It could be worse.
At least it wasn't heavy oil
Diesel evaporates readily and I have been told US warplanes routinely dump JP5 (kerosene - it's in the purple colored pipes on carriers
). If this is untrue I stand ready to be corrected.
I, for one, consider dumping empty 55 gallon drums at sea in thousands of feet of water
preferable to trying to dispose of them on land. They will disappear in short order. Better yet, preferable to turn them into a steel
pan instrument. But steps should be taken to allow any residual diesel to evaporate and to make sure the drums sink, i.e., cut the drums in half with a grinder before disposing. They'll make a nice fish
condo until they rust away.
That said, even carrying 55 gallon drums of diesel on board is bad form and if a mega sailing yacht cannot cross an ocean without that reserve it's contrary to all cruising customs
and mores I respect. I think they need to do some sailing and turn off all their needless electrical
goodies including AC, satellite
TVs, etc., etc., and underwater lights.....