Your Dam Your Responsibility (PDF~1.2MB)

4 Planning to Build a Dam
4.6.2 Extreme Events
Large earthquakes, storm/flood activity and failure of upstream dams can be considered
extreme events. The risk of failure from these events is minimised by using engineering
design standards and ANCOLD Guidelines incorporating adequate margins of safety.
Emergency preparedness set up well in advance is the only available measure of reducing
the impact when a dam failure is about to happen. This is dealt with briefly in Section
8.2.
ANCOLD is the Australian National Committee on Large Dams. Information about
ANCOLD Guidelines is available at the website: www.ancold.org.au.
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4.7 Health and Safety Issues
In addition to those responsibilities covered by the Water Act, and regardless of any dam
failure, a dam owner may have liabilities to other people in common law and/or under
the Occupational Health and Safety Act (2004), depending on the circumstances.
All dams present a level of risk to persons, especially children wandering around the site
(whether entry to the site is authorised or not) and any features that may present an
unacceptable risk should be clearly identified and addressed. For example, the dam may
have a narrow crest that is capable of being driven over, or it may have steep upstream or
downstream slopes.
Warning: Any repairs to dams that are releasing or leaking water should be left to
experts as there have been a number of incidents (including death) involving persons
trying to ‘save’ the dam. Where an embankment is suffering unusual leakage or has
suffered partial failure but has not completely failed, caution should be exercised and
expert help sought. The nature of the dangers to persons trying to ‘save’ the dam may
not be visible, and may not be recognised even by those who are used to owning dams.
Water in a dam can become contaminated or polluted if not replenished or flushed.
Therefore, there is a chance that it can become a danger to those who drink it or to
downstream users, even if the initial water quality was of satisfactory quality. Sometimes
flushing is done during periods of high inflows, but this is only possible after the nature
and level of the contamination has been determined to be safe.
Maintaining a regular flow release from an outlet pipe can prevent the bottom water
becoming anaerobic often identified as a ‘rotten egg smell’ (H 2 S or hydrogen sulphide).
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