Your Dam Your Responsibility (PDF~1.2MB)

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7 Operation and Maintenance of Dams
Figure 7.1 – Common Problem Areas
7.5.2 Seepage and Leakage
Water escaping from a reservoir might appear locally (‘leakage’) or over a wide area
(‘seepage’). It might be visible on the embankment, at the downstream toe area or at the
abutments. The rate of flow might be small or large, steady or increasing, clear or muddy.
Unless the flow is clear and the rate only small and not increasing, most forms of leakage
represent the first warning of potentially serious problems and indicate the need for early
repair work. The known or suspected presence of dispersive clays in the embankment or
foundations would be signals or alarms for even greater concern.
It is important that the embankment is well maintained and grass kept relatively short (70
millimetres is good) so that seepage is readily identified if it occurs.
Appendix B lists the most commonly encountered forms of seepage and leakage, and
the means by which repairs might be made. The only common factor is that, unless the
cause is readily apparent and the repairs immediately effective, expert professional advice
should be sought.
Leakage – measurable flow of water
PHOTO COURTESY OF J WHITEWOOD