The existing jetty, constructed in the 1950s has come to the end of its design life and needs replacing. However, this is a multi-purpose facility for shippers of neo-bulk cargoes such as steel, metals and forest products, so it has been essential that operations have continued undisrupted at the main terminal jetty.
Mackley started on site in September 2021 and work carried out since then has included initial works to divert, remove and relocate an existing substation and utilities before Mackley could begin works to strengthen the existing river wall.
The strengthening required adding 5no 36m long 1,016mm diameter anchor piles to the existing sheet piled wall, a separate waling and new tie rods.
Mackley constructed a bespoke piling gate to drive these piles accurately to avoid the existing tie rods.
They were installed in two phases to accommodate delivery by road (delivery by barge was not viable as this would severely disrupt the daily operations at the main terminal).
The first 18m were driven using an ABI piling rig; then the second 18m length was pitched and welded in situ. On completion of rigorous weld testing, the full pile was then driven to depth by the use of the more conventional crane and impact hammer.
Fourteen of the seaward piles (seven rows of pairs) that will support the new approach were driven as full 36m lengths. These were welded together and tested in advance on land within the site.
While the onsite welding was being carried out, Mackley installed significant temporary works to construct a piling platform to enable a 400t crawler crane to carry out the seaward piling.
To provide additional safe access to work from, Mackley brought in a modular jack up barge, which was also used to lift in/out and support the piling gates.
With the piles driven to depth, work could begin to lift in the precast reinforced concrete cross beams, which were welded to the new tube piles. On completion of the welding, the pile heads were grouted in situ.
New precast reinforced concrete slabs needed to be individually fabricated to ensure that the reinforcement interlocked. These were lifted onto the beams by use of the 400t crane on the landward side; after which further reinforcement stitch bars were installed and in situ concrete poured to form a monolithic Jetty.
The existing approach has remained open and operations at the main terminal have continued undisrupted throughout.
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