In a letter to Gov. Snyder:
“….BE IT FURTHER RESOLVED, that the Great Lakes and St. Lawrence Cities Initiative recommends additional safety measures, notably, all modes of transportation of fossil energies be equipped with double walled containment, including pipelines, ships, barges, tank cars, and tank trucks…”
Read the entire Resolution here — Gov Snyder re. Enbridge
----------- idle no more --------- -----Defending Mother Earth -- 
Go for quadruple walls and compromise on two.