An eight-inch-diameter pipeline operating at approximately 700-pounds-per-square-inch ruptured, releasing a mix of ethane and propane. The record low temperature of 10°F for the region is believed to have contributed to the rupture. After a few minutes, the resulting release was ignited, causing a vapor cloud explosion. The explosion shattered windows up to six miles away and could be felt as far as 15 miles away. Seventeen additional pipelines, in a pipe rack containing 70 lines, were ruptured by the explosion.

The resulting fire involved two large storage tanks holding 3.6 million gallons of diesel, 12 small tanks containing a total of 882,000 gallons of lube oil, and two separator units. The explosion resulted in the partial loss of electricity, steam, and fire water for the refinery, since two power lines, two steam lines and a 12-inch diameter fire water line were located in this pipe rack. Upon the initial explosion, the lines for the dock fire pumps were damaged. Therefore, the water for fire fighting had to be supplied with the remaining plant fire pumps and municipal fire trucks taking draught from alternate sources. Approximately 48,000 gallons of aqueous film-forming foam (AFFF) concentrate, 200 fire brigade members, and 13 pumper units were used during the fire fighting effort, which was successful in extinguishing the fire approximately 14 hours after the initial explosion. Because of this incident, the refinery was completely shut down for three days and operated at reduced capacity for an additional three weeks.

[ Property Damage $69 Million. Estimated Current Value $155 Million ]

Image credit: Sam Kittner