From an Associated Press article published 9/13/10:

“‘That’s an issue we’re going to have to look on a bigger scale — situations in which pipes of some age were put in before the dense population arrived and now the dense population is right over the pipe,’ he said.

“Thousands of pipelines nationwide fit the same bill, and they frequently experience mishaps. Federal officials have recorded 2,840 significant gas pipeline accidents since 1990, more than a third causing deaths and significant injuries.”

–  http://news.yahoo.com/s/ap/us_pipeline_explosion

In February 2009 we posted here:

“The infrastructure is aging: For years Matt Simmons, the only Peak Oil activist among the oil & gas industry elite, has been warning about, besides peak oil, the aging energy delivery system:

“’If the world wants to keep using energy from oil and gas, it will have to rebuild the infrastructure and the cost of doing this could rival the combined cost of the World War II war machine, the post-war Marshall Plan that rebuilt Europe, and the post-war buildout of the U.S. interstate highway system.’

“Simmons said the costs could be enormous–in the $50- to $100 trillion range. Triage needs to happen immediately to prioritize which links in the system are the weakest and need to be repaired or replaced first. Pipelines are old, some dating to World War II. The average age of the drilling rig fleets onshore and offshore is 24 years. Refineries are even older.”

Source:
http://blogs.oilandgasinvestor.com/leslie/2008/05/05/matt-simmons-rust-happens/