The Keystone Pipeline resumed operations Monday at a reduced pressure as cleanup efforts continue from an oil spill in North Dakota.

The Pipeline and Hazardous Materials Safety Administration said it approved operator South Bow’s plan to restart the pipeline, after a corrective action order issued by the federal regulators.

The company shut down the Keystone Pipeline on April 8 after a drop in pressure. South Bow later estimated that about 3,500 barrels, or 147,000 gallons, of oil spilled in a farm field near Fort Ransom. The spill was contained to the field.

The failed section of pipe was excavated and replaced, according to a statement from PHMSA. The failed section will be sent to Houston for testing.