It was the second largest oil spill in the history of Western Pennsylvania and one of the worst inland oil spills in the nation. According to Coast Guard statistics, as reported by the New York Times, only a 14 million gallon spill into the Delaware River in 1975 and a 2 million gallon spill after an explosion in Brooklyn the next year involved larger quantities.
At the time U.S. Sen. Arlen Specter called the Monongahela oil spill “a super, major spill.”
On January 2, 1988, a 3.8-million gallon diesel oil tank collapsed and failed, dumping an estimated 1 million gallons of diesel fuel into the Monongahela River in Floreffe, Pa., 18 miles south of Pittsburgh; 2.5 million gallons were trapped by retention dikes around the riverside storage area, forming a pool of oil. River traffic on the busy Mon stopped.
The tank burst at 5:10 p.m. at the Ashland Oil Inc. storage area as it was being filled, threatening wild life and drinking water supplies for about 1 million people in more than 80 communities across three states. After the rupture, “the tank looked like someone stepped on a marshmallow.”
The 6-inch-thick slick, spreading bank to bank had grown to 33 miles long as it flowed past Pittsburgh’s Point State Park and 10 miles up the Ohio River.
The spread of the fuel was unstoppable; foot by foot it moved forward, conquering the water surface of the Mon and carrying it all the way to the Ohio River, reporters described the asphyxiating smell of diesel fumes in the air.
As the Associated Press reported at the time, “approximately 23,000 suburban Pittsburgh residents lived for a week without tap water while the river carried the pollution past their water intakes.”
Federal agencies in collaboration with local authorities used 20,000 feet of boom and barges to contain the spill and deflect the fuel. Cold January temperatures impeded the cleanup process by not only creating the mechanical issues with the equipment but also causing hypothermia and increasing the probability of contamination because oil emulsified faster in the cold.
Following a federal investigation which concluded that Ashland violated the industry standards when they had reconstructed the tank in Floreffe the Federal Government made Ashland pay $2.25 million in fines and cover cleanup fees, which together with compensations to the distressed communities, amounted to $18 million.