Revisiting the Civil and Geotechnical Engineering Aspects of the 1889 South Fork Dam Breach and Johnstown Flood

Presented by

Michael Bennett, P.E., Gannett Fleming - Valley Forge, PA

The 1889 breach of the South Fork Dam, which caused the infamous “Johnstown Flood,” remains the deadliest dam failure in US history.  The dam was built in the mid-1800s as part of a transportation network across Pennsylvania, and its design and construction met the contemporary standard of care.  Decades of neglect, however, left the dam in disrepair until a group of Pittsburgh magnates hastily rebuilt it to create an exclusive lakeside resort.  The repairs were shoddy, but the elites ignored warnings of disaster.  On May 31^st, 1889, however, the dam overtopped after a rainstorm and breached.  The resulting tsunami-like flood wave inundated the steelmaking community of Johnstown and killed roughly 2,500 people.  Public outrage over the disaster was widespread, but the well-connected tycoons warded off legal and financial consequences and even compromised ASCE’s investigation of the failure.  Society, civil engineering, dam safety, and engineering ethics have all undergone major positive changes since 1889.  Yet the South Fork Dam saga remains a powerful reminder to civil engineers, particularly those in geotechnics, of their professional duties and responsibilities.