An aerial view of workers using heavy equipment in an attempt to contain a 20,000 barrel crude oil on the Jensen farm near Tioga. Trenches filled with oil wait to be picked up. A Tesoro Logistics LP pipeline spilled from a ruptured six-inch (15 cm) pipeline into a wheat field, the biggest leak in North Dakota since it became a major U.S. producer. The pipeline carries crude oil from the Bakken shale play to the Stampede rail facility outside Columbus.