Decommissioning and abandonment

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Decommissioning and abandonment

CUT AND LIFT

ƒ Removal of three BNFL outfalls in 2005/6 ƒ Demanded by local authority as part of planning

ƒ Severely corroded line breakup ƒ Coal-tar radioactivity on beach

Lifting stillages onto transport barge

This method is intended for the recovery of ‘short’ lengths of pipeline or bundle that are either exposed on the seabed or have been unburied with specialist equipment. A shallow- draught first-generation workbarge could be utilised. Outline procedure: Pipeline cut on seabed into pre-determined lengths Recovery grabs deployed to lift sections out of water onto barge deck Transfer pipe sections onto supply vessel for disposal/recycling onshore or re-use after refurbishment Advantages The pipeline does not require high degree of structural integrity Work could be undertaken inshore in shallow water Disadvantages Subsea cutting equipment for large diameter lines would need further development Debris from cutting released into the marine environment Barge operations slow and weather-dependent A small barge was used by Land & Marine to recover three rain water outfalls, which were potentially contaminated with low level radioactivity, in 2005. Their removal was a requirement of original planning consent. Seabed stillages (storage racks) were used to store the sections prior to lifting onto the barge. Of particular concern was the condition of one line, which was so severely corroded that there were fist-size holes in the wall. Additionally, pieces of coal-tar enamel breaking off and floating ashore (with its natural inherent radioactivity) could give a false reading of unapproved releases.

REFLOATPIPELINEANDTOWTOSHORE