Regarding the dredging stirring up old contaminants, back in '86 when the carrier I was on needed an emergency dry-dock in SF bay, the local environmentalists got a little bent out of shape when it was disclosed that the dredging to open access to the dry-dock stirred up radioactive contamination (among other materials) that had settled in the bay from decontaminating the 1950's atomic blast observer ships.
No, I do not know what happened to the dredging spoils.
Larry C
