As Alan said, they do have a refinery in the works in SD, but you still have to transport the refined fuels to where the users are. Pipelines are a FAR more efficient way of doing that than tanker trucks or train cars and far safer, too. As far as leaks and spills from the pipeline; TransCanada was planning to encase the entire line in concrete through Nebraska. I'm not sure if that was planned for the entire length or just through NE as an olive branch to the opposition.