SMALL DAMS PETITS BARRAGES

Fig. 3.4 – Nix Lake dam failure in Texas, in 1989 (ASDSO, 2007).
Fig. 3.5 – Consequences of the failure of Bear Foot Lake dam, in 1994 (ASDSO, 2007)
3.3.3 Internal Erosion
Internal erosion and piping in embankments and their foundations is the second cause of
failures and accidents at embankment dams. For new dams, the potential for internal erosion
and piping can be controlled by good design and construction of the dam and provision of
filters to intercept seepage through the embankment and the foundations. However many
existing dams were not provided with filters and are susceptible to internal erosion failure, with
a likelihood increasing with ageing.
The ICOLD Bulletin on “Internal erosion of dams and their foundations” (to be completed
soon) and Feel & Fry [2] describe the four types of internal erosion:
erosion at concentrated leaks,
erosion at contacts between coarse and fine materials,
backward erosion in which erosion at the toe of structures from erosion pipes
under them,
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