
                                                                                             Sec.   63.6(e)(1)
                                                                                             and (3) do not
                                                                                             apply.
Sec.   63.8(a)(3).................  [Reserved]...........  No.............................
Sec.   63.9(a), (b)(1), (b)(2)(i)-  Notification           Yes............................
 (v), (b)(4), (b)(5), (c), (d),      Requirements.
 (e), (g), (h)(1)-(h)(3), (h)(5),
 (h)(6), (i), (j).
Sec.   63.9(f)....................  .....................  No.............................
Sec.   63.9(b)(3), (h)(4).........  Reserved.............  No.............................
Sec.   63.10(a), (b)(1),            Recordkeeping and      Yes............................
 (b)(2)(vi)-(xiv), (b)(3), (c),      Reporting
 (d)(1)-(4), (e), (f).               Requirements.
Sec.   63.10(b)(2)(i)-(v), (d)(5).  Recordkeeping/         No.............................
                                     Reporting Associated
                                     with SSM.
Sec.   63.10(c)(2)-(c)(4), (c)(9).  Reserved.............  No.............................
Sec.   63.11......................  Control Device         No.............................
                                     Requirements.
Sec.   63.12......................  State Authority and    Yes............................
                                     Delegations.
Sec.  Sec.   63.13-63.16..........  Addresses,             Yes............................
                                     Incorporation by
                                     Reference,
                                     Availability of
                                     Information,
                                     Performance Track
                                     Provisions.
----------------------------------------------------------------------------------------------------------------

[FR Doc. 2011-2608 Filed 2-16-11; 8:45 am]
BILLING CODE 6560-50-P