Calif. pipeline explosion draws attention to work conditions

By Steve Johnson, Pete Carey and Leigh Poitinger
Sunday, October 24, 2010

SAN JOSE, CALIF. - The explosion of a natural gas pipeline in San Bruno, south of San Francisco, has underscored a growing concern about the capabilities of utility employees who watch over the nation's pipelines and whose errors have been linked to a number of mishaps, some of them catastrophic.

The National Transportation Safety Board has said that among the questions it is investigating in the Sept. 9 explosion is whether workers at a PG&E pipeline-monitoring terminal in Milpitas, Calif., were fatigued or poorly trained. Just eight days after the blast, the federal Pipeline and Hazardous Materials Safety Administration moved to speed up adoption of a rule to ensure that workers doing similar jobs at companies across the country are well-trained and rested - especially because many of those workers put in 12-hour shifts.

Officials with the pipeline agency were vague when asked if the disaster spurred their filing to expedite the gas-worker rule, saying only that the provisions have been under consideration for some time. Nonetheless, some experts say the new federal requirements are vitally needed.

Making sure utility employees aren't too tired or otherwise incapable of managing the computerized data they see "is absolutely important," said Shamin Sharoki, president of Houston-based Consipio, which advises gas companies on such matters. "If somebody is not trained, it could be very dangerous. If they don't properly respond to an alarm situation, it can cause an explosion. It can cause leaks. The damage could be very large."

Three days after the San Bruno explosion, which killed eight, the California Public Utilities Commission ordered PG&E to preserve all records at the Milpitas terminal, which monitors operations on the gas transmission line that ruptured, and to allow investigators with the NTSB to interview the workers there.

A few days later, NTSB Vice Chairman Christopher Hart revealed that the agency also was looking into the computerized system PG&E depends on to monitor and control the flow of gas.

A complex system

Use of that system - called Supervisory Control and Data Acquisition - is widespread among pipeline companies. And because the system's data would provide a detailed record of what happened to the San Bruno pipeline that burst, it's no surprise investigators were eager to inspect it. Yet worker problems associated with the system also have become a major safety concern.

A 2005 NTSB study that scrutinized 13 pipeline mishaps involving various liquids from 1992 to 2004 found that "in 10 of these accidents, some aspect of the SCADA system contributed to the severity of the accident." In many cases, the problems were aggravated when workers monitoring the systems failed to quickly recognize and respond to leaks. Among the accidents cited:

l An April 7, 1992, fire in Brenham, Tex., that caused three deaths and 21 injuries after a poorly trained worker failed to notice the changing pressure in a pipe, in part because the system didn't display data in a way the worker could easily interpret.

l On June 10, 1999, a worker failed to realize that a gasoline pipeline had ruptured and burst into flames in Bellingham, Wash., because the malfunctioning control system was providing erroneous data. As a result, it took more than an hour to shut the pipe's valves. Three people died, and eight were injured.

l On Oct. 27, 2004, after a pipeline containing the caustic and potentially deadly chemical anhydrous ammonia ruptured in Kingman, Kan., a worker misinterpreted alarms generated by a control system and mistakenly increased the flow of ammonia into the line. No one was killed or injured, but 204,000 gallons of the liquid flowed into a creek, killing more than 25,000 fish, including some threatened species.

From 1990 to 2009, gas-line operator errors caused a little more than 5 percent of all the significant accidents nationwide and resulted in eight fatalities, 150 injuries and $16.2 million in property damage, according to data kept by the Pipeline and Hazardous Materials Safety Administration. During the same period, operator error caused 11.5 percent of "serious incidents," which involve a fatality or an injury requiring hospitalization.


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