I think that pipe was dumped strategically by a tugboat or some such vessel...too big and heavy for divers to be playing with.
I have a hard time with the logistics of this, for several reasons.
- First, the pipe would have to be firmly planted at the proper angle to penetrate the ship's hull and not be driven further into the river bottom.
- Second, the odds of the ship hitting it at just the right angle, at just the right depth, in just the right part of the river are not consistent with the risks involved in planting it there.
- Third, the perpetrators would have to know that ship was going to be passing by, since an oil spill seems to have been the most damaging possible event.
I'm just scratching the surface here, but the description of the pipe and the damage, along with the amount of luck involved, just doesn't add up. I'm holding out for more data.