During the last 10 years, there have been unparalleled levels of activity in dam and levee foundation remediation. This has been triggered mainly by the U.S. Army Corps of Engineers’ evaluation of their dam and levee portfolio following the disastrous flooding of New Orleans and surrounding areas in 2005. Remedial diaphragms walls have been in installed in dams in the US since 1975 when Wolf Creek Dam, in Kentucky, was repaired for the...

Dam failures typically result from interactions of human and physical factors which extend over years or decades. Understandably, engineers and others involved with dams normally focus on the physical factors. However, because physical systems such as dams are subject to physical laws and do not make ‘mistakes’, it may be asserted that dam failures (and incidents) are fundamentally due to human factors. The other side of this coin...

The field of hydrology experienced its most dramatic period of development from the late 19th century to the mid-20th century. While the theory and equations used to estimate watershed runoff have remained relatively unchanged since that time, the availability of Geographic Information Systems (GIS) software and geospatial data has modernized the methods used to evaluate watershed characteristics and develop input parameters. Today’s hy...

Slopes on the upstream side of dams are subject to wind-generated waves. Likewise, levees along river banks experience wind waves, boat wakes and current forces. This webinar will describe how winds produce waves in reservoirs and other enclosed bodies of water. Wave heights and periods resulting from winds blowing across the water surface will be calculated as a function of wind speed, duration, water depth and fetch distance. Wakes produced...

Event tree analysis is commonly used in dam safety risk analysis. Event trees are tools used to aid in understanding, analyzing, and communicating dam safety risks and for informing dam safety decisions. Like all other tools they are imperfect and their potential value depends on the skills of their user. Event trees can be used to obtain quantitative estimates of the probability of dam failure and its associated consequences. This can be don...

Plant and animal intrusions represent a common but often overlooked threat to the long-term safety of embankment dams throughout the U.S. In fact, these hazards have been attributed to dam failures and near dam failures in the past. Proper identification, treatment, and long-term management of these dangers are important to the overall health of embankment dams. This webinar will provide engineers, owners and dam safety officials with an unde...

The first geomembranes were installed on dams in 1959 in Italy and British Columbia: both systems were covered. In the 1970’s geomembranes began to be installed on dams exposed. In the next 20 years exposed geomembrane systems would be installed on more than 2 dozen dams primarily in Europe. The first exposed geomembrane system on a dam in the United States was installed in 1997. The United States now has the largest installed base of e...

Understanding how extreme storms and their precipitation are analyzed is critically important for dam design and dam safety. This webinar will detail the background of PMP and storm analysis starting with the earliest work completed by the US Weather Bureau (now National Weather Service) and continuing through current statewide and site-specific PMP work. Data and methods used to quantify rainfall spatially, temporally, and in magnitude will...

Changing demographics in the vicinity of dams have led to hazard creep in a number of dams worldwide. Many of these dams now have insufficient spillway capacity as a result of these changes in hazard classification from low to significant or high hazard. Stepped chutes applied to the embankment dams offer an advantage by providing increased spillway capacity. This webinar provides an overview on stepped chute research conducted at the USDA-Ag...

Failure mode evaluation or what now is more commonly referred to as potential failure mode analysis (PFMA) for dam safety has become routine practice for many in the profession. The process became more formally organized by the US Bureau of Reclamation in the early to mid 1990’s and gained wider industry exposure in the early 2000’s through the publication of FERC’s Engineering Guidelines, Chapter 14 – Dam Safety Perfor...