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.