This webinar is a follow-up to the first in this series, Risk Assessment Basics for an Individual Dam. It is recommended that the two webinars be viewed in order if possible, and both are available in the On-Demand section of the website. Risk Management for a Portfolio of Dams explains how risk assessment is being used by some owners and regulators to improve the management of dam safety for a portfolio of dams in the context of the owner...

In 1980, Roller Compacted Concrete (RCC) was utilized to construct the Willow Creek gravity dam in Oregon. Since that time, there have been over 200 RCC projects in the United States. With applications such as gravity dams, overtopping protection, buttresses, guide walls at locks, and service spillways, RCC has proven to be a durable and economical solution to difficult engineering problems throughout the US. Internationally, RCC gravity and...

The Webinar consists of two basic parts: • A history of filter design practice including theoretical design considerations • A step-by-step design process with criterion for the design of a critical filter for one example soil type The primary topics covered in the first part of the Webinar are: 1. Early filter designs that addressed only interparticle seepage and piping. 2. The historical research performed by Sherard et al to deve...

Fluid Mechanics provides the theoretical foundation for hydraulics, which focuses on the engineering uses of fluid properties. Hydraulic topics include concepts such as pipe flow, dam design, pumps, hydropower, flow measurements, and open channel flow. The flow of water in an open channel in natural rivers is common, however, the solution to estimate water surface elevations can be a difficult problem when everything is considered, especially...

Hydrology is the study of the movement, distribution, and quality of water throughout the Earth, and thus addresses both the hydrologic cycle and water resources. A practitioner of hydrology is a hydrologist, working within the fields of earth or environmental science, physical geography or civil and environmental engineering. Broadly, hydrology is classified into two groups. The scientific hydrology is concerned mainly with the academic aspec...

Seepage models for earth dam projects require estimates for the coefficient of permeability for each zone in the cross-section. Models also require an estimate of the anisotropy of the permeability in the zone (anisotropy is the ratio of the horizontal to vertical permeability values of the permeability). Computations of drain designs require accurate estimates of the permeability of filter and drainage materials. Empirical estimates provide...

Quality control activities are important during the construction of an earth dam. The quality control program is intended to ensure that the compacted fill meets or exceeds all the specifications for the earth fill in the construction contract. The two primary specifications involve the degree of compaction and the acceptable range of water content for each zone in the compacted fill. This Webinar provides guidance on common pitfalls in the q...

Content & Objectives: The SITES computer program provides engineers with a tool for predicting the formation and progression of a headcut in an auxiliary spillway during a design storm. The predicted performance given by SITES includes the extent and speed of development of a headcut that may develop in the auxiliary spillway. The predicted erosion in the spillway depends on (1) the duration and quantity of design flow through the spillway...

This webinar will provide practical guidance on the selection of soil shear strength parameters for static slope stability analysis. Topics covered include: stress-strain behaviors of cohesionless and cohesive soils and their relationships to strength selection; drained and undrained strengths and their application in stability analysis; the differences between effective stress and total stress analysis methods; loading cases for stability ana...

This webinar will present the results of 2D and 3D numerical evaluations of seepage conditions around a developing piping defect. An updated model similar to the first 3D numerical model performed at the University of Florida beginning in about 1980 (Townsend, 1981) will be presented to illustrate the importance of 3D influences on estimated seepage gradients, seepage flows and the evaluation of potential internal erosion potential failure mod...