The Louisville sewer explosions were a series of explosions that destroyed more than two miles (3 km) of streets in Louisville, Kentucky, United States on February 13, 1981.
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The blasts were caused by the ignition of hexane vapors which had been illegally discharged from a Ralston Purina soybean processing plant located near the University of Louisville. The plant, located on Floyd Street, was long recognizable for its large, landmark silos, visible from Eastern Parkway and Interstate 65 until the site's demolition in 2014.
There were no fatalities, but Ralston Purina paid $18 million to the Louisville Metropolitan Sewer District and more than $8.9 million to 16,000 plaintiffs in a lawsuit settled in 1984. The company admitted that it released hexane into the sewers, but denied negligence.
The event
The Ralston Purina plant used hexane as a solvent to extract oil from soybeans. The plant employed a containment system designed to recycle used hexane from the process back to the plant. However, the containment system was not functioning that night, and a large quantity (estimated to be between several hundred and several thousand gallons) of hexane was released into the sewers. The hexane began to vaporize in the sewers and slowly began to seep out of manholes in the streets.
At approximately 5:16 a.m. on Friday, February 13, 1981, explosions ripped through the southern part of Old Louisville near the University of Louisville. The cause of the explosions was eventually traced to a spark from a car near the intersection of 12th & Hill Streets, which ignited the hexane fumes in the sewers. The car was thrown onto its side from the force of the blast, and there was extensive damage to area homes, businesses, and streets. Police officers in a police helicopter that happened to be over the area at the time said it looked like a bombing run. Two miles (3 km) of the main sewer line were completely destroyed in the blast. Water lines were severed, leaving area residents without water for weeks. Luckily, the streets were nearly deserted since it was early in the morning, so no fatalities were reported.
Aftermath and legacy
In 1985, the city of Louisville and Jefferson County, Kentucky passed a hazardous materials ordinance in response to the disaster. This ordinance gave the Louisville Metropolitan Sewer District the authority to regulate the handling of hazardous materials.
The incident has been cited by such entities as the American Society of Civil Engineers and the U.S. Government Accountability Office as an example of the need for increased security concerning the United States' wastewater systems, and by the United States Environmental Protection Agency as an example of the dangers associated with discharges of hazardous waste to sewer systems. Articles discussing the event have been published in Environmental Geology and Journal of the American Oil Chemists' Society.