From: "Barbanell, Melissa (Salt Lake City)" <mbarbanell@barrick.com> 

 

To: Steve Fruh/RTP/USEPA/US@EPA, Chuck French/RTP/USEPA/US@EPA 

 

Date: 10/28/2010 07:40 PM 

 

Subject: additional comments 

 

Dear Steve & Chuck,

I am attaching three sets of comments from the Nevada Mining Association. The 

first set of comments addresses a partial exemption under Title V. The next set 

of comments addresses the issues that were raised in the comments of the NGOs and 

shows why mining sources potential to emit HCN remains under 10 tons given EPA’s 

former guidance.

Finally, the third set of comments provides a set of possible management 

practices for HCN that the industry believes to be appropriate.

If you have any questions, please feel free to contact me.

Sincerely,

Melissa Barbanell

(See attached file: partial Title V exemption from MACT for natural minor sources comment.docx)

(See attached file: PTE on HCN emission estimates comment.docx)

(See attached file: HCN management practices comment.docx)
1

Partial Title V Exemption for Natural Minor Sources

The Nevada Mining Association and individual gold mining operations have previously submitted 

comments to EPA during the public comment period on the proposed EPA rulemaking to develop a 

NESHAP for gold mine ore processing and production area sources. While the comment period has 

closed, we believe that EPA may find the following additional information to be useful in its efforts to 

conclude the rulemaking, in particular, relative to determining the extent to which it would be appropriate 

to include a partial exemption in the final rule from Title V operating permit requirements. 

The Nevada Mining Association and individual gold mining operations have submitted prior comments to 

EPA regarding the appropriateness of an exemption from title V under section 502(a) of the CAA for area 

sources covered by the proposed NESHAP. Although a comprehensive title V exemption is still the most 

appropriate choice for avoiding “unnecessarily burdensome” regulations on facilities that are already 

subject to comprehensive permitting requirements, at the very least EPA should exempt sources that do 

not rely on air pollution control devices to stay below major source thresholds. This is an approach that 

EPA has employed on prior occasions. See e.g., 74 Fed. Reg. 56008 (Oct. 29, 2009) (NESHAP for 

Chemical Manufacturing Area Sources – Final Rule); and 75 Fed. Reg. 31896 (June 4, 2010) (NESHAP 

for Industrial, Commercial and Institutional Boilers – Proposed Rule). Such a solution is consistent with 

CAA section 502(a), which provides that the Administrator may exempt an area source category (in 

whole or in part) from title V. See 42 U.S.C. § 7661a(a); 75 Fed. Reg. at 31911.

In cases where EPA determines that at least some area sources covered by a NESHAP should remain 

subject to title V, it has found it useful to distinguish among three different types of area sources. First, 

EPA has identified “synthetic area sources” which rely on emission control systems to stay below the 

major source thresholds. Second, EPA recognizes that some synthetic area sources limit their HAP 

emissions to below the major source thresholds solely by complying with operational limits (e.g., limiting 

the number of hours a facility can operate) rather than by using emission control equipment. Finally, 

EPA defines “natural area sources” as sources that require neither emission control equipment nor 

operational limits to maintain minor source status. See 74 Fed. Reg. at 56013.

In a number of instances, EPA has determined that title V exemptions are appropriate for natural area 

sources and those synthetic area sources that only rely on operational limits to avoid major source status 

while subjecting synthetic minor sources that utilize emission controls to title V. See e.g., 74 Fed. Reg. at 

56014; 75 Fed. Reg. at 31913. EPA’s rationale for exempting the natural area sources and synthetic 

minor area sources that achieve areas source status through operational restrictions is based on its 

application of the Exemption Rule, the four-factor balancing test for determining whether title V is 

unnecessarily burdensome for a particular source category. See 75 Fed. Reg. at 31911-12.

EPA has concluded that sources that rely on emission controls are more like major sources in many 

regards than other minor sources. See 75 Fed. Reg. at 31913; 74 Fed. Reg. at 56014. EPA has also found 

that the increased burdens of title V are justified for synthetic area sources that are often located in highly 

populated areas and which have significantly higher emissions potential when uncontrolled than other 

sources. See 75 Fed. Reg. at 31913; 74 Fed. Reg. at 56014. Accordingly, EPA has decided that the 

“additional public participation and compliance benefits of additional informational, monitoring, 

reporting, certification, and enforcement requirements that exist in title V” should apply to such synthetic 

minor sources. 74 Fed. Reg. at 56014. Conversely, the simpler nature of natural area sources and 

synthetic area sources that maintain minor status through operational restrictions do not merit imposing 

the burdens of title V on such facilities. The absence of a need for emission controls to keep such 
2

facilities below minor source thresholds is a sensible basis for distinguishing the potential burdens and 

benefits of imposing title V. 

A similar conclusion applies to the gold mining industry. The application of the Exemption Rule to the 

gold mining industry has been discussed in comments submitted to EPA by both the Nevada Mining 

Association and individual gold mining operations. If EPA has been unable to conclude that title V 

would be unnecessarily burdensome for all minor sources covered by the proposed gold mining 

NESHAP, it should exempt those gold mining sources that are either (i) natural area sources or (ii) 

synthetic area sources that achieve minor source status through operational limits. Such an approach is 

especially appropriate for the gold mining source category in view of the remote locations of these 

operations. Sources that include processes that rely on complex control systems—for example, roasters at 

Goldstrike, Gold Quarry and Jerritt Canyon—would be subject to Title V operating permit requirements 

based on s synthetic/natural source distinction. On the other hand, mining sources that do not rely on 

control systems to achieve minor source status would not be subject to Title V operating permit 

requirements. This strikes an appropriate balance for the reasons that EPA has articulated in the 

determinations cited above.
1

PTE Emission Estimates for HCN

The Nevada Mining Association and individual gold mining operations have previously 

submitted comments to EPA during the public comment period on the proposed EPA rulemaking 

to develop a NESHAP for gold mine ore processing and production area sources. While the 

comment period has closed, we believe that EPA may find the following additional information 

to be useful in its efforts to conclude the rulemaking, in particular, relative to the need to develop 

regulations of HCN emissions.

EPA is evaluating whether HCN emissions should be addressed in some fashion in the NESHAP 

standard for gold mining that is currently under consideration. It is neither necessary nor 

appropriate for EPA to regulate HCN emissions from gold mining operations as part of the gold 

mining MACT rulemaking. 

If EPA were to regulate HCN emissions pursuant to CAA 112, it would have to do so under one 

of two authorities, neither of which are applicable relative to the gold mining industry based on 

EPA’s rulemaking record:1

• EPA would have to find that the gold mining source category contained one or more 

major sources of HCN pursuant to 112(c)(1), (5). (Assuming that EPA did make such a 

finding, the MACT standard would be limited to only those sources that were shown to 

be major.) The existing record does not support such a determination; to the contrary, it 

supports a conclusion that there are no major sources of HCN emissions in the gold 

mining source category. See additional discussion below regarding HCN PTE. 

• The second authority for regulating HCN emissions from gold mining operations would 

require EPA to make a determination that HCN emissions from the mining industry 

“presents a threat of adverse effects to human health or the environment.” See CAA 

112(c)(3). EPA has not made the requisite finding. In fact, based on extensive ambient 

air quality monitoring that the industry conducted pursuant to and in accord with EPA 

approved monitoring plans, EPA concluded that “the results of the fence line monitoring 

for HCN ... showed ambient concentrations below levels of public health and 

environmental concerns.” See minutes from February 17, 2010 “Meeting with Industry 

Representatives, Nevada Division of Environmental Protection (NDEP), and EPA,” 

Docket ID No. EPA-HQ-OAR-2010-0239-0146.

 

1 The announced rulemaking is being conducted pursuant to 112(c)(6) for mercury: “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 mercury emissions.” 75 Fed. Reg. at 22472, 1st column. CAA 112(c)(6) is specific to seven HAPs, 

including mercury.
2

The record currently supports the conclusion that there are no major sources of HCN based on 

PTE: “EPA recently gathered data and evaluated emissions of other HAP, including cyanide and 

non-mercury metals. The data indicate that the gold mining processing and production category

consists of only area sources (i.e., facilities that emit less than ten tons per year of any one HAP 

and less than 25 tons per year of any combination of HAP).”2 An “area source” by definition has 

a potential to emit of less than the 10/25 tpy major source thresholds.3

“Potential to emit” is defined to mean “the maximum capacity of a stationary source to emit a 

pollutant under its physical and operational design. Any physical or operational limitation on the 

capacity of the stationary source to emit a pollutant, including air pollution control equipment 

and restrictions on hours of operation or on the type or amount of material combusted, stored, or 

processed, shall be treated as part of its design if the limitation or the effect it would have on 

emissions is federally enforceable.”

 

4

Sierra Club and Earthjustice incorrectly assume that EPA’s emission estimates are not based on 

“the maximum capacity” of the mines to emit HCN under their “physical and operational 

design.” While the HCN estimates are based on specific operating parameters for each of the 

several mines, those operating parameters are based on management practices that are inherent to 

those operations. There are reasons unrelated to air pollution control that dictate those measures. 

 

EPA guidance has clearly acknowledged that certain measures that are inherent to an operation 

and that have the effect of limiting emissions are properly accounted for in PTE determinations. 

The actions taken to manage CN usage and concentrations, as discussed above, constitute such 

measures. EPA has consistently recognized that “there are sources for which inherent physical 

limitations for the operation restrict the potential emissions of individual emission units. Where 

such inherent limitations can be documented by a source and confirmed by the permitting 

agency, EPA believes that States have the authority to make such judgements and factor them 

into estimates of a stationary source's potential to emit.”5

 

2 75 Fed. Reg. at 22479-80.

 

3 CAA 112(a)(1) and (2).

4 40 CFR 63.2. 

5 EPA Memorandum, Options for Limiting the Potential to Emit (PTE) of a Stationary Source Under Section 112 

and Title V of the Clean Air Act (Act) (Jan. 25, 1995). As an example, EPA explained that it did not believe that the 

“maximum capacity” language in the PTE definition required that owner of a paint spray booth at a small auto body 

shop must assume operation year-round (8760 hours per year) in cases where there are inherent physical limitations 

on the number of cars that can be painted within any given period of time. (In estimating HCN emissions from 

mining operations, year-round operation was assumed.) See also, e.g., EPA Memorandum, Calculating Potential to 

Emit (PTE) for Emergency Generators (Sept. 6, 1995) (in which EPA explained that its previous guidance was 

intended to “clarif[y] that inherent physical limitations, and operational design features which restrict the potential 

emissions of individual emission units, can be taken into account” when assessing PTE in those cases “for which the 

theoretical use of equipment is much higher than could ever actually occur in practice.” EPA also noted that while 

sources “could in most cases readily accept enforceable [permit] limitations restricting the operation to its designed 

level, EPA believes this administrative requirement for such sources to be unnecessary and burdensome.”).
3

Further, EPA has specifically addressed the appropriateness of accounting for “inherent” control 

measures when assessing PTE.6

 EPA has explained that “control measures . . . can be taken into 

account where those control devices and measures are subject to enforceable [permit] limits or 

are inherent to the operation of the facility.”7

Control measures that are “inherent” are those which are always being operated and 

maintained for reasons other than community air quality protection. Examples of 

inherent control measures would include (a) product collection devices for which the 

value of the product collected greatly exceeds the cost of the collection device, and (b) 

devices for which the primary purpose is to improve product quality control, to recover 

product, or to enhance production operating efficiency . . . .

 EPA explains that:

8

The concept of an inherent control measure is that the source employs such a measure not

In particular, mining operations are required to manage CN exposure from tailings areas and 

heap leaches—the predominant sources of HCN at gold mining operations—so as to be 

protective of wildlife and worker safety. This requires that measures be taken to prevent wildlife 

access to these areas or requires CN concentrations to be maintained at levels that are protective 

of birds and other wildlife. In Nevada, for example, the Nevada Department of Wildlife 

requires, among other measures, that “any chemical-laden fluids that are the result of any process 

and that are impounded in a pond that is too large to cover or contain (e.g., mill tailings ponds) 

must be rendered non-lethal to wildlife.” Accordingly, steps are taken to neutralize CN or 

otherwise manage CN concentrations in these areas.

because it is required pursuant to air regulatory requirements, but due to other considerations. 

For wildlife protection purposes, used leach solution from the mill leach circuit is treated by a 

CN neutralization process prior to discharge to the mill tailing impoundment. This practice 

reduces the weak acid dissociable (WAD) CN in the discharge water to non-lethal levels (i.e., to 

levels safe for birds that will inevitably come in contact with the discharged water). Mine 

personnel routinely sample the WAD CN concentration in the tailings impoundment water to 

ensure safe levels are achieved. As per the International Cyanide Code, cyanide solution that is 

open to the environment must be operated below 50 mg/L WAD CN. Additionally, per the 

Nevada Department of Wildlife, mine personnel are required to report “all wildlife mortalities 

that are associated with chemical-containing tanks or impoundments by the beginning of the next 

day following the occurrence...” This CN neutralization practice has the benefit of minimizing 

the potential for HCN off gassing from the tailings impoundment. The low WAD CN levels 

achieved by this practice significantly reduce the potential for the formation of HCN in the 

tailings impoundment water and its subsequent evaporation to the atmosphere.

In addition to wildlife protection measures, mining companies manage CN usage and 

concentrations for worker safety reasons. Miners are routinely required to work on top of leach 

pads and around open leach solution ponds and tanks. These areas are rendered safe through the 

 

6 EPA Memorandum, Calculating Potential to Emit (PTE) and Other Guidance for Grain Handling Facilities (Nov. 

14, 1995).

7 Id.

8 Id.
4

practice of maintaining high solution pH’s and minimizing cyanide concentrations in the leach 

solutions. This practice minimizes the potential for HCN off gassing in order to comply with 

MSHA HCN exposure limits. Mining companies have a further economic incentive to not over 

utilize CN chemical due to the significant operating cost associated with its use. For instance, at 

one Nevada gold mine with heap leaching operation, the amount spent on cyanide exceeds $12 

million per year–an overuse of 10% would cost the mine an additional $1.2 million per year.

In another EPA guidance letter, EPA elaborated upon inherent controls and limitations that may 

be taken into account when estimating a source’s PTE.9

1. Is the primary purpose of the equipment to control air pollution?

 In this guidance, EPA provides a test 

for determining whether equipment constitutes “air pollution equipment” or air pollution control 

measureswhich can be taken into account in assessing PTE only if the equipment/measures are 

required by an air quality permitor “process equipment” or process measureswhich can be 

taken into account in assessing PTE even if not required by a permit if the equipment/measures 

are determined to be an inherent part of the process. EPA offers the following list of questions 

for consideration in making case-by-case judgments as to whether certain devices or practices 

should be treated as air pollution controls or as inherent to the process:

2. Where the equipment is recovering product, how do the cost savings from the product 

recovery compare to the cost of the equipment?

3. Would the equipment be installed if no air quality regulations are in place?

In the case then under consideration, EPA determined that the primary purpose of the equipment 

at issue was to increase the availability of the process, to minimize safety hazards and to prevent 

impurities from entering the process; not to control air pollution. Additionally, EPA found that 

air quality regulations were not the reason for installation of the equipment. (EPA found that the 

equipment was not used for recovering product and so the second criterion was not relevant to 

the analysis.) Based on this analysis, EPA concluded that the equipment at issue was “inherent 

to the process and can be considered in potential emission calculations without federally 

enforceable requirements.”

This is analogous to measures that mines utilize to manage CN usage and concentrations and 

prevent chemical loss. Although these measures have the effect of reducing air emissions, the 

primary purpose of these measures is not to control air pollution and they would be in place if 

even if no air quality regulations were in place. The CN control measures are for other purposes 

(protect wildlife, minimize chemical usage, address worker safety, etc.). Because they are 

inherent, they are properly accounted for in determining PTE regardless of whether they are 

specifically enumerated in an air quality permit. 

The PTE estimates of HCN emissions from the gold mining industry that EPA has made are 

based on parameters that are reflective of the manner in which the various mines are designed 

and operated for purposes other than air pollution control; they are inherent to the mines’ 

 

9 EPA Letter Detailing Criteria for Determining Whether Equipment is Air Pollution Control Equipment or Process 

Equipment (Nov. 27, 1995).
5

operations and their inclusion allows for a realistic-worst case estimate of emissions. In fact, we 

would argue that EPA has significantly overestimated HCN emissions by not accounting for the 

large surface correction factor (FA) that is necessary to account for the effect that ambient 

concentrations will have on emissions for large surface areas. This (not including FA) results in a 

very conservative (high) estimate of HCN emissions. By accounting for the effect of the large 

surfaces over which the emission is taking place, HCN emissions are estimated to range from 

3.7-4.5 tpy for the larger mines compared to the 5-9 tpy estimate without accounting for large 

surfaces. Accordingly, EPA’s estimate in the preamble to the proposed rule is very conservative 

and provides for a realistic (if not excessive) upper bound estimate of HCN emissions.10

 

10 “[P]otential to emit does not refer to the maximum emissions that can be generated by a source hypothesizing the 

worst conceivable operation. Rather, the concept contemplates the maximum emissions that can be generated while 

operating the source as it is intended to be operated and as it is normally operated. * * * Alabama Power stands for 

the proposition that hypothesizing the worst possible emissions from the worst possible operation is the wrong way 

to calculate potential to emit. 893 F.2d ___, 917 (7th Cir. 1990) (emphasis added) (quoting U.S. v. LouisianaPacific Corp., 682 F. Supp. 1141, 1158).
4837-9349-8631.2

HCN Management Practices

October 28, 2010

The Nevada Mining Association and individual gold mining operations previously submitted comments 

to EPA during the public comment period on the proposed EPA rulemaking to develop a NESHAP for 

gold mine ore processing and production area sources. While the comment period has closed, we believe 

that EPA may find the following additional information to be useful in its efforts to conclude the 

rulemaking, in particular, relative to comments received on HCN emissions. 

There does not currently exist a legal basis for regulating HCN emissions from the gold mining source 

category. The rulemaking being proposed for the gold mine ore processing and production area source 

category is being conducted pursuant to 112(c)(6) specifically for mercury. Further, the current 

administrative record and related legal authority1

Notwithstanding the absence of a legal basis for regulating HCN emissions, the proposed rulemaking 

indicates that EPA evaluated several approaches to manage CN emissions. Following are the potential 

management practices that EPA listed in the proposed rule and a brief response regarding the potential 

utility and practicality of each practice.

support EPA’s conclusion in the proposed rule that there 

are no major HCN sources in the gold mine ore processing and production source category. Finally, EPA 

has concluded that ambient HCN concentrations are below levels of public health and environmental 

concerns.

2

• Maintaining pH of cyanide leach solutions greater than nine. 

While mining operations do monitor and maintain pH levels for several reasons, it is not possible to 

specify a single pH value that will be appropriate for all mines for all times. Because of the 

difference in mineralogy at each mine, scaling can occur at different pH levels. This results in each 

mine having a different maximum pH level at which the cyanide solutions can be maintained. 

Moreover, while it may be possible to manage pH at the CN addition point for each process, it is not 

possible to control the downstream chemistry and the resulting pH. Further, establishing a single, 

enforceable, pH level would likely result in a pH number that is lower than the level at which much 

of the processes actually operate over the annual period. Such a lower number could be misleading 

in terms of the overall pH management that is employed at the majority of mines and suggest higher 

HCN emissions than actually occur. 

• Burying leach lines whenever practical and feasible. 

Some mines may be able to bury leach solution emitters on some leach pads; however, other mines 

deal with larger and more varied sized rock, which is not suited for burying emitters. While the 

proposed management practice to bury leach lines “whenever practical and feasible” is, on its face, 

reasonable, there is good deal of ambiguity in the measure; for example, what criteria will be used to 

determine if it is practical and feasible to bury leach lines? 

 

1 See additional comment on “PTE Emission Estimates for HCN.”

2 Our comment and discussion relative to CN management practices should not be construed as an endorsement by 

the mining industry of the need for such measures to be included in the NESHAP; as we have indicated repeatedly, 

there is neither a basis nor need for doing so.
- 2 - 4837-9349-8631.2

• Monitoring cyanide concentrations at the perimeter and in a downwind direction of main 

emission sources. The industry has conducted extensive ambient monitoring of HCN emissions 

and EPA has concluded that “the results of the fence line monitoring for HCN ... showed ambient 

concentrations below levels of public health and environmental concerns.” While additional 

monitoring would be costly and burdensome, EPA may want to consider allowing mines to elect 

this option in lieu of implementing a site specific plan concerning HCN work practices, as 

discussed further below. 

• Not allowing puddles to form that are greater than 1 square meter on leach pads. While 

application systems are designed to avoid puddles, the aerial extent of the pads can be quite large 

making control to this specified level burdensome, if not impossible to achieve. 

• In locations that have the highest potential for concentrated emissions (e.g., mixing tanks, CIL 

tanks, loading stations) maintain HCN air concentrations below a prescribed level (e.g., 5 ppm). 

In fact, MSHA imposes an HCN exposure limit of 10 ppm. This is for worker protection 

purposes, not ambient air protection. Concentrations in the “ambient air” will generally be 

much lower due to the dispersion and dilution that will occur. 

As we have indicated in a companion submission,3

Because of the above concerns with the specific work practice measures set forth in the proposed rule, a 

more feasible option would be to have each gold mining operation develop a site-specific plan with work 

practices designed to limit HCN emissions. These work practices could include elements contained in the 

International Cyanide Management Code, a comprehensive, peer-reviewed set of measures designed to 

reduce cyanide use in the gold mining industry. The following, based on principles derived from the 

International Cyanide Management Code, provides examples of measures that would be addressed in the 

site-specific plan.

gold mining operations currently employ a number of 

measures in order to manage CN usage and concentrations and prevent chemical loss. These measures 

are inherent to the mines’ operations and are required for worker safety, wildlife protection and cost 

management reasons. Additionally, the measures are customized to each mine based on ore mineralogy, 

gold recovery processes employed, etc. To the extent a rule were to include CN management practices, 

such practices would necessarily need to account for the unique operating characteristics of each mine. 

• Implement management and operating systems to minimize cyanide use, thereby limiting 

concentrations of cyanide in mill tailings.

• Implement a water management program to protect against unintentional releases.

• Implement measures to protect birds, other wildlife and livestock from adverse effects of cyanide 

process solutions.

• Implement measures to protect fish and wildlife from direct and indirect discharges of cyanide 

process solutions to surface water.

• Implement measures designed to manage seepage from cyanide facilities to protect the beneficial 

uses of ground water.

• Provide spill prevention or containment measures for process tanks and pipelines.

 

3 See additional comment on “PTE Emission Estimates for HCN.”
- 3 - 4837-9349-8631.2

• Implement monitoring programs to evaluate the effects of cyanide use on wildlife, surface and 

ground water quality.

These measures provide effective cyanide management practices and while they are focused on issues 

such as wildlife, surface, and groundwater protection, they have the effect of managing HCN emissions as 

well. These measures may be tailored according to the particular operating circumstances of individual 

mining operations. Mines would need to be given latitude to design their measures and plans. 

Compliance would be based on a determination that a mine had a plan in place, the plan contained 

measures designed to manage and limit CN use, and that the mine was implementing such a plan, and not 

on the specific measures that the mine has determined to be appropriate for its site-specific operations. 

To the extent that a mine is complying with permits which address these issues, the permit provisions and 

compliance with these permits could constitute compliance with this requirement. As an alternative 

compliance method to developing and implementing a plan, mines may obtain and maintain certification 

under the International Cyanide Management Code.