Cahokia Creek and Mississippi River.

​​Cahokia Creek and Mississippi River.

Marathon Pipe Line LLC Pipeline Rupture and Crude Oil Release

What Happened

​On March 11, 2022, at 8:15:21 a.m. local time, a 22-inch diameter crude oil pipeline operated by Marathon Pipe Line, LLC ruptured at a girth weld in Edwardsville, Illinois, resulting in the release of about 3,500 barrels of crude oil, some of which entered Cahokia Creek. The rupture occurred at milepost 6.2 on the Woodpat pipeline, and no injuries or fatalities occurred as a result of the rupture.

What We Found

​We determined that the probable cause of the Edwardsville, Illinois, crude oil pipeline rupture was an overstress fracture of a girth weld from external loads caused by slope instability that had not been completely mitigated by Marathon before the accident.​