determining the size of the hydraulic dredge

12/12/2014 Determining the Size of the Hydraulic Dredge http://www.dredgingspecialists.com/DetermineSizeOfDredge.htm 1/3 Home Contact Us Don Searles CV [Resume] Consultants About the Company The Dredgers Tool Box Dredging Tutorials Read before calling Products Services Dredge Automation The Aquatic Remediation System Piranha Diver Cutterhead Is Polymer Effective in Dredge Pipelines & With GeoBags? Expert Witness References Inventions Filling a Need in Nigeria March 4, 2010 Determining The Size Of The Hydraulic Dredge Needed For A Dredging Project. By Don Searles Dredging Specialists 1. Determine the volume of material to be dredged in cubic yards or cubic meters. 1.1. English System: To get cubic yards. Take the length in feet x the width in feet of the area to be dredged x the depth in feet of the material to be dredged, divided by 27 to get cubic yards. If you know the number of acres to be dredged, take acres x 1613 x depth of material in feet to be dredged to get cubic yards. 1.2. Metric System: To get cubic meters. Take length in meters x width in meters of the area to be dredged x depth in meters of the material to be dredged. If you know the hectares of the area to be dredged, take the number of hectares to be dredged x the depth in meters, of the material to be dredged x 10,000 to get cubic meters. 2. Determine the time allowed to complete the project. Days, weeks and months. 3. Determine the hours that you will work. Per day, per week. Will you run 1 shift, 2 shifts or 3 shifts? Could be 3 shifts 24/7. 4. Determine the type of material to be dredged. Fine sand, medium sand, large sand, small gravel, large gravel, silt which is mud, clay, cobbles 3 to 10 inches[76 to 254mm], boulders +10 inches [254mm]. When dredging a lake, the material will most likely be mud. 5. Determine if you will be dredging sediments or undisturbed material. Undisturbed material is much more difficult to dredge. Stay away from dredging undisturbed material unless there is a valid reason like the depth needed for large ship passage. 6. Determine the horizontal pumping distance. Maximum and minimum. 7. Determine the vertical pumping distance called static head. This is the vertical distance from the water surface to the discharge point. 8. Determine the altitude above sea level where the project is located. 9. Determine the maximum digging depth. This is the distance from the water surface to the lowest point of dredging. Only after the above 9 items have been determined is it possible to determine the size of the dredge, the inside diameter of the pipeline and the horsepower of the engines needed to do the job.

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Hydraulic Dredger Sizing

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12/12/2014 DeterminingtheSizeoftheHydraulicDredge

http://www.dredgingspecialists.com/DetermineSizeOfDredge.htm 1/3

Home

ContactUs

DonSearlesCV[Resume]

Consultants

AbouttheCompany

TheDredgersToolBox DredgingTutorialsReadbeforecallingProducts

Services DredgeAutomation TheAquaticRemediationSystem

PiranhaDiverCutterhead

IsPolymerEffectiveinDredgePipelines&WithGeoBags?

ExpertWitness

References

Inventions FillingaNeedinNigeria

March4,2010DeterminingTheSizeOfTheHydraulicDredge

NeededForADredgingProject.ByDonSearles

DredgingSpecialists

1.Determinethevolumeofmaterialtobedredgedincubicyardsorcubicmeters.

1.1.EnglishSystem:Togetcubicyards.Takethelengthinfeetxthewidthinfeetoftheareatobedredgedxthedepthinfeetofthematerialtobedredged,dividedby27togetcubicyards.Ifyouknowthenumberofacrestobedredged,takeacresx1613xdepthofmaterialinfeettobedredgedtogetcubicyards.

1.2.MetricSystem:Togetcubicmeters.Takelengthinmetersxwidthinmetersoftheareatobedredgedxdepthinmetersofthematerialtobedredged.Ifyouknowthehectaresoftheareatobedredged,takethenumberofhectarestobedredgedxthedepthinmeters,ofthematerialtobedredgedx10,000togetcubicmeters.

2.Determinethetimeallowedtocompletetheproject.Days,weeksandmonths.

3.Determinethehoursthatyouwillwork.Perday,perweek.Willyourun1shift,2shiftsor3shifts?Couldbe3shifts24/7.

4.Determinethetypeofmaterialtobedredged.Finesand,mediumsand,largesand,smallgravel,largegravel,siltwhichismud,clay,cobbles3to10inches[76to254mm],boulders+10inches[254mm].Whendredgingalake,thematerialwillmostlikelybemud.

5.Determineifyouwillbedredgingsedimentsorundisturbedmaterial.Undisturbedmaterialismuchmoredifficulttodredge.Stayawayfromdredgingundisturbedmaterialunlessthereisavalidreasonlikethedepthneededforlargeshippassage.

6.Determinethehorizontalpumpingdistance.Maximumandminimum.

7.Determinetheverticalpumpingdistancecalledstatichead.Thisistheverticaldistancefromthewatersurfacetothedischargepoint.

8.Determinethealtitudeabovesealevelwheretheprojectislocated.

9.Determinethemaximumdiggingdepth.Thisisthedistancefromthewatersurfacetothelowestpointofdredging.

Onlyaftertheabove9itemshavebeendeterminedisitpossibletodeterminethesizeofthedredge,theinsidediameterofthepipelineandthehorsepoweroftheenginesneededtodothejob.
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DredgeSizes:Thesizeofahydraulicdredgeisdeterminedbytheinsidediameterofthedischargeflangeonthedredgepump.Dredgescomeinsizesfrom8inch[203mm]to36inch[914mm].An8inch[203mm]dredgewilltypicallypump2,500gpm[gallonsperminute][9,464lpm]withanenginehorsepowerofaround300[223kw]andaweightof25tons.A36inchdredge[914mm]willpumpupto70,000gpm[265cmm]withupto10,000horsepower[7,456kw]andaweightofseveralthousandtons.Withagivensizedredgetheproductioncanvarywidelyandisdeterminedbytheoutsidediameteroftheimpellerinthedredgepump,thespeedoftheimpeller,thehorsepoweroftheenginedrivingthedredgepump,andthefrictionandstaticheadlossesinthepipeline.

Usingboosterpumps,pumpingdistancesof20miles[57km]havebeenattained.

Whenitems1through9areknown,DredgingSpecialistscandesignthedredgingsystemandrecommendthedredgeneeded,determineifboosterpumpsareneeded,thesizeofpipeandmanyotherfactorsthatareneededtocompleteadredgingproject.

Thefollowingchartwillprovideaballparkestimateofdredgeproduction.

1DredgeSize

2ProductioninCubicUnits

PerPumpingHourWhenPumpingMud

3ProductionPerWorking

Hour70%OfPumpingHourProduction

ShowninColumn2.8inch[203mm] 113cuyd[86cm] 79cuyd[60cm]10inch[254mm]

160cuyd[122cm] 112cuyd[84cm]

12inch[305mm]

250cuyd[191cm] 175cuyd[134cm]

14inch[356mm]

350cuyd[268cm] 245cuyd[188cm]

16inch[406mm]

440cuyd[336cm] 308cuyd[235cm]

18inch[457mm]

540cuyd[382cm] 378cuyd[267cm]

20inch[508mm]

712cuyd[544cm] 498cuyd[381cm]

24inch[610mm]

1,000cuyd[765cm] 700cuyd[536cm]

8and10inch[203to254mm]dredgescantypicallybehauledononetruck.Largerdredgesmustbedisassembledandhauledonseveraltrucks.For810and12inch[203254305mm]dredgesalargecraneisneededtolaunchthem.Largerdredgesaretypicallyassembledatthedredgesiteonshipwaysmadeoftimbers,andpushedintothewaterwithbulldozers.Mostdredges,20inch[508mm]andlarger,arenot
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portableandmustbefloatedtothejob.