BISMARCK, N.D. (AP) — State health officials are working this week to verify that the recent spill of about 20,000 barrels of oil in northwestern North Dakota did not contaminate groundwater.
Tesoro Corp. found no contamination during earlier testing, but state crews were at the site near Tioga on Tuesday taking their own samples. Results were expected in a week or two, State Environmental Health Chief Dave Glatt said.
The company "collected one round and we're doing a follow-up, just to make sure the first (tests) were accurate," Glatt said. "We're up there now, collecting our own, to do a verification of what (Tesoro officials) are finding."
Glatt said state officials do not expect to find any groundwater contamination, and that there continues to be no indication of any harm to wildlife.
The pipeline rupture was discovered in a wheat field in September, and the oil spill covered an area the size of seven football fields. Federal regulators have said a lightning strike may have caused the rupture in the 6-inch-diameter steel pipeline, which runs from Tioga to a rail facility outside of Columbus, near the Canadian border.
The oil spill was one of the largest in North Dakota history.
San Antonio-based Tesoro restarted the pipeline on Nov. 1 under conditions set by the federal Pipeline and Hazardous Materials Safety Administration. Tesoro continues to work on cleanup, a process the company has said could cost $4 million.
About 5,000 barrels of oil have been collected. Much of the rest will have to be baked from the soil, and the soil renewed and replaced, Glatt said.
"They will need to revitalize it with natural bacteria and nutrients to make sure it's productive," he said.