### 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 fi le: Gold_Mine_Draft

- Preamble_ EO 12866 Review Comments.docx)

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 code 1 Examples of regulated E ntities Industry:

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 gro unds 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 s ubmit a Petition for Reconsideration

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 existi ng ore pretreatment processes include calomel mercury scrubbers on roasters and venturi scrubbers on autoclaves andancillary 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?

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 4 the 4 facilities 84

99% UPL existing (MACT Floor) 15 8 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 3 7 D 49 E 5 8 A 8 0 Highest Average 8 0 99% UPL existing ( BTF Floor) 12 7

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. Plea se confirm which value is correct. Comment [ A 8 ]: 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 possib le.

Comment [ A 10 ]: Why are the facilities here listed in a different order?

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 contro ls 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 0.14lb/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 [A 11 ]: Shouldn’t there be some discussion of how many facilities there were. Table 3 has 9. RIA has 10

Comment [ A 12 ]: Please provide footnote citation/link

## Summary of interagency review comments under EO12866 Subject to further policy review

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

Retort s Facility Average performance (lb/ton of concentrate ) N 0.53 J 0.74 I 1.06 A 1.47

## Summary of interagency review comments under EO12866 Subject to further policy review

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

Retort s Facility Average performance (lb/ton of concentrate ) M 0.0 58 F 0.0 9 8 Average of top 2 0.0 78 99% UPL existing (MACT Floor) 0. 1 7 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 o f 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 [ A 13 ]: See previous comments regarding clarifying what this mean s.

Comment [ A 14 ]: Weren’t these the only two? This should be clarified/discussed.

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 [A 15 ]: Only two?

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 a re 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.

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 emission s: 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 cont inuous 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. W e 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 Monitoring Requirements

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 allow s hourly monitoring of the line pressure in the scrubber liquid supply line as an alternative to hourly monitoring of scrubber

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 th e 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 short

term 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

## Summary of interagency review comments under EO12866 Subject to further policy review

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

## Summary of interagency review comments under EO12866 Subject to further policy review

**Draft –**  **Deliberative Document for Internal**  **EPA Review (11/2/10)**  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 h ave 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 l ine 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.