CHARLESTON, W.Va. -- The natural gas pipeline that exploded last month near Sissonville was spared heightened safety scrutiny because of its size, the nation's top pipeline regulator said Monday.
The 20-inch diameter transmission line that exploded was not in what federal regulators considered a "high consequence area," even though two pipelines owned by the same company and within a stone's throw of the exploded line were.
When the line exploded on Dec. 11, it destroyed three homes, damaged several others and scorched Interstate 77 -- miraculously killing no one.
Because it was not "high consequence," the exploded line did not have to be checked for corrosion using one important pipeline safety tool. The tool -- known as a "smart pig" -- travels through a pipeline to check the pipe for irregularities, including cracks and corrosion. The tool could perhaps have found that the exploded line had corroded in places to about a third of the thickness it ought to have been.
Other details emerged about the explosion during a special hearing of the Senate's commerce committee on Monday in Charleston's federal courthouse. Sen. Jay Rockefeller, D-W.Va., is the committee's chairman and convened the special hearing here.
But Rockefeller and Sen. Joe Manchin, D-W.Va., both at times focused on the scrutiny pipelines receive.
Columbia Gas Transmission, a subsidiary of Indiana-based NiSource, owned the 20-inch line. It also owned a 30-inch pipeline 53 feet to the exploded pipeline's north and another 26-inch pipeline within 200 feet of the exploded pipeline.
Those two larger pipelines were considered to be in high consequence areas because of an equation that regulators use.
"If there are 20 residences within a bubble, it is considered a high consequence area," said Cynthia Quarterman, the head of the U.S. Pipeline and Hazardous Materials Safety Administration.
One key factor in the equation to calculate the size of the bubble is the diameter of the pipeline.
The 20-inch pipeline's bubble extended 495 feet away from the pipe in all directions, while the bubble extended 626 feet from 26-inch line and 713 feet from the 30-inch line. The two larger bubbles included nearby homes, while the smaller bubble did not, according to a chart prepared by federal regulators. Because the bubbles included more people, the two larger lines faced more scrutiny.
Quarterman said the agency is "very, very seriously" considering making changes to its rules for calculating high consequence areas.