The Great Boston Molasses Flood (or Boston Molasses Disaster) was an engineering disaster that occurred on January 15, 1919 in the North End neighbourhood of Boston. At 12:30p.m. a 2.3 million gallon storage tank (built by U.S. Industrial Alcohol) containing molasses failed, causing the molasses to flow through the streets at 35 miles per hour. Twenty-one people were killed (2 of which were children) and 150 injured because of the disaster. 
The Cause of the DisasterEdit
There were many problems that led to the failure of the storage tank. The most noticeable being the poor factor of safety in the tank design. It was found that every plate used to make the storage tank had a smaller thickness than what was recommended in the plans. It was also found that an insufficient number of rivets were used to secure the tank. Damon Hall (the plaintiff's attorney) stated that "… they (U.S. Industrial Alcohol) were like all other steel manufacturers in the country, hurrying to fill war orders, and in every instance, they furnished steel less than the specs called for". 
It was also found that Arthur Jell (supervisor of the project) had no engineering expertise and was not fit for the job. He was not educated enough to understand the harm that can occur by taking short cuts. This could be seen in his decision to not do a leak test of the storage tank (by filling the tank with water) which would have exposed many problems. 
Impact of the Disaster
Many changes to the engineering profession were implemented due to the Boston Molasses Flood. The Boston Building Department required that all drawings with a stamp/seal had to be signed by an engineer and calculations had to be submitted with each set of plans. Requirements for an engineering licence were also implemented in Massachusetts. 
The Boston Molasses Flood is often credited as the catalyst for municipalities across the United States to require "all plans for major structures to be sealed by a professional engineer".
 Engineering Ethics: The Great Boston Molasses Flood accessed March 5, 2013 from PDHengineer.com (PDH Engineer, 17350 State Highway 249, Houston, TX 77064)