The U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration issued a corrective action order to Exxon following the failure of the Pegasus oil pipeline last week in Mayflower, Ark.
"The order prevents Exxon Mobil from restarting operations on the failed segment until the agency is satisfied with repairs and is confident that all immediate safety concerns have been addressed," the agency said.
PHMSA describes Pegasus as a 20-inch diameter pipeline build in the 1940s. Exxon reversed the direction of the pipeline so it flows from Illinois to Texas in 2006.
The agency's order states that Exxon reported a failure March 29 and estimated at least 3,500 barrels of crude oil spilled from the pipeline. The company learned of the failure after a drop in pressure from the pipeline was reported. Valves isolated an 18-mile section of the pipeline within 16 minutes of the pressure drop and the entire line remains shut, PHMSA stated.
Exxon said it's started to develop plans to clear the affected portion of the pipeline.
Around 12,000 barrels of oil and water have been removed from the site of the spill.
Arkansas Attorney General Dustin McDaniel requested that Exxon preserve documents related to the incident "for any future litigation."