Scientists who determined the amount of oil spilled in the 2010 BP disaster have questioned the methods used to estimate the North Dakota wheat field spill.Tom Stromme/AP
North Dakota Gov. Jack Dalrymple announced a new oil spill Thursday night, the same day he met with an oil company official amid suggestions that the company may have known about problems with a pipeline before a 20,000-barrel spill last month.
Tesoro Logistics inspected its 20-year-old pipeline for anomalies over two weeks before it ruptured, spilling 20,600 barrels of oil onto a wheat field on Sept. 29, the company said Thursday. Tesoro, however, said it was still waiting for the analysis from the investigation when the accident occurred.
The second leak, from a one-inch oil gathering line in Divide County, made public Thursday was first estimated at 150 barrels, but was later reduced to 5-7 barrels citing an error in the preliminary report.
The governor’s office said the spill would be closely monitored, because it’s near a wetland in the northwestern part of the state.
News of the smaller spill comes on the heels of a Wednesday announcement by chief of the state Department of Health’s environmental health section, Dave Glatt, that said Tesoro may have been aware of “anomalies” in the pipeline ahead of the Sep. 29 spill.
“We have heard they may have found some anomalies in the metal but not necessarily holes,” Glatt told The Associated Press. “We have heard there were some potential problems identified.”
Tesoro did not share the data of recent pipeline tests with health officials, Glatt said.
September’s spill is the largest on U.S. soil since an Exxon Mobile pipeline spilled 5,000-7,000 barrels of heavy Canadian crude in Mayflower, Arkansas, last March.
In a statement to the AP, Tesoro said it inspected the pipeline about two weeks before the spill was reported, using a robotic device called a “smart pig” that travels through a pipeline to search for corrosion and other problems.
“We were awaiting results of the analysis of that inspection when the leak was reported,” Tesoro said.
According to documents obtained by the AP, a state inspector said in an email to health officials that a Tesoro official had told him the company “had the results of the pipeline inspection for several months.”
Tesoro has said that the hole in the 20-year-old pipeline was a quarter-inch in diameter but have not speculated on what caused it.
Oil spill estimate questioned
State officials have said the spill may have been caused by corrosion. Unconventional crude, the type of oil from tar sands and shale that is transported in the pipeline, is thought to be more corrosive than conventional oil.
Dalrymple has called on Tesoro to make improvements in monitoring equipment, and met with a company official the same day the second spill was announced.
The governor told Tesoro’s Senior Vice President of Operations Dan Romasko the company should go above and beyond federal requirements and suggested installing “real-time” pipeline monitoring technology.
“We expect high standards from North Dakota’s energy industry, and I expect timely responses from Tesoro Logistics to the many unanswered questions that remain in order to prevent this from ever happening again,” Dalrymple said in a press release.
Tesoro said they would start by setting up a website, due up Friday, to communicate more effectively with the public. North Dakota has no laws requiring public notification of spills.
Scientists who helped calculate oil spilled from a broken BP well in the Gulf of Mexico have questioned Tesoro’s methodology for estimating the amount of crude that spilled in North Dakota.
Tesoro said it came up with its spill estimate using ground analysis. But oil experts say a more accurate assessment would come from calculating how much crude went into the pipeline versus what they were able to estimate at the end.
Purdue University engineering professor Steve Wereley said Tesoro’s calculation of how much oil it released is “at best, a guess.”
Werely, who along with other scientists helped estimate the amount of oil spilled in the Gulf in 2010, said he was unaware of any scientific studies that could back Tesoro’s estimates. Werely and Ian MacDonald, a Florida State University oceanographer who also worked on spill estimates in the Gulf, said detailed oil flow data from the pipeline would provide regulators with a better estimate of the crude that spilled.
MacDonald said properly estimating the size of an oil spill “is not trivial.”
“Both the environmental impact and the liability of the company are directly related to the precise amount of release,” MacDonald said. “That is why it is critical to know.”
The pipeline remains shut down while federal regulators look into how Tesoro responded to the spill, its control-room processes and records and whether non-compliance contributed to the pipeline’s failure, said Jeannie, the U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration’s director for Governmental, International and Public Affairs.
The ruptured pipeline was built by BP in 1993 and was bought by Texas-based Tesoro in 2001. The pipeline runs underground about 35 miles from Tioga to a rail facility outside Columbus — near the Canadian border.
Al Jazeera and agencies