River Intake System

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AN ECONOMICALAN ECONOMICAL

RIVER INTAKE PUMPRIVER INTAKE PUMPSTATIONSTATION

By: Walter T. Winn, Jr., P.E., DWRE, BCEE, F.ASCEBy: Walter T. Winn, Jr., P.E., DWRE, BCEE, F.ASCEGina R. Bolton, P.E., M.ASCEGina R. Bolton, P.E., M.ASCE

Northeast Texas Section WEAT Biennial SeminarNortheast Texas Section WEAT Biennial Seminar

Longview, TexasLongview, Texas


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OverviewOverview

IntroductionIntroduction

Water SupplyWater Supply

Intake ConstraintsIntake Constraints

Unconventional Intake DesignUnconventional Intake Design Modifications to Design after ConstructionModifications to Design after Construction

SubmittalsSubmittals

Resolution of Operational IssuesResolution of Operational Issues ConclusionsConclusions


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Trinity Rural Water SupplyTrinity Rural Water Supply

CorporationCorporation

Located in Trinity, Polk, and Walker CountiesLocated in Trinity, Polk, and Walker Counties

Serves approximately 1,400 customersServes approximately 1,400 customers

System previously served by ground water andSystem previously served by ground water andpurchased water from Trinity River Authoritypurchased water from Trinity River Authority(TRA) Trinity Co. Regional System and the City(TRA) Trinity Co. Regional System and the Cityof Trinityof Trinity

Additional water not available from TRAAdditional water not available from TRARegional System & Trinity. No groundwater ofRegional System & Trinity. No groundwater ofacceptable quality and quantity.acceptable quality and quantity.


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New Source of SupplyNew Source of Supply

Water rights from Lake Livingston owned byWater rights from Lake Livingston owned by

TRA and reserved for local useTRA and reserved for local use

Raw water from Trinity River at headwaters ofRaw water from Trinity River at headwaters of

Lake LivingstonLake Livingston Plant site located 1Plant site located 1-- mile north of SH 19mile north of SH 19

crossing of the Trinity River, west of SH 19crossing of the Trinity River, west of SH 19


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Intake ConstraintsIntake Constraints

Poor soil conditionsPoor soil conditions

High groundwater tableHigh groundwater table

Financial limitationsFinancial limitations

Decided to try unconventional floating pumpDecided to try unconventional floating pump

station designstation design


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Plant Flow DiagramPlant Flow Diagram


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Soil ProfileSoil Profile


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Unconventional Intake DesignUnconventional Intake Design

Submerged intake pipe and intake screenSubmerged intake pipe and intake screen

SelfSelf--priming centrifugal pumpspriming centrifugal pumps

Above ground floating platform systemAbove ground floating platform system


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Modifications to Design AfterModifications to Design After

Construction SubmittalsConstruction Submittals

The pumps selected by Contractor wereThe pumps selected by Contractor were

significantly heavier than the originally specifiedsignificantly heavier than the originally specified

pumpspumps Concrete slab on platform was modified to useConcrete slab on platform was modified to use

light weight concrete and reduce slab thicknesslight weight concrete and reduce slab thickness

from 6from 6 to 5to 5..


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Float Test of PlatformFloat Test of Platform


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Problems Discovered in TestingProblems Discovered in Testing

Platform twisting, putting torque on the postsPlatform twisting, putting torque on the posts

and pipe rollers holding it in place.and pipe rollers holding it in place.

Platform was not level as it was tilting towardsPlatform was not level as it was tilting towards

the corner where the pumps were placed.the corner where the pumps were placed.

Therefore, the weight was not evenly distributedTherefore, the weight was not evenly distributed

across the platform.across the platform.

Back to the drawing board.Back to the drawing board.


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Initial ConfigurationInitial Configuration


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Revised ConfigurationRevised Configuration


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Buoyancy CalculationsBuoyancy Calculations


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Concrete Ballast


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Issues in OperationIssues in Operation

Pumps kept losing primePumps kept losing prime

Operation at design flow rate of 700 gpm wasOperation at design flow rate of 700 gpm was

fine, but unable to reduce the flow rate belowfine, but unable to reduce the flow rate below

300 gpm300 gpm


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Chlorine Dioxide SystemChlorine Dioxide System

Air Release Valve

Electric

Solution Valve


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FIGURE 1INTAKE PUMP CURVES

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

50.00

55.00

60.00

0 100 200 300 400 500 600 700 800

Flow (gpm)

He

ad

(ft)

System

Curve at

131

680 rpm

780 rpm

880 rpm

980 rpm

1080

rpm


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Resolution of Operation IssuesResolution of Operation Issues Pumps kept losing primePumps kept losing primeFound that chlorineFound that chlorine

dioxide injection into pump suction wasdioxide injection into pump suction wasintroducing air. Added electric solution valveintroducing air. Added electric solution valveand air release valve.and air release valve.

Operation at design flow rate of 700 gpm wasOperation at design flow rate of 700 gpm wasfine, but unable to reduce the flow rate belowfine, but unable to reduce the flow rate below300 gpm300 gpmFound that flat pump curves causedFound that flat pump curves caused

VFDs toVFDs to searchsearch for flow set point. Controlsfor flow set point. Controlschanged to set pump speed instead of flow rate.changed to set pump speed instead of flow rate.


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ConclusionsConclusions

Worked through issues to developWorked through issues to develop

unconventional river intake pump station.unconventional river intake pump station. Saved Trinity Rural WSC an estimated $650,000,Saved Trinity Rural WSC an estimated $650,000,

about 65% of the original estimated intakeabout 65% of the original estimated intake

pump station cost.pump station cost.


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Questions?Questions?

Documents

River Intake System