The "top 100" list was put together in 2009. P-G-and E president Chris Johns says the company compiles lists like this every year to keep track of pipelines that need a little extra monitoring. He says the list should put customers at ease. 

"Take security from the fact that we are constantly looking out and trying to anticipate where the risks are to the pipelines so that we can do the maintenance ahead of time to prevent any safety problems."   

But the pipeline that exploded in San Bruno near San Francisco a few weeks ago never made it onto that list.

"We were not aware of anything in this particular area that would have met the criteria that would have put it on that list."

Johns says until investigators figure out what caused the explosion, it's unclear why that piece of pipe wasn't given extra attention.

The California Public Utilities Commission requested P-G-and-E to reveal the document. Johns says the list isn't normally made public, because in the past, no one asked to see it.