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Date: August 10, 2010

Subject: Minutes of the August 9, 2010 Conference Call with Nevada Division of 

Environmental Protection

EPA Contract No. EP-D-06-118; EPA Work Assignment No. 4-06

RTI Project No. 0210426.004.006

From: Chuck French

OAQPS/SPPD/MMG (D243-02)

U.S. Environmental Protection Agency

Research Triangle Park, NC 27711

To: Docket ID No. EPA-HQ-OAR-2010-0239

I. Introduction

A conference call with Nevada Division of Environmental Protection (NDEP) was held on 

August 9, 2010. The purpose of the meeting was to clarify a few of NDEP’s comments on the 

proposed rule and how data are handled in the Nevada Mercury Control Program (NMCP).

II. Attendees

Mike Elges, NDEP

Rob Bamford, NDEP

Chuck French, U.S. EPA, OAQPS

Marvin Branscome, RTI International

Gabrielle Raymond, RTI International

III. Discussion

The major topics discussed during the meeting included how the hours of operation are 

reported in the NMCP Annual Emissions Report, how NDEP requires facilities to be measure ore 

“as fed” to the autoclave, emissions from the quenching units at Jerritt Canyon, new Twin Creeks 

autoclave data, Goldstrike preheater data, gold mine definition, carbon new source MACT limit, 

roaster parametric monitoring, and mercury concentration monitoring. 

Attachment 1 contains the discussion items for the conference call with NDEP provided by 

the EPA.
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Attachment 1 
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Discussion Items for Conference Call with NDEP on 8/9/2010

1. How do you require facilities to determine operating hours for different types of process units for 

the Annual Emission Reports (AER)? We will need to specify this in the rule, and an important 

consideration is that what we require is the same as or similar to how the data were collected that 

we used to derive the emission limits, which we think is consistent with NDEP’s AER.

2. How do you require facilities to measure and report throughput of ore for the autoclaves? Industry

recommended that the weight or the density and volumetric flow rate of the ore slurry be allowed 

to be measured as it is fed or as it exits the autoclave(s). They explained that this change would 

allow them the flexibility to monitor the density and volumetric flow rate of the ore slurry either 

before or after the autoclave, which they say is the same mass flow for all practical purposes. We 

proposed measuring the feed to the autoclave. If the two are different, we hypothesize that what 

comes out would be slightly less than what is fed, which would be a more stringent compliance 

determination (i.e., the denominator would be lower). Is this correct? Anyway, if we allowed 

industry to use ore exiting the autoclave because that is what they measure, is there any problem 

with this?

3. For Jerritt Canyon Mine (Queenstake), what is the emission point(s) for emissions from the roaster 

quenching exhaust (e.g., the roaster control system, a separate stack, and un-testable release 

point)? Let’s discuss how the quencher is configured and how the rule might address any unusual 

characteristics at Jerritt Canyon. The industry commented that Jerrit Canyon’s quenching 

emissions must be accounted for and included in the MACT analysis, and they suggested that we 

use an average of Goldstrike and Gold Quarry’s quenching data based on percent of total 

emissions from quenching to represent the quenching emissions for Jerritt. Another approach 

might be to use the lb/MM tons of ore contribution from quenching at the other facilities with 

quenching emissions data. Any other ideas?

4. Do you know why the new data for Twin Creek’s autoclaves shows lower emissions than the data 

we used at proposal (about 50% lower in lb/MM tons ore)? Were there changes in operation or 

controls that would justify using only the new data and not the higher 2007/2008 data? Or are all 

the measurements representative of normal variability?
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Autoclave Date Test 

Method

Avg Hg 

Emissions 

(lbs/hr)

Ore 

Throughput 

(tph)

Avg Hg 

Conc. 

(gr/dscf)

lb Hg/MM 

ton ore

Hg Conc 

in Ore 

(ppm)

1 6/14/2007 101A 4.34E-02 220.7 8.37E-04 197 40.8

1 6/14/2007 OHM 5.26E-02 227.3 9.68E-04 231 40.8

1 6/15/2007 101A 6.62E-02 246 1.15E-03 269 27

1 6/15/2007 OHM 6.55E-02 245 1.02E-03 267 27

1 8/18/2008 29 8.47E-02 242 1.72E-03 350 29.7

2 6/17/2007 101A 3.30E-02 232 6.06E-04 142 28.8

2 6/17/2007 OHM 2.54E-02 235.3 4.23E-04 108 28.8

2 8/21/2008 29 3.30E-02 239.3 6.73E-04 138 44.33

1 11/3/2009 3.42E-02 247.9 5.73E-04 138 34.7

2 11/5/2009 1.29E-02 236.5 2.44E-04 55 40.4

2 3/9/2010 2.16E-02* 245 4.00E-04 88 20.5

1 5/3/2010 4.36E-03* 234 7.76E-05 19 28.5

* Estimate based on gr/dscf (we need to get lb/hr data).

5. Do you know why there is so much variability in between the runs for the following tests at 

Goldstrike? See the high relative standard deviations (RSDs). Are there reasons not to use the 

data?

Unit Test Date Run 1 

(lb/hr)

Run 2 

(lb/hr)

Run 3 

(lb/hr)

Average 

(lb/hr)

Standard 

deviation

RSD

North -

Mill 1 7/9/2009 4.30E-04 6.70E-04 4.80E-04 5.27E-04 1.27E-04 0.24 

North -

Mill 1 8/3/2007 4.00E-01 4.00E-02 2.10E-02 1.54E-01 2.14E-01 1.39 

North -

Mill 1 3/14/2007 1.30E-03 9.00E-04 7.80E-04 9.93E-04 2.72E-04 0.27 

North -

Mill 1 10/22/2007 2.70E-03 2.10E-03 4.00E-04 1.73E-03 1.19E-03 0.69 

North -

Mill 1 10/22/2007 3.30E-03 1.70E-03 4.00E-04 1.80E-03 1.45E-03 0.81 

South -

Mill 2 7/14/2009 1.14E-02 6.19E-03 2.25E-03 6.62E-03 4.59E-03 0.69 

South -

Mill 2 8/4/2007 1.10E-02 8.00E-03 1.10E-02 1.00E-02 1.73E-03 0.17 

South -

Mill 2 3/12/2007 3.60E-02 7.70E-03 1.20E-03 1.50E-02 1.85E-02 1.23 

South -

Mill 2 10/22/2007 1.30E-03 1.30E-03 6.00E-04 1.07E-03 4.04E-04 0.38 

South -

Mill 2 10/23/2007 2.50E-03 1.30E-03 6.00E-04 1.47E-03 9.61E-04 0.65 
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6. We received several comments that the rule as proposed would apply to many people and 

operations for which it was not intended, such as individuals (prospectors), laboratories, pilot 

plants, small mining operations, and non-leaching operations. Apparently the proposed rule would 

capture those entities that have any type or size of melt furnace, whether used by an individual or 

by a lab for assays. Do you have any suggestions how we could clearly exclude those not 

intended to be covered by the rule, potentially, and as appropriate?

7. We continue to recognize that using Round Mountain as the basis for new source MACT for the 

carbon group is problematic. Industry suggested a separate subcategory for facilities without 

retorts or a subcategory for low mercury in the ore. We anticipate potential problems with 

subcategorizing by mercury in the ore. Any thoughts on subcategorizing facilities without retorts 

or any other ideas?

8. What should be the operating parameters to be monitored for roasters at Gold Quarry (and other 

roasters)? Newmont took great issue with monitoring pressure drop and inlet temperature, plus 

they do not like setting any operating limits based on monitoring during the compliance tests. We 

need something to ensure proper operation on a continuous basis. Has NDEP developed their 

final permit requirements for monitoring roasters?