TransCanada estimated on Thursday that about 16,800 gallons of oil leak in a field in South Dakota from the Keystone I pipeline. The spill, discovered by a farmer over the weekend, led the company to close down the pipeline.
The company reported the estimate to the National Response Center and the Pipeline and Hazardous Materials Administration which is equivalent to 400 barrels of oil, according to the Associated Press.
The company began excavating the site on Sunday in a field close the town of Freeman, South Dakota, by turning over topsoil. It said they exposed more than 100 feet of pipe, and the estimate comes from oil being observed in the soil, and the potential area affected.