EnergyWire: In comments released yesterday by the State Department, TransCanada Corp. acknowledged a possibility that opponents of Keystone XL have long used against the project: The heavy oil sands crude that would run through the controversial pipeline, if spilled in water, could sink below the surface. The TransCanada acknowledgment, tucked inside a 51-page list of proposed changes to State's March draft environmental review of KXL, came with caveats amid a suggestion that the government alter its reference...