USEPA / AmerenUESioux Power PlantIntake Structure Site VisitMarch 4, 2009 USEPA IntakeStructure Site Visit2Sioux Power Plant General NotesTwo identicalsteam-generatingunits: ~950 MWBegan Operation:1967, 1968Capacity Factor:66.4% (2008)WFGD scrubbersunder constructionMarch 4, 2009 USEPA IntakeStructure Site Visit3Sioux Power PlantMississippi River OverviewDrainage area:~189,000 mi2Located in Pool 26Water elevationdependent uponUSACE operationLarge water volumeHistoric high flowevents (Grafton IL):1993: 598,000 cfs2008: 439,000 cfsMarch 4, 2009 USEPA IntakeStructure Site Visit4Sioux Power PlantBefore 1993 Mississippi River FloodMarch 4, 2009 USEPA IntakeStructure Site Visit5Sioux Power Plant1993 Mississippi River FloodMarch 4, 2009 USEPA IntakeStructure Site Visit6Sioux Power PlantBefore 1993 Mississippi River FloodMarch 4, 2009 USEPA IntakeStructure Site Visit7Sioux Power Plant1993 Mississippi River FloodMarch 4, 2009 USEPA IntakeStructure Site Visit8Sioux Power PlantIntake Structure DesignCanal intakeAverage 2007-2008 Mississippi waterwithdrawal ~430,000gpm (~958cfs)Design flow = 520,000gpm (1,160cfs)Four intake bays/pumpsMarch 4, 2009 USEPA IntakeStructure Site Visit9Sioux Power PlantIntake ConfigurationMarch 4, 2009 USEPA IntakeStructure Site Visit10Sioux Power PlantIntake ConfigurationMarch 4, 2009 USEPA IntakeStructure Site Visit11Sioux Power PlantIntake ConfigurationMarch 4, 2009 USEPA IntakeStructure Site Visit12Sioux Power PlantIntake Structure DrawingMarch 4, 2009 USEPA IntakeStructure Site Visit13Sioux Power PlantTraveling Screen & Bar Rack DesignBar rack on 3” center1.4 fps screen approach velocity1/2” mesh screensScreen wash discharge to flumeScreen rotationDetermined by∆P“Normal” (6”)“Fast” (10”)Auto rotation 1/shiftMarch 4, 2009 USEPA IntakeStructure Site Visit14Sioux Power PlantIntake Bay DrawingMarch 4, 2009 USEPA IntakeStructure Site Visit15Sioux Power PlantIntake Structure Bar RackMarch 4, 2009 USEPA IntakeStructure Site Visit16Sioux Power PlantIntake Structure MaintenanceScheduled routine visual inspectionScheduled diver inspectionMarch 4, 2009 USEPA IntakeStructure Site Visit17Sioux Power PlantIntake Structure Debris & Icing ImpactsHistoric debris issuesLeaves during Spring and FallTraveling screen damageBar rack damageHistoric icing issuesLoad reduction and outage timeMarch 4, 2009 USEPA IntakeStructure Site Visit18Sioux Power PlantIntake Debris PhotographsMarch 4, 2009 USEPA IntakeStructure Site Visit19Sioux Power PlantIntake Debris PhotographsMarch 4, 2009 USEPA IntakeStructure Site Visit20Sioux Power PlantTraveling ScreenMarch 4, 2009 USEPA IntakeStructure Site Visit21Sioux Power PlantTraveling ScreenMarch 4, 2009 USEPA IntakeStructure Site Visit22Sioux Power PlantIntake Impingement Mortality StudiesConducted in 2005-2006No T&E species~98.2% shad & drum~99.2% shad/drum/carpMarch 4, 2009 USEPA IntakeStructure Site Visit23Sioux Power PlantIntake Draft Technology AssessmentConducted prior to remand of Phase II RuleFine mesh screens not evaluated per Phase II RuleBar rack with barrier1” spacing located at canal entrance0.4fps approach velocityTrash rake system$34M (2002 estimated)Barrier net1⁄4” mesh located at canal entrance0.2fps approach velocityManual cleaning using divers$29M (2002 estimated)March 4, 2009 USEPA IntakeStructure Site Visit24Sioux Power PlantIntake Draft Technology Assessment (Part 2)Wide slot cylindrical wedgewire screensBulkhead mounting at canal entrance, 0.5fps approach velocity8 screens (each 7’Dx23’L)Air backwash system (no provisions for biofouling)$61.5M (2002 estimated)Ristroph screens with expanded intake1.0fps screen approach velocity, 3/8” screen meshTwo new bays with pumpsNew fish return system$63.4M (2002 estimated)Ristroph screens with reduced intake flow1.0fps screen approach velocity, 3/8” screen mesh21% flow reductionNew fish return system$58.4M (2002 estimated)March 4, 2009 USEPA IntakeStructure Site Visit25Sioux Power PlantComments and questions