The Feasibility and Construction of the Landfall at the Liverpool Bay Development, Point of Ayr, North Wales

This paper describes the feasibility and construction of the landfall of a 20" gas pipeline and two 3" piggy-backed condensate pipelines at Point of Ayr, North Wales from BHP Petroleum's Liverpool Bay Development.

The 4,340 metre long pipeline was constructed from pipeslrings, each approximately 600 metres long using a construction site at Point of Ayr. The pipeslrings were pulled into position by the bottom pull technique using an 800 tonne capacity winch spread on a marine barge.

On completion of the pulling operation the pipelines were buried in the seabed using a submarine trenching machine operated from two work barges. The utilisation of the TM4 trenching machine was in preference to an extensive dredging and backfill operation.