Rothesay, Isle of Bute, Scotland
The town of Rothesay had decided to deepen the harbour for the creation of a Marina to meet the increasing leisure trade and to build a new jetty for ferry traffic.
The main contractor for this project was Balfour Beatty Civil Engineering. The Albion group were contracted for two parts of this project.
First, we were contracted to help with the piling work by drilling rock sockets. We also had to extend the existing piles into the rock and install and grout up anchors.
The work involved drilling to depths of up to 40 metres. We mainly installed Dywidag anchors.
Second, as part of deepening the harbour Balfour Beatty had to build a Cofferdam. This would seal off one section of the harbour to allow access to the low level anchors. The harbour was dewatered and steel sheet piles installed. Albion then anchored the steel sheet piles back with 185 No. anchors up to 20 metres long. These anchors required casing to full depth.
When we were finished drilling the rock sockets and the anchors were successfully tensioned, Balfour Beatty excavated, deepening the harbour, before removing the Cofferdam.
Technical:
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Used up to 4No. Atlas Copco Mustang A52 rigs with duplex drilling and casing systems
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Installed permanent ground anchorages to stabilise harbour wall
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185 No. 20m Dywidag double corrosion protected Gewi bar anchors
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220mm diameter casing in sands and gravels to depths of 20m
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Working in tidal working conditions
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Constructed 38 No. rock sockets
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Drilled 508mm rock sockets for marine pile installation
