THE PRECIOUS METALS COMPANY

Rochester Mine

Environmental Department

P.O. Box 1057 Lovelock,Nevada 89419 Phone: 775.273.7995, ext. 245 Fax: 775.273.7423

October 5, 2006

Mr. La\\Tence Kennedy, Branch Supervisor

Nevada Division of Environmental Protection

Bureau of Air Pollution Control

Enforcement Branch

901 South Stewart Street, Suite 4001

Carson City, Nevada 89701-5249

RE: Addendum to Rochester's Mercury Questionnaire of March 1, 2006

Dear Larry:

Further to our recent discussions, please find attached Coeur Rochester's Addendum to Mercury

Questionnaire which has been updated to include thermal units in our assay lab. We have completed the

attached "Annex 7. Other Thermal Process Units", v,,'ithseveral supplements to reflect that inclusion.

As we have discussed, Cocur Rochester continues to believe that our initial submittal was in full

compliance with the Questionnaire's instructions. As you are aware, this is the first Questionnqire

presented to the company on this issue, and in light of this clarification now being provided by NDEP, we

have incorporated this change in the timely Addendum submittal.

We believe this Addendum should be a full remedy to any misunderstanding as to the necessity to include

the de minimis and non-processing source under the guidelines to the Questionnaire. Please call me with

any questions or concerns.

Yours truly,

" r

, fJ{JLtLlt')~::;"

Jerald N. Hepworth

Environmental Manager

Xc: G. Jeske, C. Jones - Rochester, 11.Cougher, K. Kast, L. Russel1- CDAM, R. DeLong, C.

Postlethwaite - Enviroscientists

Attachments:

I) Completed Annex 7 (2 pages)

2) Assay Lab Thermal Units List (1 page)

3) Draft De Minimis Request (5 pages)

4) 2004 Assay Lab Hg Calculations (2 pages)

- - - - - - --- -- - - - - - - - - - - - - - -
1.

')

3,

ANNEX 7. OTHER THERMAL PROCESS UNITS

Please provide an identification of other thermal process units, including a process

description and the mechanism by which mercury emissions arc released. (Note: if

facility has more than 1 "olher thermal process" process, copy this Annex 7 and

complete a separate copy for each such unit)

a. Description: This al/dendum includes all smaller thermal units locat(~dat Roche/i;ler's

A.~sayLah. Tlte attached sheet lists each of these IInits.

An estimate oCtile actual mercury air emissions re]eased from such unit and the basis of

estimate. ill accordance with the f()lIowinghierarchy of data:

. Direct testing and measurement.

. Based on engineering calculations that take into account the average mercury

content of the orc processed, the amount of ore processed and the potentia! for

mercury releases from the specific processes utilized to recover gold.

Estimated mercury emissions from unit = 0.011 pounds for 2004 (This if;;for the

fire assay funlllces only, all other sources are described in the attacbetl DNA FT

de minimi:,' request letter.)

Basis of estimate: W'e usetla mass balance approacb, based upon number (~f

samples proce."ised and all a~'erage of rock samples tested ill a geochemical

technical report {Maxim 1999 [excerpt (ltlached to the draft de minimis

request/).

Circle the code numbers for the type of air pollution control device and the type of fume capture

system used:

APC device ID no.: NI.4 Fume capture system:

Q

1

2

3

4

No device is used

filter

Wet scrubber

Carbon adsorption unit

Other:

0

1

2

3

None

Side-draft or canopy hood

Close-fitting hood or direct process vent

Other:
Exit Exhaust Vent (or Stack) Parameters (for gascous streams):

height: iV/A n

diameter: iV/A ft

flow rate: iV/A acfm

temperature: IVIA cF

Dcscribe any work practices or other measures that prevent emissions from this operation:

Again, see the attached draft de minimis request.

Have air emission tests been conducted on thcse retort operations?

0

1

No

Yes [Enclose summary measurement data, including data on mercury speciation,

if available, thc tcst methods used, information on actual production or

processing rates and on process conditions at the time the measurements

were made, and a statement that any APC devices (if present) were

operating normally during the test, or if not, what the abnormal operating

conditions were.)

Additional comments and information:

The draft de minimis request also includes tlte men.'UI)' retorts, located in tlte process

blli/tUng refinery. Since Rochester Itad planned to request de mil1imus for tlte retorts

and all otlter tllermtll units in tlte assay lab were muclt sl1wiler, tlte ass a)' lab thermal

IIItits were not included in tlte original submittal. In additioll, tlte assay lab is not

CfJ/tsf(/eretl a processing facility, but rather (III analylical facility, Please /tote that EPA

exempts assay labs from reporting under the Toxic Release bu'el1torJ' (TR/).

Specifically, questionnaire instructions stated tlte following:

"We request that this questionnaire is completed for operations that comprise the

"Primary Extraction and ProcessinQ of Gold and Silver" industry at your facility. This

sector includes all processes that are part of primary extraction, processing, and

nrot1ur.tinn nf nnlri ..",A """A~ -~ -- LH -
Coeur Rochester, Inc.

Rochester Mine

Mercury Reduction Application File

Equipment Type

4

4

.tomicAbsorption Analyzer1

.fomicAbsorption Anal~er

LECO Induction Furnace

Hot Plate

ot Plate

1

1

1

3

1

I The Perkin-Elmer is currently not functional.

2The serial number for the LECO was not obtained as the uoit was in use.

rlA:GStt Jt 000 ~

f-trJ ~ -Av q\1-

c. ODd.1 S-/Ib';)tf ~

Fire Assay Equipment Details

Manufacturer Model

Williams & Witson Limited

Grieve

GHAP

SA-350

500 Atomic

Absorption

Spectrophotometer

Spectra AA220 ES

HF-100

53015

SP18425

Perkin-Elrner

Varian

LECO

Lindberg

Thermolyne

Serial Numberls

TSP-86-06-104.1; TSP-86-06-104-2;

TSP-86-06-104-3; TSP-86-06-104-4

610168;610169;610170;610171

128276

EL99053159

n/a

909234;868054;919

30633087
!'fiF I'I<FCIOI'<; METALS COM!'A\!V

Rochester Mine

Environmental Department . """""""""",---,---,-""'--""""""""" ." mo ~ ,-. ",---' ,.,...,

P.O. Box 1057 Lovelock, Nevada 89419 Phone: 775.273.7995, ext 245 Fax: 775,273.7423

3.2006

\1f. Rob Bam(brd

D1visionor EnvironnlcntalProtection

Gmcau uf Po1!ution Control

\kreury Control Program

Suite 4(JO!

(',lfAlm Cl1v. Ncvadd seno! ,5249

[)C,I'vhni Determination by ('ocu!' RoehesLcL

Lh::1f \11' 13:ml!<mi:

l neu! Rochester. Tne, (CRJ) ISsubmitting this request fo~ De Mininus determinatw!l Ii)!'sekc!

;:q mg in pLlrsuimt to

N \C 445B.3M7. After Hwroughrcview ofpotcntial mcrcury sources at the Facil1ty, CRt reco

assay laboratory and the retort ovens as very minor sources (If mercury emissions than (.;,]

RI Ihitt the Hureau of Air Pb!hnion Control consider these two sources f()!'

')L!lusFst1l11arcd emissions calculations froll) these tWQSOLlrCesarc attached.

LPn [

,bsay laboratory consists of sample drying ()vens, hot plates, furnaces. and analytical cqlIJpmcnl

!!1i1i\';diia!Jy Ifright constitute mercury sources. CRI has considered the assay Jabora!ory iJS

has a approach, The the !lldXinmm

'wm!h:r of samples that can be processed in year, and the average n,ercury content or the geologiC

n,;L'nals, Once [hc .samp!esarc split {\(nvn to it standard CRI iissunlCS

nicrcury II)tbe samples !s emitted at some point in thc process. This is :Jconsen'iltivc appn,adL sJn\..c

\1111\..' !neICUf)wi!! he adsorbed into the crucibles used in the analyses. ~1ndwil! not be rdL.';Jsed 10 mr.

I ']\; doc,;; 11IHconsider the initial drying ofthc bulk samples as capable of emitting mcrcurv.

tlhYS(c()lmnGI1Jyoccurs 111thc mincral cinnabar {HgS), According to CRC Handbo(jK

Ion), CimliJOar a sublimation tcrnperature or 1,082.3 . Tlh.~buJk sarnpk

e al 200 15(Y'F.The mineraJ cinnahar is swbJe in that temperature range. ;md

C:Iny ovens

Industria] hygiene problems in the assay laboratory during thcir ~20 years of operation. Sput

\\-'itb a Jerome mercury detector havt::not recorded levels greater than! tH!.J1l\ (the instrument

lirn
operations, Under standard operations, mercury cmissiom; arc belcH\' detection, Thc product of the

estimated now rale and tbe Jcrome detection limit is used to calculate n maximum mercury cr1\!$sion

Should you have any qucstlons or require additional infonnmion, please do not hesitate to [<.);1\<\(:1cnhcr

'vir ('jay PosUclhwailc ofEnviroscicl1tists, Inc, at (775) 826-8822 or our office,

,kra1d ,\, !klmunh

In"in\nmcnta! .\bnager

cc: G Jeske, C, Jones - Rochester. L, RusscJ1 CDArvt C.Posllclh\\ aite - Errvinhcicnusis

\ Ua('hmcnts
; L < I)[,l Dr M'NiM:i C,LL ;.;j.,JiC)'.

'tury Emission EstimatiQn for the Assay Laboratory

U,nS<k"",g ;h(, AsS;;} U'lx'mk"y a s,n')"" T!EiICVy;ieu,u' ,nJ (,.mp'(Jyng J mass b;)ifncG dPPUiJU, ""WCU'} Hn";SWr\S ':1" tv 8st",\;;ied fj&10ilow5

S'F1;h!$ assJyed :j:~i 135

165

49275

"aiXJU!<"} f:'W"'JI",\] d,~ys ::ie' yea;

PtAt'i;:!..: samp!i.,s a&,,3y'~(j pt;f fear

fhi "am:Ac,; ale crushed ,we: $piJi!o 20G 9 SiJ!npki$ that ;]10 (j,i,)d at 215 degn:.'BS 15 houri,; Thc m;;rC(JfYOG(:Jrs prim;Jr1:"

!f1 ttJe minerai tlrm;JDW (HgSL Wri;(t)dGes no, voiahlib) 81 the"" rempeZill,JreS The 5ampio$ ive next 'jdeh $plit to jO 9

Thes~ smaHer S,Jlits ;Jre thor nNHed '"iti1 m;:;rC\J/j !ros tux H1furnnccs Jnd mu'yn:d for !Mir f/\,)id and S1lv81 GOhteht

Mercury ;:malyse$ are oo! cDmtnOhly yerJormect or the assay $i)n;pje~, MerctJry cootWHS of 0n, ant! waSH! ,d UJU",ine ,,~)W evahl(j,ed n j998,

H!J$M 00 \40 samp'BS from a variety 0111<11101(">\1105 Dod allwpHcw tones, the avst<!ge mercury ccn,(;(1! of ,h \)<X>'Qgl<::: "'1)t8[131$ it::l :,2 ;>pm

AS$lmw1g I.h.,t ,,11mwcury in lhe samphj$ ~; released 10 the aimDsphefi},

'" fig errtml!d

(glyr)

'" 5,203

a.Ofl

gly'

Iblyr

t'VE>!i<J5"UmH\f) an <llIsfage morcwy Q)"tenl of 7 "pm, 1\nuua! fYH;>fWrySn\l5SfOf) shoul-:l nO\ exceed 0.023 Iblyr

;ury Emission Estimation for the Mercury Retort

CRM Of"lrales tv.'I) ((HQrt ovens dueted 10 a ch,ileiicO0cJ"nser that condenses I!)" majcwHy of the mew"y vapor re:e<:Jsed II!!;cvens,

The gas stream !rom the ('.()fKtens.ersp1\S$0S through cannlsters of sulfur.lmpr,;gn:.ted ;J,.t'V;)tec c:hnrcO1!1tJefore e~lrin9 the bl,J:k:!og

CRMernph:Jyt.a h;'HTd-f\\')ldJewme rnerc:urydetet:lcv1(1the refirery to Ch,)£1<m,?rcwy kwels during refilw1g opew(\Jns.

The exhzwst SldCk 01the retofl~ is also te&ted dunnq e:Jctf opwdting CloD.!of tJe retorts The Je1om0 has a detect,>n limnof 1 pp;"n?.

Stack d'3mnler is 4 IrKhe!> H()l/w,ve' Ihe 110'10'dOC ve!{)(:::y aie knG\,n A$$\irning;, GZJnscrY;Jti~'e \ls:o<Ay of 5 rnph \ '(,3 ft/s),

the ftow !;Jte eqllnls (JPv(),'ima\d~ 36 dm,

"Vr!" no mercury detected at;) 1 I'ghn3 dektOe:>n "11>1m;;j"murn retcH "'Dissinns :1", e$t10aPYJ d$

flOW ft3

mill

x. ().()2i:!JI mJ

'---iij--

x ;':£fll£i mJx 150m/I'!

--7',' )( " fig Qmission!; (g/fr)

YI

38 0.02831 UV)E;..m; 60 87M 5.85E.O1 glyr

1 25E.{)] Ifl/yr

q:15 11) " urn,. ';'VI ", -te\(ke'\ ;>49L.O3 Ibft'

,:", "18G Di,Min;n1HV:)

_mmSaj?"L" )( Weight tElL )( "Avt!!!ttQ!1ICl'1t {ppmw} x , yr 1 -1,OOE+O6

49275 x 30 x 3.52 )I, 1.()()E.Q6
Coeur Rochester

ass f G istry

SUbf>!I::" '}

US. Bureau of Land

Winnemucca, Nevada

and

Nevada Division of Environmentai Promction

Bureau of Mining Regulation and

Ci:lr$on City, Nevada

SUI;mdtf!(! by

Coeur Rochester, Inc.

L()veiock, Nevada

'0 E R

Dl:N:

Maxim Technc~ogj(;}S, Inc.

TrCHNOlOG!~5 !NK
, ii". "'iF Ph;;;$!, ! Inl(fnrrJ Nep()r;

TABLE :;1.5

MF4N WHOLE ROCK CONCENTRATIONS FOR SELEcr METALS iN ,,\U ROCKOHE j\NL

BY UTHOLOGY, ALTERATiON, AND OXiDAtiON (SHAm:'! Pf\RJi,Mf

SI(;i'm'j(;ANTL

, r,," " ,e i'", ..'.: ' ;, ",.,,~,..,

,""S'.»' , ,.". "';. ,n:",

'-,..:',-"

p,. h '.. "'",

h{; I';);;

p;n

~ it' : .W"'"

i.""

""",J:,,':
COEUR ROCHESTER,NC.

COUEUR ROCHESTER MiNE DE MINIMIS CALCULATIONS

2004 Mercury Emission Estimate for the Assay Laboratory

Considering the Assay Laboratory as a single mercury source. and employing a mass balance approacrl. mercury emissionscan be estimated as faHows:

Samples Assayed 2004 46930

The samples are crushed and split to 200 9 samples that are dried at 215 degrees F fOf 1 5 hours. The mercury occurs primarily

in the mineral cinnabar (HgS).which does not vOlatilizeat these temperatures. The samples are next each split to 30 g.

These smaHersplits are then melted with mercury-free fluxin furnaces and analyzed for theif gOldand silver content

Mercuryanalyses afe not commonly performedon the assay samples. Mercury contents of ore and waste at the mine were evaluated in 1998.

Based on 140 samples from a variety of !lithologiesand alteration zones, the average mercury content of th geologic materials is 3.52 ppm.

Assuming that all mercury in the samples is released to the atmosphere,

10/4!20D6 De Minimis 157BC.2004Assay Laboratory Emissions.xls

Samples )( Weight (g) x Ave Hg content (ppmw) ( 1 :: Hg emitted

yr 1 1.00E+O6 (gfyr)

46930 x 3CJ x 3.52 x 1.00£:-06 :: 4.956 glyr

0.011 lblyr
Coeur Rochester Phase I Geochemistry Interim Report (1998)

Total

# Samples Ave Hg (ppm) # Samples x Ave

3 1.7 5.1

1 1 1

53 3.9 206.7

212

65 3.4 221

236

14 3.6 50.4

140 3.52 Average