Piling project extends container terminal

Danish contractor Per Aarsleff is installing its largest ever combination steel pile retaining wall to extend the Port of Muuga container terminal, located 17 km east of Estonia's capital, Tallinn.

Per Aarsleff is carrying out the DKK 430 million (€ 57,7 million) joint venture project with Estonian contractor KMG Inseneriehituse AS and the specialist Danish dredging contractor Rohde Nielsen A/S.

The site team, with its fleet of specialist marine plant, has been driving 420 tubular steel piles up to 1,67 m in diameter and 45 m long into the seabed of the Gulf of Finland during harsh weather conditions and rough seas.

About two thirds of the piles, weighing up to 32 tonnes, will be linked together in combination with pairs of shorter steel sheet piles to form the main quay wall and a section of retaining wall running alongside the terminal's existing wharf.

One end of the side wall will link into the terminal's existing quay, while the other end of the main quay will combine with a new 800 m long breakwater joining with the existing natural coastline.

The wall and breakwater will form an enclosed basin, which is being filled with 1,5 million m³ of sea-dredged sand to reclaim the new 180000 m² extension to the terminal area.

A second line of smaller diameter, equally spaced tubular piles is also being installed behind and parallel to the main berthing wall. Together they will provide the foundation support for the twin rail tracks to take the existing and new quayside container handling cranes.

René Mølgaard Jensen, Per Aarsleff's deputy site manager, said, "To my knowledge this is the largest tubular profile combiwall and certainly one of the longest Per Aarsleff has installed. And 20 m behind this main 380 m long part of combiwall frontage we also have to install, using the same equipment, a row of normal 1,22 m diameter tubular piles up to 42 m long and capable of taking 6900 kN and a row 15 m behind the remainder of 1,02 m diameter tubes.

"These two back rows are spaced to accommodate the gauge of the container crane tracks," he added.

The final part of the project will involve the excavation and dredging of about 570000 m³ of material by Rohde Nielsen A/S from the seabed in front of the main wall, increasing water depth to 14,5 m to accommodate the berthing container ships.

Per Aarsleff said despite some initial delays at the start of the project and the current loss of about 15% of the time due to poor weather, the joint venture anticipates finishing its 18 month contract on schedule in January 2010.

Other contractors are expected to be brought in to pave the reclaimed terminal area and erect and commission the new container handling cranes.