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Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Table of Contents 1.0
ExecutiveSummary............................................................................................................................1‐1
1.1
SummaryofFindings..........................................................................................................................1‐1
2.0
BottomAshSettlingAreaCharacterization...............................................................................2‐1
2.1
LocationandGeneralDescription.................................................................................................2‐1
2.2
ImpoundmentDesign/ConstructionHistory...........................................................................2‐1
2.3
ImpoundmentModifications...........................................................................................................2‐1
2.4
CurrentImpoundmentDimensionsandCapacities..............................................................2‐1
2.5
ImpoundmentInstrumentation.....................................................................................................2‐2
2.6
ImpoundmentInspections...............................................................................................................2‐2
2.6.1
2009Black&VeatchInspection.................................................................................2‐2
2.6.2
2015Haley&AldrichAnnualInspection................................................................2‐2
2.6.3
2016Black&VeatchInspection.................................................................................2‐2
3.0
SubsurfaceCharacterization...........................................................................................................3‐1
3.1
PreviousInvestigations.....................................................................................................................3‐1
3.1.1
InitialGeotechnicalInvestigation...............................................................................3‐1
3.1.2
2009Investigation............................................................................................................3‐1
3.1.3
2014Survey........................................................................................................................3‐2
3.1.4
2015Inspection.................................................................................................................3‐2
3.1.5
2016MonitoringWells...................................................................................................3‐2
3.2
DataGapAnalysis................................................................................................................................3‐2
3.3
2016SupplementalInvestigation.................................................................................................3‐3
3.4
DesignSubsurfaceConditions........................................................................................................3‐4
3.5
DesignGroundwaterConditions...................................................................................................3‐6
4.0
SafetyFactorAssessment.................................................................................................................4‐1
4.1
SlopeStabilityAnalysis......................................................................................................................4‐2
4.1.1
Long‐TermMaximumStorageLoading...................................................................4‐2
4.1.2
MaximumSurchargeLoading......................................................................................4‐2
4.1.3
SeismicLoading.................................................................................................................4‐3
4.1.4
SoilLiquefaction................................................................................................................4‐3
5.0
References.............................................................................................................................................5‐1
AppendixA2016SupplementalInvestigation.......................................................................................A‐1
BLACK & VEATCH | Table of Contents i
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 LIST OF TABLES Table1‐1
Table3‐1
Table3‐2
Table4‐1
InitialSafetyFactorAssesmentResults......................................................................................1‐1
DataGapAnalysisMatrix..................................................................................................................3‐3
StabilityAnalysisparameters.........................................................................................................3‐6
CCRRuleSafetyFactorRequirements(§257.73(e)).............................................................4‐2
LIST OF FIGURES (LOCATED AFTER REPORT TEXT) Figure1‐1SafetyFactorAssessmentProcessOutline.........................................................................................F‐2
Figure2‐1SiteLocation....................................................................................................................................................F‐3
Figure2‐2SubsurfaceInvestigation............................................................................................................................F‐4
Figure4‐1SlopeStabilityResults–Long‐TermStabilityCase.........................................................................F‐5
Figure4‐2SlopeStabilityResults–MaximumSurchargeCase.......................................................................F‐6
Figure4‐3SlopeStabilityResults–SeismicCase..................................................................................................F‐7
BLACK & VEATCH | Table of Contents ii
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 1.0 Executive Summary ThisreportpresentsasummaryoftheinitialsafetyfactorassessmentfortheWestarJeffrey
EnergyCenter(JEC)BottomAshSettlingAreanearStMarys,Kansas.Thisinitialsafetyfactor
assessmentwascompletedincompliancewith40CFR§257.73(e)andincludescompilationofthe
historyofconstructionandmodificationsincompliancewith40CFR§257.73(c),aswellasreview
ofavailableinformationregardingtheimpoundmentaswellasavisualinspectionofthe
impoundmentandappurtenantstructures.Theoverallstepsforthesafetyfactorassessmentare
showninFigure1‐1.
1.1
SUMMARY OF FINDINGS TheinitialsafetyfactorassessmentfortheBottomAshSettlingAreabermconfirmsthatthe
calculatedfactorsofsafetyequalorexceedtheminimumsafetyfactorsforrequiredbytheCCRRule
(Table1‐1).
TABLE1‐1
INITIALSAFETYFACTORASSESMENTRESULTS
MINIMUMFACTOROF
SAFETY(1)
CALCULATEDFACTOROF
SAFETY
Long‐term‐maximumstoragepool
1.50
1.55
Maximumsurcharge
1.40
1.50
Seismicloading
1.00
2.82
SoilLiquefaction(2)
1.20
N/A(3)
LOADINGCONDITION
Notes:
(1)CCRRuleSafetyFactorRequirements(§257.73(e).
(2)Soilliquefactioncaseisonlyrequiredifsoilsareidentifiedashavingpotentialforliquefaction
underseismicloading.
(3)Soilsweredeterminedtobenon‐liquefiable.
BLACK & VEATCH | Executive Summary 1‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 2.0 Bottom Ash Settling Area Characterization 2.1
LOCATION AND GENERAL DESCRIPTION TheJECEnergyCenterBottomAshArea(BASA)islocatedinSt.Marys,Kansas,within
PottawatomieCounty,innortheasternKansas(Figure2‐1).ThelatitudeandlongitudeoftheBASA
centerisapproximately,39.286N,96.117W.TheBASAisavalleyfill,surfaceimpoundmentthat
collectsbottomashfromthemainplant.ThebottomashisdeliveredtotheBASAasslurryvia
multiplepipesattheeastend.Theheavierbottomashsettlesintheareanearthepipeoutlet,and
isroutinelyremovedtoallowthewatertoflowintotheremainingportionoftheBASAwherethe
suspendedbottomashisallowedtosettle.Anoutletpipenearthebermallowstheclearwaterto
exitandflowtothenextpond(BottomAshPond)inthesystem.Bottomashisremovedfromthe
BASA,dewatered,andusedattheplantsite.
2.2
IMPOUNDMENT DESIGN/CONSTRUCTION HISTORY InformationprovidedbyWestarEnergyfora2009BlackandVeatch(B&V)Inspectionand
EngineeringEvaluationreportandthe2016AnnualInspectionReportpreparedbyHaleyand
Aldrich,Inc.(H&A)fortheBASAindicatesthattheimpoundmentwasconstructedinthe1980’s
initiallyasasmall,non‐engineeredstructure.Thebermwaslaterenlargedbyusingamixedfill
consistingofflyashandbottomashspreadandcompactedin1to2footlifts.Compactiongenerally
wasaccomplishedbyusingthedozersandscrapersthatwereusedtoplacethematerial.No
constructionrecordswereprovidedaspartofthisassessment.Accordingtothe2009report,the
BASAhasaninletinvertpipeelevationof1231.72feetandanoutletinvertelevationof1205.58
feet.Theoutletpipedischargestoanopenchannelthatcontinuestowardsthenextbottomash
pond.
NodesigndrawingswereprovidedbyWestarEnergy.Threeboringsweredrilledaspartof
the2009inspectionandevaluationstudy(Figure2‐2).Allthreeboringsindicatethatthefly
ash/bottomashmix(siltysand)restsincontactwithweatheredrockandbedrockshaleand
limestone.Basedontheborings,thenativesoil(siltyclay)appearstohavebeenremovedpriorto
buildingtheberm.
2.3
IMPOUNDMENT MODIFICATIONS The2016H&AAnnualInspectionReportindicatesthatin2012theBASAunderwenta
verticalexpansionbeingraisedbyapproximately4feet.Thereportindicatedthatthebermwas
raisedusingamixtureofflyashandbottomashcompactedin8inchthicklifts.BasedonB&V
discussionwithfacilitystaff,therewasnoconstructiondocumentationoftheverticalexpansion.
Duringthiswork,theinletinvertpipeelevationwasalsoraisedto1239.5feet.
2.4
CURRENT IMPOUNDMENT DIMENSIONS AND CAPACITIES Basedonthe2015H&AAnnualInspectionReport,thebermhasanominalcrestelevation
of1,243feet.Elevationatthedownstreamtoeofthebermatthelowestpointisapproximately
BLACK & VEATCH | Bottom Ash Settling Area Characterization 2‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 1,198feetresultinginamaximumbermheightofapproximately45feet.Thebermis40feetwide
atthecrestandapproximately1,500feetlong.Theimpoundmenthasafootprintofapproximately
52.5acresandhasadesigntotalcapacityof1,593,200cubicyards
Althoughthebermisonecontinuousfeature,inplanviewitcanbeseparatedintoa“west
berm”sectionthattrendsnorth‐southanda“northberm”sectionthattrendseast‐west.Thewest
bermincreasesinelevationtoapproximately1245feetwhereitjoinstheexistinggrade.Thenorth
bermincreasesinelevationto1250feetwhereitjoinstheexistinggrade.
2.5
IMPOUNDMENT INSTRUMENTATION Currently,noinstrumentationexistsinthebermattheBASA.Twopiezometerswere
installedduringthe2009B&Vinvestigation;however,the2016H&AAnnualInspectionReport
notedthatthepiezometerswerenon‐functioningandremovedshortlyaftertheinspection.
2.6
IMPOUNDMENT INSPECTIONS InaccordancewiththeCCRRules,avisualinspectionoftheBASAisperformedbyWestar
EnergyInc.onanintervalnotexceedingsevendays.Thevisualinspectionincludesinspectionfor
anysignsofpotentialstructuralweaknessorotherconditionsthathavethepotentialtodisruptthe
operationorsafetyoftheimpoundment.
Thefollowingpreviousinspectionswerealsoreviewedaspartofthisassessment.
2.6.1 2009 Black & Veatch Inspection Black&VeatchperformedavisualinspectionoftheBASAin2009aspartoftheengineering
evaluation.Theinspectionindicatednosignsofinstability;however,severalareasoferosionwere
noted.
2.6.2 2015 Haley & Aldrich Annual Inspection Haley&AldrichperformedanannualinspectionoftheBASA(BottomAshAreaI
Impoundment)on8October2015.Accordingtothereport,theelevationofthepoolatthetimeof
theinspectionwas1239.5feet.Basedontheirinspection,nosignsofinstabilityorunusual
movementofthebermwasnoted.Haley&Aldrichdidnoteseveralareasofseepageanderosion
alongthefaceoftheberm.
2.6.3 2016 Black & Veatch Inspection Aspartoftheinitialsafetyfactorassessment,Black&Veatchperformedavisualinspection
oftheimpoundmenton29July2016.Theprimaryobjectiveoftheinspectionwastoobservethe
bermslopeconditionsandidentifyanyissuesthatwouldaffectthestabilityoftheberm.Consistent
withthe2015H&AAnnualInspection,Black&Veatchalsoobservedseveralareasofseepage
evidencealongthedownstreamslopefaceoftheberm.Atthetimeoftheinspection,
measurementsindicatedthattheseepagewasoccurringfairlyconsistentlyapproximately50feet
fromthecrestedgeoftheslope.
BLACK & VEATCH | Bottom Ash Settling Area Characterization 2‐2
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 3.0 Subsurface Characterization Theinitialstepinthesafetyfactorassessmentwastogatherandreviewtheexisting
informationontheBASAtofullycharacterizethesubsurfaceconditionsoftheberm.Black&
Veatchreviewedtheexistingsubsurfaceinvestigationsandanalysistodetermineifanydatagaps
existed.Basedontheresultsofthedatagapanalysis,samplesofthe2012fillwerecollectedand
tested.Theresultsofthedatacollectionanddatagapprocessaredescribedinthefollowing
sections.
3.1
PREVIOUS INVESTIGATIONS 3.1.1 Initial Geotechnical Investigation ThesubsurfaceinvestigationfortheJeffreyEnergyCenterwasconductedin1974.Nosoil
boringswereperformedintheimmediateareaoftheBASAaspartofthesubsurfaceinvestigation
fortheplant,coalstoragearea,andrailroadspurs.Theclosestboringthatwaspartoftheinitial
investigationislocatedontheoppositesideofthenorth‐southrailroadspureastoftheBASA.
Theexistingbermandimpoundmentdevelopedfromasmallnon‐engineered
impoundmentthatwascollectingbottomash.Itappearsthatnoboringswereperformedaspartof
thedesignanddevelopmentoftheearlyimpoundment.
3.1.2 2009 Investigation In2009,Black&VeatchwascontractedtoperformaninspectionandevaluationoftheBASAberm
atJeffreyEnergyCenter.Thestudyincluded:

Sitemonitoringandinspectionoftheberm

Surveytheberm

Geotechnicalinvestigation

Slopestabilityanalysisoftheberm

Reportofresults
Thegeotechnicalinvestigationincludedthreeboringsalongthecrestoftheberm(Figure2‐
2).Thedepthsoftheboringsvariedfrom31feetto61feet,andeachboringcoredatleast10feet
ofbedrock.SamplingincludedStandardPenetrationTests(SPT),Thin‐walledsamples(Shelby
Tubes),bulksamples,androckcores.Laboratorytestingincludessoilmoisture,drydensity,
Atterberglimits,grainsizeanalysis,unconfinedcompressivestrength,anddirectsheartesting.A
standardProctortestwasperformedontheflyash/bottomashmaterial.
Theboringlogsindicatethatthebermischaracterizedasverydensesiltysandthatisgray,
brown,reddishorange,ortan,finegrained,andcontainsatracetosomegravel.Layerswithatrace
ofcementationwerealsoobserved.Thesiltysandoverliesbedrockcomposedofgrayishgreen
shaleortantoorangelimestone.Theshalerangesfromhighlyweathered(canbebrokenbyhand,
BLACK & VEATCH | Subsurface Characterization 3‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 textureindistinct,andfabricintact)toresidualsoil(advancedstateofdecompositionresultingin
plasticsoil).LimestonewasencounteredatthebaseoftheberminboringB‐3andwasdescribed
asmoderatelyweathered(discolorationthroughout,slightlossofstrength,andtextureintact).
TwopiezometerswereinstalledatsoilboringsB‐1andB‐3aspartofthe2009geotechnical
investigation(Figure2‐2).ThepiezometeratB‐1(B‐1A)wasinstalledwiththescreenedinterval
fromadepthof19feetto29feet,whichwouldbeatthebaseoftheberm.ThepiezometeratB‐3
(B‐3B)wasinstalledwithascreenedintervalfrom12.5feetto22.5feet,whichisalsoatthebaseof
theberm.Ameasurementofgroundwaterduringdrillingwasatadepthof28.5feet.Thisvalue
shouldbeconsideredsuspectbecauseitwasbelowthebaseoftheberm.Twoothervalueswere
reportedonthepiezometerconstructionlogs;however,thedateofmeasurementisnotconsistent
withthepiezometerlogs.ThemeasuredwaterdepthsatB‐1AandB‐3Bwere19.1feet(elevation
1225.9feet)and12.1feet(elevation1226.9feet),respectively.Bothofthesedepthswouldplace
thegroundwatersurfacewithintheberm.
3.1.3 2014 Survey Asdocumentedinthe2016AnnualInspectionReport,acombinationtopographicand
bathymetricsurveywascompletedbyProfessionEngineeringConsultantsin2014.
3.1.4 2015 Inspection The2015AnnualInspectionbyHaleyandAldrichdidnotincludesoilboringsormaterial
testing.
3.1.5 2016 Monitoring Wells InMarch2016Haley&Aldrichinstalledatotalofsixmonitoringwellsaroundtheareaof
theBASAberm.ThelocationsofthesesixboringsareshownonFigure2‐2.
3.2
DATA GAP ANALYSIS Black&Veatchcompletedadatagapanalysisoftheexistingavailableinformationto
identifyiftherewereanddatagapsthatwouldneedtobefilledpriortocompletingtheboththe
factorofsafetyandliquefactionanalysis.Table3‐1presentsamatrixthatpresentstheresultsof
thedatagapanalysis.
BLACK & VEATCH | Subsurface Characterization 3‐2
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 TABLE3‐1
DATAGAPANALYSISMATRIX
REQUIRED
DATA
QUALITATIVE
EFFECTON
ANALYSIS
INFORMATIONSOURCE
QUALITYOF
DATA
DATAGAP
SlopeGeometry
High
Topographic/Bathymetric
surveyin2014
High
No
MaterialUnit
Weight
Medium
2009B&VReport
High
Yes,no
informationon
2012fill
MaterialStrength High
2009B&VReport
Medium
Yes,no
informationon
2012fill
Groundwater
Conditions
withinSlope
Medium
Seepageobservations
from2015and2016
Inspections
Low(no
piezometer
measurementsin
dike)
No
SeismicLoading
Low(minimal
seismicloadingin
thisarea)
USGSSeismicHazardMap
High
No
RequiredDesign
Margins
High
CCRRules
High
No
Basedonthedatagapanalysis,Black&Veatchdeterminedthatthelackofinformationon
thematerialpropertiesofthe2012fillmaterialwasadatagap.Basedondiscussionswithplant
staff,thematerialusedwasacombinationofflyashandbottomashthatwasconsistentwiththe
materialusedinthepreviousbermraises;however,therewasnodocumentationofthefill
placement.Inordertofilltheinformationgap,asupplementalinvestigationwasconductedon
2016andisdiscussedinthefollowingsection.
3.3
2016 SUPPLEMENTAL INVESTIGATION AsindicatedinTable3‐1,thelackofinformationregardingthematerialusedforthe2012
dammodificationswasidentifiedasadatagap.Sincetheamountoffillplacedduringthe
modificationwasgenerallylessthan3feet,shallowtestpitswereusedtoobtainsamplesofthefill
material.
BLACK & VEATCH | Subsurface Characterization 3‐3
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 ThesitewasvisitedbyBlack&Veatchon8July2016,andatthattime,threebulksamples
werecollectedofthefillmaterialasshownonFigure2‐2.Photosofthethreetestpitsareincluded
inAppendixA.
Sampleswerecollectedinfivegallonbucketswithasmallsubsamplecollectedinasealed
plasticbagtopreservethenaturalsoilmoisturecontent.Black&VeatchsubcontractedTerraconof
Lenexa,Kansastoperformthelaboratorytestingonthesamplesincludinggrain‐sizeanalysis,
standardProctortesting,anddirectsheartesting.Black&Veatchtransportedthebulksampleto
theTerraconlaboratoryaswellasassignedlaboratorytestingrequirement.Theresultsofthe
laboratorytestsareincludedinAppendixA.
Thethreetestpitsindicatedthatthefillgenerallyconsistedofgrayishbrown,siltysand
withgravelthatwascemented.Drycrushstrengthoftheintactmaterialsuggestedahard
consistency.Sincethismaterialwasreportedtobeamixtureofflyashandbottomash,the
cementationislikelytheresultoftheself‐cementingpropertiesoftheflyash.Comparedtothe
bermmaterialfromthe2009investigation,thenearsurfacematerialwithinthebermwasgenerally
coarserandhadlessfinesthanthedeeperoriginalbermmaterial.Thedirectsheartestresults
showedaslightlylowerstrength,bothfrictionandcohesion,comparedtothedeeperoriginalberm
material.Itshouldbenotedthatthedirectsheartestswereperformedonrecompactedsamples
andthesampleswerenotallowedtocure;thereforethecementationobservedinthesoilsfromthe
testpitswasnotconsideredinthetest.Basedontheobservationofcementationinthetestpits
comparedtothelowcohesioninterceptofthetestresults,thesetestresultsareconsidered
conservativeasthein‐situbermmaterialisexpectedistoshowahighercohesioninterceptdueto
thecementation.
3.4
DESIGN SUBSURFACE CONDITIONS Thedesignsubsurfaceconditionsforthefactorofsafetyassessmentweredevelopedbased
onreviewofthepreviousinvestigationsandsupplementalinvestigation.The2016Haley&Aldrich
boringswereadvancedalongthetoeoftheimpoundment.Reviewofthefourborings(MW‐BAA‐1,
2,3,and4)indicatedthatthetoeoftheimpoundmentgenerallyconsistedofzeroto7feetof
overburden/clayeysandfollowedbylimestoneandshalebedrock.Whilenogeotechnical
laboratorytestingwasprovidedfortheseborings,thesoillayeringwasusedtodevelopthecritical
slopestabilitysection.
Thethreeboringsfromthe2009Black&VeatchReportweredrilledalongthecenteraxisof
theberm(Figure2‐2).Allthreeboringsindicatedthatthebermfillconsistedofflyash/bottomash
mixthatclassifiedassiltysand.Thematerialwithinthebermwasdescribedasverydense,tan,
brownandgray,silty,finegrainedsandwithatraceofgravel.Designsoilpropertiesforthislayer
weredeterminedbasedonaveragevaluesfromlaboratorytesting,andarelistedinTable3‐2.
Thethreetestspitsthatwerecompletedaspartofthe2016supplementalinvestigation
indicatedthatthematerialusedtoraisethebermin2012wasslightlycoarserthantheoriginal
bermfillandhadaslightlylowerstrength.Designsoilpropertiesofthismaterialweredetermined
basedonthedirectsheartestresultsandarelistedinTable3‐2.
BLACK & VEATCH | Subsurface Characterization 3‐4
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Basedonthe2014topographicandbathymetricsurvey,upstreamoftheberminthe
impoundment,bottomashappearstohavesettledfromtheslurrywaterandhascollectedalong
thebottomoftheimpoundmentandupstreamtoeoftheberm.Nosamplesofthismaterialwere
collectedduringthe2009B&Vstudy.Thismaterialwasconsideredtohavenostrengthonlyaunit
weight.Sincethismaterialisontheupstreamportionoftheberm,thematerialdoesnotaffectthe
stabilityoftheberm.
Thebermfillrestsdirectlyonaweatheredbedrockprofilecomposedofshaleand
limestone.Basedonthethree2009borings,thetopoftheprofileisagrayishgreenshalethatis
weatheredtoresidualsoil.Thematerialpropertiesfortheweatheredshaleweredevelopedbased
ontheresultsfromthe2009B&Vreport.Drainedoreffectivestressstrengthparameterswere
developedbasedonpublishedcorrelations.Thedesignvaluesfortheweatheredshaleare
presentedinTable3‐2.
Belowtheweatheredshale,thebedrockiscomposedofshaleandlimestone.Unconfined
compressiontestingindicatedthestrengthoftheintactrockvariedbetweenapproximately400
and9,000poundspersquareinch.ThedesignpropertieslistedinTable3‐2werebasedonthe
loweststrengthandaverageunitweightsfromthelaboratorytesting.
BLACK & VEATCH | Subsurface Characterization 3‐5
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 TABLE3‐2
STABILITYANALYSISPARAMETERS
LAYER
BERMMATERIAL
UPPER
LOWER
TotalUnitWeight
125
125
BOTTOM
ASH
WEATHERED
SHALE
BEDROCK
115
125
140
TotalStress(Undrained)Parameters
Cohesion(c)(psf)
330
1300
0
2000
30,000
AngleofInternalFriction()
(degrees)
33
38
0
0
0
EffectiveStress(Drained)Parameters
Cohesion(c’)(psf)
330
1300
0
0
30,000
AngleofInternalFriction(’)
(degrees)
33
38
0
28
0
3.5
DESIGN GROUNDWATER CONDITIONS Nolongtermfieldmeasurementsoftheporepressureshavebeencollectedwithinthe
berm.Forthestaticandseismicanalysis,itwasassumedthatthewaterelevationontheupstream
sidewouldbeattheelevationoftheoutletinvert(1239.5feet).Waterlevelmeasurementswere
notedonthepiezometerlogsfromthe2009Investigation.ThewaterdepthsatB‐1andB‐2were
reportedat19.1feetdeep(elevation1225.9feet)and12.1feet(elevation1226.9feet),respectively
withanaveragevalueofelevation1226.4feet.Thesetwomeasurementsweremadewiththepool
elevationlowerthancurrent;therefore,anadjustmentwasmadebasedonthechangeinthe
normalpoolelevationbetweenthe2009and2015Reports.Accordingtothetworeports,the
outletinvertpipeelevationwasraisedfrom1231.72to1239.5feet;therefore,theaveragephreatic
surface(upperboundaryofthewatersaturatedzone)atthecenterlineofthebermwasincreased
7.8feettoelevation1234.2feet.
Basedontheobservationofseepageinthe2015and2016inspections,thephreaticsurface
withintheslopewasshowntointerceptthedownstreamfaceoftheberm.Accordingtothe2016
B&Vinspection,theseepagewasoccurringapproximately50feetdownslopefromthebermcrest
whichwasapproximatelyelevation1222feet.Groundwaterelevationsmeasuredatthemonitoring
wellslocatedalongthewesterntoeoftheberminApril2016indicatedthegroundwaterelevation
wasapproximately1211to1212feet.Thesegroundwaterelevationsarehigherthanthelowest
surfaceelevationatthebermstoe;therefore,thephreaticsurfaceatthetoeofthebermwas
modelledatthesurface.
BLACK & VEATCH | Subsurface Characterization 3‐6
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Forthemaximumsurchargeanalysis,thewaterelevationontheupstreamsidewas
increasedtothesameelevationasthetopoftheberm.Thephreaticsurfaceinthebermwasalso
increasedthesameamount.
BLACK & VEATCH | Subsurface Characterization 3‐7
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 4.0 Safety Factor Assessment InaccordancewiththeCCRRule§257.73(e),initialandperiodicsafetyfactorassessments
arerequiredforCCRimpoundments.
Theassessmentsaretobeperformedforthecrosssectionoftheembankmentthatis
anticipatedtobethemostsusceptibletostructuralfailure.Black&Veatchidentifiedthecritical
crosssectionbasedonengineeringjudgment,theembankmentgeometry,loadingconditions,
anticipatedphreaticwaterlevelswithintheembankmentcross‐sectionaswellasexpected
subsurfacesoilconditions.Usingthe2014topographicandbathymetricsurveydata,Black&
Veatchanalyzedthreesurfaceprofilesthroughthebermtoidentifythecriticalsection(Section1)
shownon(Figure4‐1).Overall,thecrestelevationandupstreamanddownstreambermslopes
wereconsistent;therefore,thecriticalprofilewasidentifiedbasedonthelowesttoeelevation,
whichcorrespondedtothehighestberm.
Formodelingthesoilandrocklayerswithinthemodel,thebaseofthebermwas
determinedbyconnectingastraightlinefromthedownstreamtoeofthebermthroughthebottom
ofthefillinboringB‐2totheintersectionwiththegroundsurfaceupstreamoftheberm.The
upstreamslopeofthebermwasextendedtothelineformingthebaseoftheberm.Inthecross
sectionthebermconsistsofthedownstreamslope,crest,upstreamslopeandbaseoftheberm
betweentheupstreamanddownstreamslopes.Theextensionofthebaseofthebermandthe
groundsurfaceupstreamofandadjacenttothebermformsasmallareathatisassumedtobefilled
withbottomashthathassettledfromtheslurry.Theboringlogsalongthecenterlineoftheberm
indicatethattheupperportionofbedrockisweatheredshalethatisweatheredtoresidualsoil.At
thecenterline,a10‐footthicklayerofresidualshalewasmodelledbelowthebaseoftheberm.At
thedownstreamtoe,thethicknessoftheweatheredshalewasreducedbasedontheobserved
thicknessofsoilinthe2016monitoringwelllogs.Thephreaticsurfacewithinthebermforboth
long‐termmaximumpoolandmaximumsurchargecaseswasmodelledasdescribedinSubsection
3.5.
TheCCRRulerequiresthecriticalsectiontobeanalyzedunderthefourloadingcondition
listedinTable4‐1.Eachoftheseloadingconditionsaswellastheresultsarediscussedfurtherin
Section4.2.
BLACK & VEATCH | Safety Factor Assessment 4‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 TABLE4‐1
CCRRULESAFETYFACTORREQUIREMENTS(§257.73(E))
LOADINGCONDITION
MINIMUMFACTOROFSAFETY
Long‐term‐maximumstoragepool
1.50
Maximumsurcharge
1.40
Seismicloading
1.00
SoilLiquefaction*
1.20
Note:Soilliquefactioncaseisonlyrequiredifsoilsareidentifiedashaving
potentialforliquefactionunderseismicloading.
4.1
SLOPE STABILITY ANALYSIS Black&VeatchperformedtheslopestabilityanalysisusingtheSLOPE/Wcomputer
programthatispartoftheGeoStudio2012analysissoftware.TheSLOPE/Wprogramisalimit
equilibriummethodthatallowsforcomplexsoillayeringandhasthecapabilityofperforming
optimizationoftheslipsurface.
4.1.1 Long‐Term Maximum Storage Loading Thelongtermmaximumstorageloadingconditionrepresentstheconditionwiththepoolat
normaloperatingconditionundersteady‐stateseepageconditions.Theminimumfactorofsafety
determinedfortheLong‐termMaximumStorageanalysisis1.55,whichisgreaterthantherequired
factorofsafetylistedinTable4‐1(Figure4‐1).
4.1.2 Maximum Surcharge Loading AccordingtotheCCRRulePreamblePartVI(E)(3)(b)(ii)(c),themaximumsurchargepool
loadingconditionismeanttoensurethattheimpoundmentcanwithstandatemporaryriseinthe
poolelevation.Thebermhasanoutletinvertpipeelevationof1239.5feet.Additionally,aculvert
alongthenorthedgeofthebermallowswatertoexittheimpoundmentpriortothebermover
topping.Ifthesesystemsarebothunserviceable,thenthelowelevationalongthetopoftheberm
willcontrolthewaterelevation,whichis1242feet.Thiswaterelevationwillbeusedtocompute
themaximumsurchargeloading.TheCCRrulePreamblenotesthatthisloadingconditionshould
considertheconditiontooccurlongenoughforsteady‐stateseepageconditionstooccurwithinthe
embankment;thereforedrained,oreffectivestresssoilpropertieswereusedforthiscase.The
resultsforthiscaseindicatedaminimumfactorofsafetyof1.50,whichisgreaterthantherequired
factorofsafetylistedinTable4‐1(Figure4‐2).
Inadditiontothemaximumsurchargepoolloadingcase,theCCRRulePreamblePartVI
(E)(3)(b)(i)alsoaddressesthepotentialfortherapidorsuddendrawdowncase.Theruleclearly
statesthattheconventionalrapiddrawdowncaseasistypicalforadamstructureisnotapplicable
BLACK & VEATCH | Safety Factor Assessment 4‐2
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 toCCRimpoundments,becauseatnopointwouldaCCRimpoundmentbedrawndownlikeadam.
However,asecondconsiderationforthiscaseisdiscussedspecificallyforimpoundmentsadjacent
toabodyofwater.Theintentofthiscaseisthattheadjacentbodyofwaterexperiencesaflood
conditionandtheexterioroftheCCRimpoundmentisinundatedbytheadjacentbodyofwater.
Whilethisconditionpresentsastabilizingforceontheexterioroftheimpoundment,whenthe
adjacentbodyofwaterreturnstonormalconditions,itmayoccurrapidlyenoughthattheexterior
slopescouldremaininasaturatedcondition.ThisloadingscenarioisnotpossibleattheBASAdue
totheCCRimpoundmentnotbeingadjacenttostreams,pondsorreservoirsthatcanrisetothe
pointthatthedownstreamslopeofthebermisinundated.Therefore,noadditionalcasewas
analyzed.
4.1.3 Seismic Loading Inadditiontoslopestabilityanalysesfortheembankmentsundertheprescribedstatic
loadingconditions,slopestabilityanalyseswerealsoperformedforseismicloadingconditionsas
prescribedintheCCRRule(§257.73(e)).
AsdiscussedintheCCRRulePreamblePartIII(D)(3)(b)(2)theseismicstabilityanalysis
wascompletedbasedonthemethodologiesdescribedinthe2009MineSafetyandHealth
Administration(MSHA)EngineeringandDesignManualforCoalRefuseDisposalFacilities.
FollowingtheMSHA’sguidance,asimplifiedpseudo‐staticprocedurewasapplicablesincethe
impoundmentisnotwithinaseismicimpactzoneandtheembankmentandfoundationdidnot
containmaterialthatwassusceptibletosignificantstrengthlossduringthedesignseismicevent.
Thepseudo‐staticmethodconsidersthepotentialinertialforcesduetogroundaccelerationsduring
anearthquakebytheinclusionofastatichorizontalforceinthelimitequilibriumanalyses.The
statichorizontalforceisdeterminedbasedontheweightoftheslidingmassandthehorizontal
seismiccoefficient(kh)whichistakenasone‐halfofthePGAatthebedrockperHynes‐Griffin&
Franklin(1984).
InaccordancewiththeCCRrule,thePGAvaluewasdeterminedbasedonanearthquake
eventwitha2%probabilityofexceedancein50yearswhichisequivalenttoareturnperiodof
approximately2,475years.TheearthquakeconditionsweredeterminedbasedontheU.S.
GeologicalSurvey(USGS)NationalSeismicHazardMapswhichindicatedPGAof0.084atthe
bedrock.Akhvalueof½*0.084or0.042wasusedtosimulatethehorizontalearthquakeloading
usingpseudo‐staticmethodsinthelimitequilibriumslopestabilityanalysesfortheseismicloading
condition.Theresultsforthiscaseindicatedaminimumfactorofsafetyof2.82,whichisgreater
thantherequiredfactorofsafetylistedinTable4‐1(Figure4‐3).
4.1.4 Soil Liquefaction BasedontheCCRRule,257.73,soilliquefactionanalysisoftheembankmentandfoundation
soilswereevaluatedtodetermineifthesoilsaresusceptibletoliquefactionunderthedesign
earthquake.Liquefactionofsoilstypicallyoccursinloose,saturatedorpartiallysaturatedsoilsthat
undergoalossofstrengthduetothegenerationofporepressuresduringaseismicevent.
BLACK & VEATCH | Safety Factor Assessment 4‐3
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Basedontheboringsfromthe2009B&Vinspectionandevaluationreport,thematerials
includedflyash/bottomashfill,weatheredbedrock,andbedrockcomposedofshaleand
limestone.Thebottomash/flyashfillwascompactedin1to2footliftsduringbermconstruction.
ThismaterialisverydensesiltysandwithN‐valuesgreaterthan50.Thus,thebermisnot
susceptibletoliquefaction.Thebermsitsonweatheredshaleandlimestonethatisnotconsidered
susceptibletoliquefaction.
BLACK & VEATCH | Safety Factor Assessment 4‐4
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 5.0 References Black & Veatch (2009) Bottom Ash Settling Berm Inspection and Engineering Evaluation Report, December 2009. Haley & Aldrich (2016), report on Initial Annual CCR Surface Impoundment PE Inspection Bottom Ash Area 1 Impoundment, File number 41938.006, January 2016. Hynes‐Griffin, Mary E. and Franklin Arley G., (1984), Rationalizing the Seismic Coefficient Method, Department of the Navy, Miscellaneous Paper GL‐84‐13, July 1984. U.S. Environmental Protection Agency (2015), Hazardous Solid Waste Management System; Disposal of Coal Combustion Residuals From Electric Utilities; Federal Register Volume 80, No. 74 40CFR Parts 257 and 261, April 17, 2015., BLACK & VEATCH | References 5‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figures BLACK & VEATCH | Figures F‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 STEP1:
STEP2:
STEP3:
DataGathering
Analysis
Report
 Kick‐off Meeting  Collection/ Review of Existing information  Data gap analysis  Data gathering  Design Soil Properties  Identify Critical Section  Slope Stability  Evaluate analysis results against CCR Rule  Prepare summary report Analysis  Soil Liquefaction Analysis and analysis Figure 1‐1 Safety Factor Assessment Process Outline BLACK & VEATCH | Figures F‐2
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Westar Energy
JEFFREY ENERGY CENTER
BOTTOM ASH SETTLING
AREA
St. Marys, Kansas
Site Location Map
Legend
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Bottom Ash Settling Area
Site Location
Jeffrey Energy Center
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ces: Esri, HERE,
orme, USGS, Intermap,
0 1.75 3.5
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365 730
1,460
2,190
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FIGURE 2-1
Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS,
USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User
Community
File: \\na\data\energy\dept\geo\data\Services\PowerGeneration\192728 - JEC Bottom Ash Ponds\GIS Files\Figure 2-1.mxd
Printed on: Thursday, August 25, 2016
Figure 2‐1 Site Location BLACK & VEATCH | Figures F‐3
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Westar Energy
JEFFREY ENERGY CENTER
BOTTOM ASH SETTLING
AREA
St. Marys, Kansas
Subsurface Investigation
@
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BVS-03
MW-BAA-1
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Previous Soil
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>
BVS-02
2016 Bulk
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> B-3
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| Section 1
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B-1
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orme, USGS, Intermap,
0 1.75 3.5
7
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@
A
0 90 180
360
540
720
900
1,080 1,260
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MW-BAA-5
FIGURE 2-2
Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS,
USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User
Community
File: \\na\data\energy\dept\geo\data\Services\PowerGeneration\192728 - JEC Bottom Ash Ponds\GIS Files\Figure 2-2.mxd
Printed on: Thursday, August 25, 2016
Figure 2‐2 Subsurface Investigation BLACK & VEATCH | Figures F‐4
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figure 4‐1 Slope Stability Results – Long‐Term Stability Case BLACK & VEATCH | Figures F‐5
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figure 4‐2 Slope Stability Results – Maximum Surcharge Case BLACK & VEATCH | Figures F‐6
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figure 4‐3 Slope Stability Results – Seismic Case
BLACK & VEATCH | Figures F‐7
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Appendix A 2016 Supplemental Investigation
BLACK & VEATCH | Appendix A A‐1
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figure A‐1 Photo of BVS‐01 Test Pit BLACK & VEATCH | 2016 Supplemental Investigation A‐2
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figure A‐2 Photo of BVS‐02 Test Pit BLACK & VEATCH | 2016 Supplemental Investigation A‐3
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 Figure A‐3 Photo of BVS‐03 Test Pit BLACK & VEATCH | 2016 Supplemental Investigation A‐4
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT BLACK & VEATCH | 2016 Supplemental Investigation REVISION 0 A‐5
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT BLACK & VEATCH | 2016 Supplemental Investigation REVISION 0 A‐6
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 BLACK & VEATCH | 2016 Supplemental Investigation A‐7
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 BLACK & VEATCH | 2016 Supplemental Investigation A‐8
Westar Energy, Inc. | INITIAL SAFETY FACTOR ASSESSMENT REPORT REVISION 0 BLACK & VEATCH | 2016 Supplemental Investigation A‐9