Your Dam Your Responsibility (PDF~1.2MB)

Appendix B
Problem Possible Causes and
Potential Harm
Marked change in appearance
of vegetation
Some examples of change:
• More areas of vegetation
appear to have grown.
• A given area appears darker,
lighter, larger or wetter.
• A given area appears to have
died.
Cause:
1. Embankment materials are
providing flow paths.
2. Natural seeding by wind.
3. Change in seed type during
initial post-construction
seeding.
4. Neglect of dam and lack
of proper maintenance
procedures.
Harm:
1. Can indicate a saturated area.
1. Obscures large portions of the
dam, preventing adequate,
accurate visual inspection of all
portions of the dam. Problems,
which threaten the integrity
of the dam, can develop
and remain undetected until
they progress to a point that
threatens the dam’s safety.
2. Associated root systems
develop and penetrate into the
dam’s cross-section. When the
vegetation dies, the decaying
root systems can provide paths
for seepage. This reduces the
length of the effective seepage
path through the embankment
and could lead to possible
‘piping’ situations (see Glossary
of Terms).
3. Prevents easy access to all
portions of the dam for
operation, maintenance and
inspection.
4. Provides habitat for rodents.
Action Required
B
Action:
1. Use probe and shovel to
establish if the materials in
this area are wetter than in
surrounding areas.
2. Remove all detrimental growth
from the dam, including
removal of trees, bushes, and
growth other than grass. Grass
should be encouraged on all
ports of the dam to prevent
erosion by surface run-off.
Root systems should also be
removed to the maximum
practical extent. The resulting
voids should be backfilled with
competent, well-compacted
material.
3. Cutting or spraying, as part
of an annual maintenance
program should be done to
remove further undesirable
growth.
4. All cuttings or debris resulting
from the vegetation removal
should be taken from the
dam and properly disposed of
outside the reservoir basin.
5. If area shows wetness
when surrounding areas
do not, a suitably qualified
engineer should inspect the
condition and recommend
further actions to be taken.
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