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...

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...

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...

Earthquakes represent a hazard to dams in many parts of the United States and therefore are of interest to design engineers and dam safety officials. The hazard from earthquakes includes strong shaking, fault rupture displacements, reservoir seiche and earthquake-induced landslides, all potentially damaging to dams and reservoirs. This webinar will discuss the physics and geology of the earthquake process and the methods used to identify seis...

This webinar will address a wide range of foundation preparation and treatment methods applicable to construction of new dams, rehabilitation of existing dams, and enlargement of existing dams. Topics to be covered include: 1) treatment of surface rock exposures in dam foundations, 2) rock grouting, 3) treatment of foundation soils, 4) foundation seepage barrier walls and upstream blankets, and 5) foundation seepage collection and control methods.

Some amount of seepage passes through and under all embankment dams. The collection, monitoring, and analysis of seepage is crucial in the successful execution of any dam safety program and is helpful in deciding if it is expected ambient seepage or indicative of a more serious condition. Seepage collection methods typically include toe drains, blanket drains, and relief wells. Monitoring schemes can be grouped into several categories includi...

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 Perfo...