hydrogeology and ground water quality at the … · unc mill site ground water history 1980s-2015...

HYDROGEOLOGYANDGROUNDWATERQUALITYATTHEUNITEDNUCLEARCORPORATIONURANIUMMILL,CHURCKROCK,NEWMEXICO

EarleC.DixonEnvironmentalScienEst

TsaliAssociates

UNCMillSite–RegulatorySeKng•  NuclearRegulatoryCommission(NRC):Responsibleforallonsite&beneaththefacility,insidepropertyboundarythroughlicense.

•  EnvironmentalProtecEonAgency(EPA)Region6:Responsibleforoffsitegroundwatercleanup&exposurethroughCERCLA-NPL&1988ROD.

•  NRC&EPAworktogetherunderanMOUtocleanupthesitetoUMTRCA&RODstandards.

•  NMED&NavajoNaEonparEcipateindocumentreview-comment&decisionmaking-comment.

•  Sitebecamemorecomplicatedw/planneddisposalofminewasteatUNCcentral&northdisposalponds.

EPARegion6,Dallas:UNCMillSite

EPARegion9,SanFrancisco:NECRMineSite

Southwestalvm(SWA)

Zone3,(Z3)

Zone1,(Z1)

MonitoringwelllocaEonmap2015,UNCMill,ChurchRock,NM

ChurchRockmineswaterdischargerates(gpm),

1968-1986

Zone3monitoringwellSWLdecline

projecEontoboeomofscreenelevaEon

2012GroundWaterFlowModelZone3seepage

Projectedmonitoringwelldrydates,Zone3,UNCMillSite,ChurchRock,NM

UNCMillSiteGroundWaterHistory1980s-2015(1of4)

•  1968:NECRstartsminingoperaEons,dewatering,1977UNCstartsmillingoperaEons,seepageproblemsby1981.

•  1979:Southtailingspondbreach.•  1980-1988:controversialperiodofinvesEgaEons,lawsuits,hearings,regulatorchange,&miningindustrydecline&closure.

•  1983:UNCMillSiteplacedonNaEonalPriorityList(NPL)orSuperfundforgrdw.

UNCMillSiteGroundWaterHistory1980s-2015(2of4)

•  1988RecordofDecision(ROD):selectedAlternaEve3–pumping&evaporaEonw/mistersfor3aquiferunitstostandards.

•  ROD-onetableofgroundwatercleanupstandardsforthreedifferentaquiferunits.

•  CleanupstandardsareacombinaEonofsitedata,laboratorydetecEonlimits,&healthrisklevels.

•  Remedydidnotachievestandards&pumpflowratesbelowEPAcriteriasoremedyshutdownby2001.UNCconEnuesZone3pumping.

UNCMillSiteGroundWaterHistory1980s-2015(3of4)

•  UNCrequestedalternaEvestopumping:technicalwaiverforstandards;insEtuEonalcontrols–nosupportfromNN,BIA,NMED.

•  2004-2006:beginformalprocesstoevaluateotherremedies&buildadecisionsupportdocumentrepositorytorevisethe1988RODcleanupstandardswhichneedrevision.

•  2006:SiteWideSupplementalFeasibilityStudy(SWSFS)beganinaphasedapproach.

UNCMillSiteGroundWaterHistory1980s-2015(4of4)

•  2008:Part1SWSFScompleted,ProUCLstaEsEcalstudyofUNCgroundwaterdatatocomputerevisedbackgroundvaluesforearlyCOCvaluesthatwereusedas1988RODstandards.

•  2010:Part2SWSFSAlternaEveremedyscreeninganalysis&costesEmateaccordingcompletedtoEPAcriteria.

•  2017:(?)Part3DetailedalternaEveremedyanalysis&costtoachieverevised/proposedvaluesforupdatedRODstandards.

PrimarygeochemicalreacEonforbufferingseepageimpactedgroundwater

Uv.HCO3CovariantRelaEonship

UNCMillSite–Status&Future•  2015:NRCapprovedAmendment52toUNCLicenseto

reviseGroundwaterProtecEonStandardsforselectmetals&radionuclidesin3hydrostraEgraphicunits.

•  2016-2017++:Part3SWSFScompleted(?)thenEPAsystemaEcallystartsrevisionprocessto1988ROD?

•  Lookingforward:UNCSiteneedstoachieveclosure&beremovedfromNPLinordertomovesitestewardshipunderUMTRCAtoDepartmentofEnergy(DOE)LegacyManagementbytransferofLicense.

•  NECRminewastetobedisposedatUNCSite&closedunderNRCLicense-neverbeendonebefore?

•  NRC,EPAs,NN,UNC-GE,&DOEworkingtogether.•  DOEwillbecomelong-termsitemanager??

The End.

Thank you.

Questions-Comments?