Your Dam Your Responsibility (PDF~1.2MB)

Appendix B
3. Miscellaneous
Problem Possible Causes and
Potential Harm
Broken Down or Lost Rock
Beaching
Cause:
1. Poor quality beaching has
deteriorated. Wave action has
displaced beaching. Round
and similar-sized rocks have
rolled downhill.
2. Similar-sized rocks allow
waves to pass between
them and erode small gravel
particles and soil.
Harm:
1. Soil is eroded away from
behind the beaching. This
allows beaching to settle,
providing less protection and
decreased embankment width.
Wave action against these
unprotected areas decreases
embankment width.
2. Causes over-steepness of
upstream slope increasing
instability and resulting in
reduced crest width.
Ruts along Crest Cause:
1. Heavy vehicle traffic
without adequate or proper
maintenance or proper crest
surfacing.
Harm:
1. Inhibits easy access to all parts
of crest.
2. Allows continued development
of rutting. Allows standing
water to collect and saturate
crest of dam. This may initiate
localised tunnel erosion
through to the downstream
slope.
3. Loss of soil strength in
embankment.
4. Vehicles can get stuck.
Action Required
B
Action:
1. Re-establish effective slope
protection. Place bedding
material.
2. Engineer required for design
of gradation and size of rock
for bedding and beaching.
3. A suitably qualified
engineer should inspect
the dam and recommend
further actions to be taken.
Action:
1. Drain standing water from
ruts.
2. Regrade and re-compact
crest to and provide proper
drainage toward upstream
slope.
3. Provide gravel or road-base
material to accommodate
traffic.
4. Perform periodic maintenance
and regrading to prevent
reformation of low areas.
69