.bmp)
On Sept. 9, a 30-inch natural gas pipeline exploded in the suburban community of San Bruno, Calif., creating a 2,000-degree fireball that killed eight people, destroyed 37 homes and left more than 60 people injured. A gaping crater replaced homes at the center of the blast.
Could it happen here?
A pipeline rupture of approximately the same magnitude did occur not far from the Washington area a couple of years ago, but with less-dire consequences.
On Sept. 14, 2008, a 30-inch span of the Transco pipeline ruptured in Appomattox County, Va., creating a fireball that destroyed two homes and caused five injuries. Twenty-three families were evacuated.
The Appomattox explosion was larger than the explosion in San Bruno, but it occurred in a less-populated area, said Carl Weimer, executive director of the Pipeline Safety Trust, a watchdog organization based in Bellingham, Wash.
The Appomattox rupture was caused by corrosion of the 53-year-old pipeline, which had been inspected three months earlier by a "smart pig," a computerized scanning device that travels through a pipeline searching for dings, dents or corrosion, but had not yet been repaired. Transco's owner, the Williams Cos., paid the U.S. Transportation Department a $952,000 fine, replaced 2,500 feet of the pipeline, "smart pigged" all of its pipelines in Virginia, and performed pressurized water tests to validate the repairs.
Aging pipelines - and growing populations in the once-rural areas where pipelines were routed decades ago - have increased the risks associated with ruptures throughout the United States.
"The average transmission pipe is 50 years old," Weimer said. "If you put a steel pipe in the ground 50 years ago, you can have problems. It's not the same strength as steel today, and it doesn't have the anti-corrosive coating. But the more important factor is how the company has operated and maintained the pipes."
Some of the largest interstate pipelines in the United States run through the Washington area. The massive Transco pipeline, which consists of three and four parallel pipelines of 30 to 42 inches each, runs through Culpeper, Fauquier, Prince William, Fairfax, Montgomery and Howard counties on its way north from the Gulf of Mexico and shale resources in Alabama to supply natural gas up the East Coast to New York City.
One of the largest import facilities for liquefied natural gas in the United States is at Cove Point in Calvert County. Tankers travel up the Chesapeake Bay to deliver gas from abroad; from Cove Point it is distributed via transmission pipelines throughout the region.
Columbia Gas Transmission also runs major gas pipelines across the western edge of the metro area. Washington Gas taps into these resources with 200 miles of high-pressure transmission pipelines, which run through every county in the metro area and even beneath the Mall. The pipelines connect to a 26,000-mile web of smaller distribution pipelines, typically three-quarters of a foot to one foot in diameter, where the pressure is reduced so the fuel can enter homes and businesses.
Digging up trouble
The majority of pipeline incidents in the D.C. metro area, however, are not from the large transmission pipelines. In fact, there haven't been any incidents on the 20 miles of 24-inch transmission pipelines in the District (most of which date to the 1960s) "as far back as anyone can remember," said Betty Ann Kane, chairman of the D.C. Public Service Commission.
0 comments:
Post a Comment