Keystone XL workers laying pipe across the Canada-U.S. border. CALGARY – TC Energy Corp. says it has received regulatory approval to restart the remaining segment of the Keystone pipeline that has been shut down since a Dec. 7 oil spill. The Calgary-based pipeline company says the U.S. Pipeline and Hazardous Materials Safety Administration has approved a restart plan for the 154-km stretch of pipeline that runs from just south of Steele City, Nebraska to Cushing, Oklahoma. TC Energy Corp. shut down the 4,234-km Keystone pipeline system immediately after the spill, which saw 14,000 barrels of oil leak into a creek in Washington County, Kan. The company restarted most of the pipeline on Dec. 14, though the segment affected by the rupture has remained shut down. TC Energy says its restart plan will take several days and will include rigorous testing and inspections. The company has not provided a date for when the entire pipeline system will be fully operational again.