Your Dam Your Responsibility (PDF~1.2MB)

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Appendix B
Problem Possible Causes and
Potential Harm
Leakage in or around spillway Cause:
1. Cracks and joints in geologic
formation at spillway are
permitting seepage.
2. Gravel or sand layers at
spillway are permitting
seepage.
Seepage from crack in
concrete or structure
construction joint
Harm:
1. Could lead to excessive loss of
stored water.
2. Could lead to progressive
failure if velocities are high
enough to cause erosion of
natural materials.
Cause:
1. Water is collecting behind
structure because of
insufficient drainage or
clogged weep holes.
Harm:
1. Can cause walls to tip in
and fall over. Flows through
concrete can lead to rapid
deterioration from weathering.
2. If the spillway is located
within the embankment, rapid
erosion can lead to failure of
the dam.
3. Excessive flows under the
spillway could lead to erosion
of foundation material and
collapse of portions of the
spillway.
4. Uncontrolled flows could lead
to loss of stored water.
Action Required
Action:
1. Examine exit area to see if
type of material can explain
leakage.
2. Measure flow quantity and
check for erosion of natural
materials.
3. If flow rate or amount of
eroded materials increases
rapidly, dam water level should
be lowered until flow stabilises
or stops.
4. A suitably qualified
engineer should inspect the
condition and recommend
further actions to be taken.
5. Consider installing upstream
valve on outlet pipe.
Action:
1. Check area behind wall for
ponding of surface water.
2. Immediately measure flow
quantity and check flows for
transported drain material.
3. If flows are accelerating at
a fixed storage level, the
reservoir level should be
lowered until the flow stabilises
or stops.
4. A suitably qualified
engineer should inspect the
condition and recommend
further actions to be taken.