HomeMy WebLinkAboutAPA1655FERC/DEIS-0038/'1FEDERALENERGYREGCOMMISSIONOFFICEOFELECTRICPOWERREGULATIONYIO)IDRAFTENVIRONMENTALIMPACTSTATEMENTSUSITNAHYDROELECTRICPROJECTFERCNO.7114-ALASKAVolume3.AppendixE.AppendixF.AppendixG.GeologyandSoilsLandUseandOwnershipClimate,AirQuality,NoiseAlaskaResourcesLibrary&InformationServicesAulchorage,AlaskaAlaskaPowerAuthority333West4thAvenueSuite31Anchorage,Alaska99501App1icant:AdditionalcopiesoftheDraft-EISmaybeorderedfrom:DivisionofPublicInformationFederalEnergyRegulatoryCommission825NorthCapitolSt.,NE.Washington,D.C.20426May1984
iiiTABLEOFCONTENTSAPPENDIXE.GEOLOGYANDSOILSE.lAFFECTEDENVIRONMENT.E.l.lProposedProject.E.l.l.lUpperandMiddleSusitnaRiverBasinE.l.l.l.lTopography.E.l.l.1.2Geology.E.l.l.1.3SoilsandPermafrostE.1.1.1.4Minera1Resources. .E.1.1.1.5Seismicity.....E.l.1.2LowerSusitnaRiverBasinE.l.l.2.1Topography.E.l.l.2.2Geology.E.l.l.2.3SoilsandPermafrostE.l.l.2.4MineralResources.E.l.l.2.5Seismicity. ....E.l.1.3PowerTransmissionLineCorridorsE.l.l.3.1Topography.....E.l.1.3.2Geology.. . . ....E.l.l.3.3SoilsandPermafrost..E.1.1.3.4Minera1Resources. . . .E.l.1.3.5Seismicity.E.l.2SusitnaDevelopmentAlternatives..E.l.2.1AlternativeDamLocationsandDesignsE.1.2.1.1WatanaI-DevilCanyon.E.l.2.1.2WatanaI-ModifiedHighDevilCanyonE.l.2.1.3WatanaI-ReregulatingDamE.l.2.2AlternativeAccessRoutesE.l.2:2.1Topography.E.1.2.2.2Geology.L1.2.2.3Soils . . . . . . . .E.l.2.2.4MineralResources..E.1.2.2.5SeismicGeology..,...E.l.2.3AlternativePowerTransmissionRoutesE.l.2.3.1Topography.E.l.2.3.2Geology.E.1.2.3.3Soils.L1.2.3.4Minera1Resources. .E.1.2.3.5SeismicGeology....E.l.2.4AlternativeBorrowSites..E.l.3Non-SusitnaGenerationAlternatives...E.l.3.1Natural-Gas-FiredGenerationScenarioE.l.3.1.1Anchorage-KenaiPeninsulaRegionE.l.3.1.2ChuitnaandLowerBelugaRiversE.l.3.2Coal-FiredGenerationScenario.E.1.3.2.1\olillow.E.l.3.2.2Nenana.E.l.3.3CombinedHydro-ThermalGenerationScenarioE.l.3.3.1JohnsonE.l.3.3.2Keetna.E.l.3.3.3Snow.E.l.3.3.4Browne.E.l.3.3.5LakeChakachamna..E.l.3.3.6BelugaRiver,ChuitnaRiver,NenanaandAnchorageE.2ENVIRONMENTALIMPACT.E.2.1ProposedProject.E.2.1.1WatanaDeveloDment.E.2.1.1.1Construction.E.2.1. 1.2Operation.. . . . .E.2.1.2DevilCanyonDevelopmentE.2.1.2.1Construction.E.2.1.2.2Operation.E.2.1.3AccessRoutes.E.2.1.3.1DenaliHigh"faytoWatanaE-3E-3E-3E-3E-5E-llE-llE-17E-21E-21E-22E-22E-23E-23E-24E-24E-24E-26E-27E-27E-28E-28E-28E-28E-28E-28E-28E-29E-29E-29E-29E-29E-29E-30E-30E-30E-30E-32E-32E-32E-32E-33E-33E-33E-34E-34E-34E-35E-36E-36E-37E-38E-38E-38E-38E-38E-43E-45E-45E-46E-47E-47
ivTABLEOFCONTENTS(Cont'd)E.2.1.3.2WatanatoDevilCanyon..E.2.1.3.3RailAccesstoDevilCanyon..E.2.1.4PowerTransmissionFacilities...E.2.1.4.1Dams-to-GoldCreekSegment..E.2.1.4.2GoldCreek-to-FairbanksSegmentE.2.1.4.3GoldCreek-to-AnchorageSegmentE.2.2SusitnaDevelopmentAlternatives...E.2.2.1AlternativeDamLocationsandDesignsE.2.2.1.1WatanaI-DevilCanyon.E.2.2.1.2WatanaI-ModifiedHighDevilCanyonE.2.2.1.3WatanaI-ReregulatingDam.E.2. 2.2AlternativeAccessRoutes.E.2.2.2.1NorthernAccessRoute.E.2.2.2.2SouthernAccessRoute.E.2.2.3AlternativePowerTransmissionRoutesE.2.2.3.1Willow-to-AnchorageSegmentE.2.2.3.2Dams-to-GoldCreekSegment..E.2.2.3.3Healy-to-FairbanksSegment.E.2.2.4AlternativeBorrowSites.E.2.3Non-SusitnaGenerationAlternatives.E.2.3.1Natural-Gas-FiredGenerationScenarioE.2.3.2Coal-FiredGenerationScenario.E.2.3.3CombinedHydro-ThermalGenerationScenarioE.2.3.3.1JohnsonE.2.3.3.2Keetna..E.2.3.3.3Snow.E.2.3.3.4Browne.E.2.3.3.5Chakachamna.E.2.3.3.6ThermalUnits..E.2.4ComparisonofAlternatives....E.2.4.1SusitnaDevelopmentAlternatives...E.2.4.1.1AlternativeDamLocationsandDesignsE.2.4.1.2AlternativeAccessRoutes.E.2.4.1.3AlternativePowerTransmissionRoutesE.2.4.2Non-SusitnaGenerationAlternatives...E.2.4.2.1Natural-Gas-FiredGenerationScenarioE.2.4.2.2Coal-FiredGenerationScenario.E.2.4.2.3CombinedHydro-ThermalGenerationScenarioE.3MITIGATIONREFERENCES. . . . . . . . . . . . . . . . . . . . . . . . .APPENDIXF.LANDUSEF.lAFFECTEDENVIRONMENT.F.l.lIntroduction.F.l.2ProposedProject.F.l.2.lUpperandMiddleSusitnaRiverBasinF.l.2.1.lExistingandFutureUsesF.l.2.1.2OwnershipStatusandManagementF.l.2.1.3LandValues.F.l.2.2PowerTransmissionLineCorridor.F.l.2.2.1ExistingandFutureUses...F.l.2.2.2OwnershipStatusandManagementF.l.2.2.3LandValues.F.l.3SusitnaDevelopmentAlternatives.F.l.3.lAlternativeDamLocationsandDesignsF.1.3.2AlternativeAccessRoutes.F.l.3.3AlternativePowerTransmissionRoutesF.1.3.4AlternativeBorrowSites.F.l.4Non-SusitnaGenerationAlternatives.F.l.4.1Natural-Gas-FiredGenerationScenarioF.l.4.l.lBelugaandChuitnaRivers.F.l.4.l.2KenaiPeninsula.F.l.4.l.3Anchorage.F.l.4.2Coal-FiredGenerationScenarioF.1.4.2.lNenana.F.1.4.2.2Willow.F.1.4.2.3CookInlet.F.l.4.3CombinedHydro-ThermalGenerationScenarioF.l.4.3.lChakachamnaLake.E-48E-48E-49E-49E-50E-51E-52E-52E-52E-52E-52E-52E-52E-52E-53E-53E-53E-53E-54E-54E-54E-54E-55E-55E-55E-55E-56E-56E-56E-56E-56E-56E-57E-57E-57E-57E-58E-58'E-59E-59F-3F-3F-3F-3F-3F-6F-19F-19F-19F-22F-25F-25F-25F-28F-28F-28F-28F-28F-28F-28F-28F-31F-31F-31F-31F-31F-31
vTABLEOFCONTENTS(Cont'd)F.l.4.3.2BrowneF.l.4.3.3KeetnaF.l.4.3.4Snow.F.l.4.3.5Johnson".....F.l.4.3.6Nenana,ChuitnaRiver,andAnchorageF.2ENVIRONMENTALIMPACTS.F.2.1ProposedProject.F.2.1.1WatanaDevelopmentF.2.1.1.1Construction.F.2.1.1.2Operation...F.2.1.2DevilCanyonDevelopmentF.2.1.2.1Construction.F.2.1.2.2Operation.F.2.1.3AccessRoutes.. . ......F.2.1.3.1DenaliHighway-to-WatanaRouteF.2.1.3.2Watana-to-DevilCanyonRouteF.2.1.3.3RailAccess-to-DevilCanyon..F.2.1.4PowerTransmissionFacilities...F.2.1.4.1Dams-to-GoldCreekSegment..F.2.1.4.2GoldCreek-to-FairbanksSegmentF.2.1.4.3GoldCreek-to-AnchorageSegmentF.2.2SusitnaDevelopmentAlternatives...F.2.2.1AlternativeDamLocationsandDesignsF.2.2.2AlternativeAccessRoutes.F.2.2.3AlternativePowerTransmissionRoutesF.2.2.4AlternativeBorrowSites.F.2.3Non-SusitnaGenerationAlternatives.F.2.3.1Natural-Gas-FiredGenerationScenarioF.2.3.2Coal-FiredGenerationScenario...F.2.3.3CombinedHydro-ThermalGenerationScenarioF.2.4ComparisonofAlternatives.....F.2.4.1SusitnaDevelopmentAlternatives.F.2.4.2PowerGenerationScenarios.F.3MITIGATION. . . . . . . . . . . . . . . . . . .F.3.1MitigativeMeasuresProposedbythe'ApplicantF.3.1.1DamsandImpoundmentAreas..F.3.1.2ConstructionCampsandVillages.F.3.1.3RecreationalUse.F.3.1.4AccessRouteCorridors. . . . ..'.. .'F.3.1.5TransmissionLineCorridors.F.3.2AdditionalMitigativeMeasuresRecommendedby,theStaffREFERENCES. . . . . . . . . . . . . . . . . . . . .APPENDIXG.CLIMATE~AIRQUALITY,NOISEG.lAFFECTEDENVIRONMENTG.l.lProposedProject.G.l.1.1Climate.G.1.1.2AirQuality.G.1.1.3Noise.. . . . . . .G.l.2SusitnaDevelopmentAlternatives.G.l.3Natural-Gas-FiredGenerationScenarioG.l.3.1Climate.G.l.3.2AirQuality,Noise.G.l.4Coal-FiredGenerationScenarioG.l.4.1Climate.G.l.4.2AirQuality.G.1.4.3Noise.G.l.5CombinedHydro-ThermalGenerationScenarioG.2ENVIRONMENTALIMPACTS,..G.2.1ProposedProject.G.2.1.1Climate.G.2.1.2AirQuality.G.2.1.2.1WatanaDamSite.G.2.1.2.2DevilCanyonDamSiteG.2.1.3Noise.G.2.2SusitnaDevelopmentAlternativesG.2.3Natural-Gas-FiredGenerationScenarioG.2.4Coal-FiredGenerationScenario..G.2.5CombinedHydro-ThermalGenerationScenarioREFERENCES. . . .':,. . , . . . . . . . . . . . . .F-31F-32F-32F-32F-32F-32F-32F-32F-32F-33F-36F-36F-38F-38F-38F-39F-39F-39F-39F-40F-40F-40F-40F-41F-41F-41F-41F-41F-41F-45F-45F-45F-45F-48F-48F-48F-48F-48F-48F-49F-49F-49G-3G-3G-3G-3G-5G-5G-5G-5G-6G-I0G-I0G-12G-12G-12G-12G-12G-12G-12G-12G-16G-16G-17G-17G-19G-27G-29
viLISTOFFIGURESFigureCOVERPHOTO:Artist'sRenditionoftheProposedWatanaDamandReservoirAPPENDIXE.GEOLOGYANDSOILSE-lAlternativeAccessPlan18. . . . . . .E-4E-2WatanaBorrow/QuarrySites. . . . . . .E-6E-3DevilCanyonBorrow/QuarrySites. . . .E-7E-4Regiona1GeologyUnderlyingSiteFeatures. . .E-8E-5SignificantSeismicFaultsandFeatureswithintheSusitnaBasinE-18E-6SignificantFeaturesneartheWatanaandDevilCanyonDamSites.E-20APPENDIXF.LANDUSEF-lLandUsePatternswithintheUpperandMiddleSusitnaRiverBasin.. . . . ...F-4F-2LocationofExistingStructureswithintheUpperandMiddleSusitnaBasin....F-7F-3LandOwnershipandManagementPatternswithintheUpperandMiddleSusitnaRiverBasinArea. . . . . . . . . . . . . . . . . . . . . . . . . . .F-16F-4LocationsofAlaskaDepartmentofNaturalResourcesLandDisposalSitesforRepresentativeLandValueData. . . . . . . . . . . . . . . . . .F-27F-5ProposedWatanaConstructionCamp.. . . . . . . . . . . . . . . .F-34F-6ProposedWatanaConstructionVillageandPermanentTownFacilitiesF-35F-7ProposedDevilCanyonConstructionCamp..F-37F-8ProposedDevilCanyonConstructionVillage. . . . . . . . . . . .F-37APPENDIXG.CLIMATE,AIRQUALITY,NOISEG-lClimaticZonesofAlaska. . . . . . . . . . . . . . . . .G-4G-2LocationsofWeatherMonitoringStationsinCookInletAreaG-7G-3WindRoseforAnchorage,Tyonek,andKenaiAreas. . . .G-8G-4LandUseintheKenaiArea. . . . . . . . . . . . . . .G-gG-5SeasonalTSPMeasurementsatAnchorageandKenai. . . . . .G-nG-6LocationofMajorSourcesofFugitiveDustReleaseduringConstructionofWatanaDam. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-14G-7RelativeLocationofNenanaandWillowwithRespecttotheClassIAreaatDenaliNationalPark. . . . . . . . . . . . . . . . . . . . . . . . . . .G-21G-8LocationofPlumeImpactionwiththeElevatedTerrainnearNenana.. . . .G-24G-gTwoTypesofPlumeVisibilityImpairmentConsideredintheLevel-lVisibilityScreeningAnalysis. . . . . . . . . . . . . . . . . . . . . . . . . . .G-26G-I0GeometryofPlume,Observer,andLineofSightUsedinLevel-lVisibilityScreeningAnalysis. . . . . . . . . . . . . . . . . . . . . . . . . . .G-26
viiLISTOFTABLESTablePageAPPENDIXE.GEOLOGYANDSOILSE-lSoilAssociationswithintheSusitnaProjectStudyArea-GeneralDescription,OffroadTrafficabilityLimitations,CommonCropSuitability,RoadLocationLimitations,andLowBuildingLimitations.. . . . . . . . . . . . . . . . . .E-12E-2DefinitionsforOffroadTrafficabilityLimitationsandCommonCropSuitabilityofSoilAssociations. . . . . . . . . . . . . . . . . . . . . . .E-1SE-3SummaryofBoundaryFaultsandSignificantFeatures.. . . . . . .E-19E-4SummaryofEarthquakeSourcesConsideredinGround-MotionStudies.E-2lE-SSoilsAlongtheProposedandAlternativeTransmissionLineSegmentsE-3lAPPENDIXF.LANDUSEF-lDescriptionandLocationofExistingStructureswithintheUpperandMiddleSusitnaRiverBasin.. . . . . . . . . . . . . . . . . . . . . . . .F-SF-2LandOwnership/StatusClassificationTerminology. . . . . . . . . . . . .F-17F-3SummaryofLandStatusandOwnershipAcreageintheUpperandMiddleSusitnaRiverBasinStudyArea. . . . . . . . . . . . . . . . . . . . . . .F-1SF-4ExistingandPotentialAgriculturalLandsandLandSalesLocatedAlongtheProposedTransmissionLineCorridor.. . . . . . . . . . . . . . . . . . .F-2lF-SAirports,LandingStrips,andFloatPlaneLandingSitesAlongtheProposedTransmissionLineCorridor. . . . . . . . . . . . . . . . . . . . .F-23F-6SampleLandValueDatafortheAlaskaDepartmentofNaturalResourcesLandDisposa1Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . .F-26F-7LandUsesAlongAlternativePowerTransmissionRoutes.. . . . . . . . . .F-29F-SLandRequirementsandPotentialConflictiveUsesAlongtheAlternativePowerTransmissionRoutes. . . . . . . . . . . . . . . . . . . . . . . . . . . .F-42F-9LandRequirementsandMajorRegionalLandUseAffectedbytheNatural-Gas-FiredGenerationScenario.. . . . . . . . . . . . . . . . . . . . . . .F-43F-10LandRequireme~tsandMajorRegionalLandUseAffectedbytheCoal-FiredGenerationScenario.. . . . . . . . . . . . . . . . . . . . . . . . . .F-44F-llLandRequirementsandMajorRegionalLandUseAffectedbytheCombinedHydro-Therma1GenerationScenari0 .. . . . . . .. . . .F-46F-12ComparisonofLandRequirementsandMajorRegionalLandUsesAffectedbythePowerGenerationScenarios. . . . . . . . ...F-47APPENDIXG.CLIMATE,AIRQUALITY,NOISEG-lSummaryofAirQualityMaximaatKenaiPeninsulaMonitoringSitefortheTesoroRefinery. . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-10G-2SummaryofN02MeasurementsinAnchorage. . . . . . . . . . . . . . . .G-llG-3ProjectedMajorSourcesofFugitiveDustEmissionsandEstimatedReleaseRatesforSusitnaConstructionActivities.. . . . . . . . . . . . . . . . .G-13G-4EstimatedEmissionRatesandGround-LevelPollutantConcentrationsfrom12TemporaryDieselGeneratorsDuringPlantConstruction.. . . . . . . .G-1SG-SCharacteristicsof200-MWeCombined-CycleGasPlantUsedinAirQualityMode1ing. . . . . . . . . . . . . . . . . . . . . . ........G-1SG-6AlaskaAmbientAirQualityStandards. . . . . . . . . . . . . . . . .G-1SG-7SummaryofPSDIncrements.. . . . . . . . . . . . . . . . . . . . . .G-19G-SStackCharacteristicsandEmissionsforEach200-MWeStandardCoal-FiredUnitG-22G-9MaximumGround-LevelConcentrationsofPollutantsfromOpel'ationof200-MWeCoal-FiredUnitsatNenanaandWillow.. . . . . . . . . . . . . . . . . . .G-23G-10ComparisonofSimplifiedVALLEYModelPredictionsforMaximum24-hourAveragesofS02andTSPatElevatedTerrainnearNenanafor200to1000MWeofCoal-FiredGeneration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .G-24G-llComparisonofPredictedMaximum24-hrConcentrationsofS02andTSPtoPSDClassIIncrementsatDenaliNationalParkfromNenanaandWillowCoal-FiredUnits.. . . . . . . . . . . . . . . . . . . . . . . . . . . .G-25G-12ResultsofLevel-lScreeningAnalysisBasedonNenanaandWillowEmissionsG-28
DRAFTENVIRONMENTALIMPACTSTATEMENTSUSITNAHYDROELECTRICPROJECT,FEReNO.7114APPENDIXEGEOLOGYANDSOILSPreparedbyM.e.WintersArgonneNationalLaboratoryE-1
E-3APPENDIXE.GEOLOGYANDSOILSE.lAFFECTEDENVIRONMENTE.l.lProposedProjectE.l.l.lUpperandMiddleSusitnaRiverBasinE.l.l.l.lTopographyTheupperandmiddleSusitnaRiverBasinislocatedinSouthcentralAlaskawithinthePacificMountainSystemphysiographicdivisionofAlaska(Cobb,1974).TheSusitnaRiverheadwatersintheSusitnaGlacier[2,800feet(ft),or850meters(m),MSL]onthesouthernslopeoftheAlaskaRange.ThearcuateAlaskaRange,whichbordersthebasintothenorth,westandeast,isapproximately600miles(mi)[970kilometers(km)]longand50to80mi(80to130km)wide.Mostpeaksarebetween5,000and8,200ft(1,500and2,500m)MSLnorthof theupperSusitnaBasinandwithinDenaliNationalPark.ElevationsintheAlaskaRangearegreatestinDenaliNationalParkandPreserve,increasingtoamaximumof20,320ft(6,190m)atMountMcKinleyapproximately75mi(120km)northeastofthereservoirsites.FromtheSusitnaGlacier,theSusitnaRiverflowstothesouth-southwestapproximately55mi(88km)throughabroad,glaciated,intermontainevalleyofknobandkettleandbraided-channeltopography.Justsouthofthe"TyoneRiveratapproximately2,200ft(670m)MSL,theriverturnswestandflowsacrossthenorthwesternedgeofthepoorlydrained,lake-speckledCopperRiverLowlandandthenorthernedgeoftheTalkeetnaMountains,anearlycircularmountainmasswithmostpeaksbetween6,000and8,300ft(1,830and2,530m)MSL.Approximately40mi(64km)westofTyoneRivertheSusitnaflowsthroughthebroadV-shapedvalleyattheproposedWatanaDamsite[elevation1,600ft(490m)MSL]neartheconfluenceofDeadmanCreek.Approximately30mi(50km)furtherdownstreamtheSusitnaRiverflowsthroughthedeepgorgeofDevilCanyonandtheproposedDevilCanyondamsite(elevation1000ft,or300m,MSL)afewmilesupstreamofPortageCreek.AfterpassingthroughDevilCanyon,theSusitnaRiverchannelbroadensandtheriverflowstothesouthwestalongthewesternedgeoftheTalkeetnaMountainsandtheeasternborderofDenaliStatePark.Within10mi(16km)oftheprojectdamsites,thetopographyisdominatedbyscouredbedrockknobsandridges,andglacialsedimentdeposits.TheWatanadamsiteislocatedinarelativelybroadV-shapedvalleythatrisessteplikefromasteeperlowerportion[1,600ft(490m)MSL]toflatter,moregentleslopesathigherelevations[2,200ft(670m)MSL].VerticalrockoutcropslimitaccesstothelowersectionsoftheWatanadamsite.AttheDevilCanyonsite,theSusitnaRiverflowsthroughaverynarrow,600-ft(185-m)deepgorge[1,000ft(300m)MSL]about2mi(3km)inlength.Thevalleyisasymmetricalinshape,withthenorthernabutmentslopingabout45°andthesouthernabutmentsteeperatabout60°.Thesouthernabutmentdisplaysoverhangingcliffsanddetachedrockblocks.Thenorthernabutmentislessruggedintheupperhalfbutsteeperinthelowerportion(AcresAmerican,undated).ThepreferredaccessroutetothedamsiteareasisillustratedinFigureE-l.Thisrouteorigi-natesatarailheadinCantwellintheBroadPassorChulitnaRivervalleyandthenfollowstheexistingDenaliHighwaytoapoint21mi(34km)eastof thejunctionoftheGeorgeParksandDenalihighways.Anewroadwouldbeconstt'uctedfromthispointapproximately35mi(56km)duesouthacrossrelativelyflatterrainof theBrushkanaandDeadmancreekvalleystotheWatanadamsite.AccesstotheDevilCanyondevelopmentwouldbeaccomplishedbyarailroadextensionfromtheexistingAlaskaRailroadatGoldCreektoarailheadfacilityadjacenttotheDevilCanyoncamparea.Thisrailroadextensionwouldfollowrelativelylevelterrain[1,600to1,800ft(490to550m)MSL]southoftheSusitnaRiver.ToprovideaccesstotheWatanadamsiteandtheexistinghighwaysystem,aconnectingroadwouldbeconstructednorthoftheSusitnaRiverfromtheDevilCanyonrailheadtotheWatanadamsite.The32-mi(51-km)roadwouldrisegentlytoanelevationofalmost4,000ft(1,220m)MSLbeforedroppinggentlytotheWatanadamsite.TheproposedlocationsoftheconstructionvillageandpermanenttownsiteandtheconstructioncampfortheWatanadamareonlevelterrainnorthoftheSusitnaRiverjustupstreamfromthedamsitebetweenTsusenaandDeadmancreeksatapproximately2.300ft(700m)MSL.TheproposedsitesoftheDevilCanyonconstructioncampandvillageareonthesouthernsideoftheSusitnaRiveronlevelterrain[elevationapproximately1,700ft(520m)MSL]upstreamfromthedamsite.
E-4FigureE-l.AlternativeAccessPlan18(Proposed).[Source:ExhibitE,Vol.9,Chap.10,Fig.E-IO.9]
E-5AlltheproposedborrowpitandquarryareasfortheWatanaandDevilCinyondamsiteconstruc-tionactivitiesarelocatedonrelativelyflatterrainadjacenttotheSusitnaRiverorinbroadvalleysoftributariestotheSusitna(Figs.E-2,E-3).AllbutquarrysiteKandborrowsiteGareneartheWatanadamsite.QuarrysiteAwouldbedevelopedatthesouthernabutmentoftheWatanadamsiteatapproxi-mately2,300to2,600ft(700to790m)MSLinanareathathasbeenglaciallyscouredintoeast-westswales.QuarryLislocatedonarockknob400ft(120m)upstreamoftheproposedupstreamcofferdamonthesouthernbankandisseparatedfromthemainvalleybyarelictchanne1.QuarryBislocatedabout2mi(3km)upstreamfromthedamsiteat1,700to2,000ft(520to600m)MSLalongtheSusitnaRiverandDeadmanCreek(ExhibitE,Vol.~,Chap.10,pp.E-10-84-E-10-99).*BorrowsiteDliesinabroadplateauimmediatelynorthwestoftheWatanadamsiteandextendseastwardnortheastofthedamsite[2,150ft(655m)MSL]towardsDeadmanCreek[2,450ft(745m)MSL].Benchesandswalesupto50ft(15m)inheightdominatethesite/topography.AtborrowsiteH,thetopographyisgenerallyrollingandmuchofthesiteiscoveredbyswampsandmarshes.Thesiteslopesfrom2,400to1,400ft(730to430m)MSLtowardstheSusitnaRiver.BorrowsiteEislocatedonalarge,flat,alluvialfandeposit3mi(5km)downstreamofthedamsiteonthenorthernbankoftheconfluenceofTsusenaCreekandtheSusitnaRiver.Eleva-tionacrossthesitevariesfrom1,410ft(430m)MSLneartheriverlevelto11,700ft(520m)againstthevalleywallstothenorth.BorrowsitesIandJarelocatedintheSusitnaRivervalleyfullywithintheconfinesoftheproposedDevilCanyonandWatanareservoirs(ExhibitE,Vol.9,Chap.10,pp.E-10-89-E-10-97).SecondaryborrowsiteCislocatedinabroadglacialvalley4.5mi(7.2km)upstreamfromTsusenaButte.SecondaryborrowsiteFoccupiesthemiddlestretchofTsusenaCreektonorthofClarkCreek,whereitabutsborrowsiteC(ExhibitE,Vol.9,Chap.10,pp.E-10-87-E-10-94).IntheDevilCanyonarea,borrowsiteGislocatedapproximately1,000ft(300m)upstreamfromtheproposeddamsiteonalarge,flat-lyingfanorterraceextendingfromthesouthernbankoftheSusitnaRiverapproximately80ft(24m)abovetheriver.QuarrysiteKisapproximately5,300ft(1,600m)southofthesaddledamsiteat1,900ft(580m)MSL.Thesiteislocatedontheeast-westfaceoftheexposed200-ft(60-m)highrockcliff(ExhibitE,Vol.9,Chap.10,pp.E-10-100-E-10-103).E.1.1.1.2GeologyBEDROCKGEOLOGYTheDevilCanyonandWatanadamsiteslieintheSusitnaRiverBasinwithintheTalkeetnaMoun-tainsofSouthcentralAlaska.AccordingtoCsejteyetal.(1978),southernAlaskadevelopedbytheaccretionofanumberofcontinentalblocksontotheNorthAmericanplateduringMesozoictimes.Eachoftheseterrainshadvaryinggeologichistoriesandasaresultthestratigraphyandstructureofthisregionishighlycomplex.TheoldestrockswhichoutcropintheregionaremetamorphosedupperPaleozoicclasticflowsandtuffslocallyinterbeddedwithmarble.ThisrocksequencetrendsnortheastwardalongtheeasternportionoftheSusitnaRiverBasin.TriassicandJurassicmetavolcanicandsedimentaryrocksunconformablyover1iethePaleozoicrocksequenceandcanbefoundtooutcroparoundWatanaandPortageCreeks.ThePaleozoicandLowerMesozoicrocksareintrudedbyJurassicplutonicrockscomposedchieflyofgranodioriteandquartzdiorite.TheJurassic-ageintrusiverocksformthebatholithiccomplexoftheTalkeetnaMountains(AcresAmerican,undated).AthickturbiditesequenceofinterbeddedCretaceousgraywackesandargilliteresultingfromtheupliftof theTalkeetnaMountainsandthesubsequentrapiderosionunderliealargepartof theprojectareaandformthebedrockattheDevilCanyonsite.TheserocksweresubsequentlydeformedandintrudedbyaseriesofTertiary-ageplutonicrocks.TheWatanasiteisunderlainbyonesuchplutonicbodywhichcomprisesthesouthernlimitof thedioriteplutonwhichpre-dominatesalongupperTsusenaCreek.Theplutonsweresubsequentlyintrudedandoverlainbyfelsicandmaficvolcanics,andmaficvolcanicsarefounddownstreamfromtheWatanasite(Fig.E-4)(AcresAmerican,undated).*Throughoutthisdocument,referencestospecific"Exhibits"aretotheexhibitssubmittedtoFERCaspartofAlaskaPowerAuthority'sSusitnaHydroelectricProjectLicenseApplication.Referencestospecific"Appendices"(App.)aretotheappendicesprovidedinVolumes2through7ofthisDraftEnvironmentalImpactStatement.
BORROWIQUARRYSITEUMITSSCALEE-6WatanaBorrow/QuarrySit[Source:ExhibitEVOles9Chap.10,Fig.E.10:13]',FigureE-2.
E-7INDEXBLOCKAREACOVERED*SCALENO.EXPLORATIONI··~OO'.cDDAMSlTE'TOPOFBEDROCK1-·500'?(GEOLOGICMAP1"500''~®TAILRACEAREA'*·1000'@BORROWSITEGI··SOO'@)QUARRYSITEK1"1000'LEGENDIlORROWIQUARRYSITELIIiITS*SCALEAFTERREDUCTIOHNOTESTOPOGRAPHYANODETAILSSHOWNONINDIVIDUALFIGURES.o10002000FEETSCALE~I~~5iiiiiiiiiiiii'FigureE-3.DevilCanyonBorrow/QuarrySites.[Source:ExhibitE,Vol.9,Chap.10, Fig.E.10.14]
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[Source:Exhibit E,Vol.7,Chap.6,
Fig.E-6.1]
E-9AttheproposedWatanadamsitethedioriticplutonisgenerallymassiveintextureandcom-petent.Smalldiscontinuousalterationzones,fractionzones,andshears,aswellastwomajorandtwominorjointsets,havebeenfoundatthesite.Thejointsaregenerallysteepandmanyfollowthestructuraltrendoftheregion.Thetwomostprominentareasofshearingandalterationhavebeennamed"TheFins"and"TheFingerbuster."TheFins,locatedupstreamfromtheproposedsiteofthediversiontunnelonthenorthernbankoftheSusitna,isanareaapproximately400ft(120m)widecomprisingbythreemajornorthwest-trendingzonesofshearingandalterationthathaveerodedintosteepgullies.TheFingerbusterislocateddownstreamfromtheproposeddamsite.Thisfeatureisexposedina40-ft(12-m)wide,deep,talus-filledgullyalongtheandesiteporphyry/dioritecontact.Therockcontactisseverelyweathered,withcloselyspacedjointsandslickenslidesindicatingverticaldisplacement(ExhibitE,Vol.7,Chap.6,pp.E-6-13-E-6-16).TwoburiedrelictriverchannelsthatcouldpotentiallyaffectreservoirimpoundmentexistwithintheWatanaprojectarea.TheWatanarelictchannelextendsfromalocationapproximately2,000ft(600m)upstreamfromthedamsiteonDeadmanCreektoTsusenaCreekandapparentlyfollowsthesoftershearedandfracturedrockof"TheFins"structure.TheWatanarelictchannelisfilledwithapproximately450ft(130m)ofoverburdendepositsincludingbasalfill,alluvium,glacialfluvialsilts,sands,andgravelsaswellaslacustrineclays(AcresAmericanundated:Vol.1,pp.6-36-6-39).TheFogLakesburiedchannelextendsbetweentheWatanadamsiteandthehigherground5mi(8km)tothesoutheast.Thechannelisfilledbyapproximately350ft(l00m)ofglacialdeposits(ExhibitE,Vol.7,Chap.6,p.E-6-17).ThecontactsbetweentheinterbeddedgraywackesandargillitesattheDevilCanyonsitearetightandbothrocksarefreshandhard.Theargillite/graywackehasbeenseverelydeformedbyfoldingandwhereexposed,foliationplaneswhichparallelbeddingplanesappearslatyandphylitic.Thenortherncanyonwallatthedamsiteappearstobecontrolledbythebeddingplanes.Afewofthenumerousfelsicandmaficdikesintheareaarecloselyfracturedanderodedandhaveformedsteep,talus-filledgullies,someofwhichexhibitshearingwiththehostrock(ExhibitE,Vol.7,Chap.6,p.E-6-18).FourjointsetshavebeendelineatedintheDevilCanyonarea.Looserockblockshavebeenformedbytheintersectionoftwoofthesejointsets,andonejointsetopensonthesouthernbank,dippingtowardstherivercreatingapotentialslippageplane(ExhibitE,Vol.7,Chap.6,p.E-G-19).Shearandfracturezonesexistbeneaththeproposedsaddledamarea.ThesezonesgenerallyhaveverticaJtosteepnortheastlydipsandaregenerally1ft(0.3m)wide(ExhibitE,Vol.7,Chap.6,p.E76-20).ThebedrockunitsunderlyingotherprojectfeaturesinthevicinityofthedamsiteareillustratedinFigureE-4.QuarrysitesA,L,andpossiblyBattheWatanadamsite(Fig.E-2)willbeconsideredaspoten-tialsourcesofrockfillfordamconstruction.QuarrysiteAwouldbedevelopedinalarge,exposeddioriteandandesiteporphyryrockknobapproximately1squaremile(mi2)[2.6squarekilometers(km2)JatthesouthernabutmentoftheWatanadamsite.QuarryLwouldconsistprimarilyofdiorite,withoccasionalandesiticsillsordikes.BedrockatquarryB,asecondaryquarrysite,isinterfingeredwithpoor-qualitysedimentaryvolcanicandmetamorphicrockandiscoveredwiththickoverburdeninseveralareas(ExhibitE,Vol.9,Chap.10,pp.E-I0-84-E-I0-99).AtDevilCanyonquarrysiteK,thebedrockisaslightlymetamorphosed,medium-grainedbiotitegranodioritethatcontainsinclusionsofargillite(ExhibitE,Vol.9,Chap.10,p.E-10-103).SURFICIALGEOLOGYThefollowingdescriptionofthesurficialgeologyoftheprojectareaisbased(unlessother-wisespecified)onthephotointerpretationterrainevaluationconductedbyAcresAmericanInc.(undated:Vol.2,AppendixJ).DuringthePleistocene,theentireSusitnaprojectstudyareawasrepeatedlyglaciated.TheearlyPleistoceneglacierscompletelycoveredsouth-centralAlaska,coveringmanyofthemoun-tainsintheprojectareaasevidencedbytheirroundedsummits.Thelastglaciationtocom-pletelycovertheprojectareamaybecorrelatedwiththeIllinoianglaciationoftheContinentalUnitedStates(Pewe,1975).IceflowingfromtheAlaskaRange,theTalkeetnaMountains,andsevera1high1andcentersspreadacrosstheproject1owlands,depositingasheetofgray,gravelly,sandy,andsiltybasaltill.Thetillvariesinthicknessfrom100ft(30m)inriverbasinstoathinblanketoverbedrock.Thistillisbelievedtooverlieolder,poorlyexposedQuaternarysediments.ProminentlateralmorainesofthemajorglacialadvanceoccurontheflanksofthemountainsborderingthecentralWatanaCreek-StephanLakeLowland.AnextensiveglaciolacustrinesequenceoverliesthebasaltillunitintheareasoccupiedbyproglaciallakesformedwhentheglaciersfromtheAlaskaRangeblockedtheexistingdrainage
E-10patterns.TalkeetnaRiverValleyglaciersblockedlowdividesbetweenStephanLakeandtheTalkeetnaRiver,andtheCopperRiverBasinwasoccupiedbyanextensiveproglaciallake.LacustrinedepositscovermuchoftheWatanaCreek-StephanLakeLowlandandextendupstreamalongtheSusitnaRivertotheSusitna-CopperRiverLowland.IntheWatanaCreek-StephanLakeLowland,theunitisgenerallylessthan20ft(6m)thickandcomposedofmediumtofinesandwithasignificantgravelcontent.ThelakedepositsoftheCopperRiverLowlandarethoughttobethickerandfiner.IntheWatanaCreek-StephanLakearea,severaldeltasandstrandlinefeatureswereformedataboutthe3,000ft(900m)MSL.Hummocky,coarse-graineddepositsofablationtilloverliethelacustrinesedimentsbetweenTsusenaandDeadmancreeksandthebasaltillinthevalleysnorthofDeadmanCreekandintheDenaliHighwayarea.Insmall,isolatedproglaciallakes,lacustrinesedimentdepositshavealsobeenfoundoverlyingtheablationtill.EskerandkamedepositsarealsofoundalongtheSusitnaRiverbetweentheOshetnaandTyonerivers.FluvialerosionandentrenchingoftheprojectareaportionoftheancestralSusitnaanditstributarystreamsoccurredintheinterva1sbetweenglacia1advances.RemnantsofolderentrenchingeventsarepreservedinseveralabandonedandburiedchannelsectionsalongthemodernSusitnaRiver,suchasattheVeeCanyondamsite,atDeadmanandTsusenacreeksnorthoftheWatanadamsite,aboveandsouthofthesouthernabutmentattheDevilCanyondamsite,andneartheriverleveljustupstreamoftheWatanadamsiteanddownstreamofWatanaCreek.Manyoftheserelictchannelsarefilledwithfluvial,glacio-fluvial,lacustrine,andoutwashmaterials.SincethePleistocene,downcuttingbytheSusitnaRiverhasexcavatedaV-shapedvalleywithinthewideglaciatedvalleyfloorandhasrejuvenatedmanytributarystreams.SeveralterracesarefoundabovetheSusitnaRiveranditsmajortributaries,mostnotablyTsusenaCreek.Someoccurhighonthevalleywallsaserodedterraceremnants(upstreamofWatanaCreek),whileothersoccuras veryrecentlow,flatplanarfeatures.Theterracesarefrequentlymodifiedbythedepositionofalluvialfandebrisand/orsoilsolifluctionlobesandsheetsacrosstheirsurfaces.Alluvialfanshavealsobeendepositedwheresteepsmalldrainagesemergeontofloorsofwiderglaciatedvalleys.Numerouscolluvialdepositshavebeenformedasaresultoftheeffectsoffrostcracking,cryoturbation,andgravity.Steep,rubbley,talusconeshaveaccumulatedbelowcliffs,andthindepositsoffrost-churnedsoilscoverbedrockonslightlylessprecipitousslopes.Solifluctionhasmodifiedthesurficialglacialtilland/orlacustrinedepositsonnumerousslopesinhigh-landareas(asalongDevilCreek)andonthebroadlowlands.Severaltypesofmassmovementssuchassolifluctions,bimodalflows,skinflowsandsmallrotationalslideshaveoccurredthroughouttheprojectarea.Mostoftheslopeinstabilityhasbeenfoundwithinthebasaltillunitonsteepslopesandabovetheactivelyerodingstreams.Failureofthismaterialappearstobestronglyrelatedtosaturationofsoilfollowingthethawofpermafrost.Thebasalunitisfrequentlyoverlainbylacustrinematerialandthelacustrinematerialfailswiththetill.Mostfailuresoccurassmall,shallowdebrisslidesordebrisflows;however,afewlargeslumpfailuresoccur(ExhibitE,Vol.7,Chap.6,p.E-6-34).ThesteepvalleywallsattheDevilCanyonsitearecoveredbyathinveneerofoverburden.Glacialdepositscoverflatteruplandareastodepthsof5to35ft(2to11m),whiletalusdepositsarefoundatthebaseofthevalleywalls.Atopographicdepressionalongthesouthernbankofthelakesintheareaisfilledwithglacialdepositstoadepthof85ft(26m).Upto100ft(30m)ofcoursetomassivealluviumispresentintheriverchannel.AlluvialfanandpointbardepositsattheCheechakoCreekconfluencerangefrom100ft(30m)tomorethan300ft(90m)inthickness(ExhibitE,Vol.7,Chap.6,p.E-6-18),upstreamfromDevilCanyonCreek,theriverva11eyslopesarecoveredwithincreasingamountsofbasa1tills,coarse-grainedfloodplaindepositsandalluvialfandeposits(ExhibitE,Vol.7,Chap.6,p.E-6-32).Atthe\'Jatanareservoirsite,overburdendepthrangesfrom0to80ft(0to24m).Ta1usdepositsoccuratthelowerslopes;depositsofglacialtill,alluvium,andtalusarefoundintheupperareasoftheabutmentsnearthetopoftheslopes.Riveralluviaconsistingofsand,silt,coarsegravels,andbouldersaverage80ft(24m)inthicknessbeneaththeproposeddamsite(ExhibitE,Vol.7,Chap.6,p.E-6-13).AttheWatanadamsitearea,borrowsitesDandHareconsideredaspotentialsourcesofsemi-pervioustoperviousmaterial;sitesC,E,andFforgranularmaterial;andsitesIandJforperviousgravel(Fig.E-2).AllbutsitesCandFareconsideredprimarysitesfordevelopment(ExhibitE,Vol.9,Chap.10,p.E-10-84).BorrowsiteDiscoveredwithpotentiallylargequantitiesofclayandsilt.BorrowsiteHiscoveredbyanorganiclayerandunderlainbylayersofsilt,sand,andgravel.BorrowsiteEisunderlainbyasequenceofboulderytillandriverandfloodplaingravelsandsands.BorrowsitesIandJcontainlargevolumesofriverandfloodplaingraveldeposits(ExhibitE,Vol.9,Chap.10,pp.E-10-86-E-IO-98).
E-llSecondaryborrowsiteCoverliesbasaltill,outwash,andalluvialdepositsconsistingofsatu-ratedgravelsandsands.SecondaryborrowsiteFoverliesaseriesofgravelbarsandterraces.Depositsatthissiteareexpectedtoconsistofcleansandsandgravels(ExhibitE,Vol.9,Chap.10,pp.E-10-81-E-10-95).AtDevilCanyon,borrowsiteGoverliesSusitnaRiveralluvialgravelsandsands,ancientter-races,CheechakoCreekalluviumandtalus(ExhibitE,Vol.9,Chap.10,p.E-10-101).E.1.1.1.3SoilsandPermafrostTheprominantsoilsalongtheSusitnaRiverValleyaregenerallywell-drainedSpodsols.Specifically,HumicCryorthods(SOlO)arepresentintherivervalleydownstreamoftheDevilCanyondamsiteandPergelicCryorthods-HisticPergelicCryaquepts(S015)arepresentupstream.PergelicCryorthods-HisticPergelicCryaquepts(S016)arepresentonthehighlandsnorthoftheSusitnaRivervalley.Descriptionsofthesesoilsandtheirlimitationsforuseanddevelop-mentarepresentedinTablesE-1andE-2.Thesesoilshaveformedprimarilyongravelly,glacialdepositsorloamycolluvialsediments.Thesesoilsaretypicallyunsuitedforcultivationbutmaybeusedforgrazing.Highwatertables,periodicflooding,steepslopes,poorstability,lowpermeabilities,andstoninessseverelylimitthepotentialuseofthesesoilsalthoughwelldrainedsoilsinthisareamayhaveonlyslightormoderatelimitationsforconstruction(Riegeretal.,1979).SoilsalongtheremainingsectionsoftheriverareclassifiedasInceptisolsorincompletelyformed,horizonlesssoils.InthehighlandssouthoftheSusitnaRiverValley,soilsofthePergelicCryumbrepts-RoughMountainlandassociation(IU3)occur(seeTableE-1).TheIncepti-solsinthisareaarenotsuitableforcultivationandhaveseverelimitationsforconstructionandroadsduetofloodingandhighwatertables(Riegeretal.,1979).ThroughouttheupperandmiddlereachesoftheSusitnaRiver,permafrostisgenerallyshallowinmostareasbutisdeeporabsentinsomeoftheverysandyorgravellymaterial.IntheWatanareservoirarea,permafrosthasbeendelineatedprimarilyontheflatterslopesbelowanelevationof2,300ft(700m)MSLandisnearlycontinuousinthebasaltillsandissporatictocontinuousinthelacustrinedeposits(ExhibitE,Vol.7,Chap.6,p.E-6-34).Permafrostisalsopresentprimarilyonthenorth-facingslopesandisevidencedbygroundice,patternedgroundstonenets,andslumpingofglacialtilloverlyingpermafrost.Frozenalluviumandinterstitialicecrystalshavebeenobservedinoutcropsanddrillholedrivesamplesandmaybe200to300ft(60to90m)thick.Temperaturemeasurementsofthepermafrostindicatethatthepermafrostiswarm(withinonedegreeoffreezing)(ExhibitE,Vol.7,Chap.6,p.E-6-16).Incontrasttothenorth-facingslopes,thesouth-facingslopesarelesssteepandbetterdrainedwhich"maybeindicativeoflesscontinuouspermafrostand/orslightlycoarsersurfacematerials(ExhibitE,Vol.7,Chap.6,p.E-6-35).Theconstructioncampandvillagesiteoverliepermafrostfreeablationtillandorganicdeposits(AcresAmerican,undated:AppendixJ).IntermittentpermafrosthasbeenfoundinthevicinityoftheWatanarelictchannel,todepthsof240ft(70m)intherelictchannelandtovaryingdepthsinborrowsiteD.AsoverburdeninandaroundtheDevilCanyondamsiteareaisthinorabsent,permafrosthasnotbeennoted.Thepotentialforsporadicpermafrosttobepresentinsomeareasofthesouthernabutmenthasbeennoted~'aerialphotographs(ExhibitL~~VoLJ,Chap..6,p.E-6-21).Upstr~~fromthesouthernabutr(leatpermarostmaybepresentinthebasarrrn~dep~o~~iT~CEXf1iDirr,Vol.7,Chap.6,p.E-6).Permafrostisexpectedtooccurinthebasaltillandorganicdepositswhichunderlietheconstructioncampandvillagesitessouthofthedamsite(AcresAmerican,undated).Nodeterminationhasbeenmadeastothepresenceofpermafrostalongtheproposedaccessroute;however,discontinuouspermafrostmaybeexpectedwithinfinesurficialdepositsandonthenorthernslopesoftheSusitnavalley.E.1.1.1.4MineralResourcesWithintheupperSusitnaRiverBasin,mlnlnghasbeencharacterizedsincethe1930sbylow-densityclaimsandintermittentactivity.SeveralinactiveclaimsexistwithintheprojectedareasoftheWatanaandDevilCanyonreservoirimpoundments;however,nominingactivityhasoccurredinthisareaandnointerestinfurtherexplorationofthemineralpotentialswithintheprojectareahasbeenexpressedbyoutsideparties(ExhibitE,Vol.7,Chap.6,p.E-6-5).ActiveplacermininghasbeenconcentratedprimarilyinGold,Chunilna(Clear)andPortagecreeks,withsomeactiveclaimsbeingpresentaroundStephenandFoglakes,JayCreek,andtheWatanaHillseastofJayCreek.Gold,copper,andsilverplacerminingatGoldCreekwasactivefromtheearly1950sthroughthelate1970s.GoldplacerclaimshavebeenworkedonChunilnaCreeksincethelate19thCenturyandatleastsixminingclaimsremain.OnlyoneclaimremainsactiveonPortageCreek,whereminingalsodatesbacktothelate19thCentury(ExhibitE,Vol.7,Chap.6,p.E-6-5).
E-12TableE-1.SoilAssociationswithintheSusitnaProjectStudyArea-GeneralDescription,OffroadTrafficabilityLimitations(ORTL),CommonCropSuitability(CCS),RoadLocationLimitations(RLL),andLowBuildingLimitations(LBL)t1EF1-TypicCryofluvents-TypicCryaquepts,loamy,nearlylevel.Dominantsoilsofthisassociationconsistofwell-drained,stratified,waterlaidsedi-mentofvariablethicknessoverasubstratumofgravel,sand,andcobblestones.Watertab1eishighinothersoils,inc1udingthescatteredmuskegs.ORTL:S1ight-Severe(wet;subjecttoflooding);CCS:Good-Poor(lowsoiltemperaturethroughoutgrowingseason).RLL:Moderate(flooding);LBL:Severe(flooding).E01-TypicCryorthents,loamy,nearlyleveltorolling.Thisassociationoccupiesbroadterracesandmoraines;mostofthebedrockisunderthickdepositsofverygravellyandsandyglacialdrift,cappedwithloessblownfrombarrenareasofnearbyfloodplains.Well-drained,thesesoilsarethemosthighlydevelopedagriculturallandsinAlaska.ORTL:Slight,CCS:Good-Poor(Shortfrost-freeperiod);RLL,LBL:Moderate~Severe(steepslope,susceptabilitytofrostaction).HYI-SphagnicBorofibrists,nearlylevelassociation.Broaddepressionsandbasinsinglaciatedlowlandshavedeep,poorlydrainedpeatsoils.Organicmatterisatleast5feetthickoververygravellydrift.ORTL,RLL,LBL-VerySevere(wet,organicsoils).CCS-Unsuited(wet,organic).IA15-DrystricCryandepts,loamy,hillytosteep-FluvaquenticBorohemists,nearlylevelassociation.Onfootslopesandhills,thesesoilsarewelldrained.Underathickmatofdecomposedorganicmatterthesoilsarepredominantlyfinegrained,verystronglyacid,thixotropicandextendtodepthsof20to40inches.Verypoorlydrainedfibrousorganicsoilsoccurindepressionsonhighbenchesandindrainageways.ORTL:SeveretoVerySevere(steepslopes,organicsoil);CCS-Poor-Unsuited(steepslopes,lowsoiltemperatures,organicsoilswet);RLLandLBL-SeveretoVerySevere(steepslopes,lowloadsupportingcapacity.IQ2HisticPergelicCryaquepts-loamy,nearlyleveltorolling.Thedominantsoilsinthisassociationarepoorlydrained,developedinsiltymaterialofvariablethicknessoververygravellyglacialdrift.Mostsoilshaveashallowpermafrosttable,butinsomeoftheverygravelly,well-drainedsoils,permafrostisdeeporabsent.ORTL:Severe-(wet);CCS:Poor;RLL,LBL:Verysevere(wet,permafrost).IQ3HisticPergelicCryaquepts-TypicCryofluvents,loamy,nearlylevel.Soilsofthisassociationlocatedinlowareasandmeanderscarsoffloodplainsarepoorlydrainedsiltloamorsandyloam;theseareusuallysaturatedaboveashallowpermafrosttable.Soilsonthenaturalleveesalongexistingandformerchannelsarewell-drained,stratifiedsiltloamandfinesand;permafrostmayoccur.ORTL:Severe(wet);CCS:Unsuitable(lowtemperatureduringseason;wet)-Good(butsubjecttoflooding);RLL,LBL:Moderate-VerySevere(wet,permafrost).IQ25-PergelicCryaquepts-PergelicCryochrepts,verygravelly,hillytosteep.Soilsofthisassociationoccupyingbroadridgetops,hillsides,andvalleybottomsathighelevationarepoorlydrained,consistingofafewinchesoforganicmatter,athinlayerofsiltloam,underwhichisverygravellysiltloam;permafrosttableisatadepthgreaterthan2feet.Inlocationsofhillsandridgesabovetreelinethesesoilsarewell-drained.ORTL:Severe(wet,steepslopes);CCS:Unsuitable(wet;lowsoiltemperature;short,frost-freeperiod);RLL,LBL:Severe(steepslopes,wet).IRI-TypicCryochrepts,loamy,nearlyleveltorolling.Onterracesandoutwashplains,thesesoilsarewell-drained,havingathinmatofcourseorganicmatterovergraysiltloam.Inslightdepressionsandformerdrainageways,thesearemoderatelywell-drainedsoils,havingathinorganicmatoversiltloam,withasandorgravellysubstratum.ORTL:Slight;CCS:Good-Fair(shortfrost-freeperiod);RLL,LBL:Moderate(lowloadsupportingcapacity,frostheaving).
E-13TableE-l.(Continued)SoilsRoadsRMI-IRIO-TypicCryochrepts,verygravelly,nearlyleveltorolling-AericCryaquepts,loamy,nearlyleveltorolling.Generallywe11-tomoderatelywell-drainedsoilsofterraces,outwashplains,andlowmoraines.Typically,thesesoilshaveasiltloamupperlayerovergravellysoils.Pocketsofpoorlydrainedsoilswithashallowpermafrosttableoccupyirregulardepressions.ORTL,RRL,LBL:Slight;CCS:Good-Poor(wet;lowsoiltemperaturethroughoutgrowingseason;short,frost-freeperiod).IR13-TypicCryochrepts-HisticPerge1icCryaquepts,verygravelly,hillytosteepassocia-tions.Onsteep,hillsidesandfoots10pes,thesoilsarewell-drainedandareformedinverygravellyandstonycolluviumandresidualmaterial.Soilsarecommonly20to40inchesthickoverbedrockonthesteeperslopes.ORTL,RLL,LBL:Severe(steepslopes);CCS:Poor(steepslopes,droughtysoils).IR14-A1ficCryochrepts,loamy,hillytosteep-HisticPergelicCryaquepts,loamy,nearlyleveltorolling.Onmid-slopes,thesesoilsarewelldrained,ofmicaceousloessrangingtomanyfeetthickovershatteredbedrockofmicaschist.Bottomlandareasarepoorlydrainedwitharelativelythicksurfaceofpeatmoss.Inthesesoils,permafrostrangesfrom5to30inchesindepth.ORTL:Moderate-Severe(steepslope;wet);CCS:Poor(steepslopes;highlysusceptibletoerosion);RLL,LBL:Severe(steepslopes).IU3-PergelicCryumbrepts,verygravelly,hillytosteep-roughmountainousland.Onhighalpineslopesandridgesclosetomountainpeaks,thesesoilshaveathinsurfacematoforganicmaterialbeneathwhichisan8tol2-inch-thick,darkbrownhorizonformedinverygravellyorstonyloam.Thisassociationalsoincludesareasofbarerockandstonyrubbleonmountainpeaks.ORTL,RLL,LBL:Severe-VerySevere(steepslope);CCS:Unsuitable(short,frost-freeperiod;shallowbedrock).RoughMountainousLand.Rough,mountainouslandcomposedofsteep,rockyslopes;icefie1ds;andglaciers.onlowerslopesarestonyandshallowoverbedrock.Unsuitableforagriculture.feasibleonlyInmajorvalleys.SOl-TypicCryorthods,loamy,nearlyleveltorolling-SphagnicBorofibrists,nearlylevel.Lowhills,terraces,andoutwashplainshavewell-drainedsoilsformedinsiltyloessorash,overgravellyglacialtill.Depressionshavepoorlydrained,fibrousorganicsoils.ORTL:Slight-VerySevere;CCS:Good(onwell-drainedsoils)-Unsuitable(wetorganicsoil);RLL,LBL:Moderate(frostactionsusceptability,lowloadsupport-ingcapacity)-Severe(wet,organicsoils).S04-TypicCryorthods,verygravelly,nearlyleveltorolling-SphagnicBorofibrists,nearlylevel.Soilsofnearlyleveltoundulatingoutwashplainsarewell-drainedtoexcessivelywe11-drained,formedinamantelofsiltyloessoververygravellyglacialtill.Soilsoftheassociationlocatedindepressionsareverypoorlydrained,organicsoils.ORTL,RLL,LBL:Slight-VerySevere;CCS:Good-Unsuitable(wet,organic).S05TypicCryorthods,verygravelly,hillytosteep-SphagnicBorofibrists,nearlylevel.Onthehillsandplains,thesesoils,formedinathinmetalofsiltyloessoververygravellyandstonyglacialdrift,arewelldrainedandstronglyacid.Inmuskegs,mostofthesesoilsconsistoffibrouspeat.ORTL:Severe(steepslope);CCS:Unsuitable(steepslopes;stonesandboulders;short,frost-freeseason);RLL,LBL:Severe-VerySevere(steepslopes,stony,wet,organicsoils).SOlO-HumicCryorthods,verygravelly,hillytosteep.Generally,thesearewell-drainedsoilsoffoothillsanddeepmountainvalleys,formedinverygravellydriftwithathinmantelofsiltyloessormixtureofloessandvolcanicash.Thesesoilsarecharacteristicallyfreeofpermafrostexceptinthehighestelevation.ORTL,RLL,LBL:Severe(steepslope);CCS:Poor-Unsuitable(lowsoiltemperaturethroughoutgrowingseason;steepslopes).
[-14Table[-1.(Continued)S015-PergelicCryorthods-HisticPergelicCryaquepts,verygravelly,nearlyleveltorolling.-Onlowmorainehills,thesesoilsarewelldrained,formedin10to20inchesofloamymaterialoververygravellyglacialdrifts.Onfootslopesandvalleys,thesesoilstendtobepoorlydrained,withshallowpermafrosttable.ORTL:Slight-Severe(wet);CCS:Unsuitable(short,frost-freeperiod;wet;stonesandboulders);RLL,LBL:Moderate(permafrost)-Severe(wet,steepslopes).S016-PergelicCryorthodsverygravelly,hillytosteep-HisticPergelicCryaquepts,loamy,nearlylevel.-Onhillymorainesthesesoilsarewell-drained;beneathathinsurfaceofpartiallydecomposedorganicmatter,thesoilshavespodichorizonsdevelopedinshallowsiltloamoververygravellyorsandyloam.Invalleysandlongfootslopes,thesearepoorlydrainedsoils,withathick,peatylayeroverafrost-churnedloamorsiltloam.Here,depthofpermafrostisusuallylessthan20inchesbelowsurfacemat.ORTL:Severe(steepslope;wet);CCS:Unsuitable(short,frost-freeperiod)-Poor(wet;lowsoiltemperature);RLL,LBL:Severe-VerySevere(steepslopes,wetpermafrost).t1SeeTableE-2fordefinitionsforOffroadTrafficabilityLimitations(ORTl),CommonCropSuitability(CCS),RoadLocationLimitations(Rll),andlowBuildingLimitations(lBl).Conversions:Toconvertfeettometers,multiplyby0.305;toconvertinchestocentimeters,multiplyby2.54.Source:Riegeretal.(1979).
E-15TableE-2.DefinitionsforOffroadTrafficabilityLimitationsandCommonCropSuitabilityofSoilAssociationsOFFROADTRAFFICABILITYLIMITATIONS(ORTL)OffroadTrafficabilityreferstocross-countrymovementofconventionalwheeledandtrackedvehicles,includingconstructionequipment.SoillimitationsforOffroadTrafficability(basedonfeaturesofundisturbedsoils)wereratedSlight,Moderate,Severe,andVerySevereonthefollowingbases:-51ightSoillimitations,ifany,donotrestrictthemovementofcross-countryvehicles.ModerateSoillimitationsneedtoberecognizedbutcangenerallybeovercomewithcarefulrouteplanning.Somespecialequipmentmayberequired.SevereSoillimitationsaredifficulttoovercome,andspecialequipmentandcarefulrouteplann-ingarerequired.Thesesoilsshouldbeavoidedifpossible.VerySevereSoillimitationsaregenerallytoodifficulttoovercome.Generally,thesesoilsareunsuitableforconventionaloffroadvehicles.COMMONCROPSUITABILITY(CCS)t1SoilswereratedasUnsuitable,Good,Fair,andPoorfortheproductionofcommoncropsonthefollowingbases:UnsuitableSoilorclimatelimitationsaregenerallytooseveretobeovercome.Noneofthecommoncropscanbegrownsuccessfullyinmostyears,orthereisdangerofexcessivedamagetosoilsbyerosionifcultivationisattempted.GoodSoilorclimatelimitations,ifany,areeasilyovercome,andallofthecommonAlaskancropscanbegrownunderordinarymanagementpractices.OnsoilsofthisgroupFairSoilsorclimatelimitationsneedtoberecognizedbutcanbeovercome.Commoncropscanbegrown,butcarefulmanagementandspecialpracticesmayberequired.PoorSoilsorclimatelimitationsaredifficulttoovercomeandaresevereenoughtomaketheusequestionable.Thechoiceofcropsisnarrow,andspecialtreatmentormanagementpracticesarerequired.Insomeplaces,overcomingthelimitationsmaynotbefeasible.OnsoilsofthisgroupROADLOCATIONLIMITATIONS(RLL)Thesoillimitationsratingsarebasedonthepropertiesofundisturbedsoiltoadepthof5feet.Itisassumedthatanysurfacelayeroforganicmaterialwillberemovedinconstruc-tion.-SllghtSoillimitations,ifany,areeasilyovercome.ModerateSoillimitationscanbeovercomebutresultindifficultandcostlymodificationsinroaddesignandconstruction.
E-16TableE-2.(Continued)SevereSoillimitationsaredifficulttoovercomeandmayaffectroadalignmentandlocation.Specialdesignrequirementsmayresultinexcessiveconstructioncosts.VerySevereSoillimitationsaresodifficultorexpensivetoovercomethatsoilsshouldbeavoidedifpossible.LOWBUILDINGLOCATION(LBL)Ratingsareintermsofsoillimitationsforbothconstructionandmaintenanceofbuildingswithrelativelylightfoundationloadssuchasresidences,servicebuildings,picnicareashelters:-SlightSoillimitations,ifany,areeasilyovercomeanddonotrequireunusualplanningordesignoralterationsofnaturalsoilfeatures.ModerateSoillimitationsneedtoberecognizedbutcanbeovercomebycarefulplanningordesign.Afewspecialprecautionsoralterationsmaybeneeded.SevereSoillimitationsaredifficulttoovercome.Specialprecautionsoralterationsarerequiredwhichmaynotbeeconomicallyfeasible.VerySevereSoillimitationsaretooseveretobeovercomeexceptatgreatcost.Soilsaregenerallyunsuitableforlowbuildings.t1TheprincipalcropsgrowninAlaska--barley,oats,grassesforhayandsilage,aDdpotatoes--wereconsideredinpreparingratings.Althoughonlythesecropswereused,itisassumedthattheratingsarealsovalidforvegetablesandothercropssuitedtoAlaskansoils.Conversion:Toconvertfeettometers,multiplyby0.305.Source:Riegeretal.(1979).
E-17Althoughextensivedepositsofcoal,themajormineralresourceoftheMatanuska-SusitnaBorough,arelocatedtothesouthandwestoftheprojectarea,themiddleandupperSusitnaBasinhasazeropotentialforcoal(Merrittetal.,1982b).ThemiddleandupperSusitnaBasinliesontheedgeoftheCopperRiverPlateau,however,whichisanareaof1,063,400acres(430,300ha)offuel-gradepeat,thesecondlargestareaofpeatreservesinthestate(RawlinsonandHardy,1982).E.1.1.1.5SeismicityAccordingtoCsejteyeta1.(1978)therocksoftheTalkeetnaMountainsregionhaveundergonecomplexandintensethrusting,folding,faulting,shearing,anddifferentialupliftingasaresultofregionalmetamorphismandplutonism.Threemajorperiodsofdeformationhavebeenrecognized--(l)aperiodofmetamorphism,plutonism,andupliftlastingfromtheLateEarlytotheLateJurrassic,(2)anintensealpineorogenyintheMiddletoLateCretaceous,and(3)aperiodoffaultingandfoldingintheMiddleTertiarythatextendedpossiblyintotheQuaternary.ThemajorstructuralfeaturesoftheTalkeetnaMountainstrendnortheasttosouthwestandwereformedprimarilyduringtheCretaceousalpineorogenywiththeaccretionofnorthwestdriftingcontinentalblocksintotheNorthAmericanplate.SEISMICFEATURESWithintheSusitnaBasinandsurrounding5lpe~s,severa1potentialsourcesofs.eism-i~~ooA~~~'motionatthereservoiranddamsiteshq~~igentlfled(Woodward-Clyde,1982).ThesesourcesincludetheCastleMountainfault,theD~fault,theBenioffinterplateregion,andtheBenioffintraplateregion(Fig.E-5).ThedistancesoftheclosestapproachofthesepotentialsourcestotheproposeddamsitesarelistedinTableE-3.TheCastleMountainfaultisastrik~:::sJ.;jfaultthatdisstee1tothenorthand,,~lr~~n9~~~~,,_~ceast-northeast/west-southwest.The~iautispredominantlyarightlateralstrike-slipfaultwithanarcuateeast-westtre~othfaultsareregardedasmajorsuturezoneswithintheearth'scrust,anddisplacementalongportionsofbothfaultshasoccurredsincetheendoftheMesozoic.DisplacementhascontinuedinthewesternsegmentoftheCastleMountainfaultandtheMcKinleystrandoftheDenalifaultsincetheHolocene.Withrespecttothetwodamandreservoirsites,theeffectofpotentialseismicgroundmotionsfromtheDenalifaultisconsideredtobesignificantlygreaterthanfromtheCastleMountainfault(Woodward-Clyde,1982).TheBenioffzoneisazoneofseismicityassociatedwiththesubductionofthePacificplateundertheNorthAmericanplatealongtheAleutianTrenchintheGulfofAlaska.Thetwosub-zonesorregionsoftneBenioffzoneareconsideredtobeasourceofseismicityforthesites(Woodward-Clyde,1982).Althoughthesesourcesarethoughttocontainfaultswithrecentdis-placement*thatcouldcauseseismicgroundmotionattheWatanaandDevilCanyonsites,generallyitisexpectedthatbecauseoftheirdistancefromthesites,thesefaultsdonothavethepotentialforrupturethroughthesites(Woodward-Clyde,1982).OnthebasisoftheirpotentialeffectongroundmotionandsurfaceruptureconsiderationsandtheirproximitytotheWatanaandDevilCanyonsites,13featureswereinvestigatedindetailedfieldstudies(Fig.E-6).Accordingtothe1982Woodward-Clydeseismicreport,noneofthesefeatureswasfoundtobeseismicallysignificantwithrespecttothesites.TheWatanasiteislocatedinthevicinityof4ofthe13features(TableE-4).Twoofthesefeatures,theTalkeetnathrustfaultandtheFinsfeature,arejudgedtobefaultswithoutrecentdisplacement.TheSusitnaandtheWatanariverfeaturesarejudgedtobelineamentsthatarenotrelatedtoyouthfulfaulting.OftheninefeaturesneartheDevilCanyonsite,onlyonefeature,KD5-2,isafault;theeightotherfeaturesareidentifiedas1ineaments.Norecentdisplacementisnotedforanyofthesefeatures(Woodward-Clyde,1982).WithintheSusitnaBasin,onlytheCastleMountainandDenalifaultsareconsideredtohavebeensubjecttorecentdisplacement,andtheBenioffzoneisalsoconsideredtobeapotentialseismicsource.Becauseoftheirrecentseismicactivity,themaximumcredibleearthquake(MCE)wasestimatedforeachofthesethreepotentialseismicsourcesbyWoodward-ClydeConsultants(1982).Incaseafaultwithrecentdisplacementhadbeenoverlookedinthegeologicinvestigations,estimationsofadetectionlevelearthquakeforthisfaultwerealsomade.EstimationsofMCEsforeachseismicsourceweremadeusingboththedeterministicandpro-babilisticapproach.ForthedeterministicapproachitisassumedthattheMCEwilloccurduringthelifetimeofthefacilityandattheclosestapproachoftheseismicsourcetothe*Recentdisplacementasdefinedforthisprojectisafaultthathashadsurfaceruptureduringthepast100,000years.
o...!!!!!!!!!!!!!!!!!!!!!5iiiiOiiiiiiiiiiiiiiii~'90MILESSCALEL.E-18TRANSITZONELOCATIONOF1964EARTHQUAKEPLATEMOTIONRELATIVETONORTHAMERICANPLATELEGEND:--"0.MAPPEDSTRIKE-SLIPFAULT,ARROWS~SHOWSENSEOFHORIZONTALDISPLACEMENT.MAPPEDSTRIKE-SLIPFAULTWITHDIP~USLIPCOMPONENT,LETTERSSHOWSENSE-.;:--0OFVERTICALDISPLACEMENT:UISUP.DISDOWN.___MAPPEDFAULT,SENSEOFHORIZONTALDISPLACEMENTNOTDEFINED.- - - -INFERREDSTRIKE-SLIPFAULT.••••MAPPEDTHRUSTFAULT,SAWTEETHONUPPERPLATE.FigureE-S.SignificantSeismicFaultsandFeatureswithintheSusitnaBasin.[Source:Woodward-ClydeConsultants,1982JBENIOFFZONE
E-19TableE-3.SummaryofBoundaryFaultsandSignificantFeaturesDistancet3Fault(F)(miles)fromFaultwithFeatureorLinea-LengthDevi1RecentNo.t1FeatureNamet2ment(L)(miles)CanyonWatanaDisplacementBOUNDARYFAULTSAD5-1CastleMountainF2957165YesFaultHB4-1DenaliFaultF13584043YesBenioffZoneF4345640Yes(Interp1ate)BenioffZoneF463831Yes(Intraplate)WATANASIGNIFICANTFEATURESKC4-1TalkeetnaThrustF78164NoKD3-3SusitnaFeatureL95162NoKD3-7WatanaRiverL31220NoKD4-27FinsFeatureF2230NoDEVILCANYONSIGNIFICANTFEATURESKC5-5L124.519NoKD5-2F0.83.524NoKD5-3L513.614NoKD5-9L2.5124NoKD5-12L14.51.517NoKD5-42L30.522NoKD5-43L1.5024NoKD5-44L210.323NoKD5-45L19.50.835Not1Alpha-numericcodenumberisbasedon:(a)afirstletterdesignationforthe1:250,000quadranglewherethefeatureislocated(A=Anchorage,H=Healy,K=TalkeetnaMountains);(b)theletterandnumberofthe1:63,380quadrangleatthemidpointofthefeature;and(c)anumberdesignatingtheorderofthefeature'srecognition.t2Featurenameisgivenifassigned.t3Distanceistheclosestapproachof thesurfacetraceofthefaultorlineament.Conversion:Toconvertmilestokilometers,multiplyby1.61.ModifiedfromWoodward-ClydeConsultants(1982).
WI Watana Site
____Glacial age boundary
o I Devil Canyon Site
m
I
No
Early Wisconsin surfaces 75.000 to
40,000 y.b.p.
Late Wisconsin surfaces 25,000 to
11.000 y.b.p.
Late Wisconsin surfaces 11,000 to 9,000 V,b.p
t
N·
~
y.b,p.is the abbreviation for years before present.
Glacial age boundaries are interpreted from morpho·
stratigraphic relationships and age dates.
o 10 20 Miles
~~I I I
o 10 20 Kilometers
.....Thrust fault.dotted where concealed,.1 sawteeth on upper plate
~~Pre-Wisconsin surfaces >100,000 y.b.p.
LEGEND
Key Fault and code number
Concealed shear zone or fault
..-
K05).2,..........lineament and code number
j
Y:-'"
"
'r,""",,~..,;.,,~,';~'~~~.,~"~'~;::~'1i;.~-'.'.:c.'.'~,:.;""11··~";''-''.>:>'!\",~N·',j.':1''•.~i\,'tf'-~'''''''f'a{~'''''''",•.JR?j.:·~l "'Im'V,,!>···'t···,·f",","~..I':'(,"'~~~U~;,,~f7":~;:'~~}'~,:'i
<;...~....".-
Figure E-6.Significant Features near the Watana (W)and Devil Canyon (D)Dam Sites.
[Source:Adapted from Woodward-Clyde Consultants,1982]
E-21TableE-4.SummaryofEarthquakeSourcesConsideredinGround-MotionStudiesMeanPeakGroundAcceleration(g)EarthquakeSourceMaximumCredibleEarthquake(magnitude)tlClosestApproachtoProposedDamSites(miles)DevilCanyonWatanaDevilCanyonWatanaCastleMountainFaultDenaliFaultBenioffZone(interp1ate)BenioffZone(intraplate)Detection-levelEarthquake7-1/288-1/27-1/2671405738<665434031<60.20.30.50.20.350.5t1ModifiedMercal1iScale.Conversion:Toconvertmilestokilometers,multiplyby1.61.Source:ModifiedfromWoodward-ClydeConsultants(1982).site.Theprobabilisticapproachmodelstheoccurrenceoftheseismiceventusinggeologicalandseismologicalsiteregioncharacteristicsandisdesignedtoprovideamorerealisticmodelofseismicgroundmotions.The·MCEsforeachseismicsourcearelistedinTableE-4.InformationontheMCEmagnitudesandtheproximityof thefaultfromtheproposedsiteswasalsousedtoestimatelevelsofearthquakegroundmotionsatthesites.Theseestimateswerebasedonanalysesofgroundmotionsrecordedduringpreviousearthquakesappropriatefortheconditionsofthesites.Attenuationrecordsforsubduction-zoneearthquakesinSouthAmericaandJapanwereusedtoevaluatetherelationshipofpotentialearthquakesoccurringontheBenioffzonesbeneaththesites.RecordingsfromCalifornianandotherwesternU.S.earthquakeswereusedtoevaluatetherelationshipforshallowfocuscrustalearthquakesoccurringontheCastleMountainfault,theDenalifault,andforthedetection-levelearthquakes.ThemeanattenuationrelationshipsforpeakgroundaccelerationfromtheBenioffinterp1ateregionandtheDenalifault(themostintensesourcesofgroundshakingfromMCEsof thefourpotentialsources),aswellasthedetection-leve1earthquakeare1istedforeachsiteinTableE-4.Asdiscussed,featuresinthevicinityoftheproposedWatanaandDevilCanyonsiteshavebeenjudgedeithernottobefaultsortobefaultswithoutrecentdisplacement.Asnoneofthesefeaturesareconsideredtobeseismicsources,noMCEhasbeenassignedtothevariousfeatures(Woodward-Clyde,1982).E.1.1.2LowerSusitnaRiverBasinE.i.1.2.1TopographyThelowerSusitnaRiverBasihisapartofthephysiographicregionknownastheCookIn1et-SusitnaLowland.Thislowlandisprimarilyabroad,relativelyflattogentlyrollingarea.ElevationsrangefromsealevelatthetidalflatsalongCookInletto500ft(150m)MSLwithlocalreliefrangingfrom50to250ft(15to75m).Thelowlandhastwobranchingarmswhichextendintothesurroundingruggedmountainranges--theMatanuskaValleyborderedbytheTalkeetnaMountainstothenorthandtheChugachMountainstothesouth,andtheSusitnaRiverValleyeastoftheAlaskaRange.TheSusitnaValleyextendsnorthfromthecenterofthelow-landsandoccupiesafloodplainwhichvariesfrom1to8mi(1to13km)inwidth.TheSusitnaRiver,abraided,glacier-fedstream,andtwoofitsmajortributaries,theChulitnaandYentnarivers,originateintheAlaskaRange.AtTyonek,theCookInletLowlandsextendapproximately25mi(40km)fromtheshoretothetidalrange.ThetopographyoftheSusitnaValleyisdominatedbyglacialfeaturessuchasgroundmorainestothewestoftheriveraswellasdrumlinfields,eskers,andkettles.Broadterracesandout-washplainsdominatethesouthernpartofthelowlandsandlowmoraineswithirregularrollingtosteepslopesaredominantintheeasternandnorthernpartsOf~~lO)'dandS~c.FluvialprocessescontinuetomodifyandincisetheglacialdepositsandsLama.ndterrace~ae'posTEs~~dre~'~'prevalentalongdrainageswestofCookInlet.Talusslopes,landsliscours,avalanchechutesandrockglaciersarepresentattheedgesofthevalley(Se1kregg1974;SchoephorsterandHinton,1973;Merritteta1.,1982a).
E-22Duetolowslopesandthenatureofthesubstrate,thelowlandremainspoorlydrained.Ponds,1akes,andmuskegsoccurthroughoutmostofthe1owlands.Irregularlyshaped,verypoorlydrainedmuskegsrangeinsizefromafewtoseveralthousandacres.Low-lyingtidalplainsasmuchas2mi(3km)widebordertheCookInlet(SchoephorsterandHinton,1973).E.l.1.2.2GeologyBEDROCKGEOLOGYThesubsurfacegeologyoftheSusitnaLowlandsisrelativelyunexploredand,asaresult,thestructureandstratigraphyofthisareaarepoorlyunderstood(Merrittetal.,1982a).CookInletandmuchofthelowerSusitnaBasinoccupiesastructuraltroughunderlainbyrocksofTertiaryageandmantledbyglacialdepositsofQuaternaryage.ThestratigraphyoftheSusitnaLowlandisdominatedbyathick,complex,weaklyconsolidatedTertiarycoal-bearingsedimentarysequenceofsandstone,siltstone,claystone,andconglomeratesknownastheKenaiGroup.NorthoftheCastleMountainfaulttheKenaiGroupisrelativelythin[typically2,000ft(600m)orless]andoverliesgraniticrocks;southofthefault,theKenaiGrouprangesfrom10,000to16,000ft(3,000to5,000m)inthicknessandoverliesolderTertiarysedimentaryrocksandMesozoicagedsedimentary,igneousandvolcanicrocks.RapidlateralandverticalchangesinthelithologyoftheKenaiGrouparecommon,andexposuresoftheserocksaregenerallyconfinedtothefoothillsoftheAlaskaRangeandtoisolated,usuallysteep,incised,andlargelyinaccessiblestreamcanyonwallswithinthelowlands(Merritteta1.,1982a,c).PaleozoicclasticandcarbonaterocksareexposedintheAlaskaRange.MesozoicandearlyTertiaryvolcanicandclasticrocks,locallyinterbeddedwithlimestone,makeupthebulkofthebeddedrocksintheChugachMountains.LargebatholithsofJurassic,Cretaceous,andTertiary-agegranodiorites,quartzmonzoniteandrelatedrocktypesinvadetheoldersedimentaryandvolcanicrocksintheTalkeetnaMountainsandAlaskaRange.SmallerplutonsarepresentintheChugachMountains(Cobb,1974).SURFICIALGEOLOGYThemajorityoftheSUSitJl.aaLowlandiscoveredwiththickdepositsofundifferentiatedPleistocene"~~~~~jJ)uvialunconsolidatedsedimentsrangingfromglacialtillandoutwash~~~gravelstoalluviumandbeachdeposits.Mostoftheareahasamantleofsiltywind-laiddepositsthatcontainlargequantitesofvolcanicash.Theloessrangesfromafewinchesto6ft(severalcentimetersto2m)inthickness.Depositsofgravelandsandonterracesandoutwashplainsaregenerallywellsortedandnearlyfreeoffinematerial.Morainaldepositsgenerallyconsistofpoorlysortedverygravellyandstonymaterial.Stratifieddepositsofsiltandfinesandthatrangefromafewinchesto6ft(severalcentimetersto2m)inthicknessovergraveldepositsarepresentonfloodplains.Thetidalplainsarepredominantlyclayey,andlaterallyextensiveproglaciallakedepositsthroughmuchofthesouthernlowlandsaresiltyandclayey.Mostmuskegsconsistofcoarse,extremelyacidpeatderivedfromsphagnummossandsedges(SchoephorsterandHinton,1973).Widelyscatteredareasofslumpandlandslidematerialcanbefoundthroughoutthelowland,especiallynearsteepstreamchannelsandmountainfoothills(Merrittetal.,1982a,c).E.1.1.2.3SoilsandPermafrostSpodosolicsoilsoccurthroughoutmuchoftheSusitnaLowlandinareasoflowrollingmorainesandnearlyleveltoundulatingoutwashplainsintet'spersedwithmanysmallpoorlydrainedmuskegsandlakes.Thesesoilsareprimarilywelldrainedandformedonathinmantleofsiltyloessoverthickdepositsofverygravellyglacialdrift.Inlowlyingareas,sphagnumpeatmossiscommonandonlowterracesandfloodplainsborderingstreams,soilsrangefromverygravellyclayloamtostratifiedsandandsiltloam.Ingeneral,thewell-drainedsoilsonthenearlyleveltorollinguplandsaresuitableforcultivationandhavefewuselimitations(Riegeretal.,1979).Approximately50%ofthesoilsinthisareaareclassifiedasarable(Selkregg,1974).BottomlandandterracesoilsoftheSusitnaandYentnariversaregenerallywelldrained,strati-fiedEntisolsoryoung,poorlyformedsoils.Althoughthesesoilshaveseverelimitationsforuseduetoflooding,highwatertablesandstreambankerosion,terracesoilsaresuitableforcultivationandcommercialtimberdevelopment.Accesstothesesoilsisoftendifficultbecausemanyareasareisolatedbymuskegsandfrequentlyfloodedland(Riegeretal.,1979).Histosolsordeep,wet,peatsoilsarepresentonthesouthernbankoftheYentnaRiveraswellasatthemouthoftheSusitnaRiver.Thesesoilshaveseverelimitationsforalmostallusesasaresultoftheirextremelyacidicnatureandhighwatertables(Riegeretal.,1979).
E-23Onthefootslopesandtheglaciatedandnonglaciatedhillsof theCookInlet,thedominantsoilsareInceptisolsorincompletelyformed,horizonlesssoils.Thesoilsaregenerallyformedinthelayerofvolcanicashoverlyingthegravellyglacialtill.Thewell-drainedsoilsaresuitableforrangeland,andwhereslopesaregentletomoderatecanbecultivated.Steepslopesandwetnessarethemajorlimitationstouseofthesesoils(Riegeretal.,1979).Althoughpermafrostisnotuncommononthe·northernportionoftheSusitnaLowland,thesouthernportionsofthelowlandneartheCookInletandalongtheSusitnaRiveraregenerallyfreeofpermafrost.Flankingtheseareasisazoneunderlainbyisolatedmassesofpermafrost.Dis-continuouspermafrostispresentattheedgeofthelowlandsnearthemountains(Merrittetal.,1982a).E.l.l.2.4MineralResourcesTheKenaiGroupstrataoftheCookInletBasinofSouthcentralAlaskacontainsubstantialreservesofsubbituminousandlignitecoalssuitableforsurfacemining.Thesecoalsareextremelylowinsulfurandfavorablylocatedwithrespecttopotentialmarkets.TotalcoalresourcesoftheCookInletBasin,includingdeepcoalseamsbeneathCookInlet,mayreach1.5x1012tons[1.4x1012metrictons(MT)].Becauseofgeographicandgeologicconstraints,theareasofcoalexposuresareseparatedfromoneanotherandtraditionallyhavebeendividedintofourprincipalcoalfields:Yentna,Beluga,Kenai,andMatanuska(Edgaretal.,1982).TheYentnaandBelugafieldscontainagoodgradeoflow-sulfur,lignitetosubbituminouscoalfromtheTertiaryKenaiGroup.Inthedrainageareasof theBelugaandChuitnarivers,con-ditionsarefavorableforsurfaceminingasthecoalseamsarethick(morethan50ft,or15m)nearthesurfaceandarerelativelyflat-lying(Edgaretal.,1982).IntheKenaifield,numerousthin,subbituminoustolignitecoalbeds[3to10ft(0.8to3m)thick]areinterbeddedwithsandstones,siltstones,andclaystones.Althoughoverburdenratiosarelowandcoalunitsareessentiallyflat,thethinnessof thecoalseamsinhibitscommercialdevelopment.ComplexfaultingandfoldingoftheMatanuskacoalfieldandcomparativelysmallcoalreserveshasincreasedtheexpenseanddifficultyinminingthebituminousandanthracitecoalsinthisfield(Edgaretal.,1982).TheCookInletBasinalsocontainsportionsoftwomajorsedimentarypetroleumprovinces--theMesozoicprovinceandCookInletTertiaryprovince.TheMesozoicprovinceconsistsofathickwedgeofmarinesedim~ntaryrocksofJurasicandCretaceousagethatextendsfromtheAlaskaPeninsulatotheMatanuskaValley.Theserockscontainmanyindicationsofpetroleum,includingsourcebeds,oilandgasseeps,andshowsintestwells.TheCookInletTertiaryprovinceconsistsofathickbasin-likesectionofnonmarineconglomerate,sandstoneshale,andcoalbetweentheAlaskaRangeandtheChugachMountains.Allofthepresentlyproducingoilandgasfieldsinthestatearelocatedintheserocksinthecentralpartofthebasin.Duetolimitedexploration,thetotalextentoftheseoilandgasresourcesisnotyetknown.TheSusitnaLowlandalsocontains1,825,350acres[738,870hectares(ha)]offuel-gradepeat,thesecondlargestsuchreserveinthestate(RawlinsonandHardy,1982).Smallamountsofgold,silver,andbasemetalshavebeenproducedfromtheupperChulitnaareaneartheAlaskaRailroad.InthesouthernAlaskaRange,metallicsulfidemineralsarecommoninandneargraniticplutons.Thereislarge-scaleproductionofgoldfromgold-bearingquartzveinsinthesouthernborderoftheTalkeetnabatholithintheWillowCreekareanearPalmer.PlacergolddepositshavealsobeenminedinthevicinityofYentnaandValdezcreekssincethelate19thCentury(Cobb,1974).OthermineralresourcesoftheareaincludeminoramountsofceramicclayandagriculturallimefromnearAnchorage,alittlegypsumfromSheepMountainintheupperMatanuskaValley,soap-stone(forcarving)fromnearPalmer,andlargeamountsofconstructionmaterialsalongrailroadandhighwayroutesnearAnchorage(Cobb,1974).E.l.l.2.5SeismicitySouthcentralAlaskaispartofavast,continuousseismicallyactivebeltthatcircumscribestheentirePacificOceanbasin.TheSouthcentralRegionisoneof themostseismicallyactiveareasinNorthAmerica,experiencingthousandsofshockseachyear.ThelowerSusitnaBasinfallswithinaregionwheredamageduetoseismiceventsisrankedasmajor.
E-24E.l.l.3PowerTransmissionLineCorridorsE.l.l.3.1TopographyWillow-to-AnchorageSegment.TheproposedWillow-to-AnchoragesegmentofthecQrridorextendsfromAnchorageacrossKnikArmmudflatstoPointMackenzie.ThecorridorcontinuesnorthfollowingtheElmendorfMoraineacrosslevelterrainandextensivewetlandsfromPointMackenzietoWillowviaRedShirtLake.AdetailedtopographicdescriptionofthelowerSusitnaRiverBasinwaspresentedaboveinSectionE.l.l.2.1.Healy-to-WillowSegment.ThecentralsectionoftheproposedtransmissionrouteasdescribedbyCommonwealthAssociates(1982)wouldextendnorthfromtheswampylowlandsoftheWillowsubsta-tion[200ft(60m)MSL]crosslowbedrock-coredhillsintothefloodplainsandgravelterracesofthebraidedTalkeetnaRiver[800ft(240m)MSL],proceedthroughthefoothillsoftheTalkeetnaMountains[1,500ft(460m)MSL],andcrossChunilnaCreek[950ft(290m)MSL].ThetransmissionlinewouldturnnortheastatLaneCreekandextendalongthebaseoftheTalkeetnaMountainsabovetheSusitnaRiver[3,300ft(1,000m)MSL]droppingsteeplytoGoldCreekvalley[950ft(290m)MSL].NorthofGoldCreekValley,theproposedroutewouldgraduallyrisefromanelevationof1,500ft(460m)MSL,followtheslopeneartheTalkeetnaMountains,thencrossthefloodplainandterracesoftheSusitnaRiver.Onthenorthernsideoftheriver,theproposedroutewouldtraversethetopofalow,mountainousarea,thendropintotheIndianRiverValley.BetweentheIndianRiverandChulitnaPass,therouteagainwouldfollowalongaslopenearthebaseofanothersegmentoftheTalkeetnaMountains[2,100ft(640m)MSL].Thecorridorthenwouldrisetoanelevationof2,200ft(670m)MSLnearthedeeplyincisedcanyonofHurricaneGulchacrosstalusslopes,alluvialfans,andmorainalsurfacesthatparalleltheChulitnaRiverValley.Thismorainalsurface,characterizedbyelongate,relativelyflat-toppedridges,iscontinuoustothenorthalmosttoCantwell.NorthofLittleHonoluluCreek[1,850ft(560m)MSL]theproposedroutewouldfollowtheglaciallyscouredBroadPassValleyoccupiedbytheChulitnaRiver,crosstheEastandMiddleForksoftheChulitnaRiver,andrisetoanelevationofapproximately2,200ft(670m)MSLatJackRiver.Thelinewouldcrossthewide,braidedfloodplainandextensiveterracesoftheJackRiver,climbtoanelevationof3,400ft(1,040m)MSLacrosstheReindeerHills,andthendroptothefloodplainoftheNenanaRiver[2,050ft(620m)MSL].FromtheNenanaRiver,theproposedroutewouldfollowalongthetalusslopeofPanoramaMountainsandthesteepandrockyridgetothenorth[2,000to2,400ft(610to740m)MSL].Aftercrossingtheridge,theroutewouldextendnorthwestthroughmoregentleslopesandcrossCarloCreek[2,200ft(670m)MSL]andarelativelyflatglacialtillplainsouthofthesmallfloodplainoftheYanertFork[1,700ft(520m)MSL].FromYanertForktheroutewouldfollowthebaseofMountFellows,risetoabout2,600ft(790m)MSLandturn northeasttocrossMontanaCreek.Theroutewouldcontinueatthiseleva-tion,crossingbelowtworockglaciersthroughaU-shapedglacialvalleytoMoodyCreek.Fromhere,theroutewouldbeonarelativelysteepslopeaboveMoodyCreekthatremainsfairlylevel,thenfluctuatesanddropstoabout1,700ft(520m)MSLatCopelandCreek.AfterleavingtheCopelandCreekareatheroutewouldriseto1,800ft(550m)MSL,traversealargeoutwashterracebetweenCopelandCreekandHealyCreek,anddescendtoapproximately1,300ft(400m)MSLneartheHealysubstation.Healy-to-FairbanksSegment.ThecorridorwouldfollowthenearlylevelfloodplainoftheNenanaRiverValleynorthwardfromHealy[elevation1,400ft(430m)MSL]throughthenorthernfoot-hillsoftheruggedAlaskaRange.Thefoothillsparallelthemainrangeandslopenorthwardacrossthelevel,coalescedoutwash-fansoftheAlaskaRangeandtheflatTanana-Kuskokwimlowlands[elevationsrangingfrom1,000ft(300m)MSLneartheAlaskaRangeto400ft(120m)MSLneartheTananaRiver].AftercrossingthemeanderingandbraidedTananaRivereastofNenana,thecorridorwouldparallelonexistingtransmissionlineroutethroughtheroundedridgesandgentlyslopinghillsoftheunglaciatedYukon-TananaUplandregion,followingtheflat,alluvium-flooredGoldstreamCreekValleytoEster[elevations350to600ft(l00to200m)MSL](FurbushandSchoephorster,1977;Cobb,1974).E.l.l.3.2GeologyBEDROCKGEOLOGYWi11ow-to-AnchorageSegment.BedrockalongtheWillow-to-Anchoragesegmentareaisdeeplyburiedbysurficialsediments.AdiscussionofthebedrockgeologypresentinthelowerSusitnaBasinispresentedinSectionE.l.l.2.2.Healy-to-WillowSegment.ThebedrockencounteredalongthecentralportionoftheproposedrouteparallelingtheIntertieishighlyfracturedandcloselyjointed,predominantlyasa
E-25resultofthestructuralcomplexityoftheAlaskaRangeandoffrostaction.Specificlitho-logieschangerapidlyandcanvarydrasticallywithin10ft(3m)inanydirectionoftheline.AnalysisofthebedrockalongtheIntertieroutewasconductedbyCommonwealthAssociates(1982).BedrockrockexposuresbecomecommonnorthofChunilnaCreekbetweentheTalkeetnafoothillsandmountains.Bedrockinthisareaisgenerallyahard,closelyjointed,thinlybeddedargillitewithquartzveins.ApproachingGoldCreek,bedrockisexposedatthesurface,mantledbyrubbleformedbyfrost-shatteringofbedrock.Thebedrockconsistsofargilliteinterbeddedwithslateandgraywacke,whichisthinlybedded,verycloselyjointed,andcontainsquartzveinsandminorslickensidesurfaces.BetweenGoldCreekandJackRiver,bedrockconsistingofhighlyfracturedargilliteorshaleisexposedprimarilyincreekgulliesorrivervalleys.CoaloutcropsatCoalCreeksouthofJackRiver.Metamorphosedsedimentaryrocks,thecoreoftheReindeerHillsnorthofJackRiver,aswellasthinlybeddedargillite,chert,minorconglomerates,andlimestones,outcropinstreamgulliesandoccasionallyatthesurfaceofthehills.Theserocksaretypicallyhighlyfractured,moderatelytoseverelyweathered,andheavilyslickensided.InthenorthernportionoftheReindeerHills,bedrockcomposedofrhyoliteanddaciteisalsofound.SteeptalusslopesandexposedbedrockoccurinthePanoramaMountains.Bedrockishighlyfractured,verycloselyjointed,andveryslickensidedasaresultoftheproximityoftheMcKinleyStrandoftheDenaliFault.FewbedrockoutcropsarenotedbetweenCarloCreekandYanertForkexceptalongstreamvalleys.NorthofYanertForkmorebedrockisexposedalongthebaseofMountFellows.Thisbedrockconsistsofwelltomoderatelywellconsolidatedsand-stones,conglomerates,siltstones,andminoramountsofcoalthathavebeenintrudedinplacesbymoderatelyhard,moderatelyfractured,andheavilyslickensidedbasaltanddiabasedikes.AbovetheelevationoftheIntertierouteonMountFellows,volcanic-typebedrockisexposed.AtMontanaandMoodyCreek,gr:aniteandhighlyfracturedandfoliatedmicaceousquartziticschistareexposed.Thegraniticbedrockhasformedveryopen,blockytalusdeposits,whiletalusformedfromtheschistcontainsmanyfines.Duetosteepverticaljointsintheschist,steepexposedrockfaceshaveformedalongtheMoodyCreekvalley.MoreschisticbedrockisexposedalongthesouthernsideofHealyCreek.Healy-to-FairbanksSegment.Thebedrockalongthissegmentincludestwopre-Cenozoicmetamor-phosedschistformationsandpoorlyconsolidatedTertiarycontinentalformat~,--~~QL~.unconformityseparatestheschistsandthecontinentalformations.ThePrec~metasedimentaryBirchCreekschistispresentintheNenanaRivergorgesouthofHealYandbetweenFairbanksandtheTownofNenana.TheyoungerTotatlanikaschistformationconsistsofrhyoliteflowsandtuffsandout~ropsnearWindyCreekeastofClearandintheSlateCreekdrainagewestoftheNenanaRiver(R&MConsultants,1981).Poorlyconsolidated,sandstone,claystone,subbituminousandlignitecoalunitsoutcropbetweenHealyandLigniteCreek.Individualcoalbedsupto40ft(12m)thickrepresentaresourcewithsignificantdevelopmentpotential.BetweenNenanaandHealythemostwidespreadbedrockunitistheNenanagravel,apoorlyconsolidated,easilyerodedsedimentaryconglomerate(R&MConsultants,1981;Cobb,1974).SURFICIALGEOLOGYWi11ow-to-AnchorageSegment.FromPointMacKenzienorthtowardWi11ow,theproposedtrans-missionlinerouteroughlyfollowstheprominentElmendorfMoraine,whichformedduringtheLateWisconsi,nglacialperiodatthepointoffarthestadvanceoftheMatanuskaandKnikValleyglaciers.ProglaciallacustrinedepositscovermuchoftheCookInlet-SusitnaLowlandarea,andoutwashdepositscoverthewesternflankoftheElmendorfMoraine.LacustrinedepositsoftheproglaciallakehavenotbeenmappedwithintheprojectcorridorbutarepresentnearTalkeetnaandinterfingerwithoutwashanddeltaicdepositswestoftheprojectarea(R&MConsultants,1981).LargemudflatsoccupymuchoftheCookInletandKnikArmarea,andthickorganicdepositsarepresentinpoorlydrainedareas.FurtherdescriptionsofthesurficialdepositsintheSusitnaLowlandarepresentedinSectionE.1.1.2.2.Healy-to-WillowSegment.Thesurficialgeologyalongthisportionoftheproposedroute,asinmuchofAlaska,ischaracterizedbyagreatvarietyofterraintypesoccurringoverarelativelyshortdistance.Thetypeofgeologicmaterialspresentcanchangerapidlyalongashortdistancebothlaterallyandwithdepth,particularlywherethereisanirregularbedrocksurface,asiscommoninglaciatedterrain.Iftherouteweretobechangedevenslightly,thematerialtypesencounteredcouldbesignificantlydifferentfromthosedescribedbyCommonwealthAssociates(1982).IntheswampylowlandsimmediatelynorthoftheWillowsubstation,surficialpeatdepositsoverlyinggravelarecommon.Furthernorth,gravelandtilldepositsupto30ft(9m)thick
E-26predominate.Astherouteproceedsthroughthefoothi11softheTa1keetnaMountains,grave1depositsthinandformamantleoverthefoothills.Peatdepositsoccurinthelowlandsbetweenthehills.WithintheTalkeetnaMountainsbetweenChunilnaCreekandGoldCreek,lessthan10ft(3m)ofgravel,talus,andpeatarefoundinthevalleysbetweenthebedrockridges.NorthofGoldCreek,theroutecrossestheSusitnaRiverfloodplainsandterraces.Tillandgraveldepositsgreaterthan30ft(9m)thickarepresentbetweenGoldCreekandChulitnaPass[1.400ft(430m)MSL].WithintheChulitnaRiverValleytalusslopes,alluvialfans,andmorainalsurfacedepositsarepresent.Irregularkettle-likegraveldepositsoverliethebedrocknorthofHurricaneGulch.IntheBroadPassValley,theroutecrossesalluvialfan,groundmoraine,lake,slopewash,talus,floodplain,andswampdeposits.Verydense,clayey,silty,gravellysandorsandygravel,cobb1eytillisthepredominantmateria1typeinthisarea,andtillandgrave1depositsaremorethan30ft(9m)thick.ThickgraveldepositsarealsopresentinthefloodplainsoftheJackandNenanarivers.TalusandgraveldepositsoverliebedrockinboththeReindeerHillsandPanoramaMountains.NortheastofCarloCreekthingraveldepositscoverthebedrock,andthetalusconesrangefromopen,large,angularblockstoangularblocksinafine-grainedmatrix.NorthtoYanertFork,theproposedroutecrossesaflatglacialtillplainconsistingofdensetillsgreaterthan30ft(9m)thickandtill-mantledhillsofoutwashgravelandoccasionaldepositsoflakeclay.TwoinactiverockglaciersarepresentontheslopesabovetheroutebetweenMontanaandMoodyCreek.Talusandalluvialfandepositsoverliebedrockinthisregion.FromCopelandCreektoHealytheroutetransversesalargeoutwashterrace.ModeratelytopoorlyconsolidatedgravelsandsandstonesoftheHealyCreekformationextendundertheoutwashterrace.Morainaldepositstrendalongthesouthernedgeoftheoutwashterrace.Graveldepositsinexcessof30ft(9m)thickarefoundwithinthissegmentoftheroute.Healy-to-FairbanksSegment.Extensive,well-sortedfloodplainterraceandalluvialfandeposits,aswellascolluviumandsolifluctiondeposits,covertheNenanaRiverValleys.TheTanana-KuskokwimLowlandsnorthoftheAlaskaRangearealmostexclusivelycoveredbyalluvialfandeposits.TheYukon-TananaUplandsnorthoftheTananaRiverarecoveredbysiltyandsandymicaceousloessdepositsderivedchieflyfromtheoutwashplainssouthoftheTananaRiver.Thethicknessofthismantleofloessrangesfrom1ft(0.3m)onhighridgesto200ft(60m)onthelowhillsneartheTananaRiver.Muchoftheoriginalloesshasbeenerodedfromsteeperslopesandhasaccumulatedonthelowerslopesandinnarrowuplandvalleys.Lensesoforganicmaterialoccurthroughouttheredepositedsilt.E.1.1.3.3SoilsandPermafrostWillow-to-AnchorageSegment.Thesoilsalongthisportion oftheproposedcorridorareclassi-fiedasSpodsols,specifically,TypicCryorthods-SphagnicBorofibrists[501,504and505(seeTableE-1)].Thesesoilsusuallyhaveathicksurfacematofpartiallydecomposedorganiclitteroveragraymineralhorizon(Riegeretal.,1979).Althoughtypicallydifficulttoworkandlowinnaturalfertility,goodagriculturalsoilshavebeenidentifiedinthecorridor.Approximately50%ofthesoilsinthisareamaybeclassifiedasarable(Selkregg,1974).FromPointMacKenzienorthtoWillow,soilsalongthetransmissioncorridorhaveformedonorganic-coveredoutwashdeposits,oldertill,outwash,ablationtill,andfluvialdeltaandfloodplaindepositsthathaveahigherosionpotential.Thefrostheavepotentialisconsideredextremeonlyforthefluvialdeltadeposits;theliquefactionpotentialforthesesoilsishigh,whileslopestabilityisverylow.Allothersoilshavemoderatetohighslopestabilitiesandmoderatetolowliquefactionpotentials(R&MConsultants,1981).PermafrostisgenerallyabsentinthissegmentoftheproposedCorridor.Healy-to-WillowSegment.NorthofWillowtojustnorthofCantwellthroughtheSusitnaandChulitnarivervalleys,soilsaregenerallyclassifiedaswell-drainedSpodsols.Specifically,TypicCryorthods-SphagnicBorafibrists(501)predominatebetweenWillowandjustsouthofCurry;HumicCryorthods(510)betweenCurryandBroadPass,andPergelicCryorthods-HisticPergelicCryaquepts(5015)betweenBroadPassandCantwell(seeTableE-1).Thesesoilsaregenerallyformedongravellyglacialdeposits,terraces,andoutwashplainscoveredbyvaryingthicknessesofsiltyloessorvolcanicash.Exceptforwell-drainedsoilstothesouth,thesesoilsaretypicallyunsuitedforcultivationbutmaybeusedforgrazing.Highwatertables,periodicflooding,steepslopes,poorstability,lowpermeabilities,andstoninessseverelylimitthepotentialuseofthesesoils(Riegeretal.,1979).IntheNenanaRivervalleynorthtoHealy,soilsareprimarilyclassifiedasInceptisolsorpoorlyformed,horizonlesssoils.Tothesouth,thesesoilsareformedinverygravellycol-luvialmaterialweatheredfromlocalbedrock.Theyrangeft'omwelltopoorlydrainedandare
E-27generallyshallowandunsuitedforcultivation.Tothenorth,thesoilshaveformedonloess-covered,gravellyandsandyalluvialdeposits,arewelltomoderatelywelldrained,andarepotentiallysuitedforcultivation(Riegeretal.,1979).Muchofthecentralportionofthecorridorisunderlainbydiscontinuouspermafrost(Selkregg,1974).Permafrostismorecommontowardthenorthernsectionofthecorridorathigherelevationsandinpoorlydrainedsediments.Healy-to-FairbanksSegment.ThesoilstypicallyfoundwithintheHealy-to-FairbankssegmentoftheproposedtransmissioncorridorareclassifiedasInceptisols.Poorlydrained[HisticPergelicCryaquepts-TypicCryofluventsassociations(IQ3)(seeTableE-1)JunderlainbypermafrostarepresentonthelowerpartsoftheTanana-NenanaRiverfloodplains.Ontheslightlyhighernaturallevees,soilsarewelldrainedandsuitableforforagecropsandhardyvegetables.Permafrostisoftendeeporabsentinthesewell-drainedsoils.Discontinuouspermafrostunder-liesmuchofthecorridor.Permafrostgenerallyunderliesmostofthefloodplains,alluvialfans,drainagewaysofuplands,andthenorth-facingslopes,butisabsentonsteeplyslopingsouth-facinghillsides(Riegeretal.,1963).Fromnorth oftheAlaskaRangefoothillstoFairbanksandintheNenanaRiverValleynorthofHealy,theproposedtransmissioncorridorcrossesTypicCryochrepts-AericCryaqueptssoilassoci-ations(lR10)formedonalluvialfanoutwashandterraceandfloodplaindeposits.NorthoftheTananaRiver,AlficCryochrepts-HisticPergelicCryaquepts(IR14)soilsassociationshavebeenformedoneolianloessdeposits,aswellasoncolluviumandloessoverlyingbedrock.Allbutthesoilsformedontheoutwashdepositshaveahightomoderateerosionpotential.Thefrostheavepotentialishighforsiltysoilsformedoneolianloessandsiltyalluvialfandeposits,butlowformorecoarse-grainedsoils(R&MConsultants,1981).E.1.1.3.4MineralResourcesWi11ow-to-AnchorageSegment.Adetaileddiscussionoftheminera1resourcesintheLowerSusitnaBasinispresentedinSectionE.1.1.2.4.Healy-to-WillowSegment.AdetaileddiscussionofthemineralresourcesintheupperandmiddleSusitnaBasinispresentedinSectionE.1.1.1.4.Healy-to-FairbanksSegment.TheregionthroughwhichtheHealy-to-Fairbankssegmentofthetransmissionlinecorridorwouldpassisidentifiedasametalprovinceforgold,tine,tungsten,zinc,1ead,antimonyandsilver(Se1kregg,1977).Severa1lodeandplacerdepositsconsistingofgoldwithsubordinatesilverandantimonyoreshavebeenlocatedinquartzveinsandminer-alizedzonesinthePrecambrianandPaleozoicschistsandintheTertiaryNenanagravel.Thisareahasbeenasmallbutsteady,producerofplacergoldsince1904(Cobb,1974).TheFairbanksareaisrankedasamlneralizedareaprimarilyforgold,silver,antimonyandtungsten(Selkregg,1977).Mostofthelodesareconcentratedwithin25mi(40km)ofFairbanks,thegoldloadsbeingprimarilynearthegraniticplutonsatPedroandGilmoredomesnortheastofFairbanksandattheEsterdomewestofthecity.TheFairbanksareaisalsotheleadingproducerofplacergoldinthestate,producingover7,650,000ounces[240;000kilograms(kg)Jsince1902(Cobb,1974).ExtensivedepositsofTertiarycoalarepresentintheNenanaBasin.Thesubbituminouscoalbedshavebeenfoldedandfaultedintoaseriesofsmallerbasins(JarvisCreek,HealyCreek,Tatlanika,HoodRiver,Suntrana,LigniteCreek,Teklanika,etc.)andvaryinthicknessfromafewinchestomorethan60ft(18m)(Edgaretal.,1982).TheonlymajorcurrentcoalmineinAlaska,theUsibelliCoalMinenearHealy,producedapproximately800,000tons(730,000MT)ofcoalbysurfacemining(AlaskaDept.ofNaturalResources,1982).Totaloriginalresourcesinbedsexceeding2.5ft(0.8m)inthicknessandbeneathlessthan1,000ft(300m)ofoverburdenareestimatedat4.79milliontons(4.35millionMT)(Cobb,1974).E.1.1.3.5SeismicitySEISMICFEATURESWillow-to-AnchorageSegment.TheWillow-to-AnchoragesegmentcrossestheCastleMountainfaultsystem,whichhasamaximumcredibleearthquakeof7.4magnitude,andoverliestheAleutianTrench-ArcMegathrust,whichhasapotentialseismicityofmagnitude8.5to8.7(R&MConsul-tants,1981).Healy-to-WillowSegment.TheseismicfeaturesaffectingtheHealy-to-WillowareaaresimilartothosediscussedinSectionE.1.1.1.5.Healy-to-FairbanksSegment.TheHealy-to-Fairbanksareahasahighlyactiveseismichistorythatisnotrelatedtoknownsurfacefaults.TwoareasofknownseismicactivityoccurwithinthevicinityofClear-AndersonandFairbanks-NorthPole.TheDenalifault(maximumcredibleearthquakeof8.5magnitude)isafewmilessouthofHealy,perpendiculartotheHealy-to-Fairbankscorridor.AnotherfaultofuncertainactivityhasbeenlocatedbetweenHealyandLignite(R&MConsultants~1981).
E-28Certainareasalongtheproposedtransmissionroutesmaybeunderlainbysoilsthatarepoten-tiallysusceptibletoseismicallyinducedgroundfailure,suchasliquefactionandlandsliding,duringmoderatetolargeearthquakes.Areasidentifiedashavingthepotentialforseismicallyinducedlandslidesinclude(1)areaswithpreviouslandslidesandslumps,(2)riversandstreamvalleyswithsteepslopesandoverhangingpromontories,and(3)areaswithgroundfracturingonslopesaboveriversandstreamvalleys.Areasidentifiedashavingapotentialforseismicallyinducedliquefactionincludefloodplaindepositsalongthemarginsofriversandstreams,aswel1asareasunderlainbyglacialdeposits,particularlykettlesanddepositswithstandingornear-surfacewater(Woodward-Clyde,1982).SEISMICPROBABILITIESAccordingtoa1982seismicreport(Woodward-Clyde,1982),seismicallyinducedliquefactionandlandslidesareprobableduringmoderatetolargeearthquakes.TheprobabilityofsucheventsoccurringwithintheregionarediscussedinSectionsE.l.l.l.5andE.l.l.2.5.E.l.2SusitnaDevelopmentAlternativesE.l.2.1AlternativeDamLocationsandDesignsE.l.2.1.1WatanaI-DevilCanyonDescriptionsofthetopography,geology,soils,mineralresources,andseismicityofthesetwositesarepresentedinSectionE.l.l.1.E.l.2.1.2WatanaI-ModifiedHighDevilCanyonDescriptionsofthetopography,geology,soils,mineralresourcesandseismicityoftheWatanaIsitearethesameasthosepresentedinSectionE.l.l.1.TheModifiedHighDevilCanyonalter-nativesiteislocatedabout4mi(6km)westoftheconfluenceofDevilCreekandtheSusitnaRiverwithinthesteep-sidedDevilCanyonsectionoftheSusitnaRiver.AdescriptionoftheregionaltopographyinthevicinityofthealternativesiteispresentedinSectionE.l.l.l.l,andadescriptionoftheregionalgeologyispresentedinAppendixE.l.l.l.2.TheHighDevilCanyonisunderlainbyCretaceousargillitesandgraywackesaswellasTertiarybiotitegrano-dioritesandvolcanicrocks.Thebedrocknearthesiteisgenerallycoveredbysolifluctionfloodplainandterracedeposits,aswellasablationandbasaltills,alluvialfans,andcollu-vium(AcresAmerican,undated).SoilswithintherivervalleyareprimarilyclassifiedasSpodsols,specificallyHumicCryorthods(SOlO)(seeTableE.l)andhaveathicksurfacematofpartiallydecomposedorganiclitteroveragraymineralhorizon.Thesesoilsaretypicallydifficulttoworkandgenerallyhavelownaturalfertility.NorthoftheSusitnaRiverValley,PergelicCryorthods-HisticPergelicCryaquepts(SOI6)arepresent.AthigherelevationssouthoftheSusitnaRiverValley,Incepti-solsoryoung,incompletelyformedsoils,specificallyPergelicCryumbrepts-RoughMountainousLand(IU3)arepresent(Riegeretal.,1979).Withinthisregion,thesoilsaregenerallyconsiderednonarableandsuitableonlyforgrazing.Slopesaregenerallysteeperthan12%,andsoilshaveamediumerosionpotential(Selkregg,1974).Permafrostinthisareaisdiscontinuous.Theminera1resourcesoftheentireupperandmiddleSusitnaBasinaredescribedinSec-tionE.l.l.l.4,andthepotentialforseismicactivitywithintheModifiedHighDevilCanyonsiteissimilartothatdescribedinSectionE.l.1.1.5.E.l.2.1.3WatanaI-ReregulatingDamThetopography,geology,soils,mineralresourcesandseismicitythatwouldbeaffectedbytheWatanaI-ReregulatingdamalternativeareidenticaltothosedescribedinSectionE.l.1.l.E.l.2.2AlternativeAccessRoutesThe18a1ternativeaccessroutesconformtothreegeneralcorridors:Corridor1:FromtheParksHighwaytotheWatanadamsiteviathenorthsideoftheSusitnaRiver;Corridor2:FromtheParksHighwaytotheWatanadamsiteviathesouthsideoftheSusitnaRiver;andCorridor3:FromtheDenaliHighwaytotheWatanadamsite.Environmentaldescriptionsofthesethreecorridorsarepresentedbelow.E.l.2.2.1TopographyCorridor1and2arelocatedadjacenttothesteep-sidedSusitnaRiverValleyontherelativelyflat-toppedhillsthatreachelevationsof2,000to3,000ft(600to900m)MSLsouthoftheriver(Corridor2)and3,000to4,000ft(900to1,200m)MSLnorthoftheriver(Corridor1).PortageandDevilcreeks,tributariestotheSusitnaRiver,cutsteep-sidedvalleysthroughthehillsinCorridor1.PrairieCreekcutsawide,gentlyslopingvalleythroughtheeastern
E-29portionofCorridor2.Numeroussmall,unconnected1akesarescatteredthroughoutbothcorridors.Corridor3islocatedinthebroad,relativelyflatvalleysofBrushkanaandDeadmancreeks.Elevationsvaryfromapproximately2,000ft(600m)MSLneartheconfluenceofDeadmanCreekandSusitnaRiverto5,500ft(1,700m)MSLatthecrestoftheisolatedhillslocatedwithinthevalley,to3,000ft(900m)MSLattheDenaliHighway.Small,unconnectedlakesarepresentthroughoutalllowareasofthisCorridor.E.l.2.2.2GeologyCorridors1and2aregenerallyunderlainbyTertiarybiotitegranodioritesandCretaceousargillitesandgraywackes.Thebedrockiscoveredbyablationandbasaltills;solifluction,floodplain,andterracedeposits;aswellasalluvialfansandcolluvium.Corridor3isunder-lainbyTertiaryschists,migmatites,andgranites,aswellasgranodiorites.Surficialdepositsincludebasalandablationtillsandorganic,ablation,colluvium,lacustrian,andsolifluctiondeposits(AcresAmerican,undated).E.l.2.2.3SoilsSoilsfoundthroughoutmuchofCorridors1,2,and3aregenerallyclassifiedasSpodsols.Specifically,HumicCryorthods(SI0)arepresentwithintheSusitnaRiverValley,andPergelicCryorthods-HisticPergelicCryaquepts(SOI5,SOI6)arepresentthroughoutmuchoftheremainingarea.Inceptisols,specificallyPergelicCryumbrepts-RoughMountainousLand(IU3),arepresentinthehighlandssouthoftheSusitnaRiverinCorridor2andRoughMountainousLands(RMl)arepresentinthenorthernmostsectionsofCorridor1.DescriptionsofthesesoilsandtheirlimitionsarepresentedinTableE-l.E.l.2.2.4MineralResourcesThemineralresourcesof theupperandmiddleSusitnaBasinaredescribedinSectionE.l.2.1.1.4.E.l.2.2.5SeismicGeologyThepotentialforseismicactivitywithintheareacoveredbythethreecorridorsisasdescribedinSectionE.l.l.l.5fortheupperandmiddleSusitnaBasin.E.l.2.3AlternativePowerTransmissionRoutesE.l.2.3.1TopographyWillow-to-AnchorageSegment.Withinthissegment,Corridor1and2(ADFCandAEFC)arelocatedwithinthelowerSusitnaRiverBasin.AtopographicdescriptionofthisareaispresentedinSectionE.l.l.2.1.Corridor3(ABC')extendsfromtheWillowsubstationalongtheedgeoftheTalkeetnaMountainsandtheLittleSusitnaRiverfloodplainacrosstheflatMatanuskaValleytoPalmer.SouthofPalmer,thecorridorcrossesthebraidedfloodplainsof theMatanuskaandKnikrivers.AtthebaseoftheChugachMountains,therouteextendssouthwesttowardsAnchorage,followingtheElmendorfMoraineattheedgeoftheKnikArmtidalflatsandlowlandsandthebaseoftheChugachMountains.Dams-to-Go1dCreekSegment.Thetopographyforthissegmentof thetransmissioncorridors,exceptforcorridorsectionsJHIandAHI,isasdescribedinSectionE.l.l.l.l.Corridorsec-tionJHIfollowstheDevilCreekValley[2,000ft(600m)MSL]inanortherlydirectionthroughvariouscreekvalleysandwaterdividesbetweenrugged,rockyhills[elevationsbetween4,000and5,500ft(1,200and1,700m)MSL]towardstheJackRiverValley.FollowingthefloodplainoftheJackRiver,segmentJHIjoinstheproposedIntertiejustsouthofSummitLakeinBroadPass.CorridorsegmentAHJfollowstheTsusenaCreekValleythroughsimilartopographytowardstheJackRiverValley.Healy-to-WillowSegment.Thetopographyofthissegmentof thetransmissioncorridorisdes-cribedinSectionE.l.l.3.1.Healy-to-FairbanksSegment.FourcorridorswereproposedfortheHealy-to-Fairbankssegment:Corridor1(ABC),Corridor2(ABDC),CorridOI'3(AEDC),andCorridor4(AEF).Botheasterncorridors(1and2)followtheNenanaRiverValleynorthwardthroughthenorthernfoothillsoftheAlaskaRangebeforeproceedingnorthwardandnortheastwardacrossthecoalescedoutwashfansoftheAlaskaRangeandtheflatTanana-KuskokwimLowlands.Corridor1parallelsanexistingtransmissionlineroutethroughtheroundedridgesandgentlyslopinghillsof theYukonTananaUplandregionfollowingtheflat,alluvium-flooredGoldstreamCreekValleytoEster.Corridor2bypassesthehillytopographyoftheuplandregionbycrossingthebraidedTananaRiverchannelandproceedingnorthtoEsterthroughasmallseriesofdrainagedivides.
E-30Corridors3and4bothfollowtheHealyCreekandWoodRiverValleysthroughthenorthernfoot-hillsoftheAlaskaRange.ThecorridorroutesseparatenorthoftheJapanHillsintheTanana-KuskokwimLowlandsandproceednorthacrosstheleveltopographytoEsterandFairbanks.E.l.2.3.2GeologyWil1ow-to-AnchorageSegment.AdescriptionofthebedrockandsurficialgeologyoftheCookInletandLowerSusitnaBasinapplicabletotheWi11ow-to-AnchorageSegmentispresentedinSectionE.l.l.2.2.Dams-to-GoldCreekSegment.Tertiarybiotitegranodioritesschists,migmatites,andgranites,aswe11asCretaceousgraywackesandargi11ites,under1iemostofthissegment.Extensivesurficialdepositsoverliemuchoftheregion.Thesedepositsincludefloodplain,solifluctiondeposits,colluvium,basalandablationtill.Organicdepositsarealsopresentinpoorlydrainedareas.Healy-to-Wil1owSegment.ThebedrockandsurficialgeologyofthissegmentofthetransmissioncorridoraredescribedinSectionE.1.1.3.2.Healy-to-FairbanksSegment.MississippianAge,metamorphosed,volcanicandsedimentaryrocksunderliethenorthernfoothillsoftheAlaskaRangeinthevicinityofCorridors3and4.Extensive,we11-sortedf1oodp1ain,terrace,andalluvia1fandepositscovertheNenanaRiverValleyandtheTanana-KuskokwimLowland.NorthoftheTananaRiver,thick,valleybottom,eoliansiltandsanddepositsarealsopresent.LatePrecambrianandearlyPaleozoic,highlymetamorphosed,clasticrocksunderlietheYukon-TananaUplands(Selkregg,1977).E.l.2.3.3SoilsWillow-to-AnchorageSegment.Spodso1icsoils,specificallyTypicCryorthents-SphagnicBorofi-brists(SOl,S04,S05),occurthroughoutmuchoftheWi11ow-to-Anchoragesegment.ThesesoilsarelistedinTableE-5andadescriptionandtheirlimitationsareoutlinedinTableE-1.Althoughtypicallydifficulttoworkandlowinnaturalfertility,goodagriculturalsoilshavebeenidentifiedinthevicinityofCorridor2(ADFC).Approximately50%ofthesoilsinthisareamaybeclassifiedasarable(Se1kregg,1974).Entiso1s,oryoung,poorlyformedsoils,specificallyTypicCryofluvents-TypicCryaquepts(EF1)andTypicCryorthents(E01)arepresentintheMatanuskaandKnikRiverfloodplainsinthevicinityofCorridor3(ABC').Permafrostisgenerallyabsentinthisarea.Dams-to-Go1dCreekSegment.ThesoilsfoundinthisareasdescribedinSectionLl.l.1.3.RoughMountainousLand(RMl)(seeTableE-l)ispresentwithintheCorridorsJHIandAHI.Thisareaisgenerallyunderlainbydiscontinuouspermafrost.Hea1y-to-Wil10wSegment.ThesoilsoftheHea1y-to-Wi110wSegmentofthetransmissioncorridoraredescribedinSectionE.l.l.3.3.Hea1y-to-FairbanksSegment.ThesoilswithintheHea1y-to-FairbankstransmissionsegmentareclassifiedasInceptiso1sorincompletelyformed,horizonlesssoils.AlthoughgenerallyabsentalongthenorthernflankoftheAlaskaRange,discontinuouspermafrostunderliesmostoftheTanana-KuskokwinLowland.ModeratelythicktothinpermafrostispresentnorthoftheTananaRiver(Se1kregg,1977).E.l.2.3.4MineralResourcesWi110w-to-AnchorageSegment.ThemineralresourcesofthelowerSusitnaBasinaredescribedinSectionE.l.l.2.4.Dams-to-Go1dCreekandHea1y-to-Wi11owSegments.Theminera1resourcesoftheseareasaredescribedinSectionE.l.l.l.4.Healy-to-FairbanksSegment.TheHealy-to-Fairbankssegment;sidentifiedasmetalprovinceforgold,tin,tungsten,zinc,lead,antimony,andsilver.SeveralloadandplacerdepositshavebeenlocatednorthofHealyandintheFairbanksarea.TheFairbanksareaisrankedasamineralizedareaprimarilyforgold,silver,antimony,andtungstenandistheleadingp1acer-producingdistrictinAlaska(Se1kregg,1977).E.l.2.3.5SeismicGeologyThepotentialforseismicactivitywithintheIt/illow-to-Anchol'age,Dams-to-Go1dCreek,andHealy-to-Wi1lowsegmentsissimilartothatdescribedinSectionE.1.1.1.5fortheupperandmiddleSusitnaBasin.TheHea1y-to-Fairbankssegmentliesatthenorthernedgeofavast,continuous,seismicallyactivebeltthatcircumscribesthePacificOcean.ThepotentialfordamagetostructuresduringearthquakesintheInteriorRegionisconsideredmajor(Selkregg,1977)(seeSec.E.l.l.3.5).
Table E-5.Soils Along the Proposed and Alternative Transmission Line Segments
Corridor Segments
Willow to Anchorage AB BC'ADF AEF FC
Willow to near Palmer Palmer-E01;Knik Arm-EF,
-S04,Palmer E01 south of Eklutna to
north of Anchorage SOS;
Anchorage-S04
Willow-S04;south Near lower Susitna Near F-S04;
of Willow to F-S01 River-SOS;Remainder Near C-S01
-S04
Dams to Gold Creek AB
Segment
SOlS
Healy to Fairbanks AB
Segment
- -- - - - -- - -- --- -- - -- -- -- -- - - -- - -- ----
BC CD BEC AJ JC CF AG AH H HJ
B,westward SOlO B-westward-S01S;A,westward-SOlS;SOlO SOlO Near A and Near A-SOlS;Mts.-RM1;Near J-S016;rt1
-SOlS;near between Band remainder,except along Denali mt.base-along hwy.mid elevations I
l0C-S010 C-IU3;near J-S016;near J-Hwy.-S01S;S016;mts.--SOlS -S017;mts.-f-'
C-S010 SOlO through mts.RM1 RM1
-S016
-- - -- -- - -- - --- -- - - - ---- - -- -- - - - --- --- - - - -- --- - -- --- --
BC BDC AE EDC EF
IR10 Near B,-IR10;
flats south of
Tanana River-IQ2;
Tanana River-IQ3;
Tanana River to
Ester-IR14
t 1 See Table E-1 for explanation of soil units.
Source:Rieger et al.(1979).
Near B-IR10;
remainder-IQ2
Near A-IR10;
mt.base-IQ2S;
mt.area-RM1;
near E-IR1
Near E-IR1;
between E and
open flats-IR10;
open fl ats-IQ2;
Tanana River-
IQ3;Ester-IR14
Near E-IR1;
south section of
fl ats-IR10;
fl ats-IQ2;
Fairbanks-IQ3
E-32E.1.2.4AlternativeBorrowSitesDescriptionsof thetopography,geology,soils,andmineralresourcesoftheprimaryandsecondaryborrowsitesarepresentedinSectionE.1.1.1.E.1.3Non-SusitnaGenerationAlternativesE.1.3.1Natura1-Gas-FiredGenerationScenarioUnderthenatura1-gas-firedgenerationscenario,eight200-MWcombined-cycleunitswouldbelocatedintheCookInletregion:threeonthelowerBelugaRiver,twoontheChuitnaRiver,twoonCookInletnearKenai,andonesoutheast ofAnchorageinTurnagainArm.Descriptionsofthetopography,geology,soils,mineralresources,andseismicpotentialforthesegeneralregionsarepresentedbelow.E.1.3.1.1Anchorage-KenaiPeninsulaRegionTOPOGRAPHYGlacialoutwashplainsoftheCookInletLowlandsextendsalongtheeasternshoreof theKenaiPeninsulafromtheKnikRivertoKatchemakBayalongtheedgeoftheKenaiandChugachmountainranges.WestofTurnagainArmintheAnchoragearea,thisoutwashplainisapproximately10mi(16km)wide;eastofTurnagainArm,theoutwashplainreachesamaximumwidthof45mi(72km)andisdottedbynumerouslakes.BothAnchorageandKenailieonthenorthwesternshoreoftheKenaiPeninsulaattheedgeoftheselowlands.TheKenaiMountainstothewestofTurnagainArmandtheChugachMountainstotheeastformthebackboneoftheKenaiPeninsula.Thetworangesareextremelyrugged,andpeaksreachamaximumelevationof6,600ft(2,000m)MSL.Atelevationsgreaterthan3,000ft(900m)MSL,glaciersandicefieldscovermuchofthetworanges.Severalglaciersextenddowntosealevel.EastandsouthofKatchemakBay,thecoastlineisruggedandsteep.GEOLOGYTheKenaiandChugachMountainsareunderlainbyMesozoicshales,graywackes,andvolcanicrocksthatareweaklymetamorphosedbutstronglydeformedandfaulted.Tertiarygraniticintrusionsoccurthroughouttheclasticbedrocks.Atthenortheasternbaseofthetwomountainranges,highlymodifiedglacialmorainesandassociateddrift,aswellasoutwashandvalleytraindeposits,arepresent.TheCookInletLowlandsareunderlainbyathicksequenceofcoal-bearingrocksofTertiaryAgethatoverliethicksequencesofMesozoicrocks.Thebedrockiscoveredbythick,unconsolidated,silt-richglaciolacustrine,glacial,andglaciofluvialdeposits.Well-sortedfloodplain,terrace,andalluvialfandepositsareassociatedwithmajorsteamchannels.SOILSThesoilsoftheCookInletLowlandsandtheKenaiPeninsulaareprimarilySpodsols,specificallyTypicCryorthods-SphagnicBorofibrists(SOl,S04,S05).Thesesoilsusuallyhaveathicksurfacematofpartiallydecomposedorganiclitteroveragraymineralhorizon.Spodsolsinthisregionaregenerallywell-drained,stronglyacid,loamysoils;50%ormoreofthesesoilsarearable.IntheKenai-ChugachMountainRanges,barerock(RM1)predominates,andsoilsaregenerallyabsent.Wherepresent,soilsaregenerallyclassifiedasEntisols,whicharepoorlyformed,thinsoils(Selkregg,1974;Riegeretal.,1979).TheKenaiPeninsulaisgenerallyfreeofpermafrost,althoughafewisolatedpatchesmaybepresentathigherelevations(Selkregg,1974).MINERALRESOURCESAlloftheCookInletLowlandsontheKenaiPeninsulaandintheAnchorageareaarelocatedwithintheCookInletTertiaryProvince,anareaidentifiedashavingahighpotentialforgasandoildevelopment(seeSec.1.4.3andFig.1-14),aswellascontainingknowndepositsoflignitetosubbituminouscoal.AdiscussionoftheestimatedcoalresourceoftheKenaicoalfieldispresentedinSection1.4.4.LimestoneofunknownqualityandclaysuitableforbrickmanufactureoccurintheCookInletLowlandswestofAnchorage.Thecentralspineof theKenaiPeninsulaisidentifiedasachromiumandcoppermineralizedareaandmetalprovince.Theoccurrenceofnickleandplatinuminthisareaisalsosuspected.Numerousgold,silver,lead,zinc,copper,andchromiumclaimshavebeenstakedneartheAnchorageandHomerareasonthepeninsula(Selkregg,1974).
E-33SEISMICPOTENTIALAlloftheKenaiPeninsulaandtheCookInletLowlandsarewithinaregionwherepotentialdamageduetoseismiceventsisrankedasmajor.TheepicenteroftheAlaskanearthquakeof1964waslocatedjusteastofAnchorageintheChugachMountains.E.1.3.1.2ChuitnaandLowerBelugaRivers·TOPOGRAPHYThelowerBelugaandChuitnariversprojectareasarelocatedonthelowlandsof thewesternportionofCookInlet.TheBelugaareaisadjacenttothebraidedriverchanneloftheLowerBelugaRiverandtheCookInlettidalplainsatelevationsrangingfromsealevelto200ft(60.m)MSL.Becauseoflowslopesandpoordrainage,numerousponds,lakes,andmuskegsoccurthroughoutmuchof thesitearea.TheproposedChuitnaprojectareaisboundedbythedeeplyincisedChuitnaRiverchannel[600ft(130m)MSL]tothenortheastandthebroad,flat,marshyfloodplainofNickolaiCreek[100ft(30m)MSL]tothesouthwest.Abroad,roundedmorainedottedbynumerouslakes,ponds,andmuskegsrisestoelevationsof1,100ft(340m)MSLbetweenthetwodrainagesystem.GEOLOGYTheCookInletlowlandsaregenerallyunderlainbytheKenaiGroup,athicksequenceofcoal-bearingsedimentaryrocksofTertiaryage.ThickdepositsofundifferentiatedPleistocenefluvial,glacial,orglaciofluvialunconsolidatedsediments,aswellasloessandvolcanicash,arepresentthroughouttheCookInletlowlands.FurtherdescriptionofthegeologyofthisregionispresentedinSectionE.1.1.2.2.SOILSInthelowlandsofthelowerBelugaRiverarea,Histosols,specificallySphagnicBorofibrists(HYl),arepresentinthemarshyareasneartheCookInlettidalflats.Spodsolicsoils,specificallyTypicCryorthods-SphagnicBorofibrists(SOl),occurneartheBelugaRiver.Incep-tisols,specificallyDrystricCryandepts-FluvaquenticBorohemists(lA15),predominateintheChuitnaarea(Riegeretal.,1979).Furtherdescriptionofthesesoiltypesandtheirlimita-tionstousearedescribedinTableE-1.Nopermafrostispresentintheseareas.MINERALRESOURCESThemineralresourcesofthisregionaredescribedinSectionE.1.1.2.4.SEISMICITYTheseismicpotentialforthesetwolocationsissimilartothatdescribedinSectionE.1.1.2.5fortheCookInletregion.E.1.3.2Coal-FiredGenerationScenarioUnderthecoal-firedgenerationscenario,three200-MWcoalunitswouldbelocatedatWillowandtwo200-MWcoalunitswouldbelocatedatNenana.Descriptionsofthetopography,geologysoilsandmineralresourcesforthesetwoareasarepresentedbelow.Additionally,ten70-MWcombus-tionturbineswou·ldbelocatedaroundtheCookInlet.Generaldescriptionsof thetopography,geology,soils,andmineralresourcesof theCookInletregionarepresentedinSectionsE.1.1.2andE.1.3.1.E.1.3.2.1WillowTOPOGRAPHYWillowissituatedintheflatalluvialplainofthelowerSusitnaRiverBasin(seeSec.E.1.1.2forregionaldescription)atanelevationofabout200ft(60m)MSL.NumerouslakesandpoorlydrainedmarshyareasarepresentinthisareaadjacenttotheextensivelybraidedSusitnaRiverchanne1.TotheeastofWi11ow,the1andrisesgentlytothebaseoftheTalkeetnaMountains.GEOLOGYAdetaileddescriptionofthegeologyofthelowerSusitnaRiverBasinispresentedinSec-tionE.1.1.2.TheWillowareaisgenerallyunderlainbysandyandgravellyalluvialmaterialsthatoverlieweaklyconsolidated,Tertiary,coal-bearingsedimentarysiltstones,claystones,andconglomeratesoftheKenaiGroup.
E-34SOILSSoilsintheWillowareaclosesttotheSusitnafloodplainarepredominantlyEntisols,spe-cificallyTypicCryofluvents-TypicCryaquepts(EF1)(seeTableE-1).Thesesoilsaregenerallyformedofwell-drained,stratified,waterlaidsedimentofvariablethicknessoverasubstratumofsand,gravel,andcobblestones.Floodedsoils,sloughs,andscatteredmuskegsoffibrouspeatalsooccurandseveralylimitaccessdevelopmentandintensiveuseofthesesoils(Riegereta1.,1979).OntheriverterraceseastoftheSusitnaRiverintheWillowarea,Spodosolicsoils,speci-ficallyTypicCryorthods-SphagnicBorofibrists(SOl)predominate.Wheredrainageisadequate,thesesoilsaresuitableforcultivationorforestryandhavefewlimitationsforroads,struc-tures,orotherintensiveuses(Riegereta1.,1979).PermafrostisabsentintheWi11owvicinity.MINERALRESOURCESThemineralresourcesof thelowerSusitnaBasinaredescribedinSectionE.1.1.2.SEISMICITYThepotentialforseismicactivityintheWillowareaissimilartothatdescribedforthelowerSusitnaBasin(Sec.E.1.1.2.5).E.1.3.2.2NenanaTOPOGRAPHYMostoftheNenanaprojectarealiestothesouthoftheTananaRiveronnearlylevelflood-plainsatanelevationofapproximately400ft(120m)MSLbetweentheunglaciatedYukon-TananaUplandtothenorthandtheoutwashplainsoftheglaciatedAlaskaRangetothesouth.NorthoftheTananaRiverneartheNenanaarea,roundedhillsandridgesrisetomorethan1,600ft(490m)MSL.AdescriptionoftheregionaltopographyispresentedinSectionE.1.1.3.1.GEOLOGYAdescriptionoftheregionalgeologyoftheNenanaareaispresentedinSectionE.1.1.3.2.TheareasouthoftheTananaRiverisunderlainbygravellyalluvialdepositsandTertiaryNenanagravel,apoorlyconsolidatedsedimentaryconglomerate.NorthoftheTananaRiver,PrecambrianmetasedimentaryBirchCreekschistunderliestheroundedhillswhicharemantledbyvaryingthicknessesofsiltymicaceousloess(Riegereta1.,1979;R&MConsultants,1981).SOILSWithinthefloodplainsoftheTananaRiveranditstributaries,wetInceptisols,specificallyHisticPerlagicCryaquepts-TypicCryofluvents(IQ3),arepresent.Onthelowerportionsofthefloodplain,thesesoilsarepoorlydrained,arefrequentlyflooded,andareunderlainbyshallowpermafrost.Awayfromthefloodplains,well-drainedorganic-richInceptisols,specificallyAlfieCryochrepts-HisticPergelicCryaquepts(IR14),occur.Thewell-drainedandmoderatelywelldrainedsoilsinthisareaarepotentiallysuitableforcultivationorforestryandhavefewlimitationsforintensiveuse(seeTableE-1).Thepoorlydrainedsoils,floodedandshal-lowsoils,andsoilswithpermafrostinthisareahaveseverelimitationsforconstructionandaregenerallynotsuitableforcultivation(Riegeretal.,1979).Thetotalareasuitableforagriculturalpurposesinthisareaissmall(FurbushandSchoephorster,1977).MINERALRESOURCESTheminera1resourcesoftheregionaredescribedinSectionE.1.1.3.4fortheHealy-to-Fairbankssegmentoftheproposedtransmissioncorridor.SEISMICITYThepotentialforseismicactivitywithinthevicinityoftheNenanaSiteissimilartothatdescribedfortheHealy-to-Fairbankstransmissionlinesegment(Sec.E.1.1.3.5).E.1.3.3CombinedHydro-ThermalGenerationScenarioE.1.3.3.1JohnsonTOPOGRAPHYTheJohnsonalternativesiteislocatedintheTanana-KuskokwinLowlandneartheconfluenceoftheTananaRiverandtheJohnsonRiver.TheheadwatersoftheJohnsonRiverareintheglacier
E-35onthenorthslopeofMt.Hayes[9,860ft(3,000m)MSL]oftheAlaskaRange.Flowingnorththroughaglaciated"U"-shapedvalley,theJohnsonRiverbraidstowardthebroadTananaValley[elevation2,000ft(610m)MSL].TheTananaValleyisborderedbytheAlaskaRangetothesouthandtherounded,gentleridgesandslopesoftheYukon-TananaUplandtothenorth.GEOLOGYLatePrecambrian-earlyPaleozoic,highlymetamorphicclasticrockssuchasargillite,graywacke,phyllite,quartzite,andslateunderliethenorthernslopesoftheAlaskaRangeinthevicinityoftheJohnsonsite.Jurassic-toTertiary-agedgraniticintrusiveshavealsobeenfoundinthisarea.Thickalluvialdeposits,predominatelyextensivewell-sortedfloodplain,terrace,andalluvialfandeposits,covermuchoftheTananaRiverValleyanditstributaries.Northof theTananaRiver,bedrockiscoveredbythickeoliansiltandsanddeposits(Selkregg,1977).SEISMICLikeallareasinSouthcentralAlaska,theJohnsonareaislocatedinaregionofextremeseismicactivity.ThemajorfaultsystemintheareaistheDenaliFault,locatedintheAlaskaRangeabout40mi(60km)southwestoftheJohnsonsite.NorthoftheTananaRiveraseriesofnorth-east-southwesttrendingfaultsparalleltheShawCreekFault.Theactivityofthesefaultsisnotpresentlyknown,andthemaximumprobableearthquaketobeexpectedattheJohnsonsitehasnotbeenevaluated.SOILSSoilsformedintheJohnsonareaaretypicalofthoseformedinwet,coldclimates.IntheuplandareassurroundingtheJohnsonRiver,soilsaregenerallyabsentorpoorlyformedandareclassifiedasRoughMountainouslands(RM1).WithintheJohnsonandTananarivervalleys,soilsareprimarilyInceptisolsoryoung,incompletelyformedsoils,specificallyTypicCryochepts-HisticPerlagicCryaquepts(IR13)andAlfieCryocrepts-HisticPerlagicCryaquepts(IR14).Soilsinthisregionaretypicallywelldrainedandhaveathinlayerororganicmatterincorporatedintotheupperfewinchesofsoil.Thesesoilsaregenerallynonacidandhaveasiltyloam,loamyorgravellytexture(Riegeretal.,1979).Permafrostinthisregionisgenerallydiscontinuousandoccursprimarilyinareasofpredomi-nantlycoarse-grainedmaterial.Inareasoffine-graineddeposits,permafrostmaybemoderatelythick(Selkregg,1977).MINERALRESOURCESNometallicmineralresourceshavebeenidentifiedintheJohnsonsitearea.CoalispresentwestofthesiteintheJarvisCreekcoalfieldalongtheDeltaRiver.Sandandgraveldepositsarepresentnearthesite(Selkregg,1977).E.1.3.3.2KeetnaTOPOGRAPHYTheTalkeetnasiteislocatedalongthelowerhalfoftheTalkeetnaRiverintheCopperRiverPlateauareanorthwestoftheruggedTalkeetnaMountains.TheheadwatersoftheTalkeetnaRiverareintheglaciersoftheTalkeetnaMountains[elevation8,850ft(2,700m)MSL];theriverflowswesttothebroad,flatSusitnaRiverValley.Elevationsatthealternativesiteareabout1,000ft(300m)MSLintherivervalley,risingto3,000ft(900m)MSLinthebroadplateaustothenorth.GEOLOGYWell-sortedterracedepositsaregenerallypresentalongtheTalkeetnaRiverValleymargins,andfloodplaindepositsarelimitedinextent.Slightlytomoderatelymodifiedmoraineandassoci-ateddriftdepositscovermuchofthesitearea.JurassicandCretaceousslates,shales,gray-wackes,andconglomeratesthathavebeenintrudedbyJurassictoTertiarygraniticsunderlietheTalkeetnaRiverValleyandsurroundinghills(Selkregg,1974).TheTalkeetnaMountainsareunderlainbyalargegraniticbatholithintrudedintoMesozoicvolcanicandoldersedimentaryrocks.Tothenorth,nearthesitearea,theseolderrocksarecappedbyflat-lyingTertiarybasalt.~SEISMICTheKeetnaareaislocatedinanextremelyseismicallyactiveregion.TheprincipalfaultsystemofconcernintheareaistheDenaliFaultsystem,whichisabout60mi(100km)northof
E-36thesite.Numeroussubparallelfaultstrendingsouth-southwesttonorth-northeastarelocatedapproximately30mi(50km)northwestofthearea.Anotheractivefaultsystem,theCastleMountainFault,isapproximately50mi(80km)southoftheKeetnasite.NoestimateshavebeenmadeofmaximumprobableearthquakestobeexpectedattheKeetnasite.SOILSSOilSintheTalkeetnaRiverareaaretypicalofthosefoundonuplandsinareasofhighprecipi-tation[greaterthan15in(38cm)]andareclassifiedasSpodsols,specificallyHumicCryorthods(5010).PermafrostinTalkeetnaRiverValleyoccursasisolatedmasses,predominantlyinthefine-graineddeposits(Riegeretal.,1979).MINERALRESOURCESCopperhasbeenidentifiedinamineralizedareasoutheastofthesiteareaintheTalkeetnaMountains.Sandandgraveldepositshavealsobeennotedaspotentialresourcesfortheimme-diatearea(Selkregg,1974).E.1.3.3.3SnowTOPOGRAPHYTheSnowsiteislocatedintheKenaiMountainRangeintheKenaiPeninsulaontheSnowRivernearthesouthernendinletofKenaiLake.TheKenaiRangemountainsareextremelyruggedandreachamaximumelevationof6,600ft(2,000m)MSLnearthesite.Atelevationsgreaterthan3,000ft(900m)MSL,glaciersandicefieldscovermuchoftherange.TheSnowRiveroccupiesadeepgorgecutintothebedrockonthefloorofaglacialvalley.GEOLOGYGraywackesandslatesareexposedintheSnowRiverValley(ExhibitE,Vol.9,Chap.10,p.E-10-11).DeepwatersedimentarysequenceofmildlymetamorphiclateJurassic-toCretaceous-agegraywackes,siltstone,slat,sandstone,andconglomerateinterbeddedwithvolcanicbasaltsanddetritusarereportedforthearea(Selkregg,1974).SEISMICLocatedwithinoneof themostseismicallyactiveregionsoftheworld,theSnowsiteisalsolocatednearseveralknownfaultsystems:theBruinBayFaultsystem,theCastleMountainFault,andtheBorderRangeFaultsystem.Allthreefaultsfollowtheregional,arcuate,sub-linearstructurestrendingparalleltotheGulfofAlaska.TheBorderRangeFaultsystem,approximately35miles(55km)northwestofthesite,parallelsthenorthwesternedgeoftheKenaiMountains.TheCastleMountainFaultfollowingtheMatanuskaRiverValleyliesatleast80mi(130km)northandnortheastofthesite.TheBruinBayFaultsystemparallelingthenortherncoastofCookInletliesatleast80mi(130km)northwestandwestof thesite.NoestimationsofthemaximumprobableearthquaketobeexpectedattheSnowsitehavebeenmade.SOILSSoilswithintheSnowRiverValleyaretypicalofsoilsformingonuplandsinareasofhighprecipitation[greaterthan15in(38cm)]andareclassifiedasSpodsols,specificallyHumicCryorthods(5010).RoughMountainouslands(RM1)arepresentinthehigherelevationsadjacenttotherivervalley(Riegeretal.,1979).Generallytheprojectareaisfreeofpermafrost,althoughisolatedmassesmaybelocallypresentathigherelevations.MINERALRESOURCESTheSnowsitearealieswithinanareaidentifiedasagoldandcopper(andtoalesserextentlead,zinc,silver,andtungsten)metalprovince.Numerousloadandplacerdeposits,minesandprospectshavebeenreportedinthearea,generallyalongtheSnowRiverfromMoosePass,justnortheastofthesitearea,toSeward.Amineralizedareaofchromiumandcopperoreisalsopresentnorthwestof thearea(Selkregg,1974).E.1.3.3.4BrowneTOPOGRAPHYTheBrownesiteislocatedjustnorthofHealyalongtheNenanaRiverattheedgeof thenorthernfoothi115sectionoftheAlaskaRangetothesouthandtheTanana-KuskokwinLowlandtothenorth.
E-37Thenorthernfoothillsareunglaciated,flat-topped,east-trendingridges2,000to4,500ft(600to1,500m)MSLinelevationthatareseparatedbyrollinglowlandsandglaciatedvalleys.TheNenanaRiverflowsnorth,cuttingthroughtheseridgesbeforecrossingcoalescedoutwashfansfromtheAlaskanRangeintheTanana-KuskokwinLowland.BadlandsarecommonlyformedinareasofrapidlyerodingsoftTertiarysedimentsintheHealyarea.Elevationsnearthealternativesiteareapproximately2,000ft(600m)MSLalongtheNenanaRiverValleyand1,000ftMSL(300m)inthelowlandstothenorth(Selkregg,1977).GEOLOGYExtensive,well-sortedfloodplain,terrace,andalluvialfandeposits,aswellasmoderatelymodifiedmorainesandassociateddrift,arepresentwithintheNenanaRiverValley.MiddleTertiarycontinentaldepositsofsandstonesiltstone,conglomerate,claystone,andcoalarefoundwithinthenorthernfoothillsoftheAlaskaRange.ThenorthcentralflankoftheAlaskaRangeiscomposedofMississippianmetamorphosed,volcanicandsedimentaryrocks,aswellaslatePrecambrianandearlyPaleozoic,highlymetamorphosedclasticrockssuchasargillite,graywacke,phyllite,andquartzite(Selkregg,1977).SEISMICTheBrownesiteisinanextremelyactiveseismicregion.OneofthemajoractivefaultsystemsinthisregionofAlaska,theDenaliFaultanditsassociatedbranches,islocatedneartothesite.Trendingeast-west,twomajorbranchesofthisfaultsystempasstothesouthwithin25mi(40km)and45mi(70km)ofthearea.NoestimationsofmaximumprobableearthquakestobeexpectedattheBrownesitehavebeenmade.SOILSWithintheNenanaRiverValley,soilsareclassifiedasInceptisolsoryoung,incompletelyformedsoils,specificallyTypicCryochrepts-AericCryaquepts(IRI0)(Riegeretal.,1979).Permafrostinthisareaisdiscontinuous(Selkregg,1977).MINERALRESOURCESImmediatelytotheeastoftheNenanaRiver,severalloadandplacerdeposits,prospectsandmineshavebeenidentifiedwithinaregionofpossibleantimony,gold,andsilverresources.TheNenanacoalfieldcoversmuchoftheNenanaRiverValleyandtheareanorthandeastofHealy.SubbituminouscoaliscurrentlyminedattheUsibelliMines.Clayandcementmaterialshavealsobeenidentifiedaspotentialresourcesinthearea(Selkregg,1977).E.l.3.3.5LakeChakachamnaTOPOGRAPHYLakeChakachamnaislocatedinadeep,glaciatedvalleyinthesouthernmostregionoftheAlaskaRangejustnorthoftheChigmitMountains.Thelakeissurroundedonthreesidesbynumerousglaciersandhighruggedmountainpeaks.ThelakeisborderedatitseasternoutlettoChakachatnaRiverbymorainaldepositsassociatedwiththeBarrierGlacier.TheBarrierGlacieroriginatesinthesnowfieldshighonthesouthslopeofMt.Spurr[11,070ft(3,400m)MSL],anactivevolcano(Bechtel,1983).Elevationsintheimmediatearearangefrom1,200ft(370m)tosealevelintheCookInletlowlands40mi(64km)totheeast.Thelowlandsarebroad,flat(lessthan500ft,or150m,abovesealevel)andpoorlydrained.Theycontainmanythawlakesandmarshes.TheChakachatnaRiverflowsthroughanarrowcanyonwithinabroadervalleyboundedbyMt.SpurronthenorthandtheChigmitMountainsonthesouth.TheChigmitMountainstothesouthandtheTordrilloMountainstothenorthhavebeenrepeatedlyglaciatedandcontainmanysteepslopesandnearverticalcliffs.ThesouthernsideoftheChakachatnaRiverValleyconsistsofsteep,glaciated,graniticbedrockslopesthatrisecontinuouslyfromtherivertotheadjacentmountainpeaks.Thenorthslopeiscoveredbyvolcanic,glacial,andfluvialsediments(Bechtel,1983).TheMcArthurRivercanyonisanarrow,steep-walledglaciatedvalley.GEOLOGYThelate-Tertiaryand/orearly-QuaternaryvolcanicactivityatMt.Spurrcausedabuildupofandesiticlavaflows,pyroclasticsandvolcaniclasticsedimentsontopofagraniticmountainmassthatisexposedalongthesouthernvalleyoftheChakachatnaRiver.TheQuaternaryMt.Spurrvolcanicsal'e1argelyconfinedtoabroad,wedge-shapedareaboundedbyBarrierGlacier,BroganGlacier,andtheChakachatnaRiver.InterspersedvolcanicandglacialactivityinthisregionoccurredduringthePleistocene,withalternatingperiodsoferosionanddeposi-tion;asaresult,theChakachatnaValleyiscoveredbyacomplexofvolcanicandglacialdeposits.Glacialdepositsincludemoraines,largeareasofkameandkettledeposits,andglacier-marginallakedeposits(Bechtel,1983).
E-38ThevalleywallsoftheMcArthurRivercanyonconsistofgraniticbedrock.Acomplexofcross-cuttingjointsetsandshearzonesareexposedalongthevalleywalls.Thecharacterofthevalleyslopevarieswiththejointorientationandcharacter(Bechtel,1983).TheCookInletlowlandsarecoveredbyalluvialandtidalsand,siltandgravelofHoloceneage.Thelowlandsareunderlainbyathicksequenceofcoal-bearingrocksofTertiaryagethatrestonMesozoicrocksabout30,000ft(10,000m)thick.SEIsmcSouthernAlaskaisoneofthemostseismicallyactiveregionsoftheworld.EarthquakesinthisregiongenerallyoccuralongtheinterplateboundarybetweenthePacificlithosphericplateandtheNorthAmericanplatefromtheAlaskapanhandletoPrinceWilliamSoundandalongtheKenaiandAlaskanpeninsulastotheAleutianIslands.Movementsoftheseplateshasresultedinthedevelopmentofcomplexfaultingandfoldingoftheregionalgeologicunits.TheCastleMountainandBruinBayfaults(majorregionalfaults),aswellasseveralothersmallerfaults,havebeenmappedneartheChakachamnaLakearea.TheCastleMountainFaultpasseswithinlessthan1mi(1.6km)oftheprojectfacilitiesintheMcArthurRiverareaandwithin11mi(18km)ofChakachamnaLake.AmaximummagnitudeearthquakeofMS7.5hasbeenestimatedforthisfault(Bechtel,1983).Volcanic-inducedearthquakesarealsoconsideredapotentialseismicsourceforthisregion.SOILSSoilsformedwithintheLakeChakachamnaareaaretypicalofthosefoundinwet,coldclimatesinmountainousandrecentlyglaciatedterrain.Inthearea,soilsaregenerallyabsent(RM1).Inceptisolsoryoung,incompletelyformedsoilsresultingfromtheweatheringoralterationofparentmaterial,specificallyDrystricCryandepts(IA14,IA15)havedevelopedwithintheChakachatnaRivervalley(seeTableE-1).Mostofthesoilshavedevelopedonglacialdeposits;theremainderhavebeenformedonvolcanicsediments(Riegeretal.,1979).Isolatedmassesofpermafrostoccurinthisarea.MINERALRESOURCESTheChakachamnasiteisinanareaidentifiedasametalprovinceformolybdenum,copper,gold,silver,and,toalesserextent,leadandzinc.Noloadorplacermines,depositsorclaimshavebeenrecordedwithin20mi(30km)ofthesite(Selkregg,1974).ThesiteisinanareaofpotentialgeothermalenergyandisadjacenttotheligniteandsubbituminousBelugaCoalFields.ProducingoilandgaswellsarecommonnearTyonekandtheCookInletsouthofthearea(Selkregg,1974).E.1.3.3.6BelugaRiver,ChuitnaRiver,NenanaandAnchorageDescriptionsofthetopography,geology,soils,andmineralresourcesofthelowerBelugaRiver,theChuitnaRivet',andtheAnchorageenvironsarepresentedinSectionE.1.3.1.Descriptionsofthetopography,geologysoilsandmineralresourcesfortheNenanaareaarepresentedinSec-tionE.1.3.2.E.2ENVIRONMENTALIMPACTE.2.1ProposedProjectE.2.1.1WatanaDevelopmentE.2.1.1.1ConstructionRESERVOIRSLOPEINSTABILITYDuringreservoirfilling,slopeinstabilitywithintheprojectedWatanaimpoundmentareawouldbegreatlyinfluencedbychangesinthegroundwaterregimeandthethawingofpermafrostsedi-ments.Asthereservoirlevelrises,thegroundwatertableintheconfiningslopewouldalsorise,increasingtheporepressureandseepageactingontheslopeanddecreasingslopesta-bility.Thawofpermafrostdepositsincontactwiththerisingreservoirwaterswoulddecreasethestabilityoflow-angleslopes,givingrisetosolifluction,skinflow,andbimodalflowfailures.SUbmergenceofslopesingranularmaterialmightalsoleadtoslumpingorslidingbeneaththereservoirlevel,causingincreasedsuspendedsedimentconcentrationsinlocalizedareasofthereservoir.Duringthefillingoperation,thereservoirshorelinewouldbeincontactwiththesteeperslopesoftheSusitnaRiverValleyforadistanceofabout16mi(26km)upstreamfromtheWatanadamsite.Thenorth-facingslopesofthisvalleybetweenthedamsiteandVeeCanyonwouldhaveahighpotentialforslopefailureduringfillingbecauseofthepresenceoffrozenbasalfill,deepoverburdenandthesteepslopes.Becauseofmorevariablegeologicandtopo-
E-39graphicconditionsonthesouth-facingslope,slopefailurewouldbemorelocalizedalongthisslope.UpstreamofVeeCanyon,theimpoundmentwouldbecontainedwithintheSusitnafloodplain,wherelesssteepslopesunderlainbypermafrostwouldbeencountered.Shallowrotationalandflowslidesmightbeexpectedintheseareasasaresultofpermafrostthawduringthefillingopera-tion.Slopefailureduringtheconstructionperiodgenerallywouldbeagradualprocessconfinedtothereservoirshoreline.Slopefailuresmightbeexpectedtoresultforthemostpartinminorvariationsinthetemporaryshorelineconfigurationandmightresultintemporaryincreasesinthesuspendedsedimentconcentrationsintheportionofthereservoiradjacenttotheslide.Theactualmagnitudeofthesefailureswoulddependonthenatureoftheslopematerialsandtheirdegreeofsaturation,dueinparttoclimaticconditionsandtherateofpermafrostthaw.Constructionactivitiesinvolvingthemovementofheavyequipmentneartheshorelinemightalsocauselocalizedacceleratedslopefailureasaresultofvehicle-inducedvibrationoroverloading.Useofexplosivesinthedevelopmentoftheborrowsitesmightalsotriggerlocalizedslumpinginnearbysaturatedmaterials.Becauseoftherelativelyslowandevenrateofreservoirfilling(threeyearstofilltonormalpoollevel),thepotentialforslopeinstabilityduringthefillingofthereservoirwouldbereducedandprobablylimitedtoshallowsurfaceflowsandsomelocalizedsliding.Manyoftheseslidesorflowswouldoccurunderwater,andalthoughtheywouldcontributetolocalizedsuspendedsedimentconcentrationsinthereservoir,theywouldnotdisturbsurroundingreservoirareas.Manyofthefailuresthatoccurredabovethereservoirlevelduringfillingmightbesubmergedasthereservoirlevelreachednormalpoollevel.Treerootsystemsthatwouldnotberemovedduringtheclearingofvegetationfromthereservoirwouldalsoacttostabilizethereservoirslopestosomedegree.Althoughtherootingdepthofmostvegetationintheareaisshallow,themattedtangleofrootswouldacttostabilizethesurfacesoilsuntilexcessporepressuresintheslopeshaddissipated.Areasaffectedbyhighexcessporepressureswouldbesubjecttorotationalslopefailuries,slumping,etc.,regardlessoftheexistenceofthissurfacemat,however.SEEPAGEThepermeabilitiesinthefoundationrockattheproposedWatanadamsitearenothigh[between3.3x10-6to3.3X10-3ft/s(1x10-6to1X10-3m/s)(ExhibitE,Vol.7,Chap.6,p.E-6-16)].Existingshearzonesqndjointsinthevicinityofthesitewouldbegroutedtodecreaseseepagelossesthroughandaroundthedam(seeSec.E.3).ThegreatestpotentialforseepageattheWatanadamsiteisexpectedtooccuralongtheWatanarelictchannel,especiallywithinthehighlypermeableunitsatdepthsof208to231ft(63to70m)and293to375ft(89to114m)(AcresAmerican,undated).Seepagealongthischannelwouldresultinlossofwaterfromthereservoir,aswellaspipinganderosionofmaterialsattheexitpointoftherelictchannelatTsusenaCreek.Becauseofthelongseepagepath[approximately7,000ft(2,100m)]andthe6%hydraulicgradient(AcresAmerican,undated),thepossibilityofseepageorpipingthroughtheburiedrelictchannelisatpresentconsideredremoteevenwithoutremedialmeasures.Furtherinvestigations,includ-ingadditionalboringsandgeophysicallogging,wouldbeconductedtoassessthechanneldeposits.Presentplanstomitigateanypipingorseepageproblemthatdevelopincludetheconstructionofanundergroundaditwithinterceptordrain(ExhibitE,Suppl.Information,Sec.6,Item9).AdditionalremedialmeasuresproposedbytheApplicanttocontrolseepageincludetheuseofarelativelyimperviousmaterialtoblankettheupstreamentranceoftherelictchannel,useofafilter-toedrainattherelictchannelexit,anddevelopmentofacutoffwallbygroutingofpermeablelayerswithinthechannel(ExhibitE,SJppl.Information,Sec.6,ItemNo.12).Allsuchmeasuresshouldbeeffectiveinreducingthepotentialforpipingandseepageintherelictchannel.Shouldthedecisionbemadetocontrolratherthanpreventunderseepage,anaturalspringsenvironmentwouldbecreatedattheexitoftherelictchannelinTsusenaCreek.Therateofseepageflowthroughtherelictchannelwouldbeinfluencedbytheeffectivenessofthemeasuresusedtocontrolseepage.Althoughsaturationofthechanneldepositsandthethawingofpermafrostwithinthesedepositsmightincreasethepotentialforliquefactionofthedeposits,theirhistorysuggeststhatthedepositsmaybeoverconsolidatedasaresultofrepeatedglacialloading(Harza-Ebasco,1983).Assuch,thepotentialforliquefactionofthesedepositsandthesubsequentdamagetotherimofthereservoirisbelievedtobesmall.Thelowseepagegradientandthelongseepagepathway[4to5mi(6to8km)]oftheFogLakeburiedchannel(ExhibitE,Vol.7,Chap.6,p.E-6-30)wouldreducethepotentialforseepageinthischannel.Furtherinvestigationofthischannelisrequiredtofullysubstantiatethisconclusion,however.
E-40Asaresultofincreasedhydrostaticheadorpressure,thepotentialforseepagethrougheithertherelictchannelsorthroughjointsorfracturesinthebedrockwouldincreaseasthereservoirfilledandwouldbemaximumwhenmaximumpoollevelwasreached.Shouldincreasedseepageinthedamfoundationdevelopduringimpoundment,undergroundgroutinggallerieswouldbecon-structedtofacilitateremedialgroutingactivities(ExhibitE,Vol.7,Chap.6,p.E-6-40).PERMAFROSTTHAWInadditiontoeffectsofpermafrostthawingonslopestability,majorengineeringproblemsarisewherepermafrostoccursinpoorlydrained,fine-grainedsediments.Thawingoftheseice-richsedimentsproducesexcessivewetnessandundesiredplasticityandresultsinsettling,caving,liquefaction,subsidenceofgroundsurfaces,lossofbearingcapacity,andsedimentflows.Freezingofthisactivelayerinwinterresultsinfrostheavingofthegroundsurface(Ferriansetal.,1969).BecausepermafrostoccursthroughoutmuchoftheWatanaprojectarea,theconstructionfacili-ties,includingthetemporaryconstructioncampandvillage,theairstrip,andvarioussiteroads,wouldbeexpectedtoencounterpermafrost.Constructionofthesefacilitieswoulddisturbthethermalregimeofthesoilsandcouldcauseminorsedimentflowsordifferentialsettling.Thawingofpermafrostwouldresultinsettlementofsurfacefacilitiessuchastheconstructionvillagelocatedinanareaofdeepfrozenoverburdennorthofthedamsite.Sincethisareaisrelativelyflat,flowslideswouldbeconsideredunlikely.Tominimizetheextentofpermafrostthawandtherebylimittheextentofsettlementoftheconstructionfacilities,theApplicanthasproposedtousealargepadofgranularmaterialunderthetemporaryconstructioncampandvillagefacilitytoevenlydistributetheloadandtoinsulatethesubsoilfromtheheatedbuildings.Rigidpolystyreneinsulationmightalsobeusedtoincreasetheinsulationbaseunderthebuildings.Additionally,pilesupportswouldbeusedtosupportbuildingfoundationsandthermopileswouldbeinstalledtoremoveexcessheatinthesoilssurroundingandunderlyingallstructures(ExhibitE,Suppl.Information,Sec.6,p.6-15-4).Withproperuse,thesemitigationmeasureswouldbeeffectiveinminimizingpermafrostthawandsubsequentimpacts.Thermaldisturbanceofpermafrostsoilsunderthesiteroadsandairstripcouldbeexpectedasaresultofremovalofthevegetationandthedevelopmentanduseofthefacilitiesbyheavyequipment.Withsuchdisturbances,theamplitudeofseasonalfluctuationoftemperaturesmightbetwotothreetimesgreaterthanthatofnearbyundisturbedground.Furthermore,thegroundbeneaththedisturbedareawouldbecomemoresensitivetotherandomyear-to-yearclimaticvariations.Troughsofthawedgroundsusceptibletofrostheavingandsolifluctionwouldformbeneaththeroad(orairstrip)surface;waterfromthethawingpermafrostwouldflowalongthesetroughsuntilitwastrappedinadepression,creatingquagmireconditions,orescapedthroughexteriordrainageways.Withoutproperdrainage,thissurfacerunoffcouldcauseaddi-tionalpermafrostdepositstomelt.Withthawing,settlementwouldoccur;wherewaterwastrappedandrefrozen,frostheavingwouldresult.Insubsequentyears,freezingandthawingoftheactivelayerundertheroadwaywouldbeacceleratedinareaswherethemeltwaterhaddrainedaway(Ferriansetal.,1969).Wherepossible,theApplicantwouldattempttolocateallroadandsurfacefacilitiesonthawstablesoils.Wherethisisnotfeasible,roadwayswouldbeinsulatedthroughuseofgravelpadsorrigidsyntheticinsulationandthermopileswouldbeinstalledsoastocontrolthedegradationofthepermafrost(ExhibitE,Suppl.Information,Sec.6,Item15).PreviousexperienceinconstructingroadsandotherfacilitiesinareasofpermafrostinAlaskaindicatethefeasibilityofsuchactivities(Ferriansetal.,1969).RESERVOIR-INDUCEDSEISMICITYAreservoir-inducedseismicity(RIS)eventisdefinedasanaturallyoccurringseismiceventtriggeredbytheincrementalincreaseinstressintheearth'scrustassociatedwiththeimpound-mentofareservoir.TheepicentersofRISeventsoccurwithinthelimitedareaaffectedbythereservoir'smassandporepressures,whichusuallycorrespondstotheareaunderlyingthesurfaceofthereservoir.Intheory,reservoirsareconsideredcapableoftriggeringanearlieroccurrenceofanearthquakeexpectedfortheregionpriortoreservoirconstruction,butaregenerallynotthoughttobecapableoftriggeringanearthquakeofamagnitudethatwouldexceedthatexpectedtooccurnaturallyinthearea.Adiscussionoftheimpactsrelatedtosuchnaturallyoccurringseismiceventsispresentedinthenextsubsection.Whenconsideredasonehydro1ogicentity,thecombinedWatana-DevilCanyonreservoircomp1exwouldbeamongthelargestanddeepestintheworld.Thesizeofreservoir,however,isnottheprimarydeterminingfactorinRIS,asmanyoftheworld'slargestreservoirshaveshownnochangeinseismicity,andafewrelativelysmallreservoirshaveproducedearthquakeactivity
E-41farinexcessofthatexpectedfortheseismichistoryfortheregion(SimpsonandNegmatullaev,1978).AnalysisoftheglobaloccurrenceofRISevents(Woodward-Clyde,1982)indicatesthatRISisinfluencedbyreservoirdepthandvolume,thetectonicstressesimmediatelybeneaththereservoir,therateofreservoirfilling,aswellastheexistingporepressuresandpermeabilitiesoftherockunderlyingthereservoir.InacomprehensiveandthoroughinvestigationcomparingtheproposedSusitnareservoircomplextosimilarreservoirselsewhere,Woodward-ClydeConsultants(1982)concludedthatthemeanlikelihoodofanRISearthquakewithinthe20-mi(32-km)beltoneithersideoftheproposedreservoiris0.46(onascaleof0to1)withastandarddeviationof0.22.TheassumptionsandconclusionsmadeintheanalysesofWoodward-ClydeConsultantsareconsideredtobevalidforthisanalysis.ModeratetolargeRISeventsgenerallyhavebeenfoundtooccuronlyalongfaultswithrecentdisplacementreference.Inthevicinityoftheproposedreservoircomplex,nosuchfaultshavebeenfoundtodate.Asaresult,the1ike1ihoodofanRISeventofmagnitude(M)>4iscon-sideredlowbyWoodward-ClydeConsultants(1982).BecauseofthepossibilitythaCfurtherfieldworkmayrevealtheexistenceinthisregionofafaultwithrecentdisplacement,however,aRISeventofmagnitude(M)6,themagnitudeofthedetection1eve1earthquakefortheregion(Woodward-Clyde,1982)sisconsideredpossibleforthisreservoirsystem.Soastoanalyzetheeffectsofreservoirfillingonthestressregimeof theimpoundmentarea,theAlaskanPowerAuthorityintendstoinstrumentthereservoirduringtheconstructionperiodforbaselinepurposesandwouldoperateasensitivemicroseismicnetworkduringandimmediatelyafterthereservoirfillingperiod(ExhibitE,Suppl.Responses,Sec6,Item8).BecausesuddenchangesinreservoirlevelsandrapidfillingofreservoirscorrelatepositivelywithincreasedRISactivity(SimpsonandNegmatullaev,1978)theApplicanthasproposedthattheWatanareservoirwouldbefilledslowlyandevenlyoverathree-yearperiod.ThisscheduleshouldbeeffectiveinreducingthelikelihoodofinducingRISevents.REGIONALSEISMICITYAdiscussionoftheseismicityof theproposedWatana-DevilCanyonprojectareaispresentedinSectionE.1.1.1.5.Earthquakeactivityintheprojectareawouldresultprimarilyinincreasingthemagnitudeoffailureinthepotentiallyunstableslopeswithinthereservoirarea.Earth-quakescouldalsotriggerliquefactionofvariousunconsolidateddepositswithintheWatanareservoirarea.ThethicksequenceoflacustrinematerialsoverlyingbasaltillsintheWatanaCreekdrainage(AcresAmerican,undated)areawouldbeespeciallysusceptibletoliquefactionduringearthquakes.Liquefactionoftheunconso1idatedmateria1swithintheWatanare1ictchannel(AcresAmerican;undated)isconsideredunlikely,however,becauseoftheassumeddegreeofconsolidationofthesesediments.EROSIONTodate,limitedinformationdescribingthecharacteristicsandthetypicalengineeringproper-tiesofthesoilsandsurficialsedimentsintheWatanaprojectareaisavailable.NodetailedsoilsurveyshavebeenconductedforthisareabytheSoilConservationService(Riegeretal.,1979),andpreliminaryinvestigationshavebeenrestrictedprimarilytoalarge-scalegeneralizedterrainevaluationoftheareabasedonlow-altitudeaerialphotographscollaboratedbyonlylimitedfieldchecks(AcresAmerican,undated:AppendixJ).Thislackoffieldinformationseverelyrestrictstheuseoftheterrainevaluationmapsforsite-specificanalysisofpotentialerosionimpactsresultingfromconstructionactivitiesintheWatanaprojectarea.Despitethislackofsubstantiatedsiteinformation,afewqualitativeassessmentsofthepoten-tialforsoilerosionimpactsaccompanyingconstructionactivitiescanbemade.Theseassess-wouldbesubjecttochangeshouldfieldinvestigationsnecessitatealterationsoftheexistingpreliminarydescriptionsofsoilswithintheprojectarea.1descriptionofthesoilswithintheprojectareaispresentedinSectionE.1.1.1.3.ofthesesoilsarethoughttohaveseverelimitationsforconstructionactivitiesasaresultofhighwatertables,periodicflooding,steepslopes,andpoorstability(Riegeretal.,BasedonthegeneralizedstudiesconductedtodatebytheApplicant,however,thesouth-facingslopesof theSusitnaValleywheremostoftheconstructionactivitywouldbelocatedareesssteepandthesoilsarebetterdrainedthanthenorth-facingslopes.theconstructionperiod,thedevelopmentofborrowsites,siteroads,theairstrip,theoncampandvillage,andalldam-relatedfeatureswouldresultinthelocalizeddis-ofsoilsandvegetationandsubsequentincreasederosionofsurfacesoils.Thepoten-alforerosionwouldbegreatestwhenrainfallwasheavyorduringspringsnowmeltconditions.sUbsequentrunofffromtheseeventscouldcausesheet,rill,orgullyerosion.Constructionfacilitiesonsteepslopescouldalsoresultinslopeandsoilinstabilities,increasedon,andsedimentation.
E-42Themovementofheavymachineryduringconstructionoperationsmightsubstantiallyimpactlocalareasofsoil.Suchmovementmightresultincompactionofsurfacesoilorremovalofuppersoillayers.Mechanicalcompactiongenerallyreducessoilproductivitybyreducingratesofwaterinfiltrationandpercolation,restrictingrootpenetration,andincreasingsurfacewaterrunofforponding.Excavationorbackfillactivitiesassociatedwithnumerousconstructionactivitiesmightalsochangesoilcharacteristicsbymixingthesoilprofile,bringingrockfragmentsorboulderstothesurface,interruptinginfiltrationanddrainage,aswellasincreasingerosion.Suchdis-turbancesmightcausereductionsinthesoilfertilityinthedisturbedareas.Suchactivitiesasroadconstruction,excavation,andclearingcouldalsoresultinalterationof1oca1drainagepatternsandsurfacewaterregimes.Blockageofdrainagepatternscouldresultinthewaterloggingofsoils,leadingtothedevelopmentofquagmires,thethawingofpermafrost,andincreasedsurfaceerosionofsoils.Clearingofvegetationduringconstructioncouldalterthethermalregimesofsoils,causingdeeper,earlierthawoffrozensoilsinsummerandearlierfreezeofsoilsinwinter.IncreasedhumanuseoftheWatanaprojectarea,especiallytheuseofoff-roadvehiclesinthesummer,wouldalsooccurduringtheconstructionperiod.Suchactivitieswoulddestroysurfacevegetationandsubsequentlyincreasesoildisturbanceanderosion.Theseeffectswouldbemostsevereinareasofpermafrostandtundravegetation.Toreducethepotentiallyadverseeffectsoftheseimpacts,theApplicanthasproposedtouseanumberofmitigativemeasurestoreducesoildisturbancesandsoilerosion.Theconstructioncampandvillagefacilitieswouldbelocatedongentlysloping,generallywell-drained,perma-frost-free,ablationtilldepositsnorthofthedamsite.Duringconstruction,thesesiteswouldbeclearedofvegetationandwouldbevulnerabletoerosionlossesduringperiodsofheavyprecipitationandsurfacerunoff.TheApplicanthasalsoattemptedtoreducevegetationclear-ingrequirements(andasaresultreducetheareaofdisturbedsoils)byminimizingthedimen-sionsoftheconstructioncampandvillageareas.Giventhegentle2%to3%slopesandthewell-drainedconditionofthesoil,however,soillossesduringsucheventswouldbeexpectedtobeminimal.Selectedareasofnaturalvegetationwouldalsobeleftundisturbedatthevillagesite.Theseareasandallareasleftinnaturalvegetationsurroundingtheclearedconstructionareawouldaidinfilteringoutortrappingthesoilerodedfromtheconstructionareabeforeitcouldreachanynearbywaterways.Erosioncontrolfortheconstructioncampandvillagesite,asforallconstructionoperations,wouldincludethedevelopmentofappropriatedrainagesystems,theplacementofrevetmentstoreduceflowvelocities,andtheuseofdesiltingponds.Protectivebarriersofbrushorfillwouldbeusedalongstreambankstocontrolincreasederosionresultingfromconstructionactivities(ExhibitE,Suppl.Information,Sec.6,p.6-15-5).Thesepracticesshouldbeeffec-tiveinkeepingerosionlossesfromconstructionareaswithinacceptablelevels.Useofheavyconstructionvehiclesinandaroundthecampandvillagesitesduringtheclearingandconstructionoperationswouldalsoresultinsoilcompaction,resultinglossesinsoilfertility.Topsoilfromtheadjacentdamsiteborrowareas,however,wouldbeusedbytheApplicanttoreclaimallsuchdisturbedareassurroundingthesite.Revegetationofthesedisturbedareaswouldreducetheerosionlossesintheseareas(seeAppendixJfordiscussionoftheexpectedeffectivenessofrevegetationpractices).Duringthedevelopmentoftheprojectborrowareas,theupper2to3ft(0.6to0.9m)ofsoilandorganicmatterwouldbestrippedandstockpiledforlateruseinreclaimingdisturbedprojectareasattheendoftheconstructionperiod(ExhibitE,Vol.7,Chap.6,p.E-6-38).Borrowsiteswouldbeexcavatedonlyasnecessary.Borrowsites0,F,andCandquarrysiteFwouldnotbefloodedbythereservoirandwouldeitherberegradedorreseededafteruseor,ifexca-vationissufficientlydeep,wouldbeconvertedtoponds.Duringtheprocessingofexcavatedrockandgravelfromtheborrowsitesandquarriesforuseindamconstruction,concreteaggregate,supportpadsforbuildings,andtemporaryserviceroads,largequantitiesofspoilmaterialswouldbeproduced.TheApplicantproposestodisposeofthesematerialswithintheimpoundmentarea.Exactlocationsofthesoildisposalareaswouldbedeterminedduringthedetailedengineeringdesignphase(ExhibitE,Vol.6A,Chap.3,p.E-3-267).Priortoreservoirfi11ing,temporaryconstructionbermsortemporarypitsaroundthespoilpi1eswouldbeusedtocontrolorcontaintheerosionoffines.Spoi1pileswauldalsobelocatedinareasoftheimpoundmentawayfromexpectedareasofturbulenceorhigh-ve1ocitycurrentssoastoreducethepotentia1forentrainmentofthefinesdudngreservoirfilling.A11temporarysiteroadswouldbegraded,recontoured,andseeded)fo11owingabandonment(ExhibitE,Vol.7,Chap.6,p.E-6-42).Wheresiteroadscrossareasofpermafrost,gravelpadsofsufficientthicknesstoinsulatetheroadswouldbeusedtocontrolthedegradationand
E-43subsequentfailureofthepermafrost(ExhibitE,Suppl.Information,Sec.6,Item15).Generallythesemeasuresshouldbeadequatetocontrolerosionduetoborrowsiteandroaddevelopment.FurthermitigationmeasuresthatshouldbeconsideredarediscussedinSection5.2.1.Immediatelypriortofillingofthereservoir,theApplicantproposestoclearlargetreesandshrubsfromtheportionofthereservoirtobeimpoundedduringthatconstructionyear.Whenpossible,clearingactivitieswouldbeconductedduringthewintersoastominimizesoillossesduringtheseactivities.Lowvegetationandorganicdebriscoveringtheunconsolidatedmaterialswouldnotbeintentionallyremovedduringtheclearingoperation,thusprovidingamatofstabilizingvegetationtoinhibitsoilerosion.Somedamagemightoccurtothismat,however,duetoheavyvehicletrafficduringtheclearingactivity(ExhibitE,Vol.6A,Chap.3,p.E-3-160).Becauseofthelargeareatobeaffectedbyvegetationclearingactivities(seeAppendixJ),theerosionlossesfromthisareamaybeexpectedtobesubtantial(althoughunquantifiable),despitethemeasurestocontrolerosionlosses.Increasedconcentrationsofsuspendedsedimentarelikelytobehighestinsurfacerunoffimmediatelyfollowingsiteclearingandpriortonaturalreestablishmentofvegetationintheclearedarea.Asreservoirfillingproceeded,however,theamountoftheclearedland,andthusthetotalquantityofsoilseroded,wouldbereduced.GEOLOGICALRESOURCESAtpresent,nomineralorfuelresourcesareknowntoexistwithintheWatanaprojectarea(seeSec.E.1.1.1.4).DevelopmentoftheWatanadamandassociatedfacilitieswouldrequiretheexcavationanduseofsubstantialrockandconstructionfillmaterialsfromtheprojectarea.Noneofthesematerialsisconsidereduniquetotheareaandisnotrequiredbycompetingdevelopments.Assuch,noadverseimpactstothegeologicalresourceswithintheWatanaprojectareaareexpectedduringtheconstructionperiod.Reservoirimpoundmentwouldresultinthefloodingof36,000acres(15,000ha)ofsoils.Thesesoilsarenotsuitableforagriculture.E.2.1.1.2OperationRESERVOIRSLOPEINSTABILITYWiththefillingoftheimpoundmentarea,slopeinstabilitywouldbeinfluencedprimarilybythelargeseasonaldrawdownofthereservoir[estimatedat100ft(30m)],thawingofthepermafrostsoils,reestablishmentofthegroundwaterregime,steepnessofthereservoirslopes,andthenatureoftheslopematerials.Theprimaryimpactswouldbeincreasedconcentrationsofsuspendedsedimentsintheareasadjacenttotheslopefailure,shorelineerosion,anddisturbanceofshorelinevegetation..The100-ft(30-m)drawdownzonealongthereservoiredgeshouldremainessentiallyunvegetated.Withoutvegetativecover,however,reservoirshorelinerecessionmightbeexpectedtocontinueuntilbedrockorgravel/cobble/bouldersubstrateswereexposed.Slopeinstabilityinthedraw-downzonewouldalsobeintensifiedbytheyearlyperiodicfreezing,thawing,saturation,anddesiccationofthesoilswithinthiszone.Afterthereservoirwasfilled,therelativewarmthofthereservoirwaterwouldcausepermafrostthawinadjacenthillsides,especiallythesouthernshoresoftheWatanareservoirwherethepermafrostlayeris200to300ft(60to90m)thick.AlthoughthearealextentsofslopeinstabilityalongtheWatanareservoirshorelinecannotbereliablyquantifiedinadvance,numerousareasofthereservoirwouldbeexpectedtobevulner-abletoslopefailure.The49-mi(78-km)reachalongthesouthernshoreoftheimpoundmentareabetweentheWatanadamsiteandtheOshetnaRiver/VeeCanyonareahasahighpotentialforflowsandshallowrotationalslidesbecauseofthepresenceofdeepfrozenbasaltill,relativelythickoverburden,andsteeperslopes.Similarly,a10-mi(16-km)reachfromtheheadwatersoftheWatanareservoirtotheOshetnaRiver/GooseCreekareawhichisunderlainbythickfrozensiltandclaydepositshasahighpotentialforslopefailure.Morevariablegeologicandtopographicconditionsonthenorthernshorewouldgiverisetothepotentialforavarietyofslopeconditionsinthisreachofthereservoir.A10-mi(16-km)reachalongthenorthernshoreofthereservoirbetweenWatanaCreekandthedamsitewhichisunderlainbyunconsolidatedglacialoutwashwithinthedrawdownzonewouldbeexpectedtoexperienceslopeinstabilityproblems.UpstreamofVeeCanyon,thereservoirwouldbeconfinedprimarilytothefloodplainoftheSusitnaRiver,andsmallrotationalslidesinareasunderlainbypermafrostwouldbeexpected.Shorelineerosionorbeachingwouldoccurprimarilyasaresultofwaveactionandthesloughingoroversteepeningofabackslope.Massfailuresneartheshorelinewouldprobablyresultinthecreationofnewbeachesalongthedisturbedsectionofreservoirshoreline.Mostoftheslopeswithintheproposedimpoundmentareawouldbetotallysubmerged.Approxi-mately16mi(26km)upstreamofthedamsite,thereservoirwouldinundatethesteeperslopesoftheSusitnaRiverValley,andthereservoirshorelinewouldbeincontactwiththelowslopesofthesurroundinguplandterrain.Intheseareaswherethereservoirshoresarelocatedabovethebreakinslope,instabilityproblemsI'/ouldbelessthanforareaswherereservoirshores
E-44abutsteeperslopes.Wherepermafrostunderliesthesegentlyslopingshorelines,however,flowslidescouldbeexpectedtooccurwithintheseflat-lyingslopesasaresultofpermafrostthaw.Basedonaerialphotographicinterpretationandlimitedfieldreconnaissance,theApplicanthascalculatedthatapproximately15,000acres(6,000haloflandadjacenttothereservoirshore-linemightbeaffectedtosomedegreebyeitherbeaching,flow,orblockslides(ExhibitE,Suppl.Information,Sec.6,Item7).Ofthistotal,approximately270acres(110haloflandoutsidetheWatanaprojectboundarymightbeaffectedbyslopefailureanderosionasaresultofthereservoirimpoundment(ExhibitE,Suppl.Information,Sec.6,Item10).ThemethodologyinvolvedinsuchcalculationsarethoughtbytheStafftobevalidforthisanalysis.Itisanticipatedthattheseslopefailureswouldbealong-termprogressiveactivityresultingprimarilyfromseasonalfluctuationsinthereservoirlevel,thethawingofpermafrost,andwaveactionattheshoreline.Thelengthoftimerequiredfortherestabilizationoftheslopesadjacenttothereservoirafterinundationisunknown.Withoutalteringthegivencharacter-isticsofthedamandreservoir,therewouldbenowaytoavoid,minimize,rectifyorreducetheimpactsresultingfromslopeinstability.SEEPAGEThepotentialforimpactsresultingfromseepagethroughandaroundtheWatanadamisdiscussedinSectionE.2.1.1.1.Asdiscussed,seepage impactswouldbemaximumwhenthereservoirwasatmaximumpoollevelandwoulddecreasesomewhatwithseasonaldrawdownofthereservoir.PERMAFROSTTHAWTheimpactsresultingfrompermafrostthawintheWatanaprojectareaduringtheconstructionphasearediscussedindetailinSectionE.2.1.1.1.Similarimpactsmightbeexpectedduringtheoperationphase.Thepermanentvillagewouldbelocatedinanarearelativelyfreeofpermafrostsoastopreventthedevelopmentoflong-termproblemsrelatedtopermafrostthaw.Iftheinsulationbaseplacedunderthebuildingsofthetemporarycampandvillagehadbeeneffectiveinpreventingpermafrostthaw,groundheavingshouldnotoccurwhentheheatedbuild-ingswereremovedattheendoftheconstructionperiod.RESERVOIR-INDUCEDSEISMICITYReservoir-inducedseismicity(RIS)isdescribedinSectionE.2.1.1.1.TheimpactsrelatedtoRISeventsduringtheoperationperiodwouldbesimilartothosedescribedinthesubsectiononSeismicImpacts.Afterimpoundmentofthereservoirwascompleted,variationsinthereservoirlevelresultingfromseasonaldrawdownsmightinduceRISevents.AlthoughsmallseasonaldrawdownswouldbeexpectedattheDevilCanyonreservoir,largeseasonaldrawdowns[100ft(30m)]wouldbeexpec-tedatWatanareservoirandmightincreasetheprobabilityofRISeventsinthearea.BecausetherateofseasonalfluctuationsinreservoirlevelshasnotbeenspecifiedtodatebytheApplicant,itisunclearwhethertheprobabilityofRISeventsresultingfromseasonalfluctua-tionsinthereservoirlevelduringoperationwouldbelessthantheprobabilityofRISeventsresultingfromreservoirfillingduringtheconstructionperiod.Inotherreservoirsaroundtheworld,however,thegreatestearthquakeactivityhasoccurredsoonafterthefillingofthereservoirandhasthengraduallydecreasedordisappearedwithtime(SimpsonandNegmatullaev,1978).REGIONALSEISMICITYTheseismicallyinducedimpactsexpectedfortheWatanareservoirareaduringtheoperationperiodaresimilartothosediscussedfortheconstructionperiod.EROSIONDuringtheoperationperiod,erosionwouldoccurprimarilyalongsiteroads,theairstrip,andinthevicinityofthepermanentvillage.AdetaileddiscussionofthenatureoftheseimpactsandmeasurestocontrolerosionallossesispresentedinSectionE.2.1.1.1.Manyoftheareassusceptibletoerosionduringtheconstructionperiod(e.g.,borrowsites,constructionroads,damfacilities,etc.)wouldeitherbefloodedbytheimpoundmentorwouldbecompletedpriortotheoperationperiodandthuswouldnotbesusceptib1eto furthererosion.Erosionlossesduringtheoperationperiodwouldbeexpectedtobesmallerthanduringtheconstructionphaseprimarilybecauseofthesmallerareaaffectedbysurfacefacilitiesandtheirrelatedactivities.Increaseduseofoff-roadvehiclesbythepublicduringthisperiod,however,couldincreaseerosionandsoildisturbances.Impactsrelatedtoshorelineerosionofthereservoiraredis-cussedaboveinSectionE.2.1.1.2.
E-45GEOLOGICALRESOURCESForthereasonsstatedinSectionE.2.1.1.1,thegeological resourcesof theWatanaprojectareawouldnotbeadverselyimpactedduringtheoperationperiod.E.2.1.2DevilCanyonDevelopmentE.2.1.2.1ConstructionRESERVOIRSLOPEINSTABILITYThenatureofslopeinstabilitiesthatwouldbeexpectedwithintheDevilCanyonreservoirduringthefillingofthereservoiraresimilarinnaturetothosediscussedinSectionE.2.1.1.1.Duringreservoirfillingoperations,similarareaswouldbeexpectedtobesusceptabletoslopeinstability.Thegeologicalcharacterofthisreservoirarea(e.g.,theexposureofstablebedrockalongthereservoirshores)wouldbefundamentalinreducingslopeinstabilityimpactsinthisreservoir.SEEPAGEBedrockpermeabi1itiesinthevicinityoftheDevilCanyondamsitearegenerallylowexceptinanumberofshearandfracturezones.Thepermeabilitiesofthesezonesdecreaseswithdepth,andgroutingwouldbeusedtofurtherreducethepotentialforseepagelossesthroughthesezones.FoundationpreparationandgroutingduringtheconstructionofthesaddledamacrosstheburiedchannelsouthofthedamsitewouldminimizeseepagefromtheDevilCanyonreservoirviathispathway.Remedialgroutingwouldbeusedtoreduceanyseepagesthatdevelopduringreser-voirimpoundment.PERMAFROSTTHAWAgeneraldiscussionoftheeffectsofpermafrostthawresultingfromconstructionactivitiesisgiveninSectionE.l.l.l.l.BasedonterrainunitmapspreparedfortheApplicant(AcresAmerican,Undated:AppendixJ),permafrostmightbepresentinthebasaltillsandorganicdepositsunderlyingtheproposedtemporarycampandvillagesitessouthoftheSusitnaRiverbetweenthedamsiteandPortageCreek.Preliminarysiteinvestigations,however,suggestthatnopermafrostispresent(AcresAmerican,undated).Shouldpermafrostbefoundinthesevicini-ties,vegetationclearingwouldprobablyresultinsufficientthawingofthesethinsedimentspriortoconstruction,therebyreducingtheimpactsrelatedtothethaw.TheApplicantproposestolocateallsiteroadssoastoavoid,whereverpossible,otherisolatedpocketsofpermafrostpresentintheDevilCanyonprojectarea.Wherepermafrostwasencountered,however,mitigationmeasuressuchasthosedescribedinSectionE.2.1.1.1wouldbeusedandshouldbeeffectiveinminimizingthedegradationof thepermafrost.Becauseof thelackofpermafrostinmuchof theDevilCanyonprojectarea,permafrost-relatedimpactsshouldbeminor.RESERVOIR-INDUCEDSEISMICITYThereservoir-inducedseismicimpactsexpectedforthecombinedWatana-DevilCanyonreservoircomplexduringtheconstructionperiodaredescribedinSectionE.1.1.1.1.REGIONALSEISMICITYAdiscussionoftheseismicityoftheproposedWatana-DevilCanyonprojectareaispresentedinSection3.1.1.2andSectionE.2.2.1.IntheDevilCanyonreservoirarea,earthquakeactivitywouldresultprimarilyinincreasedreservoirslopeinstability.Thepotentialforanearth-quake-inducedlandslidewouldbemostlikelyatthesiteofanoldlandslideonthesouthabut-mentatRiverMile175.Becausethe toeoftheslideislocatedabovethemaximumpooleleva-tion,itisunlikelythatthisslidewouldbereactivatedbynormalreservoirimpoundment.Triggeredbyanearthquake,however,amassslideinthisareacouldresultinthetemporaryblockageofriverflow.Thelimitedgeologic/geotechnicalinformationavailableforthisslidearea,however,precludesananalysisatthistimeofthepotentialseverityofimpactsresultingfromsuchaslide(specificallythepotentialmagnitudeoftheslide,theextentofupstreamfloodingthatmightbeexpectedduetoblockageofriverflow,theprobabilityofsuchaslide,etc.).EROSIONDuringtheconstructionperiod,thedevelopmentofborrow~reas,siteroads,t~econstructioncampandalldam-relatedfeatureswouldresultinlocalizeddisturbancesandsubsequenterosionofsurfacesoils.TheimpactsexpectedfortheseactivitieswithintheDevilCanyonandthemitigationmeasuresproposedtocontrolerosionlosseswouldbesimilartothosedescribedinSectionE.2.1.1.1.
E-46Becauseofthesteep,narrowconfigurationofDevilCanyon,thetotalareathatwouldbeclearedofvegetationpriortoreservoirimpoundmentisonly15%ofwhatwouldbeclearedfortheWatanareservoir.ThethinnessoftheoverburdenintheDevilCanyonreservoirareawouldfurtherreducethepotentialmagnitudeofcumulativeerosionlosseswithintheimpoundmentzone.Effec-tiveuseoftheproposedmitigationmeasuresshouldbesufficienttoreduceorcontrolerosionlosseswithintheDevilCanyonprojectarea.AdditionalmitigationmeasuresthatshouldbeconsideredforthisprojectaredescribedinSection5.3.GEOLOGICALRESOURCESAtpresent,nomineralorfuelresourcesareknowntoexistwithintheWatanaprojectarea(seeSec.E.1.1.1.4).DevelopmentoftheDevilCanyondamwouldrequiretheexcavationanduseofsubstantialrockandconstructionfillmaterialsfromthearea.Althoughcleansandandgraveldepositsarescarcethroughouttheprojectarea(AcresAmerican,undated),sufficientmaterialswouldbeavailablefromtheborrowandquarrypits.Noneofthesematerialswouldberequiredbycompetingdevelopments.Thus,noadverseimpactstothegeologicalresourceswithintheDevilCanyonprojectareawouldbeexpectedduringtheconstructionperiod.Floodingoftheimpoundmentareawouldresultinthelossofapproximately6,000acres(2,400ha)ofsoilsandrocks.Noneofthesoilswithintheimpoundmentareaareconsideredtobeagricul-turallysuitable.E.2.1.2.2OperationRESERVOIRSLOPEINSTABILITYConfinedentirelywithinthewallsofthepresentSusitnaRiverValley,theDevilCanyonreservoirwouldbedeepandnarrowandwouldhaveasmallseasonaldrawdown[about55ft(17m)J.IntheareaofDevilCanyonCreekanddownstream,thereservoirshorelinewouldbeincontactwithsteepbedrockcliffs,andslopeinstabilitywouldbeprimarilyduetosmallrockfallsresultingfromthefluctuationofthereservoirandgroundwatertableaccompaniedbyseasonalfrostheaving.UpstreamofDevilCanyonCreek,thepotentia1forbeachingandtoa1esserextentrotationalslides,bimodalflows,andsolifluctionwouldincreaseasthethicknessofunconsolidatedmaterialsalongthereservoirshorelineincreased.AnoldlandslideinthebasaltillonthesouthabutmentatRiverMile175mightbereactivatedasaresultofpermafrostthawandchangesinthegroundwaterregimeaccompanyingthecomp1etionofthereservoir inundation.However,becausethe toeofthisslideislocatedabovethemaximumpoolelevation,itisunlikelythattheslidewouldbereactivatedbynormalreservoirimpoundment(seeSec.E.2.1.2.1).Failureofthisslidemightextendbeyondtheprojectboundaries(ExhibitE,Suppl.Information,Sec.6,Item10).Basedonaerialphotographyinterpretationandlimitedfieldreconnaissance,theApplicanthascalculatedthatapproximately2,500acres(1,000ha)oflandadjacenttothereservoirshorelinemightbeaffectedtosomedegreebybeachingandtoamuchlesserextentbyfloworblockslides(ExhibitE,Suppl.Information,Sec.6,Item7).ThemethodologyusedincalculatingtheseareasisconsideredbytheStafftobevalidforthisanalysis.Thesefailureswouldbeantici-patedtobealong-termprogressiveactivitywithinthereservoirprojectboundaryarea.Thelengthoftimethatwouldberequiredfortheslopesadjacenttothereservoirtorestabilizeafterreservoirfillingisunknown.ThelowerestimatesoflanddisturbedbyslopefailureadjacenttotheDevilCanyonreservoirrelativetotheWatanareservoirreflectthelackofsufficientdepthsandextentofunconsolidatedmaterialsandthepresenceofstablebedrockconditionsalongtheDevilCanyonreservoirshoreline.SEEPAGEAsdiscussedinSectionE.2.1.1.1,seepagelosseswouldbemaximumwhenthemaximumpoollevelforthereservoirwasreached.SeepagelossesattheDevilCanyondamsitewouldbeexpectedtobecontrolledbygroutingandbythegenerallylowbedrockpermeabilities(seeSec.E.2.1.2.1).Asaresult,seepageimpactswouldbeexpectedtobeminimal.PERMAFROSTTHAWTheimpactsrelatedtopermafrostthawintheDevilCanyonprojectareaduringtheconstructionperiodarediscussedinSectionE.2.1.2.1.Similarimpactsmightbeexpectedduringtheopera-tionphase.Becauseoftheabsenceofpermafrost,removalofthetemporarycampandvillagestructureswouldnotdisturbthethermalregimeofthearea.RESERVOIR-INDUCEDSEISMICITYThereset'voir-inducedseismicimpactsthatwouldbeexpectedforthecombinedWatana-DevilCanyonreservoirareaduringtheoperationperiodaredescl'ibedinAppendixE.2.1.2.2.
E-47REGIONALSEISMICITYTheseismicallyinducedimpactsthatwouldbeexpectedfortheDevilCanyonreservoirareaduringtheoperationperiodaresimilartothosediscussedfortheDevilCanyonreservoirduringtheconstructionperiod(Sec.E.2.1.2.1.EROSIONSubsequenttoreservoirinundation,theprimaryerosionalimpactswithintheDevilCanyonpro-jectareawouldbeconfinedtolimitedbeacherosionintheupperreachesofthereservoirareawhereoverburdenthicknessesincreaseandtoerosionalonganysiteroadsthatmightremainaroundthedamfacilities.Duringtheoperationphase,theApplicantwoulddismantletheconstructioncampandvillagefacilityandrevegetatethesitesoastoreduceerosionlossesfromthisarea.Allborrowsiteswouldalsoberevegetated.Thesemeasuresshouldbesufficienttocontrolsoilerosionlosseswithintheprojectarea.GEOLOGICALRESOURCESForthesamereasonsdiscussedinSectionE.2.1.2.1,noadverseimpactsonthegeologicalresourcesintheDevilCanyonprojectareawouldbeexpectedduringtheoperationperiod.E.2.1.3AccessRoutesE.2.1.3.1DenaliHighwaytoWatanaCONSTRUCTIONPERIODConstructionofaccessroadsintheWatana-DevilCanyonprojectareawouldbeaffectedbyandwouldinturninfluencethepotentialsforfrostheaving,permafrostthaw,slopeinstability,andliquefactionfailures.ThepresenceofpotentiallyunstableunconsolidatedmaterialssuchasfrozenbasaltillbetweentheDenaliHighwayandtheWatanadamsitehavebeennotedinthereconnaissance-level,aerialphotographyterrainevaluationmappingconductedbytheApplicant(AcresAmerican,undated:AppendixJ)(seeSec.E.1.1.1.2).Thepotentialforliquefactionandpermafrostthawrelatedfailureinthesematerialsduringtheconstructionperiodmightbehigh.TheApplicant,however,hasproposedtosite,·totheextentpossible,theaccessroadsoastoavoidpotentiallyunstabledepositsfoundduringmoredetailedgeotechnicalinvestigationsconductedduringaccessroutedevelopment(Exhibit.E,Suppl.Information,Sec.6,Item15).Becauseofthelackofdetailedinformationpertainingtotheexactlocationandnatureofthedepositswithintheaccesscorridorandtheuncertaintyastotheexactlocationof theaccessroad,evaluationoftheextentofimpactsrelatedtoaccessroadconstructionisnotpossibleatthistime.Itisknownhowever,thatapproximately630acres(250ha)ofvegetationalongthe44-mi(70-km)corridorfromtheDenaliHighwaytotheWatanadamsitewouldbecleared(ExhibitE,Vol.6A,Chap.3,p.E-3-245).Theseconstructionoperationswouldresultinincreasedsurfaceerosion,soilcompaction,possiblechangesinsurfacedrainagepatterns(result-inginwaterloggingandpossibleliquefactionofsoils)andpotentialimpactsrelatedtoperma-frostthaw.Deve1opmentoftheaccessroutewouldalsofacilitateuseofthecorridorandsurroundingareasbyoff-roadvehicles.Inallareas,adequatedrainageoftheroadwayswouldhavetobeensuredtopreventsaturationoftheunderlyingfillmaterialandsubsequentslumpingorsolifluctionandtopreventroadsideerosion.Inadequatedrainageofroadscrossingpermafrostdepositscouldleadtopermafrostthawandeventualroadco11apse.Saturationofunconso1idatedmateria1sbeneaththeroadbedwouldalsoincreasethepotentialforliquefactionfailure.Adiscussionoftheimpactsassoci-atedwiththeconstructionofroadwaysinareasunderlainbypermafrostispresentinSec-tionE.2.1.2.1.AstheaccessroutefromtheDenaliHighwaytoWatanaisunderlainbydiscon-tinuouspermafrost,manyoftheseimpactsmightbeexpected.TheApplicantproposestoreducetheimpactscausedbypermafrostthawbyusingathickpadofgranularmaterialorrigidsyn-thetic insulation,aswe11asthermopilestopreventtherma1degradationoftheunderlyingpermafrost.Theaccessroutewouldalsobelocatedtoavoidknowndepositsofpermafrostwher-everpossible(ExhibitE,Suppl.Information,Sec.6,Item15).AssuggestedbytheApplicant,constructioncutsinice-richsoilsmightbestabilizedbyrevegetationorbygranularfillaloneOt'incombinationwithsyntheticinsulation.Erosioncouldbecontrolledbyprovidingadequatedrainageandbyplacingrevetmentstoreduceflowvelocities.Placementofbrushorfillalongstreambanksanduseofdesiltingpondscouldbeusedtomitigatedownstreamsiltationimpacts(ExhibitE,Suppl.Information,Sec.6,Item15).Tominimizetheneedforconstructionofindividualaccessroadstoborrowareas,theApplicanthasproposedtositeborrowareasrequiredforaccessroadconstructionimmediatelyadjacentto
E-48theroute.Useoftheseborrowsiteswouldbeminimized,however,throughmaximumuseofside-borrowtechniquesinlevelterrainandbalancedcut-and-fil1techniquesinsidehi11cutareas.Useofthesetechniqueswouldgenerallyconfineroadconstructionactivitiestoastripapproxi-mately20ft(6m)widealongeachsideoftheroad(ExhibitE,Vol.6A,Chap.3,p.E-3-264).TheApplicantalsohaslocatedtheroutealongthelowerslopesofthemountainousterrainwithinthiscorridorsoastofollowwell-drainedterrainandgravellysoiltypessuitabletoside-borrowandcut-and-fi11constructiontechniques(ExhibitE,Vol.6A,Chap.3,p.E-3-261).Locationoftherouteinthismannerwouldbeexpectedtoreducethevolumerequirementsforborrowextractionfortheroadandminimizethearealextentofvegetationremovaloutsidetheproposedcorridoraswell.TheApplicantproposestodevelopborrowareasonlyonacontingencytosupportroad-construc-tionwhereside-borrowmaterialwouldnotbeavailableinsufficientquantities.Intheseborrowareas,overburdenwouldbestockpiledtemporarilyduringborrowsitedevelopmentinanareaselectedtominimizeerosionandrunoff(e.g.,flat,well-drained,uplandlocations).Bermsordrainagesystemswouldbeconstructedasnecessaryaroundthestockpiletocontainanyerodedsediment.Followingborrowpituse,overburdenwouldbereplacedintheborrowpitandwouldberevegetated(ExhibitE,Vol.6A,Chap.3,p.E-3-265).ThemitigationmeasuresproposedbytheApplicantshouldbesufficienttocontrolorreducethepossibleimpactsresultingfromconstructionofaccessroadsinthisarea.Furtherinformationpertainingtotheexactnatureoftheunconsolidatedmaterialsintheareawouldberequiredbeforefinalaccessroadconstructionplanscouldbefinalized,however,andbeforethepoten-tialmagnitudeofpossibleimpactscouldbedetermined.Nominera1orfue1resourceswouldbeimpactedbythedeve1opmentofthisaccessroute.Roadconstructionmaterialswouldbereadilyavailablefromtheborrowsitesforaccessroaddevelo-pmentandwouldnotimpingeonlocaldemand.Noagriculturallysuitablesoilswouldbecrossedbytheaccessroute.OPERATIONPERIODDuringtheoperationperiod,theaccessroadbetweenDenaliHighwayandtheWatanadamsitewouldcontinuetobeaffectedbyandinturninfluencethepotentialforfrostheaving,perma-frostthaw,slopeinstability,andliquefactionfailures.Thenatureoftheseimpactsduringtheoperationperiodshouldbesimilartothosedescribedabovefortheconstructionperiod.Duringtheoperationperiod,impactsduetooff-roadvehicleusemightincrease,resultinginincreasederosionandpermafrostthawinareaswherevegetationdamageisextensive.Accessrouteborrowpitswouldberevegetatedanderosionlossesfromthesedisturbedareaswouldbelessthanduringtheconstructionperiod.E.2.1.3.2WatanatoDevilCanyonCONSTRUCTIONPERIODConstructionoftheWatana-to-DevilCanyonaccessroutewouldresultinthedisturbanceofapproximately400acres(160ha)ofsoilandvegetationalonga37-mi(59-km)corridornorthoftheSusitnaRiver(ExhibitE,Vol.6A,Chap.3,p.E-3-243).Generally,thepotentialimpactsrelatedtotheconstructionofthisaccessroutewouldbesimilartothosediscussedabovefortheDenaliHighway-to-Watanaroute.Thepresenceofunstableunconsolidatedgeologicmaterials,suchasfrozenbasaltill,betweentheWatanaandDevilCanyondamsites,asdeterminedinthereconnaissance-levelterrainevaluationstudies(AcresAmerican,undated)indicatesthehighprobabilityforliquefactionfailures,landslides,andproblemsrelatedtopermafrostthawduringtheconstructionperiod.Theseimpactscouldresultinlocalizeddisturbancesofsoilsandvegetation,andpossiblyincreasedsedimentationinnearbywaterways.ThemitigationmeasuresproposedbytheApplicant,suchassitingoftheaccessroutetoavoidareasofperma-frostwhereverpossibleandtheuseofinsulationpadsundertheaccessroads(asdescribedinSec.E.2.1.3.1),shouldbeeffectiveinreducingthemagnitudeoftheseimpacts.Moredetailedsiteinformationpertainingtotheexactnatureoftheunconsolidatedmaterialsintheareaandtheexactlocationoftheaccessroutewouldberequiredbeforethepotentialmagnitudeofpossibleimpactscouldbedeterminedhowever.OPERATIONPERIODThepotentialimpactsre1atedtotheoperationoftheWatana-to-DevilCanyonaccessroutewouldbeexpectedtobesimilarinnaturetothosedescribedinSectionE.2.1.3.1.E.2.1.3.3RailAccesstoDevilCanyonCONSTRUCTIONPERIODConstructionofthe12-mi(19-km)railroadextensionsouthernsideoftheSusitnaRiverwoulddisturb~~r.~~·,'andGoldCreekonthe(29ha)ofvegetation
E-49andsoils(ExhibitE,Vol.6A,Chap.3,p.E-3-243).ThepotentialimpactsrelatedtotheconstructionoftherailaccesstoDevilCanyonwouldbesimilartothosediscussedinSec-tionE.2.1.3.1.Thepresenceofunstableunconsolidatedgeologicmaterialssuchasbasaltill,colluvium,andsolifluctiondeposits,alongthisroute,asdeterminedinthereconnaissance-levelterrainevaluationstudies(AcresAmerican,undated)indicatesthehighprobabilityforliquefactionfailures,landslides,andproblemsrelatedtopermafrostthawduringtheconstruc-tionperiod.Theseimpactsshouldresultinlocalizeddisturbancesofsoilsandvegetationandpossiblyincreasedsedimentationinnearbywaterways.ThemitigationmeasuresproposedbytheApplicant,suchasthelocationoftheaccessroutetoavoidareasofpermafrostwhereverpossibleanduseofinsulationpadsundertheraillineshouldbeeffectiveinreducingthemagnitudeoftheseimpacts.Moredetailedsiteinformationdescribingtheexactnatureoftheunconsolidatedmaterialsintheareaandtheexactlocationoftheraillinkwouldberequiredbeforethepotentialmagnitudeofpossibleimpactsduetoconstructionactivitiescouldbedetermined.Incontrasttoaccessroadconstruction,whichwouldrequireaclearingwidthof120ft(37m),therailaccessconstructionwouldrequireaclearingwidthofonly50ft(15m).Onaperunitlengthbasis,therefore,thesoildisturbancesandconstructionmaterialrequirementswouldbelessforrailaccessthanforroadaccess.DevelopmentoftherailheadfacilityatDevilCanyonwouldrequirethedisturbanceofapproxi-mately46acres(19ha)ofvegetationandsoil.Thelocationofthisfacilityonrelativelyflatterrainwouldreducethepossibilityforexcessivesurfaceerosionduringconstruction.UseofmitigationmeasurestocontroldrainageandrunoffasproposedbytheApplicantfordevelopmentofborrowsitesandforallconstructionactivities(seeSec.E.2.1.1.1)wouldbeexpectedtoprovideadequateerosioncontrolduringtheconstructionperiod.Othermitigativemeasuresthatcouldbeusedtominimizepossibleconstruction-relatederosionimpactsaredis-cussedinSectionE.3.Nominera1orfuelresourceswouldbeimpactedbythedevelopmentoftherailaccesstoDevilCanyon.Necessaryconstructionmaterialswouldbereadilyavailableintheareaandwouldnotimpingeonlocaldemands.Noagriculturallysuitablesoilswouldbecrossedbytherailaccess.OPERATIONPERIODDuringtheoperationperiod,therailaccesstoDevilCanyonwouldcontinuetobeaffectedbyand,inturn,influencethepotentialforfrostheaving,permafrostthaw,slopeinstability,and1iquefactionfailures.Thenatureoftheseimpactsfortherail1ineduringtheoperationperiodshouldbesimilartothosedescribedfortheconstructionperiod.RunofffromtheconcretepadattheDevilCanyonrailheadfacilitymightincreasethevolumeoflocalsurfacerunofftostreamsadjacenttothepad.Suchrunoffmightincreaseerosionofsoilsadjacenttothepadunlessadequatedrainagesystemswereprovided(seeSec.E.3).Incontrasttotheaccessroadcorridors,off-roadvehicletrafficwouldnotbeexpectedtoincreaseasaresultoftherailaccessdevelopment.E.2.1.4PowerTransmissionFacilitiesE.2.1.4.1Dams-to-GoldCreekSegmentCONSTRUCTIONPERIODAspreviouslydiscussed,theproposedtransmissionlinesegmentbetweenthedamsandGoldCreekcrossespotentiallyunstable,unconsolidatedgeologicmaterialssuchasfrozenbasaltill,colluvium,andsolifluctiondeposits.Determinationofthelocationofthesedepositshasbeenmadesolelythroughtheuseofreconnaissance-levelaerialphotographterrainevaluationssup-portedbyverylimitedfieldconfirmation(AcresAmerican,undated).Typicalofsuchglaciatedareas,however,thesurficialdepositscanchangerapidlyalongashortdistancebothlaterallyandwithdepth.Becausetheexactlocationsofthetransmissiontowersandassociatedaccessroadshavenotbeenidentifiedtodate,onlygeneralassumptionspertainingtothenatureandmagnitudeofimpactsrelatedtotheconstructionofthetransmissioncorridorcanbemadeatthistime.TheApplicanthasproposedtomakeon-groundevaluationofsiteconditionsduringthedetailedengineeringdesignandconstructionplanningphasesoastodeterminetheappro-priatemanagementproceduresforspecificportionsofthetransmissioncorridor.ThesesiteassessmentswouldbeconductedincoordinationwithrepresentativesoftheU.S.FishandWild-lifeService,theAlaskaDepartmentofFishandGame,andtheAlaskaPlantMaterialsCenter(ExhibitE,Vol.6A,Chap.3,p.E-3-273).DevelopmentoftheDams-to-GoldCreektransmissionlinesegmentwouldrequiretheselectiveclearingoftreesandtallshrubsfromapproximately1,500acres(610ha)ofland.Noclearingoflow-lyingvegetationorsmallshrubsfromtheright-of-wayisproposed(ExhibitE,Vol.6A,
E-50Chap.3,p.E-3-244).Althoughheavyequipmentmovementwithintheright-of-wayduringtheclearingprocesswoulddisturbthesurfacesoilsandvegetation,resultinginthepotentialinincreasederosion,thelow-lyingvegetationandorganicmatcoveringthesoilintheareashouldgenerallyacttotrapandstabilizeanyerodedsediment.Inthefewareasrequiringextensiveremovaloftreesandtallshrubs(seeAppendixJ)orwhereclearingoccurredadjacenttodrain-agesystems,sedimentlossesmightbesubstantial.Topreventerosionofthesesedimentsintowaterways,theApplicantproposestoplacebrushalongstreambanksortousedesi1tingpondstomitigatedownstreamsiltationimpacts(ExhibitE,Supp1.Information,Sec.6,Item15).Thesemeasuresshouldbeeffectiveinprovidingadequateprotectionagainsterosionimpacts.Othermeasuresthatcouldbeusedtocontrolsucherosion arediscussedinSectionE.3.TheplantocombinetheWatana-to-Go1dCreekaccessroadandtransmissionlinecorridorwouldminimizethetraffic-relatedvegetationremovalandsoildisturbancebyreducingthedistancesrequiredfortransportofequipmentfromthenearestroadtothetransmissioncorridor(ExhibitE,Vol.6A,Chap.3,p.E-3-255).Useoftheconstructiontrailsfromthemainaccessroadtotheright-of-waywouldbelimitedbytheApplicanttoflat-treadorballoontirevehiclessothatfillreplacementorremovaloforganiclayerwouldnotberequired(ExhibitE,Vol.6A,Chap.3,p.E-3-272).Thesemeasuresshouldbeeffectiveinminimizingsoildisturbances.Theconstructionofthetransmissiontowers,controlstations,andrelaybuildingswouldresultinverylocalizeddisturbancesofsoilsandvegetation.Whereverpossible,theApplicantwouldconstructallstructuresonthawstablesoils(ExhibitE,Suppl.Information,Sec.5,Item15).Wherethatwasnotpossible,theApplicantwouldusenumerousmeasurestomitigatethepotentialimpactsduetothawingofice-richsoils.Thesemeasuresincludetheuseofreinforcingsupportpolesimbeddedinthepermafrosttodepthsgreaterthantwicethethicknessoftheactivelayerinthepermafrost,useofaconcretepadrestingonaninsulatinggravelpadforguyedmetaltowers,anduseofthermopilestodissipateheatfromthegroundunderandaroundthetowerstructure(ExhibitE,Suppl.Information,Sec.6,Item15).Useofthesemeasuresshouldincreasethestabilityofallfacilitiesandminimizethedisturbanceofthepermafrostregimeinthevicinity,therebyreducingthepotentialforlocalizedsettlement,slumpingandsoli-fluctionofsurfacedeposits.TheApplicantwouldevaluatethesuitabilityofaparticularterrainunitfortransmissiontowerfoundationsthroughtheuseofonsitesubsurfaceinvestigation,andsamplingandlaboratorytestingatrepresentativelocationsalongthelinelength.Avarietyoftowerandfoundationdesignswouldbeavailableandwouldbeselectedsoastoprovidesafeandeconomicaltowerfoundationdesignsforeachtowersite(ExhibitB,p.B-2-120).Theprimaryimpactsrelatedtotowerconstructionwouldbethoseassociatedwiththedevelopmentofaccessroads.TheimpactsthatwouldbeexpectedforthetransmissionlineaccessroutesbetweenthedamsitesandGoldCreekwouldbesimilartothosediscussedinSectionsE.2.1.3.1andE.2.1.3.2.Noagriculturallysuitablesoilsorknowngeologicresourceswouldbeimpactedbytheconstruc-tionofthetransmissionlineoraccessroadsfromGoldCreektothetwoprojectdams.OPERATIONPERIODDuringtheoperationperiod,impactsrelatedtothetransmissionlineswouldbethoseassociatedwithmaintenanceofaccessroadsbetweenGoldCreekandthedamsites.TheimpactswouldbesimilartothosediscussedinSectionsE.2.1.3.1andE.2.1.3.2.E.2.1.4.2GoldCreek-to-FairbanksSegmentCONSTRUCTIONPERIODThegeneralnatureofimpactsandtheproposedmeasurestomitigatetheimpactsassociatedwithtransmissiontowerconstruction,right-of-waydevelopment,andtransmissionlineaccessroadsarediscussedinSectionE.2.1.4.1.Landslide,solifluction,andcolluvialdeposits,aswellaseolianloess,siltyalluvialfan,floodp1ain,retransportedtillandorganicdepositsfoundalongthetransmission1inecorridor(seeSec.E.1.1.3)areknowntohavepotentiallyundesirablesoilfoundationconditions.Generally,theseconditionsbecomeincreasinglymoreseveretowardthenorthernsegmentoftheproposedtransmission1inecorridor.Permafrostdepositsa1sobecomeincreasinglymorecon-tinuoustothenorthandincreasethepotentialforconstructiondifficulties.BetweenGoldCreekandFairbanks,areasoffine-grained,poorlydrainedsedimentswereidenti-fiedasareasofprimaryconcerntoconstructionprojectsassociatedwiththeAlaskaRailroad(Ferrainsetal.,1969)andwouldlikewiseaffecttransmissionlineconstruction.SurficialdepositsbetweenBroadPassandFairbanks(especiallytheGoldstreamValley)andtheglaciolacu-strinedepositsnearMoodyintheNenanaRiverValleyaredescribedasbeingofspecialconcern
E-51becauseoftheirpotentialforimpactsfrompermafrostthawandliquefaction(e.g.,settlement,caving,slumping,flow).AsdiscussedinSectionE.2.1.4.1,theexactlocationsofthetransmissiontowersandrelatedfacilities,aswe11asthe1ocationsofspecificsurficia1depositsofconcern,havenotbeenclarifiedtodate.Asaresult,onlygeneralestimatesastothenatureandmagnitudeofimpactsrelatedtotheconstructionofthistransmissionlinesegmentcanbemadeatthistime.Right-of-waydevelopmentofthesingle-towerGoldCreek-to-FairbankslinesegmentthatwouldparalleltheIntertiecorridorformuchofitslengthwouldresultinthewideningoftheexist-ingright-of-wayby190ft(58m).Soilandvegetationdisturbancesassociatedwiththisaddi-tionalright-of-waydevelopmentwouldbelessthanthoseassociatedwiththedevelopmentofanew300-ft(90-m)transmissionright-of-way.Theexistenceofpotentialaccessroadsforalmosttheentirelengthofthislinewouldfurtherminimizeimpactsrelatedtoaccessroadconstruc-tion.Basedonthefewsoilsurveyscompiledforthisregion(FurbushandSchoephorster,1977;Riegeretal.,1963,1979),agriculturalsoilsalongthissegmentof thetransmissioncorridorappeartobevery1imited.Nosoi1sthataresuitab1eformostfie1dcropsorthathavefew1imita-tionsrestrictingtheiruse(ClassIsoils)arepresentalongthiscorridor.Inthenorthern-mostportionofthecorridor,limitedareasofClassIIsoils(soilsthathavemoderatelimi-tationsthatreducethechoiceofplantsorthatrequiremoderateconservationpractices)arecrossedbythecorridor.Theimpacttothesesoilsfromtransmissionlineconstructionwouldbesmallbecauseoftheavailabilityofexistingaccessroadsandthelimitedamountofspaceactuallydisturbedbythetransmissiontower.Forsimilarreasons,developmentofthetrans-missionlinewouldnotimpactanygeological resourceswithintheproposedcorridor.Noknownmineralorfuelresourcesareknowntoexistwithintheproposedright-of-way.OPERATIONPERIODDuringtheoperationperiod,impactswouldbeprimarilyattributabletothemaintenanceofaccessroadsalongthetransmissionline.TheseimpactswouldbesimilarinnaturetothosediscussedinSectionE.2.1.3.1.E.2.1.4.3GoldCreek-to-AnchorageSegmentCONSTRUCTIONPERIODAlongtheGoldCreek-to-Anchoragesegmentof thetransmissionlineroute,permafrostisgenerallyabsentandsoilsarethawstable.Numerousunconsolidateddepositthatwouldbecrossedbythetransmissionlinecorridorhavehighlyundesirablefoundationcharacteristics.Localizedland-slidedeposits,marinetidaldepositsfoundinthesouthernportionofthecorridor,andfluvialdeltaicandorganicdepositsfoundthroughoutthecorridorareallsubjecttoextremetohighliquefactionpotential(ExhibitE,Suppl.Information,Sec.6,Item16).AdescriptionofthelocationsofthesedepositsispresentedinSectionE.1.1.3.However,becausetheexactloca-tionofthetransmissiontowersandrelatedfacilities,aswellasthelocationofspecificsurficialdepositsofconcern,havenotbeendelineatedtodate,onlygeneralassumptionsastothenatureandmagnitudeofimpactsthatwouldbeexpectedasaresultoftransmissiontowerconstructioncanbemade.Thetransmissioncorridorright-of-waywouldaffectapproximately250acres(l00ha)ofthePointMacKenzieagriculturalprojectand535acres(216ha)oftheFishCreekagriculturalproject(ExhibitE,Suppl.Information,Sec.6,Item16).Additionally,thecorridorwouldcrossmanyareasofsoilsuitedforagricultura1production(SoilConservationServicesoilcapabilityClassesII,III,andIV)southofWillowandeastoftheSusitnaRiver(SchoephorsterandHinton,1973;Schoephorster,1968;Riegeretal.,1979).Theimpacttothesesoilswouldbeprimarilyrelatedtothedevelopmentofanynewaccessroadsthatmightberequired.ExistingIntertieaccessroadswouldbeusedwhereverpossible.Onlylimitedareasofsoilwouldbedisturbedbytransmissiontowerconstruction.Nogeologicresourcesareknowntoexistwithintheproposedtransmissioncorridor.OPERATIONPERIODDuringtheoperationperiod,transmissionlineimpactswouldbeprimarilyattributabletomain-tenanceofthetransmissionlineaccessroads.TheseimpactswouldbesimilarinnaturetothosediscussedinSectionE.2.1.3.1
E-50Chap.3,p.E-3-244).Althoughheavyequipmentmovementwithintheright-of-wayduringtheclearingprocesswoulddisturbthesurfacesoilsandvegetation,resultinginthepotentialinincreasederosion,thelow-lyingvegetationandorganicmatcoveringthesoilintheareashouldgenerallyacttotrapandstabilizeanyerodedsediment.Inthefewareasrequiringextensiveremovaloftreesandtallshrubs(seeAppendixJ)orwhereclearingoccurredadjacenttodrain-agesystems,sedimentlossesmightbesubstantial.Topreventerosionofthesesedimentsintowaterways,theApplicantproposestoplacebrushalongstreambanksortousedesiltingpondstomitigatedownstreamsiltationimpacts(ExhibitE,Suppl.Information,Sec.6,Item15).Thesemeasuresshouldbeeffectiveinprovidingadequateprotectionagainsterosionimpacts.OthermeasuresthatcouldbeusedtocontrolsucherosionarediscussedinSectionE.3.TheplantocombinetheWatana-to-GoldCreekaccessroadandtransmissionlinecorridorwouldminimizethetraffic-relatedvegetationremovalandsoildisturbancebyreducingthedistancesrequiredfortransportofequipmentfromthenearestroadtothetransmissioncorridor(ExhibitE,Vol.6A,Chap.3,p.E-3-255).Useoftheconstructiontrailsfromthemainaccessroadtotheright-of-waywouldbelimitedbytheApplicanttoflat-treadorballoontirevehiclessothatfillreplacementorremovaloforganiclayerwouldnotberequired(ExhibitE,Vol.6A,Chap.3,p.E-3-272).Thesemeasuresshouldbeeffectiveinminimizingsoildisturbances.Theconstructionofthetransmissiontowers,controlstations,andrelaybuildingswouldresultinverylocalizeddisturbancesofsoilsandvegetation.Whereverpossible,theApplicantwouldconstructallstructuresonthawstablesoils(ExhibitE,Suppl.Information,Sec.5,Item15).Wherethatwasnotpossible,theApplicantwouldusenumerousmeasurestomitigatethepotentialimpactsduetothawingofice-richsoils.Thesemeasuresincludetheuseofreinforcingsupportpolesimbeddedinthepermafrosttodepthsgreaterthantwicethethicknessoftheactivelayerinthepermafrost,useofaconcretepadrestingonaninsulatinggravelpadforguyedmetaltowers,anduseofthermopilestodissipateheatfromthegroundunderandaroundthetowerstructure(ExhibitE,Suppl.Information,Sec.6,Item15).Useofthesemeasuresshouldincreasethestabilityofallfacilitiesandminimizethedisturbanceofthepermafrostregimeinthevicinity,therebyreducingthepotentialforlocalizedsettlement,slumpingandsoli-fluctionofsurfacedeposits.TheApplicantwouldevaluatethesuitabilityofaparticularterrainunitfortransmissiontowerfoundationsthroughtheuseofonsitesubsurfaceinvestigation,andsamplingandlaboratorytestingatrepresentativelocationsalongthelinelength.Avarietyoftowerandfoundationdesignswouldbeavailableandwouldbeselectedsoastoprovidesafeandeconomicaltowerfoundationdesignsforeachtowersite(ExhibitB,p.B-2-120).Theprimaryimpactsrelatedtotowerconstructionwouldbethoseassociatedwiththedevelopmentofaccessroads.TheimpactsthatwouldbeexpectedforthetransmissionlineaccessroutesbetweenthedamsitesandGoldCreekwouldbesimilartothosediscussedinSectionsE.2.1.3.1andE.2.1.3.2.Noagriculturallysuitablesoilsorknowngeologicresourceswouldbeimpactedbytheconstruc-tionof thetransmissionlineoraccessroadsfromGoldCreektothetwoprojectdams.OPERATIONPERIODDuringtheoperationperiod,impactsrelatedtothetransmissionlineswouldbethoseassociatedwithmaintenanceofaccessroadsbetweenGoldCreekandthedamsites.TheimpactswouldbesimilartothosediscussedinSectionsE.2.1.3.1andE.2.1.3.2.E.2.1.4.2GoldCreek-to-FairbanksSegmentCONSTRUCTIONPERIODThegeneralnatureofimpactsandtheproposedmeasurestomitigatetheimpactsassociatedwithtransmissiontowerconstruction,right-of-waydevelopment,andtransmissionlineaccessroadsarediscussedinSectionE.2.1.4.1.Landslide,solifluction,andcolluvialdeposits,aswellaseolianloess,siltyalluvialfan,floodp1ain,retransportedtillandorganicdepositsfoundalongthetransmission1inecorridor(seeSec.E.1.1.3)areknowntohavepotentiallyundesirablesoilfoundationconditions.Generally,theseconditionsbecomeincreasinglymoreseveretowardthenorthernsegmentoftheproposedtransmissionlinecorridor.Permafrostdepositsalsobecomeincreasinglymorecon-tinuoustothenorthandincreasethepotentialforconstructiondifficulties.BetweenGoldCreekandFairbanks,areasoffine-grained,poorlydrainedsedimentswereidenti-fiedasareasofprimaryconcerntoconstructionprojectsassociatedwiththeAlaskaRailroad(Ferrainsetal.,1969)andwouldlikewiseaffecttransmissionlineconstruction.SurficialdepositsbetweenBroadPassandFairbanks(especiallytheGoldstreamValley)andtheglaciolacu-strinedepositsnearMoodyintheNenanaRiverValleyaredescribedasbeingofspecialconcern
E-51becauseoftheirpotentialforimpactsfrompermafrostthawandliquefaction(e.g.,settlement,caving,slumping,flow).AsdiscussedinSectionE.2.1.4.1,theexactlocationsofthetransmissiontowersandrelatedfacilities,aswellasthelocationsofspecificsurficialdepositsofconcern,havenotbeenclarifiedtodate.Asaresult,onlygeneralestimatesastothenatureandmagnitudeofimpactsrelatedtotheconstructionofthistransmissionlinesegmentcanbemadeatthistime.Right-of-waydevelopmentofthesingle-towerGoldCreek-to-FairbankslinesegmentthatwouldparalleltheIntertiecorridorformuchofitslengthwouldresultinthewideningoftheexist-ingright-of-wayby190ft(58m).Soilandvegetationdisturbancesassociatedwiththisaddi-tionalright-of-waydevelopmentwouldbelessthanthoseassociatedwiththedevelopmentofanew300-ft(90-m)transmissionright-of-way.Theexistenceofpotentialaccessroadsforalmosttheentirelengthofthislinewouldfurtherminimizeimpactsrelatedtoaccessroadconstruc-tion.Basedonthefewsoilsurveyscompiledforthisregion(FurbushandSchoephorster,1977;Riegeretal.,1963,1979),agriculturalsoilsalongthissegmentofthetransmissioncorridorappeartobeverylimited.Nosoilsthataresuitableformostfieldcropsorthathavefewlimita-tionsrestrictingtheiruse(ClassIsoils)arepresentalongthiscorridor.Inthenorthern-mostportionofthecorridor,limitedareasofClassIIsoils(soilsthathavemoderatelimi-tationsthatreducethechoiceofplantsorthatrequiremoderateconservationpractices)arecrossedbythecorridor.Theimpacttothesesoilsfromtransmissionlineconstructionwouldbesma11becauseof theavai1abilityofexistingaccessroadsandthe1imitedamountofspaceactuallydisturbedbythetransmissiontower.Forsimilarreasons,developmentof thetrans-missionlinewouldnotimpactanygeological resourceswithintheproposedcorridor.Noknownmineralorfuelresourcesareknowntoexistwithintheproposedright-of-way.OPERATIONPERIODDuringtheoperationperiod,impactswouldbeprimarilyattributabletothemaintenanceofaccessroadsalongthetransmissionline.TheseimpactswouldbesimilarinnaturetothosediscussedinSectionE.2.1.3.1.E.2.1.4.3GoldCreek-to-AnchorageSegmentCONSTRUCTIONPERIODAlongtheGoldCreek-to-Anchoragesegmentofthetransmissionlineroute,permafrostisgenerallyabsentandsoilsarethawstable.Numerousunconsolidateddepositthatwouldbecrossedbythetransmissionlinecorridorhavehighlyundesirablefoundationcharacteristics.Localizedland-slidedeposits,marinetidaldepositsfoundinthesouthernportionofthecorridor,andfluvialdeltaicandorganicdepositsfoundthroughoutthecorridorareallsubjecttoextremetohighliquefactionpotential(ExhibitE,Suppl.Information,Sec.6,Item16).AdescriptionofthelocationsofthesedepositsispresentedinSectionE.l.1.3.However,becausetheexactloca-tionofthetransmissiontowersandrelatedfacilities,aswellasthelocationofspecificsurficialdepositsofconcern,havenotbeendelineatedtodate,onlygeneralassumptionsastothenatureandmagnitudeofimpactsthatwouldbeexpectedasaresultoftransmissiontowerconstructioncanbemade.Thetransmissioncorridorright-of-waywouldaffectapproximately250acres(l00ha)ofthePointMacKenzieagriculturalprojectand535acres(216ha)oftheFishCreekagriculturalproject(ExhibitE,Suppl.Information,Sec.6,Item16).Additionally,thecorridorwouldcrossmanyareasofsoilsuitedforagriculturalproduction(SoilConservationServicesoilcapabilityClassesII,III,andIV)southofWillowandeastoftheSusitnaRiver(SchoephorsterandHinton,1973;Schoephorster,1968;Riegeretal.,1979).Theimpacttothesesoilswouldbeprimarilyrelatedtothedevelopmentofanynewaccessroadsthatmightberequired.ExistingIntertieaccessroadswouldbeusedwhereverpossible.Onlylimitedareasofsoilwouldbedisturbedbytransmissiontowerconstruction.Nogeologicresourcesareknowntoexistwithintheproposedtransmissioncorridor.OPERATIONPERIODDuringtheoperationperiod,transmissionlineimpactswouldbeprimarilyattributabletomain-tenanceofthetransmissionlineaccessroads.TheseimpactswouldbesimilarinnaturetothosediscussedinSectionE.2.1.3.1
E-52E.2.2SusitnaDevelopmentAlternativesE.2.2.1AlternativeDamLocationsandDesignsE.2.2.1.1WatanaI-DevilCanyonTheimpactsassociatedwiththedevelopmentofDevilCanyonsitewouldbeidenticaltothosediscussedinSectionE.2.1.2.TheimpactsassociatedwiththedevelopmentoftheWatanaIalternativewouldbesimilarinnature,althoughnotinmagnitude,tothosediscussedinSec-tionE.2.1.1.BecausetheWatanaIreservoirelevation[2,100ft(640m)MSLJwouldbe100ft(30m)lessthantheproposedWatanaprojectelevation[2,200ft(670m)Jthetotalareaaffec-tedbyreservoirfloodingwouldbelessfortheWatanaIalternative.FewermilesofbeacheswouldbedevelopedfortheWatanaIalternative,andasaresult,themagnitudeofreservoirslopefailuremightbeless.However,becausethereservoirheightwouldbe100ft(30m)lessforWatanaIthanfortheproposedWatanareservoir,WatanaIreservoirbeacheswouldnotbeformedatthetopofthesurroundingslopes(aswouldbethecasefortheproposedproject)butatthebaseormid-slope.SuchbeachdevelopmentundertheWatanaIalternativewouldacceleratereservoirslopefailureandincreasethemagnitudeoftheimpactsdiscussedinSectionE.2.1.1.BecauseofthereducedreservoirheightfortheWatanaIalternative,seepagelossesthroughtheWatanarelictchannelandotherjointfeatureswouldbereducedasaresultofreducedhydro-staticheadpressure.Thereduceddamheightandsizewouldalsorequireconsiderablylessconstructionmaterial,therebyreducingborrowmaterialrequirementsandborrow-site-relatedimpacts.E.2.2.1.2WatanaI-ModifiedHighDevilCanyonImpactsassociatedwiththedevelopmentoftheWatanaIalternativewouldbeaspresentedinSectionE.2.1.1.ImpactsassociatedwiththedevelopmentoftheModifiedHighDevilCanyonsitewouldbesimilarinnaturetothoseassociatedwiththedevelopmentof theDevilCanyonsite(Sec.E.2.1.2).TheModifiedHighDevilCanyonsitewouldbelocatedupriveroftheproposedDevilCanyonsiteandwouldcrestatanelevationof1,470ft(441m),sothereservoirwouldextendtojustdownstreamoftheWatanadam.ThereservoirareafortheModifiedHighDevilCanyonsitewouldbesmallerthanfortheproposedDevilCanyonsiteandconsequentlymanyimpactsmightbereduced.Thetotalareaofsoilsthatwouldbedisturbedbyreservoirfloodingwouldbeless.BecausethetotallengthofbeacheswouldbereducedfortheModifiedHighDevilCanyonalternative,themagnitudeofreservoirslopefailuremightalsobereduced.However,becauseslopefailurewouldbemorelikelytooccurintheupstreamportionsof theDevilCanyonreservoir(theareathatwouldbeaffectedbythedevelopmentoftheModifiedHighDevilCanyonreservoir),theimpactsrelatedtoreservoirslopecouldbesimilarforbothalternatives.E.2.2.1.3WatanaI-ReregulatingDamImpactsassociatedwiththedeve1opmentoftheyJatanaI a1ternativearepresentedinSec-tionE.2.2.1.1.Developmentof theReregulatingdamwouldresultintheinundationof15.8rivermiles(25.4km)andthecreationofareservoircovering4,000acres(1,600ha).TheimpactsassociatedwiththedevelopmentoftheReregulatingdamalternativewouldbesimilarinnaturetothosediscussedinSectionE.2.1.2.BecausetheReregulatingdamalternativewouldinundateasmallerareathantheproposedDevilCanyonreservoir,themagnitudeoftheimpactswouldbeless.ThedisturbanceanderosionofsurfacesoilswithinthereservoirareawouldbelessthanfortheproposedDevilCanyonalternative.Inconjunctionwiththereducedreservoirsize,thetotallengthofbeachdevelopment,andthusthetotalamountofbeacherosionandslopefailure,wouldalsobesmallerfortheReregulatingdamalternative.E.2.2.2AlternativeAccessRoutesE.2.2.2.1NorthernAccessRouteThegeneralimpactsthatmightbeexpectedasaresultoftheconstructionandoperationofanorthernaccessroutearesimi1artothosedescribedfortheproposedaccessplaninSec-tionE.2.1.3.2.Thesectionof thealternativeaccessroutebetweenDevilCreekandTsusenaCreekwouldbeidenticaltotheproposedaccessroute.WestofDevilCreektheroutewouldfollowthePortageCreekValley,whereextensivesidehillcuttingwouldberequired.Erosionlossesmightbehighinthissection.E.2.2.2.2SouthernAccessRouteThegeneralimpactsthatmightbeexpectedasaresultoftheconstructionandoperationofasouthernaccessroutearesimilartothosedescribedfortheproposedaccessplaninSec-tionE.2.1.3.2.ThemountainoustopographyoftheareabetweentheDevilCanyonandWatanadamsiteswouldrequireanumberofsidehillcutsandtheconstructionoftwomajorbridges
E-53(ExhibitE,Vol.2,pp.13-2-64)foraccessbetweenthetwosites.Soilswithintheseareasareclassifiedashavingseveretoveryseverelimitationsforroadconstructionduetosteepslopes.Asaresult,erosionlossesinthisareaduetoroadconstructioncouldbehighevenwiththeuseofmitigativemeasures.E.2.2.3AlternativePowerTransmissionRoutesE.2.2.3.1Willow-to-AnchorageSegmentThegeneralimpactsandproposedmeasurestomitigateimpactsassociatedwithtransmissiontowerconstruction,right-of-waydevelopment,andtransmissionlineaccessroadsarediscussedinSectionE.2.1.4.Allcorridorsinthissegmentwouldcrossareasofgoodagriculturalsoils.Theexactextentoftheseareasisnotknownatthistime,andthemagnitudeoftheimpactsduetotransmissionlineandaccessrouteconstructioncannotbedetermined.Generally,however,onlysmallareasofagriculturalsoilwouldbelostundereachtransmissiontowerstructure.Useofexistingroadswherepossiblewouldminimizethelossofland.Constructionactivitiesassociatedwithtoweremplacementandroaddevelopmentmightresultinsoilcompaction,whichmightreducesoilfertility.MeasurestomitigatetheeffectofsoilcompactionarediscussedinSectionE.3.Withinallthreecorridors,especiallyCorridors2(ADFC)and3(AEFC),areasofwet,organicsoilswithseverelimitationstoroadandtowerconstructionarepresent.ItisassumedthatthesesoilswouldbeavoidedbytheApplicantwhereverpossible.Constructiononthesesoilswouldjeopardizetowerstabilityandaccessroaduse,aswellasincreaseconstructioncosts.Nopermafrostispresentinthissegment.BecauseoftheincreasedlengthofCorridor1(ABC')[73mi(117km)]relativetoCorridors2[ADFC-38mi(61km)]and3[AEFC-39mi(63km)]theimpactsassociatedwiththedevelopmentofCorridor1mightbeassumedtobegreaterthanforCorridors2and3.However,assegmentBC'ofCorridor1parallelsatransmissionlinefromKnikRivertoAnchorageandparallelstheGlennHighwayfromKnikRivertoBirchwood,aswellasarailroadfromEagletoC',theactualamountoflanddisturbedinCorridor1foraccessroadsandright-of-waymightbesimilarorlessthanforCorridors2and3.E.2.2.3.2Dams-to-GoldCreekSegmentAllcorridorsegments.inthisareacrosswetsoilsandseveraldeepravines,andallcorridorsexceptCorridor13(ABCF)and15(ABECF)encountersteepslopes.ShallowbedrockisencounteredinallbutCorridors1(ABCD),2(ABECD),3(AJCF),13(ABCF),14(AJCD),and15(ABECF).Wherepossible,ravineswouldbespanned.Elsewhere,constructionoftransmissiontowersandaccessroadsonsteepterrainornearravineswouldacceleratesoilerosion.Removalofvegetationfromareasofshallowbedrockwouldresultinacceleratederosionofsoilfromthoseareas.Asthetotalamountofsoilintheseareasislimited,thetotalamountofsoillosseswouldbesmall,althoughpossiblysignificantforthevegetationinthearea.Constructiononareasofshallowbedrockaswellaswetsoilswouldrequiremoreelaborateandexpensivetowerinstalla-tionprocedures.Theexactlocationofthetransmissiontowersandassociatedaccessroads,aswellasthelocationofspecificsurficialdepositsorconditionsofconcern,arenotyetspeci-fied,andonlygeneralassumptionscanbemadeastotherelativemagnitudeofimpactsrelatedtoconstructioninaparticularcorridor.CorridorsI,2,3,13,14,and15areamongtheshortestofthecorridors,ranginginlengthfrom40to45mi(64to72km).Thesecorridorsarealsolocatedinanareaofhillytopo-graphy,whereerosionwouldbeexpectedtobemoderate.Corridors4(ABCJHI),5(ABECJHI),6(CBAHI),and7(CEBAHI)areintermediateinlength,rangingfrom68to82mi(109to132km),andsegmentsJHIandAHIpassthroughthemostmountainousportionofthearea.Althoughero-sionwouldbeexpectedtobehighinthisarea,shallowbedrockmightlimittotalerosionlosses.Corridors8(CBAG),9(CEBAG)and10(CJAG)areamongthelongestcorridors,rangingfrom90to95mi(145to153km),andcrossthroughgentlyslopingterrainofDeadmanandBrushkanacreeksandtheNenanaRiverValley.ErosionlossesforCorridol's8,9,and10mightbeslighttomoderatebasedonslope.However,thepresenceofwetsoilsandshallowpermafrostinsegmentAGwouldincreasethepotentialforlocalizedsettling,slumping,andsolifluctionofsurfacedepositsduringtransmissiontowerandaccessroadconstruction.Noexistingaccessroadsarepresentinthisarea,exceptfortheOldCorpsTrailinSegmentCDthatextendsfromGoldCreektoDevilCanyonandtheDenaliHighwaythatparallelssegmentAGbetweenBrushkanaCreekandG.TheamountofupgradingthatwouldberequiredtoallowtheuseoftheOldCorpsTrailasanaccessrouteisnotknown.NoupgradingoftheDenaliHighwaywouldberequired.Noagriculturalsoilsarecrossedbyanycorridorsinthissegment.E.2.2.3.3Healy-to-FairbanksSegmentAllcorridorsinthissegmentwouldcrosswet,poorlydrainedsoilsandpermafrostintheout-washplainsandrivervalleysnorthoftheAlaskaRange.This\-lOuldseverelyrestrictthe
E-54locationanddevelopmentofaccessroadsandtransmissiontowers(Sec.E.2.1.4).WhereCorridors3(AEDC)and4(AEF)passthroughverysteepmountainousareasbetweensegmentAE,soilerosionlossesduringtowerandaccessroadconstructionandoperationwouldbeaccelerated,althoughthelimitedextentanddepthofthesesoilsmaylimittotallosses.AllcorridorsareexpectedtocrossagriculturallysuitablesoilsneartheTananaRiverValley.Theextentofthesesoilsisunknown.Generally,however,onlythesmallareasofsoilsundereaC1towerwouldbelosttoagriculturaluse.Greaterareasofsoilsmightbelosttoaccessroaddevelopment,buttheselosseswouldbeminimizedbytheuseofexistingroadswhereverpossible.Movementofheavymachineryoverthesesoilswouldresultinsoilcompactionandlossesinfertility.MeasurestomitigatetheeffectsofsoilcompactionBrediscussedinSectionE.3.FromHealytoBrowne,segmentABofCorridors1and2closelyparallelstheParksHighway,theAlaskaRailroad,andanexistingtransmissionline.SegmentBCofCorridor1iswithinseveralmilesofthesefeatures;therefore,accessroaddevelopmentandrelatedconstructionimpactsforCorridol'1wouldbeminimized.Noknownaccessroutesarepresentforthe46-mi(74-km)BDCsegmentofCorridol'2.SegmentAEofCorridol's3and4para11e1ssmallroads,trails,andrailwaysforpartof thesegment,andexpansionandextensionoftheseaccessrouteswouldberequired.Noexistingaccessroutesarepresentalongthe50-mi(80-km)lengthofsegmentEDCinCorridor3.SegmentEFofCorridor4parallelstheBonnifieldTrailfromClearCreekButtetoFairbanks.Theamountofupgradingthatwouldberequiredforuseofthistrailasanaccessrouteisunknownatthistime.E.2.2.4AlternativeBorrowSitesAlternativeborrowsitesC,FandHwouldbelocatedoutsidethereservoirareaandtheirusewouldnecessitatetheconstructionofhaulroadstotheproposedproject.Revegetationwouldberequiredfollowingborrowareadevelopment.BorrowareaBwouldbelocatedinsidetheproposedreservoirarea,whichwouldminimizeerosionimpactsassociatedwithexcavationanduseofthisborrowarea.E.2.3Non-SusitnaGenerationAlternativesE.2.3.1Natural-Gas-FiredGenerationScenarioEight200-MWcombined-cycleunitsandtwo70-MWcombustion-turbineunitswouldbeconstructedthroughouttheCookIn1etregion.Eachunitwouldoccupyatotalofapproximately5acres(2ha),foratotallandareaof50acres(20ha).Duringthedevelopmentoftheseplants,soilcompactionandacceleratederosionwouldbetheprimaryimpactofsiteconstructionactivities(vegetationstripping,surfacegradingandexcavation).Allunitsexceptthoselocatedsouth-eastofAnchorageandontheChuitnaRiverwouldbeonlevelterrainwhereerosionlosseswouldbeeasilycontrolledorminimizedbyconventionalconstructionpractices.DependingontheChuitnaRiverlocation,uncontrollederosionlossesduetoconstructioncouldbemoderatetosevere.AreasofagriculturallysuitablesoilsarepresentatthelowerBelugaRiverandKenaisitelocations.Morespecificsiteinformationwouldberequiredtodeterminewhetherthesesoilswouldbeaffectedbysitedevelopment.Becauseofthesmalltotalareasinvolvedineachunit,itislikelythatwithpropersiting,theseareasofagriculturallysuitablesoilscouldbeavoided.Nopermafrostormineralresourcesareknowntoexistinthevicinityofanyofthetensites.Anevaluationof theavailabilityofnaturalgasforthisscenarioispresentedinSection1.4.4.E.2.3.2Coal-FiredGenerationScenarioDevelopmentoftwo200-MWcoalunitsatWillowwouldrequirethedisturbanceof340acres(140ha)ofland(includingplantfacilities,coalstorageandhandlingfacilities,andflyashdisposalareas).Similarily,operationofthree200-MWcoalunitsatNenanawouldrequirethedisturbanceof435acres(180ha)ofland.Approximately900acres(360ha)oflandwouldbedisturbedforcoalminingoperationsduringtheassumed30-yearlifeof theWillowplants.Approximately1,350acres(550ha)wouldbedisturbedbycoalminingoperationsfortheNenanaplants.Theimpactsassociatedwithsurfacecoalminingactivitiesincludeincreasedsedimen-tationandwinderosionofsoilfromspoilpiles;modificationoftopographyandsurfacedrain-age,aswellasslopeinstabilitiesresultingfromsurfaceexcavations;andpermafrostthawduringsurfacestrippingofvegetation.Allearthworkactivities,suchasexcavation,grading,trenching,andsoiltreatment,wouldresultinincreasedratesoferosion,sedimentation,andrunoff;soilcompaction;andincreasedlevelsofpotentiallyhazardousmaterialsinsoilsasaresultofleachingfromexposedcoalmaterialsorspillsofmaterialsusedintheminingopera-tion(U.S.Dept.ofEnel'gy,1981).
E-55DevelopmentofthecoalunitsatWillowandNenanawouldimpactsomeagriculturallysuitablesoils,althoughthetotalareasofsuchsoilsthatwouldbeaffectedareunknown.Bothareasarelocatedinlevelterrain,anderosionlossesduetoconstructionactivitieswouldberela-tivelymoderate.ImpactsfrompermafrostthawareexpectedtoaffecttheNenanasiteonly.Nonon-coalmineralresourceswouldbeexpectedtobeimpactedineitherarea.Approximately155milliontons(140millionMT)ofcoalwouldbeconsumptivelyusedbythefive200-MWcoalunitsoverthe40-yearlifeof theplants.Theten70-MWcombustion-turbineunitsthatwouldbelocatedaroundtheCookInletwouldrequireabout5acres(2haleach.Impactssuchasincreasedsoilerosionandsoilcompactionwouldarisefromunitconstruction,excavation,grading,andvegetationstripping.Themagnitudeofsuchimpactswouldbehighlysite-specific.Astheexactlocationsforthecombustion-turbineunitshavenotbeenspecified,analysisofthespecificimpactsrelatedtoplantconstructionarenotpossibleatthistime.Theabsenceofpermafrostinthisregionprecludespermafrost-relatedimpacts.AnevaluationoftheregionalcoalresourcesavailableforuseunderthisscenarioispresentedinSection1.4.E.2.3.3CombinedHydro-ThermalGenerationScenarioE.2.3.3.1JohnsonThegeneralimpactsrelatedtothedevelopmentofthehydroelectricdamattheJohnsonsiteandtheappropriatemitigationmeasurestocontroltheimpactsaresimilartothosedescribedfortheWatanasiteinSectionE.2.1.1.GeneralimpactsandmitigationmeasuresrelatedtotheconstructionofaccessroutesandpowertransmissionfacilitiesarepresentedinSectionsE.2.1.3andE.2.1.4.Becauseof therelativelyflatopenterrainoftheTananaandJohnsonrivervalleys,theJohnsonreservoirwouldinundateanareaofabout84,000acres(34,000hal.Floodingofthereservoirwouldresultinthelossofsomeareasofpotentiallyagriculturallysuitablesoils.Themagni-tudeofthislosscannotnowbedeterminedatthistimebecauseonlyexploratorysoilsurveyinformationisavailable.AsdiscussedinSectionE.2.1.1,vegetationstrippingandreservoirfloodingmightresultinthethawofpermafrostdepositswithinthereservoirarea.Becauseofthelargearealextentofthereservoir,manymilesofbeachwouldbeformed.Thisbeachwouldbesusceptibletoerosion,slumping,andslidingwithreservoirfilling.Unconsolidatedmaterialsonthelowslopesthatwouldsurroundthereservoirmightbemostsusceptibletoflow-typefailures.Potentialseismicactivityinthevicinityof thedamandreservoirmightalsotriggerslopeinstabilitiesandslumping.Site-specificgeotechnicalinvestigationswouldberequiredtoallowtheevaluationoftheseimpacts.NoknownmineralresourcesareexpectedtobecoveredbytheJohnsonreservoir.Sandandgraveldepositsnearthesitemightbeusedforprojectconstructionpurposes.E.2.3.3.2KeetnaThegeneralimpactsrelatedtothedevelopmentofahydroelectricdamsiteattheKeetnasiteandtheappropriatemitigationmeasurestocontroltheseimpactswouldbesimilartothosedescribedfortheWatanasiteinSectionE.2.1.1.Approximately4,800acres(1,900haloflandwouldbeinundatedbytheKeetnareservoir.Noagriculturallysuitablelandorknownmineralresourceswouldbeflooded.Sandandgraveldepositsinthevicinityoftheproposedsiteareawouldbeavailableforconstructionpurposes.Slumpingandslopefailuremightbeexpectedintheglacialdepositsthatwouldcomposetheshorelineoftheproposedreservoir.Theisolatedpermafrostpresentinthefine-grainedsedimentsmightalsocontributetoshorelinefailures.Site-specificgeotechnicalinvestigationswouldberequiredtoevaluatethepotentialforfailuretooccurwithinthesedeposits.E.2.3. 3.3SnowThegeneralimpactsrelatedtothedevelopmentofahydroelectricdamsiteattheSnowsiteandtheappropriatemitigationmeasurestocontroltheseimpactsaresimilartothosedescribedfortheWatanasiteinSectionE.2.1.1.GeneralimpactsrelatedtotheconstructionofaccessroutesandpowertransmissionfacilitiesarepresentedinSectionsE.2.1.3andE.2.1.4.Becausethesiteislocatedinadeepbedrockgorge,only2,600acres(1,050haloflandwouldbeinun-datedbytheSnowreservoir.ThefewareasofsoilsintheSnowRiverValleythatwouldbefloodedbythereservoiraregenerallyagriculturallyunsuitable.Becauseofslopessurroundingtheproposedreservoirsitewouldbebedrock,noslumpfailureswouldbeexpected.Blockfailuresmightoccur;however,detailedgeotechnicalinvestigationswouldberequiredtoevaluatethepotentialfO)'suchfailures.AlthoughtheSnowsiteisinanareaidentifiedashavingthepotentia1forsevera1minera1resources,minera1c1aimsappeartobeconcentratedalongtheSnowRiverfromMoosePass,justnortheastof theprojectarea,toSeward;noknownmineralresourcesarepresentintherivervalley.Nopermafrost-relatedfailureswouldbeexpectedforthisarea.
E-56E.2.3.3.4BrowneThegeneralimpactsrelatedtothedevelopmentofahydroelectricdamattheBrownesiteandtheappropriatemit igationmeasurestocontro1theseimpactsare5imi1artothosediscussedinSectionE.2.1.1.TheBrownereservoirwouldinundate10,640acres(4,300ha)andwouldresultinthelossofsomeareasofpotentiallysuitableagriculturalsoils.Theexactmagnitudeofthis1055cannotbedeterminedatthistimebecau.seonlyexploratorysoilsurveyinformationisava"lable.DevelopmentoftheBrownealternativemightresultintheinundationofsub-bituminouscoalreservesoftheNenanacoalfield,butdeterminationoftheexactamountofcoalreser'vesthatwouldbelostduewouldrequiremoreextensiveinvestigation.Clayandcementmineralspresentintheareacouldbeusedforprojectconstruction.Extensives1umping,slopefailure,andbeacherosionmightbeexpectedtooccurinthesoftTertiarysedimentaryrocksoftheAlaskaRangefoothillsandtheextensiveunconsolidatedflood-plain,terrace,alluvial,anddriftdepositsthatarepresentthroughoutthereservoirsite.Permafrostthaw-relatedimpactswouldalsobeprobableinthisarea.Site-specificgeotechnicalinvestigationswouldberequiredtoevaluatethepotentialforfailuretooccurwithinthesedeposits.E.2.3.3.5BecausetheChakachamnaalternativewouldbealake-tap,noadditionalareaswouldbeinundated;thereforenoadditionallossofmineralorsoilresourceswouldbeexpectedasaresultofreservoirdevelopment.ChangesinlakedrawdownratesassociatedwiththedevelopmentoftheChakachamnaalternativemightaffectslopestabilitiesaroundthelake,however,andgeotech-nicalinvestigationswouldberequiredtoevaluatethepotentialforadditionalslopefailures.ThepresenceofMt.Spurr,anactivevolcano,adjacenttothelakewouldrequireextensiveconsiderationbecausereactivationofthisvolcanocouldseriouslyjeopardizethepowerfacility.Failureoftheexistinglakeduringavolcaniceventwouldbeindependentofthepowerdevelop-mentproject.E.2.3.3.6ThermalUnitsTheimpactsassociatedwiththeconstructionandoperationofa200-MWcoalunitatNenanaarediscussedinSectionE.2.3.2.Onecoalunitwoulduseapproximately21milliontons(19millionMT)ofcoaloverthe30-yearlifeoftheplant.Developmentofthree200-MWcombined-cycleunitsrequiretheuseofatotalof15acres(6ha)ofunitsnearAnchorageandthelowerBelugaRiver.theseunitsarediscussedinSectionE.2.3.1.ontheChuitnaandLowerBelugariverswouldland,aswouldthree70MWcombustion-turbineTheimpactsrelatedtothedevelopmentofE.2.4E.2.4.1SusitnaDevelopmentAlternativesE.2.4.1.1AlternativeDamLocationsandDesignsIneachofthethreeSusitnadevelopmentalternatives,developmentoftheWatanaIreservoirwouldresultinthecreationoffewermilesofbeachesandthefloodingoflesslandthanfortheproposedWatanaproject.Fromageologicandsoilsperspective,however,theincreasedareafloodedbytheproposedWatanaprojectisnotsignificantlyasneithervaluablemineralorsoilsresourceswouldbelostineithertheWatanaorWatanaIdevelopments.BecausetheWatanaIreservoirheightwouldbe100ft(30m)lowerthanfortheproposedWatanaproject,slopesta-bilityproblemsmightbemoreseverefortheWatanaIdevelopment(seeSec.E.2.2.1.1).Furthergeophysicalinvestigationswouldberequiredtosubstantiatethisexpectationhowever.BecausetheModifiedHighDevilCanyonandReregulatingdamreservoirswouldinundatelesslandthantheproposedDevilCanyonreservoir,thealternativescontainingthesetwooptionsmightbeconsideredpreferrabletotheWatanaI-DevilCanyonalternative.Asdiscussedabove,however,novaluablesoilormineralresourcesareknowntoexistintheproposedDevilCanyonreservoirarea,andfromageologicandsoilsperspective,theincreasedlossoflandattributabletothedevelopmentoftheDevilCanyonreservoirwouldnotbesignificant.BecauseslopefailureswouldbemorelikelytooccurintheupstreamportionsoftheproposedDevilCanyonreservoir,whichwouldalsobetheareaaffectedbytheModifiedHighDevilCanyonandReregulatingdamreservoirs,noalternativewouldbesuperior.BecausetheReregulatingdamwouldbesmallerthaneithertheModifiedHighDevilCanyonortheDevi1Canyondam,constructionmateda1requirementsandhenceborrowsitedevelopmentwouldbelessforthisalternative.Likewise,constructionmaterialrequirementswouldbelessforthe
E-57WatanaIdamthantheproposedWatanadam.Foranyofthealternatives,however,theconsump-tiveuseofthematerialsfordamconstructionwouldnotimpactthearea.IdentificationoftheborrowsitestobeusedforeachalternativewouldbeneededtoevaluatetherelativeerosionpotentialfortheSusitnaBasinalternatives.E.2.4.1.2AlternativeAccessRoutesBoththenorthernandsouthernaccessroutealternativeswouldnotrequirethedevelopmentofanaccessroadbetweentheWatanadamsiteandtheDenaliHighway,therebyeliminatingtheclearinganddisturbanceofapproximately630acres(250ha)ofpotentiallyerodableandpermafrostrichlandasrequiredfortheproposedaccesscorridor.Furthermore,absenceofthisaccessbetweenthedamsiteandtheDenaliHighwayforthealternativeswouldlimittheaccessibilityoftheBrushkanaandDevilCreekareatooff-roadvehicletrafficandtherebyreducetheerosionlossesthatmightbeexpectedintheareawiththedevelopmentofthissectionoftheproposedaccesscorridor.BetweentheDevilCanyonandWatanadamsites,boththenorthernandsouthernaccessroutealternativeswouldrequiremoreextensivesidehillexcavationthantheproposedaccessrouteandasaresult,erosionlosseswouldbeexpectedtobehigherforthesetwoalternativeroutesthanfortheproposedroute.BecausethesouthernalternativeaccessroutewouldrequirethedevelopmentofanaccesscorridorbetweenHurricaneandtheDevilCanyondamsite,aswellasbetweenGoldCreekandDevilCanyon,agreateramountoflandwouldbedisturbedforthisalternativethanforthenorthernalterna-tive(whichwouldrequireanaccesscorridorbetweenGoldCreekandDevilCanyononly).Develop-mentofarailaccessbetweenGoldCreekandDevilCanyonfortheproposedalternativewouldrequirelesslanddisturbancethanthenorthernaccessalternativeareabothbecauseoftheshorterdistanceandthenarrownessofarailcorridorincontrasttoaroadaccesscorridor.E.2.4.1.3AlternativePowerTransmissionRoutesIntheWi11ow-to-Anchoragesegmentofthetransmissionroute,Corridor3andtheproposedcorridor(Corridor2)wouldbesimilarinimpacts.ImpactsassociatedwithCorridor1mightbeassumedtobegreaterthanforeitherCorridor2or3becauseofitsgreaterlength[73mi(117km)forCorridor1comparedwithabout38mi(61km)fortheothertwocorridors].However,asCorridor1parallelsexistingtransmissionlinesandhighwaysformuchofitslengthbetweenWillowandAnchorage,theactualamountoflanddisturbedforaccessroadandright-of-waydevelopmentmightbesimilarorlessthanforeitherCorridor2or3,whichdonotfollowexist-ingrightofways.AlthoughanumberofpossibletransmissionroutealternativeswereproposedfortheDams-to-GoldCreeksegment,onlythesouthernmostcorridors(Corridors1,3,13,andtheproposedCorridor14)wereconsideredbytheApplicant.BetweenWatanaandDevilCreekdamsitesmoreruggedtopog-raphyiscrossedbyCorridors1and13thanbyCorridor3andpl'oposedcorridor.BetweenGo1dCreekandDevilCanyon,Corridor3crossesmoreruggedterrainthantheproposedcorridor.Asaresult,erosionlossesduringtheconstructionoftheproposedtransmissionlinewouldbeexpec-tedtobelessthanforthealternativecorridors.Furthermore,asthetransmissionlinewouldbewithintheproposedaccesscorridor,additionalaccessrequirementsforthetransmissionlineconstructionandmaintenancewouldbeminimized,andoff-roadvehicleaccesswouldbeconfinedtotheproposedaccesscorridor.Impactsrelatedtoaccessroaddevelopmentandoff-roadvehicletrafficwouldthereforebeminimizedfortheproposedroute.IntheHealy-to-Fairbankssegment,theproposedcorridor(Corridor1),although4mi(6km)longerthanCorridor2,parallelsexistingaccessroutesforalmostitsentirelength,therebyreducingimpactsrelatedtoaccessroaddevelopment.Corridor2,althoughtheshortestofthealternatives,crossesmorewetlandsthanCorridor1andlacksexistingright-of-waysalongmostofitslength.Corridor3,thelongestofthealternativesinthissegment,wouldrequireextensivevegetationclearingintheTananaandWoodriverfloodplainsthatcouldresultinextensiveerosionandsoildisturbances,andpassesthroughmountainousareaswhereerosionlossesmightbegreat.Corridor3alsolacksright-of-wayaccess.E.2.4.2Non-SusitnaGenerationAlternativesE.2.4.2.1Natural-Gas-FiredGenerationScenarioUnderthenatural-gas-firedgenerationscenario,atotalof50acres(20ha)oflandwouldbedisturbedbytheconstructionofthe tengas-firedplantsincontrasttothe42,000acres(17,400ha)of1andthatwouldbeinundatedbytheproposedl'eservoirsalone.Withproperconstructionpractices,thetotalerosionlossesforthisscenariowouldbeaninsignificantfractionoftheproposedprojecterosionlosses.Similarly,nopermafrost-relatedorslope-relatederosionalimpactswouldbeexpectedforthisscenarioincontrasttopotentiallyexten-siveimpactsfortheproposedproject.
E-58IncontrasttotheproposedSusitnaproject,smallareasofagriculturallysuitablelandcouldbedisturbedbythedevelopmentofthegas-firedplants.Withpropersiting,however,theseimpactscouldbeavoided.Todatenovaluablemineralresourcesareknowntooccurintheproposedsiteareaorwouldbeimpactedbytheproposedprojectdevelopment.Likewise,withadequatesitingprecautionsnoimpactstomineralresourcesintheCookInletareawouldbeexpectedasaresultofthedevelop-mentofthegas-firedunits.Naturalgasreserveswouldbeusedconsumptivelyunderthisscenario,however.E.2.4.2.2Coal-FiredGenerationScenarioUnderthecoalscenario,asmuchas3,000acres(1,200ha)oflandwouldbedisturbedbytheconstructionandoperationofthefive200-MWcoalunits;thiswouldapproachinmagnitudetheamountoflandthatwouldbeinundatedbytheproposedDevilCanyonreservoir.However,totallanddisturbancesforboththeWatanaandDevilCanyondevelopments(includinglanddisturbedbyreservoirinundationandreservoirslopeinstability)wouldbefarinexcessoflanddisturbanceunderthecoal-firedscenario.Ingeneral,theerosionimpactsrelatedtosurfacecoalmlnlngactivitieswouldbesimilarinnaturetothoseforconstructionactivitiesfortheproposedproject,butthemagnitudeofsucherosionlosseswouldbeexpectedtobegreaterfortheproposedproject.Coalmining,coalstorageandhandling,andflyashdisposalpracticescouldresultintheleachingofpotentiallyhazardousmaterialsfromtheexposedcoaltonearbysoils.Nosuchimpactwouldbeexpectedastheresultoftheproposedprojectactivities.DevelopmentofthecoalunitsattheWillowandNenanasiteswouldhavethepotentialtoaffectsmallareasofagriculturallysuitableland.Incontrast,noagriculturallysuitablelandexistsintheproposedprojectarea.Althoughnoknownmineralresourceswouldbeaffectedbytheproposedproject,thecoal-firedscenariowouldrequiretheconsumptiveuseofapproximately107milliontons(97millionMT)ofcoaloverthe30-yearlifeofthefive200-MWunits,whichwouldbeequivalenttoapproximately18%oftheprovenNenanacoalfieldreservesor56%oftheprovenBelugacoalfieldreserves(seeSec.1.4).E.2.4.2.3CombinedHydro-ThermalGenerationScenarioJOHNSONTheJohnsonreservoirwouldinundateanareatwicewhatwouldbeinundatedbytheWatanaandDevilCanyonreservoirscombined.BecauseoftheextentoftheJohnsonreservoir,theperma-frostandunconsolidatedsurficialdepositsintheJohnsonarea,slopefailureandpermafrost-thaw-relatedimpactswouldbeexpectedtobegreaterfortheJohnsonprojectthanforthepro-posedproject.NoknownmineralresourceswouldbeinundatedbyeithertheJohnsonortheproposedreservoirs.AnasyetundeterminableamountofagriculturallysuitablelandwouldbeinundatedbytheJohnsonreservoir,whereasnonewouldbelostbydevelopmentoftheproposedproject.KEETNATheKeetnareservoirwouldinundateaboutonetenththeareathatwouldbefloodedbytheproposedproject.ReservoirslopefailuresandslumpingwouldbeexpectedintheglacialdepositspresentatKeetnasite,althoughthemagnitudeoftheareasaffectedbysuchfailuresmightbelessfortheKeetnaalternativethantheproposedprojectasaresultofthesmallerreservoirperimeter.NoagriculturallysuitablelandorknownmineralresourceswouldbefloodedbyeithertheKeetnaortheproposedproject.SNOWTheSnowreservoirwouldinundateonlyabout6%ofthetotalareathatwouldbefloodedbytheproposedproject.BecausetheSnowsiteisinadeepbedrockgorgeandbecauseofitssubstan-tiallysmallerreservoirperimeterrelativetotheproposedreservoirs,reservoirslope-relatedfailureswouldbesubstantiallylessthanfortheproposedproject.Permafrost-relatedimpactswouldbeexpectedfortheproposedprojectonly.NoagriculturallysuitablesoilsorknownmineralresourceswouldbefloodedbyeithertheSnowortheproposedprojects.BROWNETheBrownereservoirwouldinundateanareaaboutonequarterthesizeoftheproposedreservoirs.TheBrownereservoir,un1iketheWatanaandDevi1Canyonreservoirs,wouldinundatesomeareas
E-59ofpotentiallyagriculturallysuitablesoilsandmightresultinthefloodingofsomesubbitumi-nouscoalreservesoftheNenanacoalfield.Reservoirslopefailureandpermafrost-thaw-relatedimpactswouldoccurunderthisalternative.However,becausetheBrownereservoirperimeterwouldbeconsiderablysmallerthanthatoftheproposedproject,themagnitudeoftheimpactsrelatedtothedevelopmentoftheBrownereservoirwouldbeexpectedtobesubstantiallylessthanfortheproposedproject.CHAKACHAMNABecausetheChakachamnaalternativewouldbealake-tap,noadditionalareaswouldbeinundated,and,asaresultnoknownmineralresourcesoragriculturallysuitablesoilswouldbeimpactedbytheChakachamnaalternative.Similarlynoknownmineralresourcesoragriculturallysuitablesoilswouldbelostbythedevelopmentoftheproposedproject.SlopestabilitiesaroundLakeChakachamnawouldbeaffectedbychangesinlakedrawdownasaresultoftheoperationofthelaketap.Althoughthemagnitudeofsuchslopefailureisunknownatthistime,itshouldbesubstantiallylessthantheslopefailureimpactsthatwouldbeexpectedfortheproposedproject.NopermafrostimpactswouldbeexpectedfortheChakachamnaalternative.THERMALUNITSInconjunctionwiththedevelopmentofaspecifichydrosite,minorareaswouldbedisturbedbytheconstructionofcombined-cycleandcombustion-turbineunitsintheCookInletarea.TherelationofsuchimpactstotheproposedprojectarediscussedinSectionsE.2.4.2.1andE.2.4.2.2.E.3MITIGATIONThemethodsproposedbytheApplicantfordealingwithexpectedimpactsfortheproposedprojectarediscussedasappropriateinSectionE.2.1.Ingeneral,thesemitigativemeasuresarefeltbytheStafftobeadequatetoreducethemajorityofproject-relatedimpactstotheextentpossible.Severalsignificantimpactsassociatedwithreservoirdevelopment,however,wouldbeunavoidable.Includedarethelossofinundatedland,reservoirslopeinstability,andseis-micallyinducedlandfailures.AnadditionalmitigativemeasurethatshouldbeconsideredbytheApplicantistheconsultationandinvolvementofstategeologicandsoilconservationagenciesintheanalysisofallsite-specificconstructionplansforallprojectfacilities.Thisconsultation,inconjunctionwiththeproposedgeotechnicalstudies,shouldensureminimizationofallpotentialconstruction-relatedimpacts.REFERENCESFORAPPENDIXEAcresAmericanInc.Undated.SusitnaHydroelectricProjectGeotechnicalReport.1980-1981.FinalDraft.AlaskaDepartmentofNaturalResources.1982.PreliminaryAnalysisoftheDirectorRegardingProposedBe1ugaCoalLeaseSa1e.DivisionofMinera1sandEnergyManagement.Anchorage.BechtelCivilandMinerals,Inc.AssessmentReport.Vol.1.1983.ChakachamnaHydroelectricProjectInterimFeasibilityPreparedfortheAlaskaPowerAuthority.Cobb,E.H.1974.SynopsisoftheMineralResourcesandGeologyofAlaska.U.S.GeologicalSurveyBulletin1307.53pp.CommonwealthAssociates,Inc.TransmissionLineRoute.1982.GeotechnicalInvestigationAnchorage/FairbanksIntertiePreparedwithShannon&Wilson,Inc.,forAlaskaPowerAuthority.Csejtey,B.,Jr.,etal.1978.ReconnaissanceGeologicMapandGeochronology.TalkeetnaMountainsQuadrangle,northernpartofAnchorageQuadrangleandsouthwestcornerofHealyQuadrangleAlaska.U.S.GeologicSurveyOpenFileReport78-558-A.Edgar,D.E.,L.J.OnestiandG.M.Kaszynski.1982.AlaskanCoal:ResourcesandDevelopmentConstraints.ANL/LRP-18.ArgonneNationalLaboratoryfortheU.S.DepartmentofEnergy.Ferrains,O.J.,Ji'.,R.KachadoorianandG.W.Greene.1969.PermafrostandRelatedEngineeringProblemsinAlaska.U.S.GeologicalSurveyProfessionalPaper678.37pp.Furbush,C.E.andD.B.Schoephorstei'.1977.SoilSurveyofGoldstream-NenanaArea,Alaska.U.S.DepartmentofAgricultureSoilConservationServiceincooperationwithUniversityofAlaska,InstituteofAgriculturalSciences.
E-60Harza-EbascoSusitnaJointVenture.1983.SusitnaHydroelectricProject.WatanaDevelopment.Winter1983.GeotechnicalExplorationProject.Vol.1.MainReport.PreparedfortheAlaskaPowerAuthority.Anchorage.Merritt,R.D.,G.R.EakinsandJ.G.Clough.1982a.CoalInvestigationoftheSusitnaLowland,Alaska.AlaskaOpen-fileReport142.AlaskaDepartmentofNaturalResources,DivisionofGeologicalandGeophysicalSurveys.42pp.Merritt,R.D.,G.R.EakinsandJ.G.Clough.1982b.CoalpotentialmapoftheSusitnalowland,Alaska.In:CoalInvestigationoftheSusitnaLowland,Alaska.AlaskaOpen-fileReport142.AlaskaDepartmentofNaturalResources,DivisionofGeologicalandGeophysicalSurveys.Merritt,R.D.,G.R.EakinsandJ.G.Clough.1982c.Bedrock-geologyandstructuremapoftheSusitnalowland,Alaska.In:CoalInvestigationoftheSusitnaLowland,Alaska.AlaskaOpen-fileReport142(Plate1of4).AlaskaDepartmentofNaturalResources,DivisionofGeologicalandGeophysicalSurveys.Pewe,T.L.1975.QuaternaryGeologyofAlaska.U.S.GeologicalSurveyProfessionalPaper835.145pp.R&MConsultants.1981.SusitnaHydroelectricProject.TransmissionCorridorTerrainUnitMaps,PhotoInterpretation,SouthandNorthInterties,13maps,SummaryReport,andTerrainUnitPropertiesandEngineeringInterpretation.Rawlinson,S.E.andS.B.Hardy.1982.PeatResourceMapofAlaska.AlaskaOpen-fileReport152.AlaskaDepartmentofNaturalResources,DivisionofGeologicalandGeophysicalSurveys.RiegerS.,J.A.DementandD.Sanders.1963.SoilSurveyofFairbanksArea,Alaska.U.S.DepartmentofAgriculture,SoilConservation,incooperationwithAlaskaAgriculturalExperimentStation.Rieger,S.,D.B.SchoephorsterandC.E.Furbush.1979.ExploratorySoilSurveyofAlaska.U.S.DepartmentofAgriculture,SoilConservationService.Schoephorster,D.B.1968.SoilSurveyofMatanuskaValleyArea,Alaska.U.S.DepartmentofAgricultureSoilConservationServicewiththeAlaskaAgriculturalExperimentStation.Schoephorster,D.B.andR.B.Hinton.1973.SoilSurvey,SusitnaValleyArea,Alaska.U.S.DepartmentofAgricultureSoilConservationServiceincooperationwiththeUniversityofAlaskaInstituteofAgriculturalSciences.Selkregg,L. L.(ed.).1974.AlaskaRegionalProfiles-SouthCentralRegion.UniversityofAlaskaArcticEnvironmentalInformationandDataCenterfortheStateofAlaska,OfficeofGovernor,andtheJointFederal-StateLandUsePlanningCommissionforAlaska.Selkregg,L. L.(ed.).1977.AlaskaRegionalProfiles-YukonRegion.UniversityofAlaskaArcticEnvironmentalInformationandDataCenterfortheStateofAlaska,OfficeofGovernor,andtheJointFederal-StateLandUsePlanningCommissionforAlaska.Simpson,D.W.,andS.Kh.Negmatullaev.1978.InducedseismicitystudiesinSovietCentralAsia.EarthquakeInformationBulletin10(6):209-213.U.S.DepartmentofEnergy.1981.CoaltoMethanol,FeasibilityStudy.BelugaMethanolProject.FinalReport.Vol.IV.Environmental.PreparedbyCookInletRegion,Inc.,andPlacerAmex,Inc.Woodward-ClydeConsultants.1982.FinalReportonSeismicStudiesforSusitnaHydroelectricProject.Subtasks4.09through4.15.PreparedforAcresAmerican,Inc.
DRAFTENVIRONMENTALIMPACTSTATEMENTSUSITNAHYDROELECTRICPROJECT,FERCNO.7114APPENDIXFLANDUSEpreparedbyR.C.SundellArgonneNationalLaboratory
F-3APPENDIXF.LANDUSEF.lAFFECTEDENVIRONMENTF.l.lIntroductionThefacilitiesoftheproposedSusitnaprojectwouldbelocatedprimarilyinSouthcentralAlaska.SomeprojectfeaturesandtransmissionlinecorridorsalsowouldextendintotheInteriorRegion.AnchorageandFairbanksarethemajorpopulationcentersofthestate;other,smallercommunitiesarescatteredalongthefewtransportationroutes(e.g.,GeorgeParksHigh-way).Muchoftheregionissparselyinhabited,withrecreationbeingtheprimarylandusebyman.Scatteredtimberandminingactivitiesdooccurthroughouttheregion,andsomeagricultureofactivitiesoccurinafewrivervalleys.MostcommercialandindustrialdevelopmentsintheregionarelocatedinFairbanksandAnchorage.TheenactmentoftheAlaskaStatehoodActof1958,theAlaskaNativeClaimsSettlementActof1971,andtheAlaskaNationalInterestLandsConservationActof1981hasplacedmuchofthelandinAlaska,includinglandinthevicinityofvariousproposedprojectfeatures,inastateoftransitionofownershipandmanagement.TheStatehoodActauthorizedthestatetoselectover100millionacres[40millionhectares(ha)JofFederallandinAlaska.TheAlaskaMunicipalCodeallowstheboroughswithinthestatetoselect10%ofthevacantunreservedstatelandholdingswithinboroughboundariesformunicipalpurposes.UndertheAlaskaNativeClaimsSettlementActpassedbyCongressin1971,AlaskaNativesreceivedover40millionacres(16millionha)oflandandapproximately$1billion.NineregionalcommissionsandassociatedAlaskaNativevillageswereincorporatedunderstatelawtoselectandmanagetheselands.TheAlaskaNationalInterestLandsConservationActof1981placedover100millionacres(40millionha)ofFederallandsinvariousconservationsystemsmanagedbysuchFederalagenciesastheBureauofLandManagement,Nationa1ParkService,FishandWildlifeService,andtheForestService.Asaresultoftheseactions,thereisagreatdealofuncertaintyregardingownershipstatusoflargeamountsoflandinthestate.When1andtransfersandconveyancesarecompleted,theFederalgovernmentwi11ownandmanageabout225millionacres(91millionha),orabout60%ofthelandinAlaska.Thestatewillcontrolnearly28%andtheNativesnearly12%,leavinglessthan1%ofthelandinprivateownership(U.S.GeneralAccountingOffice,1982).Futureuseoflandsinthestudyareawilldepend,inpart,onfinalownershipdecisions.Landvalueinformationforspecificlandparcelsisoftenunknown.F.1.2ProposedProjectThesitesoftheproposedWatanaandDevilCanyondamsandrelatedfacilities,includingborrowareas,constructioncampsandsettlementareas,accessroads,andtheWatana-to-Go1dCreektransmissionlinesegment[37miles(mi),or60kilometers(km)10ngJarewithintheupperandmiddleSusitnaRiverBasin.The330-mi(530-km)powertransmissionlinecorridorbetweenFairbanksandAnchoragewouldextendthroughportionsoftheTanana,Nenana,Chulitna,andSusitnariverbasinsandparallelsectionsoftheGeorgeParksHighway(Route3)andAlaskaRailroad.ThelocationsofthesevariousprojectfeaturesinrelationtotheupperandmiddleSusitnaRiverBasinandtheFairbankstoAnchorageareasareshowninFigure2-1.F.1.2.1UpperandMiddleSusitnaRiverBasinF.1.2.1.1ExistingandFutureUsesPatternsofhumanlandusewithintheupperandmiddleSusitnaRivet'Basinarecharacterizedbyscatteredareasoflowintensity,butsomewhatdiverseuses(seeFig.F-1).Thetypeofuseisinpartdependentonseasonalchange.Thereat'eessentiallynomajorareasofagriculture,timbering,orresidential,commercial,orindustrialactivitieswithinthearea.Theprimarylanduseisrecreation.Developmentwithintheupperandmiddlebasingenerallyconsistsofindividualcabinsorsmallclustersofcabins.Groundaccessintotheareaisextremelylimited,andtheprimarylanduseisrecreation.Concerningfuturelandusedevelopmentandactivities,nosignificantchangeincurrenttypesorintensityofuseisanticipatedfortheupperandmiddleSusitnaRiverBasinunlesstheproposed
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LEGEND
SCALE ?3 6 9 MILESI
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IEEillIE
l\S~
[::,:,;,::',:,::'::1
LIt i
LOW
MEDIUM
LO'N
MEDIUM
INTENSITY
RECREATION
RECREATION /
RESIDENTIAL
MINING
MINING/
RESIDENTIAL
USE
Figure F-l.Land Use Patterns within the Upper and Middle Susitna River Basin.
[Source:Exhibit E,Vol.8,Chap.9,Fig.E.9.8]
F-5projectisdeveloped.Inthefuture,significantlandusechangewithinthebasinareawouldonlybegintooccurwiththedevelopmentofaroadsystem.AGRICULTURALRESOURCELANDSNolarge-scalefarmingactivitiesoccurwithintheupperandmiddleSusitnaRiverBasin.TheU.S.SoilConservationServicehasdeterminedthattherearenoprimeoruniquefarmlandsorrangelandslocatedinthemiddleSusitnaRiverBasinstudyarea(ExhibitE,Vol.8,p.E-9-27).*Ingeneral,agriculturalactivitieswithinAlaskaareconfinedtorelativelysmallareas,andthereapparentlyisverylittleadditionallandsuitableforagriculturaldevelopment(AlaskaCropLivestockReportingService,1978).ThelargestagriculturalareasinthestateincludetheTananaValley,MatanuskaValley,KenaiPeninsula,asectionofthesoutheasternpanhandle,andasectionoftheSouthwesternPeninsula--alloutsidetheupperandmiddleSusitnaBasin(AlaskaNorthwestPublishing,1981).FORESTRESOURCELANDSTimberresourceswithintheupperandmiddleSusitnaRiverBasinareaarevirtuallyundisturbedexceptforlimitedusebylocalresidentsasabuildingmaterialandheatingfuel.LandswithhighestcommercialforestrypotentialwithintheareaarelocatedalongtheSusitnaRiverdown-streamfromtheconfluencewithPortageCreek,essentiallywithinthefloodplain.WithintheWatana-to-GoldCreekarea,forestvegetationtypesarelocatedatthelowerelevations[belowabout3,000feet(ft),or900meters(m)]andcovermorethan860,000acres(348,000ha)ormorethan20%ofthearea(ExhibitE,Vol.6A,Chap.3,p.E-3-204).About19%oftheforestedareasconsistsofconifers,principallywhiteorblackspruce.Whitespruceismostvaluedforsawtimberandhouselogs;blackspruceisasecondchoiceforhouselogs.Theremainderoftheforestedareaconsistsofdeciduousstandsofpaperbirch,balsampoplar,andtremblingaspenormixedstandsofconiferousanddeciduoustrees.Manyofthebirchstandsaretooyoungforindustrialusesotherthanforpulp,butsomestandsaresatisfactoryforveneerorfurniture.Birchisalsothemostpopularfirewoodtype.Cottonwoodisoftenusedforroughcutlumber(AlaskaDept.ofNaturalResources,1982).TheforestcoverisdescribedindetailinSec-tion3.1.5.1andAppendixJ.MINERALRESOURCELANDSPartoftheupperandmiddleSusitnaRiverBasinislocatedintheMatanuska-Susitna(Mat-Su)Borough.GoldhasbeentheprimarymineralminedintheMat-Suregionforthelast80years.PlacerminesworkingalluvialdepositsformineralsarelocatedatsitesthroughouttheentireMat-SuBorough.Atpresent,significantquantitiesofoilandgasandsandandgravelarealsobeingextracted(AlaskaDept.ofNaturalResources,1982).CoaldepositsofvaryingqualityarelocatedthroughouttheMat-SuBorough,andfurthercoaldevelopmentmayexpandmineralproduc-tion.ThepotentialalsoexiststhroughouttheMat-Suregionforfurtherdevelopmentofmetallic(e.g.,gold,copper,tin)andnonmetallic(e.g.,limestone,gypsum)minerals.WithintheupperandmiddleSusitnaRiverBasin,mineralexplorationandminingactivitieshavebeenlimited(Fig.F-1).Scatteredminingclaimshavebeenoperatedintermittentlyinthearea.Therecurrentlyarelessthan50miningclaimsinthestudyarea;threegoldclaimsthatwereactivefrom1976to1978arelocatedwithintheareathatwouldbeinundatedbytheproposedWatanareservoir(TerrestrialEnvironmentalSpecialists,1982).ThemostactiveminingareaswithintheupperandmiddlebasinarearoundGold,Chunilna(Clear),andPortagecreeks.GoldplacerminesarestillbeingworkedonChunilnaCreek.Gold,copper,andsilverplacermineswereactiveonGoldCreekuntilthelate1970s.ThePortageCreekareahaddepositsofsilver,copper,magnesium,zinc,andmolybdenum.Alltheclaimswerelode(compositemineralvein)deposits,andatpresent,onlyoneclaimisstillactive(TerrestrialEnvironmentalSpecialists,1982).SomeactiveclaimsalsoarelocatednearStephanandFoglakes,JayCreek,andintheWatanahillstotheeastofJayCreek(ExhibitE,Vol.8,Chap.9,p.E-9-18).NocoaliscurrentlyminedintheupperandmiddleSusitnaRiverBasinarea(ExhibitE,Vol.8,Chap.3,p.E-9-18).RECREATIONLANDSANDNATURALAREASAspreviouslyindicated,theupperandmiddleSusitnaRiverBasinisgenerallyinanaturalstatewithouthumandevelopmentexceptforsomescatteredcabinsandafewplacermines."'Throughoutthisdocument,referencestospecific"Exhibits"aretotheexhibitssubmittedtoFERCaspartofAlaskaPowerAuthority'sSusitnaHydroelectricProjectLicenseApplication.Referencestospecific"Appendices"(App.)aretotheappendicesprovidedinVolumes2through7ofthisDraftEnvironmentalImpactStatement.
F-6A1thoughtheareamaynotbeconsideredbysomeasaestheticorpicturesqueasotherpartsofAlaska,theexistenceofadiverselandscapeinabasicallyroadlessandsparselyinhabitedareaoffersavarietyofviewsandrecreationalopportunitieswithinanaturalsetting.Accordingly,theprimarylanduseactivitywithinthestudyareaisrecreation.Recreationactivitiesoccur-ringintheareaincludehunting,fishing,boating,canoeing,kayaking,camping,andcross-countryskiing.AmoredetaileddiscussionofrecreationalactivitieswithintheupperandmiddleSusitnaRiverBasinareaispresentedinSection3.1.7andAppendixL.Duringthepastdecade,themiddleSusitnaRiverBasinhasbeenevaluatedbyvariousstateandFederalagenciesforitsnaturalattributes.Todate,theareahasnotmetthecriteriarequiredforinclusioninanyofthefollowingprograms:NationalPark-PreserveSystem,NationalorHistoricLandmarkStatus,WildernessPreservationSystem,NationalForestSystem,orStateParkSystem.TheSusitnaRiverhasnotbeenstudiedforinclusionintheNationalandWildScenicRiverSystem(ExhibitE,Vol.8,Chap.7,p.E-7-16).TRANSPORTATIONANDUTILITYCORRIDORSFewhighwayormajorutilitycorridorspassthroughtheupperandmiddleSusitnaRiverBasinarea.HighwaytransportationtoorwithintheareaisconfinedtotheDenaliHighway(Route8)tothenorth(closedinwinter),GeorgeParksHighway(Route3)tothewest,RichardsonHighway(Route4)totheeast,andGlennHighway(Route1)tothesouth.Groundaccessintotheareaisextremelylimitedandconsistsofanetworkofconnectingtrails.Modesoftravelwithintheinteriorportionofthebasinincludewalking,dog-sledding,snow-shoeing,cross-countryskiing,all-terrainvehicles,trackedvehicles,andfour-wheeldrivevehiclesonland;boats,canoes,kayaks,andraftsalongrivers,streams,andlakes;andairplanes,floatplanes,andhelicoptersbyair.SETTLEMENTAREASANDSPECIALUSELANDSBecauseoflimitedaccess,littledevelopmenthastakenplaceintheupperandmiddlebasinarea.Asindicatedabove,theiparsedevelopmentthatdoesexistgenerallyconsistsofsinglecabinsandsmallclustersofcabins.Someofthesestructuresareusedyeararound,whileothersareusedonlyseasonallyorhavebeenabandoned.Thereareabout110structureswithin18mi(30km)oftheSusitnaRiverbetweenGoldCreekandTyoneRiver(TerrestrialEnvironmentalSpecialists,1982).Almost20%ofthesestructuresareassociatedwiththefourlodgeslocatedalongTsusenaCreeknearTsusenaButte,HighLake,StephanLake,andChulitnaRiverLodge(Fig.F-2andTableF-1).ThegreatestconcentrationofdevelopmentisintheStephanLakearea,wherethereare13isolatedcabinsandonelodgewithout-buildings,andatChunilnaCreek,wherethereisanairstrip,severalsmallmines,and19cabinsandrelatedstructures(TerrestrialEnvironmentalSpecialists,1982).Inadditiontothefourlodgeareas,concentrationsofresidences,cabins,andotherstructuresoccurnearOtterLake,PortageCreek,GoldCreek,ChunilnaCreek,ClaranceLake,andBigLake(TerrestrialEnvironmentalSpecialists,1982).Manyofthesecabinsare,orwere,usedonaintermittentbasisbytrappers,hunters,fishermen,andotherrecreationists.LocationsofthesestructuresareshowninFigureF-1.MuchofthelandwithintheupperandmiddleSusitnaBasinappearsincapableofsupportingsignificanthumansettlement(AlaskaDept.ofNaturalResources,1982).Basedonevaluationofsuchphysica1factorsasslope,soildrainage,soilload-bearingcapacity,these1andshavemoderatetoseverebuildinglimitation.CommunityandsettlementareasintheupperandmiddleSusitnaBasinarefurtherdiscussedinAppendixNNospecialuselands(suchasmilitarybasesorreservations,firingranges,testingortrainingareas)havebeenidentifiedwithintheupperandmiddleSusitnaRiverBasinarea.WETLANDSANDFLOODPLAINSWetlandscoveralargeportionofthemiddleSusitnaRiverBasin.TheseareasincluderiparianzonesalongthemainstemSusitna,sloughs,andtributarystreams,aswellasnumerouslakesandpondsonuplandplateaus.WetlandareasofparticularimportanceincludeportionsofBrushkanaCreek;UpperDeadmanCreek;theareabetweenDeadmanandTsusenacreeks;theareasaroundFog,Stepllen,andSwimmingBearlakes;andinthevicinityofJackLongCreek(ExhibitE,Vol.8,Chap.9,p.E-9-21).ManyoftheproposedWatanaandDevilCanyondamprojectfeatureswouldbelocatedinwetlandareas.ThesewetlandareasaredescribedindetailinSection3.1.5.1andAppendixJ.Atpresent,littlefloodplaininformationisavailablefortheSusitnaRiver.The100-yearfloodplainfortheproposedreservoirareasisshowninFigures2-2and2-6.F.l.2.1.2OwnershipStatusandManagementMostofthelandintheupperandmiddleSusitnaRiverBasiniscurrentlyownedbytheU.S.GovernmentandmanagedbytheBureauofLandManagement.Therearetwostatelanddisposal
"I
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82~-87
84
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77 ~
78 ~~81~
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SIJSITNA RIVER
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-110 2--'STEPHAN
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14
15 38_20 _-2.
HIGH
t)KE
28--30
c¢£'i-
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@
SCALE 9 3 6 9 MILES
•
Figure F-2.Location of Existing Structures within the Upper and Middle Susitna Basin
(Numbers are keyed to Table F-l).[Source:Exhibit E,Vol.8,Chap.9,
Fig.E.9.9]
Table F-1.Description and Location of Existing Structures within the Upper and Middle Susitna River Basil]
Map
Locationt l
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Structure
Cabin;meat
house
Boat cabin
Cabin;shed
Cabin
Cabin
Cabin
foundations
Cabin;shed
Cabin
Stephen Lodge
(10 structures)
Cabin;shed
Cabin;shed
Cabin;shed
Cabin;shed
Cabin;shed
Cabin;shed
Zonet 2
2
1
2
2
1
2
2
2
2
2
2
Location
Lake E.of Stephan Lake,
1850 ft elevation
S.bank Susitna:on
tributary 3 mi S.W.
of Fog Creek/Susitna
Confluence
N.W.shore of Stephan
Lake
Tsusena Creek:3.5 mi
from Tsusena/Susitna
confluence
N.shore of Susitna:
W.bank of 1st tribu-
tary W.of Tsusena/
Susitna confluence
S.shore of Fog Lake #2
On knob of Fog Lake #1
W.central shore of
Stephan Lake
0.5 mi S.W.of
Stephan Lodge on
Stephan Lake shore
E.shore of Stephan Lake
E.shore of Stephan Lake
Accesst 3
Floatplane,skis
Boat,foot
Airplane
Foot,dog·team
Foot,dog team
Floatplane
Airplane
Airplane,foot
Airplane,foot
Airplane,foot
Airplane,foot
Currently
Maintained
Yes
Yes
Yes
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Use Status
Built in 1960s and in current use
for seasonal hunting,fishing,and
boating.
Built in 1960s for Stephan Lake
Lodge;currently used seasonally by
Stephan boating/hunting guests.
Built 1960s and in current use for
seasonal hunting,fishing,and
boating.
Built in 1940s as a trapline cabin
and used until late 1950s;no longer
in use.
Built in 1939 by Oscar Vogel as a
trapping line cabin;used until late
1950s,now collapsed;no longer
used.
Built in 1960s and currently being
used as a seasonal fishing and
hunting cabin.
Built in 1960s and currently being
used as a seasonal hunting and
fishing cabin.
Built in 1960s and in current use as
hunting,fishing,and recreation
lodge;can accommodate up to 35
guests;operates year-round.
Built in 1960s and in current use
seasonally as a hunting and fishing
cabin.
Hunting,fishing,boating,seasonal
use;built in 1960s.
Built in 1960s and in current
seasonal use as hunting,fishing,
and boating cabins.
.."
I
ex>
Map
Locationtl Structure Zonet 2 Location
Table F-l.(Continued)
Accesst 3
Currently
Maintained Use Status
16
17
18
19
20
21
22
23
25
26
27
Cabin;shed
Cabin
Cabin
Cabin;meat
house
Cabin;shed
Cabin;shed
Cabin;shed
Cabin;shed
Mining
buildings
(5)
Cabins (2)
Cabins (2)
2
2
2
3
3
2
2
2
Mouth of Prairie
Creek at Stephan Lake
W.shore of Prairie
Creek
E.shore of Murder
Lake (S.of Stephan
Lake)
S.E.shore of Daneka
Lake
Prairie/Talkeetna
confl uence
Game Lake
Portage Creek:2.5 mi
N.of Portage/Susitna
confl uence
1 mi N.of Portage
Creek mining
N.W.shore of Dawn Lake
Airplane,foot,
horse
Airplane,foot
Airplane,foot
Airplane,foot
Foot,dog team,
boat
Airplane,foot
Airplane,ATV,
foot,dog team,
horse
Airplane,ATV,
foot,dog team
Airplane,ATV,
horse,dog team
No
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Built in 1940s and used until late
1950s as a hunting,fishing,and
trapping base and residence;no
longer used.
Built in 1960 and 1979,respec-
tively,and currently used as a
year-round residence from which
hunting,fishing,and trapping
occur.
Built in 1960s and used as a
year-round residence;hunting and
fishing.
Built in 1960s and currently used on
a seasonal basis for hunting,
fishing,and recreation by guests of
Stephan Lodge.
Built in 1960s and currently used
seasonally by Stephan Lodge for
purposes of fishing and hunting.
Built in 1940s and used since then
for trophy game hunting;now a part
of Stephan Lodge's series of out-
reach cabins used on a seasonal
basis.
Mining records exist as far back as
1890s;mined 1920 and sporadically
1930s,then 1950-1970s;currently
inactive mining operations;
buildings not in use.
Mining;built in 1950s;used creek
seasonally.
Built in 1960s by owners of High
Lake;used currently as a hunting
cabin on a seasonal basis.
..,.,,
<.0
Map
Locationt l Structure Zonet 2 Location
Table F-l.(Continued)
Accesst 3
Currently
Maintained Use Status
28
30
34
36
37
38
39
40
42
45
46
47
48
49
Lodge,High
Lake (9
buildings)
Cabin
foundations
Chunilna
Creek Placer
(7 buildings)
Mining
buildings
Cabin
Cabin
Cabin
Cabin;shed
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
2
2
3
3
3
3
2
2
2
2
2
2
S.shore of High Lake
S.shore of High Lake
Chunilna Creek
Chuni 1na Creek:8 mi
S.W.of VABM Clear
3 mi N.E.of VABM Curry
Grizzly Camp:5 mi
E.of Daneka Lake
9 mi from Stephan Lake:
7 mi S.of Fog Lake
E.shore of Stephan Lake
Portage Creek:2 mi
N.W.of Dawn Lake
1 mi W.of Portage Creek
mining
1 mi W.of Portage Creek
mining,on sled road
Unnamed lake N.of
Otter Lake
Airplane,ATV,
horse,dog team
Airplane,ATV,
horse,dog team
Airplane,ATV,
4WD,snowmachine
Airplane,ATV,
4WD,snowmachine,
dog team,foot
Foot,dog team
Foot,dog team,
airplane
Foot,airplane
Airplane,foot
Foot,sled,road,
airplane,ATV
Foot,airplane,
ATV,4WD
Foot,airplane
ATV,4WD
Foot,airplane,
ATV,4WD
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Built in 1960s for use as an inter-
national hunting/fishing lodge;
currently in use by Acres American
Susitna project on a seasonal basis.
Built 1980.
Large placer mixing operation in
existence since 1950 and currently
mined on a seasonal basis.
Four buildings built in the 1920s,
1940s and 1960s and used seasonally
for mining.
Built in 1940s and used seasonally
for trapping until early 1960s;no
longer used.
Built by Vogel in the 1940s as a
hunting cabin;currently used on a
seasonal basis as a Stephan outreach
cabin for hunting.
Built in 1970s;current use not
known at this time.
Built in 1960s and in current
seasonal use for hunting,fishing,
and boating.
Built in 1960s and currently used
on a seasonal basis for hunting and
fishing.
Currently used on a seasonal basis
for recreational purposes.
Currently used on a seasonal basis
for recreational purposes.
Currently used on a seasonal basis
for recreational purposes.
."
I
l-'o
Map
Locationt 1 Structure Zonet 2 Location
Table F-1.(Continued)
Accesst 3
Currently
Maintained Use Status
50
51
52
53
55
56
57
58
59
60
61
62
63
64
65
69
70
Trailer
Cabin
Cabin
Cabin
Cabins (3)
Cabin
Lodge
Cabin
foundations
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Lodge
2
2
2
2
2
2
2
3
2
2
3
W.end of S.shore of
unnamed lake N.of
Otter Lake
W.end of S.shore of
unnamed lake N.of
Otter Lake
S.shore of unnamed
lake N.of Otter Lake
W.end of Bear Lake
N.shore of Bear Lake
N.shore of Bear Lake
E.end of Bear Lake
Chul itna Pass:near
railroad
Miami Lake
S.shore of Bear Lake
N.shore of Tsusena
Lake
Foot,airplane,
ATV,4WD
Foot,airplane
ATV,4WD
Foot,airplane,
ATV,4WD
Foot,airplane,
ATV,4WD
Foot,airplane,
ATV,4WD
Foot,airplane,
ATV,4WD
Foot,airplane
Foot,airplane,
ra i 1,car
Rail,foot,car,
airplane
Airplane,foot,
4WD
Airplane,ATV
No
No
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Currently not in use,abandoned.
Built in late 1960s and currently
used for hunting and fishing on a
seasonal basis.
Built in late 1960s and is
seasonally used for hunting and
fishing.
Built in 1970s and currently used
on a seasonal basis for hunting and
fishing.
Built in 1970s and currently used
on a seasonal basis for hunting and
fishing.
Built in 1970s;lodge and cabin
used for fishing,hunting,and
skiing on a year-round basis;
seasonal boating.
Built in 1950s for trapping
purposes;no longer in use.
Exact construction dates not known;
currently used as year-round
residences.
Perhaps being used as recreational
cabins.
Built in 1960s and currently used
for hunting,fishing,and swimming.
Built in 1958;used for commer-
cially guided hunts until 1976;
presently used on a seasonal basis
for private hunting,fishing,and
skiing trips.
.,.,
I
I-'
I-'
Table F-1.(Continued)
Map
Locationt J
72
73
74
75
76
77
78
79
80
81
82
84
85
86
87
Structure
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Tent frame
Cabins (2)
Cabin
Cabin
Cabin
Zonet 2
3
3
2
2
2
2
2
2
2
2
2
2
Location
Deadman Lake:W.of
Bi g Lake
Big Lake
4 mi from Watana/Susitna
confl uence
7 mi E.of Big Lake
W.end of Watana Lake
E.end of Watana Lake
E.end of Gilbert/Kosina
confl uence
S.W.foot,Clarence Lake
S.E.end of Clarence
Lake
E.end of Clarence Lake
N.end of Clarence Lake
On tributary 1 mi E.of
Clarence Lake
Accesst 3
Airplane,ATV
ATV
Airplane,ATV
Airplane,ATV
Airplane,dog
team,snowmachine
Airplane,dog
team,snowmachine
Foot,dog team
Foot,dog team
Airplane
Airplane
Airplane
Foot,dog team
Currently
Maintained
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Yes
No
Use Status
Built in 1960s for fishing and
hunting purposes and currently used
on a seasonal basis.
Built in 1960s;currently used on a
seasonal basis for hunting and
fishing.
Built in 1960s;currently used on a
seasonal basis for hunting.
Constructed in 1970s and currently
used on a seasonal basis for hunting
and fishing.
Built in 1950s and 1960s,respec-
tively,and currently used
seasonally for hunting and fishing.
Built in 1950s and 1960s,respec-
tively,and currently used
seasonally for hunting and fishing.
Built in 1936 as a trapping line
cabin;used until 1955;currently
abandoned with everything intact.
Built in 1950s and used until 1960s
for seasonal hunting.
Built in 1950s and currently used
seasonally as a hunting and fishing
cabin.
Built in 1970s and currently used
on a seasonal basis for hunting,
fishing,and trapping.
Built in 1960s and currently used
on a seasonal basis for hunting,
fishing,and trapping.
Built in 1930 and used until 1950
for trapping,hunting,and fishing
(Simco's line Cabin #4);currently
used seasonally as a hunting
shelter.
"T1
I
I-'
N
Map
Locationt 1 Structure Zonet 2 Location
Table F-1.(Continued)
Accesst 3
Currently
Maintained Use Status
88
89
90
91
92
93
94
95
96
98
99
100
101
103
Cabins (2)
Cabin
Hunting lean-to
Cabin
Cabin/cache
Cabin
Cabin
Cabin
Cabin
Cabin
Cabin
Tent platform
Cabin
Cabin
2
3
1
1
1
2
2
2
3
2
2
3
2
Gaging station:S.
bank of Susitna
Unnamed lake 3 mi S.W.
of Clarence Lake (island
in middle)
S.E.bank of Kosina/
Susitna confluence
2 mi N.E.of Watana/
Susitna confluence
N.W.bank of Watana/
Susitna confluence
W.of Jay/Susitna
confluence
Laha Lake:1.5 mi W.
of Jay Creek
Unnamed lake:2.5 mi
S.E.of Vee Canyon
gaging station
Oshetna River:10 mi
S.of Oshetna/Susitna
confl uence
Tyone River/Susitna
confl uence
Susitna sandbar:S.of
Tyone River/Susitna
confl uence
0.2 mi S.of Maclaren/
Susitna confluence
Jay Creek:3 mi N.
of VABM Brown
Airplane
Floatplane,boat
Boat,foot,
floatplane
Floatplane
Dog team,foot
Airplane
Floatplane,
airplane
Airplane
Dog team,foot,
boat
Boat
Boat,helicopter
Boat
ATV
No
Yes
Yes
No
No
Yes
Yes
Yes
No
Yes
No
Yes
Yes
Built in 1950s for research
purposes;currently not used or
maintained.
Exact construction date not known;
currently used on a seasonal basis
for fishing.
Built in late 1970s for hunting/
fishing purposes;fresh supplies
indicate current use.
Built in 1950s;used as a seasonal
hunting and fishing cabin;supplies
indicate current use.
Built in 1960s for hunting purposes;
cabin collapsed;no longer in use.
Built in 1960s and used currently on
a seasonal basis for hunting and
fishing.
Built in 1960s and used currently
on a seasonal basis for fishing.
Built in 1950s and used currently
on a seasonal basis for fishing.
Built by Simco in 1930 as a trap
line cabin and used on a seasonal
basis for hunting and fishing.
Built in 1960s by Stephan Lodge
owner as a river cabin for Stephan
Lodge boating guests.
Built in 1970s and used currently
for transient boaters.
Built in 1960s and currently used
for boating on a seasonal basis.
Built in 1970s for hunting and
currently used on a seasonal basis.
.,.,
I......
W
Table F-l.(Continued)
Map
Locationt J
105
106
107
110
111
112
112
113
114
115
116
117
Structure
Cabin
Cabin
Cabin
Cabin
Cabin
Line cabin
Cabin
foundations
Cabin
Cabin
Cabin
Cabin
-Cabi n
Zonet 2
3
3
1
2
1
1
2
3
3
3
2
2
Location
Coal Creek
S.end of Coal Lake
S.bank of Susitna at
Devil Canyon
N.end of Madman Lake
S.bank of Susitna;1 mi
upstream of Watana/
Susitna confluence
N.E.corner of Jay/
Susitna confluence
W.bank of Portage
Creek:4 mi from
Portage/Susitna
confluence
Unnamed lake:6 mi W.
of Murder Lake
7 mi N.E.of VABM
Disappointment
2 mi of N.of
Tsusena Lake
1 mi W.of VABM Oshetna
Tyone River/Tyone Creek
confluence
Access1'3
ATV,airplane
ATV,airplane
4WD
Airplane
Dog team,foot
Foot,dog team,
boat,floatplane
Dog team,foot
Airplane
Airplane
Airplane
Airplane
Boat,dog team
Currently
Maintained
Yes
Yes
No
Yes
No
No
No
No
Yes
Yes
Yes
Yes
Use Status
Built in 1970s for hunting and
currently used on a seasonal basis.
Built in 1960s and currently used
on a seasonal basis for mining and
fishing.
Built and used in 1950s for Bureau
of Rec.study;currently not in use.
Built in 1960s and currently used on
a seasonal basis for hunting and
fishing.
Built in 1945 as a trapping line/
hunting cabin;used for trapping
until mid 1950s,presently covered
with brush;no longer used.
E.Simco's line (trapping)and hunt-
ing cabin built in 1939;dates and
game records indicate annual use.
Built in 1940s as a mining/prospect-
ing cabin;no longer in use.
Built in 1960s for hunting purposes;
no longer in use.
Built in 1970s for hunting use and
currently used for seasonal hunting.
Built in 1970s and currently used
as a year-round residence by a
guiding outfit.
Built in 1970s for hunting purposes
and is currently used on a seasonal
basis.
Built in 1960s for hunting and
fishing purposes and currently used
on a seasonal basis.
.,.,
I
t-'
.l:>o
Map
Locationt 1 Structure
118 Cabin
119 Trailer;work
shack
120 Shack
Table F-l.(Continued)
Zonet 2 Location Accesst 3
2 7 mi E.of Tyone River/Boat,dog team
Susitna confluence
1 N.bank of Susitna:Helicopter
1 mi from Deadman/
Susitna confluence
1 S.bank of Susitna:Helicopter
1 mi from Deadman/
Susitna confluence
Currently
Maintained
No
Yes
No
Use Status
Built in 1960s for hunting and
fishing purposes,no longer in use.
Built in 1970s by Army Corps for
Susitna study.
Used and built in 1970s as a re-
search site;since Army Corps study,
has collapsed;no longer used.
t 1 Numbers are keyed to map locations shown in Figure F-2.
t 2 Zone 1 is the impoundment zone plus a 200-ft perimeter;Zone 2 is the 6-mi perimeter around Zone 1;Zone 3 is that zone between 6 and
12 mi from the impoundment.
t 3 Almost all sites are accessible by helicopter.
Conversion:To convert feet to meters,multiply by 0.305;to convert miles to kilometers,multiply by 1.61.
Source:Modified from Exhibit E,Vol.8,Chap.9,Table E.9.5.."
I
I-'
U1
F-16areas(seeTableF-2)westoftheareaoftheproposedprojectandsomesmallprivateparcelsandNative-conveyedlandsintheprojectarea(ExhibitE,Vol.8,Chap.9,p.E-9-3).However,muchoftheFederallandisintheprocessofbeingtransferredtothestateandtheCookInletRegion,Inc.(CIRI),theNativeregionalcommissionforthearea.ThemajorlandmanagementplanscurrentlyinuseorbeingdevelopedfortheregionincludingtheupperandmiddlebasinaretheDenaliLandBankStudy,Matanuska-Susitna-BelugaAreaPlan,MatanuskaandSusitnaTransportationStudy,Matanuska-SusitnaBoroughComprehensivePlan,andCoastalZoneManagementPlan.Theleadagenciesresponsiblefordevelopingandimplementingtheprovisionsoftheseplansincludetheu.S.BureauofLandManagement,AlaskaDepartmentofNaturalResources,AlaskaDepartmentofTransportationandPublicFacilities,andMatanuska-SusitnaBoroughPlanningDepartment.SpecificcategoriesoflandownershipandmanagementintheupperandmiddleSusitnaRiverBasinarediscussedbelow.ThepresentpatternoflandownershipwithintheprojectareaisshowninFigureF-3.Definitionsoflandownership/statusclassificationterminologyarepresentedinTableF-2.AsummaryoftheamountofacreageofvariouslandholdingsispresentedinTableF-3.FEDERALLANDSMostfederallandswithintheupperandmiddleSusitnaRiverBasinareunderthejurisdictionoftheBureauofLandManagement.LocationsoftheselandholdingsareshowninrelationtotheproposedWatanaandDevilCanyondamprojectfeaturesinFigureF-3.FederallandsnorthofthebasinareaalsoaremanagedprincipallybytheBureauofLandManagement.TheselandsareincludedintheBureau'sDenaliPlanningBlock,forwhichalanduseplanhasbeenapproved.Thepresentmanagementprocessisbasicallypassive.TheBureauobjectivesincludeprotectingthenaturalenvironment,withparticularattentiontocariboucalvingareasandriverrecreationroutes.Firecontrolmanagementisalsoanimportantfactor.TheBureauhasacooperativeagreementwiththestateregardingfire-controlmanagementthatincludestheprojectarea(TerrestrialEnvironmentalSpecialists,1982).Finally,theBureauisalsodevelopingawild-lifehabitatmanagementplanincooperationwithAlaskaDepartmentofFishandGamefortheAlphabetHillsbetweentheTyoneandMaclarenrivers(TII-12N,R2-9W,CopperRiverMeridian).Thisplanwillinvolvemoosehabitatmanipulation.Asyet,however,onlystudyplotsforthisprojecthavebeenmappedout.TheBureauhasconveyedtoCIRIsomesectionsoflandadjacenttotheSusitnaRiverintheupperandmiddlebasinarea(Fig.F-3).SomeoftheselandsarewithintheproposedreservoirareasandhavebeenfiledasvaluablelandstotheUnitedStatesforwater-powersites,subjecttotheprovisionsofSection24oftheFederalPowerAct.UndertheAct,theselandsmustremainavailableforentryandselectionasapowersiteandcannotbedestroyedforuseasapowersitebytheowner.Furthermore,noclaimtocompensationforsuchlandcanbemadebythelandowners.However,ownerswouldbepaidfordamagestolanduseimprovements(e.g.,crops,buildings,etc.)ifthelandisselectedforwater-powerdevelopment.Becauseoftheimplica-tionsoftheAct,controversyexistsabouttheinterpretationoftherightsofthelandownerandofthewater-powerlicensee.Atpresent,theBureauofLandManagementisdevelopingregulationsformanagingpubliceasementsacrossNativelands.LandsintendedforconveyancetotheNativeswillhavesixpubliceasementslocatedacrossthem.Theseeasementsincludeanaccesstrail50ft(15m)widefromtheChulitnawaysideontheAlaskaRailroadtopubliclandsimmediately"eastofPortageCreek,astatesiteeasementandtraileasementsonStephanLake,andanaccesstrailextendingeastfromGoldCreek.Easementswereidentifiedonlywhenitwasshownthataccesstopubliclandswasnotpossiblefromanyotherpubliclandarea.TherearenoeasementsimmediatelyadjacenttotheSusitnaRiveraboveGoldCreek(TerrestrialEnvironmentalSpecialists,1982).STATELANDSState-ownedlandintheupperandmiddleSusitnaRiverBasin(seeFig.F-3)hasbeencategorizedinthestate'slandresourceevaluationsystemasagricultural,material,privaterecreation,resourcemanagement,utility,orunclassified(seeExhibitE,Vol.8,Chap.9,p.E-9-10,foradiscussionoftheclassificationsystem).MostofthestatelandsareunderthejurisdictionoftheAlaskaDepartmentofNaturalResources,andcurrently,theDepartment'sDivisionofResearchandDevelopmentisundertakingacomprehensiveassessmentoftheresourcebasewithintheprojectarea(Terrestt'ialEnvironmentalSpecialists,1982).Elsewhereinthebasin,thestateisdispos-ingof1,500acres(610ha)ofremotehousingparcelsnorthofChulitnaand1,280acres(518ha)inasubdivisionlocationsouthofChulitna,tothewestoftheprojectareainthevicinityoftheproposedaccessroute.ConveyancebytheFederalgovernmentofsomestate-selectedlandsintheprojectvicinityhasbeensuspendeduntillandsselectedbytheNativeshavebeenconveyedundertheprovisionsoftheAlaskaNativeClaimsSettlementAct.UnderthetermsandconditionsoftheCookInletLandExchange(PublicLaw94-204),thestatecanacquirepreviouslyselectedlandafterthecompletionoftransferofcorporation-selectedlandstoCIRI.
RI2WRIIW~-'-l'-"-'--..-.~.~.~..T~$'ISTATESELECTIONPATENTEDORTENTATIVELYAPPROVEDSTATESELECTIONSTATESELECTIONSUSPENDEDBUREAUOFLANDMANAGEMENTSECTIONSCONVEYEDTOCOOKINLETREGION,INC.STUDYAREABOUNDARYFEDERALRAILROADPUBLICPARKSNATIVESELECTIONPRIVATEo36 9MILESSCALE!!!!~~5iiiiiiiiiiiiil~~~iLEGEND~-,....•<,'."-:~,~;i:Fi:::.·.rii:1•-k/t?-]~~~[2Z2Jc=l@]~.•<,':R9ERIWi,- --1-.------"'1III,jI-1-----1R2Wi~.iR5W--..-_._._--+--R4WR5WR6WR7WR8WR9WRIOW~.,t.[---'/-.L'.,.1,""IIT!JHFigureF-3.LandOwnershipandManagementPatternsintheUpperandMiddleSusitnaRiverBasinArea.[Source:ExhibitE,Vol.8,Chap.9,Fig.E.9.3]
F-17TableF-2.LandOwnership/StatusClassificationTerminology•Federal:Thoselandsunderjurisdiction.oftheDepartmentoftheInterior,theNationalParkService,theBureauofLandManagement,ortheAlaskaRailroad.•FederalState-Selected:LandisreceivedbythestatefromtheFederalgovernmentinathree-stepprocess.ThestatefirstappliesforlandwhichisclassifiedasStateSelectionsApplicationsorFederalState-Selected.•StateSelectionsTentativelyApprovedorStateT.A.:State-selectedlandsapprovedbytheFederalgovernmentfortransfertothestate.•StateSelectionSuspended:Duetotheconditionsinlandstatusinsouth-centralAlaska,somestateselectionsintheprojectvicinityweresuspendeduntillandsselectedbyNativeshavebeenconveyedundertheprovisionoftheAlaskaNativeClaimsSettlementAct(ANCSA).TheCookInletLandExchange,PublicLaw94-204,hasanextensiveTermsandConditionsdocumentwhichallowsthestatetoacquirepre-viouslyselectedlandaftertheconveyanceofcorporationselectedlandstoCIRI.StateSelectionsPatented:ThoseFederallandsthatarefinallyconveyedtothestate.StatePlannedLandDisposals:Thosestatelandsplottedforsubdivisiondevelopment.Twoarelocatedwithintheprojectarea:ColoradoStationandIndianRiver.BoroughorMunicipalityApprovedorPatented:StatepatentedlandnotreservedforaparticularusecanbeselectedbyaboroughthroughaprocesssimilartothatusedbythestateinselectingFederallands.RegionalCorporationSelections:ThoselandsselectedbytheregionalcorporationsunderprovisinnsoftheANCSA.Eachregioniscomposedof,asfaraspractical,nativeshavingacommonheritageandsharingcommoninterests.TheprojectarealieswithintheCookInletandtheAhtnaregionalcorporations.RegionalCorporation-SelectionPatented:Federallandsconveyedtothecorporations.Interimconveyanceisallocatedtothecorporationiftheselectedlandshavenotbeensurveyed.VillageSelections:ThoselandsselectedbyAlaskanNatives,underprovlslonsoftheANCSA,whichhavebeentraditionallyusedbyNativesfortheircommercialresourcevalue,subsistencehuntingandfishing.Theselandsarelocatednearvillagesoralongrivers.Thevillagereceivesthesurfacerights,theregionalcorporationreceivesthesubsurfacerights.VillageSelectionPatented:VillageselectionconveyedtothevillagecorporationbytheBLM.Interimconveyanceisallocatedtothecorporationiftheselectedlandshavenotbeensurveyed.VillagecorporationsintheCookInletRegionreceivevillage-selectedlandbyreconveyancefromtheregionalcorporation,nottheBLM.TheprocedureforconveyanceandreconveyanceintheCookInletRegionisexcep-tionaltoANCSA.·NativeAllotments:Natives,atthestartofthecentury(1906),wereallowedtofileforallotmentsofupto160acresonunoccupiedFederallands.Theseareprivateholdings.•Private:ThoselandsselectedforprivateownershipundertheAlaskaNativeClaimsSettlementAct.Nativelandsarenotincluded.Source:AdaptedfromCommonwealthAssociates(1982)andExhibitE,Vol.8,Chap.9,p.E-9-9throughE-9-11.
F-18TableF-3.SummaryofLandStatusandOwnershipAcreageintheUpperandMiddleSusitnaRiverBasinStudyAreaConversion:Toconvertacrestohectares,multiplyby0.405.Source:ModifiedfromExhibitE,Vol.8,Chap.9,TablesE.9.1andE.9.2.LandStatus/OwnershipCategoryFederalFederal(StateSelectionSuspended)Federal(RailroadWithdrawal)StateSelectionStateSelectionPatentedorTADenaliStatePark(withinstudyarea)RegionalSelectionNativeGroupSelectionNativeSelectionVillageSelections(includedinNativeselectiontotal)ChickaloonTyonekKnikPrivateTOTAL5,12020,48039,680TotalArea(acres)303,680370,9454,724569,883174,23925,50031,0403,840207,4879,8741,766,492NATIVELANDSNativeindividualswereallowedundertheprovlslonsoftheNativeAllotmentActof1906tofileforallotmentofupto160acres(65ha)onunoccupiedFederalland.SelectionoflandsbytheNativeregionalcorporationsundertheprovisionsoftheAlaskaNativeClaimsSettlementActissimi1artose1ectionbythestate.Federa1 1andsconveyedtotheregiona1corporationareentitled"regionalcorporation-selectionpatented."Interimconveyanceoflandsisallocatedtothecorporationiftheselectedlandshavenotbeensurveyed.VillagecorporationsintheCookInletregionreceivevillage-selectedlandbyreconveyancefromtheregionalcorporations,nottheBureauofLandManagement.TheprocedureforconveyanceandreconveyanceintheCookInletregionisexceptionaltoAlaskaNativeClaimsSettlementAct.Undernormalprocedures,regionandvillagecorporationsselectpreferredlandandtheBureauofLandManagementconveyslanddirectlytothecorporation(ExhibitE,Vol.8,Chap.9,p.E-9-11).CIRI-conveyedlandsareheldintrustuntilthelandisconveyedtotheappropriatevillages.ThesevillagesareChickalom-MooseCreek,Tyonek,andKnik.Atpresent,noactivelandmanagementprogramsarebeingcarriedoutfortheselands.TheNativevillageselectionsaregenerallythoselandsthathavebeentraditionallyusedfortheircommercialresourcevalueandforSUbsistencehuntingandfishing.Mostvillagecorpora-tionsselectlandnearvillagesoralongrivers.Thevillagereceivesthesurfacerights,andtheregionalcorporationreceivesthesubsurfacerights(ExhibitE,Vol.8,Chap.9,p.E-9-11).Whenthevillagesobtaintheirlands,differentownershipswillcreateacheckerboardpatterninthebasin.AnylanddisputeormanagementproblemsthatmayresultfromthissituationwillbehandledbytheVillageDeficiencyManagementAssociation,whichconsistsofrepresentativesfromeachofthevillages.Becauseofthecheckerboardownershippattern,themanagementofNativelandsmayalsobeundertakenbytheassociation.Native-selectedlandsintheupperandmiddleSusitnaRiverBasinareagenerallyarelocatedalongbothsidesoftheSusitnaRiverandaroundtheStephanLakearea.ExistingNativelandownershippatternsareshowninFigureF-3.
F-19BOROUGHLANDSAboroughormunicipalitycanselectstate-patentedlandthatisvacant,unappropriated,orunreservedforaparticularuseuntiltheboroughfulfillsitsentitlementallotmentthroughaprocesssimilartothatusedbythestateinselectingFederallands.Theseselectionscanbemadefromutilityorunclassifiedlands.Oncethelandhasbeenselected,thestateclassifica-tionbecomesinapplicable.ExistingboroughandmunicipallyownedlandsareshowninFigureF-3.TheMat-SuBoroughisconcentratingitsselectionoflandsinthelowerSusitnaRiverBasinnearexistinghighwaysandwestoftheSusitnaRiver.Theboroughhasreceivedtitletoabout92%ofits355,200-acre(143,700-ha)landentitlement(AlaskaDept.ofNaturalResources,1982).Itisunlikelythattheboroughwillselectanylandslocatedinthedamsite,reservoir,oraccessroadareas.Theboroughisinvolvedinthreeseparatemanagementplans(TerrestrialEnvironmentalSpecialists,1982)--(1)theMatanuska-SusitnaComprehensivePlan(1970),(2)theTalkeetnaMountainsSpecialUseDistrict,and(3)theMatanuska-SusitnaBoroughCoastalZoneManagementProgram.TheboroughcanexerciseitsplanningandzoningauthorityoveralllandswithintheSpecialUseDistrictboundaries,whichincludestheprojectarea.TheordinancethatestablishedtheSpecialUseDistrictprovidesformultipleresourceuseandtakesintoaccountuniquescenicvalues.LandslocatedintheSpecialUseDistrictaresubjecttopermitrequirementsforvariousdevelopments(e.g.,roads,subdivisions,etc.).Theboroughhasbeenupdatingthe1970Matanuska-SusitnaBoroughComprehensiveDevelopmentPlan.AFebruary1983draftoftheupdatedplaniscurrentlyunderreview.Theproposedprojectareaisconsideredamixed-usezone,whichwouldpermithydroelectricdevelopment.TheMat-SuBorough,inconjunctionwiththeNationalOceanicandAtmosphericAdministration,OfficeofCoastalZoneManagementandtheAlaskaCoastalZoneManagementProgramundertheAlaskaDivisionofCommunityPlanning,DepartmentofCommunityandRegionalAffairs,ispreparingaCoastalZoneManagementPlan.TheSusitnaRiveruptoDevilCanyonisdesignatedtobewithintheareacoveredbytheprogram.PRIVATELANDSThereareonlyscatteredprivatelandholdingsintheupperandmiddleSusitnaRiverBasin.Mostoftheselandholdingsareconcentratedalongmajorroads,suchastheGeorgeParksandDenalihighways.AfewsmallprivatelandholdingsalsoarelocatedinmoreremoteareasasaresultofstateandboroughlandsalesandpatentedFederalminingclaims.Ingeneral,privatelandsareoftenlocatednearwaterfrontsorairstripstoallowaccess(AlaskaDept.ofNaturalResources,1982).TheMatanuska-SusitnaBoroughassessor'sofficeestimatesthatoftheapproxi-mately45,550privatelotsintheboroughtotalingslightlylessthanone-halfmillionacres,approximately80%remainundeveloped(AlaskaDept.ofNaturalResources,1982).ExistingparcelsunderprivateownershipareshowninFigureF-3.F.l.2.1.3LandValuesCompleteandaccuratelandvaluedatafortheupperandmiddleSusitnaRiverBasinareaarecurrentlyunavailable.ThisisprimarilybecauseoftheongoingchangesinlandownershipandthecurrentlackofdevelopmentanduseintheSusitnaRivervalleyareathatwouldindicateorassignalandvaluetoaspecificpieceofproperty.Marketvaluesareavailableonlyforstate,borough,Native,orprivatelandsthathavebeenorareabouttobesold.SpecificlandvaluesfortheproposedWatanaandDevilCanyonprojectlandswouldnotbeestablisheduntiltheprojectlandacqu1sitionprocesswasstarted.Althoughpreciselandvaluescannotbeascer-tainedforlandslocatedwithinmuchoftheupperandmiddlebasinarea,anindicationofrepre-sentativeAlaskanlandvaluescanbeobtainedfromlandvaluedataprovidedbytheAlaskaDepart-mentofNaturalResourceslanddisposalprogram.CalculationscarriedoutforlandvaluesalongtheproposedtransmissionlinecorridorarediscussedbelowinSectionF.l.2.2.3.F.l.2.2PowerTransmissionLineCorridorF.l.2.2.1ExistingandFutureUsesTheproposed330-mi(530-km)longtransmissionlinecorridorbetweenFairbanksandAnchoragewouldextendthroughportionsoftheTanana,Nenana,Chulitna,andSusitnarivervalleys.ThecorridorwouldparallelportionsoftheGeorgeParksHighwayandAlaskaRailroad.ThisregioniscommonlyreferredtoastheAlaskaRailbelt.Theregionaloverviewsanddefinitionsgivenaboveforthevariouslandusetypesalsoapplytothetransmissionlinecorridor.Evenwithoutthedevelopmentoftheproposedtransmissionlinecorridor,landuseactivitiesanddevelopmentwouldlikelycontinuetoincreasealongtheGeorgeParksHighwayandAlaskaRailroadcorridorsasgreaterdemandswereplacedonexistinglandresourcesforplannedrecreation,agricultural,utility,andmineralresourcedevelopmentwithintheRailbeltcorridor.
F-20AGRICULTURALLANDSSomefarmingandgrazingoccursinthelowerreachesoftheSusitnaRiverBasinandintheTananaRiverBasinbetweentheFairbanksandDeltaJunctionareas.AlongtheFairbanks-to-Healysegmentofthetransmissionlinecorridor,agriculturallandsarelocatednearFairbankstotheeastandnorthoftheproposedrouteandalongtheParksHighwayandAlaskaRailroadbetweenthecommunitiesofDunbarandNenana.AgriculturallandsalsooccurimmediatelynorthofHealy.BetweenHealyandWillow(alongtheintertieroute),thereareagriculturallandsinthevicinityofTalkeetna.Theselandsaregenerallytothewestoftheproposedtransmissionlineroute;however,afewparcelsareimmediatelyadjacenttotheeasternsideoftheproposedline.AlongtheWillow-to-Anchoragesegmentofthetransmissionline,stateagriculturalsaleareasincludetheDeltaIslandagriculturaldisposalabout5mi(8km)southwestofWillow,theFishCreekManagementUnitsouthofRedShirtLake,andthePointMacKenzieagriculturalsalenorthwestofPointMacKenzie.Approximately20,000acres(8,000ha)ofstateandboroughlandswererecentlysoldforagriculturaluse.Mostofthesaleshavetakenplacealongthesouthernportion ofParksHighwayandintheWillowsubbasinarea.Manyofthesefarmsarenotinproductionbutareexpectedtobeginonceaccesshasbeenachievedandthelandcleared.Existingandpoten-tialagriculturallandsandlandsalesareshowninTableF-4.AgriculturalsoilsarediscussedinAppendixE.FORESTRESOURCELANDSApreliminaryanalysisbythestatehasindicatedthatforestedareasalongbothsidesoftheGeorgeParksHighwayhavehightomoderatevalueasforestrylands(AlaskaDept.ofNaturalResources,1982).Theforest1andcovertypeisdescribedindetai1inSection3.1.5.1andAppendixJ.Todate,commercialuseof'woodresourceshasbeenlimitedtosmallloggingopera-tionsalongtheSusitnaRiverfloodplaininthelowerbasin.ForestlandwithhighpotentialforcommercialvalueislocatedallalongtheSusitnafloodplaindownstreamfromPortageCreeks(ExhibitE,Vol.6a,Chap.3,p.E-3-195).Thebestcommercialstandsarewithintheuplandspruce-hardwoodforesttypeatelevationsof800to1,200ft(120to370m)(CommonwealthAssoc.,1982).Eleventimbersalesthatwilltotalabout325,000acres(132,000ha)withinthelowerSusitnaRiverBasinareplannedbytheAlaskaDepartmentofNaturalResourcesandtheMat-SuBorough(ExhibitE,Vol.6a,Chap.3,pp.E-3-195-196).However,mostofthesesalesarenotscheduledtobeginearlierthan1992.MINERALRESOURCELANDSMineralexplorationandmlnlngactivitieswithinthegeneralareaoftheproposedtransmissionlinecorridorhavebeenlimited.Generallylow-intensityminingclaimshavebeenoperatedintheareaonanintermittentbasis.CoalisamajorresourcewithintheMat-SuBorough,withdepositsofvaryingqualitylocatedthroughouttheborough(ExhibitE,Vol.8,Chap.9,p.E-9-18).MiningareasinthevicinityoftheproposedtransmissionlinecorridorbetweenFairbanksandHealyarelocatedwestofFairbanks,eastofDunbar,inthevicinityofNenana,immediatelysouthofwheretheGeorgeParksHighwaycrossestheAlaskaRailroad,andanexten-siveareaeastofHealy.CoalhasbeenminedintheHealyareasince1918,andfurtherexplora-tioniscontinuing.BetweenHealyandWillow(alongtheIntertieroute),theprincipaleconomic,non-metallicresourcesarecoalandgravel.CoalisalsolocatedintheBroadPassarea(CommonwealthAssoc.,1982).BetweenWillowandAnchorage,littleminingactivityoccurswithintheproposedtransmission1inecorridorarea.Minera1resourcesarediscussedfurtherinAppendixE.NATURALAREASANDRECREATIONLANDSTheproposedtransmissionlinecorridordoesnotextendthroughanationalpark-preservesystem,nationalhistoriclandmarkarea,designatedwildernessarea,ornationalforestsystem.However,significantnaturalandrecreationareasarelocatedbothtotheeastandtothewestoftheproposedcorridor.ThetwomostsignificantrecreationareastothewestofthecorridoraretheDenaliNationalParkandPreserveandtheDenaliStatePark.Inaddition,thecorridordoesparallelaportionoftheDenaliStateParkandextendsthroughabout5mi(8km)oftheSusitnaFlatsStateGameRefugelocatednearAnchorage.TheNancyLakeStateRecreationAreaislocatedneartheproposedrouteintheWillowarea.Recreationactivitiesintheareaincludehunting,fishing,boating,canoeing,kayaking,camping,backpacking,andskiing.RecreationalactivitieswithintheproposedtransmissionlinecorridorstudyareaarediscussedfurtherinAppendixL.TRANSPORTATIONANDUTILITYCORRIDORSTheproposedtransmissionlinecorridoressentiallyparallelstheGeorgeParksHighwayandtheA1askaRailroadfromFairbankstoAnchorage.Thecorridorwou1dbecrossedbytheDenaliHighway(Route8)nearthecommunityofCantwell.Atpresent,thisroadisclosedduringthewinter.RivertravelispossiblealongportionsoftheTanana,Nenana,Chulitna,andSusitnarivers.Boats,canoes,rafts,andkayaksareusedalongtheseriversandtheiradjacenttribu-taries.Majorairportsandairbases nearthetransmissionlinecorridorarelocatedat
F-21TableF-4.ExistingandPotentialAgriculturalLandsandLandSalesLocatedAlongtheProposedTransmissionLineCorridorNorthernStudyArea(Fairbanks-to-Healy)GoldstreamAgriculturalDisposalBrown'sCourtAgriculturalDisposalWindyAgriculturalDisposalHealyAgriculturalDisposalCentralStudyArea(Healy-to-Willow)GooseCreekAgriculturalDisposalSouthernStudyArea(Willow-to-Anchorage)DeltaIslandsAgriculturalDisposalFishCreekManagementUnitPointMacKenzieAgriculturalSaleWestofBonanzaCreekExperimentalForest10misouthofAndersonSouthoftheClearMissileEarlyWarningStationBeginsapproximately13minorthwestofHealyandextendssouthfor6mibetweentheParksHighwayandtheNenanaRiver.Approximately17misouth-eastofTalkeetna,northofGooseCreekandeastofEmi1Lake.Approximately5misouth-westofWi11owBetweenthePointMacKenzieprojectandRedShirtLakeNorthwestofMacKenziePointTheagriculturalsaleisplannedforFiscalYear1984.Theproposedtrans-missioncorridoreithercrossesorisadjacenttoapproximately3.5mioftheGoldstreamdisposal.Agriculturalsaleswereofferedin1983.Thetransmissioncorridorpassesapproximately0.5mifromthesouth-easterncorneroftheparcel.AgriculturalsaleswillbegininFiscalYear1985.Theproposedtransmissioncorridorcrossesapproxi-mately3mioftheWindydisposal.AgriculturalsaleswillbegininFiscalYear1985.Theproposedtransmissioncorridorcrosses6mioftheHealydisposal.A160-acreparcel(currentlyopenforsale).TheIntertieeasementoccupiesthewesternportion oftheparcel,running0.5miinlengthand400ftinwidth.Theareaiscurrentlyopenforagriculturalsales.Theproposedtransmissioncorridorismorethan1mifromtheDeltaIslandsdisposalarea.Agriculturalsaleswillbeginwithinthenext2years.Theproposedtransmissioncorridorcrossesapproximately11mioftheFishCreekunit.Planningforthisunitiscurrentlytakingplace.Therefore,theextentofagriculturalsalesisunknown.Theproposedtransmissionlineextendsacrossmorethan5miofagriculturalsaleproperty.Conversion:Toconvertmilestokilometers,multiplyby1.61;toconvertacrestohectares,multiplyby0.405;toconvertfeettometers,multiplyby0.305.Source:SupplementalInformationtoExhibitE,Chapter9,ResponsetoComment7.
F-22AnchorageandFairbanks.NumerousgroundandfloatplanelandingsitesarealsolocatedalongthecorridorareawiththemajorityofthefloatplanelandingsiteslocatedsouthofWillow.LandingstripsandfloatplanelandingsiteslocatedalongthetransmissionlinecorridorarelistedinTableF-5.OthertransmissionlinecorridorsexistorarebeingconstructedinareasneartheproposedSusitnatransmissionlinecorridor(seeFig.1-2).AChugachElectricAssociationtransmissionlineextendseastfromtheKnikArmnearAnchorageandaGoldenValleyElectricAssociationtransmissionlineextendsfromFairbankstoHealy.Right-of-wayisbeingclearedfortheAnchorage-FairbanksIntertiebetweenHealyandWillow.TheIntertie,notpartoftheSusitnaproject,wouldbeexpectedtobeinplacebythetimetheproposedWatanaandDevilCanyonprojectswerecompleted.SETTLEMENTAREASANDSPECIALUSELANDSBetweenFairbanksandAnchorage,theproposedtransmissioncorridorwouldextendpastanumberofsmallcommunities,aswellasundevelopedlandscapableofsupportingsettlement.Theselandshaveslightormoderatebuildinglimitationbasedonphysicalfactorssuchasslope,soildrainage,andsoilload-bearingcapacity(AlaskaDept.ofNaturalResources,1982).AlongtheHealy-to-Fairbankssegment,residentialand/orcommerciallandusesoccuratthecommunitiesofDunbar,Nenana,andHealy.TheU.S.AirForceClearM.E.W.S.MilitaryReserveislocatedinthevicinityofAnderson.ThecorridoralsowouldextendpasttheKeystoneExtension(Sec.21,TIS,R3W,FM),HealySmallTracts(Sec.12,TIS,R8W,FM),andtheNorthridgeSubdivisions(Sec.17,TIS,R2W,FM)onthewesternsideofParksHighway.ResidentialdevelopmentbetweenthemiddleandeastforksoftheChulitnaRiverandalongthemainstemChulitnaRiverislimitedtoafewresidencesontheParksHighway.AlongtheHealy-to-Willowsegment,residentialandcommercialdevelopmentsarelocatedalongtheNenanaRiverandtheParksHighwayneartheDenaliNationalParkandPreserve(e.g.,McKinleyVillage)andjustoutsidetheNenanaGorgearea.ResidentialandcommercialdevelopmentalsooccursatCantwell,Summit,andBroadPass.Development,suchastheCantwellCommunityCenter,isexpectedtocontinuealongtheDenaliHighway.SomescatteredresidencesexistalongtheParksHighwayandtheChulitnaRiverwithinDenaliStatePark.LanddevelopmentoccurseastofCurryRidgealongtheAlaskaRailroad,includingtheIndianRiverLandDisposalandtheIndianRiverRemoteParcel.Boththeseareasarerecreationoriented.Onlyafewresidentsremainthereyear-round.HomesteadsoccuralongtheAlaskaRailroadatChulitna,GoldCreek,andtheSusitnaandIndianrivers.LanduseeastofTalkeetnaisdominatedbythelanddisposalsalongtheTalkeetnaRiver.AfewhomesteadsexistaroundLarsonLake,andlocalresidentscoulddeveloptheareaforresidentialandrecreationuse(ExhibitE,Vol.8,Chap.9,p.E-9-20).ResidentialandcommercialdevelopmentdoesoccurwestofCurryRidgeandalongPetersvilleRoadnearTrapperCreek.AlongtheWillow-to-AnchoragesegmentofthetransmissionlineresidentialuseoccursatWillow,RedShirtLake,andonmanyofthesmalllakeseastoftheproposedroute.Approximately25cabinsarelocatedalongtheshoresofRedShirtLake(ExhibitE,Vol.8,Chap.9,p.E-9-49).WithintheWillowarea,scatteredcabinsarelocatedneartheParksHighwayandtheAlaskaRailroad.AtWillow,thecorridorareaencompassestheHolsteinHeightsSubdivisionandstateandprivaterecreationland(Sec.20,T15N,R4W,SM).LandsmanagedbytheU.S.Army(FortRichardson)andU.S.AirForce(ElmondorfAirForceBase)arelocatedalongthesouthernendofthetransmissionlinecorridorareanearAnchorage.WETLANDSANDFLOODPLAINSWetlandsoccurinanumberofareasalongtheentireproposedtransmissionlinecorridor.WetlandsalongthecorridoraredescribedindetailinSection3.1.5.1andAppendixJ.TheU.S.ArmyCorpsofEngineershasmappedthe100-yearfloodelevationontheNenanaRivernearthecommunityofNenanaandatChulitnaonPassCreek.The100-yearfloodplainoftheTalkeetna,Susitna,andChulitnarivershasbeenmappedwithinthecorporatelimitsofTalkeetna.Talkeetnaissubjecttofloodingfromallthreerivers.ThefloodplainoftheTalkeetnaRiveratTalkeetnaiswideanddevelopedonlyonthesouthernsideatthemouthoftheriver.Openspacesinthefloodplainareextensiveandmaycomeunderpressureforfuturedevelopment(ExhibitE,Vol.8,Chap.9,p.E-9-26).F.1.2.2.2OwnershipStatusandManagementMostofthelandalongtheproposedtransmissionlinecorridoriscurrentlyownedbytheStateandmanagedbytheDepartmentofNaturalResources.Managingagenciesforthelandalongthe
F-23TableF-5.Airports,LandingStrips,andFloatPlaneLandingSitesAlongtheProposedTransmissionLineCorridorLandingSiteLocationsinProximitytotheCorridorNorthernStudyArea(Fairbanks-to-Healy)FairbanksNenanaNearClearM.E.W.S.MilitaryReserveRexFerryLigniteHealyCentralStudyArea(Healy-to-Willow)McKinleyParkMt.McKinleyNationalParkCantwellSummitColoradoChulitnaGoldCreekCurryMontanaKashwitnaSouthernStudyArea(Willow-to-Anchorage)Wi11owElmendorfAirForceBaseAnchorageLandingSitesLocatedLessthanOneMilefromtheProposedCorridorFloatplanelandingsitewithinthepro-posedcorridorLandingstripandfloatplanelandingsitewithin2,500ftand5,000ft,respectivelyGoldenNorthAirportwithin5,000ft2landingstripswithin1,500ftandafloatplanelandingsiteadjacenttothecorridorNumerousfloatplanelandingsiteswithinonemileofthecorridorinWi11owregionConversion:Toconvertfeettometers,multiplyby0.305.Source:ExhibitE,Vol.8,Chap.9;ExhibitG,Vol.4,ConstraintMap,AppendixA;CommonwealthAssoc.,1982.
F-24varioustransmissionlinecorridorsegmentsareasfollows:RouteSegmentDams-to-GoldCreekHealy-to-FairbanksWi11ow-to-HealyWillow-to-AnchorageLand-ManagingAgenciesMatanuska-SusitnaBorough;AlaskaDepartmentofNaturalResources;CookInletRegion,Inc.Fairbanks-NorthStarBorough;AlaskaDepartmentofNaturalResources;U.S.AirForce,NationalParkService,andBureauofLandManagement;AhtnaRegion,Inc.Matanuska-SusitnaBorough;AlaskaDepartmentofNaturalResources;U.S.NationalParkServiceandBureauofLandManagement;AhtnaRegion,Inc.andCookInletRegion,Inc.Matanuska-SusitnaBorough;MunicipalityofAnchorage;AlaskaDepartmentofNaturalResources;U.S.ArmyandU.S.AirForce.IntheHealy-to-Fairbankssegment,theFairbanks-NorthStarBoroughispreparingacomprehensiveplanthatwi11inc1udeapproximately25mi(40km)ofthenortheasternportionofthecorridorarea.TheAlaskaDepartmentofNaturalResourceshasanon-goingandactivelanddisposalprograminthisregion.TheDepartmentalsoisdevelopingtheTananaAreaPlan.Currentlyonlybaselineinformationhasbeenpreparedandnopoliciesordraftplanshavebeenpublished.TheNationalParkServicemanagesactivitieswithintheDenaliNationalParkandPreserve.FormalplanningactivitiesforAhtnaRegion,Inc.landshavenotbegun.AgencyplanningandmanagementactivitiesfortheHealy-to-Wi11owandWillow-to-AnchorageportionsofthetransmissionlineroutearesimilartothosedescribedintheprevioussectionontheupperandmiddleSusitnaRiverBasinarea.Thefinalportion oftheWillow-to-Anchoragesegmentwouldbelocatedwithinthe~nchoragemunicipality,whichhasbothacurrentcompre-hensiveplanandadraftutilityplan.InthisareathetransmissionlinecorridoralsowouldextendacrossmilitaryreservationlandsunderthejurisdictionoftheU.S.AirForceandtheU.S.Army.Masterplanprogramsexistforbothmilitaryfacilities.FEDERALLANDSTheFederalgovernmentownsonlyscatteredparcelsoflandalongtheproposedtransmissionlinecorridor.ThelargestFederallandholdingadjacenttotheproposedcorridoristheDenaliNationalPark,managedbytheU.S.ParkService.TheU.S.AirForcemanagesalandreservelocatednearAndersonandtheElmendorfAirForceBasenearAnchorage.TheU.S.ArmymanagesFt.RichardsonnearAnchorage.OtherFederallyownedlandsoccurnorthofCantwellandnorthofTalkeetna(CommonwealthAssoc.,1982).TheBureauofLandManagementmanageslandinthevicinityofBroadPass.ThelandonwhichtheAlaskaRailroadislocatedisalsoFederalproperty.RailroadholdingsexistsinvariouslocationsalongtheRailbeltcorridor.TheAlaskaRailroadmanageslandeastofDenaliStateParkandrailroadwithdrawlsexistinthevicinitiesofHonoluluandTalkeetna.STATELANDSTheproposedtransmissionlineroutewouldbelocatedprincipallyonstate-ownedand-managedlands.Themajorityoftheselandsareinvariousstagesofthestateselectionprocessandareclassifiedasselected,tentativelyapproved,orpatented.BetweenFairbanksandHealy,themajorityoflandalongtheproposedcorridoriseitherstatepatentedortentativelyapproved1ands.Thestatealsohasselected1andtotheeastandsouthofthecommunityofNenana.AlongtheHealy-to-Willowsegment(alongtheIntertieroute),state-selectedlandsarelocatedtothenortheastoftheDenaliNationalParkandPreserve.DenaliStateParklandsarelocatedtothewestoftheproposedtransmissionlinecorridorandaremanagedbytheAlaskaDepartmentofNaturalResources,DivisionofParks.MostoftheselandshavebeententativelyapprovedbytheFederalgovernmentforpatentlandstatustothestate.Anumberofstatelandparcelswilleventuallybedeededtolocalagenciesandrelinquishedforprivatelandsales.TwostatelanddisposalsitesexistneartheIndianRiver,justnorthoftheSusitnaRiver.BetweenWillowandAnchoragetheproposedtransmissionlinecorridorextendsthroughlandsthatareeitherstatepatentedortentativelyapproved.Muchoftheareaiscurrentlyusedasstaterecreationlandsandgamerefuges.NATIVELANDSTheprovisionsforNative-selectedlandswerediscussedinSectionF.l.2.1.2.BetweenFairbanksandHealy,Native-selectedlandsarelocatednearthecommunityofDunbarandalongtheParksHighwayinthevicinityofAnderson.AlongtheHealy-to-Willowsegmentoftheproposedtrans-missionlinecorridor,CookInletRegion,Inc.,hasappliedfortheselectionofstate-owned
F-25landsintheTalkeetnaarea.Atpresent,therearenoNative-selectedlandsaltransmissionlinecorridorbetweenWillowandAnchorage.BOROUGHLANDSBetweenFairbanksandHealytheonlyFairbanks-NorthStarBoroughapprovedorn~tpr1tc,rlalongtheproposedtransmissionlinecorridorarewestofFairbanks.Alongthesegment,theMat-SuBoroughlandsgenerallyfollowtheParksHighwayandPetersvilOnlyasmallamountoftheselandshavebeenpatented.Themajorityofthelandsareeitherselectedortentativelyapprovedlands.BetweenWillowandMat-SuBoroughhasapprovedorpatentedlandsinthevicinityofRedShirtLakeandTheboroughisconcentratingitsselectionoflandsinthelowerSusitnaBasinnearhighwaysandwestoftheSusitnaRiver.PRIVATELANDSPrivatelyownedlandisscatteredalongtheentiretransmissionlinecorridor,butgenerallyisconcentratedalonghighwayandrailtransportationcorridors,nearwaterfrontholdings,orinthevicinityofairstrips.PrivatepropertyislocatedinthevariousRailbeltcommunitiesadjacenttotheGeorgeParksHighwayandAlaskaRailroad.PrivateparcelsalsooccurinthevicinityofFerry,nearNenana,andalongEsterCreekinaminingdistrictatthenorthernendoftheproposedcorridornearFairbanks(ExhibitE,Vol.8,Chap.9,p.E-9-11).AlongtheHealy-to-Willowsegment,privateandleasedlandsoccurprimarilysouthofCurry.MostoftheseprivatelandsarelocatedintheMontanaandTrappersCreekareaandeastofChaseandTalkeetna.AdditionalresidentialdevelopmentsarelocatedbetweentheChulitnaandSusitnarivers,eastofDenaliStatePark,intheIndianRiverLandDisposalandIndianRiverRemoteParcel,inTalkeetna,andalongtheremainderofParksHighway.PrivateparcelsalsooccurnearWillowandthroughoutAnchoragealongthesouthernportionofthetransmissionlinecorridor.F.l.2.2.3LandValuesAsdiscussedinSectionF.l.2.1.3,preciselandvaluedataforthetransmissionlinecorridorareaarecurrentlyunavailable.Althoughpreciselandvaluescannotbeascertainedforlandslocatedwithinmuchofthecorridor,anindicationofrepresentativeAlaskanlandvaluescanbeestab1ishedbyusing1andvaluedatafromtheAlaskaDepartmentofNaturalResources1anddisposalprogram.TherepresentativelandvalueinformationpresentedinTableF-6includesunitprice,parcelsize,andtypeofaccessavailabilityforsubdivisionandagriculturallanddisposalareas.BecauseoflandpricediscountsofferedtoqualifiedAlaskaresidents(50%to75%ofresidentsqualify),pricesactuallypaidforspecificlandtractsmaybesubstantiallylowerthantheappraisedvaluescited.Thedisposalsitesshownarelocatedwithinthegeneralvicinityoftheproposedtransmissionlinecorridor(Fig.F-4).However,thelandvaluedatadonotrepresentthemetropolitanAnchoragearea,whereindividuallotsmaybevaluedasmuchas$75,000.Althoughitisdifficulttopredictfuturelandvaluesaccurately,itisanticipatedthatthesevalueswillincreasewithtime.ThisisespeciallytruefortheRailbeltRegionofAlaskabecauseofexistingandplannedhumandevelopmentandactivities,roadandutilitycorridors,andresourcedevelopment.F.l.3SusitnaDevelopmentAlternativesF.l.3.1AlternativeDamLocationsandDesignsIngeneral,theareasofalternativedamlocationsanddesignsareallwithintheupperandmiddleSusitnaRiverBasin.LanduseofthebasinwasdescribedinSectionF.l.2.1.PresentlandownershipwithinthebasinisshowninFigureF-3.MostofthelandinthebasiniscurrentlyownedbytheU.S.GovernmentandmanagedbytheU.S.BureauofLandManagement.However,muchofthefederallandispresentlyintheprocessofbeingtransferredtothestateandtotheCookInletRegion,Inc.Existinglandusetypes,patterns,anddevelopmentwithinthebasinarescatteredandoflowintensity(Figs.F-landF-2).Thereareessentiallynoagriculture,large-scaletimbering,large-scalemining,orsignificantresidential,commercial,orindustrialuseswithinthearea.Theprimarylanduseactivityisdispersedrecreation.InthecaseofthealternativesinvolvingtheWatanaIandReregulatingdams,thenearest(low-use-intensity)recreationalactivitiesoccurtothesouthintheFogLakesarea.SectionsoflandalongtheSusitnaRiverandtothesouthhavebeenselectedbytheNativesorconveyedtotheCookInletRegion,Inc.,whilelandstothenorthhavebeensuspendedforstateselection.Low-use-intensityrecreationactivitiesalsooccurtothenorthwestofthealternativeModifiedHighDevilCanyondamintheHighLakearea.Ahuntingandfishinglodgeconsistingofninebuildingsislocatedalongthelake.SectionsoflandalongtheSusitnaRiverinthatareahavebeenconveyedtotheCookInletRegion,Inc.Landstothenorthwestofthesitehavebeen
F-26TableF-6.SampleLandValueDatafortheAlaskaDepartmentofNaturalResourcesLandDisposalProgramMapAccessNo.ofAve.ParcelAve.ParcelAve.PerDisposalNameNumbert1Codet2ParcelsSize(acres)Price($)AcrePrice($)SUBDIVISIONSNorthridge1 11811.626,4502,277Parkridge21135.327,7965,268Farmview3 12123.716,571699NenanaSouth41354.23,497832Anderson535336.922,245603JuneCreek612555.05,000994PanguinqueCreek7 31656.05,684953IndianRiver81604.44,362985BaldMountain9 31734.81,692356SouthBaldMountain1038411.65,955511PuppyHaven1131338.841,5301,069AGRICULTURALDISPOSALSPercentinMapAccessNo.ofClassII/IIIAve.PerDisposalNameNumbert1Codet2ParcelsAcresSoilsAcrePrice($)TwoMi1eLake121173,10174136Brown'sCourt13191,77596134MooseCreek142466760103GooseCreekt3153116042105DeltaIsland163490679227NancyLake171220065136LittleSusitna182356073152t1MapnumbersarekeyedtoFigureF-4.t2AccessCode:1 -Adjacentto(withinoneortwomiles)theParksHighway;2 -Servedbymajorexistingorplannedsecondaryroad;3 -Notaccessedbymainroad.t3CrossedbyproposedSusitnatransmissioncorridor.Conversion:Toconvertacrestohectares,multiplyby0.405.Source:ModifiedfromAlaskaDepartmentofNaturalResources,DivisionofLandandWaterManagement.MaterialspreparedforStateLandDisposalBrochuresfor1981-1983period.
FigureF-4.F-27,"/"~,,-LocationsofAlaskaDepartmentofNaturalResourcesLandDisposalSitesforRepresentativeLandValueData.[Source:MOdifiedfromAlaskaDepartmentofNaturalResources,DivisionofLandandWaterManagement.MaterialspreparedforStateLandDisposalBrochuresfor1981-1983period,andExhibitG,PlateG.1]
F-28selectedbythestate,whilelandstothenorthandeasthavebeensuspendedforstateselec-tion,andlandstothesouthhavebeenselectedbyNativeAlaskans.AsmallamountofprivatelandoccursneartheHighLakearea.F.l.3.2AlternativeAccessRoutesTwoalternativeaccesscorridorswereconsideredfortheproposedWatanaandDevilCanyondamprojects.Corridor1wouldextendfromtheParksHighway(nearHurricane)totheWatanadamsiteonthenorthsideoftheSusitnaRiverandCorridor2wouldextendfromtheParksHighwaytotheWatanadamsiteonthesouthsideoftheSusitnaRiver(seeSec.2,Fig.2-13).AsdiscussedinSectionF.l.2.1.2,muchofthelandinbasinareahasbeenorisbeingconveyedtoNativecorporations,andtheremainderofthelandsaremostlyunderFederalorstateowner-shipandmanagement.Currentlanduseisprimarilydispersedrecreation.Corridor1(River-northside)extendsmostlythroughstate-selectedlandsandsomeNativeselectedandprivatelands.Landuseiscurrentlylow-densityrecreationandminingactivities.Corridor2(River-southside)tr'aversesmoreNative-selectedlands.Nativeorganizationshaveexpressedinterestindevelopingtheselow-density,intermittentuselandsformining,recreation,forestry,andresidentialuse(ExhibitE,Vol.9,Chap.10,p.E-IO-48).F.l.3.3AlternativePowerTransmissionRoutesThealternativepowertransmissionlineroutesegmentsareinthreecorridorareas:(1)theNorthernStudyAreabetweenFairbanksandHealy,(2)theCentralStudyArea,whichincludestheupperandmiddleSusitnaRiverBasinarea,and(3)theSouthernStudyAreabetweenWillowandAnchorage.ThesealternativeroutesegmentsareshowninSection2,Figures2-14through2-16.Ingeneral,landuses,ownershippatterns,managementplans,andlandvaluesareasdiscussedinSectionF.l.2.RecreationaluseisdiscussedinSection3.2.2.7andAppendixL.LandusealongeachalternativetransmissionroutesegmentisshowninTableF-7.F.l.3.4AlternativeBorrowSitesThealternativeborrowsiteareas,allwithintheupperandmiddleSusitnaRiverBasinstudyarea,areshowninFigures2-2and2-6.Landusewithintheborrowsiteareasisgenerallylow-intensity,dispersedrecreation.MostoftheborrowsitelandsalongtheSusitnaRiverhavebeenselectedbytheNativesorconveyedtotheCookInletRegion,Inc.LandownershipalongtheTsusenaCreekborrowsiteareasconsistsofstateselection-suspendedandstateselection-approvedlands.Landuse,ownership,management,andvaluesfortheseareasarediscussedinmoredetailinSectionF.l.2.F.l.4Non-SusitnaGenerationAlternativesF.l.4.1Natural-Gas-FiredGenerationScenarioF.l.4.1.1BelugaandChuitnaRiversTheBeluga/Chuitnariversregionisarelativelyremoteareaandlanduseisdiverseandoflowintensity.Dispersedrecreationactivitiesoccurwithintheregion.Naturalresourcesbeingdevelopedintheareaincludeoil,gas,coal,andtimber.Nomajorgroundtransportationroutesoccurintheregion.LandownershipintheBelugaareaisvariedandincludestheStateofAlaska;CookInletRegion,Inc.;TyonekNativeCorp.;andtheKenaiPeninsulaBorough.State-ownedlandshavebeendesignatedasresourcemanagementlands,industriallands,reserveduse1ands,andmateriallands.MostoftheBelugacoaldistrictisresourcemanagement1and(ExhibitE,Vol.9,Chap.10,p.E-IO-120).F.l.4.1.2KenaiPeninsulaLanduseinthenorthwesternKenaiareaismixedandincludesdevelopedlands,aswellaslandsof1ow-intensityuse.MuchoftheKenairegionisusedforrecreation.MorethanhalfoftheKenaiPeninsulaisencompassedbythemajorfederalholdingsoftheKenaiFjordsNationalPark,theKenaiNationalWildlifeRefuge,andtheChugachNationalForest.Themajorgroundtranspor-tationcorridorinthenorthwesternKenaiareaistheSterlingHighway(Route1).F.l.4.1.3AnchorageLanduseintheAnchorageregionismixedandownershipdiverse.LanduseinandsurroundingtheAnchoragemetropolitanareaincludesresidential,commercial,industrial,andrecreation.Litt1eagricultura1orforestresource1andsoccurwithinthegreaterAnchoragearea.TheU.S.ArmyandU.S.AirForcemanagelandsnearAnchorage.TheareaisservedbytheGeorgeParksHighway(Route3),GlennHighway(Route1),theAlaskaNationalRailroad,theAnchorageInternationalAirport,andanoceanport.
Table F-7.Land Uses Along Alternative Power Transmission Routes
Route Segment
Northern Study Area
(Fairbanks-to-Healy)
1.ABC (Proposed Route)
2.ABDC
3.AEDC
4.AEF
Central Study Area
(Upper and Middle
Susitna River Basin)
1.ABCD
2.ABECD
3.AJCF
4.ABCJHI
5.ABECJHI
6.CBAHI
7.CEBAHI
Length
(mi)
90
86
115
105
40
45
41
77
82
68
73
Land Use
Air s~rip;residential areas and isolated cabins;some U.S.
Military withdrawal and Native land.
No known existing right-of-way (ROW)north of Browne;scattered
residential and isolated cabins;airstrip;Fort Wainwright
Military Reservation.
No existing ROW beyond Healy/Cody Creek confluence;isolated
cabins;airstrips;Fort Wainwright Military Reservation.
Air strips;isolated cabins;Fort Wainwright Military
Reservation.
Little existing ROW except Corps Road;mostly village selection
and private lands.
Little existing ROW except Corps Road;and at D;recreation
and residential areas;float plane areas;mostly village
selection and private lands.
No existing ROW except at F;recreation areas;float plane
areas;mostly village selection and private land;residential
and recreational development in area of Otter Lake and Old
Sled Road.
No existing ROW;recreation areas and isolated caoins;lakes
used by float planes;much village selection land.
Same as Corridor 4
No known existing ROW;recreation areas and isolated cabins,
float plane area;Susitna area and near I are village and
selection land.
Same as Corridor 6
"I
N
<.0
Length
Route Segment (mi)
8.CBAG 90
9.CEBAG 95
10.CJAG 86
11.CJAHI 69
12.JA-CJHI 70
13.ABCF 41
14.AJCD (Proposed Route)
15.ABECF
Southern Study Area
(Willow-to-Anchorage)
1.ABC I
2.ADFC (Proposed Route)
3.AEFC
41
45
73
38
39
Table F-7.(Continued)
Land Use
No existing ROW;recreation areas and isolated cabins,float
plane areas;air strip and airport;much village selection
and Federal land.
Same as Corridor 8
No existing ROW;recreation areas and isolated cabins,float
plane areas;air strip and airport;mostly village selection
and Federal land.
No existing ROW;recreation areas and isolated cabins;float
plane area;mostly village selection and private land.
No existing ROW;recreation areas and isolated cabins;float
plane area;mostly village selection and private land.
No known existing ROW except at F;recreation areas;float
plane areas;residential and recreation use near Otter Lake
and Old Sled Road;isolated cabins;mostly village selection
land and some private land.
Little existing ROW except Old Corps Road and at 0;recreation
areas;isolated cabins;much village selection land;some
private land.
No known existing ROW except at F;recreation areas;float
plane areas;residential and recreation use near Old Sled
Road;isolated cabins;mostly village selection land with some
private land.
No existing ROW in AB,residential uses near Palmer;proposed
capitol site;much U.S.Military land,private and village
selection land.
Trail is only existing ROW;residential and recreation
areas;Susitna Flats Game Refuge;agricultural land sale.
No known existing ROW;residential and recreation use
areas,including Nancy Lakes;lakes used by float planes;
agricultural land sale.
.."
I
Wo
Conversion:To convert miles to kilometers,multiply by 1.61.
Source:Adapted from Exhibit E,Vol.9,Chap.10,Tables E.10.21 through E.10.23.
F-31F.1.4.2Coal-FiredGenerationScenarioF.1.4.2.1NenanaLanduseintheNenana/Healyareaisgenerallyoflowintensity.SomeagriculturallandsoccurimmediatelynorthofHealy.MiningactivitiesoccurintheNenanavicinityandextensivelyintheHealyarea.CommunitieslocatedbetweenNenanaandHealyinc1udeAnderson,Ferry,andSuntrana.DevelopmentiscontinuihgintheHealyarea.Amajorrecreationarea,theDenaliNationalParkandPreserve,islocatedtothesouthwestofHealy.TheU.S.AirForceClearM.E.W.S.MilitaryReserveislocatedinthevicinityofAnderson.Themajorityofthelandisinvariousstagesofthestate-selectionprocessandisclassifiedasselected,tentativelyapproved,orpatented.MajortransportationroutesincludetheGeorgeParksHighwayandtheAlaskaNationalRailroad.F.1.4.2.2WillowResidentialuseoccursintheWillowareaandincludestheHolsteinHeightssubdivisionandscatteredcabinsalongtheGeorgeParksHighwayandAlaskaRailroad.Stateandprivaterecrea-tionlandsalsooccurinthearea.AgriculturallandssaleshaveoccurredalongtheGeorgeParksHighwayintheWillowSubbasinareaandincludetheDeltaIslandagriculturaldisposallocated5mi(8km)southwestofWillow.Littleminingactivityoccurswithinthearea.MajortransportationroutesincludetheGeorgeParksHighwayandtheAlaskaRailroad.F.1.4.2.3CookInletLanduseandownershipintheCookInletareaisdiverse.Muchoftheregionisrelativelyremote,andcurrentlanduseisgenerallyoflowintensity.Dispersedrecreationactivitiesoccurwithintheregion.Naturalresourcesbeingdevelopedincludeoil,gas,coal,andtimber.TheCityofAnchorageisthemajormetropolitanarealocatedintheregionandisdescribedinSectionF.1.4.1.3.F.1.4.3CombinedHydro-ThermalGenerationScenarioF.1.4.3.1ChakachamnaLakeTheChakachamnaLakeareaisremote,andcurrentlanduseisdiverseandoflowintensity.Recreationa1activitieswithintheareaare1imitedbutincreasinginpopularity(Bechtel,1983).Futurelandusewillprobablyrevolvearoundresourceextraction,processing,andtrans-portation.Statelandclassificationintheprojectareaincludesresourcemanagementlandsandindustriallands.Resourcesintheareaincludeoil,gas,coal,andtimber.IndustrialsitesincludetheKodiakLumberdockingfacilityatNorthForelandandvarioussitesoperatedbyTexacoandAtlanticRichfield(Bechtel,1983).ThestatehassoldtimberrightstoKodiakLumberMi11s,Inc.on223,000acres(90,245ha)of1and.Anetworkof1oggingroadshasbeenconstructedtogainaccesstothetimber.Severalgasfieldshavebeendiscoveredonshore,andbothgasandoilfieldshavebeendiscoveredoffshore.State,Federal,andprivateleasesaleshaveoccurred.Twopetroleum-relatedfacilities,MarathonOilCompanyoilandgastreatmentplantandDriftRiverPetroleumTerminal,arelocatedonthewestsideofCookInlet(Bechtel,1983).ThethreemajorcoalleaseslocatedintheareaaretheCappsleasearea,theChuitnaleasearea,andtheThreeMileleasearea;mostoftheseareaswouldbeopen-pitmined.LandownershipandmanagementintheChakachamnaLakeareahavenotbeenmadefinal.LargeportionsofFederallandholdingshavebeenorareintheprocessofbeingtransferredtotheAlaskanNativesandthestate;and,subsequently,somelandswillbetransferredtotheKenaiPeninsulaBorough.Afewsmallparcelsareprivatelyowned,primarilyalongthecoast(Bechtel,1983).FederallandsintheareaincludetheLakeClarkNationalPark,LakeChakachamnapowersite,andanumberoftownshipssurroundingthepowersite.MostoftheBureauofLandManage-mentlandsarepassivelymanaged.State-ownedlandsarepresentlyclassifiedasresourcemanage-mentlandsandindustriallands.TheTradingBayStateGameRefugeislocatedinthealterna-tivesitearea.ThefourmajorownersandmanagersofNativelandsintheprojectareaaretheCookInletRegion,Inc.;TyonekNativeCorporation;NativeVillageofTyonek;andindividualNativeallotments.Fiveprivatelandholdingsareknowntooccurintheprojectarea(Bechtel,1983).F.1.4.3.2BrowneTheBrownesiteislocatedwithintheAlaskaRailbeltnearthevicinityofthecommunitiesofHealy,Suntrana,andFerry.Landuseisdiverseandoflowintensity.Dispersedrecreationuseoccursthroughoutthearea.ExtensivecoaldepositsandminingoccurinthevicinityeastofHealy.MajortransportationroutesintheareaincludetheGeorgeParksHighwayandtheAlaskaNationalRailroad.
F-32Asisthecaseelsewhereinthestate,landownershipandmanagementisinastateoffluxduetolandtransfers.ThelargestFederallandholdingintheareaistheDenaliNationalParkandPreserve,managedbytheU.S.ParkService.State,NativeAlaskan,andboroughlandsarelocatedatvariouspointsinthearea.PrivatelandholdingsaregenerallyconcentratedincommunitiesalongtheGeorgeParksHighwayandAlaskaNationalRailroad.Landuse,ownership,andmanage-mentforthisareaarediscussedfurtherinSectionF.l.2.2.F.1.4.3.3KeetnaLanduseintheKeetnaareaischaracterizedbydispersed,low-intensityrecreationandsub-sistenceactivities.ThecommunityofTalkeetnaislocatedabout15mi(24km)westofthesite.LanduseeastofTalkeetnaisdominatedbylanddisposalsalongtheTalkeetnaRiver.Theclosest1anddevelopment,consistingofseveralhomesteadsatParsonLake,isabout13mi(21km)southwest.RecreationactivitiesintheKeetnaareaincludeboating,fishing,andoff-roaddriving.Accesswithinthesiteareaislimited.ThenearestmajortransportationroutesaretheGeorgeParksHighwayandtheAlaskaNationalRailroad,locatedapproximately15mi(24km)westofthearea.Landownershipandmanagementarecurrentlyinastateofflux.FederallyownedlandoccursnorthofTalkeetna.ThelandonwhichtheAlaskaRailroadislocatedisalsoFederalproperty.RailroadlandholdingsexistinvariouslocationsalongtheRailbeltcorridor,includingeastofDenaliStatePark.ThelargeststatelandholdingsoccurnorthwestoftheKeetnasiteatDenaliStatePark.TheCookInletRegion,Inc.,hasappliedfortheselectionofstate-ownedlandsintheTalkeetnaarea.Mat-SuBoroughlandsgenerallyarearoundtheGeorgeParksHighwayarea.PrivateandleasedlandsoccursouthofCurry.MostoftheseprivatelandsarelocatedintheMontanaandTrappersCreekareaandeastofChaseandTalkeetna.Landuse,ownership,andmanagementforthisareaarediscussedfurtherinSectionF.1.2.2.F.1.4.3.4SnowTheSnowareaislocatedwithintheChugachNationalForest.Theforestismanagedformultipleuse.Intermittentlandusesintheregionincluderecreation,sporthuntingandfishing,sub-sistenceliving,seasonalresidences,andresourceexploration(Selkregg,1974).CommunitiesincludeMoosePasstothenorthandSewardabout20mi(32km)tothesouth.Majortransporta-tionroutesintheareaincludetheAlaskaHighwayandtheAlaskaNationalRailroad.F.l.4.3.5JohnsonIntermittentlandusesintheJohnsonareaincluderecreation,sporthuntingandfishing,sub-sistenceliving,seasonalresidences,andresourceexploration.SomeruralsettlementsarelocatedalongtheTananaRivereastoftheJohnsonRiverconfluence(Selkregg,1977).ThenearestcommunityisDotLake,locatedabout15mi(24km)eastoftheJohnsonsiteontheAlaskaHighway.Someagriculturalusealsooccursinthearea,with25%to50%oftheuplandsoilssuitableforfarming.F.l.4.3.6Nenana,ChuitnaRiver,andAnchorageLanduseandownershippatternsfortheNenanaareaaredescribedinSectionF.l.4.2.1.TheChuitnaRiverandAnchoragelanduseandownershippatternsaredescribedinSectionF.l.4.1.F.2ENVIRONMENTALIMPACTSF.2.1ProposedProjectF.2.1.1WatanaDevelopmentF.2.1.1.1ConstructionTheproposedconstructionoftheWatanadamandassociatedpower-generationandtransmissionfacilities(e.g.,substation);theimpoundmentarea;theconstructioncampandvillage;andthepermanentsettlementwouldproduceasignificantchangeinthecharacteranduseofthelandintheupperandmiddleSusitnaRiverBasinarea.Theremote,highlyinaccessible,largelyundis-turbedareawouldbecomeoneofgreaterhumanactivityanddevelopment.Landthatwasusedprimarilyfordispersedrecreationalactivities,subsistenceliving,andsmallminingoperationswouldbecomemorehighlydevelopedforhydroelectricpowergenerationandresultininducedresidential,commercial,recreation,andnaturalresourcedevelopment.Constructionactivitiesandtheassociatednoisearoundthedamandreservoirprojectareawouldadverselyaffectthosepersonsusingtheareaforrecreationalandsubsistencepurposes.Theproposeddamandreservoirwouldinundateapproximately36,000acres(14,600ha)oflandwithintheSusitnaRivervalley.TheWatanaimpoundmentwouldinundatesixstructures--ahuntinglean-to,fourcabins(twonolongerinuse),andacollapsedshack.Thelocationsoftheseand
F-33otherstructuresintheupperandmiddleSusitnaRiverBasinareaareshowninFigureF-2.TheWatanaconstructioncampandvillagewouldbelocatednortheastofthedamsitebetweenDeadmanandTsusenacreeks.Theconstructioncamp,temporaryvillage,andairstripwouldcoverabout290acres(120ha)ofwetlands.Facilitiesattheconstructioncampandvillagewouldconsistofdormitories,ahospital,recreationfacilities,administrativebuildings,singleandmulti-familydwellings,schools,stores,asewagetreatmentplant,andalandfill(Figs.F-5andF-6).Duringtheconstructionphase,increasedhumanactivitypatternsintheareasurroundingthecampandvillagewouldlikelyfurtherdisturbsurroundingvegetationandincreasepressuresonwildlifeandfisheriesresourcesbecauseofincreasedhuntingandfishing.TheseimpactsarediscussedfurtherinAppendicesJ,K,andL.ConstructionoftheWatanadamanditsassociatedfacilitieswouldrequirethetransferofownershipofsubstantialareasofFederal,Native,andprivatelandstothestateofAlaska.Thesetransferswouldoccureitherthroughactualpurchaseorthroughright-of-wayeasementforprojectlands.Atpresent,thetransferoflandsisacomplexprocessbecauseofthecurrentlandexchangesallowedundertheAlaskaStatehoodActof1958,theAlaskaNativeClaimsActof1971andtheAlaskaNationalInterestLandsConservationActof1981.Currentlandmanagementplansintheprojectareaarelimited.Landmanagementisessentiallypassivewithfewdefinitiveorcomprehensivemanagementplansorregulationsspecificallyapplicabletotheprojectarea.TheTalkeetnaMountainSpecialUseDistrict(managedbytheMat-SuBorough)wouldrequirepermitsforspecifieddevelopmentssuchasroads.Becauseofthelackofdevelopmentandlandexchangesoccurringintheprojectarea,landvaluedataforprojectlandsarealsolimited.Specificlandvaluesforrequiredprojectlandshavenotbeenestablished.Itisanticipatedthatlandvalueswouldnotbedetermineduntilthelandacquisi-tionprocessfortheprojectisstarted.F.2.1.1.2OperationTheremoteandnaturalcharacterofthelandintheupperandmiddleSusitnaRiverBasinstudyareawouldcontinuetochangeduringtheoperationoftheWatanadamandtheestablishmentofapermanenttown.Thepermanenttownsite,locatedtothenorthofthedam,wouldoccupyabout90acres(36ha)ofland.Thetownwouldconsistofacentralareawithapproximately20build-ings,ahospital,93singleandmultifamilydwellingunitsby1992(125unitsbytheyear2001),awaterandsewagetreatmentplantandalandfill.ThelocationandfacilitiesoftheproposedtownareshowninFigureF-6.MuchofthelandintheWatanaprojectareaappearstohavemoderatetoseverelimitationtoconcentrated,highdensity,humandevelopmentbasedonphysicallimitationssuchasslope,soil,drainage,soilland-bearingcapacity,andothernaturalconstraints(ExhibitE,Vol.8).Settle-mentpressurescouldincreaseneartheWatanadamsiteandpermanenttownasaresultofthepotentialdemandforincreasedrecreationservices(e.g.,supplystores,outfitters).Increasedhumanactivityanddevelopmentatthetownandincreasedrecreationactivitiesonandsurround-ingtheWatanareservoirwouldcausefurtherfundamentalchangesinthelanduseinthearea,degradingthevegetationandincreasingthepressureonhuntingandfishingresourcesintheupperandmiddleSusitnaRiverBasinarea.Thelandswithintheproposedprojectareaarenotconducivetofarmingactivities,andnoimpactstofutureagriculturaldevelopmentwouldbeexpectedasaresultofprojectoperation.Timberresourcescouldbeaffected.Atpresent,theseresourcesarevirtuallyundisturbedandpresentlyusedonlyasalocalfuelsourceandforbuildingmaterials.ForestlandswiththehighestpotentialcommercialvaluearelocateddownstreamfromtheconfluenceofPortageCreek,essentiallywithintheSusitnaRiverfloodplain.ThenewlycreatedroadandrailaccessfortheproposedWatanaandDevilcanyonprojectswouldallowforeasieraccessandexploitationoftimberresources.Also,increasedopportunitiesformineralexplorationandminingactivitieswouldresultfromincreasedaccessintotheareaandtheavailabilityofsupportservicesatthepermanentWatanadamsettlement.NewmineralexplorationandincreasedminingactivitiescouldcauseadditionaldevelopmentpressuresattheWatanadamsettlementforcommercialandindustrialsupportservicesassociatedwithmineralexplorationandminingactivities.TheactuallevelofresourcedevelopmenttooccurintheupperandmiddleSusitnaRiverBasinareaasaresultofprojectopel'ationwoulddependonnumerousfactors,includingtheamountandtypeofaccessintothearea,fina1 1andownershipandmanagementpatterns,resourcemarketdemands,1aborsupply,developmentconstraints,andtheactualqualityandquantityofmineralresourcefoundintheupperandmiddleSusitnaRiverBasinarea.LandvaluedatafortheWatanaprojectareaarecurrentlyunavailable.Thisisprimarilyduetotheon-goingchangesinlandownershipandthecurrentlackofdevelopmentanduseintheSusitnaRivervalleyareathatwouldindicateorassignalandvaluetoaspecificpieceofproperty.Althoughpreciselandvaluescannotbeascertainedforprojectlands,anindicationofrepre-sentativeAlaskanlandvaluesispresentedinSectionsF.l.2.1.3andF.l.2.2.3.Ingeneral,
)\I )SEWAGEf\-.TREATWENT<.\PLANT\!\..1,"!l-f.>ToiiAiNACCESSAOlOF-34=====TY~=======FENCE---~I,I!1~··~~LEGEND0)BASEBALL®SOFTBALL®SECURITYoHOSPtTAL@FIREaOILSPtLL®CAMPMANAGER'sOFf"la:oSOILSlAB®PARKINGAREAS®ADMINISTRATIONOFFICES@STORf®BUSSHElTERS®DORMITORIES@LAVNlllIY®COMMUHICATtONSCTR.@-®RECREATIONHALL@KITCHENaDINING@FOODSERVICEWAREHOUSE@WAREHOUSE@GY_®_GPOOL@....TENANCEGARAGE@F'lIMPHOUSE(WATER)@HOCKEYRINK@BACHELORDORMSWONT.TYPEA@BACHElORDORVSWGMT.TYPEB@10'PERMAWALK@16'PERMAWALK~MANAGER'sGUESTHOUSEl~OWNER'SGUESTHOUSE®CONTRACTOR'sGUESTHOUSE®STAFFCLUBHOUSE@GEH£RATIHGSTATION€1RELOCATEDCAMPHOUSfHGU60SPACES)@FOOTBALLFIELD.@FU-ELSTORAGETANK®WATERRESERYOfR@UfltWOR@HELI"'"SCALE200400FEETClINCH·200FEET)FigureF-S.ProposedWatanaConstructionCamp.Vol.3,PlateF36][Source:ExhibitF,
F-351--._....2.t~O~(I"),-\/l!!!!!!"""~200~_1"~FEET(IINCH•200FEET)SCALE.JCDMANAGERsOfFICES®G£H£RATINGSTATION@FIRESTATIONG)GASSTATION®SCHOOL®,SWIMMINGPOOLG)GYMNASIUM@STORE®RECREATIONCENTER@SEWAGECOLLECTIONPUMPSTATJOH@WATERPUMPSTATION@UTII,.IOOR@SEWAGETREATMENTPLANT@WATERTREATMENTPLANT@FUELSTORAGETANK150,OOOq)//~..~/illmc.:JPERMANENTNON-RESIDENTIALBLDG.~PERMANENTROADlIIIIIlPERMANENTMULTIFAMILYDWELLINGS12.UNITSFURNISHEDBYYEAR199216UNITS••2001[§]PfRMAH£NTSINGLEFAMILY'()WfLLIHGS21UNITSfURNISHEDBYYEAR19926UNITS•2001(!DPERMANENTHOSPITAl..E:Bi~~S:::~Y8:O~S~;:/UTILITI£516EA.-4BEDROOMSUNITS28'11'0'16EA.-2·•24'.50'KiEA.-3•72EA.-2•14'l60'200EA.-3•14'l60'E,3::3~~M=LOTSIUTlllTiESFURHISHEO240EA,-LOTSPACESc:JPARKINGAREASFigureF-6.ProposedWatanaConstructionVillageandPermanentTownFacilities.[Source:ExhibitF,Vol.3,PlateF37]
F-36landvaluesinAlaskahavegreatlyincreasedoverthepast15years,muchastheyhaveallovertheUnitedStates.AsaresultoftheWatanadamproject,landvalueswouldprobablyincreaseforpropertieslocatednearthepermanenttown,adjacenttothereservoirandaccessroads,alongtheDenaliandGeorgeParksHighways,andinthecommunitiesofTalkeetna,Cantwell,andGoldCreek.Futurelandvalueswoulddependinpartonthesupplyoflandmadeavailablebythemajorlandowners,parcelsize,locationinrelationtoaccess,naturalresourceslocatedontheproperty,andtheplannedtypeofdevelopment.Atpresent,nosinglecomprehensivelandmanagementplanexistsfortheentireupperandmiddleSusitnaRiverBasinarea.CurrentlandmanagersincludetheU.S.BureauoflandManagement(BlM),AlaskaDepartmentofNaturalResources(ADNR),theMatanuska-SusitnaBoroughandtheCookInletRegionInc.(CIRI).BlMlandswithintheDenaliPlanningBlockUnitareessentiallypassivelymanaged.BlMobjectivestoprotectthenaturalenvironment,especiallycariboucalvingareasandriverrecreationroutes,couldbeadverselyaffectedbyincreasedrecreationpressuresaroundtheWatanaprojectarea.AnotherBlMmanagementobjective,adequatefirecontrol,couldbeaffectedbyaninfluxofrecreationists.BlMisdevelopingawildlifehabitatmanagementplanincooperationwiththeAlaskaDepartmentofFishandGamefortheAlphabetHillsareabetweentheTyoneandMaclarenRivers.SincethisplanisinanearlydevelopmentstageitcannotbedeterminediftheplanwouldbeadverselyimpactedbytheWatanaproject.Atpresent,state-managedlandsintheproposedWatanadamareaarebeingpassivelymanaged.TheAlaskaDNRispreparingaresourceassessmentofstateselectedlandsinthearea(ExhibitE,Vol.8).ItisanticipatedthattheWatanaprojectwouldhavenosignificantimpactonthatassessmentplan.TheMatanuska-SusitnaBoroughisinvolvedinthreemanagementplansfortheprojectarea,includ-ingtheMat-SuBoroughComprehensivePlan,theTalkeetnaMountainsSpecialUseDistrict,andtheMat-SuBoroughCoastalManagementProgram.TheproposedWatanadamprojectshouldnotadverselyaffectthemanagementofboroughlandsasdescribedintheComprehensivePlan,sincemostoftheplanningeffortconcernsboroughlandsalongtheParksHighway,outsideoftheWatanadamprojectarea.IntheComprehensivePlantheprojectareaisclassedasamixed-usezone,whichwouldpermithydrodevelopment.However,theMat-SuBoroughhasplanningandzoningauthorityforalllandwithinthedistrictboundaries.TheTalkeetnaMountainSpecialUseDistrictalsoincludestheprojectarea.Theordinancethatcreatedthedistrictprovidesformultipleresourceuseofthedistrict,andlandsaresubjecttopermitrequirementsforspecifieddevelopments,suchasroadsandsubdivisions.TheWatanadamareaisnotconsideredtobewithinthecoastalzonemanagementareaandthuswouldnotdirectlyaffectorbeaffectedbytheCoastalManagementPlan.NoknownlandmanagementplansoractivitiesarecurrentlybeingadministeredbytheCookInletRegion,Inc.F.2.1.2DevilCanyonDevelopmentF.2.1.2.1ConstructionTheconstructionoftheproposedDevilCanyondamandassociatedfacilities,theimpoundmentarea,andtheconstructioncampandvillagewouldproducefurtherchangesintheuseandcharac-teroflandintheupperandmiddleSusitnaRiverBasinarea.AswouldbethecasefortheWatanaSite,theremote,highlyinaccessible,andlargelyundisturbedDevilCanyonareawouldbesubjectedtogreaterhumanactivityanddeve1opment.landthatisnowusedprimarilyfordispersedrecreationactivities(e.g.,hiking,hunting,andfishing),subsistenceliving,andsmallminingoperationswouldbeconvertedtoahighlydevelopedareaforgenerationofhydro-electricpower.Recreationandnaturalresourcedevelopmentintheareawouldalsoincrease.Developmentofthe32-mi(53-km)longreservoirwithanimpoundmentareaof7,900acres(3,200ha)wouldnotinundateanyexistingstructures.However,constructionactivitiesandthenoisearoundtheprojectareacouldadverselyaffectthosepersonsusingtheareaforrecrea-tion,subsistenceliving,andtrappingpurposes.TheDevilCanyonconstructioncampandvillagewouldbelocatedtothesouthofthedamsiteonapproximately185ac(75ha)ofland.Thetemporaryconstructioncampandvillagefacilitieswouldconsistofvariousstructures,includ-ingdormitories,ahospital,recreationfacilities,warehouse,administrativebuildings,singleandmulti-familydwellings,aschool,astore,asewagetreatmentplant,andalandfill(Figs.F-7andF-8).Theincreasedhumanactivityintheareasurroundingthecampandvillage,coulddegradesurroundingvegetationandwouldincrease pressuresonhuntingandfishing.However,nopermanenttownistobelocatedintheDevilCanyondamarea,andremovalofthecampandvillageuponthecompletionoftheconstructionprojectwouldeliminatethisparticularsourceofpressureonrecreationalactivitiesandnaturalresourcesinthearea.TheconstructionoftheDevilCanyondamandassociatedfacilitieswouldrequirethetransferofownershiporcontrolofsubstantialareasofFederal,Native,andprivatelandtothestate.Aspreviouslydiscussed,landtransferswouldoccureitherbyactualpurchaseorbyacquiringright-of-wayeasementsforprojectlands.Relationshipsbetweenconstructionimpactsandmanage-mentplansandlandvaluesaresimilartothosediscussedinSectionF.2.1.1.
~~STAFFANDFORENANHOUSING:2DORMITORiES3MANAGER'SGUESTHOOSEoOWNER'SGUESTHOUSEoCONTRACTOR'SGUESTHOUSE®CAM?MANAGER'sOFFICES(i)SECUR1TYoFIREAHOOILSPILLoHOSPITAL@HELIPAO{MEDICALEMERQENCYI@CDMM\HtICATlOH$CENTER@KITCHENANDDINING@STAFFCLUBHOUSE@RECREATIONHALL@BANK@LAUHORIES®SOILSLAB@FOODSERVICEWAREHOUSE@WAREHOUSE@MAINTENANCEGARAGE@PUMPHOUSE~GENERATINGSTATION@ausSTATION@PARKINGANDLAYOOWHAREAS!510'PERNAWALI(16IS'PERMAWALK21GYMNASIUM@SWIMMlHGPOct.€yHOCKEYRINK@.8ASE8ALLFIELD@SOFTBALLFIELD@FOOTBALLFIELD@FUELSTORAGE{W,OeDGALJ@STORE@UTlLIOOR@WATERTREATMENTPLANT®WATERRESERVOIRFigureF-7.F-371800(liNCH.200FEETIProposedDevilCanyonConstructionCamp.[Source:ExhibitF,Vol.3,PlateF72]\VILLAGEHOUSING-320UNITSFAMILYHOUSING-2B.R.-16UNITS(24',So')FAMILYHOUSING-3B.R.-16UNITS(24''SO')FAMILYHOUSING-4B.R.-16UNITS(2B',Sd)FAMILYHOUSING-3B.R.-72UNITS(14',60'>FAMILYHOUSING-3B.R.-200UNITS(14',60')18=11.~TEMPORARYHOUSING/UTILITIESFURNISHEOBYOWNER.PARKINGAREASSCHOOL-30',3S'02UNITS)GYM-100'x100'SWIMMINGPOOL-100',100'RECREATIONCENTER80',100'STORE-100'x160'FIRESTATtON-30'll40'GENERATINGSTATION-20'lt30'(2UNITS)UTILIOORSEWERPUMPINGSTATION-50'x60'oSCALE[200400FEETI(lINCH.200FEET)FigureF-8.ProposedDevilCanyonConstructionVillage.[Source:ExhibitF,Vol.3,PlateF73]
F-38F.2.1.2.2OperationTheremoteandnaturalcharacterofthelandintheDevilCanyonareawouldcontinuetobealteredwiththeoperationoftheDevilCanyondam,theinundationoftheDevilCanyonRapids,andtheopeningofthevisitorcenteratthedam.IncreasedhumanactivitiesaroundthedamandreservoirwouldplaceincreasedpressureonhuntingandfishingactivitiesintheSusitnaRiverregion.ThedevelopmentoftheDevilCanyonareaalsowouldincreasethelikelihoodofnaturalresourceexplorationanddevelopmentinthearea.ThepotentialimpactofsuchdevelopmentisdiscussedinSectionF.2.1.1.LiketheWatanadamprojectarea,muchofthelandintheDevilCanyonprojectareaappearstohavemoderatetoseverebuildinglimitationstoaccommodateconcentrated,high-densityhumandevelopment(ExhibitE,Vol.8).However,settlementpressurescouldincreaseneartheDevilCanyondamandreservoirareaasaresultofthepotentialdemandforincreasedrecreationservices.Asdiscussedpreviouslyland-valuedatafortheupperandmiddleSusitnaBasinareaarecurrentlynotavailable.Althoughspecificfuturelandvaluescannotbedetermined,itisanticipatedthatlandvalueswouldtendtoincreasearoundtheDevilCanyonreservoirarea.TheassumptionsandfactorsconcerningincreasedlandvaluesarediscussedinSectionF.2.1.1.Atpresent,nosinglecomprehensivelandmanagementplancurrentlyexistsfortheentireupperandmiddleSusitnaRiverBasinstudyarea.CurrentlandmanagementplansthatcouldbeimpactedbytheDevilCanyonprojectarethesameasdiscussedinSectionF.2.1.1fortheWatanadevelop-ment.F.2.1.3AccessRoutesTransportofmaterials,equipment,andpersonnelneededtoconstructthevariousSusitnaprojectfacilitieswouldnecessitatetheconstructionofaccessroadsfromDenaliHighwaytotheWatanadamsiteandfromWatanatotheDevilCanyondamsite,aswellasarailspurfromGoldCreektotheDevilCanyonsite.Constructionoftheseaccessfacilitieswouldcontributetosignificantlychangingtheuseandcharacterofthe1andintheupperandmiddleSusitnaRiverBasin.Forthefirsttime,thehighlyinaccessible,remote,andlargelyundisturbedSusitnaRiverareawouldbecomeaccessiblebyautomobiles,trucks,andheavyequipmentvehicles.Landthatisnowusedprimarilyfordispersedrecreation,subsistenceliving,andsmallminingoperationswouldbemadeaccessibleforlarge-scalehydropowerdevelopmentanditsvariousassociatedfacilities.Constructionactivitiesandtheassociatednoisecreatedwhiletheaccessrouteswerebeingbuiltwouldadverselyaffectthosepersonsusingtheareasforrecreationandtrapping.Theconstructionoftheaccessroadsandtherailspurwouldresultinthedestructionofvegetation,slumping,anderosionofsoilsduringtheconstructionperiod.ConstructionoftheaccessfacilitieswouldrequirethetransferofownershiporcontrolofFederal,Native,andprivatelandtothestateofAlaska.Thesetransferswouldoccureitherthroughactualpurchasesorright-of-wayeasements.Aspreviouslydiscussed,thetransferoflandinAlaskaisacomplexissuebecauseofthecurrentlandexchangesallowedundervariousFederalacts.Mostofthesignificantchangesinlandusepatternsthatwouldresultfromconstructionoftheaccessfacilitieswouldcontinueduringtheoperationalperiodoftheprojectandforaslongthereafterastheaccessrouteswereopenandusable.PreviouslyremoteareasinthevicinityoftheWatanaandDevilCreekdevelopmentswouldbeaccessibleforrecreation,mineralexploration,harvestingoftimber,andsettlement.Althoughthesechangescouldbeofpositivecommercialvalue,allwouldproduceincreasedpressureon,andinmanycasesdegrada-tionof,thenaturalresourcesofthebasinbecauseofunwanteddevelopment,conflictivelanduses,andunlimitedoff-roadaccess.Atpresent,nosinglecomprehensivelandmanagementplanexistsfortheentireupperandmiddleSusitnaRiverBasinareatoregulateuncontrolledaccess.Increasedaccessibilitycouldalsobeexpectedtoincreaselandvaluesintheopenedareas.Site-specificimpactsoftheseaccessfacilitiesarediscussedinmoredetailbelow.F.2.1.3.1DenaliHighway-to-WatanaRouteTheproposed40-mi(67-km)gravelaccessroadbetweentheDenaliHighwayandtheWatanasitewouldrequireabout630acres(255ha)ofland.Pulloutsandtrailheadswouldbeconstructedalongtheroutetopermitviewingandaccessintotheinteriorregionofthebasin.ThenewgravelroadwouldprovideaccesstothepermanenttownsitelocatednearWatanadam,aswellasaccesstoCIRIandvillagecorporationlands.TheAlaskaNativeshaveexpressedinterestinthedevelopmentoftheirlandsforrecreation,mining,andtimberactivities(ExhibitE,Vol.8)..1
F-39F.2.1.3.2Watana-to-DevilCanyonRouteTheproposed37-mi(60-km)WatanatoDevilCanyonroutewouldrequireapproximately400acres(160ha)ofland.Ahigh-levelsuspensionbridgewouldextendacrosstheSusitnaRiverbelowthedamsiteandconnecttheaccessroadwiththeterminusoftherailspurfromGoldCreek.TheaccessroadwouldalterthecurrentrecreationallandusepatternsurroundingHighLakeLodge.Outdoorrecreationalvehicleusewouldincreaseandcontributetohuntingandfishingpressuresaswellasthedegradationofvegetationinthearea.AlthoughnopermanenttownisplannedfortheDevilCanyon'area,increasedcommercialdevelopmentmayoccurinresponsetothenumberofpersonsvisitingthedamfacilitiesandtheproposedvisitorcenterorpursuingrecrea-tionopportunitiesinthearea.ImprovedaccesstotheminingareasalongPortageandGoldcreeksmightalsoimprovetheeconomicfeasibilityofmineralexplorationandmining.F.2.1.3.3RailAccess-to-DevilCanyonTheproposed12-mi(20-km)railextensionfromGoldCreektotheDevilCanyonsitewouldrequireabout72acres(29ha)ofland.Railaccesswouldallowforthetransportationofconstructionmaterials,equipment,andpersonneltotheDevilCanyondamsite.IncreaseddevelopmentwouldoccurinandsurroundingtheGoldCreekarea,whichwouldbeastagingareaforitemstobetransportedforconstructionofDevilCanyondamanditssupportfacilities.LanddevelopmentandfuturelandvaluesalongtherailspurwoulddependonwhetherpUblicuseoftherailfacilityisallowed.F.2.1.4PowerTransmissionFacilitiesAsisthecaseforotherproject-relatedfeatures,constructionofthevariouspowertransmissionfacilitieswouldcontributetosignificantchangesintheuseandcharacteroftheland.Inmanycases,landthatnowisusedprimarilyfordispersedlow-densityactivities,suchasrecrea-tionandsmallminingoperations,wouldbeclearedforthetransmissionlineright-of-way.Adjacentareasalsomightbemademoreaccessible.Insomecases,thelineswouldextendthroughdevelopedareas.Theconstructionandmerepresenceofthelinecouldalsoaffectadjacentlanduses.Constructionactivitiesandtheassociatednoisecreatedduringclearingofthetransmissionlinerights-of-way,constructionoftowerstructures,andstringingoftransmissionlinescouldadverselyaffectnearbyresidentsorrecreationists.TheconstructionofthetransmissionlineswouldrequirethetransferofownershiporcontrolofFederal,Native,andprivatelandstothestateofAlaska.Thesetransferswouldoccureitherthroughactualright-of-waypurchaseoreasementsofprojectlands.Aminimumstandardaccessroadwouldbecreatedalongtheentirelengthofthetransmissionlinerouteformaintenancepurposes.Routinemaintenanceactivitiesshouldnotadverselyimpactsurroundinglanduses.However,floatplaneflightpatternscouldbeadverselyaffectedwherethetransmissionlineextendednearlakesusedfortakeoffsandlandings.Becauseofthepresentlow-intensityuseandundeterminedlandvaluesalongmuchoftheproposedtransmissionlineroute,itisnotanticipatedthattherewouldbesignificantimpacttoadjacentlandvaluesalongmostoftheroute.However,theresalevalueoflandmightbelimitedforresidentialorrecreationallandslocatedadjacenttothetransmissionlineroute.Informationonspecificsegmentsofthetransmissionlinesystemisprovidedinthefollowingsections.F.2.1.4.1Dams-to-GoldCreekSegmentTheproposed4S-mi(72-km)longDams-to-GoldCreektransmissionlinesegmentwouldrequirea300-ft(90-m)right-of-waybetweentheWatanaandDevilCanyondamsandaSl0-ft(ISS-km)right-of-wayfromDevilCanyonDamtoGoldCreek.Totalright-of-wayrequirementswouldbeI,SOOacres(600ha)ofland.Thenewright-of-waywithintheremoteandnaturalareaoftheupperandmiddleSusitnaRiverbasinwouldallowincreasedrecreationalaccessintothearea,affectinghunting,fishing,trapping,andotherrecreationalactivities,However,becauseoftheremotelocationandlowintensityoflanduse,valuesoflandadjacenttotheright-of-wayarenotexpectedtobeadverselyaffectedbythetransmissionline.FloatplanetakeoffandlandingactivitiesintheHighLakeareacouldbeadverselyimpactedduetotheproximityoftheproposedtransmissionlines.
F-40F.2.1.4.2GoldCreek-to-FairbanksSegmentThe185-mi(300-km)transmissionlinesegmentbetweenGoldCreekandFairbankswouldoccupya300-ft(90-m)right-of-way.However,betweenGoldCreekandtheHealysubstation,thetrans-missionlinewouldparallelthe110-ft(34-m)wideAnchorage-FairbanksTransmissionIntertieforapproximately95mi(145km)andrequireonly190ft(58m)ofnewright-of-way.Onlyincre-menta1impactson1andusewouldbeexpectedbecauseof theexistenceoftheIntertieTrans-missionLine.FromtheHealySubstationtotheterminusattheEsterSubstation,anew300-ft(90-m)transmissionlineright-of-waywouldbenecessary.Totalright-of-wayrequirementsbetweenGoldCreekandFairbankswouldbeapproximately5,500acres(2,200ha)ofland.LanduseconflictscouldoccurinthecommunitiesofCantwell,Healy,Nenana,andEster,andinothel'moresparselysettledresidentialareasadjacenttothetransmissionline,suchasLignite,Ferry,Browne,andothersmallresidentialareasalongtheGeorgeParksHighwayandAlaskaNationalRailroad.Approximately12.5mi(20km)ofexistingorproposedagriculturalsalelandswouldbetraversedbythetransmissionlinecorridorbetweenGoldCreekandFairbanks(ExhibitE,Supp1.Information,Sec.9,Item7).TheselandsarelocatedattheGoldstl'eam,Windy,andHealyagriculturaldisposalsiteareas.Totallandacreageimpactedduetoconstruc-tion,towerplacement,andaccessrequirementswoulddependontheamountoflandactuallydevelopedforagriculturaluse,finalright-of-wayalignment(e.g.,alongfencelinesoraccessfields),andtypeofagriculturaluse(e.g.,pastureorrowcrops).However,itisanticipatedthatthetotalamountofpotentialfarmlandthatwouldberequiredfortowerplacementwouldbeminimal[6to11acres(2-4ha)].TheHealy-to-Fairbankssegmentalsowould'extendacrossabout10mi(16km)theU.S.AirForceClear/4.E.W.S.MilitaryReservenearAnderson.Theproposedtransmissionlineandclearedright-of-waycouldpotentiallyaffectexistingandplannedmilitaryactivitiesandsecurity.LanduseconflictsalsocouldoccurwheresectionsofthenortherntransmissionlinesegmentwouldextendacrosslandthathasbeendesignatedforvillageselectionwithintheboundariesofDoyon,Ltd.Dependingonfinalalignmentoftheproposedtransmissionlines,takeoffsandlandingsatlandingstripsandfloatplanesitescouldbeadverselyaffectednearNenana,Healy,Cantwell,andGoldCreek.F.2.1.4.3GoldCreek-to-AnchorageSegmentThe145-mi(233-km)powertransmissionlinesegmentbetweenGoldCreekandAnchoragewouldbeona400-ft(120-m)right-of-way.BetweenGoldCreekandtheWillowsubstationthetransmissionlinewouldparalleltheAnchorage-FairbanksTransmissionIntertieforabout75mi(120km)andrequireonly290ft(88m)of the400-ft(122-m)right-of-way.Becauseof theexistenceoftheIntertieTransmissionLine,onlyincrementalimpactstolandusewouldbeexpected.FromtheWillowsubstationtotheterminusatAnchorage,anew400-ft(122-m)transmissionlineright-of-waywouldbenecessary.Totalright-of-wayrequirementsbetweenGoldCreekandAnchoragewouldbeabout4,700acres(1,900ha)ofland.Landuseconflictscouldoccurinareasofmoderateconcentrationsofresidentialdevelopment,suchasinthecommunitiesofTalkeetna,Willow,andAnchorage,andinotherresidentialareasadjacenttothetransmission1ine.Dependingonfina1transmission1inealignment,upto16.5mi(26.5km)ofpotentia1agricultura1 1andbetweenGo1dCreekandAnchoragecou1dbetraversedbythetransmissionlineattheGooseCreekAgriculturaldisposal,FishCreekManage-mentUnit,andPointMacKenzieAgriculturalSale(ExhibitE,Suppl.Information,Sec.9,Item7).However,themaximumamountofpotentialfarmlandtobeusedfortowerplacementwouldbeminimal[9to15acres(4-6ha)J.Theroutewouldextendacross5mi(8km)ofthenortheastcorneroftheSusitnaFlatsStateGameRefuge.PotentialimpactstotherefugearediscussedinAppendixK.About18mi(29km)ofthetransmissionlinewouldextendacrosstheFortRichardsonMilitaryReserveandcouldadverselyaffecttrainingmaneuversandbasesecurity.TheproposedlinewouldalsoextendneartheElmendorfAirForceBaselandsnearAnchorage.Thetransmissionlinelocations,design,andtowerheightcouldadverselyaffectflightactivities,communications,andbasesecurity.Also,dependingonfinaltransmissionlinealignment,takeoffsandlandingscouldbeadverselyaffectedatlandingstripandfloatplanelandingsitesnearGoldCreek,Curry,Willow,andsouthofWillow.LanduseconflictsalsocouldoccurwheresectionsofthetransmissionlinecorridorextentedacrosslandsownedbyCIRI.Theproposedtransmissionlinewouldcrossorparallelnumeroustrails,includingtheIditarodTrail,seismicsurveylines,tractorandpioneeringORVtrails,andseveralrecreationtrailsnearWillow.F.2.2SusitnaDevelopmentAlternativesF.2.2.1AlternativeDamLocationsandDesignsTheconstructionandoperationofthealternativesinvolvingtheWatanaI,Reregulating,and~10difiedHighDevilCanyondamswouldresultinessentiallythesametypeoflanduseimpactsdiscussedinSectionF.2.1.1andF.2.1.2.TheModifiedHighDevilCanyondamwouldinundateapproximately6,800acres(2,750ha)ofland.TheWatanaIandReregulatingdamswouldinundate28,300acres(11,450ha)and4,000acres(1,600ha),respectively.Theremote,highlyinaccess-ible,largelyundisturbedupperandmiddleSusitnaRiverBasinwouldbecomeoneofgreaterhuman
F-41activityanddevelopmentasaresultoftheconstructionandoperationofhydroelectricpowergenerationfacilitiesandassociatedinducedresidential,commercial,recreation,andnaturalresourcedevelopments.F.2.2.2AlternativeAccessRoutesInasimilarfashionastheproposedaccessroute,thenorthernandsouthernalternativeaccessrouteswouldmakethehighlyinaccessibleandremoteSusitnaRiverareaaccessiblebyauto-mobiles,trucks,andheavyequipmentvehicles.Landthatisnowusedprimarilyfordispersedrecreation,subsistenceliving,andsmallminingoperationswouldbemadeaccessibleforlarge-scalehydropowerfacilitiesandassociateddevelopment.The48-mi(77-km)northernaccessroute(corridor1)wouldimpactlandsalongthenorthsideoftheSusitnaRiverfromHurricane(alongtheGeorgeParksHighway)totheWatanadamsiteandalonga7-mi(ll-km)roadspurtotheDevilCanyondamsite.Thenorthernaccessroutewouldrequireabout810acres(330ha)ofland.Thesouthernaccessroutealternative(corridor2)wouldimpact12mi(19km)oflandalongthesouthsideoftheSusitnaRiver(railspurbetweenGoldCreekandtheDevilCanyondamsite)andanother35mi(56km)of1andsbetweentheDevi1CanyonandWatanadamsites.Thesouthernaccessroutewouldalsoincludea20mi(32km)accessroadbetweentheDevilCanyondamsiteandHurricanelocatedalongtheGeorgeParksHighway.Thesouthernaccessroutewouldrequireabout980acres(400ha)ofland.F.2.2.3AlternativePowerTransmissionRoutesIngeneral,theconstructionandoperationofthealternativepowertransmissionroutesegmentswouldresultinthesametypesoflanduseimpactsdiscussedinSectionF.2.1.4.Totallandarearequiredwouldvarydependingonthesegmentconfigurationofthetransmissionline.ApproximateacreagesrequiredandpotentiallanduseimpactsforthealternativesegmentsareshowninTableF-8.F.2.2.4AlternativeBorrowSitesAllthealternativeborrowsitesarelocatedwithintheupperandmiddleSusitnaRiverBasin.Landuseimpactsassociatedwiththea1ternativeborrowsiteareasarediscussedinSec-tionsF.2.1.1andF.2.1.2.Borrowsiteslocatedcompletelywithintheproposedareasofinunda-tionforWatanaandDevilCanyondamswouldhavenolong-termimpactstosurroundinglanduse.TwoborrowareaslocatedalongTsusenaCreek(SiteC)andadjacenttoFogCreek(SiteH)wouldrequiretheconstructi.onofextensivehaulroads,whichcouldpotentiallyimpactfutureadjacentlanduse.F.2.3Non-SusitnaGenerationAlternativesF.2.3.1Natural-Gas-FiredGenerationScenarioEachofthe200-MWcombinedcycleunitsand70-MWcombustionturbinesfor.thenaturalgas-firedgenerationscenariowouldrequirea5-acre(2-ha)site.Therefore,atotalofonly50acres(20ha)oflandwouldbeneededforthetencombined-cycleandcombustion-turbineunits.Inaddition,right-of-waywouldberequiredforgaspipelinespursandpowertransmissionlinestotheplant.Dependingonfinalplantsitings,significantlanduseimpactscouldoccurifextendedaccessortransmissionlinerouteswouldberequiredtothealternativesitesorifthesitelocationswereadjacenttoanexistinglandusethatwasnotconsideredtobecompatiblewithanindustrialuse(e.g.,dispersedrecreationorresidentialarea).Itisestimatedthatover9,000acres(3,600ha)oflandwouldberequiredfortransmissionlinefacilities.Thelandrequirementsandmajorregionallandusesthatwouldbeaffectedbythenaturalgas-firedgenerationscenarioareshowninTableF-9.F.2.3.2Coal-FiredGenerationScenarioTheconstructionandoperationofcoal-firedgenerationplantscouldproducesignificantlanduseimpactsatallthealternativesites.Approximately200to300acres(80to120ha)wouldbeneededfortheplantandassociatedstructures,coalunloadingfacilities,andcoalstoragepiles;andanadditional1.5acres(0.6ha)oflandperyearwouldberequiredforwastedisposal.Inaddition,itisestimatedthattosupplycoalfora200-MWcoal-firedpowerplantunitwouldrequirestripmining450acres(180-ha)oflandoverthe30-yearlifeoftheplant.Thefive200-MWcoal-firedunits(locatedatNenanaandWillow)andthe ten70-MWgascombustionturbinesforthecoal-firedgenerationscenariowouldrequireatotalof600acres(240ha)forplantsitefacilities,225acres(90ha)oflandforwastedisposalsites,andabout2,250acres(910ha)oflandforsurfacecoalminingoperationsdw'ingthe30-yearoperatinglifeofthefacilities.Similartothenatul'al-gas-firedgenerationscenario,additionalimpactscouldresultfromadditionallandrequirementsforpipelineandtransmissionlineright-of-wayextend-ingfromtheplantsitestoexistingutilitycorridors.Also,itisestimatedthatmorethan9,000acres(3,600ha)oflandwouldbel'equiredfOI'transmissionlineright-of-way.Theland
F-42TableF-8.LandRequirementsandPotentialConflictiveUsesAlongtheAlternativePowerTransmissionRoutesSegmentLength(mi)AcreageRequiredt1PotentialConflictiveLandUseImpactNortnernStudyArea(Fairbanks-to-Healy)1.ABC(Proposed)2.ABDC3.AEDC4.AEF903,300Minimalconflictiveuse863,200Naturalareas1154,200Naturalareas1053,800ActivebombingrangeCentralStudyArea(UpperandMiddleSusitnaRiverBasin)1.ABCD2.ABECD3.AJCF4.ABCJHI5.ABECJHI6.CBAHI7.CEBAHI8.CBAG9.CEBAG10.CJAG11.CJAHI12.JA-CJHI13.ABCF14.AJCD(Proposed)15.ABECFSouthernStudyArea(Wi1low-to-Anchorage)1.ABCI2.ADFC(Proposed)3.AEFC4045817782687390958669704141457338391,7001,9001,3004,1004,3003,5003,7004,7005,1004,7003,5003,6001,5001,5001,8003,6002,0001,900ExtensiveNativeVillageselectionandprivatelandsResidentialandrecreationalusenearStephanLakeRecreationaluseatHighandOtterlakesRecreationallandusenearHighLakeRecreationallandusenearHighLakeandStephanLakeNewaccesswouldberequired;impactstonaturalareaandrecreationlandsResidentialandrecreationalfacilitiesnearStephanLakeRecreationaluse;floatplaneandlandbasedairstripsRecreationalusenearStephanLakeRecreationaluseRecreationaluse;naturalareasExtensiveNativeVillageselectionandprivatelandsRecreationalusenearOtterLakeRecreationalusenearHighLakeRecreationaluseatStephan,High,andOtterlakesExtensivedevelopedareasbetweenEklutnaandAnchorage;militarylandsPlannedagriculturalsales;SusitnaFlatsGameRefuge;residentialareasResidentialdevelopment;NancyLakeRecreationAreat1Basedon36.4acres/milefor300-ftright-of-way,48.5acres/milefor400-ftright-of-way,and61.8acres/milefor510-ftright-of-way.Conversion:Toconvertmilestokilometers,multiplyby1.61;toconvertacrestohectares,multiplyby0.405;toconvertfeettometers,multiplyby0.305.
Table F-9.Land Requirements and Major Regional Land Use Affected by the Natural-Gas-Fired
Generation Scenario
Alternative Site Number Acreage
Location Plant Typet 1 of Units Requiredt 2 Major Regional Land Use
Lower Beluga River Combined-cycle 2 10 Recreation/natural resource
Chuitna River Combined-cycle 3 15 Recreation/natural resource
Kenai Combined-cycle 2 10 Recreation
Southeast of Anchorage Combined-cycle 1 5 Recreation
Anchorage Combustion-turbine 2 10 Residential/commercial/industrial
TOTAL 50
t l Combined-cycle units would be 200 MW each;combustion-turbine units would be 70 MW.
t 2 Does not include land and easement requirements for access routes,pipeline right-of-way,and transmission line
right-of-way.
Conversion:To convert acres to hectares,multiply by 0.405.
.."
I
-""LV
Table F-I0.Land Requirements and Major Regional Land Use Affected by the Coal-Fired Generation Scenario
Acreage Requiredt 2
-n
I.p.
.p.
Major Regional Land Use
Recreation
Residential/recreation
Recreation/natural resources
Residential/commercial/industrial
Residential/recreation
Surface
Miningt 3
Temporary
Solid Waste
Disposalt 3
90 900
135 1,350
0 0
0 0
0 0
225 2,250
200 MW each.
10
250
300
5-10
30-35
595-605
Permanent
Plant
Facilities
Alternative Number
Site Locations Plant Typet!of Units
Wi 11 ow Coal unit 2
Nenana Coa I uni t 3
Tyonek/Be I uga Combustion-turbine 6-7
area gas
Anchorage Combustion-turbine 2
gas
Kenai Combustion-turbine 1-2
gas
TOTAL
F Combustion-turbine units would be 70 MW each;coal units would be
t 2 Does not include land and easement requirements for access routes,pipeline right-of-way,and transmission line right-of-way.
t 3 Assumes 30-yr operating life of each unit.
Conversion:To convert acres to hectares,multiply by 0.405.
F-45requirementsandmajorregionallandusesthatwouldbeimpactedbythecoal-firedgenerationscenarioareshowninTableF-10.F.2.3.3CombinedHydro-ThermalGenerationScenarioIngeneral,thetypesoflanduseimpactsthatwouldbeincurredatthealternativedamsiteswouldbesimilartothosedescribedinSectionF.2.1.Thehydroportionofthecombinedhydro-thermalalternativewouldinundateabout102,000acres(41,300ha)ofland,notincludinglandsrequiredforaccessroutes,powertransmissionright-of-ways,borrowareas,orsupportfacilities(e.g.,constructioncampsites).TheBrownealternativewouldinundate10,640acres(4,310ha)andcausesignificantlanduseimpactsbyinundatingportionsoftheexistingGeorgeParksHighwayandAlaskaRailroad.TheJohnsonsitewouldresultinsubstantialacreage[84,000acres(33,990ha)Jbeinginundated,includingaportionoftheAlaskaHighway(Route2)andanoilproductspipeline.LanduseimpactswouldbeminimalattheChakachamnasitesincenodamandassociatedreservoirwouldberequired.Landuseimpactsinrelationtothethermal(coalandgas)portionofthecombinedhydro-thermalalternativewerediscussedinSectionsF.2.3.1andF.2.3.2.Thelandrequirementsandmajorregionallandusesthatwouldbeimpactedbythecombinedhydro-thermalgenerationscenarioareshowninTableF-ll.F.2.4ComparisonofAlternativesF.2.4.1SusitnaDevelopmentAlternativesTheconstructionandoperationofthein-basindamalternativeswouldresultinthesametypeoflanduseimpactsdiscussedfortheproposedprojectinSectionF.2.1.AllthealternativedamsiteswouldchangethecharacteranduseofthelandintheupperandmiddleSusitnaRiverBasinfromaremoteandlargelyundisturbedareatooneofgreaterhumanactivityanddevelopment.ThealternativeaccessrouteswouldaffecttheleveloflandusedevelopmentindifferentareasoftheupperandmiddleSusitnaRiverBasin.ThenorthernaccessroutewouldpromotegreaterlanduseactivityanddevelopmentalongthenorthsideoftheSusitnaRiverbetweenHurricaneandtheDevilCanyonandWatanadamsites,whereasthesouthernaccessroutewouldpromotelandusedevelopmentalongthesouthsideoftheSusitnaRiverbetweenGoldCreekandthedamsitesandfromtheDevilCanyondamsitenorthtoHurricanelocatedontheGeorgeParksHighway.TheproposedaccessroutewouldpromotedevelopmentfromalongtheDenaliHighwaytothedamsitesandfromtheDevilCanyondamsitetoGoldCreek.Concerningthealternativepowertransmissionroutes,inthenortherncorridorarea(Healy-to-Fairbanks),alternativesABCandABDCwouldimpactlandsalongtheGeorgeParksHighwaybetweenHealyandBrowneandalsowouldextendacrossaportionoftheU.S.AirForceCLEARmilitaryreservationlands.ThealternativerouteABCwouldagainextendnearlandsalongtheGeorgeParksHighwaynorthofGoldstreamCreektotheEstersubstation,whilealternativerouteABDCwouldextendthroughamoreisolatedareatotheeastofthehighway.AlternativesAEFandAEDCwouldimpactlandsalongHealyCreek,theWoodRiver,andtheopenflatlandareasouthofFairbanks.Inaddition,alternativeAEFwouldextendacrosstheBlairLakeAirForceactivebombingrangeandFortWainwrightMilitaryReservation.Ingeneral,thealternativetransmissionroutesinthecentralcorridorarea(UpperandMiddleSusitnaRiverBasin)thatextendfromtheproposeddamsiteareasnorthtowardstheDenaliHighwayortheGeorgeParksHighwayintheBroadPassAreawouldproducegreaterlanduseimpactsthanthoseroutesegmentsextendinginaneasterlydirectiontowardGoldCreek.Thisisprimarilyduetothegreaterlandacreagerequired,andextendingthroughanessentiallynaturalareaproposedforrecreationdevelopment.Inaddition,segmentABwouldparallelthescenicDenaliHighwayareaforabout23mi(37km),whichisusedbyrecreationistsforscenicroadtouring.Inthesoutherncorridorarea(Willow-to-Anchorage),alternativerouteABC'wouldimpactlandsalongtheLittleSusitnaRiverValley,aroundthecommunityofPalmer,andalongtheGlennHighwaytoAnchorage.AlternativeADFCwouldimpactresidentialandrecreationalareasintheRedShirtLakeregion,andAlternativeAEFCwouldimpactlandsalongtheeasternedgeoftheNancyLakeStateRecreationarea.Allofthetransmissionlinesegmentsmentionedabovewouldresultingreaterimpactstolandusethantheproposedtransmissionlineroute.MostoftheborrowsiteswouldproducelanduseimpactssimilartothosediscussedinSec-tionF.2.1.OnlyborrowsitesCandHnearTsusenaandFogCreekswouldrequireextensivehaulroadsthatmightcauseunwantedaccessordevelopment.F.2.4.2PowerGenerationScenariosAcomparisonoflandacreagesrequiredandthemajorregionallanduseaffectedbythealterna-tivepowergenerationscenariosispresentedinTableF-12.Thecomparisonindicatesthatthenatural-gas-firedgenerationscenariowouldrequiretheleastamountoflandandwouldhave
Table F-11.Land Requirements and Major Regional Land Use Affected by the Combined Hydro-Thermal Generation Scenario
Acreage Reguiredt 2
Alternat i ve Number With Without
Site Location Plant Typet 1 of Units Chakachamna Chakachamna Major Regional Land Use
Johnson Hydro (dam and impoundment)-84,000t 3 84,000t 3 Recreation
Keetna Hydro (dam and impoundment)-4,800t 3 4,800t 3 Recreation
Snow Hydro (dam and impoundment)-2,600t 3 2,600t 3 Recreation
Browne Hydro (dam and impoundment)-10,640t 3 10,640t 3 Recreation
Lake Chakachamna Hydro (lake tap)-Negligiblet 3 0 Recreation
Nenana Coal unit 1 695t 4 695t 4 Recreation/Residential
Chuitna River Combined-cycle gas 2 10 10 Recreation/Natural Resource
Anchorage Combustion-turbine gas 3 15 15 Residential/Commercial/Industrial
"Lower Beluga River Combined-cycle gas 1 or 2t 5 5 10 Recreation/Natural Resource I
-I:>
O'l
TOTAL 102,765 102,770
t 1 Combined-cycle and coal units would be 200 MW each,combustion-turbine units would be 70 MW each;hydro units would vary.
t 2 Does not include land and easement requirements for access routes,pipeline right-of-way,and transmission line right-of-way.
t 3 Acreages are estimates only of area to be inundated.Land area required for support facilities (e.g.,construction camp,airstrip,etc.)is
not included.
t 4 Includes 200 acres for plant facilities,45 acres for solid waste disposal,and 450 acres for surface mining over the 30-year operating life
of the unit.
t 5 One unit with Chakachamna and two units without Chakachamna.
Conversion:To convert acres to hectares,multiply by 0.405.
Table F-12.Comparison of Land Requirements and Major Regional Land Uses Affected by the Power Generation Scenarios
Acreage Requirements
Dams,Impoundmentst 1 ,Temporary Facilities,
Construction of Per-Borrow Areas,Waste Transmission Potential Land
Scenario manent Facilities Access Disposal,Miningt 2 Facilitiest3 Total Use Affectedt 4
Proposed Susitna Project
Watana-Devil Canyon 44,900 1;100 6,400 11,700 64,100 A,C
Alternative Susitna Developments
Watana I-Devil Canyon 36,200 1,100 6,400 11,700 55,400 A,C
Watana I-Reregulating dam 32,300 1,100 6,400 11,700 51,500 A,C
Watana I-Modified High Devil Canyon 35,100 1,100 6,400 11,700 54,300 A,C
Natural Gas-Fired 50 U.D.t 5 N.A.t 6 9,OOO+t 7 9,050+A,C
Coal-Fired 600 U.D.2,475 9,000+12,075+A,B,C
Combined Hydro-Thermal "I
"'"Johnson,Keetna,Snow,Browne,Chakachamna 102,040 U.D.U.D.13,600 115,640+A,C -...J
Thermal units 230 U.D.495 200+925+A,B,C
Total 102,270 U.D.495+13,800+114,340+
Johnson,Keetna,Snow,Browne 102,040 U.D.U.D.12,300 114,340+A,C
Thermal Units 235 U.D.495 200+930+A,B,C
Total 102,275 U.D.495+12,500+115,270+
t l Total area inundated.
t 2 The use of the word temporary implies that the area would eventually be rehabilitated.
t 3 For natural-gas-fired,coal-fired,and combined hydro-thermal scenarios,assumes (1)construction of two 345-kV lines from Willow to
Anchorage and from Healy to Fairbanks and (2)upgrading of existing Intertie between Healy and Willow to two 345-kV lines as well as
construction of lines described in Sections 2.3.3 and 2.5.3 to the various dam sites and thermal units.
t 4 Land Use designations:A =Recreation,B =Residential,C =Natural setting.
t 5 U.D.=Undetermined.
t 6 N.A.=Not applicable.
t 7 "+"indicates an additional undeterminable acreage;these amounts would likely be higher for hydro sites than for thermal sites because of
greater constraints on siting.
Conversion:To convert acres to hectares,multiply by 0.405.
F-48fewerdirect1anduseimpactstosurroundingareasthantheotherscenarios.Thecombinedhydro-thermalgenerationscenariowouldrequirethegreatestamountofacreageforprojectfacilities.Inparticular,theBrownesitewouldsignificantlyimpacttransportationandutilitycorridorsbyinundatingportionsoftheGeorgeParksHighwayandAlaskaRailroad,whiletheJohnsonsitewouldinundateportionsoftheAlaskaHighwayandapetroleumproductspipe-line.Althoughthecoalgenerationscenariowouldrequiresignificantlylessacreagethanthecombined-hydt'o-thermalalternative,coal-firedplantlocationsatNenanaandWillowcouldadverselyaffectsurroundingrecreationalandresidentiallands.F.3MITIGATIONF.3.1MitigativeMeasuresProposedbytheApplicantThelandusemitigationmeasuresproposedbytheapplicantweredevelopedinrelationtothevariousproposedprojectfacilitiesandaredescribedinAppendixE(Vol.8,Chap.9).Thesemitigativestrategiesincludethefollowing.F.3.1.1DamsandImpoundmentAreasThe1andmanagementplansdevelopedwiththecooperationofjurisdictiona1agencieswou1dincludecontroloflanduseactivitiesandwouldbeimplementeduponoperationofthefacilities.Theplanswoulddirectlanduseactivitiesforthereductionoftheimpactonthegame,fish,andfurbearersresultingfromincreasedlanduseactivity.F.3.1.2ConstructionCampsandVillagesProposeddevelopmentfocusesrecreationalactivitiesoncorerecreationalfacilitiesandindirectlydivertstheusersawayfromsensitiveenvironmentalareasoutsidetheprojectarea.Impactsfromhumanusecouldbereducediftrailsoutsidetheproposedcampsareestablishedandifspecificareasaredesignedforleisureactivity.Landuseactivitiescouldalsobeconfinedtoprojectconstructionareastodiscourageincreasedhunting,fishingandtrappingintheprojectarea..Postingandenforcingconstructioncampruleswouldhelpmakeprojectpersonnelawareofadverseenvironmentalimpacts.Othermitigationmeasurestoreduceincreasedlandusedevelopmentofthecampandvillagemightincluderestrictingtheuseofprivatevehiclesandprovidingtrans-portationservices.Transportationservicescouldincludeair,bus,orvanservices,parkandridelots,travelschedulesand/ortravelallowances.Travelservicesmayalsoinfluencecon-structionworkertravelschedules,whichwouldalleviatepressureonlandusedevelopmentandactivity.Impactsfromfacilitiesassociatedwithhousing,suchassewagetreatmentlagoonsandlandfills,couldbereducediftheyarelocatedawayfromexistingorproposeddevelopments.F.3.1.3RecreationalUseTheimpactsofconstructionandoperationactivitiesextendbeyondthephysicalareasbeingdisturbedandcouldbepartiallymitigatedbycarefulmanagementoftheremaininglandsforpublicrecreationandappreciation.TherecreationplanproposedfortheSusitnaHydroelectricProjectwouldprovideorganizedrecreationaldevelopmentforprojectwatersandadjacentlands.RoadandORVaccesswouldbelimited.Otheraccessoptionssuchasboating,hikingandskiingwouldbeprovidedincertainareas.Recreationaldevelopmentfocusesactivitiesoncorerecrea-tionalfacilitiesanddivertsthegreatestnumberofusersawayfromsensitiveoperationsorenvironmentalareas.F.3.1.4AccessRouteCorridorsToreduceimpactsfromtheproposedaccessroute,severalmanagementtechniquescou1dbedesigned.Theaccessrouteshouldnotcrossunstablesoilsorwetlandstothegreatestdegreepractical.Disturbedsitescouldberestoredtoastablecondition.Stagingareasandparkinglotsusedduringconstructioncouldbeplannedanddesignedtobeusedforfuturescenicandrecreationpulloutsforthepublic.Afireprotectionandpreventionplancouldbeformulatedtodecreasethefirehazardassociatedwithincreasedaccess.Landuseactivitywouldbeconfinedtowithinprojectconstructionareasuntilthefacilitiesarebuilt.Thiswouldreducetheimpactoflanduseactivityuntiltheimplementationofthelandusemanagementplanstakeplace.Iftheuseofoff-roadvehicles(ORV)originatingfromtheaccessroutebecomesadisturbance,measureswouldneedtobetakentoinhibitthisactivity.Suchmeasureswouldincludeabufferstripdesignatedfornon-motorizeduseadjacenttotheaccessroute,naturalconditionsemployedassubtlebutabsolutedeterrentstoORVuse,designatedandplannedORVtrailsinlocationsthatwouldneitherconflictwithotherlandusenordamagetheenvironment,and,ifnecessary,ORVrestrictionbetweentheproposeddamsites.Spurroadstoprivateholdingsandminingclaimswouldbedesigned,located,andConstructedsimilarly.Recreationaluseextendingfromtheaccessroutewouldbedirectedtositesdesignedtosupportsuchuse.
F-49F.3.1.5TransmissionLineCorridorsEffortsweremadetose1ecttransmission1ineroutesthatwouldm1n1m1zenegativeimpact.Properalignmentofthetransmissionlineright-of-waywithintheroutecouldreducetheline'sobtrusiveness.TechniquesemployedtofurtherreducetheimpactofthetransmissionlinewouldincludefollowingtheChugachandGVEAexistingtransmissioncorridorsandinitiatingtheirstructuredesign,spacing,andconductormaterial.Othertechniquesusedtominimizedisturb-ancewouldincluderight-of-wayclearingdesignedtobeunobtrusivebybreakingupthelinearityandfeatheringthetreeheight,locatingtheright-of-wayawayfromprivateandspecialinterestland,andbymaintainingtheaccessroadsonlywhennecessaryinwinter.TheimpactofthetransmissionlineroutesfromGoldCreektoHealyandWillowwouldbeminimalbecausetheroutewouldbewithinthesamecorridorastheAlaskaPowerAuthority'sHealy-Willowintertietransmissionline.TheconstructionofthePowerAuthority'sWillow-HealyIntertiewi11becompleteuponcommencementoftheproposedSusitnatransmissionconstruction.Theimpactoftheproposedtransmissionlineswouldbereducedbecausetheywouldparallelandbeadjacenttotheapprovedintertieright-of-way.F.3.2AdditionalMitigativeMeasuresRecommendedbytheStaffAtpresent,nosinglecomprehensivelandmanagementplanexistsfortheentireupperandmiddleSusitnaRiverBasinarea.Inordertocontrolunwanteddevelopment,conflictivelanduses,andunlimitedoff-roadaccessintotheregion,theApplicantmustcontinuetocoordinatewiththevariousFederal,state,Native,andlocalgoverningagenciesandwithprivatelandholders.TheApplicantshouldassistinthedevelopmentandimplementationofappropriatelandmanagementpracticesthrough1anduseandcomprehensiveplans,specia1purposefunctiona1plans,zoningordinances,andotherpertinentlandusecontrols.AgencycoordinationthathasbegunintheplanninganddesignstageoftheSusitnaprojectshouldcontinuethroughtheconstructionandoperationphasesoftheproposeddevelopments.TheApplicantalsoshouldcontinuetomonitorthelandstatusandownershipchangeswithintheproposedprojectareaandkeepthenewland-ownersandmanagersinformedofprojectstatusandanychangesindesign,constructionmethods,accessrequired,andoperationalprocedurestobeused.Tominimizeconflictivelandusealongtheproposedpowertransmissionlinecorridor,theApplicantshouldavoid,totheextentfeasible,recreationlands,residentialareas,and anyexistingorplannedagriculturaluseareas.Ifatransmissionlinetowerislocatedonagri-culturalland,theuseofguyedX-frametowersshouldbeavoidediffeasible.Theamountoflandremovedfromcropproductioncanbeminimizedbyusingself-supporting,H-frameorsingle-poletowerswherefeasible.Whereverpossible,anytowerstructuresinanagriculturalareashouldbelocatedalongtheedgeofanagriculturalfieldtolessentheprobabilityofopera-tionaldamagetofarmequipmentand/orthetransmissionlinetowerandtominimizetheamountofcropland(existingorpotential)removedfromproduction.Wherefeasible,theproposedtrans-missionlineshouldbeplacedadjacenttoexistingtransmissionlinecorridorstominimizetheamountofnewright-of-wayrequired.MeasurestomitigateimpactstorecreationallandusearediscussedinSections2.1.12.6and5.3.6andAppendixL,whilemitigativemeasurestominimizeaestheticimpactstolandownersandusersadjacenttoprojectfacilitiesaredescribedinAppendixM.REFERENCESFORAPPENDIXFAlaskaCropandLivestockReportingService.1978.AlaskaAgriculturalStatistics.1977.PreparedincooperationwiththeU.S.DepartmentofAgriculture,Economics,Statistics,andCooperativeService;UniversityofAlaska,AgriculturalExperimentStation;AlaskaDepart-mentofNaturalResources,DivisionofAgriculture;andUniversityofAlaska,CooperativeExtensiveService.Palmer,AK.A1askaDepartmentofNaturalResources.1982.LandUseIssuesandPre1iminaryResourceInventory.Vol.1:PlanningBackgroundReport.PreparedincooperationwiththeMatanuska-SusitnaBorough,AlaskaDepartmentofFishandGame,andTransportationandPublicFacilitiesoftheKenaiPeninsulaBorough.AlaskaNorthwestPublishingCompany.1981.TheAlaskaAlmanac,1982Edition.Anchorage.BechtelCivilandMineralsInc.1983.ChakachamnaHydroelectricProjectInterimFeasibilityAssessmentReport.Vol.1,Sec.1-10,AppendicestoSec.4.0and8.0,andVol.II,AppendixtoSec.6.0.PreparedfortheAlaskaPowerAuthority,Anchorage,AK.CommonwealthAssociates,Inc.1982.EnvironmentalAssessmentReport,Anchorage-FairbanksTransmissionIntertie.PreparedfortheAlaskaPowerAuthority,Anchorage.
F-50Selkregg,L.L.1974.AlaskaRegionalProfiles-SouthcentralRegion.PreparedfortheStateofAlaskaincooperationwiththeJointFederal-StateLandUsePlanningCommissionforAlaska.Anchorage.Selkregg,L.L.1977.AlaskaRegionalProfiles-YukonRegion.PreparedfortheStateofAlaskaincooperationwiththeJointFederal-StateLandUsePlanningCommissionforAlaska.Anchorage.Tel'restrialEnvironmentalSpecialists,Inc.1982.SusitnaHydroelectricProject,EnvironmentalStudies,Subtask7.07:LandUseAnalysis,Phase1Report.PreparedforAcresAmerican,Inc.Buffalo,NY.U.S.GeneralAccountingOffice.1982.StatusofFederalAgencies'ImplementationoftheAlaskaNationalInterestLandsConservationAct.ReportCEO-82-74.
DRAFTENVIRONMENTALIMPACTSTATEMENTSUSITNAHYDROELECTRICPROJECT,FERCNO.7114APPENDIXGCLIMATE,AIRQUALITY,NOISEPreparedbyA.J.PolicastroArgonneNationalLaboratoryG-1
G-3APPENDIXG.CLIMATE,AIRQUALITY,NOISEG.1AFFECTEDENVIRONMENTG.1.1ProposedProjectG.1.1.1ClimateTheclimateofAlaskaexhibitswideseasonalandgeographicvariability.Climateisinfluencedprimarilybylatitude(Alaskaliesbetween60°and70°north),arealextent,topography(e.g.,largemountainmassestraversingthestate),andthepresenceofoceansonthreesidesofthestate.Fourmajorclimaticzoneshavebeendelineatedforthestate(Fig.G-1).TheproposedSusitnaprojectwouldbelocatedmainlywithintheContinentalZone,althoughthelowerportionofthetransmissionlinecorridorwouldextendintothesouthernTransitionZonenearAnchorage.TheContinentalZonecoverstheinteriorofAlaskaandislargerthanallotherclimaticzonescombined.ContinentalclimateinAlaskaischaracterizedbylowprecipitationandextremedailyandseasonaltemperaturevariations.Mostofthiszonereceives10to20inches(in)[25-50centimeters(cm)]ofprecipitationannually,withabout50to95in.(125-250cm)oftotalsnowaccumulation,dependingonaltitude.Therangeinrecordedmaximumandminimumtempera-turesisabout144Fo(80CO).Monthlyaveragetemperaturesarebelowfreezingforuptosevenmonthsoftheyear,andlowwintertemperaturesbelow-58°F(-50°C)areoccasionallyrecorded.Summertemperaturessometimesexceed95°F(35°C).EightmeteorologicalstationswereinstalledwithinthestudyareafortheSusitnaproject(AcresAmerican,1983:Vol.II,pp.3B-10-3-3B-10-140).ThestationswereatSusitnaGlacier,Denali,TyoneRiver,KosinaCreek,Sherman,andEklutnaLake,andneartheproposedWatanaandDevilCanyondamsites.Parametersmeasuredateachstationwereairtemperature,averagewindspeed,winddirection,peakwindgust,relativehumidity,precipitation,andsolarradiation.Snowfallamountswere.measuredonlyatWatana,andevaporationmeasurementsweremadedailyduringMay-Septemberin1981.MostrepresentativeofthestudyareaaretheWatanameasurementsreportedfromAprilE,1980throughSeptember30,1981.TheWatanastationislocatedabout1mile(mi)[1.6kilometers(km)]northoftheSusitnaRiver,aboutmidwaybetweenTsusenaandDeadmancreeks.AtWatana,windswererarelyabove22milesperhour(mph)[10meterspersecond(m/s)],withdirectionstypicallyfromthesouthwestornortheast.Otherstationsrevealthesamerangeinwindspeedbutwiththepredominantwinddirectionalteredbytopographica1features.Forexample,theupperandmiddleSusitnaRiverValleyareahasahigherelevationthanlocationslikeWillowandAnchorage,andasaresult,greaterwindspeedsaretobeexpected,inthearea,withanextremegustwindspeedanticipatedtobe120mph(54m/s)overa50-yearperiod.Therangeintemperatureswastypically-58°F(-50°C)to95°F(35°C)atallstationsinthestudyarea.DatafromnearbylocationssupportsthedatafromtheWatanasite.SincerecordshavebeenkeptatWillow,forexample,therecordlowtemperaturehasbeen-56°F(-49°C)andtherecordhightemperature90°F(32°C).FortheAnchorage-FairbanksTransmissionIntertieregion,estimatedtemperaturerangesweregreater,withalowof-93°F(-69°C)andahighof103°F(39°C)overa50-yearperiod(CommonwealthAssoc.,1982).G.1.1.2AirQualityNodataonairqualityhavebeenpresentedbytheApplicantfortheprojectarea.Somegeneralcommentscanbemade,however,usingdatafromnearbyregions.Theairqualityisgenerallyexcellentsincetherearenourbanorindustrialcomplexeswithinabout100mi(160km),andfewanywherewithinthestate.Thelargeindustrialsourcesthatdoexistareisolatedbydistanceandbyprecipitousmountainrangesintoseparateairbasins.AnimportantfeaturecharacteristicofAlaskaandtheprojectareainparticularintermsofairqualityistheso-called"extreme"meteorology.BecauseofthedramatictopographicalandmeteorologicalconditionsinAlaska,thepotentialforairpollutionisfargreaterthanintherestoftheUnitedStates.ThewinterinversionsinAlaskaareamongthestrongestanywhereintheworld.Stronginversionsoccurwhenthegroundsurfacecoolsfasterthantheoverlyingair,aconditioncommonintheArcticwinterwhenthereislittlesunlighttoheatthegroundsurface.Thelongwinternightsprolongtheseinversionperiods,andastrongpotentialforairpollution
G-4\I\I\I\II~Cl\FigureG-1.ClimaticZonesofAlaska.[Source:Selkregg,1974]A_ARCTICC-CONTINENTALT-TRANSITIQto..IM-MARITIME
G-5maylastforseveralweeks.IntheFairbanksarea,forexample,verystronginversions--temperatureissometimes50Fo(28CO)warmeratanelevationof1,500feet(ft)[460meters(m)J--combinedwithlowwindspeedsallowlittledilutionofpollutantemissions.AlthoughnodirectmeasurementsofairqualityandmeteorologyweremadeattheSusitnasite,measurementsinsimilarruralareasprovidethefollowingestimatesofthebackgroundlevels(U.S.EnvironmentalProtectionAgency,1980):oxidesofnitrogen(NO),8microgramspercubicmeters(lJg/m3);totalsuspendedparticulates(TSP),15IJg/m3;and~ulfurdioxide(S02),0.0IJg/m3.G.1.1.3NoiseNoambientnoisemeasurementshavebeenmadeattheSusitnaprojectsite,whichisinanisolated,ruralarea.Veryfewambientnoisemeasurementshavebeenmadeinanyruralareas.ThesitemostsimilartoSusitnawheresuchdatahavebeenmeasuredis"LocationQ-FarminValley"(U.S.EnvironmentalProtectionAgency,1974).Atthatlocation,anL90of27dBAwasmeasuredforthenighttimeperiodof12-2a.m.L90representsthelevelwhichisexceeded90%ofthetime;itisoftenusedasameasureofquiet.Consideringbothdaytimeandnighttimeperiods,ruralareastypicallyhavebackgroundnoiselevelsofL90=27-45dBA.LevelsbelowtheambientL90areassumedtobeinaudible,andnighttimevaluesareconsideredmostrepresentativeofthetruenoiseresidual.Atpresent,therearenoEnvironmentalProtectionAgency(EPA)standardsfornoiseexposuretothegeneralpublic.However,EPA-recommendednoiselevelstopreventhearinglossandminimizepotentialpublichealthandwelfareeffectsofnoiseareoftenusedascriteria.NoiselevelsatSusitnaareexpectedtobeextremelylowunderlowwindconditions;highwindswouldaddsomenoisefromincreasedatmosphericturbulence.G.1.2SusitnaDevelopmentAlternativesBecauseoftheshortdistancesbetweenthesitesoftheproposedSusitnaprojectandthoseoftheSusitnadevelopmentalternatives,theconclusionsreachedinSectionG.1.1alsoapplytothealternatives.Thatis,thesesitesarecharacterizedbyContinentalZoneclimate,excellentambientairquality,andverylowambientnoiselevels.G.1.3Natural-Gas-FiredGenerationScenarioG.1.3.1ClimateAlloftheplantsinthenatural-gasscenariowouldbelocatedintheTransitionZonebetweentheinlandContinentalZoneandtheMaritimeZone.ThesitesnearAnchorage,ChuitnaRiver,BelugaRiver,andKenaiareinthisTransitionZone.Attheselocations,thereisalessextremeclimatethanthatintheInterior,withtemperaturesbeingmoderatedsomewhatbythenearbyseas.TheCookInletarea,ingeneral,isinatransitionalclimatezonebetweentheContinentalZoneoftheInteriorandtheMaritimeZonemorecommontothecoastalareasfarthersouth.TheAleutianandAlaskamountainrangestothenortheastareeffectiveinpreventingthelarge,extremelycoldairmassesthattypicallysettleintheinteriorbasinfromcausingcomparablyfrigidconditionsalongtheinletduringwinters.TheKenaiandChugachranges,whichextendinanortheasterndirectiontothesouthofthisarea,protecttheInletfrommoistairfromtheGulfofAlaskaandfrompotentiallyheavyprecipitation.Thehigherelevationsexperiencecoldertemperatures,moreprecipitation,andstrongerwindsthanthelow-lyingcoastalareas.Thefourseasonsarenotwelldefinedintheregion.Wintergenerallybeginsmid-Octoberandlastsuntilmid-Apri"'.Heavyfogoccursmainlyduringthisseason.Monthlyaveragetemperaturesvarybetween10°Fand30°F(-12°Cand-1°C)duringwinter.However,temperaturesfallwellbelowfreezing,withsomeinlandlocationsreaching-50°F(-46°C).Springtimeoccursfrommid-ApriltoJune,whentheaveragedailytemperaturesrisefrom30°F(1°C)inApriltonear50°F(IOOC)inJune.Precipitationislowestinthespring,withmonthlyaveragesabout1in(2.5cm).Therelativehumidityismoderate,butincreasestohighduringthesummer.Precipi-tationalsoincreasesrapidlyduringthesummer:about40%ofthetotalannualprecipitationfallsbetweenmid-Julyandtheendofsummer.Julyisalsothewarmestmonthoftheyear,withtheaveragedailytemperaturenear55°F(13°C).Autumnisbrief,accompaniedbyadecreaseinprecipitation.Mostprecipitationoccursasrainearlyintheseasonandsnowlater,althoughsnowmaypredominatethroughouttheseasonatthehigherelevations.Temperaturesalsofallrapidlyduringthisshortseason;monthlyaveragetemperaturesforSeptemberandOctoberdifferby15Fo(8CO).TheTransitionZonehasalessextremeclimatethanthatoftheInterior,withtemperaturesbeingmoderatedbythenearbyseas.PrecipitationisgenerallywithinthesamerangeastheInterior,butcanreachabout60in(150cm)inthesouthernpartoftheareaadjacenttotheMaritimeZone.NoneofthealternativesitesislocatedintheMaritimeorArcticzones.
G-6FigureG-2showsthelocationsofweatherstationsassociatedwiththeNationalOceanographicandAtmosphericAdministrationintheCookInletarea.Stationsrepresentedbydoublecirclesmonitorwindspeedanddirection,skycover,andcloudceilingheightsinadditiontomeasuringtemperaturesandprecipitation.WindprofilesfortheKenaiandAnchoragestationsindicatethatageneralwindpatternexistsfortheentireinletregion.However,localvariationsinwindprofilesandturbulentdiffusionareexpected.Thisisbecausetheterrainroughnessincreasesmechanicalturbulence,allowingfortheatmospheretobewell-mixedduringperiodsofhighwinds.Duringthewinter,windsfromthenorth-northeastaredominant;assummerapproaches,theprevailingwindsarefromthesouth-southwest.TheannualaveragewindspeedatbothKenaiandAnchorageisapproximately7mph(3m/s).Monthlyaveragewindspeedsrangefrom4to9mph(2to4m/s)atAnchorage.FigureG-3illustrateswindrosesforKenai,Anchorage,andthePhillipsPetroleum'sPlatform"A"locatedapproximately5mi(8km)eastofTyonek.ObservationsfromtheweatherstationsatKenaiandAnchoragehavebeenanalyzed(DOWLEngineers,1981)todescribetheturbulentstructureoftheatmosphere.ForKenai,theannualfrequenciesofoccurrenceofthevariousstabilityclassesareClassA -0%,ClassB -1%,ClassC -10%,ClassD -62%,ClassE -9%,ClassF -18%.Thisdistributionreflectstherathercommonoccur-renceofcloudyskies(ClassD).Italsosuggeststhatthedispersionofcontaminantsreleasedintotheatmospherewillbecontrolledmostoftheyearbywindspeedandroughnessofthegroundsurface.WeatherdatafromthemonitoringstationatKenaiindicatecoldwintersandcoolsummerswithmoderatewinds.Mostofthelightannualprecipitationtotalisrecordedinthesummerandfall,althoughsubstantialsnowfalloccursinthewinter.Skiesarefrequentlycloudyandtherelativehumidityrangesfrommoderateinthespringtohighinthesummer.Thunderstormsarerareandheavyfogoccursmainlyinthewinter.Thelong-term(1941-1970)temperatureaverageatAnchorage,locatedabout70mi(113km)northeastofKenai,is35°F(2°C).Thisiscomparabletotheaveragetemperatureof33.8°F(1°C)forthemonitoringyearattheTesororefinerymonitoringsitelocatednearKenai.TheaveragedailytemperatureattheTesoromonitorrangedfrom9.3°F(-12.6°C)inJanuaryto53.1°F(11.7°C)inJuly.G.l.3.2AirQuality,NoiseNationalandAlaskaAmbientAirQualityStandardssetmaximumlevelsofseveralpollutants:ozone(03),carbonmonoxide(CO),sulfurdioxide(S02),totalsuspendedparticulates(TSP),hydrocarbons(HC),nitrogendioxide(N02),andlead(Pb).TheCookInletAirQualityControlRegionisdesignatedaClassIIattainmentareaforallcriteriapollutants.TheTuxedniNationaIWiIdlifeRefuge,about100mi(160km)southwestoftheTyonekarea,istheclosestClassIarea.AnchorageisoneoftwoareasofAlaska(alongwithFairbanks)thatisnon-attainmentintermsofambientairqualitystandardsforcarbonmonoxide.TheactualairqualityonthewesternshoreofCookInletnearTyonekisnotdocumented.Severalsourcesofemissionsofparticulatematter,sulfuroxides,carbonmonoxide,nitrogenoxides,andhydrocarbonsarescatteredthroughouttheonshorearea,withanumberofoffshoreoilandgasplatformsconcentratedintheNikishka/Kenaiarea.Nitrogendioxideemissionsaregreatest,withcombustionproductsrepresentingthemajorityofemissionsfrombothoffshoreandonshoresources.Theimpactofthesesourcesonambientairqua1itytendstobevery1oca1ized,withthehighestconcentrationsofpollutantsoccurringwheresourcecongestionisgreatest.ThemostcongestedareasincludeTradingBayandSalamatof,andevenintheseareasseparationbetweenindividualsourcesisgood.Forthesereasons,airqualitywithintheareaisexpectedtobewellwithintheNationalandAlaskaAmbientAirQualityStandards.DetailsconcerningthesestandardsarepresentedbelowinSectionG.2.3.VisibilityisoccasionallyaproblemthroughouttheCookInletarea.AtAnchorage,thevisibilityisone-halfmileorless«1km)5%ofthetimeduringDecemberandJanuary,primarilybecauseoffog.Inaddition,snowsfrequentlydecreasevisibilitytolessthan3mi(5km).TheAlaskaDepartmentofEnvironmentalConservation,atitsdiscretion,mayrequireanypersonproposingtobuildoroperateanindustrialprocess,fuel-burningequipment,oranincineratorinareasofpotentialicefogtoobtainapermittooperateandtoreducewateremissions(AlaskaDept.ofEnvironmentConservation,1983).Air-qualitydatadoexistfortheKenaiPeninsula.AsketchofthisregionandthelandusesthereisshowninFigureG-4.Amonitoringstationwassetupabout9mi(14km)north-northwestofKenaiand0.9mi(1.3km)southoftheTesororefinerytoprovideambientdataforapotentialexpansionoftherefinery.MonitoringwasconductedfromJune1,1981,toMay31,1982.TheairqualitydatacollectedtherearesummarizedinTableG-l.TheNationalAmbientAirQualityStandards(sameasAlaskaAmbientAirQualityStandardsforthepollutantslisted)arealsoshown.ThetablerevealsthattheambientpollutantlevelsintheKenaiareaarewellwithinthosestandards.
....25Dl'IIl'T"IVERn""'IALG-71Ioo'!~~_""'ljRANITE33POINT~E32.-AlUlA.JIlAillTE4D5POlleTFigureG-2.LocationsofWeatherMonitoringStationsinCookInletArea.[Source:DOWLEngineers,1981J
G-8SSESSSNOCCURRENCE,N%INNW251.NNEFREQUENCYOFW-+---+--+-+--+-wiiCALM-PHIL1.IPS<1·1.ANCHORAGE13"1.KENAI10-1.L.OCATIONSYMBOL.NUMBEROFOBSERVATIONDATAPERIODDAYSPHlWPSANNUAL74-."2PL.ATFORMANCHORAGE----ANNUAL.SI-6024KENAI=ANNUAL.64-708NOTE'KENAIROSEHASCAL.MSDlSTRI8UTIONB£TWEENTHEI -3a4'6KNOTGROUPINGS.FigureG-3.WindRoseforAnchorage,Tyonek,andKenaiAreas.[Source:DOWLEngineers,1981J
G-9KENAIMOOSERANGESPURr-----------IIIIIIIIIIIIIIII:NATIONALIIIIIIIIIIIIIIIII'----------..,IIL.KENAI64~aniels-~".I)Dogbone(7"LakeIsland0ke~NORTH32MILES-~oo()oFigureG-4.LandUseintheKenaiArea.(Source:RadianCorp.,1983J
G-10TableG-l.SummaryofAirQualityMaximaatKenaiPeninsulaMonitoringSitefortheTesoroRefineryHighestValueSecondHighestValueFederalStandardPollutant(fJg/m3)(fJg/m3)(fJg/m3)NO(l-hr)580.0(2/19)tl436.0(2/19)NonexNO(l-hr)197.0(2/8)152.0(10/24)NoneN02(1-hr)560.0(2/19)406.0(2/19)NoneN02(arithmeticmean)6.3t2100t2S02(3-hr)69.6(5/29)35.0(4/9)1,300t3S02(24-hr)8.6(5/28)7.0(8/4)365S02(arithmeticmean)0.3t280t2CO(l-hr)2,560.0(5/18)2,190.0(liB)40,000CO(8-hr)1,660.0(liB)1,411.°(12/7)10,00003(l-hr)96.0(5/15)94.0(5/1)235TSP(24-hr)60.0(lOll)50.0(6/27)150t3TSP(geometricmean)9.0t275t2t1Numberinparenthesesisthedateofoccurrence.t2Annual.t3Secondary.Source:RadianCorp.(1983).ThenorthernKenaiPeninsulaisthesiteofseveralindustrialplants,includingtwooilrefineries,aliquifiednaturalgas(LNG)plant,amajorammonia-ureacomplex,petroleumstoragefacilities,andaproposedsecondLNGfacility.RecentTSPdatafromtheareahaveshownsomeexcursionsbeyondthe24-hraveragestandard,butthesearethoughttobeduetonaturaldustratherthanplantemissions.TheoccurrenceswererecordedsimultaneouslyatboththesamplingsiteinthecityofKenaiandtheindustrialsite10mi(16km)northoftownondry,windydays.Ofspecialsignificanceisthe20-40fJg/m3increaseinTSPconcentrationsintheindus-trializedareasincelandwasclearedforconstructionofthenewLNGfacilityandamajorconstructionprojectcommencedattheammonia-ureaplant.Anchoragehasair-qualitymonitorsinsidethecitylimitsandoneinanoutsideruralareatomeasureS02,NO, 03,CO,andTSP.MeasurementsofS02inAnchoragehaverarelyexceeded25fJg/m3,theml~imumdetection1imitforthepollutant.ConcentrationsofN02inAnchoragealsohavebeenfoundtoberelativelylow.AsummaryofNOandozonemeasurementsinAnchorageisgiveninTableG-2.Asmentionedabove,AnchorageisdgsignatednonattainmentwithrespecttoCOfromautomobileemissions.ItisstrictlynonattainmentfromTSPbutisdesignatedattain-mentsincetheTSPviolationisduelargelytonaturalsourcesofparticulates.NolargestationarysourceofTSPexistsinAnchorage.AsamplingofTSPmeasurementsatAnchorageandKenaiarepresentedinFigureG-5.AirqualitydatatakeninAnchoragewouldnotnecessarilyberepresentativeofairqualityatthepossiblealternativeprojectareas,becauseofthelargenumberofindustrial,residential,andautomobilesourcesofpollutionthatexist.Thesedatashould,however,provideanupperbound.AsdescribedinSectionG.l.l,ambientnoiselevelsareexpectedtobeverylowinruralareassuchasthosedesignatedforthealternativegas-firedplants.G.l.4Coal-FiredGenerationScenarioG.l.4.1ClimateThecoalgenerationscenarioinvolvesconstructionandoperationofpowerplantsatWillowandNenana.TheselocationsareintheContinentalZoneandshouldhaveclimaticfeaturessimilartothoseintheproposedSusitnaprojectarea.Dataavailablesince1963atWillowrevealarecordhightemperatureof90°F(32°C)andrecordlowtemperatureof-56°F(-49°C).
G-nTableG-2.SummaryofNOzMeasurementsinAnchorageNOzConcentrationMeasurement(~g/m3)Annualaveraget116Maximum24-hraveragetZSecondHigh24-hraverage8151t1TheAlaskastandardis100~g/m3,annualaverage.tZThereisno24-houraveragestandardforNOz.Source:AlaskaDepartmentofEnvironmentalConser-vation(1977).ALASKATSPMEASUREMENTSSeasonalMeansinp,g/m3cr::<!lcr::cr::<!lcr::cr::<!lcr::cr::<!lcr::cr::<!lcr::wzwwZww:;::wwzwwzW-Jf-~::;:-Jf-~::;:-Jf-~::;:-Jf-::2::;:-Jf-~::;:--JZcr::::;:-Jzo::::::;:-JZcr::::;:-Jz::;:-Jzcr::::;:et:~0..::>et:~o..::>et:3:0..=>et:~0..=>et:~0..=>L.l..;3:VlVlL.l..::t:U1.V')L.l..VlVlL.l..;3:VlVlL.l..;3:VlVl200100AlaskaAnnua1StandardFigureG-5.SeasonalTSPMeasurementatAnchorageandKenai.[Source:AlaskaDept.ofEnvironmentalConservation,1977J
G-12G.l.4.2AirQualityThenearestairqualitymonitoringstationstoWillowareatPalmerandEagleRiver.Thesestations,whichmeasureonlyTSP,showthatthe24-hrTSPstandardhasfrequentlybeenexceededbecauseoffugitiveemissions.RecentdatacollectedatPalmer,however,indicatemuchlowerTSPconcentrations(belowthestandard).Thisimprovementisprobablyduetorecentpavingofanearbyroad.ItshouldbenotedthatTSPsamplesareusuallytakennearanthropogenicsourcesofparticulatestodeterminetheeffectsofman-madeactivities.Veryfewaretakeninisolatedruralareas(suchasatthealternativeplantsites).DatafromtheHealyareameasurementstationsatNorthNenanaandGarnerindicateexcellentairquality.DataavailableareforJanuary1979throughAugust1979(S02inI-hr,3-hr,and24-hraverages,andmeteorologicalvariablesoftemperature,windspeed,winddirection,andpressure)andMarch1978throughJuly1979(TSPin24-hraverages).TheS02datarevealednoexceedenceofstandards;theTSPdataindicatedincreasesfromverylow1eve1sonlywhenthewindwasblowingfromtheriverbank.Atbothsites,ambientlevelsofallpollutantswereextremelylow,exceptoccasionallyforTSP.G.1.4.3NoiseAmbientnoiselevelsareexpectedtobeverylowintheruralenvironmentinwhichthecoal-firedplantswouldbelocated.NoiselevelsshouldbesimilartolevelsdescribedinSec-tionG.l.l.3fortheproposedSusitnaprojectarea.G.1.5CombinedHydro-ThermalGenerationScenarioThecoal-fired,combined-cycle,andcombustion-turbineplantswouldbelocatedprimarilynearAnchorageandNenana.TheexistingenvironmentsoftheseareasweredescribedinSectionsG.1.1throughG.l.4.ThealternativehydropowerunitsatJohnson,Browne,Keetna,andSnowshouldhaveclimate,airquality,andnoisefeaturessimilartothoseintheSusitnaprojectarea.TheChakachamnasiteisclosetoTyonek;thatareawasdiscussedinSectionG.l.3.G.2ENVIRONMENTALIMPACTSG.2.1ProposedProjectG.2.1.1ClimateTheWatanaandDevilCanyondamsandreservoirswouldcausenosignificantchangesinthemicro-climate.Thesurfaceareaofeachofthereservoirswouldbetoosmalltoproducemeasurabledifferencesinthebasicmeteorologicalvariablesbeyond50ft(15m)fromthereservoir.Thewatersurfaceshouldbefrozeninthewinter,furtherlesseningthechangesbetweenlandandwaterconditions.G.2.1.2AirQualityG.2.1.2.1WatanaDamSiteDuringtheperiodofconstruction,foursourcesofairqualityimpactswouldoccurattheWatanadamsite:fugitivedust,dieselgeneratorexhausts,incineratorsattheconstructioncamps,andicefog.Eachoftheseisdiscussedbelow.ItshouldbenotedthatduringoperationoftheWatanadam,therewouldnolongerbefugitiveemissionsfromconstructionactivities.Therealsowouldnolongerbeanytemporarydieselgenerators.Thepermanentworkersvillagewould,however,containsmallincineratorswhichwouldberegulatedbythestatefortheemissionofparticulatesandtheopacityofthestackplume.FUGITIVEDUSTFugitivedustisanyparticulatematternotemittedthroughanormalexhaustvent.AttheSusitnaprojectsites,thelargestsourceswouldberoaddustraisedbytrucktrafficandwind-blowndustfromstoragepiles.Themajorsites,sources,andquantitiesoffugitivedustreleases,andtheperiodofoperationofequipmentinthoseareas,arelistedinTableG-3.ThequantitiesoffugitivedustreleaseswerecomputedusingEPA-recommendedmethodos(Bowlesetal.,1979).FigureG-6showsthelocationofthesources.MostwouldbewithintheWatanasiteboundary;however,fugitiveemissionsmightbetransportedbeyondthesiteboundarybythewind.Fugitivedustwouldalsobeproducedfromtrucksandcarspassingoverunpavedaccessroadstothesite.Becauseoftheintermittentandtemporarynatureoftrafficontheseroads,however,theoverallimpactisexpectedtobeinsignificant.
Table G-3.Projected Major Sources of Fugitive Oust Emissions and Estimated
Release Rates for Susitna Construction Activities
Site
Dams,quarry A
Quarry A,borrow
sites D&E,dam
Borrow site E,
batch plant
Borrow sites
D&E,quarry A.dam
Source/Activity
Drilling
Blasting
Truck loading
Truck hauling
Truck unloading
Storage piles (wind-
blown removal)
River gravel
Aggregate storage
Overburden removal
Concrete batch
plant operation
Emissionst 1 Days of
Activity Months of
lb/dayt2 tons/yr Per Year Operation Control Technique
312 19 121 April-July Water spray
33 2 121 April-July Water spray
1,443 87 121 April-July Water sprinkle
1,973 482 121 April-July
78 5 121 April-July
8,064 399 182 April-September
40 2 182 April-September
450 30 135 April-Mid August
Gl
200 18 182 April-September Bag house I
I-'
W
t 1 Values are rounded to nearest whole number.
t 2 Computed using EPA-recommended methodologies (Bowles et al.,1979).
Conversion:To convert pounds to kilograms,multiply by 0.454.
To convert tons to metric tons,multiply by 0.907.
Source:Acres American (1983).
TsusenaCreekG-14DeadmanCreekBorrowSiteE~~~~~~~~'~"E-~:==:~WatanaIDamQuarrySiteAFogCreeko246MilesFigureG-6.LocationofMajorSourcesofFugitiveDustReleaseduringConstructionofWatanaDam.[Source:BasedonAcresAmerican,1983JSourcesoffugitivedustaccountforsomeofthesmallparticlesandamajorportionofthelargerparticlesinaTSPsample.TSPmeasurementsthroughoutAlaskaoftenexceedthe24-hrparticulatematterstandardof150~g/m3.ThisnumberisthesecondaryFederalstandardonTSP,adoptedbyAlaskaasitsstatestandard.Exceedencesofthisstandardusuallyarearesultofdispersionoflarge-diameterdustparticlesduringdryweather(AlaskaDept.ofEnvironmentalConservation,1977);rainfallorsnowonthegroundreducesgenerationoffugitivedust.Asmentionedabove,particulatesamplersareusuallyplacednearareasofman-madeactivity;andreportedexceedencesofTSPstandardsareusuallytraceabletosuchactivities.InruralareasinAlaska,TSPlevelsaregenerallyonlyabout15~g/m3.Underaworst-casescenariodevelopedtocalculatetheconcentrationoffugitivedustastoragepile3mi(4.8km)long(easttowest)by220ft(67m)widewashypothesized(AcresAmerican,1983).Vehiculartrafficwasassumedtotravelparalleltothestoragepileonaroadway2mi(3.2km)longby50ft(15m)wide.UsingmeteorologicaldatafromtheWatanaclimatestation,aworstdaywaschosentomaximizethe24-hrTSPconcentration.CalculationswiththeEPA-approvedmodelISCST(Bowlesetal.,1979)indicatedaTSPconcentrationof627~g/m3atapoint1,300ft(400m)fromthestoragepile.ThisvalueexceedstheAlaskaTSPstandardsof150~g/m3.Althoughthispointwouldprobablybeinsidetheplantboundary,itraisesthepossibilitythattheregulationsmightalsobeexceededoutsidethesiteboundary.Ifso,thenmitigativemeasuresshou1dbetaken,suchaswateringroadsondaysafterdryperiods,usingstabilizingagentsonstoragepilestomaintainasurfacecrustandtoholddownfugitiveemissions,andrestrictingvehiclespeedsanddenyingaccesstounauthorizedvehiclesonunpavedroads.ItisnotclearwhethertheSusitnaprojectwouldbesubjecttoPSDreviewonTSPsince(a)itisnotdefinitethattherewouldbeareleaseofanypollutantwithemissionsabovethetrigger
G-15levelof250tons(225MT)peryear,and(b)ithasnotyetbeendeterminedbytheAlaskaDepart-mentofEnvironmentalConservationwhethertheanticipatedreleaseswouldbeclassifiedastemporary,thusexemptingtheproject.Fugitiveemissionsarenotconsideredincomputingwhetherparticulateemissionsareabove250tons(225MT)peryear.However,ifthatlimitwereexceededbyprocessparticulateemissions,thenfugitiveemissionswouldbeincludedinplanstoreduceTSPbelowtheregulatedconcentrationincrementof37pg/m3.DIESELGENERATOREXHAUSTTwelvetemporarydieselgeneratorswouldbeinstalledattheWatanasitetoprovide10.3megawatts(MW)ofpowerforthefirstthreeyearsofconstruction.Thesegeneratorswouldburn723gallons(gal)[2,740liters(L)]perhourofNo.2dieselfuelandwouldbeusedcontinuouslythroughouttheyear.Thisisalow-sulfuroilandmeetsstateregulationsonthemaximumsulfurcontentafuelcanhave.EstimatesoftheemissionsfromthesegeneratorshavebeencomputedbasedonEPAemissionfactorsandengineeringcalculations(U.S.EnvironmentalProtectionAgency,1982).ThemajorpollutantsandtheestimatedemissionratesarelistedinTableG-4.TheEPA-approvedPTPLUmodel(U.S.EnvironmentalProtectionAgency,1983)wasalsoused,togetherwithdatarecordedattheWatanaweatherstationonJuly18,1981,toestimatethemaximum1-hrconcentrationofeachpollutant.TheresultsareshowninTableG-4.ThepredictedvaluesarequitesmallcomparedwithPSDincrementvalues:forparticulates,a24-hraverageof37pg/m3(nomorethanonceayear);andforsulfurdioxide,a24-hraverageof91pg/m3anda3-hraverageof512pg/m3,eachexceedednomorethanonceperyear.TableG-4.EstimatedEmissionRatesandGround-LevelPollutantConcentrationsfrom12TemporaryDieselGeneratorsDuringPlantConstructionEmissionsMaximum1-hrConcentrationPollutant(lb/hr)(tons/yr)(pg/m3)Particulates1.46.31.6Sulfurdioxide11.650.712.9Carbonmonoxide3.615.84.0Hydrocarbons0.73.20.8Nitrogenoxides15.969.717.7Conversions:Toconvertpoundstokilograms,multiplyby0.454;toconverttonstometrictons,multiplyby0.907.Source:AcresAmerican(1983).Thecalculationsweremadewithonlyoneday'smeteorologicaldata;however,thatdaywaschosenbecauseofitshighpersistenceinwinddirection,whichwouldtendtomaximizetheimpactfora24-hraveragingperiod.Thecomparisonconfirmsthatairqualityimpactsfromthediese1generatorsshouldbeminimalintermsofstateorEPAairqualitystandards.INCINERATORSIncineratorswouldbeusedtoburngarbageatthetemporarycampsforworkers.Alaskahasparticulateandopacityregulations(AlaskaDept.ofEnvironmentalConservation,1983)onsuchsmallincinerators.Theparticulateemissionsmaynotexceed0.15grainspercubicfoot.Opacityisameasureofthedensityofthestackplumeonapercentagebasisfrom0to100.Forsuchincinerators,visibleemissions(excludingcondensedwatervapor)maynotreducevisibilitythroughtheexhausteffluentbymorethan20%foratotalofmorethanthreeminutesinanyonehour.Pollutantemissionsfromincineratorsdependtoagreatdegreeonhowtheincineratorsareoperated.Itisimportanttocontrolcombustionconditionstominimizecarryoverofunburnedmaterialortopreventblowingtoomuchairthroughtheincinerator,leadingtotheemissionoftoomanyparticulates.Stateregulationsshouldensureefficientoperationofthetemporaryincinerators.
G-16ICEFOGSIcefogsareapotentialproblemininlandAlaska,especiallyatFairbanks.Whentheaircoolstoextremelylowtemperatures[-30°Fto-40°F(-34°Cto-40°C)],thewatervaporintheaircondenses,formingicecrystalsaroundparticulatematterintheair.Whenthetemperatureislowenough,watervaporfromthecombustionoffuelbyautomobilesandtruckswillfreeze,enhancinganyicefogcondition.Additionally,thetemporarydieselgeneratorswouldproduceseveraltonsofwatervaporperhour.Theexhaustsofthegeneratorswouldbe20ft(601)offtheground,andthebuoyantnatureoftheplumewouldtendtokeepitandtheicefogaloftunderlowwindconditions.TheincreaseinparticulatematterintheairduringSusitnacon-structionactivitiesshouldenhanceicefogformation.However,inverycoldconditions,evenifnaturalicefogconditionsdidnotoccur,avisibleplumewouldpersistwithicecrystalspresent.Verylittlecanbedonetoavoidtheicefogproblem.Placingcondensersontheexhaustsofthedieselgeneratorsisonepossiblemitigativemeasure.Locatingthegeneratorssoastoavoidpotentialicefogimpactsonroadsshouldbesufficient,however,sincetheareawouldbelargelyisolatedexceptforplantworkers.TheAlaskaAirQualityRegulationsprovidethattheAlaskaDepartmentofEnvironmentalConser-vation"will,initsdiscretion,requireanypersonproposingtobuildoroperateanindustrialprocess,fuelburningequipment,orincinerator,inareasofpotentialicefogtoobtainapermittooperateandtoreducewateremissions"(AlaskaDept.ofEnvironmentalConservation,1983).C.2.1.2.2DevilCanyonDamSiteLiketheWatanasite,DevilCanyonwouldhavedieselgeneratorsandincineratorsatthetemporaryworkerscampandwouldexperienceicefogsduringtheconstructionphase.However,thefugitivedustproblemwouldbesignificantonlyatWatanasinceconstructionatDevilCanyonwouldtakeplacewithintheriverbed,andthusverylittlefugitivedustwouldbereleased.Thepollutantemissionsreleasedbythedieselgeneratorswouldbeverylow(lowground-levelconcentrationsarepredicted);nopermitwouldberequiredtooperatethesegenerators.ThecampincineratorswouldbesubjecttoAlaskastateregulationstoensureefficientoperationintermsofparticulateemissionandopacityofthestackdischarge.Icefogscouldaffectvisi-bilityifthegeneratorswerepositionednearroads.However,thesmallriseachievedbytheexhaustplumeshouldbesufficienttoavoidsignificantvisibilityreduction,exceptperhapsunderthemoststable,calmconditions.DuringoperationoftheDevilCanyondamsite,thepotentialforsuchimpactswouldbeeliminated.NodieselgeneratorsorincineratorswouldbeusedsinceaworkersvillagewouldbeattheWatanasiteonly.G.2.1.3NoiseDuringconstruction,theprincipalsourcesofnoisewouldbeblasting,drilling,bulldozeroperations,andtruckloading,unloading,andhaulingoperations.Thenoisefromblastingcanbeannoying,butshouldbelimitedtoshortperiods.Inahycase,theclosesttownsaresuf-ficientlydistantandtheconstructionperiodtemporary,sothatannoyancetoarearesidentswouldbeminimal.Theoperationofthegeneratingfacilitieswouldinvolvetheuseoftransformersthatemittonesinthe120,240,360,and480Hzoctavebands.Becauseofthelowambientsoundlevelexpectedatthesite,audibletonesfromthetransformersmightbeheardatdistancesof3,000ft(900km)orso,iftheterrainwereflat.However,thepowerhousewouldbelocatedatthebottomoftherivervalley,andthenearesttownisonthetopoftheridgeabovetheproposedpowerhousesite.Thetonalnoisewouldbedirectedupwardsbyreflectiononthesidewallsofthevalleyandwouldnotimpactthevillage.Nonoiseimpactsoftheplantoperationareexpectedtobeexperiencedbythenearestresidents.Transmissionlinescauseionizationofthesurroundingairlayerswhenthefieldintensityexceedsthebreakdownstrengthoftheair.TheresultingcoronaformationgivesrisetoaudiblenoiseandgeneratesozoneandNO(AppendixD).Forboththe138-kVandthe345-kVtransmissionlines,theincrementof03andNOtoambientlevelsduringlineoperationprobablywouldnotbemeasurable.AlthoughnoaUdiblexnoiseshouldresultfromoperationofthe138-kVline,therewouldbeaudiblenoisefromthe345-kVline.Thisnoisewouldbemorepervasiveinextentandintensityduringperiodsofrainyweather.NoisefromtransmissionlinesisofbothbroadbandandtonaIcharacter,Thebroadbandnoiseischaracterizedbyacracklingsoundoccurringfromhighfrequencycomponents.Superimposedonthisspectrumisa120-Hztonethatsoundslikethehumofatransformer.Thehigh-frequencybroadbandcomponentshaverapidattenuationbecauseof
G-17airabsorption,however.Audiblenoiseimpactsdependgreatlyonambientmeteorologicalcondi-tionsandambientnoiselevels.ConservativecalculationsbasedondatafromtheBonnevillePowerAdministration(1983)andChartierandStearns(1981)revealthatinfairweather,audiblenoiseofbroadbandandtonalcharactershouldextendonlyabout50ft(15m)fromthetrans-missionlines.Underworst-caseconditions(duringrain),however,annoyingtonalandbroadbandnoisecouldextendapproximately500ft(150m)fromthelines.Atabout1,000ft(300m),thetonesshouldbecomeinaudible,butthebroadbandcracklingnoiseshouldstillbeaudibleandremainannoying.Atapproximately2,000ft(600m),nonoiseofeithertypeshouldbeaudible.G.2.2SusitnaDevelopmentAlternativesTheimpactsonclimate,airquality,andnoisefromtheSusitnadevelopmentalternativesareverysimilartothosedescribedinSectionG.2.1fortheproposedproject.TheModifiedHighDevilCanyonalternativewouldinvolvedamconstructionatanearbylocation.TheReregulatingdamalternativewouldinvolveconstructionofareregulationdamdownstreamoftheWatanaIdam.Foralldamconfigurationsandalternatives,fugitivedustemissionsmightextendbeyondsiteboundaries,asindicatedfromthecalculationsdiscussedabovefortheproposedWatanadam.G.2.3Natural-Gas-FiredGenerationScenarioClimaticimpactsoftheeight200-MWecombined-cyclegasunitsandthetwo70-MWecombustion-turbineunitswouldbenegligible.Impactswouldinvolvechangesinsurfacealbedosandheatcapacitiesoversmallareasasaresultoflandclearing,paving,anderectionofbuildings.Alsoinvolvedwouldbeveryslighttemperatureandhumidityincreasesinthelocalareaoftheplants.Thevisibleplumefromthewet/drycoolingtowersthatwouldbeusedwhentheplantswereinoperationwouldextend0-300ft(0-100m)downwind,dependinguponairtemperatureandrelativehumidity.(Vaporplumelengthsincreaseastheambienttemperatureandtheambientsaturationdeficitdecrease.)Ground-levelfoggingandicingwouldbeveryunlikelyfromsuchwet-drytowers.Specificdataonthedesigncharacteristicsofthetowersandonlocalmeteorol-ogicalconditionswouldberequiredinordertomakequantitativepredictionsofcoolingtowerimpacts.Pollutantemissionsfromatypical200-MWecombined-cyclegasunitaregiveninTableG-5.Alsolistedarethestackdimensionsandexitandemissioncharacteristicsofthetwoplumesfromsuchaplant.Notethattheexitplumesareveryhot,indicatingahigh-risingbuoyantrelease.OnlytheNOemissionslevelsfromthesecombined-cyclegasunitswouldbesignificantinabsoluteterms.ThexNOreleaserateforeach200-MWeplantwouldvaryfrom138g/s(nosteaminjection)to34g/s(ste~minjection).WithoutsteaminjectiontoreduceNOemissions,thethreeunits(600MWe)locatedneartheChuitnaRiverwouldemit414g/sofNOx.TheChuitnaplantmighthavethreeidentical200-MWeunits,twostacksperunit.Thepote~tialairqualityimpactofthisplantisevaluatedinsomedetailheresinceitwouldhavethelargestemissionratesofallthecombined-cycleplantsthatwouldbeoperatedunderthenatural-gasgenerationscenario.Theemissionratescitedherewerecalculatedonthebasisofnosteaminjection;thisassumptionwasmadeinordertoprovideconservativepredictions.Ground-levelconcentrationsshouldbeincompliancewithAlaskaambientairqualitystandardsandPSDregulationspromulgatedbytheU.S.EnvironmentalProtectionAgency.TheseregulationsaresummarizedinTablesG-6andG-7.Eachcombined-cyclegasunitwouldbelocatedinaPSDClassIIarea,withthenearestClassIareadistantfromthesite.ToensurethatAlaskaairqualitystandardsandlocalPSDClassIIrequirementsweremetforNO,theEPAscreeningmodelPTPLUwasusedtocalculatemaximumpredictedground-levelconcen-tr3tionsforNO.PTPLUisapoint-sourceGaussianmodelthatisusedtopredictmaximum1-hrconcentrationso~anypollutantbasedonstackcharacteristicsandpollutantemissionrate.Themodelincludes7stabilityclasses(A-F)and14wind-speedranges.Amaximumground-levelconcentrationiscalculatedforeachoftheapproximately100combinationsofstabilityclassandwindspeed.Thismodelwasappliedtothethree200-MWcombined-cycleunitsatChuitnaasrepresentingtheworst-casesituation.Themaximum1-hrconcentrationoccurredforStabilityClassCandawindspeedof38.5mph(17.2m/s).Themaximumconcentrationof23IJg/m3occurred3mi(4.7km)downwind.Anestimateforthemaximum24-hraverageconcentrationwas9.2IJg/m3.Alaskaairqua1ityregulationsrequirethattheconcentrationbeIessthan100IJg/m3onanannualaveragebasisatanygroundlocation.Clearly,sincethemaximum24-hraveragewaslessthantheannualaveragelimit,theannualstandardwouldbemet.Itshouldbenotedthatnosite-specificmeteorologicaldataarerequiredintheuseofPTPLU.Ifthisscreeningmodelledtoapotentialviolationofstandards,site-specificdatawouldberequired,alongwithamoredetailedmodel--perhapsISCorVALLEY(Burt,1977)--inordertoprovidemoreaccuratepredictions.OncePTPLUscreeningmodelpredictionsindicatecompliancewithstandards,nofurtheranalysisisrequired.
G-18TableG-5.Characteristicsof200-MWeCombined-CycleGasPlantUsedinAirQualityModelingParameterValueStackCharacteristicsNumberofstacksDimensionsofeachstack(ft)Heightofeachstack(ft)Stackexittemperature(OF)Stackgasvelocity(ft/s)Emissions(perstack)211x176535070Dependsonsulfurinfuel(verylowvalues,however)NOx(lb/hr)S02CO(lb/hr)ParticulatesNoSteamInjection54521oWithSteamInjectionof52,530lb/hr13621°Conversion:Toconvertfeettometers,multiplyby0.305;toconvertpoundstokilograms,multiplyby0.454.Source:Stepien(1984).TableG-6.AlaskaAmbientAirQualityStandardst1ControllingNAAQS,(J-lg/m3)ContaminantandTimePeriodPrimarySecondaryTotalsuspendedparticulatesAnnual606024-hrt2150150SulfurdioxideAnnual8024-hrt23653-hrt21,300Carbonmonoxide8-hrt210,00010,000I-hrt240,00040,000NitrogendioxideAnnual100100OzoneI-hrt2235235LeadQuarterly1.51.5tlAlaskastandardsareidenticaltoNationalAmbientAirQualityStandards(NAAQS)exceptthatforAlaska(a)theprimaryandsecondarystandardsforTSParereplacedbyasinglestandard,themorestringentsecondarystandard;and(b)thereducedsulfurstandardismademorestringent(however,reducedsulfurisnotofconcernhere).AlaskastandardsarefromtheAirQualityControlRegulations18AAC50,AlaskaDepartmentofEnvironmentalConservation.NAAQSstandardsarefromtheCodeofFederalRegulations,40CFRPart50.t2Nottobeexceededmorethanonceinacalendaryear.
G-19TableG-7.SummaryofPSDIncrementst1AllowableIncrement(J.lg/m3)ContaminantandAveragingTimeClassClass11ClassIIITotalsuspendedparticulateAnnual5193724-hrt2103775SulfurdioxideAnnual2204024-hrt25911823-hrt225512700t1AlaskaPSDincrementsareidenticaltoCodeofFederalRegulations,40CFRPart52.t2Nottobeexceededmorethanonceinacalendaryear.Althoughthecombined-cycleplantstackswouldbeonly65ft(20m)high,theveryhightempera-tureatplumeexit[about350°F(180°C)]wouldleadtoaverybuoyantplumeandhighplumerise.Asaresult,lowconcentrationsarepredictedatgroundlevel.Otherpollutantsreleasedfromthecombined-cyclegasunitwouldbeatextremelylowlevels.PSDlimitsonS02andTSPshouldbesatisfied,giventheverylowemissionlevelsofthesepollutantsfromsuchunits.Itshouldalsobenotedthatthecombined-cycleplantswouldnotbelocatedclosetoelevatedterrain.Thus,thereshouldbenoPSDClassIIviolations.*NosignificantimpactonnearbyClassIareasisexpected,giventhelowpollutantemissionlevelsforS02andTSPandthelargedistancesbetweenanyoftheseunitsandtheClassIareasofAlaska.Carbonmonoxideemissionsfromthe200-MWeunitsoutheastofAnchoragewouldbesufficientlydilutedduringtransporttohaveaninsignificantimpactontheAnchoragenonattain-mentarea.Thep~edictedground-levelconcentrationsattheAnchoragemunicipalboundarywerebelowsignificantlevelsforcarbonmonoxide.CarbonmonoxideconcentrationsattheboundaryofAnchoragefromasourceoriginatingoutsidethemunicipalityareregulatedbytheStateofAlaska:anincreaseofnomorethan500J.lg/m3isallowedforamaximum8-hraverage,or2,000J.lg/m3foramaximum1-hraverage.Climaticandairqualityimpactsofthe70-MWecombustion-turbineunitswouldbenegligiblebecauseofthesmallheat,moisture,andpollutantreleases.Noiseimpactsshouldalsobeinsignificantiftheturbinesweresitedatleast3,000to6,000ft(900to1,800m)fromthenearestnoise-sensitiveareas.G.2.4Coal-FiredGenerationScenarioThepotentialimpactsofthecoal-firedgenerationscenariosareanalyzedinthissection.Thescenariosinvolvedare(1)one200-MWeunitatNenanatobebuiltbetweentheyears2010and2020aspartoftheimpactcomparisoninvolvingtheproposedSusitnaproject,(2)two200-MWecoalunitsatWillowandthreeatNenanaaspartofthecoal-firedgenerationscenario,and(3)one200-MWecoalunitatNenanaaspartofthecombinedhydro-thermalgenerationscenario.Alsoanalyzedisthecoal-generationscenarioinwhichfive200-MWecoalunitswouldbesitedatNenana.Aswillbeseen,thatlatterscenariowouldhavedifficultyinmeetingail'qualityregulationsandwasrejectedfromdetailedconsiderationintheremainingportionofthedocument.Thecoal-firedplants(uptofive200-MWeunitsatNenana,twoatWillow)wouldbetoosmalltosignificantlyaffecttheclimateintheNenanaandWillowareas.Theeffectoflandclearing,paving,anderectionofbuildingswouldinvolveachangeinthesurfacealbedosandheatcapaci-tiesoversmallarea.Asmallvaporplumeapproximately0-300ft(0-100m)longwouldbeexpectedfromthewet/drycoolingtowel's;onlyverysmallincreasesintemperatureandhumiditywouldbeexpectedinsmallareasnearthetowerstructures.Avaporplumefromtheplantstackswouldbe*Thisproblemdoesarisewiththecoal-generationscenarioatNenanaaswillbeseeninthenextsection.
G-20visibleovertensoffeetinthesummerandupto2,000ft(600m)inthewinter;thepreciselengthoftheplumedependsontheairtemperatureandhumidity.Ground-levelfoggingandicingwouldbeveryunlikely.Specificcalculationscould,however,bemadeonceadesignforthecoolingtowersismadeavailable.Thesearethemajorairqualityissuesinvolvingthecoal-firedplantstackreleases:(1)main-tainingAlaskaambientairqualitystandards,(2)meetingPSDincrementsnotonlyintheClassIIareainwhichNenanaandWillowarelocated,butattheClassIDenaliNationalParkapproximately60mi(100km)southoftheNenanasite(seeFig.G-7),(3)ensuringnosignificantimpactonthenearbynon-attainmentareaforCOatFairbanks,and(4)ensuringnoimpairmentofvisibilityattheDenaliNationalPark.Toinvestigatetheseissues,theStaffmadenumericalcomputationswithEPA-approvedscreeningmodels.First,inresponsetoitems(1)and(2),EPAmodelswereusedtoevaluatecompliancewithAlaskaambientairqualitystandardsandPSDClassIIincrementsinthevicinityofNenanaandWillow.Twodifferentissuesareinvolvedhere:1.ComplianceinareasofflatterrainabouttheWillowandNenanasites.Here,theEPAscreeningmodelPTPLUwasemployed,2.ComplianceinthemountainousareajustnortheastofNenana.Here,asimplifiedformoftheVALLEYModel(Budney,1977)wasusedtosimulateworst-caseconditions.SpecialconsiderationneedstobegiventothepotentialfortheNenanaplumetoimpactonthisarea,violatingPSDandpossiblyAlaskaairqualitystandards.TableG-8liststhestackcharacteristicsandemissionsofthe200-MWecoal-firedplantsemployedintheair-qualitycalculations.CalculationswithPTPLUatNenanaandWillow(seeTableG-9)revealedthatmaximum3-hrand24-hrconcentrationsforS02andmaximum24-hrconcentrationsforTSPwouldbewellwithinPSDincrements.Additionally,AlaskaambientairqualitystandardsshouldbemetforS02,TSP,andNO.AlthoughnoairqualitymonitorsarelocatedatWillowandNenana,itishighlyunlikelyth~tambientconcentrationsofS02,TSP,andNOaresufficientlyhightocauseanexceedenceofAlaskaambientairqualitystandards.Willow~ndNenanaarenotnearmajorindustrialsourcesand,asaresult,ambientlevelsareverylow.Althoughthemaximum24-houraverageNOconcen-trationswouldbegreaterthan100~g/m3,theannualaverageconcentrationsshouldberessthan100~g/m3.Thisisduetovariationinwinddirectionsovertheyearandbecauseofonlyminordifferencesbetweenthemaximum24-hraveragepredictionandtheannualNOstandard.Incrementscontributedbythecoal-firedplantswouldbesufficientlysmallthat,whgnaddedtotheback-ground,thetotalwouldfallfarbelowAlaskastandards.Forexample,forthree200-MWeunitsoperatingatNenana,thepredictedmaximum3-hrS02concentrationwas90.3~g/m3andthemaximum24-hrTSPconcentrationwas2.8~g/m3.PSDClassIIincrementsforthesepollutantsare512~g/m3and37~g/m3,respectively.Allpredictedmaximaoccurred0.9mi(1.4km)downwindofthestacks.OneadditionalfactorthatmustbetakenintoaccountinthisairqualityscreeninganalysisisthepresenceofelevatedterrainnearNenana.Thecoal-firedunitswouldbelocatedinterrain400ft(125m)abovesealevel.TothenortheastofNenanathereiselevatedterrain1,400ft(425.m)abovesealevel.Plumesfromtheonetofive(dependingonscenario)coal-firedunitsatNenanawouldnotriseoverthatelevatedterrainunderworst-casemeteorologicalconditions,accordingtotheformulasrecommendedbyBudney(1977).TobeevaluatedareplumepredictionsascomparedwithAlaskaambientairqualitystandardsandtheClassIIPSDstandardsatthelocationofplumeimpactionwiththeelevatedterrain.AsketchillustratingthesituationispresentedinFigureG-8,andthepredictedplumeconcentrationsatthepointofimpactionarelistedinTableG-10.PSDlimitsarealsopresentedforcomparison.Itappearsthatoperationofthree,four,andfive200-MWeunitsatNenanamightleadtoaviolationofPSDClassIIincrementsforS02'AmoredetailedanalysisusingtheVALLEYmodelandemployingsite-specificmeteorologicaldatawouldberequiredtoverifythesefindings.Atpresent,itseemslikelythat600,800,or1000MWeofcoal-firedgeneratingcapacityatNenanawouldviolatePSDstandards.TheissueofClassIareaimpactswasaddressedusingasimplifiedversionoftheVALLEYmodeltopredictmaximumincrementalconcentrationsunderaworst-casescenarioattheDenaliNationalPark.Nenanaisabout51mi(85km)northofthenorthernboundaryofthepark,andWi11owisabout96mi(160km)southofthesouthernboundary.Thecalculations,showninTableG-11revealedverylowS02andTSPincrementsatthisClassIarea.Forinstance,maximum24-hrconcentrationsofS02atDenaliresultingfromplantemissionsatNenanawerepredictedtobe4.1~g/m3;thePSDClassIincrementis5~g/m3.Itisalsoseenthatfourandfive200-MWeunitsatNenanawouldviolatePSDClassIincrementsforS02'MorerefinedcalculationsagainwouldinvolvetheuseoftheVALLEYmodelandsite-specificmeteorologicaldata.
G-21oFairbanksoNenanaWillow0_IoPalmero3060MilestNorthFigureG-7.RelativeLocationofNenanaandWillowwithRespecttotheClassIAreaatDenaliNationalPark.
G-22TableG-8.StackCharacteristicsandEmissionsforEach200-MWeStandardCoal-FiredUnitParameterStackCharacteristicsStackheight(ft)Exitdiameter(ft)Buildingdimensions(ft)HeightWidthLengthStackexitvelocity(ft/s)Stackexittemperature(OF)Emissionst1(g/s)S02TSPN02COValue440182101751756619056.5t21.2t3176.0t47.9t5t1Emissionsformultiplesof200MWeareobtainedbysimplymultiplyingthe200MWeemissionratesbythatmultiple.t20.3%sulfurinHealycoalisassumedwitha70%efficientdryscrubberinremovingS02't3Assumptionsare:ashcontentofcoal,9.9%;ashpartitioningis24%bottomash,76%flyash;baghouseefficiencyis99.95%.t40.6lbNOImillionBtuisassumedforNOemissionsxforHealycoal.ThislevelmehsNewSourcePerformanceStandards(NSPS).t51.0lbCOltonofcoalisassumed,basedonU.S.EnvironmentalProtectionAgency(1982).
G-23TableG-9.MaximumGround-LevelConcentrations(~g/m3)ofPollutantsfromOperationof200-MWeCoal-FiredUnitsatNenanaandWillowt1PollutantPredictedConcentrationPSDIncrementEstimatedBackgroundPredictedTotalAlaskaStandardOne200-MWePlantatNenanaMaximum3-HourAverageS02TSPNOxMaximum24-HourAverageS02TSPNOxTwo200-MWePlantsatWillowMaximum3-HourAverageS02TSPNOxMaximum24-HourAverageS02TSPNOxThree200-MWePlantsatNenanaMaximum3-HourAverageS02TSPNOxMaximum24-HourAverage502TSPNOxFour200-MWePlantsatNenanaMaximum3-HourAverage502TSPNOxMaximum24-HourAverageS02TSPNOxFive200-MWePlantsatNenanaMaximum3-HourAverageS02TSPNOxMaximum24-HourAverage502TSPNOx30.11.693.713.40.741.660.23.2187.426.81.483.290.34.8281.140.22.8166.4120.46.4374.853.62.8166.4150.58.0468.567.03.5208.0512913751291375129137512913751291370.015.08.00.015.08.00.015.08.00.015.08.00.015.08.00.015.08.00.015.08.00.015.08.00.015.08.00.015.08.030.116.6101.713.415.749.660.718.2195.426.816.491.290.319.8289.840.217.8174.4120.421.4382.853.617.8174.4150.523.0476.567.018.5216.0365150t2365150t2365150t2365150t2365150t2t1Inallcases,themaximumconcentrationwouldoccur0.9mi(1.4km)downwind.t2AlaskaairqualitystandardforNOxisanannualaverageof100~g/m3andshouldbemetinallcases.
G-24Proposedareaplantsiting~ELEVATEDTERRAIN~nd"5.6mphFstabilityPlume33ftaboveterrainx--possiblelocationofstacksofcoal-firedNenanaunitsFigureG-8.LocationofPlumeImpactionwiththeElevatedTerrainnearNenana.TableG-10.ComparisonofSimplifiedVALLEYModelPredictionsforMaximum24-hourAveragesofS02andTSPatElevatedTerrainnearNenanafor200to1000MWeofCoal-FiredGenerationSimplifiedVALLEYModelPredictionst1PSDClass(24-hraverages,in~g/m3)IIPollutant200MWe400MWe600MWe800MWe1000MWeLimitsS0233.967.8101.7135.6169.591TSP0.71.42.2 2.93.637t1Accordingtoscreeningmodelpredictions,PSDClassIIlimitsattheelevatedterrainlocationswouldbeexceededformaximum24-houraveragesofS02for3,4,and5unitsof200MWeeach.
G-25TableG-11.ComparisonofPredictedMaximum24-hrConcentrationsofS02andTSPtoPSDClassIIncrementsatDenaliNationalParkfromNenanaandWillowCoal-FiredUnitsPollutants.SimplifiedVALLEYModelPredictionPSDClassIIncrementNENANASITE200MWeS02TSP600MWeS02TSP800MWeS02TSP1000MWeS02TSP1.45.00.0410.04.15.00.1110.05.45.00.1410.06.85.00.1810.0WILLOWSITE400MWeS02TSP3.40.075.010.0AsimplifiedversionoftheVALLEYmodelwasusedtoestimatelong-distance[55-mi(88-km)]dispersionfromfiveunitsatNenanatothenearestnonattainmentareaforCO(thecityofFairbanks).Aworst-casemixingscenariowassimulated,representedbystabilityClassF,windspeedof5.6mph(2.5m/s),andaplume32ft(10m)abovetheterrain.ThepredictionforthisworstcaserevealedanextremelysmallCOincrement(1.1~g/m3foramaximum24-hraverage)atFairbanks.Thispredictedincrementwouldnotlikelyviolateanystandards(incrementof500~g/m3foran8-hraverageor2,000~g/m3foraI-hraverage).Section169AoftheCleanAirActrequiresvisibilityprotectionformandatoryClassIFederalareaswhereithasbeendeterminedthatvisibilityisanimportantvalue.Consequently,aLevel-lscreeninganalysiswasperformedtoassesspotentialvisibilityimpactsonDenaliNationalParkfromtheoperationofonetofivecoal-firedunitsatNenana.TheLevel-lvisibilityscreeninganalysisisbasedonassumptionsregardingworst-casemeteorol-ogicalconditions,andisintendedtoevaluatetwopotentialtypesofvisibilityimpairmentsthatmightbecausedbyplumesfromstackemissions.FigureG-9illustratesthetwotypesofplumeimpactsconsidered.Oneisadiscolored,darkplumeobservedagainstabrighthorizonsky(labeled1inFig.G-9).ThiseffectiscausedprincipallybyN02gasformedfromNOemissions,thoughparticulatescancontributeinsomecases.Theothertypeisabrightplumexobservedagainstadarkterrainviewingbackground(labeled2inFig.G-9).ThiseffectiscausedprincipallybyparticleemissionsandsulfateaerosolformedfromS02emissions.FigureG-I0illustratesthegeometryoftheplume,observer,andlineofsightassumedforthisscreeninganalysis.Theplumewasassumedtopassveryclosetotheobserver,withitscenter-linelocatedhalfthewidthofa22.5°sectorawayfromtheobserveratthegivendownwinddistancex.Theobserver'slineofsightwasassumedtobeperpendiculartotheplumecenterline.Theviewingbackgroundwasassumedtobeeitherthehorizonskyorablackterrainobjectlocatedontheoppositesideoftheplumeatadistanceequivalenttoafullsectorfromtheobserver.Threevalueswerecomputed:C1(thesky/plumecontl'ast),C2(thereductioninsky/terraincontrast),andC3(thechangeinsky/terraincontrastcausedbyprimaryandsecondaryaerosols).
G-26TERRAINVIEWiNGBACKGROUNDFigureG-9.TwoTypesofPlumeVisibilityImpairmentConsideredintheLevel-1VisibilityScreeningAnalysis.[Source:LatimerandIreson,1980JBLACKTARGETORHORIZONSKYVIEW-INGBACKGROUNDOBSERVER'SLINEOFSIGHT(PERPENDICULARTOPLUMECENTERLINE)ATDOWNWINDDISTANCEXFigureG-10.GeometryofPlume,Observer,andLineofSightUsedinLevel-1VisibilityScreeningAnalysis.[Source:LatimerandIreson,1980J
G-27IftheabsolutevalueofeitherC1,C2,orC3isgreaterthan0.10,theemissionssourcefailstheLevel-lvisibilityscreeningtest,andfurtherscreeninganalysisisrequiredtoassesspotentialvisibilityimpairment.IftheabsolutevalueofC1,C2,orC3islessthan0.10,itishighlyunlikelythattheemissionssourcewouldcauseadversevisibilityimpairmentinClassareas,andfurtheranalysisofpotentialvisibilityimpactswouldbeunnecessary.TheLevel-lscreeninganalysiswasbasedonworst-casemeteorologicalconditions.ForC1andC2,theseoccurwhentheplumematerialisconcentratedinstable(Pasqui11-GiffordstabilitycategoryF),light-windconditions,witha12-hrtransporttimetotheclosestClassIarea.ForC3,theworstcaseoccursinlimitedmixingconditions,saywithaverticallywell-mixedplumewitha3,000-ft(l,OOO-m)mixingdepthanda7.5ft/s(2m/s)windspeed.Fiveadditionalinputparameterswerealsousedtoevaluatepotentialvisibilityimpactswiththisscreeninganalysisprocedure;minimumdistanceoftheemissionssourcefromapotentiallyaffectedClassIarea,locationoftheemissionssourceandClassIarea,particulateemissionrate,NOemissionrate,andS02emissionrate.TableG-12presentstheresultsofthescreeningcalculatfonsforonetofiveunitsatNenanaandtwounitsatWillow.Asthetableshows,therewasnovisibilityimpairmentwithoneandtwocoal-firedunits,althoughsomeplumecontrastwiththeskywouldstillbenoticeable'atDenali.Forthethree,four,andfiveunits,however,therewasvisibilityimpairment,largelybecauseofNOxemissionsandchemicalconversionsduringtransportoftheNenanaplumetoDenali.ThelargebackgroundvisualrangeatDenali[100-235mi(170-390km)Jisacontributingfactorinthisvisibilityimpairment.Level-2andLevel-3analysesmayleadtothesameresultsbecauseoftheextrememeteorologyinthatarea,i.e.,highfrequencyofinversionsandpoormixingofpollutants.ControltechnologyappliedtoNOmight,however,permitthesitingofthreeunitsatNenana.Anotherpossibilityistheplace~entof,say,threeunitsatWillowandtwoatNenana.ThislatterpossibilitywouldnotleadtoPSDorvisibilityimpairmentproblemsateitherNenanaorWi11ow.Visibilityscreeningfortheplumefromthetwo-unitplaneatWillowindicatednovisualimpair-mentatDenali,althoughaplumecontrastwiththeskywouldbeobservedoverDenaliNationalPark.Constructionandoperationalnoiseimpactsfromthecoal-firedplantswouldbeminimalifsitingwereatleast1,500to3,000ft(450to900m)fromthenearestresidences.Themajornoisesourcesduringplantoperationwouldbethecoal-handlingequipment,thecoolingtower,andthetransformers.Anin-depthanalysisofnoiseimpactsrequiresapreciselocationoftheplantwithrespecttothenearestnoise-sensitiveareas,dataonambientnoiselevels,andanidentifi-cationofspecific'equipmenttobeusedinplantconstructionandoperation.G.2.5CombinedHydro-ThermalGenerationScenarioThethermalportionofthecombinedhydro-thermalgenerationscenariowasdiscussedinSec-tionsG.2.1throughG.2.4,Theimpactsofthenon-SusitnaBasinhydropoweralternativeswouldbesimilartothoseofthein-basinalternatives.Dependingonthesiteboundariesforcon-structionandoperationofJohnson,Keetna,Snow,andBrowne,fugitiveemissionandnoiseimpactsmightextendbeyondthoseboundaries.Nonoiseimpactswouldbeexpected,however,ifnonoise-sensitiveareaswerewithin1,500to3,000ft(450to900m)oftheplantsite.The85,000-acre(34,400-ha)impoundmentassociatedwiththeJohnsonalternativemightcauseoccasionalfoggingandicingeffectsupto150ft(45m)beyondthereservoirboundaries.
Table G-12.Results of Level-1 Screening Analysis Based on Nenana and Willow Emissions
Background Visual Range (miles)
Clt l C2 t 2 Cs t 3
Scenario 100 120 150 240 100 120 150 240 100 120 150 240
Nenana
1 unit 0.035 0.037 0.040 0.044 0.010 O.Oll O.Oll 0.010 0.004 0.005 0.006 0.010
2 units 0.068 0.072 0.077 0.085 0.021 0.021 0.021 0.020 0.009 0.010 0.012 0.019
3 units 0.103*t 4 0.105*0.ll2*0.124*0.031 0.032 0.032 0.030 0.013 0.015 0.019 0.028
4 units 0.128* 0.136* 0.145* 0.161*0.042 0.043 0.043 0.040 0.017 0.020 0.024 0.037
5 units 0.156*0.165*0.177*0.195*0.052 0.054 0.054 0.051 0.021 0.024 0.030 0.046
Wi 11 ow c;)
I2units0.028 0.034 0.077 0.045 0.009 O.Oll 0.021 0.012 0.009 0.010 0.012 0.019
Nco
t 1 C1 refers to sky/plume contrast.
t 2 C2 refers to reduction in sky/terrain contrast.
t 3 Cs represents the contrast reduction of the plume with respect to terrain.
t 4 An asterisk ("*")means that the Level-1 screening analysis exceeds 0.1,indicating visibility impairment.
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