Gravity Flow Water Systems重力流供水排水系统 31

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GravityFlowWaterSystems重力流供水排水系统3

WATER-c5-1.6.Thefoundation,walls,covering,andalljoint6shouldbewa.tertight.1.7.ThereshouldbenotreesorvegetationwhoserOOt6mayeventuallyenteranddisturbthesourceprotection.However,anyexistinglargetreesshouldbeleftundisturbedsoa6nottodisturbthesource.1.8.Theoutflowconduitfromthecapteringshouldbelargeenoughandofsufficientslopetoaccommodatethemaximumanticipatedflow.1.9.Arrangementshouldbemadefordiversionanddrainageofanysurfacewater.1.10.Ifitispossibletostoptheflowofwaterinthecollectingpipethentheremustbeprovisionforanoverflowofsufficientsize.1.11.Ifthereisanoverflowpipethenitmustbeofsufficientdiameteranditmusthaveastrainer.Theopenareaofthestrainershouldbe2-3timesthe~066sectionalareaoftheoverflowpipe.Openingsinthestrainershouldbesmallenoughtoprevententryofsmallanimals.Theofftakeinawaterchamberorreservoirshouldalsohaveastrainer.1.72.Ifthereisanoverflowthentheremustbesuitablearrangementsfordrainageofanyexcesswater.1.13.Ifwaterfromthecapteringischannelledtoawaterchamberorsto-ragereservoirthentheoverflowofthechamber/reservoirmustbeatalowerlevelthantheinflowfromthecaptering.1.14.Thedateofconstructionshouldbeengravedsomewhereonthestruc-tureandanyburiedstructuresshouldbeidentifiedbyasmallcon-cretemarker.1.15.Insofaraspossiblethesourceshouldbeprotectedfromanydis-turbance.Fencingisrecommendedforadistanceof10metersinthefrontof,IOmetersoneitherside,and50meterstotherearofthesource.Protectionsnd/orreforestationofthecatchmentareashouldbestronglyencouraged.1.16.Ifpossible,arrangementsshouldbemadesothattheyieldofthesourcecanbeeasilymeasured.-c6-2.REXRVOIRCONSTHUCTION2.1.Reservoirsprovidestoragetooffsetfluctuatingdemandandlowsourceflows.Pheymayimprovewaterqualitythroughsedimenta-tioniftheyallowforsomeretentiontime.Theycansoservetobreakpressureinthesystem.Importantconsiderations.intheirconstructionarelistedbelow.2.2.Thereshouldbeacleanoutpipeineachcompartmentofthereservoir.Thecleanoutshouldbeplacedatthelowestpoint,aandthefloorofthereservoirshouldslopetoward6it.Itisnotnecessarytohaveanexpensivevalvetocontrolthis.iisimpleplugissufficient.2.3.Joiningsofthewallandfloorshouldbeslightlyroundedtofaci-litatecleaning.2.4.*nyofftakesshouldbe5to20centimetersabovethereservoirfloor.Thelargerthereservoir,thehigherthelevel.Theleveloftheofftakeswithrespecttothegroundwilldependontheusageofthereservoir.2.5.Theleveloftheinletpipeshouldbeapproximately10to20cmbelowthecoverofthereservoir.Insmallerreservoirs(generallythosewithaninflowpipeof1I1diameterorless)theinletshouldbefittedwithafloatvalvesothattheflowisstoppedwhenthereservoirisfull.Thefloatshouldbeplacedsothattheflowisstoppedbeforethewaterlevelreachestheleveloftheinletpipe.Ifthefloatvalveisnotinstalledthen=elbowshouldheusedtodirecttheflowdownwards.Inlargerreservoirsanelboworbafflearerequiredtoreduceturbulence.2.6.Theinletpipeshouldbefittedwithaglobevalvetocontroltheinflow.Thevalveshouldbeprotectedfrompossibletampering.2.7.Theoverflowshouldbeplacedataslightlyhigherlevelthantheinflowsothatitwillcomeintoplayonlyifthefloatvalvemal-functions.Theoverflovalsoservesasanairventilationpipe.2.8.Theoverflowpipediametershouldbelargeenoughtoaccommodatethemaximumexpectedflow.Itisnormallylargerthantheinflowpipeb6C6U66theinflowisunderpressure.Forexample,aninflowpipeofSttdiametermightrequireanoverflowof1%diameter.-c?-2.9.Theoverfl\wandofftakestoservethedistributionpipeshouldbescreened.Theopenareaofthescreenshouldbe2to3timesthecro66sectionalareaofthepipetowhichitisattached.Forexample,aI?Wpipehasacro66eJectionaareaof1.23inches2.Ifthescreenismadebydrillinghole6inPVCwithaJbitthaneachholeisapproximately0.5inches2andatleast50to75holesshouldbedrilled.2.10.Thereshouldbeamanholeonthereservoirwhichisjustlargeenoughforamantoenter.Thedesignofthecovershouldbesuchthatrain-watercannotenterthereservoir.Aconcretemanholecoverwitharemovableironhandleisrecommended.2.11.Thefloatvalveandoverflowpipeshouldbecloseenoughtotheman-holesothattheymaybeinspectedandservicedwithouthavingtoenterthereservoir.heyshouldnotinterferewithenteringthereservoir.2.12.ThetopofthereservoirshouldbeslopedsothatrainwaterdoesnotCollectonit.2.13.Thereshouldbeprovisionforproperdrainageofanywastewateroroverflow.Theslopeshouldbeatleastaanditshouldbedirectedtoasoakagepit,pondorflowingditch.Anopen,concretelined,drain10xIOcmispreferable.Properdrainageofwastewaterisunfortunatelytotallyneglectedinpracticeeventhoughitiscriticaltoachievingdesiredhealthbenefits.Infact-poordrainagemaycreatemorehealthproblemsthantheprovisionofcleanwateralleviates.2.14.Reservoir6largerthan80m3shouldbedividedintotwocompartmentsandprovisionmadesothattheinflowcanbedirectedtoeithercompartment.Thereshouldbeaseparateofftakeforeachcompartment.Thueeachcompartmentcanbeseparatelycleanedwithoutinteruptingtheflovinthesystem.2.15.Reservoirsgreaterthanabout40m3shouldhavebuiltinironrungstepsontheoutsidetofacilitateaccesstothetop.2.16.Anyexposedironorpipesshouldbepainted.2.17.Thedateofconstructionshouldbeengravedsomewhereontheconcreteforfuturereference.2.lh.Incalculatingreservoirvolumetheeffectivedepthisfromtheofftaketothehighestlevelthewatercanreach.3.PIPELINE3.1.Thechoiceofpipematerialdependsonphysical,technic61,andcul-turalfactors.althoughitispresentlymoreexpensivegalvanizedironispreferredforuseinIndonesia.Thisisprimarilytopreventunauthorizedtappingintothesystem.Itisalsofrequentlynotpossibletoburythepipeandironpipemustbeusedintheseareas.3.2.Thepipelinemusthaveairreleasevalvesatallhighpoints.Anyairpresentinthewaterwilltendtocollectathighpointsandblockorreducetheflowofwater.3.3.Thepipelinemusthavewashoutvalvesatalllowpoints.3.4.Unionjointsingalvanizedironpipeshouldbeinstalledatminimumevery120metersandneareveryfitting.Inroughterraintheyshouldbeinstalledatleastevery50meters.3.5.PVCpipemustbeburiedatleast50cmbelovthenaturalgroundlevel.--3.6.AllGIpipeinstalledabovegroundshouldbesecuredandanchoredwithconcretepillarsatsuitableintervals.Theinstallationofpipeabovegroundhasseveraladvantages:itisnotpossibletolosettthepipelineseveralyearsafterinstallation:itmaylastlongerduetoreducedcorrosion:andtrenchingisnotnecessary.Thedisadvantagesare:itismoresubjecttotamperingandcertainkindsofstress:andexpensiveconcretepillarsarerequiredforsupport.-Dl-APPENDIXDSTEPSINSURVEYANDDESIGNI.ThefieldSurvey1.2.3.Surveythesourceandthevillage;initiatecontactwiththecornmu-nity.bromsurveyresultsdecideonthefeasibilityofconstructingthewatersystem.Forsystemsconsideredfeasibleadetailedsurveyofthesource,distance,andgroundlevelsismade.Jomeonefromthevillageshouldassistinthis.Atthistimetentativelocationsfordistributionpoihtsaredecideduponinconsultationwiththevillagers,takingintoaccounttheirownwishes,populationdistributionetc.II.TheDesignProcessThesurveydatai5usedtomakepreliminarydesignroughlyasfollows:I.Decideongeneralsystemdesign,typeofdistributionfacilities,etc.2.Decideofhowmuchofthepopulationcanbeservedbythesystem.aecideonpercapitausageandcalculatetheaveragedailyusageta-kingintoaccountpopulationgrowth.J.;romthetypeofsystemandaveragedailyusagedeterminethedesiredstorageanditsplacement.‘theplacementofthedistributionpointsmustbefixedatthistime.4.JromtheplacementofthedistributionpointsmakeageneralBketchofthesystemincludingallrelevantdistancesandelevations.Basedonthepopulationdistributiontheaveragedailyflowsrequiredateachpointcanbecalculatedandnotedonthesketch.5.‘rOmtheaveragedailyflowsandthetypeofsystemthedesignflowsforthepipearecalculated.6.‘ramtheelevationprofileandgeneralschemeofthesystemtheneedandplacementof-breakpressuretanksisdetermined.andrecordedonthegeneralsketch.7.i’rt%athedesignflow6andelevationstheheadlossesforvariousdi-ameterpipesarecalculatedforeachunbrokensectionofthepipeline.8.Themostappropriatepipeischosenforallsectionsofthepipelinebasedonthecalculatedheadlosses.Thehydraulicgradientsarethenplottedontheprofile.Pipediametersshouldbechargedwherenece-ssaryinordertoeliminateanynegativepressure.9.Detaileddrawings,specifications,materialslistsandbudgetscannowbeprepared.,-El-APPENDIXESAMPLEDESIGNFORDESAGEMBIRA1.General1.1.ThevillageofDesaGembirahasapopulationof850dividedintotwokampongs,GembiraIwith605personsandGembiraIIwith245persons.Awatersourcewithanestimatedminimumflowof1l/sislocatedapproximately2,300metersfromthevillage.AsketchmapofthevillageandagroundprofilearepresentedinFiguresEltoE4.2.DesignParameters2.1.PopulationThedesignpopulationwillbetheexpectedpopulationin10year5ata2%growthrateor850x1.22equalto1,037persons.Fordesignpurposesthismsyberoundedupto1,050persons.2.2.WaterUsageItispreferabletosupplythemaximumamountofwaterpossiblebutapercapitasupplyof100litersperdaywouldrequire105,000liters/dayoraflowof1.2l/s.asincetheestimatedminimumflowofthesourceisonly1l/sthisisnotpossible.Apercapitauseof80liters/daywouldrequireanaveragedailyflowof0.97l/sandthisispossible.2.3.StorageRequirement6Apercapitauseof80liters/daymeansthattheaveragedailyusageisa0x1,050or84,000liters.Inordertoreducethesizeofthemainpipestoragewillbelocatedinthevillage.Therecommendedstorageisthenonehalfof84,000litersor42m3.Basedonthepresentpopulationdistribution245+a50x42m3or12.1m3shouldbeinGembiraIIand6058850x42m3or29.9m3shouldbeinGem-biraI.Basedonthevillagesketchithasbeendecidedthatthewaterwillbedistributedto5publicreservoirs,threeinGembiraIandtwoinGembiraII.ThethreereservoirsinGembiraIwillhe10m3eachforatotalof30q3(roundedupfrom29.9m3)ThetworeservoirsinGembiraIIwillbe6m3eachforatoralof12m3(roundeddownfrom12.1m3).d!.ththisdietributionofreservoirsnoonehastowalkmorethanICCImeterstoobtainwater.2.4.NumberofFaucet5Thenumberofpersonsperfaucetshouldbebetween30and100sothenumberoffaucet5forGembiraIshouldbebetween6and20RES.CIcslrvI-E3-andfor(GembiraIIbetween2and8.Inordertofacilitateusageahighernumberispreferable.Thus6faucetsateachofthe3reser-voirsinGembiraIand4faucetsateachofthereservoirsinGem-biraIIgiveatotalof26.Theaveragenumberofpersonsperfau-cetis42forGembiraIand37forGembiraII.Halfofthefaucetscanbeplacedononesideofthereservoirandhalfontheoppositeside.Thus,oneareacanbeusedbyfemalesandtheotherbymales.2.5.iesignFlowsThepathofthepipelineissketchedinFigureEl.Thewaterwillflowcontinouslyintothereservoirssothedesignflowswillbethesameastheaver,gedailyflows.Attheprojectedpercapitauseof80l/daytheaveragedailyflowis0.97l/sbutthespringhasanestimatedminimumflowof1.0l/s.Therefore,l.ol/scanalsobeusedindesigningthepipeline.FromthesourcetothejunctionatpointAthedesignflowusedis1.0l/s.AtpointAthisflowisdividedwith0.71l/sflowingtoGembiraIandreservoirB.Theremainderof0.29l/swillflowtoGembiraIIandreservoirE.AtreservoirB0.23l/sistakenandtheremainderof0.48l/sflowstoreservoirC.Atc0.24l/sistakenaridtheremainderof0.24l/sflowstoreservoirD.AtreservoirE0.14l/sistakenandtheremainderof0.15l/sflowstoreservoirF.Thedesignflowsarenotedonthepipelinerouteandprofile.3.PipelineDesign3.1,PressureReleaseTanks3.2.InspectionoftheprofilesinFig.E2to!Skindicatedthatapressurereleasetankisnecessary1,300metersfromthesource.‘Thestaticheadatthispointis55meters.Thepointofgreatestpressureis1,100metersfromthesourcebutitisnotpossibletoplacethetankatthispoint.PipeMaterialGalvanidironpipewillbeusedduetodifficultiesinburyingmanysections.3.3.PipeSizefromSourcetoPressureReleaseTankThedistancetothetankis1,300mandtheavailablehead55mwithadesignflowof1.0l/s.Calculatedheadlossesareasfollows:wi.-94-9siQ-I$--In6I3.4.3.L-E7-lengthfloupipediameterhead1066(meters)(l/s)(inches)(incl.1096extra)(meters)1,3001.0212l.3001.01.5501,3001.0‘1.251’54001.0249001.07.5347001.01.5272001.01.2521Fromthecalculatedheadloesesitappearsthat1.5inchiseuffi-cientbutacheckoftheHGLontheprofileindiaateanegativepressureinthefirst400meters.Thuea2inchpipemustbeusedtoavoidthenegativepressureandtheremainingpipecanbeacom-binationof1.5inchandI.25inchwhichisfoundbytrialanderror.?ith400metersof2inch,700meter6of1.5inchand200metersof1.25inchthetotalcalculatedheadlossi651meters.PressureReleaseTanktoJunctionatPointACalculatedheadlossesarea6follows:lengthflowpipediameter(meters)(l/S)(inches)headloss(incl.IQ%extra)(meters)50l.U25.!m1.01.519501.01.2551Hiththeavailableheadof20metersa1.5inchpipeisappropriate.PointAtoReservoirsB,C,D.Calculatedheadlossesareasfollows:lengthflowpipediameter(meters)(l/s)(inches)headloss(incl.lC$extra)(meters)Availablehead(meters)500.711.510105w0.711.2523105000.712.03102000.481.52102000.481.255IO2000.481.016102000.247.25102000.241.0502000.240.75180-z8-FromPointAtoReservoirBa1.5inchpipeisappropriata,Fromre-servoirBtoCaI.25inchpipeisadequateandthereisextraheadavailableofIO-5=5meters.SincereservoirsCandDareatthesameelevationthisheadwillallowthewatertoflowtoreservoirD.ThuebetweenreservoirsBandDthetotalhead1066is10metersandthetotalavailableheadisal60IOmeters.3.6.PointAtoReservoirEandFCalculatedheadlossesarea6follovs:lengthb’low(meters)(l/s)PipediameterheadlossAvailablehead(inches)(incl.lC%extra)(meters)(meters)6000.291.5376000.291.25676000.291.01972000.151.0232000.150.7563If1.25inchpipeisusedfrompointAtoreservoirEand1.0inchpipefromreservoirEtoFthenthetotalheadlossis6+2or8metersvhichcloselymatchestheavailableheadofIOmeters.Thepipesizes,HGL,anddesignflowsareallnotedontheprofile.-Fl-APPENDIXF.AvailableHeadGLOSSARY:Theactualdifferenceinelevationbetveenthetwopoint6inquestion.Forexample,thedifferenceinelevationbetweentheoutflowpipeofthecapteringandtheover-flovpipeofthefirstreservoirwouldbetheavailableheadueedinselectingauappropriatepipe.AverageDailyFlow:TheflowofwaternecessarytosupplytheAverageDailyU-eifthewatervereflowingcontinuously.Itlausedaethebasi6forselectingdesignflowsforpipeTheAverageDailyDaageinq3dividedby86.4givestheAverageDailyFlovinl/sthatisneces8uytosupplytbetmount.AverageDailyUsage:TheaveragevoluneofwaterwhichflowsthroughthewaterColifozmBacturiaDesignFlowslystaduringa24hourperiod.ItiabasedonthetotalpopulationcIezpedandtheprojectedpercapitausageandisummllyexpressedincubicmeters(m3).TheAverageDailyWageieahypotheticalquantity.Inreality,onsomeday8waterusageisgreaterandonsomeday8itislem,itisonlyrarelythe6aae.Hovever,thisfigureisthebauisusedfordeterminingotherdesignparameterssuchasetoragevolumeanddesignflare.TheAverageDailyUsageforaeystemsupplying1,000pereonswith100llitursperdayis;1,000xICClitersor100q3.:Definedasrodshapedgrmnegativebacteriathatfomentlactoseet35OC.Theyarevideqmendintheenvironmentandnot~neceserrilyharmfultomm.Theywerefonuerlywidelyueeda8anindicatororgani-forwaterqualitybutarebeingreplacedbyfed,colifome.SeealsoFecalColiforme.:Theflowusedinthecalculationofheadlomeetode-terminethepipediameter.Itiechosen,bythedesignerbaaedonthenumberofusera,levelofeervica,andtypeofatoragetobeprovidedandisthusrelatedtotheaveragedailyflow.-F2-EstimatedMinimumFlow:Thebeetestimateofthetenyearlowflow*fromthewatersourcethatcanbemadewiththeavailabledata.?(:IOftenthelovestpointmeasurementtakenreducedby;y,,,,Ianappropriatefactortakingintoxcotitallrelevant!L,,,:+i.;JJ‘factors.,Itisbesttobeconservativeinestiroating:*,\theminimumflowtobeusedindesigningthesystem.E.Coli:SeeFecalColiformsFecalColiforms:AlsoreferredtoasEscherichiaColiorE.Coli.Thesearepartofthecoliformgroupbutthefermentationtoetisconductedat44C.Atthistemperaturethenon-fecalorganismdiefromheatahock.Itisbelievedthatallfeaalcoliformeoriginateintheintestine8ofmanandhighermaanalsandthattheywillnotreproduceoutsidethehost.Lhereissomeevidencethatthisdoesnotholdtruefortropicalareasbutuntilfurtherre-eearchiscompletedthepresenceoffecalcoliformemustberegardedasevidenceoffeoalcontamination.Fecalcoliformathemeelvesareusuallynotharmful,tomanbuttheirpresenceindicatesthatthewat~’chtaindiseasecausingorganism6whichscauseillnessinthowwhoconsumeit.Guideline:Avalueorrulederivedfromknownfact6orfigurestobeusedindecisionmakingor,designing.Thedecisionmakermaychoosetodeviatefromtheguideline.Thisisopposedtoastandardorcriteriawhichisgenerallyaruleestablishedbyauthoritythatcannotbedeviatedfrom.Head:Thepressureorforceperunitareathatisavailableormustbeovercomeinordertotransportwater.Headmaybesuppliedbygravityorbymechanicalmean6suchasaPW*Althoughitieapressureitiegenerallyre-ferredtoinmetersorfeetwhichistheequivalentpressurethatwouldbeexertedbyastandingcolumnofwaterofthheight.-F3-Headloss:Alossofpressure(orhead)inaclosedpipelineduetofric-tionbetweenthepipeandtheflow