This webinar will provide an overview of multiple dam design and dam safety resources available from the USDA of Natural Resources Conservation Service (NRCS). The overview will include a presentation on the NRCS history of building dams and dam safety. The policy presentation will focus on key dam design and dam safety elements in the NRCS General Manual, the National Engineering Manual and NRCS directives process. The presentation on NRCS de...

Potential failure modes analyses (PFMA) was first used in dam safety over twenty years ago and although thousands of PFMA workshops have been conducted since it was first introduced, the use and application of PFMAs is still mostly limited to larger federal agencies and occasionally by others on larger projects. PFMA is a tool and a framework to evaluate dam and levee safety. It has fundamentally changed the way many now approach assessing and...

This course will provide a thorough overview of the fundamentals of specifying the fresh and hardened properties of concrete mixes; the review of applicable codes for concrete hydraulic structures; the design philosophy and methodology of reinforced concrete hydraulic structures; and issues associated with the construction process. The course will include actual design examples of frequently used hydraulic structures utilizing current design c...

Dam-related problems include blockage of fish migrations, drowning hazards, failure hazards, reservoir sedimentation, habitat loss, and tailwater erosion. Some environmental problems can only be addressed through dam removal while other issues, where removal is not a viable option, can be remediated by dam modification and nature-like fish passage. Traditional fish passage projects have typically focused solely on passage of single or few lar...

With the release of HEC-RAS 5.0 (and newer versions), the Hydrologic Engineering Center (HEC) has added the ability to perform two-dimensional (2D) hydrodynamic routing to the HEC-RAS computer model. This webinar will provide an overview of the new HEC-RAS 2D tools and solution processes and the basic capabilities of the HEC-RAS 2D model. The 2D flow modeling can be accomplished by adding 2D flow area element. This is similar to adding a stora...

The overwhelming majority of dams in the world, and also in the United States, are embankment dams. This webinar is intended as an overview of embankment dams, to serve as an introduction for those relatively new to dam safety and a refresher for the more experienced practitioner. The webinar will begin with a review of the history of embankment dams from antiquity to today and comments on today’s inventory of dams. Types of embankment d...

The most common deficiency at dams in North America is inadequate spillway capacity. Inadequate spillway capacity can result in overtopping of a dam during flood events. This is especially a concern for embankment dams where overtopping of the dam embankment can cause breaching of the dam and uncontrolled release of the impounded water. This failure mode accounts for more than 40 percent of recent dam failures. A broad overview of the many app...

The purpose of this course is to provide a brief introduction into the science of concrete arch dams. The review will touch on design methods used in the past, but primarily focus on the methods used in the current state of the practice. A historical review of construction techniques will be discussed, and how that relates to evaluations and the physical behavior of the structures. The basic loads and loading conditions used for analysis will...

This webinar will review the 2004 failure of Big Bay Dam. A potential failure modes framework was used to make the forensic root-cause assessment based on data and information provided by the State of Mississippi. A detailed timeline of the failure obtained through review of court proceedings will be presented including the appearance of a number of distress indicators, the seriousness of which were not recognized and acted upon by the Owner a...

This course is based on 50 years of NRCS experience with investigating and remediating cracked earth embankments. The presentation consists of two main sections, covering: 1) the nature of soil cracking and the associated internal erosion failure modes; and 2) how to remediate cracked earth embankments. In the first section, general information is presented on which soils are most susceptible to cracking and which pose the greatest risk for fa...