TC Energy shut the pipeline after the spill was discovered late last Wednesday. The 622,000 barrel-per-day Keystone line ships heavy Canadian crude from Alberta to refiners in the U.S. Midwest and the Gulf Coast. Prices for sour crude grades in the U.S. Gulf of Mexico were strengthening on Monday, as the shutdown means more demand for heavier Gulf barrels. TC Energy said on Sunday that it has more than 250 people working on the leak, including third-party environmental specialists. The U.S. Environmental Protection Agency and pipeline regulator the Pipeline and Hazardous Materials Safety Administration (PHMSA) are also on the scene.

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