Q & A: How safe is the Transco pipeline?

Q. What is the pipeline?

A. It is part of the Transco natural gas pipeline that extends through 12 states, from the Gulf of Mexico to New York, including 858 miles in Virginia, according to the U.S. Department of Transportation’s Pipeline Hazardous Materials Safety Administration.

Q. How common are injuries along the line?

A. The incident marked the first time that members of the public have been hurt in a pipeline failure along the Transco line, said Larry Hjalmarson, vice president of operations for Williams Gas Pipeline, which operates the line.

A record of incidents along the line over the past 22 years, excluding Sunday’s explosion, shows three incidents in Virginia and none that have caused injuries, according to the Pipeline Safety Trust, an advocacy group.

One failure happened in January 1993 in Campbell County, when a material defect caused $54,000 in damages. Another happened in Culpeper in 1994, caused by corrosion that left $250,000 in damages. The final one happened in Chantilly in 2005, caused by excavation damage and resulting in more than $161,000 in damages.

Overall, along the line, there have been 64 incidents causing nearly $43 million in damages since 1986.

The number one cause of these failures is damage by outside forces, such as an excavator mishap. Other causes are material defect and corrosion.

“With how many miles of pipeline, they seem to be a fairly safe pipeline,” said Carl Weimer, executive director of the Pipeline Safety Trust.

“It’s a big system and they have had no deaths. It seems like they run a pretty safe pipeline, but past performance is not really a good way to predict future safety.”

Q. How does the pipeline work?

A. Pipelines used in the natural gas system range from two inches in diameter to 42 inches; most are steel. The line that failed in Appomattox was 30 inches in diameter and normally operates at about 800 pounds per square inch of pressure. That line, called the B line, runs alongside two other pipelines, the A and C lines. Compressor stations every 50 to 100 miles along the line, including one in Appomattox, maintain pressure and push the gas up the lines.

Gates also are installed about every 10 miles to stop gas flow completely if necessary. In lines that run side-by-side, as they do in Appomattox, crossover pipes typically are installed to divert gas to other lines.

Q. What are the inspection requirements?

A. Until 2002, there was no federal requirement that pipelines like the Transco line undergo regular inspections.

The Pipeline Safety Improvement Act calls for inspections to be completed by Dec. 17 of this year for pipelines that run through “high consequence areas” — locations with more than 46 houses, within 100 yards of a business, or places with buildings that are at least four stories tall.

The act requires inspections of all other pipelines by 2012, and re-inspections every seven years.

“Up until 2002, once a gas pipeline was built and put into the ground, they did not ever have to inspect them again,” said Weimer, of the Pipeline Safety Trust.

Williams already had an inspection protocol in place. In Appomattox, the A line was inspected in 2000. The C line was inspected early this year and repaired. The B line — the one that failed — had just been inspected, but Williams’ officials had not analyzed the results prior to the explosion.

“Pipelines, if well maintained, will last indefinitely,” Hjalmarson said.

Q. How is the inspection done?

A. The inspection process uses a computerized tool commonly called a “pig,” Hjalmarson said, which goes into the lines and looks for corrosion or other damage that can cause a failure. Analyzing the data can take up to four months, he said.

Pigs are run on lines no sooner than every three years and no longer than every 10, he said.

“In some of these lines, it’s the first time the pig has been run,” Hjalmarson said.

Pipeline companies have long been required to conduct flyover inspections of the pipeline rights-of-way, looking for evidence of potential damage, such as signs that someone had been digging in the area, Weimer said.

Q. Is there a map of the pipeline?

A. The Pipeline Safety Act of 2002 also required pipeline companies to map their systems, Weimer said.

“Many didn’t have maps of their pipelines and the federal government didn’t know where they were,” he said.

Q. Do county planners take the pipeline into consideration when new development is proposed?

A. The location of the lines has become more important as houses and businesses have begun to grow up near the lines, many of which were installed 50 years ago or more, in areas that were then rural. That isn’t as big of a problem in the Lynchburg area, according to community planners.

Paul Harvey, community development director for Campbell County, said the portion of the pipeline that runs through his county is in a predominantly rural area. However, if a property was subdivided without needing rezoning, Harvey said the planning department would have no choice but to approve the plan.

Bedford County does not have any natural gas pipelines, but it does have fuel pipelines in and out of the tank farm in Montvale, said county planning director George Nester.

Those lines mirror U.S. 460 or the Norfolk & Western railroad lines, so few houses are close, he said.

“We always consider it to be a potential problem,” Nester said. “Any flammable liquid gas or gas, there is potential for a problem. We do check and make sure to the best of our ability there is not an encroachment problem.”

Q. How can I find out if there is a pipeline in my area?

A. The U.S. Department of Transportation’s Pipeline Hazardous Materials Safety Administration has a Web site that can give property owners a rough idea of where the pipelines lie in their communities. It can be found at http://www.npms.phmsa.dot.gov/searchp/newlogin.asp?Search=Pub. Pipelines should also be marked with signs.