CHARLESTON, W.Va. (AP) -- Severe corrosion caused a 2012 natural gas pipeline rupture and explosion in West Virginia that destroyed three houses and cooked a stretch of Interstate 77, and the incident likely could have been prevented if the pipeline had been inspected or tested, the National Transportation Safety Board said in a report released Monday.
Investigators found severe external corrosion that reduced the thickness of the pipeline wall to about 30 percent of its original thickness. The 20-inch buried pipeline, which was installed in 1967, had not been inspected or tested since 1988, the report said.
Columbia Gas Transmission Corp.'s response to the rupture was delayed by inadequate configuration of alerts and the lack of automatic shut-off or remote control valves, the report said. Columbia owns and operates the pipeline.
Prior to the rupture, the company's supervisory control and data acquisition system issued a series of alerts over a period of about 12 minutes indicating that pressure in the pipeline was dropping. The controller at Columbia's control center did not recognize the alerts' significance and did not begin to shut down the system until a controller with another pipeline company called and reported a possible rupture.
No one was seriously injured when the pipeline ruptured on Dec. 11, 2012, and the gas ignited and exploded about 100 feet west of I-77 in Sissonville. The rupture released more than 76 million standard cubic feet of natural gas, which burned. Fire damage extended nearly 1,100 feet along the pipeline right of way and the blast hurled a 20-foot section of pipe more than 40 feet.
Automatic shut-off valves would have reduced the fire's duration, the report said.
The NTSB recommended that Columbia modify its supervisory control and data acquisition system to provide operating trend data that the controller can use to evaluate the significance of a change. Trends that are likely significant system malfunctions should have an alarm function assigned to them, the report said.
The board also recommended that the company provide guidance to pipeline controllers regarding evaluating and responding to alerts.
Katherine Dupuis, a spokeswoman for Columbia, said the company is reviewing the report.
"We are committed to operating safely and doing whatever we can to ensure that will be the case," Dupuis said.
The NTSB said in the report that it is concerned about gas transmission pipelines located near arterial roadways. It recommended that the Pipeline and Hazardous Materials Safety Administration add interstates and other arterial roadways, such as expressways and freeways, to its list of sites identified as high consequence areas, which require more stringent inspections.
"The Sissonville pipeline rupture caused major damage to I-77. An intense fire raged directly across the interstate for nearly an hour. Had the accident occurred during commuting hours, when traffic would have been significant, severe or fatal injuries could have occurred," the report said.
Closing arterial roadways for several hours can significantly affect first responders, commuters and commerce, the report said.