Back when gold companies started commercially processing in Alaska they would bring in these gigantic dredges piece by piece and they would assembled them on site.  Then the dredge would then make its own path down the creek they were processing.  These dredges are the reason you will find large tailing piles in the middle of no where.  This particular dredge is no longer here, the state dismantled it due to people breaking into the fenced in area.  It would have been very dangerous to have been walking around in due to rotten floor boards and other hazards created from having sat for so long out in the elements.