From: "King, Heidi R." <Heidi_R._King@omb.eop.gov> 

 

To: Chuck French/RTP/USEPA/US@EPA 

 

Date: 12/08/2010 03:44 PM 

 

Subject: EO 12866 Interagency Review comments on Gold Mine Draft Final 

 

Chuck,

I did receive a few comments today on Gold Mines preamble. I provide them here, 

hopefully a little easier to address as they are combined in a markup on the 

draft under review.

A few more comments will follow later today, but given the short review timeline 

I did not want to wait before passing these along.

Best,

Heidi

(202) 395-4551

(See attached file: Gold_Mine_Draft-Preamble_ EO 12866 Review Comments.docx)
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6560-50-P 

ENVIRONMENTAL PROTECTION AGENCY 

40 CFR Parts 9 and 63

[EPA-HQ-OAR-2010-0239; FRL-9140-7] 

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. EPA proposed these 

actions on April 28, 2010 (75 FR 22470). 

DATES: This final rule is effective on [INSERT DATE 60 DAYS 

AFTER PUBLICATION IN THE FEDERAL REGISTER]. 

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 www.regulations.gov website. 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 
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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. Summary of Significant Changes Since Proposal 
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A. Applicability 

B. Final Emission Standards 

C. Compliance Dates 

D. Compliance Requirements 

E. Monitoring Requirements 

F. Definitions 

IV. Summary of Responses to Major Comments 

A. Statutory Requirements 

B. Applicability 

C. MACT Floors 

D. Compliance Determinations 

E. Monitoring 

V. Summary of Environmental, Economic and Health Benefits? 

VI. 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 Information60 

A. Does this action apply to me

 The regulated categories and entities potentially affected 

by this final rule include: 

? 

Category NAICS 

code1

Examples of regulated 

Entities

Industry:
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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: 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: 

? 
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www.epa.gov/ttn/oarpg/. The TTN provides information and 

technology exchange in various areas of air pollution control. 

C. 

 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 Appeals for the 

District of Columbia Circuit by [INSERT DATE 60 DAYS AFTER 

PUBLICATION IN FEDERAL REGISTER]. 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 

Judicial Review

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 
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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. 

III. 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 IV of this preamble. 

A. 

 We have clarified in §63.11651 of the final rule that the 

term "gold mine ore processing and production facility" does not 

include laboratories (see CAA section 112(c)(7)) , individual 

prospectors, and very small pilot scale mining operations. The 

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 gold mine ore processing and production source category. 

Applicability
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B. 

 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; (2) additional analyses in response to public comments 

on the proposed rule; 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 IV of 

this preamble. 

Final emission standards

 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; 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 

Ore Pretreatment Processes

Comment [A1]: Somewhere in this 

front section, EPA should provide a 

footnote and clear link to where 

the new test data can be found in 

the docket.

Comment [A2]: Please note where this 

analysis can be found

Comment [A3]: Since this rule needs 

to stand on its own, it may be 

helpful to present the 

requirements/statutory language for 

creating the Mact floor and beyond 

the floor standards. All that 

introduction seems to be missing 

from this preamble.

Comment [A4]: Can a citation for 

this be provided. In the TSD, it 

seems that EPA decided they were 

invalid for use? Was it EPA or 

NDEP?
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results from the database. 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. Moreover, we conducted a beyond-the-floor 

analysis for roasters, which was not included in the proposed 

rule. The new information and analyses described above are 

discussed in more detail in Section IV.C of this preamble and in 

the MACT Floor document 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/million 

tons of ore for new sources. As explained in the proposed rule 

(75 FR at 22482), the technologies for achieving the MACT floor 

for existing ore pretreatment processes include calomel mercury 

scrubbers on roasters and venturi scrubbers on autoclaves and 

ancillary roaster operations. After applying the beyond-thefloor analysis to the data, we determined the MACT limit for 

existing sources to be 127 lb/million tons of ore. For new 

sources, the MACT limit is 84 lb/million tons (which is the same 

as the MACT floor for new sources). Table 1 summarizes the MACT 

Comment [A5]: Shouldn’t there be 

some discussion of how it was 

conducted?
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floor analysis for existing and new ore pretreatment processes. 

Table 2 summarizes the results of the beyond-the-floor analysis 

for these sources. 

Table 1—MACT Floor Results for Ore Pretreatment Processes

Facility Average performance 

(lb/million tons of ore)

A 45

C 56

E 71

D 165

Average of top 4the 4 

facilities

84

99% UPL existing (MACT Floor) 158

99% UPL new (MACT Floor) 84

 

Table 2—Beyond-the-Floor Results for Ore Pretreatment Processes

Facility Average performance

(lb/million tons of ore)

C 37

D 49

E 58

A 80

Highest Average 80

99% UPL existing (BTF Floor) 127

 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 

Carbon Processes

Comment [A6]: Please use facility 

name consistent with the TSD

Comment [A7]: Briefing slides we 

were provided said 127. Please 

confirm which value is correct.

Comment [A8]: Please clarify that 

new and existing refer to new 

sources and existing sources. 

Please also provide citation and 

link to TSD where calculations are 

provided.

Comment [A9]: So the 99% UPL is the 

same as the average? How is this 

possible.

Comment [A10]: Why are the 

facilities here listed in a 

different order?
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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 removed from the data set emissions data 

based on previously uncontrolled sources that installed controls 

in 2009; for those sources, only the controlled emissions data 

were used. (see section IV 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. We considered beyondthe-floor options for these affected sources; however, we 

rejected those options because they were not cost effective. 

Additional information on the analyses performed can be found in 

the MACT Floor document in the docket for this rulemaking. 

We also eliminated in the final rule the compliance 

Comment [A11]: Shouldn’t there be 

some discussion of how many 

facilities there were. Table 3 has 

9. RIA has 10

Comment [A12]: Please provide 

footnote citation/link
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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 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 3 summarizes the results of the MACT floor analysis 

for carbon processes with mercury retorts, and Table 4 

summarizes the analysis for carbon processes without mercury 

retorts. 

Table 3—MACT Floor Results for Carbon Processes with Mercury 

Retorts

Facility Average performance

(lb/ton of concentrate)

N 0.53

J 0.74

I 1.06

A 1.47
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H 1.67

D 2.20

C 3.71

G 8.17

B 20.60

Average of top 5 1.1

99% UPL existing (MACT Floor) 2.2

99% UPL new (MACT Floor) 0.8

Table 4—MACT Floor Results for Carbon Processes without Mercury 

Retorts

Facility Average performance 

(lb/ton of concentrate)

M 0.058

F 0.098

Average of top 2 0.078

99% UPL existing (MACT Floor) 0.17

99% UPL new (MACT Floor) 0.14

For carbon processes, regardless of whether the facility 

operates a mercury retort, the MACT floor is based on control of 

mercury emissions using mercury condensers and carbon adsorbers. 

For the beyond-the-floor analysis, we considered adding a second 

carbon adsorber to the MACT floor level controls. 

 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 

Non-Carbon Concentrate Processes

Comment [A13]: See previous comments 

regarding clarifying what this 

means.

Comment [A14]: Weren’t these the 

only two? This should be 

clarified/discussed.
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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 most of the data that were 

used for the proposal. We also considered beyond-the-floor 

controls for these sources, but concluded those controls would 

not be a cost-effective option. Table 5 summarizes the results 

of the MACT floor analysis for non-carbon concentrate processes. 

Table 5—MACT Floor Results for Non-Carbon Concentrate Processes

Facility Average performance 

(lb/ton of concentrate)

K 0.047

L 0.078

Average of top 2 0.062

99% UPL existing (MACT Floor) 0.2

99% UPL new (MACT Floor) 0.1

For non-carbon concentrate processes, the MACT floor is based on 

control of mercury emissions using mercury condensers and carbon 

adsorbers. For the beyond-the-floor analysis, we considered 

adding a second carbon adsorber to the MACT floor level 

controls. 

C. 

 In the final rule, we provide in §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, 

Compliance Dates

Comment [A15]: Only two?
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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; and the consideration of installing new controls 

on the roaster preheaters, which also have not been demonstrated 

yet, 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. 

 Section 63.11646(a)(1)(v) 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 only if approved by the 

permit authority. 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 

§63.11646(a)(1). Method 29 already includes requirements for 

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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 §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 emissions 

rate used to calculate the emissions factor (lb/ton) for that 

emission point and to calculate the sum of the emissions factors 

for all emission points subject to the emission standard. If 

the resulting mercury emissions factor is greater than the 

allowable 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 
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roasters) ducted to a common control device and stack, we have 

clarified in §63.11646(a)(3) that compliance testing must be 

performed with all affected emissions units in operation, if 

this is possible. This same requirement applies to the 

establishment of operating limits for all process units. 

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 §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. 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 

§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. 
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 Because the final rule does not include the 97 percent 

reduction option that was in §63.11645(e)(2) of the proposed 

rule, we have removed from the final rule the compliance 

requirement for that option that was in §63.11646(b) of the 

proposed rule, which addressed testing the inlets and outlets 

for sources choosing that proposed option. 

E. 

 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 this monitoring 

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option. 

 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 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 

§63.11647(b), which addresses monitoring of calomel scrubbers 

that are used to control emissions from roasters. 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 
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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) to be based on the minimum flow rate (or 

line pressure) established during the initial performance test. 

It also includes two additional options for setting the 

operating limit: (1) based on the manufacturer’s specifications 

if certain types of systems are designed to operate within a 

specified range of flow rates; and (2) based on limits 

established by the permitting authority. If the facility 

chooses the first option (to establish the limits during initial 

compliance), the final rule requires the 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. This requirement takes 

into account the fact that, although initially the system may 

exhibit little variability from test run to test run, the shortterm variability in performance may increase with time. 

Additional discussion of these changes can be found in Section 

IV.E of this preamble and in the Summary of Public Comments and 

Responses document in the docket for this rulemaking. 

We have clarified the requirements for corrective action 
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following control device monitoring parameter exceedances 

specified in §63.11647(d). Under the final rule, if the 

corrective actions taken following an exceedance do not result 

in the parameter value (e.g., water flow rate, pressure drop, 

etc.) 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 §63.11647(d)) within 40 days to determine whether 

the source is in compliance with the MACT standard. We believe 
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40 days is reasonable 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 to receive the finals test 

results. 

In §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 roaster operations are 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. 

We also removed the requirement that roasters must shut down 

operations if a parameter is out of range. 

 In the final rule, §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, up to one week. The 
Summary of interagency review comments under EO12866 

Subject to further policy review

Draft – Deliberative Document for Internal EPA Review (11/2/10)

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 §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 §63.11647(h) with respect to monitoring 

of scrubbers. Under the final rule, owners or operations 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 pressure drop was outside 

the manufacturer’s recommended operating range, take corrective 

actions to return the pressure drop back in range, and record 

the corrective actions taken. At proposal, the water flow rate 
Summary of interagency review comments under EO12866 

Subject to further policy review

Draft – Deliberative Document for Internal EPA Review (11/2/10)

and pressure drop were to be monitored continuously. However, 

measuring pressure drop once per shift will provide two to three 

measurements per day, and we believe that is sufficient to 

assure proper operating 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. We have also clarified that, for 

scrubbers on autoclaves, the pressure drop parameter range 

should be established from manufacturer’s specifications only. 

F. 

 We have added a definition of carbon adsorber to §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. 

Definitions

The definition of "gold mine ore processing and production 

facility" in §63.11651 of the rule has been clarified to state 

that operations, such as prospectors, laboratories, and very 

small pilot scale mining operations, that process or produce 

less than 50 pounds of concentrate per year are excluded from 
Summary of interagency review comments under EO12866 

Subject to further policy review

Draft – Deliberative Document for Internal EPA Review (11/2/10)

the source category. These prospectors and very small pilotscale operations (that process at or below this cutoff) are 

orders of magnitude smaller than all the facilities in our 

database. These very small operations process far less material 

than the typical facility in our inventory. For example, the 21 

facilities that are in our current inventory and that we expect 

will be subject to the final rule process or produce between 

4,000 to 500,000 pounds of concentrate per year (i.e., at least 

100 times the 50 lb/yr cutoff). 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.