8/27/2013 1

Dredging

By Rick Wilmot C/E Port Engineer

Clamshell Division Weeks Marine

PresenterPresentation Notes.

8/27/2013 2

Topics of Discussion History of dredging Modern dredging Why we dredge Training

8/27/2013 3

History

PresenterPresentation NotesDredging by manual labor dates back thousands of years. As early as 1380 BC the egyptians built a canal from the Nile to the red sea,The Romans built canals in conquered lands in Briton as much as 40 miles long.Chinas Grand Canal was completed in the thirtenth century and is still in use todayAll these feats were accomplished without the use of dredging machinery

8/27/2013 4

Designs By Leonardo Da Vinci

PresenterPresentation NotesMechanical dredging really began during medieval times and the industry leaders from the startr were the Belgialns. Canals and locks can be found therwe dating back to the 1100’s These are some Da Vinci designs from the mid to late 1400sYou can see how as the bucket wheel turned the dredge would advance on these lines

8/27/2013 5

8/27/2013 6

PresenterPresentation NotesIn 1729 the missisipi river was dredged by the agitation method to a depth of 17 feet. This is done by stirring up the bottom and letting the current carry the materials downstream.This is done today with water injection dredges. The first american built dredge was the hippopotumus, it was built in Philidelphia in 1774 and was powered by three men and a horse, it was of the clamshell design.

8/27/2013 7

PresenterPresentation NotesAt the start of the industrial revolution steam was aplied to dredging. This was commissioned by the philadelphia board of health to dig around the city docks but wasnot very successful

8/27/2013 8

PresenterPresentation NotesThe Suez Canal was built by the french engineer De Lesseps and completed in 1869. The job was done in 10 years and shortened the trade route to india by 6000 miles

8/27/2013 9

Erie Canal

PresenterPresentation NotesA great example of the effect of dredging on commerce was the erie canal, opened in 1825 at a cost of about 7 million, it connected lake Erie to the hudson river. This canal brought down the cost of shipping a ton of goods from buffulo to new york from 100 dollars to less than 25 dollars. And by 1882 had earned back its cost of construction and maintenance and turned a profit of 42 million dollars.

8/27/2013 10

Panama Canal

PresenterPresentation NotesThis brings us to the Panama Canal, the first attempt was made by the French in1879, again with the french engineer DE Lesseps. The contract went to a San Fransisco company at 23 cents a yard. (today it can range from 2 dollars a yard for beach work to 50 or 60 dollars a yard for contaminated material or maore.) The first dredge sent was a bucketladder design with 36- 27 cubic yard buckets the ladder was 100 foot long and the machine was built in philadelphia.The project went bankrupt in 1888 but was revived under Teddy Roosevelt and completed by the American Army Engineers in 1914. This shortened the voyage between New York and San Fransisco by 9000 milesAt this point Id like to move on to modern dredging.

8/27/2013 11

Modern Dredging Excavation Transportation Disposal or end-use of spoils Support equipment Training

PresenterPresentation NotesA dredging job breaks down into three parts ETC.

8/27/2013 12

Excavation

PresenterPresentation NotesExcavation falls into two catagories, mechanical and hydraulic.

8/27/2013 13

Mechanical Excavation

PresenterPresentation NotesIn Mechanical dredging the material is removed directly with a bucket or scoop of some type.

8/27/2013 14

Mechanical Dredges

Clamshell dredge Backhoe dredge Bucket ladder dredge Dipper dredge Dragline

8/27/2013 15

Clamshell Bucket Dredge

PresenterPresentation NotesClamshell dredges, this one is using a cablearm bucket, these are designed and built by a fellow named Ray Bergeron somwhere up in the midwest. They are designed for use with light material and minimal disturbance. There are several types of buckets, some for harder materaials and some for mud.

8/27/2013 16

Backhoe Dredge

PresenterPresentation NotesThis is a ytpe of dredge we are seeing more and more often they are able to dig very hard material. They are all hydraulic but in this case Im refering to an oil hydraulic system which moves the arms and controls the spuds. The three spuds are pushed down to hold the machine in place and then the digging begins. These high pressure hydraulic systems are prone to leaks and fires, this dredge is only a few years old and has already had two major fires.

8/27/2013 17

Bucketladder Dredge

PresenterPresentation NotesAs you can see this type of dredge uses a conveyor belt of bucket scooping up the material from the bottom and exiting through the shoot into the barge, these are more common in mining operations.

8/27/2013 18

Dipper Dredge

PresenterPresentation NotesThese are not used much anymore but you still find them in the mining industry This slide shows a dipper working with a pocket scow in the construction of penns landing in philidelphia

8/27/2013 19

Hydraulic Excavation

PresenterPresentation NotesThe second type of excavation is hydraulic, this means the material is mixed with water and pumped as a slurry either down a pipeline or into a hopper for transport

8/27/2013 20

Hydraulic Dredges

Cutter suction Dustpan Plain suction Water injection dredge Hopper dredge

8/27/2013 21

Cutter Suction Dredge

PresenterPresentation NotesThe cutter suction dredge shown works kind of like a drillbit. The cutter on the front rotates and churns up the material to be dredged and located behind it is the suction of the pump. There may be two or three pumps onboard, these boost the pressure, but more importantly they boost the velocity of the slurry you can theoretically pump as far as you like as long as you maintain velocity by adding booster stations along the line. The longest line I ever worked on was about eight miles. Before you start you have to establish flow throughout the line then you can introduce the material. You only run about ten to twenty percent solids. Different cutters are used for different mstrerials this type of dredge puts down one spud and swings back and forth on anchors pumping as it swings.

8/27/2013 22

Water Injection Dredge

PresenterPresentation NotesA water injection dredge pumps high pressure water into the mud or sand bottom and stirs the material into a slurry then lets the natural current carry off the material

8/27/2013 23

Dustpan Dredge

PresenterPresentation NotesOften used in Beach reclamation this dredge can pump as much as 100 thousand cubic yards a day. And if you’ve ever been to the jersey sghore you’ve probably laid on sand pumped there by this machine

8/27/2013 24

Trailing Arm Hopper Dredges

PresenterPresentation NotesHopper dredges vary in size from a few thousand cubic meters capacity to one of the largest at 33,00o cubic meters. Thye can have one two or three arms and basically are a seagoing vacumn cleaner. They suck up the mud or sand and place it into the hopper then when they get to the disposal area they can either split open to dump or some have pump out capability. The last slide you can see the drdge in drydock that split at the bottom opens to about 14 feet wide when fully open.

8/27/2013 25

Transportation

PresenterPresentation NotesThe second part of any dredging job is transporting the material to the dump site. By one of two methods

8/27/2013 26

Barge or Pipeline

PresenterPresentation NotesIn mechanical dredging the spoils are usually hauled away by barge, the barges are either pumped out or bottom dumped through doors or in the case of splithull scows they can be opened up by hydraulics remotely from the tug by radio. In the case of hydraulic dredging the material is kept in solution and pumped , with booster stations as needed

8/27/2013 27

Disposal of Spoils

PresenterPresentation NotesThis slide shows some of the ways of disposing of the dredged material. In the one they hopper dredge is pumping the mud directly onto the beach. The second shows an island being built in Baltimore, the mud is pumped ashore and as it migrates across the disposal area the solids drop out and the water returns to the harbor. In some cases when dealing with contaminated spoils the mud is buried and capped with clean sand or even mixed with other materials and used as construction material

8/27/2013 28

Barge Unloader

PresenterPresentation NotesHer you see a barge unloader pumping out a barge of dredge spoils, this combine the efficiency of using mechanical dredgeing to load the scows with the versatility of hydraulic disposal. The tugs bring in the barges from as far away as you need and the tender tug helps with the docking. The unloader injects water to liquify the mud then pumps it ashore

8/27/2013 29

Support Equipment

Drill rig Survey boats Stifflegs Drag barges Boosters

PresenterPresentation NotesThat’s just some of the support equipment.

8/27/2013 30

PresenterPresentation NotesSupport equipment, drillrig- we drill and blast bedrock when we have to deepen the channel in hard bottom areas. You can control the size of the blasted rock by changing the blast pattern. We did this when deepening the KVK channel between new jersey and staten island.Survey boats, create a three d map of the bottom of the channel which we use to dig withStifflegs are used for anchor movement, they are moved about with tugsDrag barges are used to clean up the little lumps and give a smooth bottom

8/27/2013 31

8/27/2013 32

Why Do We Dredge ?

Channel deepening and maintenance Reclamation of land Beach nourishment and restoration Mining for aggregates and minerals

8/27/2013 33

Maintenance

Reclamation and Use

PresenterPresentation NotesWe dredge to maintain the channel for ship traffic, channels constantly silt in and must be clearedWe dredge to reclaim land for use. Examples would be the meadowlands, were built on swamp, also long stretches of the new jersey turnpike were dredges and then refilled with stable materials for the roadbed, other examples would be the exrtension of the Honk kong airport and many others.

8/27/2013 34

Beachbuilding

Aggregate Mining

Beachbuilding and Mining

PresenterPresentation NotesBeaches erode after every storm, if you’ve ever been to the jersey shore you were probably lying on sand put there by a dredgeAs for mining we use them to mine for sand for concrete as well as gold and precious gems, I have a friend who owns a diamond dredge in venezuela.

8/27/2013 35

Training

Hopper personnel are Coast Guard

licensed DSMP training On The Job Union Schools

PresenterPresentation NotesWhile most of the the training is on the job on most of the equipment the union does offer some training schools for operatorsAll personnel on the hopper dredges are licensed by the US coast guard requiring sea time and a series of exams at each step in gradeThe DSMP is a new program started by some of the larger dredging companies to answer this need for better trained personnel. It is a series of procedures and some classroom training as well as firefighting and lifesaving techniques that is being given to all new hires and will some day become industry standerd

8/27/2013 36

Survey

PresenterPresentation NotesThis shows a modern example of what the operator is working from, The left you can see a backhoe representation with depths and a profile veiw, the right shows a cutter dredge

DredgingTopics of DiscussionHistorySlide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Erie CanalPanama CanalModern Dredging ExcavationMechanical ExcavationMechanical DredgesClamshell Bucket DredgeBackhoe DredgeBucketladder DredgeDipper DredgeHydraulic ExcavationHydraulic DredgesCutter Suction DredgeWater Injection DredgeDustpan DredgeTrailing Arm Hopper DredgesTransportationBarge or PipelineDisposal of SpoilsBarge UnloaderSupport EquipmentSlide Number 30Slide Number 31Why Do We Dredge ?Maintenance Beachbuilding� and� MiningTrainingSurvey