A massive explosion Dec. 11 of a natural gas transmission pipeline near Sissonville is raising questions about natural gas pipeline safety in West Virginia and elsewhere.
The explosion of a NiSource/Columbia Gas pipeline leveled several houses and wrecked a section of Interstate 77, closing the roadway for several hours. The explosion was the 38th natural gas pipeline explosion in the nation this year.
More than 15,000 miles of pipelines lie under West Virginia's surface, including 14,959 devoted to gas transmission, gas gathering and gas distribution. But the explosion had some people asking whether those pipelines are safe.
Charlie Burd, executive director of the Independent Oil and Gas Association of West Virginia, said pipelines are common all over the country, but incidents related to pipelines aren't that common.
"The incidents are very rare. I don't think that it's a cause for any citizen to be alarmed. These pipelines are inspected routinely and they have a very high level of inspection, and this particular pipeline would be a USDOT jurisdictional pipeline. The US Department of Transportation oversees the inspection process on this particular line, on lines of this particular type," he said.
Burd said pipelines, such as the 20-inch pipeline running near Sissonville, operate out of sight, out of mind.
"Its only when you have some sort of catastrophic event such as this that people are even truly reminded that they're there," Burd said. "But they're there for a purpose. Without these types of pipelines, we don't energize our nation. That's what brings volumes of natural gas to the state of West Virginia, through the state of West Virginia and to other locations."
The cause of the explosion has not been determined yet. However, investigators with the National Transportation Safety Board said the explosion could have been caused by deterioration within the pipeline.
According to Robert Sumwalt from the NTSB, a six-foot area along the bottom of the pipe had thin walls, in some places less than a tenth of an inch in thickness, or about 70 percent thinner than designed. This loss of wall thickness could have contributed to the explosion.
Sumwalt said this section of pipeline SM-80 was connected to the Lanham Compression Station owned by NiSource/Columbia Gas. Pressure within the pipe dropped at approximately 12:41 p.m. Dec. 11, but Sumwalt said NTSB investigators don't know if the pressure drop contributed to the blast or was a result of the pipe rupture.
According to NTSB investigators, the pipeline ran west to east perpendicular to Interstate 77. When the pipe exploded, it left a crater 15 to 17 feet deep. The 20-inch transmission line was located near a 30-inch line and a 26-inch line. Neither pipe was damaged by the blast. According to Sumwalt, a section of pipe more than 20 feet long was ejected in the blast.
"That part was ejected out of the crater," he told the press.
A part of the pipeline that was shut down after the blast was returned to service about a week after the explosion. A report authored by Columbia and shared by the Public Service Commission shows that the pipe, known as the SM-86 loop, was not affected by the accident and would return to service. A larger line had already been returned to service just after the incident.
The loop is approximately 53 feet north of the pipeline that exploded. Officials say SM-86 will be slowly brought online, increasing pressure in three different stages to ensure it had not experienced a defect as a result of depressurization/repressurization.
The company used aerial surveillance to monitor potential leaks.
Columbia's plan did not include details of restoring the service to the 20-inch pipeline that exploded Dec. 11. That pipeline, SM-80, will have a separate plan detailing its restoration plans.