Brent Alpha is the only one of the four Brent platforms that has a steel jacket. The jacket stands in water deep enough to completely submerge the London Eye at a depth of 140m below sea level. The structure has eight legs and was built in Scotland before being floated out to position in the 1970s.
For all but the very largest steel structures, current legislation prohibits leaving steel jackets completely in place at sea. However, OSPAR Decision 98/3 recognises that there may be difficulty in removing the “footings” of large steel jackets weighing more than 10,000 tonnes where structures were installed before 9th February 1999. OSPAR Decision 98/3 defines the 'footings' as those parts of a steel installation which are below the highest point of the steel piles (pins) that are used to fix the structure to the sea bed.
Where significant reasons for leaving all or part of the ‘footings’ in place can be demonstrated as preferable compared to returning them to the shore, derogation to leave these parts can be sought.
In terms of what we propose to leave behind, the ‘footings’ of a piled steel jacket are clearly defined in the OSPAR regulations.
After completing a Comparative Assessment, the recommendation will be to leave the steel jacket footings in place due to the engineering challenges and broader concerns associated with their removal. Leaving the footings in place will also allow the drill cuttings pile to be left to degrade naturally.