Jump to Categories
Hinman Pulse

August 28, 2014

This Month, Hinman Remembers: 2010 San Bruno Pipeline Rupture and Fire

by Eve Hinman

This September 11th will be the 13th anniversary of the terrorist attacks on the WTC and Pentagon.  As horrendous as these events were,  I would like to use this opportunity to turn our attent ion to a disaster type that is not related to an external villain, but is emblematic of a growing menace that is self inflicted and largely ignored: our aging infrastructure. We tend to take for granted that we will have water, electricity, and natural gas in our homes and workplaces. The pipes and wires that provide these services are largely unseen below the ground. As our population continues to grow, these networked systems become more complex and challenging to manage. The newer pipes need to be bigger and stronger, while the old ones are asked to perform at higher levels.  The end result is that when accidents happen, the magnitude and losses are amplified.

Humans are very good at adapting in crises, but unable to see that the everyday things that we build to make our lives more comfortable are also able to harm us.  Every year more critical infrastructure reaches the end of its useful life. It is fair to say that it is likely that it has not been sufficiently maintained during its lifetime. Infrastructure is all around us and we are very dependent on it in our daily lives.

This is a ticking bomb. It is more insidious and more frightening to me than terrorism because infrastructure is ubiquitous and under served. 

Rather than provide a narrative about the San Bruno pipeline incident, this month I will provide a short synopsis and summary table followed by some of my observations.


   Explosion followed by fire due to the rupture of a faulty weld made in 1956
   A  faulty weld in  30 in gas pipeline installed in 1956 ruptured


   September 9, 2010, 6:11pm PDT


   San Bruno,  California (12 miles from San Francisco, 2.5 miles from SFO)


   A worker mistakenly allowed the pressure in the pipeline to increase


   8 fatalities; 66 injuries (10 serious)
   37 homes destroyed; 70 damaged

   PG&E Costs

   $759M in safety upgrades ($229 borne by customers over 3 year period)
   $550M to victims
   Possibly $1.3B for profits earned as a result of misconduct
   Possibly $2.5B for state regulatory violations

This time bomb started ticking in 1956 when a section of the pipeline was moved to accommodate the construction of homes. The replaced pipe section that failed 54 years later did not meet PG&E standards (or any standard). Also, it had a longitudinal crack that was repaired with a substandard weld. This weld endured for 54 years growing progressively weaker with fatigue. It had never been inspected. Finally in 2010 at the SCADA facility which controls the gas flow, PG&E decided to perform some maintenance and the measurement equipment erroneously showed  that the pressure level was normal, 386 psig although the actual pressure was slightly higher, 396 psig. This pushed the already weakened weld beyond its impaired capacity and caused its failure.  In addition to the pipe weld, there were not automatic valves to shut off the gas after the rupture.  It took the emergency crew 95 minutes to manually reach the pipe and shut off the flow of gas which was feeding the fire. Overall PG&E did not exhibit the level of safety management which is expected for utility companies.

As part of the investigation it was found that the state regulator, the California Public Utilities Commission (CPUC), and the federal Pipeline and Hazardous Materials Safety Administration (PHMSA) had some responsibility for the incident as well. CPUC evidently had a cozy relationship with PG&E and did not enforce the safety provisions on the books. PHMSA apparently was very friendly with the utilities it regulated and exempted inspection of older pipes (which affects a lot of pipes in the US). Some changes are being made to correct these errors and more oversight will thankfully occur as a result of this incident.

In conclusion, studies have shown that people tend to overestimate the probability of very rare but spectacular events like terrorism, but under estimate the probability of losses due to much more frequent hazardous events such as natural disasters and the failure of infrastructure. Although we have little control over terrorism (which is why it creates so much anxiety) we do in fact have a lot of control over infrastructure. I suggest to the reader that we need to begin to focus inward on our own man made issues and stop worrying so much about some great evil in the universe like terrorism.

Join the conversation

Please enter the word you see to the right: