From: French.Chuck@epamail.epa.gov 

 

 To: King, Heidi R.

 

 Cc: Branning.Amy@epamail.epa.gov; Higgins, Cortney; 

VanLare.Paula@epamail.epa.gov; Fruh.Steve@epamail.epa.gov; Raymond, Gabrielle; 

Marinshaw, Richard

 

 Date: Thu 12/2/2010 12:36 PM

 

 Subject: Gold Mines MACT Standard - costs documents, etc....

Hi Heidi,

 As we discussed, attached are the Cost and Impacts Document and the MACT 

Document (shows the MACT Floor and "beyond the floor"

calculations). Also, as I mentioned, we made some edits to the

preamble and rule to clarify/improve some things, make some minor corrections, 

and update the text on startup, shutdown and malfunctions.

Attached is the revised preamble and rule (one version is a clean new version, 

and the other version shows the changes in "track changes").

 We will also send you information on Title V very soon.

 Please let me know if you have comments or questions.

 Thank You.

 Chuck

(See attached file: Estimate of Impacts-Final-Draft-12-1-2010.doc)

(See attached file: Gold Mine MACT Floor Document-Final-Draft-12-1-10.doc) 

(See attached file: Gold_Mine_Draft-Preamble__Final_Rule_12-2-10-clean.doc)

(See attached file: Gold_Mine_Draft-Preamble__Final_Rule_11-19-10-edits-trackchanges.doc)
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

ESTIMATES OF IMPACTS FOR THE FINAL MERCURY EMISSION STANDARDS 

FOR GOLD MINE ORE PROCESSING AND PRODUCTION

Metals and Minerals Group

Sector Policies and Programs Division

Office of Air Quality Planning and Standards

U.S. Environmental Protection Agency

Research Triangle Park, NC

Draft - November 22, 2010
2

Estimates of Impacts for the Final Mercury Emission Standards for Gold Mine Ore 

Processing and Production

1.0 Cost Estimates

This section provides a summary of the estimated costs of the final rule and background 

details on how these costs were developed. The cost components include both the cost of 

mercury emission controls and the costs associated with monitoring, reporting, and 

recordkeeping (MRR). The costs of mercury emission controls for each facility that we estimate 

will likely need to add controls to meet the emissions limits in the final MACT rule are 

summarized in Table 1. There were cases where facilities had installed new or additional 

controls on thermal process units in 2008 – 2010 as a result of the Nevada Mercury Control 

Program (NMCP). The costs of these newly-installed controls are not included in the estimates 

presented here because the controls were installed prior to the final national standard. For 

example, mercury controls were installed at Round Mountain in 2008, at Cortez in 2008 and 

2009, and at Jerritt Canyon (roasters) in 2009. 

Table 1. Estimated Cost of Mercury Emission Controls for MACT Floor

No. Facility Name Location

Hg 

reduction 

(lb/yr)

Estimates of mercury emission control costs

Total 

capital 

cost 

($2008)

Total 

O&M 

cost 

($/yr)

Total 

annual 

cost 

($/yr)

Cost 

effectiveness 

($/lb)

1 Goldstrike Elko, NV 107 658,512 135,968 198,131 1,854

2 Denton-Rawhide Fallon, NV 27 135,100 103,900 116,653 4,250

3 Florida Canyon Pershing Co., NV 87 367,868 165,382 200,109 2,305

4 Gold Quarry Carlin, NV 126 199,400 44,222 63,045 502

5 Jerritt Canyon Elko, NV 165 450,882 122,737 165,300 1,001

6 Lone Tree Valmy, NV 181 453,500 157,858 200,669 1,110

7 Midas Midas, NV 14 430,000 150,421 191,013 13,707

8 Twin Creeks Golconda, NV 636 30,064,551 2,413,109 5,239,483 8,232

Totals 1,343 32,759,813 3,293,597 6,374,404 4,746

Table 2 presents the costs of MRR and includes all of the gold mine ore processing and 

production facilities identified as having the thermal processes that would be subject to the final

rule. All of these facilities will incur additional MRR costs. The final rule provides options for 

MRR; consequently, costs are presented for a range of these MRR options that includes the 

higher and lower costs options. Details for the MRR cost estimates are provided in Section 1.2.
3

Table 2. Estimates of Costs for Monitoring, Reporting, and Recordkeeping

No. Facility Name Facility Location 

Number of stacksa Higher estimates of MRR costs Lower estimates of MRR costs

Roaste

r Other

Not in 

NVb

Monitoring 

capital

Method 29 

testing

Monitoring 

O&M

Monitoring 

total annual

Monitoring 

capital

Method 29 

testing

Monitoring 

O&M

Monitoring 

total annual

1 Goldstrike Elko, NV 2 15

 

120,000 

 

- 

 

182,061 

 

199,149 

 

200,668 

 

- 

 

78,619 107,194

2 Coeur Rochester Lovelock, NV 3

 

40,000 

 

- 

 

31,794 

 

37,490 

 

- 

 

- 

 

11,299 11,299

3 Cortez Crescent Valley, NV 6

 

40,000 

 

- 

 

62,565 

 

68,261 

 

- 

 

- 

 

21,576 21,576

4 Cripple Creek Victor, CO 3 3

 

40,000 

 

28,260 

 

31,794 

 

65,750 

 

- 

 

28,260 

 

11,299 39,559

5 Denton-Rawhide Fallon, NV 4

 

40,000 

 

- 

 

42,051 

 

47,747 

 

- 

 

- 

 

14,725 14,725

6 Echo Bay/Kettle River Republic, WA 3 3

 

40,000 

 

28,260 

 

31,794 

 

65,750 

 

- 

 

28,260 

 

11,299 39,559

7 Florida Canyon Pershing County, NV 7

 

40,000 

 

- 

 

72,822 

 

78,518 

 

- 

 

- 

 

25,001 25,001

8 Fort Knox Fairbanks, AK 2 2

 

40,000 

 

18,840 

 

21,537 

 

46,073 

 

- 

 

18,840 

 

7,873 26,713

9 Gold Quarry Carlin, NV 1 10

 

80,000 

 

- 

 

117,184 

 

128,576 

 

100,334 

 

- 

 

48,385 62,672

10 Golden Sunlight Whitehall, MT 3 3

 

40,000 

 

28,260 

 

31,794 

 

65,750 

 

- 

 

28,260 

 

11,299 39,559

11 Greens Creek Mine Greens Creek , AK 1 1

 

40,000 

 

9,420 

 

11,279 

 

26,395 

 

- 

 

9,420 

 

4,448 13,868

12 Bald Mountain Elko, NV 5

 

40,000 

 

- 

 

52,308 

 

58,004 

 

- 

 

- 

 

18,150 18,150

13 Jerritt Canyon Elko, NV 2 3

 

120,000 

 

- 

 

58,976 

 

76,064 

 

200,668 

 

- 

 

37,512 66,087

14 Lone Tree Valmy, NV 5

 

40,000 

 

- 

 

52,308 

 

58,004 

 

- 

 

- 

 

18,150 18,150

15 Marigold Valmy, NV 4

 

40,000 

 

- 

 

42,051 

 

47,747 

 

- 

 

- 

 

14,725 14,725

16 Midas Midas, NV 3

 

40,000 

 

- 

 

31,794 

 

37,490 

 

- 

 

- 

 

11,299 11,299

17 Ruby Hill Eureka, NV 4

 

40,000 

 

- 

 

42,051 

 

47,747 

 

- 

 

- 

 

14,725 14,725

18 Round Mountain

Round Mountain, 

NV 4

 

40,000 

 

- 

 

42,051 

 

47,747 

 

- 

 

- 

 

14,725 14,725

19 Twin Creeks Golconda, NV 13

 

40,000 

 

- 

 

134,365 

 

140,061 

 

- 

 

- 

 

45,555 45,555

20 Western Mesquite Brawley, CA 3 3

 

40,000 

 

28,260 

 

31,794 

 

65,750 

 

- 

 

28,260 

 

11,299 39,559

21 Wharf Resources

Lawrence County, 

SD 2 2

 

40,000

 

18,840 

 

21,537 

 

46,073 

 

- 

 

18,840 

 

7,873 26,713

Totals 5 103 17 1,040,000 160,140 1,145,905 1,454,141 501,670 160,140 439,837 671,414 a Number of stacks that must be monitored. b Stacks at facilities outside of Nevada will incur additional costs for Method 29 testing (Method 29 testing is already required in Nevada).
4

1.1 Cost of Mercury Emission Controls

The primary basis for the cost estimates are the estimates developed by the gold mine ore 

processing and production facilities in their Phase 2 applications for the NMCP.

1

 In these 

applications, individual facilities identified their process units that emit mercury and proposed 

additional controls for units that were not currently controlled. The cost estimates were based on 

applying carbon adsorbers to capture mercury emissions and were developed from the actual 

costs that had been incurred when installing those types of controls on other process units. Most 

of the facilities provided estimates of capital costs for the proposed emission control systems. 

For the few facilities that did not provide a capital cost estimate, a cost algorithm presented in the 

Phase 2 application for the Twins Creek facility was used.1 This algorithm uses the total 

installed cost ($184,000) for a carbon adsorption system with a volumetric flow rate of 2,500 

cubic feet per minute (cfm). The cost for applying carbon adsorbers to other process units was 

based on the process unit’s exhaust flow rate (cfm) scaled with an exponent of 0.6 to account for 

economy of size:

Total installed capital cost = $184,000 * (cfm/2,500)0.6

Many facilities did not provide an estimate of the annual operating and maintenance

(O&M) costs. However, when a facility estimated annual O&M costs in their Phase 2 

application, those estimates were used in this analysis. For facilities without their own sitespecific estimates, O&M cost estimates were developed based on the reported costs for other 

units that had already been equipped with carbon adsorbers. The Goldstrike facility estimated 

the annual labor costs for carbon adsorbers as $4,968/yr for operating labor, $4,752/yr for 

maintenance labor, and $106/yr for carbon replacement labor for a total of $9,826/yr.2 The 

annual material and utility costs include the cost of replacement carbon and electricity for the 

additional fan capacity needed to move the vent stream through the carbon adsorber. The 

Goldstrike facility estimated carbon replacement cost as $54,000/yr for a system designed for 

4,400 cfm, or $12.27/cfm.2 The Florida Canyon facility estimated carbon replacement costs as 

$23,541 for a 2,000 cfm system, or about $11.77/cfm.3 Carbon replacement costs presented here 

are based on the average of these two values ($12/cfm of design capacity). For the fan, Florida 

Canyon estimated annual energy costs as $3,291/yr for a 2,000 cfm system or $1.65/cfm.3 The 

combined O&M costs were then estimated based on the exhaust flow rate for each process unit 

using the following equation:

O&M costs ($/yr) = $9,826 + $13.65 * cfm.

The annualized cost of capital was estimated based on a 20-year lifetime, an interest rate 

of 7 percent, and a capital recovery factor of 0.094. The total annualized cost is estimated from 

the O&M costs plus the annualized cost of capital. Table 3 presents the estimated mercury 

emission control costs for each of the process units and provides references for the estimates.

 1 Copies of the Phase 2 applications are available at http://ndep.nv.gov/baqp/hg/clearinghouse.html. 
5

Table 3. Breakdown of Estimated Cost of Mercury Emission Controls for Affected Process 

Units for MACT Floor

No. Facility Unit Controla

Mercury 

reduction 

(lb/yr)

Flow 

(cfm)

b

Total 

capital costc

Annual 

O&M

coste

Total 

annualized 

cost

Cost 

effectiveness 

($/lb)

1 Denton Rawhide Melt furnace CA 27.4 6,500 135,1008 103,9008 116,653 4,250

2 Florida Canyon Carbon kilns CA 80.9 1,000 183,9347 82,6917 100,054 1,237

3 Florida Canyon

Electrowinning, preg 

tanks, melt furnace CA 5.9 1,000 183,9342 82,6917 100,054 16,962

4 Gold Quarry AARL carbon kiln CA 108.7 900 99,7006 22,111 31,523 290

5 Gold Quarry Zadra carbon kiln CA 16.9 900 99,7006 22,111 31,523 1,864

6 Goldstrike Carbon kilns WC, CA 106.9 4,406 658,512d 135,968 198,131 1,854

7 Jerritt Canyon Melt furnace CA 131.3 1,622 141,933d 31,966 45,365 346

8 Jerritt Canyon Carbon kiln & retort CA 33.9 5,930 308,949d 90,771 119,935 3,536

9 Lone Tree Electrowinning CA 24.3 10,000 423,0009 146,326 186,257 7,662

10 Lone Tree Preg tanks CA 156.4 125 30,50010 11,532 14,411 92

11 Twin Creeks Juniper preg tanks CA 94.5 3,085 209,0004 51,936 71,666 758

12 Twin Creeks Electrowinning CA 52.4 7,311 434,0005 109,621 150,591 2,871

13 Twin Creeks Melt furnace new CA 16.4 3,000 60,77614 50,776 56,513 3,455

14 Twin Creeks Melt furnace old CA 42.5 3,000 60,77614 50,776 56,513 1,329

15 Midas Furnace CA 13.9 10,300 430,00015 150,421 191,013 13,707

16 Twin Creeks Autoclave WC, CA 430.6 11,300 29,300,00019 2,150,000 4,904,200 11,390

Subtotal Carbon Group with Hg retorts (No. 1 through 

No. 14) 899 3,029,813 993,176 1,279,191 1,424

Subtotal Non-carbon Concentrate Group (No. 15) 14 430,000 150,421 191,013 13,707

Subtotal Ore Pretreatment Group (No. 16) 431 29,300,000 2,150,000 4,904,200 11,390

Total 1,343 32,759,813 3,293,597 6,374,404 4,746 a CA = carbon adsorber, WC = water chiller (e.g., refrigeration unit or condenser) b cfm = cubic feet per minute

c Capital costs estimates come primarily from the referenced NDEP Phase 2 applications (exceptions have footnotes). d Estimated from : $184,000 * (cfm/2,500)0.6 (see text). e Unless a reference is given, estimated from : $9,826 + $13.65 * cfm (see text).

1.2 MRR Costs

The final rule includes three monitoring options for roasters: a mercury continuous 

emission monitoring system (CEMS), continuous sorbent trap sampling, and periodic sorbent 

trap sampling. (Costs are not included for parametric monitoring of control devices because the 

facilities are already performing that monitoring as a result of State permit requirements.) The 

cost estimates for the mercury CEMS were developed using EPA's CEMS Cost Model for 

estimating CEMS costs and are summarized in Table 4.

Costs for the sorbent trap monitoring for roasters were obtained from EPA testing 

personnel and from vendor quotes for the cost of sorbent tubes and mercury analyses. The 

capital cost is estimated as $40,000 for the sampling probe, pump, moisture conditioner,

metering console, and data logger. The paired traps cost $150 each with an analysis cost of 

$200 each. The estimated labor to install the traps, leak check, and set flow rates is 4 hours or 

$206/sample (at $51.51/hr). Sampling twice per month would be required, which results in an 

annual sampling cost of $13,335/yr per stack. 
6

Table 4. Cost Estimate for a Mercury CEMS

Capital cost

CEMS equipment (analyzer, sampling line data acquisition software, etc.) $90,000

Taxes and shipping $5,400

Install and check CEMS $4,320

Initial calibration $614

Total installed capital cost $100,334

Total annualized cost

Daily operation of CEMS $4,608

Weekly checks of CEMS $2,938

Monthly checks of CEMS $2,765

Consumables $1,000

Annual QA $288

Recordkeeping and reporting $1.253

Subtotal $12,852

Capital recovery (10 years at 7%, CRF = 0.1424) $14,288

Total annualized cost $27,140

For process units other than roasters, the common mercury control device is a carbon 

adsorber. The final rule provides options for sampling carbon adsorbers: monthly sorbent trap 

sampling (except going to weekly when the adsorber reaches 75 percent of the operating limit) or 

quarterly sampling of the carbon for mercury loading (going to monthly when 50 percent of 

capacity is reached). The capital cost for the sorbent trap sampling is the same as estimated 

above ($40,000). The annual cost is also estimated in a similar manner except the lower 

frequency of sampling results in lower sampling costs. The annual costs for sorbent trap 

sampling and analysis of carbon adsorbers based on monthly sampling for 10 months and weekly 

sampling for 2 months is $10,000/yr per stack that is sampled. The carbon bed sampling is much 

less expensive because there is no capital cost, the analytical cost is less ($110/sample instead of 

$200/sample), and the sampling frequency is less. The carbon bed sampling is estimated as 

$3,170/yr per carbon bed that is sampled.

Reporting and recordkeeping costs are based on an estimate of 16 hours per plant plus 

4 hours per stack that is monitored. The reporting costs for a facility were developed as shown 

in Table 5 ($1,022+ $256 × number of stacks).
7

Table 5. Estimate of Reporting and Recordkeeping Costs

General Description 

Mean 

Hourly 

Ratea

Rate with 

overheadb hr/plant $/plant hr/stack $/stack

Environmental Engineer $35.24 $56.38 16 $902 4 $226

Managementc $57.27 $91.63 0.8 $73 0.20 $18

Office/Admin. Supportd $18.31 $29.30 1.6 $47 0.40 $12

Total 18.4 $1,022 4.6 $256 a Labor rates are for private industry workers in the mining industry (NAICS 212200) and were taken from the 

United States Department of Labor, Bureau of Labor Statistics, May 2009, available at: 

http://www.bls.gov/oes/current/naics4_212200.htm. b Overhead at 60%.

c

Estimated as 5% of technical hours. d Estimated as 10% of technical hours.

The final rule also requires annual stack sampling for mercury emissions (e.g., using EPA 

Method 29). However, most of the gold mine facilities are located in Nevada, and the Nevada 

Division of Environmental Protection already requires annual sampling using Method 29. 

Consequently, only facilities outside of Nevada would incur additional costs for stack sampling. 

The cost of Method 29 testing is estimated as $9,420 per stack test as shown in Table 6:

Table 6. Estimate of Costs for Method 29 Testing

Cost Description Cost

Equipment rental $1,850

Travel and lodging $1,625

Testing cost $2,611

Laboratory analysis $2,650

Test report $680

TOTAL $9,420

The MRR costs were estimated for each facility and are presented in Table 2. The costs 

are estimated from the cost functions described in this section and the number of roaster stacks,

number of other (non-roaster process unit) stacks, and stacks not located in Nevada (for 

Method 29 testing) that must be monitored and tested.

1.3 Beyond-the-Floor Costs

The affected sources with carbon processes with mercury retorts use carbon to recover 

the gold and have one or more of the following process units: carbon kilns, electrowinning, preg 

tanks, mercury retorts, and melt furnaces. Approximately 7 of the 10 facilities for which data are 

available will need to improve control to meet the floor limits because these 7 plants have an 

average emission control performance that is above the Maximum Achievable Control 

Technology (MACT) floor average performance. We expect that the carbon process with 

mercury retorts units not currently controlled will have carbon adsorbers installed to effectively 

control mercury emissions at the MACT floor level. Considering the very low mercury 
8

concentrations when the carbon processes with mercury retorts are performing at the MACT 

level of control, it is difficult to identify a technology that can obtain efficient additional percent 

reductions from low concentration streams. The final rule requires close monitoring of the 

carbon adsorber so that the carbon can be replaced before breakthrough occurs and mercury is 

emitted. With careful monitoring, emission reductions on the order of 99 percent could be 

achieved by the carbon adsorbers installed to achieve the MACT floor level of control. For a 

beyond-the-floor analysis, we assumed that theoretically a second carbon adsorption system 

could be installed in series with the first one and would get an additional 90 percent reduction (a 

lower reduction because of the very low mercury concentrations that result from the MACT floor 

level of control). We acknowledge that there is uncertainty as to the additional percent reduction 

the second control system might achieve. The cost estimates for a second carbon adsorption 

system in series with the first one for carbon processes with mercury retorts are presented in 

Table 7. The capital cost was estimated as $3 million with a total annualized cost of about 

$1.3 million/yr and a cost effectiveness of about $150,000/lb. 

The facilities with ore pretreatment processes have installed, or would be required to 

install mercury scrubbers and carbon adsorbers on their roasters and autoclaves, to achieve the 

MACT floor for ore pretreatment processes. To achieve further reduction in mercury, one 

beyond-the-floor option is the installation of both a refrigeration unit and a carbon adsorber 

on the remaining facility with autoclaves. This additional control system would follow the 

existing venturi scrubbers, and, because autoclave exhaust is saturated with water, a 

refrigeration unit or condenser would be required to remove moisture that would otherwise 

adversely affect the adsorptive capacity of the carbon adsorber. We estimate the capital cost 

for the additional controls on the autoclaves would be $47,000,000, with a total annualized 

cost of $8,200,000/yr. This option would reduce mercury emissions by 10 lbs/yr, resulting in 

an estimated cost effectiveness of $782,409/lb.

We also identified as a beyond-the-floor option the installation of a carbon adsorber on

ore preheater/dryer units. We estimated the capital cost for the additional controls as $2,962,000, 

with a total annualized cost of $1,622,000/yr. Based on an estimated control efficiency of 70 

percent, mercury emissions would be reduced by 118 lbs/yr, resulting in an estimated cost 

effectiveness of $13,784/lb. 
9

Table 7. Estimate of Costs for a Second Carbon Adsorber for Carbon Processes with 

Mercury Retorts

No. Facility Unit

Flow 

(cfm)

Total 

capital 

costa

Annual 

O&M 

costb

Total 

annualized 

cost

Mercury 

reduction 

(lb/yr)

1 Twin Creeks Juniper P/B tanks 3,085 209,000 51,936 71,666 0.90

2 Twin Creeks Electrowinning 7,311 434,000 109,621 150,591 0.50

3 Goldstrike Carbon kilns 4,406 658,512 135,968 198,131 1.00

4 Gold Quarry AARL carbon kiln 900 99,700 22,111 31,523 1.03

5

Florida 

Canyon Carbon kilns 1,000 183,934 82,691 100,054 0.77

6

Florida 

Canyon

Electrowinning, P/B 

tanks, melt furnace 1,000 183,934 82,691 100,054 0.06

7

Denton 

Rawhide Melt furnace 6,500 135,100 103,900 116,653 0.26

8 Lone Tree Electrowinning 10,000 423,000 146,326 186,257 0.23

9 Lone Tree P/B tanks 125 30,500 11,532 14,411 1.48

10 Gold Quarry Zadra Carbon kiln 900 99,700 22,111 31,523 0.16

11 Twin Creeks Melt furnace new 3,000 60,776 50,776 56,513 0.15

12 Twin Creeks Melt furnace old 3,000 60,776 50,776 56,513 0.40

13 Jerritt Canyon Melt furnace 1,622 141,933 31,966 45,365 1.24

14 Jerritt Canyon Carbon kiln & retort 5,930 308,949 90,771 119,935 0.32

Totals 3,029,813 993,176 1,279,191 8.50 a Estimated from : $184,000 * (cfm/2,500)0.6 (see text). b Operation and maintenance (O&M) costs estimated from : $9,826 + $13.65 × cfm (see text).

For the two facilities with carbon processes without retorts, we expect that Cortez will 

duct their uncontrolled P/B tank emissions into the electrowinning control device. For a beyondthe-floor analysis for carbon processes without mercury retorts, we estimated the costs and 

emissions reductions for installing a carbon adsorber to a unit at Round Mountain that is 

currently uncontrolled. For carbon processes without mercury retorts, the capital cost for a 

carbon adsorber was estimated to be $0.2 million with a total annualized cost of $72,000/yr. The 

mercury emissions reduction associated with this option would be 1.6 lbs/yr, resulting in an 

estimated cost effectiveness of $44,000/lb. 

For the two facilities with non-carbon concentrate processes, we expect that Midas would 

need to add a carbon adsorber to its melt furnace to achieve the MACT floor level of control. 

For beyond-the-floor, we again assumed that the existing carbon adsorbers would be 

supplemented by adding a second control system of carbon adsorbers in series for all of the melt 

furnaces at both facilities. Using the cost algorithms presented earlier as a function of system 

flow rate, we estimated the capital cost for the second set of carbon adsorber control systems as 

$430,000, an annual operating cost of $150,421/yr, and a total annualized cost of $191,013/year. 

Emissions would be reduced by 0.13 lb/year, which results in a cost effectiveness of 

$1.4 million/lb.

Table 8 summarizes the final mercury emission control costs including the beyond-thefloor costs for ore pretreatment and the MACT floor costs for all the affected sources.
10

Table 8. Final Mercury Emission Control Costsa

No. Facility Name Location

Hg 

reduction 

(lb/yr)

Estimates of mercury emission control costs

Total 

capital 

cost 

($2008)

Total 

O&M 

cost 

($/yr)

Total 

annual 

cost 

($/yr)

Cost 

effectiveness 

($/lb)

1 Goldstrike Elko, NV 141 858,512 1,335,968 1,417,131 10,016

2 Denton-Rawhide Fallon, NV 27 135,100 103,900 116,653 4,250

3 Florida Canyon Pershing Co., NV 87 367,868 165,382 200,109 2,305

4 Gold Quarry Carlin, NV 189 2,451,400 74,672 305,045 1,617

5 Jerritt Canyon Elko, NV 185 960,882 235,737 326,300 1,761

6 Lone Tree Valmy, NV 181 453,500 157,858 200,669 1,110

7 Midas Midas, NV 14 430,000 150,421 191,013 13,707

8 Twin Creeks Golconda, NV 636 30,064,551 2,413,109 5,239,483 8,232

Totals 1,461 35,721,813 4,637,047 7,996,404 5,474 a Includes beyond-the-floor costs for ore pretreatment and MACT floor costs for all other affected sources.

Table 9 summarizes the overall costs of the final MACT rule.

Table 9. Overall Costs and Cost Effectiveness of the Final MACT Rule

Capital Costs TAC 

Control Costs, $ million/yr 35,721,813 7,996,404

MRR, $ million/yr 770,835 1,062,778

Total Cost, $ million/yr 36,492,648 9,059,181

2.0 Emission Estimates

The emission estimates are based on mercury emission stack tests conducted in 2007 

through 2009.2 The data collected for the MACT floor analysis were used to estimate mercury 

emissions in pounds per year (lb/yr) for each process unit in each of the three groups of affected 

sources. The run-by-run data are presented in Appendix A, which also provides the details 

(emissions, operating hours, etc.) that were used in the calculations. When emissions were 

presented for different years for a single process unit, the emissions over the different years were 

averaged to estimate the average baseline emissions. Consequently, the emissions do not 

represent those reported for a given year, but the average of the years (2007-2009) for which data 

were available. Emissions for the facility were determined by summing emissions for each of 

the process units at the facility. A summary of the baseline emission estimates (i.e., emissions 

before MACT is effective) is given in Table 10 for the four groups of affected sources.

 2 Copies of the emission test reports are available in the rulemaking docket: EPA-HQ-OAR 2010-0239.
11

Emission reductions attributable to MACT for the carbon processes with mercury retorts, 

carbon processes without mercury retorts, and non-carbon processes group of units were 

estimated based on 95 percent and 99 percent control. The increased monitoring for carbon 

adsorbers is expected to result in continuing high reductions because the carbon would be 

replaced before complete breakthrough occurs. Table 11 presents the baseline emissions and 

emission reductions for the process units in the carbon processes with mercury retorts group that 

would be affected by MACT.

For the carbon processes without retorts group, we expect that MACT would result in the 

installation of a carbon adsorber on the electrowinning cells at Round Mountain. Round 

Mountain electrowinning baseline emissions of 1.72 lb/yr would be reduced by 1.6 to 0.12 lb/yr. 

The overall carbon processes without retorts baseline emissions of 3.52 lb/yr would be reduced 

by 1.6 to 1.89 lb/yr. 

The MACT reductions for the ore pretreatment group are based on the installation of 

carbon adsorbers on the autoclaves at Twin Creeks. No carbon adsorbers have been installed on 

autoclaves, so there is some uncertainty in the emission reductions that would be achieved. A 

conservative estimate of 70 to 90 percent reduction is used here because the autoclaves have a 

much higher flow rate and higher temperature than the exhaust streams typical of the carbon 

process units. The Twin Creeks autoclave baseline emissions of 615 lb/yr would be reduced by 

431 to 184 lb/yr. The overall ore pretreatment baseline emissions of 1,451 lb/yr would be 

reduced by 431 lb/yr from the controls on the autoclaves and 118 lb/yr from the beyond-the-floor 

control on the ore preheaters to 903 lb/yr. 

For the non-carbon concentrate group, we expect that MACT would result in the 

installation of a carbon adsorber on the melt furnace at Midas Operations. The Midas melt 

furnace baseline emissions of 14.67 lb/yr would be reduced by 13.94 to 0.73 lb/yr. The overall 

non-carbon concentrate baseline emissions of 25.79 lb/yr would be reduced by 13.94 to 

11.85 lb/yr.
12

Table 10. Baseline Mercury Emissions Estimates for the Four Groups of Affected 

Sources (based on data for 2007-2009)

Ore Pretreatment Processes

Facility Mercury Emissions (lb/yr)

Gold Quarry 186

Goldstrike 538

Jerritt Canyon Mine 112

Twin Creeks Mine 615

Subtotal 1,451

Carbon Processes with Mercury Retorts

Facility Mercury Emissions (lb/yr)

Bald Mountain 2.8

Denton-Rawhide 31

Florida Canyon Mine 93

Gold Quarry 231

Goldstrike 156

Jerritt Canyon 174

Lone Tree Mine 227

Marigold 5.7

Ruby Hill 5.9

Twin Creeks 230

Subtotal 1,155

Carbon Processes without Mercury Retorts

Facility Mercury Emissions (lb/yr)

Round Mountain 2.6

Cortez 2.3

Subtotal 4.9

Non-carbon Concentrate Processes

Facility Mercury Emissions (lb/yr)

Coeur Rochester 8.1

Midas Operations 18

Subtotal 26

Grand Total 2,636

We estimate that in 2007 about 5,000 pounds of mercury were emitted from this source 

category based mainly on test data for year 2007. In 2008 and 2009 a few facilities added 

controls or modified their operations. Thus, using a combination of data from 2007 to 2009, we 

estimate that current emissions are about 2,636 lb/yr. Overall, the proposed MACT limits are 

expected to reduce mercury emissions by about 1,461 to 1,174 lb/yr.
13

Table 11. Mercury Emissions Reductions for the Carbon Processes with Mercury Retorts 

Group

 

No. Facility Unit

Maximum 

concentrate 

usage (tpy)

Unit average 

(lb/ton 

concentrate)

Unit 

emissions 

lb/yr

Reductions 

@95% 

(lb/yr)

Reductions 

@99% 

(lb/yr)

1 Twin Creeks Juniper PregTanks 104.57 0.95 99.50 94.52 98.50

2 Twin Creeks Electrowinning 104.57 0.53 55.21 52.45 54.66

3 Goldstrike Carbon Kiln #2-Drum 105.93 1.05 110.94 105.40 109.83

4 Goldstrike Preg and Barren Tank A 105.93 0.01 0.92 0.88 0.91

5 Goldstrike Preg and Barren Tank B 105.93 0.01 0.65 0.61 0.64

6 Gold Quarry AARL Carbon Kiln 62.10 1.84 114.43 108.71 113.28

7 Florida Canyon Carbon Kiln 11.35 7.50 85.16 80.90 84.31

8 Florida Canyon Electrowinning Cell A 11.35 0.55 6.21 5.90 6.15

9 Denton-Rawhide Refinery Furnace 18.50 1.56 28.89 27.45 28.60

10 Lone Tree Mine Electrowinning Scavenger 11.00 2.33 25.59 24.31 25.33

11 Lone Tree Mine Pregnant & Barren Tanks 11.00 14.97 164.63 156.40 162.98

12 Gold Quarry Zadra Carbon Kiln 62.10 0.29 17.80 16.91 17.63

13 Twin Creeks Furnace (New) 104.57 0.16 17.22 16.36 17.05

14 Twin Creeks Furnace (Old) 104.57 0.43 44.77 42.53 44.32

15 Jerritt Canyon Carbon Kiln & Retort 12.00 2.98 35.70 33.92 35.34

16 Jerritt Canyon Melt furnace 12.00 11.52 138.20 131.29 136.82

Totals 946 899 936

3. Secondary Impacts

Secondary impacts include an increase in electricity consumption by fans and 

refrigeration units (in some cases) plus the generation of solid waste when the carbon in carbon 

adsorbers is replaced. The increase in electricity consumption was estimated from the following 

equation from the OAQPS Cost Manual18:

kW-hr/yr = 0.00081 * acfm * pressure drop (use 6 inches of water) * operating hr/yr.

The results are shown in Table 12 with a total increase of 12.6 million kW-hr/yr.

The estimated increase in spent carbon for regeneration or disposal assumes the carbon is 

replaced when half of its potential mercury capacity has been reached (about 0.1 lb mercury/lb 

carbon). For a mercury reduction of 1,461 lbs, approximately 14,600 lbs of carbon would be 

used and 16,060 lbs of spent loaded carbon would be generated.
14

Table 12. Estimated Increase in Electricity Consumption

No. Facility Unit

Operating 

hr/yr

Flow 

(cfm) kw hr/yr

1

DentonRawhide Melt Furnace 347 6,500 10,962

2 Florida Canyon 

Electrowinning, P/B tanks, melt 

furnace 8,760 1,000 42,574

3 Florida Canyon Carbon Kiln 8,760 1,000 42,574

4 Gold Quarry Zadra Carbon Kiln 8,760 900 38,316

5 Gold Quarry AARL Carbon Kiln 6,471 900 28,304

6 Goldstrike Carbon Kiln 6,884 4,406 147,408

7 Jerritt Canyon Carbon Kiln & Retort 1,541 5,930 44,411

8 Jerritt Canyon Melt Furnace 872 1,622 6,874

9 Lone Tree Electrowinning 2,424 10,000 117,806

10 Lone Tree P/B Tanks 8,760 125 5,322

11 Midas Furnace 832 10,300 41,648

12 Twin Creeks Melt Furnace 2 (new) 8,760 3,000 127,721

13 Twin Creeks Melt Furnace 1 (old) 8,760 3,000 127,721

14 Twin Creeks Electrowinning 8,760 7,311 311,256

15 Twin Creeks Juniper P/B tanks 8,760 3,085 131,340

16 Twin Creeks Autoclave 11,300 11,389,107a

Total 12,613,343 a Electricity consumption for the refrigeration unit taken from Phase 2 application (Reference 

19). 
15

References

1. Application for Phase 2 Operating Permit for Twin Creeks. Nevada Division of 

Environmental Protection. Page 3-21. 2008.

2. Application for Phase 2 Operating Permit for Barrick Goldstrike. Nevada Division of 

Environmental Protection. Appendix 3, Table 3.4, Page 22. 2008.

3. Application for Phase 2 Operating Permit for Florida Canyon. Nevada Division of 

Environmental Protection. Table 3.4, Page 19. 2008.

4. Application for Phase 2 Operating Permit for Twin Creeks. Nevada Division of 

Environmental Protection. Table 14, Page 3-21. 2008.

5. Application for Phase 2 Operating Permit for Twin Creeks. Nevada Division of 

Environmental Protection. Table 17, Page 3-24. 2008.

6. Application for Phase 2 Operating Permit for Gold Quarry. Nevada Division of 

Environmental Protection. Table 20, Page 3-26. 2008.

7. Application for Phase 2 Operating Permit for Florida Canyon. Nevada Division of 

Environmental Protection. Table 3.4, Page 18. 2008.

8. Application for Phase 2 Operating Permit for Denton-Rawhide. Nevada Division of 

Environmental Protection. Table 3.4, Page 21. 2008.

9. Application for Phase 2 Operating Permit for Lone Tree. Nevada Division of 

Environmental Protection. Page 3-10. 2008.

10. Application for Phase 2 Operating Permit for Lone Tree. Nevada Division of 

Environmental Protection. Page 3-12. 2008.

11. Application for Phase 2 Operating Permit for Bald Mountain. Nevada Division of 

Environmental Protection. Appendix 3, Page 21. 2008.

12. Application for Phase 2 Operating Permit for Bald Mountain. Nevada Division of 

Environmental Protection. Appendix 3, Page 16. 2008.

13. Application for Phase 2 Operating Permit for Ruby Hill. Nevada Division of 

Environmental Protection. Appendix 3, Table 3.8, Page 31. 2008.

14. Application for Phase 2 Operating Permit for Twin Creeks. Nevada Division of 

Environmental Protection. Page 3-21. 2008.
16

15. Application for Phase 2 Operating Permit for Midas. Nevada Division of Environmental 

Protection. Page 3-33. 2008.

16. Application for Phase 2 Operating Permit for Twin Creeks. Nevada Division of 

Environmental Protection. Page 3-11. 2008.

17. Application for Phase 2 Operating Permit for Twin Creeks. Nevada Division of 

Environmental Protection. Pages 3-11 and 3-12.

18. U.S. Environmental Protection Agency. EPA Air Pollution Control Cost Manual. 

Chapter 1. Baghouses and Filters. EPA/452/B-02-001. January 2002.

19. Barrick Goldstrike Mines Inc. public comments (docket item EPA-HQ-OAR-2010-0239-

0274) to proposed rule 75 Fed. Reg. 22470 (April 28, 2010) 
17

Appendix A. Emission Test Results and Estimates of Baseline Emissions
18

TABLE A-1. BASELINE MERCURY EMISSIONS FOR CARBON PROCESSES WITH MERCURY RETORTS

Facility Unit

Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr

Concentr

ate (tpy)

Max 

Concentr

ate (tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Marigold EW, P/B 6.30E-04 9.30E-04 7.40E-04 3.68E-01 5.43E-01 4.32E-01 2008 6,281 10.75 10.75 4.48E-01 4.82E+00

Marigold Retort 6.30E-04 9.30E-04 7.40E-04 7.72E-02 1.14E-01 9.07E-02 2008 1,318 10.75

Marigold Retort 2.00E-05 9.20E-05 1.10E-05 2.48E-03 1.14E-02 1.37E-03 2009 1,142 9.20 10.75 4.95E-02 5.33E-01

Marigold Melt Furnace 4.54E-03 2.20E-03 1.35E-03 8.49E-02 4.11E-02 2.52E-02 2008 201 10.75

Marigold Melt Furnace 4.40E-04 4.81E-04 7.67E-04 1.00E-02 1.09E-02 1.74E-02 2009 209 9.20 10.75 3.16E-02 3.40E-01

Marigold Carbon Kiln 1.41E-05 1.18E-05 1.31E-05 7.52E-03 6.29E-03 6.99E-03 2008 5,732 10.75

Marigold Carbon Kiln 1.50E-06 5.00E-07 8.00E-07 7.36E-04 2.45E-04 3.93E-04 2009 4,515 9.20 10.75 3.69E-03 3.97E-02 0.53 5.7

DentonRawhide Carbon Kiln 6.88E-06 7.55E-06 3.61E-05 3.16E-03 3.47E-03 1.66E-02 2007 8,497 18.5

DentonRawhide Carbon Kiln 1.35E-05 7.58E-06 2.42E-06 1.15E-02 6.48E-03 2.07E-03 2008 7,870 9.2

DentonRawhide Carbon Kiln 3.18E-04 1.85E-04 1.63E-04 2.50E-01 1.45E-01 1.28E-01 2009 6,482 8.25 18.50 6.30E-02 1.16E+00

DentonRawhide Electrowinning 3.83E-06 1.44E-06 3.79E-05 6.46E-04 2.43E-04 6.39E-03 2007 3,120 18.5

DentonRawhide Electrowinning 2.27E-05 4.25E-06 5.27E-06 1.40E-02 2.62E-03 3.25E-03 2008 5,667 9.2

DentonRawhide Electrowinning 1.14E-05 8.10E-05 1.59E-04 9.14E-03 6.49E-02 1.27E-01 2009 6,612 8.25 18.50 2.54E-02 4.70E-01

DentonRawhide Melt Furnace 1.94E-01 8.31E-02 6.32E-02 3.64E+00 1.56E+00 1.19E+00 2007 347 18.5

DentonRawhide Melt Furnace 9.95E-02 2.07E-01 1.66E-01 8.90E-01 1.85E+00 1.48E+00 2008 82 9.2

DentonRawhide Melt Furnace 6.53E-02 1.95E-01 2.69E-02 7.84E-01 2.34E+00 3.23E-01 2009 99 8.25 18.50 1.56E+00 2.89E+01

DentonRawhide Retort 4.30E-07 4.66E-07 5.28E-07 5.84E-05 6.33E-05 7.17E-05 2007 2,513 18.5

DentonRawhide Retort 8.95E-07 2.93E-07 2.74E-07 4.59E-05 1.50E-05 1.40E-05 2008 472 9.2

DentonRawhide Retort 2.92E-04 2.05E-04 3.57E-04 6.24E-02 4.38E-02 7.62E-02 2009 1,762 8.25 18.50 2.03E-02 3.75E-01 1.67 31

Bald 

Mountain Carbon Kiln 8.23E-05 5.59E-05 6.30E-05 2.37E-02 1.61E-02 1.82E-02 2009 1,084 3.76 3.76 1.93E-02 7.27E-02

Bald 

Mountain

Electrowinning 

& Barren Tank 5.57E-04 1.32E-04 8.14E-04 7.41E-01 1.76E-01 1.08E+00 2009 5,000 3.76 3.76 6.66E-01 2.51E+00

Bald 

Mountain Melt Furnace 1.80E-03 9.21E-04 1.21E-03 7.09E-02 3.63E-02 4.76E-02 2009 148 3.76 3.76 5.16E-02 1.94E-01

Bald 

Mountain Retort 6.68E-06 6.58E-06 2.88E-06 1.11E-03 1.09E-03 4.79E-04 2009 625 3.76 3.76 8.94E-04 3.36E-03 0.74 2.8

Ruby Hill Carbon Kiln 1.01E-03 9.49E-04 3.56E-04 2.30E-01 2.16E-01 8.08E-02 2009 1,274 5.61 5.61 1.75E-01 9.84E-01
19

Facility Unit

Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr

Concentr

ate (tpy)

Max 

Concentr

ate (tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Ruby Hill

Electrowinning 

& Preg/Barren 

Tanks 9.64E-04 3.49E-04 3.18E-04 1.51E+00 5.45E-01 4.97E-01 2009 8,760 5.61 5.61 8.49E-01 4.76E+00

Ruby Hill Melt Furnace 1.70E-03 2.04E-03 3.02E-02 3.63E-02 2009 100 5.61 5.61 3.33E-02 1.87E-01

Ruby Hill Retort 8.00E-07 8.00E-07 7.00E-07 1.30E-04 1.30E-04 1.14E-04 2009 911 5.61 5.61 1.24E-04 6.98E-04 1.06 5.9

Goldstrike Carbon Kiln 8.38E-02 1.49E-02 8.62E-03 5.45E+00 9.68E-01 5.60E-01 2007 6,884 105.9

Goldstrike Carbon Kiln 6.03E-03 8.76E-03 5.92E-03 4.27E-01 6.21E-01 4.20E-01 2008 7,271 102.6

Goldstrike Carbon Kiln 1.81E-02 1.85E-02 2.21E-02 1.28E+00 1.31E+00 1.57E+00 2008 7,271 102.6

Goldstrike Carbon Kiln 1.97E-02 2.06E-02 1.90E-02 1.40E+00 1.46E+00 1.35E+00 2008 7,271 102.6

Goldstrike Carbon Kiln 9.04E-03 1.28E-02 5.71E-03 6.41E-01 9.07E-01 4.05E-01 2008 7,271 102.6

Goldstrike Carbon Kiln 3.10E-04 4.20E-04 4.90E-04 2.39E-02 3.23E-02 3.77E-02 2009 7,527 97.8 105.93 1.05E+00 1.11E+02

Goldstrike Electrowinning 2.38E-03 2.71E-03 3.03E-03 1.58E-01 1.80E-01 2.02E-01 2007 7,053 105.9

Goldstrike Electrowinning 3.90E-03 5.60E-03 3.20E-03 2.74E-01 3.93E-01 2.25E-01 2008 7,202 102.6

Goldstrike Electrowinning 1.44E-03 9.60E-04 2.21E-03 1.06E-01 7.07E-02 1.63E-01 2009 7,202 97.8 105.93 1.97E-01 2.09E+01

Goldstrike Melt Furnace 4.95E-03 1.24E-02 3.96E-03 2.93E-02 7.35E-02 2.35E-02 2007 628 105.9

Goldstrike Melt Furnace 1.02E-02 2.88E-02 4.71E-02 4.56E-02 1.28E-01 2.10E-01 2009 436 97.8 105.93 8.50E-02 9.00E+00

Goldstrike Preg Tank 3.27E-03 2.27E-03 1.16E-03 2.07E-02 1.43E-02 7.33E-03 2008 648 102.6

Goldstrike Preg Tank 4.20E-04 4.80E-04 6.10E-04 2.78E-03 3.18E-03 4.04E-03 2009 648 97.8 105.93 8.72E-03 9.24E-01

Goldstrike Preg Tank 6.28E-04 2.11E-03 1.89E-03 3.97E-03 1.33E-02 1.19E-02 2008 648 102.6

Goldstrike Preg Tank 4.80E-04 3.00E-04 3.30E-04 3.18E-03 1.99E-03 2.19E-03 2009 648 97.8 105.93 6.10E-03 6.46E-01

Goldstrike Retort 3.11E-03 2.51E-03 1.73E-03 5.91E-02 4.77E-02 3.29E-02 2009 1,858 97.8 105.93 4.65E-02 4.93E+00

Goldstrike Retort 1.36E-03 6.90E-04 5.60E-04 3.00E-02 1.52E-02 1.23E-02 2009 2,154 97.8 105.93 1.92E-02 2.03E+00

Goldstrike Retort 3.08E-03 3.53E-03 3.34E-03 5.85E-02 6.70E-02 6.34E-02 2009 1,856 97.8 105.93 6.29E-02 6.67E+00 1.47 156

Twin Creeks Electrowinning 1.70E-04 9.00E-04 3.64E-03 2.29E-02 1.21E-01 4.91E-01 2007 8,760 64.9

Twin Creeks Electrowinning 1.30E-02 7.90E-03 8.80E-03 1.74E+00 1.06E+00 1.18E+00 2008 8,784 65.7

Twin Creeks Electrowinning 8.03E-04 5.15E-04 4.13E-04 6.73E-02 4.31E-02 3.46E-02 2009 8,760 104.57 104.57 5.28E-01 5.52E+01

Twin Creeks Melt Furnace 2 6.46E-02 1.85E-02 4.45E-02 4.20E-01 1.20E-01 2.89E-01 2007 422 64.9

Twin Creeks Melt Furnace 2 7.45E-02 2.12E-02 5.99E-02 4.85E-01 1.38E-01 3.90E-01 2007 422 64.9

Twin Creeks Melt Furnace 2 1.10E-02 3.10E-03 8.00E-03 6.60E-02 1.86E-02 4.80E-02 2008 394 65.7

Twin Creeks Melt Furnace 2 5.68E-05 7.99E-05 2.20E-04 1.77E-04 2.48E-04 6.84E-04 2009 325 104.57 104.57 1.65E-01 1.72E+01

Twin Creeks Melt Furnace 1 8.16E-02 3.28E-02 5.11E-02 1.04E+00 4.20E-01 6.54E-01 2007 831 64.9

Twin Creeks Melt Furnace 1 1.71E-01 6.65E-02 7.28E-02 2.19E+00 8.51E-01 9.32E-01 2007 831 64.9
20

Facility Unit

Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr

Concentr

ate (tpy)

Max 

Concentr

ate (tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Twin Creeks Melt Furnace 1 1.68E-03 4.99E-03 7.30E-03 2.15E-02 6.39E-02 9.35E-02 2007 831 64.9

Twin Creeks Melt Furnace 1 1.34E-02 7.00E-03 4.60E-03 7.79E-02 4.07E-02 2.67E-02 2008 382 65.7

Twin Creeks Melt Furnace 1 1.34E-04 1.14E-04 1.22E-04 5.36E-04 4.56E-04 4.88E-04 2009 418 104.57 104.57 4.28E-01 4.48E+01

Twin Creeks Carbon Kiln 1.88E-03 1.98E-04 8.21E-04 2.19E-01 2.30E-02 9.55E-02 2007 7,551 64.9

Twin Creeks Carbon Kiln 2.41E-03 9.20E-04 7.80E-04 2.80E-01 1.07E-01 9.08E-02 2007 7,551 64.9

Twin Creeks Carbon Kiln 6.50E-04 1.22E-03 1.20E-03 4.76E-02 8.89E-02 8.76E-02 2009 7,654 104.57 104.57 1.16E-01 1.21E+01

Twin Creeks Preg Tank 1.57E-02 1.41E-02 2.70E-03 2.12E+00 1.91E+00 3.64E-01 2007 8,760 64.9

Twin Creeks Preg Tank 6.10E-03 1.30E-02 5.80E-03 8.16E-01 1.74E+00 7.75E-01 2008 8,784 65.7

Twin Creeks Preg Tank 3.07E-03 3.08E-03 3.84E-03 2.57E-01 2.58E-01 3.22E-01 2009 8,760 104.57 104.57 9.52E-01 9.95E+01

Twin Creeks Retort 1.65E-06 1.43E-06 1.26E-06 8.80E-06 7.63E-06 6.72E-06 2009 558 104.57 104.57 7.72E-06 8.07E-04

Twin Creeks Retort 1.50E-05 2.20E-05 4.40E-05 8.13E-04 1.19E-03 2.39E-03 2007 3,519 64.9

Twin Creeks Retort 7.70E-05 9.20E-05 1.91E-04 4.18E-03 4.99E-03 1.04E-02 2007 3,519 64.9

Twin Creeks Retort 5.00E-05 1.30E-05 2.10E-05 2.57E-03 6.68E-04 1.08E-03 2008 3,375 65.7 104.57 3.14E-03 3.28E-01

Twin Creeks Retort 7.20E-06 2.75E-05 2.82E-05 3.51E-04 1.34E-03 1.38E-03 2007 3,168 64.9

Twin Creeks Retort 3.20E-05 1.16E-04 5.70E-05 1.56E-03 5.66E-03 2.78E-03 2007 3,168 64.9

Twin Creeks Retort 1.20E-05 6.00E-05 1.20E-05 5.07E-04 2.54E-03 5.07E-04 2008 2,778 65.7 104.57 1.85E-03 1.93E-01

Twin Creeks Retort 1.91E-05 7.46E-05 1.36E-04 7.58E-04 2.96E-03 5.40E-03 2007 2,574 64.9

Twin Creeks Retort 1.90E-06 6.20E-06 7.80E-06 7.54E-05 2.46E-04 3.09E-04 2007 2,574 64.9

Twin Creeks Retort 1.30E-05 9.40E-05 1.11E-04 4.75E-04 3.43E-03 4.05E-03 2008 2,400 65.7 104.57 1.97E-03 2.06E-01

Twin Creeks Retort 5.00E-07 1.27E-04 4.76E-05 2.17E-05 5.49E-03 2.06E-03 2007 2,814 64.9

Twin Creeks Retort 1.50E-05 1.10E-05 4.00E-06 6.50E-04 4.77E-04 1.73E-04 2007 2,814 64.9

Twin Creeks Retort 2.60E-06 6.10E-06 1.10E-05 1.17E-04 2.75E-04 4.95E-04 2008 2,958 65.7 104.57 1.09E-03 1.13E-01 2.20 230

Florida 

Canyon Carbon Kiln 1.31E-03 7.00E-04 8.50E-04 1.03E+00 5.52E-01 6.71E-01 2007 8,760 11.1

Florida 

Canyon Carbon Kiln 2.38E-02 3.71E-02 3.64E-02 1.30E+01 2.03E+01 2.00E+01 2008 6,195 11.3

Florida 

Canyon Carbon Kiln 7.06E-03 7.74E-03 3.24E-02 3.87E+00 4.24E+00 1.78E+01 2008 6,195 11.3

Florida 

Canyon Carbon Kiln 5.83E-03 2.72E-03 6.90E-03 3.23E+00 1.51E+00 3.83E+00 2009 6,292 11.4 11.35 7.50E+00 8.52E+01

Florida 

Canyon Melt Furnace 1.22E-02 3.20E-04 6.60E-04 3.17E-01 8.30E-03 1.71E-02 2007 288 11.1

Florida 

Canyon Melt Furnace 5.20E-04 7.20E-04 1.83E-03 1.45E-02 2.01E-02 5.11E-02 2008 316 11.3

Florida 

Canyon Melt Furnace 2.00E-04 2.80E-04 3.30E-04 5.76E-03 8.07E-03 9.51E-03 2009 327 11.4 11.35 5.02E-02 5.70E-01
21

Facility Unit

Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr

Concentr

ate (tpy)

Max 

Concentr

ate (tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Florida 

Canyon Electrowinning 3.40E-04 1.80E-04 7.60E-04 2.68E-01 1.42E-01 6.00E-01 2007 8,760 11.1

Florida 

Canyon Electrowinning 1.33E-03 1.90E-04 1.05E-03 1.03E+00 1.47E-01 8.14E-01 2008 8,760 11.3

Florida 

Canyon Electrowinning 1.79E-04 9.00E-04 1.41E-03 1.38E-01 6.95E-01 1.09E+00 2009 8,760 11.4 11.35 5.47E-01 6.21E+00

Florida 

Canyon Electrowinning 1.30E-04 1.30E-04 9.00E-05 1.03E-01 1.03E-01 7.10E-02 2007 8,760 11.1

Florida 

Canyon Electrowinning 9.80E-05 4.40E-05 5.90E-05 7.60E-02 3.41E-02 4.57E-02 2008 8,760 11.3

Florida 

Canyon Electrowinning 1.00E-04 1.00E-04 2.20E-05 7.72E-02 7.72E-02 1.70E-02 2009 8,760 11.4 11.35 6.70E-02 7.61E-01

Florida 

Canyon Retort 2.99E-05 1.42E-05 3.30E-06 2.63E-03 1.25E-03 2.90E-04 2008 992 11.3

Florida 

Canyon Retort 3.30E-07 2.20E-07 2.40E-07 2.30E-06 1.53E-06 1.67E-06 2009 79 11.4 11.35 6.95E-04 7.89E-03

Florida 

Canyon Retort 6.70E-07 5.20E-07 6.00E-07 6.89E-05 5.35E-05 6.17E-05 2007 1,141 11.1

Florida 

Canyon Retort 3.00E-06 1.60E-06 1.30E-06 3.08E-05 1.65E-05 1.34E-05 2008 116 11.3

Florida 

Canyon Retort 6.20E-07 4.50E-08 5.90E-07 5.07E-05 3.68E-06 4.82E-05 2009 928 11.4 11.35 3.86E-05 4.38E-04 8.17 93

Lone Tree Electrowinning 1.96E-03 1.08E-03 1.63E-03 1.39E+00 7.68E-01 1.16E+00 2007 7,824 11.0

Lone Tree Electrowinning 6.60E-04 5.75E-03 7.30E-04 7.02E-01 6.11E+00 7.76E-01 2008 2,424 2.28 11.00 1.82E+00 2.00E+01

Lone Tree Elecrowinning 2.70E-04 1.01E-02 1.10E-04 1.92E-01 7.15E+00 7.82E-02 2007 7,824 11.0

Lone Tree Electrowinning 5.82E-03 2.38E-04 9.70E-05 6.18E+00 2.53E-01 1.03E-01 2008 2,424 2.28 11.00 2.33E+00 2.56E+01

Lone Tree Electrowinning 2.51E-03 1.22E-03 4.70E-04 2.67E+00 1.30E+00 5.00E-01 2008 2,424 2.28 11.00 1.49E+00 1.64E+01

Lone Tree Preg Tank 2.48E-03 4.13E-03 2.15E-02 1.97E+00 3.29E+00 1.72E+01 2007 8,760 11.0

Lone Tree Preg Tank 7.40E-03 1.73E-02 2.97E-02 9.17E+00 2.14E+01 3.68E+01 2008 2,824 2.28 11.00 1.50E+01 1.65E+02 20.60 227

Gold Quarry Carbon Kiln 3.31E-02 3.45E-02 3.77E-02 3.46E+00 3.60E+00 3.93E+00 2007 6,471 62.0

Gold Quarry Carbon Kiln 7.83E-03 4.07E-03 5.86E-03 7.47E-01 3.88E-01 5.59E-01 2008 5,920 62.1

Gold Quarry Carbon Kiln 1.01E-02 9.48E-03 1.11E-02 1.29E+00 1.21E+00 1.41E+00 2009 6,523 51.2 62.10 1.84E+00 1.14E+02

Gold Quarry Electrowinning 3.67E-04 3.43E-04 3.75E-04 4.54E-02 4.24E-02 4.64E-02 2007 7,671 62.0

Gold Quarry Electrowinning 5.81E-04 5.32E-04 4.71E-04 7.32E-02 6.70E-02 5.94E-02 2008 7,826 62.1

Gold Quarry Electrowinning 3.12E-03 2.96E-03 5.89E-04 4.48E-01 4.25E-01 8.46E-02 2009 7,356 51.2 62.10 1.44E-01 8.91E+00

Gold Quarry Preg Tank 1.63E-03 1.73E-03 2.63E-03 2.30E-01 2.44E-01 3.71E-01 2007 8,760 62.0

Gold Quarry Preg Tank 2.38E-03 4.31E-04 9.11E-03 3.36E-01 6.10E-02 1.29E+00 2008 8,784 62.1

Gold Quarry Preg Tank 2.70E-05 1.68E-03 3.83E-03 3.82E-03 2.38E-01 5.42E-01 2008 8,784 62.1
22

Facility Unit

Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr

Concentr

ate (tpy)

Max 

Concentr

ate (tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Gold Quarry Preg Tank 1.89E-03 2.29E-04 6.04E-04 3.06E-01 3.71E-02 9.78E-02 2009 8,290 51.2 62.10 3.13E-01 1.94E+01

Gold Quarry Melt Furnace 2.41E-01 5.46E-02 1.28E-01 2.35E+00 5.33E-01 1.25E+00 2007 605 62.0

Gold Quarry Melt Furnace 2.61E-03 6.67E-04 1.83E-02 2.59E-02 6.61E-03 1.81E-01 2008 615 62.1

Gold Quarry Melt Furnace 4.32E-02 9.55E-02 2.63E-01 4.76E-01 1.05E+00 2.90E+00 2009 564 51.2 62.10 9.75E-01 6.05E+01

Gold Quarry Retort 7.20E-04 1.58E-03 8.22E-04 3.73E-02 8.17E-02 4.26E-02 2007 3,216 62.0

Gold Quarry Retort 2.50E-03 1.89E-03 1.72E-03 1.30E-01 9.79E-02 8.90E-02 2007 3,216 62.0

Gold Quarry Retort 1.67E-01 1.80E-01 1.32E-01 2007 3,216 62.0

Gold Quarry Retort 2.94E-03 3.06E-03 1.69E-03 1.66E-01 1.72E-01 9.52E-02 2009 2,880 51.2 62.10 1.52E-01 9.43E+00

Gold Quarry Carbon Kiln 8.49E-03 5.47E-03 4.54E-03 9.23E-01 5.95E-01 4.94E-01 2007 6,746 62.0

Gold Quarry Carbon Kiln 4.59E-04 5.16E-04 6.55E-04 5.56E-02 6.25E-02 7.94E-02 2008 7,527 62.1

Gold Quarry Carbon Kiln 1.17E-03 1.17E-03 1.42E-03 1.42E-01 1.41E-01 1.72E-01 2008 7,527 62.1

Gold Quarry Carbon Kiln 1.09E-03 2.17E-03 2.01E-03 1.60E-01 3.19E-01 2.96E-01 2009 7,529 51.2 62.10 2.87E-01 1.78E+01 3.71 231

Jerritt 

Canyon 

Mine

Carbon Kiln & 

Retort 2.09E-02 9.14E-03 6.56E-03 5.10E+00 2.23E+00 1.60E+00 2007 2,930 12 12 2.98E+00 3.57E+01

Jerritt 

Canyon 

Mine Melt Furnace 5.25E-03 2.27E-01 2.43E-01 3.82E-01 1.65E+01 1.76E+01 2007 872 12 12 1.15E+01 1.38E+02 14.49 174

Total 1,155 1,155
23

TABLE A-2. BASELINE MERCURY EMISSIONS FOR CARBON PROCESSES WITHOUT MERCURY RETORTS 

Facility Unit

Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr

Concentrate 

(tpy)

Max 

Concentrate 

(tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Round Mountain Electrowinning 9.17E-05 4.00E-04 9.59E-05 1.82E-02 7.93E-02 1.90E-02 2008 8760 44.2 44.2 3.88E-02 1.72E+00

Round Mountain Melt Furnace 1.07E-05 1.29E-04 1.27E-04 1.49E-04 1.80E-03 1.77E-03 2008 617 44.2

Round Mountain Melt Furnace 2.62E-03 7.21E-04 1.39E-03 3.49E-02 9.59E-03 1.85E-02 2009 584 43.9 44.2 1.11E-02 4.91E-01

Round Mountain Carbon Kiln 1.32E-05 1.47E-05 8.05E-06 2.57E-03 2.86E-03 1.56E-03 2008 8,592 44.2

Round Mountain Carbon Kiln 7.73E-05 5.18E-05 8.05E-05 1.52E-02 1.02E-02 1.59E-02 2009 8,652 43.9 44.2 8.05E-03 3.56E-01 0.058 2.56

Cortez Pipeline Carbon Kiln 1.52E-05 8.70E-06 3.99E-05 1.12E-03 6.42E-04 2.94E-03 2008 1,748 23.7

Cortez Pipeline Carbon Kiln 2.38E-05 1.62E-05 1.03E-05 2.59E-03 1.76E-03 1.12E-03 2009 2,341 21.50 23.7 1.70E-03 4.02E-02

Cortez Pipeline Carbon Kiln 1.57E-04 1.17E-04 4.59E-05 1.26E-02 9.36E-03 3.67E-03 2008 1,896 23.7

Cortez Pipeline Carbon Kiln 8.09E-05 3.48E-05 3.33E-05 6.13E-04 2.64E-04 2.52E-04 2009 163 21.50 23.7 4.45E-03 1.06E-01

Cortez Pipeline Electrowinning 6.99E-05 5.19E-05 8.08E-05 2.58E-02 1.92E-02 2.99E-02 2008 8,760 23.7

Cortez Pipeline Electrowinning 4.29E-05 1.09E-05 2.68E-05 1.41E-02 3.58E-03 8.79E-03 2009 7,055 21.50 23.7 1.69E-02 4.00E-01

Cortez Pipeline Electrowinning 3.79E-05 9.60E-06 1.71E-05 1.40E-02 3.55E-03 6.32E-03 2008 8,760 23.7

Cortez Pipeline Electrowinning 1.49E-05 1.58E-05 7.00E-06 5.30E-03 5.62E-03 2.49E-03 2009 7,641 21.50 23.7 6.21E-03 1.47E-01

Cortez Pipeline Preg & Barren Tanks 2.72E-04 4.36E-04 2.38E-04 1.01E-01 1.61E-01 8.80E-02 2008 8,760 23.7

Cortez Pipeline Preg & Barren Tanks 9.56E-06 7.17E-06 7.36E-06 3.25E-03 2.44E-03 2.50E-03 2009 7,317 21.50 23.7 5.96E-02 1.41E+00

Cortez Pipeline Melt Furnace 2.19E-05 1.66E-05 2.57E-05 2009 385 21.50

Cortez Pipeline Melt Furnace 1.49E-04 6.74E-05 1.03E-04 2.67E-03 1.21E-03 1.84E-03 2009 385 21.50 23.7 1.91E-03 4.52E-02

Cortez Pipeline Melt Furnace 1.23E-04 1.54E-04 1.16E-04 1.43E-04 1.79E-04 1.35E-04 2009 25 21.50 23.7 1.52E-04 3.61E-03

Cortez Pipeline Fusion furnace 2.20E-05 5.78E-05 9.77E-06 5.23E-03 1.37E-02 2.32E-03 2009 5,107 21.50 23.7 7.09E-03 1.68E-01 0.098 2.32

Total 4.89 4.89
24

TABLE A-3. BASELINE MERCURY EMISSIONS FOR ORE PRETREATMENT PROCESSES

Facility Unit 

Run 1 

(lbs/hr)

Run 2 

(lbs/hr)

Run 3 

(lbs/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr Ore (tpy)

Max Ore 

(tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Gold Quarry North Quench Circuit 5.67E-03 4.01E-03 5.76E-03 1.35E-05 9.56E-06 1.37E-05 2007 7,526 3,154,578

Gold Quarry North Quench Circuit 4.41E-03 5.55E-03 7.06E-03 1.05E-05 1.33E-05 1.69E-05 2008 7,973 3,336,226

Gold Quarry North Quench Circuit 3.57E-03 4.44E-03 4.09E-03 8.45E-06 1.05E-05 9.66E-06 2009 7,611 3,220,396 3,336,226 1.18E-05 3.93E+01

Gold Quarry Ore Preheater 5.32E-03 2.27E-03 1.90E-03 1.27E-05 5.41E-06 4.53E-06 2007 7,526 3,154,578

Gold Quarry Ore Preheater 1.10E-02 1.05E-02 6.45E-02 2.63E-05 2.50E-05 1.54E-04 2008 7,973 3,336,226

Gold Quarry Ore Preheater 3.42E-03 1.46E-03 1.27E-03 8.18E-06 3.48E-06 3.03E-06 2009 7,692 3,220,396 3,336,226 2.70E-05 9.00E+01

Gold Quarry Ore Roaster 3.77E-04 2.92E-04 3.30E-04 8.99E-07 6.97E-07 7.87E-07 2007 7,526 3,154,578

Gold Quarry Ore Roaster 5.33E-04 6.72E-04 2.59E-04 1.27E-06 1.61E-06 6.19E-07 2008 7,973 3,336,226

Gold Quarry Ore Roaster 2.06E-04 1.15E-04 1.49E-04 4.92E-07 2.75E-07 3.56E-07 2009 7,692 3,220,396 3,336,226 7.78E-07 2.60E+00

Gold Quarry

ROTP: Ore Dry 

Grind 7.01E-04 8.70E-04 6.25E-04 1.66E-06 2.06E-06 1.48E-06 2007 7,483 3,154,578

Gold Quarry

ROTP: Ore Dry 

Grind 6.36E-04 2.04E-03 7.44E-04 1.50E-06 4.82E-06 1.75E-06 2008 7,868 3,336,226 3,336,226 2.21E-06 7.39E+00

Gold Quarry South Quench Circuit 7.10E-03 5.75E-03 4.05E-03 1.67E-05 1.36E-05 9.55E-06 2007 7,446 3,154,578

Gold Quarry South Quench Circuit 5.40E-03 6.20E-03 8.96E-03 1.27E-05 1.46E-05 2.11E-05 2008 7,862 3,336,226

Gold Quarry South Quench Circuit 4.33E-03 5.49E-03 5.51E-03 1.03E-05 1.31E-05 1.32E-05 2009 7,692 3,220,396 3,336,226 1.39E-05 4.63E+01 5.56E-05 186

Goldstrike Roaster Mill #1 4.30E-04 6.70E-04 4.80E-04 3.23E-07 5.03E-07 3.60E-07 2009 7,754 10,330,763

Goldstrike

North Dry grinding 

process and preheater - Mill 1 1.30E-03 9.00E-04 7.80E-04 8.61E-07 5.96E-07 5.17E-07 2007 7,940 11,985,898

Goldstrike

North Dry grinding 

process and preheater - Mill 1 2.70E-03 2.10E-03 4.00E-04 1.79E-06 1.39E-06 2.65E-07 2007 7,940 11,985,898

Goldstrike

North Dry grinding 

process and preheater - Mill 1 3.30E-03 1.70E-03 4.00E-04 2.19E-06 1.13E-06 2.65E-07 2007 7,940 11,985,898 11,985,898 8.48E-07 1.02E+01

Goldstrike Roaster Mill #2 1.14E-02 6.19E-03 2.25E-03 8.68E-06 4.71E-06 1.71E-06 2009 7,855 10,330,763

Goldstrike

South Dry grinding 

process and preheater - Mill 2 3.60E-02 7.70E-03 1.20E-03 2.36E-05 5.05E-06 7.86E-07 2007 7,854 11,985,898

Goldstrike

South Dry grinding 

process and preheater - Mill 2 1.30E-03 1.30E-03 6.00E-04 8.52E-07 8.52E-07 3.93E-07 2007 7,854 11,985,898

Goldstrike

South Dry grinding 

process and preheater - Mill 2 2.50E-03 1.30E-03 6.00E-04 1.64E-06 8.52E-07 3.93E-07 2007 7,854 11,985,898 11,985,898 4.12E-06 4.94E+01
25

Facility Unit 

Run 1 

(lbs/hr)

Run 2 

(lbs/hr)

Run 3 

(lbs/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton) Year hr/yr Ore (tpy)

Max Ore 

(tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Goldstrike Roaster 1 & 2 1.10E-01 8.66E-02 7.98E-02 7.25E-05 5.71E-05 5.26E-05 2007 7,899 11,985,898

Goldstrike Roaster 1 & 2 1.90E-02 1.90E-02 2.60E-02 1.25E-05 1.25E-05 1.71E-05 2007 7,899 11,985,898

Goldstrike Roaster 1 & 2 2.56E-02 2.28E-02 1.73E-02 1.95E-05 1.73E-05 1.31E-05 2009 7,864 10,330,763 11,985,898 3.05E-05 3.65E+02

Goldstrike

Roaster #1 Quench 

Tank 5.72E-03 3.89E-03 3.78E-03 4.35E-06 2.96E-06 2.87E-06 2009 7,851 10,330,763 11,985,898 3.39E-06 4.07E+01

Goldstrike

Roaster #2 Quench 

Tank 4.65E-03 4.93E-03 4.36E-03 3.55E-06 3.76E-06 3.32E-06 2009 7,876 10,330,763 11,985,898 3.54E-06 4.25E+01

Goldstrike Autoclave 1 4.90E-04 7.60E-04 8.90E-04 2.59E-07 4.01E-07 4.70E-07 2009 5,457 10,330,763 11,985,898 3.77E-07 4.52E+00

Goldstrike Autoclave 2/3 8.60E-04 1.01E-03 7.20E-04 6.57E-07 7.71E-07 5.50E-07 2009 7,887 10,330,763 11,985,898 6.59E-07 7.90E+00

Goldstrike Autoclave 4 2.59E-03 3.00E-04 3.30E-04 1.42E-06 1.65E-07 1.81E-07 2009 5,679 10,330,763 11,985,898 5.90E-07 7.07E+00

Goldstrike Autoclave 5/6 1.84E-03 1.08E-03 6.00E-04 1.42E-06 8.32E-07 4.62E-07 2009 7,954 10,330,763 11,985,898 9.03E-07 1.08E+01 4.49E-05 538

Jerritt Canyon Ore dryer 2.60E-03 5.50E-03 3.70E-03 1.35E-05 2.86E-05 1.92E-05 2007 5,033 967,727

Jerritt Canyon Ore dryer 5.94E-04 5.03E-03 1.77E-03 3.82E-06 3.24E-05 1.14E-05 2010 155.3 tph 1,576,800 1.82E-05 2.86E+01

Jerritt Canyon Roaster West 6.12E-03 6.20E-03 7.12E-03 4.42E-05 4.47E-05 5.14E-05 2010 138.6 tph 

Jerritt Canyon Roaster West 6.20E-03 2.86E-03 4.13E-03 4.48E-05 2.07E-05 2.99E-05 2010 138.3 tph

Jerritt Canyon Roaster West 9.56E-04 1.08E-03 1.14E-03 7.01E-06 7.92E-06 8.36E-06 2010 136.3 tph 1,576,800 2.88E-05 4.54E+01

Jerritt Canyon Roaster East 7.62E-03 6.45E-03 3.91E-03 5.50E-05 4.65E-05 2.82E-05 2010 138.6 tph

Jerritt Canyon Roaster East 7.91E-04 5.86E-04 6.34E-04 5.80E-06 4.30E-06 4.65E-06 2010 136.3 tph 1,576,800 2.41E-05 3.80E+01 7.10E-05 112

Twin Creeks Autoclave 1 2.38E-02 6.24E-02 4.40E-02 5.52E-05 1.45E-04 1.02E-04 2007 7,914 3,410,717

Twin Creeks Autoclave 1 3.37E-02 1.12E-01 1.25E-02 7.82E-05 2.59E-04 2.90E-05 2007 7,914 3,410,717

Twin Creeks Autoclave 1 1.02E-01 5.04E-02 4.67E-02 2.36E-04 1.17E-04 1.08E-04 2007 7,914 3,410,717

Twin Creeks Autoclave 1 9.20E-02 5.73E-02 4.73E-02 2.13E-04 1.33E-04 1.10E-04 2007 7,914 3,410,717

Twin Creeks Autoclave 1 4.50E-02 8.90E-02 1.20E-01 9.97E-05 1.97E-04 2.66E-04 2008 8,265 3,728,849

Twin Creeks Autoclave 1 4.58E-02 3.00E-02 2.68E-02 1.06E-04 6.95E-05 6.21E-05 2009 8,282 3,572,940

Twin Creeks Autoclave 1 3.73E-03 3.48E-03 3.29E-03 8.65E-06 8.07E-06 7.63E-06 2010 8,282 3,572,940 3,728,849 1.15E-04 4.28E+02

Twin Creeks Autoclave 2 5.09E-02 2.44E-02 2.38E-02 1.14E-04 5.47E-05 5.33E-05 2007 7,644 3,410,717

Twin Creeks Autoclave 2 3.87E-02 2.22E-02 1.54E-02 8.67E-05 4.98E-05 3.45E-05 2007 7,644 3,410,717

Twin Creeks Autoclave 2 2.20E-02 4.10E-02 3.60E-02 4.87E-05 9.07E-05 7.96E-05 2008 8,250 3,728,849

Twin Creeks Autoclave 2 1.68E-02 1.19E-02 1.01E-02 3.53E-05 2.50E-05 2.12E-05 2009 7,502 3,572,940

Twin Creeks Autoclave 2 9.72E-03 9.11E-03 9.33E-03 2.04E-05 1.91E-05 1.96E-05 2010 7,502 3,572,940 3,728,849 5.02E-05 1.87E+02 1.65E-04 615

Total 1,451

 

1,451 
26

TABLE A-4. BASELINE MERCURY EMISSIONS FOR NON-CARBON CONCENTRATE PROCESSES

Facility Unit

Run 1 

(lbs/hr)

Run 2 

(lbs/hr)

Run 3 

(lbs/hr)

Run 4 

(lbs/hr)

Run 5 

(lbs/hr)

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Run 4 

(lb/ton)

Run 5 

(lb/ton) Year hr/yr

Conc 

(tpy)

Max 

Conc 

(tpy)

Unit 

average 

(lb/ton)

Per unit 

(lb/yr)

Facility 

total 

(lb/ton)

Facility 

total 

(lb/yr)

Coeur 

Rochester 

Refinery 

Furnace 2.23E-02 4.38E-02 8.54E-03 5.96E-02 1.17E-01 2.28E-02 2008 300 112

Coeur 

Rochester 

Refinery 

Furnace 1.01E-02 4.89E-03 1.20E-02 2.47E-02 1.20E-02 2.94E-02 2009 280 114 172 4.43E-02 7.61E+00

Coeur 

Rochester 

Retorts #1 

& #2 9.60E-04 9.70E-04 2.60E-05 6.50E-04 5.50E-04 3.41E-03 3.45E-03 9.24E-05 2.31E-03 1.95E-03 2007 611 172

Coeur 

Rochester 

Retorts #1 

& #2 8.65E-06 4.52E-04 1.24E-04 2.93E-04 1.53E-02 4.20E-03 2008 3,792 112

Coeur 

Rochester Retort 1.99E-06 8.76E-06 2.57E-06 4.17E-05 1.84E-04 5.39E-05 2009 2,400 114 172 2.84E-03 4.89E-01 0.047 8.10

Midas 

Melt 

Furnace 1 1.28E-03 4.15E-03 2.13E-03 5.58E-03 1.81E-02 9.29E-03 2009 994 228

Midas 

Refinery 

Furnace 

#1 7.50E-02 3.30E-02 1.50E-02 1.23E-01 5.41E-02 2.46E-02 2008 356 217

Midas 

Melt 

Furnace 2 2.12E-03 4.22E-03 3.14E-03 5.42E-03 1.08E-02 8.03E-03 2009 583 228

Midas 

Refinery 

Furnace 

#2 2.00E-02 6.50E-02 7.80E-03 5.01E-02 1.63E-01 1.95E-02 2008 543 217

Midas 

Refinery 

Furnace 1 

& 2 2.62E-03 4.30E-03 7.43E-03 1.60E-02 2.63E-02 4.55E-02 2007 832 136

Midas 

Refinery 

Furnace 1 

& 2 1.73E-01 2.17E-01 4.41E-02 2008

Midas 

Refinery 

Furnace 1 

& 2 1.10E-02 2.89E-02 1.73E-02 2009 228 6.43E-02 1.47E+01

Midas Retort A 1.23E-04 9.51E-05 7.75E-05 2.32E-03 1.79E-03 1.46E-03 2007 2,565 136

Midas Retort A 7.70E-05 3.70E-03 2.10E-03 1.25E-03 6.01E-02 3.41E-02 2008 3524 217

Midas Retort A 2.64E-06 2.06E-06 2.41E-06 4.07E-05 3.18E-05 3.72E-05 2009 3,518 228 228 1.12E-02 2.56E+00

Midas Retort B 1.93E-05 7.46E-07 5.11E-07 2.78E-04 1.07E-05 7.36E-06 2007 1,959 136

Midas Retort B 3.10E-04 3.29E-04 4.15E-04 4.22E-03 4.48E-03 5.66E-03 2008 2957 217

Midas Retort B 6.96E-05 1.06E-04 7.49E-05 9.51E-04 1.45E-03 1.02E-03 2009 3,115 228 228 2.01E-03 4.58E-01 0.078 18

Total 25.79 25.79
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

DEVELOPMENT OF THE MACT FLOORS AND MACT FOR THE FINAL NESHAP 

FOR GOLD MINE ORE PROCESSING AND PRODUCTION

Metals and Minerals Group

Sector Policies and Programs Division

Office of Air Quality Planning and Standards

U.S. Environmental Protection Agency

Research Triangle Park, NC

Draft - November 10, 2010
1

Development of the MACT Floors and MACT for the Final NESHAP for Gold Mine Ore 

Processing and Production

1. Selection of Affected Source

The Gold Mine Ore Processing and Production source category consists of facilities 

engaged in processing gold ore to recover gold using roasters, autoclaves, carbon kilns, melt 

furnaces, mercury retorts, electrowinning, and preg tanks. There were approximately 21 gold 

mine ore processing facilities operating these processes in the United States in 2008.

The final rule applies to each new or existing affected source and specifies maximum 

achievable control technology (MACT) standards for mercury emissions for the following four

affected sources in the Gold Mine Ore Processing and Production source category: ore 

pretreatment, carbon processes with mercury retorts, carbon processes without mercury retorts, 

and non-carbon concentrate processes. These affected sources reflect the differences in process 

operations, the sources of mercury entering the processes, and the nature of the emissions.

The ore pretreatment affected source includes roasting operations and autoclaves that 

pretreat refractory ore, which contains organic carbon and sulfide mineral grains that prevent the 

initial use of cyanide leaching to effectively extract the gold from the ore. The refractory ore is 

oxidized in the roaster or autoclave, converting it to an “oxidized” ore, which can then be 

effectively leached with cyanide solution. Mercury enters these processes with the ore. 

Ore Pretreatment

There are four existing facilities that use ore pretreatment processes, and mercury 

emissions data are available for all four of these facilities. The potential for mercury emissions 

from this affected source is directly related to the amount of ore processed in the autoclaves and 

roasters; consequently, the format selected for the standard for this affected source is pounds of 

mercury emissions (lb) per million ton of ore processed (lb/million ton of ore). In the 2007-2009 

timeframe, the ore pretreatment sources accounted for approximately 55 percent of the mercury 

emissions from the source category.

 The second affected source is carbon processes with mercury retorts, which includes 

those gold production operations that use carbon to collect (adsorb) the gold and mercury from 

solution and the process units that follow (i.e., carbon kilns, pregnant tanks, electrowinning cells, 

mercury retorts, and melt furnaces). Mercury emissions are subsequently generated by these 

Carbon Processes with Mercury Retorts
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

2

process units. The primary intermediate product that is common to all of the facilities with these 

carbon processes with mercury retorts is the gold-bearing concentrate, which is the input to 

mercury retorts. Further, concentrate is closely related to the final product because it contains 

about 60 percent gold, and because of its value, it is carefully weighed and records of the 

quantities are kept. The amount of concentrate input to the mercury retort is also required to be 

reported under the Nevada Division of Environmental Protection (NDEP) program, so we had 

comparable and reliable data from the different gold mine facilities. Consequently, we decided 

that the most appropriate format of the emission limit for the carbon processes with mercury 

retorts is lb/ton of concentrate processed. 

There are approximately 10 facilities with the carbon processes with mercury retorts, and 

we have mercury emissions data for 10 of these facilities. In the 2007-2009 timeframe, the 

carbon processes with mercury retorts sources accounted for approximately 44 percent of the 

mercury emissions from the source category.

The third affected source is carbon processes without mercury retorts, which includes 

those gold production operations that use carbon to collect the gold and mercury from solution

without the use of mercury retorts. Several facilities have such low concentrations of mercury in 

their ore that they do not require a mercury retort to remove and recover mercury. In addition, 

the average mercury emissions from these types of facilities that do not have mercury retorts are 

a factor of 10 less than facilities that do have mercury retorts. For these reasons, the final rule 

differentiates between carbon processes with and without mercury retorts.

Carbon Processes without Mercury Retorts

Mercury emissions are subsequently generated by the process units included in this 

affected source (i.e., carbon kilns, pregnant tanks, electrowinning cells, and melt furnaces). 

Similar to the reasons described previously for carbon processes with mercury retorts, the 

concentrate is the input to the melt furnace for carbon processes without mercury retorts; we 

decided that the most appropriate format of the emission limit for the carbon processes without 

mercury retorts is lb/ton of concentrate processed. 

There are approximately eight facilities with the carbon processes without mercury 

retorts, and we have mercury emissions data for two of these facilities. In the 2007-2009 

timeframe, the carbon processes without mercury retorts sources accounted for approximately 

0.19 percent of the mercury emissions from the source category.
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

3

This affected source includes facilities with gold ore processes that do not use carbon or 

ore pre-treatment. These facilities do not have roasters, autoclaves, or carbon kilns and instead 

only use mercury retorts and melt furnaces to recover the gold and liberate mercury from the 

concentrate. The amount of mercury entering these processes and potential mercury emissions 

are directly related to the amount of concentrate processed; consequently, the appropriate format 

for the final standard for this affected source is lb/ton of concentrate processed. There are about 

three gold mine ore processing facilities sources with non-carbon concentrate affected sources, 

and we have mercury emissions data for two of these facilities. In the 2007-2009 timeframe, the 

non-carbon concentrate sources accounted for approximately 0.98 percent of the mercury 

emissions from the source category.

Non-Carbon Concentrate Processes

2. Approach for Developing the MACT Floor

Pursuant to Section 112(d) of the Clean Air Act, MACT standards for existing 

affected sources must be at least as stringent as the average emissions limitation achieved by 

sources in the MACT pool; that is, the best performing 12 percent of existing affected sources 

for which the Administrator has data for source categories with 30 or more sources or the best 

performing 5 sources for source categories with fewer than 30 sources. This level of 

minimum stringency is called the MACT floor. For new sources, MACT standards must be at 

least as stringent as the control level achieved in practice by the best controlled similar 

affected source. 

The MACT floor limits for each of the four affected sources were calculated based on 

the performance of the lowest emitting (best performing) sources in each pool of sources with 

available data. We ranked all of the sources for which we had valid data representing current 

performance based on their emissions and identified the lowest emitting of the existing 

affected sources, which resulted in 4 facilities with ore pretreatment processes, 10 facilities 

for those with carbon processes with mercury retorts, 2 facilities for those with carbon 

processes without mercury retorts, and 2 facilities with the non-carbon concentrate processes. 

For new sources, MACT was based on the best performing source for each of the four

affected sources.

The run-by-run data and the details of the statistical calculations for the MACT floor 

analyses are provided in Appendices A through E.
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

4

2.1 Statistical Approach for Existing Sources 

To calculate the MACT floor limit for each of the affected sources, we established and 

ranked sources’ emissions from lowest to highest. The data on which the limits are based are 

expressed in terms of pounds of mercury emitted per unit of mass of input, where millions of 

tons of gold mine ore is the input for the ore pretreatment processes and tons of concentrate is the 

input for the carbon processes with mercury retorts, carbon processes without mercury retorts,

and the non-carbon concentrate processes. 

The emissions data for those best performing affected sources were used to determine the 

final emission limits, with an accounting for variability. EPA must exercise its judgment, based 

on an evaluation of the relevant factors and available data, to determine the level of emissions 

control that has been achieved by the best performing sources under variable conditions. The 

Court has recognized that EPA may consider variability in estimating the degree of emission 

reduction achieved by best-performing sources and in setting MACT floors. See Mossville Envt’l 

Action Now v. EPA, 370 F.3d 1232, 1241–42 (D.C. Cir 2004) (holding EPA may consider 

emission variability in estimating performance achieved by best-performing sources and may set 

the floor at a level that a best-performing source can expect to meet “every day and under all 

operating conditions”).

To calculate the achieved emission limit, including variability, we used upper prediction 

limit (UPL) approach, which is defined by the following equation:

T df T UPL = x + t v

where:

UPL = upper prediction limit,

T x = the average total emission rate over the best performing affected sources,

df t = the 99th percentile of the t distribution, and

T v = the total variance for the top performing affected sources.

The degrees of freedom associated with df t is given by:

∑ ∑ ( ) = = = − N

i

M

j ij

i

df n

1 1

1
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

5

where:

N = number of best performing affected sources (2 to 4 for the four affected sources),

Mi = number of mercury emitting processes at each affected source, and

nij = number of mercury emission test runs for each process unit.

The average total emission rate ( T x ) is calculated from: 

∑=

=

N

i

T Ti x

N

x

1

1

where:

N = the number of top N affected sources (N = 2 to 5),

Ti x = the total emission rate of an entire ith affected source.

To calculate Ti x :

∑=

=

Mi

j

Ti ij x x

1

where: 

Mi = the number of distinct units within the ith affected source (i.e., we count all the distinct 

units in an affected source, so if a process type has two or more units, then each of those 

units must be counted), 

ij x = the unit average for the jth unit within the ith affected source. 

To calculate ij x :

∑=

=

ij n

k

ijk

ij

ij x

n

x

1

1

where:

nij = the number of runs within the jth unit of the ith affected source,

xijk = the observation associated with the kth run within the jth unit and ith affected source. 

The total variance ( T v ) consists of the following two variance components:

T B W v = v + v
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

6

The first variance component ( B v ) is simply the variance of T x (the average total emission rate 

over all affected sources). Suppose 2 var( ) ij ijk s x = is the variance of an individual run in the jth 

unit and ith affected source, then the variance of the unit average, ij x in the jth unit and ith 

affected source is

ij

ij

ij n

s

x

2

var( ) = .

If all units operate independently, then the unit variances, 2

ij s , will be additive. Therefore, based 

on the assumption of variance additivity, the variance of the total emission rate of the ith affected 

source is 

∑=

=

Mi

j ij

ij

Ti

n

s

x

1

2

var( ) ,

and the variance of the average total emission rate over all affected sources is

∑∑= =

= =

N

i

M

j ij

ij

B T

i

n

s

N

v x

1 1

2

2

1 var( ) .

The second variance component ( Wv ) is the variance of T new x , , the total emission rate 

from new test runs at an affected source in the future to determine compliance. The theoretical

formulation of Wv based on these future runs is:

, , 2 ,

1 1 1

1 var( ) var( ) var( )

M M m

W T new j new jk new

j j k

vx x x = m = =

= = ∑ ∑∑ = ,

where jk new , x refers to the kth run of the jth unit in the new affected source, and M is the number 

of units in the new affected source. Also note that the number of units, M, in the affected source

to be tested in the future is unknown and may vary.

However, the theoretical formulation informs us how to derive an operational

formulation of Wv based on the data available from the runs already completed from the top N

affected sources:
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

7

2

2

1 11 1 1

1 1 1 var( )

N m M M i i N

W ijk ij

i jk i j

v xs

N m = = = Nm = =

  =   =

  ∑ ∑∑ ∑∑

Substituting into the equation provided for UPL earlier and rearranging yields:

2

1 1

1 11 N Mi

T df ij

i j ij

UPL x t s

N Nn m = =

  = + +  

  ∑∑

The first term of the equation refers to the average total emission rate of the top N affected 

sources. The second term accounts for the expected variability in future measurements due to 

variations resulting from system operation and measurement activities, and this variability 

consists of two components. The first component accounts for the variability of the average 

total emissions of the existing lowest emitting MACT pool sources, and the second component 

accounts for the variability of the average of m new test runs based on the observed variance of 

individual runs within test conditions from the lowest emitting MACT pool sources (the 

second component typically accounts for the major portion of the overall variability). The 

variability factor assumes that variability from the individual best performing sources are 

independent, and thus are additive. This is a reasonable assumption because each individual 

best performing source has certain characteristics, such as material inputs, design and 

operation, etc., that are unique to that process unit. 

2.2 Statistical Approach for New Sources

MACT for new sources is based on the UPL for the best performing source for each of 

the four types of affected sources and is calculated from:

1 df T1 UPL = x + t v

where:

1 x = the average total emission rate of the best performing affected source,

df t = the 99th percentile of the t distribution with (n – 1) degrees of freedom, and

T1 v = the total variance of the best performing source.

The total variance of the best performing source is calculated from the formulas given in Section 

2.1, except that in this case, N = 1 and the subscript i is replaced by the subscript 1:

1

2

1 1

1 1

1 1 M

T j

j j

v s = n m

 

= +  

  ∑ ,
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

8

where 2

1 j s and 1 j n are the variance and number of runs, respectively, from the jth mercuryemitting unit of the best performing source, M1 is the number of distinct mercury-emitting units 

in this source, and m is the number of future runs to determine compliance (typically 3).

3. MACT Floor for Mercury

Most of the mercury emissions data used in the MACT floor analyses were obtained 

from annual testing that was required by the Nevada Division of Environmental Protection 

(NDEP) for 2007 through 2009.

1

The NDEP invalidated several mercury emission tests conducted in 2007 and 2008 

because of failures to follow the reference test method or the established testing protocol. As 

a result, none of the test data for Barrick Goldstrike’s roasters and autoclaves for 2008 were

used in the analysis. However, 2007 and 2009 data for Goldstrike’s autoclaves and roasters 

were used in the analyses. The 2007 and 2008 tests for the mercury retorts at Goldstrike were 

also invalidated; however, test data for 2009 were available for the mercury retorts and were

used in the analysis for the carbon processes with mercury retorts. Other tests that were 

invalidated included the 2007 tests at Coeur Rochester, one of the October 2008 tests at 

Marigold, two of the August 2007 ore preheater tests at Goldstrike, and one of the February 

2010 roaster tests at Jerritt Canyon. In addition, we excluded data from the October 2009 

emission test on one of the melt furnaces for the Cortez Pipeline facility. The NDEP reported 

that, for that test, the mercury content of the concentrate was only 8 ppm, whereas the content 

 However, 2010 test data were used for one facility that 

installed new mercury emission controls on its roasters and resumed operation in late 2009. 

The tests generally consist of three runs per test per process at each affected source. Most of 

the measurements were made using EPA Method 29; however, Method 101A and the Ontario 

Hydro method were used in a few cases. There were cases where 2007 and/or 2008 results 

represent emissions before a control device was installed, and 2008 and/or 2009 test results 

represent emissions after a mercury emission control device had been installed. In those 

cases, we used only the controlled test results to determine the top performing affected 

sources. Emissions in lb/hr were multiplied by the number of hours the process operated in 

2007, 2008, or 2009 and then divided by the process input rate for the year (in tons or million 

tons) to express mercury emissions in lbs per ton (or million tons) of input material.

 

1 A complete listing of the emission test data is provided in a spreadsheet in docket item “Mercury Emissions Test 

Data” in the rulemaking docket.
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

9

for the December 2009 test was 1,557 ppm, and the content in 2007 and 2008 averaged 

4,480 ppm and 4,250 ppm, respectively. Based on that information, we concluded that the 

mercury content was unusually low for the October test, and the emissions data would not be

representative of typical operations.

The following paragraphs discuss the results of the MACT floor analyses for the four 

affected sources for the Gold Mine Ore Processing and Production source category. Tables 1

through 4 summarize the results. 

Valid emissions data were available for all four of the facilities with ore pretreatment 

processes. As shown in Table 1, the average emissions level achieved by these four facilities 

is 84 lb Hg/million tons of ore. The MACT floor based on the UPL is 158 lb Hg/million tons 

of ore. For new sources, MACT corresponds to 84 lb Hg/million tons of ore. We estimate 

that requiring the MACT floor emission limit for this affected source would reduce emissions 

of mercury by about 431 pounds per year (lbs/yr), a reduction of 30 percent from current 

levels. In addition, energy consumption would increase by about 11,400 megawatt-hours per 

year (or 11.4 gigawatt-hours per year). Solid waste generation and disposal (spent carbon 

loaded with mercury) would increase by about 3 tons per year.

Ore Pretreatment

Table 1. MACT Floor Results for Ore Pretreatment

Affected Source Average performance (lb Hg/million tons ore)

Goldstrike 45

Gold Quarry 56

Jerritt Canyon Mine 71

Twin Creeks Mine 165

Summary of Statistical Analysis

Statistic Existing (top 4) New

Average (lb/MM tons) 84 45

df 131 42

t 2.36 2.42

Vb 52 65

Vw 935 198

Vt 988 263

99% UPL (lb/MM tons), MACT Floor 158 84
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

10

Valid emissions data were available for 10 facilities that operate carbon processes with 

mercury retorts. Based on the MACT floor analysis, the average emissions level achieved by 

the best performing five sources is 1.1 lb Hg/ton of concentrate. After accounting for the 

variability in emissions, the MACT floor for this affected source is 2.2 lb Hg/ton of 

concentrate. For new sources, MACT is 0.8 lb Hg/ton concentrate. We estimate that the 

MACT floor limit for this affected source would reduce emissions by about 899 lbs/yr, a 

reduction of 78 percent from current levels.

Carbon Processes with Mercury Retorts

Table 2. MACT Floor Results for Carbon Processes with Mercury Retorts

Affected Source Average performance (lb Hg/ton concentrate)

Marigold 0.53

Bald Mountain 0.74

Ruby Hill 1.06

Goldstrike 1.47

Denton-Rawhide 1.67

Twin Creeks 2.20

Gold Quarry 3.71

Florida Canyon 8.17

Jerritt Canyon 14.49

Lone Tree 20.60

Summary of Statistical Analysis

Statistic Existing (top 5) New

Average (lb/tons) 1.1 0.53

Df 110 17

t 2.36 2.57

Vb 0.015 0.0032

Vw 0.20 0.0037

Vt 0.22 0.0069

99% UPL (lb/ton), MACT Floor 2.2 0.8

Valid data were available for two facilities that operate carbon processes without 

mercury retorts. As shown in Table 3, the average emissions level achieved by these two

facilities is 0.078 lb Hg/ton of concentrate. The existing MACT floor based on the UPL is 

Carbon Processes without Mercury Retorts
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

11

0.17 lb Hg/ton of concentrate. For new sources, MACT corresponds to 0.14 lb Hg/ton of 

concentrate.

Table 3. MACT Floor Results for Carbon Processes without Mercury Retorts

Affected Source Average performance (lb Hg/ton concentrate)

Round Mountain 0.058

Cortez 0.098

Summary of Statistical Analysis

Statistic Existing (top 2) New

Average (lb/ton) 0.078 0.058

df 43 12

t 2.42 2.68

Vb 0.00031 0.00045

Vw 0.0010 0.00048

Vt 0.0013 0.00093

99% UPL (lb/ton), MACT Floor 0.17 0.14

For this affected source, valid emissions data were available for two facilities. The 

results of the analysis are summarized in Table 4. Based on the MACT floor analysis, the 

average emissions level achieved by these two facilities is 0.062 lb Hg/ton of concentrate. 

The MACT floor for this affected source is 0.2 Hg/ton of concentrate. For new sources, 

MACT is 0.1 lb Hg/ton concentrate. We estimate that requiring the MACT floor emissions 

limit for non-carbon concentrate processes would reduce emissions by about 14 lbs/yr, a 

reduction of 54 percent from current levels.

Non-Carbon Concentrate Processes

Table 4. MACT Floor Results for Non-Carbon Concentrate Processes

Affected Source Average performance (lb Hg/ton concentrate)

Coeur Rochester Mine 0.047

Midas Operations 0.078

Summary of Statistical Analysis

Statistic Existing (top 2) New

Average (lb/ton) 0.062 0.047

df 39 15

t 2.43 2.60

Vb 0.00024 0.00026

Vw 0.0026 0.00052

Vt 0.0028 0.00077

99% UPL (lb/ton), MACT Floor 0.2 0.1
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

12

4. Beyond the Floor2

To evaluate opportunities for emission reductions beyond those that would result from 

requiring facilities to meet the MACT floor emissions limits, we typically identify control 

techniques that have the ability to achieve an emissions limit more stringent than the MACT 

floor. The following paragraphs summarize the results of this "beyond-the-floor" analysis for 

the four affected sources for the Gold Mine Ore Processing and Production source category.

 

Facilities with ore pretreatment processes either have installed, or would be required to 

install, calomel scrubbers and carbon adsorbers on their roasters and autoclaves, to achieve 

the MACT floor for ore pretreatment processes. We identified as a beyond-the-floor option 

the installation of both a refrigeration unit and a carbon adsorber on the remaining facility 

with autoclaves. This additional control system would follow the existing venturi scrubbers, 

and, because autoclave exhaust is saturated with water, a refrigeration unit or condenser 

would be required to remove moisture that would otherwise adversely affect the adsorptive 

capacity of the carbon adsorber. We estimate the capital cost for the additional controls on 

the autoclaves would be $47,000,000, with a total annualized cost of $8,200,000/yr. This 

option would reduce mercury emissions by 10 lbs/yr, resulting in an estimated cost

effectiveness of $782,409/lb.

Ore Pretreatment

We also identified as a beyond-the-floor option the installation of a carbon adsorber on 

ore preheater/dryer units. We estimated the capital cost for the additional controls as 

$2,962,000, with a total annualized cost of $1,622,000/yr. Based on an estimated control 

efficiency of 70 percent, mercury emissions would be reduced by 118 lbs/yr, resulting in an 

estimated cost effectiveness of $13,784/lb. Another assumption used in the beyond-the-floor 

calculations was that one facility, which has both roasters and autoclaves, would operate only

their roasters. With these additional controls, the average emissions level achieved by these 

sources facilities would be 80 lb/million tons of ore. We estimate that requiring the MACT

floor emissions limit and the beyond-the-floor options for ore pretreatment processes results 

in a total emissions reductions of 548 lbs/yr, a reduction of 38 percent from current levels.

 

2 Additional details and documentation for the estimates of emissions, emission reductions, and costs are provided 

in the rulemaking docket (EPA-HQ-OAR-2010-0239).
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

13

Applying the UPL formula to account for variability, the resulting beyond-the-floor emissions 

limit would be 127 lb/million tons of ore. Table 5 summarizes the beyond-the-floor analysis 

for ore pretreatment processes. This emission limit was incorporated in the final rule. 

Table 5. Beyond the Floor Results for Ore Pretreatment

Affected Source

Average performance 

(lb Hg/million tons ore)

Gold Quarry (70% reduction) 37

Twin Creeks (70% reduction) 49

Jerritt Canyon (70% reduction) 58

Goldstrike (70% reduction) 80

Summary of Statistical Analysis

Statistic

Average achieved by all (lb/MM tons) 80

df 123

t 2.36

Vb 30

Vw 369

Vt 399

Affected Source 99% UPL (lb/MM tons) 127

For two of the other affected sources (carbon processes with mercury retorts and noncarbon concentrate processes), existing sources are equipped with efficient mercury emission 

controls, and it is difficult to identify a technology that might be applied to achieve further 

reductions in emissions, especially considering the very low mercury concentrations after the 

MACT floor level of control and the difficulty in obtaining efficient additional percent 

reductions for low concentration streams. For the beyond-the-floor analysis, we assumed that 

a second carbon adsorption system could be installed in series with the first or existing 

adsorber and would get an additional reduction of 90 percent. (We acknowledge that there is 

significant uncertainty in the additional reductions the redundant control system might 

achieve.) For carbon processes with mercury retorts, the capital cost for the additional control 

was estimated to be $3 million, with a total annualized cost of $1.3 million/yr. The emissions

reductions for this control option would be 9 lbs/yr, resulting in an estimated cost 

effectiveness of $150,275/lb. For non-carbon concentrate processes, we estimated the capital 

cost for the additional adsorber to be $0.4 million, with a total annualized cost of 

$191,000/year. The mercury emissions reductions that would be achieved by this option 

Other Affected Sources
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

14

would be 0.13 lb/year, resulting in an estimated cost effectiveness of $1,400,000/lb. Because 

of the uncertainties in the emissions reductions that could be achieved, and the high cost 

effectiveness values, beyond-the-floor limits for these three types of affected sources were not 

adopted in the final rule.

For a beyond-the-floor analysis for carbon processes without mercury retorts, we 

estimated the costs and reductions for installing a carbon adsorber to a unit at Round 

Mountain that is currently uncontrolled. The capital cost for a carbon adsorber was estimated 

to be $0.2 million with a total annualized cost of $72,000/yr. The mercury emissions

reduction associated with this option would be 1.6 lbs/yr, resulting in an estimated cost 

effectiveness of $44,000/lb. For the same reasons described above for carbon processes with 

mercury retorts and non-carbon concentrate processes, it was concluded that this option was 

not cost effective, and it was not adopted in the final rule.

4. Summary of Final Emission Standards 

Table 6 summarizes the mercury emission limits included in the final Gold Mine Ore 

Processing and Production Area Source NESHAP. 

Table 6. Summary of Final Mercury Emission Limits

Affected Source

Hg Emission Limits

Existing Units

Sources

New 

Sources

Ore pretreatment processes 127 84 lb/million tons of ore

Carbon processes with mercury retorts 2.2 0.8 lb/ton of concentrate

Carbon processes without mercury retorts 0.17 0.14 lb/ton of concentrate

Non-carbon concentrate processes 0.2 0.1 lb/ton of concentrate
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

15

Appendix A. Mercury Emissions Data for the Ore Pretreatment Affected Source (lb/ton of ore)

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF (n-1) 

per unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

Gold Quarry

Roaster/Calcine 

quench 1.35E-05 9.56E-06 1.37E-05

Gold Quarry

Roaster/Calcine 

quench 1.05E-05 1.33E-05 1.69E-05

Gold Quarry

Roaster/Calcine 

quench 8.45E-06 1.05E-05 9.66E-06 1.06E-04 1.18E-05 7.33E-12 9 8 8.14E-13 2.44E-12

Gold Quarry

Roaster Ore 

Preheater 1.27E-05 5.41E-06 4.53E-06

Gold Quarry

Roaster Ore 

Preheater 2.63E-05 2.50E-05 1.54E-04

Gold Quarry

Roaster Ore 

Preheater 8.18E-06 3.48E-06 3.03E-06 2.43E-04 2.70E-05 2.35E-09 9 8 2.62E-10 7.85E-10

Gold Quarry Roaster 8.99E-07 6.97E-07 7.87E-07

Gold Quarry Roaster 1.27E-06 1.61E-06 6.19E-07

Gold Quarry Roaster 4.92E-07 2.75E-07 3.56E-07 7.00E-06 7.78E-07 1.86E-13 9 8 2.07E-14 6.21E-14

Gold Quarry

Roaster Ore 

Grinder 1.66E-06 2.06E-06 1.48E-06

Gold Quarry

Roaster Ore 

Grinder 1.50E-06 4.82E-06 1.75E-06 1.33E-05 2.21E-06 1.67E-12 6 5 2.79E-13 5.58E-13

Gold Quarry

Roaster/Calcine 

quench 1.67E-05 1.36E-05 9.55E-06

Gold Quarry

Roaster/Calcine 

quench 1.27E-05 1.46E-05 2.11E-05

Gold Quarry

Roaster/Calcine 

quench 1.03E-05 1.31E-05 1.32E-05 1.25E-04 1.39E-05 5.56E-05 1.19E-11 9 8 1.32E-12 2.64E-10 3.96E-12 7.92E-10

Goldstrike

Roaster Ore 

Preheater 3.23E-07 5.03E-07 3.60E-07

Goldstrike

Roaster Ore 

Preheater 8.61E-07 5.96E-07 5.17E-07

Goldstrike

Roaster Ore 

Preheater 1.79E-06 1.39E-06 2.65E-07

Goldstrike

Roaster Ore 

Preheater 2.19E-06 1.13E-06 2.65E-07 1.02E-05 8.48E-07 4.12E-13 12 11 3.43E-14 1.37E-13

Goldstrike

Roaster Ore 

Preheater 8.68E-06 4.71E-06 1.71E-06

Goldstrike

Roaster Ore 

Preheater 2.36E-05 5.05E-06 7.86E-07

Goldstrike

Roaster Ore 

Preheater 8.52E-07 8.52E-07 3.93E-07

Goldstrike

Roaster Ore 

Preheater 1.64E-06 8.52E-07 3.93E-07 4.95E-05 4.12E-06 4.40E-11 12 11 3.67E-12 1.47E-11
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

16

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF (n-1) 

per unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

Goldstrike Roaster 7.25E-05 5.71E-05 5.26E-05

Goldstrike Roaster 1.25E-05 1.25E-05 1.71E-05

Goldstrike Roaster 1.95E-05 1.73E-05 1.31E-05 2.74E-04 3.05E-05 5.47E-10 9 8 6.08E-11 1.82E-10

Goldstrike

Roaster/Calcine 

quench 4.35E-06 2.96E-06 2.87E-06 1.02E-05 3.39E-06 6.86E-13 3 2 2.29E-13 2.29E-13

Goldstrike

Roaster/Calcine 

quench 3.55E-06 3.76E-06 3.32E-06 1.06E-05 3.54E-06 4.72E-14 3 2 1.57E-14 1.57E-14

Goldstrike Autoclave 2.59E-07 4.01E-07 4.70E-07 1.13E-06 3.77E-07 1.16E-14 3 2 3.87E-15 3.87E-15

Goldstrike Autoclave 6.57E-07 7.71E-07 5.50E-07 1.98E-06 6.59E-07 1.23E-14 3 2 4.09E-15 4.09E-15

Goldstrike Autoclave 1.42E-06 1.65E-07 1.81E-07 1.77E-06 5.90E-07 5.21E-13 3 2 1.74E-13 1.74E-13

Goldstrike Autoclave 1.42E-06 8.32E-07 4.62E-07 2.71E-06 9.03E-07 4.49E-05 2.32E-13 3 2 7.72E-14 6.50E-11 7.72E-14 1.98E-10

Jerritt 

Canyon Ore dryer 1.35E-05 2.86E-05 1.92E-05

Jerritt 

Canyon Ore dryer 3.82E-06 3.24E-05 1.14E-05 1.09E-04 1.82E-05 1.17E-10 6 5 1.95E-11 3.90E-11

Jerritt 

Canyon Roaster 4.42E-05 4.47E-05 5.14E-05

Jerritt 

Canyon Roaster 4.48E-05 2.07E-05 2.99E-05

Jerritt 

Canyon Roaster 7.01E-06 7.92E-06 8.36E-06 2.59E-04 2.88E-05 3.31E-10 9 8 3.68E-11 1.10E-10

Jerritt 

Canyon Roaster 5.50E-05 4.65E-05 2.82E-05

Jerritt 

Canyon Roaster 5.80E-06 4.30E-06 4.65E-06 1.44E-04 2.41E-05 7.10E-05 5.16E-10 6 5 8.60E-11 1.42E-10 1.72E-10 3.21E-10

Twin Creeks Autoclave 5.52E-05 1.45E-04 1.02E-04

Twin Creeks Autoclave 7.82E-05 2.59E-04 2.90E-05

Twin Creeks Autoclave 2.36E-04 1.17E-04 1.08E-04

Twin Creeks Autoclave 2.13E-04 1.33E-04 1.10E-04

Twin Creeks Autoclave 9.97E-05 1.97E-04 2.66E-04

Twin Creeks Autoclave 1.06E-04 6.95E-05 6.21E-05

Twin Creeks Autoclave 8.65E-06 8.07E-06 7.63E-06 2.41E-03 1.15E-04 6.39E-09 21 20 3.04E-10 2.13E-09

Twin Creeks Autoclave 1.14E-04 5.47E-05 5.33E-05

Twin Creeks Autoclave 8.67E-05 4.98E-05 3.45E-05

Twin Creeks Autoclave 4.87E-05 9.07E-05 7.96E-05

Twin Creeks Autoclave 3.53E-05 2.50E-05 2.12E-05

Twin Creeks Autoclave 2.04E-05 1.91E-05 1.96E-05 7.53E-04 5.02E-05 1.65E-04 9.06E-10 15 14 6.04E-11 3.65E-10 3.02E-10 2.43E-09

Average 

of top 4: 8.41E-05 t DF: 131 Vb: 5.22E-11

Vw 

(unpoole

d): 9.35E-10
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

17

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF (n-1) 

per unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

t(.99): 2.36
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

18

Appendix B. Mercury Emissions Data for the Carbon Processes with Mercury Retorts Affected Source (lb/ton concentrate)

Facility Unit

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Marigold EW, P/B 3.68E-01 5.43E-01 4.32E-01 1.34E+00 4.48E-01 7.86E-03 3 2 2.62E-03 2.62E-03

Marigold Retort 7.72E-02 1.14E-01 9.07E-02

Marigold Retort 2.48E-03 1.14E-02 1.37E-03 2.97E-01 4.95E-02 2.52E-03 6 5 4.20E-04 8.41E-04

Marigold Furnace 8.49E-02 4.11E-02 2.52E-02

Marigold Melt Furnace 1.00E-02 1.09E-02 1.74E-02 1.90E-01 3.16E-02 8.13E-04 6 5 1.36E-04 2.71E-04

Marigold Carbon Kiln 7.52E-03 6.29E-03 6.99E-03

Marigold Carbon Kiln 7.36E-04 2.45E-04 3.93E-04 2.22E-02 3.69E-03 5.33E-01 1.27E-05 6 5 2.12E-06 3.18E-03 4.25E-06 3.74E-03

Bald 

Mountain Carbon Kiln 2.37E-02 1.61E-02 1.82E-02 5.80E-02 1.93E-02 1.55E-05 3 2 5.17E-06 5.17E-06

Bald 

Mountain

EW, Barren 

Tank 7.41E-01 1.76E-01 1.08E+00 2.00E+00 6.66E-01 2.10E-01 3 2 6.99E-02 6.99E-02

Bald 

Mountain Melt Furnace 7.09E-02 3.63E-02 4.76E-02 1.55E-01 5.16E-02 3.11E-04 3 2 1.04E-04 1.04E-04

Bald 

Mountain Retort 1.11E-03 1.09E-03 4.79E-04 2.68E-03 8.94E-04 7.38E-01 1.30E-07 3 2 4.32E-08 7.00E-02 4.32E-08 7.00E-02

Ruby Hill Carbon Kiln 2.30E-01 2.16E-01 8.08E-02 5.26E-01 1.75E-01 6.77E-03 3 2 2.26E-03 2.26E-03

Ruby Hill EW, P/B 1.51E+00 5.45E-01 4.97E-01 2.55E+00 8.49E-01 3.24E-01 3 2 1.08E-01 1.08E-01

Ruby Hill Melt Furnace 3.02E-02 3.63E-02 6.65E-02 3.33E-02 1.83E-05 2 1 9.13E-06 6.09E-06

Ruby Hill Retort 1.30E-04 1.30E-04 1.14E-04 3.73E-04 1.24E-04 1.06E+00 8.79E-11 3 2 2.93E-11 1.10E-01 2.93E-11 1.10E-01

Goldstrike Carbon Kiln 5.45E+00 9.68E-01 5.60E-01

Goldstrike Carbon Kiln 4.27E-01 6.21E-01 4.20E-01

Goldstrike Carbon Kiln 1.28E+00 1.31E+00 1.57E+00

Goldstrike Carbon Kiln 1.40E+00 1.46E+00 1.35E+00

Goldstrike Carbon Kiln 6.41E-01 9.07E-01 4.05E-01

Goldstrike Carbon Kiln 2.39E-02 3.23E-02 3.77E-02 1.89E+01 1.05E+00 1.47E+00 18 17 8.18E-02 4.91E-01

Goldstrike Electrowinning 1.58E-01 1.80E-01 2.02E-01

Goldstrike Electrowinning 2.74E-01 3.93E-01 2.25E-01

Goldstrike Electrowinning 1.06E-01 7.07E-02 1.63E-01 1.77E+00 1.97E-01 9.04E-03 9 8 1.00E-03 3.01E-03

Goldstrike Melt Furnace 2.93E-02 7.35E-02 2.35E-02

Goldstrike Melt Furnace

Goldstrike Melt Furnace 4.56E-02 1.28E-01 2.10E-01 5.10E-01 8.50E-02 5.21E-03 6 5 8.68E-04 1.74E-03

Goldstrike Preg Tank 2.07E-02 1.43E-02 7.33E-03

Goldstrike Preg Tank 2.78E-03 3.18E-03 4.04E-03 5.23E-02 8.72E-03 5.28E-05 6 5 8.79E-06 1.76E-05

Goldstrike Preg Tank 3.97E-03 1.33E-02 1.19E-02

Goldstrike Preg Tank 3.18E-03 1.99E-03 2.19E-03 3.66E-02 6.10E-03 2.63E-05 6 5 4.39E-06 8.77E-06

Goldstrike Retort

Goldstrike Retort
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

19

Facility Unit

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Goldstrike Retort

Goldstrike Retort

Goldstrike Retort 5.91E-02 4.77E-02 3.29E-02 1.40E-01 4.65E-02 1.73E-04 3 2 5.76E-05 5.76E-05

Goldstrike Retort

Goldstrike Retort

Goldstrike Retort

Goldstrike Retort 3.00E-02 1.52E-02 1.23E-02 5.75E-02 1.92E-02 8.94E-05 3 2 2.98E-05 2.98E-05

Goldstrike Retort

Goldstrike Retort

Goldstrike Retort

Goldstrike Retort

Goldstrike Retort 5.85E-02 6.70E-02 6.34E-02 1.89E-01 6.29E-02 1.47E+00 1.84E-05 3 2 6.13E-06 8.38E-02 6.13E-06 4.95E-01

DentonRawhide Carbon Kiln 3.16E-03 3.47E-03 1.66E-02

DentonRawhide Carbon Kiln 1.15E-02 6.48E-03 2.07E-03

DentonRawhide Carbon Kiln 2.50E-01 1.45E-01 1.28E-01 5.67E-01 6.30E-02 8.10E-03 9 8 9.00E-04 2.70E-03

DentonRawhide Electrowinning 6.46E-04 2.43E-04 6.39E-03

DentonRawhide Electrowinning 1.40E-02 2.62E-03 3.25E-03

DentonRawhide Electrowinning 9.14E-03 6.49E-02 1.27E-01 2.29E-01 2.54E-02 1.87E-03 9 8 2.08E-04 6.24E-04

DentonRawhide Melt Furnace 3.64E+00 1.56E+00 1.19E+00

DentonRawhide Melt Furnace 8.90E-01 1.85E+00 1.48E+00

DentonRawhide Melt Furnace 7.84E-01 2.34E+00 3.23E-01 1.41E+01 1.56E+00 9.69E-01 9 8 1.08E-01 3.23E-01

DentonRawhide Retort 5.84E-05 6.33E-05 7.17E-05

DentonRawhide Retort 4.59E-05 1.50E-05 1.40E-05

DentonRawhide Retort 6.24E-02 4.38E-02 7.62E-02 1.83E-01 2.03E-02 1.67E+00 9.89E-04 9 8 1.10E-04 1.09E-01 3.30E-04 3.27E-01

Average of 

top 5: 1.09E+00 tDF: 110 Vb: 1.50E-02

Vw 

(unpooled): 2.01E-01

t(.99): 2.36

Twin Creeks Electrowinning 2.29E-02 1.21E-01 4.91E-01

Twin Creeks Electrowinning 1.74E+00 1.06E+00 1.18E+00
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

20

Facility Unit

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Twin Creeks Electrowinning 6.73E-02 4.31E-02 3.46E-02 4.75E+00 5.28E-01 4.10E-01 9 8 4.55E-02 1.37E-01

Twin Creeks

Melt Furnace 2 

(new) 4.20E-01 1.20E-01 2.89E-01

Twin Creeks

Melt Furnace 2 

(new) 4.85E-01 1.38E-01 3.90E-01

Twin Creeks

Melt Furnace 2 

(new) 6.60E-02 1.86E-02 4.80E-02

Twin Creeks

Melt Furnace 2 

(new) 1.77E-04 2.48E-04 6.84E-04 1.98E+00 1.65E-01 3.29E-02 12 11 2.74E-03 1.10E-02

Twin Creeks

Melt Furnace 1 

(old) 1.04E+00 4.20E-01 6.54E-01

Twin Creeks

Melt Furnace 1 

(old) 2.19E+00 8.51E-01 9.32E-01

Twin Creeks

Melt Furnace 1 

(old) 2.15E-02 6.39E-02 9.35E-02

Twin Creeks

Melt Furnace 1 

(old) 7.79E-02 4.07E-02 2.67E-02

Twin Creeks

Melt Furnace 1 

(old) 5.36E-04 4.56E-04 4.88E-04 6.42E+00 4.28E-01 3.84E-01 15 14 2.56E-02 1.28E-01

Twin Creeks Carbon Kiln 2.19E-01 2.30E-02 9.55E-02

Twin Creeks Carbon Kiln 2.80E-01 1.07E-01 9.08E-02

Twin Creeks Carbon Kiln 4.76E-02 8.89E-02 8.76E-02 1.04E+00 1.16E-01 6.70E-03 9 8 7.44E-04 2.23E-03

Twin Creeks Preg Tank 2.12E+00 1.91E+00 3.64E-01

Twin Creeks Preg Tank 8.16E-01 1.74E+00 7.75E-01

Twin Creeks Preg Tank 2.57E-01 2.58E-01 3.22E-01 8.56E+00 9.52E-01 5.83E-01 9 8 6.48E-02 1.94E-01

Twin Creeks Retort 8.80E-06 7.63E-06 6.72E-06 2.32E-05 7.72E-06 1.09E-12 3 2 3.63E-13 3.63E-13

Twin Creeks Retort 8.13E-04 1.19E-03 2.39E-03

Twin Creeks Retort 4.18E-03 4.99E-03 1.04E-02

Twin Creeks Retort 2.57E-03 6.68E-04 1.08E-03 2.82E-02 3.14E-03 9.63E-06 9 8 1.07E-06 3.21E-06

Twin Creeks Retort 3.51E-04 1.34E-03 1.38E-03

Twin Creeks Retort 1.56E-03 5.66E-03 2.78E-03

Twin Creeks Retort 5.07E-04 2.54E-03 5.07E-04 1.66E-02 1.85E-03 2.79E-06 9 8 3.10E-07 9.29E-07

Twin Creeks Retort 7.58E-04 2.96E-03 5.40E-03

Twin Creeks Retort 7.54E-05 2.46E-04 3.09E-04

Twin Creeks Retort 4.75E-04 3.43E-03 4.05E-03 1.77E-02 1.97E-03 4.03E-06 9 8 4.48E-07 1.34E-06

Twin Creeks Retort 2.17E-05 5.49E-03 2.06E-03

Twin Creeks Retort 6.50E-04 4.77E-04 1.73E-04

Twin Creeks Retort 1.17E-04 2.75E-04 4.95E-04 9.77E-03 1.09E-03 2.20E+00 3.11E-06 9 8 3.45E-07 1.39E-01 1.04E-06 4.72E-01

Gold Quarry Carbon Kiln 3.46E+00 3.60E+00 3.93E+00

Gold Quarry Carbon Kiln 7.47E-01 3.88E-01 5.59E-01
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

21

Facility Unit

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Gold Quarry Carbon Kiln 1.29E+00 1.21E+00 1.41E+00 1.66E+01 1.84E+00 1.99E+00 9 8 2.21E-01 6.63E-01

Gold Quarry Electrowinning 4.54E-02 4.24E-02 4.64E-02

Gold Quarry Electrowinning 7.32E-02 6.70E-02 5.94E-02

Gold Quarry Electrowinning 4.48E-01 4.25E-01 8.46E-02 1.29E+00 1.44E-01 2.78E-02 9 8 3.09E-03 9.28E-03

Gold Quarry Preg Tank 2.30E-01 2.44E-01 3.71E-01

Gold Quarry Preg Tank 3.36E-01 6.10E-02 1.29E+00

Gold Quarry Preg Tank 3.82E-03 2.38E-01 5.42E-01

Gold Quarry Preg Tank 3.06E-01 3.71E-02 9.78E-02 3.76E+00 3.13E-01 1.19E-01 12 11 9.91E-03 3.96E-02

Gold Quarry Melt Furnace 2.35E+00 5.33E-01 1.25E+00

Gold Quarry Melt Furnace 2.59E-02 6.61E-03 1.81E-01

Gold Quarry Melt Furnace 4.76E-01 1.05E+00 2.90E+00 8.77E+00 9.75E-01 1.07E+00 9 8 1.19E-01 3.58E-01

Gold Quarry Retort

Gold Quarry Retort 3.73E-02 8.17E-02 4.26E-02

Gold Quarry Retort 1.30E-01 9.79E-02 8.90E-02

Gold Quarry Retort 1.67E-01 1.80E-01 1.32E-01

Gold Quarry Retort 1.66E-01 1.72E-01 9.52E-02 9.11E-01 1.52E-01 1.04E-03 6 5 1.74E-04 3.48E-04

Gold Quarry Carbon Kiln 9.23E-01 5.95E-01 4.94E-01

Gold Quarry Carbon Kiln 5.56E-02 6.25E-02 7.94E-02

Gold Quarry Carbon Kiln 1.42E-01 1.41E-01 1.72E-01

Gold Quarry Carbon Kiln 1.60E-01 3.19E-01 2.96E-01 3.44E+00 2.87E-01 3.71E+00 6.93E-02 12 11 5.77E-03 3.59E-01 2.31E-02 1.09E+00

Florida 

Canyon Carbon Kiln 1.03E+00 5.52E-01 6.71E-01

Florida 

Canyon Carbon Kiln 1.30E+01 2.03E+01 2.00E+01

Florida 

Canyon Carbon Kiln 3.87E+00 4.24E+00 1.78E+01

Florida 

Canyon Carbon Kiln 3.23E+00 1.51E+00 3.83E+00 9.00E+01 7.50E+00 6.22E+01 12 11 5.18E+00 2.07E+01

Florida 

Canyon Melt Furnace 3.17E-01 8.30E-03 1.71E-02

Florida 

Canyon Melt Furnace 1.45E-02 2.01E-02 5.11E-02

Florida 

Canyon Melt Furnace 5.76E-03 8.07E-03 9.51E-03 4.52E-01 5.02E-02 1.02E-02 9 8 1.13E-03 3.40E-03

Florida 

Canyon Electrowinning 2.68E-01 1.42E-01 6.00E-01

Florida 

Canyon Electrowinning 1.03E+00 1.47E-01 8.14E-01

Florida 

Canyon Electrowinning 1.38E-01 6.95E-01 1.09E+00 4.92E+00 5.47E-01 1.49E-01 9 8 1.66E-02 4.97E-02

Florida 

Canyon Electrowinning 1.03E-01 1.03E-01 7.10E-02
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

22

Facility Unit

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Florida 

Canyon Electrowinning 7.60E-02 3.41E-02 4.57E-02

Florida 

Canyon Electrowinning 7.72E-02 7.72E-02 1.70E-02 6.03E-01 6.70E-02 8.59E-04 9 8 9.55E-05 2.86E-04

Florida 

Canyon Retort 2.63E-03 1.25E-03 2.90E-04

Florida 

Canyon Retort 2.30E-06 1.53E-06 1.67E-06 4.17E-03 6.95E-04 1.13E-06 6 5 1.88E-07 3.76E-07

Florida 

Canyon Retort 6.89E-05 5.35E-05 6.17E-05

Florida 

Canyon Retort 3.08E-05 1.65E-05 1.34E-05

Florida 

Canyon Retort 5.07E-05 3.68E-06 4.82E-05 3.47E-04 3.86E-05 8.17E+00 5.39E-10 9 8 5.99E-11 5.20E+00 1.80E-10 2.08E+01

Jerritt Canyon Carbon Kiln 5.10E+00 2.23E+00 1.60E+00 8.93E+00 2.98E+00 3.48E+00 3 2 1.16E+00 1.16E+00

Jerritt Canyon Melt Furnace 3.82E-01 1.65E+01 1.76E+01 3.45E+01 1.15E+01 1.45E+01 9.32E+01 3 2 3.11E+01 3.22E+01 3.11E+01 3.22E+01

Lone Tree Electrowinning 1.39E+00 7.68E-01 1.16E+00

Lone Tree Electrowinning 7.02E-01 6.11E+00 7.76E-01 1.09E+01 1.82E+00 4.50E+00 6 5 7.50E-01 1.50E+00

Lone Tree Elecrowinning 1.92E-01 7.15E+00 7.82E-02

Lone Tree Electrowinning 6.18E+00 2.53E-01 1.03E-01 1.40E+01 2.33E+00 1.14E+01 6 5 1.90E+00 3.80E+00

Lone Tree Electrowinning 2.67E+00 1.30E+00 5.00E-01 4.47E+00 1.49E+00 1.20E+00 3 2 4.01E-01 4.01E-01

Lone Tree Preg Tank 1.97E+00 3.29E+00 1.72E+01

Lone Tree Preg Tank 9.17E+00 2.14E+01 3.68E+01 8.98E+01 1.50E+01 2.06E+01 1.72E+02 6 5 2.87E+01 3.18E+01 5.74E+01 6.31E+01
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

23

Appendix C. Mercury Emissions Data for the Carbon Processes without Mercury Retorts Affected Source (lb/ton concentrate)

Facility Process type

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton) Unit var

No. of runs 

per unit

DF (n-1) 

per unit

Var of unit 

average Facility var

Vw (m = 3 

per unit) Facility Vw

Round Mountain Electrowinning 1.82E-02 7.93E-02 1.90E-02 1.16E-01 3.88E-02 1.23E-03 3 2 4.09E-04 4.09E-04

Round Mountain Melt Furnace 1.49E-04 1.80E-03 1.77E-03

Round Mountain Melt Furnace 3.49E-02 9.59E-03 1.85E-02 6.67E-02 1.11E-02 1.83E-04 6 5 3.05E-05 6.10E-05

Round Mountain Carbon Kiln 2.57E-03 2.86E-03 1.56E-03

Round Mountain Carbon Kiln 1.52E-02 1.02E-02 1.59E-02 4.83E-02 8.05E-03 0.058 4.33E-05 6 5 7.22E-06 4.47E-04 1.44E-05 4.85E-04

Cortez Pipeline Carbon Kiln 1.12E-03 6.42E-04 2.94E-03

Cortez Pipeline Carbon Kiln 2.59E-03 1.76E-03 1.12E-03 1.02E-02 1.70E-03 8.27E-07 6 5 1.38E-07 2.76E-07

Cortez Pipeline Carbon Kiln 1.26E-02 9.36E-03 3.67E-03

Cortez Pipeline Carbon Kiln 6.13E-04 2.64E-04 2.52E-04 2.67E-02 4.45E-03 2.81E-05 6 5 4.68E-06 9.36E-06

Cortez Pipeline Electrowinning 2.58E-02 1.92E-02 2.99E-02

Cortez Pipeline

Electro Winning 

System 1.41E-02 3.58E-03 8.79E-03 1.01E-01 1.69E-02 1.01E-04 6 5 1.68E-05 3.36E-05

Cortez Pipeline Electrowinning 1.40E-02 3.55E-03 6.32E-03

Cortez Pipeline

Electro Winning 

System 5.30E-03 5.62E-03 2.49E-03 3.73E-02 6.21E-03 1.66E-05 6 5 2.77E-06 5.53E-06

Cortez Pipeline Preg Tank 1.01E-01 1.61E-01 8.80E-02

Cortez Pipeline

Pregnant and Barren 

Tanks 3.25E-03 2.44E-03 2.50E-03 3.58E-01 5.96E-02 4.50E-03 6 5 7.50E-04 1.50E-03

Cortez Pipeline Melt Furnace 2.67E-03 1.21E-03 1.84E-03 5.72E-03 1.91E-03 5.37E-07 3 2 1.79E-07 1.79E-07

Cortez Pipeline Melt Furnace 1.43E-04 1.79E-04 1.35E-04 4.57E-04 1.52E-04 5.53E-10 3 2 1.84E-10 1.84E-10

Cortez Pipeline Fusion furnace 5.23E-03 1.37E-02 2.32E-03 2.13E-02 7.09E-03 0.098 3.52E-05 3 2 1.17E-05 7.86E-04 1.17E-05 1.56E-03

Average of 

top 2: 0.078 tDF: 43Vb: 3.08E-04

Vw 

(unpooled): 1.02E-03

t(.99): 2.42
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

24

Appendix D. Mercury Emissions Data for the Non-Carbon Concentrate Affected Source (lb/ton concentrate)

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Run 4 

(lb/ton)

Run 5 

(lb/ton)

Unit 

sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF (n-1) 

per unit

Varianc

e of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

Coeur 

Rochester 

Refinery 

Furnace 5.96E-02 1.17E-01 2.28E-02

Coeur 

Rochester 

Refinery 

Furnace 2.47E-02 1.20E-02 2.94E-02 2.66E-01 4.43E-02 1.53E-03 6 5 2.55E-04 5.10E-04

Coeur 

Rochester Retorts #1 & #2 3.41E-03 3.45E-03 9.24E-05 2.31E-03 1.95E-03

Coeur 

Rochester Retorts #1 & #2 2.93E-04 1.53E-02 4.20E-03

Coeur 

Rochester Retorts #1 & #2 4.17E-05 1.84E-04 5.39E-05 3.13E-02 2.84E-03 0.047 1.96E-05 11 10 1.78E-06 2.57E-04 6.52E-06 5.17E-04

Midas 

Operations

Refinery 

Furnace 1 & 2 1.60E-02 2.63E-02 4.55E-02

Midas 

Operations

Refinery 

Furnace 1 & 2 1.73E-01 2.17E-01 4.41E-02

Midas 

Operations

Refinery 

Furnace 1 & 2 1.10E-02 2.89E-02 1.73E-02 5.79E-01 6.43E-02 5.74E-03 9 8 6.38E-04 1.91E-03

Midas 

Operations Retort A 2.32E-03 1.79E-03 1.46E-03

Midas 

Operations Retort A 1.25E-03 6.01E-02 3.41E-02

Midas 

Operations Retort A 4.07E-05 3.18E-05 3.72E-05 1.01E-01 1.12E-02 4.56E-04 9 8 5.07E-05 1.52E-04

Midas 

Operations Retort B 2.78E-04 1.07E-05 7.36E-06

Midas 

Operations Retort B 4.22E-03 4.48E-03 5.66E-03

Midas 

Operations Retort B 9.51E-04 1.45E-03 1.02E-03 1.81E-02 2.01E-03 0.078 4.72E-06 9 8 5.24E-07 6.89E-04 1.57E-06 2.07E-03

Average 

of top 2: 6.23E-02 1.55E-03 t DF: 39 Vb: 2.37E-04

Vw 

(unpoole

d): 2.58E-03

t(.99): 2.43
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

25

Appendix E. New Source MACT Floors

Ore Pretreatment Processes

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit 

sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Goldstrike Roaster Ore Preheater 3.23E-07 5.03E-07 3.60E-07

Goldstrike Roaster Ore Preheater 8.61E-07 5.96E-07 5.17E-07

Goldstrike Roaster Ore Preheater 1.79E-06 1.39E-06 2.65E-07

Goldstrike Roaster Ore Preheater 2.19E-06 1.13E-06 2.65E-07 1.02E-05 8.48E-07 4.12E-13 12 11 3.43E-14 1.37E-13

Goldstrike Roaster Ore Preheater 8.68E-06 4.71E-06 1.71E-06

Goldstrike Roaster Ore Preheater 2.36E-05 5.05E-06 7.86E-07

Goldstrike Roaster Ore Preheater 8.52E-07 8.52E-07 3.93E-07

Goldstrike Roaster Ore Preheater 1.64E-06 8.52E-07 3.93E-07 4.95E-05 4.12E-06 4.40E-11 12 11 3.67E-12 1.47E-11

Goldstrike Roaster 7.25E-05 5.71E-05 5.26E-05

Goldstrike Roaster 1.25E-05 1.25E-05 1.71E-05

Goldstrike Roaster 1.95E-05 1.73E-05 1.31E-05 2.74E-04 3.05E-05 5.47E-10 9 8 6.08E-11 1.82E-10

Goldstrike Roaster/Calcine quench 4.35E-06 2.96E-06 2.87E-06 1.02E-05 3.39E-06 6.86E-13 3 2 2.29E-13 2.29E-13

Goldstrike Roaster/Calcine quench 3.55E-06 3.76E-06 3.32E-06 1.06E-05 3.54E-06 4.72E-14 3 2 1.57E-14 1.57E-14

Goldstrike Autoclave 2.59E-07 4.01E-07 4.70E-07 1.13E-06 3.77E-07 1.16E-14 3 2 3.87E-15 3.87E-15

Goldstrike Autoclave 6.57E-07 7.71E-07 5.50E-07 1.98E-06 6.59E-07 1.23E-14 3 2 4.09E-15 4.09E-15

Goldstrike Autoclave 1.42E-06 1.65E-07 1.81E-07 1.77E-06 5.90E-07 5.21E-13 3 2 1.74E-13 1.74E-13

Goldstrike Autoclave 1.42E-06 8.32E-07 4.62E-07 2.71E-06 9.03E-07 4.49E-05 2.32E-13 3 2 7.72E-14 6.50E-11 7.72E-14 1.98E-10

Average = 4.49E-05

DF = 42

t = 2.42

Vb = 6.50E-11

Vw = 1.98E-10

Vt = 2.63E-10

Facility 

99% UPL 

= 8.41E-05
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

26

Carbon Processes with Mercury Retorts

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Marigold EW, P/B 3.68E-01 5.43E-01 4.32E-01 1.34E+00 4.48E-01 7.86E-03 3 2 2.62E-03 2.62E-03

Marigold Retort 7.72E-02 1.14E-01 9.07E-02

Marigold Retort 2.48E-03 1.14E-02 1.37E-03 2.97E-01 4.95E-02 2.52E-03 6 5 4.20E-04 8.41E-04

Marigold Furnace 8.49E-02 4.11E-02 2.52E-02

Marigold Melt Furnace 1.00E-02 1.09E-02 1.74E-02 1.90E-01 3.16E-02 8.13E-04 6 5 1.36E-04 2.71E-04

Marigold Carbon Kiln 7.52E-03 6.29E-03 6.99E-03

Marigold Carbon Kiln 7.36E-04 2.45E-04 3.93E-04 2.22E-02 3.69E-03 5.33E-01 1.27E-05 6 5 2.12E-06 3.18E-03 4.25E-06 3.74E-03

Average = 5.33E-01

DF = 17

t = 2.57

Vb = 3.18E-03

Vw = 3.74E-03

Vt = 6.92E-03

Facility 99% 

UPL = 7.46E-01

Carbon Processes without Mercury Retorts

Facility Unit

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit 

sum 

(lb/ton)

Unit 

average

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF (n1) per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 3 

per unit)

Facility 

Vw

Round Mountain Electrowinning 1.82E-02 7.93E-02 1.90E-02 1.16E-01 3.88E-02 1.23E-03 3 2 4.09E-04 4.09E-04

Round Mountain Melt Furnace 1.49E-04 1.80E-03 1.77E-03

Round Mountain Melt Furnace 3.49E-02 9.59E-03 1.85E-02 6.67E-02 1.11E-02 1.83E-04 6 5 3.05E-05 6.10E-05

Round Mountain Carbon Kiln 2.57E-03 2.86E-03 1.56E-03

Round Mountain Carbon Kiln 1.52E-02 1.02E-02 1.59E-02 4.83E-02 8.05E-03 0.058 4.33E-05 6 5 7.22E-06 4.47E-04 1.44E-05 4.85E-04

Average = 5.80E-02

DF = 12

t = 2.68

Vb = 4.47E-04

Vw = 4.85E-04

Vt = 9.32E-04

Facility 

99% UPL = 1.40E-01
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

27

Non-Carbon Concentrate

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Run 4 

(lb/ton)

Run 5 

(lb/ton)

Unit 

sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility 

total 

(lb/ton)

Unit 

variance

No. of 

runs 

per 

unit

DF

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw 

(m = 3 

per 

unit)

Facility 

Vw

Coeur 

Rochester 

Mine

Refinery 

Furnace 5.96E-02 1.17E-01 2.28E-02

Coeur 

Rochester 

Mine

Refinery 

Furnace 2.47E-02 1.20E-02 2.94E-02 2.66E-01 4.43E-02 1.53E-03 6 5 2.55E-04 5.10E-04

Coeur 

Rochester 

Mine

Retorts 

#1 & #2 3.41E-03 3.45E-03 9.24E-05 2.31E-03 1.95E-03

Coeur 

Rochester 

Mine

Retorts 

#1 & #2 2.93E-04 1.53E-02 4.20E-03

Coeur 

Rochester 

Mine Retort 4.17E-05 1.84E-04 5.39E-05 3.13E-02 2.84E-03 4.71E-02 1.96E-05 11 10 1.78E-06 2.57E-04 6.52E-06 5.17E-04

Average 

= 4.71E-02

DF = 15

t = 2.60

Vb = 2.57E-04

Vw = 5.17E-04

Vt = 7.74E-04

Facility 

99% 

UPL = 1.19E-01
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

28

Appendix F. Beyond the Floor – Ore Pretreatment

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

Gold 

Quarry

Roaster/Calcine 

quench 1.35E-05 9.56E-06 1.37E-05

Gold 

Quarry

Roaster/Calcine

quench 1.05E-05 1.33E-05 1.69E-05

Gold 

Quarry

Roaster/Calcine 

quench 8.45E-06 1.05E-05 9.66E-06 1.06E-04 1.18E-05 7.33E-12 9 8 8.14E-13 2.44E-12

Gold 

Quarry

Roaster Ore 

Preheater 3.81E-06 1.62E-06 1.36E-06

Gold 

Quarry

Roaster Ore 

Preheater 7.90E-06 7.51E-06 4.63E-05

Gold 

Quarry

Roaster Ore 

Preheater 2.45E-06 1.04E-06 9.09E-07 7.29E-05 8.10E-06 2.12E-10 9 8 2.35E-11 7.06E-11

Gold 

Quarry Roaster 8.99E-07 6.97E-07 7.87E-07

Gold 

Quarry Roaster 1.27E-06 1.61E-06 6.19E-07

Gold 

Quarry Roaster 4.92E-07 2.75E-07 3.56E-07 7.00E-06 7.78E-07 1.86E-13 9 8 2.07E-14 6.21E-14

Gold 

Quarry

Roaster Ore 

Grinder 1.66E-06 2.06E-06 1.48E-06

Gold 

Quarry

Roaster Ore 

Grinder 1.50E-06 4.82E-06 1.75E-06 1.33E-05 2.21E-06 1.67E-12 6 5 2.79E-13 5.58E-13

Gold 

Quarry

Roaster/Calcine 

quench 1.67E-05 1.36E-05 9.55E-06

Gold 

Quarry

Roaster/Calcine 

quench 1.27E-05 1.46E-05 2.11E-05

Gold 

Quarry

Roaster/Calcine 

quench 1.03E-05 1.31E-05 1.32E-05 1.25E-04 1.39E-05 3.68E-05 1.19E-11 9 8 1.32E-12 2.60E-11 3.96E-12 7.77E-11

Goldstrike

Roaster Ore 

Preheater 1.82E-07 2.84E-07 2.03E-07

Goldstrike

Roaster Ore 

Preheater 5.58E-07 3.86E-07 3.35E-07

Goldstrike

Roaster Ore 

Preheater 1.16E-06 9.01E-07 1.72E-07

Goldstrike

Roaster Ore 

Preheater 1.42E-06 7.29E-07 1.72E-07 6.49E-06 5.41E-07 1.78E-13 12 11 1.48E-14 5.94E-14

Goldstrike

Roaster Ore 

Preheater 4.90E-06 2.66E-06 9.66E-07

Goldstrike

Roaster Ore 

Preheater 1.53E-05 3.27E-06 5.09E-07

Goldstrike

Roaster Ore 

Preheater 5.52E-07 5.52E-07 2.55E-07

Goldstrike

Roaster Ore 

Preheater 1.06E-06 5.52E-07 2.55E-07 3.08E-05 2.57E-06 1.81E-11 12 11 1.51E-12 6.04E-12
***E.O. 12866 Review – Draft – Do Not Cite, Quote, or Release During Review***

29

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

Goldstrike Roaster 1.56E-04 1.23E-04 1.14E-04

Goldstrike Roaster 2.70E-05 2.70E-05 3.70E-05

Goldstrike Roaster 3.67E-05 3.26E-05 2.47E-05 5.78E-04 6.42E-05 2.65E-09 9 8 2.95E-10 8.85E-10

Goldstrike

Roaster/Calcine 

quench 8.18E-06 5.56E-06 5.40E-06 1.91E-05 6.38E-06 2.43E-12 3 2 8.09E-13 8.09E-13

Goldstrike

Roaster/Calcine 

quench 6.67E-06 7.07E-06 6.25E-06 2.00E-05 6.66E-06 8.04E-05 1.67E-13 3 2 5.57E-14 2.97E-10 5.57E-14 8.92E-10

Jerritt 

Canyon Ore dryer 4.06E-06 8.58E-06 5.77E-06

Jerritt 

Canyon Ore dryer 1.15E-06 9.71E-06 3.42E-06 3.27E-05 5.45E-06 1.05E-11 6 5 1.76E-12 3.51E-12

Jerritt 

Canyon Roaster 4.42E-05 4.47E-05 5.14E-05

Jerritt 

Canyon Roaster 4.48E-05 2.07E-05 2.99E-05

Jerritt 

Canyon Roaster 7.01E-06 7.92E-06 8.36E-06 2.59E-04 2.88E-05 3.31E-10 9 8 3.68E-11 1.10E-10

Jerritt 

Canyon Roaster 5.50E-05 4.65E-05 2.82E-05

Jerritt 

Canyon Roaster 5.80E-06 4.30E-06 4.65E-06 1.44E-04 2.41E-05 5.83E-05 5.16E-10 6 5 8.60E-11 1.25E-10 1.72E-10 2.86E-10

Twin 

Creeks Autoclave 1.66E-05 4.34E-05 3.06E-05

Twin 

Creeks Autoclave 2.35E-05 7.76E-05 8.70E-06

Twin 

Creeks Autoclave 7.07E-05 3.51E-05 3.25E-05

Twin 

Creeks Autoclave 6.40E-05 3.99E-05 3.29E-05

Twin 

Creeks Autoclave 2.99E-05 5.92E-05 7.98E-05

Twin 

Creeks Autoclave 3.18E-05 2.09E-05 1.86E-05

Twin 

Creeks Autoclave 2.59E-06 2.42E-06 2.29E-06 7.23E-04 3.44E-05 5.75E-10 21 20 2.74E-11 1.92E-10

Twin 

Creeks Autoclave 3.42E-05 1.64E-05 1.60E-05

Twin 

Creeks Autoclave 2.60E-05 1.49E-05 1.04E-05

Twin 

Creeks Autoclave 1.46E-05 2.72E-05 2.39E-05

Twin 

Creeks Autoclave 1.06E-05 7.50E-06 6.36E-06

Twin 

Creeks Autoclave 6.12E-06 5.74E-06 5.88E-06 2.26E-04 1.51E-05 4.95E-05 8.16E-11 15 14 5.44E-12 3.28E-11 2.72E-11 2.19E-10
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30

Facility Unit 

Run 1 

(lb/ton)

Run 2 

(lb/ton)

Run 3 

(lb/ton)

Unit sum 

(lb/ton)

Unit 

average 

(lb/ton)

Facility

total 

(lb/ton)

Unit 

variance

No. of 

runs per 

unit

DF 

(n-1) 

per 

unit

Variance 

of unit 

average

Facility 

variance

Vw (m = 

3 per 

unit)

Facility 

Vw

Average 

of top 5: 5.62E-05 t DF: 123 Vb:

3.00E11

Vw 

(unpooled

): 3.69E-10

56 t(.99): 2.36
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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 OF

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 
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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?
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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

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. Startup, Shutdown and Malfunctions

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 Information60

A. Does this action apply to me

The regulated categories and entities potentially affected 

by this final rule include:

?
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Category NAICS 

code1

Examples of 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: 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 

?
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(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: 

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
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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.

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 

Applicability
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include laboratories (see CAA section 112(c)(7)) , 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. 

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 

Ore Pretreatment Processes
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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. 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 additional beyondthe-floor analyses for the ore pretreatment affected source. 

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

for existing ore pretreatment processes include calomel-based

mercury scrubbers on roasters and venturi scrubbers on 

autoclaves and ancillary roaster operations. After applying the 

beyond-the-floor 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 floor analysis for existing and new ore pretreatment 

processes. Table 2 summarizes the results of the beyond-thefloor 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 84

99% UPL existing (MACT Floor) 158

99% UPL new1 (MACT Floor) 84

 1 The MACT Floor for new sources is based on the average performance of 

Facility A plus an amount to account for variability (i.e., 45 + 39 = 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
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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 

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 

Carbon Processes
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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 

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 
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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

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
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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 

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.

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
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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, 

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 

Compliance Dates
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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 for compliance tests 

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 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.

Compliance Requirements

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 
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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 

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 
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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.

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. Monitoring Requirements
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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 
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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-based 

mercury scrubbers (i.e., mercury scrubbers) that are used to 

control emissions from roasters. The final rule does not 

include the requirement to monitor pressure drop across calomelbased 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 
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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 

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 
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in the parameter value (e.g., liquid flow rate or line pressure)

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 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 
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receive the final 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 ore pretreatment 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 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 

proposed rule required a full week of such sampling, but, as 
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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 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 pressure drop was 

outside the manufacturer’s recommended operating range, take 

corrective actions to return the pressure drop back in range,
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and record the corrective actions taken. At proposal, the water 

flow rate 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 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. 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 
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small pilot scale mining operations, that process or produce 

less than 50 pounds of concentrate per year are excluded from 

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. 

IV. Summary of Responses to Major Comments

A. Statutory Requirements 
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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. Several other 

commenters claimed that EPA did not provide the legal basis for 

listing gold mining as a source category under section 

112(c)(6). These commenters stated that EPA does not have the 

authority to list gold mining 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 
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all listed sources by 2000, a task that would be impossible if 

EPA had the authority to add source categories ad infinitum. 

Response

Some commenters questioned EPA’s estimated emissions of 4.4 

tons from this source category in the 1990 baseline year; 

however, they did not estimate or explain what the baseline 

emission should have been. EPA continues to believe that its 

baseline emissions estimate is reasonable and, as mentioned 

above, we have not received other estimates. We disagree with 

the comment that, because EPA already completed this listing 

obligation when it published its section 112(c)(6) category list 

on April 10, 1998 (63 FR 17838), EPA has no authority to list 

gold mine ore processing and production as a category under 

section 112(c)(6). Section 112(c)(6) requires that EPA list 

sufficient categories to ensure that sources accounting for not 

less than 90 percent of the aggregate emissions of each of the 

: Section 112(c)(6) does not prescribe any 

methodology that EPA must follow in listing source categories, 

thus giving EPA discretion on how to carry out this obligation. 

Therefore, unless sources from the gold mine ore processing and 

production area source category did not emit mercury in the 1990 

baseline year, EPA has authority to list that category for 

regulation pursuant to section 112(c)(6). 
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HAP specified in section 112(c)(6) are subject to standards. 

Although section 112(c)(6) requires that EPA list the categories 

by 1995, it contains no language prohibiting EPA from revising 

the list. In fact, in order for EPA to regulate sufficient 

source categories to meet the 90 percent statutory requirement, 

EPA must have the authority to revise the category list, 

including adding categories, should it discover during the 

course of developing section 112(c)(6) standards that such 

revision is necessary to meet the statutory 90 percent

obligation. Further, were the section 112(c)(6) list of source 

categories that EPA published in 1998 considered final and 

unchangeable under the CAA, the CAA would have made the list 

judicially reviewable upon publication to ensure that EPA can 

later regulate sufficient categories to meet the statutory 90

percent requirement. To the contrary, CAA section 112(e)(4)

states that listing of a source category under section 112(c) is 

not a final agency action subject to judicial review, but such 

action may be reviewed when EPA issues the standards. In light 

of section 112(e)(4), and were EPA prohibited from revising the 

category list, as the commenter claimed, it could potentially be 

impossible for EPA to meet the 90 percent requirement under 

section 112(c)(6). We do not believe that Congress would have 
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structured the CAA in a way that could potentially make it 

impossible for EPA to meet a statutory requirement. For the 

reasons stated above, we believe that EPA has authority to 

revise the section 112(c)(6) category list as necessary to 

ensure that sufficient categories are subject to regulation 

under section 112(c)(6). 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. 

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 MACTlevel 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 
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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: We believe it is appropriate to promulgate MACT 

standards for mercury emissions for this industry. Based on our 

1990 baseline inventory for 112(c)(6) and other emission 

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. In summary, we believe it is necessary and 

appropriate to promulgate a federal NESHAP for existing and new 

gold mine ore processing and production facilities.
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2. Emission Standards for HAP Other than Mercury

Comment

The commenter said that EPA appears to believe that because 

gold mines are 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 

: 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 clear 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. 
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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 D.C. 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 
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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 conflicts with the National Lime decision.

There are several important distinctions between the 

National Lime case and this final rule for Gold Mine Ore 

Processing and Production area source category. The relevant 

issue in the portion of the opinion referenced by the commenter 

was how EPA set standards for a HAP where there are no control 

technologies being used to control that HAP. Accordingly, the 

court’s statements described above in National Lime were made to

address this specific issue and in the context of a major source 

category. Today’s final rule applies to EPA’s obligation to 

issue emission standards for a listed area source category under 

CAA section 112(c)(6). On the other hand, the National Lime 

case addressed a major source category and not area source 

categories or EPA’s obligation under section 112(c)(6). 
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We further note that the applicable lists of HAP under the 

CAA differ for major and area source categories. Under CAA 

section 112(c), a major source category must be listed for 

regulation if it emits any of the HAP listed in section 112(b). 

Accordingly, in National Lime, the court referenced the 112(b) 

HAP list in requiring that EPA “promulgate regulations 

establishing emission standards for each category or subcategory 

of major sources ... of hazardous air pollutants listed for 

regulation.” Id. Unlike major source categories, the CAA does 

not require that EPA list an area source category for regulation 

if it emits a pollutant listed in section 112(b). Rather, an 

area source category may be listed for regulation under section 

112 if EPA makes an adverse effect finding pursuant to Section 

112(c)(3) or if that area source category emits an urban HAP 

listed under section 112(k) or a HAP listed in section 

112(c)(6). The gold mine ore processing and production area 

source category is listed for regulation under section 112(c)(6) 

because it emits mercury, one of the HAP listed in section 

112(c)(6). Because the listed HAP at issue is only mercury, we 

have established in this final rule mercury emission standards 

for this area source category. For the reasons stated above,

EPA disagrees with the comment that it must set emission 
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standards for all HAP emitted by the gold mine ore processing 

and production area source category. 

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. The 

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 
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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

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 have not included fugitive mercury emissions 

at gold mine facilities in our 1990 baseline emissions estimate, 

or in our more recent emissions estimates, largely due to the 

lack of information about these emissions. Accordingly, these 

fugitive emissions are not part of the 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 from gold mine facilities. The 

recent preliminary research suggests that some fugitive 

emissions may be occurring at these facilities from large nonpoint 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 peerreviewed.
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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, 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. 
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4. Major Source Determination

Comment

The commenter also stated that EPA’s failure to apply the 

same variability analysis in calculating gold mines’ potential 

to emit that was used in setting floors was internally 

inconsistent, unexplained, and arbitrary and capricious. The 

commenter 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 

: One commenter noted that the proposal states the 

following: “data indicate that the gold mining processing and 

production category consists of only area sources (i.e. 

facilities that emit less than 10 tons per year of any single 

HAP and less than 25 tons per year of any combination of HAP).” 

75 Fed. Reg. at 22479. The commenter also claimed that the 

proposal indicates that actual emissions of hydrogen cyanide at 

a few facilities are near the major source threshold. The 

commenter continued by saying that “by basing its evaluation of 

whether gold mines are major sources on their actual emissions 

instead of their potential emissions, EPA violates both the 

Clean Air Act and its own regulations.” 
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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 and resulted in higher 

calculated HCN emissions than may actually be present. For 

instance, EPA did not apply what the commenters believe to be a 

key correction factor to account for the fact that much of the 

mass transfer of HCN for large surface areas is expected to be 

gas phase limited. Application of this correction factor would 

have reduced the estimates for HCN emissions from the mines 

tested by about 40-50%. The commenters also stated that fence 

line testing at selected gold mine operations demonstrated that 

there was no concern with fenceline levels of HCN emissions, and 

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 
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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

Nevertheless, 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 

: As explained above, some commenters believe that 

EPA’s estimates of hydrogen cyanide emissions are overly 

conservative (i.e., overestimated). Other commenters believe 

that EPA’s estimates do not reflect the “potential to emit” from 

these sources. However, these commenters also incorrectly 

suggested that EPA’s estimates included only actual emissions. 
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section 112(a)(1) and 40 CFR 63.2. For each gold mine facility 

in our inventory we developed a range of estimated emissions, 

including an upper-end estimate for each facility. Based on 

these estimates the largest facility emits between 5 and 9 tons 

per year of hydrogen cyanide. All other facilities emit less 

than this level. Based on test data, all facilities emit less 

than 25 tons per year for the sum of all HAP. Our analysis of 

the test data include calculations for estimated emissions based 

on facilities operating at full capacity. 

We understand that these facilities 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. Nevertheless, based on our current 

knowledge of these management practices and based on the results 

of the emissions testing, we believe that these facilities are 

area sources. We have no information that would indicate these 

facilities are major sources. Accordingly, we are taking final 
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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). In addition, we intend to send 

letters to various Gold Production companies pursuant to Section 

114 of the Clean Air Act to obtain additional information which 

we will use to further evaluate the facilities’ potential to 

emit and to address any remaining questions regarding their area 

source status.

5. Title V Permit Exemption

Comment

• EPA did not properly determine whether some or all sources 

in the category are major sources by determining each 

source’s potential to emit. 

: 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:

• 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. 
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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 
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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 
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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 
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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 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 
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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 nontitle 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 
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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, multinational, corporations. Therefore, we do not believe that the 
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argument of financial burden, which has supported title V 

exemption for other source categories, applies to the gold 

mining industry. 

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 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 
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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

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 

: 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.
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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 
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a reconstruction.

Response

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:

: 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:

(1) The fixed capital cost of the new components 

exceeds 50 percent of the fixed capital cost that 

would be required to 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 
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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 

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 
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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 
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would exempt placer and other non-leaching operators, including 

both small commercial efforts as well as individual recreationtype 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: As mentioned above, we have clarified in this 

final rule that this area source category does not include 

laboratories (see CAA section 112(c)(7)), 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 50 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 

production and processing source category. All the facilities 

in our current inventory, as well as the facilities considered 

in developing the 1990 baseline emissions inventory, process or 
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produce more than 4,000 lb/yr of concentrate. We believe that 

emissions from the very small scale operations described above 

to be very minimal, especially in comparison to the mercury 

emissions from operations that are regulated under this rule, 

which process or produce concentrate at amounts far above this 

threshold. 

However, we believe that the 100 pounds of concentrate cutoff suggested by the commenters is too high. We believe that 50 

pounds of concentrate per year more appropriately reflect these 

very small 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. We are also not making the exemption of 

facilities that process less than 1,000 tons per year of ore 

because we believe this exemption is not necessary or 

appropriate. 

C. MACT Floors

1. Consideration of Variability in Determining Floors

Comment: One commenter acknowledged that EPA may consider 
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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 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, 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 does not yield an accurate picture of 

the best sources 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: It is EPA policy to allow for variance in test 

data, between units, and among facilities when developing the 
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MACT standard. For this rule, we used the UPL analysis on the 

emissions data for the top five performing sources to account 

for the variance. We believe that this calculation method does 

yield an accurate picture of the best performers. It is an 

incorrect statement that no sources among the best performers 

(i.e., the top five performers for this final rule) would ever 

exceed the floor limit. The variability that is accounted for 

in the UPL analysis of historical data would apply to future 

data as well. Thus, although the average of several data sets 

may show a top performing source meeting the emission standard 

by a wide 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.

The operating conditions under which emissions measurements 

are made for a given process unit will directly affect those 

measurements. For example, emissions obtained from a process 

that is operating poorly will almost certainly be higher than 

when operating properly. Therefore, the process that is 

operating poorly will be less likely to be included in the pool 

of best performers than if it were operating properly.

We believe the data we used to calculate the MACT limits

are based on representative and normal performance of the 
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sources for many reasons. First, the test results that we are 

using in our MACT database are tests conducted under Nevada’s 

mercury emission control program, and some of these tests are 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 

floor 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 
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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 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. The MACT floor is based on the average 

performance of the top performers, and we can and must develop a 

MACT floor limit from this average that accounts for 

variability. We accomplish this by calculating the MACT floor 

limit from this average performance and account for variability 

by using the 99 percent UPL, which is discussed in more detail 

in the Summary of Public Comments and Responses document in the 

docket for this rulemaking. It is not appropriate to ignore the 

variability in the data because that would be contrary to 

established statistical theory and practice, and it is also at 

odds with recent judicial decisions. Finally, on a practical 

level and in terms of achievability, ignoring variability and 

using only the average performance would virtually guarantee 
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that some of even the best performers would exceed the floor 

limit.

Comment

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 

: 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.
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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 variability used in 

the development of the proposed new source MACT for the ore 

: 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. 
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pretreatment group appeared to be inconsistent with other data, 

and it was due in part to two tests of the ore preheater/dry 

grinding process at Goldstrike that the commenter identified. 

As discussed in more detail below in this preamble, we have 

obtained new (additional) test data for the ore pretreatment 

group, including the ore preheater/dry grinding process at 

Goldstrike. 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). In addition, we have performed additional analyses 

using the newer test data, which show lower emissions and lower 

variability than the previous data available at the time of 

proposal. Also, we have conducted additional beyond-the-floor 

analyses. The variability associated with the new source MACT 

is now significantly lower than the estimate of variability at 

proposal, and the new source standard in the final rule is more 

stringent than the proposed standard. As discussed in more 

detail below, MACT for new sources for the ore pretreatment 

group has been reduced from 149 lb/million tons of ore at 

proposal to 84 lb/million tons in the final rule. 
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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 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 these well-controlled facilities 

and used the information to conduct MACT floor analysis, as 
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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 it 

has been demonstrated as achievable in practice by facilities 

that installed mercury emission controls. 

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° to 700°C, releasing 

gaseous elemental mercury, whereas autoclaves commonly reach 

temperatures of 175° to 230°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 
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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. Moreover, autoclaves and 

roasters process that same input material (i.e., ore) and are 

intended for the same purpose (to oxidize the ore). Therefore, 
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we believe that it is appropriate to maintain the ore 

pretreatment affected source as we had proposed, keeping 

roasting operations and autoclaves together.

Comment

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. 

: 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.

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 
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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, it is not 

appropriate to 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 wet scrubbers, calomel 

scrubbers, and carbon adsorbers, depending on the specific 

processing unit included in the affected source. We conducted a 

beyond-the-floor analysis during the development of the proposed 

rule. The roasters were already equipped with very good mercury 

controls, and we did not identify any beyond-the-floor options 

for the roasters. However, we identified as a beyond-the-floor 
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control for autoclaves the installation of both a refrigeration 

unit (or condenser) and a carbon adsorber. Since our proposal, 

we have identified a beyond-the-floor control option (carbon 

adsorption) for the ore pre-heaters/dryers 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 

believe that the 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
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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. 

Beyond-the-floor analyses have been included in the 

determination of the MACT limit for existing ore pre-treatment 

affected sources based on the emissions level achieved by the 

best controlled similar source. We did not go beyond-the-floor 

the floor for new sources because we did not identify a feasible 

and cost-effective technology that would achieve reduction 

greater than the new source 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.

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 
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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 megawatthours 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), 
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and our review of these details indicates it to be a reasonable

cost estimate. 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 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 the proposed new gold mine in 

Alaska, the commenters’ estimate of 3,200 lb/yr of mercury 

emissions is inaccurate and a significant overestimate for 

several reasons. The two primary reasons are that, based on 

available information, if the facility is built, only an 
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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). 

With the new source MACT standard in the final rule that is 

about two times more stringent 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 they could not meet 

the new source MACT limit, installation of carbon adsorbers 

would likely reduce the emissions below 45 lb/million tons, we 

believe that, if the facility is built, emissions would quite 
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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 D.C. 

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 
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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 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 reexamination of the emission controls and 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 mercury emissions from carbon processes at this facility are 

a factor of 10 less than the next “best” performer (Facility N) 
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and a factor of 23 less than the average of the top 5 performing 

facilities in the proposed rule. This level of emissions is due 

primarily to the very low levels of mercury in the ore rather 

than having better emission controls than those found at the 

other top performing facilities. Facility M has good controls

for mercury emissions from its carbon processes, but they are 

not as effective as the controls at Facility N. Facility N has 

state-of-the-art controls. The difference is further manifested 

by the differences in the processing train for the carbon group 

in that mercury retorts are not needed or used at Facility M to 

recover mercury because the mercury levels are so low. 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 two 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 MACT for 

sources that are in the carbon processes with mercury retorts 
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and those without mercury retorts, 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 

that 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). 

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. In light of the small 

emission reduction and the high cost effectiveness of this 

beyond-the-floor option, we decided not to go beyond-the-floor. 

Therefore, for existing sources of carbon processes without 

mercury retorts, the MACT floor limit is the MACT standard for 

this affected source. 
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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 newlyinstalled 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). 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 or 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 
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retorts, the MACT floor limit is the MACT standard for this 

affected source.

5. Compliance Alternative for New Carbon Process Sources

Comment

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. 

: 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.

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 
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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 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.
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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, 

and the fact that these controls have not yet been demonstrated 

on autoclaves and ore preheaters, 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 
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provide adequate time for existing sources to comply with the 

final emission standards.

Comment

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. 

: 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. 

Response: The permitting authority needs to be able to 
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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 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. 
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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 (μg/m3)). 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 for the 12 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 
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located in the same State (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 of sources 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 
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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 on Method 29 data. The 

commenter said that the typical gas streams associated with the 

mining industry have high particulate loadings, high mercury 

concentrations, sulfur dioxide (SO2), and contain particulatebound mercury. The commenter also stated that the alternative 

methods were not developed specifically for the gold mining 

industry and their typical gas streams and concluded that the 

results from the various alternative methods will yield varying 

results, will not be comparable, and will provide inconsistent 

reporting of overall mercury emissions.

Response

When specifying the minimum requirements for compliance 

: 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 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. 
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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 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 mass emissions rate is 

greater than the allowable emission limit, the owner or operator 

may use procedures that produce lower MDL results and repeat the 
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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).

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, 

however alternative methods (such as 30B and OHM) may prove to 

be more appropriate under certain circumstances. 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), could be used to demonstrate compliance for 

this source category if approved by the permitting authority. 

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 
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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 proposes 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 
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levels of mercury in the ore and different operational measures 

within the control of the facility.

Other commenters supported EPA’s decision to require 

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 
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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 this alternative because Method 30B 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 

are appropriate and necessary for roasters. 

We believe that the mercury concentrations monitoring for 

roasters along with the parametric monitoring of all control 

devices on all units is an acceptable approach to assure 

compliance with the emission standards. Parametric monitoring 

of control devices assures that the control devices are 

operating properly (and reducing emissions) on an ongoing basis. 
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We disagree with the commenter that the proposed monitoring 

requirements render the rule unenforceable. The mercury 

operating limits in both the proposed and final rules are 

enforceable, and any exceedance of these 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 disagree with commenters that CEMS should be required 

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. With 

regard to some of the units without carbon adsorbers, we believe 
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that annual tests coupled with appropriate parametric monitoring 

of the control devices 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 
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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 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 
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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 
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demonstrate compliance for sources controlled with carbon 

adsorbers. Such an approach does not provide for continuous 

monitoring. The parametric monitoring and operating limits 

specified in this final rule provide ongoing assurance that 

control devices are properly operated and maintained between 

emissions tests, and exceedances of the operating limit require 

corrective action. We also reject the comment that all 

operating limits should be based solely on manufacturer 

specifications and/or in consultation with the permitting 

authority. Control device operating parameter values often are 

site-specific and are associated with a level of emissions from 

the source. In order to ensure continuous compliance, certain 

parameter limits generally should 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 
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applicable range of proper operation. A facility may request us 

to consider alternative procedures for setting operating limits 

on a case-by-case basis under 40 CFR 63.8, if desired. 

Comment: Some commenters stated that their established 

parametric monitoring programs are sufficient to confirm that 

mercury emission controls are functioning properly for roasters. 

The commenters also stated that the NMCP permits have required 

parametric limits and that additional CEMS for mercury would 

neither improve the operation of these current controls, nor 

reduce mercury emissions. The commenters concluded that the 

operating parameters monitored on a regular basis are key 

parameters for measuring the efficiency and operation of the 

mercury controls and that operating each of these units within 

the optimum ranges ensures that mercury emissions are being 

effectively controlled. 

Response: As discussed above, we do not believe parametric 

monitoring alone is sufficient for roasters because of the very 

high mercury emission potential, unless the facility has 

adequately demonstrated that the mercury emissions from the 

roasters are consistently very low (e.g., less than 10 pounds 

per million tons). Nevertheless, we have concluded that the 

combined approach of annual stack compliance testing along with 
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the 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. 

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.
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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 

good 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 
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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. 

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 
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by the integrated sample.

As discussed above, the final rule includes continuous 

sampling with PS 12B as a second option for monitoring roasters. 

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, parametric 

monitoring of the mercury scrubber must also be performed. For 

the third 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 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 
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rules for emissions of organic compounds exiting carbon 

adsorbers. That monitoring has proven to be effective to 

prevent or detect breakthrough, and the same principles apply 

here for mercury. 

Comment: Commenters stated that CEMS for gold mining 

operations are not capable of accurately measuring mercury 

emissions and that there are three major challenges with the 

feasibility of mercury CEMS for the gold mining industry: 

mercury CEMS calibration, sample transport, and system 

operability and reliability. The commenters are concerned with 

the unavailability of a means to calibrate the CEMS for roasters 

because existing calibrator designs are simply not capable of 

generating mercury concentrations high enough to provide 

meaningful upscale calibration points that correspond to gold 

mining source characteristics. The commenters noted the 

unavailability of National Institute of Standards and Technology 

(NIST) traceable calibration gases and stated that the current 

calibration standards traceable to NIST do not apply to the full 

range of mercury concentrations that can be present in the 

exhaust gases of roasters. The commenters concluded that the 

lack of a NIST-traceable standard is a fatal flaw that precludes 

using mercury CEMS to monitor roaster emissions. Regarding 
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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.
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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

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

μg/m3

. 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 

: Regarding the feasibility of using CEMS to 

monitor mercury emissions from roasters, CEMS have been 

demonstrated for process units similar to roasters (e.g., coalfired power plants), and we believe there is no technical reason 

why they will not work for the roasters. Many of the issues 

with mercury CEMS have been resolved as facilities have gained 

experience with their use. As we discussed in the proposal 

preamble, CEMS manufacturers supply calibration standards for 

the ranges of concentrations seen at roasters.
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concentrations that exceed the concentrations typically seen 

from roasters.

After consideration of public comments, we continue to 

believe CEMS are a valuable tool and a reasonable option for

monitoring mercury concentration and comparing those 

concentrations to the operating limit that is established by 

CEMS measurements made during the compliance test. In addition, 

we are promulgating a second option for continuous monitoring 

using PS 12B, and a third option of twice per month sampling

using PS 12B or Method 30B coupled with parametric monitoring. 

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 to ensure that emissions from the 

roasters are not exceed 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. 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.

We understand the commenter’s concerns regarding the 

transport of samples and converter failures. We have revised 

the final rule to give facilities 3 years to successfully 
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operate controls and monitoring equipment to be able to comply 

with the MACT standards. 

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 
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concentration monitoring procedures. As described in section 

IV.D. of this preamble, we have established in the final rule a 

compliance date that is 3 years after the effective date of the 

final rule for existing sources, partly to allow sources time to 

ensure they can successfully comply with the monitoring 

requirements, but mainly to allow time to install new mercury 

emission controls that we believe will be necessary to meet the 

emission standards in the final rule.

We agree that mercury concentration measurements are not

direct measurements of the emissions rate from the affected 

source and that flow rate, production, and other factors need to 

be considered. These are some of the reasons that the operating 

limit is not being used as a direct measure of compliance with 

the MACT limit. 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.

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 
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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, the final rule requires monitoring mercury 

concentration twice per month (at least 11 days apart). 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 
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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 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 
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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 three test runs. 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 
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that these parameters were intended to monitor for physical 

processes, and the scrubbers on roasters often include chemical 

reactions, which are not monitored. 

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° to 134°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°F and monitors the 
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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 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. The facility must

monitor the temperature hourly, and any exceedance of the upper 

limit for temperature would trigger corrective action. 
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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. The final rule requires hourly monitoring 

and that corrective action is triggered if the flow rate or line

pressure falls below the established parameters.

Regarding the acceptability of parameter values that were 
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approved by permitting authorities prior to this final rule, 

such values must be established as specified in the final rule 

and are not presumed in advance to be acceptable.

5. Exceeding the Operating Limits for Roasters

Comment

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 

: 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. 
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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, 
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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 believe the 

requirements of this final rule provide assurance that timely 
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corrective actions are taken when a monitoring parameter is 

exceeded, and we have included requirements for testing for 

mercury concentrations to determine if the corrective actions 

were successful or if a deviation has occurred. The final rule 

includes parametric monitoring of the mercury scrubbers applied 

to roasters to control mercury. If a parameter is outside of 

the established range or limit, corrective actions are 

triggered. If corrective actions do not result in the parameter 

reading being corrected and verified within 48 hours, a mercury 

concentration measurement (using method 30B, 12B, 29, or OHM) 

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 the 

operating limit is exceeded, the exceedance must be reported as 

a deviation and the facility must conduct a full compliance test 
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within 40 days to determine if the source is in compliance with 

the MACT limit. 

Comment

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 

: 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.
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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 or Method 12B or 30B) 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 
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used to establish a new operating limit for mercury 

concentration.

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 §63.11647(a)(5) (i.e., facilities 

exempt from mercury concentration monitoring by having 

demonstrated that their roaster emissions are less than 10 
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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 or Method 30B or Method 29 

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 3 in the final rule, 

where the value for “Ctrap” in Equation 3 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 
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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.

Comment

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 

: 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.
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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: 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 additional scrubbers that are used to remove PM and SO2 prior 

to the mercury scrubber. We are also clarifying in the final 

rule that when the primary mercury emission control device is a 

carbon adsorber, which is the last stage of the exhaust gas 

cleaning treatment train, it is necessary to monitor the carbon 

adsorber to ensure it is operating properly and controlling 
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mercury emissions, and the rule does not require that scrubbers 

in the gas treatment train (typically used for control of PM

and/or SO2) prior to the carbon adsorber be monitored under this 

rule for mercury emissions. However, if there is no carbon 

adsorber or mercury scrubber, and the 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) for pressure drop and flow rate 

with operating limits that either are 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 scrubbers on ore preheaters and quenching if there is no 

carbon adsorber or mercury scrubber in the exhaust gas treatment 

train.

We are clarifying in the final rule that condensers, such 

as those found at roasters and 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 NSPS subpart is appropriate 

for this NESHAP for mercury. The comment suggesting an option 
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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 the option in the final rule,

as suggested by the commenter.

6. Carbon Adsorber Temperature Monitoring

Comment: Several commenters stated their concern with the 

proposed requirement of monitoring gas stream temperature at the 

inlet to the carbon adsorber and maintaining the inlet 

temperature below the maximum temperature established during the 

compliance test. They noted that the primary purpose for 

monitoring the inlet gas stream temperature of carbon adsorbers 

is to prevent spontaneous combustion of the sulfidized carbon in 

the adsorber, not to detect excursions in mercury emissions. 

The commenters also stated that some carbon adsorption systems 

heat the gas stream prior to the carbon adsorber to prevent 

moisture buildup and/or subsequent condensation in the carbon. 

The commenters explained that the NMCP already requires that the 

exit gas temperature of condensers prior to the carbon adsorbers 
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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 
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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 
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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 
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monitoring would not necessarily detect if mercury had been 

desorbed and excess emissions occurred.

7. Monitoring of Multiple Units Ducted to One Stack

Comment

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. 

: 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. 

Response: We agree with the commenters in general and have 
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made the following clarifications in the final rule. If two 

roasters share a common control device and stack, the mercury 

concentration operating limit, as well as stack testing for 

compliance will be based on both roasters operating. 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 and the stack testing for 

compliance must 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.

8. 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 
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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

V. Summary of Environmental, Economic and Health Benefits? 

: We agree with the commenter and have removed 

this requirement 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 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.
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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 post-MACT. The annual emissions expected after MACT 

(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 
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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. Nonhazardous solid waste (spent carbon containing mercury that must 

be regenerated or disposed of) would increase by about 7 tons 

per year.

VI. Startup, Shutdown, and Malfunctions

The United States Court of Appeals for the District of 

Columbia Circuit vacated portions of two provisions in EPA’s CAA 

Section 112 regulations governing the emissions of HAP during 

periods of startup, shutdown, and malfunction (SSM). Sierra 

Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 130 

S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the 

SSM exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 

63.6(h)(1), that are part of a regulation, commonly referred to 

as the “General Provisions Rule,” that EPA promulgated under 

section 112 of the CAA. When incorporated into CAA Section 
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112(d) regulations for specific source categories, these two 

provisions exempt sources from the requirement to comply with 

the otherwise applicable CAA section 112(d) emission standard 

during periods of SSM.

Consistent with Sierra Club v. EPA, EPA has established 

standards in this rule that apply at all times. In establishing 

the standards in this rule, EPA has taken into account startup 

and shutdown periods and, for the reasons explained below, has 

not established different standards for those periods. We have 

no reason to believe that emissions are different during startup 

or shutdown. The mercury emissions from significant emissions 

points are, or will be, controlled by condensers, carbon bed 

filters, or mercury scrubbers. The carbon beds, which are 

applied to most types of process units to control mercury 

emissions, will capture mercury as well, or better, during 

periods of startup and shutdown as compared to normal 

operations. Condensers also capture mercury as well, or better, 

during periods of startup and shutdown as compared to normal 

operations. Mercury scrubbers are applied only to roasters, and 

roasters operate continuously for most of the year. Roasters 

are normally shutdown purposely only about once per year 

(typically for a few weeks) for maintenance and repair. The 
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facilities that have roasters ensure that the control devices 

(including the mercury scrubbers) are fully operational before 

the roasters are started. Also, the controls stay operational 

throughout the shutdown period. Therefore, no increases in

emissions are expected during the startup and shutdown periods. 

Moreover, the MACT limit is based on pounds of mercury emissions 

per rate of input or production over a 12-month rolling average 

(e.g., pounds of mercury per million tons of input ore). 

Therefore, no change in the emissions standards are needed for 

periods of startup and shutdown. 

Periods of startup, normal operations, and shutdown are all 

predictable and routine aspects of a source’s operations. 

However, by contrast, malfunction is defined as a “sudden, 

infrequent, and not reasonably preventable failure of air 

pollution control and monitoring equipment, process equipment or 

a process to operate in a normal or usual manner” (40 CFR 63.2). 

EPA has determined that malfunctions should not be viewed as a 

distinct operating mode and, therefore, any emissions that occur 

at such times do not need to be factored into development of CAA 

section 112(d) standards, which, once promulgated, apply at all 

times. In Mossville Environmental Action Now v. EPA, 370 F.3d 

1232, 1242 (D.C. Cir. 2004), the court upheld as reasonable 
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standards that had factored in variability of emissions under 

all operating conditions. However, nothing in section 112(d) or 

in caselaw requires that EPA anticipate and account for the 

innumerable types of potential malfunction events in setting 

emission standards. See, Weyerhaeuser v Costle

Further, it is reasonable to interpret section 112(d) as 

not requiring EPA to account for malfunctions in setting 

emissions standards. For example, we note that Section 112 uses 

the concept of “best performing” sources in defining MACT. 

Applying the concept of “best performing” to a source that is 

malfunctioning presents significant difficulties. The goal of 

best performing sources is to operate in such a way as to avoid 

malfunctions of their units. 

, 590 F.2d 1011, 

1058 (D.C. Cir. 1978) (“ In the nature of things, no general 

limit, individual permit, or even any upset provision can 

anticipate all upset situations. After a certain point, the 

transgression of regulatory limits caused by ‘uncontrollable 

acts of third parties,’ such as strikes, sabotage, operator 

intoxication or insanity, and a variety of other eventualities, 

must be a matter for the administrative exercise of case-by-case 

enforcement discretion, not for specification in advance by 

regulation.”) 
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Moreover, even if malfunctions were considered a distinct 

operating mode, we believe it would be impracticable to take 

malfunctions into account in setting CAA section 112(d) 

standards for the gold mine ore processing and production source 

category. As noted above, by definition, malfunctions are 

sudden and unexpected events and it would be difficult to set a 

standard that takes into account the myriad different types of 

malfunctions that can occur across all sources in the category. 

Moreover, malfunctions can vary in frequency, degree, and 

duration, further complicating standard setting. 

We believe it unlikely that malfunctions would result in 

violations of the standards in this rule. The primary pollution 

control devices used in this industry to control mercury 

emissions (condensers, carbon bed filters and mercury scrubbers) 

are not expected to be significantly affected by SSM events. 

Moreover, the standards in this rule are expressed in terms of 

long-term averages (e.g., pounds of mercury emitted per rate of 

production over a 12-month period). We believe that 

malfunctions (which are expected to occur quite infrequently 

over that period) are not likely to result in an exceedance of 

the standards.

In the unlikely event that a source fails to comply with 
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the applicable CAA section 112(d) standards as a result of a 

malfunction event, EPA would determine an appropriate response 

based on, among other things, the good faith efforts of the 

source to minimize emissions during malfunction periods, 

including preventative and corrective actions, as well as root 

cause analyses to ascertain and rectify excess emissions. EPA 

would also consider whether the source's failure to comply with 

the CAA section 112(d) standard was, in fact, “sudden, 

infrequent, not reasonably preventable” and was not instead 

“caused in part by poor maintenance or careless operation.” 40 

C.F.R. § 63.2 (definition of malfunction).

Finally, EPA recognizes that even equipment that is 

properly designed and maintained can sometimes fail and that 

such failure can sometimes cause an exceedance of the relevant 

emission standard. (See, e.g., State Implementation Plans: 

Policy Regarding Excessive Emissions During Malfunctions, 

Startup, and Shutdown (Sept. 20, 1999); Policy on Excess 

Emissions During Startup, Shutdown, Maintenance, and 

Malfunctions (Feb. 15, 1983)). EPA is therefore adding to the 

final rule an affirmative defense to civil penalties for 

exceedances of emission limits that are caused by malfunctions. 

See 40 CFR 63.11651 (defining “affirmative defense” to mean, in 
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the context of an enforcement proceeding, a response or defense 

put forward by a defendant, regarding which the defendant has 

the burden of proof, and the merits of which are independently 

and objectively evaluated in a judicial or administrative 

proceeding.). We also have added other regulatory provisions to 

specify the elements that are necessary to establish this 

affirmative defense; the source must prove by a preponderance of 

the evidence that it has met all of the elements set forth in 

63.11648. (See 40 C.F.R. 22.24). The criteria ensure that the 

affirmative defense is available only where the event that 

causes an exceedance of the emission limit meets the narrow 

definition of malfunction in 40 C.F.R. 63.2 (sudden, infrequent, 

not reasonable preventable and not caused by poor maintenance 

and/or careless operation). For example, to successfully assert 

the affirmative defense, the source must prove by a 

preponderance of the evidence that excess emissions “[w]ere 

caused by a sudden, short, infrequent, and unavoidable failure 

of air pollution control and monitoring equipment, process 

equipment, or a process to operate in a normal or usual 

manner....” The criteria also are designed to ensure that steps 

are taken to correct the malfunction, to minimize emissions in 

accordance with section 63.11646(b) and to prevent future 
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malfunctions. For example, the source must prove by a 

preponderance of the evidence that “[r]epairs were made as 

expeditiously as possible when the applicable emission 

limitations were being exceeded...” and that “[a]ll possible steps 

were taken to minimize the impact of the excess emissions on 

ambient air quality, the environment and human health....” In any 

judicial or administrative proceeding, the Administrator may 

challenge the assertion of the affirmative defense and, if the 

respondent has not met its burden of proving all of the 

requirements in the affirmative defense, appropriate penalties 

may be assessed in accordance with Section 113 of the Clean Air 

Act (see also 40 C.F.R. Part 22.77).

VII. Statutory and Executive Order Reviews

A. 

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. 

Executive Order 12866: Regulatory Planning and Review

B. Paperwork Reduction Act
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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 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.

. The Information 

Collection Request (ICR) document prepared by EPA has been 

assigned EPA ICR No. 2383.01.

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.
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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. 

The Regulatory Flexibility Act generally requires an agency 

Regulatory Flexibility Act
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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 
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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. 

This final rule does not contain a federal mandate that may 

result in expenditures of $100 million or more for state, local, 

Unfunded Mandates Reform Act
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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. 

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. 

Executive Order 13132: Federalism

In the spirit of Executive Order 13132, and consistent with 
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EPA policy to promote communications between EPA and State and 

local governments, EPA specifically solicited comment on this 

proposed action from State and local officials.

F. 

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. 

Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments

G. 

EPA interprets Executive Order 13045 (62 F.R. 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: Protection of Children from 

Environmental Health and Safety Risks
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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. 

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.

Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use

I. 

Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (“NTTAA”), Public Law No. 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 

National Technology Transfer and Advancement Act
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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. 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, 29, 30B, Method 7471A, “Mercury in 

Solid or Semisolid Waste (Manual Cold-Vapor Technique),” and 

ASTM D6784–02, “Standard Test Method for Elemental, Oxidized, 

Particle-Bound and Total Mercury in Flue Gas Generated from 
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Coal-Fired Stationary Sources,” (incorporated by reference – see 

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 (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 

Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations
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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. 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. 

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 

Congressional Review Act
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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 [INSERT DATE OF PUBLICATION IN THE FEDERAL 

REGISTER].
National Emission Standards for Hazardous Air Pollutants: Gold 

Mine Ore Processing and Production Area Source Category; and 

Addition to Source Category List for Standards

Page 152 of 203

List of Subjects in 40 CFR Parts 9 and 63

Environmental protection, Air pollution control, Hazardous 

substances, Incorporations by reference, Reporting and 

recordkeeping requirements.

___________

Dated: 

____________________________

Lisa P. Jackson,

Administrator.
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For the reasons stated in the preamble, title 40, chapter I, of 

the Code of Federal Regulations is amended as follows:

PART 9—[AMENDED]

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

Subpart A—[Amended]

., 

6901–6992k, 7401–7671q, 7542, 9601–9657, 11023, 11048.

* * * * *

2. The table in §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:

§9.1 OMB Approvals under the Paperwork Reduction Act.

* * * * *

40 CFR citation OMB control No.

* * * * *
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National Emission Standards for Hazardous Air Pollutants for 

Source Categories3

* * * * *

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]

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

follows:

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

Subpart A—[Amended]

.

4. Section 63.14 is amended by revising paragraphs (b)(35)

and (i)(1) and by adding paragraph (k)(1)(v) to read as follows:

§63.14 Incorporation by reference.

* * * * *

(b) * * *

(35) 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), IBR 

approved for §63.11646(a)(1)(v) and table 5 to subpart DDDDD of 

this part.
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* * * * *

(i) * * *

(1) ANSI/ASME PTC 19.10–1981, “Flue and Exhaust Gas 

Analyses [Part 10, Instruments and Apparatus],” IBR approved for 

§§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) Method 7471A, “Mercury in Solid or Semisolid Waste 

(Manual Cold-Vapor Technique),” IBR approved for 

§63.11647(f)(2).

* * * * *

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 
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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 Affirmative Defense for Exceedance of Emission Limits

During Malfunction.

63.11649 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

§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 

§63.11651, that is an area source.

?
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(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 

§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.

§63.11641 What are my compliance dates?
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(a) If you own or operate an existing affected source, you 

must comply with the applicable provisions of this subpart no 

later than [INSERT DATE 3 YEARS AFTER PUBLICATION OF THIS FINAL 

RULE IN THE FEDERAL REGISTER].

(b) If you own or operate a new affected source, and the 

initial startup of your affected source is on or before [INSERT 

DATE OF PUBLICATION OF THIS FINAL RULE IN THE FEDERAL REGISTER], 

you must comply with the provisions of this subpart no later 

than [INSERT DATE OF PUBLICATION OF THIS FINAL RULE IN THE 

FEDERAL REGISTER].

(c) If you own or operate a new affected source, and the 

initial startup of your affected source is after [INSERT DATE OF 

PUBLICATION OF THIS FINAL RULE IN THE FEDERAL REGISTER], you 

must comply with the provisions of this subpart upon startup of 

your affected source.

Standards and Compliance Requirements

§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.
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(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. 

§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

?
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days of the compliance date for all process units at new and 

existing affected sources according to the requirements in 

paragraphs (a)(1) through (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 A1), or Method 2G (40 CFR part 60, appendix A-2) to determine the 

volumetric flow rate of the stack gas.

(iii) Method 3, 3A, or 3B (40 CFR part 60, appendix A-2) 

to determine the dry molecular weight of the stack gas. You may 

use ANSI/ASME PTC 19.10-1981, “Flue and Exhaust Gas Analyses” 

(incorporated by reference-see §63.14) as an alternative to EPA 

Method 3B.
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(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 

D6784–02; “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 §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 Ontario Hydro Method, determine 

sample time and volume according to the testing criteria set 
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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 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 mass emissions rate is 

greater than the allowable 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 
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the permit authority the process throughput for each test run. 

For sources with multiple emission units (e.g., two roasters) 

ducted to a common control device and stack, compliance testing 

must be performed with all affected emissions units in operation

if possible. If it is not possible to test all sources ducted 

to a common control device simultaneously, the sources can be 

tested separately. In such cases, any source that is not tested 

initially must be tested as soon as is practicable.

(4) Calculate the mercury emission rate, based on the 

average of 3 test run values, for each process unit using 

Equation (1) of this section:

E = Cs * Qs * K (Eq. 1)

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 report to the permit authority 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 
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rate in lb/hr for each process unit by the number of hours each 

process unit operated during those full calendar months prior to 

the initial compliance test. After the initial compliance test, 

for subsequent compliance tests, determine the mercury mass

emissions for the 12 month period 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 (4) of this section, and the tests were representative 

of current operating processes and conditions. 

(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-

month period preceding the performance test by multiplying the 

emission rate in lb/hr for each process unit by the number of 

hours each process unit 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,
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daily and monthly totals in tons of ore according to paragraphs 

(a)(8)(i) and (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 and before the carbon-in-leach tanks.

(ii) Measure the weight or the density and volumetric flow 

rate of the ore slurry as it is fed to the autoclave(s).

(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. 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, record, 

and report to the permit authority 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 
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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 noncarbon concentrate processes on a daily and monthly basis and 

report the monthly values to the permit authority.

(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 (iv) of this section to 

determine initial compliance with the emission standards in 

§63.11645. 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 
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mercury mass emissions 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 these process 

units during those same full months following the compliance 

date. 

(ii) For carbon processes with mercury retorts, divide the 

sum of mercury mass emissions 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 

processed in these process units during those same full months 

following the compliance date.

(iii) For carbon processes without mercury retorts, divide 

the sum of mercury mass emissions 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 

processed in these process units during those same full months 

following the compliance date.

(iv) For non-carbon concentrate processes, divide the sum 

of mercury mass emissions from mercury retorts and melt furnaces 

during the initial number of full months between the compliance 
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date and the initial compliance tests by the total amount of 

concentrate processed in these process units during those same 

full months following the compliance date.

(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 §63.11645. 

(i) For ore pretreatment processes, divide the sum of 

mercury mass emissions 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 that

12-month period.

(ii) For carbon processes with mercury retorts, divide the 

sum of mercury mass emissions 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 processed in these process units in that 12-month 

period.

(iii) For carbon processes without mercury retorts, divide 

the sum of mercury mass emissions from all carbon kilns, preg 

tanks, electrowinning, and melt furnaces in the 12-month period 
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preceding a compliance test by the total amount of concentrate 

processed in these process units in that 12-month period.

(iv) For non-carbon concentrate processes, divide the sum 

of mercury mass emissions from mercury retorts and melt furnaces 

in the 12-month period preceding a compliance test by the total 

amount of concentrate 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.

(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), (2), or (3) of 

this section and establish operating limits for mercury 

concentration as described in paragraph (a)(4) of this section.

§63.11647 What are my monitoring requirements?
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(1) Perform sampling and analysis of the roaster’s exhaust 

for mercury concentration using EPA Performance Specification 

12B or EPA Method 30B 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 30 days using a 

shorter sampling duration.

(ii) If the any mercury concentration measurement from the 

twice per month sampling with method 12B or 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 
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results. Moreover, within 96 hours of the exceedance, the owner 

or operator must measure the concentration again (with method 

12B or 30B) 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 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 (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 monitoring requirements in 

§63.8, except that 63.8(c)(1)(i) and (iii) no longer apply. 
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Moreover, 63.8(d)(3) applies except the last sentence, which 

refers to an SSM plan. SSM plans are no longer required. 

(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) 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 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 results may also be used to 

establish a new operating limit for mercury concentration (in 

accordance with paragraph (e) of this section).
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(iii) You must submit a monitoring plan that includes 

quality assurance and quality control (QA/QC) procedures 

sufficient to demonstrate the accuracy of 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.

(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 30 days using a shorter sampling 

duration.
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(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 method 12B 

or 30B 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 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 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), (2), or (3) of this section

concurrently while you are conducting your annual compliance 

performance stack test according to the procedures in 

§63.11646(a).
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OLR = Ctest * (EL/CT) (Eq 2)

where

OLR = mercury concentration operating limit for the 

roaster (in micrograms per cubic meter);

Ctest = average mercury concentration measured by the 

monitoring procedures (PS 12A or PS 12B or 30B) 

during the annual 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), (2), or (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 §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 
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procedures in §63.11646(a)(1) through (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 the lowest value 

during any run of the initial compliance test, and your maximum 
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scrubber inlet temperature limit is the highest measured during 

any run of the initial 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 procedures in paragraph (c)(1) or (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. 

Alternatively, the mercuric ion concentration and chloride ion 

concentration ranges for each calomel-based mercury control 
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system may be 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 calomelbased mercury control system must be based on the manufacturer’s 

specifications. Alternatively, the oxidation reduction 

potential and pH range for each calomel-based mercury control 

system may be 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 
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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 method 12B or 30B) 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 

§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. The owner or operator must conduct a compliance test 

pursuant to §63.11646(a) within 40 days to determine if the 
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roaster operations are in compliance with the MACT emission 

standard. 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),(2), or (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

(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 
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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 as calculated from Equation (3) of this section.

OLC = Ctrap * (EL/CT) (Eq 3)

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 

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 
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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 EPA 

Method 7471A (incorporated by reference - see §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 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 autoclave, carbon kiln, melt 

furnace, and mercury retort equipped with a carbon adsorber. 

Establish a maximum value for the inlet temperature either 
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during the annual performance test as required in §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°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 

follow the requirements for outlet concentration measurement in 

paragraph (f)(1) of this section. If the concentration is below 

90 percent of the operating limit, you may set a new temperature 

operating limit 10°F above the previous operating limit. If the 

concentration is above 90 percent of the operating limit, you 

must take corrective action to reduce the temperature back below 

the temperature operating limit and again measure the outlet 

concentration according to paragraph (f)(1) of this section. If 

the concentration is still above 90 percent of the operating 

limit, then you must change the carbon in the bed within 30 days

and report the deviation to your permitting 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 
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drop. Establish a minimum value as the operating limit either 

during the performance test required in §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 

average value during any test run or no lower than 10 percent of 

the average value measured during the test. For wet scrubbers 

on an autoclave, establish the 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 within 40 days to determine if the 

source is in compliance with the MACT limit. 

(i) You may conduct additional compliance tests according 

to the procedures in §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 
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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.

§63.11648

In response to an action to enforce the standards set forth 

in paragraph §63.11645 you may assert an affirmative defense to 

a claim for civil penalties for exceedances of such standards 

that are caused by malfunction, as defined at 40 CFR 63.2. 

Appropriate penalties may be assessed, however, if you fail to 

meet your burden of proving all of the requirements in the 

affirmative defense. The affirmative defense shall not be 

available for claims for injunctive relief.

 Affirmative Defense for Exceedance of Emission Limit 

During Malfunction. 

(a) To establish the affirmative defense in any action to 

enforce such a limit, you must timely meet the notification 

requirements in paragraph (b) of this section, and must prove by 

a preponderance of evidence that:

 (1) The excess emissions: 

(i) Were caused by a sudden, short, infrequent, and 

unavoidable failure of air pollution control and monitoring 

equipment, process equipment, or a process to operate in a 
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normal or usual manner, and 

(ii) Could not have been prevented through careful 

planning, proper design or better operation and maintenance 

practices; and

 (iii) Did not stem from any activity or event that could 

have been foreseen and avoided, or planned for; and

(iv) Were not part of a recurring pattern indicative of 

inadequate design, operation, or maintenance; and

 (2) Repairs were made as expeditiously as possible when the 

applicable emission limitations were being exceeded. Off-shift 

and overtime labor were used, to the extent practicable to make 

these repairs; and

 (3) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and

 (4) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, severe personal injury, or severe 

property damage; and

 (5) All possible steps were taken to minimize the impact of 

the excess emissions on ambient air quality, the environment and 

human health; and

 (6) All emissions monitoring and control systems were kept 
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in operation if at all possible; and

 (7) All of the actions in response to the excess emissions 

were documented by properly signed, contemporaneous operating 

logs; and

 (8) At all times, the facility was operated in a manner 

consistent with good practices for minimizing emissions; and

(9) A written root cause analysis has been prepared to 

determine, correct, and eliminate the primary causes of the 

malfunction and the excess emissions resulting from the 

malfunction event at issue. The analysis shall also specify, 

using best monitoring methods and engineering judgment, the 

amount of excess emissions that were the result of the 

malfunction. 

(b) Notification. The owner or operator of the facility 

experiencing an exceedance of its emission limit(s) during a 

malfunction shall notify the Administrator by telephone or 

facsimile (FAX) transmission as soon as possible, but no later 

than two business days after the initial occurrence of the 

malfunction, if it wishes to avail itself of an affirmative 

defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense shall also 

submit a written report to the Administrator within 30 days of 

the initial occurrence of the exceedance of the standard in 
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§63.11645 to demonstrate, with all necessary supporting 

documentation, that it has met the requirements set forth in 

paragraph (a) of this section.

§63.11649 What are my notification, reporting, and 

recordkeeping requirements

(a) You must submit the Initial Notification required by 

§63.9(b)(2) no later than 120 calendar days after the date of 

publication of the final rule in the 

?

Federal Register

(b) You must submit an initial Notification of Compliance 

Status as required by §63.9(h).

or within 

120 days after the source becomes subject to the standard. The 

Initial Notification must include the information specified in 

§63.9(b)(2)(i) through (b)(2)(iv). 

(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 §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 
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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 (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 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 

include records of the occurrence and duration of each 

malfunction of operation (i.e., process equipment) or the air 

pollution control and monitoring equipment.

The report must also include a description of actions taken 

by an owner or operator during periods of malfunction of an 
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affected source to minimize emissions in accordance with 

§63.11646(c), including corrective actions taken to restore 

malfunctioning process and air pollution control and monitoring 

equipment to its normal or usual manner of operation. 

(e) You must keep the records specified in paragraphs 

(e)(1) through (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 §63.10(b)(2)(xiv), you must keep a copy 

of each 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 §§63.11646 and 63.11647, and the information identified in 

paragraphs (c)(2)(i) through (vi) of this section for each 

corrective action required by §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 
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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 §63.11646(a)(5) and records of the 

monthly quantity of ore and concentrate processed as required by 

§63.11646(a)(10).

(f) Your records must be in a form suitable and readily 

available for expeditious review, according to §63.10(b)(1). As 

specified in §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 §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 
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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

§63.11650 What General Provisions apply to this subpart

Table 1 to this subpart shows which parts of the General 

Provisions in §§63.1 through 63.16 apply to you.

?

§63.11651 What definitions apply to this subpart

Terms used in this subpart are defined in the Clean Air 

Act, in §63.2, and in this section as follows:

?

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 

regarding which the defendant has the burden of proof, and the 

merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.

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° to 430°F.

Calomel-based mercury control system means a mercury 

emissions control system that uses scrubbers to remove mercury 
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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 used as a subsititute 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 used as a subsititute for activated carbon,

to recover (adsorb) gold from the pregnant cyanide solution.
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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

(1) Fails to meet any requirement or obligation 

established by this subpart, including but not limited to any 

emissions limitation or work practice standard;

means any instance where an affected source 

subject to this subpart, or an owner or operator of such a 

source:

(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 
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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. An operation that processes or 

produces less than 50 pounds of concentrate per year is 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 or 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 
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electrowinning, the Merrill-Crowe process, or other processes 

for facilities without mercury retorts. 

Mercury retort means a vessel that is operated under a 

partial vacuum at approximately 1100° to 1300oF 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 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 
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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. 

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 

?
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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 §63.11640, the compliance date requirements in 

§63.11641, and the applicable standards in §63.11645.

(2) Approval of an alternative nonopacity emissions 

standard under §63.6(g). 

(3) Approval of a major change to a test method under 

§63.7(e)(2)(ii) and (f). A “major change to test method” is 

defined in §63.90(a).

(4) Approval of a major change to monitoring under 

§63.8(f). A “major change to monitoring” is defined in 
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§63.90(a).

(5) Approval of a waiver of recordkeeping or reporting 

requirements under §63.10(f), or another major change to 

recordkeeping/reporting. A “major change to 

recordkeeping/reporting” is defined in §63.90(a).

§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 §63.11650, you must comply with the applicable 

General Provisions requirements according to the following 

table: 

Citation Subject

Applies to 

subpart 

EEEEEEE Explanation

§63.1(a)(1), 

(a)(2), (a)(3), 

(a)(4), (a)(6), 

(a)(10)–(a)(12), 

(b)(1), (b)(3), 

(c)(1), (c)(2), 

(c)(5), (e)

Applicability Yes

§63.1(a)(5), 

(a)(7)–(a)(9), 

(b)(2), (c)(3), 

(c)(4), (d)

Reserved No

§63.2 Definitions Yes

§63.3 Units and 

Abbreviations

Yes

§63.4 Prohibited 

Activities and 

Circumvention

Yes

§63.5 Preconstruction Yes
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Review and 

Notification 

Requirements

§63.6(a), (b)(1)–

(b)(5), (b)(7), 

(c)(1), (c)(2), 

(c)(5), 

(e)(1)(iii),(f)(2

), (f)(3), (g), 

(i), (j)

Compliance with 

Standards and 

Maintenance 

Requirements

Yes

63.6(e)(1)(i) General Duty to 

minimize emissions

No. 

See 

63.11646(b)

for general 

duty 

requirement

See 

63.11646(b)

63.6(e)(1)(ii) Requirement to 

correct 

malfunctions as 

soon as possible.

No

63.6(e)(3) SSM Plan 

requirements

No

63.6(f)(1) SSM exemption No Malfunctions 

are no longer 

exempt. All 

excursions are 

violations and 

there is no 

need to 

specify 

corrections.

§63.6(h)(1), 

(h)(2), 

(h)(4),(h)(5)(i), 

(ii), (iii) and 

(v), (h)(6)–

(h)(9)

Compliance with 

Opacity and 

Visible Emission 

Limits

No Subpart 

EEEEEEE does 

not contain 

opacity or 

visible 

emission 

limits.

§63.6(b)(6), 

(c)(3), (c)(4), 

(d), (e)(2), 

(e)(3)(ii), 

Reserved No
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(h)(3), 

(h)(5)(iv)

§63.7, except 

(e)(1) 

Applicability and 

Performance Test 

Dates

Yes

§63.7(e)(1) Performance 

Testing

See 63.11646 See 

63.11646(a)(3)

§63.8(a)(1), 

(b)(1), (f)(1)-

(5), (g)

Monitoring 

Requirements

Yes

§63.8(a)(2), 

(a)(4), (b)(2)-

(3), (c)(ii), 

(d)(i), (e), 

(f)(6), (g)

Continuous 

Monitoring Systems

(CMS)

Yes Except cross 

references to 

SSM 

requirements 

in §63.6(e)(1) 

and (3) do not 

apply

63.8(c)(1)(i) General duty to 

minimize emissions 

and CMS operation

No See 

63.11646(b)

63.8(c)(1)(iii) Requirement to 

develop SSM Plan 

for CMS

No

63.8(d)(3) Written procedures 

for CMS

Yes, except 

for last 

sentence.

Last sentence 

refers to an 

SSM Plan which 

is no longer 

required.

§63.8(a)(3) [Reserved] No

§63.9(a), (b)(1), 

(b)(2)(i)-(v), 

(b)(4), (b)(5), 

(c), (d)(1), 

(d)(2), (e), (g), 

(h)(1)–(h)(3), 

(h)(5), (h)(6), 

(i), (j)

Notification 

Requirements

Yes

§63.9(f) No

§63.9(b)(3), Reserved No
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(h)(4)

§63.10(a), 

(b)(1), 

(b)(2)(vi)–(xiv), 

(b)(3), (c)(1)-

(14), (d)(1)-(4), 

(e), (f)

Recordkeeping and 

Reporting 

Requirements

Yes

63.10(b)(2)(i) Recordkeeping of 

occurrence and 

duration of 

startups and 

shutdowns

No

63.10(b)(2)(ii) Recordkeeping of 

malfunctions

No. 

See 63.11649

for 

recordkeeping 

of (1) 

occurrence 

and duration 

and (2) 

actions taken 

during 

malfunction

See 63.11648

63.10(b)(2)(iii) Maintenance 

records

Yes.

63.10(b)(2)(iv) Actions taken to 

minimize emissions 

during SSM

No.

63.10(b)(2)(v) Actions taken to 

minimize emissions 

during SSM

No.

63.10(b)(2)(vi) Recordkeeping for 

CMS malfunctions

Yes.

63.10(b)(2)(vii)-

(ix)

Other CMS 

requirements

Yes.

§63.10(c)(2)–

(c)(4), (c)(9)

Reserved No

63.10(c)(7) Additional Yes
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recordkeeping 

requirements for 

CMS – identifying 

exceedances and 

excess emissions

63.10(c)(8) Additional 

recordkeeping 

requirements for 

CMS – identifying 

exceedances and 

excess emissions

Yes

63.10(c)(10) Recording nature 

and cause of 

malfunctions

No. See 

63.11649 for 

malfunctions 

recordkeeping 

requirements. 

63.10(d)(5) SSM reports No. See 

63.11649 for 

malfunction 

reporting 

requirements. 

See 63.11649

§63.11 Control Device 

Requirements

No

§63.12 State Authority 

and Delegations

Yes

§§63.13–63.16 Addresses, 

Incorporations by 

Reference, 

Availability of 

Information, 

Performance Track 

Provisions

Yes
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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 OF60 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 
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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?
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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

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. Startup, Shutdown and Malfunctions

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 Information60

A. Does this action apply to me

The regulated categories and entities potentially affected 

by this final rule include:

?
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Category NAICS 

code1

Examples of 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: 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 

?
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(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: 

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
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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.

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 

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

prospectors, and very small pilot scale mining operations. 

TheThese 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. 

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 

Ore Pretreatment Processes
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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. 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 additional beyondthe-floor analyseis for the ore pretreatment affected 

sourceroasters, 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 
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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-based

mercury scrubbers on roasters and venturi scrubbers on 

autoclaves and ancillary roaster operations. After applying the 

beyond-the-floor 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 floor analysis for existing and new ore pretreatment 

processes. Table 2 summarizes the results of the beyond-thefloor 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 84

99% UPL existing (MACT Floor) 158

99% UPL new1 (MACT Floor) 84

 1 The MACT Floor for new sources is based on the average performance of 

Facility A plus an amount to account for variability (i.e., 45 + 39 = 84).

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

Facility Average performance

(lb/million tons of ore)

C 37

D 49
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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 

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 

Carbon Processes
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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 

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 
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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

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
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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 

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.

Non-Carbon Concentrate Processes

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

Facility Average performance 

(lb/ton of concentrate)

K 0.047
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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, 

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 

Compliance Dates
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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 for compliance tests 

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 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.

Compliance Requirements

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 
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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 

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 
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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.

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 
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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 thisthe

monitoring option in paragraph (a)(1).

Monitoring Requirements

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 
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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-based 

mercury scrubbers (i.e., mercury scrubbers) that are used to 

control emissions from roasters. The final rule does not 

include the requirement to monitor pressure drop across calomelbased 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 
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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 

following control device monitoring parameter exceedances 
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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., waterliquid flow rate, or line

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 final 

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 ore pretreatment 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 

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 
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30B. The duration of sampling must be at least the minimum 

sampling time specified in Method 30B, 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 §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 the 

monitoring of scrubbers (other than the calomel-based mercury 

scrubbers described above). Under the final rule, owners or 

operations operators are required to monitor and record water 

flow rate (or line pressure) and scrubber pressure drop once per 
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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 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 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.

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, 

Definitions
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and other variations of carbon adsorber design. 

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 

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 
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gold ore processing and production source category. 

IV. 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. Several other 

commenters claimed that EPA did not provide the legal basis for 

listing gold mining as a source category under section 

112(c)(6). These commenters stated that EPA does not have the 

authority to list gold mining 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 
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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

Some commenters questioned EPA’s estimated emissions of 4.4 

tons from this source category in the 1990 baseline year; 

however, they did not estimate or explain what the baseline 

emission should have been. EPA continues to believe that its 

baseline emissions estimate is reasonable and, as mentioned 

above, we have not received other estimates. We disagree with 

the comment that, because EPA already completed this listing 

obligation when it published its section 112(c)(6) category list 

on April 10, 1998 (63 FR 17838), EPA has no authority to list 

gold mine ore processing and production as a category under 

: Section 112(c)(6) does not prescribe any 

methodology that EPA must follow in listing source categories, 

thus giving EPA discretion on how to carry out this obligation. 

Therefore, unless sources from the gold mine ore processing and 

production area source category did not emit mercury in the 1990 

baseline year, EPA has authority to list that category for 

regulation pursuant to section 112(c)(6). 
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section 112(c)(6). Section 112(c)(6) requires that EPA list 

sufficient categories to ensure that sources accounting for not 

less than 90 percent of the aggregate emissions of each of the 

HAP specified in section 112(c)(6) are subject to standards. 

Although section 112(c)(6) requires that EPA list the categories 

by 1995, it contains no language prohibiting EPA from revising 

the list. In fact, in order for EPA to regulate sufficient 

source categories to meet the 90 percent statutory requirement, 

EPA must have the authority to revise the category list, 

including adding categories, should it discover during the 

course of developing section 112(c)(6) standards that such 

revision is necessary to meet the statutory 90 percent

obligation. Further, were the section 112(c)(6) list of source 

categories that EPA published in 1998 considered final and 

unchangeable under the CAA, the CAA would have made the list 

judicially reviewable upon publication to ensure that EPA can 

later regulate sufficient categories to meet the statutory 90

percent requirement. To the contrary, CAA section 112(e)(4)

states that listing of a source category under section 112(c) is 

not a final agency action subject to judicial review, but such 

action may be reviewed when EPA issues the standards. In light 

of section 112(e)(4), and were EPA prohibited from revising the 
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category list, as the commenter claimed, it could potentially be 

impossible for EPA to meet the 90 percent requirement under 

section 112(c)(6). We do not believe that Congress would have 

structured the CAA in a way that could potentially make it 

impossible for EPA to meet a statutory requirement. For the 

reasons stated above, we believe that EPA has authority to 

revise the section 112(c)(6) category list as necessary to 

ensure that sufficient categories are subject to regulation 

under section 112(c)(6). 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. 

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 MACTlevel 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 
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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: We believe it is appropriate to promulgate MACT 

standards for mercury emissions for this industry. Based on our 

1990 baseline inventory for 112(c)(6) and other emission 

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
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facilities. In summary, we believe it is necessary and 

appropriate to promulgate a federal NESHAP for existing and new 

gold mine ore processing and production facilities.

2. Emission Standards for HAP Other than Mercury

Comment

The commenter said that EPA appears to believe that because 

gold mines are needed only to reach the section 112(c)(6)

requirement of 90 percent for mercury and not for the other 

: 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 clear 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. 
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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 D.C. 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 
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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 conflicts with the National Lime decision.

There are several important distinctions between the 

National Lime case and this final rule for Gold Mine Ore 

Processing and Production area source category. First, the 

National Lime case dealt with a major source category. Second, 

the The relevant issue in the portion of the opinion referenced 

by the commenter was how EPA set standards for a HAP where there 

are no control technologies being used to control that HAP. 

Accordingly, the court’s statements described above in National 

Lime were made to address this specific issue and in the context 

of a major source category. Today’s final rule applies to EPA’s 
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obligation to issue emission standards for a listed area source 

category under CAA section 112(c)(6). TheOn the other hand, the

National Lime case didaddressed a major source category and not

address area source categories or EPA’s obligation under section

112(c)(6). 

We further note that the applicable lists of HAP under the 

CAA differ for major and area source categories. Under CAA 

section 112(c), a major source category must be listed for 

regulation if it emits any of the HAP listed in section 112(b). 

Accordingly, in National Lime, the court referenced the 112(b) 

HAP list in requiring that EPA “promulgate regulations 

establishing emission standards for each category or subcategory 

of major sources ... of hazardous air pollutants listed for 

regulation.” Id. Unlike major source categories, the CAA does 

not require that EPA list an area source category for regulation 

if it emits a pollutant listed in section 112(b). Rather, an 

area source category may be listed for regulation under section 

112 if EPA makes an adverse effect finding pursuant to Section 

112(c)(3) or if that area source category emits an urban HAP 

listed under section 112(k) or a HAP listed in section 

112(c)(6). The gold mine ore processing and production area 

source category is listed for regulation under section 112(c)(6) 
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because it emits mercury, one of the HAP listed in section 

112(c)(6). Because the listed HAP at issue is only mercury, we 

have established in this final rule mercury emission standards 

for this area source category. For the reasons stated above,

EPA disagrees with the comment that it must set emission 

standards for all HAP emitted by the gold mine ore processing 

and production area source category. 

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. The 

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 
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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: We have not included fugitive mercury emissions 

at gold mine facilities in our 1990 baseline emissions estimate, 

or in our more recent emissions estimates, largely due to the 

lack of information about these emissions. Accordingly, these 

fugitive emissions are not part of the 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 from gold mine facilities. The 

recent preliminary research suggests that some fugitive 

emissions may be occurring at these facilities from large nonpoint 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-
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reviewed.

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, 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 
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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

The commenter also stated that EPA’s failure to apply the 

same variability analysis in calculating gold mines’ potential 

to emit that was used in setting floors was internally 

inconsistent, unexplained, and arbitrary and capricious. The 

: One commenter noted that the proposal statedstates the 

following: “data indicate that the gold mining processing and 

production source category consists of only area sources; 

however, (i.e. facilities that emit less than 10 tons per year 

of any single HAP and less than 25 tons per year of any 

combination of HAP).” 75 Fed. Reg. at 22479. The commenter also 

claimed that the proposal indicatedindicates that actual 

emissions of hydrogen cyanide (HCN) at a few facilities were are 

near the major source threshold. The commenter concluded that 

EPA violates both the CAA and its own regulationscontinued by 

saying that “by basing its evaluation of whether gold mines are 

major sources on their actual emissions instead of their 

potential emissions., EPA violates both the Clean Air Act and 

its own regulations.” 
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commenter 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 and resulted in higher 

calculated HCN emissions than may actually be present. For 

instance, EPA did not apply what the commenters believe to be a 

key correction factor to account for the fact that much of the 

mass transfer of HCN for large surface areas is expected to be 

gas phase limited. Application of this correction factor would 

have reduced the estimates for HCN emissions from the mines 

tested by about 40-50%. The commenters also stated that fence 

line testing at selected gold mine operations demonstrated that 
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there was no concern with offsitefenceline levels of HCN 

emissions, and 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: Based on available data we estimate that the 

largest emitting facility emits between 5 to 9 tons per year of 

hydrogen cyanide, and that all other facilities emit less than 

this level. Based on test data, all facilities emit less than
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25 tons per year for the sum of all HAP. Our analysis of the 

test data included calculations based on facilities operating at 

full capacity. We understand that these facilities implement 

various management practices 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). Most 

companies are signatories to the international Cyanide 

Management Code, which includes a number of provisions to 

minimize the use and release of cyanide. 

As a commenter correctly notes, 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. In determining a 

source’s potential to emit, we may consider physical and 

operation limitations that are “federally enforceable,” which is 

defined in our regulation as limitations and conditions that are 

enforceable by EPA and the citizens under the CAA or by EPA 

under other statutes. See 40 CFR 63.2 for definitions of 

“potential to emit” and “federally enforceable.” It is our 

current understanding that the above-mentioned standards and 
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agreements for implementing hydrogen cyanide management 

practices are not federally enforceable, as that term is 

defined. Accordingly, we believe that the emissions reductions

achieved through these management practices would not be 

considered in determining gold mine facilities’ potential to 

emit. We currently do not have sufficient information to 

quantify the emissions reductions achieved through these 

management practices. However, based on our current knowledge 

of these management practices and our hydrogen cyanide emission 

estimates, we believe that most of these facilities are area 

sources. 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). 

In addition, we plan to evaluate the area source status of 

the largest facilities by gathering additional information about 

these management practices, including information on their 

emissions reduction potential. We plan to use the additional 

information to further evaluate the potential to emit of these 

few large facilities and subsequently address their cyanide and 

other emissions if necessary or appropriate.

Response: As explained above, some commenters believe that 
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EPA’s estimates of hydrogen cyanide emissions are overly 

conservative (i.e., overestimated). Other commenters believe 

that EPA’s estimates do not reflect the “potential to emit” from 

these sources. However, these commenters also incorrectly 

suggested that EPA’s estimates included only actual emissions. 

Nevertheless, 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. For each gold mine facility 

in our inventory we developed a range of estimated emissions, 

including an upper-end estimate for each facility. Based on 

these estimates the largest facility emits between 5 and 9 tons 

per year of hydrogen cyanide. All other facilities emit less 

than this level. Based on test data, all facilities emit less 

than 25 tons per year for the sum of all HAP. Our analysis of 

the test data include calculations for estimated emissions based 

on facilities operating at full capacity. 

We understand that these facilities 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, 
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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. Nevertheless, based on our current 

knowledge of these management practices and based on the results 

of the emissions testing, we believe that these facilities are 

area sources. We have no information that would indicate these 

facilities are major sources. 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). In addition, we intend to send 

letters to various Gold Production companies pursuant to Section 

114 of the Clean Air Act to obtain additional information which 

we will use to further evaluate the facilities’ potential to 

emit and to address any remaining questions regarding their area 

source status.

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:
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• 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 
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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 
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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 
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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 
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that would be imposed on these area sources from title V 

permitting 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 nontitle 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 
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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. 
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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, multinational, corporations. Therefore, we do not believe that the 

argument of financial burden, which has supported title V 

exemption for other source categories, applies to the gold 

mining industry. 

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 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 many more 

facilities in Nevada that will be subject to the final rule, as 
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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 those 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 
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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 
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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

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:

: 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:

(1) The fixed capital cost of the new components 

exceeds 50 percent of the fixed capital cost that 

would be required to 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.
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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 processes

with a mercury retorts group 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 
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processes with mercury retorts is installed at a facility in 

addition to 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 
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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 recreationtype 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: As mentioned above, we have clarified in this 

final rule that this area source category does not include 
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laboratories (see CAA section 112(c)(7)), 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 50 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 

production and processing source category. All the facilities 

in our current inventory, as well as the facilities considered 

in developing the 1990 baseline emissions inventory, process or 

produce more than 4,000 lb/yr of concentrate. We believe that 

emissions from the very small scale operations described above 

to be very minimal, especially in comparison to the mercury 

emissions from operations that are regulated under this rule, 

which process or produce concentrate at amounts far above this 

threshold. 

However, we believe that the 100 pounds of concentrate cutoff suggested by the commenters is too high. We believe that 50 

pounds of concentrate per year more appropriately reflect these 

very small 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 
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gravity flotation processes and perform thermal processing of

concentrate in melt furnaces, which can have significant 

emissions of mercury. We are also not making the exemption of 

facilities that process less than 1,000 tons per year of ore 

because we believe this exemption is not necessary or 

appropriate. 

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 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, 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. 
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 The commenter said that using an upper prediction limit 

to set standards reflecting the statistical worst performance 

these sources could have does not yield an accurate picture of 

the best sources 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: It is EPA policy to allow for variance in test 

data, between units, and among facilities when developing the 

MACT standard. For this rule, we used the UPL analysis on the 

emissions data for the top five performing sources to account 

for the variance. We believe that this calculation method does 

yield an accurate picture of the best performers. It is an 

incorrect statement that no sources among the best performers 

(i.e., the top five performers for this final rule) would ever 

exceed the floor limit. The variability that is accounted for 

in the UPL analysis of historical data would apply to future 

data as well. Thus, although the average of several data sets 

may show a top performing source meeting the emission standard 

by a wide 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.
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The operating conditions under which emissions measurements 

are made for a given process unit will directly affect those 

measurements. For example, emissions obtained from a process 

that is operating poorly will almost certainly be higher than 

when operating properly. Therefore, the process that is 

operating poorly will be less likely to be included in the pool 

of best performers than if it were operating properly.

We believe the data we used to calculate the MACT limits

are based on representative and normal performance of the 

sources for many reasons. First, the test results that we are 

using in our MACT database are tests conducted under Nevada’s 

mercury emission control program, and some of these tests are to 

determine whether a facility is in compliance with a State or 

operating permit emission standardrequirements. Facilities 

typically try to perform as well as they can during

performancesuch tests to avoid violations, fines, and other 

enforcement actions. 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.
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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 

floor 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 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. The MACT floor is based on the average 

performance of the top performers, and we can and must develop a 
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MACT floor limit from this average that accounts for 

variability. We accomplish this by calculating the MACT floor 

limit from this average performance and account for variability 

by using the 99 percent UPL, which is discussed in more detail 

in the Summary of Public Comments and Responses document in the 

docket for this rulemaking. It is not appropriate to ignore the 

variability in the data because that would be contrary to 

established statistical theory and practice, and it is also at 

odds with recent judicial decisions. Finally, on a practical 

level and in terms of achievability, ignoring variability and 

using only the average performance would virtually guarantee 

that some of even the best performers would exceed the floor 

limit.

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 
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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 
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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. 

We agree with the commenter that the variability used in 

the development of the proposed new source MACT for the ore 

pretreatment group appeared to be inconsistent with other data, 

and it was due in part to two tests of the ore preheater/dry 

grinding process at Goldstrike that the commenter identified. 

As discussed in more detail below in this preamble, we have 

obtained new (additional) test data for the ore pretreatment 

group, including the ore preheater/dry grinding process at 

Goldstrike. 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 
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rulemaking). In addition, we have performed additional analyses 

using the newer test data, which show lower emissions and lower 

variability than the previous data available at the time of 

proposal. Also, we have conducted additional beyond-the-floor 

analyses. The variability associated with the new source MACT 

is now significantly lower than the estimate of variability at 

proposal, and the new source standard in the final rule is more 

stringent than the proposed standard. As discussed in more 

detail below, MACT for new sources for the ore pretreatment 

group has been reduced from 149 lb/million tons of ore at 

proposal to 84 lb/million tons in the final rule. 

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 
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facilities are already well controlled for many 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 these 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 it 

has been demonstrated as achievable in practice by facilities 

that installed mercury emission controls. 

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 
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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° to 700°C, releasing 

gaseous elemental mercury, whereas autoclaves commonly reach 

temperatures of 175° to 230°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 
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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. Moreover, autoclaves and 

roasters process that same input material (i.e., ore) and are 

intended for the same purpose (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

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 

: 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.
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claims that EPA has a statutory obligation to ensure that its 

new source standards reflect the maximum achievable reduction in 

emissions. 

Response

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 

: 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, it is not 

appropriate to include data for that facility in the analysis, 

which is now based on the only four facilities currently 

operating.
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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 wet scrubbers, calomel 

scrubbers, and carbon adsorbers, depending on the specific 

processing unit included in the affected source. We conducted a 

beyond-the-floor analysis during the development of the proposed 

rule. The roasters were already equipped with very good mercury 

controls, 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. Since our proposal, 

we have identified a beyond-the-floor control option (carbon 

adsorption) for the ore pre-heaters/dryers 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 
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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 

160118 lb/yr of mercury emissions would be achieved at an 

overall cost effectiveness of about $10,00013,800 per pound of 

mercury. We believe that the 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. 

Beyond-the-floor analyses have been included in the 

determination of the MACT limit for existing ore pre-treatment 

affected sources based on the emissions level achieved by the 

best controlled similar source. We did not go beyond-the-floor 
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the floor for new sources because we did not identify a feasible 

and cost-effective technology that would achieve reduction 

greater than the new source 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.

Comment

Another commenter estimated that for the installation of 

: 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.
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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 megawatthours 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. 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 480431 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 
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conclude that the beyond the floor controls are 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 the new source MACT standard in the final rule that is 

about two times more stringent 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 

: With respect to the proposed new gold mine in 

Alaska, the commenters’ estimate of 3,200 lb/yr of mercury 

emissions is inaccurate and a significant overestimate for 

several 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). 
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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 they could not meet 

the new source MACT limit, installation of carbon adsorbers 

would likely reduce the emissions below 45 lb/million tons, 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 
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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 D.C. 

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 
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source MACT floor because the 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 reexamination of the emission controls and 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 mercury emissions from carbon processes at this facility are 

a factor of 10 less than the next “best” performer (Facility N) 

and a factor of 23 less than the average of the top 5 performing 

facilities in the proposed rule. This level of emissions is due 

primarily to the very low levels of mercury in the ore rather 

than having better emission controls than those found at the 

other top performing facilities. Facility M has good controls

for mercury emissions from its carbon processes, but they are 

not as effective as the controls at Facility N. Facility N has 

state-of-the-art controls. The difference is further manifested 

by the differences in the processing train for the carbon group 

in that mercury retorts are not needed or used at Facility M to 
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recover mercury because the mercury levels are so low. 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 two 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 MACT for 

sources that are in the carbon processes with mercury retorts 

and those without mercury retorts, 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 

that 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 
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for new sources (based on the best performing facility). 

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. In light of the small 

emission reduction and the high cost effectiveness of this 

beyond-the-floor option, we decided not to go beyond-the-floor. 

Therefore, for 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 newlyinstalled 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 
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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). 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 or 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.

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 
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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 
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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. Largely due to the reasons 

stated above, we have eliminated the 97 percent control 

efficiency option for new carbon processes in the final rule.

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 
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operation for the particular source. 

Response: After reviewing the information provided in 

public comments on the challenges of retrofitting new controls, 

and the fact that these controls have not yet been demonstrated 

on autoclaves and ore preheaters, 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 
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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 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 
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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 (μg/m3

)). 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. 
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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 for the 12 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 (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 
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authority because that is the case for many other source 

categories of sources 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 on Method 29 data. The 

commenter said that the typical gas streams associated with the 

mining industry have high particulate loadings, high mercury 

concentrations, sulfur dioxide (SO2), and contain particulatebound 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 
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results, will not be comparable, and will provide inconsistent 

reporting of overall mercury emissions.

Response

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 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 

: 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 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. 
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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 mass emissions rate is 

greater than the allowable emission limit, 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).

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, 

however alternative methods (such as 30B and OHM) may prove to 

be more appropriate under certain circumstances. Therefore, we 

are promulgating Method 29 as the main method for compliance in 

this rule. Alternative methods, such as 30B and the Ontario 
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Hydro method (OHM), could be used to demonstrate compliance for 

this source category if approved by the permitting authority. 

We have omitted Method 30A as an option in the final rule, as it 

is not yet in general use. Both Method 30B and the OHM (ASTM 

D6784-02) have been considered acceptable for some source 

categories. However, as described by the commenter, gold 

facilities have unique processes and exhaust gas 

characteristics. Method 29 can be used for any emission point

for any of the affected sources. The alternative methods may 

eventually prove to be more appropriate under certain 

circumstances. Nevertheless, because it is not an isokinetic 

method, Method 30B is applicable to sampling only wellcontrolled PM emissions outlets. The OHM is similar to Method 

29, except that it is more expensive and more complicated, and 

is typically used to measure the individual species of mercury 

rather than just total mercury. 

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 
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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 proposes 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 
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levels of mercury in the ore and different operational measures 

within the control of the facility.

Other commenters supported EPA’s decision to require 

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 
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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 this alternative because Method 30B 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 

are appropriate and necessary for roasters. 

We believe that the mercury concentrations monitoring for 

roasters along with the parametric monitoring of all control 

devices on all units is an acceptable approach to assure 

compliance with the emission standards. Parametric monitoring 

of control devices assures that the control devices are 

operating properly (and reducing emissions) on an ongoing basis. 
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We disagree with the commenter that the proposed monitoring 

requirements render the rule unenforceable. The mercury 

operating limits in both the proposed and final rules are 

enforceable, and any exceedance of these 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 disagree with commenters that CEMS should be required 

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. With 

regard to some of the units without carbon adsorbers, we believe 
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that annual tests coupled with appropriate parametric monitoring 

of the control devices 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 
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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 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 
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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 
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demonstrate compliance for sources controlled with carbon 

adsorbers. Such an approach does not provide for continuous 

monitoring. The parametric monitoring and operating limits 

specified in this final rule provide ongoing assurance that 

control devices are properly operated and maintained between 

emissions tests, and exceedances of the operating limit require 

corrective action. We also reject the comment that all 

operating limits should be based solely on manufacturer 

specifications and/or in consultation with the permitting 

authority. Control device operating parameter values often are 

site-specific and are associated with a level of emissions from 

the source. In order to ensure continuous compliance, certain 

parameter limits generally should 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 
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applicable range of proper operation. A facility may request us 

to consider alternative procedures for setting operating limits 

on a case-by-case basis under 40 CFR 63.8, if desired. 

Comment: Some commenters stated that their established 

parametric monitoring programs are sufficient to confirm that 

mercury emission controls are functioning properly for roasters. 

The commenters also stated that the NMCP permits have required 

parametric limits and that additional CEMS for mercury would 

neither improve the operation of these current controls, nor 

reduce mercury emissions. The commenters concluded that the 

operating parameters monitored on a regular basis are key 

parameters for measuring the efficiency and operation of the 

mercury controls and that operating each of these units within 

the optimum ranges ensures that mercury emissions are being 

effectively controlled. 

Response: As discussed above, we do not believe parametric 

monitoring alone is sufficient for roasters because of the very 

high mercury emission potential, unless the facility has 

adequately demonstrated that the mercury emissions from the 

roasters are consistently very low (e.g., less than 10 pounds 

per million tons). Nevertheless, we have concluded that the 

combined approach of annual stack compliance testing along with 
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the 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. 

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.
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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 

good 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 
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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. 

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 
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by the integrated sample.

As discussed above, the final rule includes continuous 

sampling with PS 12B as a second option for monitoring roasters. 

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, parametric 

monitoring of the mercury scrubber must also be performed. For 

the third 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 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 
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rules for emissions of organic compounds exiting carbon 

adsorbers. That monitoring has proven to be effective to 

prevent or detect breakthrough, and the same principles apply 

here for mercury. 

Comment: Commenters stated that CEMS for gold mining 

operations are not capable of accurately measuring mercury 

emissions and that there are three major challenges with the 

feasibility of mercury CEMS for the gold mining industry: 

mercury CEMS calibration, sample transport, and system 

operability and reliability. The commenters are concerned with 

the unavailability of a means to calibrate the CEMS for roasters 

because existing calibrator designs are simply not capable of 

generating mercury concentrations high enough to provide 

meaningful upscale calibration points that correspond to gold 

mining source characteristics. The commenters noted the 

unavailability of National Institute of Standards and Technology 

(NIST) traceable calibration gases and stated that the current 

calibration standards traceable to NIST do not apply to the full 

range of mercury concentrations that can be present in the 

exhaust gases of roasters. The commenters concluded that the 

lack of a NIST-traceable standard is a fatal flaw that precludes 

using mercury CEMS to monitor roaster emissions. Regarding 
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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.
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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

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

μg/m3. 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 

: Regarding the feasibility of using CEMS to 

monitor mercury emissions from roasters, CEMS have been 

demonstrated for process units similar to roasters (e.g., coalfired power plants), and we believe there is no technical reason 

why they will not work for the roasters. Many of the issues 

with mercury CEMS have been resolved as facilities have gained 

experience with their use. As we discussed in the proposal 

preamble, CEMS manufacturers supply calibration standards for 

the ranges of concentrations seen at roasters.
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concentrations that exceed the concentrations typically seen 

from roasters.

After consideration of public comments, we continue to 

believe CEMS are a valuable tool and a reasonable option for

monitoring mercury concentration and comparing those 

concentrations to the operating limit that is established by 

CEMS measurements made during the compliance test. In addition, 

we are promulgating a second option for continuous monitoring 

using PS 12B, and a third option of twice per month sampling

using PS 12B or Method 30B coupled with parametric monitoring. 

We also point out that the final rule does not require the use 

of CEMS; instead, the final rule includes CEMS as a one of the 

three monitoring option, the results of which wills to ensure 

that emissions from the roasters are not exceed 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. The CEMs can 

also be used to help identify problems with control systems and 

ensure that corrective actions are taken immediately to fix such 

problemsbe used for compliance testing required in this rule. .

We understand the commenter’s concerns regarding the 

transport of samples and converter failures. We have revised 
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the final rule to give facilities 3 years to successfully 

operate controls and monitoring equipment to be able to comply 

with the MACT standards. 

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 

exceedenceexceedance in mercury concentration should be verified 

first with a compliance test before halting the roaster 

production.
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Response

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 limit. 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.

: 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 

IV.D. of this preamble, we have established in the final rule a 

compliance date that is 3 years after the effective date of the 

final rule for existing sources, partly to allow sources time to 

ensure they can successfully comply with the monitoring 

requirements, but mainly to allow time to install new mercury 

emission controls that we believe will be necessary to meet the 

emission standards in the final rule.

Comment: One commenter requested that EPA reduce the 

weekly Method 12B monitoring frequency to quarterly or at most 
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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, the final rule requires monitoring mercury 

concentration twice per month (at least 11 days apart). 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 
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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 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 
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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 three test runs. 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 
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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. 

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° to 134°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 
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relevant control performance parameter, their facility maintains 

the inlet gas temperature below 134°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 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. The facility must
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monitor the temperature hourly, and any exceedance of the upper 

limit for temperature would trigger corrective action. 

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. The final rule requires hourly monitoring 

and that corrective action is triggered if the flow rate or line 
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pressure falls below the established parameters.

Regarding the acceptability of parameter values that were 

approved by permitting authorities prior to this final rule, 

such values must be established as specified in the final rule 

and are not presumed in advance to be acceptable.

5. Exceeding the Operating Limits for Roasters

Comment

One commenter recommended that the corrective action 

response time be extended minimally to 48 hours after daily 

: 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. 
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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 
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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 
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learn more about appropriate roaster monitoring. We believe the 

requirements of this final rule provide assurance that timely 

corrective actions are taken when a monitoring parameter is 

exceeded, and we have included requirements for testing for 

mercury concentrations to determine if the corrective actions 

were successful or if a deviation has occurred. The final rule 

includes parametric monitoring of the mercury scrubbers applied 

to roasters to control mercury. If a parameter is outside of 

the established range or limit, corrective actions are 

triggered. If corrective actions do not result in the parameter 

reading being corrected and verified within 48 hours, a mercury 

concentration measurement (using method 30B, 12B, 29, or OHM) 

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 the 
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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. 

Comment

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 

: 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.
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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 or Method 12B or 30B) 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 
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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.

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 §63.11647(a)(5) (i.e., facilities 
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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 or Method 30B or Method 29 

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 3 in the final rule, 

where the value for “Ctrap” in Equation 3 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 
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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.

Comment

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 

: 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.
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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: 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 additional scrubbers that are used to remove PM and SO2 prior 

to the mercury scrubber. We are also clarifying in the final 

rule that when the primary mercury emission control device is a 

carbon adsorber, which is the last stage of the exhaust gas 
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cleaning treatment train, it is necessary to monitor the carbon 

adsorber to ensure it is operating properly and controlling 

mercury emissions, and the rule does not require that scrubbers 

in the gas treatment train (typically used for control of PM

and/or SO2) prior to the carbon adsorber be monitored under this 

rule for mercury emissions. However, if there is no carbon 

adsorber or mercury scrubber, and the 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) for pressure drop and flow rate 

with operating limits that either are 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 scrubbers on ore preheaters and quenching if there is no 

carbon adsorber or mercury scrubber in the exhaust gas treatment 

train.

We are clarifying in the final rule that condensers, such 

as those found at roasters and 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 
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of +/- 30 percent based on a certain 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 the option in the final rule,

as suggested by the commenter.

6. Carbon Adsorber Temperature Monitoring

Comment: Several commenters stated their concern with the 

proposed requirement of monitoring gas stream temperature at the 

inlet to the carbon adsorber and maintaining the inlet 

temperature below the maximum temperature established during the 

compliance test. They noted that the primary purpose for 

monitoring the inlet gas stream temperature of carbon adsorbers 

is to prevent spontaneous combustion of the sulfidized carbon in 

the adsorber, not to detect excursions in mercury emissions. 

The commenters also stated that some carbon adsorption systems 

heat the gas stream prior to the carbon adsorber to prevent 

moisture buildup and/or subsequent condensation in the carbon. 
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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 
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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 
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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 
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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 Multiple Units Ducted to One Stack

Comment

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 

: 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. 
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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, as well as stack testing for 

compliance will be based on both roasters operating. 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 and the stack testing for 

compliance must 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.

8. 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 
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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 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 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 
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of variations in ore mercury content.

V. 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 2,635636 lb/yr. 

We estimate the final MACT standard will reduce mercury 

emissions from gold mine ore processing and production by 

1,496461 lb/yr from the baseline emissions levels of 2,635636

lb/yr down to a level of 1,139176 lb/yr post-MACT. The annual 

emissions expected after MACT (1,139176 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 $8.1 million per year. The 

capital costs for monitoring, reporting, and recordkeeping are 
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estimated as $1.0.5 to $1.30 million with a total annualized 

cost of $0.8 7 to $1.5 million per year, depending on the 

monitoring option that is chosen. The overall cost 

effectiveness is estimated to be about $6,400300 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 12,700600 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. Nonhazardous solid waste (spent carbon containing mercury that must 

be regenerated or disposed of) would increase by about 7 tons 

per year.

VI. Startup, Shutdown, and Malfunctions

The United States Court of Appeals for the District of 

Columbia Circuit vacated portions of two provisions in EPA’s CAA 

Section 112 regulations governing the emissions of HAP during 

periods of startup, shutdown, and malfunction (SSM). Sierra 

Club v. EPA, 551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 130 

S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the 

SSM exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 
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63.6(h)(1), that are part of a regulation, commonly referred to 

as the “General Provisions Rule,” that EPA promulgated under 

section 112 of the CAA. When incorporated into CAA Section 

112(d) regulations for specific source categories, these two 

provisions exempt sources from the requirement to comply with 

the otherwise applicable CAA section 112(d) emission standard 

during periods of SSM.

Consistent with Sierra Club v. EPA, EPA has established 

standards in this rule that apply at all times. In establishing 

the standards in this rule, EPA has taken into account startup 

and shutdown periods and, for the reasons explained below, has 

not established different standards for those periods. We have 

no reason to believe that emissions are different during startup 

or shutdown. The mercury emissions from significant emissions 

points are, or will be, controlled by condensers, carbon bed 

filters, or mercury scrubbers. The carbon beds, which are 

applied to most types of process units to control mercury 

emissions, will capture mercury as well, or better, during 

periods of startup and shutdown as compared to normal 

operations. Condensers also capture mercury as well, or better, 

during periods of startup and shutdown as compared to normal 

operations. Mercury scrubbers are applied only to roasters, and 
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roasters operate continuously for most of the year. Roasters 

are normally shutdown purposely only about once per year 

(typically for a few weeks) for maintenance and repair. The 

facilities that have roasters ensure that the control devices 

(including the mercury scrubbers) are fully operational before 

the roasters are started. Also, the controls stay operational 

throughout the shutdown period. Therefore, no increases in

emissions are expected during the startup and shutdown periods. 

Moreover, the MACT limit is based on pounds of mercury emissions 

per rate of input or production over a 12-month rolling average 

(e.g., pounds of mercury per million tons of input ore). 

Therefore, no change in the emissions standards are needed for 

periods of startup and shutdown. 

Periods of startup, normal operations, and shutdown are all 

predictable and routine aspects of a source’s operations. 

However, by contrast, malfunction is defined as a “sudden, 

infrequent, and not reasonably preventable failure of air 

pollution control and monitoring equipment, process equipment or 

a process to operate in a normal or usual manner” (40 CFR 63.2). 

EPA has determined that malfunctions should not be viewed as a 

distinct operating mode and, therefore, any emissions that occur 

at such times do not need to be factored into development of CAA 
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section 112(d) standards, which, once promulgated, apply at all 

times. In Mossville Environmental Action Now v. EPA, 370 F.3d 

1232, 1242 (D.C. Cir. 2004), the court upheld as reasonable 

standards that had factored in variability of emissions under 

all operating conditions. However, nothing in section 112(d) or

in caselaw requires that EPA anticipate and account for the 

innumerable types of potential malfunction events in setting 

emission standards. See, Weyerhaeuser v Costle

Further, it is reasonable to interpret section 112(d) as 

not requiring EPA to account for malfunctions in setting 

emissions standards. For example, we note that Section 112 uses 

the concept of “best performing” sources in defining MACT. 

Applying the concept of “best performing” to a source that is 

, 590 F.2d 1011, 

1058 (D.C. Cir. 1978) (“ In the nature of things, no general 

limit, individual permit, or even any upset provision can 

anticipate all upset situations. After a certain point, the 

transgression of regulatory limits caused by ‘uncontrollable 

acts of third parties,’ such as strikes, sabotage, operator 

intoxication or insanity, and a variety of other eventualities, 

must be a matter for the administrative exercise of case-by-case 

enforcement discretion, not for specification in advance by 

regulation.”) 
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malfunctioning presents significant difficulties. The goal of 

best performing sources is to operate in such a way as to avoid 

malfunctions of their units. 

Moreover, even if malfunctions were considered a distinct 

operating mode, we believe it would be impracticable to take 

malfunctions into account in setting CAA section 112(d) 

standards for the gold mine ore processing and production source 

category. As noted above, by definition, malfunctions are 

sudden and unexpected events and it would be difficult to set a 

standard that takes into account the myriad different types of 

malfunctions that can occur across all sources in the category. 

Moreover, malfunctions can vary in frequency, degree, and 

duration, further complicating standard setting. 

We believe it unlikely that malfunctions would result in 

violations of the standards in this rule. The primary pollution 

control devices used in this industry to control mercury 

emissions (condensers, carbon bed filters and mercury scrubbers) 

are not expected to be significantly affected by SSM events. 

Moreover, the standards in this rule are expressed in terms of 

long-term averages (e.g., pounds of mercury emitted per rate of 

production over a 12-month period). We believe that 

malfunctions (which are expected to occur quite infrequently 
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over that period) are not likely to result in an exceedance of 

the standards.

In the unlikely event that a source fails to comply with 

the applicable CAA section 112(d) standards as a result of a 

malfunction event, EPA would determine an appropriate response 

based on, among other things, the good faith efforts of the 

source to minimize emissions during malfunction periods, 

including preventative and corrective actions, as well as root 

cause analyses to ascertain and rectify excess emissions. EPA 

would also consider whether the source's failure to comply with 

the CAA section 112(d) standard was, in fact, “sudden, 

infrequent, not reasonably preventable” and was not instead 

“caused in part by poor maintenance or careless operation.” 40 

C.F.R. § 63.2 (definition of malfunction).

Finally, EPA recognizes that even equipment that is 

properly designed and maintained can sometimes fail and that 

such failure can sometimes cause an exceedance of the relevant 

emission standard. (See, e.g., State Implementation Plans: 

Policy Regarding Excessive Emissions During Malfunctions, 

Startup, and Shutdown (Sept. 20, 1999); Policy on Excess 

Emissions During Startup, Shutdown, Maintenance, and 

Malfunctions (Feb. 15, 1983)). EPA is therefore adding to the 
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final rule an affirmative defense to civil penalties for 

exceedances of emission limits that are caused by malfunctions. 

See 40 CFR 63.11651 (defining “affirmative defense” to mean, in 

the context of an enforcement proceeding, a response or defense 

put forward by a defendant, regarding which the defendant has 

the burden of proof, and the merits of which are independently 

and objectively evaluated in a judicial or administrative 

proceeding.). We also have added other regulatory provisions to 

specify the elements that are necessary to establish this 

affirmative defense; the source must prove by a preponderance of 

the evidence that it has met all of the elements set forth in 

63.11648. (See 40 C.F.R. 22.24). The criteria ensure that the 

affirmative defense is available only where the event that 

causes an exceedance of the emission limit meets the narrow 

definition of malfunction in 40 C.F.R. 63.2 (sudden, infrequent, 

not reasonable preventable and not caused by poor maintenance 

and/or careless operation). For example, to successfully assert 

the affirmative defense, the source must prove by a 

preponderance of the evidence that excess emissions “[w]ere 

caused by a sudden, short, infrequent, and unavoidable failure 

of air pollution control and monitoring equipment, process 

equipment, or a process to operate in a normal or usual 
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manner....” The criteria also are designed to ensure that steps 

are taken to correct the malfunction, to minimize emissions in 

accordance with section 63.11646(b) and to prevent future 

malfunctions. For example, the source must prove by a 

preponderance of the evidence that “[r]epairs were made as 

expeditiously as possible when the applicable emission 

limitations were being exceeded...” and that “[a]ll possible steps 

were taken to minimize the impact of the excess emissions on 

ambient air quality, the environment and human health....” In any 

judicial or administrative proceeding, the Administrator may 

challenge the assertion of the affirmative defense and, if the 

respondent has not met its burden of proving all of the 

requirements in the affirmative defense, appropriate penalties 

may be assessed in accordance with Section 113 of the Clean Air 

Act (see also 40 C.F.R. Part 22.77).

VII. Statutory and Executive Order Reviews

A. 

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 

Executive Order 12866: Regulatory Planning and Review
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made in response to OMB recommendations have been documented in 

the docket for this action. 

B. 

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 

Paperwork Reduction Act

et seq

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.

. The Information 

Collection Request (ICR) document prepared by EPA has been 

assigned EPA ICR No. 2383.01.

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 
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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 $1.340 million, 

operation and maintenance costs are estimated as $6752,000 per 

year, and total annualized cost (including capital recovery) is 

estimated as $417,930360,210 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 
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information requirements contained in this final rule.

C. 

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. 

Regulatory Flexibility Act

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 
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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. 
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D. 

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 $9.21 million/yr. Thus, this final rule 

is not subject to the requirements of sections 202 and 205 of 

the Unfunded Mandates Reform Act (UMRA).

Unfunded Mandates Reform Act

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. 

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 

Executive Order 13132: Federalism
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state and local governments. Thus, Executive Order 13132 does 

not apply to this action. 

In the spirit of Executive Order 13132, and consistent with 

EPA policy to promote communications between EPA and State and 

local governments, EPA specifically solicited comment on this 

proposed action from State and local officials.

F. 

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 

Executive Order 13175 does not apply to this action, EPA 

requested comment from tribal officials in developing this 

action. However, 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. 

Executive Order 13175: Consultation and Coordination with 

Indian Tribal Governments

G. Executive Order 13045: Protection of Children from 

Environmental Health and Safety Risks
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EPA interprets Executive Order 13045 (62 F.R. 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. 

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 

12,700600 megawatt-hours per year.

Executive Order 13211: Actions Concerning Regulations That 

Significantly Affect Energy Supply, Distribution, or Use

I. 

Section 12(d) of the National Technology Transfer and 

Advancement Act of 1995 (“NTTAA”), Public Law No. 104-113 (15 

U.S.C. 272 note), directs EPA to use voluntary consensus 

National Technology Transfer and Advancement Act
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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. This 

performance test method is available from ASTM International. 

See http://www.astm.org/.
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EPA has also decided to use EPA Methods 1, 1A, 2, 2A, 2C, 

2D, 2F, 2G, 3, 3A, 3B, 4, 29, 30B, Method 7471A, “Mercury in 

Solid or Semisolid Waste (Manual Cold-Vapor Technique),” 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 

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 (59 FR 7629, February 16, 1994) 

Executive Order 12898: Federal Actions to Address 

Environmental Justice in Minority Populations and Low-Income 

Populations
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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. 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. 

The Congressional Review Act, 5 U.S.C. 801 et seq., as 

added by the Small Business Regulatory Enforcement Fairness Act 

Congressional Review Act
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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 [INSERT DATE OF PUBLICATION IN THE FEDERAL 

REGISTER].
National Emission Standards for Hazardous Air Pollutants: Gold 

Mine Ore Processing and Production Area Source Category; and 

Addition to Source Category List for Standards

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List of Subjects in 40 CFR Parts 9 and 63

Environmental protection, Air pollution control, Hazardous 

substances, Incorporations by reference, Reporting and 

recordkeeping requirements.

___________

Dated: 

____________________________

Lisa P. Jackson,

Administrator.
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For the reasons stated in the preamble, title 40, chapter I, of 

the Code of Federal Regulations is amended as follows:

PART 9—[AMENDED]

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

Subpart A—[Amended]

., 

6901–6992k, 7401–7671q, 7542, 9601–9657, 11023, 11048.

* * * * *

2. The table in §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:

§9.1 OMB Approvals under the Paperwork Reduction Act.

* * * * *

40 CFR citation OMB control No.

* * * * *
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National Emission Standards for Hazardous Air Pollutants for 

Source Categories3

* * * * *

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]

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

follows:

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

Subpart A—[Amended]

.

4. Section 63.14 is amended by revising paragraphs (b)(35)

and (i)(1) and by adding paragraph (k)(1)(v) to read as follows:

§63.14 Incorporation by reference.

* * * * *

(b) * * *

(35) 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), IBR 

approved for §63.11646(a)(1)(v) and table 5 to subpart DDDDD of 

this part.
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* * * * *

(i) * * *

(1) ANSI/ASME PTC 19.10–1981, “Flue and Exhaust Gas 

Analyses [Part 10, Instruments and Apparatus],” IBR approved for 

§§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) Method 7471A, “Mercury in Solid or Semisolid Waste 

(Manual Cold-Vapor Technique),” IBR approved for 

§63.11647(f)(2).

* * * * *

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 
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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 Affirmative Defense for Exceedance of Emission Limits

During Malfunction.

63.11649 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

§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 

§63.11651, that is an area source.

?
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(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 

§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.

§63.11641 What are my compliance dates?
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(a) If you own or operate an existing affected source, you 

must comply with the applicable provisions of this subpart no 

later than [INSERT DATE 3 YEARS AFTER PUBLICATION OF THIS FINAL 

RULE IN THE FEDERAL REGISTER].

(b) If you own or operate a new affected source, and the 

initial startup of your affected source is on or before [INSERT 

DATE OF PUBLICATION OF THIS FINAL RULE IN THE FEDERAL REGISTER], 

you must comply with the provisions of this subpart no later 

than [INSERT DATE OF PUBLICATION OF THIS FINAL RULE IN THE 

FEDERAL REGISTER].

(c) If you own or operate a new affected source, and the 

initial startup of your affected source is after [INSERT DATE OF 

PUBLICATION OF THIS FINAL RULE IN THE FEDERAL REGISTER], you 

must comply with the provisions of this subpart upon startup of 

your affected source.

Standards and Compliance Requirements

§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.
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(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. 

§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

?
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days of the compliance date for all process units at new and 

existing affected sources according to the requirements in 

paragraphs (a)(1) through (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 A1), or Method 2G (40 CFR part 60, appendix A-2) to determine the 

volumetric flow rate of the stack gas.

(iii) Method 3, 3A, or 3B (40 CFR part 60, appendix A-2) 

to determine the dry molecular weight of the stack gas. You may 

use ANSI/ASME PTC 19.10-1981, “Flue and Exhaust Gas Analyses” 

(incorporated by reference-see §63.14) as an alternative to EPA 

Method 3B.
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(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 

D6784–02; “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 §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 Ontario Hydro Method, determine 

sample time and volume according to the testing criteria set 
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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 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 mass emissions rate is 

greater than the allowable 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) TestsPerformance 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 
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the permit authority the process throughput for each test run. 

For sources with multiple emission units (e.g., two roasters) 

ducted to a common control device and stack, compliance testing 

must be performed with all affected emissions units in operation

if possible. If it is not possible to test all sources ducted 

to a common control device simultaneously, the sources can be 

tested separately. In such cases, any source that is not tested 

initially must be tested as soon as is practicable.

(4) Calculate the mercury emission rate, based on the 

average of 3 test run values, for each process unit using 

Equation (1) of this section:

E = Cs * Qs * K (Eq. 1)

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 report to the permit authority 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 
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rate in lb/hr for each process unit by the number of hours each 

process unit operated during those full calendar months prior to 

the initial compliance test. After the initial compliance test, 

for subsequent compliance tests, determine the mercury mass

emissions for the 12 month period 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 (4) of this section, and the tests were representative 

of current operating processes and conditions. 

(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-

month period preceding the performance test by multiplying the 

emission rate in lb/hr for each process unit by the number of 

hours each process unit 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,
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daily and monthly totals in tons of ore according to paragraphs 

(a)(8)(i) and (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 and before the carbon-in-leach tanks.

(ii) Measure the weight or the density and volumetric flow 

rate of the ore slurry as it is fed to or as it exits the 

autoclave(s).

(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. 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, record, 

and report to the permit authority 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. 
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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 noncarbon concentrate processes on a daily and monthly basis and 

report the monthly values to the permit authority.

(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 (iv) of this section to 

determine initial compliance with the emission standards in 

§63.11645. After this initial compliance test period, determine 

annual compliance using the procedures in paragraph (a)(13) of 

this section for existing sources.
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(i) For ore pretreatment processes, divide the sum of 

mercury mass emissions 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 these process 

units during those same full months following the compliance 

date. 

(ii) For carbon processes with mercury retorts, divide the 

sum of mercury mass emissions 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 

processed in these process units during those same full months 

following the compliance date.

(iii) For carbon processes without mercury retorts, divide 

the sum of mercury mass emissions 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 

processed in these process units during those same full months 

following the compliance date.

(iv) For non-carbon concentrate processes, divide the sum 

of mercury mass emissions from mercury retorts and melt furnaces 
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during the initial number of full months between the compliance 

date and the initial compliance tests by the total amount of 

concentrate processed in these process units during those same 

full months following the compliance date.

(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 §63.11645. 

(i) For ore pretreatment processes, divide the sum of 

mercury mass emissions 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 that

12-month period.

(ii) For carbon processes with mercury retorts, divide the 

sum of mercury mass emissions 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 processed in these process units in that 12-month 

period.

(iii) For carbon processes without mercury retorts, divide 

the sum of mercury mass emissions from all carbon kilns, preg 
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tanks, electrowinning, and melt furnaces in the 12-month period 

preceding a compliance test by the total amount of concentrate 

processed in these process units in that 12-month period.

(iv) For non-carbon concentrate processes, divide the sum 

of mercury mass emissions from mercury retorts and melt furnaces 

in the 12-month period preceding a compliance test by the total 

amount of concentrate processed in these process units in that

12-month period.

(b) At all times, youyou 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.

(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), (2), or (3) of 

this section and establish operating limits for mercury 

§63.11647 What are my monitoring requirements?
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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 or EPA Method 30B 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 30 days using a 

shorter sampling duration.

(ii) If the any mercury concentration measurement from the 

twice per month sampling with method 12B or 30B is higher than 

the operating limit, the exceedance must be reported to the 

permit authority as a deviation and corrective actions must be 
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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 method 

12B or 30B) 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 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 (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 monitoring requirements in 
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§63.8, .except that 63.8(c)(1)(i) and (iii) no longer apply. 

Moreover, 63.8(d)(3) applies except the last sentence, which 

refers to an SSM plan. SSM plans are no longer required. 

(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) 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 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 results may also be used to 

establish a new operating limit for mercury concentration (in 
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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 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.

(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 30 days using a shorter sampling 
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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 method 12B 

or 30B 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 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 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), (2), or (3) of this section

concurrently while you are conducting your annual compliance 

performance stack test according to the procedures in 
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§63.11646(a).

OLR = Ctest * (EL/CT) (Eq 2)

where

OLR = mercury concentration operating limit for the 

roaster (in micrograms per cubic meter);

Ctest = average mercury concentration measured by the 

monitoring procedures (PS 12A or PS 12B or 30B) 

during the annual 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), (2), or (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 §63.11646. The results of each of 

the tests must be less than 10 pounds of mercury per million 
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tons of ore. The testing must be performed according to the 

procedures in §63.11646(a)(1) through (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 the lowest value 
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during any run of the initial compliance test, and your maximum 

scrubber inlet temperature limit is the highest measured during 

any run of the initial 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 procedures in paragraph (c)(1) or (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. 

Alternatively, the mercuric ion concentration and chloride ion 
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concentration ranges for each calomel-based mercury control 

system may be 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 calomelbased mercury control system must be based on the manufacturer’s 

specifications. Alternatively, the oxidation reduction 

potential and pH range for each calomel-based mercury control 

system may be 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 
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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 method 12B or 30B) 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 

§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. The owner or operator must conduct a compliance test 
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pursuant to §63.11646(a) within 40 days to determine if the 

roaster operations are in compliance with the MACT emission 

standard. 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),(2), or (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

(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 
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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 as calculated from Equation (3) of this section.

OLC = Ctrap * (EL/CT) (Eq 3)

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 

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.
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(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 EPA 

Method 7471A (incorporated by reference - see §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 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 autoclave, carbon kiln, melt 

furnace, and mercury retort equipped with a carbon adsorber. 
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Establish a maximum value for the inlet temperature either 

during the annual performance test as required in §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°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 

follow the requirements for outlet concentration measurement in 

paragraph (f)(1) of this section. If the concentration is below 

90 percent of the operating limit, you may set a new temperature 

operating limit 10°F above the previous operating limit. If the 

concentration is above 90 percent of the operating limit, you 

must take corrective action to reduce the temperature back below 

the temperature operating limit and again measure the outlet 

concentration according to paragraph (f)(1) of this section. If 

the concentration is still above 90 percent of the operating 

limit, then you must change the carbon in the bed within 30 days

and report the deviation to your permitting authority. 

(h) For each wet scrubber at each new and existing 

affected source not followed by a mercury control system, you 
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must monitor the water flow rate (or line pressure) and pressure 

drop. Establish a minimum value as the operating limit either 

during the performance test required in §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 

average value during any test run or no lower than 10 percent of 

the average value measured during the test. For wet scrubbers 

on an autoclave, establish the 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 within 40 days to determine if the 

source is in compliance with the MACT limit. 

(i) You may conduct additional compliance tests according 

to the procedures in §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 
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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.

§63.11648

In response to an action to enforce the standards set forth 

in paragraph §63.11645 you may assert an affirmative defense to 

a claim for civil penalties for exceedances of such standards 

that are caused by malfunction, as defined at 40 CFR 63.2. 

Appropriate penalties may be assessed, however, if you fail to 

meet your burden of proving all of the requirements in the 

affirmative defense. The affirmative defense shall not be 

available for claims for injunctive relief.

 Affirmative Defense for Exceedance of Emission Limit 

During Malfunction. 

(a) To establish the affirmative defense in any action to 

enforce such a limit, you must timely meet the notification 

requirements in paragraph (b) of this section, and must prove by 

a preponderance of evidence that:

 (1) The excess emissions: 

(i) Were caused by a sudden, short, infrequent, and 

unavoidable failure of air pollution control and monitoring 
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equipment, process equipment, or a process to operate in a 

normal or usual manner, and 

(ii) Could not have been prevented through careful 

planning, proper design or better operation and maintenance 

practices; and

 (iii) Did not stem from any activity or event that could 

have been foreseen and avoided, or planned for; and

(iv) Were not part of a recurring pattern indicative of 

inadequate design, operation, or maintenance; and

 (2) Repairs were made as expeditiously as possible when the 

applicable emission limitations were being exceeded. Off-shift 

and overtime labor were used, to the extent practicable to make 

these repairs; and

 (3) The frequency, amount and duration of the excess 

emissions (including any bypass) were minimized to the maximum 

extent practicable during periods of such emissions; and

 (4) If the excess emissions resulted from a bypass of 

control equipment or a process, then the bypass was unavoidable 

to prevent loss of life, severe personal injury, or severe 

property damage; and

 (5) All possible steps were taken to minimize the impact of 

the excess emissions on ambient air quality, the environment and 

human health; and
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 (6) All emissions monitoring and control systems were kept 

in operation if at all possible; and

 (7) All of the actions in response to the excess emissions 

were documented by properly signed, contemporaneous operating 

logs; and

 (8) At all times, the facility was operated in a manner 

consistent with good practices for minimizing emissions; and

(9) A written root cause analysis has been prepared to 

determine, correct, and eliminate the primary causes of the 

malfunction and the excess emissions resulting from the 

malfunction event at issue. The analysis shall also specify, 

using best monitoring methods and engineering judgment, the 

amount of excess emissions that were the result of the 

malfunction. 

(b) Notification. The owner or operator of the facility 

experiencing an exceedance of its emission limit(s) during a 

malfunction shall notify the Administrator by telephone or 

facsimile (FAX) transmission as soon as possible, but no later 

than two business days after the initial occurrence of the 

malfunction, if it wishes to avail itself of an affirmative 

defense to civil penalties for that malfunction. The owner or 

operator seeking to assert an affirmative defense shall also 

submit a written report to the Administrator within 30 days of 
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the initial occurrence of the exceedance of the standard in 

§63.11645 to demonstrate, with all necessary supporting

documentation, that it has met the requirements set forth in 

paragraph (a) of this section.

§63.11649 What are my notification, reporting, and 

recordkeeping requirements

(a) You must submit the Initial Notification required by 

§63.9(b)(2) no later than 120 calendar days after the date of 

publication of the final rule in the 

?

Federal Register

(b) You must submit an initial Notification of Compliance 

Status as required by §63.9(h).

or within 

120 days after the source becomes subject to the standard. The 

Initial Notification must include the information specified in 

§63.9(b)(2)(i) through (b)(2)(iv). 

(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 §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 
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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 (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 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 

include records of the occurrence and duration of each 

malfunction of operation (i.e., process equipment) or the air 

pollution control and monitoring equipment.

The report must also include a description of actions taken by 
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an owner or operator during aperiods of malfunction of an 

affected source to minimize emissions in accordance with 

§63.11646(c), including corrective actions taken to correct a 

malfunction.

restore malfunctioning process and air pollution control 

and monitoring equipment to its normal or usual manner of 

operation. 

(e) You must keep the records specified in paragraphs 

(e)(1) through (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 §63.10(b)(2)(xiv), you must keep a copy 

of each 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 §§63.11646 and 63.11647, and the information identified in 

paragraphs (c)(2)(i) through (vi) of this section for each 

corrective action required by §63.11647.

(i) The date, place, and time of the monitoring event 

requiring corrective action;
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(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 §63.11646(a)(5) and records of the 

monthly quantity of ore and concentrate processed as required by 

§63.11646(a)(10).

(f) Your records must be in a form suitable and readily 

available for expeditious review, according to §63.10(b)(1). As 

specified in §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 §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 
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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

§63.11650 What General Provisions apply to this subpart

Table 1 to this subpart shows which parts of the General 

Provisions in §§63.1 through 63.16 apply to you.

?

§63.11651 What definitions apply to this subpart

Terms used in this subpart are defined in the Clean Air 

Act, in §63.2, and in this section as follows:

?

Affirmative defense means, in the context of an enforcement 

proceeding, a response or defense put forward by a defendant, 

regarding which the defendant has the burden of proof, and the 

merits of which are independently and objectively evaluated in a 

judicial or administrative proceeding.

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 
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approximately 350° to 430°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 used as a subsititute 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 
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processing and production facilities that use activated carbon, 

or resins that can used as a subsititute 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

(1) Fails to meet any requirement or obligation 

established by this subpart, including but not limited to any 

emissions limitation or work practice standard;

means any instance where an affected source 

subject to this subpart, or an owner or operator of such a 

source:

(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 
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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. An operation that processes or 

produces less than 50 pounds of concentrate per year is 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 or processing and 

production source category. 
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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 process, or other processes 

for facilities without mercury retorts. 

Mercury retort means a vessel that is operated under a 

partial vacuum at approximately 1100° to 1300oF 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 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.
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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. 

63.11652 Who implements and enforces this subpart

(a) This subpart can be implemented and enforced by the 

?
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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 §63.11640, the compliance date requirements in

§63.11641, and the applicable standards in §63.11645.

(2) Approval of an alternative nonopacity emissions 

standard under §63.6(g). 

(3) Approval of a major change to a test method under 

§63.7(e)(2)(ii) and (f). A “major change to test method” is 
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defined in §63.90(a).

(4) Approval of a major change to monitoring under 

§63.8(f). A “major change to monitoring” is defined in 

§63.90(a).

(5) Approval of a waiver of recordkeeping or reporting 

requirements under §63.10(f), or another major change to 

recordkeeping/reporting. A “major change to 

recordkeeping/reporting” is defined in §63.90(a).

§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 §63.11650, you must comply with the applicable 

General Provisions requirements according to the following 

table: 

Citation Subject

Applies to 

subpart 

EEEEEEE Explanation

§63.1(a)(1), 

(a)(2), (a)(3), 

(a)(4), (a)(6), 

(a)(10)–(a)(12), 

(b)(1), (b)(3), 

(c)(1), (c)(2), 

(c)(5), (e)

Applicability Yes

§63.1(a)(5), 

(a)(7)–(a)(9), 

(b)(2), (c)(3), 

(c)(4), (d)

Reserved No

§63.2 Definitions Yes

§63.3 Units and Yes
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Formatted: Portuguese (Brazil)

Formatted: HTML Preformatted

Abbreviations

§63.4 Prohibited 

Activities and 

Circumvention

Yes

§63.5 Preconstruction 

Review and 

Notification 

Requirements

Yes

§63.6(a), (b)(1)–

(b)(5), (b)(7), 

(c)(1), (c)(2), 

(c)(5), 

(e)(1)(iii),(f)(2

), (f)(3), (g), 

(i), (j)

Compliance with 

Standards and 

Maintenance 

Requirements

Yes

§63.6(e)(1)(i)

and (ii), (e)(3), 

and(f)(1)

Startup, Shutdown 

and Malfunction 

Requirements 

(SSM)General Duty 

to minimize 

emissions

No. 

See 

63.11646(b)

for general 

duty 

requirement

Subpart 

EEEEEEE

standards 

apply at all 

times.See 

63.11646(b)

63.6(e)(1)(ii) Requirement to 

correct 

malfunctions as 

soon as possible.

No

63.6(e)(3) SSM Plan 

requirements

No

63.6(f)(1) SSM exemption No Malfunctions 

are no longer 

exempt. All 

excursions are 

violations and 

there is no 

need to 

specify 

corrections.

§63.6(h)(1), 

(h)(2), 

(h)(4),(h)(5)(i), 

(ii), (iii) and 

(v), (h)(6)–

Compliance with 

Opacity and 

Visible Emission 

Limits

No Subpart 

EEEEEEE does 

not contain 

opacity or 

visible 
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Formatted: Spanish (Spain-Traditional Sort)

(h)(9) emission 

limits.

§63.6(b)(6), 

(c)(3), (c)(4), 

(d), (e)(2), 

(e)(3)(ii), 

(h)(3), 

(h)(5)(iv)

Reserved No

§63.7, except 

(e)(1) 

Applicability and 

Performance Test 

Dates

Yes

§ 63.7(e)(1) Performance 

Testing

Requirements 

Related to SSM

NoSee 

63.11646

See 

63.11646(a)(3)

§63.8(a)(1), 

(b)(1), (f)(1)-

(5), (g)

Monitoring 

Requirements

Yes

§63.8(a)(2), 

(a)(4), (b)(2)-

(3), (c)(ii), 

(d)(i), (e), 

(f)(6), (g)

Continuous 

Monitoring Systems

(CMS)

Yes Except cross 

references to 

SSM 

requirements 

in §63.6(e)(1) 

and (3) do not 

apply

63.8(c)(1)(i) General duty to 

minimize emissions 

and CMS operation

No See 

63.11646(b)

63.8(c)(1)(iii) Requirement to 

develop SSM Plan 

for CMS

No

63.8(d)(3) Written procedures 

for CMS

Yes, except 

for last 

sentence.

Last sentence 

refers to an 

SSM Plan which 

is no longer 

required.

§63.8(a)(3) [Reserved] No

§63.9(a), (b)(1), 

(b)(2)(i)-(v), 

(b)(4), (b)(5), 

Notification 

Requirements

Yes
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(c), (d)(1), 

(d)(2), (e), (g), 

(h)(1)–(h)(3), 

(h)(5), (h)(6), 

(i), (j)

§63.9(f) No

§63.9(b)(3), 

(h)(4)

Reserved No

§63.10(a), 

(b)(1), 

(b)(2)(vi)–(xiv), 

(b)(3), (c)(1)-

(14), (d)(1)-(4), 

(e), (f)

Recordkeeping and 

Reporting 

Requirements

Yes

63.10(b)(2)(i) Recordkeeping of 

occurrence and 

duration of 

startups and 

shutdowns

No

63.10(b)(2)(ii) Recordkeeping of 

malfunctions

No. 

See 63.11649

for 

recordkeeping 

of (1) 

occurrence 

and duration 

and (2) 

actions taken 

during 

malfunction

See 63.11648

63.10(b)(2)(iii) Maintenance 

records

Yes.

63.10(b)(2)(iv) Actions taken to 

minimize emissions 

during SSM

No.

63.10(b)(2)(v) Actions taken to 

minimize emissions 

during SSM

No.

63.10(b)(2)(vi) Recordkeeping for 

CMS malfunctions

Yes.
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63.10(b)(2)(vii)-

(ix)

Other CMS 

requirements

Yes.

§ 63.10(b)(2)(i)-

(v), (d)(5)

Recordkeeping/Repo

rting Associated 

with SSM

No

§63.10(c)(2)–

(c)(4), (c)(9)

Reserved No

63.10(c)(7) Additional 

recordkeeping 

requirements for 

CMS – identifying 

exceedances and 

excess emissions

Yes

63.10(c)(8) Additional 

recordkeeping 

requirements for 

CMS – identifying 

exceedances and 

excess emissions

Yes

63.10(c)(10) Recording nature 

and cause of 

malfunctions

No. See 

63.11649 for 

malfunctions 

recordkeeping 

requirements. 

63.10(d)(5) SSM reports No. See 

63.11649 for 

malfunction 

reporting 

requirements. 

See 63.11649

§63.11 Control Device 

Requirements

No

§63.12 State Authority 

and Delegations

Yes

§§63.13–63.16 Addresses, 

Incorporations by 

Reference, 

Availability of 

Information, 

Performance Track 

Provisions

Yes