PreparationandDesignofaPhysicalandElectronicInspectionofa66-inchSteelWater

MaininWashington,DC

MandyLeBlanc,PE- PM- DCWaterLouisRagozzino,PE- PM- OBG

Background

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Approximately20milesofsteelwatermainintheDCWatersystemrangingfrom16”to66”diameter

Theyhavearecordofthehighestfrequencyofbreaksand/orleaksinDC

DCWaterAssetManagementisevaluatingthemostcriticalwatertransmissionmainsaspartoftheCIP

66”SteelWaterMainwasidentifiedashavingaMedium-HighConsequenceofFailure

ProjectObjectives§ Internalpipeinspectionbyvisual,

physicalandelectronictesting

§ Documentationofobservedconditionsandrepairs

§ Minorjointandpointrepairs

§ Internalcoatingsystemrepair

§ Cathodicprotectionsystemupgrade

§ Disinfectionandplacingbackintoservice

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Challenges§ Location

§ Timing

§ Access

§ Safety

§ Inspectionrequirements

§ DesignConsiderations

§ Dewatering/Disinfection

§ Conclusions/Lessonslearned(FuturePlanning)

4

5

Constructedunderfourcontractsfrom1961to1968

History

Theoverallpipelineisapproximately8,000feetlongwitha1/2inchwallthicknessandisboundedonthenorthandsouthendsbya66-inchdiameterPrestressedConcreteCylinderPipe(PCCP)

Onlyonecontractincludedcathodicprotection

Theexisting66-inchSteelMainislinedwithcoaltarenamelontheinteriorandwithcoaltarwrappedwithasbestosfeltontheexterior

Location

8thSt.NEFromEastCapitolNorthTo3rd St.NEBetweenMSt.NEandNSt.NE

6

MStreetNE

IStreetNE

8th

StreetNE

EastCapitolStreetNE

Timing/Schedule

7

WorkisscheduledtocoincidewithinspectionanddrainingoftheBrentwoodReservoirCleaning.Thisrequires:

§ CoordinationwithDCWaterOperationsandWashingtonAqueduct

§ Valveexercisingpriortoconstructiontoensurereliability

§ Assesscriticalitytoidentifyuserimpacts

§ Developmentofadewateringanddisinfectionplan

§ Projectmustbecompletedbtw.Sept.andMay

BrentwoodReservoirInter-connectionWith66-inchMain

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25MGBrentwoodReservoir

Twin48-inchPCCPconnecttothe66-inchSteelMain

66-inchSteelMain

Access

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InordertomeettheProjectObjective,accesstomainisneededfor:

§ Dewatering–Blowofflocations(1.5Milliongallons)

§ Dischargelocations(sanitarysewer)

§ Ventilation

§ Inspection

§ PotentialRepairs

§ FutureImprovements

Safety

DoubleShutdownCriteria

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Mainrequiresafullshutdowntomaintainadrypipeinteriorconditionforanyworkrequiringmannedentryintothepipetoperformworkorinspectthepipe.Theshutdownshallbeaccomplishedbyfullclosureoftwo,ormore,existingmainvalves,temporarylinestop valves,and/ortemporarycuttingandrestrainedcappingofthemaintobeentered.

OthermeansandmethodsofachievingadoubleshutdownaresubjecttoreviewandapprovalbyDCWater.

Safety

DoubleShutdownArea

17,200LFof66”Main

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3,500LFofshutdown

5,700LFofshutdown

8,000LFprojectarea

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CutandCap InternalBulkhead

LineStop AddaNewValve

Safety

DoubleShutdownAlternatives

NEW VAULT

NEW 66” BUTTERFLY VALVENEW ACCESS

Safety

DoubleShutdownComparison

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DoubleShut

Method

ConstructionImpacts

FutureShutdown

DurationofRoadImpact

RequiresVault

DisinfectionLength(LF)

EstimatedCost

CutandCapwithConcreteThrust

Restraint

1 1 1 5 11,500($173,000) $300kx2

InsertNewValve

1 5 1 2 11,500($173,000) $500kx2

InternalBulkhead 3 1 3 5 11,500

($173,000) $200kx2

DoubleValveClosure

5 2 5 5 17,200($260,000) $0

Note:1indicatesleastadvantageous,and5indicatesmostadvantageous.

Safety

DoubleShutdownCriticalityAnalysis

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Criticalityanalysisresultsinrecommendationtoshutexistingvalves.

Nocustomersappeartobeoutofservicewhenthe66-inchLowServicesteelmainisoutofservice.

ReviewOfSteelPipeNondestructiveTests

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Technology Pros Cons

Radiography• Usefulforthinsectionsof

pipe

• Cannotpenetratethicksectionsofpipe

• Onlydetectssurfacedefects

UltrasonicFlawDetection

• Offersextremesensitivitywhenrequired(internalandsurfacedetection)

• Nopermanentrecordofresultsisavailable

• Canonlytestalengthofpipeupto30feetinlength.

DyePenetrantTesting

• Simple• Detectssurfacebreaking

cracks

• Willnotdetectcrackswithoutcurrentleaks

• Doesnotdetectthinningmetal

EddyCurrentTesting(BroadbandElectromagneticTechnology)

• CandetectalargerangeofsurfaceorsubsurfaceflawsDetectswallthickness

• Scansfullcircumference

• Sincesomanyparametersaredetected,somemaymaskothers.

• Navigatingbendscanbeachallenge

• Assemblyofequipmentcantakedays

VisualInspection • Effectivemethodtoidentifymajorinternaldefects

• Cannotdeterminethicknessofpipe.

• Maynotdetectmoreminorflaws.

Inspection

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Visualinspectionandnon-destructivetestingoftheinteriorofthe66-inchsteelpipe,includingjoints,coatingsandinteriorpipewallcondition:

§ Fulldigitalsurveyfootageofkeyjoints,pipeshellspotsandinteriorpipesurfaces

§ Inchormilgaugescaleorinstrumentdepthofallisolatedpits,orrangeofpitdepths

§ Conditionandtypeofalljoints

§ Averificationovality

§ MagneticFluxLeakDetection(MFL)inspection

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MagneticFluxLeakage(MFL)isamethodofnon-destructivetestingthatisusedtodetectcorrosionandpittinginmetallicpipelines.

Scansthefullcircumferenceandlengthofapipeline,providinghigh-resolutioninformationonpipewallcondition.

Iseitherpushedorpulledthroughpipe.

Cannotgothroughvalvesornavigatebends

Requirestighttolerancetopipewallforaccuracyofdata.

MFLInspection

https://www.puretechltd.com/technologies-brands/pure-mflSource:PURETechnologies

InspectionAccess

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Selectionoftheaccesslocationswasbasedon:1. Existingvalvelocations

2. Bends,bothhorizontalandvertical

3. Existingutilities

4. Repairtechniques5. Dewateringatlowpoints

As-builtDrawingInformation

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DesignConsiderations

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Designofsteelaccessports(36-inchminimum)

DesignofAccessManholesupportfortrafficloadingandkeepingloadsoffpipe

Insertionof66-inchbutterflyvalve

Designofrepairoptions

Upgradeofcathodicprotectionsystem

Useofhelicalpilestoreducepotentialforimpactstoexistingpipe

DesignConsiderations

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Designofaccessportsintosteelmain1. 10access

locationselected

2. 24-inchmin.pipeaccessforequipment

3. Reinforcementcollarincludedforpipestiffening

DesignConsiderations

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DesignofAccessManholesupportfortrafficloadingandkeepingloadsoffpipe

DESIGNCONSIDERATIONS

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Insertionof66-inchbutterflyvalve

DisinfectionPlan

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Flushing11,500feetof66-inchmain

Chlorinationof25milliongallonBrentwoodReservoirwithapproximately10,000poundsofsodiumhypochlorite.

Concentrationof20mg/latreservoir,minimumof4mg/latfarthestpoint.

Dischargeofhighly-chlorinatedwatertosanitarysewer

Fillingofmainandreservoirwithpotablewater

LessonsLearned

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Aprojectofthisnaturerequiresanextensiveamountofcoordinationandcommunication.

ThenumberofpartiesinvolvedincludebothinsideDCWateraswellasoutsidedepartmentsandagencies.

GoodrecordsandunderstandingtheAs-Builtconditioniscriticalidentifyingtheconstraintsandexistingconditionsoftheburiedassets.

Planningforrepairspriortoinspectioninvolvedinclusionofcontingenciesforrepairitemswhichmayormaynotbeneeded.

THANKYOU

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Acknowledgements§ WilliamElledge,DCW

§ Getachew Melsew,DCW

§ Marlee Franzen,DCW

§ DavidWall,DCW

§ MaureenSchmelling,DCW

§ BrianWalls,DCW

§ SoniaOton,MM

§ SarahGhali,MM

§ ChelseaGress,OBG

OBG|THERE’SAWAY

Questions?Thankyou!

DESIGNSTANDARDS

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1. AWWAC206.11“FieldWeldingofSteelWaterPipe”

2. AWWAC207-13,“SteelPipeFlangesforService,Sizes4-inchthrough144-inch”

3. AWWAC210-15,“Liquid-EpoxyCoatingsandLiningsforSteelWaterPipe.”

4. AWWAC651-14,“DisinfectingWaterMains”

5. AWWAM11,“SteelPipe– GuideforDesignandInstallation”

6. AWWAM77,“ManualofPractice:ConditionAssessmentofWaterMains”

7. DCWaterDesignGuidelines,StandardSpecifications,andDetails

PERMITTING/COORDINATION

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DuringDesign

1. DDOT– Occupancy/MOTPermit- Survey,utilitydesignation,geotechnicalinvestigations

2. DDOT– ConstructionPermit- Pavementmoratoriums/restoration

3. DDOE– ErosionandSedimentControlPlans

4. DDOE– AsbestosRemoval5. Localeventscoordination

6. Stakeholdersnotifications

7. DCWaterOperations

MAINTENANCEAND

PROTECTIONOFTRAFFIC

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10individualworklocations,eachwithuniquetrafficcontrolrequirementssuchas:1. Bikelanes2. HospitalEmergencyRoom

3. Residentialparking4. Busstops

5. Staging