What’s feesible? The tunnel or the bridge? I’d heard the tunnel wasn’t possible due to the particular geography of the channel. But a bridge? Now that I’d be interesting I seeing. There used to be a giants causeway across there in mythical times ...
The bridge is unfeasible because the channel is around 200m deep in places which makes it crazy expensive. I also found a couple of references to nuclear waste in the trench, but that might have been for another site.
Both of which I was aware of but I heard that some kind of suspension design would work. The tunnel is infeasible because there’s a very deep trench there, and that as you mentioned is filled with all sorts of nasty stuff.