A Comparison of Methods for Managing Seepage through Embankment Dams

Uncontrolled seepage is a common problem associated with many existing embankment dams, resulting in high pore pressures and seepage forces that can lead to internal erosion or "piping" through the dam embankment or foundation, uplift at the dam's downstream toe, and slope instability. This paper discusses the various methods available for addressing uncontrolled seepage and mitigating the potential for internal erosion and outlines the typical process for selecting the appropriate technology. These methods can be divided into two general categories: 1) Seepage Collection and Control, and 2) Seepage Reduction. This paper describes the current construction techniques used for the various remedial methods and discusses how site conditions, including geology and foundation conditions, embankment materials and geometry, seepage characteristics, equipment access, and environmental and permitting issues, influence the selection of the appropriate methods. The conditions favoring the various methods are discussed as well as the advantages and disadvantages of each method in terms of applicability to site conditions, reliability and efficiency, constructability, construction and long-term risks, proprietary issues, environmental and permitting concerns, and relative cost.