Remedial Action Progress 1st Quarter 2019 · capability to reinject, so the system has operated at a higher capacity using injection, release to Playa 1, and shutdown of P1PTS to

[Typetext]

UNCLASSIFIED

PANTEXQUARTERLYPROGRESSREPORT

RemedialActionProgress

1stQuarter2019

InsupportofHazardousWastePermit#50284and

PantexPlantInteragencyAgreement

June2019

PantexPlant

FM2373andU.S.Highway60

P.O.Box30030

Amarillo,TX79120

CERTIFICATION STATEMENT

1st Quarter 2019 Remedial Action Progress ReportPantex Plant, June 2019

I certify under penalty of law that this document and all attachments were prepared under mydirection or supervision according to a system designed to assure that qualified personnel properlygather and evaluate the information submitted. Based on my inquiry of the person or persons whomanage the system, or those persons directly responsible for gathering the information, theinformation submitted is, to the best of my knowledge and belief, true, accurate, and complete. I amaware that there are significant penalties for submitting false information, including the possibilityof fine and imprisonment for knowing violations.

2 -

)es C. Cantwell DateVDirector

Environment, Safety and HealthConsolidated Nuclear Security, LLC

Quarterly Progress Report1st Quarter 2019

in Support of Hazardous Waste Permit #50284and Pantex Plant Interagency Agreement

for the Pantex Plant, Amarillo, TexasMarch 2019

Prepared byConsolidated Nuclear Security, LLC

Management and Operating Contractorfor the

Pantex Plant and Y-12 National Security Complexunder Contract No. DE-NA000 1942

with theU.S. Department of Energy

National Nuclear Security Administration

In accordance with 30 TAC §335.553 (g], this report has been prepared and sealed by anappropriately qualified licensed professional engineer or licensed professional geoscientist.

ToflyBiggs’ Date’Licensed Professional Geologist No. 2693

2693 Environmental ProjectscENsf Consolidated Nuclear Security, LLC

Project Team: Tony BiggsMichelle Jarrett

LISTOFACRONYMS

µg/L microgramsperliterCatOX catalyticoxidationCOC contaminantofconcernCr(VI) hexavalentchromiumDCE dichloroetheneDHC Dehalococcoidesspp.DNT4A 4‐amino‐2,6‐dinitrotolueneDO dissolvedoxygenEVO emulsifiedvegetableoilFGZ fine‐grainedzoneFY fiscalyearFYR five‐yearreviewGWPS groundwaterprotectionstandardHE highexplosiveHW‐50284 HazardousWastePermit#50284IAG InteragencyAgreementISPM insituperformancemonitoringISB insitubioremediationlb poundMgal milliongallonsmV millivoltsNAPL non‐aqueousphaseliquidORP oxidation‐reductionpotentialP1PTS Playa1PumpandTreatSystemPID photoionizationdetectorPQL practicalquantitationlimitRDX hexahydro‐1,3,5‐trinitro‐1,3,5‐triazineSAP samplingandanalysisplanSEPTS SoutheastPumpandTreatSystemSVE soilvaporextractionSWMU SolidWasteManagementUnitTCE trichloroetheneTHF tetrahydrofuranTNT trinitrotolueneVOC volatileorganiccompoundWWTF wastewatertreatmentfacility

11stQuarterReport,January–March2019

INTRODUCTION

ThePantexPlant,locatedintheTexasPanhandle17milesnortheastofAmarillo,hasimplementedaresponseactiontoremediateperchedgroundwaterandsoils.Twotypesofsystemshavebeeninstalledforthegroundwaterresponseaction:pumpandtreatsystemsintwoareasandinsitubioremediation(ISB)systemsintwoareas.Asoilvaporextraction(SVE)systemhasbeeninstalledtoremediatevolatileorganiccompounds(VOCs)insoilsattheBurningGroundarea.Thisquarterlyreportaddressesprogressachievedthroughimplementationoftheremedialactionsfor1stquarter2019.

Thisreportprovidesanintermediatedatasummaryforresponseactionsystemsthroughouttheyear.Moreintensivedatareportingisincludedintheannualprogressreports.Thequarterlyprogressreportsaddressthreeofthefiveevaluationsincludedintheannualprogressreports:responseactioneffectiveness,uncertaintymanagement,andearlydetection.ThereportsproviderequiredinformationfromHazardousWastePermit#50284(HW‐50284)CPTableVIIandthePantexInteragencyAgreement(IAG).

Mapsoftheplumes,remedialactionsystems,samplinglocations,andsystemwellsareprovidedinAppendixA.GraphsofoperationandflowratesforthepumpandtreatsystemsareprovidedinAppendixB.GraphsofimportantparametersfortheISBtreatmentzoneanddowngradientwellsareprovidedinAppendixC.

RESPONSEACTIONEFFECTIVENESS

Thisquarterlyprogressreportfocusesonspecificcriteriaforthepumpandtreatsystems,ISBsystems,andasmall‐scaleSVEsystem.Systemoperation,massremoval,andevaluationofeffluentinreferencetoestablishedoperationalgoalsarereportedforthepumpandtreatsystems.FortheISBsystems,thisreportevaluatesgeochemicalconditionsandavailabilityoffoodsourceinthetreatmentzoneandreductionofconcentrationsofcontaminantsofconcern(COCs)indowngradientperformancemonitoringwellstoevaluatewhetherthetreatmentzoneisworkingeffectively.Systemoperation,massremoval,andeffluentphotoionizationdetector(PID)readingsareevaluatedfortheSVEsystem.

2 PantexPlantQuarterlyProgressReport

PUMPANDTREATSYSTEMS

ThegroundwaterremedialactionatthePantexPlantincludestwopumpandtreatsystems:SoutheastPumpandTreatSystem(SEPTS)andPlaya1PumpandTreatSystem(P1PTS).Thepumpandtreatsystemsaredesignedtoextractwaterandremovecontaminantmassfromthewaterbeforetheeffluentisbeneficiallyusedbythewastewatertreatmentfacility(WWTF)andirrigationsystem,forgeneralPlantneeds,orforamendmentinjectionsattheISBsystems.Thesystemswerealsodesignedtoremovewaterfromtheperchedaquifertoreducesaturatedthickness.Thisreductioninsaturatedthicknessreducesmigrationofcontaminantsbothverticallyandhorizontallysothatnaturalbreakdownprocessescanoccurovertime.ReducingmigrationprovidesprotectionfortheunderlyingHighPlainsAquifer(alsoknownasandreferredtohereinastheOgallalaAquifer).SEPTShasthecapabilitytoinjectthetreatedwaterbackintotheperchedaquiferwhenbeneficialuseisnotpossible.Operationalprioritiesforthepumpandtreatsystemsemphasizebeneficialuseofwater.

SEPTSandP1PTSoperationandthroughputcontinuedtobeimpactedinthe1stquarterbyafilterbankbreakattheirrigationsystemthatoccurredinlateJune2017.Duetotheseverityofthebreak,engineeringevaluation,contracting,andmajorrepairswererequiredtorestoretheirrigationsystem.RepairswerecompletedinMay2019,withstartuptestingbeginning.Meanwhile,PantexcontinuestoreleaseallWWTFwatertoPlaya1.TheflowtoPlaya1isrestrictedbypermit,soflowfromthesystemsmustalsoberestricteduntiltheirrigationsystemisrepaired.CurrentandfutureoperationswillbeimpairedbytherestrictedflowtotheWWTF.SEPTShasthecapabilitytoreinject,sothesystemhasoperatedatahighercapacityusinginjection,releasetoPlaya1,andshutdownofP1PTStoallowfulltreatmentatthesystemsinceJanuary14,2019.AfterJanuary,P1PTSwasonlyoperatedoneweekpermonthtoensurecontinuedoperabilityofthesystem.WhenP1PTSwasoperating,SEPTSoperatedatalowerflow,withtreatedwaterinjected.AsmallamountofwaterwasbeneficiallyusedattheSoutheastISBextensionforinjectionandforreseedingofareaswherebuildingswereremoved.

Thesystemswereoperatedtooptimizecaptureofwaterandmassinthesoutheastareaduring1stquarter2019.Forthisreason,P1PTSthroughputwaslowerthantheusualgoalof90%.WiththeincreasedflowafterJanuary14,SEPTSthroughputwasnearthe90%goal.GraphsofmonthlyoperationandthroughputareincludedinAppendixB.About97%ofthetreatedwaterwaseither

Pump and Treat System

1st Quarter 2019 Operation

Playa 1 Pump and Treat System (P1PTS)

Days Operated 30

% Operation Time 30%

Volume Water Treated (Mgal) 5.7

HE Mass Removal (lbs) 2.4

Beneficial Use of Water 0

Southeast Pump and Treat System (SEPTS)

Days Operated 90

% Operation Time 99%

Volume Water Treated (Mgal) 32.9

HE Mass Removal (lbs) 89.8

Chromium Mass Removal (lbs) 21.6

Beneficial Use of Water 3.3%

Value below operational goals


releasedtoPlaya1orinjectedintoperchedinjectionwells.Whenbothsystemsareoperating,PantexhasfocusedonoperatingthehighestprioritywellsatSEPTStocontinuecaptureofwateralongtheFM2373fencelineandalongthehighestplumeconcentrationstothesouthonTexasTechproperty.WellsonthenorthernfencelinealongFM2373aredemonstratingimpactfromthereductioninwaterlevels,andcontinuedissueswithpumpingareexpected.MostwellswereoperatingatP1PTS.

P1PTSprimarilytreatsRDXandSEPTSprimarilytreatsRDXandhexavalentchromium[Cr(VI)].Figures1and2providemassremovalinformationforRDXandotherhighexplosives(HEs)andCr(VI)forthe1stquarter,aswellastotalssincesystemstartup.ConcentrationsnearPlaya1aremuchlowerduetodecliningsourceconcentrations;therefore,massremovalismuchloweratP1PTS.TheprimarygoalofP1PTSiswaterremovaltodecreasesaturatedthicknessandremovetheheadpressurethatpushesgroundwaterouthorizontally,withmassremovalasasecondarygoal.Overall,thesystemshaveremovedover14,600lbsofofHEandchromiumcontaminantsfromperchedgroundwatersinceoperationsbegan.

Thetotalrecoveryandtreatmentfrombothsystemssincestartuphasbeencalculatedatabout2.7billiongallons.BecauseSEPTSwasoriginallydesignedtoinjecttreatedwater,allofthetreatedwaterpriorto2005wasinjected.However,asignificantvolumeoftreatedwaterhasbeenusedbeneficiallysince2005,withatotalofover1.7billiongallonsoftreatedwaterbeneficiallyusedsincestartupoftheirrigationsystem.TherecoveryandbeneficialusetotalsarepresentedinFigure3.CurrentlythesystemsarereleasingwatertotheWWTFandthentoPlaya1ortoinjectionwells,somostofthetreatedwaterisnotcurrentlybeneficiallyused.

Figure1.P1PTSMassRemoval

Figure2.SEPTSMassRemoval

Figure3.SystemRecoveryandUse


EvaluationofeffluentdatafrombothsystemsindicatesthatallCOCsweretreatedtolevelsbelowthegroundwaterprotectionstandards(GWPS).

WhilePantexcontinuestodevelopotheralternativesfortheuseorreleaseoftreatedwater,PantexrevisedtheoperationofP1PTSandSEPTS.Evaluationofplumedataandwaterlevelsduring1stquarter2019indicatedthatfulloperationofSEPTSwouldbebeneficialforcaptureofmassandwaterfluxtothesoutheast.Therefore,whiletheirrigationsystemremainsdownandflowsfromthesystemsmustbelimited,PantexwillonlyoperateP1PTSduringoneweekofeachmonthtoensurecontinuedoperabilityofthesystemandtoallowfulloperationoftheSEPTS.WhenP1PTSisoperating,SEPTSwilloperatewithreducedflowstolimitinjection.

PantexiscurrentlyplanningforotherirrigationalternativesonthepropertyeastofFM2373toprovideadditionallong‐termuseofthetreatmentsystemwater.Fundinghasbeenrequestedinfiscalyear(FY)2021todesignandconstructtheinfrastructureforirrigationoflandeastofFM2373usingcenterpivot.PantexhasidentifiedfundingtodesignandconstructthreenewperchedinjectionwellstotheeastofPlaya2,northwestoftheZone11ISB.Contractingforthedesignandconstructionoftheinjectionwellsandinfrastructureisunderway.Thesenewinjectionwellswillprovideaconsistentoutletforaportionofthetreatedwaterwhenirrigationisnotanavailablemethodforbeneficialuseofthetreatedwater.Thesewellswillalsoprovideamethodtoinjectthetreatedwaterwithoutaffectingmovementandcaptureofplumesinthesoutheastarea.

Pantexisalsoevaluatingashort‐termsolutiontomorefullyoperatebothsystems.Therearesomesmallareasthatcouldbeirrigatedusingwatercannonsthatcouldbeconnectedtoexistingtreatedwatersupplylinesthatwouldnotbeco‐mingledwithPantexwastewater.

PantexhasnotobservedanycurrentissueswiththemovementofplumesduetothecontinuedinjectionofwaterfromtheSEPTS.However,pastissueswithpushingplumesinanotherdirectionwereobservedwhenprolongedinjectionoccurredatawell.Changesintheplumehavebeenobserved,butchangesappeartoberelatedtothereducedextractionfromthesystem.PantexexpectstocontinueinjectionatSEPTSinthenearfuture,asrepairstothecurrentirrigationsystemwillbelimitedtotwo100‐acreplots.OncethethreenewinjectionwellsareinstalledandanewirrigationsystemeastofFM2373isdesignedandconstructed,thesystemswillbeabletoconsistentlyoperateatornearcapacity.

ISBSYSTEMS

ThreeISBsystems(Zone11ISB,SoutheastISB,andSoutheastISBExtension)areinstalledatPantex.Thesystemsaredesignedwithcloselyspacedwellstosetupatreatmentzoneinareasoftheperchedgroundwaterwherepumpandtreatmaynotbeaseffective,orwheretheareaissensitivetoverticalmigrationofCOCstotheOgallalaAquifer.AmendmentisinjectedintothesesystemstoestablishtreatmentzoneswhereCOCsaredegraded.MonitoringwellswereinstalleddowngradientofthetreatmentzonetomonitorwhetherthesystemiseffectivelydegradingtheCOCs(seemapsinAppendixA).TheprimaryCOCsattheZone11ISBaretrichloroethene(TCE)andperchlorate.TheprimaryCOCsattheSoutheastISBareRDXandhexavalentchromium.TheprimaryCOCattheSoutheastISBExtensionisRDX.


NotreatmentdataarepresentedinthisreportfortheSoutheastISBExtension,asthesystemwasinstalledinlate2017andinjectioncompletedinFebruary2019.Treatmentzonedatawillbecollectedin2ndquarter2019.

Forthetreatmentzonewells,thisreportevaluateswhethertheconditionsarepresenttodegradetheCOCsineacharea,andevaluatesthepresenceofacontinuedfoodsourceforthemicrobialreductionofCOCs(seeTable1).

DowngradientmonitoringwellsareevaluatedtodetermineiftheISBsystemsareeffectiveindegradingtheCOCsandanybreakdownproductsoftheCOCs.Graphsofdatafromsampledtreatmentzonewellsanddowngradientinsituperformancemonitoring(ISPM)wellsareincludedinAppendixC.Table1alsosummarizesISBsystemperformance.

ZONE11ISB

InstallationoftheZone11ISBremedialactionwascompletedin2009,andanexpansionwascompletedinearly2015(seeAppendixAmaps).Nineinjectioneventshavebeencompletedatthecurrentsystem,withthefirstinjectioneventoccurringintheexpansionzonein2015.TheninthinjectioneventfortheISBwascompletedinOctober2018,withonlytheexpansionareainjected.Asdocumentedinthe2016AnnualProgressReport(Pantex,2017),dataindicatethatmovingtoa

Table1.ISBSystemPerformance

TreatmentZoneWells DowngradientPerformanceMonitoringWells

SystemReducingConditions

FoodSourceAvailable

PrimaryCOCs

Reduced? COCs<GWPS?

DegradationProductsof

COCsReduced?Zone11ISB Verymildto

strongYes Yes Perchloratein

8of9wellsTCEin6of9wells

No1

SoutheastISB Mildtostrong

Yes Yes RDXin1of2wellsCr(VI)in2of2wells2

No3

Mildconditions=oxidation‐reductionpotential(ORP)of0to‐50millivolts(mV)Strongconditions=ORP<‐100mVandsulfateandnitratereduced,indicatingthatconditionsarepresentforreductivedechlorination.1 cis‐1,2‐Dichloroethene(DCE)concentrationsremainaboveGWPSinthreedowngradientwells,whilevinylchlorideconcentrations(finalbreakdowncompound)remainatlowconcentrationsornotdetected.Duringthe1stquarter,cis‐1,2‐dichloroetheneconcentrationswereneartheGWPS,indicatingthatthesystemisnearingtreatmenttotheGWPS.Pantexbioaugmentedtheoriginalwellsonthewestsideofthesystemduringtheseventhinjectioneventin2015.Pantexiscontinuingtomonitortheeffectivenessofthebioaugmentation.

2 Pantexformerlysampledfourdowngradientwellsatthissystem.However,oneofthewells(PTX06‐1123)continuestodemonstratelowwaterconditionsandcannolongerbesampled.ThiswellhaddemonstratedcompletetreatmentofHEsandCr(VI)fromOctober2012toAugust2015.PTX06‐1037hasbeensampledforlimitedanalytes,butin1stquarter2018waterlevelshaddroppedsufficientlythatsamplescannolongerbecollected.PTX06‐1037demonstratedtreatmentfrom10/19/2011through9/18/2018.

3 PTX06‐1153iscurrentlydemonstratingpartialtreatment.Therefore,thedegradationproductsofRDXarenowobservedabovetheGWPS.


two‐yearinjectionfrequencyintheoriginalportionofthesystemisappropriateforfutureinjectionswithemulsifiedvegetableoil(EVO).However,aspresentedinthe4thquarter2018ProgressReport,Pantexplanstomoveprimarilytotheuseofamoresolublecarbonsource,molasses,asstudiesconductedattheZone11ISBin2018indicatedthatmolassesdistributedbetweeninjectionwellsatamuchhigherconcentrationthanEVO.MorefrequentinjectionsareanticipatedformolassesandhavebeenplannedatleastannuallyfortheZone11ISBduetotheneedtocontinuedeepreducingconditions.Pantexwillcontinuetoevaluatethesystemforthetimingofinjectionswiththemolasses.PantexwillalsocontinuetoevaluatetheexpansionareatodeterminetheappropriatetimingorneedforbioaugmentationwithDehalococcoidesspp.(DHC)topotentiallyboostthetreatmentefficiencyforTCE.TheentiresystemwillbeinjectedbeginningMay2019.

TheZone11ISBhasawell‐establishedtreatmentzoneintheoriginalportionofthesystem,whereinjectionhasoccurredsince2009.Theexpansionarea(seemapinAppendixA)hasreceivedthreeinjections,sodeeperreducingconditionsarelikelyestablishedattheinjectionwells.Deepreducingconditionshavenotbeenfullydemonstratedatallofthetreatmentzonemonitorwellslocatedbetweentheinjectionwellsintheexpansionarea.Themolassesinjectionisexpectedtoimproveconditionsbetweeninjectionwells.Mostwellsdowngradientofthesystemhaveindicatedarrivaloftreatedwater.However,PTX06‐1175isintheexpansionareaandfartherdowngradientthanotherwellsinthatarea,soisslowertorespondduetotheincreasedtraveldistancetothewell.

Evaluationofdatainthetreatmentzoneindicatesverymildtostrongreducingconditions(ORPrangingfrom40to‐138andsulfatefromnon‐detectto25µg/L)acrosstheZone11ISB.Monitoredconditionsindicatethatsulfatewasreducedinnineoftwelvewellsinsidethetreatmentzone,indicatingdeeperreducingconditionsinthoseareas.Thethreewellsthatdonothavedeepreducingconditionsarenon‐injectedmonitoringwells.Twoofthosewellsareintheoriginalpartofthesystemthatwasnotinjectedin2018.Conditionsimprovedatmostofthenon‐injectedwellsintheexpansionarea,followingthemolasses/EVOinjectionin2018.PTX06‐1164,afirst‐rowmonitorwell,hadconditionsimprovefollowinginjectionbutrecentdataindicateconditionsarereversing.However,methaneconcentrationswerehighinmosttreatmentzonewellsthisquarter,indicatingthatstrongreducingconditionscontinuetooccurinmanyareas.TCEcontinuestobereducedtocis‐1,2‐dichloroethene(DCE),withTCEconcentrationsbelowGWPSineightmonitorwellsinsideofthetreatmentzoneandcis‐1,2‐DCEpresentatconcentrationsbelowtheGWPSinnineofthetwelvemonitorwells.ThepresenceofTCEandcis‐1,2‐DCEcontinuestoindicatepartialtreatmentinthenon‐injectedtreatmentzonewells,asconcentrationstendtobehigherinthenon‐injectedwells.WhengreateramountsofTCEandcis‐1,2‐DCEarebeingdegraded,etheneandvinylchlorideareexpectedtobedetected.Vinylchloridewasdetectedintwowellsinsidethetreatmentzone,butethenewasnotdetectedatanywells.ThesevinylchlorideandetheneresultsindicatethatalimitedamountofTCEisbeingcompletelydegradedinsomeareasofthetreatmentzone.WhenTCEconcentrationsinsidethetreatmentzonearelow(<300µg/L),theselowdegradationratesmaybeenoughtotreatTCEanditsbreakdownproductstoGWPS.UpgradientdatastillindicateTCEconcentrationsperiodicallyfluctuatingabove300µg/L,withaconcentrationof1500µg/Lindicatedatanupgradientmonitoringwellinlate2018.


PantexevaluatesperformanceatninedowngradientISPMwellsfortheZone11ISB,includingthewellsintheexpansionarea.EightofthesewellshaveperchlorateconcentrationsbelowtheGWPS.PTX06‐1148,whichisfartherdowngradient,hasbeenslowertorespondduetoexpectedlongertraveltimes;however,dataindicateadecreasingtrendwithconcentrationsneartheGWPS.TCEconcentrationsarebelowtheGWPSinsixofnineISPMwells.ThefirstbreakdownproductofTCE,cis‐1,2‐DCEwasdetectedabovetheGWPSinthreedowngradientwells,PTX06‐1155,PTX06‐1173,andPTX06‐1175.Wherecis‐1,2‐DCEishigh,TCEisbelowtheGWPS.WhereTCEconcentrationsremainaboveGWPSatPTX06‐1175andPTX06‐1150,thereislittleornocis‐1,2‐DCEindicatingthatreducingconditionsarenotconducivetotreatmentorthattreatmentisslowertoreachthedowngradientwell.ConcentrationsatPTX06‐1173areneartheGWPS.However,dataindicatethatduetotreatment,concentrationsofTCEanditsbreakdownproductsareveryclosetomeetingtheGWPSintreatedwaterfromtheoriginalportionofthesystem.TheonlydowngradientwellthatisnotdemonstratingstrongtreatmentisPTX06‐1175,downgradientofthenewerexpandedareaofthesystem.

TwoformerISBinjectionwells(PTX06‐ISB079andPTX06‐ISB082)arenowmonitoredtoevaluateconditionsontheperchlorate(eastern)sideoftheISB,inthesecondrowofinjectionwells.Pantexwillnolongerinjectintothesecondrowofwells,andwillevaluatethesewellstoensurethattreatmentcontinuesontheperchloratesideoftheISB.Additionally,theresultsforupgradientwellPTX06‐1127indicatethatTCEisincreasingaboveGWPSontheeasternsideoftheISB,sotreatmentoftheTCEwillalsobeevaluatedtodetermineifchangesinthesystemoperationwillberequired.Currently,perchlorateandthelowconcentrationsofTCEthatoccurontheeasternsidearetreatedtonon‐detect.NodegradationproductsofTCEweredetected.

Althoughthereareareasinthetreatmentzonethatindicatemildreducingconditions,thedowngradientdataindicatethattreatmentiseffectivelyreducingcontaminantsandriskacrosstheZone11ISB.ThemildconditionsatPTX06‐1170andPTX06‐ISB075indicateagreaterlossofreducingconditionsinthatareaoftheISBandpossiblehigherconcentrationsofTCEmovingthroughthesystem.FuturedowngradientCOCconcentrationsmayincreaseaftertheimpactedwatermovesthroughthesystem.

PantexbeganrehabilitationofwellsinMarch2019andinjectionbeganinMay2019.Duetoverymildconditionsthatoccurinthenewtreatmentzonewellsintheexpansionarea,Pantexwillcontinuetoevaluatedatatodeterminetheappropriatetimingandneedforbioaugmentation.

Duetoproblemswithpluggingofthewells,Pantexhasmovedtoinjectionofmolassesonly,asrecommendedinthe4thquarter2018report.Pantexhasalreadyencounteredinjectionissuesataportionofthewellsintheexpansionareaeventhoughthe2018injectioneventwasonlythethirdinjectioneventforthatareaoftheISB.During3rdquarter2018,adoseresponsestudywasperformedtoevaluatethearrivalofthecarbonatnon‐injectedtreatmentzonemonitoringwellslocatedbetweeninjectionwells.Thestudyindicatesthatthemoresolublecarboniswidelydistributedathigherconcentrationsandthatlargervolumesofwater/amendmentinjectionusingsolublecarbonshouldimprovedistributionandreducingconditionsbetweenthewells.Dataindicatethattheconditionsbetweenwellshasgenerallyimprovedintheexpansionarea.Pantex


willcontinuetoevaluatethedataandmakeappropriaterecommendationsfortreatmentintheupcomingprogressreports.

SOUTHEASTISB

TheSoutheastISBwasinstalledin2007.Sixinjectioneventshavebeencompletedatthissystem.TheSoutheastISBcontinuestodemonstratedecliningwaterlevelsatthesystem;asaresult,only50%ofthesystemwasinjectedduring2016.Adiscussionoftheinjectionandissuesencounteredisprovidedinthe2016AnnualProgressReport.BasedonreviewofsystemdataandISBPilotStudydata,PantexrecommendedwaitingthreeyearsforthenextinjectionintheSoutheastISB.Thatinjectioneventisscheduledforlaterin2019.RehabilitationofwellswillbegininJuly.Asrecommendedinthe2018AnnualProgressReport,PantexplanstousemolassesonlyforthenextfewinjectioneventstoimprovedistributionofamendmenttherebyimprovingreducingconditionsattheISBs.Pantexscheduledinjectionatthissystemin2021duetotheuseofmolassesonlyduringthe2019injection.

Duetolowwaterlevelsordryconditionsinwells,onlyfourofeighttreatmentzonemonitoringwellsweresampledin1stquarter.EvaluationoftreatmentzonedataindicatesthatmildtodeepreducingconditionsarepresentfortreatmentofHEsandhexavalentchromium.ORPisbetween‐7mVand‐98mVandsulfateisreducedtovalueslessthan2µg/Lintwowells.Twowells(PTX06‐ISB046andPTX06‐ISB048)indicatethatsulfateisbeginningtorebound,withconcentrationsat4and7µg/L.However,thedatacontinuetoindicatethatreducingconditionsarepresentforcontinuedreductionofHEsandhexavalentchromium.Totalorganiccarbonresultsindicatethatacontinuedfoodsourceisavailabletomaintainthereducingconditions,althoughTOChasnowdeclinedtolessthan200mg/Latthewellsthatdemonstratereboundingconditions.AllCOCswerenon‐detectinthesampledtreatmentzonewells.

Fourdowngradientwellshavehistoricallybeensampledatthissystem.OneoftheclosestdowngradientmonitoringwellsfortheSoutheastISB,PTX06‐1154,demonstratesreductionofRDX,RDXdegradationproducts,andhexavalentchromium,withallCOCsnon‐detect.PTX06‐1123haddemonstratedCOCconcentrationsbelowtheGWPS;however,thiswellhasnotbeensampledsinceAugust2015duetoinsufficientwaterinthewell.PTX06‐1037alsodemonstratedtreatmentfromOctober2011throughSeptember2018.LimitedsamplinghasoccurredatthiswellsinceNovember2017duetodecliningwaterlevels.Waterlevelshavecontinuedtodeclineandsamplingcouldnotbeconductedatthiswellduring1stquarter.PTX06‐1153continuestoexhibitRDXconcentrationsabovetheGWPS,buthexavalentchromiumconcentrationsremainbelowtheGWPS.Duringthe1stquarter,thiswellcontinuedtodemonstratesignsofpartialtreatment.BreakdownproductsofRDXweredetectedatconcentrationsabovetheGWPS(rangingfrom14.8to17.9µg/L).Upgradientdrywellswereinjectedin2013and2015inanattempttoaffectthiswell.ItispossiblethatthoseinjectionswereslowtorespondatthislocationandmayonlybepartiallyaffectingthewaterthatcontinuestomoveintoPTX06‐1153.Aswithotherlocations,waterlevelsatthiswellcontinuetodecline.PantexwillcontinuetomonitorPTX06‐1153forcontaminantconcentrationsandwaterlevelsovertime.ItisexpectedthatinjectionwithmolasseswillimprovetreatmentconditionsandaffectPTX06‐1153inthefuture.


Figure4.SVEMassRemoval

ManyoftheinjectionandperformancemonitoringwellsindicatevariablewaterconditionsattheSoutheastISB.TwoSoutheastISBperformancemonitoringwells(oneupgradientandonefartherdowngradient)remaindryandcannotbesampled.PTX06‐1123andPTX06‐1037,downgradientperformancemonitoringwells,arenolongersampled.Theremainingtwodowngradientwellsdemonstratedecliningwaterlevels,withonlyPTX06‐1153containingmorethan4ftofwaterabovethebottomofscreen.Onlyfourofeightmonitoringwellsinthetreatmentzonecouldbesampledinthe1stquarterduetoinsufficientwater.Injectionwascompletedatonly50%oftheinjectionwellsduringthe2016injectioneventduetodryorlowwater(<1ft)conditionsinthewells.TheinabilitytosampleorinjectintothesewellsisexpectedtopersistwithcontinuedupgradientremovalofwaterbytheSEPTS.EvaluationofdataindicatesthatmostwellsintheSoutheastISBwillnotcontainappreciablewaterby2022.Pantexplanstoinjectthesystemin2021duetotheuseofmolasses,butfurtherinjectionsmaybelimitedorunnecessary.

SOUTHEASTISBEXTENSION

TheSoutheastISBExtensionwasinstalledin2017asanextensionofthechosenremedyforthesoutheastperchedgroundwater.Oneinjectioneventhasbeencompletedforthissystem,withtheinjectioncompletedinFebruary2019.Duetothesuccesswithdistributionofamoresolublecarbon(molasses)andthelongturnaroundneededtoorderEVO,PantexbeganinjectionattheSoutheastISBExtensionusingonlysolublecarbon(molasses),asrecommendedinthe3rdQuarterProgressReport.Pantexplanstocontinueinjectionatthissystemusingonlymolassestoimprovedistributionandtreatment.BecausethissystemhasnotbeentreatedwithEVO,injectionshavebeenscheduledatapproximatelysixmonths.Pantexisplanningtoinjectthissystemagain,startinginAugust.

Baselinedatawerepresentedinthe1stQuarter2018ProgressReport.Post‐injectiondatawillbecollectedin2ndand3rdquarter2019andpresentedinthosequarterlyreports.

BURNINGGROUNDSVE

TheBurningGroundSVEsystembeganoperationin2002asalarge‐scalecatalyticoxidizer(CatOX)system.DuetoalargereductioninVOCconcentrations,asmallCatOXsystemhasbeenoperatingattheBurningGroundSVEsystemsinceApril2012.Thissmall‐scalesystemfocusesontreatingresidualnon‐aqueousphaseliquid(NAPL)andsoilgasatasingleextractionwell(SVE‐S‐20)nearthesourcearea.

Thesystemwasintermittentlyoperatedduringthe1stquarter.Itwasshutdownduetolowairflow,lowprocessflow,lowpH,andforchange‐outoftheblow‐offwatertankthathadasmallleak.Thesystemoperatedabout63%ofthequarter(about1,354hoursofoperation).Figure4showsmassremovalcalculatedforthe1stquarterandsincestartupforVOCs


contributingmorethan2%ofthetotalVOCconcentration.

Thesystemremovedabout157lbsofVOCsduring1stquarter,andhasremovedover20,600lbsofVOCssincestartup.BasedonPIDdatacollectedatthesystemeffluentport,systemdestructionefficiencywasatleast97%.Thesystemoperatedatahigherflowduetothemodificationstothesystem,withtheflowincreasedfrom32standardcubicfeetperminute(scfm)inearly2017tothecurrentlevelof44scfm.ThehourlyVOCremovalratesincreasedwiththeincreasedflowuntil1stquarter2018.Theremovalratedeclinedduring2018,buttherecentremovalrateimproved.Pantexwillcontinuetoevaluatetheeffectivenessoftheactivesystemtodeterminewhenactiveremediationmaynolongerbeeffective.

UNCERTAINTYMANAGEMENTANDEARLYDETECTION

Uncertaintymanagementandearlydetectionwellsareevaluatedtodetermineifthereareunexpectedconditionsinareaswherepreviousgroundwatercontaminationhasnotbeendetectedorconfirmed(Ogallalaandperchedaquifers),orinpreviousplumelocationswhereconcentrationshavefallenbelowGWPS,background,andthePQL(e.g.,perchedwellsattheBurningGroundandOldSewageTreatmentPlantareas).IndicatorCOCsareevaluatedattheuncertaintymanagement/earlydetectionwellsinthequarterlyreport.AmapdepictingthewellsevaluatedisincludedinAppendixA.

Reviewoftheuncertaintymanagement/earlydetectiondatacollectedduringthe1stquarterindicatesunexpectedconditionsatoneOgallalaAquiferwell(PTX06‐1056).NodetectionsexceededtheGWPSintheOgallalaAquiferuncertaintymanagement/earlydetectionwellssampledduringthe1stquarter.Therewerenounexpectedconditionsatpercheduncertaintymanagementwellsinthe1stquarter.

PTX06‐1056continuestodemonstratedetectionsof4‐amino‐2,6‐dinitrotoluene(DNT4A),abreakdownproductoftheHETNT,withtheinitialdetectionoccurringinApril2014.Sampleresultscollectedsincethattimehavebeenvariable,withvaluesslightlyexceedingthePQLsincelate2016.1,2‐Dichloroethane(DCA12)hasbeenvariablydetectedsinceAugust2015,withalldetectionsbelowthePQL.TrendsoftheseanalyteswereperformedusingMann‐Kendallstatistics;DNT4Acontinuestodemonstrateaslightincreasingtrendacrossalldata,withastabletrendacrossrecentsamples(lastfoursamples).DCA12isdemonstratinganincreasingtrendacrossalldataandnotrendacrossrecentdata.

Pantexhasproactivelyevaluatedpotentialsourcesforthecontamination.Anearbyperchedwellthatwasdrilleddeepintothefine‐grainedzone(FGZ)waspluggedtoaddressthatpotentialsource.

Summary of Unexpected Ogallala Detections, 1st Quarter 2019

Well ID Sample Date

Analyte

Measured Value (µg/L)

PQL (µg/L)

GWPS (µg/L)

PTX06‐1056 1/15/2019 4‐Amino‐2,6‐Dinitrotoluene 0.356 0.269 1.2

PTX06‐1056 1/15/2019 1,2‐Dichloroethane 0.95 1 5


Anoutsidereviewindicatedthat,basedonfateandtransportmodeling,theperchedwellwasthemostlikelysourceofthecontamination.AcementbondlogwasrunonPTX06‐1056inOctober2016todeterminethecompetencyoftheconcretesealattheFGZ.ThelogindicatesthatthesealiscompetentandthatPTX06‐1056islikelynotactingasapreferentialpathwayforcontaminationtoreachtheOgallalaAquifer.Asagreedwithregulatoryagencies,Pantexwillcontinuewithquarterlysamplingtoevaluatetrendsinthesedetections.FurtheractionswillbedeterminedbasedonresultsofsamplingandinaccordancewiththePantexGroundwaterContingencyPlan.

OTHERUNEXPECTEDCONDITIONS

Pantexroutinelyevaluatesdataastheycomeinfromthelaboratorytodetermineifdataareoff‐trend,atanall‐timehigh,orrepresentanewdetectionthatmayrequirefurthersamplingorevaluation.Throughthewellmaintenanceprogram,Pantexalsoinspectswellsatleasteveryfiveyearstoensuretheyarenotsiltinginandtoevaluatewhetherthewellremainsincontactwiththeformation.

DuringreviewoftheDecemberwaterlevelmeasurements,itwasnotedthatPTX06‐1079,locatedatthenortheastcornerofthePlant,neartheOldSewageTreatmentPlant,hadseveralfeetofwater.Thewellhadbeendrysinceitwasdrilledandtheexpectedconditionforthiswellisthatitremainsdry.FurtherevaluationofwaterlevelsinJanuaryandFebruaryindicatedthatthewaterinthewellwasvariable.Thewellislocatednearproductionwelllinesandisbelievedtobeaffectedbyleaksfromthoselines.AsamplewascollectedonMarch27,2019,toconfirmnocontaminantswerepresentinthewater.Thesampleindicatedonlythepresenceofnaturallyoccurringboron,belowtheestablishedbackgroundcriteria.PantexiscurrentlyplanningaprojecttoreplacetheleakingwaterlinesinthenortheastareaofthePlant.Waterisexpectedtopersistinthewellforsometimeafterthewaterleaksarerepaired.

Asdiscussedinpreviousquarterlyreports,PantexdrilledPTX06‐1182in2016toevaluatewaterconditionsinthesoutheasternlobeofperchedgroundwaterbasedonthecontinuedannualevaluationthatindicatedthatsomeportionsofthesoutheastperchedgroundwaterarenotundertheinfluenceofthepumpandtreatsystems.WatercontainingHEsatconcentrationsabovetheGWPSwasdiscoveredinPTX06‐1182.Inresponsetothatinformation,Pantexinstalledthreenewwells(PTX06‐1184,PTX06‐1185,andPTX06‐1186[subsequentlychangedtoPTX06‐ISB107,thefirstwellonthewestsideoftheISB])during2ndquarter2017todefinetheextentoftheplumetothesoutheast(seefigureinAttachmentAmapsforwelllocations).WaterwasdiscoveredinPTX06‐1184andPTX06‐1186anddataconfirmedthepresenceoftwoHEs,RDXandDNT4A.

Aspreviouslyrecommended,PantexobtainedadditionalfundingtoextendtheSoutheastISBremedytothesoutheastboundaryofthesiteandaddnewmonitoringwells.PantexcompleteddrillingtheISBwellsinDecember2017.PantexalsoobtainedanagreementwiththelandownertothesouthandcompletedinstallationoffourmonitoringwellsinJanuary2018.Waterwaspresentinthreeofthewells;theother(PTX06‐1193)wasdry.SamplingofthethreewellsindicatedthatonlyoneofthenewwellsontheneighboringpropertydemonstrateddetectionsofCOCsaboveGWPS.InJanuary2018,Pantexalsoinstalledanothermonitoringwell(PTX06‐1195)alongthePantexeasternfenceline,northofthefinalSoutheastISBextensionwell,todefineextentinthat


area.ResultsindicatethatthewellhadnodetectionsofCOCsabovebackgroundconcentrationsorGWPS.

During2ndquarter2018,Pantexobtainedanagreementwiththeneighbortothesoutheastallowingthreemonitoringwells(PTX06‐1196,PTX06‐1197,andPTX06‐1199)tobedrilledinJuly2018.SampleswerecollectedinAugust2018,andresultsindicatethatwewereneartheextentofcontaminationtotheeast,butnottothesoutheast,asdemonstratedbythedetectionofRDXinPTX06‐1197(thefarthestdowngradientwell).

BecausethecontaminantdistributionindicatesflowprimarilythroughanoldsubsurfacepaleochannelandthemainRDXplumeisonly500to700ftwideatthepropertyboundary,properpositioningofwellsisimportanttoidentifythechannelandextentofcontamination.Themainpaleochannelwherethehighestconcentrationsoccurisnarrower,likelyonlyabout250ftwide.Toidentifytheboundariesofthepaleochannel,PantexconductedanelectromagneticstudyusingWillowstickTechnologies,LLC.Theobjectiveofthisstudywastoattempttoidentifytheareawithfasterflowpathsinthegroundwatersothattheextentofcontaminationcanbepositivelyidentified.ThefinalreportwasreceivedinDecember2018.ThereportindicatedthepossibilityofchannelsextendingthroughtheISB,withoneprimarychannelleadingoffsitetothesouthandsouthwest.Theresultsofthestudywerelesscertainattheoffsitepropertyduetointerferencefromutilitylinesandthewiringloopthatconnectedthebeginningandendingwells,homogeneityofthesubsurfacesoilsintheperchedaquifertothesoutheast,andlackofdown‐gradientwells.TheseissuesresultedintheinabilitytoidentifyanychannelstothesoutheastofPantex.However,basedontheoneidentifiedchannelandcontaminantdatacollectedatinstalledwells,Pantexbeganinstalling6newwells(PTX06‐1200through1205)onthepropertytothesouthandsoutheastofPantexpropertyinDecember2018.Thewelldrilledtothesouth(PTX06‐1205),intheareaoftheidentifiedchannelintheWillowstickstudy,doesnotconfirmthepresenceofwater.Datafromthelatestfivewellsinstalledtothesoutheastindicatethattheextentofcontaminationisdefinedtothesoutheast.RDXandDNT4AdatareportedfromthosewellsareprovidedinTable2.

Table2.ResultsofSamplingatOffsiteWellsinstalledtotheSoutheast

Well ID Sample Date DNT4A Measured Value (GWPS=1.2)

RDX Measured Value (GWPS=2)

PTX06‐1200 2/20/2019 ND ND

PTX06‐1201 2/20/2019 0.378 1.11

PTX06‐1202 2/21/2019 0.291 0.168

PTX06‐1203 2/21/2019 6.22 97.6

PTX06‐1204 2/20/2019 0.192 ND

PTX06‐1204 2/28/2019 0.182 ND

All values are reported in µg/L

ND = Non‐detect


SCHEDULEUPDATE

Pantexprovidedadetailedscheduleofupcomingworkinthe2018AnnualProgressReport.Anupdateoftheactivitiesscheduledtobestartedorcompletedbythepublicationdateofthisreportisprovidedbelow.

Pantexcompletedthefollowing:

ConstructionofLandfill3erosioncontrolbeganinAugust2018.WorkwascompletedinMarch2019.

Pantexconstructedthetie‐inofthenewextractionwellseastofFM2373toSEPTS.TheconstructionwascompletedinMarch2019.WellsbeganoperatingconsistentlyinMay2019.

AninjectionwascompletedattheSoutheastISBExtensioninFebruary2019.

Pantexcontinuesprogresstowardcompletionofthefollowingitems:

Pantexiscontractingforlandfillrepairwork.Theworkfocusesonfillingholes/voidsandreseedingofmultiplelandfills.AseparatecontractisunderwayformaintenanceoftheLandfill1ClosureTurf.Thisworkisexpectedtobecompletedin2019.

PantexiscurrentlyworkingoncontractingforthedesignandconstructionofinfrastructureandnewinjectionwellsfortheSEPTSnearPlaya2.Designandconstructionisexpectedtobecompletedbytheendof2019.

Pantexhascontractedfortheupdateoftheperchedgroundwaterfateandtransportmodelandevaluationoftreatmentoptionsfortheoff‐siteplume.ThisworkisexpectedtobecompletedinJune2019.

WellrehabilitationbeganattheZone11ISBinMarch2019.InjectionwillbegininMay2019.

PlanningbeganfortherehabilitationandinjectionoftheSoutheastISBandSoutheastISBExtension.RehabilitationeffortsareexpectedtobegininJune2019.

Contracting/constructionofsevennewinjectionwellsattheZone11ISBtoextendtreatmenttotheareatothenorthwestandencompasstheentireTCE/perchlorateplume.NewwellswillalsobeinstalledtothenorthwestoftheSoutheastISBtotrackthehexavalentchromiumandperchlorateplumesthataremovingthroughthatarea.Extractionwellswillalsobeinstalledtointercepttheplumes.

UpdateofthePantexPlantOgallalaAquiferandPerchedGroundwaterContingencyPlantoaddressnewremediationsystemstothesoutheastandupdategeneralinformation.ThisreportisscheduledtobesubmittedtoregulatoryagenciesinAugust2019.


UpdateoftheLong‐TermMonitoringDesign.ThisdesigndocumentisscheduledtobesubmittedtoregulatoryagenciesinSeptember2019.

UpdateoftheSamplingandAnalysisPlan.ThisdocumentisscheduledtobesubmittedtoregulatoryagenciesinSeptember2019.

Upcomingworkincludesthefollowing:

Pantexplanstomeetwithneighborstoaddresslong‐termcontrolofperchedgroundwaterontheoffsitepropertiesandtogainaccessforcleanupoftheoffsiteplume.

Contractingforconstructionofanoffsiteremediationsystem.

CONCLUSIONSANDRECOMMENDATIONSFORCHANGE

Theremedialactionscontinuetooperateandmeetshort‐termexpectationsforcleanupoftheperchedgroundwaterinareasundertheinfluenceoftheremediationsystems.Perchedwaterlevelsaredeclining,massisbeingremovedorreduced,andinstitutionalcontrolsprovideprotectionforuseofimpactedgroundwater,whiletheremedialactionscontinuetooperatetomeetlong‐termgoals.Pantexisworkingtoextendtreatmentsystemstoareasthatarenotcurrentlyundertheinfluenceoftheexistingremediationsystems.Pantexisalsoworkingtoextendtreatedwaterinjectionandbeneficialusetonewareastoensureconsistentoperationofthepumpandtreatsystems.

ThepumpandtreatsystemscontinuetoremoveCOCmassandwaterfromcriticalareasintheperchedaquifer,thusdecreasingheadthatisdrivingverticalandlateralmovementofperchedgroundwater.ThesystemshavebeenimpactedbytheshutdownoftheirrigationsystemandPantexiscontinuingtoevaluateotheroptionsforreleaseoruseofthetreatedwater.PantexwillcontinuetoinjectandreleasewatertoPlaya1untiltheirrigationsystemisrepairedorotherusescanbeidentifiedandconstructed.PantexrecommendedtheinstallationofperchedinjectionwellseastofthePlaya2area.ThesewellswillhelpprovideaconsistentoutletforreleaseoftreatedwaterfromSEPTSwhenbeneficialuseisnotpossible.Pantexexpectstoinjectupto150gpmoftreatedperchedgroundwateronceconstructioniscomplete.PantexisalsoplanningtodesignandconstructacenterpivotirrigationsystemeastofFM2373.Fundinghasbeenrequestedforthatproject.Pantexisalsoevaluatingashort‐termoptiontousewatercannonstoapplywatertoagriculturalfieldsthatareneartreatedwaterlines.

MonitoringresultsforareasdowngradientoftheISBsystemscontinuetodemonstratethatsystemtreatmenthasbeengenerallyeffective.COCconcentrationsmeettheGWPSattheSoutheastISBatthreedowngradientwells.Onedowngradientwell(PTX06‐1153)fortheSoutheastISBisnotrespondingtotreatmentaswellastheothers.Pantexplanstoinjectmolassesatthe2019injectioneventtoattemptbetterdistributionoftheamendmentandwillmonitortheresultsovertimetodetermineiftheinjectionwillimpactthewatermovingintothatarea.Monitoringwillcontinueat


PTX06‐1153asdescribedintheSAP,asthequarterlysampleswillprovideadequateinformationforthiswell.Furtherrecommendationswillbemadebasedonevaluationofdataovertime.

DowngradientwellsattheZone11ISBaregenerallydemonstratingtreatment.EightoftheninedowngradientISPMwellsexhibitperchlorateconcentrationsbelowtheGWPS,withperchlorateconcentrationsdecliningnearGWPSintheremainingwell.Sincethestartoftheremedialaction,TCEconcentrationscontinuetoindicateadecreasingtrend,withcurrentconcentrationsbelowtheGWPSinsixofninedowngradientwells.OnlyoneofthethreewellsnotmeetingGWPSdoesnotyetindicatestronglydecliningconcentrationsofTCE.DetectedconcentrationsoftheTCEbreakdownproductcis‐1,2‐DCEpersist,althoughthelatestresultsindicatethatitisbeingtreatedtoconcentrationsbelowtheGWPSinthesixofnineISPMwellsandconcentrationsnearGWPSintheotherwells.PantexhaschangedtheinjectionstrategyattheISBtoattemptbetterdistributionbetweenwellsandprovidebettertreatmentofTCE.Earlydataindicatethattheinjectionofamoresolublecarbonsource(molasses)hasdistributedwidelyintheareaitwasinjectedandthatreducingconditionshaveimprovedinthoseareas.Itwilltaketwoormoreyearstoevaluatetheresultsdowngradient.Basedontheresultsoftheuseofmolasses,Pantexissolelyinjectingmolassesduringthe2019injectioneventfortheZone11ISB.ThismeasureisexpectedtohelpavoidissueswithpluggingofthewellsandformationbytheEVOandresultingbiomass.Pantexwillcontinuetoevaluatethedataandmakeappropriaterecommendationsfortreatmentintheupcomingprogressreports.

TheSVEsystemcontinuestotreatsoilgasandresidualNAPLinthesolventevaporationpit/chemicalburnpitareaoftheBurningGround,therebymitigatingverticalmovementofVOCstogroundwater.Pantexhascontinuedtohaveproblemswithcompletingreboundtests,andhasbeenunabletoprepareapathtoclosureasrecommendedinthefirstFive‐YearReview(FYR).Therefore,Pantexhasevaluatedotherpathstoclosureforthissystem.InMay2017,PantexcompletedamodificationtosixinactiveSVEextractionwellssurroundingtheactiveextractionwellSVE‐S‐20toopenthewellstoambientair.Thismodificationenhancesairflowthroughtheformationwhilethesystemisoperating.Theairflowwasincreasedfrom32scfmtoabout45scfmovertime.EvaluationofhourlyVOCremovalindicatesthatthemassremovalrateinitiallyincreasedwiththeincreaseininfluentairflow.Althoughtheremovalrateincreasedslightlythisquarter,recentdataindicateadeclineinthemassremovalrateaswellasadropininfluentgasconcentrations.PantexwillcontinuetoevaluatetheVOCremovaltodeterminewhenactiveremovalwillnolongerbeeffective.PantexwillprovidefurtherrecommendationsbasedonreviewofinfluentSVEdataovertime.

Thegroundwaterremediesareconsideredtobeprotectivefortheshort‐term,asuntreatedperchedgroundwateruseiscontrolledtopreventhumancontactandmonitoringdatacontinuetoindicatethattheremedialactionsremainprotectiveoftheOgallalaAquifer.DetectionsofDNT4Aand1,2‐dichloroethaneatconcentrationsbelowtheGWPScontinuetooccurinoneOgallalawell(PTX06‐1056),andPantexisactivelyfollowingtheGroundwaterContingencyPlantoguidetheresponse.Pantexproactivelyconductedworktodeterminepossiblecausesofthedetections;thoseresultsindicatethatthemostlikelycauseisthenearbyperchedwellthatwasdrilleddeepintotheFGZ.PantexpluggedthenearbyperchedwellinNovember2014.Pantexwillcontinuetomonitor


thisOgallalawellquarterlytodetermineifatrendemerges,andwilldetermineiffurtherstepsarenecessaryfortheprotectionoftheOgallalaAquifer.

PantexcontinuestoevaluateoptionsforthesoutheastlobeofperchedgroundwatereastofFM2373.Asrecommendedinthe2016AnnualProgressReport,PantexhascompletedextendingtheSEPTSoperationtothatareatoaddressthecontinuedplumemovementtothesouth.PantexobtainedadditionalfundingtoextendtheSoutheastISBtothesoutheastboundaryofthesite,anddrillingoftheISBwellswascompletedinDecember2017.Infrastructuretoinjectwasdesignedandconstructedduring2018andthesystemwasinjectedinFebruary2019.Aftergainingaccessagreementswithneighbors,PantexinstalledsixadditionalwellstothesouthandsoutheastinDecember2018,withthewellssampledinFebruary2019.Resultsfromthosewellsindicatethatextentoftheplumehasbeenidentifiedtothesoutheast.Pantexisnowdesigningaremedialactiontoaddresstheoffsitecontaminationandisworkingwithneighborstogainaccessforremediationandensurelong‐termcontroloftheperchedgroundwaterforprotectionofpeopleandtheenvironment.

AppendixAMaps

1 Appendix A

Extent of Perched Groundwater and Contaminant Plumes

2 Pantex Plant 1st Quarter Progress Report, January – March 2019

Playa 1 Pump and Treat System Wells

3 Appendix A

Southeast Pump and Treat System Wells


Southeast ISB Wells and Sampling Locations

5 Appendix A

Zone 11 ISB Wells and Sampling Locations


Southeast ISB Extension Wells and Sampling Locations

7 Appendix A

Uncertainty Management and Early Detection Wells Evaluated in the Quarterly Progress Report


Other Unexpected Conditions Wells

AppendixBPumpandTreatSystemGraphs

1 Appendix B

SoutheastPumpandTreatSystemGraphs


3 Southeast Pump and Treat System Graphs

SEPTS Operation Time vs Target

SEPTS Average GPM and % Capacity

SEPTS GPD and % Capacity

SEPTS Monthly Total Flow


SEPTS Chromium Mass Removal by Month

SEPTS HE Mass Removal by Month

5

Playa1PumpandTreatSystemGraphs


7 Playa 1 Pump and Treat System Graphs

P1PTS Operational Time Vs Target

P1PTS Average GPM and % Capacity

P1PTS Average GPD and % Capacity

P1PTS Monthly System Total Flow


P1PTS HE Mass Removal by Month

9 Playa 1 Pump and Treat System Graphs

Appendix B Glossary

Operation Time Operation time represents the percentage of the total number of hours the

system was actually operated vs. the total possible hours the system could have

operated on a monthly basis.

GPM Extraction The gallons per minute (GPM) extraction rate represents the extraction rate from

the well field while the system was operating. This is a measurement of the well

field’s capability to support the overall system throughput goals. Low well field

rates can occur due to inoperable wells or decline in saturated thickness that

makes extraction difficult.

GPD Extraction The gallons per day (GPD) extraction rate represents the system’s ability to meet

overall throughput goals, considering the well field extraction rate and the

system’s operational rate. This rate is affected by the ability to extract water

from the well field and the system downtime.

Total Monthly Flow Total monthly flow is the total volume of extracted water measured at the

influent point of the pump and treat system. Individual well measurements and

flow rates are provided in the annual progress report.

AppendixCISBGraphs

ii Pantex Plant 1st Quarter Progress Report, January – March 2019

1

SoutheastISBGraphs


3 Southeast ISB Graphs












15

Zone11ISBGraphs


17 Zone 11 ISB Graphs























Documents

Remedial Action Progress 1st Quarter 2019 · capability to reinject, so the system has operated at a higher capacity using injection, release to Playa 1, and shutdown of P1PTS to