A section of natural gas pipeline SM-80 is "hazardous to life, property and the environment," the Pipeline and Hazardous Materials Safety Administration found.
PHMSA, part of the U.S. Department of Transportation, issued a corrective order to Columbia Gas, a subsidiary of NiSource, detailing how the company can suitably repair part of that pipeline which exploded Dec. 11 near Sissonville. Columbia has 10 days within receipt of the order to request a public hearing.
According to the order, the rupture and fire occurred about 4.7 miles downstream from Columbia's Lanham Compressor Station near Sissonville at approximately 12:43 p.m. About an hour after the rupture, the Rocky Hollow and Lanham valves that controlled gas flow through the pipeline were manually shut off. Currently, the failed 15-foot section of SM-80 is blocked off at upstream and downstream block valves and has not been repaired or returned to service.
Line SM-80 was originally installed in 1951 as a 26.2 mile section between Lanham and Broad Run. In 1955, the line was extended from Lanham to Leach. Since then, various parts of the line have been replace, resulting in a line with a hodge-podge of sections of various ages, the newest of which stems from a 1992 project.
Columbia operates two additional pipelines, SM-86 Loop and SM-86, which run parallel to SM-80. Following the explosion, service from the Lanham Compressor Station to Patterson Fork was stopped as a precautionary measure. Line SM-86 lies about 183 feet from the affected pipe. Independent engineering firm Det Norske Veritas and Columbia determined the incident did not affect SM-86 and pressure to the line was slowly restored. SM-86 was returned to full service early the following morning. No leaks were detected on line SM-86.
However, line SM-86 Loop lies about 53 feet from the affected line. DNV and Columbia concluded that line was not affected by the SM-80 rupture, but because the lines were in close proximity, Columbia developed a return to service plan, which was successfully implemented Dec. 19.
Both the Office of Pipeline Safety and the National Transportation Safety Board, which investigated the blast, found that portions of SM-80 were corroded and had too thin walls. The OPS has preliminarily determined wall thinning was a major contributor to the blast.
The affected part of SM-80 was constructed in 1967. Preliminary data from the pipe at the point of the rupture shows a general wall thickness of 0.281 inches, 20 inches in diameter and has an electric resistance weld long seam.
The required corrective action comes in four phases. Phases one and two focus on returning the line to restricted operation and long term assessment and remediation. Phases three and four look at how to summarize the work and requires monthly and quarterly reports including all available data and results of testing and evaluations.
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