DPC Middle East Report
Stepping On The Gas
As the first phase of Ras Laffan Industrial City’s ambitious gas port
expansion scheme nears handover, ROGER LINDLEY marvels at the size of
the job and the precision it demanded
S
pecialist marine and coastal elements were used to profile and Accropodes, depending on position. At
engineering plant hire company protect the land reclaimed by placing the foot, there’s a large breakwater toe
Abeko is close to completing the more than 20M mthree.superior of dredged with a 5m extension.
first-phase expansion of the Qatari limestone and 25M mthree.superior of offshore On the harbour side, the ‘standard’
LNG port – already home to two of the sand. And well over 900,000m
3
of composition uses a 1.8m layer of 500kg
world’s largest natural gas terminals – geotextiles have been incorporated into quarry stone, a 1.15m-thick under-layer
in preparation for handing the site over the structures. of 100–500kg stone and an outer layer
to its client, Van Oord, for fitting out. The causeways and breakwaters are – around 1.8m thick – of 500–2,000kg
Abeko won the contract to provide topped by 3.4m-high crown walls and armour rock.
the machinery and operators that reinforced road slabs that typically Such is the variation in the
Van Oord needs to build 22.5km of measure 50m wide and 2.15m deep, for dimensions however – depending on
causeways and breakwaters. Van Oord which more than 170,000mthree.superior of concrete water depth and where additional
is already undertaking final surveys was poured. protection is required against ship
and, in conjunction with the Abeko impact – that there’s nothing ‘typical’
team, is carrying out any remedial work NON-STOP about the project. And that’s why it’s
needed to ensure the constructions Throughout the project, the proved to be so challenging.
conform to design specifications. contractors have used 45 heavy-duty Challenges included the project’s
Whether using land-based equipment or excavators and high-capacity crawler sheer scale, time constraints,
working at sea, these operations call for cranes, 40 rigid and articulated dump logistics, the many variations and
precision to avoid disturbing material trucks, 20 wheel loaders and other very demanding quality control for
already in place. To that end, an O&K support equipment. Work on the project materials and construction tolerances
RH90C excavator mounted on board continued non-stop, 24 hours a day, – as little as ±0.2m. Achieving this
Abeko Server 1 is helping with final seven days a week and, at its peak, kept required deployment of the very latest
underwater profiling of the breakwaters. more than 700 Van Oord and Abeko technology, advanced computer-aided
As the first phase nears completion, personnel busy. systems, sophisticated heavy-duty
some idea of the sheer volume of All the works are designed to very machines configured specially for the
material deployed can be gained from demanding requirements. The many works and a team of skilled operators.
the kilometres of structures standing kilometres of breakwaters have varying
several metres above the water line. specifications depending on their MEN AND MACHINES
Over 10.6M tonnes of local rock, location, but a typical cross-section Abeko needed all its experience in
together with a further 4.2M tonnes is about 133m wide, from the toe marine and coastal engineering projects,
imported from the UAE, have been put extension on one side to the extremity not to mention its team’s expertise and
in place, either by side-dump barges of the armour rock on the other. They specialised equipment, to complete the
or by dump trucks. The prefabrication rise to a maximum height of almost job at Ras Laffan.
yard’s swallowed up more than 1M mthree.superior 21m (of which 12m is below the Critical to the works has been the
of concrete to make the 185,000 precast waterline) and are profiled to a slope of 52m-long, 470-tonne Abeko Server 1,
concrete antifers and 36,000 concrete 33º on the seaward side and 37º on the which, with 30m-long spuds, is able to
Accropodes that formed the armour harbour side. work in 24m water depths. Its generous
layer for the breakwaters. The antifers Typically, the seaward side of the 6m × 40m deck area allows very large
come in three sizes – 1.5mthree.superior, 3mthree.superior and embankments comprises a 3m layer of heavy-duty excavators to be used. For
3.5mthree.superior – while the Accropodes range selected quarry stones of up to 500kg; Ras Laffan, the machine selected was a
from 3mthree.superior to 5mthree.superior. a 1.8m layer of 500–2,000kg rocks and 230t O&K RH90C with a triple boom,
The rock and precast concrete a 3.2m protective layer of antifers or equipped with a Prolec GPS Digmaster
system and 30m boom to aid precision
working in deep water.
A variety of land-based equipment
was used during the finishing work. To
place the antifers, 127t Hitachi Zaxis
850s were used, fitted with specially
designed rotating grabs to pick up and
position the large and heavy blocks,
which could be up to 5mthree.superior. To the
untrained eye, the antifers seem to be
placed at random, but in fact they’re
carefully positioned to ensure maximum
effectiveness in dispersing wave energy
and preventing back-scouring.
Other Hitachi ZX850s were
Long reach – configured with 30m-reach booms and
Hitachi ZX8703 excavator modified by Abeko with a special float
arrangement on the end of the stick to
A P R I L 2 0 0 9 D R E D G I N G A N D P O RT C O N S T R U C T I O N 44 www.dpcmagazine.com
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