I studied this incident closely while at MSU and I have never forgotten the dramatic images of what 18,000 gallons of a flammable liquid can do in a sewer!
On Feb. 13, 1981, at 5:16 a.m. a series of explosions occurred in the sewer lines of Louisville, KY. The explosions happened after a soybean extraction plant had a chemical spill of hexane which made it to the sewer. Ultimately investigators estimated the spill was 18,000 gallons of hexane which made it’s way into the Louisville sewer system. Officials said the leak lead to a series of explosions along 13 miles of sewer lines throughout the city. At the time of the incident, the director of the city works cabinet, estimated private property damage exceeding $25 million and “inestimable” damage to underground utilities.
The main explosion damaged streets, businesses, and underground utilities (namely sewers where the vapors were present) in an area 15 blocks wide and 14 blocks long and a series of minor explosions continued to occur three (3) hours after the original explosion and up to 10 blocks from the original damage scene. At 3:45 pm, the last explosion occurred, blowing out a manhole cover at the intersection of Second Street and Burnett Avenue.
The soybean extraction 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, a large quantity of hexane was released into the sewers. The hexane began to vaporize in the sewers. At about 1:30 a.m. on the day of the explosions, the company called an inspector and informed him that there had been some leakage from the facility. The inspector visited the site and checked for vapors on some nearby streets but did not notice a serious problem; the circumstances surrounding the visit by the inspector and the amount and type of information given to him were disputed.
It took 20 months to repair the sewer lines, and another several months to finish the work on the streets. Ralston-Purina pleaded guilty to four counts of violating federal environmental laws and paid a fine of $62,500. In February 1984, the company agreed to pay the Metropolitan Sewer District more than $18 million in damages. Many millions more were paid to other government agencies and private individuals who suffered damage.