Oct 17 Tesoro Logistics LP detected
anomalies during an inspection of its 20-year-old North Dakota
pipeline just days before the line ruptured and spilled 20,600
barrels of oil onto farmland, the company said on Thursday.
The six-inch pipeline was carrying Bakken oil to the
Stampede rail facility outside Columbus, North Dakota, when it
ruptured. A farmer harvesting wheat discovered oil spouting from
the line on Sept. 29.
A robot, known as a "smart pig," detected anomalies during
what Tesoro called routine internal inspections of the pipeline
Sept. 10 and 11.
"We were awaiting results of the analysis of that inspection
when the leak was reported," Tesoro spokeswoman Tina Barbee
North Dakota regulators said corrosion on the pipeline may
have caused the spill.
The U.S. Department of Transportation's Pipeline and
Hazardous Materials Safety Administration was on site
investigating the spill despite the government shutdown over the
last few weeks.
The pipeline remains shut down while the federal regulator
looks 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 Shiffer, PHMSA's director
for Governmental, International, and Public Affairs.
The ruptured pipeline runs 35 miles from Tioga to Black
Slough in North Dakota. It was built by BP Plc in 1993.
It is a part of Tesoro's "High Plains" pipeline system in
North Dakota and Montana that gathers oil from the Bakken shale
and delivers it to another pipeline and to Tesoro's 68,000
barrels-per-day Mandan refinery.
Texas-based Tesoro bought the pipeline and the refinery from
BP in 2001.
The spill is the largest on U.S. soil since an Exxon Mobil
pipeline spilled 5,000 to 7,000 barrels of heavy
Canadian crude in Mayflower, Arkansas, last March.
It is the largest oil leak in North Dakota since hydraulic
fracturing unlocked massive oil reserves in the Bakken shale. In
August North Dakota produced more than 911,000 barrels of oil