"On March 25, 2010, there was a release of 1700 barrels of Vacuum Gas Oil (VGO) from the FM-1 pipeline into an open in-ground valve pit and the surrounding area in the West Yard of the Sunoco, R&M Philadelphia refinery in Philadelphia, PA. The cause of the release was a failure of a flange gasket downstream of a main line valve in a dead leg of pipe leading to the FM-1 pig trap. Loss of pipe support and leakage through a closed valve contributed to the failure. There were no fatalities or injuries, and the incident did not result in a fire, explosion or evacuation. The flange gasket failed during a shipment of VGO between the Schuylkill River Tank Farm (SRTF) and the North Yard (NYOM) of the Refinery. The flange and pipe headers were located in a holding pit which overflowed during the release but was contained within the West Yard facility."
Pipeline and Hazardous Materials Safety Administration: http://phmsa.dot.gov/