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...

The implementation of a successful dam design is predicated on the construction contractor using acceptable construction means and methods when perform the work and the quality control staff performing timely and through inspections. There are many critical work items associated with dam construction which, if not performed correctly, will lead to poor performance, reduced service life, and contribute to potential failure modes. This webinar...

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...

This webinar covers the use of sand and gravel filter/drainage systems in embankment dams to protect against excessive seepage pressures, internal erosion in cracks or other anomalies, and piping. Excessive seepage pressures can affect embankment stability related to slope sloughing or failure and piping from progressive removal of soil forming a tunnel feature in or under the embankment. Many seepage issues in dams involve the development of...

This webinar will provide participants with information on the importance of preparing operations and maintenance (O&M) manuals for dams. It will include an overview of some of the key federal agency and state requirements and formats for dam O&M manuals. Operations and maintenance guidelines will be presented for both embankment and concrete dams and key dam appurtenances, such as spillways and outlet works. Many examples will be prov...

Quality control on projects for the construction or rehabilitation of dams is the responsibility of the construction contractor. Contractors have control of the site during construction and are responsible for understanding and complying with the requirements of the contract documents. It would be remiss on the part of the owner however, to solely rely on the contractor for this task. To verify contract compliance, construction of complex and...