Dams & Civil Structures: An Examination of Dam Failures vs. Age of Dams

Some dam failures stem from long-term use, while other incidents are tied to earthquakes, floods, and other events. How are failures distributed over the life of a dam? And does a long period of satisfactory performance mean there will be no significant incident over the remainder of its life?


By Patrick J. Regan


Dam safety professionals must be ever vigilant in their efforts to assure the safety of dams and other water retention or control structures under their charge; whether owner, regulator or consultant, none can be complacent when it comes to dam safety.


And yet, all too often complacency creeps in when a dam has had a lengthy history of apparent successful operation. How many times have we heard, or used the words, "The dam's been OK for 50 years. Why are you worried about it now?"


During many Potential Failure Mode Analysis sessions conducted by the Federal Energy Regulatory Commission, this reasoning came up as a way to lower the categorization of a potential failure mode.


We seem to forget that dams are subject to many of the affects of aging and exposure that we are all subject to. Some failures are the result of long-term use. In humans, it may result in carpal tunnel syndrome; in dams, it may result in the failure of a gate hoist mechanism.


Some incidents are simply due to a longer exposure to a potentially hazardous situation.


Diseases like cancer may come on rapidly or progress over a long period of time. Similarly, piping can be a rapidly developing situation on first filling like at Teton Dam or a longer process such as at Kantale Dam in Sri Lanka that failed from piping after 117 years of, apparently, successful operation.