That's pretty significant, environmentally speaking - surprised it didn't make the national news.
How did the water get in but no fuel get out? Petrol station tanks are double skinned and generally more than up to the job, are there serious landslip issues at the site?
No idea - perhaps the double skinned thing is how water managed to get in but no fuel got out, or perhaps the crack was just in the neck - I do not know. That is just the explanation that was offered in the local press.