Dew Construction's piling division has finished two major contracts in 18 weeks at the Rosyth roll-on-rolloff ferry project in Scotland.
Government confirmation of the scheme was six months late but the port still had to meet the original programme. The delay reduced the original schedule of 44 weeks to 18.
This meant the port had to be ready to receive its first ferry from Zeebrugge, Belgium in May 2002 and be fully operational with a second berth and new terminal building by August.
Imported fill was used to reclaim the land and to form access benches and haul roads across the site. A 200t barge-mounted excavator operated by subcontractor Westminster Dredging was then used to excavate 40,000t of bedrock. This round-the-clock operation was completed in three weeks.
Work could then begin on a 162m quay wall to create a deep-water berth hewn out of the bedrock. A Combi pile design was chosen and used a mixture of 1067mm high yield tubular piles with three Larson LX 25 sheet piles as infill panels.
Piling work progressed at 6m a day with installation immediately followed by cutting and trimming. Then 600mm diameter holes were drilled 7m into the bedrock and spigot piles placed.
The second project was to build two marine dolphins, the outer a canting dolphin to help the 23,000t ferries to moor safely and the inner to act as an extension of the berthing face of the existing quay.
The structures were retrofitted with instant soffit shutters, fender brackets, bollards and ladder cleats.
A modular approach meant that each dolphin could be finished in seven days.