Case Study

Tolmount Landfall Cofferdam Easington, East Yorkshire

Temporary works to supply, install and extract sheet piles for a pipeline landfall cofferdam

Contract No.
C21399
Process
ABI Leader Rigs
Number of Piles
771

Overview

Tolmount Landfall Cofferdam

We were engaged to design, supply, install and extract a reception pit and landfall cofferdam for a new north sea landfall pipeline in East Yorkshire. The sheet piling was carried out in tidal working conditions and a 50m length of the trench was located below Mean Low Water Springs.

We utilised both our ABI TM 14/17 and ABI TM 20 Telescopic Leader Rigs alongside our 55tonne telescopic crawler crane on the beach to install the following;

Reception Pit area - 92No. L607/PU32 Larssen piles between 14.5m and 17.5m long.
Pipe Pull Trench - 679No. L605/PU22-1 Larssen piles between 10m and 12m long (the overall length of the trench was approximately 190 linear metres).

Ground conditions dictated that all sheet pile positions had to be pre-augered at 450mm diameter at 600mm centres using one of the rigs with the second rig then pitching and driving the piles. The sheet piles were distributed using a 38-tonne tracked excavator providing piles on a just in time basis as nothing could be left on the beach outside tidal working windoes. Prefabricated steel support framing was also fitted within the trench between low tides.