Your Dam Your Responsibility (PDF~1.2MB)

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Appendix B
Problem Possible Causes and
Potential Harm
Cracks due to drying
(random pattern)
Cause:
1. The soil loses its moisture and
shrinks, causing cracks.
2. Note: Usually seen on crest
and downstream slope.
Harm:
1. Heavy rains can fill up cracks
soften the soil and cause small
portions of embankment
to move along internal slip
surfaces.
2. Provides points of entrance
for surface run-off, leading to
deterioration of the crest.
Slide, Slump or Slip Cause:
1. Lack of or loss of strength of
embankment material.
2. Loss of strength can be
attributed to infiltration of
water into the embankment
or loss of support by the
foundation.
3. Earth or rocks move down
the slope along a slippage
surface because they were
on too steep a slope or the
foundation moves.
Harm:
1. A slide can reduce the dam’s
seepage path. This can
accelerate the rate of seepage
and lead to loss of material.
2. A series of slides can lead to
obstruction of the outlet or
failure of the dam.
Action Required
Action:
1. Monitor cracks for increases in
width, depth, or length.
2. On crest, seal surface cracks
with a tight impervious
material.
3. Routinely grade crest to
provide proper drainage and
fill cracks.
4. Cover crest with non-plastic
(not clay) material to prevent
large moisture content
variation with respect to time.
5. A suitably qualified
engineer should inspect
the condition and
recommend further actions
to be taken.
Action:
1. Evaluate extent of the slide.
Monitor slide.
2. Draw the dam water level
down if safety of dam is
threatened.
3. A suitably qualified
engineer should inspect
the conditions and
recommend further actions
to be taken.