Columbia Gas Transmission officials have reported that the pipeline that exploded last week could not be checked for corrosion using one important pipeline safety tool, Kanawha County officials said Monday.
The 20-inch diameter natural gas transmission line showed signs of external corrosion, according to the National Transportation Safety Board, which is investigating the incident. The pipe had thinned in places to about a third of the thickness it ought to have been, the NTSB said.
Pipeline safety advocates - including the NTSB - recommend pipes be tested for such corrosion using "smart pigs," which are metal tools that travel through a pipeline to check the pipe for irregularities, including cracks and corrosion.
"The pipe that ruptured did not have valves on it that would accept the pig," said Kanawha fire coordinator C.W. Sigman, who met Monday with Columbia representatives.
Kanawha County Commission President Kent Carper confirmed Sigman's account of the meeting.
"It is our understanding that the ruptured pipe was not piggable," Carper said through a spokeswoman.
Columbia is a subsidiary of Indiana-based NiSource. Last week, one of its 20-inch diameter transmission lines ruptured and filled the sky with fire, scorched the earth and ruined the surface of a segment of Interstate 77. Miraculously, nobody was injured or killed.
The company did not comment on that pipe's ability to handle a smart pig, citing the NTSB's ongoing investigation of the explosion.
Pipeline safety advocates have argued smart pigs are a key way to ensure the structural integrity of pipelines.
"I think those are kind of the gold standards for measuring corrosion," said Carl Weimer, head of the Pipeline Safety Trust, a Bellingham, Wash.-based group devoted to improving pipeline safety.
Following a deadly pipeline explosion in San Bruno, Calif., the NTSB recommended all gas transmission pipelines be upgraded to accommodate smart pigs, with priority given to older pipelines.
According to a recent NTSB report, 61 percent of the nation's pipelines cannot physically accommodate pigs and it could cost companies about $12 billion to retrofit the nation's pipes to make them do so.
Weimer said only about 7 percent of the nation's pipelines are required to run smart pigs.
Sigman said Columbia plans to upgrade the exploded pipeline so it can accommodate a smart pig - when and if it reopens.
"I think they are going to upgrade it to where they can pig it," Sigman said of the pipeline.
But it will be a long time before the pipeline is back in service, Sigman said the company told him.
Columbia operates two other lines in the area.
The company does not believe the explosion harmed either of those two lines.
Both of the lines that did not explode had been pigged in 2009, Sigman said. (He had previously said the year was 2008.)
County officials and Columbia representatives met at 5 p.m. Monday to talk about the company's plan to restart the second of the two pipelines near the one that exploded.
A 30-inch line and 26-inch line are both within 200 feet of the exploded pipe.
The lines help supply demand to customers near Washington.
The 26-inch line, known as SM-86, was back in service the night of the explosion. It is 183 feet from the exploded pipe, according to a company plan.
"Pressure was restored slowly over a 2.5-hour period to verify the integrity of the pipeline," the company told the state Public Service Commission.
As it slowly put gas back into the line, the company had people patrolling the pipe by foot and by helicopter looking for leaks.
Columbia has developed a similar plan to return the 30-inch line known as the "SM-86 loop" to service on Wednesday.
That line is 53 feet north of the exploded pipe, according to the company plan.
The company said it could do so without closing either Interstate 77 or Kanawha 21 (Sissonville Drive).
The company had previously floated the idea of rerouting traffic in the Sissonville area while the company gradually refilled the SM-86 loops with gas. The state Department of Transportation was not a fan of the idea, which could have closed a major interstate for several hours the week before Christmas.
Columbia also hired Det Norske Veritas, an international risk management company, to study whether last week's explosion could have damaged the 30-inch line nearest the ruptured pipe.
The consultant, known as DNK, concluded it was unlikely the nearby pipe had suffered any damage.
Citing another report by the Pipeline Research Council International, DNK said, "a spacing of at least 25 feet, regardless of other factors such as pipe diameter, gas flow in the second pipeline, etc., is sufficient to reduce possible thermal damage to parallel pipelines." The nearby pipe was more than twice that distance from the ruptured pipe.
But the consultant said there was "finite, albeit small, probability that a near critical defect existed" just before the flow of gas was stopped to the pipe. Columbia shut off the flow of gas to all three pipes in the hour following the explosion.
"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," DNK cautioned.
Columbia said it was confident it could return its pipeline to service this week in a "slow and controlled manager, gradually increasing supply and pressure."
"In addition to performing the analysis to confirm that the incident did not affect Line SM-86 Loop in the vicinity of the incident, Columbia reviewed past inspection and testing data for Line SM-86 Loop to further ensure the safety of the pipeline," company spokeswoman Chevalier Mayes said in an email.
"A detailed review of these past inspections confirms that the lines are safe to return to service, and the data from these past inspections was reviewed in detail with representatives of the (state and federal pipeline regulation agencies)."
Some of the data for that analysis came from a smart pig inspection in 2009, Columbia told the state PSC.