Source: World Dredging Mining & Construction
An Australian dredging and earthmoving contractor is using a recently purchased 14-inch Ellicott® B890 dredge to clear access channels for six isolated island communities in the remote Torres Strait between Northern Australia and New Guinea.
Hall Contracting Pty. Ltd., headquartered on Queensland’s Sunshine Coast, won a tender for the Torres Strait job from the Australian government.
The contract involves dredging channels for large landing barges to supply six island communities direct from Cairns instead of off-loading to smaller barges and awaiting tides.
The logistics of working in this remote region prompted Hall Contracting to purchase a 12,000 ton dump barge as a support vessel. The stern end was outfitted with portable accommodations and a kitchen. The pipeline, floats, and hoses are carried in racks forward. A 30T Caterpillar excavator, IT18 for pipe carrying work, an 18-ton rough terrain crane, 4WD vehicles, and other equipment are carried in the center. The barge also carried a complete workshop, several hundred thousand liters of fuel, and a salt-water desalinator.
On arrival at each island, the ramp is lowered and the machinery and pipe is unloaded. A pipeline corridor is cleared and the 14-inch line is bolted together by an air gun. A bonded area and silt trap is made ready for the arrival of the Ellicott® dredge which is also towed from island to island, weather permitting.
The tailwater quality is monitored using a turbidity meter, as the islands are conscious of their dependence on the local fishing industry.
The six channels in the project vary in the quantity and type of material to be dredged. Sand, clay, and coral “bommies” are the norm for the Southern three islands. The Northern island close to New Guinea features marine mud and stiff yellow clay. The quantities range from 10,000 cubic meters to 60,000 cubic meters each.
“The Ellicott® dredge is performing well with both the rotary cutter and the bucket wheel being used. Our operators are particularly impressed by the traveling spud carriage for its accuracy in positioning the dredge in the 40-meter-wide channels”, Brian Hall, director of Hall Contracting, said.
An 11-meter tender barge powered by a 3306T CAT engine and fitted with two hydraulic winches for lifting duties carries out fuel transfers and anchor shifts.
For the ocean tows, a false bow was designed and built in the company’s workshop to fit in behind the spud carriage in the closed position. Brian Hall reports that this unit, when fitted, with spuds removed and hatches and windows shuttered, has proved itself during the long ocean tow from Brisbane to Torres Strait.
Due to the remoteness of these islands, the operation is run continuously and the crew is rotated using the company aircraft. Currents in the area run at up to eight knots and can play havoc with the pipeline and work boat anchor shifts. Although the weather has caused some lost time and equipment, Brian Hall reports the company has completed three of the six islands and is “ahead of the bar chart”.
Reprinted from World Dredging Mining & Construction