Re-Examination and Lessons Learned From the 2004 Failure of Big Bay Dam, Mississippi

Big Bay Dam is a 57’ tall, approximately 2000’ long, earthen embankment dam located in south central Mississippi (Figure 1). The construction of the dam in 1990-1991 created a 900-acre lake with a storage capacity of more than 11,000 acre-feet, which is primarily used for recreation. The original dam breached on March 12, 2004 due to piping/internal erosion mechanisms that occurred over a period of years. The final stages of the failure took less than 24 hours.

The failure destroyed 48 homes, washed out a bridge, and damaged 53 homes, 2 churches, 3 businesses, and a fire station. Thankfully, no lives were lost. The primary failure investigation report, prepared by the lead engineer for the original design of the dam, concluded that the dam had failed by piping through the foundation.

As a result, many people were led to believe that the dam failed in less than 24 hours by piping through the foundation without any previous signs of distress. This misconception resulted in discussions in late 2012 between the State of Mississippi and the ASDSO Dam Failures and Incidents Committee about how the ‘real story’ of Big Bay could be determined and how the Committee’s 2011 Dam Failure Investigation Guidelines could be tested in the process. The authors then made an extensive effort to investigate the failure, including evaluating all available documentation and performing a visit to the site in 2013. The results of this effort were presented in an in-depth technical paper and presentation which evaluated the failure in a potential failure modes analysis framework. This paper was presented at the 2014 United States Society on Dams Conference. Two additional papers and a Soapbox Session to discuss lessons learned from the failure were presented at the 2014 ASDSO national conference. This article summarizes that work, emphasizing the many distress indicators and other warning signs extending back to the construction of the dam, as well as lessons learned as a culmination to this investigation process.