THURSDAY, NOVEMBER 7, 2013
Lightning may be to blame for a pipeline hole that leaked 20,000 barrels of crude oil in North Dakota, new reports say.
Earlier reports speculated corrosion as the cause of the Sept. 29 pipeline failure outside of Tioga, ND, but a preliminary mechanical and metallurgical analysis report points to a "strong electrical discharge."
However, the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration has not made a final determination.
A farmer discovered the pipeline failure when he was harvesting his crops and noticed oil seeping from the ground.
The six-inch pipeline segment is part of a 35-mile pipeline owned by San Antonio-based Tesoro Logistics LP. Part of the 700-mile Tesoro High Plains System, the pipeline runs from Tioga to Black Slough in North Dakota and was installed by BP Plc in 1993. Tesoro bought the pipeline and refinery from BP in 2001.
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| Kiefner & Associates |
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A "strong electrical discharge," possibly from lightning, caused a hole in a North Dakota pipeline, leaking 20,000 barrels of crude oil. |
PHMSA has since issued a Safety Order to Tesoro and allowed the pipeline to restart on Nov. 1.
The North Dakota State Health Department didn't publicly announce the spill until 11 days later; officials said they had thought spill was small—about 750 barrels. It was later determined that the spill spewed an estimated 20,000 barrels of oil over 7.3 acres of land, making it one of the largest spills in the state's history.
Tesoro Reports
Tesoro published a preliminary report prepared by Kiefner & Associates Inc., which provides engineering services to pipeline operators.
"The leak was caused by an electrical discharge that resulted in localized heating of the pipe wall above the melting point of the steel," the report said.
A 10/32-inch-diameter hole was left in the pipe wall, according to the report.
The source of the electrical current has not been identified. However, Tesoro's report said that sections of the metal had been melted and resolidified, "which is consistent with an electrical discharge event, such as a lightning strike or contact with an AC power line."
The failed section of the pipe, which was had a two-layer polyethylene coating system, has been sent to a laboratory for metallurgical testing, and an initial lab report did not indicate any signs of corrosion or other defects at the failure location, according to Tesoro.
According to the report, the coating system appeared to be in good condition and would have been expected to act as an insulator, preventing the current from easily flowing on or off the pipeline. A well-coated pipeline would allow a current to travel a "significant distance" before finding a path to ground, "such as at a coating fault or a variety of pipeline appurtenances."
"Lightning could be the source, but the metallurgical examination will look at all possible factors that may have caused the failure," Damon Hill, a PHMSA spokesman, told Reuters.
"It's possible [lightning] could have struck the pipeline or another conduit near the pipeline, such as a fence," Hill said, according to The Washington Post.
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| Tesoro Logistics LP |
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Tesoro is using interception trenches as collection sumps to contain and capture oil. As oil drains from the soil, it collects in the trenches, allowing it to be recovered, the company explained. |
A new seamless, fusion bonded epoxy-coated pipe has been installed and tested, and pressure and flow detection systems have been installed, according to PHMSA.
PHMSA has also required the company to conduct mechanical testing and failure analysis and evaluate previous inspection results. According to Tesoro, the segment was internally inspected with smart pig technology in 2005 and again in September 2013. The company was waiting for the results of the September inspection when the leak was reported.
Safety Order Issued
On Oct. 31, PHMSA issued a Safety Order to Tesoro, ordering the company to complete short- and long-term system-wide improvements. After evaluating the age of the pipe, the manufacturer, and other characteristics, PHMSA said the pipeline has "a condition or conditions that pose a pipeline integrity risk to public safety, property, or the environment."
"Safety is our highest priority," U.S. Transportation Secretary Anthony Foxx said in a press release. "Today's Safety Order is an important step to protect the people and environment in this area and to strengthen the integrity of the pipeline so that something like this doesn't happen again."
"PHMSA is committed to improving safety and environmental protection for the nation's pipeline systems," said PHMSA Administrator Cynthia Quarterman. "This Order requires Tesoro to apply its resources to address any potential future risks to property and to the environment."
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| Greenpeace / Neal Lauron |
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North Dakota officials did not publicly announce the oil spill for 11 days, saying they thought it was a smaller spill of around 750 barrels. |
The order requires the company to:
Tesoro will be required to submit a monthly report on the status of each item.
'Unacceptable'
Tesoro previously said that it expected remediation to cost $4 million and an internal investigation was underway to determine the cause.
"We deeply regret our recent crude oil spill north of Tioga, North Dakota. This type of event is unacceptable. We take full responsibility and will make the situation right," Dan Romasko, COO of Tesoro, said in a statement.
The company said that there have been no injuries or known impacts to water or wildlife.
At a meeting with North Dakota legislators on Oct. 31, state Department of Health Official Dave Glatt told the Energy Transmission and Development Committee that a new website to alert the public about hazardous leaks and oil spills will likely go online within the next month.
According to the Grand Forks Herald, the department was already considering making the website before the pipeline spill, but the incident accelerated the timeline.
Tagged categories: Accidents; Coating failure; Corrosion; Failure analysis; PHMSA; Pipelines; Program/Project Management
