Ahhhh... I would like to see the plans for that. When ice is pushed by wind and you couple that with freeze-thaw and currents, Mother Nature can be a bitch.

My main qusetion would be about the height of the top of the 400m diameter island above sea level. Secondly, about the assessment of the seabed to withstand, over time, the horizontal shear force at the base of the island radiating from the centre... about 2000m or more. That's a lot of seabed. If it lets go in one direction in future, or if the island settles differentially over time, the remedial actions taken in the Gulf of Mexico won't even be an option.

But, I am sure BP has ther top peeps on it and there are no worries.