As Enbridge prepares to resume crude shipments through its massive Line 6A, a federal U.S. investigator said the section of pipe that ruptured showed evidence of "poor" construction practice.
Crude shipments through the 670,000 barrel-per-day line were halted last week, when a major leak spilled 6,100 barrels into a Romeoville, Ill., industrial park. An investigation points to lapses in building a protective barrier around the burst line, but it's not clear Enbridge is to blame.
Enbridge has informed U.S. regulators that it will re-open the pipe Friday morning, and that deliveries to refineries will resume almost immediately. The company has not been required to seek regulatory permission to re-launch operations, since it has not been ordered to submit a formal restart plan by the Pipeline and Hazardous Materials Safety Administration.
PHMSA regulates the industry and has, so far, refused to allow Enbridge to restart Line 6B, a different pipeline that leaked 19,500 barrels into a Michigan river system in July. Investigators have said corrosion is a likely cause of that leak, and lawmakers have criticized the company for hundreds of unresolved "defects" on that line. Enbridge, however, said many of those may simply be anomalies, and inspections typically show that many require no repairs at all, said Steve Wuori, Enbridge's executive vice-president of liquids pipelines.
The Illinois leak appears to have happened for a completely different reason. Preliminary findings released Thursday by Matt Nicholson, an investigator with the National Transportation Safety Board, reveal that the Enbridge pipe was buried beneath a roadway just 13 centimetres from a municipal water line. The normal Enbridge separation standard is 45 centimetres.
The area between the two pipes was also littered with rocks, some the size of basketballs, which Mr. Nicholson called "poor practice." Pipeline companies usually surround their infrastructure with materials that will not damage the pipe.
"It's alarming to find rocks of that size directly below that line," Mr. Nicholson said.
It's unclear who was at fault for the construction of the crossing, although Mr. Nicholson said the best current information indicates the municipal water line was built nine years after the Enbridge oil pipeline.
While Mr. Nicholson would not conclude the rocks caused the leak until his investigation is complete, he said the Enbridge line was punctured, and that his initial examination suggests corrosion was not an issue.
The nearby water line also burst, and while investigators say it is only a theory, it's possible the pressure from the ruptured water line also punctured the Enbridge line.
It's also possible that heavy traffic played a role, since the two lines leaked beneath a road.
"It is known that this line is directly outside a company that makes heavy blocks, and they run trucks in and out of that facility that weigh anywhere from 70,000 to 75,000 lbs [32,000 to 34,000 kilograms]" Mr. Nicholson said. "So yes, there is heavy traffic in the area, and that will be looked at as well."