Massive 2013 oil spill in North Dakota finally cleaned up

Five years and almost $100 million later, cleanup is complete on a massive oil pipeline leak in North Dakota that has been called one of the biggest onshore spills in U.S. history, industry and state officials said Wednesday.

FILE - This Oct. 11, 2013, file photo shows cleanup at the site of a Tesoro Corp. pipeline break that spilled more than 20,000 barrels of oil into a Tioga, N.D., wheat field. Nearly five years after a North Dakota farmer discovered oil oozing into his wheat field, cleanup of what turned out to be a massive spill is nearly complete. It cost almost $100 million to excavate and clean the soil devastated by the pipeline break that may have been caused by a lightning strike. [Photo: AP/Kevin Cederstrom]

The spill by Tesoro, now known as Andeavor, was found by a Tioga farmer in September 2013. Crews had been working around the clock to clean it.

Farmer Steve Jenkins had smelled the crude oil for days before discovering the spill in his wheat field after his combine's tires were covered in it.

Steve Jensen poses for a photo near the site of an oil spill he discovered outside of Tioga, N.D., on Friday, Oct. 11, 2013. Officials took nearly two weeks to tell the public about the break in a Tesoro Corp. pipeline that happened in a remote area of North Dakota. Officials say no water was contaminated and no wildlife was hurt. Jensen was harvesting wheat when an oil pipeline leak was discovered. [Photo: AP/Kevin Cederstrom]

Patty Jensen, Steve's wife, said the cleanup's finish has "lifted a weight off our shoulders."

She said her husband began planting a mixture of sweet clover, grass, and winter rye last week as a cover crop to keep the soil in place on the affected area that she estimated at about 70 acres (29 hectares), or a little less than the size of 70 football fields.

The spill was not far from where oil was first discovered in North Dakota in 1951. The Texas-based company and regulators have said a lightning strike may have caused the rupture in the 6-inch (15-centimeter) diameter steel pipeline, which runs from Tioga to a rail facility outside of Columbus, near the Canadian border.

North Dakota regulators initially thought just 31,500 gallons (26,230 imperial gallons) of oil was involved in the spill, but later updated the amount exponentially.

Health Department environmental scientist Bill Suess said less than a third of the 840,000 gallons (699,450 imperial gallons) that spilled was recovered. The remaining oil was cooked from the soil in a process called thermal desorption.

Suess said about 1.4 million tons (1.3 million metric tons) was excavated from the site and treated. Crews had to dig as deep as 60 feet (18 meters) to remove oil-tainted soil. No water sources or wildlife was affected, he said.

Suess said the site will be monitored by the company and the state for up to five years.

The company originally thought it could clean up the site in two years for about $4 million. It later estimated the cost at $93 million.

The state fined the company $454,000 for the spill.