Final environmental impact statement appended to and adopting the draft environmental impact statement : Pegasus Gold Corporation's, Diamond Hill Mine Project

66 Pages·1996·2.9 MB·English

by  Montana. Hard Rock Bureau

s
622*342
E30fepg DEPARTMENTOFENVIRONMENTALQUALITY
1996
RECLAMATIONDIVISION
MARCRACICOT,GOVERNOR 1625ELEVENTHAVENUE
STATE OF MONTANA
(F4A06X)(444046-)2404744-1923 HELENA,MONTAPNOAB5O9X62200-11660011
LLri
March28,1995> * i t f Ul'l/V
Re: FinalEnvironmentalImpactStatementfortheproposedDiamondHillMineProject
DearReader:
TheDepartment ofEnvironmental Quality has adopted the draftEnvironmental Impact
Statement(EIS) fortheDiamondHillMineProjectasthefinalEIS. Theenclosederrataand
appendicesamendthedraftEIS. Theappendicescontainthepubliccomments,thedepartment's
responsestopubliccomments,andPegasusresponsestosomeconcerns. However,noneofthis
additionalinformationsubstantiallychangedtheanalysescontainedinthedraftEIS.
dateoftThhiseldeettpearratsmepnrtovwiidleldnoitnAmaRkMea26f.i2na.l65d0e(c4i)s.ionAopnutbhliiscpnrootpiocesewdilplrbojeepctreupnatirled15anddaydsisatfrtiebrutthede
nosoonerthanApril12,1996. However,thepreferredalternativeisdescribedintheattachederrata
(pages1and3). Agencystipulationswouldincludefouritemspertainingtotrafficsafetyandone
pertainingtotheprotectionofculturalresourceslocatedinIndianCreekCanyonthatareinclose
proximitytoproposedroadwideningactivities,atraffic-safetymitigation. Stipulationscouldbe
addedoralteredwhenthefinaldecisionismade.
PegasusGoldCorporation'sproposedDiamondHillMillProjectwouldbelocatedapproxi-
mately8milesnorthwestofTownsend,Montana. Thedevelopmentofthisundergroundgoldand
silverminewouldresultinexpansionoftheexistingexplorationdeclineandwasterockdump,
constructionofaninfiltrationgallery,thehaulingoforetoMontanaTunnelsoranothersuitable
millingfacility,andwhenthemine'seconomicspermit,thedevelopmentofamill, stormwater
reservoir,andwasterock/tailingsrepository. Theprojectwouldlast7yearsanddisturbamaximum
of37.2acres.
Ifyouhaveanyquestionspertainingtothisprojectandrelateddocuments,pleasecontactthe
departmentatP.O. Box200901 or 1520E. SixthAvenue, Helena,MT 59620-0901, attention
KathleenJohnson. OryoumaycontactMs.Johnsonat(406)444-1760.
Sincerely, mTEDOCUMENTSCOLLECTION
JUL 03 1996
MONTANASTATELIBRARY
SHaanrddraRoJ.ckOlBsuerne,auChief HELEN1A5,15MEO.N6TtAhNAAVE5.9620
KJ/fo
Attachment
fc: DiamondHill.833 "ANEQUALOPPORTUNITYEMPLOYER"

FINALENVIRONMENTALIMPACTSTATEMENT
APPENDEDTOANDADOPTINGTHE
DRAFTENVIRONMENTALIMPACTSTATEMENT
PEGASUSGOLDCORPORATION'S
DIAMONDHILLMINEPROJECT
March1996
TheDepartmentofEnvironmentalQualityisadoptingthedraftEnvironmentalImpactStatement
(EIS)fortheproposedDiamondHillMineProjectasthefinalEISasallowedunder26.2.650ARM.
Thefollowingerrataitemsaretheresultofchangesnecessarytorespondtopubliccommentsonand
agencyreviewofthedraftEIS fortheproposedDiamond Hill MineProject. Thesechanges are
presentedinthismannerbecauseoftherelativelysmallnumberofchanges. Thebulkofthechanges
incorporatedadditionalinformationaboutlandusesandtraffic. MinormodificationstoPegasusGold
Corporation'sorehaulingplanmitigatedsomeofthetrafficsafetyconcernssubmitted. Pegasusprovided
additionaldetailregardingaroadimprovementplanandagreementwithBroadwaterCountyaboutIndian
CreekRoad. Thedepartmentdevelopedafewmorestipulationstoaddresstrafficsafetyissuesandthe
protectionofaculturalsitewithinIndianCreekCanyonfromroadimprovementactivities. Noneofthis
additionalinformationsubstantiallychangedtheanalyses;however,someofthetrafficsafetyhazards
havebeenfurtherreduced.
Anappendix,PUBLICCOMMENTSANDCONCERNSfollowstheerrataandcontainsa
compilation ofthe comments received during thepublic comment period and the Department of
EnvironmentalQuality'sresponsestothosecomments.
ERRATAFORTHEDIAMONDHILLEIS
SUMMARY
1. PageS-7
Lastparagraph,AGENCYPREFERREDALTERNATIVEheader:
Replacetheparagraphwiththefollowingparagraph:
"Theagency-preferredalternativeisthemitigatedproject. Thisalternativewouldhave
thegreateropportunityto improvetrafficsafetyalongIndian CreekRoad. However, the
developmentofthesemitigationsdependsuponcooperationandagreementbetweenPegasus,
BLM, BroadwaterCounty and possibly Continental Lime. DEQ prefersthetrafficsafety
mitigation which involves some improvements to Indian Creek Road in conjunction with
Pegasus'sproposedtransportationplans. Additionalmitigationsincluderestrictingorehauling
duringpeaktrafficperiodsonMontanaHighways287/12,timingoftruckentrytoavoidconvoys
onthehighway,compliancewithPegasus'MOAwithBroadwaterCounty,andthestipulation
toprotecttheculturalresourceswithinIndianCreekCanyontothesatisfactionofBLM. This
alternativewouldresultintheexpansionoftheexistingexplorationdeclineandwasterockdump,
constructionofanadditioninfiltrationgallery,thehaulingoforetoMontanaTunnelsoranother
1
Uafu W>~ fl^ k7
suitablemillingfacility,andwhenthemine'seconomicspermit,thedevelopmentofamill,
stormwaterreservoir,andwasterock/tailingsrepository."
CHAPTER1
2. Page8
Fourthparagraph,5thsentence:
Inserttheword"for"beforethephrase"sitegrading."
3. Page11
Firstparagraphunder"Issue1:CountyEconomics"header:
Addthefollowingsentencetotheendoftheparagraph:"Thisgrowthhasoutpacedthe
government'sabilitytoprovidethoseservices."
4. Page12
Lastparagraph,3rdsentenceafteritalicizedheader:
Deletethewords"wasterockand"andinserttheword"or"sothelastphrasereads
"runonorwaterdischarges."
5. Page12
Lastparagraph,4thsentenceafteritalicizedheader:
Insertthephrase"wasterock"afterthephrase"byisolatingreactive."
6. Page16
Thirdparagraph
Replacetheperiodattheendofthe2ndsentencewithacommatocombinethelasttwo
sentencesintoonesentence.
CHAPTER2
7. Page21
Lastparagraph,6thsentence:
Insertthereference"(PegasusGoldCorp. 1996d)"attheendofthesentenceending
"...onCorbin-WickesRoadtothemill."
8. Page25
ThirdparagraphafterPhaseIIheader,2ndsentence:
Deletethephrase"inconvoysofatleastthreetrucksunderPhaseII."
9. Page33
Secondbullet:
Addthefollowingsentencetotheendoftheparagraph: "Pegasuswouldinformits
2
" "
contractorswhowouldbedoingapprovedroadimprovementsalongIndianCreekRoad(Pegasus
GoldCorp.,1996b)thattheMcCormickLiveryandFeedStableSignandanhistoricwooden
flumeinthecanyoncouldnotbedisturbedduringthework(PegasusGoldCorp.,1996c)."
10. Page34
Thirdbullet:
Addthefollowingsentencetotheendoftheparagraph: "Thecountyhastheauthority
tomakethesechangestoIndianCreekRoadonBLMlandsaslongasthechangesoccurwithin
thecounty'sexisting60-footright-of-way."
Addthefollowingparagraphsafterthethirdbullet:
"Inordertominimizetraffichazardscausedbyslow-movingore-haulingtrucksentering
MontanaHighways287/12,Pegasuswouldrestrictorehaulingbetween4:00p.m.to6:00p.m.,
JunethroughSeptember,andwouldensurethattrucksenteredthehighwaysinglyataminimum
of10minuteintervalstopreventpassinghazardscausedbyhighway-speedtraffictryingtopass
alonglineofslow-movingtruckstryingtoattainhighwayspeedsonthelonguphillclimbtoward
Helena.
"ConcernsexpressedaboutthepotentialforimpactingculturalresourceswithinIndian
Creek Canyon during road widening activities has resulted in the need for an additional
mitigation. ThedepartmentwouldstipulatethatPegasustakeallnecessarymeasurestoprotect
theMcCormickLiveryandFeedStableSignandthehistoricflume. Anyactivitieswhich
potentiallythreatenthesesitesmustimmediatelybereportedtoBLMsothatBLMcaninitiate
106consultationwiththeSHPO. Activitiespotentiallythreateningthesesiteswouldneedtobe
halteduntilBLMwassatisfiedthatthesesiteswereappropriatelyprotected."
11. Page35
Fourthline:
Addthefollowingsentencetotheendoftheparagraph:"Theconstructionstart-update
hasnotbeenestablished.
12. Page35
Firstparagraphunder"BroadwaterRodandGunClub"heading,1stsentence:
Replacethephrase"oflandBLMleasedtothecounty"withthephrase"ofcountyland.
13. Page38
Lastparagraph,AGENCYPREFERREDALTERNATIVEheader:
Replacetheparagraphwiththefollowingparagraph:
"Theagency-preferredalternativeisthemitigatedproject. Thisalternativewouldhave
thegreateropportunityto improvetrafficsafety alongIndianCreekRoad. However, the
developmentofthesemitigationsdependsuponcooperationandagreementbetweenPegasus,
BLM, Broadwater County andpossibly Continental Lime. DEQprefers thetraffic safety
mitigation which involves some improvements to Indian Creek Road in conjunction with
Pegasus'sproposedtransportationplans. Additionalmitigationsincluderestrictingorehauling
3
duringpeaktrafficperiodsonMontanaHighways287/12,timingoftruckentrytoavoidconvoys
onthehighway,compliancewithPegasus'MOAwithBroadwaterCounty,andthestipulation
toprotecttheculturalresourceswithinIndianCreekCanyontothesatisfactionofBLM. This
alternativewouldresultintheexpansionoftheexistingexplorationdeclineandwasterockdump,
constructionofanadditioninfiltrationgallery,thehaulingoforetoMontanaTunnelsoranother
suitablemillingfacility,andwhenthemine'seconomicspermit,thedevelopmentofamill,
stormwaterreservoir,andwasterock/tailingsrepository."
CHAPTER3
14. Page40
Secondfullparagraph,1stsentence,lastword:
Theword"oxidize"shouldbe"oxidizes."
15. Page49
Thirdparagraph1stsentence:
Addthefollowingreferencetotheparentheticalphrase"BLM1995b."
16. Page49
Fourthparagraph:
Insertthefollowingsentenceafterthe1stsentence: "Otherrecreationalusersinclude
weekendminers,goldpanners,rockclimbersinIndianCreekCanyon,aswellasbowhunters
(fromLaborDaytostartofregularhuntingseason),andfishermengoingtoCrowCreek."
Changetheword"daus"to"days"inthelastsentence.
17. Page50
Secondparagraph:
Replacethesecondparagraphwiththefollowingparagraph,insertionsareredlined:
"TheHelenaNationalForest's1980trafficdataforIndianCreekRoadindicatethatthe
averagevehicledailytraffic(ADT)fromMaythroughSeptemberwas11.8vehicles;frommid-
OctoberthroughtheendofhuntingseasoninDecemberitwas22.7vehicles(PegasusGoldCorp.
1995). TheoverallADTwas14.2vehicles;thehighestdailyvolumewas56andthelowestwas
six. Itislikelythatexistingtraffichasincreasedsignificantlysince1980. ForestServicedata
forCrowCreekRoad,,anothermainaccessrouteontheeastsideoftheElkhorns,indicatesabout
40vehiclesperdayduringhuntingseason. Duringtheweek,trafficthroughthecanyonand
aboveitisprobablycomposedofpeopleaccessingminesandhomesteadsandcheckingoncattle.
Thereareoccasionalcattledrivesinearlysummerandfalltakingcattletoandfromsummer
grazingranges. Weekendandseasonaltrafficisgreaterduetorecreationalactivitiesandhunting,
trafficisgenerallytheheaviestduringhuntingseason. TrafficbelowIndianCreekCanyon
consistsprimarilyofcoaltruckstoandlimetrucksfromtheContinentalLimeplantaswellas
commutingemployees,countygarbagecontainertrucksgoingtothetransferstation(eightto10
tripsperday),semi-truckshaulinggarbagedumpstersawayfromthetransferstation(oneevery
otherday),andvisitorstotheBroadwaterRodandGunClub(MikeMasolo,BroadwaterCounty,
personalcommunicationwithKathleenJohnson,DEQ,January 10, 1996). Accordingtothe
4
"
MontanaDepartmentofTransportation,720vehiclesadayusethelowerportionofIndianCreek
Roadtoaccessexistingminingoperationsandresidentialdevelopments. Residentialtrafficis
expectedtoincreaseoverthenextseveralyears(DOT1996)it
;
18. Page50
Fourthparagraph:
Insertthefollowingsentenceatthebeginningoftheparagraph:"Thereareapproximately
22trainsadaycrossingIndianCreekRoadapproximately320feetwestofMontanaHighways
287/12."
Addthefollowingsentencetotheendoftheparagraph:"Trafficturningnorthwestonto
thehighwayfromIndianCreekRoadhasalonguphillgradetoclimbwhilereachinghighway
speeds.
19. Page49
Firstparagraph:
Insertthefollowingparagraphaftertheparagraph:
"WithintheIndianCreekCanyonisahand-paintedsignononeofthelimestonewalls.
Thesigndatesbacktothelate1800sandisknownasthe"McCormickLiveryandFeedStable
Sign." ItwasplacedontheNationalRegisterofHistoricPlacesonJuly8,1981. Thereisalso
anhistoricflumeinthecanyonthatprobablyprovidedwatertooneofthehistoricminesormills
inthearea.
CHAPTER4
20. Page55
Secondparagraphunder"AIRQUALITY", 3rdparagraph:
Insertthephrase"Littleorno"atthebeginningofthesentenceandreplacetheword
"and"inthephrase"mineopeningsandfromoldminewaste"withtheword"or."
21. Page56
Lastparagraph,nexttolastsentence:
Deletethe"BritishColumbiaAcidMineDrainageTaskForce,1988"referencefromthe
parentheticalphraseattheendofthesentence.
22. Page57
Thirdparagraph,nexttolastsentence:
Correctthephrase"(limits(37.2),acresdesigncapacities"toread"limits(37.2acres)
ordesigncapacities."
23. Page58
Lastparagraph,1stsentence:
Inserttheword"deeper"beforethephrase"undergroundworkingsfillwithwater."
5
24. Page61
Lastparagraph,3rdsentence:
Insertthefollowingsentence"However,thisisnotlikely."afterthe3rdsentencewhich
endswith"ifinflowsaregreatenough"
25. Page64
Firstparagraphunder"SOILSANDRECLAMATION"heading,4thsentence:
Movetheabbreviation"DEQ"fromtheendofthesentenceandinsertitbeforetheword
"salvageability."
26. Page68
Firstparagraph,1stsentence:
Deletethephrase"forconvoys."
27. Page68
Secondparagraph:
Addthefollowingparagraphsafterthesecondparagraph, butbeforethe "Mitigated
Project"header:
"Ifanumberoflargevehiclessuchasore-haulingtrucksorsupplyvehicleswerestopped
betweentherailroadtracksandthehighway,thepotentialexistsforacoupleofunsafesituations.
Thefirstisthatifthelineoftrafficwaitingtoenterthehighwaywaslongenoughtocrossthe
tracks,itwouldincreasethepotentialforatrain-vehiclecollision. Thecounty'srestrictionon
theuseofconvoyswouldhelptoreducethepotentialforthistypeofproblem. Thesecond
situationoccurswhenalargenumberofvehiclesincludingtheoretruckarestoppedonthe
highwaywaitingtoenterIndianCreekRoad;thedelaysmaybedueeithertoatrainoroncoming
trafficnotallowingtraffictoturn. Thiswouldcreateasafetyhazardasvehiclesinthesamelane
oftravelonhighways287/12mightbeforcedacrossthecenterlinetocontinueathighway
speeds.
Other impacts to theflow oftrafficonthehighway would result from thespeed
differentialbetweentheore-haulingtrucksenteringthetrafficstreamandthetravellingpublic
alreadyathighwayspeed. Asthefullyloadedtrucksbegintheirclimbfromastoppedposition,
itwouldtakeseveralmilesbeforetheycouldreachhighwayspeeds. Thespeeddifferential
betweenthetrucksandotherhighwayuserswouldcreatetraveldelayandmayimpacttraffic
safetyasdriversoffastermovingvehiclesmightelecttopasstheslowermovingtrucks. The
compounded effectofaconvoyenteringthehighwayhasbeeneliminated bythecounty's
restrictionagainstPegasus'proposeduseofconvoysalongIndianCreekRoad.
6
"
28. Page69
Firstparagraph:
Add the following paragraph after the 1st paragraph but before the heading,
AESTHETICS:
"Impactsresultingfromthespeeddifferentialofslowmovingore-haulingtrucksand
highwaytrafficalreadyathighwayspeedwouldbeminimizedbyrestrictingthemovementofthe
trucksduringthepeaktraffictimeandtherateatwhichthetruckenteredandtraveledalongthe
highway. Restrictingtrucktrafficbetweenbetween4:00p.m.and6:00p.m.duringthemonths
ofJuneto September couldhelp minimizethepotential fortraffic accidents dueto speed
differentials. Thispotentialhazardwouldbefurtherminimizedbykeepingtheorehaulingtrucks
aminimumof10minutesaparttoallowforsaferpassingbyfastertraffic."
29. Page69
Firstparagraphunder"AESTHETIC"heading,1stsentence:
Addthefollowingphraseafterthephrase"underalternatives": "giventhereclamation
measuresexplainedinChapter2underReclamation/MineClosure.
30. Page71
Paragraphunder"CULTURALRESOURCES"heading:
Addthefollowingparagraphaftertheparagraph:
"PegasuswouldlimittheamountofblastingrequiredtowidentheroadwithinIndian
CreekCanyonanddoasmuchworkaspossiblewithequipment. Afieldinspectionalongthe
roadindicatedthatareasneedingblastingwerenotinthedirectvicinityofeithertheMcCormick
LiveryandFeedStableSignorthehistoricflumewhichareonBLMlands. However,Pegasus
wouldneedtocontactBLMimmediatelyofanyroadwideningactivitieswhichthreatenedthe
sites,sothatBLMcouldinitiatetheSection106process. Theactivitieswouldhavetobehalted
untilBLMdeterminedthereweresufficientadditionprotectivemeasures inplaceoritwas
determinedacceptabletoproceedduringtheSection106consultation. Thesemeasureswould
allowprotectionforbothsites."
31. Page75
Lastparagraph:
Insertthefollowingsentenceafterthe1stsentence:"Trafficsafetyimpactsrelatedtothe
powerlineconstructionwouldbemitigatedbyrequiringpilotcarsforconstructionequipment
(BLM1996)."
CHAPTER8
32. Addthefollowingabbreviations:
DOT MontanaDepartmentofTransportation
MTMI MontanaTunnelsMining,Inc.
7
CHAPTER9
33. Addthefollowingreferencestothischapter:
BureauofLandManagement,1995b.FinalEnvironmentalAssessmentfortheContinentalLime,
Inc.ProposedMineExpansionPlanintheLimestoneHills,January. EANo.MT-075-
95-07.
toDiamondH,il1l99M6i.neE,nvJiarnounamreynt29a.lAEssAesNsom.enMtTf-o0r7t5h-e9M5o-n2t5a.naPowerCo.100kVLine
MontanaDepartmentofTransportation,1996. MemorandumfromSandraS.Straehl,Montana
DepartmentofTransportation,toKathyJohnson,MontanaDepartmentofEnvironmental
Quality,March11. Memotransmitsagency'scommentsontheDiamondHilldraftEIS
andprovidesadditional informationabouttheexistingtrafficsituationandpotential
impacts.
PegasusGoldCorporation, 1996b. LetterfromConstanceM. Cole,PegasusGoldCorp.,to
SandraOlsen,MontanaDepartmentofEnvironmentalQuality,March11. Lettersubmits
company's comments on theDiamond Hill draft EIS and provides a copy ofthe
MemorandumofAgreementwithBroadwaterCounty.
CountyCommi,s1s9i9o6nce.rsL,eMttaerrcfhro1m8.MikLeettMearslcoowmsmkiit,tiPneggatsouasvoGiodlidngCodrips.t,urtboinBgrotahdewsaitgensr
andwoodenflumeinIndianCreekCanyonduringroadwork.
Olsen,Monta,n1a99D6edp.artLemtetnetrforfoEmnvJiorhonnmSe.ntFiatlzpQautarliictky,,PMeagarscuhs1G9o.ldLeCtotrepr.,retsopoSnadnsdrtao
concerns submitted by Montana City Schools regardingpossibleore-haulingtraffic
throughMontanaCity.
8