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TRANSCRIPT
Chapter 1Introduction
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor StationDraft Environmental Impact Report
1‐1 August 2012
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Chapter 1 1
Introduction 2
1.1 Overview 3
TheCaliforniaRegionalWaterQualityControlBoard,LahontanRegion(WaterBoard),isthe4
CaliforniaEnvironmentalQualityAct(CEQA)leadagencyfortheenvironmentalinvestigationand5
chromiumgroundwatercleanupatPacificGasandElectricCompany’s(PG&E’s)HinkleyCompressor6
Station.TheCompressorStationislocatedabout3milessoutheastofthetownofHinkleyin7
SanBernardinoCounty,California.8
TheCompressorStationfacilityisusedtotransportnaturalgasalongpipelinesfromTexasto9
California.Between1952and1964,coolingtowerwaterwastreatedwithacompoundcontaining10
chromiumtopreventcorrosion,andthewaterwasthendischargedtounlinedpondswhichresulted11
incontaminationofthesoilandgroundwaterbeneaththesitewithtotalandhexavalentchromium12
(Cr[T]andCr[VI]1,respectively).Asof2008,thiscontaminationcreatedaplumeofchromiumin13
groundwaterextendingabouttwomilestothenorthoftheCompressorStationandabout1.3miles14
wide(LahontanRegionalWaterQualityControlBoard2008).Asoflate2011,theplumewasmuch15
largerthanin2008andwasapproximately5.4milesinlengthandupto2.4mileswideatitswidest16
point.TheWaterBoardhasrequiredPG&Etotakeremedialactions2tocleanupthechromium17
contamination,andtoslowandstoptheplumefromspreading(alsoreferredtoascontainingthe18
plume).Theseremedialactionstodatehaveconsistedofthefollowingcleanuptechnologies:19
Groundwaterextraction:contaminatedgroundwaterispumpedfromthesubsurface(alsocalled20
theaquifer)tocontainthecontaminationplume.21
Agriculturalre‐use(alsocalledagriculturaltreatment,landtreatmentoragriculturalunits):22
extractedgroundwaterisusedtoirrigateforagecropsforlivestock.Hexavalentchromiuminthe23
extractedgroundwaterisconvertedtotrivalentchromium(Cr[III])bycontactwithorganic24
matterinthesoilasitinfiltratesthroughthesoil.Hexavalentchromiumisthetoxicformof25
chromium;trivalentchromiumhasverylowtoxicity(OEHHA2011).26
Subsurfacetreatment(alsocalledin‐situtreatmentorin‐situreactivezones):carbonsubstancesare27
injectedintothegroundwateraquifertoturnthehexavalentchromiumintotrivalentchromium.28
Subsurfacefreshwaterinjection:freshwaterisinjectedwithintheaquiferalongthewesternside29
oftheplumetopreventthespreadofcontaminatedgroundwatertotheHinkleySchooland30
residentialareas.31
1Inthecontextofthedescriptionofcontaminationingeneral,theterm“chromium”(Cr)isusedinplaceoftheseparateterms“totalchromium”(Cr[T])or“hexavalentchromium”(Cr[VI]).Hexavalentchromiumisacomponentoftotalchromium.Whenthereisreferencetoonlyhexavalentchromium,thenitisidentifiedassuch.2Varioustermsareusedinterchangeablythroughoutthisdocumenttoreferto“remedialactions.”Theseinclude“remedialoptions,”“technologies,”“remediationactivities,”and/or“treatmentapproaches.”Additionally,theproposedalternativesaredefinedasthevariouscombinationsofthenewremedialoptionsthatarebeingevaluatedinthisEIR.ThesealternativesaredescribedinChapter2,ProjectDescription.
California Regional Water Quality Control Board, Lahontan Region Introduction
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
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TheWaterBoardadoptedCleanupandAbatementOrder(CAO)No.R6V‐2008‐0002in2008,which1
requiredsite‐wideremediationofthecontaminatedgroundwater,andadoptedWasteDischarge2
Requirements(WDRs3)(OrderNo.R6V‐2008‐0014),alsoknownastheGeneralPermit,forthe3
implementationofplumecontainmentactions,in‐situremediation,andabove‐groundtreatment.4
Althoughabove‐groundtreatmentwasanapprovedactionundertheGeneralPermit,thisremedial5
methodhasnotbeenusedtodate.PriortoadoptionoftheGeneralPermit,PG&Ewasimplementing6
plumecontainment,in‐situtreatment,andlandtreatmentactionspursuanttopriorWaterBoard7
ordersandtheassociatedWDRsonalimitedbasis.ThemainWDRsthatexpandedonthemore8
limitedremediationactivitiesbefore2008include:9
AgriculturalreuseattheDesertViewDairyunderindividualWDRsforthePG&EInterimPlume10
ContainmentandHexavalentChromiumTreatmentProject(WaterBoardOrderNo.R6V‐2004‐11
0034)in2004;12
Extended‐scalein‐situremediationatthesourcearea(WaterBoardOrderNo.R6V‐2006‐0054),13
locatedonPG&E’sHinkleyCompressorStationpropertyin2006;14
Extended‐scaleinsituremediationintheCentralArea(WaterBoardOrderNo.R6V‐2007‐15
0032),locatedalongandnorthofFrontierRoad,in2007;and16
ExpandedpumpingfrompropertiesoutsidetheDesertViewDairywithdischargestotheDesert17
ViewDairy(WaterBoardOrderNo.RCV‐2004‐0034A1)in2007.18
AnadditionalWDRamendmentwasadoptedin2010toallowgroundwaterextractionfrom19
propertiesnorthandeastoftheDesertViewDairywithdischargestotheDesertViewDairyanda20
50percentincreaseintheallowablecombinedextractionrate(WaterBoardOrderNo.R6V‐2004‐21
0034A2).422
PriortoadoptionoftheWDRsandpursuanttoCEQA,theWaterBoardconductedenvironmental23
analysestoaddresstheimpactsofimplementingtheWDRsbypreparingandcertifyingrespective24
mitigatednegativedeclarations(MNDs)in2004,2006,and2007.In2008,aMNDwasalsoprepared25
toevaluateenvironmentalimpactsofimplementingtheGeneralPermitpriortoitsadoption.The26
WaterBoardadoptedaresolutionapprovingtheMNDpreparedfortheGeneralPermit(State27
ClearinghouseNo.2008011097)in2008.Anamendmenttothe2007MNDwaspreparedin2010to28
addressadditionalimpactsresultingfromexpandingremediationactivitiesattheDesertView29
Dairy.30
TheWaterBoardisnowpreparingtoissueanewCAOwhichwillsetspecificcleanuprequirements31
includingthecleanuplevelsandthetimeperiodsbywhichthoselevelsmustbemet.Anewsite‐32
wideGeneralPermitwillbeadopted,specifyingtheoperating,dischargeandmonitoring33
requirementsforcomprehensivecleanupofchromiumingroundwatertomeettherequirementsset34
bytheCAO.AlthoughtheWaterBoardisrestrictedbyWaterCodesection13360fromspecifying35
themethodandmannerofPG&E’scompliancewiththecleanupandabatementorder,thecleanup36
levelswilldrivewhatremedialactionsaretaken,wheretheyaretaken,andatwhatintensity.37
3WDRsarethepermitsthatsetoperating,dischargeandmonitoringrequirementsforPG&Etoconductremediationactivities.WDRsarealsoreferredtobytheirWaterBoardOrdernumber.4AlistofthecurrentCAOsandWDRsbeingimplementedcanbeaccessedontheWaterBoard’sprojectwebsiteathttp://www.waterboards.ca.gov/rwqcb6/water_issues/projects/pge/index.shtml#wbo.
California Regional Water Quality Control Board, Lahontan Region Introduction
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Manyofthesametechnologiesthatarecurrentlybeingimplemented(agricultural/landtreatment,1
in‐situtreatment,plumecontainment,freshwaterinjection/extraction)underexistingindividual2
WDRsandtheGeneralPermitwillcontinuetobeimplementedunderthenewGeneralPermit;3
however,theremaybenewpotentiallysignificantenvironmentalimpactssincethevarious4
combinationsofthesetechnologieswillbeexpandedsubstantiallyoverthosethatwereanalyzedin5
priorMNDs.Therefore,theWaterBoardhasdeterminedthatpreparationofanEIRisnecessaryto6
disclosepotentiallysignificantimpactsofadoptingthenewGeneralPermitandimplementing7
cleanuprequirementsprescribedintheCAO.TheEIRwillincludethefollowingcontentspursuantto8
therequirementsofCEQA:9
Newprojectalternativesdevelopedforcomprehensiveremediationofthechromium10
contamination.11
Newinformationrelatedtochangesinphysicalconditionswhereremedialactionshavebeen12
implemented,includingchangesinthecontaminatedareathathaveoccurredsincetheprevious13
CEQAMNDswereadopted(between2004and2010)(LahontanRegionalWaterQualityControl14
Board2008).15
Potentialsignificantdirectandindirectenvironmentalimpactsresultingfromimplementation16
oftheprojectalternatives,including:17
Groundwaterdrawdowneffectsonregionalandlocalwatersupplies,18
Impairmentofwaterqualityfromremedialactions,19
Lossordisturbanceofendangeredspecieshabitat,20
Increasednoiseandtraffic,21
Permanentlossofresidencesthroughpropertybuyouts,and22
Constructionimpacts.23
Mitigationmeasuresproposedtoreduceoravoidpotentialsignificantenvironmentalimpacts24
resultingfromimplementationoftheprojectalternatives.25
Cumulativeandgrowth‐inducingimpacts.26
1.2 Water Board Outreach Activities 27
AspartoftheCEQAprocess,theWaterBoardhasengagedthepublicinanexpansiveprocessto28
keeptheminvolvedandinformedoftheproject’sdevelopmentandtheEIRdevelopment.TheWater29
Boardissuedpublicnoticesrequestingcommentsonthevariousremediationfeasibilitystudiesand30
CAOsandconductedseveralcommunitymeetings.Thisprocesshasbeenongoingsinceinitiationof31
theCEQAscopingperiodinNovember2010.DuringthescopingperiodforthisEIR,whichwas32
concurrentwiththecommentperiodforthe2010FeasibilityStudypreparedbyPG&E,theWater33
BoardreceivedcommentsrelativetotheCEQAanalysis,theoveralltreatmentapproach,andother34
issuesrelatedtoPG&E’sactivitiesintheHinkleyarea(someofwhichareoutsidethepurviewofthe35
WaterBoard).Thekeymilestonesinthepublicoutreachprocesstodate,andasummaryof36
commentsandissuesraisedareprovidedbelow.Foreachissueraised,asummaryoftheissueanda37
discussionofwhetheritiswithinthepurviewofthisEIRisprovided,includingadescriptionof38
whetherandhowtheissueisaddressedinthisEIR.39
California Regional Water Quality Control Board, Lahontan Region Introduction
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1.2.1 Timeline of Activities 1
November24,2010:ANoticeofPreparation(NOP)waspublishedtonotifythepublicofthe2
WaterBoard’sintentforpreparinganEIRtoevaluatepotentialenvironmentalimpactsofthe3
project.TheNOPincludedinformationontheproposedcomprehensivecleanupstrategy4
proposedbyPG&EandtheCEQAprocess.TheWaterBoardrequestedpubliccommentsonthe5
NOP.ThedeadlineforpubliccommentswasDecember31,2010.6
December1,2010:AspartoftheCEQAscopingprocess,apublicscoping/feasibilitystudy7
informationalmeetingwasheldinHinkley.TheWaterBoardstaffaskedforinputonissuesto8
evaluateintheEIRandalsoaskedforpublicinputonthealternativesanalyzedintheSeptember9
2010FeasibilityStudy.10
December10,2010:RequestforpubliccommentsonfinalsitecleanupatthePG&E11
CompressorStation.TheWaterBoardrequestedpubliccommentsonPG&E’sfeasibilitystudy12
forfinalcleanup.ThedeadlineforpubliccommentswasJanuary10,2011.13
January26and27,2011:TheWaterBoardhostedtwoinformationmeetingsatHinkley14
ElementarySchoolaboutcleanupactivitiesatPG&E’sHinkleysite.Themeetingsincludedmaps15
showingcurrentboundariesofthechromiumplumeingroundwater,summariesofcomments16
theWaterBoardreceivedonPG&E’sSeptemberfeasibilitystudyonachievingfinalsitecleanup,17
andinformationonthescopeandcontentoftheEIRtheWaterBoardisdevelopingtoevaluate18
theenvironmentalimpactsofcleanupalternatives.19
March9and10,2011:TheWaterBoardhostedapublicmeetinginBarstowtoprovideastatus20
reportonPG&E’scontainmentandremediationactivitiesforthecleanup.Discussionwas21
providedontheneedandprocessfordevelopingtheEIR,thecleanupstandard,cleanuptimes22
andtechnologies,andpotentialenvironmentalimpactsofthecleanupactivities.Hinkley23
residentsexpressedconcernsaboutPG&E’s2007chromiumbackgroundstudyandhowthe24
backgroundchromiumconcentrationsingroundwaterweredetermined.Inresponsetothose25
concerns,WaterBoardmembersdirectedstafftohavePG&E’s2007GroundwaterBackground26
StudyReport(the2007BackgroundStudyReport)reviewedbyindependentscientific27
reviewers(seethesummaryofpubliccommentsonthisissueunderSection1.2.2below).28
October14,2011:TheWaterBoardpostedtheresultsofthethreeindependentpeerreviews29
ofthebackgroundchromiumstudyonitswebsite.Thereviewswereconductedandsubmitted30
byProfessorYoramRubin,Ph.D.,oftheUniversityofCaliforniaatBerkeleyDepartmentofCivil31
andEnvironmentalEngineering;JamesJacobs,PG,fromClearwaterGroupEnvironmental32
Services;andDr.StuartNagourneyoftheCollegeofNewJersey,DepartmentofChemistry.The33
WaterBoardalsoadoptedCAONo.R6V‐2011‐0005A1concerningwholehousewater34
replacement.35
December8,2011:TheWaterBoardheldapublicinformationmeetingatHinkleyElementary36
School.MeetingtopicsincludedCAONo.R6V‐2011‐0005A1issuedinOctober2011,resultsofthefall37
2011groundwatermonitoringforchromium,EIRdevelopmentupdate,andasummaryofpeer38
reviewcommentsonthe2007BackgroundStudyReport.39
March15and16,2012:AtaWaterBoardMeetinginBarstow,theBoardadoptedastipulated40
orderandsettlementagreementimposingatotalliabilityamountof$3.6millionagainstPG&E41
forfailuretocomplywitharequirementofCAONo.R6V‐2008‐0002.One‐halfoftheliability42
wouldbepaidtotheStateandtheotherhalfwouldbeusedtoimplementaprojecttoeliminate43
California Regional Water Quality Control Board, Lahontan Region Introduction
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groundwaterpumpingattheHinkleySchoolandsupplywaterfromalocationupgradientofthe1
CompressorStation.TheSettlementalsoincludesaprovisionwherebytheWaterBoard2
amendedtheplumecontainmentrequirementsintheexistingAmendedCAONo.R6V‐2008‐3
0002A1issuedonApril7,2009,allowingcertainlateralspreadingofthechromiumplume4
associatedwithremediationactivities.Atthismeeting,theBoardalsoheardasummaryand5
discussionofthe2011PeerReviewofPG&E’s2007BackgroundStudyReportfromWaterBoard6
staff.Supportingmaterialsincluded:1)aWaterBoardstaffreportdiscussingthepeer7
reviewers’comments;2)apubliccommentletter;and3)PG&E’sFebruary2012proposedwork8
planforevaluationofbackgroundchromiumintheupperaquiferoftheHinkleyValley.9
October2011toJune2012:InOctober2011,theWaterBoardissuedCAONo.R6V‐2011‐10
0005A1toPG&E.TheOrderrequired,inpart,thatPG&Eprovideinterimandwholehouse11
replacementwaterservicetothoseservedbydomesticorcommunitywellsthatarewithinthe12
affectedareaanddeterminedtobeimpactedbyitsdischarge.TheOrderdefinedimpactedwells13
asalldomesticorcommunitywellsintheaffectedareathatareabove3.1partsperbillion(ppb)14
hexavalentchromiumor3.2ppbtotalchromiumplumeboundaries,baseduponmonitoringwell15
datadrawninthemostcurrentquarterlysite‐widegroundwatermonitoringreportsubmitted16
byPG&E.TheOrderalsodefinedimpactedwellsasthosedomesticorcommunitywellsinthe17
affectedareathatcontainhexavalentchromiuminconcentrationsgreaterthan0.02ppbthat18
weretheresultofPG&E’sdischargeattheFacility.PG&Ewasrequiredtodevelopamethodto19
determineifawellwithintheaffectedarea,thatcontaineddetectablelevelsofhexavalent20
chromiumbelow3.1ppbortotalchromiumbelow3.2ppb,wasimpactedbyitsdischarge.21
InlettersdatedNovember23,2011,andDecember22,2011,PG&Eprovideditspositionthat22
thereiscurrentlynocrediblemethodtodeterminethesourceofhexavalentchromiumin23
domesticwellswithdetectionsbelowthecurrentbackgroundvalues(3.1ppbhexavalent24
chromiumor3.2ppbtotalchromium).Instead,PG&EofferedtoimplementaVoluntaryWhole25
HouseReplacementWaterProgram(Program).26
OnJune6,2012,PG&Esubmittedaletterwithits“RevisedReplacementWaterSupply27
FeasibilityReport,”(FeasibilityStudy)supplementinginformationregardingtheProgram.28
TheProgramwillprovideinterim(untilthewholehousereplacementwaterisimplemented)or29
wholehousereplacementwaterservicefordrinkingwaterpurposesthatmeetsallCalifornia30
primaryandsecondarydrinkingwaterstandardsandhexavalentchromiumlevelsoflessthan31
0.02ppborthefinalMCL,oncethatstandardisadoptedbyCDPH,toallthoseservedby32
domesticorcommunitywellsintheaffectedareawhenanalyticalmonitoringresultsfromthose33
wellsindicatedetectablelevelsofhexavalentchromiumatanytimeduringthemostrecentfour34
consecutivequarters.Propertyownerswouldbegiventheoptionofanionexchangeunitsfor35
thetreatmentofallwaterplusandundersinkreverseosmosisunitforadditionaltreatmentof36
allwaterusedfordrinkingwaterpurposesorinstallationofdeeperwells,wherefeasiblebased37
onPG&E’sassessmentofexistingwaterqualityandhydrogeology.38
Inresponsetothatproposal,theWaterBoardsuspendedseveralprovisionsofOrderR6V‐2011‐39
0005A1,includingtherequirementtodevelopamethodtodetermineifawellwithinthe40
affectedareathatcontaineddetectablelevelsofhexavalentchromiumbelow3.1ppbortotal41
chromiumbelow3.2ppbwasimpactedbyitsdischarge,aslongasPG&Econtinuedto42
implementitsvoluntaryprogram(CAOR6V‐2011‐0005A2).43
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1.2.2 Public Comments 1
1.2.2.1 Cleanup Levels and the Definition of Background 2
Thecommentsbelowweremadeduringthescoping/feasibilitystudycommentperiodregardingthe3
definitionof“background”andtheextenttowhichtheWaterBoardshouldrequirePG&Etoclean4
upthechromiumcontaminationintheHinkleyaquifer.5
TheWaterBoardshouldrequirecleanuptoresultinconcentrationsthatarelessthanthe6
maximumbackground(3.1ppb)identifiedinthebackgroundstudy(forbothhexavalentchromium7
(Cr[VI])andtotalchromium(Cr[T])).8
TheWaterBoardshouldrequirecleanuptoresultinconcentrationsthatarelessthantheaverage9
backgroundlevel(1.2ppb)identifiedinthebackgroundstudy.10
TheWaterBoardshouldconsiderOEHHA’sadoptedPublicHealthGoal(0.02ppb)asthe11
backgroundandstandardforCr[VI]cleanup.12
TheWaterBoardshouldrevisitthebackgroundstudy(PacificGasandElectric2007[submittedto13
theWaterBoardin2007andacceptedbytheWaterBoardin2008])inlightoftheplume14
spreadingtothenorthandeastin2010.15
In2011,theWaterBoardinitiatedapeerreviewofthe2007BackgroundStudyReportandpeer16
reviewcommentsidentifiedspecificconcernsregardingthewellsutilized,analyticalprocedures,17
statisticalanalysis,andotherissues.TheWaterBoardstaff,asdirectedbytheWaterBoardinits18
March2012meeting,isretainingtheexistingbackgroundvaluesadoptedinamendedCAOR6V‐19
2011‐005A1whilereviewingPG&E’sproposednewbackgroundstudyandconsideringtheneedfor20
peerreviewand/orconsultationwithotherexperts,suchastheUSGeologicalSurvey,toensurethat21
anynewstudywillyieldavalid,credibleanddefensibleresult.ForthepurposeofthisDraftEIR,the22
WaterBoardisusingthevaluesderivedfromthe2007BackgroundStudyReporttodefinethe23
chromiumplumeandasinterimcleanuplevelspendingcompletionofanewbackgroundstudy.24
StateWaterResourcesControlBoardResolution92‐49requiresdischargerstocleanupandabate25
theeffectsofdischargesinamannerthatpromotesattainmentofeitherbackgroundwaterquality,26
orthebestwaterqualitywhichisreasonableifbackgroundlevelsofwaterqualitycannotbe27
restored.Insettingcleanuplevels,allcurrentandexpecteddemandsonthosewatersmustbe28
considered,includingbeneficial,detrimental,economic,social,tangible,andintangiblevalues.29
TheWaterBoardcannotrequirePG&EtocleanupnaturallyoccurringCr[VI].Totheextentthatthe30
proposedPublicHealthGoalislessthannaturallyoccurringbackgroundlevels,theWaterBoard31
doesnothavetheauthoritytorequirecleanuptotheproposedPublicHealthGoal.Asnotedabove,32
theWaterBoardisrevisitingthebackgroundstudyandmayadoptrevisedbackgroundlevelsif33
warrantedbasedontheresultsofanewbackgroundstudy.Ifnewbackgroundlevelsareadopted,34
theWaterBoardmayberequiredtoamendthenewGeneralPermitandCAO,andsubsequent35
environmentalanalysismayberequirediftheamendmentswouldrequireanyactionsthatgo36
beyondthescopeofthisEIRanalysis.Section3.1,WaterResourcesandWaterQuality,describesthe37
regulatorybackgroundrelatedtoestablishmentandrevisionofbackgroundcontaminationlevels.38
1.2.2.2 Project Alternatives and Time Period to Complete Cleanup 39
Thecommentsbelowweremadeduringthescopingperiodregardingthetimeitwilltaketo40
completethecleanupofthesiteunderthevariousproposedalternatives:41
California Regional Water Quality Control Board, Lahontan Region Introduction
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Allofthe2010FeasibilityStudyalternativestaketoolongtocleanupthesite.1
Theloweraquiferplumeareashouldbedelineated.2
SoilcontaminationattheCompressorStationshouldbeaddressed.3
TheeffectsofCr[III]remaininginthesoilafterproposedin‐situtreatmentshouldbeaddressed.4
ThepotentialforCr[VI]andothercontaminantstospreadshouldbeaddressed.5
Additionaltechnologiesbeyondthoseproposedinthefeasibilitystudyshouldbeconsidered.6
TheimpactofPG&E’spropertybuyoutprogramshouldbeanalyzed.7
TheWaterBoard’sgoalinsettingcleanupobjectivesistorequirePG&Etocleanuptheportionof8
theHinkleygroundwateraquiferthatitcontaminatedtobackgroundlevelsofCr[VI]aspossiblein9
theminimumamountoftimefeasible,whilelimitingormitigatingenvironmentalimpacts10
associatedwiththecleanupactivities.Tothatend,theWaterBoardhasrequiredPG&Etoconsider11
additionalalternativesthatwouldresultinshortercleanuptimeframesthanthoseoriginally12
proposedinthe2010FeasibilityStudy.Accordingly,threeaddendaandadditionalevaluationshave13
beenpreparedbyPG&Etoevaluatemethodstoachievecleanupgoalsmorerapidly(seeChapter2,14
ProjectDescription,foradescriptionofthealternativesanalyzedindetailinthisEIRaswellasthe15
alternativesconsideredanddismissedfromfurtherconsideration).16
PG&EcompleteddelineationofthecontaminationintheloweraquiferinFebruary2011.17
Informationfromthatinvestigationisusedinthisdocument.Theapprovedcomprehensivecleanup18
strategywillincludecleanupofloweraquifercontaminationtobackgroundconcentrationsorthe19
cleanupgoalstobesetbytheWaterBoardspecificallyfortheloweraquifer.20
TheWaterBoardcanrequirecleanupofsoilswheretheyposeathreattogroundwaterorother21
watercontamination.PriorsoilremovalactionsoccurredattheCompressorStation.Thecurrent22
remedialactionisfocusedongroundwatercleanup.23
ThisEIR(seeSection3.1,WaterResourcesandWaterQuality)addressesthepotentialforand24
impactsofconversionofCr[III]backtoCr[VI],potentialchangesintheplumeasaresultof25
remediationactivities,thepotentialforincreasesinothercontaminantsattributabletoremediation,26
andotherpotentialeffectsonwaterqualityasaresultofimplementingremediation.27
AsdescribedinChapter2,ProjectDescription,theproposedalternativesweredevelopedandbased28
onthe2010FeasibilityStudyanditsfirst,second,andthirdaddendaandotherinformation.The29
suiteoftechnologiesevaluatedinthefeasibilitystudy/addenda(andinaprior2002feasibility30
study)isextensiveandbasedondatasupportingtheeffectivenessofeachtechnology.31
PG&E’spropertyacquisitionprogramisanongoingactivitythatPG&Ehasbeenimplementingatits32
owninitiativeovertime.However,theremedialalternativesconsideredinthisEIRwillmostlikely33
requireacquisitionofcertainparcelsofland(andpossiblyresidences)toimplementremediation34
fully.Whereitisreasonablyforeseeablethatimplementationofremediationwillrequireproperty35
acquisition,theenvironmentalimpactofthatacquisitionwillbeanalyzedinthisEIRinrelationto36
impactstolanduse,housing,population,andsocioeconomics(seeSection3.2,LandUse,Agriculture,37
Population,andHousing).38
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1.2.2.3 Water Supply 1
Theprimaryconcernraisedinthescopingcommentsrelatedtowatersupplywasthepossibilityof2
reducedavailabilityofpotable/domesticwaterasaresultofcontinuedcontamination.Inaddition,3
residentsraisedconcernaboutwaterfordomesticanimals(includinghorses)andvegetableplanting.4
Thepotentialeffectsofremediationongroundwaterlevels,supply,andqualityareevaluatedinthis5
EIR(seeSection3.1,WaterResourcesandWaterQuality).6
1.2.2.4 Data Collection and Information 7
Thecommentsbelowconcerningdatacollectionandinformationwerereceived.8
PG&EshouldbeinvolvedonlyinfundingtheWaterBoard’scollectionofdataanddevelopmentof9
alternatives,notproducingit.10
Anindependentcostanalysisshouldbeprepared.11
Plumemapsneedtohavebetterreferencepoints,suchasroads,andbelabeledmoreclearly.12
Thetypeandamountoftracersbeinginjectedintheaquifershouldbeidentified.13
ItisPG&E’sresponsibilitytocollectdatanecessarytodevelopfeasiblealternativestomeetWater14
Boardcleanuprequirements(WaterCodeSection13307;StateWaterResourcesControlBoard15
Resolution92‐49).Ininvestigatingthesiteanddevelopingcleanupalternatives,PG&Eisrequiredto16
usecertifiedmethods,labs,andprofessionals.17
PG&Eisresponsibleforthecostsofremediation.ThosecostsarenotaprimaryfactorintheWater18
Board’sdeterminationofcleanupobjectives,excepttotheextentthatitisonefactorofseveralthat19
theWaterBoardmustconsiderindecidingwhethertorequirecleanuptobackgroundlevelsorto20
thebestwaterqualitywhichisreasonableifbackgroundlevelsofwaterqualitycannotberestored.21
(StateWaterResourcesControlBoard,Resolution92‐49.)Anindependentcostanalysisisnot22
required,anditisnotclearwhatbenefitsuchananalysiswouldprovide.Thecostsprovidedby23
PG&Einitsfeasibilitystudyandaddendaareusedprimarilyforcomparingrelativecostsofeach24
alternativeanalyzed.25
ThisEIRincludesmapsanddiagramsdesignedtohelpthereaderunderstandthelocationsof26
componentsoftheproposedremediationactivitiesandhowtheyrelatetoexistingfeatures.Tothe27
extentpossible,mapsincluderoadnamesandotherlabels.28
ThisEIRdescribesallowedtracers,allowablelimits,andhowtheleveloftraceelementsmaychange29
withimplementationoftheremediationactivities(Section3.1,WaterResourcesandWaterQuality).30
TheWaterBoardwillrequirereportingandtrackingoftracersandotheradditives/chemicalsas31
partoffuturepermitsororders.TheexistingGeneralPermitrequiresidentification,tracking/32
monitoring,andreportingofanytracersoradditivesused(injectedintothegroundwater).33
1.2.2.5 Health and Safety 34
Thecommunityalsoexpressedconcernsaboutthesafetyofwellwaterfordrinking,cooking,35
bathing,swimming,laundry,petconsumption,anduseinswampcoolers.Additionally,therewere36
questionsabouthowlawnsandotheroutdoorareasirrigatedwithwellwatercouldaffectthose37
playingonormowingthelawns.38
California Regional Water Quality Control Board, Lahontan Region Introduction
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Thepotentialhealtheffectsofchromium(bothCr[III]andCr[VI])andotherconstituentsare1
discussedinSection3.1,WaterResourcesandWaterQuality,includingrisksassociatedwithpotable2
useandnon‐potableuses.3
ContaminatedgroundwaterisanexistingconditionattributabletothepriorreleaseofCrfromthe4
CompressorStation.Assuch,priororcurrenthealthimpactsrelatedtoCrcontaminationarea5
componentoftheproject’senvironmentalbaselineandattributabletothepriorreleasesandnot6
totheproposedproject(i.e.,thecomprehensivecleanupstrategy).Thecomprehensivecleanup7
strategyisintendedtolowertheCr[VI]concentrationsingroundwatertobackgroundlevelsand8
assuchwouldreducehealthimpactsrelatedtoCrcontaminationcomparedwithexisting9
conditions(late2011).Therefore,theimpactsidentifiedinthisEIRarethoseassociatedwiththe10
remediationactivities,nottheexistingcontamination.However,thereisthepotentialforcertain11
remedialactionstoresultinincreasedconcentrationsofotherconstituents(suchasarsenic,iron,12
manganese,nitrate,ortotaldissolvedsolids)asaresultofremedialactivity.Shouldthisoccur,13
remedialactivitycouldincreasepublichealthriskscomparedwithexisting,conditions.Sections14
3.1,WaterResourcesandWaterQuality,and3.3,HazardsandHazardousMaterials,analyzethis15
possibility.16
Itshouldalsobenotedthatin2011,theWaterBoardorderedPG&Etoprovidewholehouse17
replacementwatertoanyresidencesaffectedbythecontaminatedplume.Furthermore,PG&Ewas18
orderedtosubmitaplantoprovidepermanentreplacementwaterforallindoordomesticuses19
(referredtoas“wholehousewater”)forallwellsimpactedbyPG&E’sdischargewithinthe“affected20
area”(definedastheareawithin1miledowngradientorcrossgradientfromtheplume).PG&E21
conductedapilotstudytoevaluatewatertreatmenttechnologiesforpurposesofprovidingwhole22
housewaterreplacementtoaffectedresidences.Basedonconclusionsofthatstudy,foranyone23
withintheaffectedareawithdetectablelevelsofhexavalentchromiumintheirwell,PG&Edecided24
toofferthechoiceofeither1)anionexchangeunitforthetreatmentofallwaterplusanundersink25
reverseosmosisunitforadditionaltreatmentofallwaterusedfordrinkingwaterpurposes,or2)26
installationofadeeperwell,wherefeasiblebasedonPG&E’sassessmentofexistingwaterquality27
andhydrogeology.28
1.3 Other Permits and Approvals 29
Asdescribedabove,PG&Eiscurrentlyimplementingprojectremedialactivitiesincompliancewith30
priorandexistingCAOsandWDRs.Implementationoftheactionalternativeswillrequirethe31
LahontanWaterBoardtoadoptnewWDRsandaCAOthatwilladdressbothexistingandexpanded32
remedialactivities.ToimplementtheremediationactivitiesanalyzedinthisEIR,PG&Ewillalso33
needtoobtainthepermitsandapprovalsfoundinTable1‐1.34
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Table 1‐1. Other Required Permits and Approvals 1
Permit PermittingAgency Trigger
Incidentaltakepermit(perthefederalEndangeredSpeciesAct(ESA)undereitherSection7orSection10oftheAct)
U.S.FishandWildlifeService(USFWS)
Potentialtakeofdeserttortoiseduetoremedialactivities.DeserttortoiseislistedasthreatenedunderthefederalESA.TakeisdefinedunderfederalESAas“harass,harm,pursue,hunt,shoot,wound,kill,trap,capture,orcollect,ortoattempttoengageinanysuchconduct.”
Encroachmentpermit U.S.BureauofLandManagement(BLM)
Encroachmentduetoconstructionactivitiesonfederalland
CleanWaterAct(CWA)Section404
U.S.ArmyCorpsofEngineers PotentialpermitforfillthatmayoccurindrainagestotheMojaveRiver.
NewWDRs;CWASection401and402;PorterCologneWaterQualityAct
CaliforniaRegionalWaterQualityControlBoard,LahontanRegion(WaterBoard)
RemediationofchromiumplumeDischargeofpollutantsduringconstruction
Incidentaltakeauthorization(perSection2081oftheCaliforniaFishandGameCode)
CaliforniaDepartmentofFishandGame(CDFG)
PotentialtakeofMohavegroundsquirrelduetoremedialactivities.MohavegroundsquirrelislistedasthreatenedundertheCaliforniaEndangeredSpeciesAct(CESA).TakeisdefinedunderCESAas“hunt,pursue,catch,capture,orkill,orattempttohunt,pursue,catch,capture,orkill.”
Encroachmentpermit CaliforniaDepartmentofTransportation(Caltrans)
Encroachmentinstatehighwayrightofway(ifneeded)
Emissionreductioncreditlease
MojaveDesertAirQualityManagementDistrict(MDAQMD)
Particulateandexhaustemissionimpactsbeyondestablishedthresholds(ifneeded)
Encroachment,drilling,grading,andbuildingpermits
SanBernardinoCounty Drilling,grading,and/orotherconstructionactivitiesandnewbuildings(suchasabove‐groundtreatmentfacilities)inareasunderCountyjurisdiction.
1.4 Intent of the EIR 2
ThisDraftEIRhasbeenpreparedinaccordancewithCEQA,whichrequiresallstateandlocal3
governmentagenciestoconsidertheenvironmentalconsequencesofprojectsoverwhichtheyhave4
discretionaryauthoritybeforetakingactiononthoseprojects(CaliforniaPublicResourcesCode5
Section21000etseq.).6
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TheintentofthisDraftEIRisto:1
Identifypotentialdirect,indirect,andcumulativeenvironmentalimpactsassociatedwiththe2
project.3
Describefeasiblemitigationmeasuresintendedtolessenoravoidpotentiallysignificantproject4
impactsorreducethemtoaless‐than‐significantlevel.5
Disclosepotentialprojectimpactsandproposedmitigationmeasuresforpublicreviewand6
comment.7
Discussprojectalternativesthatavoidorreduceidentifiedsignificantprojectimpacts.8
ThisEIRevaluatessixalternativestoachievethefinalgroundwatercleanup.Allofthealternatives9
involvedifferentcombinationsofseveraltypesofremediationtechnologies,includinggroundwater10
extractionandagriculturalreuse;cleanwaterinjection;groundwaterextraction,aboveground11
treatment,anddischarge;andin‐situtreatment.Thedifferentcombinationsoftheseremediation12
technologiesnotonlyresultincleanuptimesto3.1ppbofCr[VI])rangingfrom29to40years,but13
theyalsoresultindifferingkindsandseverityofimpacts.Thescopeofthealternativeschosentobe14
analyzedinthisEIRwasintendedinparttodemonstratethetradeoffsbetweencleanuptimeand15
environmentalimpactsfromtheremedialactivities.Asremediationactivitiesarerampedupin16
ordertoachievecleanupmorequickly,theseverityoftheenvironmentalimpactspotentiallyalso17
increases.18
Ratherthanselectingoneremediationalternativeastheproposedprojectandprovidingaless19
detailedevaluationofotheralternatives(asCEQAallows),thisEIRprovidesadetailedanalysisofall20
ofthealternatives.TheWaterBoardwillusethisEIRtosupportitsadoptionofWDRsforPG&Eto21
implementthevariousremediationtechnologiesthroughouttheprojectareaandduration,andto22
supportitsadoptionofanewCAO.ThenewCAOwillestablishspecificcleanupobjectivesand23
timelinesbasedontheanalysiscontainedintheEIRandwillrequirePG&Etotakeactionswithinthe24
prescribedtimelinestomeetthecleanupobjectives.AlthoughtheWaterBoardmaydecideto25
identifyinitsnewCAOoneofthealternativesanalyzedintheEIRasthebestmethodtoachievethe26
prescribedobjectivesandtimelines,theWaterBoardmayonlyfocusitsOrderonwaterquality27
outcomesbasedonimplementationofoneormoreoftheremediationtechnologiesanalyzedinthis28
EIR.29
1.5 EIR Organization 30
ThisEIRisorganizedasoutlinedbelow.31
ExecutiveSummary:Providesasummaryoftheprojectandproposedalternativesand32
environmentalimpactsandmitigationmeasures.33
Chapter1,Introduction:Providesanoverviewoftheproject,pastenvironmentalanalysisof34
elementsoftheprojectonwhichthisEIRisbased,anddescribestheWaterBoard’spublic35
outreachactivities,includingsummarizingconcernsraisedduringthepublicscopingmeeting,36
andhowthoseconcernswillbeaddressed,andidentifiesadditionalrequiredpermitsand37
approvals.38
Chapter2,ProjectDescription:Identifiestheprojectlocationandprojectarea,describes39
developmentoftheproposedalternativesandeachofalternativestobeevaluated,disclosesthe40
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alternativesconsideredandwithdrawnfromfurtheranalysis,andidentifiesmitigation1
measuresthatwillbeimplementedaspartoftheproject.2
Chapter3,ExistingConditionsandImpacts:Describestheenvironmentalsettingandpresents3
theimpactanalysisassociatedwithimplementationoftheproposedalternativesforthe4
followingresources:5
3.1,WaterResourcesandWaterQuality6
3.2,LandUse,Agriculture,PopulationandHousing7
3.3,HazardsandHazardousMaterials8
3.4,GeologyandSoils9
3.5,AirQualityandClimateChange10
3.6,Noise11
3.7,BiologicalResources12
3.8,CulturalResources13
3.9,UtilitiesandPublicServices14
3.10,TransportationandTraffic15
3.11,Aesthetics16
3.12,Socioeconomics17
Chapter4,OtherCEQAAnalyses:Presentsthepotentialgrowth‐inducingandcumulativeeffects18
resultingfromimplementationoftheprojectforeachresourcearealistedabove,andidentifies19
theenvironmentallysuperioralternative,significantandunavoidableenvironmentalimpactsof20
theproject,andsignificantirreversibleenvironmentalchangesthatwouldbecausedbythe21
project.22
Chapter5,References23
Chapter6,ListofPreparers24
AppendixA,GroundwaterandRemediationSupportingDocumentation25
AppendixB,AdditionalDataonAlternatives26
AppendixC,BiologicalResourcesReport27
AppendixD,AirQualityandClimateChangeBackgroundInformationandCalculations28
AppendixE,NoticeofPreparationandScopingComments29
Chapter 2Project Description
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Chapter 2 1
Project Description 2
2.1 Introduction 3
Thischapterdescribestheprojectlocation,definestheprojectarea,establishestheexisting4conditions,identifiesprojectgoalsandobjectives,discussesthecontextforhowtheproject5alternativesweredeveloped,anddescribesthealternativesevaluatedintheEIR.6
PursuanttoexistingWaterBoardorders,PG&Ehasimplementedremediationactivitiestocleanthe7groundwaterimpactedbyhistoricalchromiumdischargesfromPG&E’sHinkleyCompressorStation8(refertoSection1.1,Overview,inChapter1).Theproposedprojectconsistsofexpanded9remediationactivities.ThisEIRevaluatessixalternativeswithdifferenttypesandcombinationsof10additionalremediationactivities,includingplumecontainment,in‐situtreatment,landtreatment,11andabove‐groundtreatment.RefertoSection2.8,ProjectAlternatives,belowforadetailed12descriptionofeach.13
Ratherthanselectingonealternativeastheproposedprojectandprovidingalessdetailed14evaluationoftheotheralternatives(asCEQAallows),theWaterBoardhaselectedtoevaluateeach15alternativewithanequallevelofdetailtoprovidemoredetailedinformationanddisclosureof16impacts.17
2.2 Project Location 18
TheproposedprojectislocatedinSanBernardinoCountyinthetownofHinkley,California.The19PG&EHinkleyCompressorStationislocatedintheMojaveDesertapproximately6mileswestofthe20cityofBarstow,California,andabout1milenorthoftheMojaveRiver.Figure2‐1showstheproject21locationandvicinity.AllChapter2figuresareincludedattheendofthischapter.22
2.3 Project Area 23
AttheinitiationofthisCEQAprocessinlate2010,theprojectareawasdelineatedasthehexavalent24chromiumCr[VI]contamination(orplume)areacontainingmorethan3.1partsperbillion(ppb)of25Cr[VI],includingimmediatelyadjacentareas.Sincelate2010,thedefinedplumeareacontaining26morethan3.1ppbofCr[VI]hasbeendeterminedtobesubstantiallylarger,likelyduetosome27combinationofmovementofthechromiumwithgroundwater(alsocalledplumemigration),more28comprehensivesamplingofadditionalareassurroundingthepriorplumeboundaries,andimproved29understandingofwherethechromiumoccursindifferentlayersoftheaquiferandhowtosampleto30obtainmaximumconcentrations.Inaddition,groundwatermodelinganalysisofprojectalternatives31hasindicatedthatremediationactivitiesmayresultinpotentialgroundwaterdrawdowninareasfar32outsideofthedefinedplumearea.Theprojectarea,therefore,hadtobeexpandedtobeableto33analyzethesepotentialimpactsoftheremediationactivities.34
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Consequently,thecurrentprojectareafortheEIRanalysisencompassestheplumeareaasofthe1fourthquarterof2011(Q42011),adjacentareastothenorth,eastandwestwheretheplumemay2bedefinedinthefuture(duetomigrationandadditionalinvestigation)andwheremonitoring3activitiesmayoccur,aswellasareasofpotentialeffectsduetogroundwaterpumpingfromthe4remediationalternatives.Thisprojectareathatcouldbedirectlyorindirectlyaffectedbytheproject5isapproximately33squaremiles(21,093acres)insizeandextendsapproximately6milesnorth6and3milessouthofStateRoute58(SR58)atitslongestpoint.Itisapproximately6mileseastto7westatitswidestpoint,andgenerallyboundedbyHinkleyRoadonthewest,MountGeneralonthe8northeast,andtheMojaveRiveronthesoutheast.9
ForthepurposesofEIRanalysis,theprojectareaisalsodiscussedintermsofsub‐areas,which10includethefollowing:11
Plumearea,whichisthegeographicallimitsofknowngroundwatercontaminationasofQ4122011;13
Areasinwhichgroundwatercontaminationmaymigrateorbedetectedasaresultofexpanding14themonitoringwellnetwork;15
Operableunits(OUs),whichareareaswherespecificremedialactivitieswouldcontinueorbe16expandedundertheproject;and17
Potentialareasofdirectandindirecteffectsfromtheremedialactivities,suchasbutnotlimited18togroundwaterdrawdown,impairmentofwaterquality,reductionindomesticwatersupplies,19visualeffects,increasednoiseandtraffic,socioeconomiceffects,lossordisturbanceof20endangeredspecieshabitat;monitoringactivities,constructionofsupportinginfrastructureto21implementremediation(suchaspiping,buildings,ethanol,andequipmentstorage),and22constructionofnewwellstoprovidewatersupplies(forfreshwaterinjection,replacement23water,andextractionandinjectionforcleanup).24
Theprojectareaisalsogenerallydiscussedashavingsouth,central,andnorthsectionsrelativeto25thegeographicportionsoftheplume.ThesouthareaextendsfromRiverviewAvenuenorthto26CommunityBoulevardandcontainsthePG&EHinkleyCompressorStation;thecentralareaextends27fromCommunityBoulevardnorthtoSR58;andthenorthareaextendsfromSR58northtothe28northernlimitoftheprojectarea.29
TheEIRprojectarea,includingthesub–areas,isshowninFigure2‐2a.Detaileddescriptionsofthe30plumeareaandOUsareprovidedbelow.31
2.3.1 Plume Area 32
AsdescribedinChapter1,Introduction,theWaterBoardrequiresPG&Etomonitorandreporton33theconcentrationsoftotalchromium(Cr[T])andCr[VI]presenttoestablishtheextentofwaste34chromiumingroundwater.PG&EhassampledforCr[T]andCr[VI]contaminationlevelsformany35yearsbyinstallingmonitoringwellsthroughouttheprojectarea.Monitoringactivitiesconsistof36samplingofgroundwaterandsoils(i.e.,collectionofgroundwaterandsoilsfortesting)andwater37levelreadings.Datacollectedduringsamplingisusedtodeterminethegeographicalvariancein38contaminationlevelsthatisthenusedtodevelopboundariestorepresentthepresenceofCr[T]and39Cr[VI]contamination.Themaximumextentoftheseboundariesischaracterizedastheplumearea40andthegroundwatercontoursfordifferentlevelsofcontaminationaredepictedonplumemaps.At41present,theplumemapsdepictcontoursrepresentingCr[VI]concentrationsof3.1partsperbillion42
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(ppb,essentiallyequivalenttomicrogramsperliter)(Figure2‐2b),10ppb(Figure2‐2c),and50ppb1(Figure2‐2d).Theseconcentrationsweremappedforthefollowingreasons:2
3.1ppbforCr[VI]–Thiscontourtracestheouterboundaryofwhatisdefinedasthechromium3plumeingroundwaterasoftheFourthQuarter2011.The3.1ppbvalueforCr[VI]was4determinedbasedona2007BackgroundStudyReportconductedbyPG&Ethatevaluated5backgroundlevelsofCr[T]andCr[VI]inareasthatwerethenoutsidetherecognizedplume6area.Theresultsofthatstudyestimatedthatmaximumbackgroundlevelswere3.1ppbfor7Cr[VI]and3.2ppbforCr[T]andtheaveragebackgroundlevelswere1.2ppbforCr[VI]and1.58ppbforCr[T](PacificGasandElectric2007).TheWaterBoardwillusethesevaluesascleanup9targetsfortheremediationunlessanduntilnewevidenceisdevelopedthatbackgroundlevels10aredifferentthanthesecleanuptargets1orPG&Edemonstratesthatbackgroundlevelsofwater11qualitycannotberestored,atwhichtimetheWaterBoardwillidentifythebestwaterquality12achievable,consistentwiththeproceduressetforthinStateWaterResourcesControlBoard13Resolution92‐49(describedindetailinSection2.5below).14
10ppbforCr[VI]–Thiscontourdefinestheportionoftheplumewheremedium‐level15concentrationsoccur.The10ppblevelisnottiedtoaregulatorylevelorabackgroundlevel.16
50ppbforCr[T]orCr[VI]–ThiscontourdefinestheportionoftheplumewhereinCr[T]or17Cr[VI]concentrationsareatorabovetheCaliforniaMaximumContaminantLevel(MCL)of5018ppbforCr[T],whichincludesCr[VI].TheMCListhecurrentdrinkingwaterstandardandisonly19specifiedfortotalchromium,nothexavalentchromium.20
Sinceinitiatingmonitoringactivities,PG&Ehaspreparedquarterlygroundwatermonitoringreports21(GMP)inaccordancewithWaterBoardordersthathavebeenusedtotracktheareaof22contamination.GMPsarealsousedasameanstodetermineeffectivenessofremediationactivities23beingimplementedaswellastheirabilitytomeetinterimremedialtargets.Insamplingfrom24monitoringwellsconductedbetween2006throughthesecondquarterof2010(Q22010),alevelof254.0partsperbillion(ppb)wasusedtodelineatetheextentoftheplumearea.Subsequently,the263.1ppbCr[VI]andCr[T]levelshavebeenusedtodelineatetheextentoftheplumearea.27
Figures2‐2bthrough2‐2dillustratetheprogressionoftheplumeareaboundariesfrom200828throughtheendof2011.29
2.3.2 Operable Units 30
ThreeOUs(OU1,OU2,andOU3)weredefinedtogenerallyrepresentareasinwhichdifferenttypes31ofremedialactivitieswouldbeimplementedinrelationtothevariousgroundwatercontamination32levelsrepresentedbytheplumearea(seeFigures2‐2ato2‐2d).TheOUlocationsandtheir33boundariesaredescribedbelow.Adetaileddescriptionofthetypesofremedialactivitiestobe34implementedwithineachOUisprovidedinSection2.9,Construction,Operation,andMaintenance.35
OU1extendsfromthesourceareainthesouthtotheapproximatenorthernextentofthe50ppb36groundwatercontouroftheplume.TheOU1areaencompassesapproximately1,378acresand37istheareawiththehighestlevelsofchromiumcontamination.Remedialactivities(in‐situ,land38
1AsdescribedinSections1.2.1and3.1,WaterResourcesandWaterQuality,theWaterBoardinitiatedapeerreviewin2011ofthe2007BackgroundStudyReportandisevaluatingthepotentialreevaluationofthe2007dataand/orconductinganewbackgroundstudy.Theseeffortsmayresultinidentificationofdifferentbackgroundlevelsthanthe2007study.
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treatment,andabove‐groundex‐situtreatment)aimedattreatingthehighestconcentration1portionsoftheplumewouldlikelybelocatedwithinOU1.Existingin‐situremediationzones2(IRZs)arelocatedwithinOU1.3
OU2extendsfromthenorthernboundaryofOU1northtoSalinasRoadandcontainsmostofthe410ppbgroundwatercontouroftheplumearea(thatisoutsidethe50ppbcontour).TheOU25areaencompassesapproximately1,715acres.Thisareacontainstheexistingagricultural/land6treatmentunits2,includingtheDesertViewDairylandtreatmentunit,theformerGormanand7Cottrellpropertyagriculturalunits,andtheRanchagriculturalunit.8
OU3encompassestheportionoftheprojectareathatisoutsideofandadjacenttoOU1andOU2.9Thisincludesareaswheretheplumemaymigrate,andfutureremedialactions,monitoring10activitiesanddirectandindirecteffectsofremedialactions(suchasthoseasdescribedabove)11mayoccur.Itispossiblethatthemaximumextentoftheplumeareamaychangecomparedto12thelate2011plumeareaandthatremedialactionsmayultimatelybenecessarybeyondtheOU313boundaryandpossiblyoutsideoftheoverallEIRprojectareaasshowninFigure2‐2a.The14currentOU3areaencompassesapproximately16,765acres.15
Forthepurposesofthisanalysis,remedialactionsareassumedtopotentiallyoccurwithinany16portionofOU3.However,therearepracticalconstraintswithincertainareasincludedinOU3that17mayinfluencewhereremedialactionsaremostlikelytooccur.Forexample,OU3containsareasof18steeplyslopinggroundtothewestandeastoftheHinkleyValley.Itisunlikelythatabove‐groundex‐19situtreatmentfacilitiesoragriculturalunitswouldbeplacedinsuchareas.Similarly,OU3contains20residentialareasnorthoftheHinkleySchoolwheremonitoringwellsmightbeplaced,butitwould21notbefeasibleordesirabletoplaceagriculturalunitsintheseresidentialareas.Themostlikely22areasofremedialactioninOU3arewithintheboundariesoftheplumeasknowninlate2011,23depictedinFigure2‐2a.24
2.4 Existing Conditions 25
AsdiscussedinChapter1,Introduction,theWaterBoardpreviouslyissuedCAOsrequiringactions26topreventplumemigrationandactionstocleanuptheaffectedgroundwater.TheWaterBoard27preparedCEQAdocumentationforallWDRsissuedtoimplementremedialactivities,suchasin‐situ28remediation,agriculturallandtreatment,andfreshwaterinjection.IftheWaterBoardtakesno29furtheractiononthecleanup,PG&EwillstillbeobligatedtofulfillthepriorCAOrequirementsand30canimplementremedialactivitiescurrentlyallowedunderexistingWDRswhosepotential31environmentalimpactswerepreviouslyevaluatedunderCEQA.TheseCEQAdocuments,all32mitigatednegativedeclarations,encompasstheareafromtheCompressorStationto1,000ftnorth33oftheDesertViewDairyonMountainViewRoad,whichisabout3milesinlength.34
SincetheNoticeofPreparation(NOP)oftheEIRwaspublishedinlate2010,theprojectareaandthe35amountofexistingremedialactionshavebothexpanded.Thesechangesneedtobeaccountedfor36whendescribingtheexistingconditionsagainstwhichpotentialenvironmentalimpactswillbe37
2Landtreatmentisperformedbyirrigatinglandwithchromium‐ladenwaterresultingintransformationofdissolvedCr[VI]tosolidCr[III]throughmicrobialactionandchemicalreactionsinsoil.Landtreatmentunitsinvolvedispersingwateronsoilwithorwithoutcrops,whereasagriculturalunitsincludegrowingcrops.TherearemoreagriculturalunitsthanlandtreatmentunitsatpresentandinthealternativesconsideredinthisEIR;theterm“agriculturalunit”issometimesusedtorefertoboth.
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analyzed.Therefore,forthepurposesofthisEIRanalysis,theexistingconditionsaredefinedasthe1physicalconditionsonthegroundasoflate2011.Inordertofullydiscloseproject‐relatedimpacts,2impactsofallprojectalternativeswillbecomparedtotheexistingconditions(late2011)insteadof3physicalconditionsthatwerepresentwhentheNOPwaspublishedinlate2010.4
Table2‐1summarizesandFigure2‐2eshowsthecharacteristicsofexistingremediationactivities5andtheremediationinfrastructurecurrentlyinplaceandoperatingintheprojectarea.Remediation6activitiesforchromiumcontaminationarecurrentlybeingimplementedwherepastandongoing7remediationpilottestingandexperiencehasshowntreatmenttobeeffective.Thecurrenttreatment8approachesandtechnologiesbeingimplementedwithintheprojectareainclude:9
In‐situtreatmentofthehigher‐concentrationplumeintheIRZareaswithinthesouthandcentral10sectionsofOU1.TheIRZareasaregenerallydividedintotheSourceAreaIRZ,theSouthCentral11ReinjectionAreaIRZ,andtheCentralAreaIRZ.Groundwaterextractedwithintheseareasis12carbon‐amended(e.g.,ethanolorlactate)andinjectedineitherarecirculationloop13configurationorasspotinjections(alsoreferredtoasdosed‐injectioninTable2‐1below).14
Plumecontainmentandlandtreatmentusingwaterextractedfromthelow‐concentration15northernandfringeportionsoftheplume.Fiveagriculturalunitsarecurrentlybeingoperated16(2Gorman,1Cottrell,1Ranch,andtheDesertViewDairylandtreatmentunit).Extractionwells17areoperatedtoaugmentcontainmentpumpingandforapplicationofwatertotheagricultural18unitsthroughaconveyancesystemofpiping.19
Plumecontainment(orhydrauliccontrol)usingfreshwaterinjectiontofivewellslocatedinthe20northarea,directlyadjacenttothewesternboundariesofOU1andOU2.Freshwaterisextracted21fromthreesupplywells(PGE‐14,FW‐01,andFW‐02)locatedsouthoftheCompressorStation22property.ThewaterfromwellPGE‐14isfilteredforarsenicandcombinedwiththewaterfrom23theothertwowells,whichhavelowarsenicconcentrations;andthatwaterisconveyedthrough24apipelinetothenorthernfreshwaterreinjectionwells.Theresultinggroundwatermound25createsahydraulicbarrierandpreventsfurtherplumemigrationtothewest.26
Monitoring.Inadditiontothecontainment,landtreatment,andin‐situactivities,PG&Eoversees27anextensivenetworkofmonitoringwells,whicharelocatedthroughouttheprojectarea.28Monitoringwellsareconstructedwithscreensacrossvariousdepthsoftheupperaquiferandin29theloweraquifer.Monitoringactivitiesincludegroundwatersamplingandwaterlevelreadings.30Groundwatersamplingfrequencyrangesfromquarterlytosemi‐annuallyorannually,although31PG&Emaysometimessamplemorefrequentlywhenanewmonitoringwellisinstalled.Water32levelreadingsareconductedconcurrentwiththegroundwatersamplingactivities.Themajority33ofaccessroadstowellsandtheagriculturalunitsarefromsecondarydirtroadsor,where34feasible,frompublicstreets.Existingpublicstreetsarealsousedasthemainpointofaccessto35dirtroads.36
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Table 2‐1. Summary of Remedial Components under Existing Conditions 1
AgriculturalLandApplicationAgriculturalUnits 182acaAgriculturalUnitExtractionWells 29Trenches(maycontainmultiplepipelines) 24,499linearfeet(lf)AgriculturalUnitExtractionflowb,c 1,100gpmIn‐SituRemediation(IRZ)
ExtractionWells 12InjectionWells 58Pipelines 14,985lfCarbon‐amendedIRZflow(SouthCentralAreaIRZ,SourceAreaIRZ)c
190gpm
IRZrecirculationflow(CentralAreaIRZ,SourceAreaIRZ)c
83gpm
NorthwestFreshwaterReinjectionExtractionWells 3InjectionWells 5Pipelines 31,886lfFreshwaterinjectionflowc 80gpmMonitoringWellsandOtherInfrastructureMonitoringWells 434WellsandSupportinginfrastructured 36acresAccessroads 1acreNotes:a AgriculturalUnitsincludetheDesertViewDairy+4pivots[Gorman(2),Cottrell,Ranch])b Flows(gpm)forDesertViewDairylandtreatmentunitareincludedinagriculturalunittreatmentflowsforallalternatives.
c Allflowsareaverageannualpumpingrates.d Includesareaforagriculturalunits,IRZ,andnorthwestreinjectionwellsaswellasmonitoringwells.
2.5 Whole‐House Replacement Water 2
AsdescribedinSection1.2.1,TimelineofActivities,inChapter1,Introduction,PG&Eisrequiredto3provideinterimandwholehousereplacementwaterservicetothoseservedbydomesticor4communitywellsthatarewithintheaffectedareaofthechromiumplumeanddeterminedtobe5impactedbythePG&Echromiumdischargeforallindooruses,includingdrinking,cooking,bathing,6andhygiene(CAONo.R6V‐2011‐0005A1andR6V‐2011‐0005A2).Thisorderappliestoalldomestic7supplywellsaffectedbyPG&E’swastedischargeofchromiumwithin1miledowngradientorcross8gradientfromthemostrecentplumeboundary,definedbythemaximumbackgroundchromium9concentrations,currently3.1ppbCr[VI]/3.2ppbCr[T].10
2.5.1 Affected Wells Eligible for Replacement Water 11
CaliforniaWaterCodesection13304(a)allowstheWaterBoardtorequirereplacementwaterfor12wells“affected”byadischargeofwaste.“Affectedwells”arethosethatdonotmeetfederal,state13
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andlocaldrinkingwaterstandards.Wherenofederal,state,orlocalstandardyetexists,asisthe1situationforhexavalentchromium,theStateWaterBoardWaterhasconcludedthat“itis2appropriatetousegoalsdevelopedbyagencieswithexpertiseforpublichealthdeterminationsin3decidingwhetherreplacementdrinkingwaterisnecessary”(WaterQualityOrder2005‐007,the4“OlinOrder”).5
BecausenoMCLforhexavalentchromiumhasbeenset,theWaterBoardisrelyingonthePublic6HealthGoalof0.02ppbhexavalentchromiumtodetermine“affectedwells”requiringreplacement7waterpursuanttoCAOR6V‐2011‐0005A2.Duetothecurrentlimitationsoflaboratoriestodetect8hexavalentchromiumdowntothePublicHealthGoalof0.02ppb,affectedwellsarethosethat9containanyhexavalentchromiumabovethecurrentlaboratorydetectionlimit,whichis0.06ppb.10
2.5.2 Replacement Water Provision before an MCL is Adopted 11
CAOR6V‐2011‐0005A2addressesimpactstowatersupplywellsfromtheexistingchromiumplume,12whicharenotconsideredimpactsunderCEQAbecausetheywerenotcausedbytheimplementation13oftheproject(remedialactivities).Thechromiumplumeingroundwaterispartofthebaselineor14existingconditionsoftheprojectareacausedbypastactionsofPG&Ewhenwastechromiumwas15dischargedtogroundwaterinthe1950sand1960s.Thatdischargeofwasteissubjecttoregulatory16andenforcementactionsbytheWaterBoard,suchasCAOR6V‐2011‐0005A2,butisnotanimpact17oftheprojectunderCEQAbecauseitisnotcausedbytheproject(where,ashere,theprojecthereis18tocleanuptheplume).19
ThereplacementwatersupplyprogramrequiredbyR6V‐2011‐0005A2willcontinue,ataminimum,20untilafinalMCL(ordrinkingwaterstandard)forhexavalentchromiumisadoptedbytheCalifornia21DepartmentofPublicHealth(CDPH).22
AsdiscussedinSection3.1,WaterResourcesandWaterQuality,ifremedialactivitiessignificantly23affectwaterqualityconditionsforwatersupplywells,replacementwaterwillalsoberequiredas24mitigationforremedialimpacts.25
2.5.3 Replacement Water Provisions after an MCL is Adopted 26
AfterCDPHadoptsanMCLforhexavalentchromium,requirementspertainingtoprovidingwhole‐27housereplacementwatertoaffectedwellswillonlyapplytolocationswithwellscontaining28hexavalentchromiumatlevelsabovetheMCLlevelestablishedbyCDPH.Atthattime,PG&E’s29obligationunderCAOR6V‐2011‐0005A2toprovidewholehousereplacementwaterceasesfor30thoselocationswithfourconsecutivequartersofhexavalentchromiumdetectionswhichdonot31exceedtheMCL.32
AsdiscussedinSection3.1,WaterResourcesandWaterQuality,ifremedialactivitiessignificantly33affectwaterqualityconditionsforwatersupplywells,replacementwaterwillalsoberequiredas34mitigationforremedialimpacts.35
2.6 Project Goal and Objectives 36
Thefollowingprovidesabriefcontextforthediscussionoftheprojectgoalandobjectives.37
California Regional Water Quality Control Board, Lahontan Region Project Description
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The2008CAONo.R6V‐2008‐0002requiredPG&EtosubmitafeasibilitystudybySeptember1,12010(the2010FeasibilityStudyisdescribedinmoredetailinSection2.6below)thatassessed2remediationstrategiesforchromiumandproposedafinalgroundwaterremediationproposalto3achievecompliancewithStateWaterResourcesControlBoard(SWRCB)Resolution92‐49,“Policies4andProceduresforInvestigationandCleanupandAbatementofDischargesUnderWaterCode5Section13304”(Resolution92‐49).6
Resolution92‐49requiresadischargerto:7
Developacleanupplanthatevaluatesmultipleremediesandweighsthemagainstnumerous8factorssuchas:9
Abilitytoachievebackgroundlevels;310
Timeframetoachievebackgroundlevels;and11
Potentiallysignificantimpacts.12
Proposeacleanupplanthateithertargetsgroundwatercleanuptobackgroundlevelsor13providestheappropriatejustificationforahigherstandard;and14
Considerwhatisreasonablewhenevaluatingacleanupgoal,takingintoaccountthetechnical15andeconomicfeasibilityofattainingbackgroundconditions,theprojectedtimeframetoachieve16backgroundconditions,andthemaximumbeneficialuseoftheresourcebeingprotected.17
2.6.1 Project Goal 18
Thegoaloftheprojectistorestoregroundwaterqualitytobackgroundlevelsofchromiuminthe19minimumamountoftimepracticable,whilelimitingormitigatingenvironmentalimpactsassociated20withthecleanupactivities.21
TheWaterBoardhastheauthoritytorequirecleanupofanygroundwateraffectedbychromium22dischargedfromPG&E’sHinkleyCompressorStation.Groundwaterisconsideredtobeaffectedby23PG&E’sdischargeifthelevelsofchromiumareabovenaturallyoccurringbackgroundlevelsasa24resultofCompressorStationoperations.25
ForthisEIR,theanalysislooksatcleanuptothechromiumbackgroundlevelssetinCAONo.R6V‐262008‐002A1because,inpart,PG&E’sfeasibilitystudyandaddendahaveconsideredcleanupto27thoselevelsandthatanalysishasgenerallyshownthatitispossibletomeetthoselevels.Inthe28future,theWaterBoardmayidentifyadifferentbackgroundlevelandmaysetcleanuplevelsto29meetthatnewbackgroundlevel.IfPG&Eisabletoshowthatitisnotfeasibletorestorewater30qualitytobackgroundlevels,theWaterBoardmayrequirecleanuptothebestwaterquality31reasonablyachievable,afterconsideringanumberoffactorsidentifiedinStateWaterResources32ControlBoardResolution92‐49,subsectionG.Aslongastheremedialactivitiesthatwouldbe33necessarytomeetanynewcleanupobjectivesaresimilartothoseanalyzedinthisEIRandany34associatedenvironmentalimpactsdonotexceedwhathadbeenanalyzedinthisEIR,theWater35Board’sconsiderationoftherevisedcleanupobjectivesandapprovalofneworamendedWDRscan36relyuponforCEQAcompliancetheevaluationinthisdocument.37
3Theterm“backgroundlevel”referstothewaterqualitythatexistedbeforethedischarge.
California Regional Water Quality Control Board, Lahontan Region Project Description
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2.6.2 Project Objectives 1
Thespecificprojectobjectivesareto:2
Containthecontaminatedgroundwaterplumehorizontallyandverticallyimmediatelyand3continuouslyintheareadescribedintheamendedCAONoR6V‐2008‐0002A3.4
Containthecontaminatedgroundwaterplumeoverall.5
Reducemaximumgroundwaterconcentrationsto3.2ppbCr[T]and3.1ppbCr[VI]asdescribed6inCAONo.R6V‐2008‐0002A1.7
Reduceaveragegroundwaterconcentrationsto1.2ppbCr[VI]and1.5ppbCr[T],asdescribedin8CAONo.R6V‐2008‐0002A1.9
Restorebeneficialusesofthegroundwaterbyachievingthecleanuplevelsnotedaboveinthe10minimumtimefeasible.11
Limitormitigateenvironmentalimpactsassociatedwiththecleanupactivities.12
Overall,theseobjectivesareintendedtoreducechromiumconcentrationsingroundwatertothe13cleanuptargetsandcontainthegroundwaterplume.4Developmentoftheseobjectivestakesinto14considerationtheavailabletechnologies,recoveryofbeneficialuses,short‐termeffectiveness,long‐15termeffectiveness,andcommunityconcerns.Together,theseobjectivesareintendedtorestore16beneficialuses5tothegroundwateraquifer.17
2.7 Development of Project Alternatives 18
DevelopmentoftheprojectalternativesbytheWaterBoardwasprimarilybasedontheWater19Board’sindependentreviewofinformationcontainedinthe2010FeasibilityStudy6andits20Addendum1and2,theinputandsuggestionsofthepublic(asdescribedinChapter1,Introduction),21independentreviewofthefeasibilitystudyandaddendabytheU.S.EnvironmentalProtection22AgencyandtheCaliforniaDepartmentofToxicSubstancesControl,aswellasinformationbasedon23previousandexistingPG&EremedialpilotprojectsinHinkley.Thefeasibilitystudyanditsaddenda24provideextensivedetailregardingthepotentialtechnologies,theireffectivenessatmeetingcleanup25objectives,andlogistical,technological,andeconomicfeasibility.26
The2010FeasibilityStudyinitiallyscreened36chromiumcleanuptechnologies/approaches(also27referredtoasremediationoptionsortreatmentapproaches)withpotentialtobefeasibleand28
4Minorexpansionofthechromiumplume,incidentaltotheremediation,suchaslimited“bulging”duetoinjectionofwaterassociatedwithremediationactivitieswouldbeconsistentwiththeseobjectivessimilartotheminorexpansion(upto1,000feet)allowedbyAmendedCAONo.R6V‐2008‐0002A2providedthatchromiumwillbecapturedbythegroundwaterextractionsysteminthedowngradientflowdirection.5DesignatedbeneficialusesfortheHinkleyaquiferintheBasinPlan(seediscussioninSection3.1)include:municipalanddomesticsupply;agriculturalsupply;industrialservicesupply;freshwaterreplenishment;andaquaculture.6Apriorfeasibilitystudywascompletedin2002andwasalsoconsideredbyWaterBoardstaff,butthe2010feasibilitystudy(anditsaddenda)isamorecomprehensiveevaluationofpotentialremedialapproachesfrom2002through2010andistheprimarysourceofinformationusedtohelpdefineprojectalternatives.The2002feasibilitystudyisavailablefromtheWaterBoarduponrequest.
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effectiveforcontainmentandcleanupoftheplume(PacificGasandElectric2010).These361technologiescangenerallybecategorizedintothefollowingremedialapproaches:2
PlumeContainmentthroughGroundwaterExtraction:Extractingcontaminated3groundwaterattheouteredgeoftheplumetopreventfurtherspreadingoftheplume.4
PlumeContainmentthroughCleanWaterInjection:Injectingclean(non‐contaminated5water)attheouteredgeoftheplumetocreateahydraulicbarriertopreventfurtherspreading6oftheplume.7
GroundwaterExtractionandLandTreatment(withAgriculturalReuse):Extracting8contaminatedgroundwaterandapplyingittolandwheresoilmicrobialactionwillreduce79dissolvedCr[VI]tosolidCr[III].10
Plume‐wideIn‐SituTreatment:Throughouttheplume,injectingbiologicalandchemical11reductants(food‐gradecarbonsourcessuchasethanolorlactate)directlyintothe12contaminatedgroundwatertopromotemicrobialreductionofCr[VI]toCr[III]withinthe13aquifer.Cr[III]hasverylowtoxicityandisanessentialdietarynutrient.Itistypically14immobilizedinsoilsandtendsnottodissolveeasilyingroundwater.15
Plume‐core8OnlyIn‐SituTreatment:Onlyinthesourcearea(i.e.,OU1),injectingbiological16andchemicalreductantsdirectlyintothecontaminatedgroundwatertopromotemicrobial17reductionofCr[VI]toCr[III]withintheaquifer.18
Ex‐SituTreatment(i.e.,above‐ground)andDischargetoLand:Extractingcontaminated19groundwaterandphysicallyseparatingCr[VI]fromthewater,disposingoftheprecipitated20Cr[VI]offsite,anddischargingthetreatedwatertoland.Alternatively,ex‐situtreatmentcould21usebiologicalandchemicalreductantstoreduceCr[VI]toCr[III]incontaminatedwaterand22thendischargethetreatedwatertoland.23
Ex‐SituTreatmentandInjectiontoGroundwater:Extractingcontaminatedgroundwaterand24physicallyseparatingCr[VI]fromthewater,disposingoftheprecipitatedCr[VI]offsite,and25injectingthetreatedwaterdirectlyintotheaquifer.Alternatively,ex‐situtreatmentcoulduse26biologicalandchemicalreductantstoreduceCr[VI]toCr[III]incontaminatedwaterandthen27injectthetreatedwaterdirectlyintotheaquifer.28
Manyofthetechnologiesstudiedinthefeasibilitystudyandaddendawereincludedinoneormore29ofthealternativesevaluatedinthefeasibilitystudyand/orincludedintheprojectalternatives30evaluatedinthisEIR.Someoftheapproacheswerenotadvancedfurtherandarenotconsideredin31detailinthisEIR.Section2.10belowdiscussesthereasonswhycertaintechnologies/approaches32werenotstudiedfurther.33
7“Reduce”inthiscontextreferstoachemicalreactionthataddselectronstoachemicalspecies.Chromiumhas24protonsand24electronsinitsneutralstate.Cr[VI]has24protons,butonly18electronsandanoxidationstateof+6.Cr[III]has24protonsand21electronsandanoxidationstateof+3.Inthiscase,reductionofCr[VI]toCr[III]meansthatthechemicalreactionadds3electronstoeachCr[VI]moleculewhichreducesitsoxidationstatefrom+6to+3,therebyconvertinghexavalentchromiumtotrivalentchromium.8Theterm“plume‐core”isonlyusedtorefertothetechnologiesconsistentwiththeterminologyusedinthefeasibilitystudy.
California Regional Water Quality Control Board, Lahontan Region Project Description
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2.7.1 2010 Feasibility Study (September 2010) 1
Inthe2010FeasibilityStudy,theselectedtechnologieswerecombinedtoformfivealternativesto2addressthechromiumcleanupgoalsspecifiedintheprojectobjectives.Thesefivealternativeswere3asfollows:4
FeasibilityStudyAlternative1.Nofuturepumpingorgroundwatertreatment;cleanup5achievedthroughnaturalattenuation.Estimatedtimetocleanupto3.1ppbCr[VI]:>1,000years6
FeasibilityStudyAlternative2.Containmentbyinjectingfreshwateratthetoeoftheplume7andlandtreatment.Estimatedtimetocleanupto3.1ppbCr[VI]:260years8
FeasibilityStudyAlternative3.Plume‐widein‐situtreatmentusingexistingandnew9proposedinjectionwells.Estimatedtimetocleanupto3.1ppbCr[VI]:110years10
FeasibilityStudyAlternative4.In‐situtreatmentinOU1andlandtreatmentusingoneexisting11andonenewagriculturalunit.Estimatedtimetocleanupto3.1ppbCr[VI]:150years12
FeasibilityStudyAlternative5.Plume‐widepumpandtreatex‐situ,usingexistingandnew13injectionandextractionwellsandnewabove‐groundtreatmentfacilities.Estimatedtimeto14cleanupto3.1ppbCr[VI]:140years15
BasedontheWaterBoardstaff’sindependentreviewofthe2010FeasibilityStudy,itwas16determinedthatnoneofthefiveprimaryalternativesdescribedabovemettheprojectgoaland17objectivesforthefollowingreasons:theproposedtimeframesforcleanupandbeneficialuses18restorationachievedbythefiveoriginalalternativesweretooslow;thealternativesdidnotappear19tocleanupcontaminationintheminimumtimefeasible;andduetoalargerplumeareainlate202011/early2012thanin2010,noneofthefiveoriginalalternativeswerespecificallydesignedto21containthelargerplume.22
TheWaterBoardstaffrequestedPG&Etodevelopadditionalalternativesthatincludedplume23containment,ex‐situtreatment,in‐situtreatment,andlandtreatmentthatcouldachievecleanup24fasterandcontrolplumemigrationbetterthanthefive2010FeasibilityStudyalternatives.25
2.7.2 2010 Feasibility Study Addendum 1 and Addendum 2 26
(January/March 2011) 27
BasedonWaterBoarddirection,PG&Edevelopedtwoadditionalalternativestoaccelerate28groundwatercleanupandtoprovidemorecomprehensiveplumecontainment,whichwerethebasis29ofFeasibilityStudyAddendum1(PacificGasandElectric2011a).30
Alternative4A:Hydrauliccontainmentofthechromiumplumethroughgroundwater31extractionandinjection,in‐situtreatmentusingIRZchromiumconversionfromCr[VI]toCr[III],32andtreatmentofaportionoftheextractedgroundwaterinagriculturalfields.Alternative4Ais33enlargedinscaleoverthe2010FeasibilityStudyAlternative4byanincreaseintheCentralArea34IRZ,expansionofagriculturalunits,increasedIRZoperationsby15years,andincreased35volumesofgroundwaterextractionforapplicationtoexpandedagriculturalunits.Estimated36timetocleanupto3.1ppbCr[VI]:75years37
CombinedAlternative:Hydrauliccontainmentofthechromiumplumethroughgroundwater38extractionandinjection,corein‐situtreatment,above‐groundtreatmentofthehigh39concentrationportionoftheplume,groundwaterextractionandlandtreatmentofthelow40
California Regional Water Quality Control Board, Lahontan Region Project Description
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concentrationportionoftheplumethroughexpandedagriculturalunitstoachievetheproject1objectives.Estimatedtimetocleanupto3.1ppbCr[VI]:90years2
Uponreviewoftheeffectivenessofthesealternatives,theWaterBoardrequestedthatPG&E3investigateoptionstousetechnologiesemployedinAlternative4Atofurtherreducethetime4necessarytomeettheprojectobjectivesandtoprovideformorecomprehensiveplumecontrol.Asa5result,PG&EissuedaFeasibilityStudyAddendum2(PacificGasandElectric2011b)thatdescribed6Alternative4B.7
Alternative4B.ThisalternativeusesthesameapproachasAlternative4A,butitincludes8additionalextractionwellsforagriculturallandtreatmentandotherfacilitiesthatmore9effectivelyremovetheCr[VI]contaminationthanAlternative4Aandsignificantlyaccelerates10cleanuptimes.Estimatedtimetocleanupto3.1ppbCr[VI]:40years11
2.7.3 2010 Feasibility Study Addendum 3 (September 2011) 12
FollowingreviewofFeasibilityStudyAddendum2,theWaterBoardsolicitedinputfromthe13CaliforniaDepartmentofToxicSubstancesControl(DTSC)andtheU.S.EPAonthe2010Feasibility14Study,FeasibilityStudyAddendum1,andFeasibilityStudyAddendum2.Basedonthisinputand15review,theWaterBoardrequestedPG&Etodevelopfurtheroptionstoimplementaprogramthat16maintainedmaximumyear‐roundpumpingandplumecontainment,evaluatedtheneedforand17effectivenessofvaryingpumpingschedules,furtherevaluatedthepotentialforadditionalcleanup18time‐framereductionfromthatestimatedunderAlternative4B,developedmilestonesforcleanup19ofdifferentparts(or“operableunits”)oftheplume,developedoptimizationperiodstofacilitate20adaptivemanagementoftheremedialactivities,andestablishedacontingencyplantomaintain21year‐roundplumecapture.Optimizationreferstochangesthatwouldbemadeintheremediation22systemconfiguration(e.g.,changeextractionwelllocations)tomaximizeremediationasplume23cleanupprogressesandtheplumeshapechanges.24
InresponsetotheWaterBoard’srequest,PG&Edevelopedfouradditionalalternativesaspartof25FeasibilityStudyAddendum3(PacificGasandElectric2011c)thatusedthesamegeneral26remediationtechnologiesasthepreviouslystudiedAlternative4Bwiththeadditionof27extraction/treatmentfeaturesandincreasestoextractionflowrates,continuousyear‐round28pumpingforenhancedyear‐roundhydrauliccontrol,winter‐cropagriculturalunitoperation,and29theconsiderationofwinterwatertreatmentbyanex‐situ(above‐ground)treatmentplant.The30purposeoftheex‐situtreatmentapproachistomaintainfixedrate,year‐roundextractionrates31sincetheagriculturalunitshaveareducedcapacitytotreatwateronaper‐acrebasisduringwinter32monthswhenlesswatercanbeabsorbed.Theadditionalalternativeswere:33
Alternative4C‐1.In‐situandenhancedagriculturaltreatment,includingadditionalextraction34wellsandagriculturalunitsandassociatedinfrastructurewithhigherextractionrates.Onlyone35cropwouldbeusedforeachagriculturaltreatmentunit,resultinginseasonalfluctuationsin36flowrates.Estimatedtimetocleanupto3.1ppbCr[VI]:40years37
Alternative4C‐2.Samein‐situandenhancedagriculturaltreatmentasAlternative4C‐1,except38awintercropwouldbeaddedtoincreaseextractionratesinwinterrelativetoAlternative4C‐2.39Estimatedtimetocleanupto3.1ppbCr[VI]:39years40
Alternative4C‐3.Samein‐situandenhancedagriculturaltreatmentasAlternative4C‐2with41operationsduringsummerandwinterandtheadditionofex‐situtreatmentwithadditional42
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
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injectionwellstoaccommodatetheexcessflowfromtheagriculturalunitsinthewinterinorder1tomaintainacontinuousextractionflowyear‐round.Estimatedtimetocleanupto3.1ppbCr[VI]:236years3
Alternative4C‐4.Samein‐situasAlternative4C‐2withsubstantiallyexpandedagriculture4operationsoccurringduringsummerandwinter,withadditionofnewagriculturalunitsfor5winter‐onlyoperationsinlieuofex‐situtreatmentinordertomaintaincontinuousextraction6flowyear‐round.Estimatedtimetocleanupto3.1ppbCr[VI]:29years7
AfterreviewofFeasibilityStudyAddendum3,theWaterBoardrecommendeddevelopmentofa8moreaggressivecombinedalternativethatapproximatelymatchedthecleanuptimeframeof9Alternatives4C‐1through4C‐4whileprovidingforremovalofchromiumfromtheaquiferinthe10highconcentrationportionoftheplume.PG&Edevelopedanew“Alternative4C‐5”inMarch2012to11respondtotheWaterBoard’srecommendation.12
Alternative4C‐5.Thisalternativecombinesthein‐situandlandtreatmentapproaches13proposedunderAlternative4C‐2withex‐situapproachesproposedundertheprevious14CombinedAlternativetoremovechromiumfromtheoverallsitefromthehighconcentration15portionoftheplume.Estimatedtimetocleanupto3.1ppbCr[VI]:50years16
2.8 Scaling Approach to Address Recent Plume 17
Changes 18
Thefeasibilitystudyevaluations(andaddenda)werebasedonthecontaminatedplumeasitwas19definedatthetimeoftheevaluation.ThecurrentchromiumplumeasofQ42011isapproximately202,949acres,whichismuchlargerthantheplumethatwasstudiedinthefeasibilitystudyas21describedbelow:22
Alternative4B.FeasibilityStudyAddendum2usedtheQ12010plumeasitsbaseconditionfor23studyforAlternative4B.TheQ12010plume(definedbythe3.1ppbCr[VI]contour)was24approximately1,225acresinsize.25
Alternative4C‐1toAlternative4C‐5.Asnotedabove,FeasibilityStudyAddendum3studied26boththeQ12010plumeandtheQ12011plume.Addendum3(andsubsequentdataprovided27byPG&E)presentedanidentificationofinfrastructureneededtoaddresstheQ12011plume.28TheQ12011plume(definedbythe3.1ppbCr[VI]contour)wasapproximately1,788acresin29size.30
Thefullextentoftheplumeareacannotbedefinedatthistimebecausetheplumeboundarymaybe31largerthantheQ42011delineatedboundaryasaresultoffurtherinvestigationand/orplume32migration.Therefore,forthisEIR,ithasbeenassumedthatthecontaminatedplumemaybelarger33byupto15%fromtheQ42011plume,whichwouldresultinatotalplumeareaof3,391acres.This34plumeareaisapproximately190%largerthantheQ12011plumeand277%largerthantheQ1352010plume.36
Toprovideanestimateofthepotentialexpandedamountofremedialactivitythatmaybenecessary37toaddressafutureplumethatissubstantiallylargerthanthatusedasthebaseconditionfor38identificationofremedialactivitiesproposedinthefeasibilitystudy(andaddenda),thefeasibility39studyestimatesofremedialactivitywerescaledasfollows:40
California Regional Water Quality Control Board, Lahontan Region Project Description
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NoProjectAlternative.TheNoProjectAlternativewasnotscaledupasitispresumedthat1remedialactivitywillbelimitedtotheareaoftheplumeasidentifiedbetween2008and2010.2
AgriculturalLandTreatment.Agriculturalunitacreages,piping,wells,andextractionflows3werescaledupbyincreasingthefeasibilitystudyamountstoincludeadditionalagriculturalunit4acreage,infrastructure,andflowstotreattherevisedplumearea.5
In‐SituRemediation.In‐situremediationisprimarilyproposedtoaddressthehigh6concentrationpartoftheplume(>50ppb)andsomeofthemediumconcentrationpartofthe7plume(>10ppb).The50ppbplumeboundaryhasbeenmostlystableinrecentyearsdueto8remedialactions.The10ppbplumeboundaryhasexpandedbutnottothesamedegreeasthe93.1ppbplumeboundary.Asaresult,scalingforin‐situremediationwells,piping,andflows10utilizeda25%factorinsteadofscalingbasedonplumesize.11
Ex‐SituRemediation.Ex‐situremediationisproposedinAlternative4C‐3tomaintainyear‐12roundpumpingratesandwinterhydrauliccontrolandtreatment,andthusex‐situremediation13activityforAlternative4C‐3wasscaledusingthesamemethodsasforagriculturalland14treatment.Ex‐situtreatmentisproposedinAlternative4C‐5fortreatmentofthehigh15concentrationplume(>50ppb)area.Sincethehighconcentrationplumeareahasbeenmoreor16lessstableduetocurrentremedialactions,noscalingwasappliedforex‐situtreatmentin17Alternative4C‐5,butascalingfactorof25%wasincludedforthepurposesofEIRanalysisinthe18eventthathigherpumpingratesmaybeneededtosupportremedialgoals.19
FreshwaterInjection.Todate,freshwaterinjectiononthenorthwestsideoftheplumehas20beeneffectiveatcontrollingfurtherwestwardmigrationoftheplumeanddeflectingits21movementnorthward.Thus,itwasassumedthatasimilaramountoffreshwaterinjectionwould22beusedinallalternativesinthefuture.Ascalingfactorof15%wasusedinordertocover23potentialexpansion,shoulditbeneeded,totheexistingamountsforEIRanalysis.24
MonitoringWells.Astheplumehasexpanded,thenumberofmonitoringwellshasalso25expanded.PG&Eoriginallyincludedanadditional12monitoringwellsaboveexistingwells.In26ordertocoverpotentialmonitoringwellneedstoaddressanexpandingplume,ascalingfactor27of25%wasaddedtotheexistingandprojectednumberofmonitoringwellsfortheEIRanalysis.28
Inthealternativedescriptionsbelow,referencetoagriculturalacreages,wells,pipinglengths,and29flowsaretothescaledtotals,nottheoriginalfeasibilitystudytotal.Tablesthatsummarizethe30originalfeasibilitystudytotalsforeachalternativeandshowthespecificscalingadjustmentsto31accountfortheexpandedplumearepresentedinAppendixB.32
2.9 Project Alternatives 33
Basedonthereviewofthefeasibilitystudy(andaddenda),inputfromEPAandDTSC,public34commentandreviewofremediationexperiencesofpriorpilottestsandremediationactivitiesatthe35sitetodate,theWaterBoardselectedthemostpromisingfiveprojectalternativestoanalyzeinthis36EIR,inadditiontotheCEQArequiredanalysisoftheNoProjectAlternative.Table2‐2identifiesthe37keyfeaturesoftheanalyzedalternatives.Eachalternativeisfurtherdescribedbelow.38
Table 2‐2. PG&E Hinkley Groundwater Remediation Alternatives Analyzed in the EIR 1
Alternatives NoProjecta 4B 4C‐2 4C‐3 4C‐4 4C‐5SourceofInformation FSAddendum3 FSAddendum2 FSAddendum3 FSAddendum3 FSAddendum3 FSAddendum4PlumeFSanalysisbasedon Q1/2011 Q1/2010 Q1/2011 Q1/2011 Q1/2011 Q1/2011OU1–RemedialMethodforHighConcentrationPlume
In‐Situ In‐Situ In‐Situ In‐Situ In‐Situ Above‐ground/In‐situ
Timeto50ppb 6b 6 6 4 3 20Timeto80%Cr[VI]MassConversiontoCr[III]orRemoval
13b 10 7 6 6 15
OU1/2/3–Remedialmethodforlowconcentrationplume
IRZ/AUsc
IRZfor20yearsAUsfor95years
IRZfor20yearsAUsfor90years
IRZfor20yearsAUsfor85years
IRZfor20yearsAUsfor75years
IRZfor32yearsAUsfor95years
Timeto3.1ppbcleanup NAc 40 39 36 29 50Timeto1.2ppbcleanup NAc 95 90 85 75 95FateofCr3+inthesoil Leaves Leaves Leaves Leaves Leaves Removesfromhigh
concentrationareaAUPumpingRatesc 1,100gpm(FS) 1,270gpm(FS)
2,395gpm(total)2,042gpm(FS)3,167gpm(total)
2,829gpm(FS)4,388gpm(total)
2,829gpm(FS)4,388gpm(total)
2,042gpm(FS)3,167gpm(total)
AUsd,e 182acres 222acres(FS)/446acres(total)
351acres(FS)/575acres(total)
351acres(FS)/575acres(total)
895acres(FS)/1,394acres(total)
351acres(FS)/575acres(total)
FSEstimatedCosts(NPV)f N/A $84.9M $118M $276M $173M $171MKeyFeature RequiredbyCEQA Lessgroundwater
pumping,AUacreageandlowercost.
Yearroundpumpingforplumecontrol(winterCrop).
Yearroundpumpingforplumecontrol(winterabove‐groundtreatment).
Yearroundpumpingforplumecontrol.Fastestcleanupofallalternative.
Removalofchromiumfromthehighconcentrationplumearea.
Notes:a NoProjectAlternativedefinedbasedontheNoProjectdetailsprovidedforAlternative4C‐2inFSAddendumNo.3.b BasedonFSAlternativeNo.4cleanuptimesbecauseFSAddendumNo.3didnotidentifycleanuptimesforNoProjectconditions.c NoProjectAlternativelimitedtoaddressingthe2008–2010plume.Thus,nodurationforcleanupofentireplumeisidentified.d Twopumpingratesshownforactionalternatives.FirstishighestpumpingrateintheFS/Addendamarkedwitha(FS).SecondisscaleduptoaccountforexpandedplumebeyondthatatthetimeoftheFS/Addenda.
e Twoacreagesshownforagriculturalunitsforactionalternatives.FirstisfromtheFS/Addendamarkedwitha(FS).SecondisscaleduptoaccountforexpandedplumebeyondthatatthetimeoftheFS/Addenda.
f CostsarebasedonFS/Addendacoststoremediateto1.2ppbCr[VI]levelandonlyincludetheinfrastructuredescribedintheFS/Addendaanddonotaccountfortheadditionalcostfortheinfrastructureandactivitiestoaddresstheexpandedplume.
AU = AgriculturalUnitsFS = FeasibilityStudygpm = gallonsperminuteIRZ = In‐SituRemediationNPV = Netpresentvalueppb = partsperbillion
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐15 August 2012
ICF 00122.11
Thedescriptionofremedialactionsundereachalternativeisidentifiedbyphases,includingtheyear1thatanactionwouldbeinitiatedandtheperiodoftimeitwouldbeimplementeduntilcleanupis2achieved.Forallalternatives,theoverallphasesare:3
InitialBuildout(0–5years)4
Years5to105
Years10to206
BeyondYear207
2.9.1 No Project Alternative 8
UndertheNoProjectAlternative,theWaterBoardwouldnotadoptanewCAO(andassociatedsite‐9wideWDRs)andthepriorauthorizationswouldcontinuetobeusedforcleanupactivities.Thecurrent10remediationactivitiesthatwouldcontinuetobeimplementedundertheNoProjectAlternativeare11describedbelow.Table2‐3summarizestheremedialactionsfortheNoProjectAlternative,and12Figure2‐3showsthelocationsofwhereremediationactivitieswouldbeimplemented.13
PlumeContainment.Plumecontainmentwouldcontinueviafreshwaterreinjectionand14northernlandtreatment.FreshwaterwouldbepumpedfromthethreeexistingPG&Esupply15wellslocatedsouthoftheCompressorStationandpipedtothefivereinjectionwellslocated16northwestoftheplumeatthecurrentlyauthorizedvolumesandrates(80gpm).Landtreatment17viatheDesertViewDairyandfouragriculturalunits(describedbelow)wouldcontinueasunder18existingconditions.19
LandTreatmentattheDesertViewDairyandFourAdjacentParcels.Extractionoflow20concentrationCr[VI]groundwaterandlandapplicationattheDesertViewDairyandthefour21agriculturalunits(ontheGorman[northandsouth],Cottrell,andRanchproperties)within22OU1/OU2wouldcontinueatthecurrentvolumesandrates(1,100gpm).23
In‐SituTreatment.In‐situtreatmentwithintheSource,Central,andSouthCentralIRZareas24usinginjectionofreductantsintothecontaminatedaquifertoconvertdissolvedCr[VI]tosolid25Cr[III]wouldcontinue.In‐situoperationswouldcontinueviapumpinggroundwaterfrom26extractionwells,mixinggroundwaterandreagentsinmixingtanks,andinjectionofthemixture27intoinjectionwells.Biological(i.e.,carbon‐amended)andchemicalreductantsareinjectedby28manualorsemi‐automatedrecirculationsystems,ormanuallyusingtemporarywellpointson29directinjectionmethods.TherearecurrentlytwoIRZcompoundsthatincludeequipment,tanks,30andwells,withfootprintofnomorethan100by200feetinareaand20feetinheight31surroundedbyfencesupto12feethigh.Additionally,therearealmost30smallerabove‐ground32compounds(withapproximately20by20feetfootprint)forextractionwells,and5similar33smallcompoundsforinjectionwellsdealingwiththewesternbulge.Allcompoundshave34approximately12‐foothighfenceswithbrown‐coloredslats.Alsoincludedareconveyance35pipelinesforin‐situtreatment.36
Authorizedchemicalreductantsusedforin‐situtreatmentandgroundwaterinjectionforabove‐37groundtreatmentincludecalciumpolysulfide,ferrouschloride,ferroussulfate,sodium38dithionite,andzero‐valentiron.Biologicalreductantsincludeemulsifiedvegetableoil,ethanol,39lactate,whey,molasses,cornsyrup,acetate,glucose,andmethanol.Onlysomeofthese40biologicalreductantshavebeenusedtodate.Authorizedoperationandmaintenance(O&M)41activitiesincludedischargesoftracercompounds,well‐rehabilitationcompounds,process42
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐16 August 2012
ICF 00122.11
chemicals,andnutrientsintogroundwater.Tracersareinjectedintogroundwaterto1characterizeflowconditionswithinthetreatmentareas.Tracersmayincludebromide,2fluorescein,eosine,andadditionalfluorescenttracers.Wellrehabilitationcompoundsareused3toremovemicrobialorgeochemicalfoulingthatmayhavedevelopedinthewell.Well4rehabilitationcompoundsauthorizedforuseareaceticacid,citricacid,hydrochloricacid,5hydrogenperoxide,andsodiumhydroxide.Additionally,theWaterBoardhasapprovedtheuse6ofseveralcommercialwellrehabilitationcompoundsthatarecertifiedundertheCalifornia7WaterworksStandardsforcommonlyusedrehabilitationofdrinkingwaterwells(LiquidAcid8Descaler,Aqua‐ClearAE,Aqua‐ClearMGA,BETZMPH500,NuWell120LiquidAcid,NuWell3109BioacidDispersant,andNuWell400Non‐IonicSurfactant).Processchemicalsauthorizedfor10remediationactivitiesincludealuminumsulfate,anti‐sealants,calciumhydroxide,calciumoxide,11hydrochloricacid,phosphoricacid,polymericflocculants,sodiumhydroxide,andsulfuricacid.12Potentialdischargesofnutrientsduringoperationincludeammonium,nitrate,phosphate,13vitamins,andyeastextract.14
MonitoringActivities.Monitoringwellsandsamplingofchromiumandby‐product15concentrationswouldcontinuetooccurasunderexistingconditions;theseactivitieswouldnot16belimitedtoaspecificOUareaandcouldbeimplementedthroughouttheprojectarea.17
ThephasedimplementationoftheremedialactionsundertheNoProjectAlternativewouldoccuras18follows:19
InitialBuildout:InstallnewextractionwellsintheOU1IRZareasandadjacenttotheCottrell20pivot9andtheDesertViewDairylandtreatmentunitinOU2.Installnewinjectionwellsinthe21OU1IRZareas.Constructassociatedadditionalpipelineconnections.Additionalmonitoring22wellswouldbeinstalledthroughouttheprojectarea.ContinuelandtreatmentandIRZ23treatment,includingIRZby‐productmanagement.24
Year5to10:Constructanadditional600linearfeet(lf)oftrenchingforpipelinesto25accommodateagriculturalunitwelloperations.Allotheroperationswouldcontinueasinthe26previousphase.27
Year10to20:Installthreenewextractionwells(inOU2forpumpingtoIRZarea)andthree28newinjectionwells(inSourceAreaIRZandSouthCentralAreaIRZ)forIRZtreatmentofhighest29remainingCr[VI].Allotheroperationswouldcontinueasinthepreviousphases.30
Allextractionandinjectionflowrateswouldbemaintainedthroughouteachphaseascurrently31beingoperatedunderexistingconditions.32
AsnotedinTable2‐2,theestimatedtimeperiodsforcleanupforthisalternativeareexpectedtobe33asfollows:34
Estimatedtimeto50ppb:6years35
Estimatedtimetoachieveconversionof80%ofCr[VI]masstoCr[III]inhighconcentrationarea:3613years37
9Center“pivot”irrigationisaformofirrigationconsistingofseveralsegmentsofpipe(usuallygalvanizedsteeloraluminum)joinedtogetherandsupportedbytrusses,mountedonwheeledtowerswithsprinklersordriplinespositionedalongitslength.Thesystemmovesinacircularpatternandisfedwithwaterfromthepivotpointatthecenterofthearc.DriplineswouldbeusedtoeliminatethepotentialforairbornemistscontainingCr[VI].
Table 2‐3. Summary of Components under No Project Alternativea 1
OptimizationPeriodInitialBuildout(0–5years)
Year5(5–10years)
Year10(10–20years)
Year20(20+years)
AgriculturalLandApplicationAgriculturalUnits(AUs) 182acresbAUExtractionWells 29Pipelines 24,499lfAUExtractionFlowc 1,100gpmIn‐SituRemediationZone(IRZ)ExtractionWells 17 17 20 20InjectionWells 86 86 89 89Pipelines 31,392lf 31,992lf 33,892lf 33,892lfCarbonamendedIRZflow(SCRIA,SAIRZ)c,d 190gpm(110gpm–SCRIA;80gpm–SAIRZ)IRZRecirculationflow(CAIRZ)c,d 83gpmNorthwestAreaFreshwaterInjectionExtractionWells 5InjectionWells 3Pipelines 31,886lfNorthwestFreshwaterReinjectionFlowc 80gpmMonitoringWellsMonitoringWells 446WellsandSupportinginfrastructureacreagee 39 39 39 39Accessroads 1 1 1 1Notes:a Alltotalsincludeexistinginfrastructure(seeTable2‐1)b AgriculturalUnits=DVD,Gorman,Cottrell,andRanch(allexisting).c Allflowsarebasedonaverageannualrates.d SCRIAreferstotheSouthCentralReinjectionArea.SAIRZreferstotheSourceAreaIn‐SituRemediationZone.CAIRZreferstotheCentralAreaIn‐SituRemediationZone.
e Includesacreageforallwells,includingAgriculturalUnits,In‐SituRemediation,NorthwestFreshwaterReinjection,andmonitoringwells.lf=linearfeetgpm=gallonsperminute
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐17 August 2012
ICF 00122.11
Estimatedtimetointerimmaximumcleanuplevelof3.1ppbCr[VI]/3.2ppbCr[T]:150years1(butonlyfortheQ12010plume)2
Estimatedtimetointerimaveragecleanuplevelsof1.2ppbCr[VI]/1.5ppbCr[T]:220years3(butonlyfortheQ12010plume)4
Asdescribedabove,theNoProjectAlternativedoesnotincluderemedialactionstoaddressthe5expandedplumeandthuswouldnotactivelyremediatealloftheexisting(orpotentialfuture6expanded)plume.Asaresult,thetimetoremediatechromiumcontaminationwithintheentireplume7wouldbecloserto1,000yearsforareasoutsidetheQ12010plume(similartofeasibilitystudy8Alternative1).TheNoProjectAlternativealsodoesnotincludeacontingencyplanintheeventthat9agriculturalunitscannotbeoperatedduetocropdisease,extendedstorms,orotherevents.10
2.9.2 Alternative 4B 11
2.9.2.1 Overview 12
Alternative4Bexpandsthearea,intensity,anddurationofremediationactivitiesoverexisting13authorizedandoperatingactivitiesproposedundertheNoProjectAlternative.Theproposed14treatmentapproachunderthisalternativewouldbesimilartothegeneralapproachthatPG&Eis15currentlyoperatingintheprojectareabutonagreaterscale.16
Treatmentmethodsforthisalternativeincludein‐situtreatmentbyextraction,carbonamendment17ofgroundwaterandreinjectionintheIRZareasinOU1(asdescribedinthedescriptionoftheNo18ProjectAlternative),agriculturalapplicationwithinandadjacenttothenortherndiffuseportionof19theplumeinOU2,andfreshwaterinjectioninthenorthwestareaoftheplumeadjacenttothe20westernboundariesofOU1andOU2.Therewouldbemorein‐situcarboninjection/extractionwells21andthusmoreabove‐groundIRZwellcompounds(approximately20by20feetfootprint)22comparedtotheNoProjectAlternative.Thisalternativealsoincludesexpansionofagriculturalland23treatmentandgroundwaterpumpingasnecessarytoaddresstherevisedplumearea,includinginto24OU3.Forexample,thisalternativecouldincludeupto446acresofagriculturalunitsandupto2,39525gpmofextractionforlandtreatment(comparedto182acresofagriculturalunitsand1,100gpmof26extractionpumpingforlandtreatmentwiththeNoProjectAlternative).27
Implementationofthisalternativeislikelytorequiretheacquisitionofpropertiesand/or28easementswithintheprojectareaforinstallationandmaintenanceofsupportinginfrastructurefor29implementingremediationactivities.Thisalternativealsowouldrequireacquisitionofwaterrights30becauseitincludesagriculturalwaterusethatwouldexceedPG&E’scurrentwaterallocation.31
Table2‐4summarizesthemaincomponentsofAlternative4B,andFigure2‐4showstheproposed32remediationactivitiesthatwouldbeimplemented.Thephasedimplementationoftheremedial33actionsunderAlternative4Bwouldoccurasfollows:34
InitialBuildout:AgriculturalunitsandassociatedwellsandpipelineswouldbeinstalledinOU235forexpandedlandtreatment(andinOU3asnecessary);flowrateswouldbeincreasedover36existingconditionsforplumecontainment,landapplication,andIRZtreatment.IRZtreatment37wouldbecontinuouslyoperated.Additionalmonitoringwellsalsowouldbeinstalledwithinthe38projectarea.39
Year5:SeveralSouthCentralAreainjectionwellsintheIRZareaswouldbeturnedoffand40northernareaextractionflowswouldberedirectedtotheremainingSouthCentralAreaand41
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐18 August 2012
ICF 00122.11
SourceAreainjectionwellsforshareddosedinjection;therewouldbeareductionintheSouth1CentralArea/SourceAreaflowrate.SouthernSourceAreaextractionwellswouldbeturnedoff2andconvertedtoinjectionwells;allotheroperationswouldcontinueasinthepreviousphases.3
Year10:Newextractionwellsandpipelinesforagriculturalunittreatmentwouldbeinstalled4inthenorthwestandnorthernareasinOU2(andinotherareasasnecessary);IRZflowratesin5theSourceAreaandSouthCentralAreawouldbeincreased.Allotheroperationswould6continueasinpreviousphases.7
Year20:IRZflowratesintheSourceArea/SouthCentralAreawouldbereducedandeastern8SouthCentralAreawellswouldbeturnedoff.TheCentralAreaflowswouldbeshutdown.IRZ9treatmentinSouthCentralAreawouldbemodifiedfromcontinuousoperationtolong‐term10intermittentcarbonamendedtreatmentoflowconcentrationareasinselectSouthCentral11Area/SourceAreainjectionwellsthatmayneedtooperatebeyond20years.Carbondosagein12theSourceAreawouldbereduced.Allotheroperationswouldcontinueasinpreviousphases.13
AsnotedinTable2‐2,theestimatedtimeperiodsforcleanupforthisalternativeareexpectedtobe14asfollows:15
Estimatedtimeto50ppb:6years16
Estimatedtimetoachieveconversionof80%ofCr[VI]masstoCr[III]inhighconcentrationarea:1710years18
Estimatedtimetointerimmaximumcleanuplevelof3.1ppbCr[VI]/3.2ppbCr[T]:40years19
Estimatedtimetointerimaveragecleanuplevelsof1.2ppbCr[VI]/1.5ppbCr[T]:95years20
Overall,incomparisontotheotherprojectalternatives,Alternative4Bwould:21
HaveasmallerlandtreatmentoperationthanAlternatives4C‐2,4C‐3,4C‐4,and4C‐5;22
Havenowinteragriculturaloperations/extraction;23
Havesimilarcleanuptimeframesasotherprojectalternatives;24
Havethesamefreshwaterinjectionoperationstomaintainhydrauliccontroloftheplumeasall25projectalternatives;and26
Costlessthanallotherprojectalternatives.27
2.9.2.2 Implementation Details 28
Plume Containment and Land Treatment 29
UnderAlternative4B,anewagriculturalunitwouldbeinstalledintheOU2areareferredtoasthe30Yangpivotandadditionalagriculturalunitswouldbeinstalledasnecessarytoaddresstheexpanded31plume.TheYangpivotislocatedadjacenttotheeasternareaoftheDesertViewDairyland32treatmentunit.Thespecificlocationofadditionalagriculturalunitshavenotyetbeenidentifiedbut33arelikelytobeinthenorthernoreasternportionsofOU2orinOU3basedonthecurrent34configurationofthechromiumplume.Agriculturalapplicationwouldinvolveextractionofwater35fromextractionwellsconstructedtosupportlandtreatment.Thewaterwouldbepipedtoexisting36ornewagriculturalunitsforapplicationbyfloodordripirrigation(drag‐driporsubsurface).37OperationoftheDesertViewDairylandtreatmentunitwouldcontinueasitdoesunderexisting38conditions.Landtreatmentwouldbeseasonalandwouldnotoccurduringwintermonths.39
Table 2‐4. Summary of Components under Alternative 4Ba 1
OptimizationPeriodInitialBuildout(0–5years)
Year5(5–10years)
Year10(10–20years)
Year20(20+years)
AgriculturalLandApplicationAgriculturalUnits(AUs)b 446 acresAUExtractionWells 65 65 90 90AUPipeline 59,049 lf 59,049 lf 78,419 lf 78,419 lfAUExtractionFlowc 2,395 gpmIn‐SituRemediationZone(IRZ)ExtractionWells 21 21 21 25InjectionWells 108 108 111 111Pipelines 39,240 lf 39,990 lf 42,365 lf 42,365 lfCarbon‐amendedIRZflow(SCRIA/SAIRZ)c,d 431 gpm 244 gpm 319 gpm 213 gpmIRZRecirculationflow(CAIRZ)c,d 279 gpmNorthwestAreaFreshwaterInjectionExtractionWells 5InjectionWells 4Pipelines 36,669lfNorthwestFreshwaterReinjectionFlowc 92 gpmMonitoringWells/SupportingInfrastructureMonitoringWells 558WellsandSupportingInfrastructure(acres)e 51 51 53 53Accessroads(acres) 3 3 5 5Notes:a Alltotalsincludeexistinginfrastructure.AllestimateshavebeenscaledupfromthedatafromtheFeasibilityStudyandAddendatoaccountforalargerplumethanusedinthefeasibilitystudy.Seediscussionintext.
b DesertViewDairy,Gorman,Cottrell,Ranch,plusadditionalAgriculturalUnits.c Allflowsarebasedonaverageannualrates.d SCRIAreferstotheSouthCentralReinjectionArea;SAIRZreferstotheSourceAreaIn‐SituRemediationZone;CAIRZreferstotheCentralAreaIn‐SituRemediationZone.
e Includesacreageforallwells,includingAgriculturalUnits,In‐SituRemediation,NorthwestFreshwaterReinjection,andmonitoringwells.lf=linearfeetgpm=gallonsperminute
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐19 August 2012
ICF 00122.11
Containmentofthechromiumplumewouldalsobeachievedascurrentlyoperatedthrough1freshwaterextractionfromfreshwaterwellsinthesouthernIRZareaandinjectiontowellslocated2atthenorthwesternboundaryoftheplumeadjacenttoOU1andOU2.Freshwaterextractionand3injectionisestimatedtobeuptoapproximately92gpm(including15%contingencyovercurrent4levels).5
In‐Situ Treatment 6
IRZtreatmentwouldoccurthroughoutOU1.TheinjectionswithinOU1wouldtargetthehighest7Cr[VI]concentrationswithintheplume.GroundwaterrecirculationintheareaoftheCentralArea8IRZandSourceAreaIRZandinjectionintheSouthCentralAreaIRZwouldprovideadditional9treatmenttotheSourceAreainOU1.10
In‐situtreatmentwouldinclude:11
ContinuousSouthCentralAreaIRZ/SourceAreaIRZoperationsupto431gpmduringinitial12buildout.13
ContinuousSourceAreaIRZoperationsupto188gpmduringinitialbuildout.14
ContinuousCentralAreaIRZrecirculationoperationfor20yearsatupto279gpm.15
Duringthesecondphase(5–10years),selectSouthCentralAreawellswouldbeturnedoffwith16flowsredistributedtobothSouthCentralAreaandSourceAreainjectionwellsforsharedflow17fordosed‐injection(operatedatupto244gpmbetweenyear5and10andthenupto319gpm18foryears10through20).19
After20years,easternSouthCentralAreawellswouldbeturnedoffandcontinuous,20intermittentlow‐dosagecarbonamendmentwouldbeappliedtoselectSouthCentral21Area/SourceAreainjectionwellsafter20years(upto213gpm)withreductionindosagefrom22125mg/Lto25mg/L.CentralAreaIRZflowswouldbeturnedoff.23
Monitoring Activities 24
Monitoringactivitieswouldbethesameasthosebeingimplementedforexistingoperations25throughouttheprojectarea(describedunderSection2.4above).26
Contingency Plan for Agricultural Unit Operations 27
Alternative4Bincludesacontingencyplanintheeventthatagricultural/landtreatmentcannotbe28implementedduetosevereandextendedstormactivitythatwouldprecludeinfiltration,crop29disease,orotherunforeseeneventsthatwouldprecludeagriculturalunitoperationsforany30substantialdurationoftime.10Basedonareviewofstormrecordsandincludinga200percent31contingency,thepotentialdurationofasignificantstormeventwouldbe18days.Thisgapin32agriculturalunitextractionpumpingisnotexpectedtoresultinanymeaningfulplumemovementor33lossofcaptureandevena90‐daygapisnotexpectedtoresultinfullreversalofhydraulicgradients34(PacificGasandElectric2011c).Thus,thelikelihoodofhavingtoimplementthecontingencyplan35duetoinclementweatherislow.However,theremaybeotherunforeseeneventsthatcouldresultin36aprolongedimpairmentofagriculturalunitoperationsthatimpairsplumecontrolandtreatment;in37suchacasethecontingencyplanwouldbeputintoeffect.38
10Alternatives4C‐2,4C‐3,and4C‐4alsoincludecontingencymeasuresasdescribedbelow.
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐20 August 2012
ICF 00122.11
ThecontingencyplanisdescribedintheSeptember2011FeasibilityStudyAddendum3and1includesthefollowingphases:2
RoutineAgriculturalUnitOperations–Flowratesincludedinthisalternativewouldbe3maintainedbyadjustingthenumberofagriculturalunitsbeingoperated.4
TierIContingencyAgriculturalUnitOperation–Intheeventofsevereweatherorother5impedimentstotemporaryagriculturalunitoperations,agriculturalunitflowratescanbe6temporarilyreducedforaperiodoftimewithouthamperingplumehydrauliccontrol.However,7iftheimpairmentislengthier,thenPG&Ewouldbringadditionalagriculturalunitsonlineby8constructingadditionalagriculturalunitsorrestartingidleagriculturalunits.Flowrateswould9bereducedtoupto90days(asnecessary)whileadditionalagriculturalunitswerebroughton10line.11
TierIIContingencyAlternativeOperations–Ifadditionalagriculturalunitsarenotfeasible,then12alternativecontrolandtreatmentmethodswillneedtobeemployed.Thecontingencyplan13identifiespotentialuseofinfiltrationgalleriesand/orex‐situtreatment11.Giventhattheamount14oflandrequired(200acrestomaintainflowratesof1,200gpm)forinfiltrationgalleriesismuch15smallerthantheamountoflandrequiredforagriculturalunitsforagivenflowandthatthe16natureofimpacts(suchasgrounddisturbance)areverysimilartoagriculturalunits,infiltration17galleriesarenotseparatelyanalyzedinthisEIR.Theimpactsofex‐situtreatmentareas18describedbelowfortheex‐situelementsincludedinAlternatives4C‐3and4C‐5.19
2.9.3 Alternative 4C‐2 20
2.9.3.1 Overview 21
Alternative4C‐2usesmuchofthesamegeneralinfrastructureandoptimizationasthatproposed22underAlternative4BinrelationtoplumecontainmentandIRZtreatment.Alternative4C‐2differs23fromAlternative4Bbyincludingmoreintensivegroundwaterextractionforlandtreatmentwiththe24additionofwintercrops(winterryeorasimilarcrop)atselectagriculturalunits.Thisexpansionis25proposedtoachieveandmaintainyear‐roundextraction/hydrauliccontroloftheplumemovement26tofosterfastercleanupperiodscomparedtoAlternative4B.27
Thisalternativealsoincludesexpansionofagriculturallandtreatmentandgroundwaterpumpingas28necessarytoaddresstherevisedplumearea,includingintoOU3;forexamplethisalternativecould29includeupto575acresofagriculturalunitsandupto3,167gpmofextractionforlandtreatment30(comparedto182acresofagriculturalunitsand1,100gpmofextractionpumpingforland31treatmentwiththeNoProjectAlternative).32
Implementationofthisalternativeislikelytorequiretheacquisitionofpropertiesand/or33easementswithintheprojectareaforinstallationandmaintenanceofsupportinginfrastructureto34implementremediationactivities.Thisalternativealsowouldrequireacquisitionofwaterrights35becauseitincludesagriculturalwaterusethatwouldexceedPG&E’scurrentwaterallocation.36
11Aninfiltrationgalleryisanundergroundstructurewithperforatedpipeswhereextractedgroundwateristreatedandrechargedtothevadosezoneandwatertable.WatertreatmentisaccomplishedthroughtheadditionofamendmentstoreduceCr[VI]toCr[III]similartotheIRZprocess.
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐21 August 2012
ICF 00122.11
Table2‐5summarizesthemaincomponentsofAlternative4C‐2,andFigure2‐5showstheproposed1remediationactivitiesthatwouldbeimplemented.Thephasedimplementationoftheremedial2actionsunderAlternative4C‐2wouldoccurasfollows:3
InitialBuildout:Agriculturalunitpivotsandassociatedextractionwellsandpipelineswouldbe4constructedinOU1andOU2areas;allflowratesforcontainment,landapplication,andIRZ5treatmentwouldincreasefromexistingconditions.Additionalpivotsnecessarytoaddress6plumeexpansionwouldbelocatedinOU2andOU3.IRZtreatmentwouldbecontinuous.7Additionalmonitoringwellsalsowouldbeinstalledwithintheprojectarea.8
Year5:SeveralSouthCentralAreainjectionwellsintheIRZareaswouldbeturnedoffand9northernareaextractionflowswouldberedirectedtoremainingSouthCentralAreaandSource10Areainjectionwellsforshareddosedinjection;therewouldbeareductionintheSouthCentral11Area/SourceAreaflowrate.SouthernSourceAreaextractionwellswouldbeturnedoffand12convertedtoinjectionwells;allotheroperationswouldcontinueasinthepreviousphases.13
Year10:Additionalextractionwellsandpipelineswouldbeconstructedinthenorthwestand14northernareasinOU2toexpandagriculturalunittreatment;IRZflowratesintheSourceArea15andSouthCentralAreawouldbeincreased.Allotheroperationswouldcontinueasinprevious16phases.17
Year20:Severalagriculturalpivotsmaybeturnedoff(dependingonremedialprogressatthe18time)andflowsfromnorthernagriculturalunitextractionwellsinstalledinYear10couldbe19shiftedtoIRZtreatment;CentralAreaIRZrecirculationflowswouldbeturnedoff.EasternSouth20CentralAreawellswouldbeturnedoff;IRZtreatmentinSouthCentralAreawouldbemodified21fromcontinuousoperationtolong‐termintermittentcarbonamendedtreatmentoflow22concentrationareasinselectSouthCentralArea/SourceAreainjectionwellsbeyond20years.23CarbondosageintheSourceAreawouldbereduced.24
AsnotedinTable2‐2,theestimatedtimeperiodsforcleanupforthisalternativeareexpectedtobe25asfollows:26
Estimatedtimeto50ppb:6years27
Estimatedtimetoachieveconversionof80%ofCr[VI]masstoCr[III]inhighconcentrationarea:287years29
Estimatedtimetointerimmaximumcleanuplevelof3.1ppbCr[VI]/3.2ppbCr[T]:39years30
Estimatedtimetointerimaveragecleanuplevelsof1.2ppbCr[VI]/1.5ppbCr[T]:90years31
Overall,incomparisontotheotherprojectalternatives,Alternative4C‐2would:32
Haveamoreextensivelandtreatmentapproach(includingwinteroperations)thantheNo33ProjectAlternativeandAlternative4B;34
Havethesamefreshwaterinjectionoperationstomaintainhydrauliccontrolasallproject35alternatives;and36
HaveashorterperiodforachievingcleanuptoaverageandmaximumCr[T]andCr[VI]interim37cleanuplevelsovertheNoProjectAlternativeandAlternative4Bonly.38
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐22 August 2012
ICF 00122.11
2.9.3.2 Implementation Details 1
Plume Containment and Land Treatment 2
ThisalternativesupportsmoreagriculturaltreatmentthanAlternative4Btoaccommodate3additionalagriculturalextraction.Theadditionalagriculturalunitswouldinclude:4
OnepivotlocatedjustsouthoftheDesertViewDairylandtreatmentunit;5
OnepivotlocatedeastoftheDesertViewDairy;6
TwopivotslocatedinthecentralareaoftheplumeonorneartheformerBellproperty;7
OnepivotlocatedinthesouthernportionoftheSouthCentralArea,southeastoftheBellpivots8andnorthofthesourceareawithinOU1;and9
Additionalpivotsnecessarytoaddresstheexpandedplumeareatotheeastandthenorth10(infuturelocationsasyetundetermined).11
UnderAlternative4C‐2themaximumflowratesforextractionofgroundwaterfromnorthernlow‐12concentrationareaswouldbeincreasedandusedforyear‐roundcontinuousoperationof13agriculturaltreatmentonselectagriculturalunitstosupportwintercrops.Agriculturalunitflows14maybedecreasedatYear20dependingonthetreatmentachievementsatthattime.Freshwater15injectionwouldremainthesame,withestimatedflowsofupto92gpm(15%contingencyover16existinglevels)forthedurationoftreatment.Otherthanthesechanges,allotheractivitieswouldbe17similartoAlternative4B.18
In‐Situ Treatment 19
In‐situtreatmentunderAlternative4C‐2wouldbethesameasin‐situtreatmentdescribedunder20Alternative4B.21
Monitoring Activities 22
Monitoringactivitieswouldbethesameasthosebeingimplementedforexistingoperations23throughouttheprojectarea(asdescribedunderSection2.4above).24
Contingency Plan for Agricultural Unit Operations 25
Alternative4C‐2wouldincludeacontingencyplanasdescribedforAlternative4Babove.26
2.9.4 Alternative 4C‐3 27
2.9.4.1 Overview 28
Alternative4C‐3usesmuchofthesamegeneralinfrastructureandoptimizationasthatproposed29underAlternatives4Band4C‐2inrelationtoplumecontainment,landtreatmentviaagricultural30treatment,andIRZtreatment.Alternative4C‐3addsex‐situtreatmentplantstoprovideyear‐round31continuouspumpingtotreatexcesswinterwaterthatcannotbetreatedbyproposedagricultural32unitsinwinter.Theproposedex‐situtechnologyisextraction,treatmentthroughchemical33reduction/precipitation,andreinjectionoftreatedwaterintothegroundwater.Thistechnologywas34selectedbasedonsimilaroperationsthathavebeenimplementedbyPG&EatitsTopocksitewhere35
Table 2‐5. Summary of Components under Alternative 4C‐2a 1
OptimizationPeriodInitialBuildout(0–5years)
Year5(5–10years)
Year10(10–20years)
Year20(20+years)
AgriculturalLandApplicationAgriculturalUnits(AUs)b 575 acresAUExtractionWells 80 80 102 102AUPipeline 68,489 lf 68,489 lf 83,374 lf 83,374 lfAUExtractionFlowc 3,167 gpmIn‐SituRemediationZone(IRZ)ExtractionWells 21 21 25 25InjectionWells 108 108 111 111Pipelines 39,240 lf 39,990 lf 42,365 lf 42,365 lfCarbon‐amendedIRZflow(SCRIA/SAIRZ)c,d 431 gpm 244 gpm 319 gpm 213 gpmIRZRecirculationflow(CAIRZ)c,d 279 gpmNorthwestAreaFreshwaterInjectionExtractionWells 5InjectionWells 4Pipelines 36,669 lfNorthwestFreshwaterReinjectionFlowc 92 gpmMonitoringWells/SupportingInfrastructureMonitoringWells 558WellsandSupportingInfrastructureAcreagee 52 52 54 54Accessroads(acres) 4 4 5 5Notes:a Alltotalsincludeexistinginfrastructure.AllestimateshavebeenscaledupfromthedatafromtheFeasibilityStudyandAddendatoaccountforalargerplumethanusedinthefeasibilitystudy.Seediscussionintext.
b DesertViewDairy,Gorman,Cottrell,Ranch,plusadditionalAgriculturalUnits.c Allflowsarebasedonaverageannualrates.d SCRIAreferstotheSouthCentralReinjectionArea.SAIRZreferstotheSourceAreaIn‐SituRemediationZone.CAIRZreferstotheCentralAreaIn‐SituRemediationZone.
e Includesacreageforallwells,includingAgriculturalUnits,In‐SituRemediation,NorthwestFreshwaterReinjection,andmonitoringwells.lf=linearfeetgpm=gallonsperminute
California Regional Water Quality Control Board, Lahontan Region Project Description
Comprehensive Groundwater Cleanup Strategy for Historical Chromium Discharges from PG&E’s Hinkley Compressor Station Draft Environmental Impact Report
2‐23 August 2012
ICF 00122.11
thetechnologyhasbeeneffectiveinthecleanupofwatercontaminatedbyCr[VI].Therewouldbeup1toatotaloftwoabove‐groundtreatmentfacilities.Onetreatmentfacilitywouldbelocatedgenerally2neartheCompressorStationadjacenttothesouthernboundaryoftheSourceAreaIRZinOU1,and3onetreatmentfacilitywouldbelocatedgenerallyneartheDesertViewDairyadjacenttothe4northwesternboundaryofOU2.5
Thisalternativealsoincludesadditionalagriculturallandtreatmentandgroundwaterpumpingas6necessarytoaddresstherevisedplumeareaincludingintoOU3;forexamplethisalternativecould7includeupto575acresofagriculturalunitsandupto4,388gpmofextraction(annualaverage)for8landtreatment(comparedto182acresofagriculturalunitsand1,100gpmofextractionpumping9forlandtreatmentwiththeNoProjectAlternative).10
Implementationofthisalternativeislikelytorequiretheacquisitionofpropertiesand/or11easementswithintheprojectareafortheinstallationandmaintenanceofinfrastructurethat12supportstheimplementationofremediationactivities.Thisalternativealsowouldrequire13acquisitionofwaterrightsbecauseitincludesagriculturalwaterusethatwouldexceedPG&E’s14currentwaterallocation.15
Table2‐6summarizesthemaincomponentsofAlternative4C‐3,andFigure2‐6showstheproposed16remediationactivitiesthatwouldbeimplemented.Thephasedimplementationoftheremedial17actionsunderAlternative4C‐3wouldoccurasfollows:18
InitialBuildout:Newagriculturalunitpivotsandassociatedextractionwellsandpipelines19wouldbeconstructedinOU1andOU2areas;allflowratesforcontainment,landapplicationand20IRZtreatmentwouldincrease.Additionalpivotsnecessarytoaddressplumeexpansionwould21belocatedinOU2andOU3.Northandsouthex‐situtreatmentplants,includingsupporting22facilities,wouldbeconstructed;newex‐situinjectionwellsassociatedwitheachtreatmentplant23wouldbeinstalled,withadditionalconveyancepipingandsupportinginfrastructure;operation24ofex‐situtreatmentwouldbeinitiated.Additionalmonitoringwellswouldalsobeinstalled25withintheprojectarea.26
Year5:SeveralSouthCentralAreainjectionwellsintheIRZareaswouldbeturnedoffand27northernareaextractionflowswouldberedirectedtoremainingSouthCentralAreaandSource28Areainjectionwellsforshareddosedinjection;therewouldbeareductionintheSouthCentral29Area/SourceAreaflowrate.SouthernSourceAreaextractionwellswouldbeturnedoffand30convertedtoinjectionwells.31
Year10:Additionalextractionwellsandpipelineswouldbeconstructedinthenorthwestand32northernareasinOU2toexpandagriculturalunittreatment;IRZflowratesintheSourceArea33andSouthCentralAreawouldbeincreased.Allotheroperationswouldcontinueasinprevious34phases.35
Year20:Severalagriculturalunitpivotsmaybeturnedoff(dependingoncleanupachievements36byyear20)andflowsfromnorthernagriculturalunitextractionwellsinstalledinYear1037wouldbeshiftedtoIRZtreatment.CentralAreaIRZrecirculationflowswouldbeturnedoff.38EasternSouthCentralAreawellswouldbeturnedoff;IRZtreatmentinSouthCentralArea39wouldbemodifiedfromcontinuousoperationtolong‐termintermittentcarbonamended40treatmentoflowconcentrationareasinselectSouthCentralArea/SourceAreainjectionwells41beyond20years.CarbondosageintheSourceAreaIRZwouldbereduced.42
California Regional Water Quality Control Board, Lahontan Region Project Description
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2‐24 August 2012
ICF 00122.11
AsnotedinTable2‐2,theestimatedtimeperiodsforcleanupforthisalternativeareexpectedtobe1asfollows:2
Estimatedtimeto50ppb:4years3
Estimatedtimetoachieveconversionof80%ofCr[VI]masstoCr[III]inhighconcentrationarea:46years5
Estimatedtimetointerimmaximumcleanuplevelof3.1ppbCr[VI]/3.2ppbCr[T]:36years6
Estimatedtimetointerimaveragecleanuplevelsof1.2ppbCr[VI]/1.5ppbCr[T]:85years7
Overall,incomparisontotheotherprojectalternatives,Alternative4C‐3would:8
HaveashortertimeperiodtoachievecleanuptoaverageandmaximumCr[T]andCr[VI]interim9cleanuplevelsthanallotheralternativesexceptAlternative4C‐4;10
Removechromiummassfromtheaquiferduetotheuseofwinterex‐situtreatment12;11
Requiremoreexpansiveconstructionassociatedwiththeex‐situtreatmentplantsand12supportinginfrastructure;13
Haveagreateramountoftrucktrafficasrequiredbytheoperationoftheex‐situtreatment14plants;15
Havethesamefreshwaterinjectionoperationstomaintainhydrauliccontrolasallproject16alternatives;and17
Havethehighestcostforimplementationofallalternatives.18
2.9.4.2 Implementation Details 19
Plume Containment and Land Treatment 20
ThisalternativewouldsupportasimilarlevelofagriculturallandtreatmentandunitsasAlternative214C‐2.UnderAlternative4C‐3,themaximumflowratesforextractionofgroundwaterfromnorthern22low‐concentrationareasforagriculturallandtreatmentwouldbethehighestofallproject23alternatives,exceptforAlternative4C‐4,whichwouldhavethesameflowrate.Agriculturalunit24flowswouldbedecreasedatYear20,dependingontheeffectivenessofremediationinreducing25contaminationlevelsbythattime.Freshwaterinjectionwouldremainthesamewithestimated26flowsofupto92gpm(15%morethanexisting)forthedurationoftreatment.Otherthanthese27changes,allotheractivitieswouldbethesameasthosedescribedforAlternative4C‐2.28
In‐Situ Treatment 29
In‐situtreatmentunderAlternative4C‐3wouldbethesameastreatmentdescribedunder30Alternatives4Band4C‐2.31
12Alternatives4B,4C‐2,and4C‐4wouldnotremovechromiumfromtheaquiferbutinsteadconvertthehighlytoxicCr[VI]ingroundwatertolowtoxicitysolidCr[III].Alternative4C‐5wouldremovechromiuminthesourceareausingex‐situabove‐groundtreatment.
Table 2‐6. Summary of Components under Alternative 4C‐3 1
OptimizationPeriodInitialBuildout(0–5years)
Year5(5–10years)
Year10(10–20years)
Year20(20+years)
AgriculturalLandApplicationAgriculturalUnits(AUs)a 575acresAUExtractionWells 80 80 102 103AUPipeline 72,751lf 72,751lf 83,374lf 83,374lfAUExtractionFlow 4,388gpm 4,388gpm 4,388gpm 3,606gpmIn‐SituRemediationZone(IRZ)ExtractionWells 22 22 25 25InjectionWells 108 108 111 111Pipelines 39,240lf 39,990lf 42,365lf 42,365lfCarbon‐amendedIRZflow(SCRIA/SAIRZ)b,c 431gpm 244gpm 319gpm 213gpmIRZRecirculationflow(CAIRZ)b,c 279gpmEx‐SituTreatmentExtractionWells 31Pipelines 41,816 lfExtractionFlow(annual) 1,222 gpmNorthwestAreaFreshwaterInjectionExtraction/InjectionWells 5/4Pipelines 36,669lfNorthwestFreshwaterReinjectionFlowb 92 gpmMonitoringWells/SupportingInfrastructureMonitoringWells 558WellsandSupportingInfrastructureacreaged 54 54 56 56Accessroads(acres) 7 9 12 15Notes:a DesertViewDairy,Gorman,Cottrell,Ranch,plusadditionalAgriculturalUnits.b Allflowsarebasedonaverageannualrates.c SCRIAreferstotheSouthCentralReinjectionArea.SAIRZreferstotheSourceAreaIn‐SituRemediationZone.CAIRZreferstotheCentralAreaIn‐SituRemediationZone.
d Includesacreageforallwells,includingAgriculturalUnits,In‐SituRemediation,NorthwestFreshwaterReinjection,andmonitoringwells.lf=linearfeetgpm=gallonsperminute
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2‐25 August 2012
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Ex‐Situ Treatment 1
Asdescribedabove,underAlternative4C‐3,uptoatotaloftwoex‐situtreatmentplantswouldbe2constructedtotreatexcesswinterflowsthatwouldnotbesupportedbytheagriculturalunit3operations.Asshownintheconceptuallayout(Figures2‐6),asouthplantandassociatedinjection4wellswouldbelocatednearthesourceareaattheCompressorStationinOU1andanorthplant5wouldbelocatedadjacenttotheDesertViewDairyinOU2.Twotreatmentplantsareassumed6underthisalternative,onewithatreatmentcapacityofapproximately1,200gpmfromflowsnorth7ofSR58,whichwouldgenerallytreatcontaminationinOU2,andasecondplantwithatreatment8capacityofapproximately450gpmsouthofSR58,whichwouldgenerallytreatcontaminationin9OU1.Ex‐situtreatmentaverageannualflowswouldbe1,222gpm.Ex‐situtreatmentincludes10extractionofchromiumcontaminatedgroundwaterfromthehighestconcentrationareasandlow‐11concentrationareas,treatingitatthenearbyabove‐groundfacilityusingchemicalprecipitationand12filtrationprocesses,andreinjectingthecleanwaterintoassociatedinjectionwells.Thesolidby‐13productresiduegeneratedduringtreatmentwouldbemanagedanddisposedofatClassIlandfill14disposalfacilities,suchastheWasteManagementKettlemanHillsFacility,thatarepermittedto15accepthazardouswastesasauthorizedunderTitle27oftheCaliforniaCodeofRegulations.16
Monitoring Activities 17
Monitoringactivitieswouldbethesameasthosebeingimplementedunderexistingoperations18throughouttheprojectarea(asdescribedunderSection2.4).19
Contingency Plan for Agricultural Unit Operations 20
Alternative4C‐3wouldincludeacontingencyplanasdescribedforAlternative4Babove,exceptthat21thetwoabove‐groundtreatmentplantsincludedinthisalternativealreadyprovidecontingency22optionsintheeventthatagriculturalunittreatmentisimpairedforashortperiodoftime.The23above‐groundtreatmentplantsarebeingdesignedwithmorecapacitythanneededforexpected24averageflows,whichcreatessomebuilt‐incontingency.Also,sinceAlternative4C‐3alreadyrelies25onabove‐groundtreatmentinwinter,ithasabuilt‐incontingencyintheeventofimpairmentof26agriculturalunitsduetowinterstorms.27
2.9.5 Alternative 4C‐4 28
2.9.5.1 Overview 29
Alternative4C‐4usesmuchofthesameinfrastructureandoptimizationasproposedunder30Alternatives4B,4C‐2,and4C‐3butsignificantlyexpandsthenumberofagriculturalunitsforland31treatmentviaoperationofwinteragriculturalunitpivotsusingcontinuouspumpinginlieuofanex‐32situtreatmentplantasproposedunderAlternative4C‐3.33
Thisalternativealsoexpandsagriculturallandtreatmentandgroundwaterpumpingasnecessaryto34addresstherevisedplumearea,includingintoOU3;forexamplethisalternativecouldincludeupto351,394acresofagriculturalunitsandanannualextractionrateofupto4,388gpmforlandtreatment36(comparedto182acresofagriculturalunitsand1,100gpmofextractionpumpingforland37treatmentwiththeNoProjectAlternative).38
Implementationofthisalternativeislikelytorequiretheacquisitionofpropertiesand/or39easementswithintheprojectareaforinstallationandmaintenanceofsupportinginfrastructurefor40
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2‐26 August 2012
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implementingremediationactivities.Thisalternativealsowouldrequireacquisitionofwaterrights1becauseitincludesagriculturalwaterusethatwouldexceedPG&E’scurrentwaterallocation.2
Table2‐7summarizesthemaincomponentsofAlternative4C‐4,andFigure2‐7showstheproposed3remediationtechnologiesthatwouldbeimplemented.Thephasedimplementationoftheremedial4actionsunderAlternative4C‐4wouldoccurasfollows:5
InitialBuildout:Atleastsixteennewagriculturalunitpivotsandassociatedextractionwells6andpipelineswouldbeconstructedinOU1andOU2areas;allflowratesforcontainment,land7application,andIRZtreatmentwouldincrease.Additionalagriculturalunitpivotswouldbe8necessarytoaddresstheexpandedplumeandwouldlikelybelocatedinOU2andOU3.9Additionalmonitoringwellsalsowouldbeinstalledwithintheprojectarea.10
Year5:SeveralSouthCentralAreainjectionwellsintheIRZareaswouldbeturnedoffand11northernareaextractionflowswouldberedirectedtoremainingSouthCentralAreaandSource12Areainjectionwellsforshareddosedinjection;therewouldbeareductionintheSouthCentral13Area/SourceAreaflowrate.SouthernSourceAreaextractionwellswouldbeturnedoffand14convertedtoinjectionwells.15
Year10:Additionalextractionwellsandpipelineswouldbeconstructedinthenorthwestand16northernareasinOU2toexpandagriculturalunittreatment;IRZflowratesintheSourceArea17andSouthCentralAreawouldbeincreased.Allotheroperationswouldcontinueasinprevious18phases.19
Year20:Severalagriculturalunitpivotsmaybeturnedoff(dependingoneffectivenessof20remediationbyYear20)andflowsfromnorthernagriculturalunitextractionwellsinstalledin21Year10wouldbeshiftedtoIRZtreatment;CentralAreaIRZrecirculationflowswouldbeturned22off;EasternSouthCentralAreawellswouldbeturnedoff;IRZtreatmentinSouthCentralArea23wouldbemodifiedfromcontinuousoperationtolong‐termintermittentcarbonamended24treatmentoflowconcentrationareasinselectSouthCentralArea/SourceAreainjectionwells25beyond20years.CarbondosageintheSourceAreawouldbereduced.Allotheroperations26wouldcontinueasinpreviousphases.27
AsnotedinTable2‐2,theestimatedtimeperiodsforcleanupforthisalternativeareexpectedtobe28asfollows:29
Estimatedtimeto50ppb:3years30
Estimatedtimetoachieveconversionof80%ofCr[VI]masstoCr[III]inhighconcentrationarea:316years32
Estimatedtimetointerimmaximumcleanuplevelof3.1ppbCr[VI]/3.2ppbCr[T]:29years33
Estimatedtimetointerimaveragecleanuplevelsof1.2ppbCr[VI]/1.5ppbCr[T]:75years34
Overall,incomparisontotheotherprojectalternatives,Alternative4C‐4would:35
HavethefastesttimeframestoachieveaverageandmaximumCr[T]andCr[VI]interimcleanup36levelsoverallprojectalternatives;37
Requireconstructionofthelargestareaofagriculturalunitsandassociatedpipelineconveyance38systemsofallprojectalternatives;andhavethesamefreshwaterinjectionoperationsto39maintainhydrauliccontrolasallalternatives;and40
Havethesecondhighestcostofallalternatives.41
Table 2‐7. Summary of Components under Alternative 4C‐4 1
OptimizationPeriodInitialBuildout(0–5years)
Year5(5–10years)
Year10(10–20years)
Year20(20+years)
AgriculturalLandApplicationAgriculturalUnits(AUs)a 1,394acresAUExtractionWells 149 149 190 190AUPipeline 132,875lf 132,875lf 147,374lf 147,374lfAUExtractionFlow 4,388gpmIn‐SituRemediationZone(IRZ)ExtractionWells 22 22 25 25InjectionWells 108 108 111 111Pipelines 39,240lf 39,990lf 42,365lf 42,365lfCarbon‐amendedIRZflow(SCRIA/SAIRZ)b,c 431gpm 244gpm 319gpm 213gpmIRZRecirculationflow(CAIRZ)b,c 279gpmNorthwestAreaFreshwaterInjectionExtractionWells 5InjectionWells 4Pipelines 36,669lfNorthwestFreshwaterReinjectionFlowb 92gpmMonitoringWells/SupportingInfrastructureMonitoringWells 558WellsandSupportingInfrastructureacreaged 56 56 59 59Accessroads(acres) 8 8 9 9Notes:a DesertViewDairy,Gorman,Cottrell,Ranch,plusadditionalAgriculturalUnits.b Allflowsarebasedaverageannualrates.c SCRIAreferstotheSouthCentralReinjectionArea.SAIRZreferstotheSourceAreaIn‐SituRemediationZone.CAIRZreferstotheCentralAreaIn‐SituRemediationZone.
d Includesacreageforallwells,includingAgriculturalUnits,In‐SituRemediation,NorthwestFreshwaterReinjection,andmonitoringwells.lf=linearfeetgpm=gallonsperminute
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2‐27 August 2012
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2.9.5.2 Implementation Details 1
Containment and Land Treatment 2
Thisalternativeincludesalargeincreaseinagriculturalpivotsovertheexistingcondition.3Theincreaseinagriculturalpivotsforthisalternativeisgreaterthanallotheralternatives,with4additionalagriculturalunitstobeaddedforwinter‐onlyoperations.UnderAlternative4C‐4,5themaximumflowratesforextractionofgroundwaterfromnorthernlow‐concentrationareasfor6agriculturallandtreatmentwouldbethehighestofallalternatives,exceptforAlternative4C‐3,7whichwouldhavethesameflowrates.AgriculturalunitflowsmaybedecreasedatYear208dependingoneffectivenessofremediationbythattime.Theoveralllandtreatmentflowratesare9higherthanAlternatives4Band4C‐2becausethetreatmentapproachismoreaggressive.10Freshwaterinjectionwouldremainthesamewithestimatedflowsofupto92gpm(existingflow11levelplus15%contingency)forthedurationoftreatment.12
In‐Situ Treatment 13
In‐situtreatmentunderAlternative4C‐4wouldbethesameasin‐situtreatmentproposedunderthe14otherdescribedalternatives.15
Monitoring Activities 16
Monitoringactivitieswouldbethesameasthoseproposedundertheotherdescribedalternatives.17
Contingency Plan for Agricultural Unit Operations 18
Alternative4C‐4wouldincludeacontingencyplanasdescribedforAlternative4Babove.19
2.9.6 Alternative 4C‐5 20
2.9.6.1 Overview 21
Alternative4C‐5isacombinationofthreeremedialstrategies:agriculturallandtreatment,in‐situ22remediation,andex‐situ(above‐ground)chemicaltreatment.Liketheotheractionalternatives,23implementationofthisalternativeislikelytorequiretheacquisitionofpropertiesand/or24easementswithintheprojectareaforinstallationandmaintenanceofsupportinginfrastructurefor25implementingremediationactivities.Thisalternativealsowouldrequireacquisitionofwaterrights26becauseitincludesagriculturalwaterusethatwouldexceedPG&E’scurrentwaterallocation.27
Table2‐8summarizesthemaincomponentsofAlternative4C‐5,andFigure2‐8showstheproposed28remediationactivitiesthatwouldbeimplemented.29
TheprimarydifferenceintheconfigurationsofAlternative4C‐5andAlternative4C‐2isthat30Alternative4C‐5focusesin‐situtreatmentintheSouthCentralAreaandCentralAreaandincludes31above‐groundtreatmentintheSourceAreainsteadofthein‐situtreatmentproposedfortheSource32AreaunderAlternative4C‐2.Therefore,comparedtotheNoProjectAlternativeandtheotheraction33alternatives,therewouldfewerin‐situcarboninjection/extractionwellsandthuslessabove‐ground34IRZwellcompounds(approximately20by20feetfootprint).Theprimarydifferencebetweenthe35configurationsofAlternative4C‐5andAlternative4C‐3isthatAlternative4C‐5usesonlyoneabove‐36groundtreatmentplantforyear‐roundex‐situtreatmentofthehighconcentrationplume,whereas37
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2‐28 August 2012
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Alternative4C‐3usestwoabove‐groundtreatmentplantsforwinterplumecontrolonly.Theabove‐1groundtreatmentplantwouldbelocatedgenerallyneartheCompressorStationadjacenttothe2southernboundaryoftheSourceAreaIRZinOU1.Thisalternativealsoexpandsagriculturalland3treatmentandgroundwaterpumpingasnecessarytoaddresstherevisedplumearea,includinginto4OU3;forexample,thisalternativecouldincludeupto575acresofagriculturalunitsandupto3,1675gpm(annualaverage)ofextractionforlandtreatment(comparedto182acresofagriculturalunits6and1,100gpmofextractionpumpingforlandtreatmentwiththeNoProjectAlternative).7
Implementationofthisalternativeislikelytorequiretheacquisitionofpropertiesand/or8easementswithintheprojectarea.Theseacquisitionswouldbeforinstallationandmaintenanceof9supportinginfrastructureforimplementingremediationactivities.10
ThephasedimplementationoftheremedialactionsunderAlternative4C‐5wouldoccurasfollows:11
InitialBuildout:Newagriculturalunitpivotsandassociatedextractionwellsandpipelines12wouldbeconstructedinOU1andOU2areas;allflowratesforcontainment,landapplicationand13IRZtreatmentwouldincrease.Theex‐situtreatmentplantandassociatedsupporting14infrastructurewouldbeconstructed.Newex‐situinjectionwellswouldbeinstalledinthe15SourceAreawithassociatedpipelines.16
Year5:SeveralSouthCentralAreainjectionwellsintheIRZareaswouldbeturnedoffand17northernareaextractionflowswouldberedirectedtoremainingSouthCentralArea;there18wouldbeareductionintheSouthCentralAreaflowrate.Allotheroperationswouldcontinueas19inpreviousphases.20
Year10:Additionalextractionwellsandpipelineswouldbeconstructedinthenorthwestand21northernareasinOU2toexpandagriculturalunittreatment;IRZflowratesintheSourceArea22andSouthCentralAreawouldbeincreased.Allotheroperationswouldcontinueasinprevious23phases.24
Year15:SourceAreaex‐situtreatedwaterinjectionwouldbeshiftednorth;additionalinjection25wellsinstalledandconveyancepipingandsupportinginfrastructurewouldbeconstructed;26severalextractionwellswouldbeturnedoff.27
Year20:Severalagriculturalunitpivotswouldbeturnedoff(dependingoneffectivenessof28remediationbythattime)andflowsfromnorthernagriculturalunitextractionwellsinstalledin29Year10wouldbeshiftedtoIRZtreatment;CentralAreaIRZrecirculationflowswouldbeturned30off;IRZtreatmentinSouthCentralAreawouldbemodifiedfromcontinuousoperationtolong‐31termintermittentcarbonamendedtreatmentoflowconcentrationareasinselectSouthCentral32Areainjectionwellsbeyond20years.CarbondosageintheSourceAreawouldbereduced.All33otheroperationswouldcontinueasinpreviousphases.34
Year32:SourceAreaextractionwellswouldbeconvertedtocarbon‐amendedinjectionwells35suppliedbySouthCentralAreaextractionflows.36
AsnotedinTable2‐2,theestimatedtimeperiodsforcleanupforthisalternativeareexpectedtobe37asfollows:38
Estimatedtimeto50ppb:20years39
Estimatedtimetoachieveremovalof80%ofCr[VI]massinhighconcentrationarea:15years40
Estimatedtimetointerimmaximumcleanuplevelof3.1ppbCr[VI]/3.2ppbCr[T]:50years41
Table 2‐8. Summary of Components under Alternative 4C‐5 1
OptimizationPeriodInitialBuildout(0–5years)
Year5(5–10years)
Year10(10–20years)
Year20(20+years)
AgriculturalLandApplicationAgriculturalUnits(AUs)a 575 acresAUExtractionWells 80 80 102 102AUPipeline 68,489 lf 68,489 lf 83,374 lf 83,374 lfAUExtractionFlowb 3,167gpm 3,167gpm 3,167gpm 2,618gpmIn‐SituRemediationZone(IRZ)ExtractionWells 19 19 23 23InjectionWells 90 90 91 91Pipelines 33,940lf 34,690lf 36,340 lf 36,340 lfCarbon‐amendedIRZflow(SCRIA/SAIRZ)b,c 244 gpm 244gpm 319gpm 213gpmIRZRecirculationflow(CAIRZ)b,c 279gpmEx‐SituTreatmentExtractionWells 20 20 24 24Pipelines 7,719lf 7,719lf 8,594lf 8,589lfExtractionFlow(annual) 250gpm 250gpm 250gpm 0gpmNorthwestAreaFreshwaterInjectionExtraction/InjectionWells 5/4Pipelines 36,669lfNorthwestFreshwaterReinjectionFlowb 92gpmMonitoringWells/SupportingInfrastructureMonitoringWells 558WellsandSupportingInfrastructure(acres)d 52 52 54 54Accessroads(acres) 4 4 5 5Notes:a DesertViewDairy,Gorman,Cottrell,Ranch,plusadditionalAgriculturalUnits.b Allflowsarebasedonaverageannualrates.c SCRIAreferstotheSouthCentralReinjectionArea.
SAIRZreferstotheSourceAreaIn‐SituRemediationZone.CAIRZreferstotheCentralAreaIn‐SituRemediationZone.
d Includesacreageforallwells,includingAgriculturalUnits,In‐SituRemediation,NorthwestFreshwaterReinjection,andmonitoringwells.lf=linearfeetgpm=gallonsperminute
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ICF 00122.11
Estimatedtimetointerimaveragecleanuplevelsof1.2ppbCr[VI]/1.5ppbCr[T]:95years1
Overall,incomparisontotheotherprojectalternatives,Alternative4C‐5would:2
TakelongertoachieveinterimcleanuplevelstomeetthedrinkingwaterMCLforCr[T](below350ppb)thantheotherdescribedalternatives;4
TakelongertoachieveaverageandmaximumCr[T]andCr[VI]interimcleanuplevelscompared5tootheralternatives;6
Useabove‐groundpumpandtreatintheSourceAreaIRZinsteadofin‐situtreatmentresulting7inremovalofchromiumfromthefromtheoverallsiteinsteadofconversionfromCr[VI]to8Cr[III]thusresultinginthelargestremovalofchromiummassofallalternatives;and9
Havethesamefreshwaterinjectionoperationstomaintainhydrauliccontrolasallother10describedalternatives.11
2.9.6.2 Implementation Details 12
Containment and Land Treatment 13
ThiscomponentofAlternative4C‐5wouldbethesameasthatdescribedforAlternative4C‐2;14howeverthetotalmaximumgroundwaterextractionflowsforlandtreatmentwouldbeslightly15higher.16
In‐Situ Treatment 17
In‐situtreatmentunderAlternative4C‐5wouldbesimilartoin‐situtreatmentdescribedfor18Alternative4C‐2.However,Alternative4C‐5doesnotincludein‐situtreatmentintheSourceArea19IRZ;asaresult,theoverallin‐situtreatmentimplementedunderAlternative4C‐5wouldbeless20thanthatoftheotherdescribedalternatives.21
Ex‐Situ Treatment 22
AsshowninFigure2‐8,theconceptualapproachforex‐situtreatmentactivitiesunderAlternative234C‐5includesextractingapproximately200gpmofchromiumcontaminatedgroundwaterfromthe24highestconcentrationareasintheSourceAreaIRZ,treatingitatthenearbyabove‐groundfacility25usingchemicalprecipitationandfiltrationprocesses,andreinjectingthecleanwaterintothesouth26endoftheSourceAreaIRZ.Thesolidby‐productresiduewouldbemanagedanddisposedoffsitein27thesamemannerasthatdescribedunderAlternative4C‐3.28
Monitoring Activities 29
Monitoringactivitieswouldbethesameasthosebeingimplementedunderexistingoperations30throughouttheprojectarea(asdescribedunderSection2.4above).31
Contingency Plan for Agricultural Unit Operations 32
Alternative4C‐5wouldincludeacontingencyplanasdescribedforAlternative4Babove.33
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2.10 Construction, Operation, and Maintenance 1
2.10.1 Description of Remediation Activities in Operable Units 2
AspartofAddendum3,PG&EdelineatedthreeOUs(Figure2‐2a).TheOUdelineationwasgenerally3basedonareasthatcontaindifferentplumecharacteristicsandthereforedifferentremedial4emphasis.ThespecificactivitiesthatwouldoccurwithineachOUaregenerallyasfollows:5
OU1.TheremediationemphasisinOU1istreatmentofthehighconcentrationplumethrough6eitherin‐situchromiumreductionfromCr[VI]toCr[III](allalternativesexcept4C‐5)orremoval7throughex‐situtreatment(Alternative4C‐5).In‐situtreatment(Alternatives4B,4C‐2,‐3,and‐84)inOU1willuseIRZtechnology(i.e.,treatmentbybiologicalorchemicalreductants)andwill9focusonaccomplishingtheMCLfordrinkingwater(50ppb)attheboundaryofOU1andOU2.10In‐situreductionbyproducts(e.g.,manganese,iron,arsenic)willbegeneratedthroughtheIRZ11processandprimarilymanagedwithinOU1.Duetotheaggressivenatureoftreatmentproposed12inOU1,thefringesofthe3.1ppbplumecouldtemporarilyfluctuateovertimeinresponseto13injectionandextractionactivities.Tominimizetheseeffects,hydrauliccontrolandinward14gradients(i.e.,plumecontainment)willbemaintainedaslongasnecessarytopreventCr[VI]15andbyproduct(e.g.,manganese)migration.TheagriculturalunitswithinOU1willbeusedfor16watertreatmentasappropriatetoassistwithinwardhydraulicgradientsandplumewater17balance.Alternative4C‐5wouldaddex‐situtreatmentinOU1toremoveCr[VI]fromtheaquifer18insteadofreducingittoCr[III].19
OU2.OU2isalowerconcentrationareawhereagriculturaltreatmentwouldbefocusedinall20alternatives.Theremediationemphasiswillbeongroundwaterextractionandtreatmentvia21agriculturalunits.Chromiumplumecontainmentisaccomplishedthroughthemaintenanceof22seasonaloryear‐roundinwardhydraulicgradientsproducedbynumerousgroundwater23extractionwellsandlimitedfreshwaterinjection.Watersupplypumpingintheloweraquifer1324willbeminimizedtomitigatefurtherCr[VI]impactsontheloweraquifer.Aggressivepumping25intheupperaquifer14overtheloweraquifercombinedwithminimizingloweraquiferpumping26isalsoplannedtoneutralizeorreversedownwardgradientsandmitigateCr[VI]impacts27occurringviadownwardmigration.Limitedremedialpumpingintheloweraquifermayalsobe28consideredinthefuturetoaddressthelimitedareaofcontaminationintheloweraquiferat29present.In‐situremediation,asdescribedabove,maybeappliedtoOU2toaddresshigher30concentrationsoftheplumeifand/orwhereitispresentinOU2.Anabove‐groundtreatment31plantwouldbeincludedinOU2inAlternative4C‐3toprovideforwintergroundwater32extractionandtreatment.33
OU3.AsofDecember2011,theexpandedplumeincludedover900acresinOU3.Assuch,34agriculturallandtreatmentmaybeappliedtotreattheplumeinOU3,similartothatdescribed35aboveforOU2.Groundwatermonitoringandassessmentactivitiesarecurrentlyongoinginthe36northernsectionofOU3incoordinationwiththeWaterBoard.ItispossiblethattheOU3area37(andsubsequentlytheplumeareaboundary)couldchangeintheeventmonitoringand38assessmentactivitiesshowcontinuedmigrationofchromiumcontaminationlevels.Monitoring39
13Theloweraquiferistheportionoftheaquiferlocatedbelowtheclayconfininglayer(i.e.,theblueclay)whichseparatestheupperandloweraquifer.14Theupperaquiferistheportionoftheaquiferlocatedabovetheblueclaywhichseparatestheupperandloweraquifer.
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andremedialpumpingandconveyance(toagriculturalunittreatmentunits)aretheprimary1activitiesanticipatedforthisarea.Elevatedtotaldissolvedsolids(TDS)andnitrate2concentrationsareobservedinsomeofthenorthernportionsofOU3asaresultofhistorical3agriculturaloperations.AlthoughnoremediationiscurrentlyshownforOU3inthefeasibility4studyandaddenda,itisexpectedthatnewagriculturalunitunitsmaybeplacedinOU3starting5intheareasnorthofThompsonRoadwithgroundwaterextractionwithlocalizedagricultural6unittreatment.Ex‐situtreatment(asproposedinAlternative4C‐3)couldalsobeimplemented7inOU3incombinationwithabove‐groundtreatment,ifrequired.AdjustmentofthefinalOU38boundarymaybenecessarytoaddressanymigrationofthechromiumcontaminationlevels.9
2.10.2 Construction Equipment 10
Constructionequipmentwillbeneededfortheinstallationofwellsandsupportinginfrastructure,to11developagriculturalunitsandconstructconveyancepipelinesandnewfacilitiesassociatedwith12above‐groundtreatmentplants.Thisequipmentwouldbesimilarforallalternatives.The13constructionequipmentandanticipateddurationofconstructionactivitiesaresummarizedbyeach14alternativeinTables2‐9and2‐10below.Constructionactivitiesareexpectedtooccurbetweenthe15hoursof7a.m.and7p.m.Uponcompletionofconstruction,allconstructionequipmentwillbe16removedandsiteswillbereturnedtopre‐projectconditionstotheextentpossible.17
Table 2‐9. Required Construction Equipment and Infrastructure. 18Alternative ConstructionActivity EquipmentAllAlternatives
Pipelineinstallation ExcavatorBackhoeFront‐endloaderMotorgraderWatertruckUtilitypotholingmachineUtility/support/weldingtruck
Jumpingjackcompactor(aroundvaults)VibratoryplatecompactorTrenchrollercompactorGeneratorCompressorHDPEweldingmachine
Wellinstallationanddevelopment
DrillrigAuxiliarycompressorConcretewellvault480‐voltpowerdropandmotorcontrolpanelHDPEgroundwaterconveyancepipingSSsubmersiblegroundwaterextractionpump120‐voltpowerconduit
SupporttruckForkliftPVCandSSwellcasing120‐voltcontrolpanelwithradiocommunicationsSteelwellheadpipingSecurityfencingActuatedvalvesandswitches
Alternatives4C‐3and4C‐5only
Above‐GroundTreatmentFacilityGrading/excavation Motorgrader
BackhoeUtility/support/weldingtruck
RubbertireddozerFrontendloaderWatertruck
Paving/concrete Cement/mortarmakerRollerMotorgraderChopsawforsteelreinforcementVibratoryplatecompactorUtility/support/weldingtruck
PaverFront‐endloaderwithforksWatertruckConcretesawGenerators
Buildingconstruction
CraneTractor/loader/backhoeCutoffsawordemolitionsawVibratoryplatecompactorUtility/support/weldingtruck
ForkliftFront‐endloaderwithforksConcretesaw
Source:PacificGasandElectric2011d,2012Notes:HDPE=High‐densitypolyethylene,PVC=Polyvinylchloride,SS=Stainlesssteel
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Table 2‐10. Typical Timeframes by Alternative 1
AlternativePipelineaInstallation
WellInstallationandDevelopmenta
TreatmentFacility—GradingandExcavation
TreatmentFacility—PavingandConcrete
TreatmentFacility—BuildingConstructiona
NoProject 5months 16months n/a n/a n/a
Alternative4B 3months 6months n/a n/a n/a
Alternative4C‐2 4months 11months n/a n/a n/a
Alternative4C‐3 6months 16months 1month 2months 12months
Alternative4C‐4 7months 11months n/a n/a n/a
Alternative4C‐5 4months 11months 1month 2months 12monthsa ThedurationassumesfullbuildoutasdefinedintheFeasibilityStudyandAddenda.DurationsforactionsrelativetothelargerplumeareassumedtobethesameasdescribedinFeasibilityStudyandAddendaindicatinghigherintensityofactivitywithhigherinfrastructureconstruction.
2.10.3 Construction Activities 2
2.10.3.1 Wells and Agricultural Units 3
Constructionofnewwellswouldinvolveaminimalamountoflandclearing,welldrillingandwell4casingplacement,installationofwellpadsandmounts,installationofsupportingequipment5(e.g.,pumps)andmixingtanks(forwellsusedinin‐situtreatment),installationofconveyance6piping,andinstallingexclusionaryfencingaroundthewelloperationalarea.7
Constructionofnewagriculturalunitswouldinvolvelandclearing,plantingofcrops,installationof8irrigationsystems,andinstallationofconveyancepipingtocarrywaterpumpedfromextraction9wellsforlandapplication.Newaccessroadsmayberequiredtoreachwellsandagriculturalunits10withtheirassociatedsupportinginfrastructureinareasthatwerepreviouslyundisturbed.These11accessroadswouldprimarilybeunpavedandconsistoflandclearedtoaccommodatethelargest12pieceofequipment(abouta10‐footwidelane).Itisestimatedthatapproximately3–6workersper13daywouldberequiredforinstallationanddevelopmentofawellandapproximately15workersper14daywouldberequiredforpipelineinstallation.15
2.10.3.2 Ex‐Situ Treatment Facilities 16
Constructionoftheex‐situ(above‐ground)facilitieswouldinvolvesitepreparationthroughgrading17andexcavation,pavingandconcretepouringforbuildingfoundations,andconstructionofthe18treatmentfacilitybuildingandotherstructures.Newutilitiesincludingpowerconnections19(includingbackupdieselgenerators),septicsystems(fornon‐processandnon‐labwastewater),and20telecommunicationsconnectionsalsowouldbeinstalled.Anewpavedroadwouldbeconstructedto21provideaccesstothetreatmentfacilityfromtheneareststreet.Therewouldbeapproximately5–1922workersonsiteperdayduringconstructionactivities.Uponcompletionofconstruction,all23constructionequipmentwouldberemovedandsiteswouldbereturnedtopre‐projectconditionsto24theextentpossible.Thesizeoftheabove‐groundfacilityisdescribedunderEx‐SituTreatment25Facilitiesbelow.26
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2.10.4 Operations and Maintenance Activities 1
Operationsandmaintenance(O&M)activitieswouldbesimilartocurrent,ongoingactivitiesand2wouldbesimilaracrossallalternativesforeachtypeoftreatmentbeingimplemented.Thescaleof3activitywouldincreasefromexistinglevelsandwouldvaryinscalefordifferentprojectalternatives.4
2.10.4.1 Wells 5
Operatingcharacteristicsforfutureextractionandinjectionwellswouldbesimilartotheoperating6characteristicsofexistingwells.Extractionwellssupplyingwatertoagriculturalunitswould7operatemostlyatnight,andthelevelofpumpingactivitycouldvaryoverthecourseoftheyear.8(Operationsandmaintenanceactivitiesassociatedwithagriculturalunitsaredescribedbelow.)IRZ9extractionandinjectionwellswouldlikelyoperatecontinuously,andflowcouldvarybasedonthe10relativeoptimizationyear.SourceAreaIRZwellsandthefreshwatersupplywellPG&E#14are11connectedtotheHinkleyCompressorStation’selectricalsupply.Itisexpectedthatpowertonew12IRZwells(notwithintheSourceAreaIRZ)wouldcomefromtie‐instotheexistinginfrastructure13andwouldbepoweredbytheelectricgrid.Itisexpectedthat2to4additionalworkerswouldbe14neededtooperateandmaintainnewwellandassociatedfacilities.15
ThemainoperationsandmaintenanceactivitiesatIRZwellswouldinclude:16
Dailysystemchecks(e.g.,onsitesysteminspections);17
Collectionofoperatingdataatwellandotherfacilitysites(e.g.,water‐levelmeasurements,tank18readings);19
Adjustmentofpumpoperations;20
CompletingCentralArea,SourceArea,andSouthCentralAreainjections;21
Periodiccleaning,includinghandlingofbackwashwater;22
Periodictroubleshooting,repairs,andreplacementofcomponents;23
Collectionofwaterqualitysamplesforlaboratoryanalysis;24
Periodiccleaningormaintenanceofpipelines,tanks,andappurtenances;25
Removalandcleaningormaintenanceofdownholeequipmentsuchaspumps,pipes,andvalves;26and27
As‐neededmanualcarbonsubstrateaddition.28
Freshwatersupplywellswouldcontinuetobeoperatedasunderexistingconditions.Thesame29generalO&MactivitieswouldoccuratthesewellsasundertheIRZwells.Inaddition,O&Mactivities30atthesewellswouldrequireadjustmentofflowratesinextractionwellsandinindividual31freshwaterinjectionwellstooptimizehydraulicmounding.32
Desert View Dairy Land Treatment Unit 33
OperationsandmaintenanceactivitiesassociatedwiththeDesertViewDairylandtreatmentunit34wouldcontinueasexistingconditionsandinclude:35
Performingdailysystemchecksforleaks,potentialtroubleshootingandrepair,andgeneral36maintenanceneeds;37
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Collectingsystemflow,pressure,andtotalizerreadingsinextractionwellsandboosterpump1andperformingvisualinspectionofinstrumentationandequipment;2
Adjustingflowratesinindividualextractionwellstooptimizeirrigationratesand/orhydraulic3capture;4
Collectingwaterdepthmeasurementsatextractionwellsandsamplesfromlysimetersand5monitoringwellsforlaboratoryanalyses;6
Planting,coordinatingharvestscheduling,andevaluatingcrophealth;7
Periodictroubleshooting,maintenance,andrepairofpumpsandothersystems;8
Periodicwellrehabilitationandredevelopment;9
Periodiccleaningormaintenanceofpipelinesandappurtenancesviasurgingorchemical10injection;11
Removalandcleaningormaintenanceofdownholeequipmentsuchaspumps,pipes,andvalves;12and13
Replacementofequipmentoverthecourseofoperations.14
Agricultural Units 15
Operationsandmaintenanceactivitiesassociatedwithlandtreatmentviaagriculturalunitswould16besimilartoexistingagriculturalunitoperations,whicharealsosimilartotheDesertViewDairy17landtreatmentunitoperations.O&Mactivitiesatnewagriculturalunitswouldinclude:18
Checkingwaterapplicationratestoevaluategroundwaterextractionforhydrauliccontrol;19
Routineinspectionandmonitoringofextractionwellperformance;20
Routineinspection,repair,andmaintenanceoffiltersandsystemparts;21
Planting,coordinatingharvestscheduling,andevaluatingcrophealth;22
Periodicwellrehabilitationandredevelopment;23
Periodiccleaningormaintenanceofpipelinesandappurtenances;24
Periodicpumptroubleshootingandrepair;25
Removalandcleaningormaintenanceofdownholeequipment–pumps,pipes,andvalves;and26
Replacementofequipmentoverthecourseofoperations.27
Itisexpectedthat1to3additionalworkerswouldbeneededtooperateandmaintainthenew28agriculturalunits.29
Ex‐Situ Treatment Facilities 30
Asdescribedabove,therewouldbetwoex‐situ(above‐ground)treatmentfacilitiesunder31Alternative4C‐3andonetreatmentfacilityunderAlternative4C‐5.Figures2‐6and2‐8,32respectively,showtheapproximatelocationsoftheex‐situtreatmentfacilities.Eachoftheproposed33above‐groundtreatmentfacilitieswouldbelocatedinacompoundapproximately40,500square34
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feetinsize.15ForAlternative4C‐3,onefacilitywouldtreatwaterfrommostlynorthofSR58andone1wouldtreatwaterfrommostlysouthofSR58.ForAlternative4C‐5,thefacilitywouldonlytreat2waterintheSourceAreasouthofSR58.Eachtreatmentfacilitywouldincludetreatmentwells,3conveyancesystemoperations,a35‐foottallprocessbuildingandanoffice/laboratory,and12‐foot4highsecurityfencingwithbrownslats.Theprocessbuildingswouldhousepumps,pipes,reactors16,5filters,andotherequipmenttotreatthecontaminatedwater.Theoffice/laboratorieswouldinclude6officespaces,acontrolroom,restrooms,andalaboratory.Theareawithinthecompoundwouldbe7paved,wouldincludeaconcreteloadingdockforoutgoingwasteandincomingmaterials,andwould8includeexteriorfloodlighting.Watertanksandotherappurtenantstructuresmaybehousedinthe9compoundareas.Operationsofnewfacilitieswouldbepoweredbytheexistingelectricgrid.Waste10residuefromex‐situwatertreatmentwouldbetransportedanddisposedoff‐siteattheWaste11ManagementKettlemanHillsFacilityorasimilarClassIlandfillpermittedtoaccepthazardous12wastesasauthorizedunderTitle27oftheCaliforniaCodeofRegulations.Operationsand13maintenanceactivitiesassociatedwithex‐situtreatmentfacilitieswouldprimarilyinclude:14
Monitoringandmaintenanceofex‐situtreatmentwellsandconveyancesystemoperations;15
Collectingandanalyzingmid‐treatmentsamplesattheon‐sitelab;16
Measuring,tracking,andchangingoperationalandprocessparametersasneeded;17
Schedulingtrashandlabwastepickupandtransportationtoalandfill;18
Schedulingmaterialsdelivery;19
Mechanicalmaintenanceofallequipment;and20
Inspectionandmaintenanceofallsupportingstructures.21
Onetothreeworkerswouldbepresentatalltimes(24‐hoursaday)ateachtreatmentfacilitythat22maybeconstructed,workingin2–3shiftsperdaytoconductallO&Mactivities.23
2.11 Other Alternatives Considered but Dismissed 24
from Further Analysis 25
CEQArequiresthattheleadagencyconsideralternativesthatwouldavoidorreduceoneormoreof26thesignificantimpactsidentifiedfortheprojectinanEIR.TheCEQAGuidelines(Title14ofthe27CaliforniaCodeofRegulations)statethattherangeofalternativesrequiredtobeevaluatedinanEIR28isgovernedbythe“ruleofreason”;theEIRneedstodescribeandevaluateonlythosealternatives29necessarytoallowareasonablechoiceandtofosterinformeddecision‐makingandinformedpublic30participation(CEQAGuidelinessection15126.6[a][f]).Detailedconsiderationofalternativesfocuses31onthosethatcaneithereliminatesignificantadverseenvironmentalimpactsorreducethemtoless‐32than‐significantlevels;alternativesconsideredinthiscontextmayincludethosethataremore33costlyandthosethatcouldimpedetosomedegreetheattainmentofalltheprojectobjectives(CEQA34Guidelinessection15126.6[b][f]).CEQAdoesnotrequirethealternativestobeevaluatedinthesame35levelofdetailastheproposedproject.36
15Theprecisesizeofthetreatmentfacilitydependsonthealternative.16Thisisavat(i.e.,vatreactor)wherethecontaminatedwaterisplacedtoreactwithsubstances.
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Aspartofthealternativesdevelopmentprocess,arangeofreasonablechromiumcleanup1alternativeswasevaluatedinthe2002and2010feasibilitystudiesandthethreeaddendatothe22010FeasibilityStudy.Thesealternativesincludesuggestionsbymembersofthepublicduringthe3EIRscopingprocess.4
Outofthesealternatives,fiveprojectalternatives(4B,4C‐2,4C‐3,4C‐4,and4C‐5,asdescribed5above)wereselectedfordetailedanalysisinthisEIR.6
Theotheralternatives,alldescribedbelow,eitherdonotmeettheprojectgoalandmostofthe7objectives,orhavefeasibilityoreffectivenessconcernsthatprecludedthemfromfurther8consideration.Thealternativesaredescribedbrieflybelow,andthereasonstheyweredismissed9fromfurtherconsiderationareidentified.10
2.11.1 2010 Feasibility Study Alternative 1—Natural 11
Attenuation 12
Thisalternativeassumesnofuturepumpingorgroundwatertreatment;thus,currentcontainment13pumping,agriculturalwatertreatment,andin‐situchromiumtreatmentoperationswouldbe14discontinued.Thisalternativewouldtakemorethan1,000yearstoreduceCr[VI]concentrationsto153.1ppb.Thisalternativedoesnotmeetthefundamentalprojectobjectivesbecauseitdoesnotclean16upchromiuminthegroundwaterwithinameaningfulperiodoftime.17
2.11.2 2010 Feasibility Study Alternative 2—Containment Only 18
Themainoperationalfeaturesofthisalternativeincludeplumecontainment/hydrauliccontrol19throughgroundwaterextractionfollowedbytreatmentanduseofextractedgroundwaterfor20agriculturalapplication.AlloperationswouldoccurnorthofSR58.Thisalternativewouldtake21approximately120yearstoreduceCr[VI]concentrationsthroughouttheplumeto50ppb,260years22toreduceCr[VI]concentrationsto3.1ppb,and320yearstoreduceCr[VI]concentrationsto1.2ppb.23Thisalternativedoesnotmeetthefundamentalprojectobjectivesbecauseitdoesnotcleanupthe24groundwaterwithinameaningfulperiodoftime.25
2.11.3 2010 Feasibility Study Alternative 3—Plume‐Wide In‐Situ 26
Treatment 27
TheconceptualapproachforAlternative3istoutilizeextractionwellsatthepointoftheplume28farthestawayfromthesourcetoprovidehydrauliccontainment,addcarbonamendmenttothe29extractedwater,andinjectthecarbon‐amendedwaterintowellstocreateIRZs.Thisalternative30wouldtakeapproximately8yearstoreduceCr[VI]concentrationsthroughouttheplumeto50ppb,31approximately110yearstoreduceCr[VI]levelsto3.1ppb,and180yearstoreduceCr[VI]32concentrationsto1.2ppb.Thisalternativedoesnotmeetthefundamentalprojectobjectives33becauseitdoesnotcleanupchromiumingroundwaterwithinameaningfulperiodoftime.34
2.11.4 2010 Feasibility Study Alternative 4—In‐Situ Remediation 35
and Land Treatment 36
Thisalternativewouldbesimilartothegeneralcombinedtreatmentapproachpresentlyoperating37intheprojectarea(in‐situremediationandagriculturallandtreatment)andthatproposedin38
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Alternatives4Band4C‐2.Asoriginallyproposedinthe2010FeasibilityStudy,thisalternativewas1onlydesignedtoaddresstheextentofthechromiumplumethatwasknownasofFebruary2010,2whichisfarsmallerthantheplumenowknowntoexistasoflate2011andwouldhaveagricultural3unitsandpumpingsimilartowhatisalreadyoccurring,butwouldhaveincreasedIRZtreatment.4Thisalternativewouldtakeapproximately6yearstoreduceCr[VI]concentrationsthroughoutthe5plumeto50ppb,approximately150yearstoreduceCr[VI]concentrationsto3.1ppb,and220years6toreduceCr[VI]concentrationsto1.2ppb.Thisalternativedoesnotmeetthefundamentalproject7objectivesbecauseitdoesnotcleanupchromiumingroundwaterwithinameaningfulperiodof8time.9
2.11.5 2010 Feasibility Study Alternative 5—Plume‐Wide Pump 10
and Treat 11
Thisalternativewouldfocusonplumecontainmentandex‐situtreatmenttoreduceCr[VI]12contaminantmasswhileprovidingsupplementalcontainmentthroughrechargingthetreated13groundwatertotheperipheryoftheplume.Thisalternativeprovidesalevelofhydraulic14containmentsimilartoAlternative2,althoughwithadifferentgroundwaterwithdrawal15configuration.Thisalternativewouldtakeapproximately50yearstoreduceCr[VI]concentrations16throughouttheplumeto50ppb,approximately140yearstoreduceCr[VI]concentrationsto3.117ppb,and210yearstoreduceCr[VI]concentrationsto1.2ppb.Thisalternativedoesnotmeetthe18fundamentalprojectobjectivesbecauseitdoesnotcleanupchromiumingroundwaterwithina19meaningfulperiodoftime.20
2.11.6 2010 Feasibility Study (Addendum 1) Alternative 4A—21
Aggressive In‐Situ Treatment with Beneficial Agricultural 22
Use 23
Alternative4Awasdevelopedtofurtheraccelerateclean‐upperiodstomeettheprojectobjectiveof24timelycleanup.Alternative4AwasenlargedinscaleoverfeasibilitystudyAlternative4byan25increaseintheCentralAreaIRZ,expansionofagriculturalunits,increasingIRZoperationsby1526years,andincreasingthevolumeofgroundwaterextractionforapplicationtoexpandedagricultural27units.Alternative4AwouldcleanupCr[VI]contaminationtothemaximuminterimcleanuptarget28levelof3.1ppbin75yearsandtotheaverageinterimcleanuptargetlevelof1.2ppbin130years.29Thesetimeperiodswouldnotadequatelymeettheobjectivesoftheproject.30
2.11.7 2010 Feasibility Study (Addendum 1)—Combined 31
Alternative 32
TheCombinedAlternativewasdevelopedasanalternativemethodforacceleratingremovalof33Cr[VI]fromthehighconcentrationareaoftheplumethroughadditionofex‐situtreatmentatan34above‐groundfacility.TheCombinedAlternativewouldcleanupCr[VI]contaminationtothe35maximuminterimcleanuptargetlevelof3.1ppbin90yearsandtotheaverageinterimcleanup36targetlevelof1.2ppbin130years.37
ThisalternativewouldbeslowerthanAlternative4B,anyofthealternativesdevelopedunder38Addendum3,andAlternative4C‐5,whichincludesabove‐groundtreatment(includedinthe39
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detailedanalysisintheEIR).Thisalternativedoesnotachievetheprojectobjectiveoftimely1cleanupand,therefore,doesnotmeaningfullyexpandtherangeofalternativesforanalysis.2
2.11.8 2010 Feasibility Study (Addendum 3) Alternative 4C‐1—3
In‐Situ and Enhanced Agricultural Treatment (1 crop) 4
Alternative4C‐1wasdevelopedtofurtherexpandonthein‐situandagriculturaltreatment5approachesdevelopedunderAlternative4B.Themaingoalsofdevelopingthisalternativewereto6optimizeandincreaseextractionrelatedtoplumecapture,mitigateplumemigrationtotheeast,7reducetheincidenceoftheuntreatedareasintheIRZ,reduceformationofmanganeseasaby‐8productofin‐situreduction,andattempttofurtherreducetheoverallremediationtimeframe.This9alternativedoesnotacceleratecleanuptimeperiodsorprovideadditionalbenefitbeyondthat10providedbyAlternatives4B,4C‐2,4C‐3,4C‐4,or4C‐5,andthusdoesnotmeaningfullyexpandthe11rangeofalternativesforanalysis.12
2.11.9 Other Alternative Technologies Considered in the 13
2010 Feasibility Study 14
Thefollowinglistdescribestherangeofotheralternativetechnologiesforchromiumcleanup15consideredinthe2010FeasibilityStudythatweredismissedfrommoredetailedanalysisor16considerationintheEIR.Thesealternativeswerescreenedoutbecauseeither(1)theydonotmeet17theprojectgoalandmostoftheobjectivesor(2)feasibilityoreffectivenessconcernsprecluded18themfromfurtherconsideration.Thesealternativesarebrieflydescribedbelow,andthereasons19theyweredismissedfromfurtherconsiderationareidentified.20
AlternativeWaterSupply:Developaplantosupplyalternativewatertolocalresidentsanda21monitoringprogramtolimituseofcurrentlyaffecteddomesticgroundwaterwells.Thiswould22requireagroundwaterpipinginfrastructurefromthenewwell(s).Thisalternativealonewould23notresultinremediationofthecontaminatedaquiferandwouldnotreturnittobeneficialuse.24Asdescribedabove,the2011CAO(No.RV6‐2011‐005)requiresPG&Etoprovideinterimand25wholehousereplacementwaterservicetothoseservedbydomesticorcommunitywellsthat26arewithintheaffectedareaanddeterminedtobeimpactedbyitsdischarge.TheOrderdefined27impactedwellsasalldomesticorcommunitywellsintheaffectedareathatareabove3.1ppb28hexavalentchromiumor3.2ppbtotalchromiumplumeboundaries,baseduponmonitoringwell29datadrawninthemostcurrentquarterlysite‐widegroundwatermonitoringreportsubmitted30byPG&E.TheOrderalsodefinedimpactedwellsasthosedomesticorcommunitywellsinthe31affectedareathatcontainhexavalentchromiuminconcentrationsgreaterthan0.02ppbthat32weretheresultofPG&E’sdischargeattheFacility.Asaresult,thisremedialactionisalready33requiredandneednotbeconsideredasanalternative.34
Containment—Capping:Coveraffectedareaswithanimpermeablecap(i.e.,engineered,native35soils,orimportedsoilcaps)tomitigateinfiltrationandaidingroundwatertransport36retardation.Thisalternativewasnotretainedbecauseitisconsiderednottobeeffectivedueto37limitedrainfallintheregion,influencesofareaagriculturalpumping,andthedepthof38contaminatedgroundwater.Thisalternativealsowouldnotrestorebeneficialusestothe39aquifer.40
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Containment—PhysicalBarriers:Installaverticalorhorizontalphysicalbarrierthatlimits1themigrationoftheaffectedgroundwater.Thislikelywouldbeincorporatedinconjunction2withagroundwaterextractionsystem.Thisalternativeiseffectiveinlocalizedareas,butitwas3notretainedbecausetheextent(5.4milesby2.4miles)andmobilityoftheplumealongwiththe4requireddepths(>100feet)wouldmakeitinfeasibletoeffectivelycontroltheplumeusingthis5method.6
In‐SituBiologicalTreatment—AerobicBioremediation:Addanoxidativesubstratetothe7subsurfacetoaerobicallydegradeCr[VI].Thisalternativewasnotretainedbecauseitisnot8applicabletoCr[VI]asthismaterialisalreadyinanoxidizedstateandneedstobereduced9ratherthanoxidized.10
In‐SituBiologicalTreatment—Phytoremediation:Useplantsandtheirassociated11rhizosphericmicroorganismstoremove,degrade,orcontaincontaminantsingroundwater.This12alternativewasnotretainedbecausetheextentofgroundwatercontaminationistoodeepfor13thisdirectapplicationtobeeffective.However,theagriculturallandtreatmentincludedinall14projectalternativesoperatesonthesameprincipalsasthisalternative,butusesagricultural15cropsandtheirmicroorganisms.Thereforethisalternativeisincorporatedinitsgeneral16approachintotheprojectalternatives.17
In‐SituPhysical/ChemicalTreatment—AirSparging:Injectairintothesubsurfaceto18volatilizethecontaminantandenhanceaerobicconditionstoaccelerateaerobicbiological19remediationofplume.Thisalternativewasnotretainedbecauseairspargingisnotapplicable20forCr[VI],whichisnotvolatileandalreadyexistsinanoxidizedstate.21
In‐SituPhysical/ChemicalTreatment—ElectrokineticTreatment:Createelectricalfieldsby22applicationoflow‐voltagepowertosubsurfaceelectrodestoalterredoxstateandtoimmobilize23certainconstituentsin‐situ.Althoughthisalternativeiseffective,itwasnotretainedbecauseit24iscost‐prohibitiveduetothelargesizeoftheplume.Inaddition,thistechnologyisonlyeffective25inareasofhighcontaminantconcentrations,butnotforrelativelylowCr[VI]concentrationsand26highaquiferpermeabilitycharacteristicoftheplume.27
In‐SituPhysical/ChemicalTreatment—DualPhaseExtraction:Applyahigh‐powered28vacuumsystemtosimultaneouslyremovesoilvapors,groundwater,andotherliquid(i.e.,29nonaqueous‐phaseliquid)fromlow‐permeabilityorheterogeneoussubsurfaceenvironments.30ThisalternativewasnotretainedbecauseCr[VI]isnotvolatile,andthistechnologyhasnotbeen31proventoreduceCr[VI]concentrations.32
In‐SituPhysical/ChemicalTreatment—PermeableReactiveBarriers(PRBs):Install33permeabletreatmentwalls(i.e.,zero‐valentironPRBs)usingtrenches,fracturing,boreholes,or34othermeanstocreateabarrierwallacrosstheflowpathofacontaminantplume.As35groundwatermovesthroughthetreatmentwall,contaminantsarepassivelyremovedinthe36treatmentzonesbyphysicaland/orchemicalprocesses.Althoughthisalternativeiseffective,it37wasnotretainedbecauseitisnotfeasibleduetothedepthofcontamination,whichisatthehigh38endoftraditionaltrenchapplicationtechnologylimits.39
In‐SituPhysical/ChemicalTreatment—In‐SituAirStripping:Injectairintothesubsurface40(throughcirculatingcells,vacuumvaporextraction,etc.)atahighratetostripCr[VI]outofthe41groundwater;theprocessalsooxidizesthetreatmentarea.Thisalternativewasnotretained42becauseairstrippingisnotapplicableforCr[VI],whichisnotvolatileandalreadyexistsinan43oxidizedstate.44
California Regional Water Quality Control Board, Lahontan Region Project Description
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In‐SituPhysical/ChemicalTreatment—In‐SituChemicalOxidation:Injectanoxidantsuch1ashydrogenperoxideorpotassiumpermanganatetooxidizetheaffectedareas.Thisalternative2wasnotretainedbecausechemicaloxidationhasnotbeenproventoreduceCr[VI]3concentrationsbecauseCr[VI]alreadyexistsinanoxidizedstate.4
In‐SituThermalTreatment—SteamInjection,6‐PhaseHeating,ElectricalResistance:Use5heattovolatilize,oxidize,ormobilizeCr[VI].Thisalternativewasnotretainedbecauseitisnot6applicableforreducingCr[VI]concentrationsasCr[VI]alreadyexistsinanoxidizedstate,isnot7volatile,andneedstobereduced.8
Ex‐SituBiologicalTreatment—AerobicBioremediation:Addanoxidativesubstratetoa9bioreactortoaerobicallydegradeCr[VI].Thisalternativewasnotretainedbecauseitisnot10applicableforreducingCr[VI]concentrationsasCr[VI]alreadyexistsinanoxidatedstateand11needstobereduced.12
Ex‐SituPhysical/ChemicalTreatment—ChemicalOxidation:Extractgroundwaterfromthe13subsurfaceandaddanoxidantsuchashydrogenperoxideorpotassiumpermanganatetothe14flowtooxidizetheaffectedgroundwater.Thisalternativewasnotretainedbecauseitisnot15applicableforreducingCr[VI]concentrationsasCr[VI]isalreadyinanoxidatedstateandneeds16tobereduced.17
Ex‐SituPhysical/ChemicalTreatment—AirStripping:Extractwaterandpassitthroughan18airstrippertostripCr[VI]fromthegroundwatertotheair.Thisalternativewasnotretained19becauseitwouldnotbeeffectiveasCr[VI]isnotvolatileandthereforewillnotstripoutof20water;inadditionthetechnologyhasnotbeenproventoworkforremovingCr[VI]fromwater.21
Ex‐SituPhysical/ChemicalTreatment—ElectrocoagulationProcess:Useelectricitypassed22throughironplatestogenerateferrousirontoreducethechromiumandprecipitateitfrom23solution.Theresultingsludgeissettledinaclarifierandthendisposed.Thisalternativecanbe24effectivebutwasnotretainedbecauseitisnotfeasibleatthesiteduetohighcapitalandO&M25costs,andbecausethesizeoftheexistingdiffuseplumeandtreatmentflows.26
Ex‐SituPhysical/ChemicalTreatment—Liquid‐PhaseCarbonAdsorption:Pump27groundwaterthroughaseriesofcanistersorcolumnscontainingactivatedcarbontowhich28dissolvedorganiccontaminantsareadsorbed.Periodicreplacementorregenerationof29saturatedcarbonisrequired.Thisalternativewasnotretainedbecauseitisgenerallynot30applicabletoCr[VI]treatment,andbecauseCr[VI]doesnotabsorbtocarbonmediaasorganic31carboncontaminantsdo.32
Discharge/Injection—Off‐SiteManagementatPermittedFacility:Pumpgroundwaterfrom33theplumeandpipeorshipittoanoff‐sitetreatmentfacility.Thisalternativewasnotretained34becausetheprojectareaislocatedinaremoteareaandnotreatmentfacilityislocatedwithina35suitabledistanceforthisoption,especiallyinlightoftheamountofcontaminatedwaterthat36wouldhavetobepipedorshippedconsideringtheplumeextentandextractionflows.In37additiontothepotentialnegativeenvironmentalimpactsofextensiveshipping,offsitedisposal38wouldreducegroundwateravailabletosurroundingagriculturaloperations.39
Discharge/Injection—DischargetoSurfaceWater:Treatgroundwaterusingex‐situ40remediationbyanapprovedtreatmentmethodandthendischargetreatedwatertosurface41receivingstreams.Althoughthisalternativeiseffective,itwasnotretainedbecausethe42preferenceistokeepwaterwithinprojectboundariesandreturnittotheaquiferifpossible,43andtherealsoarenoreceivingsurfacewaterstreamswithactiveflowinthearea.44
California Regional Water Quality Control Board, Lahontan Region Project Description
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Discharge/Injection—DischargetoEvaporationPonds:Usesurfaceimpoundmentsto1containtreatedoruntreatedgroundwateruntilitevaporates.Evaporationpondsfortemporary2storageofextractedwaterwereevaluatedasacontingencytoinjectionoragricultural3application.Evaporationpondswouldbedesignedwithimpermeablelinerstoprevent4infiltrationofstoredwater,aleakdetectionsystem,andaccesscontrolstopreventaccesstothe5pondsbyunauthorizedpersonnelorwildlife.Thepondswouldpossiblyrequireclassificationas6permittedWasteManagementUnitsbasedonthequalityofthestoredwater.Pondswould7requirelargesurfaceareastocompletelyevaporatestoredwaterinareasonabletime.A8minimumofapproximately330acresofstoragepondswouldberequiredtoevaporate9extractedwaterwithinoneyear.Theconcentrationofdissolvedconstituentswouldincreaseas10storedwaterevaporates,possiblyrequiringfurthertreatmentoroff‐sitedisposalofremaining11concentratedwaterorsludge.Evaporatedwaterwouldnotbeputtobeneficialuses,suchasfor12agriculture,orinjectedtoenhanceplumecontrol.Itismorefeasibletotreat,irrigate,or13otherwiseactivelymanageextractedwateratthetimeofextractionratherthantostoreiton‐14sitebecauseon‐sitestoragewouldrequiresomuchlandandalsomayrequirefurtheron‐siteof15off‐sitetreatment.Thisalternativewasnotretainedbecausespacerequirements,potential16environmentalimpacts(e.g.,theconversionofagriculturallandtoponds),andreduced17groundwateravailabilityforagriculturerenderthealternativeunattractive.18
Thefollowinglistdescribesotheralternativesconsideredforchromiumcleanupinthe201019FeasibilityStudythatinitiallywereretainedduringthealternativesscreeningandwerepilot‐tested20orresearchedforapplicationatthesite.Althoughthesealternativeswereinitiallyretained,they21ultimatelywerenotincludedascoreelementsoftheremedialalternativesbecausethereareother22technologiesincludedinthefiveactionalternativesanalyzedinthisEIR(agriculturalland23treatment,in‐situremediation,andex‐situremediation)thathavebeenfoundtobemoresuitedfor24usebasedonpastsiteexperienceorotherconsiderations.Thesetechnologyalternativesmayplaya25roleinthefutureassubstitutesforthecoreelements(forexample,anionexchangesystemcouldbe26substitutedforachemicalreduction/precipitationsystemforuseinanex‐situtreatmentplant).27Thesealternativesarebrieflydescribedbelowandthereasonstheywerenotselectedasthecurrent28primarytechnologyatthistimeareidentified.29
Direct‐PushTechnology(DPT):Directlyinjectreducingagentsatvariousgroundwaterdepths30ineachoftheDPTinjectionpoints.TracerstudyresultsindicatedDPTisnoteffectiveforfull‐31scaleimplementationbecausethedistributionofinjectedamendmentintargetareaswas32unpredictableandwouldrequireverycloseinjectionspacing(PacificGasandElectricCompany332010).34
InfiltrationGalleriesforIn‐SituCr[VI]ReductionintheVadoseZone:Divertcontaminated35groundwaterthroughasubsurfaceinfiltrationgallery(gravel)andamendtheinfiltratedwater36withethanolandthetracerdyeeosine.PilotStudyresultsindicatedinfiltrationgalleriescanbe37effective,buttheycouldgenerateby‐productssuchasiron,manganese,andarsenic(similarto38IRZoperations),theydonotprovideforanybeneficialuseofgroundwater(e.g.,forcrop39production),andfull‐scaleinfiltrationgallerieshavenotbeentestedorprovenatthesite.40
Ex‐SituTreatmentUsingIonExchangeUnits:RemoveCr[VI]inextractedgroundwaterusing41ionexchangetechnology.Althoughthistechnologywasnotrecommendedforuseintheex‐situ42treatmentplantspresentedinthefeasibilitystudy,thetechnologymaybebeneficialinspecific43circumstancesthatariseastheprojectevolves.Giventhesimilaritiesofenvironmentalimpacts44expectedforionexchangetochemicalreduction/precipitation,theanalysesinthisEIRforex‐45
California Regional Water Quality Control Board, Lahontan Region Project Description
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situchemicalreductionwouldbeapplicabletoion‐exchangeaswell.Intheionexchange1process,theCr[VI]isremovedbyexchangewithanotherinertion.Ion‐exchangecanbedone2througheitheraStrong‐BaseAnion(SBA)ExchangeoraWeak‐BaseAnion(WBA)Exchange.3BothwerereviewedforpotentialapplicationatHinkleyasdiscussedbelow.4
TheSBAexchangeprocessisgreatlyinfluencedbysulfateconcentrations.TheSBAresins5haveahigherselectivityforsulfatecomparedtootheranions.Hinkleygroundwaterhas6highconcentrationsofsulfate(relativetocomingledCr[VI]concentrations)thatseverely7affecttheperformanceandfeasibilityofSBAexchangeprocesses.TheLawrenceLivermore8NationalLaboratory(LLNL)evaluatedtheuseofSBAresinstoremoveCr[VI]from9groundwater.AttheLLNLSite,theaverageCr[VI]andsulfateconcentrationswere10respectively34ppband38ppm(LLNL1997).FortheLLNLstudy,thebreakthroughfor11Cr[VI]occurredatlessthan6,000bedvolumes,whichtranslatetoapproximately10daysof12runtimeat2.5minutescontacttime.TheCityofGlendaleevaluatedseveralSBAresinsfor13treatinggroundwaterwithCr[VI]andsulfateconcentrationsof100ppband87ppm,14respectively(WRFReport2007).Thenumberofbedvolumesforbreakthroughwas400to151,700,whichtranslatetoapproximately1to3daysofruntime.AttheHinkleySite,Cr[VI]16concentrationsinthediffusedowngradientareaoftheplumecanrangeaslowas17approximately2.5to4.5ppbwithsulfateconcentrationsintherangeof186to700ppm.18SulfateconcentrationsareseveralordersofmagnitudehigherthanCr[VI]concentrations19throughoutthediffusedowngradientplume.Underthesegroundwaterconditions,20anticipatedruntimebeforebreakthroughforSBAresinsislessthanoneday.Rigorouspilot21testingandcontinuousmonitoringandoperationofSBAvesselsinserieswouldbe22necessarytoavoidsubstandardperformancedueto“chromatographicpeaking,”whichisa23phenomenainwhichlesspreferentiallyabsorbedionsappearintheeffluentathigher24concentrationsthantheyappearintheinfluentastheyarereleasedfromionexchangeresin25whenmorestronglyheldionsareadsorbed.Duetointerferencefromhighlevelsofsulfate26insomeareasandexpectedshorttimetobreakthrough,theSBAexchangeprocessisnot27recommendedforfurtherconsiderationforlarge‐scaleremediationatHinkley17(PacificGas28andElectric2011c).29
TheWBAexchangeprocessislesssensitivetoco‐occurringions.However,thepotential30feasibilityofWBAexchangeprocessforCr[VI]removalfromHinkleygroundwaterhasnot31beenevaluatedatbenchorpilot‐scalelevel.BeforeWBAexchangecanbeconsideredasan32alternative,extensivepilottestingoftheWBAexchangeprocesswouldneedtooccurto33evaluatetechnicaleffectivenessandtheimplementabilityfactorsdescribedbelow(Pacific34GasandElectric2011c).35
TheperformanceoftheWBAresinsisstronglyinfluencedbyfactorssuchastheinfluent36waterpH.RecentstudiesindicatetheoptimumpHforCr[VI]removalisapproximately375.5to6.0.TestingisnecessarytoconfirmandoptimizethepHrangeforHinkley38groundwater.39
IntheWBAexchangeprocess,theCr[VI]canberemovedbytwomechanisms:ion40exchangeprocessandreductiontotrivalentchromium(Cr[III]).Themechanismof41
17IonexchangewithSBAisbeingconsideredasoneapproachforprovidingwhole‐housewaterforaffectedresidences.However,theuseforanindividualhouseisonaverysmallscalebycomparisonwiththeefforttocleantheentirecontaminatedplume.Theoperationalconcernsnotedaboveforlarge‐scaleapplicationarenotthesameforasingleresidence‐scaletreatmentsystem.
California Regional Water Quality Control Board, Lahontan Region Project Description
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ICF 00122.11
removalfortheHinkleygroundwaterwillneedtobedeterminedtodesignatreatment1systemthatcanreliablylowertheCr[VI]concentrationstotherequiredtarget2concentrations.3
RecentstudiesonWBAresinsbytheCityofGlendaleindicatedpotentialleachingof4harmfulbyproductssuchasformaldehydeandN‐nitrosodimethylamine(NDMA)or5nitrosamines.TheEPAisplanningtoregulateNDMAindrinkingwaterinthenear6future.7
TheWBAresinscouldalsoaccumulateotherionssuchasradionuclides(uraniumwas8recentlydetectedatoneoftheexistingagriculturalunits),whichwouldrequirespecial9handlinganddisposalofthespentresin.10
RigorouspilottestingthataddressesthetechnicalissuesofWBAresinswouldneedto11beconductedpriortofull‐scaleimplementation.Pendingpilottestresultsthatprovide12datarequiredtofullyevaluatethetechnicaleffectivenessandabilitytoimplement,WBA13exchangemaybefeasiblefortheContingencyPlanduetothesimplicityof14implementationandalsomaybeconsideredatafuturedate.15
MembraneBiofilmReactors(MBfRs):ReduceCr[VI]andnitrateinextractedgroundwater16withamembrane‐basedbiologicaltreatment.Bench‐scaletestresultsindicatethatMBfR17technologycantreatgroundwaterwithCr[VI]concentrationsintherangeof50µg/L,butitis18ineffectivefortreatinggroundwaterwiththehighCr[VI]concentrationspresentintheplume19coreandhasnotbeendemonstratedfortreatmenttotheinterimcleanuplevelsforthisproject.20Thefollowingisasummaryofreasonswhythisalternativewasdismissedfromfurther21considerationatthistime(PacificGasandElectric2011c).22
Asdescribedinthefeasibilitystudy,MBfRisapotentiallyviabletechnologyfortreating23relativelylow(i.e.,≤50ppb)Cr[VI]concentrationsingroundwater.MBfRwasretainedasan24ex‐situtreatmentprocessoptionduringtheinitialtechnologyscreeninginthefeasibility25study,butwasnotselectedasthepreferredprocessoptionforremediationalternativesthat26wouldincludeex‐situtreatment.27
Bench‐scaletestingconductedbyPG&Ein2009showedproof‐of‐conceptoftheprocess’s28technicaleffectivenessforremovingCr[VI]ingroundwater.However,MBfRhasnotyetbeen29fullyimplementedataremediationsitetotreatCr[VI].Asofthelastreviewofthe30technology,MBfRwasbeingpilottestedforremovalofdissolvedperchlorateandnitratein31groundwateronly.Thetechnologyiscurrentlycommerciallyavailableonlyasanitrate32removalprocessinthewastewatertreatmentindustry.Asaresult,thetechnologycannotbe33fullyevaluatedfortechnicaleffectiveness.Ataminimum,thefollowingfactorswouldneed34tobebetterunderstoodbeforeitcouldbeadoptedasaremedialoption.35
Treatmenttodischargelimits:MBfRhasnotbeenproventoremoveCr[VI]tomeet36projectobjectivesofCr[VI]levelsof3.1ppbmaximumand1.2ppbaverageatfullscale.37
Reliability:Thistechnologyhasnotbeenimplementedatascalesimilartothescale38neededinHinkley.Itisnotknownwhetherthisprocesscouldoperatereliablyforthe39extendedperiodoftimeneeded.40
Hydrogenstorageandmanagement:MBfRusesdiffusedhydrogengasastheelectron41donor.Hydrogenwouldhavetobedeliveredandstoredorgeneratedon‐site.AsMBfR42hasneverbeenimplementedatthescalerequiredattheHinkleySite,itiscurrently43
California Regional Water Quality Control Board, Lahontan Region Project Description
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ICF 00122.11
infeasibletofullyevaluatetheimplementabilityconstraintsofeffectivelyandsafely1delivering,storing,orgeneratingtherequiredquantityofhydrogengas.2
Post‐MBfRsecondarytreatmentforinjection:MBfRgeneratesbiomassaspartofthe3process.Thisexcessbiomassisusuallysloughedintothewaterstream.Astreatedwater4wouldbereturnedtogroundwaterviainjectionwells,thesuspendedbiomasswould5likelyhavetoberemovedtopreventbiofoulingininjectionwells.Withoutextensive6pilottesting,biomassgenerationcannotbeestimatedandtheappropriatesecondary7treatmentprocessrequiredtomitigatebiomassgenerationcannotbeevaluated.8
Thetechnologyrequiresextensivepilottestingtoevaluatetechnicaleffectivenessand9implementabilityfactorsdescribedabove.Withoutthisinformation,MBfRisnot10recommendedasapreferredex‐situtreatmentprocess(forAlternative4C‐3orAlternative114C‐5)relativetootherprocesses.12
In‐SituChemicalReductants:Useseveraldifferentchemicalreductantsforin‐situremediation13insteadoforganiccompounds.Thefollowingisasummaryofthereasonschemicalreductants14werenotincludedintheactionalternativesaspartofin‐situremediationapproaches(PacificGas15andElectric2011c).Althoughthesereagentsarenotrecommendedforgeneraluseinthein‐situ16recirculationsystemspresentedinthefeasibilitystudy,theymaybebeneficialinspecific17circumstancesthatariseastheprojectevolves.18
Thisalternativewasconsideredinthebenchtestingphaseoftheproject,priortopilotstudy19implementationandfeasibilitystudypreparation.Calciumpolysulfidewasscreenedout20priortobenchscaletestingduetopotentialproblemswithprecipitationin‐well,uncertainty21ofnitratetreatment,andpotentialincreasedsulfurcontentoftheaquifer.Zero‐valentiron22(ZVI)wasscreenedoutduetocostandin‐situdeliverychallenges.Thebenchtestingresults23indicatethattheorganiccarbonsubstrates(e.g.,emulsifiedvegetableoil,lactate,and24ethanol)andsodiumdithioniteareeffectivereagentsforthetreatmentofCr[VI]in25groundwater.Theorganiccarbonsubstrateswereretainedforpilottestingoversodium26dithionitebasedonsafety,easeofhandling,materialproperties,abilitytodelivertothe27aquifer,permitting,andnitrateremovalconsiderations.28
Oneofthemostchallengingaspectsofin‐situtreatmentisreagentdeliverywithinthe29aquifer,particularlyatthespatialscalesofthein‐situareasforthisproject.Reagentswhich30areveryreactivewillbeconsumedmorequicklyinthesubsurfaceandaremoredifficultto31distributethanlessreactivereagentsthataremoreslowlyconsumed.Chemicalreductants,32includingcalciumpolysulfide,sodiumdithionite,andferrousiron,areveryreactiveinthe33subsurface.Forexample,dithioniteconsumptionisonthetimescaleofminutescomparedto34organiccarbonconsumptionrateswhichareonthetimescaleofdays.Theslower35consumptionratesoftheorganiccarbonsubstratesallowthemtopersistinthesubsurface36andbedistributedtogreaterdistancesfrominjectionlocations.Asecondconsiderationfor37reagentdistributionisthepotentialforcloggingtheaquiferformation,whichlimitsthe38abilitytoinjectanddistributereductants.Sulfide‐andferrousiron‐basedreagentsmay39oxidizetoelementalsulfurandferricironprecipitates,whichcanlimitinjectabilitymuch40morerapidlythanthegradualbuild‐upoffoulingmaterialswithorganiccarbonsubstrates.41Nanoscalezerovalentiron(nZVI)distributionislimitedbytheagglomerationofnZVI42particlesandincorporationintoaquifersolids;thismakesitdifficulttodistributenZVIvia43injectionsforin‐situtreatment.44
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TreatmentEffectiveness.Organiccarbonsubstratesarejustaseffectiveandaggressiveas1chemicalreductantsintreatinghighCr[VI]concentrationsinsourceareas.Forexample,in2theSourceArea,Cr[VI]concentrationswerereducedfromgreaterthan1,000ppbtoless3than0.2ppbatonelocationwithinapproximatelyonemonthofthestartupofin‐situ4injectionsofsodiumlactateinonesourcearea(seediscussioninSection3.1,Water5ResourcesandWaterQuality).Similarly,inapilottestconductedatthePG&ETopock6CompressorStationinNeedles,California,Cr[VI]concentrationsofupto8,000ppbwere7rapidlytreatedtolessthan0.2ppbinapilottestusingethanol.Organiccarbonsubstrates8arealsoaseffectiveaschemicalreductantsfortreatmentofCr[VI]thatmaybepresentin9immobileporespaceinsourceareas.10
GenerationofBy‐products.Forbothorganiccarbonsubstratesandsolublechemical11reductants,reductionofaquifermineralsandassociateddissolutionofiron,manganese,and12arsenicwilloccurwithin‐situtreatmentimplementation.Duetothehighlyreactivenature13ofchemicalreductants,concentrationsofmetalsgeneratedmaybecomparabletoorgreater14withchemicalreductantsthanwiththeuseoforganiccarbonsubstrates,asindicatedinEPA15commentsonthefeasibilitystudy.Forexample,injectionofsodiumdithioniteissometimes16followedbyanextractionphasewhereseveraltimestheinjectedvolumeofreagentis17extractedduetotheproductionofelevatedconcentrationsofby‐productsaswellasreagent18reactionby‐products.Inadditiontodissolutionofmetals,somechemicalreductantsmay19alsoincreaseconcentrationsofotherconstituentsthatcontributetototaldissolvedsolids.20Thereactionproductsofsodiumdithioniteincludesulfite,thiosulfate,andsulfate.Ferrous21ironisoftenprovidedasferroussulfate,therebyincreasingtheconcentrationofsulfate22throughinjections.23
MonitoredNaturalAttenuation:Dilute,diffuse,and/orreduceCr[VI]toCr[III]underthe24geochemicalconditionsthatexistingroundwaterinthenortherndiffuseportionoftheplume.25Resultsofan8‐weekPilotStudyindicatedthatportionsoftheupperaquiferhavesome26reductivecapacity,whichcanreducelowlevelsofCr[VI]ingroundwater,butthemagnitudeof27thisreductivecapacityisnotsufficientforuseasaprimarycomponentofaplume‐wideremedy.28
2.11.10 Other Alternatives Considered in the 2002 Feasibility 29
Study 30
Thefollowinglistdescribestherangeofotheralternativesconsideredinthe2002FeasibilityStudy31thatweredismissedfromfurtherconsideration.Thesealternativeswerescreenedoutbecausethey32donotmeettheprojectgoalandmostoftheobjectivesorhavefeasibilityoreffectivenessconcerns33thatprecludedthemfromfurtherconsideration.Thesealternativesarebrieflydescribedbelow,and34thereasonstheyweredismissedfromfurtherconsiderationareidentified.Alternativesthatwere35consideredinthe2002FeasibilityStudyandpreviouslylistedasconsiderationsinthe201036FeasibilityStudy,suchasmonitorednaturalattenuation,ex‐situtreatment—ionexchange,ex‐situ37treatment—coagulation,andmicrofiltrationwerediscussedaboveunderthediscussionofthe201038FeasibilityStudyandarenotdiscussedfurtherhere.39
Ex‐SituTreatment—ElectrochemicalPrecipitation:Useelectricalcurrentandreactive40electrodestoreduceCr[VI]andprecipitatechromiumasCr[III].Thisalternativewasnot41retainedbecauseofuncertaintyofeffectivenessandveryhighO&Mcostsfromtheproductionof42wasterequiringtransportanddisposal.43
California Regional Water Quality Control Board, Lahontan Region Project Description
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Ex‐SituTreatment—ReverseOsmosis:UsemembranestoremoveCr[VI]fromwater.This1alternativewasnotretainedbecauseofveryhighO&Mcostsfromtheproductionofwaste2requiringtransportanddisposal.3
Ex‐SituTreatment—BiologicalReduction/Precipitation:BiologicallyreduceCr[VI]toless4solubleCr[III]inabioreactor.Althoughthisalternativecanbeeffective,itwasnotretained5becauseitrequirescontinualoperatoroversight,whichmakesitdifficulttoimplement.6
WaterReuse/Disposal—FloodIrrigation:Useoverlandflow(floodirrigation)todistribute7water.Althoughthisalternativeisconsideredtobepotentiallyeffectiveasareuseoption,its8effectivenessdependsonspecificsoilconditionsatproposedlocations(i.e.,infiltrationability),9themethodrequiresadditionaloperationalcontrolstocontainalloverlandflowfromentering10adjacentareas,andthemethodrequiresfencingtoprecludehumanentryintotheirrigatedarea11toavoidexposure.Further,thisapproachwouldresultinmuchhigherevaporationthandrip12irrigationincludedintheprojectalternativesandthereforelacksthegreaterbeneficialuseof13treatedwaterthatresultsfromdripirrigation.14
WaterReuse/Disposal—ReuseatCompressorStation:Reusetreatedwaterattheplantfor15variouspurposes,suchasprocessandcoolingwater.Thisalternativewasnotretainedbecause16itiseffectiveonlyiftheCompressorStationcanuseallthewaterandthusitmaybe17incompatiblewithCompressorStationoperations.Additionally,itisnotfeasiblebecauseof18pipelinelengthsandextensivepermittingandapprovalrequiredforrailway/roadwaycrossings,19wouldnotmeetthefundamentalobjectiveofremediatingthecontaminatedgroundwaterwithin20ameaningfulperiodoftime.21
WaterReuse/Disposal—Reinjection:Injecttreatedgroundwaterintosubsurfaceusingwells,22infiltrationgalleries,orrechargebasins.Thisalternativeiseffectiveifasubsurfaceaquifercan23accommodatewaterquantitiesandthusitisretainedonlyasabackuptodripirrigationsystems24includedinagriculturaltreatmentapproachesincludedinthefiveprojectalternatives.25
Barstow
Hinkley
247
5858
15
15
40
Project Location
K E R N
L O S A N G E L E S
O R A N G E
R I V E R S I D E
S A NB E R N A R D I N O
1
1
111
138
138
138
138
14
14
14
142
178
178
18
18
18
1818
2
2
215
243
247
247
30
330
371
38
38
39
58
58
58
60
62
74
74
74
74
79
79
91
91
395
395
10
10
15
15
15
40
5
5
East Los Angeles
Fullerton
Garden Grove
Glendale
Huntington Beach
Pasadena
Riverside
San Bernardino
Torrance
Alhambra Baldwin Park
Burbank
Carson
CerritosCompton
Costa Mesa
Downey
Fountain Valley
Hawthorne
Inglewood
Irvine
Lakewood
Mission Viejo
Montebello
Monterey Park
Newport Beach
Norwalk
Ontario
Orange
Pico Rivera
PomonaRancho Cucamonga
Redondo Beach
Santa Monica
South Gate
West Covina
Westminster
Whittier
East Los Angeles
Fullerton
Garden Grove
Glendale
Huntington Beach
Pasadena
Riverside
San Bernardino
Torrance
Alhambra Baldwin Park
Burbank
Carson
CerritosCompton
Costa Mesa
Downey
Fountain Valley
Hawthorne
Inglewood
Irvine
Lakewood
Mission Viejo
Montebello
Monterey Park
Newport Beach
Norwalk
Ontario
Orange
Pico Rivera
PomonaRancho Cucamonga
Redondo Beach
Santa Monica
South Gate
West Covina
Westminster
Whittier
Anaheim
Long Beach
Los Angeles
Santa Ana
Anaheim
Long Beach
Los Angeles
Santa Ana
Barstow
Project Location
1
1
111
138
138
138
138
14
14
14
142
178
178
18
18
18
1818
2
2
215
243
247
247
30
330
371
38
38
39
58
58
58
60
62
74
74
74
74
79
79
91
91
395
395
10
10
15
15
15
40
5
5
East Los Angeles
Fullerton
Garden Grove
Glendale
Huntington Beach
Pasadena
Riverside
San Bernardino
Torrance
Alhambra Baldwin Park
Burbank
Carson
CerritosCompton
Costa Mesa
Downey
Fountain Valley
Hawthorne
Inglewood
Irvine
Lakewood
Mission Viejo
Montebello
Monterey Park
Newport Beach
Norwalk
Ontario
Orange
Pico Rivera
PomonaRancho Cucamonga
Redondo Beach
Santa Monica
South Gate
West Covina
Westminster
Whittier
East Los Angeles
Fullerton
Garden Grove
Glendale
Huntington Beach
Pasadena
Riverside
San Bernardino
Torrance
Alhambra Baldwin Park
Burbank
Carson
CerritosCompton
Costa Mesa
Downey
Fountain Valley
Hawthorne
Inglewood
Irvine
Lakewood
Mission Viejo
Montebello
Monterey Park
Newport Beach
Norwalk
Ontario
Orange
Pico Rivera
PomonaRancho Cucamonga
Redondo Beach
Santa Monica
South Gate
West Covina
Westminster
Whittier
Anaheim
Long Beach
Los Angeles
Santa Ana
Anaheim
Long Beach
Los Angeles
Santa Ana
Barstow
Project Location
K E R N
L O S A N G E L E S
O R A N G E
R I V E R S I D E
S A NB E R N A R D I N O
Miles
2 41 30
Figure 2-1Project Location and Vicinity
Gra
ph
ics
… 0
0122
.11
(07-
2012
)
W O R K I N G D R A F T
MountGeneral
Sonoma
arreS
Acacia
Plymouth
weiV ni at nuo
M
Manacor
Sunset
arreiS
Thompson
Acacia
Burnt Tree
Salinas
tesrem
muS
HolsteadFossil B
ed
Coo
n
Can
yon
Mountain General
Alcudia
yelkniH
Mountain General
Coon Canyon
weivri aF
Highcrest
Ser
ra
Riverview
weiV ni at nuoM
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
onyel kniH
State Highway 58
Santa Fe Railway
MO
JA
VE
R I V E R
K:\P
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0089
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_Pro
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Figure 2-2aProject Area±0 0.5 10.25
Miles
HinkleyElementary
School
PG&E HinkleyCompressorStation
DVD LTU
NO
RT
H A
RE
A
Sources: Based on information from PG&E 2011c.
CEN
TRA
L A
REA
SO
UT
H A
RE
ALegend
Project Study Area
IRZ Area
OU1
OU2
OU3
Roads
Santa Fe Railway
!
!!
!
!!
!!
!!
!!
!!
!!
!!
!!
!!
!!
!!
!
! ! !
!!
!!
!
!!
!
!
!
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!!
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!!
!!
!!
!!
MountGeneral
Sonoma
arreS
Acacia
Plymouth
weiV ni at nuo
M
Manacor
Sunset
arreiS
Thompson
Acacia
Burnt Tree
Salinas
tesrem
muS
HolsteadFossil B
ed
Coo
n
Can
yon
Mountain General
Alcudia
yelkniH
Mountain General
Coon Canyon
weivri aF
Highcrest
Ser
ra
Riverview
weiV ni at nuoM
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
onyel kniH
State Highway 58
Santa Fe Railway
MO
JA
VE
R I V E R
K:\P
roje
cts_
3\P
GE\
0089
8_10
_Hin
kley
\map
doc\
Figu
res\
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\Fig
_2-2
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xd 8
/6/2
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PG
Figure 2-2bExpansion of 3.1/4.0 ppb MaximumBackground Plume Area Contours
±0 0.5 10.25
Miles
HinkleyElementary
School
PG&E HinkleyCompressorStation
NO
RT
H A
RE
A
Sources: Based on information from PG&E quarterly monitoring reports available at www.geotracker.swrcb.ca.gov/.
CEN
TRA
L A
REA
SO
UT
H A
RE
AApproximated Contours by Year
4th Quarter 2011, 3.1 ppb
!
! !
!!
! 4th Quarter 2011, 3.1 ppb (approximate)
3rd Quarter 2011, 3.1 ppb
1st Quarter 2011, 3.1 ppb
1st Quarter 2010, 4.0 ppb
3rd Quarter 2008, 4.0 ppb
Project Study Area
Roads
Santa Fe Railway
MountGeneral
Sonoma
arreS
Acacia
Plymouth
weiV ni at nuo
M
Manacor
Sunset
arreiS
Thompson
Acacia
Burnt Tree
Salinas
tesrem
muS
HolsteadFossil B
ed
Coo
n
Can
yon
Mountain General
Alcudia
yelkniH
Mountain General
Coon Canyon
weivri aF
Highcrest
Ser
ra
Riverview
weiV ni at nuoM
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
onyel kniH
State Highway 58
Santa Fe Railway
MO
JA
VE
R I V E R
K:\P
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cts_
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0089
8_10
_Hin
kley
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\Fig
_2-2
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Figure 2-2cExpansion of 10 ppb
Plume Area Contours±0 0.5 10.25
Miles
HinkleyElementary
School
PG&E HinkleyCompressorStation
NO
RT
H A
RE
A
Sources: Based on information from PG&E quarterly monitoring reports available at www.geotracker.swrcb.ca.gov/.
CEN
TRA
L A
REA
SO
UT
H A
RE
AApproximated Contours by Year
4th Quarter 2011
3rd Quarter 2011
1st Quarter 2011
1st Quarter 2010
3rd Quarter 2008
Project Study Area
Roads
Santa Fe Railway
MountGeneral
Sonoma
arreS
Acacia
Plymouth
weiV ni at nuo
M
Manacor
Sunset
arreiS
Thompson
Acacia
Burnt Tree
Salinas
tesrem
muS
HolsteadFossil B
ed
Coo
n
Can
yon
Mountain General
Alcudia
yelkniH
Mountain General
Coon Canyon
weivri aF
Highcrest
Ser
ra
Riverview
weiV ni at nuoM
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
onyel kniH
State Highway 58
Santa Fe Railway
MO
JA
VE
R I V E R
K:\P
roje
cts_
3\P
GE\
0089
8_10
_Hin
kley
\map
doc\
Figu
res\
Plu
mes
\Fig
_2-2
d_P
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mxd
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Figure 2-2dExpansion of 50 ppb
Plume Area Contours±0 0.5 10.25
Miles
HinkleyElementary
School
PG&E HinkleyCompressorStation
NO
RT
H A
RE
A
Sources: Based on information from PG&E quarterly monitoring reports available at www.geotracker.swrcb.ca.gov/.
CEN
TRA
L A
REA
SO
UT
H A
RE
AApproximated Contours by Year
4th Quarter 2011
3rd Quarter 2011
1st Quarter 2011
1st Quarter 2010
3rd Quarter 2008
Project Study Area
Roads
Santa Fe Railway
!C
!C
!C
!C
!C
!.!.!.!.!.!.!C!.!.!.!.!C
!C
!C!C
!C!C
!C
!C
!C!C
!C !C
!C
!C!C
!C
!C
!C
!C!C
!C
!C
!C
!C
"/
"/
"/
"/
"/!C !C !C
!C
!.!.!.!.
!.!.!.!.!.!.!.!.!.!.
!.!.!.!.!.!.
!.!. !.!.!.
!C !C !C !C
!.!.!.!.!.!.
!.!.!.!.!.!.
!.!.!.!.!.!.!.!.!.!C!.!C !C!C!.!.!C!C
!C
!C
!. !.!. !.!.!.!.!.
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V E R
K:\
Pro
ject
s_3
\PG
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0_
Hin
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y\m
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Figure 2-2eExisting Remedial Activities±0 0.5 10.25
Miles
HinkleyElementary
School
PG&E HinkleyCompressorStationPG&E-14
NORT
H AR
EA
Sources: Haley-Aldrich 2011. CH2MHill, 2011.
CENT
RAL A
REA
SOUT
H AR
EA
Ranch
Gorman N.
Gorman S.
Cottrell
NOTE: All well locations are approximated.
FW-01FW-02
!. Existing Injection Wells
!C Existing Extraction Wells
"/ Northwest Freshwater Injection Wells
!C Existing Freshwater Extraction Wells
LegendProject Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
!!!!
!
!!!! ! !
!! !
!!
!!!
!!!
! ! ! ! !! ! !
!! ! !! !
!
!
!
!C
!C !C
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V E R
K:\
Pro
ject
s_3
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Fig
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ject
.mxd
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Figure 2-3No Project Alternative Conceptual Layout
(Initial Buildout to Year 20)±0 0.5 10.25
Miles
HinkleyElementary
School
PG&E HinkleyCompressorStation
PG&E-14
NORT
H AR
EA
Sources: Haley-Aldrich 2011. CH2MHill, 2011.
CENT
RAL A
REA
SOUT
H AR
EA
Ranch
Gorman N.
Gorman S.
Cottrell
NOTE: New infrastructure layouts are slightlyexaggerated and locations are approximatedfor graphical display.
FW-01FW-02
LegendProject Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
!C Existing Freshwater Extraction Wells
! ! New Infrastructure
!
!
!!
!
! !!
!
!
!
!
!
!
!
!
!!!!
!
!!!! ! !
!! !
!!
!!!
!!!
! ! ! ! !! ! !
!! ! !! !
!
!
!C
!C!C
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V
E R
Note 1: New infrastructure layouts are slightlyexaggerated and locations are approximatedfor graphical display.Note 2: Number of new wells shown on thisfigure are according to FS/Addenda estimates.It is expected additional infrastructure will benecessary to address the expanded plume.See discussions in text.
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
±0 0.5 10.25
Miles
!C Existing Freshwater Extraction Wells
New Infrastructure (wells and pipelines)! !
K:\
Pro
ject
s_3
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Fig
_2
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.mxd
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Figure 2-4Alternative 4B Conceptual Layout
(Initial Buildout to Year 20)
HinkleyElementary
School
PG&E HinkleyCompressorStation
NORT
H AR
EACE
NTRA
L ARE
ASO
UTH
AREA
Ranch
Gorman N.Gorman S.
Cottrell
FW-01FW-02
Legend
Project Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
New Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
Yang
PG&E-14
!
! !
! ! !
! ! ! ! ! !
!
!
!!
!
!!
!
!
!
!
!
!
!!
!
!!!!
!
!!!! ! !
!! !
!!
!!!
!!!
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!! ! !! !
!
!
!C
!C!C
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V E R
Note 1: New infrastructure layouts are slightlyexaggerated and locations are approximatedfor graphical display.Note 2: Number of new wells shown on thisfigure are according to FS/Addenda estimates.It is expected additional infrastructure will benecessary to address the expanded plume.See discussions in text.
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
±0 0.5 10.25
Miles
!C Existing Freshwater Extraction Wells
New Infrastructure (wells and pipelines)! !
K:\
Pro
ject
s_3
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Figure 2-5Alternative 4C-2 Conceptual Layout
(Initial Buildout to Year 20)
HinkleyElementary
School
PG&E HinkleyCompressorStationPG&E-14
NORT
H AR
EACE
NTRA
L ARE
ASO
UTH
AREA
Ranch
Gorman N.Gorman S.
Cottrell
FW-01FW-02
Legend
Project Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
New Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
Bell N.
Yang
West
Bell S.
South
! !!!! !! !!
!!! !!
!!!! ! !
!! !
!!
!!!
!!!!
! !! ! ! ! !! ! !
!!! ! ! ! !! !
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!
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!!
!
!!!
!!
!!
!
!
!
!
! ! !
!
!
!
!C
!C!C
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V
E R
Note 1: New infrastructure layouts are slightlyexaggerated and locations are approximatedfor graphical display.Note 2: Number of new wells shown on thisfigure are according to FS/Addenda estimates.It is expected additional infrastructure will benecessary to address the expanded plume.See discussions in text.
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
±0 0.5 10.25
Miles
!C Existing Freshwater Extraction Wells
New Infrastructure (wells and pipelines)! !
K:\
Pro
ject
s_3
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Fig
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P
G
Figure 2-6Alternative 4C-3 Conceptual Layout
(Initial Buildout to Year 20)
HinkleyElementary
School
PG&E HinkleyCompressorStation
PG&E-14
NORT
H AR
EACE
NTRA
L ARE
ASO
UTH
AREA
Ranch
Gorman N.Gorman S.
Cottrell
FW-01FW-02
Legend
Project Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
New Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
Bell N.
Yang
West
Bell S.
South
Above GroundTreatment Plant
Above GroundTreatment Plant
!!!!
!
!!!! ! !
!! !
!!
!!!
!!!!
! !! ! ! ! !! ! !
!!! ! ! ! !! !
! ! ! ! ! !
!
! !
!!
!!
!! !!
!!
!
!
!!
!
!
!C
!C!C
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V
E R
Note 1: New infrastructure layouts are slightlyexaggerated and locations are approximatedfor graphical display.Note 2: Number of new wells shown on thisfigure are according to FS/Addenda estimates.It is expected additional infrastructure will benecessary to address the expanded plume.See discussions in text.
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
±0 0.5 10.25
Miles
K:\
Pro
ject
s_3
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E\0
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P
G
Figure 2-7Alternative 4C-4 Conceptual Layout
(Initial Buildout to Year 20)
HinkleyElementary
School
PG&E HinkleyCompressorStation
PG&E-14
NORT
H AR
EACE
NTRA
L ARE
ASO
UTH
AREA
Ranch
Gorman N.Gorman S.
Cottrell
FW-01FW-02
Bell N.
Yang
West
Bell S.
South
Legend
Project Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
New Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
!C Existing Freshwater Extraction Wells
New Infrastructure (wells and pipelines)! !
!
! !
! ! !
!
!
!!
!!
! !!
!!
!
!
!
!
! ! ! ! ! !
!!
!!!!
!!
!
!!
!
!
! !!
!
!! !
!
!
!!!
! ! ! ! !! ! !
!! ! !! !
!
!C
!C!C
MountGeneral
Sonoma
Ser
ra
Acacia
Plymouth
Mo
unta
in V
iew
Manacor
Sunset
Sie
rra
Thompson
Acacia
Burnt Tree
Salinas
Sum
me
rse
t
Holstead
Fossil Bed
Coo
n
Can
yon
Mountain General
Alcudia
Hin
kley
Mountain General
Coon Canyon
Fai
rvie
w
Highcrest
Ser
ra
Riverview
Mo
unta
in V
iew
Community Blvd
Dix
ie
Santa Fe Railway
State Highway 58
Livi
ngst
on
Hin
kley
State Highway 58
Santa Fe Railway
M O J A V E
R I V
E R
K:\
Pro
ject
s_3
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Figure 2-8Alternative 4C-5 Conceptual Layout
(Initial Buildout to Year 20)
HinkleyElementary
School
PG&E HinkleyCompressorStation
PG&E-14
NORT
H AR
EACE
NTRA
L ARE
ASO
UTH
AREA
Ranch
Gorman N.Gorman S.
Cottrell
FW-01FW-02
Legend
Project Study Area
IRZ Area
OU1
OU2
OU3
Desert View Dairy LTU
Existing Agricultural Units
New Agricultural Units
Approximate limit of saturated alluvial aquifer
Bedrock exposed at ground surface
Roads
Santa Fe Railway
Bell N.
Yang
West
Bell S.
South
Above GroundTreatment Plant
Note 1: New infrastructure layouts are slightlyexaggerated and locations are approximatedfor graphical display.Note 2: Number of new wells shown on thisfigure are according to FS/Addenda estimates.It is expected additional infrastructure will benecessary to address the expanded plume.See discussions in text.
!C Existing Freshwater Extraction Wells
New Infrastructure (wells and pipelines)! !
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
PotentialFuture
RemedialActivity Area
±0 0.5 10.25
Miles