THE PRECIOUS METALS COMPANY 

# Rochester Mine Environmental Department P.O. Box 1057 Lovelock,Nevada89419 Phone: 775.273.7995, ext. 245 Fax: 775.273.7423


### October 5, 2006 Mr. La\\TenceKennedy, Branch Supervisor Nevada Division ofEnvironmental Protection Bureau ofAir Pollution Control Enforcement Branch 901 South Stewart Street, Suite4001 Carson City, Nevada 89701-5249 RE: Addendum to Rochester's Mercury Questionnaire of March 1,2006 Dear Larry: 

### Further to ourrecent discussions, please find attached Coeur Rochester's Addendum to Mercury Questionnaire which has beenupdated to include thermal units inour assay lab. We havecompleted the attached "Annex 7. Other Thermal Process Units", v,,'ith several supplements to reflectthat 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 firstQuestionnqire presented tothe company onthis issue, and in lightofthis clarification now being provided by NDEP, we have incorporated this change in thetimely Addendum submittal. Webelieve this Addendum should be a fullremedyto any misunderstanding as to the necessity to include the de minimis and non-processing source underthe guidelines to the Questionnaire. Please call mewith 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 (2pages) 2) Assay LabThermal Units List (1 page) 3) Draft De Minimis Request (5 pages) 4) 2004 Assay Lab Hg Calculations (2pages)

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### 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 copyfor each such unit)
a. Description: This al/dendum includes allsmaller thermal units locat(~d atRoche/i;ler's A.~sayLah. Tlte attached sheet lists each ofthese IInits. An estimate oCtileactual mercury airemissions re]eased from such unit and the basis of estimate. illaccordance with the f()lIowinghierarchy ofdata:



# . 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 assayfunlllces 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 airpollution control device andthe 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 (forgascous streams): height: iV/A 

# n diameter: iV/A ft flowrate: iV/A acfm temperature: IVIA cF 

### Dcscribe any work practices or other measures that prevent emissions fromthis 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 (ifpresent) 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 Itadplanned to request de mil1imus for tlte retorts and all otlter tllermtll units in tlte assay lab were muclt sl1wiler, tlte assa)' lab thermal II

Itits were not included in tlte original submittal. In additioll, tlte assay lab is not CfJ/tsf(/eretl a processing facility, but rather (IIIanalylical facility, Please /tote that EPA 

### exempts assay labsfrom reporting under the Toxic Release bu'el1torJ' (TR/). Specifically, questionnaire instructions stated tltefollowing:
"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.



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f-trJ ~ -Av

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# \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-86-06-1 04.1; 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 

### D1vision or 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 (Ifmercury emissions than (.;,]



### RI Ihitt 

### the Hureau of Air Pb!hnion Control consider these two sources f()!' ')L!lusFst1l11arcd emissions calculations froll) these tWQSOLlrCes arc attached. LPn [ ,bsay laboratory consists of sample drying ()vens, hot plates, furnaces. and analytical cqlIJpmcnl !!1i1i\';diia!JyIfright 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 itstandard 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. ~1nd wil! not be rdL.';Jsed10mr. I ']\; doc,;; 11IH consider the initial drying 

### ofthc bulk samples as capable ofemitting mcrcurv. tlhYS( c()lmnGI1Jyoccurs 111 thc 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 swbJein 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 lirnoperations, 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\<\(:1 cnhcr '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(JfY OG(: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;>fWry Sn\l5SfOf) shoul-:l nO\ exceed 0.023 Iblyr ;ury Emission Estimation forthe 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$0Sthrough cannlsters of sulfur.lmpr,;gn:.ted ;J,.t'V;)tec c:hnrcO1!1 tJefore e~lrin9 the bl,J:k:!og CRMernph:Jyt. a h;'HTd-f\\')ld Jewme rnerc:ury detet:lcv1(1the refirery to Ch,)£1< m,?rcwykwels during refilw1g opew(\Jns. The exhzwst SldCk 01the retofl~ is also te&ted dunnq e:Jctf opwdting CloD.!of tJe retorts The Je1om0has a detect,>n limnof 1pp;"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$t10aPYJ d$

flOWft3

mill x. ().()2i:!JImJ '---iij-- x ;':£fll£i mJ x 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 fG 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



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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

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""",J:,,':COEUR ROCHESTER,NC. COUEUR ROCHESTERMiNE DE MINIMIS CALCULATIONS
2004 Mercury Emission Estimate for the Assay Laboratory ConsideringtheAssay Laboratoryasa single mercurysource. and employinga mass balanceapproacrl. mercury emissionscan be estimated as faHows: Samples Assayed2004 46930 The samples are crushedand split to 2009 samplesthatare driedat 215degrees FfOf 1 5 hours. The mercuryoccurs primarily in the mineral cinnabar (HgS).whichdoes not vOlatilizeat these temperatures. Thesamples are nexteach splitto 30 g. These smaHer splits are then meltedwith mercury-freefluxin furnacesand analyzedfor theif gOldand silver content Mercuryanalysesafe not commonlyperformedon the assaysamples. Mercurycontentsof ore and waste at the minewere evaluated in 1998. Basedon 140samplesfrom a varietyof !lithologiesand alteration zones, the average mercury content ofth geologic materials is 3.52 ppm. Assumingthat all mercuryin the samplesis releasedto the atmosphere,

10/4!20D6 De Minimis 157BC.2004Assay LaboratoryEmissions.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 IGeochemistry Interim Report (1998)

Total 

# # Samples AveHg(ppm) #Samples xAve 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