ML18031A306

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Forwards Response to 791029 Request for Addl Info to Complete Environ Review of Low Flow Augmentation Reservoir. Preliminary List of Approvals,Permits & Licenses Required to Const & Operate Pond Hill Reservoir Encl
ML18031A306
Person / Time
Site: Susquehanna  Talen Energy icon.png
Issue date: 11/13/1979
From: CURTIS N W
PENNSYLVANIA POWER & LIGHT CO.
To: SELLS D E
Office of Nuclear Reactor Regulation
References
PLA-421, NUDOCS 7911200521
Download: ML18031A306 (44)


Text

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SUBJECT:

For>erasresoonseto19L029requestforaaalinfotoco+ateteenvironrev>ewoflai0fIoaugmentat ionreservoir~Preliminary listofaoorovalsppermits Klicensesreouireatoconst4ooeratePonawillreservoir encl'10THI80TI04 000':600IIICUPIEEPECEIvE0:LTH

)EwCI.gEIIE:~lITLE:POLAR/FsAKAvoTsannReIatec)corresoonaence vuTEE:~gEtlAcrIU~:RECIP[E.'4rIOCDE)h/NAT)E nePi~P,L,KSC.Hate+aCOPIESL.rrkEVCLL110~EC[p[E)r[OCUI)E/4A'aEAl:~DOC5LAt084~COVLESLTTRElVCL00['~TERNAL:0REr[Lh,Ooc09GEOSC[EIV dR11<EcrlENGdH13MATLc,'4GdHANALYSISUR18AUXSYSHK20I8,CSYSBH22'AOSITETECr)27EFFLTRTSYS29KIRKhuuDADPLATVTSYSADS[rEAVLYSISHYPkOHETEUKBHi3ELDEXTERNAL:

05LPOR50ACRS1144112211L11110111101021011101002<'RCPOH05UVERALICBH10QAdsTRucE.vGBRLSREACSYSBTcLTCOREFERFBfc19CUVTA[uSYS21Pd'hERSYSBR2bACCDIVTAiuLYS28RAGASIArdRAOiOKci)6AoHEACsAFE,rYD[RE,Ct'URT~HiiYiPA04VSIC1111L1.11111111L11110L001011gggg$979L.gpRJ4uR+3~BCpm'3-LRruTALNu).BEKoFCU)lesRE"u[RED:

LTTR,~E,,uCL40 TWONORTHNINTHSTREET,ALLEN1'OWN, PA.18101PHONE:{215)8215151NORMANW.CURTISvicePrescentEngineering 8Construction 821.5381SOV13tS7OMr.DonaldE.Sells,ActingBranchChiefEnvironmental ProjectsBranchU.S.NuclearRegulatory CommissonDivisionofSiteSafety8Environmental AnalysisWashington, DC205SSSUSQUEHANNA SESPONDHILLRESERVOIR INFORMATION ER100450FILE991-2PLA-421DOCKETNOS.50<<387AND50-388

DearMr.Sells:

Theinformation requested inyourletterofOctober29,1979iscontained onAttachment l.Apreliminary listofapprovals, permitsand/orlicensesrequiredtoconstruct andoperatethePondHillReservoir isincludedonAttachment 2.Ifyouhaveadditional questions, pleasecontactittilliam Barberich (215-821-5833).

Verytrulyyours,N.N.CurtisCopyto:Mr.PaulLeech(4copies)ilStopP522U.S.NuclearRegulatory Commission Dr.JamesCarson(5copies)BuildingIlaDivisionofEnvironmental ImpactStudiesArgonneNationalLaboratory Argonne,IL60439PENNSYLVANIA POWERILLIGHTCOMPANYTgt,>SO~<RI 3~/C=5rrri Attachment 1Additional Information Requested forEnvironmental ReviewoftheLow-FlowAugmentation Reservoir forSusquehanna SteamElectricStationDocketNos.50-387and50-388HdroloicEnineerin1.Provideadescription oftheone-percent chancefloodplain ofPondHillCreekbefore,during,andaftertheconstruction ofthereservoir.

Includefloodinundation mapsforallconditions.

Providedetailsofyourmethodsofanalyses.

Includeyourassumptions ofandbasisforpertinent parameters suchaslengthandslopeofdrainage.

basins,timesofconcentration, infiltration rates,rainfallamountsanddistribution, Manning's "n"values,andanyotherassumptions orparameters usedinthedeterminations ofthefloodplains.

Discussthealterations ofthefloodplain, including thereachesdownstream ofthereservoir, thatwillresultfromtheproject.RESPONSE:

Theattachedexcerptsfromhydrological studiesforPondHillReservoir detailthederivation offloodhydrographs forPondHillCreekforconditions bothbeforeandafterconstruction inthecasesofProbableMaximum,100,50and25yearfloods.Reservoir floodroutingsforthePMFand100yearfloods(figures859)arealsoattached.

Afloodinnundation mapshowingtheapproximate areawhichwouldbefloodedduringa100yearfloodbeforeconstruction ofthedamisattached.

Duringconstruction, floodflowswillbecontrolled byacofferdamanddiversion releaseswillbecontrolled tominimizedownstream flooding.

Aftertheprojectiscomplete, thereservoir discharge will-beapproximately 30cfswhichwillbepassedbytheexistingchannel.Becausetheexistingchannelwillpassthepeakdischarges forboththeduringandafterconstruction conditions, noinnundation mapshavebeenpreparedfortheseconditions.

Inpreparing thefloodinnundation map,floodflowswereassumednottoincreasedownstream ofthedam.AManning"n"valueof0.05wasassumedandachannelslope,basedonprojectmaps,rangingfrom3to10percentwasused.Noalteration ofthefloodplaindownstream ofthedamisproaosed.

2.Provideadescription, including afloodinundation map,oftheonepercentchancefloodplain oftheSusquehanna Riverinthevicinityofthepumpingplant.Providedescriptions oftherelationship ofallstructures andconstruction activities tothefloodplain.

Includemapsanddrawings.

RESPONSE

The100yearfloodplain foradistanceofinexcessof3000feetupstreamandapproximately 10,000feetdownstream islargelyundeveloped ontheeastsideoftheriverwithexception ofseveralisolatedhouseswhichmaybeinthefloodplain.

Thefloodplain isapproximately boundedontheeastbytheDelawareandHudsonRailroad.

Thewestbankoftheriverwithinthesamelimitsalsocontainslittledevelopment.

FloodprofilesandfloodboundaryandfloodwaymapsforConyngham

Township, LuzerneCountyinthevicinityofthepumoingplantareattached.

TheyaretakenfromtheAugust1976FloodInsurance StudyforConyngham Township(U.S.Department ofHousingandUrbanDevelopment).

Basedonthisdata,the100yearfloodplainelevation isapproximately El.519atthepumpingplant.Theonlystructure proposedforconstruction inthefloodplain isthepumpingplant.Theproposedandtheapproximate extentofitsconstruction inthefloodplain isshownonplateS(attached)

.

Foranystructures chancefloodplain, floodplain's floodanalyses.

Discussyourbasisforanyfloodplain arenotorconstruction activities ontheone-percent providedescriptions oftheireffectsonthehandlingcapability.

Includedetailsofyouralternate locations offthefloodplain andprovideconclusions thatalternate locations offthepracticable.

RESPONSE

Theproposedpumpingplantwouldbetheonlystructure intheSusquehanna Riverfloodplain.

Thisstructure willbelocatedapproximately atrivercrosssectionJasshownontheFloodProfilesandFloodBoundaryandFloodwaymaps(attached)

.FloodwaydataforthiscrosssectionfromtheFloodInsurance Studyisalsoattached.

BasedontheproposedpumpstationshowninPlate8,approximately 600squarefeetofthestructure wouldencroachonthefloodplain.

Becauseofthesteepslopeontheeastbankoftheriverat'thispointitisassumedthatthisentirewidthislocatedinthefloodwayasdefinedintheFloodInsurance Study.Ifitisconservatively assumedthatnofloodwayfringeexistsonthewestbank,anduniformvelocitydistribution acrossthecrosssectionoccurs,thedepthofthe100yearfloodatthepumpstationisnotexpectedtoincreasemorthan0.6'600SF/948ft.floodwaywidth)duetoconstruction ofthepumpstation.Itisexpectedthatthisincreaseinriverstagewouldnotextendveryfarupstreamduetotherelatively steepfloodprofileinthisarea.Becauseoftheterraininthevicinityofthesite,thereisnolocationoutsidethefloodplain whereapumpingplantcouldbeconstructed withoutalteringthewaterconduitconceptorrelocating familiesresidinginexistingdwellings.

Thefloodplain extendstoapproximately theDelaware5HudsonRailroadtracksandarockcliffadjoinsRoute239totheeastinalllocations whicharenotdeveloped, limitingtheareaavailable forpumpstationconstruction.

4.Provideadiscussion ofthegroundwater conditions atthereservoir sitepriortoconstruction.

Includeamapshowinggroundwater contoursandlocatingallnearbywells.RESPONSE:

Amapshowinggroundwaterelevations atcompleted coreboringsatthedamsiteandaseparatemapshowingnearbywellswheregroundwaterelevations havebeenmeasuredisattached.

Althoughnotlocated,mosthousesshownonthemaphaveindividual wells.Therearenowellswithintheproposedprojectboundary, andnearbywellarelocatedinsidethePondHillCreekdrainagebasin.Artesianpressurehasbeenobservedatseveraloftheboringsonthesouthabutment.

Duetoalackofsufficient data,nogroundwater contourplanthasbeenprepared, however,groundwater contoursappeartofollowsurfacecontoursintheimmediate reservoir area.

5.Provideananalysistojustifyyourconclusion onpage4-4thatgroundwater alterations thatwillresultfromthecreationofthereservoir willbeconfinedtothebuffer"oneownedbyPPP<L.Includeamapshowinggroundwater contoursexpectedafterthereservoir isfilledandequilibrium isreached.RESPONSE:

Theconclusion onpage4-4isbasedonthesitegeology.Underlying rockformations didabout45'othenorthintothereservoir.

Theonlymajorfractures arealongthebeddingplanes.Rockqualitybecomesverygoodbelowaweathered

-oneofabout10feet.Permeability testsindicatethatatabout90'epththerocktightensabruptly, andtheonlysignificant seepageisthroughthejointsintherock.Asthesejointsdipintothereservoir, significant seepageawayfromthereservoir isnotexpected.

Becausethenaturalgroundwater pathisintothereservoir, andbecause,basedonobservations todate,thegroundwater appearstogenerally followthesurfacecontoursandagroundwater dividehasbeenobservednearorabovethemaximumwaterstorageelevation onthesouthabutment, itisnotexpectedthatthegroundwater outsidethePondHillCreekBasinwillbeeffected.

PP5Lproposestoacquirealmostallthelandwithinthebasin.Becauseofalackofsufficient basedata,nogroundwater contourplanhasbeenprepared.

6.Provideinformation onallpresentusesofPondHillCreek.Iftherearenone,sostate.RESPONSE:

Ourinvestigations haved'isclosed nopresentusesofPondHillCreek.

7.Justifythechoiceof0.2cfsfortheconservation releasetoPondHillCreekduringperiodsofdrawdownorrefilling ofthereservoir.

RESPONSE

ThePennsylvania Department ofEnvironmental Resources (DER)inthepermitting processnormallyincludesasoneoftheconditions therequirement thatallnewreservoirs provideaminimumreleasetomaintaindownstream flows.Theminimumreleaserequirement isusuallytheaverageflowoverasevendaylowflowperiodwithareturninterimoftenyears(Q7-10).Intheabsenceofanystreamflowdata,avalueof0.15cfspersquaremileofstreamdrainageareaisnormallyutilizedbyDER.The0.15cfspersquaremilemultiplied bythedrainageareaatthedam(1.3squaremiles)isthebasisfortheproposedminimumflowof0.2cfs.RPN$979:5 ATTACHMENT 2Preliminary ListofApprovals, PermitsorLicensesNeededforPondHillReservoir Federall.Intake5Discharge Structure, WaterWithdrawal--U.S.

ArmyCorpsofEngineers (ACE)2.DredgingPermit--ACE State1.LimitedPowerPermit-Department ofEnvironmental Resources (DER)2.Intake5Discharge Permit--DER 3.ErosionandSedimentation ControlPlan--DER 4.NPDESDischarge Permit--DER S.Roadcrossings forpipeline, distribution lines,etc.--PADepartment ofTransportation Interstate Pro'ectAroyal1.SRBC-WaterUsePermit PONDBILLRESERVOIR APPENDXXAHYDROLOGY nitDu~r-APPE.'i'DZ.C AHYDROLOGY TABLEOPCO'.1TH:ITS Derivation ofFloodHydrograahs UnitHydrograghs ProbableMaximumRainfallProbablemaximumPloodNaturalConditions Reservoir Conditions 100-.Year Plood50-YearFlood25-YearFloodRecurrent FloodOperation Studyfor1964DroughtAccumulation ofSediments Pa<acA-1A-2A-6A-7A-10 HYDROLOGY ZZST.OPPXGURESPiureNo.ProbableMaximumFloodHydroqragh, NaturalConditions ProbableMaximumFloodXnflo~Hydrogragh, Reservoir Conditions 100-YearFlood,NaturalConditions 100-YearFlood,Reservoir Conditions 50-.YearFlood,NaturalConditions 50~YearFlood,Reservoir Conditions 25=YearPlood,NaturalConditions Recurrent FloodA-6A-8

~<<~~J<<V>>>>'Ji<<<<w~<<Ãiv~~~gr<<~t<<<<~.<<<<r<<<<<<~rive'ni4(1@a~JQ<<oc444l~>><<lie>>0talc.~v1'vi>>i+i'~>>vv>><<>>a~wc<<esa<aceC,i>><<V<<I<<~4>>ancusis<<aevarua>>cna~ac<<uo'ormal watersu"plyLevelaf981.Inclucied a:(1)cier'va"ionoffloodhydragraphs fostormsofvariousfrecuencies; (2)detailsofthereservoir ogera"ion stciyfortne1964"raugnŽperiod,and(3)estimates ofturesec'=ntaccu.=uLat'".".thereservoir.

Derivation ofFloodHydroraahsThepurposeofthispartoftheAppend'xistopse..ttheestimates offloodmagnitudes tobeexpectedatcnePondHillsiteunciernaturalconditions andaftercanstuc"ionaftheproposedreservair..

Computations naveaeenmadefortheprobablemaximumflood(PNP),whichisthedes'gnoasisfordamstability ancispillwaycapacityaalculations andfarfloodstobeexpectedatrecurrence intervals of100,50,and25years.Asthereisnastream-flow measurement stationatthePandHillsite,itwasnecessary toderivethevariousflaodhydrographs fromsynthetic unithydrogiagns ancidesignstormrainfalls.

Ztisbelievedbasedonstudiesoffloodmagnitudes intheregionthatthederivedfloodmagnitudes areconserva-tive.Asthereservoir surfaceareawillbeeauivalent taabout39percentofthetotalcontributing area,itwill"epossibletoobtainahighdegreeofsurcharge storagefamodification ofinflowfloods.Becauseofthisconc'tion,

".".evolumeaftheinflowfloodwillbemoreimportant thanthepea<discharge indetermining

<<load.madificationbythereser;.oir.Althoughthereservoir hasahighpotential for:-ad'ation ofin~lawfloods,itsexistence changstrecharac=r'=--ticsofthetotalinrlowhycirograph, particular'y t'"i==arconcentration ofthecomponent areas.Thestorm.rainfallonone 4serOIQ~faffp8+p<<fspn1<<offth/<<QQ+

If.lp~C<<OI~C0Ln<<<<wgirv-~ivi<<s<<i.a<<<<4~~Ieauk3aIso<<ra4n<<<<~~~cwaterarea-i.s"er"eiveda:.-,.ost i..".sta.".=anec s;.ata<<<<<<timingoftheruroifrom'tnelandareas(theotherco.ponen)isalsochangedbytheexistencofthe~atrara.Toevalua"ethislattereffect,i"wasnecessary todividethelandareaintotwosub-components whichdischar"e dirct'yintothe<<arearea'nstead offollowing theorigina'tream ne"cworkasundernaturalconditions.

Znsomeinstances, alargesurcharge storagevolumecouldleadtotheselec"ionofaspillwaycapacitywhichmightbetoosmallshouldasubsequent floodoccurbeforethesurcharge storagefromapreceding floodhadbeendepleted.

Topreventthis,arecurrent floodwhichisassuagedtooccurtwodaysafterthepeakfloodlevelresulting fromtheprobablemaximumfloodisgenerally usedtotesttheadequacyofthe.proposeddesign.Therecurrent floodisalsoderivedherein.Unit2droaranhs Asstatedaboveitwasnecessary toestablish therunoffcharacteristics ofthetotalnaturaldrainageareaabovethedamsite,andofthetwocomponent areascontributing tothereservoir, byderivingsynthetic unithydrographs.

Toobtainthenecessary characteristics oftheunit.hydro-graphssuchaspeakdischarge, lagtimeandlengthofbase,theprocedure fortriangular hydrograph analysisproposedbytheU.S.BureauofReclamation (USBR)-wasfollowed.

Unit1/hydrographs compiledbytheSusquehanna RiverBasinStudyCoordinatingCommittee-ortheSusquehanna River"asinl~"DesignofSmallDams",.BureauofReclamation, U.S.Oepart-mentoftheEnterior, 2ndEdition,1973.2I"Susquehanna RverBasinStudy-AppendixD,Hycro'g'",Susquehanna RiverBasinStudyCoordinat'ng Commi"tee, June,1970.A;2

~~sellaht~owvaaaakLec aQaa,v4n&sdnUQJng0IVaL51QasI~~Asstudiesccnatinc'uaeanysmalldrainaceareaa.=the5unaerconsideratian (1.2Is=.;..'.)

i"wasdeciaectauserneUSBRprocedure wnichallowstheuseofemg.irical datacompiledbytheSoilConservation Serviceforverymalldrainagearas.Thestudyofdesignhydrographs ayJ.E.AcSgaran-farPennsylvania Natersneds, whichincludedonedr'ainage areacP.2.4squaremiles,supgortstheuseoftheadoptedprocedure.

Thetimeframthestartoftheunithydrogragh toitspeak(tinhours)isexpressed asfolLows:D+0.6T2where:D~Durationofexcessrainfallinhours;T~Timeofconcentration inhourscofthewatershed definedasthetraveltimeofwaterframthemostdistantpointofthewater-shedtothegointofinterest.

Theterm'.6Tisanempirical relationship developed bytheSoilConservation Servicetorepresent thelagtime,whichisdefinedasthetimeinhoursfromthe'idpoint afexcessrainfall, D,tothetimeofpeakdischarge.

Therelationdeveloped forthepeakdischarge (qP)oftheunithydrograpn incubicfeetpersecondpersquaremileisasfollows:Pp3~"Delaware RiverBasinEngineers

,l960."DesignHydrog"'..".sNcSparran, Proce=.'-'ng Report,Vol.VX,AppendixM,CorpsoforPennsylvania Hatersheds",Z.:-.ofASCE,Vol94,HoBY4,Julv196S.A3 Thetimebaseoftneunithydroccaph (tb,in-hours)isminedfromtneempi-'cal

-e:ations.".i" s-L.67anato+ttowhere:tristherecession timeinhoursfromthepeaktotheendofthefloodhydrograpn.

Thepeakofthe1-hourunithydrograph forthe1.27squaremilesofnaturalareabasedontheaboverelationships is683cfsor538cfspersquaremile.Thepeakofthecombinedhydro-graphofthetwoareascontributing tothereservoir (totalareaof0.78squaremiLes)is559cfs.Asummaryoftheunithydrograph characteristics

.forbothconditions foLLows:Unit8drooraohCharacteristics

~WithReservoir WithoutReservoir DrainageArea-sq.mi.DhoursTchourstphourstbhoursPeakDischarge cfs0.781.00.360.72~20559l.27100.92~4683ProbableMaximumRainfallAsthedrainageareaabovethePondHilldamisLessthanLQsquaremiles,computedvalues.forpointrainfalLcanbeap-pliedtothetotalareaorsubareas.

Furthermore, atotalstormdurationof6hoursisconsidered

adequate, asincrements ora~fall'or Longerdurations wouldnotbesignificant insiz-ingofthespillway.

A6-hourdepthof25incheswasoreviously recommended fortheareaofinterest.-

K,aterstudiesby5/5iT.chnical PaperMo.40,Q.S.WeatherBureau,Hay'96L.A-4 theCorpsof=ng'neers rcommended "hatvalesor'ess".'".an'0squaremiesbereduced'"'0pecentinorertopcvce=ortneimperec"zt"ostor..isohyet'a"=ensto".".s'".peofa.particular basin.The.assumeddistibutionandarrangement ofthedesignrainfallwithinthe6-hourperiodisgivenbelow.Thedistribution isasrecommended inthe"DesignorSmallDams."Thearrangement wassettoootainaconservative floodpeak.Hour123456Depth(inches)229.83-21.61.620.0ProbableNaximumFloodNaturalConditions

~Theprobablemaximumrainfallwasappliedtotheunithydrograph forthePondHillReservoir drainageareaundernaturalconditions andthecomputations areshownonFigureA-1.Thepeakdischarge is7,120cfs(5,600cfs/sq.mi.).Reservoir Conditions Theprobablemaximumrainfallwasappliedtothecombinedunitgraphforthe0.78squaremilelandareacontri-butingtothereservoir andtothe0.49squaremilewaterarea.Thepeakinflowfromthecombinedlandandwaterareais8,755cfs(6,892.cfs/sqmi.).Thepeakdischarge fromthewaterareais36percentofthetotalpeakdischarge whichisinturn1.23timesthepeakdischarge fromthenaturalareaandoccurs0.40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br />sooner.hus,"he-porcancofevaluate.'.".g floodsofc"aigrelat've'y large<<aearease~cs~~~L,.c'acaoThe.compgtat'northes"-'~waycesign=1"ocinlowundec..reservoir conditions.

isshown'nFigureA-2.100-YearFloodThefloodwitharecurrence intervaLofoncein100yearswasestimated from.the6-hourrainfallfrequency datagiveninTechnical Paper40.Thetotal6-'hourdepthfortheregionofthereservoir was5.0inches.Theassumeddistribution ofrainfaLLwithintheperiodisasfolLows:Hour1235Depth~inches)0.30~0.702.500.650500.3S5.00Aninfiltration Lossof0.1inchesperhourwasassumedforthestormperiod,givinganettotalrainfallexcessof4.4inches.Application ofthedesignstormtotheunithydrograph resultsinapeakdischarge ofL,756cfsundernaturalcondi-tionsandwiththereservoir thepeakdischarge is2,148cfs.Thecomputations areshowninFiguresA-3and.A-450-YearFloodThefloodwitharecurrence intervalofoncein50-yearswascomputedasexplained aboveforthe100>>yearflood.T.".erainfallis4.3.inches,andwouldbedistributed asfollows:A-6 Sour123456Dept."a(neos)0.300;572.150.600.420.264.30Usinganinfiltration lossof0.1inchperhour,andapplyingthedesignstormtotheappropriate unithydrographs, resultedinapeakdischarge of1,490cfsundernaturalcondi-tions,and1,832cfswiththereservoir.

Thecompletecomputa-tionsareshowninFiguresA-5andA-6.25-YearFloodThefloodwitharecurrence intervalofoncein25yearswithoutthereservoir wascomputed'sexplained aboveforthe100-yearflood.Thetotaldepthforthe25-year6-hourrain-fallis4.0inches,distributed asfollows:Hour234.56Depth~inchaS0.240.562.000.520.400.264.00Usinganinfiltration Lossof01inchperhour,andapplyingtheresulting designstormtotheunithydragraph ornaturalconditions resultedinapeak.discharge of1,387cfs.Thecompletehydrograph isshownanFigureA-7.A7 Recurrent

":LoodThecapacityofthePondHillReservoir spillwaywastestedbyroutingarecurrentfloodbeginning two..daysafterthepeakoutflowproducedbytheprobablemaximumflood.Therecurrent floodwas'computed fromtheunithydrographandatotalrainfallthatisapproximately equaltotherecordrainfallfortheregion.Thetotalrainfalloftherecurrent stormwasestimated basedonafactorthatrelatestherainfallofrecordtothatoftheprobablemaximumstorm.Aspublished inthe'DesignofSmallDams,"thefactorforthisregionis2.2.Theresulting rainfallof9.1incheswasdistributed asfollows:Hour123456Depth~inches0.734'6146.0.730.729.10ITherecurrent stormrainfallwasappliedtotheunithy-drographforthePondBillReservoir drainageareaconsideingafullreservoir.

Thecomputations

'areshowninFigureA-8.

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