L3 -Intake Structures.ppt

Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.

1. WATER SUPPLY ENGINEERING
ENVIRONMENT ENGINEERING I
INTAKE STRUCTURES

2. What are Intake Structures?
i.Structuresareusedforcollectingwaterfrom
thesurfacesourcessuchasriver,lake,and
reservoir
ii.Conveyingitfurthertothewatertreatment
plant.
iii.CircularorRectangular
iv.Masonryorconcretestructures
v.Providesrelativelycleanwater,freefrom
pollution,sandandobjectionablefloating
material.
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3. Selecting Location Of Intake Structure
1.Providepurerwatersothatitstreatmentmaybecomelessexhaustive.
2.Heavywatercurrentsshouldnotstriketheintakedirectly.
3.Placedwheresufficientquantityofwaterremainsavailableunderallthecircumstances.
4.Wellconnectedbygoodtypeofroads.
5.Positionedtoprovidemorewaterifrequiredtodoso.
6.Notbelocatedinnavigationchannels,becausewaterofsuchchannelsisgenerallypolluted.
7.Duringfloodsinrivers,floodwatersshouldnotbeconcentratedtowardstheintake.
8.Notbelocatedonthecurveoftheriver.Ifthereisnoalternativethenintakeshouldbelocatedon
theouterbankandnotontheinnerbank.
9.Locatedonupstreamsideofthetown.
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4. Design of Intake
Intakeshouldbedesignedonthebasisofthefollowingconsiderations:-
1.Shouldbesufficientlyheavy,notbewashedawaybyheavywatercurrents.
2.Alltheforceswhichareexpectedtoworkonintakeshouldbecarefullyanalyzedandintake
shouldbedesignedtowithstandalltheseforces.
3.Thefoundationoftheintakeshouldbetakensufficientlydeep-avoidoverturningofthe
structure.
4.Shouldnotbeconstructedinanavigationchannelaspossible.
5.Strainersintheformofwiremeshshouldbeprovidedonalltheintakeinlets.Thiswillavoid
entryoflargefloatingobjectsandfishesintotheintake.
6.Shouldbeofsuchsizeandsolocatedthatsufficientquantityofwatercanbeobtainedfromthe
intakeinallcircumstances.
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5. TYPES OF INTAKES
According to type of source
◦River Intake
◦Canal Intake
◦Reservoir Intake
◦Lake Intake
According to location
◦Submerged Intake
◦Exposed Intake
According to presence of water in the tower
◦Wet Intake
◦Dry Intake
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6. Intake constructed in the middle of the river Intake constructed on the banks on the river
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7. RIVER INTAKE WELL
i.Located-insidetheriversothatdemandsof
wateraremetwithinalltheseasonsofthe
year,ortheymaybelocatedneartheriver
bankwhereasufficientdepthofwateris
available.
ii.circularmasonrytower
iii.Dia=4to7m
iv.constructedatsuchplacefromwhere
requiredquantityofwatercanbeobtained
eveninthedryperiod.
v.Thewaterentersinthelowerportionofthe
intakeknownfrompenstocks.
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8. CANAL INTAKE WELL
i.Theentryofwaterintheintakechambertakes
throughcoarsescreenandthetopofoutletpipeis
providedwithfinescreen.
ii.Theinlettooutletpipeisofbell-mouthshapewith
perforationsofthefinescreenonitssurface.
iii.Theoutletvalveisoperatedfromthetopandit
controlstheentryofwaterintotheoutletpipe
fromwhereitistakentothetreatmentplant.
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9. RESERVOIR INTAKE WELL
i.Intakepipesarelocatedatdifferentlevelswith
commonverticalpipe.
ii.Thevalvesofpipesareoperatedfromthetopand
theyareinstalledinavalveroom.
iii.Eachintakepipeisprovidedwithbellmouthentry
withperforationsoffinescreenonits
iv.surface.Theoutletpipeistakenoutthroughthe
bodyofdam.
v.Thelocationofintakepipesatdifferentlevels
ensuressupplyofwaterfromalevellowerthanthe
surfacelevelofwater.
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10. LAKE INTAKE
i.Theseintakesareconstructedinthebedof
thelakebelowthewaterlevel;soasto
drawwaterindryseasonalso.
ii.Astheseintakesdrawsmallquantityof
water,thesearenotusedinbigwater
supplyschemesoronriversorreservoirs.
iii.Advantages-noobstructiontothe
navigation,nodangerfromthefloating
bodiesandnotroubleduetoice.
iv.Disadvantage-theyarenoteasily
approachableformaintenance.
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11. Intake Structures
EXPOSED INTAKE STRUCTURES
i.Generally,awellortowerconstructednearthe
bankofariver/lake,orinsomecasesevenaway
fromtheriverbanks.
ii.Thesearemorecommonduetoeaseinthe
operationandmaintenance.
SUBMERGED INTAKE STRUCTURES
i.Constructedentirelyunderwater
ii.Simpleconcreteblockorarockfilledtimbercrib
supportingthestartingendofthewithdrawalpipe
iii.Intakeopeningiscoveredbyscreentopreventthe
entryofdebris,iceetc.
iv.Generally,donotobstructnavigation
v.Thecostislowercomparedtootheroptions
vi.Limitation:Noteasilyaccessibleforcleaningand
repairing
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12. According to presence of water in the tower
WET INTAKE DRY INTAKE
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13. Wet Intake Towers
i.Concretecircularshellfilledwithwaterupto
theriver/reservoirlevelkeepingwaterlevelin
theintakepracticallythesameasthelevelof
thesources.
ii.Hasaverticalinsideshaftconnectedtothe
withdrawalpipe
iii.Controlledgatebasedopeningsaremadeinto
theouterconcreteshellaswellas,intothe
insideshaft.
iv.Thewithdrawalpipemaylieovertheriverbed
ormaybeintheformoftunnelsbelowthe
riverbed
v.ItisoftenknownasJackwellandismost
commonlyused.
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14. Dry Intake Towers
i.Incaseofdryintakethereisnooutershell(as
incaseofwetintaketowers).
ii.Waterentersthroughentryportdirectlyinto
thewithdrawalconduits.
iii.Whentheentryportsareclosedandthereisno
waterinthewithdrawalconduit,adryintake
towerwillbesubjectedtogreaterbuoyancy
forces.
iv.Henceitmustbeofheavierconstructionthan
wetintaketower.
v.Operationofvalvesetc.arereasonablysimple
indryintaketowers.
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15. Single Well vs Twin Well Intake
TwinWellTypeIntakesconsistsofaninletwell,intakepipe,andaJackWell.Intakepipe
connectsinletwellwithjackwellwithflowvelocity<1.2m/s.
Single Well Type Intakes, no inlet well & inlet pipe in needed, and opening or ports fitted with
bar screens are provided in the jack well itself.
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16. Recommended Readings
i.Mark J. Hammer; Water and Waste Water Technology; Prentice Hall of India.
ii.S. K. Garg; Water Supply Engineering; Khanna Publ.
iii.B. C. Punmia, A. K. Jain; Water Supply Engineering; Laxmi Publication.
iv.G. S. Birdie; Water Supply Engineering and Sanitary Engineering; Dhanpat Rai.
v.R. C. Rangwala; Water Supply Engineering, Charotar Publ. House.
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