Conceptions of what constitutes a tanker are irrelevant.  The data is clear, the east coast of Canada experiences far greater marine movement of all hydrocarbons, into, out of and among their refineries than does the west coast.  This includes trips  along the st lawrence to quebec and montreal.   Even if KM is built the flow of tanker traffic in/out Vancouver will not compare to the east coast, especially as the west has no offshore oil production, which the east coast has enjoyed for decades with not a hint of rebuke.