Columbia Gas Transmission is working to restart the second of two pipelines shut down after a nearby line exploded last week, destroying four homes near Sissonville.
The 30-inch line is within 200 feet of the one that ruptured Dec. 11, sparking a fire that also cooked a section of Interstate 77 and damaged five other homes.
In a filing with the West Virginia Public Service Commission, Columbia says a smaller 26-inch line was restarted the night of the blast. As gas began to flow back through that line, workers patrolled the pipe on foot and by helicopter to spot leaks and possible damage.
The Charleston Daily Mail (http://bit.ly/UOkW99) says Columbia has a similar plan for the 30-inch line, which it hoped to restart Wednesday. It’s about 53 feet away from the exploded pipe, but Columbia says it can restart the flow without closing either I-77 or a local road.
Columbia says there are no signs of damage to the line, which was shut down as a precaution because pressure waves from explosions can increase the load on parallel lines.
Both of the temporarily idled lines send natural gas to customers near Washington, D.C.
PSC spokeswoman Susan Small said Tuesday the head of the agency’s gas pipeline safety division has been onsite with investigators since the blast and has signed off on the restart plan.
It includes the findings of Det Norske Veritas, an international risk management company, which concluded it was unlikely the pipeline was damaged because it was more than double the recommended safety distance. However, “there is a finite, albeit small, probability that a near critical defect existed” just before the line was depressurized, it said.
“This defect could grow to a critical size as a result of the large pressure cycle associated with depressurization and re-pressurization of the pipeline, resulting in a rupture or leak,” the consultant cautioned.
The pressure will be increased gradually in three phases, the company’s restart plan says, with 30-minute pauses at each stage to give inspectors time to verify the pipeline’s integrity.
The cause of the explosion in the 20-inch line, meanwhile, remains under investigation.
The National Transportation Safety Board has said that line showed signs of external corrosion and had thinned to about one-third of the recommended thickness in some spots.
Pipeline safety advocates including the NTSB recommend companies use metal tools called “smart pigs” to check for cracks, corrosion and other problems. But Kanawha County fire coordinator C.W. Sigman says the ruptured line didn’t have the kind of valves that would accept that tool.
Columbia, a subsidiary of Indiana-based NiSource, declined to comment on that.